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WO2024161378A1 - Procédé de production de pastilles agglomérées - Google Patents

Procédé de production de pastilles agglomérées Download PDF

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Publication number
WO2024161378A1
WO2024161378A1 PCT/IB2024/051033 IB2024051033W WO2024161378A1 WO 2024161378 A1 WO2024161378 A1 WO 2024161378A1 IB 2024051033 W IB2024051033 W IB 2024051033W WO 2024161378 A1 WO2024161378 A1 WO 2024161378A1
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WO
WIPO (PCT)
Prior art keywords
pellets
binder
agglomerated
mass
porous
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2024/051033
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English (en)
Inventor
Ryan Michael MCCONNACHIE
Jeffrey Santos CHAUKE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sylvania South Africa Pty Ltd
Tizer International Pty Ltd
Original Assignee
Sylvania South Africa Pty Ltd
Tizer International Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sylvania South Africa Pty Ltd, Tizer International Pty Ltd filed Critical Sylvania South Africa Pty Ltd
Priority to EP24709835.3A priority Critical patent/EP4658826A1/fr
Publication of WO2024161378A1 publication Critical patent/WO2024161378A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/02—Roasting processes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/16—Sintering; Agglomerating
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C22B1/2406—Binding; Briquetting ; Granulating pelletizing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C22B1/2413—Binding; Briquetting ; Granulating enduration of pellets
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C22B1/242—Binding; Briquetting ; Granulating with binders
    • C22B1/244—Binding; Briquetting ; Granulating with binders organic
    • C22B1/245—Binding; Briquetting ; Granulating with binders organic with carbonaceous material for the production of coked agglomerates
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/10—Dry methods smelting of sulfides or formation of mattes by solid carbonaceous reducing agents

Definitions

  • This disclosure relates to a method for producing agglomerated pellets and extends to use of said agglomerated pellets to produce reduced metal and/or metal alloys.
  • the disclosure also relates to agglomerated pellets, typically porous, comprising mineral ore fines and a reductant agent.
  • Extracting metal from ore, and the production of alloys is well known. There remains an ongoing need to produce alloys (and other final metal products) that have enhanced physico-chemical properties including enhanced hardness, hardenability, anti-corrosion characteristics, anti-abrasion characteristics, and wear resistance, and to do so in a profitable manner.
  • U.S. Patent No. 4,576,637 describes a process for producing alloys from pellets, wherein said pellets comprise a metal oxide and a carbonaceous reducing agent. It is now established that producing agglomerated pellets of metal oxide ore, and conducting a solid state pre-reduction prior to a smelting process lowers the overall energy required to produce alloys. However, the carbonaceous reducing agent contributes to an increased carbon footprint which is undesirable.
  • EP 1 274 870 Bl relates to a smelting process, wherein ferrochrome alloy is produced by adding carbide to material containing chromium and iron as oxides.
  • WO 2013/071955 teaches use of silicon carbide in green (or wet) pellets (the so-called sintering feed) when producing sintered pellets of ore before commencing a smelting process to produce corresponding alloys, wherein the silicon carbide surprisingly allowed for the exclusion of an additional carbonaceous reducing agent typically required in a sintering process to form pellets. This was seen as an advancement on the reduction of the overall carbon footprint associated with alloy production, however, the cost of silicon carbide per kilogram as a raw material is significantly more than the cost of coal (including anthracite) per kilogram as a raw material carbonaceous source.
  • EP 1 274 870 Bl also teaches that use of silicon carbide results in a loss of chromium during the smelting process, and as such teaches the further inclusion of additional fluxing agents present during smelting such as MgO, CaO, AI2O3 or SiCK This adds further cost and complicates the overall process design. As such, the apparent advantage of using silicon carbide becomes redundant when taking into account the negative impact on the downstream smelting process.
  • the sintering process to produce the pellets has been improved over time by the inclusion of binders such as clay and/or bentonite to ameliorate the risk of particulate matter from disintegrating pellets resulting in bed turnovers and/or blowout and/or otherwise compromising the smelting process.
  • binders such as clay and/or bentonite to ameliorate the risk of particulate matter from disintegrating pellets resulting in bed turnovers and/or blowout and/or otherwise compromising the smelting process.
  • a method for producing agglomerated pellets from mineral ore fines and a reductant agent, typically a carbonaceous reductant agent wherein the method includes the steps of combining the mineral ore fines and the reductant agent to produce a first mixture and pelletizing the first mixture to produce agglomerated pellets.
  • the agglomerated pellets may then typically by cured at a desired temperature.
  • the agglomerated pellets may typically be porous.
  • a method for producing porous agglomerated pellets comprising the following steps: resizing mineral ore fines such that the particle size distribution D50 is less than or equal to about 1mm in diameter, including less than or equal to about 600 pm in diameter, to provide resized mineral ore fines; resizing a carbonaceous reductant material such that the particle size distribution D50 is less than or equal to about 1mm in diameter, including less than or equal to 600 pm in diameter, including less than or equal to about 500 pm in diameter, to provide resized carbonaceous reductant material; admixing the resized mineral ore fines and the resized carbonaceous reductant material in a container; introducing into the container at least one additive to provide a pre-agglomerated composition; agglomerating the pre-agglomerated composition into pellets; curing the pellets to provide cured pellets; exposing the cured pellets to temperatures of between about 800°C to about 1800°
  • the Applicant has surprisingly and unexpectedly found that the particular particle size distribution D50 of the resized mineral ore fines and the resized carbonaceous reductant material provide porous agglomerated pellets that result in reduced energy requirements when employed in the downstream smelting or reduction processes to produce metal or alloy products in accordance with the second aspect of this disclosure.
  • the mineral ore fines may typically be chromite, hematite, calamine, zincite, tenorite and magnetite.
  • the at least partial solid state reduction of the cured pellets occurs to provide porous agglomerated pellets provides for the at least partial conversion of the mineral ore fines to an alloy.
  • the mineral ore fines is chromite
  • the at least partial solid state reduction of the cured pellets occurs to provide porous agglomerated pellets provides for the at least partial conversion of chromite to ferrochrome. Further downstream processes will see further conversion and/or complete conversion of chromite to ferrochrome.
  • the carbonaceous reductant material may typically be coke, coal and/or anthracite. In a preferred embodiment the carbonaceous reductant material is anthracite.
  • the resized carbonaceous reductant material may be between about 1 and about 50% of the mass of the resized mineral ore fines, including between about 5 to about 35% of the mass of the resized mineral ore fines.
  • the additive may include at least one of, but not limited to, the following group including: a binder, a strengthening agent, a curing agent, and a water repellent.
  • the binder may include at least one of, but not limited to, the follow group including: sodium silicate, bitumen, bentonite, aluminosilicates, biological plant material, paper waste and/or geostabilisation agents.
  • the binder may in use facilitate binding of the resized mineral ore fines and the resized carbonaceous reductant material.
  • the binder is an inorganic binder comprising water, dibasic ester (DBE) and sodium silicate.
  • the binder may comprise between about 1 and about 20% by mass of the agglomerated pellet, including between about 4 and about 15% of the agglomerated pellet.
  • the strengthening agent may include at least one of, but not limited to, the follow group including: fibre glass, paper, cotton, or organic fibre.
  • the strengthening agent may in use improve the structural strength and/or tensile strength of the resulting agglomerated pellet.
  • the strengthening agent provides a demonstrable increase in resistance to shear or elastic damage of the pellets, especially during the curing process.
  • the strengthening agent further facilitates providing an increase in compressive strength of the porous agglomerated pellets.
  • the strengthening agent may comprise between about 1 to about 20% by mass of any solid material being utilized to produce the agglomerated pellet, including between about 5 to about 10% of any solid fines material being utilized to produce the agglomerated pellet.
  • the curing agent may include at least one of, but not limited to, the follow group including: dibasic ester (DBE), carboxylic acid, carbon dioxide, formic acid or other aqueous acidic solutions that may promote and/or accelerate the formation of a binder matrix in the pellets.
  • DBE dibasic ester
  • carboxylic acid carboxylic acid
  • carbon dioxide formic acid
  • formic acid aqueous acidic solutions
  • the curing agent may comprise between about 0.1 to about 20% by mass of the binding agent utilized, including between about 0.5 to 10% by mass of the binding agent.
  • the water repellent may include at least one of, but not limited to, the follow group including: latex, natural rubber, linseed oil, viscous hydrocarbons, paraffin, BS16, and proprietary water and geotextile sealers.
  • the binding agent has demonstrated a behavior of reduced curing and strengthening rate in the presence of atmospheric or free water applied after the formation of the pellet. To combat this, and reduce the necessity of water free storage for uncured pellets, the addition of a water repellent has the dual effect of speeding the curing rate and preventing deleterious effects of high humidity in during curing.
  • the water repellent may comprise between about 1 to about 20% by mass of any solid material being utilized to produce the agglomerated pellet, including between about 2 to about 15% by mass of any solid fines mineral material being utilized to produce the agglomerated pellet.
  • the water repellent may be added to the container before curing and/or before at least partial solid state reduction.
  • the water repellant may be provided to the porous agglomerated pellets after production, and may be provided by way of a spray and/or a dip.
  • the step of agglomerating the pre-agglomerated composition into pellets may take place utilizing conventional pelletizers, including without limitation either a drum or disc pelletizer or combination thereof.
  • the step of curing may include utilization of at least one, but not limited to, the following group including: an ambient curing process, a forced airflow process, an open air exposure process, and a low temperature enhanced curing process.
  • the low temperature enhanced curing process may include temperatures up to about 150°C.
  • the step of curing may take place for a period of between about 30 minutes to about 20 days, including a period between about 1 hour to about 10 days.
  • the step of curing limits exposure to moisture and/or limits mechanical agitation. Limiting exposure to moisture and/or limiting mechanical agitation is necessary to preserve mechanical integrity and curing rate of the pellet during the step of curing while the cured strength develops. Further to this, any moisture content in the pellet has a direct linear impact on the increased power requirement for the reduction of the pellet.
  • the step of exposing the cured pellets to temperatures of between about 800°C to about 1800°C, in use causes the resized carbonaceous reductant to reduce (at least partially) the resized mineral ore fines to provide porous agglomerated pellets, and in turn, improves the overall energy efficiency of a smelting process. It is to be understood that the at least partial solid state reduction of the cured pellets occurs to provide porous agglomerated pellets provides for the at least partial conversion of the mineral ore fines to an alloy.
  • the at least partial solid state reduction of the cured pellets occurs to provide porous agglomerated pellets provides for the at least partial conversion of chromite to ferrochrome. Further downstream processes will see further conversion and/or complete conversion of chromite to ferrochrome.
  • the Applicant was surprised that the particular particle sizes of the resized carbonaceous reductant and the resized mineral ore fines resulted in porous agglomerated pellets that showed, when in use in a smelting process, an improvement of between about 1% and about 21%, including between about 10% and about 21%, compared to current state of the art methods in regard to energy efficiencies. This efficiency improvement is reproducibly demonstrated in furnace runs comparing the porous agglomerated pellets produced via the method of this disclosure and those produced from current industrial processes.
  • the particular particle size distribution of the resized mineral ore fines and/or the resized carbonaceous reductant enhances the likelihood that a resized carbonaceous reductant particle will come into close enough contact with a resized mineral ore fine particle such that at least partial solid state reduction of a metal oxide included within the resized mineral ore fine particle should take place.
  • the pores within the porous agglomerated pellets facilitate more efficient and effective heat and gas transfer throughout a majority of a volume of said porous agglomerated pellet, such that in use, the at least partial solid state reduction is greater when compared to non-porous pellets, and in turn the energy efficiencies in a downstream smelting process is greater.
  • Pores formed in the step of curing and/or the step of at least partial solid state reduction are further enlarged and/or enhanced during a reduction process downstream due to the removal of volume from reduced metal oxides and the consumption of the carbon based reductant providing increased volume or space in the porous agglomerated pellet for gas flow.
  • the method may include a further step of determining size of the pellets such that in use any pellets outside a preferred pellet particle size are not exposed to the step of curing and/or cured pellets outside a preferred particle size are not exposed to the step of at least partial solid state reduction.
  • Pellets falling outside of the ambit of the preferred pellet particle size are recycled within the method.
  • the pellets falling outside of the ambit of the preferred pellet particle size and which are greater than the preferred pellet particle size are resized to reduce their size (including via crushing or other conventional means). This is necessary to provide optimal gas flow and packing in a reduction furnace downstream.
  • a method for producing a metal product or alloy comprising the following steps: smelting and/or reducing the porous agglomerated pellets according to the first aspect of this disclosure.
  • the step of smelting and/or reducing may take place in a furnace and/or a kiln and/or another known smelting and/or reducing apparatus.
  • the Applicant has surprisingly found that the use of the porous agglomerated pellets (that have already undergone at least partial solid state reduction) results in overall increased energy efficiencies.
  • a porous agglomerated pellet for use in methods for producing a metal product and/or alloy (typically via a smelting and/or reduction process), the porous agglomerated pellet comprising: resized mineral ore fines having a particle size distribution D50 less than or equal to about 1mm in diameter, including less than or equal to about 600 pm in diameter; resized carbonaceous reductant material having a particle size distribution D50 less than or equal to about 1mm in diameter, including less than or equal to 600 pm in diameter, including less than or equal to about 500 pm in diameter; and an additive.
  • the additive may include at least of, but not limited to, the following group including: a binder, a strengthening agent, a curing agent, and a water repellent.
  • the binder may include at least one of, but not limited to, the following group including: sodium silicate, bitumen, bentonite, aluminosilicates, biological plant material, paper waste or geostabilisation agents.
  • the binder may in use facilitate binding of the resized mineral ore fines and the resized carbonaceous reductant material.
  • the binder is an inorganic binder comprising water, dibasic ester (DBE) and sodium silicate.
  • the binder may comprise between about 1 and about 20% by mass of the porous agglomerated pellet, including between about 4 and 15% of the porous agglomerated pellet.
  • the strengthening agent may include at least one of, but not limited to, the follow group including: fibre glass, paper, cotton, maize meal or organic fibres.
  • the strengthening agent may in use improve the structural strength and/or tensile strength of the resulting agglomerated pellet.
  • the strengthening agent may comprise between about 1 to about 20% by mass of any solid material being utilized to produce the porous agglomerated pellet, including between about 5 to about 10% of any solid material being utilized to produce the agglomerated pellet.
  • the curing agent may include at least one of, but not limited to, the follow group including: dibasic ester (DBE), carboxylic acid, carbon dioxide, formic acid and/or other aqueous acidic solutions.
  • the curing agent may comprise between about 0.1 to about 20% by mass of the binding agent, including between about 0.5 to about 10% by mass of the binding agent.
  • the water repellent may include at least one of, but not limited to, the follow group including: latex, natural rubber, linseed oil, viscous hydrocarbons, paraffin, BS16, and proprietary water and geotextile sealers.
  • the water repellent may comprise between about 1 to about 20% by mass of any solid material being utilized to produce the agglomerated pellet, including between about 2 to about 15% of any solid material being utilized to produce the porous agglomerated pellet.
  • the resized carbonaceous reductant material may be between about 1 and about 50% of the mass of the resized mineral ore fines, including between about 5 to about 35% of the mass of the resized mineral ore fines.
  • porous agglomerated pellet of this third aspect of the disclosure may be produced in accordance with the method described in the first aspect of this disclosure.
  • Figure 1 shows green strength mapping of pellets from 70:30 chromite (mineral ore fines) to anthracite (carbonaceous reductant material) ratio;
  • Figure 2 shows green strength mapping of pellets from 70:30 chromite (mineral ore fines) to anthracite (carbonaceous reductant material) ratio;
  • Figure 2 shows green strength mapping of pellets from 80:20 chromite (mineral ore fines) to anthracite (carbonaceous reductant material) ratio;
  • Figure 4 shows overall compressive strength for 70:30 ferrochrome carbon pellets
  • Figure 5 shows overall compressive strength for 80:20 ferrochrome carbon pellets
  • Figure 7 80 20 chromite: coal at various binder mix
  • Figure 8 90 10 chromite: coal at various binder mix
  • Figure 9 100:0 chromite: coal at various binder mix
  • Figure 10 shows pellets size distribution
  • Figure 11 shows pilot plant trial runs compressive strength
  • Figure 12 shows compressive strength of porous agglomerated pellets of the disclosure and of Samancor prior art
  • Figure 13 shows 100 kg small scale compressive strength
  • Figure 14 shows trial runs curing rate
  • Figure 15 shows moisture content results of the 100 kg runs
  • Figure 16 shows moisture content results of the 250 kg runs.
  • Figure 17 shows laboratory compressive strengths for all the pellets.
  • a method for producing porous agglomerated pellets comprising the following steps:
  • Step (g) exposing the cured pellets to temperatures of between about 800°C to about 1800°C, including between about 1000°C to about 1500°C, for a time period of between about 5 to about 60 minutes, including between about 10 and about 30 minutes, such that at least partial solid state reduction of the cured pellets occurs to provide porous agglomerated pellets.
  • Step (g) is an at least partial solid state reduction of the cured pellets.
  • the at least partial solid state reduction of the cured pellets occurs to provide porous agglomerated pellets provides for the at least partial conversion of the mineral ore fines to an alloy.
  • the mineral ore fines is chromite
  • the at least partial solid state reduction of the cured pellets occurs to provide porous agglomerated pellets provides for the at least partial conversion of chromite to ferrochrome. Further downstream processes will see further conversion and/or complete conversion of chromite to ferrochrome.
  • Coal (Anthracite) (as example of carbonaceous reductant material), chrome containing ore (typically chromite) (as example of mineral ore fines), sodium silicate (S.S), dibasic ester (DBE), water, fibre , and black box (wherein black box is a proprietary chemical blend of oils, alcohols and surfactants) Apparatus for agglomeration into pellets via pelletization technique
  • Raw material characteristics are extremely important for the agglomeration step to produce pellets.
  • chrome particle size as an example mineral ore fines
  • carbonaceous reductant material a particle size of about 500 pm coal (as an example of the carbonaceous reductant material) as utilized for agglomeration/pelletization purposes (Step (e)).
  • the ratio of chromite to coal was split into 70:30, 80:20, 90:10 and 100:0 for specific tests respectively.
  • the required masses per test were measured using an LBK 30 (electronic scale).
  • the quantities for each test were based on table 3.1 and 3.2, also the tests were conducted at one test at the time, consecutively. It was necessary to mix the carbon chromite using the high shear mixer to achieve an even mix throughout the tests.
  • the binder Before the addition of the binder, the binder needs to be prepared.
  • Binders are usually any substance that can be utilized to cause particles to agglomerate together into a single mass.
  • the function of the binder is to create a moist fine plastics material, this provides nucleate seeds that grow at a controlled rate into well -formed and uniformly shaped pellets.
  • the binder holds the particles in the pellets together while the water is removed and continues to bind them together until the pellet is fully cured to provide the cured pellets.
  • the binder is an inorganic binder comprising a combination or mixture of water, dibasic ester (DBE) and sodium silicate.
  • Sodium silicate is an inorganic polymer that offers cross -linking structures and tends to create chains when it interacts with other mineral materials in the pellet curing process.
  • the compound comprises two major components namely di-sodium oxide (NazO) and silicone dioxide (SiOz) in defined ratios.
  • the binder goes through a precipitation process where it can form either gel-like silica, silicic acid or sodium silicate depending on the concentration, pH and temperature.
  • the mechanism of binding needs to go through a curing stage where compound could be heated or reacted with carbon dioxide to form a polysilicon acid polymer which is the actual binder formed in the final pellets.
  • Both the commercial sodium silicate (Natsil 3044 & Natsil 3245) samples used, and the proprietary sodium silicate of the Applicant were used to conduct the pelletization and briquetting test runs.
  • the purpose of using the aforementioned mixture of water, dibasic ester (DBE) and sodium silicate is to create the baseline binding effects on solid raw material to form spherical pellets.
  • DBE dibasic ester
  • sodium silicate There were two commercial batches of sodium silicate that were used to conduct these test; NAtsil 3044 and Natsil 3245 mass percent. Due to poor mixing effects (immiscible components), the sequence of preparing the inorganic binder would start with water (polar), sodium silicate (polar) and DBE (nonpolar), in that particular order. The specific order was necessary to prevent separation and skinning effects between the components.
  • the DBE component brings about drying effects when added to the silicate binder. Therefore, it is necessary to mix the components of the inorganic binder using a high mixer for at least 5 minutes. Additional observations were noted when the mixing is conducted at high temperature (above 60°C) and low temperatures (below 25°C). At high temperature, the inorganic binder tends to solidify due to the presence of DBE. Also, at low temperatures, the mixture becomes extremely vicious to an effect where the binder is not usable.
  • the sequence of preparation had to be optimised to mitigate such negative performance from the binder.
  • the three reagents were all mixed in a IL (one litre) beaker and were vigorously mixed with an aid of electronic stirrer to achieve a homogenous solution. These preparations were conducted in ambient conditions.
  • briquetting comprises compressing of fine particles into lumps of consistent shapes. Briquetting is usually used for direct reduction processes due to the metal produced being ductile to agglomerate together by mechanical deformation without the requirement for a binder. However, for this investigation briquetting technique was used with a binder to develop control samples/pellets. The incorporation of the binder was to ensure complete coverage of the fines/particles being agglomerated.
  • Pelletization technique varies slightly from briquetting in a sense that, through pelletization, the fine particles are first formed into ball like shapes by combining moist ore with a binder and rolling into balls using a pelletization disc.
  • the following requirement must be met: (i) sufficient particle size distribution, (ii) effective binder (the binder should be able to hold particles together after the pellet is dried), and (iii) sufficient moisture content.
  • Agglomeration requires a pelletization disc, stopwatch, logbook, and electronic scale and transfer bottle.
  • a plastic bin/sample vial of known mass was placed on the scale at proximity to disc pelletizer, this was to simplify the transfer of fine material into the disc. The moment the first load was transferred into the disc pelletiser the time was monitored to keep track of the additional rates of material.
  • the disc pelletizer was set at a frequency of 8.0 Hz.
  • the agglomeration/pelletization occurred after seed formation and extra binder addition would increase the size of the pellets in the rotating disc.
  • the time and mass transfers of both the binder and raw material were recorded to attain the rates of addition.
  • the reason for including the briquetting technique was to develop control samples to assist in the selection of the best performing mix in terms of binder composition and carbon and chrome ore and eliminate the variations arising from the agglomeration techniques.
  • the technique was executed using muffin pan and 16 kg compressing weight. The mixtures were prepared, compressed with the 16kg for 20 minutes, before they were allowed to cure.
  • Briquetting procedure typically proceeds as follows: coal fines (anthracite) passing 500pm and chromite particles passing 1mm were mixing using a hand drilling (high shear mixer) in a 5L bucket for 5 minutes; the inorganic binder was then mixed with anthracite and chromite (sufficient mixing was achieved after 10 minutes of blending the binder with dry particles); a clean muffin pan was laid on a flat surface followed by laying a cling wrapper on pan opening; a slurry mix of carbon ferrochrome and binder filled up the pan opening and extended cling wrapper was used to cover the surface of the slurry; 16kg weight was applied on top of the slurry mix after being wrapped; the weight was allowed to compress the mixture for 20 minutes before it was removed to tip off the resultant muffins; the compressed muffins were placed in a plastic tray where they were allowed to cure (Step (f)) for a 144 hours. Compressive strength was measured on an interval of 24hours. Step (f):
  • Curing the pellets to provide cured pellets may take place via conventional means known to the person in skilled in the art. In the examples herein above, curing took place via natural means (ambient air drying/curing). Curing took place for about 144 hours.
  • Step (g) is an at least partial solid state reduction of the cured pellets.
  • Figure 1 shows the compressive green strength trend of the 70:30 composition which was prepared from Natsil 3245 (binder) and it was tracked for 96 hours.
  • Figure 4 shows green strength mapping of pellets from 80:20 chromite to coal (anthracite) ratio.
  • Figure 5 shows overall compressive strength for 70:30 ferrochrome carbon pellets.
  • Figure 4 presents compressive strengths for 70:30 ferrochrome carbon pellets after 22 days. Test 4 and 7 showed an improved strength of 74.5kg on average, this slight improvement could be the result of an increased binder content of 10%. However, a significant improvement on strength was realized on the 80:20 ferrochrome carbon pellets presented in Figure 5.
  • Figure 6 shows overall compressive strength for 80:20 ferrochrome carbon pellets.
  • Test 4 showed exceptional strength on both fibre and non-fibre pellets. These results correspond to the results seen in Figure 4 where non-fibre pellets showed better strength relative to the other tests. This suggests that the presence of carbon hinders the strength of the pellets that are produced in a pelletization disc. Also, the extended curing period suggests that the strength of the pellets could be improve when offered sufficient time to cure.
  • Phase two (briquetting technique) compressive strength for proprietary sodium silicate containing inorganic binder at various grades/composition of raw material and inorganic binder.
  • the solid material was categorized (mass basis) into three class as per chrome to coal ratio. Also, the phase two study was investigating the decisive control sample for upscale purposes. Additional parameters such as a hot binder, different silicate grades (2.2, 2.6 & 3.2), inclusion of black-box, fibre were also investigated.
  • Figure 6 shows 70:30 chromite: coal (anthracite) at various binder mix. Increased content of coal (anthracite) relative to the other combinations of chromite to carbon (anthracite) is reported in Figure 6. An exceptional performance was observed on the 3.2-grade silicate on an average of 106kg.
  • Figure 7 shows 80:20 chromite: coal (anthracite) at various binder mix.
  • Figure 8 shows 90:10 chrome: coal at various binder mix
  • Figure 9 presents pure ferrochrome carbon pellets, these were produced through briquetting method to ensure that full coverage of the particles is achieved and measured. As mapped out in Figure 9, different reagents that were blended with sodium silicate binder to enhance the compressive strength are presented. An exceptional performance was observed on 3.2-grade sodium silicate binder followed by silicate binder with no DBE.
  • pelletization and briquetting processes Two methods of agglomeration were investigated, the methods include pelletization and briquetting processes in which the briquetting technique was used as the basis of the control sample.
  • the briquetting method was achieved by mixing the appropriate quantities of binder and fines to form a slurry/sludge-like mixture, the wet sludge was then dispersed in a muffin pan where it was compacted with 16kg object for 20 minutes to form stable briquettes.
  • pelletization method was achieved through charging dry fine and spraying binder solution into a rotating disc set at the frequency range of 8 - 13Hz and 45° angle.
  • phase one pelletization technique
  • the fine particles were screened to passing 1mm for chromite and 500pm for anthracite (coal) and these were mixed with binder solution of 10 - 8% sodium silicate and total moisture (inherent moisture, DBE, sodium silicate) content of 13.5 - 14.00%.
  • binder solution 10 - 8% sodium silicate and total moisture (inherent moisture, DBE, sodium silicate) content of 13.5 - 14.00%.
  • test 9a The highest strength achieved was 38.7 kg after 72 hours from 70:30 (chromite: anthracite [coal]) ratio produced from batch Natsil 3044 (commercial binder).
  • This high strength was obtained from test 9a with a composition of 60.2% chromite, 25.8% coal, 5.2% water and 8% binder as given in Table 3. This composition amounts to 14% moisture and 8% binder.
  • the presence of fibre seems to have a diminishing effect, this is supported by a plot of test 4 in Figure 3 in which the strength exponential increases to a maximum of 27.6 kg after 48 hours and declines to 25.7 kg at 72 hours.
  • test 4 in discussion comprised of 80:20 (chromite: anthracite [coal]) ratio, and binder: water ratio (10:14) % which was a slight improvement compared to 70:30 chromite to coal ratio.
  • the pellets from test 4 (80:20 chromite to anthracite [coal]) showed a significant increase in strength after being allowed to cure for 22 days.
  • the strength attained after 22 days was 105 kg which was by far the strongest compared to the rest of the samples.
  • the same test 4 without fibre also showed a significant strength (94.2 kg) after 22 days.
  • the strength of the pellet is proportional to the size of the resultant pellet and this was consistent for all the samples. Further, it has been observed that it is necessary to induce tumbling and scrapping during pelletization technique. Therefore, it is recommended to scrape off the material as they pelletize inside the pan.
  • phase two (briquetting method) investigation the best pellets performance was achieved through grade 2.2 silicate (DBE inclusive) on 90:10 chromite :carbon. A common decline in compressive strength is realized throughout the pellets and this could be linked to the nature of sodium silicate that seems to be sensitive to environmental weather conditions. Lastly, warm binder showed poor performance in terms of compressive strength.
  • the purpose of this further example is to report the production and the performance of ferrochrome coal porous agglomerated pellets at various compositions (70:30, 80:20, 90:10, 100:0) with the use of a sodium silicate binder at two different grades LSiCUNazO ; 3.2 & 2.2) on the demonstration scale pilot plant.
  • the mineral ore fines (particularly in this example chromite), were resized via conventional means to having a particle size of about 1 mm. Carbonaceous reductant material in the form of anthracite was reduced in particle size from -3 mm to -500 pm.
  • the resized mineral ore fines (chromite) and carbonaceous reductant material (anthracite) were mixed via conventional means in a first ratio.
  • Solid raw material (chromite and anthracite) was milled to the desired particle size from arrival.
  • a Hammer mill J-101 was utilized to process the material where the outlet screens are changed in-between the milling procedures. It required an hour to process a ton of chromite through the mill under normal operation where the 1mm screen is set on the outlet of the J-101. Subsequently, it took a further hour to process the anthracite through the mill where 500um is set on the outlet.
  • the screened material was transferred into hopper H-101 and H-102 using tractor loader backhoe (TLB).
  • the chromite is loaded onto running conveyor through screw conveyor.
  • the reason for mounting the running conveyor to the screw conveyor is to further eliminate any coarse particles from chromite, this is achieved through an additional crushing mechanism offered by the screw conveyor.
  • the chromite and anthracite coal material are admixed in a high shear mixer.
  • the inorganic bind is preferably a sodium silicate wherein the SiO : Na O ratio varying from 2.2 to 3.2.
  • aqueous silicate carbon dioxide gas, or acid, such as that released by hydrolysis of ester such as dibasic ester (DBE)
  • DBE dibasic ester
  • the produced hydrated silica namely silica gel is responsible for giving the necessary strength for the agglomerates and pellets.
  • Sodium silicate solution as an inorganic binder is of particular importance mainly because the curing time of the agglomerates is low, and it is environmentally extremely beneficial.
  • the pre-agglomerated composition is a wet material, and is fed into a drum pelletizer at a rate determined by an operator to either form seed or grow pellets.
  • the drum pelletizer has an adjustable angle and speed/frequency.
  • the wet pre-agglomerated material is gradually loaded into the drum pelletizer. After a growth period of between 5 -7minutes of process initiation, the seed material is sufficiently grown to produce mature pellets, +13mm.
  • Curing the pellets to provide cured pellets may take place via conventional means known to the person in skilled in the art. In the examples herein above, curing took place via natural means (ambient air drying/curing). Curing took place for about 144 hours.
  • Step (g) is an at least partial solid state reduction of the cured pellets.
  • Pilot plant production differs from small scale production which impacts the preferred or optimized embodiments produced via each process.
  • Table 4 Optimized batch ratios for small scale pelletization for 70:30 combination.
  • Table 5. Preferred upscale (pilot plant) pelletization batch for 70:30 carbon ferrochrome.
  • the cured pellets [after Step (f)] of this disclosure were evaluated to ascertain certain physicochemical properties. It is noted that two different sodium silicate binders that were investigated were 3.2 and 2.2 grades of sodium silicate as described above. The mechanical strength of the porous agglomerated pellet was evaluated “green”, in other words, directly from the production process, and then every 24 hours to monitor the impact and effect of the curing.
  • Particles or pellet size distribution was measured through the use of shaker screens.
  • the purpose of using these tools was to grade the size of the pellets/particles from both the Samancor (the industry standard known in the art) and the porous agglomerated pellets of this disclosure and the input feed materials. This enabled categorization and standardization of the overall assessment.
  • the screens were also utilized in the evaluation of the abrasion test products to determine the resulting size classification from those tests.
  • the test was conducted on the cured pellets [after Step (f)] of this disclosure.
  • a compressive strength tester (rated to a maximum 500kg capacity) mounted on a Loadtech LT 1240 control panel was used to conduct compressive breakage strength measurements of the porous agglomerated pellets of this disclosure.
  • a minimum sample size of 10 pellets was randomly selected from both the disclosure and commercial pellet (Samancor). The instrument used a hydraulic mechanism to apply pressure and ensure test reproducibility and minimise inaccuracy. The test was conducted on the cured pellets [after Step (f)] of this disclosure.
  • the cured pellet samples (of the disclosure and of Samancor) were subjected to abrasion (tumbler) tests. These tests measure the toughness of the pellets in terms of degradation, crushing and disintegration properties under a rotational load.
  • Three kilograms (3kg) of pellets (of the disclosure and of Samancor) were placed in a drum, and the drum rotated at a frequency of 33Hz for 10 minutes.
  • the resulting pellets and fine particles are then separated into the amounts passing 20mm, 16mm, and 6mm and 500pm screens.
  • the tests are intended to demonstrate the abrasion durability of the pellets under standard handling processes.
  • Drop tests were conducted to evaluate the ability of the pellets (of the disclosure and of Samancor) to withstand drop impacts. This assessed the ability to resist deformation or breaking during handling.
  • the tests were conducted on pellets of the disclosure and of Samancor (industry available pellets).
  • the pellets were loaded into the 2 m tubes with steel plates on both ends.
  • the tube was rotated in the vertical axis 10 times to simulate a repeated dropping scenario at a height of 2 metres.
  • the resulting material is then separated into those passing a +4mm screen to measure the mass of fines generated as a percentage of the starting mass.
  • the porosity test was conducted by Mintek on the porous agglomerated pellets of this disclosure [after Step (g)] .
  • the porosity measurement was conducted to assess the pore volume that is accessible to reducing gases or liquid ingress within the pellets.
  • the porosity methodology was executed as follows on pellets of the disclosure and of Samancor:
  • the hot compression test is conducted to evaluate the behavior of the binder at elevated temperatures on pellets of the disclosure and of Samancor.
  • the pellets were placed in a furnace (1200 °C) for 4 hours.
  • the average mass of five pellets were measured before and after the furnace test to determine any loss in mass during the high-temperature test. After four hours elapsed, the pellets were removed from the furnace and the compression strength test is conducted on each agglomerate, while still hot, and the data is recorded and the strength is compared to the cold compression strength.
  • Step (g) the test was conducted during Step (g). In other words, during the at least partial solid state reduction pellets were taken out and tested.
  • the pellets of the disclosure were produced from the silicate-based binder in which carbon ferrochrome fines and anthracite were utilised as the raw material. Before pelletization, the fines were mixed on three set ratios of chromite to anthracite to produce the sample pellets. The mass basis ratios used to produce these were as follows: 90:10 (chromite to coal), 80:20 (chromite to coal) and 100:0 (chromite to coal).
  • the pellets of the disclosure were cured in ambient conditions.
  • Figure 10 shows pellets size distribution.
  • the overall particle size distribution for the porous agglomerated pellets of the disclosure is coarser when compared to Samancor agglomerates.
  • the majority of the pellets of the disclosure ranged between -25 mm and 16 mm with an average of 74.125% retained on +20 mm and + 16 mm.
  • the size distribution of the pellets of the disclosure relies on the production/pelletization procedure which can be adjusted to achieve any desired size.
  • the pilot plant is flexible to accommodate any desired size pellets and this information is merely included for completeness of the assessment. Compressive Strengths Results
  • Compression strength tests were tracked every 24 hours after production/pelletization. The purpose of this exercise was to measure the load/weight required to cause a pellet to break. 10 pellets were selected from each batch (Samancor and in-house pellets).
  • Figure 11 shows a range of trial tests that were executed on the plant. These tests include the investigation of DBE effect (in terms of dosage) and strength properties.
  • grade 3.2 silicate pellets showed exceptional performance in contrast to grade 2.2 silicate binder. Poor performance can be observed on the grade 2.2 pellets of 80:20 chromite: anthracite composition, these pellets resulted in an average of 51.00 kg in terms of compressive strength as shown in Figure 11. The highest compressive strength achieved by grade 2.2 silicate pellets was 99.46kg on pure ferrochrome pellets (100:0). Above and beyond, 2.2-grade silicate showed low performance and it was therefore eliminated on the samples to be compared against commercial pellets.
  • DBE hardener
  • Figure 12 shows compressive strength of pellets (of the disclosure and of Samancor prior art), and particularly shows strength development of the pellets over the curing step of Step (f) [before Step (g)]. In other words, strength tests from green pellets to cured pellets (with no at least partial reduction).
  • the prior art comparison uses sintered Mooinooi pellets and sintered Samancor pellets.
  • the 3.2-grade sodium silicate based pellets (of the disclosure and of Samancor) compressive strengths and moisture content for the final runs were monitored for at least 13 days of curing. There were seven runs conducted on the pilot plant at 12% binder dosage (DBE inclusive) and 14.5% total moisture. Four of these runs were produced in 100 kg batches with different chromite: anthracite ratios (100:0, 90:10, 80:20 & 70:30), and three were produced in 250 kg batches (100, 90:10, 80:20).
  • the compressive strengths of the porous agglomerated pellets of the disclosure were directly compared to sample received from Samancor.
  • Figure 13 presents the compressive strength results for the 100 kg batches and Figure 12 for the 250 kg batches.
  • the compressive strength of agglomerates took six days of curing to surpass the 100 kg specification, except the 70:30 compositions that remained below 100 kg for 17 days of curing.
  • the 80% chromite agglomerates reached the highest compressive strength of 210.48 kg after 20 days of curing, and 70% reached 120 kg after 18 days of curing.
  • the 90% and 80% chromite agglomerates had a gradual increase in strength for the upscale runs when compared to the 100 kg run.
  • the compressive strength of both runs surpassed the 100 kg target after 8 days of curing and both Samancor samples after 12 days of curing.
  • the 90% achieved a maximum compressive strength of 281.40 kg after 15 days curing and the 80% chromite agglomerates achieved a maximum of 195 kg after 15 days of curing.
  • the strength results from both the 100 kg and the 250 kg run show a common trend of gradual strength increase, then a maximum strength is reached and the strength falls off and keeps fluctuating thereafter. This trend could be explained by evaluating the susceptibility of the agglomerates towards moisture absorption under different environmental conditions.
  • Figure 14 shows trial moisture runs curing rate.
  • the curing rate of the 2.2 and 3.2 sodium silicate agglomerates were monitored every 24 hours by measuring the moisture content in the curing pellets. It is shown in Figure 14 that 2.2 sodium silicate pellets of the disclosure were curing at a slow rate and the moisture was fluctuating due to the hygroscopic nature of these pellets.
  • the 3.2 sodium silicate agglomerates took 11 days for their moisture content to fall below 2% moisture whereas the 2.2 remained above 2% until the 13 th day. The lowest moisture achieved was observed from the 90: 10 agglomerates with 1.5% DBE content at 1% after 18 days of curing.
  • the drop test analysis was conducted with a minimum of 10 agglomerates from each composition (varying mass ratios of chromite to coal).
  • the tube used for testing was rotated in the vertical axis for 10 times to simulate a repeated dropping scenario at a height of 2 metres.
  • the resulting material is then separated into particles passing -4mm screen to measure the mass of fines generated as a percentage against the starting mass.
  • porous agglomerated pellets according to the disclosure were of great size (- 25mm to +16mm) with no cracks, this could explain the generation of fewer fines by the pellets of the disclosure. Nevertheless, pellets made from 80:20 chromite to carbon with an optimized binder mix showed a slight generation of fines even though it was lower than fines generated by Samancor pellets.
  • the size of the porous agglomerated pellets according to the disclosure ranges from +16mm to 20mm thus the 3kg sample required for abrasion tests comprised 50% +16mm agglomerates and 50% of 20mm agglomerates.
  • the tests only accounts for the -20mm +16mm cumulative passing. This is considered as a measure of fines generated after 10 minutes of abrasion.
  • the minimum fines generated can be observed from the ‘3.2 SS 90: 10 - 1.5% DBE, 14.5% moisture composition’ composition’. On average the 2.2 binder compositions performed better than the 3.2 with averages of 6.08% and 3.57% respectively.
  • Hot Compression The hot compression strength tests were conducted at 1200°C for a period of four hours, the results obtained are presented in Table 22 below: Table 22. Hot compression strength at 1200 °C
  • the pellets with the low carbon content cools down at a rapid rate. This was observed during pellets discharge from the furnace. Chromite pellets containing high carbon content tend to maintain their heat, hence the softness behavior during compression strength measurements.
  • phase characterization requires the specialized instrument to extract the mineralogical properties of the pellets.
  • Analyses showed that the porous agglomerated pellets of the disclosure are predominately made of chromite, with the substantial dissolution of aluminium and magnesium in the chromite structure. It was also reported that the pellets containing coal (90:10 - chromite: coal and 80:20 - chromite: coal) result in more alloy phases (higher Cr to Fe mass ratio) which is not observed in the pure chromite pellets (Samancor and 100:0 pellets).
  • the high FeCr alloy and mass ratio of Cr to Fe was attributed to the high content of coal/carbon which enhanced the reduction of Fe and Cr oxides in the pellets during sintering procedure.
  • ICP-EOS Inductively Coupled Optical Emission Spectrometry
  • the carbon content of AR Sylvania pellets ranged from 1.4% to 13.7% and it was reported that AR pure chromite pellets contained at least 1.4% carbon. This indicated that some coal fines were present during the production of the pellets (this could be caused by using a common equipment during the production).
  • Sintered pellets consist of carbon range of 0.21% to 9.68% which indicates a proportional decline in carbon after sintering procedure.
  • Iron to chromium ratio was relatively high for industrial pellets compared to the porous agglomerated pellets of this disclosure, however comparable with 0.72 and 0.68 ratios respectively
  • porous agglomerated pellets according to this disclosure The best performing porous agglomerated pellets according to this disclosure that were produced in the pilot plant was sent to Samancor for external quality assurance and control. On average, the porous agglomerated pellets according to this disclosure outperformed the Mooinooi pellets in terms of the compressive strength across the board.
  • the porous agglomerated pellets according to this disclosure strength ranged between 200 kg and 245 kg. The highest being the pellets with no carbon content (100:0).
  • Figure 17 shows laboratory compressive strengths for all the pellets.
  • the water up-take testing showed material erosion or dissolution of the chromite samples.
  • the erosion of the material resulted in material losses and presented a significant sample disintegration.
  • the erosion of the chromite samples were observed across the samples treated with linseed and paraffin agents.
  • the reagents are linear related to the content of carbon content.
  • the 3.2 sodium silicate grade produced best porous agglomerated pellets according to this disclosure as far as mechanical properties are concerned.
  • 3.2 - Silicate based pellets cures at a high rate relative to 2.2 - silicate based binder.
  • 2.2% DBE content showed optimum performance compared to 3% and 1.5% dosage in the binder mix.
  • An effect of spraying DBE on the surface of pellet after production showed poor mechanical properties.
  • the strength of the porous agglomerated pellets according to this disclosure is compromised when exposed to humid environmental conditions. It is concluded that high humid conditions affects the pellets of the disclosure adversely. It is therefore, recommended that the pellets should be kept in less humid environment to enhance curing rates.
  • the pores within the porous agglomerated pellets facilitate more efficient and effective heat and gas transfer throughout a majority of a volume of said porous agglomerated pellet, such that in use, the at least partial solid state reduction is greater when compared to non-porous pellets, and in turn the energy efficiencies in a downstream smelting process is greater.
  • Pores formed in the step of curing and/or the step of at least partial solid state reduction are further enlarged and/or enhanced during a reduction process downstream due to the removal of volume from reduced metal oxides and the consumption of the carbon based reductant providing increased volume or space in the porous agglomerated pellet for gas flow.
  • the energy efficiency may, without being limited to theory, in part also be attributed to the binder, particularly the inorganic binder.
  • the energy efficiency may, without being limited to theory, in part also be attributed to the method of producing the porous agglomerated pellets according to this disclosure and/or the unique composition of the porous agglomerated pellets themselves.
  • a cost model was developed for the FeCr (ferrochrome) smelting pipeline with detailed calculations on efficiencies, raw material cost, unit consumptions and exchange rates. The accuracy of the model was tested with actual data from a FeCr (ferrochrome) smelter and proved to be more than 98% accurate.
  • pellets are produced through the Outokumpu process at Cira R360/t conversion cost and contained a max of 1,6% Carbon;
  • furnace reductant mix consists of approximately: 45% coke, 10% char and 45% anthracite;
  • the newly developed porous agglomerated pellets according to this disclosure were designed to agglomerate carbon and chromite ore into a pellet.
  • the close proximity of the carbon and ore particles in the pellet proved to have significant technical advantages over the conventional prior art pellets.
  • the results from small furnace tests at RaySA show the following results and impact on FeCr production costs:
  • porous agglomerated pellets of the disclosure agglomerate Cr ore and contain +-20% anthracite;
  • anticipated furnace reductant mix should be: 15% coke, 0% char and 5% anthracite;
  • furnace throughput is 16% higher due to lower electricity consumption (furnace output is limited due to furnace availability and specific energy consumption of the raw material) ;
  • the unit consumption of the porous agglomerated pellets of the disclosure is higher than the furnace, as it contains 20% anthracite (same amount of Cr units per tonne FeCr); 3. carbon is supplied to the furnace via the porous agglomerated pellets of the disclosure and a 75% cost saving on reductants should be achievable;
  • Table 26 Savings calculated for anthracite at RO/t, no delivery cost and IRR at 20%: Table 27 Savings calculated for anthracite at RO/t, no delivery cost and break even:
  • Table 28 shows various data for the tests conducted
  • Table 29 continues to show various data for the tests conducted
  • Table 30 continues to show various data for the tests conducted
  • Table 31 continues to show various data for the tests conducted
  • the average power consumption prior art pellets from Samancor was 7.65 Mwh/ton
  • the average power consumption of the porous agglomerated pellets according to this disclosure (Disclosure Example 1 and Disclosure Example 2) was 6.43 Mwh/ton, which represents an energy saving of 16%.
  • the energy saving of 16% obtained when employing the agglomerated pellets according to the disclosure provided a significant improvement when compared to the prior art Samancor pellets.
  • the Applicant believes that the disclosures of this disclosure at least ameliorate the disadvantages known or described in the prior art in a surprising and unexpected manners.

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Abstract

La divulgation concerne un procédé de production de pastilles agglomérées et s'étend à l'utilisation desdites pastilles agglomérées pour produire du métal réduit et/ou des alliages métalliques réduits. Généralement, lesdites pastilles agglomérées comprennent des fines de minerai et un agent réducteur. La divulgation s'étend aux pastilles elles-mêmes qui sont typiquement poreuses, et à un procédé de production d'un métal et/ou d'un alliage utilisant la pastille.
PCT/IB2024/051033 2023-02-03 2024-02-05 Procédé de production de pastilles agglomérées Ceased WO2024161378A1 (fr)

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CA3056280A1 (fr) * 2017-05-02 2018-11-08 Dawei Yu Reduction carbothermique directe de chromite au moyen d'un catalyseur pour la production d'alliage de ferrochrome
CN112359204A (zh) * 2020-11-06 2021-02-12 佩思国际科贸(北京)有限公司 冷压球团粘合剂、冷压球团及冷压球团的制备方法

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