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WO2025016961A1 - Installation de production électrique de carbonate ou de bicarbonate de sodium - Google Patents

Installation de production électrique de carbonate ou de bicarbonate de sodium Download PDF

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Publication number
WO2025016961A1
WO2025016961A1 PCT/EP2024/069989 EP2024069989W WO2025016961A1 WO 2025016961 A1 WO2025016961 A1 WO 2025016961A1 EP 2024069989 W EP2024069989 W EP 2024069989W WO 2025016961 A1 WO2025016961 A1 WO 2025016961A1
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WO
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Prior art keywords
sodium carbonate
sodium
aqueous solution
crystals
na2co3
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.)
Pending
Application number
PCT/EP2024/069989
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English (en)
Inventor
Jose Manuel DE LA HOZ
Salvador ASENSIO GIMENEZ
Dominique Horbez
Perrine Davoine
Hugo Walravens
Claude Criado
Vasil BONEV
Luca SAONER
Karine Cavalier
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Solvay SA
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Solvay SA
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Publication of WO2025016961A1 publication Critical patent/WO2025016961A1/fr
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D7/00—Carbonates of sodium, potassium or alkali metals in general
    • C01D7/07—Preparation from the hydroxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • B01D61/46—Apparatus therefor
    • B01D61/464—Apparatus therefor comprising the membrane sequence CC
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • B01D61/46—Apparatus therefor
    • B01D61/466—Apparatus therefor comprising the membrane sequence BC or CB
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • B01D61/46—Apparatus therefor
    • B01D61/50—Stacks of the plate-and-frame type
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis

Definitions

  • the present invention relates to a plant for producing sodium carbonate (Na2CO3) and/or optionally sodium bicarbonate (NaHCO3) with reduced fossil carbon dioxide (CO2) emission, by electrodialysis of sodium chloride.
  • the invention relates also to a process for producing sodium carbonate or bicarbonate. It relates also to sodium carbonate and bicarbonate crystals having a low and/or having ‘net zero’ fossil CO2 footprint.
  • the said plant or the related method use an electricity which is partly or totally a ‘green electricity’, or an electricity having a reduced fossil CO2 footprint.
  • this electricity is selected among the group consisting of: hydraulic electricity (hydropower), solar photovoltaic electricity, wind electricity, waste to energy electricity, electricity generated from biomass combustion, electricity generated from biogas combustion, or low fossil CO2 footprint electricity such as from nuclear power.
  • the carbon dioxide (CO2) used for carbonating partially or totally the sodium hydroxide (NaOH) aqueous solution produced by said plant or process is partly, or totally, biogenic, or from biogenic origin, or not deriving from fossil origin.
  • the said method enables sensitively a reduction of the CO2 fossil footprint when producing sodium carbonate or bicarbonate, compared to known processes and is a way to achieve net zero emission for such manufacturing and for the obtained products.
  • Sodium carbonate (Na2CO3), or soda ash, is one of the largest volume essential alkali product made worldwide with a total production in 2022 of more than 65 million tons.
  • Sodium carbonate finds major use in the glass, chemicals, detergents industries, non-ferrous metallurgy, and also in the sodium bicarbonate production industry.
  • Sodium bicarbonate (NaHCO3) is also an essential chemical produced worldwide finding main uses in food and feed, acidic fumes mitigation, and pharmaceuticals uses.
  • the main processes for manufacturing sodium carbonate production are the ammonia synthetic process (also called the SOLVAY ammonia soda process), the ammonium chloride process, and sodium carbonate or bicarbonate ore-based processes.
  • the ammonia synthetic process which encompass one of its alternatives: the ‘dual process’ or HOU process, is the main one used worldwide (two thirds of the world production).
  • This process consists in treating an ammoniacal brine comprising sodium chloride with a gas containing carbon dioxide. From the solution, sodium bicarbonate precipitates, is recovered and calcined to obtain sodium carbonate. Details of said process and of the production of refined sodium bicarbonate, is described in Ullmann's Encyclopedia of Industrial Chemistry (“Sodium carbonate” chapter, Vol.33, pages 299-317, 2012 edition, Wiley-VCH Verlag GmbH & Co, paragraphs 1.4.1 and 1.4.2).
  • ammonia soda process uses, as starting materials, worldwide abundant raw materials, which are: sodium chloride (NaCl) as source of sodium, and lime stone (CaCO3) as source of CO2 (or of the carbonate). And both raw materials are constantly generated and replenished by the nature, on a human timescale. Said sourcing of carbonate in the ammonia soda process may be replaced partially or totally with CO2 from other industries or with biogenic CO2. And limestone (CaCO3), as source of alkalinity when calcined, can be substitute with non-fossil alkalis.
  • NaCl sodium chloride
  • CaCO3 lime stone
  • One limit of the present ammonia soda process is that it uses thermic energy (9.7 to 13.6 GJ/ ton of soda ash), part of it at high temperatures for limestone calcination (above 950°C). This high temperature energy is not easy to substitute with green energy such as fast developing solar photovoltaic or wind electrical power.
  • the main present alternative processes to produce sodium carbonate (soda ash) are those using sodium carbonate-containing minerals, such as fossil Trona, which represent one third of the world production of soda ash.
  • the exploited ores related to alkaline volcanism occur in a limited number of countries: mainly the USA, Turkey, China.
  • US6554990 discloses a process for the manufacture of alkali metal hydroxide such as sodium hydroxide, according to which an electrodialysis cell containing three compartments is used, an aqueous alkali metal halide solution is circulated in a saline compartment of the cell, delimited between an anionic membrane and a cationic membrane, and an alkali metal halide is introduced into an acidic compartment of the cell, delimited between the anionic membrane and a cationic face of a bipolar membrane and an aqueous alkali metal hydroxide solution is extracted from an alkaline compartment of the cell, delimited between the cationic membrane and an anionic face of the bipolar membrane.
  • the present invention relates to a plant for electrically producing sodium carbonate (Na2CO3) comprising: (A) an electrodialyzer cellstack to electrodialyze a sodium chloride (NaCl) aqueous solution into a sodium hydroxide (NaOH) aqueous solution and into a hydrochloric acid (HCl) aqueous solution, wherein the electrodialyzer cellstack is operated in at least 2 production rates on a given time period; (B) carbonating mean(s) to partially or totally carbonate the sodium hydroxide (NaOH) aqueous solution with a gas comprising carbon dioxide (CO2) into a sodium carbonate (Na2CO3) aqueous solution; (C) storage mean(s) of the sodium hydroxide (NaOH) aqueous solution or of the sodium carbonate (Na2CO3)
  • the present plant may be used for producing sodium bicarbonate (NaHCO3), by either adding a crystallization reactor means (D’) to bicarbonate the sodium carbonate aqueous solution from storage mean (C ) and crystallizing sodium bicarbonate crystals.
  • the present invention relates also to the sodium carbonate or bicarbonate crystals produced by the plant or the process of the present invention, wherein the carbon dioxide (CO2) in the gas used to partially or totally carbonate the sodium hydroxide (NaOH) aqueous solution is at least partly or is totally biogenic.
  • the present inventors found surprisingly, that storing the intermediate sodium hydroxide or sodium carbonate aqueous solutions represent a higher energy density per volume or per ton of equivalent electric energy than known accumulators such as classical batteries as lead-acid batteries (25 Wh/kg) or modern lithium-ion batteries (125 Wh/kg). Indeed considering the electric energy needed for electrically producing sodium carbonate from caustic soda needing about 2000 (+/- 30%) kWh/ t caustic soda and close stoichiometrically for the manufacturing of sodium carbonate, a storage of caustic soda or sodium carbonate aqueous solution at 1 to 3 mol of sodium per kg of solution represents an equivalent storage of electrical energy of about 160 to 480 Wh/ kg of solution.
  • the remaining steps of the manufacture of sodium carbonate or bicarbonate represents a minor ratio of the overall consumed energy.
  • the invention enables to run at a stable production rate the crystallization and drying equipment, without over-sizing their volumes and sizes, to compensate the fluctuant availability of the used electricity, in particular when solar or wind energy is used, or when the electrical network has to be balanced during peak-hours. Indeed this fluctuation of available energy is a major problem for industrials processes, and for operators investing in them.
  • the present invention avoids and decreases sensitively the need of ‘strategic materials’ (such as lithium, nickel, cobalt, cupper, cadmium, molybdenum, dysprosium, gallium, and other rare earths) for storing in batteries or other storing means, said green and low fossil CO2 energy.
  • strategic materials are considered limited Earth resources, and represent bottleneck and a limit for the energy transition of the industry to be done progressively by 2050.
  • the production of sodium carbonate using electrodialysis of sodium chloride solutions into caustic soda (NaOH) and hydrochloric acid (HCl) has an electricity consumption sensitively decreased compared to the production of caustic soda and chlorine by membrane electrolysis of sodium chloride solutions.
  • the decrease of energy consumption is down to about 30% less by electrodialysis compared to electrolysis. This eases decreasing the CO2 footprint for the needed electrical power for producing sodium carbonate/ bicarbonate from caustic soda, and to switch to ‘green energy’.
  • electrodialysis of sodium chloride solution into sodium hydroxide with sodium carbonate (in base chamber) gives good synergies with the use of gaseous CO2 from biogenic origin: impurities level requirements in the CO2 gas feeding an electrodialyzer, wherein at least part of the caustic soda (NaOH) is replaced by sodium carbonate with a lower pH, causes less precipitation of divalent and trivalent metal impurities than with sodium hydroxide at same molarity, preserving in this the operation life expectancy of the used membranes in the electrodialyzer.
  • the invention relates also to a method wherein part of the carbonated liquid obtained from carbonating the outlet solution of the base chamber of the above method is further processed to crystallize sodium carbonate crystals or sodium bicarbonate crystals.
  • the invention relates also to sodium carbonate crystals produced with a process using said plant of the invention.
  • the present invention relates also to sodium carbonate crystals in which at least 25% of its carbon content is biogenic carbon, and comprise at most 20 mg calcium or magnesium per kilogram of sodium carbonate crystals.
  • the invention relates also to sodium bicarbonate crystals in which at least 25% of its carbon content is biogenic carbon, and comprise at most 20 mg calcium or magnesium per kilogram of sodium bicarbonate crystals.
  • the invention relates also to sodium carbonate crystals or the sodium bicarbonate crystals made according to the present process and in which at least 25% of the used electrical energy for the electrodialyzer is provided with electricity selected from the group consisting of: hydraulic electricity, solar photovoltaic electricity, wind electricity, waste to energy electricity, electricity generated from biomass combustion, electricity generated from biogas combustion, electricity generated from hydrogen combustion, geothermal electricity, electricity generated by compressed air such as from compressed air stored in underground cavities, nuclear electricity, or mixtures thereof.
  • electricity selected from the group consisting of: hydraulic electricity, solar photovoltaic electricity, wind electricity, waste to energy electricity, electricity generated from biomass combustion, electricity generated from biogas combustion, electricity generated from hydrogen combustion, geothermal electricity, electricity generated by compressed air such as from compressed air stored in underground cavities, nuclear electricity, or mixtures thereof.
  • electrodialysis refers to an electrochemical process which enables to at least partially or totally extract salt ions from one solution through an ion-exchange membrane subjected to an electric field to another solution.
  • electrodialyzer cellstack refers to an equipment wherein an electrodialysis process may be performed. It generally comprises several cells delimited by ion exchange membranes (also called ion perm-selective membranes).
  • ion exchange membranes also called ion perm-selective membranes.
  • the expression ‘to operate the crystallizer equipment in a constant production rate’ intends to mean that the production rate is between +/-10% of a nominal production rate on the given time period considered for the operation of the electrodialyzer cellstack which ‘is operated at the at least 2 production rates on the given time period’.
  • This variation of the nominal production rate within the ‘given time period’ of the crystallization sector is advantageously less than one third, preferably less than 20% of the bigger ratio of the at least 2 production rates of the electrodialyzer cellstack during the given time period.
  • the ‘given time period’ is daily or at least twice daily (such as solar photovoltaic production day / night, or mornings and evenings peak-hours). It may also be one or several days (for instance when considering wind power variability).
  • biogenic carbon’ or ‘biogenic carbonate’ in the present specification is carbon or carbonate whose carbon source was directly in equilibrium with CO2 in the atmosphere.
  • biogenic carbon content is measured according to ASTM D6866- 22 Standard Test Method for determining the biobased content of solid, liquid, and gaseous samples using Radiocarbon Analysis.
  • Said method provides accurate biobased/biogenic carbon content results: the method uses Isotope Ratio Mass Spectrometry (IRMS) techniques to quantify the biobased or biogenic content of a given product, based on carbon 14 isotope measurement of said sample. Instrumental error of the method is typically within 0.1-0.5 % (on relative standard deviation).
  • green energy also called ‘renewable energy’ refers commonly to energy from renewable natural resources that are replenished on a human timescale.
  • solar energy thermo or photovoltaic electricity energy
  • wind power wind power
  • hydropower bioenergy
  • bioenergy derived from biomass (generally from terrestrial of from marine origin)
  • geothermal energy low fossil CO2 footprint energy in complement of the ‘green energy’ listed above, includes heat or cold recovered by heat pumps, and nuclear energy.
  • green electricity also called ‘renewable electricity’ refers commonly to electricity produced from renewable natural resources that are replenished on a human timescale. This encompasses solar electricity (either from thermic origin, or from solar photovoltaic production), wind power, hydropower or hydraulic electricity, marine power, electricity deriving or produced from bioenergy (ie. derived from biomass, and generally from terrestrial of from marine origins), and electricity derived from geothermal energy.
  • feed and bleed mode relates to operating an electrodialyzer cellstack so that an original solution feeds a loop of an aqueous solution feeding a least one chamber of an electrodialyzer cellstack, and said loop of the aqueous solution feeding the at least one chamber collects also at least part of the aqueous solution exiting said chamber, and a bleed is operated on said loop or on the solution exiting the chamber so that the volume of the solution in the loop is controlled to be more or less constant, such as for instance +/-15%.
  • This mode of operation of an electrodialyzer has the interest to operate the electrodialyzer in concentrations range which may be different from the concentrations of the original solution that feeds the loop.
  • the term "purge” refers to a stream withdrawn from a part of a process to limit impurity concentration in this process.
  • sodium chloride derived from: a solar pond salt or from sea refers to a sodium chloride stream withdrawn as such from said solar pond or sea, or to a stream that have been subjected to one or several chemical engineering operation downstream the said crystallizer (such as: purifying, concentrating, thermally transforming, decanting, centrifuging, crystallizing, filtering, evaporating, drying, diluting, heating, cooling operations), or that has been mixed with one or more other stream(s), though keeping at least one part of the sodium chloride withdrawn from said solar pond or sea.
  • impurity refers to a compound different from the sodium carbonate and/or the sodium bicarbonate salt to be produced.
  • carbonating refers to the action of increasing the amount of total carbonate (i.e. carbonate and bicarbonate) of a stream.
  • bicarbonating refers to the action of increasing the amount of bicarbonate of a stream.
  • comprising includes “consisting essentially of” and also “consisting of”.
  • % by weight can be used interchangeably, unless the “%” term is explicitly referred to an other physical unit (such as for instance “% in mole”, or mol. %”, “% in volume” or “vol. %”, etc.).
  • a plurality of elements includes two or more elements.
  • the phrase ‘A and/or B’ refers to the following selections: element A; or element B; or combination of elements A and B (A+B).
  • the phrase ‘A and/or B’ is equivalent to at least one of A and B.
  • the phrase ‘A and/or B’ equates to at least one of A and B.
  • the phrase ‘A1, A2, and/or A3’ refers to the following choices: A1; A2; A3; A1+A2; A1+A3; A2+A3; or A1+A2+A3.
  • the description of a range of values for a variable, defined by a bottom limit, or a top limit, or by a bottom limit and a top limit also comprises the embodiments in which the variable is chosen, respectively, within the value range: excluding the bottom limit, or excluding the top limit, or excluding the bottom limit and the top limit.
  • the description of several successive ranges of values for the same variable also comprises the description of embodiments where the variable is chosen in any other intermediate range included in the successive ranges.
  • the present description also includes another embodiment where a new minimum can be selected between 10 and 15, for example: where "the element X is at least 11", or also where: “the element X is at least 13.74", etc.; 11 or 13.74 being values included between 10 and 15. Also for illustration purpose, when it is indicated that "the element X is generally at most 15, advantageously at most 10", the present description also includes another embodiment where a new maximum can be selected between 10 and 15.
  • an element or composition is said to be included in and/or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components.
  • the choice of an element from a group of elements is described, the following embodiments are also explicitly described: - the choice of two or more elements from the group, - the choice of an element from a subgroup of elements consisting of the group of elements from which one or more elements have been removed.
  • the use of the singular ‘a’ or ‘one’ herein includes the plural unless specifically stated otherwise.
  • FIG.1 shows schematically the function of an electrodialyzer in one embodiment of the plant and process of the present invention.
  • Figure 2 shows schematically an equipment for implementing an embodiment of the plant according to the invention.
  • Electrodialysis refers to electrochemical processes which enable to extract salt ions from one solution through an ion-exchange membrane subjected to an electrical field to another solution.
  • Electrodialysis technologies are known: they are mainly used for electro- separation processes, such as the production of drinkable water, industrial waste water treatments, acid or alkali recovery in metal plating industries, food and pharmaceuticals processes. Electrodialysis principles are well described for instance in Ullmann’s Encyclopedia of Industrial Chemistry (2011 edition, Wiley -VCH Verlag GmbH & Co, Vol.12 pp 273-313, Electrochemistry), or in Technique de l’In con Encyclopedia (2006 edition, Chapter Electrodialyse, J2840 V1, 2006, pp 1-15 and Technical appendixes pp 1-3).
  • the electrodialysis is operated in an electrodialysis cellstack which comprises combining, within a set of adjoining chambers, bipolar ion-exchange membranes with anionic and/or cationic ion-exchange membranes.
  • the anionic membranes are ion-exchange membranes that are permeable to anions and, ideally, impermeable to cations.
  • the cationic membranes are themselves permeable to cations and impermeable to anions.
  • a bipolar membrane is an ion-exchange membrane comprising a cationic face and an anionic face. Such membranes may be produced by joining a cationic membrane and an anionic membrane.
  • the bipolar membrane may for example be produced by the process described in WO 01/79335 in the name of Solvay.
  • the bipolar membrane under the action of a sufficient local electric field, the dissociation of the water that has diffused therein, to its H+ and OH- ions takes places, which ions then migrate on both sides of this membrane. There is therefore acidification in one of the chambers adjacent to the bipolar membrane and alkalization in the other adjacent chamber.
  • Successive bipolar membranes are separated by cationic or anionic monopolar membranes.
  • the electrodialyzer only possesses bipolar membranes and one type of monopolar membranes (cationic or anionic), they are said to have two (types of) chambers.
  • the electrodialyzer used in the method of the present invention possesses preferably only bipolar and anionic membranes.
  • the chamber located between the anionic face of the bipolar membrane and a cationic membrane constitutes a base chamber.
  • this chamber there is a supply of OH- ions originating from the bipolar membrane.
  • the base chamber is preferably fed with an aqueous solution comprising sodium carbonate.
  • the OH- ions supplied from the bipolar membrane will provide alkalinity to absorb then acidic carbon dioxide to form a carbonated solution.
  • the electrodialyzer used in present invention comprises at least three chambers one of which is a salt chamber, a second one is a base chamber and a third one is an acid chamber.
  • a first advantage of the present invention is the decrease of the need to store fluctuating electricity such as the one produced by solar energy or wind energy (highly variable in a daily period or days period such as photovoltaic electricity or wind power electricity that constitutes and will constitutes major sourcing of renewable electricity by 2050.
  • a second advantage of the present invention is the possibility to store electrical energy at a higher energy density (per unit of volume and/or per unit of weight) and with a lower consumption of ‘strategic materials’ for the industrial use of the manufacture of sodium carbonate or sodium bicarbonate, in particular for the manufacture of said products with low fossil CO2 footprint.
  • a third advantage of the present invention is the reduced electrical energy consumption of the plant to produce sodium carbonate or bicarbonate compared to an equivalent plant wherein an electrolyzer would be used rather than an electrodialyzer, decreasing as such the CO2 footprint related to the electrical energy production, whatever the electrical energy origin, easing as such a near- zero CO2 foot-print of the produced sodium carbonate or bicarbonate.
  • a fourth advantage of the present invention is the possibility to use renewable energy or low fossil CO2 footprint energy, replacing high temperature steps of conventional processes (limestone calcination into lime used in both Soda ammonia process and Trona solution mining process using generally coal) and replacing it with electricity having a reduced fossil CO2 footprint, said electricity being preferably selected among the group consisting of: hydraulic electricity, photovoltaic electricity, wind electricity, waste to energy electricity, electricity generated from biogas, electricity generated from biomass combustion, electricity generated from hydrogen combustion, geothermal electricity, electricity generated by compressed air such as from compressed air stored in underground cavities, nuclear electricity, and mixtures thereof. This contributes also to a near-zero CO2 foot-print of the produced sodium carbonate or bicarbonate.
  • a fifth advantage of the present invention is that the crystallization equipment producing sodium carbonate or bicarbonate crystals is operating at a more constant operation conditions (such as the residence time and the growing rate of the crystals in the crystallizers) inducing more stable particle size distribution of the produced sodium carbonate or bicarbonate crystals.
  • the crystallizer (D) in much higher rate generates a higher quantity of fines crystals that constitute problems for main customers uses, such as glass manufacturers (giving less homogeneity in the mixture fed in glass oven, also dust generation when the mixture is loaded in the oven, melted incrustations on the oven surfaces above the melt, and potential sanitary problems for the workers in said areas).
  • problems for main customers uses such as glass manufacturers (giving less homogeneity in the mixture fed in glass oven, also dust generation when the mixture is loaded in the oven, melted incrustations on the oven surfaces above the melt, and potential sanitary problems for the workers in said areas).
  • Such problem is much less sensitive or does not occur for industrials producing caustic soda and chlorine: the electrolyzer stack generates a liquid (sodium hydroxide solution) that is quite less impacted than crystallized solids such as sodium carbonate or bicarbonate by production rate.
  • a sixth advantage of the present invention is to ease CO2 capture from fumes, or from other industries, or from the atmosphere, as the produced sodium hydroxide is highly reactive to capture said CO2 even at low concentration (with CO2 at concentrations lower than 30% vol. or even lower than 10% vol. on dry gases), or even for capturing efficiently CO2 from Earth atmosphere (a.420 ppm by volume) and to increase the circularity of CO2 resources by manufacturing sodium carbonate or bicarbonate.
  • a seventh advantage of the present invention is when CO2 capture, or CO2 from other industries, are not available locally to be able to use limestone (CaCO3) of low purity at 60 to 85% CaCO3 (which is not at all recommended in Ammonia soda process, as mineral impurities of limestone mainly clays and aluminum or iron silicates form with hydrated lime Ca(OH)2 insoluble matters, generating a loss of calcium hydroxide, and heavy incrustations in distillers).
  • limestone CaCO3 of low purity at 60 to 85% CaCO3 (which is not at all recommended in Ammonia soda process, as mineral impurities of limestone mainly clays and aluminum or iron silicates form with hydrated lime Ca(OH)2 insoluble matters, generating a loss of calcium hydroxide, and heavy incrustations in distillers).
  • a eighth advantage of the present invention is to increase by synergy the use of other by-products, such as concentrated brines from desalination discharge from reverse osmosis or from multiple effects evaporation equipment in regions of the world were drinkable water is scarce, and to use it as NaCl raw material for the present method and by so-doing, reducing the stress on existing natural resources.
  • a ninth advantage of the present invention is the possibility to process the sodium hydroxide aqueous solution, or the carbonate solution exiting from the base chamber, even if the said sodium hydroxide or carbonate solution comprises traces of sodium chloride generated by the leakage of chlorides ions from the salt chamber to the base chamber through a cationic membrane of the electrodialyzer, as sodium chloride will be then separated during crystallization of sodium carbonate or bicarbonate and will remain in the mother liquor of the crystallizers.
  • Said sodium chloride then purged with part of sodium carbonate can be recycled upfront the brine (NaCl solution) to be used for purifying said brines in impurities such as calcium, before feeding it to the salt chamber, avoiding or reducing sodium carbonate loss and enabling a useful synergy between electrodialyzer sector and the crystallization of sodium carbonate or bicarbonate. Therefore, the method of the present invention enables to improve the circularity of the use of raw materials such as sodium chloride or limestone, and optimizes by synergy, a decrease of the CO2 fossil footprint of the manufacture of sodium carbonate or bicarbonate, and a decrease of consumption of ‘strategic materials’, paving the way to net zero emission for sodium carbonate or bicarbonate manufacturing.
  • Item 1 Plant for electrically producing sodium carbonate (Na2CO3) comprising: (A) an electrodialyzer cellstack to electrodialyze a sodium chloride (NaCl) aqueous solution into a sodium hydroxide (NaOH) aqueous solution and into a hydrochloric acid (HCl) aqueous solution, wherein the electrodialyzer cellstack is operated in at least 2 production rates on a given time period; (B) carbonating mean(s) to partially or totally carbonate the sodium hydroxide (NaOH) aqueous solution with a gas comprising carbon dioxide (CO2) into a sodium carbonate (Na2CO3) aqueous solution; (C) storage mean(s) of the sodium hydroxide (NaOH) aqueous solution or of the sodium carbonate (Na2CO3) aqueous solution; (D) a crystallizer equipment to concentrate the sodium carbonate (Na2CO3) aqueous solution; (A) an electrodialyzer cellstack to electro
  • Item 2 The plant of item 1, wherein the electrodialyzer (A) uses electricity to electrodialyze the sodium chloride (NaCl) aqueous solution into the sodium hydroxide (NaOH) aqueous solution and into the hydrochloric acid (HCl) aqueous solution, and wherein the electricity is at least partly, and preferably totally, a ‘green electricity’ or has a reduced fossil CO2 footprint, preferably selected among the group consisting of: hydraulic electricity, solar photovoltaic electricity, wind electricity, waste to energy electricity, electricity generated from biomass combustion, electricity generated from biogas combustion, electricity generated from hydrogen combustion, geothermal electricity, electricity generated by compressed air such as from compressed air stored in underground cavities, nuclear electricity, electricity from cogeneration of steam and electricity, or mixtures thereof.
  • Item 3 Item 3.
  • Item 4 Item 4.
  • the plant of any preceding items, wherein the at least 2 production rates ratio expressed as the ratio of a high production rate to a low production rate is at least 1,2 or at least 1,5.
  • Item 5. The plant of any preceding items, wherein the at least 2 production rates ratio expressed as the ratio of a high production rate to a low production rate is at most 5 or at most 3.
  • Item 6. The plant of any preceding items, wherein the said given time period is at least 1 hour, preferably at least 10 hours. Item 6’.
  • the plant of any preceding items, wherein the said given time period is at least 6 hours, preferably at least 12 hours.
  • Item 7. The plant of any preceding items, wherein the said given time period is at most one week, preferably at most 1 day.
  • the plant of any preceding items, wherein the electrodialyzer cellstack (A) to electrodialyze the sodium chloride (NaCl) aqueous solution into a sodium hydroxide (NaOH) aqueous solution and a hydrochloric acid (HCl) aqueous solution comprises at least 2 chambers: a base chamber wherein the sodium hydroxide (NaOH) aqueous solution is produced and an acid chamber wherein the hydrochloric acid (HCl) aqueous solution is produced.
  • a base chamber wherein the sodium hydroxide (NaOH) aqueous solution is produced
  • an acid chamber wherein the hydrochloric acid (HCl) aqueous solution is produced.
  • the electrodialyzer cellstack (A) comprises at least 3 chambers: a base chamber, an acid chamber, and a salt chamber wherein the sodium chloride is fed and wherein the sodium ions are permeated to the base chamber through a cation permselective membrane and the chloride ions are permeated to the acid chamber through an anion permselective membrane.
  • Item 10 The plant of any preceding items, wherein the electrodialyzer cellstack (A), can be, or is, operated in a feed and bleed mode. Item 11.
  • the crystallizer equipment (D) to concentrate the sodium carbonate (Na2CO3) aqueous solution and to produce sodium carbonate (Na2CO3) crystals and a mother liquor comprises: - an optional (D1) pre-evaporator means such as: a falling film evaporator or a forced circulation evaporator, to remove at least part of the water of the sodium carbonate (Na2CO3) aqueous solution; - (D2) crystallizer means such as a sodium carbonate anhydrous (Na2CO3) crystallizer, or a sodium carbonate monohydrate (Na2CO3.H2O) crystallizer, or a sodium carbonate decahydrate (Na2CO3.10H2O) crystallizer, or a sodium sesquicarbonate (Na2CO3.NaHCO3.2H2O) crystallizer.
  • D1 pre-evaporator means such as: a falling film evaporator or a forced circulation evaporator, to remove at least part of the water of the sodium carbonate (Na
  • the crystallizer equipment (D) further comprises: - an optional (D1) pre-evaporator means, and - (D2) a sodium carbonate decahydrate (Na2CO3.10H2O) crystallizer, - a separation means (E2) to separate sodium carbonate decahydrate (Na2CO3.10H2O) crystals from their mother liquor, - a melting device to melt the sodium carbonate decahydrate (Na2CO3.10H2O) crystals into a purified sodium carbonate solution, - (D2’) a sodium carbonate monohydrate (Na2CO3.H2O) crystallizer fed with the purified sodium carbonate solution to produce (Na2CO3.H2O) crystals and their mother liquor, - (E) a separation means to separate sodium carbonate monohydrate (Na2CO3.H2O) crystals from their mother liquor.
  • the crystallizer equipment (D) further comprises: - an optional (D1) pre-evaporator means, and - (D2) a sodium carbonate de
  • This item 12 embodiment comprising a sodium carbonate decahydrate crystallizer and then a sodium carbonate monohydrate crystallizer is particularly advantageous when the produced sodium carbonate (Na2CO3) aqueous solution comprises high levels of sodium chloride (NaCl), such as at least 1.0 wt.% or at least 1.5 wt.% NaCl.
  • NaCl sodium chloride
  • This embodiment enables to reduce the energy consumption of such configuration for concentrating the NaCl impurity and others (Na2SO4, KCl, ...) and reducing sodium carbonate in the final purge compared to a configuration according to the following item 13, comprising a monohydrate crystallizer and then the treatment of the purge of the monohydrate crystallizer in a decahydrate crystallizer.
  • Item 13 comprising a monohydrate crystallizer and then the treatment of the purge of the monohydrate crystallizer in a decahydrate crystallizer.
  • the crystallizer equipment (D) further comprises: - an optional (D1) pre-evaporator means, and - (D2’) a sodium carbonate monohydrate (Na2CO3.H2O) crystallizer fed with the sodium carbonate solution to produce sodium carbonate monohydrate (Na2CO3.H2O) crystals and their mother liquor, - (E) a separation means to separate sodium carbonate monohydrate (Na2CO3.H2O) crystals from their mother liquor, - a purge means of at least part of the mother liquor from the sodium carbonate monohydrate crystallizer, - (D2) a sodium carbonate decahydrate (Na2CO3.10H2O) crystallizer fed with the purged mother liquor from the sodium carbonate monohydrate crystallizer, - a separation means (E’) to separate sodium carbonate decahydrate (Na2CO3.10H2O) crystals from their mother liquor, - a melting device to melt the sodium carbonate decahydrate (Na)
  • This item 13 embodiment comprising first a sodium carbonate monohydrate crystallizer and then a sodium carbonate decahydrate crystallizer for treating the mono purge, recovering most of the sodium carbonate from the purge, and concentrating the purge in sodium chloride, is particularly advantageous when the produced sodium carbonate (Na2CO3) aqueous solution out of the electrodialyzer, and feeding the mono crystallizer, comprises lower levels of sodium chloride (NaCl), such as: at most 1.5 wt.% or even at most 1.0 wt.% NaCl.
  • the mother liquor from the crystallizer equipment comprises dissolved sodium carbonate and dissolved sodium chloride
  • the crystallizer equipment (D) or the separation means (E) comprises a purge means for purging at least part of the mother liquor from the crystallizer equipment ( (D), (D2), or (D2’) ) and a recycling means of the least part of the purged mother liquor, to recycle the at least part of the mother liquor to a sodium chloride brine purification module or to the EDIA cellstack or upfront the EDIA cellstack to recover at least part of the sodium chloride of the purged mother liquor and to electrolyze it into sodium hydroxide and/or hydrochloric acid.
  • the crystallizer equipment (D) or the separation means (E) comprises a purge means for purging at least part of the mother liquor from the crystallizer equipment (D), (D2), or (D2’) ) and a recycling means of the least part of the purged mother liquor, to recycle the at least part of the mother liquor to a sodium chloride
  • Process for producing sodium carbonate (Na2CO3) crystals or sodium bicarbonate (NaHCO3) crystals from a sodium chloride (NaCl) solution comprising the following steps : (i) optionally pre-treating the sodium chloride (NaCl) solution in removing at least part of impurities selected from the group consisting of: insolubles, calcium, magnesium, heavy metals, fluoride, bromide, iodide, sulfate, organics and combination thereof to obtain an optional pre-treated sodium chloride solution; (ii) electro-dialyzing in an electrodialyzer cellstack (A), the sodium chloride solution or the optional pre-treated sodium chloride solution into a sodium hydroxide (NaOH) aqueous solution and into a hydrochloric acid (HCl) aqueous solution, wherein the electrodialyzer cellstack is operated in at least 2 production rates on a given time period; (iii) carbonating partially or totally the sodium hydroxide (NaOH) aque
  • the carbon dioxide (CO2) in the gas used for carbonating partially or totally the sodium hydroxide (NaOH) aqueous solution, or the sodium carbonate aqueous solution is partially or totally biogenic, or is CO2 captured from the air.
  • the carbon dioxide (CO2) may result from concentration or purification processes which increase its CO2 concentration. This may include concentration processes such as: an amine based process, an ammonia based process, a Pressure Swing Absorption (PSA) process, a Temperature Swing Absorption (TSA) process, a cryogenic process, or a membrane process.
  • concentration processes such as: an amine based process, an ammonia based process, a Pressure Swing Absorption (PSA) process, a Temperature Swing Absorption (TSA) process, a cryogenic process, or a membrane process.
  • Item 21 The process of any the items 15 to 20, wherein the sodium chloride derives from: a seawater desalination process, preferably from a reverse osmosis desalination process.
  • Item 22 The process of any of the preceding items, wherein the sodium chloride derives from a geological salt cavity, or is an industrial crystallized salt.
  • Item 23 The process of any of the preceding items, wherein the sodium chloride derives from a geological salt cavity, or is an industrial crystallized salt.
  • the sodium chloride (NaCl) solution is pre-treated at a step (i), and the step (i) comprises pre-treating a brine comprising sodium chloride, water, and impurities selected among: insolubles, soluble calcium and/or soluble magnesium, and optional soluble metals, - in a primary purification step (i1) wherein sodium carbonate is added, preferably as part of a purge of the crystallizing step (v) comprising sodium carbonate aqueous solution, to precipitate calcium carbonate and remove at least partly soluble calcium from the brine, and/or wherein a sodium hydroxide aqueous solution is added, preferably as part of the one produced by the electrodialyzer cell-stack at step (i1), or as part of the sodium carbonate aqueous solution comprising sodium hydroxide of the carbonation step (iii) to precipitate magnesium hydroxide, removing the insolubles, the precipitated calcium carbonate and/or the precipitated magnesium hydroxide
  • Item 24 The process of any preceding items wherein the sodium hydroxide (NaOH) aqueous solution from step (ii) or the sodium carbonate (Na2CO3) aqueous solution from steps (iii) or (iv) comprises at least 1 mol alkaline Na+ (from NaOH or from Na2CO3) per liter, and comprises preferably at most 3 mol alkaline Na+ per liter.
  • Item 25 The sodium carbonate or bicarbonate crystals produced by the process of any preceding items, wherein the carbon dioxide (CO2) in the gas used for carbonating partially or totally the sodium hydroxide (NaOH) aqueous solution is at least partly biogenic.
  • CO2 carbon dioxide
  • Sodium carbonate crystals or sodium bicarbonate crystals wherein at least 25 wt.% of its carbon content is biogenic, preferably at least 80 wt. % of its carbon content is biogenic; and - and comprising at most 20 mg calcium and / or at most 20 mg magnesium per kilogram of crystals, preferably at most 8 mg calcium and / or at most 8 mg magnesium per kilogram of crystals.
  • Item 27 Sodium carbonate crystals or sodium bicarbonate crystals according to the preceding items: - wherein at least 95 wt.% or at least 99 wt% of its carbon content is biogenic, or is CO2 captured from the air.
  • Sodium carbonate crystals or sodium bicarbonate crystals according to one of the items 25 to 31 wherein the crystals have a size fraction passing a 125 ⁇ m sieve is less than 8 wt%, preferably less than 4 wt%, more preferably less than 1 wt. %.
  • the following examples are intended only to exemplify the invention and are not intended to limit the scope of the claimed invention.
  • FIG.1 shows schematically the function of the electrodialyzer in one embodiment of the process of the present invention, illustrating an advantageous configuration of the electrodialysis cellstack.
  • the electrodialyzer cellstack comprises a succession of 3 chambers: base chamber, acid chamber, salt chamber.
  • An aqueous solution advantageously comprising sodium carbonate is fed into the base chamber, bounded between a cationic permselective membrane and an anionic permselective face of a bipolar membrane.
  • An aqueous solution is fed into the acid chamber, said acid chamber being bounded between a cationic face of the bipolar membrane and an anionic membrane
  • An aqueous solution comprising sodium chloride is fed into the salt chamber, said salt chamber being bounded between one anionic membrane and one cationic membrane
  • sodium hydroxide (NaOH) and in the acid chamber hydrochloric acid (HCl) are generated, by splitting water molecules with the bipolar membrane into hydroxide anions (OH-) in the base chamber and into hydronium cations (H+) in the acid chamber, transferring sodium ions (Na+) to the base chamber through the cation selective membrane and transferring chloride ions (Cl-) to the acid chamber through the anionic membrane by using an electrical tension between the salt chamber and the acid chamber,
  • An aqueous outlet solution comprising sodium hydroxide and sodium carbonate from the base chamber is removed and cane be used as illustrated in Example 2.An aqueous outlet solution comprising sodium chloride depleted in sodium chloride
  • Example 2 Figure 2 (Fig.2) schematically shows an installation for implementing an advantageous embodiment of the plant or of the process according to the invention.
  • the installation shown schematically in Figure 2 comprises an electrodialysis cellstack (A) [also (1) in the figure], a carbonation tower (B) [also (2) in the figure], a storing mean (C) for the sodium hydroxide and sodium carbonate aqueous solution, an evaporator-crystallizer (D) [also referenced (3) in the figure] and a dryer (4).
  • the electrodialysis cell is a multi-chamber cell type with a combination of cation, anion, and bipolar membranes comprising acid, base and salt compartments.
  • Cells of this type are well known in electrolytic technique and widely used for the industrial production of aqueous solutions of a base and an acid starting from aqueous solutions of the corresponding salt (Ullmann’s Encyclopedia, Sodium Hydroxide, p.376).
  • an aqueous solution of sodium chloride (6) is introduced into the salt compartment of the electrodialysis cell, while a diluted aqueous hydrochloric acid solution (9) and a diluted aqueous solution comprising sodium carbonate and caustic soda (11) are introduced into the acid and base compartments of the cell, respectively.
  • hydrochloric acid and sodium hydroxide are generated in the acid and base compartments, respectively, while sodium chloride is gradually depleted in the salt compartment.
  • An aqueous outlet solution comprising sodium chloride depleted in sodium chloride is extracted from the salt chamber.
  • an aqueous solution comprising sodium carbonate and sodium hydroxide enriched in sodium hydroxide and a hydrochloric acid solution enriched in hydrochloric acid are extracted from the base and the acid compartment, respectively.
  • the aqueous solution of sodium chloride fed to the electrodialysis cell and the outlet aqueous solution depleted in sodium chloride extracted from the cell constitute a sodium chloride solution loop.
  • the outlet aqueous solution depleted in sodium chloride is partially purged (7).
  • Another aqueous solution of sodium chloride (5) is fed to the loop in order to raise the sodium chloride concentration.
  • the aqueous solution of hydrochloric acid fed to the electrodialysis cell and the outlet aqueous solution enriched in hydrochloric acid extracted from the cell constitute a hydrochloric acid solution loop.
  • the outlet aqueous solution enriched in hydrochloric acid is partially purged from the system for downstream use (10).
  • Water (8) is fed to the hydrochloric acid solution loop in order to regulate the hydrochloric acid concentration.
  • the aqueous solution comprising sodium carbonate and sodium hydroxide fed to the electrodialysis cell and the outlet aqueous solution comprising sodium carbonate and sodium hydroxide enriched in sodium hydroxide extracted from the cell constitute a sodium hydroxide and sodium carbonate solution loop.
  • a first portion of the outlet aqueous solution comprising sodium carbonate and sodium hydroxide enriched in sodium hydroxide extracted from the cell (12) is recycled in the sodium hydroxide and sodium carbonate solution loop, wherein another portion (13) is sent to a carbonation tower (B) also referenced (2), where a gas comprising carbon dioxide (14) of which 82% of its carbon content is biogenic, generated from a waste to energy unit using waste biomass material, and said CO2 gas is to the carbonation tower to obtain a carbonated liquid, wherein the sodium hydroxide is transformed into sodium carbonate and water.
  • Said carbonated liquid is partly recycled in the sodium hydroxide and sodium carbonate solution loop (15), wherein another portion is sent to a storing tank (C) wherein the sodium carbonate aqueous solution is stored so that the sections (A) and (B) using fluctuating energy as much as available, producing variable flow thereto of carbonated solution more independent from sections (D) and (E) operating then at constant nominal production rate.
  • a storing tank (C) wherein the sodium carbonate aqueous solution is stored so that the sections (A) and (B) using fluctuating energy as much as available, producing variable flow thereto of carbonated solution more independent from sections (D) and (E) operating then at constant nominal production rate.
  • This enables to decrease investment for delivering a constant sourcing of electricity for sodium carbonate or bicarbonate crystals.
  • Part of the sodium carbonate aqueous solution is sent (17) to an evaporator-crystallizer (D) (also referenced (3) in the figure). In this unit, the slurry is subjected to controlled e
  • a substantially saturated brine (5), containing, per kg, 250 g of sodium chloride are fed to the sodium chloride solution loop.
  • 22 t/h of an aqueous solution of sodium chloride (6) containing, per kg, 155 g of sodium chloride is introduced into the salt compartment of the electrodialysis cell.
  • the following are obtained: - 20.9 t/h of depleted or dilute brine, containing per kg, 150 g of sodium chloride; - 20.5 t/h of an enriched hydrochloric acid solution, containing per kg, 40 g of hydrochloric acid; - 23.8 t/h of an aqueous solution comprising sodium carbonate and sodium hydroxide containing per kg, 134 g of sodium carbonate and 50 g sodium hydroxide.
  • 3.2 t/h of water (8) are fed to the hydrochloric acid solution loop.
  • 3.3 t/h of a hydrochloric acid solution containing, per kg, 40 g of hydrochloric acid (10) are extracted from the hydrochloric acid solution loop.
  • 0.15 t/h of depleted or dilute brine, containing, per kg, 150 g of sodium chloride are extracted from the sodium chloride solution loop.
  • 20.5 t/h of the outlet aqueous solution comprising sodium carbonate and sodium hydroxide are recycled to sodium hydroxide and sodium carbonate solution loop (12), wherein 3.3 t/h are sent to a carbonation tower (2).
  • 90 kg/h of carbon dioxide (14) are also fed to obtain a carbonated liquid containing, per kg, 180 g of sodium carbonate.
  • 1 t/h of carbonated liquid (16) are stored in a storage tank insulated. Part of carbonated liquid (17) is withdrawn from the storage tank C and introduced at a constant flow of 0.8 t/h into the evaporator-crystallizer (3), and where 134 kg/h of sodium carbonate crystals (17) are produced and separated from the mother liquor (18), and sent to a dryer (4) obtaining 128 kg/h of dried sodium carbonate crystals (19).
  • the mother liquor (18) is recycled mostly up-front at the evaporator-crystallizer (3) feed, except a part of it which is purged from the crystallizer to control and limit the concentration of soluble impurities (mainly sodium chloride and sulfate) in the mother liquor present in the crystallizer (3) and adjusted according to the specifications content of said impurities to be achieved in the dried sodium carbonate crystals (20).
  • soluble impurities mainly sodium chloride and sulfate
  • This represents a production flow (16) of 0.7 t/ h of sodium carbonate solution feeding the storage tank for 16 hours.
  • the excess of the storage volume needed corresponds to the 0.25 x 0.8 t/ h x 8 hours and represents 1.6 t of sodium carbonate solution to be stored to feed constantly the crystallizer equipment which is reasonable. This results in a constant crystal particles size distribution meeting consumer specifications.
  • the purge is recycled at the brine purification sector wherein sodium chloride brine is purified before feeding the electrodialysis cell (1). This enables to valorize the sodium chloride part of the purge and be electrolyzed and so avoiding to be lost.
  • Sodium carbonate and optionally sodium sulfate are also valorized and not lost, as they can be used as precipitating agent of calcium ions (as gypsum and/or calcium carbonate) at the purification sector of the raw brine comprising sodium chloride and its impurities, before being purified and then used in the electrodialysis cell (1) feeding the salt chamber as stream (6).
  • This enables to achieve a sharp decrease in purged brine quantity and to approach a near-zero loss of sodium carbonate in the purged mother liquor from the evaporator- crystallizer (3) sector.
  • the sodium carbonate produced with the obtained carbonated solution generated in the electrodialyzer is of excellent purity in complement of the good particle size distribution stability and characteristics.
  • the sodium carbonate crystals obtained on the 24 hours’ time period have a calcium (Ca) and a magnesium (Mg) content of less than 20 ppm, an iron content (Fe) of less than 10 mg/ kg, with most samples taken every hour having respectively less than 8 ppm regarding calcium, same for magnesium content, and less than 4 ppm for the iron content.
  • a manufacturing of sodium bicarbonate crystals from the outlet aqueous solution comprising sodium hydroxide and sodium carbonate would enable to obtain comparable crystal purities with the used carbon dioxide gas, as the occlusion of impurities are similar for sodium carbonate and bicarbonate, with generally a favorable impurity split in crystals and mother liquor for sodium bicarbonate compared to sodium carbonate crystals for said impurities.
  • the obtained sodium carbonate crystals present surprisingly a good particle size distribution, with less than 10% in weight of the crystals above 1100 ⁇ m, a medium particle size in weight (D50) comprised between 480 ⁇ m and 620 ⁇ m on the 24 hours, with a size fraction passing a 125 ⁇ m sieve of less than 1 wt. % for most samples.
  • D50 medium particle size in weight
  • the attrition behavior of such sodium carbonate is similar to the one of the soda ammonia process, meeting market requests.
  • the fossil CO2 footprint of said sodium carbonate is reduced when using green electricity of a factor 3 to more than 5 compared to existing soda ammonia process and trona ore process.

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Abstract

Est divulguée une installation de production électrique de carbonate ou de bicarbonate de sodium, pour la production électrique de carbonate de sodium (Na2CO3), comprenant : (A) un empilement d'électrodialyseurs pour électrodialyser une solution aqueuse de chlorure de sodium (NaCl) en une solution d'hydroxyde de sodium (NaOH) et en une solution d'acide chlorhydrique (HCl), l'empilement d'électrodialyseurs fonctionnant à au moins 2 vitesses de production sur une période de temps donnée ; (B) un/des moyen(s) de carbonatation pour carbonater partiellement ou totalement la solution de NaOH avec du CO2 en une solution de Na2CO3 ; (C) un/des moyen(s) de stockage de la solution de NaOH ou de la solution de Na2CO3 ; (D) un équipement de cristallisation pour concentrer la solution de Na2CO3 et pour produire des cristaux de Na2CO3 et une liqueur mère ; les moyens de stockage de la solution de NaOH ou de la solution de Na2CO3 étant d'un volume suffisant pour faire fonctionner l'équipement de cristallisation à une vitesse de production constante au cours de ladite période.
PCT/EP2024/069989 2023-07-14 2024-07-15 Installation de production électrique de carbonate ou de bicarbonate de sodium Pending WO2025016961A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4219396A (en) * 1979-08-03 1980-08-26 Allied Chemical Corporation Electrodialytic process
CA2009616A1 (fr) * 1988-10-13 1991-08-08 Jochen Bosse Methode de production de sels d'acide carbonique de metaux alcalins
WO2001079335A1 (fr) 2000-04-19 2001-10-25 Solvay (Societe Anonyme) Procede de fabrication d'une membrane bipolaire et utilisation de la membrane bipolaire ainsi obtenue
US6554990B1 (en) 1993-12-24 2003-04-29 Solvay (Societe Anonyme) Process for the manufacture of alkali metal hydroxide

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4219396A (en) * 1979-08-03 1980-08-26 Allied Chemical Corporation Electrodialytic process
CA2009616A1 (fr) * 1988-10-13 1991-08-08 Jochen Bosse Methode de production de sels d'acide carbonique de metaux alcalins
US6554990B1 (en) 1993-12-24 2003-04-29 Solvay (Societe Anonyme) Process for the manufacture of alkali metal hydroxide
WO2001079335A1 (fr) 2000-04-19 2001-10-25 Solvay (Societe Anonyme) Procede de fabrication d'une membrane bipolaire et utilisation de la membrane bipolaire ainsi obtenue

Non-Patent Citations (6)

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Title
"Sodium carbonate", vol. 33, 2012, WILEY-VCH VERLAG GMBH, article "Ullmann's Encyclopedia of Industrial Chemistry", pages: 299 - 317
"Technique de l'Ingénieur Encyclopedia", 2006, pages: 1 - 15
"Ullmann's Encyclopedia of Industrial Chemistry", vol. 12, 2011, WILEY -VCH VERLAG GMBH, pages: 273 - 313
ANONYMOUS: "Inorganic Trace Analysis", 31 December 2017 (2017-12-31), XP093212062, Retrieved from the Internet <URL:https://prod-edam.honeywell.com/content/dam/honeywell-edam/pmt/rc/en-us/website/brochures/traceselect/pmt-rc-traceanalysis-brochure-digital.pdf> [retrieved on 20241007] *
TECHNICAL APPENDIXES, pages 1 - 3
ULLMANN'S ENCYCLOPEDIA, SODIUM HYDROXIDE, pages 376

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