WO2025010353A2

WO2025010353A2 - Sustainable manufacture of synthetic graphite from remediated carbonaceous feedstocks

Info

Publication number: WO2025010353A2
Application number: PCT/US2024/036766
Authority: WO
Inventors: John Francis Unsworth; Pranetr PATTABHIRAMAN; Clayton AYERS; Liam BRITNELL; Benjamin KEVERNE; Timothy Blackburn
Original assignee: Arq IP Ltd
Current assignee: Arq IP Ltd
Priority date: 2023-07-06
Filing date: 2024-07-03
Publication date: 2025-01-09
Anticipated expiration: 2026-01-06
Also published as: WO2025010353A3

Abstract

A synthetic graphite having a purity level of at least 99.5%, wherein the graphite is obtainable from a purified carbonaceous product (PCP) or a solvent extract thereof, wherein the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 µm in diameter; and wherein the PCP has an ash content of less than about 8 wt%. The PCP may be derived from processing of a coal waste material comprised of coal ultrafines and/or coal microfines.

Description

SUSTAINABLE MANUFACTURE OF SYNTHETIC GRAPHITE FROM REMEDIATED CARBONACEOUS FEEDSTOCKS

FIELD OF THE INVENTION

[0001] The invention relates to compositions and methods for the manufacture of synthetic graphite.

BACKGROUND OF THE INVENTION

[0002] Graphite is a naturally occurring crystalline form of the element carbon. It consists of stacked layers of graphene and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large scale with demand currently standing at 700,000 to 800,000 metric tons (MT) annually, with the lithium-ion battery sector accounting for 200,000 MT. It is estimated that by 2030, total global demand is expected to rise substantially to 4 million MT a year, with the lithium- ion battery market consuming nearly 3 million MT. Many approaches focusing on the need to reduce fossil fuel dependence require graphite as a key component within their energy generation and storage technology solutions.

[0003] Naturally mined graphite is a finite resource, and its extraction comes with trade-offs in terms of environmental degradation as well as generation of waste and toxic by-products. The principal export sources of mined graphite are in order of tonnage: China, Mexico, Canada, Brazil, and Madagascar. Indeed, China accounts for nearly three quarters of global output of the natural mineral supply. Hence, to meet the growing demand for high purity graphite interest has shifted to manufacture of synthetic graphite from other sources of carbon.

[0004] Synthetic graphite is a unique material often used in metal fabrication and as a primary component of lithium batteries. It is composed of high-purity carbon and is known for its ability to withstand high temperatures and corrosion. Synthetic graphite is purer in terms of carbon content and tends to behave more predictably than naturally sourced graphite, which in turn contributes to its perceived value in specialty applications such as solar energy generation, electrical storage and in electric arc furnaces. However, synthetic graphite can be significantly more expensive to produce than natural graphite, as the process is energy intensive particularly if high purity graphite is needed. It is estimated that the production cost of synthetic graphite can be double or triple that for naturally mined graphite. In addition current processes for manufacturing synthetic graphite generate nearly 5 kg of carbon dioxide per kg of graphite which is more than three times higher than mining the natural mineral (Dai et al. Batteries 2019, 5(2), 48).

[0005] High purity graphite may be obtained from natural or synthetic sources using a variety of processes that vary depending on the specific source material and desired purity level. Natural sources include graphite ore or flake graphite, while synthetic carbon sources involve carbonaceous materials like petroleum coke or coal tar pitch. Whatever the carbon source typically the raw material will undergo purification steps to remove impurities and increase the carbon content. This process typically involves crushing the material and subjecting it to various physical, chemical and/or thermal treatments. The purified material is then ground into fine particles, using ball mills for example, to achieve the desired particle size distribution. The graphite particles can mixed with a binder material, such as pitch or a synthetic resin, to form a paste. This paste is then shaped and moulded into the desired product form using techniques like extrusion, isostatic pressing, or vibration moulding. The shaped graphite products are suitably subjected to a baking process, also known as carbonization, where they are heated to high temperatures in an inert atmosphere or under vacuum conditions. This step drives off volatile components and converts the binder material into a carbon matrix. The baked graphite products are further processed through a graphitization step, which involves exposing them to extremely high temperatures (over 2,000°C) often in the presence of a catalyst or by using electric resistance furnaces. This process rearranges the carbon atoms into a more ordered graphite crystal structure, resulting in improved electrical and thermal conductivity. For applications requiring ultra-high purity graphite, an additional purification step may be included. This can involve chemical or thermal treatment methods to further remove any remaining impurities and, thus, increase the purity level.

[0006] US-20230017556 (Azenkeng) describes a process that utilises chemical cleaning of coal feedstock using a cesium chloride bath to purify the carbon content. As a result of this step the ash content is actually increased so that there is a need to introduce additional chemical de-ashing steps to remove the cesium from the cleaned coal. This is followed by multiple stages of heating in order to achieve sufficient graphitization and to drive off ash components introduced via the chemical cleaning steps.

[0007] Hence, there is a need to improve the availability of high-purity synthetic graphite to meet high global demand. In addition, it is desirable to provide improved synthetic graphite of high purity utilising methods that reduce energy consumption and release of greenhouse gasses. Furthermore, it would be advantageous to provide more sustainable sources of synthetic graphite, ideally from upcycled waste materials.

[0008] These and other uses, features and advantages of the invention should be apparent to those skilled in the art from the teachings provided herein.

SUMMARY OF THE INVENTION

[0009] The invention relates to improvements in processes for the manufacture of high purity synthetic graphite from a diverse variety of feedstocks that are typically considered unsuitable for such applications due to high impurity content in the form of entrained ash. Advantageously, in specific embodiments the feedstocks may be derived from carbonaceous waste materials and/or from renewable biological sources. Further, by providing for reduction of impurity in ash content in the source feedstock to very low levels, the process of graphitization can be made far more energy efficient than was hitherto thought possible.

[0010] In a first aspect the invention provides for a synthetic graphite having a purity level of at least 99.5%, wherein the graphite is obtainable from a carbonaceous feedstock material, wherein the carbonaceous feedstock material is comprised within a purified carbonaceous product (PCP), wherein the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the PCP has an ash content of less than about 8 wt%.

[0011] In specific embodiments of the invention the PCP is obtained from a carbonaceous feedstock material selected from (a) a coal waste material comprised of coal ultrafines and/or coal microfines, and wherein the coal waste material is comprised of one or more of the group consisting of: hard coal, such as anthracite; bituminous coal; sub-bituminous coal; and brown coal, including lignite (as defined in ISO 11760:2005); (b) a microfine natural graphite; and/or (c) a biochar.

[0012] Second to fourth aspects of the invention provides for method of using a coal waste material, a biochar material or a microfine natural graphite material in a process for the manufacture of a synthetic graphite, wherein the coal waste material comprises coal ultrafines and/or coal microfines, and wherein the coal waste material is comprised of one or more of the group consisting of: hard coal, such as anthracite; bituminous coal; sub-bituminous coal; and brown coal, including lignite (as defined in ISO 11760:2005), and wherein coal waste material, biochar material or microfine natural graphite material is comprised within a purified carbonaceous product (PCP), wherein the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the PCP has an ash content of less than about 8 wt%.

[0013] In specific embodiments, the PCP is in particulate form with at least about 90% by volume (%v) of the particles being no greater than about 25 pm in diameter; and wherein the PCP has an ash content of less than about 1 wt%.

[0014] A fifth aspect of the invention provides a process for making a synthetic graphite having a purity in excess of 99.5%, the process comprising obtaining purified carbonaceous product (PCP) from a carbonaceous feedstock material, wherein the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the PCP has an ash content of less than about 8 wt%; and undertaking a graphitisation reaction on the PCP selected from one of the following:

(i) graphitising the PCP at a temperature of around 2500 to around 3000°C in an inert atmosphere; (ii) calcining the PCP at a temperature of between around 1000 and around 1200 °C in an inert atmosphere, followed by graphitisation at a temperature of around 2500 to around 3000°C in an inert atmosphere;

(iii) pyrolyzing the PCP at a temperature of between around 400 and around 1000°C in the absence of air, followed by graphitisation at a temperature of around 2500 to around 3000°C in an inert atmosphere; or

(iv) pyrolyzing the PCP at a temperature of between around 400 and around 1000°C in the absence of air, calcining at a temperature of between around 1000 and around 1200 °C in an inert atmosphere, followed by graphitisation at a temperature of around 2500 to around 3000°C in an inert atmosphere.

[0015] In specific embodiments, the PCP is in particulate form with at least about 90% by volume (%v) of the particles being no greater than about 25 pm in diameter; and wherein the PCP has an ash content of less than about 1 wt%.

[0016] A sixth aspect of the invention provides process for making a synthetic graphite having a purity in excess of 99.5%, the process comprising obtaining purified carbonaceous product (PCP) from a carbonaceous feedstock material, wherein the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the PCP has an ash content of less than about 8 wt%; blending the PCP with a graphitisation feedstock material selected from: petroleum coke, coal tar pitch, petroleum pitch or mixtures thereof, in order to produce a blended graphitisation feedstock; and undertaking a graphitisation reaction selected from one of the following:

(i) graphitising the blended graphitisation feedstock at a temperature of around 2500 to around 3000°C in an inert atmosphere;

(ii) calcining the blended graphitisation feedstock at a temperature of between around 1000 and around 1200 °C in an inert atmosphere, followed by graphitisation at a temperature of around 2500 to around 3000°C in an inert atmosphere;

(iii) pyrolyzing the blended graphitisation feedstock at a temperature of between around 400 and around 1000°C in the absence of air, followed by graphitisation at a temperature of around 2500 to around 3000°C in an inert atmosphere; or

(iv) pyrolyzing the blended graphitisation feedstock at a temperature of between around 400 and around 1000°C in the absence of air, calcining at a temperature of between around 1000 and around 1200 °C in an inert atmosphere, followed by graphitisation at a temperature of around 2500 to around 3000°C in an inert atmosphere. [0017] In specific embodiments, the PCP is in particulate form with at least about 90% by volume (%v) of the particles being no greater than about 25 pm in diameter; and wherein the PCP has an ash content of less than about 1 wt%.

[0018] In embodiments of any of the methods of the invention the carbonaceous feedstock material is comprised of one or more of the group consisting of:

(a) a coal waste material comprised of coal ultrafines and/or coal microfines, and wherein the coal waste material is comprised of one or more of the group consisting of: hard coal, such as anthracite; bituminous coal; sub-bituminous coal; and brown coal, including lignite (as defined in ISO 11760:2005);

(b) a microfine natural graphite;

(c) a biochar; and/or

(d) a PCP solvent extract.

[0019] A seventh aspect of the invention provides a synthetic graphite material having a purity in excess of 99.5% manufactured according to the processes described herein.

[0020] An eighth aspect of the invention provides a synthetic graphite having a purity level of at least 99.5%, wherein the graphite is obtainable from a coal waste material; wherein the coal waste material is comprised of coal ultrafines and/or coal microfines, and wherein the coal waste material is comprised of one or more of the group consisting of: hard coal, such as anthracite; bituminous coal; sub-bituminous coal; and brown coal, including lignite (as defined in ASTM D388-23); and wherein the coal waste material is comprised within a purified carbonaceous product (PCP), wherein the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the PCP has an ash content of less than about 8 wt%.

[0021] An anode for a lithium battery comprising the synthetic graphite material manufactured according to any of the processes described herein.

[0022] In embodiments, at least about 90%v (d90) of the PCP particles are no greater than about 25 pm in diameter, optionally no greater than about 20 pm in diameter.

[0023] In embodiments, at least about 90%v (d90) of the PCP particles are no greater than about 15 pm in diameter, optionally no greater than about 10 pm in diameter.

[0024] In embodiments, at least about 95%v (d95) of the PCP particles are no greater than about 25 pm in diameter.

[0025] In embodiments, at least about 99%v of the PCP particles are no greater than about 20 pm in diameter, suitably no greater than about 15 pm in diameter. [0026] In embodiments, at least about 80%v (d80) of the PCP particles are no greater than about 12 pm in diameter, preferably no greater than about 10 pm in diameter, suitably no greater than about 8 pm in diameter and optionally no greater than about 5 pm in diameter.

[0027] In embodiments, the average particle size of the PCP is no more than 10 pm and wherein the average particle size of the PCP is determined by laser diffraction.

[0028] In embodiments, at least about 99%v of the PCP particles have an average particle size of the PCP that is not more than 10 pm.

[0029] In embodiments, the PCP has an ash content of less than about 5 wt%, or less than about 3 wt%, or less than about 1 .5 wt%, or less than about 1 .0 wt%, or less than about 0.8 wt%, or optionally less than 0.5 wt%.

[0030] In embodiments, the PCP has a water content of less than about 5 wt%, optionally less than about 3 wt%, suitably less than about 1 wt%.

[0031] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0033] Figure 1 is a schematic of a process for making synthetic graphite of high purity according to embodiments of the present invention.

[0034] Figure 2 is schematic of a process for PCP separation techniques to be used for spheroidal graphite manufacture from a waste natural graphite feedstock according to an embodiment of the invention.

[0035] Figure 3 shows a graph representing carbon unit ordering as temperature increases.

[0036] Figure 4 shows a graph indicating the change in ash content (by % mass) at each cleaning stage for a coal waste feedstock (sample F) according to one embodiment of the invention.

[0037] Figure 5 shows an X-Ray diffractogram of a PCP sample heated to temperatures between 1250°C and 2000°C. [0038] Figure 6 shows Raman spectra of (a) graphite film for reference (b) spheroidal graphite (SPG) for reference (c) a sample of PCP-A heated to 3000°C (d) a sample of PCP-A heated to 2000°C.

[0039] Figure 7 shows Raman spectra of (a) a sample of PCP-B prior to heating (b) PCP-B heated to 2000°C for 1 hour (c) PCP-B heated to 3000°C for 1 hour.

[0040] Figure 8 shows a graph of the particle size distribution of raw graphite feedstock.

DETAILED DESCRIPTION OF THE INVENTION

[0041] All references cited herein are incorporated by reference in their entirety. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0042] Prior to setting forth the invention in greater detail, a number of definitions are provided that will assist in the understanding of the invention.

[0043] As used herein, the term "comprising" means any of the recited elements are necessarily included and other elements may optionally be included as well. "Consisting essentially of” means any recited elements are necessarily included, elements that would materially affect the basic and novel characteristics of the listed elements are excluded, and other elements may optionally be included. "Consisting of” means that all elements other than those listed are excluded. Embodiments defined by each of these terms are within the scope of this invention.

[0044] The term “coal” is used herein to denote readily combustible sedimentary mineral-derived solid hydrocarbonaceous material including, but not limited to, hard coal, such as anthracite; bituminous coal; sub-bituminous coal; and brown coal including lignite (as defined in ISO 11760:2005). “Native” or “feedstock” coal refers coal that has not been subjected to extensive processing and comprises a physical composition (e.g. maceral content) that is substantially unchanged from the point of extraction.

[0045] As used herein, the term “graphite” refers to the crystalline form of the element carbon with its atoms arranged in a hexagonal layered structure. Graphite may take the form of finely divided solid particles consisting essentially of carbon, typically, in powder or flake form. Naturally sourced may be obtained in the form of graphite flakes or as crystalline layers in metamorphic rocks such as marble, schists and gneisses. Graphite may also be found in organic-rich shales and coal beds.

[0046] As used herein, “char” or “biochar” refers to a product obtained by thermal decomposition of a biomass material (e.g., carbohydrate, cellulosic, protein-containing, and/or fat-containing material, such as wood, agricultural residue, manure, and the like) under an atmosphere that is deficient in oxygen relative to normal air, or in the absence of oxygen/air. Biochars typically are porous materials that are carbon-rich, and generally also contain various levels of inorganic salts/minerals. The thermal decomposition generally is performed at a temperature of less than about 700° C.

[0047] As used herein, the term “ash” refers to the inorganic - e.g. non-hydrocarbon - mineral component found within most types of fossil fuels such as coal, graphite ore, as well as in char or biochar. Ash that is comprised within the solid residue that remains following combustion of coal is sometimes referred to as fly ash. As the source and type of carbonaceous feedstock is highly variable, so is the composition and chemistry of the ash. However, typical ash content includes several oxides, such as carbonate, silicon dioxide, calcium oxide, iron (III) oxide and aluminium oxide, that may be present in the form of minerals such as feldspar, quartz, chalk and mica. Depending on its source, carbonaceous feedstocks such as coal, graphite ore, char or biochar may further include in trace amounts one or more substances that may be comprised within the subsequent ash, such as arsenic, beryllium, boron, cadmium, chromium, cobalt, lead, manganese, mercury, molybdenum, selenium, strontium, thallium, and vanadium. In the production of high purity graphite it is desirable to reduce the ash content of the material prior to final graphitisation steps.

[0048] The term “purified carbonaceous product” or “PCP” as used herein refers to a material that is comprised of a carbon-containing, hydrocarbonaceous or carbonaceous, substance of geological or biological origin - e.g. coal, coke, pet coke, and/or char or biochar. A PCP is typically subjected to various process steps to reduce non-carbonaceous substances that are present, such as ash or sulfur, to a minimum. Purified carbonaceous compositions comprised of purified coal are different to coals in their native or un-purified state. Likewise, carbonaceous substances may be purified from starting feedstocks of coke, pet coke, or biochar that are subjected to processes to deplete non-carbonaceous content, such as ash, sulfur, and/or water. Typically, the PCP of geological (or biological origin) according to embodiments of the present invention will comprise an ash content of less than 8 wt%, of less than 5 wt%, of less than 2 wt%, suitably of less than 1 wt%, optionally of less than 0.8 wt%, in certain cases of less than 0.5 wt%, and in specific embodiments of no more than 0.2 wt%. Conventional non-purified virgin graphite sources can have an ash content of up to 85 wt% or more which is reduced substantially via aggressive chemical processing such as hydrofluoric acid treatment. In embodiments of the present invention the PCP comprises coal derived from or obtained from waste and has an ash content lower than that of non-purified coal waste material. In specific embodiments, the PCP comprised of coal derived from or obtained from waste coal material that has an ash content in excess of 10 wt%.

[0049] As used herein, “solvent extraction” is a process in which PCP is mixed with a solvent capable of providing atomic or molecular hydrogen to the system at temperatures up to 500°C (930°F) and pressures up to 5000 psi. In this process PCP component molecules are converted to lower molecular weight compounds making them soluble. Embodiments of the invention provide for extraction to be achieved by one of the following:

(i) in the absence of hydrogen using a recycle solvent that has been previously hydrogenated; (ii) in the presence of hydrogen with a recycle solvent that has not been previously hydrogenated;

(iii) in the presence of hydrogen using a hydrogenated recycle solvent.

[0050] As used herein the term “low ash coal” refers to native coal that has a proportion of ashforming components that is lower when compared to other industry standard coals. Typically, a low ash native or feedstock coal will comprise less than around 12 wt% ash. The term “deashed coal”, or the related term “demineralised coal”, is used herein to refer to coal that has a reduced proportion of inorganic minerals compared to its natural native state. Ash content may be determined by proximate analysis of a coal composition as described in ASTM D3174 - 12 Standard Test Method for Ash in the Analysis Sample of Coal and Coke from Coal.

[0051] Inferior coal is a term used in geological survey of the quality of coal seams (e.g. UK coal survey, 1937) and refers to intrinsic ash in coal bands or coal seams above 15.1 wt% and below 40.0 wt%. Coal bands or coal seams consisting of inferior coal contain mineral matter intimately mixed within the coal itself and consequently are very difficult to purify using conventional coal processing techniques. The methods described in embodiments of the invention allow for the use of inferior coal, particularly waste or spoil that comprises inferior coal, to be utilised as a feedstock for the production of carbon black substitutes.

[0052] ASTM coal classification system (ASTM D388-23) defines coal types according to fixed carbon on a dry, mineral-matter- free basis (dmmf) and/or moist calorific value. Volatile matter (VM, dmmf) is calculated as 100 - fixed carbon (dmmf) and is more often used in practice to differentiate coals of different rank.

• Anthracite: 2%m - 8%m VM(dmmf)

• Semi-anthracite: 8%m - 14%m VM(dmmf)

• Low-volatile bituminous coals: 14%m - 22%m VM(dmmf)

• Medium-volatile bituminous coals: 22%m - 31 %m VM(dmmf)

• High volatile bituminous coals, Sub-bituminous coals and Lignites: >31 %m VM(dmmf), but distinguished by their calorific value at their natural bed moisture; i.e. as mined but free from any moisture on the surface of the lumps.

[0053] As used herein, the term “coal fines” refers to coal in particulate form with a maximum particle size typically less than 1.0mm. The term “coal ultrafines” or “ultrafine coal” or “ultrafines” refers to coal with a maximum particle size typically less than 0.5mm (500 microns (pm), approximately 0.02 inches). The term “coal microfines” or “microfine coal” or “microfines” refers to coal with a maximum particle size typically less than 20pm.

[0054] Most suitably the particle size of the carbonaceous material (e.g. PCP) that is utilized as feedstock in the presently described processes may be at most 1000pm or 500 pm. Specifically, the maximum average particle size may be at most 500pm. More suitably, the maximum average particle size may be at most 300pm, 250pm, 200pm, 150pm, or 100pm. Most suitably, the maximum average particle size may be at most 75pm, 50pm, 40pm, 30pm, 20pm, 10pm, or 5pm. The minimum average particle size may be 0.01 pm, 0.1 pm, 0.5pm, 1 pm, 2pm, or 5pm. Hence, in particular embodiments the invention includes utilisation of nanoscale fines with average particle sizes in the sub-micron range.

[0055] An alternative measure of particle size is to quote a maximum particle size and a percentage value or “d” value for the proportion by volume of particles within the sample or composition that fall below that particle size. For the present invention, any particle size of PCP that is suitable for use as a feedstock or as an additive for blending with other feedstock materials is considered to be encompassed by the invention. Suitably, the particle size of the PCP is in the ultrafine range. Most suitably the particle size of the PCP is in the microfine range. Specifically, the maximum particle size may be at most 500 pm. More suitably, the maximum particle size may be at most 300 pm, 250 pm, 200 pm, 150 pm, or 100 pm. Most suitably, the maximum particle size may be at most 75 pm, 50 pm, 40 pm, 30 pm, 25 pm, 20 pm, 15 pm, 10 pm, or 5 pm. The minimum particle size may be 0.01 pm, 0.1 pm, 0.5 pm, 1 pm, 2 pm, or 5 pm. Any “d” value may be associated with any one of these particle sizes. Suitably, the “d” value associated with any of the above maximum particle sizes may be d99, d98, d95, d90, d80, d70, d60, or d50. A d value may also, or additionally, represent a mass division diameter; the diameter which, when all particles in a sample or composition are arranged in order of ascending mass, thereby dividing the mass into specified percentages. The percentage mass of a composition below the diameter of interest is the number expressed after the "d". Hence, a d90 of 10 pm can indicate that 90 percent of the mass of the composition is comprised within particles of less than 10 pm in diameter. To maximize the conversion of PCP into high purity synthetic graphite it is desirable for the particle size to be both relatively homogeneous and small. For instance, in a specific embodiment of the invention the PCP has a d90 or higher of <100 pm, <90 pm, <70 pm, <50 pm, <25 pm, optionally <20 pm, suitably <10 pm. In some embodiments of the invention, the PCP has a d99 of <70 pm, <60 pm, <50 pm, <40 pm, <25 pm, optionally <20 pm, suitably <10 pm.

[0056] Particle size can be characterized by a number of different techniques (laser diffraction, dynamic light scattering, electrophoretic light scattering, automated imaging, sedimentation, etc.) which do not always correspond exactly. In a specific embodiment of the invention, laser diffraction techniques are employed to measure particle size distributions and to specify particle size parameters.

[0057] In embodiments of the present invention the particles of the PCP may have a planar, flattened or plate/disc-like morphology similar to that observed in waste graphite microfine particles. Typically, planar morphologies are seen in PCP derived from coal feedstocks and in such embodiments, the reference to a maximum or average particle size as mentioned above refers to the maximum diameter of the particle, that is the diameter of the planar surface of the PCP particle. [0058] As used herein, the term “water content” refers to the total amount of water within a sample of PCP and is expressed as a concentration or as a mass or weight percentage (wt% or wt%). When the term refers to the water content in a PCP obtained from a coal sample it includes the inherent or residual water content of the coal, and any water or moisture that has been absorbed from the environment. As used herein the term “dewatered coal” refers to coal that has an absolute proportion of water that is lower than that of its natural state. The term “dewatered coal” may also be used to refer to coal that has a low, naturally occurring proportion of water. Water content may be determined by analysis of a native or purified coal composition as described in ASTM D3302 / D3302M - 17 Standard Test Method for Total Moisture in Coal. Water content may also apply to the inherent level of moisture present in products comprised of PCP, such as pellets or granules that comprise PCP as a minority or majority constituent.

[0059] Demineralising and dewatering of carbonaceous feedstocks, such as coal fines, graphite ore or char/biochar, most suitably from waste or discard sources, to produce a PCP may be achieved via a combination of froth flotation separation, specifically designed for ultrafines and microfine particles, plus mechanical and thermal dewatering techniques. Typically, PCP may be produced from a particulate carbon-containing feedstock via processes that comprise particle size reduction, mineral matter removal, dewatering and drying. Some or all of these steps may be altered or modified to suit the specification of the starting material or of the desired end product. The key process steps are summarised below in relation to a typical waste coal starting material derived from an impoundment, tailings pond or production tailings underflow. It should be noted that the inventors have found that in order to achieve high-purity graphite it is desirable to reduce ash content in the carbon containing feedstock to levels <8 wt%, <5 wt%, <2 wt%, more suitably < 1 wt% which is achievable via the processes described herein. Hitherto, froth flotation techniques when applied particularly to graphite ore have rarely produced ash content levels below 3 wt%.

Particle size reduction

[0060] The starting carbonaceous material feedstock is reduced to a particle size of d80=30-50 microns (or finer in some coals or graphite ores) to achieve efficient separation to a target mineral matter (ash) content of 7-10 wt%. To achieve this, a feed comprising the starting material is diluted with water to achieve a solids content of in the range 20-40 wt%, then ground in a ball or bead mill depending on the top size of the feedstock. The product is screened at a size range of approximately 100 microns to exclude particles above this size. Suitable equipment for size reduction is manufactured by Metso Corporation, Fabianinkatu 9 A, PO Box 1220, Fl-00130 Helsinki, FIN-00101 , Finland; Glencore Technology Pty. Ltd., Level 10, 160 Ann St, Brisbane QLD 4000, Australia, and FLSmidth, Vigerslev Alle 77, 2500 Valby, Denmark.

Ash removal

[0061] One or a series of froth flotation stages are carried out to bring the entrained mineral content down to the target level. For some coals where the mineral matter is disseminated mainly within sub- 10-micron size domains, more than one stage of flotation following further milling may be required to achieve a low ash level.

[0062] During froth flotation a coal slurry is diluted further with water typically to a range of 2-20 wt% solids then collected in a tank and froth flotation agents, known as frother (e.g. methyl iso-butyl carbinol dipropyleneglycol monomethyl ether or pine oil) and collector (e.g. diesel fuel, kerosene, cyclohexane, or other hydrocarbon oil, bio-diesel or other fatty acid methyl ester, or flotation reagent Nalco 8836 plus from Ecolab, Naperville, IL, USA), are added using controlled dose rates. Micro particle separators (e.g. Flotation test machines manufactured by Eriez Manufacturing Co., 2200 Asbury Road, Erie, Pa. 16505, USA, by FLSmidth, Vigerslev Alle 77, 2500 Valby, Denmark, by Metso Corporation, Fabianinkatu 9 A, PO Box 1220, Fl-00130 Helsinki, Finland, and GTEK Mineral Technologies Co. Ltd.) filled with process water and filtered air from an enclosed air compressor are used to sort hydrophobic carbon materials from hydrophilic mineral materials. Froth containing hydro-carbonaceous particles overflows the tank and this froth is collected in an open, top gutter. The mineral pulp is retained in the separation tank until discharged, whereas the demineralised coal slurry is de-aerated, before being subjected to additional processing. After each flotation stage a series of cyclones are used to selectively remove excess water and any oversized particles prior to the next stage of milling. After the final milling stage, decanter centrifuges are incorporated into the process design to remove 10 micron over-sized particles. Suitable equipment is manufactured by Alfa Laval Corporate AB, Rudeboksvagen 1 , SE-226 55 Lund, Sweden.

Dewatering

[0063] The concentrate from froth flotation is dewatered with a filter-press or tube-press to a target range of 20-50wt% depending on the actual particle size, under pressure or vacuum, sometimes with air-blowing, to remove water by mechanical means, in order to generate feed for the extruder. Suitable filter-press equipment is manufactured by Metso, Fl-00130 Helsinki, Finland, FLSmidth, Valby, Denmark, and by Outotec. Rauhalanpuisto 9, 02230 Espoo, Finland.

[0064] In some instances, flocculant (or thickener, e.g. anionic and cationic polyacrylamide additives manufactured by Nalco Champion, 1 Ecolab Place, St. Paul, MN 55102-2233, USA) is added to optimise both settling properties of PCP and inorganic waste and underflow density. To optimise the procedure settling tests are carried out to measure settling rates and generate a settling curve, tracking underflow density with time. Filtration may also be necessary depending on the filtration rate and resultant cake moisture. To optimise the procedure feed % solids (thickened / un-thickened), feed viscosity, pH and filtration pressure will be measured, Filter cloths are chosen after assessment of cake discharge and blinding performance. Suitable filter cloths are manufactured by Clear Edge Filtration, 11607 E 43rd Street North, Tulsa, Oklahoma 74116 USA. Drying

[0065] The PCP product may be dried thermally to reduce water to below 40 wt%, below 20 wt%, below 5 wt%, suitably below 2 wt% and in specific embodiments less than 1 wt%, less than 0.8 wt%, or less than 0.5 wt%. This may be achieved directly on the PCP, or by pelleting or granulating it first to facilitate handling, by conveying it to a belt dryer where oxygen-deprived hot process air is blown directly over the microfine coal. Suitable equipment is manufactured by STELA Laxhuber GmbH, Ottingerstr. 2, D-84323 Massing, Germany or by GEA Group Aktiengesellschaft, Peter-Muller-Str. 12, 40468 Dusseldorf, Germany; drying in a ring drier in a reduced oxygen or inert environment may be carried out in driers made by Dedert (17740 Hoffman Way, Homewood, Illinois 60430, USA), GEA (Peter- Muller-Str. 12, 40468 Dusseldorf, Germany), or Swedish Exergy (Gamla Rambergsvagen 34 SE-417 10, Gothenburg, Sweden); drying in a rotary drier system, indirectly heated with natural gas burners on a shroud in contact with the inner shell, such as those made by Mitchell Dryers (Mitchell Dryers (Kingmoor) Ltd, Unit B, Kings Drive, Kingmoor Park South, Carlisle CA6 4RD,UK) or the helical screwtype rotary drier, with hollow flights that use oil or steam as thermal fluids, such as those made by Komline-Sanderson (Komline-Sanderson, 12 Holland Avenue, PO Box 257, Peapack, NJ 07977 USA).

[0066] In specific embodiments, PCP derived from coal is characterised has having particles that adopt a flattened disc or plate-shaped morphology. This unique morphology is distinct from conventional particles of virgin coal which tend to be more irregular agglomerates having a substantially globular morphology. Without wishing to be bound by theory, it is believed that improved dispersion characteristics in coal tar or petroleum pitch may be associated with such flattened disc or plate-shaped morphology. In addition, graphitic crystallinity may be improved, at least in part, by the enhanced orientation from the flattened disc-shaped morphology of coal-derived or graphite -ore derived PCP particles.

[0067] PCP material can be utilised in the manufacture of high purity synthetic graphite via several routes. As shown in Figure 1 , the PCP feedstock may be used as a lone feedstock that is subjected to various thermal treatments - e.g. pyrolysis, baking and/or graphitisation. Alternatively, a PCP may be used as an additive that is blended with more conventional synthetic graphite feedstocks such as petroleum coke, coal-tar, and/or petroleum pitch prior to thermal treatment - e.g. pyrolysis, baking and/or graphitisation. In relation to the schematic shown in Figure 1 , the various synthetic routes to a high purity graphite product are summarised below:

A. Graphitise PCP at 3000°C in an inert atmosphere.

B. Calcine (bake or sinter) at 1000-1200°C in absence of air with or without pitch impregnation, followed by graphitisation at 3000°C in an inert atmosphere.

C. Pyrolyse at 400-1000°C to a char in absence of air, followed by graphitisation at 3000°C in an inert atmosphere.

D. Pyrolyse at 400-1000°C to a char in absence of air, followed by calcination at 1000-1200°C in absence of air with or without pitch impregnation, followed by graphitisation at 3000°C in an inert atmosphere. E. Blend with milled petroleum coke or coal tar pitch or petroleum pitch or a mixture of coal tar pitch, petroleum pitch and petroleum coke prior to baking, followed by:

1. graphitisation at 3000°C in an inert atmosphere

2. calcination at 1000-1200°C in absence of air, with or without pitch impregnation, followed by graphitisation at 3000°C in an inert atmosphere.

3. pyrolysis at 400-1000°C in absence of air, followed by graphitisation at 3000°C in an inert atmosphere.

4. pyrolysis at 400-1000°C in absence of air, followed by calcination at 1000-1200°C in absence of air with or without pitch impregnation, followed by graphitisation at 3000°C in an inert atmosphere.

[0068] In relation to the above processes, pyrolysis entails the thermal decomposition of an organic containing substrate that occurs at high temperatures (400°C - 1000°C) in the absence of an oxidizing atmosphere. In contrast, a step of calcination/baking/sintering incorporates a firing at a temperature lower than the final firing temperature usually for the purpose of homogenizing the composition of the feedstock material - e.g. to decompose a variety of impurity compounds that contribute to the ash content. Finally, graphitization is the final thermal stage of firing to high temperatures in excess of 1000°C and more typically in excess of 2000°C in an oxygen free atmosphere that allows for the rearrangement of carbon atoms within the carbonaceous material and, thus, the formation of graphite.

[0069] Figure 3 illustrates diagrammatically the changing structure of the aromatic carbon units within carbonaceous raw materials, such as anthracites and bituminous coals, as they are progressively heated in the absence of air through four temperature zones.

1. <800°C: semi-coke (char) containing small highly aromatic units with some local ordering of the plate-like molecules,

2. 800-1 ,500°C: coke with larger units of aligned carbon plates,

3. 1 , 500-2, 000°C: calcination where units of aligned carbon plates merge horizontally and vertically,

4. 2,000-3,000°C: graphitisation where the carbon aligns in parallel plates.

[0070] In embodiments of the present invention the graphitising occurs over a time period of at least 1 minute, at least 1 hour, at least 12 hours or at least 24 hours; and/or the calcining occurs over a time period of at least 1 hour, at least 6 hours, at least 12 hours, or least 24 hours; and/or the pyrolysis occurs over a time period of at least 1 hour, at least 3 hours, at least 6 hours, or least 12 hours.

[0071] The techniques typically used to measure the development of graphite crystallinity are Electron Microscopy, X-Ray Diffraction (XRD) and Raman spectroscopy techniques. Prior art studies on anthracites, bituminous coals and lignite used samples with as much as 3%m - 8%m ash content and pay little or no attention to the level of inorganic impurity present. However, impurities are known to affect the final stages of graphitisation and the ability to achieve high spheroidal graphite carbon purity specifications of 99.95 wt%. Microstructural characterisation by scanning electron microscopy and XRD (Qiu, T., Yang, J-G. & Bai, X-J., Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 42:15, 1874-1881 , 2019) of for different ranks of coals showed carbon microstructures ranging from sub-micron sized plates (semi-anthracite) to spherical particles (low- volatile bituminous coal) to rod-like structure (lignite). These samples had to be chemically “demineralised” with 40% hydrofluoric and 40% hydrochloric strong acids, although even after this step their residual ash content remained relatively high at 3 - 8 wt%. XRD spectra showed characteristic graphite peaks 002 and 100 (representing aromatic layer orientation and degree of condensation of aromatic rings) for semi-anthracite which were much smaller and broader for the low-volatile bituminous coal and the lignite. Another sample with 7%m ash content was studied by both XRD and Raman spectra to show progressive increase in degree of graphitisation with increasing temperature between 2000°C and 2800°C for a Chinese low-volatile bituminous coal (Xing, B., Zhang, C., Cao, Y., Huang, G., Liu, Q., Zhang, C., Chen, Z., Yia, G., Chen, L. & Yuc, J., Fuel Processing Technology 172 (2018) 162-171).

[0072] In embodiments, purified biochar derived from biomass, such as waste wood, can similarly be incorporated into graphite via mechanisms D and E2-E4, as shown in Figure 1 , post charring. Whilst, synthetic graphite has been produced from various biochar sources in the art, biochars derived from wood wastes, crop residues, animal waste and industrial bio-sludges are known have ash contents that range from 3.0 wt% up to 75 wt%. Due to the biological nature of their origin, biochar ash content can vary considerably on a batch-to-batch basis and from growing season to growing season. Hence, prior art efforts to reduce ash tend to focus on extending the energy intensive pyrolysis and calcining stages, as well as chemical treatment with strong acids. This reduces the environmental benefits of utilising biochar as a feedstock as well as limiting its use in very high purity applications.

[0073] In further embodiments of the invention, PCP separation approaches as described above may be used to isolate sub-20 pm particles for demineralization of natural graphite waste or amorphous graphite. Figure 2, shows an embodiment of a process of the invention as a source for spheroidal graphite. This process avoids the costly and environmentally polluting strong acid-leaching stages described previously (e.g. using concentrated mixtures of hydrofluoric, sulphuric, nitric and hydrochloric acids). This purification stage could be combined with a further graphitisation stage to grow graphite crystallite size for SPG. According to this embodiment, natural graphite either waste or raw material is subjected to one or a series of froth flotation stages carried out to bring entrained mineral content down to a target level of less than 2 wt%, optionally less than 1 wt%, and typically a particle size distribution of a d90 of less than about 20 microns. Surprisingly, it has been found that this allows for production of high purity lithium ion battery grade graphite without the need for strong acid demineralisation steps.

[0074] In a further embodiment a solvent extract of PCP can further reduce ash content approximately ten-fold more and be in incorporated into graphite via routes A, B and E1-E4 shown in Figure 1 and described above. Although solvent extraction requires additional processing because of its high temperature and high-pressure requirements, this route to production of such a highly valuable synthetic graphite feedstock with sub-1000 ppm of inorganic impurities proves to be surprisingly economic, especially for manufacturing synthetic graphite of the highest possible quality.

[0075] The synthetic graphite of the present invention suitably has a very high purity with embodiments having a carbon content of at least 99.5 wt%, in excess of 99.75 wt%, in excess of 99.85 wt%, in excess of 99.90 wt%, in excess of 99.95 wt%, and even around 99.99 wt% or more. This is surprising given that the starting material feedstocks may include discard, mining or agricultural/forestry production waste and other carbonaceous materials that are conventionally considered unsuitable for manufacture of such specialty products. Further, the processes described herein do not require the use of environmentally and potentially unsafe chemical treatments including the use of strong acids to enhance the degradation of ash contaminants. Ash components extracted by the processes described are not necessarily destined for discard and may be used as soil improvers, as clinker in the cement industry or as a filler in polymer/elastomer production. This in turn reduces greenhouse gas emissions further by mitigating the need to burn off ash components during calcination.

[0076] The synthetic graphite obtainable by the processes of the present invention exhibits surprisingly high electrical conductivity and good chemical stability, with high mechanical strength and high thermal conductivity inferred from structural characterization data, rendering it ideal for various applications. The properties of the high purity synthetic graphite enable its utilization in the production of advanced lithium-ion batteries, where it serves as a superior anode material, providing enhanced energy storage capacity and prolonged battery life. Furthermore, the synthetic graphite finds application in aerospace and automotive industries for the development of lightweight and durable composite materials, ensuring optimal performance and fuel efficiency. Additionally, it may be utilized in the manufacturing of crucibles and electrodes employed in metallurgical and electrical applications, owing to its excellent heat resistance and electrical conductivity.

[0077] The invention is further illustrated by the following non-limiting examples.

EXAMPLES

Example 1. Preparation of very low ash (<1.5%) content PCP samples

[0078] A methodology for purifying coal waste to produce material that contains >99%m organic, <1 %m inorganic material was developed based initially on a knowledge of the distribution of mineral matter in coals obtained by reflection optical microscopy as used in coal petrographic techniques.

[0079] Coal wastes from 24 different locations have been collected and separated using the procedure below to yield PCP with an ash content < 1.5%m. These locations cover a range of geographical and geological origin: Eastern USA (Carboniferous), Western USA (Cretaceous), Australia (Permian) and South Africa (Permian), and Colombia (Paleocene). [0080] The waste sources tested range from

• Tailings ponds (or coal impoundments), both active and historical,

• underflow, process rejects from current coal cleaning, that will be added subsequently to an active tailings pond,

• surrogate samples for waste coal, e.g. clean coals or run of mine seam coal sampled in situ,

• fines screened from commercial washed coal as rejects.

[0081] In some locations, where waste streams were not available, clean coals (i.e. processed run- of-mine coal for commercial use), have been tested as surrogates to assess the potential of associated tailings or underflow. To test the validity of this assumption we tested four pairs of locations where clean coal and underflow samples were available. Closely similar stage 3 ash contents were obtained in each case, Table 1 : In two cases the underflow had a lower stage 3 ash content (samples V & W), in the third (sample S), the values were the same for underflow and clean coal.

[0082] Table 1. Stage 3 ash contents for clean coal and underflow samples from three locations

[0083] The sample of the coal waste source, as received, was weighed, screened at 1.7 mm and oversize crushed until all material passes 1.7 mm screen. The sub-1.7 mm sample was split into subsamples before grinding to d80=40pm (d100=100pm) in a 1 kW Stirred Media Detritor (SMD from Metso Corporation, Helsinki, Finland) using 6mm diameter ceramic media (Kings Beads, Beijing, China). A particle size distribution (psd) was determined both before and after the SMD grind, and an ash content determined after the SMD grind.

[0084] All particle size distributions were determined by laser diffraction in a Mastersizer 3000 (from Malvern Panalytical, Malvern, UK), and ash contents by ASTM D3174 Standard Test Method for Ash in the Analysis Sample of Coal and Coke from Coal.

[0085] Stage 1: 215g of the SMD ground sample was diluted to a solids concentration of 5%m in water and introduced into a 5 litre float cell. A few drops of Methyl Isobutyl Carbinol (MIBC) were added as a frother and the cell placed in a FTM101 flotation machine (FLSmidth Pty Ltd, Welshpool, WA Australia) Using an air flow rate of 15-20 litres/min the froth was separated off, while adding water to the float cell to maintain the pulp level. Froth recovery was continued until the froth contains no visible black particles. The recovered wet froth (concentrate 1) was weighed to calculate the % solids and the water recovery, and a sample of froth concentrate 1 was filtered, dried in an oven at 60°C, and the ash content measured. Concentrate 1 was re-introduced into the flotation cell and the procedure repeated twice more to yield froth concentrates 2 and 3. Filtration may be needed at each step to reduce the volume to 5 litres, the capacity of the float cell.

[0086] Stage 2: Froth concentrate 3 was passed through a pressure filter, concentrated to a volume of 700 ml and ground in the SMD to d80=10pm, except that 2 mm ceramic media was used. As before a psd was determined both before and after this grind, and an ash content determined after the grind. The Stage 1 flotation procedure above was then repeated for stage 2 and samples of froth concentrates 4-6 were filtered, dried in an oven at 60°C, weighed to calculate mass and coal recovery, and ash content measured.

[0087] Stage 3: Froth concentrate 6 was passed through a pressure filter, concentrated to a volume of 700 ml and ground in the SMD to d80=5pm, except that 1 mm ceramic media was used this time. As before a psd was determined both before and after this grind, and an ash content determined after the grind. The Stage 1 flotation procedure above was then repeated eight more times for stage 3 and samples of froth concentrate 7-15 filtered, dried in an oven at 60°C, weighed to calculate mass and coal recovery, and ash content measured.

[0088] Figure 4 illustrates the change in ash content at each cleaning stage for sample F, thus in Stage 1 (the first 3 cleaning stages) the ash content is reduced from 45.0%m in the feed to 13.58% through concentrate 1 (rougher) at 34.3%m and concentrate 2 at 23.3%m. The three concentrate stages in stage 2 reduce ash content progressively to 3.1 %m, and the final 9 concentrates in stage 3 reduce ash content gradually to 0.59%m. The objective of the rougher stage is to remove the maximum amount of inorganic material at as coarse a particle size as possible to minimum grinding energy.

[0089] Table 2 summarises the results of the separation procedure for a range of different coal waste sources and surrogate samples. Samples from 24 different sites have been tested using the flotation procedure described above, and ash contents given for the feedstock, stage 1 , stage 2 and stage 3 products. Yields in terms of both overall mass and coal content are also given. These experiments were carried out at Grinding Solutions Ltd., Truro, UK with the exception of PCP-R which was carried out by Michael Young at Core Resources, Albion, Queensland, Australia.

[0090] Table 2. Summary of the results of the separation procedure for 24 different coal waste sources

Notes: n.d. not determined, n.a. not available, * based on 100 - ash content of originating waste sample

[0091] Table 2 summarises the results of the separation procedure for a range of different coal waste sources and surrogate samples. Samples from 24 different sites have been tested using the flotation procedure described above, and ash contents given for the feedstock, stage 1 , stage 2 and stage 3 products. Yields in terms of both overall mass and coal content are also given.

[0092] Three waste samples came from Australia, two from South Africa, one from Colombia, and the remainder from the USA. Most of these samples were derived from various types of high volatile bituminous coals, except for PCP-E (a medium volatile bituminous coal) and PCP-R (a low volatile bituminous coal). The carbon content of the samples ranged from 78%m (PCP-O) to 86. %m (PCP-R) and vitrinite maximum reflectance from 0.54%(PCP-C) to 1.03% (PCP-R).

[0093] PCP samples with ash content <0.5% were prepared from 4 sites, and 7 sites yielded PCP between 0.5 and 1 ,0%m. Additionally, PCP with ash content between 1 ,0%m and 1 ,4%m were prepared from tailings or underflow at 13 further sites. These are exceptionally pure carbonaceous materials, the more so as they are derived from waste coal in which mineral matter is inherently difficult to separate from organic material - one of the main reasons for discarding at the mine or processing plant in the first place. Typical ash contents of commercial coals are above 5%m ash content and more typically >10%m or >15%m.

[0094] Not only are very low ash contents achieved, but at a remarkably high yield of organic material above 70%m from most of the tailings and underflow samples. Only two samples were below 70%m (PCP-F and PCP-S1).

Example 2. Impact on graphite crystallinity of heating a PCP to temperatures between 1250°C and 2000°C

[0095] Dry PCP-A was heated in graphite crucibles (10 mm diameter and 50 mm deep) within a high temperature furnace with resistance heating (FCT Systeme GmBH, Frankenblick, Germany) up to temperatures between 1250 °C and 2000 °C under an argon atmosphere (+20 mbar relative pressure) at Graphene Engineering Innovation Centre (GEIC), Manchester, UK, where X-ray diffractograms and Raman spectra were also carried out.

[0096] The results are shown in Figure 5 as X-ray diffractrograms, where the 002 peak is attributed to orientation of aromatic ring carbon reticulated laminates in graphite. The narrower and higher the 002 peak, the better the aromatic layer slice orientation. In Figure 5 the sharpness of 002 peak increases in order: 1250°C < 1750°C < 2000°C. The 100 peak is attributed to the degree of condensation of aromatic rings; the narrower and higher the 100 peak the larger the size of the aromatic layer slice. In Figure 5 the height and sharpness of the 100 peak increases in the order: 1250°C < 1750°C < 2000°C.

[0097] Thus, the distinctive diffraction peaks (002 and 100 representing aromatic layer orientation and degree of condensation of aromatic rings respectively) present in synthetic and spherical graphite are progressively developing as PCP-A is heated from 1250°C through 1750°C to 2000°C.

Example 3. Graphitization of PCP to 3000°C and its impact on inorganic impurities

[0098] This is an example of pathway A from PCP to synthetic graphite as illustrated in Figure 1 .

[0099] Dry PCP-A was graphitized in an RDC-201 furnace by the manufacturers (R&D Carbon Ltd., Granges, Switzerland) to maximum temperatures of 2500°C and 3000°C without further soaking time. Cooling commenced as soon as 3000°C was reached. . The design of this furnace is based on a full- scale horizontal graphitization furnace and consists of a core with a diameter of 50 mm and a total length of 470 mm clamped between two graphite electrodes under a specific pressure. The temperature rise of approximately 500°C/hour is automatically controlled by the regulation of the electrical current flowing through the column of samples.

[00100] The loss in weight during graphitization was recorded. Ash content (ISO 8005) and elemental analysis for 10 key elements was carried out by X-Ray Fluorescence (ISO 12980) on the starting PCP powder and the two graphitized samples, Table 3.

[00101] Table 3. Analyses of PCP-A graphitized to 2500°C and 3000°C

Note: n.a. = not applicable

[00102] The reduction in ash content from 1 .09% in PCP-A to 0.47% after heating to 2500°C and to 0.26%m after 3000°C (without further soaking at 3000°C) represents a considerable change (reduction in ash content of 76.2%m) due to vaporisation of inorganic elements. All the more so, when considering the loss in graphitization of 41 .6% in mass of the 3000°C graphite, which would have increased the effective ash content to 1.87%m [100*1.09/(100-41.6)], if no vaporisation of inorganic elements had occurred. Thus, the ash content of PCP-A is actually reduced by 86% [100*(1.87-0.26)/1.87] as a result of heating to 3000°C with immediate cooling.

[00103] As a result of optimisation of the purity of organic feedstock for graphitization processes, the residence time at these extremely high temperatures required to vaporize trace inorganic species is reduced with concomitant energy savings. Improved methods to reduce the energy requirement for graphitisation are an important part of the pursuit for economic manufacturing of SG and SPG. Currently, techniques such as microwave heating (Kim, T., Lee, J. & Lee, K-H., Full graphitization of amorphous carbon by microwave heating, RSC Advances 2016, 6, 24667), electrothermal fluidized bed technology (Sybir, A.V., Hubynskyi, M.V., Balalaiev, O.K., Burchak, O.V., Sukhyy, K.M., Fedorov, S.S., Pinchuk, V.O., Hubynskyi, S.M., & Vvedenska, T.Y., Effect of parameters of the anthracite heat treatment on the properties of carbon materials during shock heating, Voprosy khimii i khimicheskoi tekhnologii, 2022 (5), 94) and laser pulse heating (Gallais, L., Vidal, T., Lescoute, E., Pontillon, Y. & Rullier, J.L., High power continuous wave laser heating of graphite in a high temperature range up to 3800 K, Journal of Applied Physics 129, 043102 (2021)) may be used to replace the high energy Acheson furnace process currently employed in the art.

[00104] Typical ranges of values for inorganic element concentrations acceptable in Li-battery anodes with high graphitizability are shown in parentheses in the 3000°C column in Table 3. Of the nine elements considered, six, i.e. sulphur, silicon, iron aluminium, calcium and phosphorus, are already below the purity limits. Vanadium, nickel and sodium levels are higher, but nevertheless very close to the purity requirements. It is reasonable to predict that by extending heating at 3000°C for longer all nine elemental purity limits would be achievable.

[00105] Assuming that the reduction in ash content of 76.2% is typical of the increase in purity from graphitization at 3000°C without soaking, then 99.9% purity should be achievable from a feed PCP ash content of 0.42%m (i.e. 100x(100-99.9)/100-76.2). Similarly the PCP ash content to achieve 99.5% fixed carbon purity (i.e. 2.1 %m ash), and 99.95% fixed carbon purity (0.21 %m ash) can be calculated, Table 4.

[00106] Example 1 illustrates how PCPs ranging from 0.24%m to 1.37%m ash content have been prepared. Without further soaking at 3000°C, these PCPs could yield graphite of carbon purity ranging from very close to 99.95%m (99.943%m for PCP-B) to well above 99.5%m (99.67%m for PCP-X). [00107] Table 4. Fixed carbon purities of PCP graphites calculated for different PCP ash contents

Example 4. Graphitic structure determined by Raman spectra and other properties of PCP graphitized to 3000°C

[00108] For Raman Spectroscopy, the heated PCP-A and PCP-B samples were deposited on double-sided tape on a glass slide. Raman spectroscopic maps were taken on a Renishaw InVia at 532 nm laser with 60 pm x 60 pm square and 3 pm step at GEIC, Manchester, UK.

[00109] The Raman G band is a characteristic of the number of graphene layers. The 2D band is also used to determine graphene layer thickness. The D band reflects disorder (or defects) present and is typically very weak in graphite and in high quality graphene.

[00110] Figure 6 shows Raman spectra of (a) graphite film (b) spheroidal graphite (c) PCP-A heated to 3000°C (d) PCP-A heated to 2000°C.

(a) The graphite film shows just the two pronounced characteristic graphene layer peaks (G band and 2D band).

(b) The spheroidal graphite - this also shows G and 2D bands, but also present is a small D peak reflecting some crystalline disorder.

(c) PCP-A heated to 3000°C - this shows Raman G and 2D bands as in (a) and (b), but the D band is more pronounced than in (b) indicating a greater level of crystalline disorder.

(d) PCP-A heated to 2000°C - this spectrum is noisier, containing broader peaks, nevertheless both graphene layer G and 2D bands are present.

(e) The intensity of the D band is directly proportional to the level of defects in the sample. The level of defects increases in the order graphite film < spheroidal graphite < PCP-A @ 3000°C < PCP-A @ 2000°C. [00111] Figure 7 shows Raman spectra of (a) PCP-B unheated (b) PCP-B heated to 2000°C for one hour (c) PCP-B heated to 2500°C for one hour.

(f) Untreated PCP-B - this contains very undefined peaks, material is carbon-based (G band just present), but with very little graphitic-like material.

(g) PCP-B heated to 2000°C - material has become graphitic with clear G band and a clear 2D band showing the presence of hexagonal structure, but the high D band shows that defects are present.

(h) PCP-B heated to 2500°C - decrease in the D band shows less defects than (b), and the narrowing of the G and 2D bands indicate further graphitization.

[00112] Thus, graphite prepared at temperatures of 2500-3000°C from purified coal waste has similar spectral features to synthetic and spherical graphite.

[00113] Powder conductivity of PCP-A (3000°C) was determined by compression between copper foil and a copper rod of a 4.5 g powder sample held in a cylindrical plastic tube. Pressure of 0.175 MPa to was applied by adding water to a beaker on top of the copper rod. Resistivity of 5.97 x 10^-3 ohmmetres (Dm) was obtained for the heated PCP-A sample by this method. The resistivity of a spherical graphite sample was determined under the same compression conditions as 5.17 x 10-3 Dm. SPG resistivity is only slightly better, just 13% lower than PCP-A (3000°C).

[00114] BET surface area was determined by nitrogen adsorption for both the PCP-A (3000°C) as 7.9 m²/g and for PCP-A (2000°C) from example 2 as 30 m²/g. A BET surface area of <10 m²/g is quoted in the specification for Ecograf SPG (EcoGraf-Material-Product-Data-Sheet-Purified-Spherical- Graphite-SPG-WEB-1-1.pdf), thus that of PCP-A (3000°C) satisfies this criterion. Lower surface area SPG is associated with higher Li-ion battery specific capacity and long-term cycling stability (Mao, C. et al, Selecting the Best Graphite for Long-Life, High-Energy Li-Ion Batteries, J. Electrochem. Soc. 165 A1837, 2018).

Example 5. Purification of waste graphite

[00115] This is an example of the pathway to spheroidal natural graphite illustrated in Figure 2.

[00116] A Chinese waste graphite with particle size <20 microns was chosen for this study and its particle size distribution was measured using Malvern Mastersizer 3000. The detailed particle size distribution is given in Figure 8 and shows a d95 of <15.3 microns.

[00117] The following froth flotation test conditions were used: flotation volume 5L, flotation speed 650 RPM and feed solids 5% w/w. The raw graphite sample was subjected to six cleaning stages, each using four different frother and collector reagent combinations, Table 5. The weights of concentrate and tailings were noted at each cleaning stage and fixed carbon content determined. Tests 1-4. MIBC (methyl isobutyl carbinol) and Dowfroth 200 (manufactured by Dow, Michigan, USA) were used as frothers, NASMIN (manufactured by NASACO, Cossonay, Switzerland) as a combined frother/collector, and diesel as a collector. The whole concentrate at each stage was taken forward to the next cleaning stage. For Test 5 the stage 3 concentrate was ground finer in a Stirred Media Detritor to d80 = 5pm. Float times for each cleaning stage varied from 10-20 minutes, MIBC concentrations from 200 to 560 ppm, Dowfroth 200 concentrations from 280-560 ppm,w, NASMIN concentrations from 640-1800 ppm,w and diesel from 40-560 ppm,w. The highest concentration of each reagent was used in cleaning stage one (also known as the rougher stage). pH, EH (redox potential) and float kinetics were monitored at each stage. Tailings were combined from each of the flotation stages. Flotation testing was carried out at Grinding Solutions Ltd., Truro, Cornwall, UK.

[00118] Table 5. Fixed carbon content and yields of concentrates prepared by 6 cleaning stages using different frother/collector options

Note: * signifies that further milling to d80 = 5 pm was carried out after cleaning stage 3.

[00119] These test results on natural graphite waste showed that six separation stages increased the graphitic carbon content to 98.6 % from 95.3%. The PCP separation process is unique in separating small sized <20 pm particles, the benefit of improving carbon purity from 95% to 99% without using hazardous strong acid leaching methods is unexpectedly beneficial particularly for countries where acid leaching is either banned or is economically unviable when meeting appropriate environmental standards. It could not be predicted that reducing the raw graphite particle size used for flotation to d99 <20 pm would achieve this significant change. Furthermore, these results indicate that further size reduction from d80=10.7 pm to d80 = 5 pm, does not lead to a further improvement in graphite fixed carbon content.

Example 6. Purification of biochar

[00120] This is an example of a pathway to synthetic graphite as illustrated for PCP as mechanisms D and E2-E4, in Figure 1.

[00121] A biochar sample manufactured by gasification of waste wood by Aries Clean Technologies LLC, Franklin, Tennessee, USA and examined by optical microscopy (transmission, reflectance and cross-polarized) using a Leica Model DM 750 M Polarizing microscope at magnifications of 300, 600 and 3000. Slide samples were prepared via dilution with DI water and sonicated for 30 seconds or up to 5 minutes to facilitate thorough mixing and breakage of agglomerated materials, then dried at 107°C. Observations showed that many individual mineral matter particles were present together with smaller fragmented organic char particles, and this was used to guide the purification procedure selected. The sample was first homogenised, then crushed to <250 pm (60 mesh) with a Holmes pulverizer. A 10g sub-sample separated in heavy media with a Specific Gravity (SG) of 1.3 prepared by concentrating sugar in water (note: the ash content of sugar is negligible). The floats sample from this 1.3 SG separation was then screened using a 20 pm (635 mesh) screen. Ash content measurements were carried out on the feed and the various fractions separated, see Table 6. The microscopy and separation tests were carried out at Arq LLC, Corbin, KY, USA.

[00122] Table 6. Biochar SG/size fractions: proportions and ash contents

[00123] The results were surprising:

1. Separation at 1.3 SG gave a relatively low yield (5%m) of high ash content material reduced ash content of the floats fraction by more than a half from 4.53%m to 2.05%m.

2. Size separation at 20 pm split the floats into higher ash (3.16%m) and low ash fractions (0.52%m) with a 40% yield of the latter. An ash content of 0.52%m is unusually low for a biochar.

Example 7. Further purification of PCP by solvent extraction with tetralin

[00124] 4g PCP-A was mixed with 210 mL tetralin and treated in a 2.5 cm reactor at 370°C under a pressure of 4.14 MPa. The resultant mixture was filtered on 0.5 pm glass microfiber and tetralin removed from the filtrate by vacuum distillation. The extract and residue were weighed. Ash content for both products was determined by thermogravimetric analysis by combustion in air for 8 hours at 750°C; this follows removal of moisture (<130°C), volatiles (130°-395°C) and pyrolysis (395°C-600°C) in the absence of air. This was carried out at Western Research Institute, Laramie, WY, USA and full elemental analysis by Inductively-Coupled Plasma Mass Spectrometry determined at Hufman Hazen Labs., Golden, CO, USA. [00125] The results for ash content and element concentrations of PCP-Aand the tetralin extract are given in Table 6. Thus, a PCP extract with an ash content of 0.12 %m was prepared at a yield of 59 %m.

Table 7. Elemental analyses of PCP-Aand the tetralin extract

[00126] The elemental analysis of the extract, Table 7, showed that carbon content had been increased by 3 %m largely at the expense of oxygen content, both changes improve the suitability of the extract for graphitisation.

[00127] Just as the ash content is reduced by over an order of magnitude, most of the principal metal impurities, i.e. Al, Si, Fe, Ca, Mg and Ti, are also reduced by ten-fold or more. Na and K levels were reduced two-three times. Even without graphization at 3000°C, the calcium level is below the typical maximum concentration acceptable in Li-battery anodes, Table 3.

[00128] Graphitization @ 3000°C of PCP-Ahas been shown to reduce ash content by 76% (Example 3) with respect to PCP ash content. Similar heat treatment could be expected to reduce the ash content of this PCP-A extract from 0.12 %m to 0.03 %m, i.e. 99.97% purity, well above the 99.95% purity requirement for synthetic graphite. Conclusions

[00129] Organic material sufficiently pure to act as feedstock for manufacturing hiqh quality graphite for use in lithium-ion batteries has been prepared by novel methods from waste coals, biochar and waste graphite. This avoids the very strong acid treatment currently used in some countries but which are uneconomic in developed economies because of the associated health and safety risks.

[00130] A manufacturing-scale separation procedure has been developed for waste coals to reach organic purity levels one order of magnitude or more below purity levels available from conventionally processed mined coal, such that PCP samples with ash content as low as 0.24%m have been prepared at remarkably high yields (>70%m) of organic material available. Optimum results are achieved following progressive pre-milling through three separation stages to particle sizes below 10 pm with 80% of the particles below 5 pm size.

[00131] Graphite has been prepared at temperatures between 2000°C and 3000°C from PCP that exhibits similar X-Ray diffraction peaks and Raman spectral features to those in synthetic and spherical graphite. The resistivity of graphite heated to 3000°C is slightly lower than that of spherical graphite, but its BET nitrogen surface area meets the specification for a commercial spherical graphite.

[00132] High purity PCPs from coal sourced from 24 sites worldwide have been prepared with ash contents ranging from 0.24%m to 1 ,37%m ash content. Graphitization experiments indicate that without further soaking at 3000°C, these PCPs could yield graphite of carbon purity ranging from well above 99.5%m to almost 99.95%m. This could contribute to the present strategic requirement in to develop processes to enable manufacturing of synthetic graphite more economically.

[00133] By optimising the purity of feedstock for graphitization processes, the residence time at extremely high temperatures (i.e. 2500°C -3000°C) required to vaporize trace inorganic species will be reduced with concomitant energy savings.

[00134] Analogous procedures have been developed to upgrade waste graphite to 98.6%m carbon purity, biochar to 99.5%m organic purity and PCP solvent extract to 99.88%m organic purity.

[00135] Although particular embodiments of the invention have been disclosed herein in detail, this has been done by way of example and for the purposes of illustration only. The aforementioned embodiments are not intended to be limiting with respect to the scope of the appended claims, which follow. It is contemplated by the inventors that various substitutions, alterations, and modifications may be made to the invention without departing from the spirit and scope of the invention as defined by the claims.

Claims

1. A synthetic graphite having a purity level of at least 99.5%, wherein the graphite is obtainable from a coal, wherein the coal is comprised within a purified carbonaceous product (PCP), wherein the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the PCP has an ash content of less than about 8 wt%.

2. The synthetic graphite of claim 1 , wherein at least about 90%v (d90) of the PCP particles are no greater than about 25 pm in diameter, optionally no greater than about 20 pm in diameter.

3. The synthetic graphite of claim 1 or claim 2, wherein at least about 90%v (d90) of the PCP particles are no greater than about 15 pm in diameter, optionally no greater than about 10 pm in diameter.

4. The synthetic graphite of claim 1 or claim 2, wherein at least about 95%v (d95) of the PCP particles are no greater than about 25 pm in diameter.

5. The synthetic graphite of claim 4, wherein at least about 99%v of the PCP particles are no greater than about 20 pm in diameter, suitably no greater than about 15 pm in diameter.

6. The synthetic graphite of claim 1 , wherein at least about 80%v (d80) of the PCP particles are no greater than about 12 pm in diameter, preferably no greater than about 10 pm in diameter, suitably no greater than about 8 pm in diameter, optionally no greater than about 5 pm in diameter.

7. The synthetic graphite of any preceding claim, wherein the average particle size of the PCP is no more than 10 pm, wherein the average particle size of the PCP is determined by laser diffraction.

8. The synthetic graphite of claim 7, wherein the at least about 99%v of the PCP particles have an average particle size of the PCP that is not more than 10 pm.

9. The synthetic graphite of any preceding claim, wherein the PCP has an ash content of less than about 5 wt%, or less than about 3 wt%, or less than about 1 .5 wt%, or less than about 1 .0 wt%, or less than about 0.8 wt%, or optionally less than 0.5 wt%.

10. The synthetic graphite of any preceding claim, wherein the PCP has a water content of less than about 5 wt%, optionally less than about 3 wt%, suitably less than about 1 wt%.

11. The synthetic graphite of any preceding claim, wherein the synthetic graphite is obtained by a process selected from one of: (i) graphitising the PCP at a temperature of around 2500 to around 3000°C in an inert atmosphere;

(ii) calcining the PCP at a temperature of between around 1000 and around 1200 °C in an inert atmosphere, followed by graphitisation at a temperature of around 2500 to around 3000°C in an inert atmosphere;

12. The synthetic graphite of claim 11 , wherein: the graphitising occurs over a time period of at least 1 minute, at least 1 hour, at least 12 hours or at least 24 hours; and/or the calcining occurs over a time period of at least 1 hour, at least 6 hours, at least 12 hours, or least 24 hours; and/or the pyrolysis occurs over a time period of at least 1 hour, at least 3 hours, at least 6 hours, or least 12 hours.

13. The synthetic graphite of any preceding claim, wherein the PCP is obtained from a carbonaceous feedstock material selected from:

(a) a coal waste material comprised of coal ultrafines and/or coal microfines, and wherein the coal waste material is comprised of one or more of the group consisting of: hard coal, such as anthracite; bituminous coal; sub-bituminous coal; and brown coal, including lignite (as defined in ASTM D388-23);

(b) a microfine natural graphite; and/or

(c) a biochar, and/or

(d) a PCP solvent extract.

14. The synthetic graphite of claim 13, wherein the carbonaceous feedstock material is subjected to one or more floatation steps to remove entrained ash in order to produce the PCP.

15. The synthetic graphite of claims 13 or 14, wherein the carbonaceous feedstock material is not pre-treated with a strong acid to reduce ash content.

16. A method of using a coal waste material in a process for the manufacture of a synthetic graphite, wherein the coal waste material comprises coal ultrafines and/or coal microfines, and wherein the coal waste material is comprised of one or more of the group consisting of: hard coal, such as anthracite; bituminous coal; sub-bituminous coal; and brown coal, including lignite (as defined in ISO 11760:2005), and wherein the coal waste material is comprised within a purified carbonaceous product (POP) that is derived from the coal waste material, wherein the POP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the POP has an ash content of less than about 8 wt%.

17. The method of claim 16, wherein the POP is in particulate form with at least about 90% by volume (%v) of the particles being no greater than about 25 pm in diameter; and wherein the PCP has an ash content of less than about 5 wt%, typically less than about 3 wt%, suitably less than about 2 wt%.

18. A method of using a PCP solvent extract in a process for the manufacture of a synthetic graphite, wherein the PCP solvent extract is derived by solvent extraction of a purified carbonaceous product (PCP) where the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the PCP has an ash content of less than about 8 wt%.

19. The method of claim 18, wherein the PCP is in particulate form with at least about 90% by volume (%v) of the particles being no greater than about 25 pm in diameter; and wherein the PCP has an ash content of less than about 5 wt%, and typically less than 3 wt%, suitably less than about 2 wt%.

20. The method of any one of claims 16 to 19, wherein the PCP has an ash content of less than about 1.5 wt%, 1.0 wt%, 0.8 wt%, optionally less than 0.5 wt%.

21. The method of any one of claims 16 to 20, wherein the PCP has a water content of less than about 5 wt%, optionally less than about 3 wt%, and suitably less than about 1 wt%.

22. The method of any one of claims 16 to 21 , wherein the PCP is used as a blend component with a graphitisation feedstock material selected from: petroleum coke, coal tar pitch, petroleum pitch or mixtures thereof, in order to produce a blended graphitisation feedstock.

23. A process for making a synthetic graphite having a purity in excess of 99.5%, the process comprising obtaining purified carbonaceous product (PCP) from a carbonaceous feedstock material, wherein the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the PCP has an ash content of less than about 8 wt%; and undertaking a graphitisation reaction on the PCP selected from one of the following: (i) graphitising the PCP at a temperature of around 2500 to around 3000°C in an inert atmosphere;

24. The process of claim 23 wherein the PCP is in particulate form with at least about 90% by volume (%v) of the particles being no greater than about 25 pm in diameter; and wherein the PCP has an ash content of less than about 5 wt%, and typically less than 3 wt%, suitably less than about 2 wt%.

25. The process of claims 23 and 24, wherein the carbonaceous feedstock material is comprised of one or more of the group consisting of:

(b) a PCP solvent extract.

26. The process of claim 25, wherein the carbonaceous feedstock material is subjected to one or more floatation steps to remove entrained ash in order to produce the PCP.

27 The process of claims 23 to 26, wherein the carbonaceous feedstock material and/or the PCP is not pre-treated with a strong acid to reduce ash content prior to graphitisation.

28. The process of claims 23 to 27, wherein: the graphitising occurs over a time period of at least 1 minute, at least 1 hour, at least 12 hours or at least 24 hours; and/or the calcining occurs over a time period of at least 1 hour, at least 6 hours, at least 12 hours, or least 24 hours; and/or the pyrolysis occurs over a time period of at least 1 hour, at least 3 hours, at least 6 hours, or least 12 hours.

29. A synthetic graphite material having a purity in excess of 99.5% manufactured according to the process of any one of claims 23 to 28.

30. An anode for a lithium battery comprising the synthetic graphite material of claim 29.

31. A synthetic graphite having a purity level of at least 99.5%, wherein the graphite is obtainable from a coal waste material; wherein the coal waste material is comprised of coal ultrafines and/or coal microfines, and wherein the coal waste material is comprised of one or more of the group consisting of: hard coal, such as anthracite; bituminous coal; sub-bituminous coal; and brown coal, including lignite (as defined in ASTM D388-23); and wherein the coal waste material is comprised within a purified carbonaceous product (PCP), wherein the PCP is in particulate form with at least about 80% by volume (%v) of the particles being no greater than about 15 pm in diameter; and wherein the PCP has an ash content of less than about 8 wt%.

32. The synthetic graphite of claim 31 , wherein at least about 90%v (d90) of the PCP particles are no greater than about 25 pm in diameter, optionally no greater than about 20 pm in diameter.

33. The synthetic graphite of claim 31 or claim 32, wherein at least about 90%v (d90) of the PCP particles are no greater than about 15 pm in diameter, optionally no greater than about 10 pm in diameter.

34. The synthetic graphite of claim 31 or claim 32, wherein at least about 95%v (d95) of the PCP particles are no greater than about 25 pm in diameter.

35. The synthetic graphite of claim 34, wherein at least about 99%v of the PCP particles are no greater than about 20 pm in diameter, suitably no greater than about 15 pm in diameter.

36. The synthetic graphite of claim 35, wherein at least about 80%v (d80) of the PCP particles are no greater than about 12 pm in diameter, preferably no greater than about 10 pm in diameter, suitably no greater than about 8 pm in diameter and optionally no greater than about 5 pm in diameter.

37. The synthetic graphite of any preceding claim, wherein the average particle size of the PCP is no more than 10 pm and wherein the average particle size of the PCP is determined by laser diffraction.

38. The synthetic graphite of claim 37, wherein the at least about 99%v of the PCP particles have an average particle size of the PCP that is not more than 10 pm.

39. The synthetic graphite of any of claims 31 to 38, wherein the PCP has an ash content of less than about 5 wt%, or less than about 3 wt%, or less than about 1 .5 wt%, or less than about 1 .0 wt%, or less than about 0.8 wt%, or optionally less than 0.5 wt%.

40. The synthetic graphite of any of claims 31 to 39, wherein the PCP has a water content of less than about 5 wt%, optionally less than about 3 wt%, suitably less than about 1 wt%.

41 . The synthetic graphite of any of claims 31 to 40, wherein the synthetic graphite is obtained by a process selected from one of:

(i) graphitising the PCP at a temperature of around 2500 to around 3000°C in an inert atmosphere;

42. The synthetic graphite of claim 41 , wherein: the graphitising occurs over a time period of at least 1 minute, at least 1 hour, at least 12 hours or at least 24 hours; and/or the calcining occurs over a time period of at least 1 hour, at least 6 hours, at least 12 hours, or least 24 hours; and/or the pyrolysis occurs over a time period of at least 1 hour, at least 3 hours, at least 6 hours, or least 12 hours.

43. The synthetic graphite of any of claims 31 to 42, wherein the PCP is obtained from a carbonaceous feedstock material selected from:

(b) a PCP solvent extract.

44. The synthetic graphite of claim 43, wherein the carbonaceous feedstock material is subjected to one or more floatation steps to remove entrained ash in order to produce the PCP.

45. The synthetic graphite of claims 43 or 44, wherein the carbonaceous feedstock material is not pre-treated with a strong acid to reduce ash content.