RU2564806C2 - Method of producing ultrapure lithium carbonate from technical-grade lithium carbonate and apparatus therefor - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. A method of producing ultrapure lithium carbonate from technical-grade Li₂CO₃ includes conducting a carbonisation process with fourfold excess lithium carbonate to obtain a lithium bicarbonate solution. The residual solid Li₂CO₃ after the carbonisation process is separated from the lithium bicarbonate solution and returned in the form of a thickened pulp to the process of preparing the initial Li₂CO₃ pulp. Insoluble impurities are filtered off from the lithium bicarbonate solution, followed by ion-exchange purification of the filtrate from impurity cations and decarbonisation of the lithium bicarbonate solution while heating to release carbon dioxide gas. Lithium carbonate pulp is obtained. Lithium carbonate is separated from the carbonate mother solution, washed with hot water and dried.

EFFECT: invention enables to avoid mechanochemical grinding, reduces the power consumption of the carbonisation process 1,6-fold, increases efficiency of carbonisation 1,8-fold and output of ultrapure Li₂CO₃ to 98,6%, and enables to conduct the process of producing ultrapure Li₂CO₃ in a continuous mode.

7 cl, 2 dwg, 5 tbl, 4 ex

Description

The invention relates to chemical technology for producing ultrapure inorganic compounds and can be used in chemical, metallurgical and electrochemical industries.

A known method of producing ultrapure lithium carbonate from natural lithium containing sodium chloride type brines (Pat. US No. 6207126), according to which the natural sodium chloride type brine is evaporated to a lithium content of not less than 6 wt.%, Sequentially salting out NaCl, KCl, KCl from the brine · MgCl ₂ · 6H ₂ O. The lithium concentrate thus obtained is purified from impurities of boron, magnesium, calcium, sulfate ions and treated with a soda solution to precipitate lithium carbonate by the reaction:

Precipitated lithium carbonate containing not less than 99% wt. of the main substance, separated from the mother liquor, the mother liquor is mixed with evaporated brine, and from the obtained lithium carbonate after washing with demineralized water, an aqueous pulp is prepared (the solids content is 3-5% wt.), which is treated with carbon dioxide at a temperature of 30-40 ° C and atmospheric pressure, converting the solid phase Li ₂ CO ₃ in a solution of lithium bicarbonate. The resulting solution (LiHCO ₃ content _of 7-8% wt.) Is sent to a decarbonizer, where at a temperature of 70-95 ° C and LiHCO ₃ decomposition is carried out with stirring, accompanied by the formation of a solid phase Li ₂ CO ₃ and carbon dioxide returned to the carbonization operation. After separation from the mother liquor and washing with demineralized water and drying, it is guaranteed to obtain high-purity lithium carbonate, composition (% wt.): Li ₂ CO ₃ >99.9; Na <0.001, Mg <0.0007; K <0.00025; Ca <0.012; B <0.0001; Al <0.0002; As <0.0001; Fe <0.0001; Si <0.001; Zn <0.00005; SO ₄ <0.037; Cl <0.005.

To obtain ultrapure lithium carbonate composition (% wt.): Li ₂ CO ₃ >99.995; Na <0.0002, Mg <0.00001; K <0.00015; Ca <0.0007; Al <0.0002; As <0.0001; Fe <0.0001; Si <0.00011; Zn <0.000014; SO ₄ <0.003; Cl <0.005, a LiHCO ₃ solution produced at the stage of carbonization of the pulp Li ₂ CO ₃ , is subjected to purification on an Amberlite IRC-718 ion-exchange resin before the decarbonization operation.

The disadvantage of this method is the inability to obtain lithium carbonate from natural lithium brines of magnesium chloride, calcium chloride or chloride calcium-magnesium types by this method, since it is impossible to evaporate lithium concentrates suitable for the deposition of lithium carbonate with soda. The reason for this is the lack of ability of these types of brines to concentrate on lithium due to the inevitability of lithium salting out in the form of double chloride salts: (LiCl · MgCl ₂ · 6H ₂ O and LiCl · CaCl ₂ · 5H ₂ O) with an increase in its concentration in brines with a high MgCl content ₂ and CaCl ₂ . In addition, the yield of ultrapure (content. Li ₂ CO ₃ ≥99.995%) and high-purity lithium carbonate (content. Li ₂ CO ₃ ≥99.9%) by this method is low and corresponds to 12% of the mass. and 48% of the mass.

A method of producing lithium carbonate of high purity from lithium-bearing natural brines, including the separation of lithium chloride concentrate from brine in the form of an aqueous solution of lithium chloride by sorption-desorption enrichment of brine with lithium on a granular selective sorbent based on LiCl · 2Al (OH) ₃ · mH ₂ O DGAL-Cl (a double inorganic compound of lithium and aluminum with a defective structure) eliminates the disadvantage of the previous method, because in this case, for the production of ultrahigh-purity lithium carbonate, lithium-bearing brine of any of the types currently known (Patent RU No. 2283283) can be used as a feedstock. In addition, as a precipitant of lithium carbonate from lithium concentrate in this method, an aqueous salt pulp is used: NH ₄ HCO ₃ . The precipitation of lithium carbonate occurs in accordance with the following reaction:

The lithium carbonate precipitated by this method, firstly, contains virtually no impurities of sodium and potassium, and secondly, the NH ₄ Cl impurity, which is the main impurity in this product, is easily removed during drying and calcination of Li ₂ CO ₃ (t = 200 ° C ), decomposing by reaction:

In this way, high-purity lithium carbonate is obtained with a yield of 60%, provided that the LiCl solution used to precipitate LiCl was first subjected to reactive and then ion-exchange purification of impurities.

To produce ultrapure Li ₂ CO ₃ from this carbonate, it is also carbonized using CO ₂ released in the precipitation stage (reaction 2), and solid-state Li ₂ CO ₃ is converted into a lithium bicarbonate solution, followed by heating, decomposition of LiHCO ₃ into Li ₂ CO ₃ , CO ₂ and H ₂ O and the selection of the solid phase of ultrapure Li ₂ CO ₃ . The yield of such a product is 36-53%.

The main disadvantage of this method are: the use of a LiCl solution as the initial lithium reagent, which leads to a complex deposition scheme of Li ₂ CO ₃ , due to the need to process the mother liquor of the deposition (NH ₄ Cl) and the high consumption of NH ₄ HCO ₃ at a relatively low (not higher than 73 %) the degree of deposition of Li ₂ CO ₃ . In addition, the yield of ultrapure Li ₂ CO ₃ obtained is entirely determined by the purity of the LiCl solution used.

A known method of producing highly pure lithium carbonate from technical Li ₂ CO ₃ (US Pat. RU No. 2223157), including mechanically activation grinding of technical lithium carbonate, carbonization of water pulp mechanically activated lithium carbonate with carbon dioxide at a temperature of 5-25 ° C and a pressure of 0.5 ATM. and stirring to obtain a lithium bicarbonate solution, filtering a lithium bicarbonate solution, purifying a lithium bicarbonate solution on a synthetic cation exchange resin based on vinyl pyridine compounds or sulfa acids, or complex chelating compounds, for example, resin: Purolite S-940, Lewatit TP 208, VPK, decarbonization of purified LiHCO ₃ solution under heating with separation of the solid phase ultrapure lithium carbonate, lithium carbonate ultrapure separation from the mother liquor, washing with hot water and drying, the return of the mother liquor and preparing pulp technical operation of lithium carbonate and carbonation with repetition of the process cycle of operations up to the ion exchange treatment and calcined to release solid high purity lithium carbonate and returning the mother liquor in the next process head recycled. The mother liquor of the decarbonization operation is removed from the process when the precipitated lithium carbonate in terms of impurity content does not meet the requirements of the qualification “high-purity”. According to this method, the yield of ultrapure Li ₂ CO ₃ is 11-14%, and the yield of high purity Li ₂ CO ₃ is 32-36%. This method is the closest to the proposed solution and our choice as a prototype.

The disadvantages of the method are: high energy intensity of the process due to the use of mechanochemical grinding of Li ₂ CO ₃ , reduced carbonization rate of Li ₂ CO ₃ due to the processing of lithium carbonate pulp with carbon dioxide under low pressure (0.5 at.) In the reaction zone, low yield of ultrapure Li ₂ CO ₃ .

A known installation for producing ultrapure Li ₂ CO ₃ from industrial lithium carbonate (US Pat. US No. 6207126), including a metering device and supply Li ₂ CO ₃ articulated with a reactor for the preparation of pulp connected to one of the upper pipe by pipelines with a source of demineralized water and the lower pipe through the pulp pump with the upper pipe of the cooled reactor-carbonizer equipped with a stirrer; baffle crystal Li ₂ CO _3, heated reactor calciner equipped with a stirrer, one of the upper pipes which successively through the heat exchanger, a filter and a pump through a conduit connected to the nozzle output solution LiHCO _{3-carbonation} reactor, another upper carbon dioxide output pipe coupled to the nozzle carbon dioxide inlet to the carbonization reactor and a carbon dioxide source, and the lower outlet pipe of the pulp of the decarbonization reactor-decarbonizer is connected through a pump through a pipeline device separating the solid and liquid phases combined nozzle solids discharge to a container receiving ultrapure Li ₂ CO _3, nozzle output mother liquor decarbonation means of a conduit through the heat exchanger with one of the top nozzle-carbonation reactor or directly to the receiver-accumulator relief mother decarbonization solution a wash water inlet port through a pipeline with a wash water source and an outlet for the outlet of the spent wash solution with an accumulator receiver botanical wash solution.

This installation on the technical nature and the achieved result is the closest solution to the claimed method and the installation for its implementation was taken by us as a prototype. The main disadvantages of the prototype is the inability to conduct the process of obtaining high-yield ultrafine lithium carbonate.

The main distinguishing feature of the proposed method for producing ultrapure lithium carbonate from industrial Li ₂ CO ₃ and the installation for its implementation are: the process of carbonization of the pulp Li ₂ CO ₃ with obtaining a solution of LiHCO ₃ in excess lithium carbonate, providing an increase in the contact surface of the phases and the maximum concentration of carbon dioxide a percolation zone carbonation reaction, stable in time from the commencement of carbonation process to its closure when the 100% degree of utilization of CO ₂ and deep utilization of lithium from the mother liquor decarbonization process, followed by processing in ultrapure lithium carbonate. Obtaining ultrapure Li ₂ CO ₃ from industrial lithium carbonate by the proposed method in comparison with the prototype allows, firstly, to exclude the operation of mechanochemical grinding from the process and reduce the energy intensity of the process by 1.6 times, and secondly, to increase the productivity of the carbonization process by 1.8 times, thirdly, to conduct the process in a continuous mode; fourthly, to increase the yield of ultrapure Li ₂ CO ₃ to 98.6%.

SUMMARY OF THE INVENTION

When developing the inventive method, a technical lithium carbonate manufactured by the Chilean company SQM with a basic substance content of at least 99% was used as a starting raw material source for producing ultrapure lithium carbonate. The operation of mechanical activation grinding is excluded from the production process of ultrapure lithium carbonate by increasing the contact surface of the phases by conducting the carbonization of pulp of technical carbonate in a 4-fold excess of the solid phase Li ₂ CO ₃ , the residue, which, after the completion of the carbonization operation, is separated from the obtained lithium bicarbonate solution, entering the ion exchange purification, the residue in the form of a thickened pulp is returned to the preparation operation of the initial pulp Li ₂ CO ₃ , and the carbonate solution of the decarbonization operation and a solution of lithium bicarbonate, formed after the separation of the ultrapure Li ₂ CO ₃ phase, is evaporated by crystallization of the solid Li ₂ CO ₃ phase to form a pulp Ж: Т = 0.80-0.85, the pulp is centrifuged, the obtained solid Li ₂ CO ₃ phase is washed with demineralized water and sent to the carbonization operation of technical Li ₂ CO ₃ , the centrate is purified from boron and sulfate ions by transferring them to insoluble compounds CaB ₄ O ₇ and BaSO ₄ , sequentially introducing CaO and BaCl ₂ into the centrate, the alkaline lithium-containing solution formed after separation of the precipitate is neutralized hydrochloric acid d pH 6.0-6.5, obtaining a lithium chloride solution, which is evaporated, bringing the LiCl concentration to 400-450 g / l and salting out NaCl crystals, NaCl crystals are separated from the evaporated chloride solution, washed with demineralized water, directing the spent wash solution to the evaporation operation chloride solution and salting NaCl, chloride The evaporated solution is diluted with demineralized water to a LiCl 190-200 g / liter and precipitated therefrom as a lithium Li ₂ CO ₃ sodium carbonate, Li ₂ CO ₃ is separated from the mother liquor containing soda and after washing deminers ripple water directed to the technical operation carbonization Li ₂ CO _3, and the mother deposition soda solution is mixed with an alkaline, formed after separation CaB ₄ O ₇ and BaSO ₄ precipitation.

The technical result is achieved by the fact that the regeneration hydrochloric acid solution when the Lewatit TP 208 resin is converted to the H ⁺ form containing the residual amount of acid, magnesium chloride, calcium chloride and heavy metals, according to the first embodiment, is subjected to reagent treatment with soda, introduced in an amount that provides a solution pH of 9.5 -10.0 to form a slurry consisting of solid phases CaCO ₃ and ₃ 3MgCO Mg (OH) ₂ 3H ₂ O, heavy metal carbonates and NaCl solution, precipitation was separated from the liquid phase by filtration, and the filtered solution was mixed with NaCl-holding litiyso they chloride solution before evaporation. In the second embodiment, the regeneration hydrochloric acid solution of Lewatit TP 208 resin is subjected to reagent treatment with a mixture of Ba (OH) ₂ and BaCO ₃ at the rate of 1 mol of Ba (OH) ₂ per mole of MgCl ₂ , 1 mol of Ba (OH) ₂ per 2 moles of HCl and 1 mol of BaCO ₃ per 1 mol of CaCl ₂ to obtain a suspension consisting of solid CaCO ₃ , Mg (OH) ₂ , heavy metal hydroxides and a solution of BaCl ₂ , the precipitate is separated from the solution by filtration, sulfuric acid is added to the BaCl ₂ solution at a rate of 1 mol H ₂ SO ₄ per 1 mol of BaCl ₂ , precipitating from a solution of barium in the form of Ba ₂ SO ₄ and obtaining a hydrochloric acid solution used for acidic resin regeneration, and / or and acidification of the lithium-containing alkaline solution formed at the stage of purification of the centrate of the operation of evaporation of the mother liquor of decarbonization after separation of ultrapure Li ₂ CO ₃ .

The technical result is also achieved due to the fact that the carbonization of the pulp of technical lithium carbonate with carbon dioxide is carried out in a cooled reactor with a stirrer at a degree of filling of the reactor with pulp of 50% and a constant, close to atmospheric, pressure of carbon dioxide in the upper zone of the reactor, providing a constant level of time over time carbon dioxide in the carbonizable pulp by continuously ejecting carbon dioxide from the upper zone of the reactor in communication with the CO ₂ source into the pulp stream of lithium carbonate circulated from the lower zone of the reactor to its upper zone through the ejection device.

The technical result is achieved in that the conversion of the Lewatit TP 208 resin, which is a polyampholyte, from the H-form to the Li-form is carried out by treating the resin with a lithium bicarbonate solution that has passed the ion exchange purification stage, followed by the use of the spent bicarbonate solution in a mixture with washing solutions formed in the stages washing Li ₂ CO ₃ obtained in the process of processing the mother liquor of the decarbonization operation as a liquid phase in the preparation of the pulp of industrial Li ₂ CO ₃ and its carbonization.

The technical result is also achieved by the fact that the installation for producing ultrapure LiHCO ₃ includes a cooled thin-layer pulp thickener that has passed the carbonization stage, a pulp pump for pumping thickened pulp from the lower thickener zone to the carbonizer, and a tank for receiving clarified carbonated LiHCO ₃ solution coming from the upper thickener zone, a pump for supplying the clarified solution to filtration, a filter for fine cleaning clarified solution tank receiving the filtered LiHCO ₃ solution cooled in an ion exchange Olona packed with Lewatit TP 208 resin in the Li-form, the tank with demineralised water rinse, the pump for supplying washing with demineralized water cooled ion exchange column, a tank with a hydrochloric acid solution, a pump for conveying the acid solution, the container with a regeneration solution LiHCO _3, pump supplying LiHCO ₃ solution to the ion exchange column, a heated crystallizer to thicken the pulp of ultrapure Li ₂ CO ₃ formed in the decarbonizer, pulp pump for transporting the Li ₂ CO ₃ pulp formed in the decar reactor bonizer in a centrifuge, a centrifuge for separating ultrapure Li ₂ CO ₃ crystals from the decarbonization mother liquor, ultrapure Li ₂ CO ₃ pulp meter, demineralized water meter, wet ultrapure Li ₂ CO ₃ dryer, unloading device with a cooled feeder, filling device, container with finished products, a blower for removing moisture, an exhaust gas heat recovery unit, a refrigerator, a condenser, a mist eliminator, a container for receiving a centrate mother liquor of decarbonization, a pump for supplying a mother liquor of a deck bonizatsii for evaporation, the evaporator for evaporation of the mother liquor decarbonation crystallizer for thickening Li ₂ CO ₃ from the pulp produced by evaporation of the mother liquor decarbonization CO _2, the pulp pump for supplying thickened in the crystallizer slurry in the dipstick, the dipstick the evaporated and thickened sludge, a centrifuge for separation of the solid phase Li ₂ CO ₃ of the evaporated and thickened pulp collecting tank of supernatant carbonate residue, a pump for supplying the carbonate of supernatant residue, stirred reactor for reagent purification carbonate fugue and boron and sulfate ions, a pump for supplying generated in the reactor reagent purification slurry to filtration in the filter press, filter press for the removal of filterable slurry solids CaB ₄ O compounds ₇ and Ba ₂ SO _4, stirred reactor for the conversion of carbonate centrate in the chloride solution, a pump for feeding the chloride solution to the residue, an evaporation apparatus for evaporating the chloride solution and salting out NaCl crystals, a crystallizer for separating NaCl crystals from the evaporated chloride solution, pulp pump for removing pulp crystal fishing NaCl from LiCl solution, a centrifuge for separating NaCl crystals from LiCl solution, a container for receiving clarified concentrated LiCl solution coming from the upper zone of the NaCl crystallizer, a pump for feeding the evaporated LiCl solution to a heated reactor with a stirrer for soda deposition of Li ₂ CO ₃ from solution LiCl, a pump for supplying pulp Li ₂ CO _3, precipitated from the evaporated solution soda LiCl, filter press to separate the precipitated Li ₂ CO ₃ from the mother liquor, a source of soda solution and a stirred reactor for precipitation of calcium and magnesium of CLOSED hydrochloric acid regenerant soda or Ba mixture (OH) ₂ and Ba ₂ CO _3, feed pump formed as a result of deposition of calcium and magnesium slurry to filtration, filter press for separating the carbonate-alkali precipitation of NaCl solution or BaCl _2, reactor a mixer for converting a BaCl ₂ solution to an HCl solution, a source of sulfuric acid, an intermediate container for collecting lithium-containing wash water, a gas blower for transporting recycled carbon dioxide to a gas holder containing CO ₂ , a carbon dioxide source, a demineral source Bound water, a collection of recycled water, a baking device for opening bags with technical lithium carbonate, a source of hot steam, a source of refrigerant.

The technical result is achieved by the fact that in the installation for producing ultrapure Li ₂ CO _{3, a} cooled reactor-carbonizer equipped with a stirrer, one upper branch pipe is connected to a gas tank by means of a pipeline, and the lower pipe is connected via a pulp pump, shut-off and control valve and other upper pipe via a pipeline connected to an ejector installed inside the upper zone of the carbonizer reactor, and through a pulp pump and a shut-off and control valve with an inlet pipe of a thin-layer thickener, thin-layer with Li ₂ CO ₃ pulp thickener with its lower outlet for condensed pulp exit through the pulp pump is connected via a pipe to the nozzle of the technical pulp preparation reactor Li ₂ CO ₃ , and the clarified solution outlet pipe is connected to the clarified carbonated solution intake tank, and the clarified carbonized LiHCO ₃ solution tank is received through the pump, through a pipe connected to the inlet of the filter for fine cleaning the clarified LiHCO ₃ solution, the inlet of which is connected by pipe to In order to receive the filtered LiHCO ₃ solution, the tank for receiving the filtered solution is connected via a pipeline through a pump and a shut-off and control valve to the inlet of the cooled ion-exchange column and by means of a pipeline and a shut-off and adjustable valve with the inlet of the filter for fine cleaning the LiHCO ₃ solution, the cooled ion-exchange column by its inlet a pipe is connected through a pipeline through shut-off and control valves and to a pump: to the outlet pipe of the wash water tank, to the outlet pipe acid regeneration solution, with the outlet nozzle of the LiHCO ₃ regeneration solution tank, connected to the intermediate tank for collecting lithium-containing washing water, with the inlet of the reactor for precipitating calcium and magnesium from the spent hydrochloric acid regeneration solution and the inlet nozzle with its outlet nozzle through pipelines and shut-off and control valves fine filter, and with its blow-off pipe by means of a gas duct through a gas blower with a gas holder, an intermediate capacity for collecting lithium ERZHAN washing water through a conduit through a pump and pert-regulating valves connected to the inlet of the collection of recycled water, with an aqueous reactor tube for the conversion of the carbonate of supernatant in the chloride solution and with the inlet tank for receiving the evaporated LiCl solution, fine filter solution LiHCO ₃ passing the ion exchange by means of a pipeline by an inlet pipe is connected to an inlet pipe of a heated circuit in a heat recuperator and by a pipeline through a shut-off and control valve with an inlet a LiHCO ₃ regeneration solution tank nozzle, a heat recuperator with an inlet pipe of a heated circuit through a pipe connected to an inlet pipe of a heated decarbonizer reactor, an inlet pipe of a cooled circuit with an outlet nozzle of a centrifuge, and an outlet pipe of a cooled circuit with an inlet pipe of a tank for receiving a decarbonization mother liquor, heated the mold is connected via its pipeline to the blowdown nozzle of the heated reactor through its duct of the argonizer and by means of a pipeline through a gas blower with a gas holder, the heated decarbonizer reactor with its lower branch pipe for withdrawing pulp of ultrapure Li ₂ CO ₃ through the pulp pump through a pipeline and shut-off and control valves is connected to its upper pipe and branch pipe for the entrance of the heated crystallizer pulp, the lower pipe, for pulp output through a pulp pump through a pipeline and shut-off and control valves connected to the pulp meter and the upper pipe of the heated reagent ra-decarbonizer, the upper nozzle for the outlet of the clarified decarbonized solution is connected via a pipeline to the receiving tank of the clarified decarbonized solution, the receiving capacity of the clarified decarbonized solution is connected via a pipe to the inlet of the evaporation apparatus for evaporating the decarbonized solution and the recirculated water collector and directly to the clarified water outlet decarbonated solution evaporated mold Li ₂ CO _3, which conduit connected with an outlet of the evaporator for evaporation of the decarbonated solution and at its lower pipe for outlet of the pulp through the pulp pump and measuring tank via a conduit connected to the centrifuge dryer ultrapure Li ₂ CO ₃ nozzle discharging the dried product connected to the hopper of a cooled feeder tube discharge is articulated to a filling device, a dry gas carrier inlet pipe with an outlet pipe for a heated gas circuit of a heat recuperator, leaving the wet gas dryer, the exhaust outlet pipe of the dryer with the inlet pipe of the cooled gas circuit of the exhaust gas heat recuperator, the exhaust gas heat recuperator is connected to the inlet pipe of the gas circuit of the refrigerator-condenser with its outlet pipe of the refrigerated gas circuit, and connected to the inlet pipe of the heated gas circuit through the gas blower through a pipe with the outlet nozzle of the mist eliminator, which is connected with its outlet nozzle to the outlet nozzle of the gas circuit x a condenser, a centrifuge for separating Li ₂ CO ₃ crystals from an evaporated decarbonized solution - a carbonate evaporation centrate, is connected via a pipeline through shut-off valves to a washing water meter, a container for collecting a carbonate evaporation centrate and an intermediate container for collecting lithium-containing washing water, a tank for collecting the carbonate centrate of the residue by means of a pipeline through a pump and through a shut-off and control valve is connected to the reactor with a stirrer for reactive cleaning of carb of the sodium carbonate residue from boron and sulfate ions: a reactor with a stirrer for the reactive purification of the carbonate residue of evaporation with its lower pipe to exit the suspension through the pump through a pipeline and shut-off and control valves with its upper pipe and press filter inlet to remove solid suspension from the filtered suspension phases CaB ₄ O ₇ and BaSO ₄ , which through its outlet pipe is connected via a pipe to the outlet pipe of the reactor for the conversion of the carbonate centrate of the residue into a chloride solution, other upper patrons whose flanges are connected via a pipeline to the outlet of the press filter to remove carbonate deposits of calcium and magnesium from the spent regeneration solution after its reagent treatment, an intermediate tank for collecting lithium-containing wash water and an overflow nozzle of the crystallizer to remove NaCl crystals from the evaporated chloride solution, and the lower nozzle a reactor for conversion through a pump through a pipe connected to the inlet of the evaporator for evaporation of the chloride solution, the evaporator for evaporating the chloride solution with its nozzle for the output of the evaporated chloride solution is connected via a pipeline to the inlet of the crystallizer for separating NaCl crystals from the evaporated chloride solution with its lower nozzle for piping the condensed pulp through a pipe through a measuring tube to the centrifuge inlet and the side outlet clarified concentrated LiCl solution with a container for receiving a clarified concentrated LiCl solution, centrifuge for the separation of NaCl crystals from the evaporated chloride solution with its pipe for exiting the centrate through a pipeline is connected to the pipe for receiving the centrate of a NaCl crystallizer, the tank for receiving the clarified concentrated LiCl solution is connected via an pipeline to an intermediate container for collecting lithium-containing wash water and through a pipeline through a pump with a Li soda sedimentation reactor ₂ CO ₃ from a clarified concentrated solution of LiCl, a reactor for soda deposition of Li ₂ CO ₃ from a clarified concentrated solution the thief with his lower pipe to exit the Li ₂ CO ₃ pulp through the pump and shut-off valve through a pipe connected to the inlet pipe of the press filter to separate Li ₂ CO ₃ from the mother liquor of the soda deposition operation, and the upper pipe to enter the soda solution with the source of soda solution, a press filter for separating Li ₂ CO ₃ from the mother liquor of the soda deposition operation with its nozzle of the filtrate outlet — a NaCl admixture with Li ₂ CO ₃ impurity is connected via a pipeline to one of the upper nozzles of the reactor for versions of the carbonate centrate of the residue in the chloride solution, the source of the soda solution is connected via a pipe through a shut-off valve to the inlet of the soda solution to precipitate calcium and magnesium from the spent hydrochloric acid regeneration solution, the blow-off pipe of which through the blower is connected via a pipe to the gas holder, and the lower pipe for the output of the suspension through the valves and the pump through pipelines is connected to the inlet of the press filter to separate the sediment from the solution NaCl or HCl, resulting from chemical treatment of spent acid regenerant solution, and through a conduit with an outlet of the reactor the conversion of BaCl ₂ solution into the HCl solution, filter press to separate precipitation from solutions of NaCl or HCl, resulting from chemical treatment of spent hydrochloric acid regenerant , through its outlet pipe through pipes and shut-off and control valves connected to the tank for a solution of hydrochloric acid and a reactor with a stirrer for the conversion of carbonate of the centrate in the chloride solution, a reactor for converting the BaCl ₂ solution into the HCl solution is connected to the sulfuric acid source through a pipeline and a shut-off and control valve.

The technical result is also achieved by the fact that in the installation for producing ultrapure lithium carbonate, the cooling circuits of the reactor for the preparation of Li ₂ CO ₃ pulp, carbonizer reactor, thin-layer thickener, condenser cooler, filling device feeder are connected via pipelines to the cooling source circulating in the coolant circuits, heating contours of a decarbonization reactor, a crystallizer for thickening pulp of ultrapure Li ₂ CO ₃ from a decar-bonded LiHCO ₃ solution, an ultrapure dryer Li ₂ CO _{3 of} a soda deposition reactor Li ₂ CO ₃ from a concentrated LiCl solution, an evaporation apparatus for evaporating the mother liquor of decarbonization, an evaporation apparatus for evaporating the chloride solution by means of a pipeline is connected to a source of heating steam, and the condensate collectors of the above-mentioned equipment heated by steam are connected via a pipeline to a circulating water collector connected by a pipeline to a source of demineralized water. The proposed apparatus for producing ultrapure of lithium carbonate Li ₂ CO Technical ₃ provides a high degree of output the resulting product with minimal energy consumption and high productivity, while avoiding the formation of liquid and gaseous waste products.

List of drawings

FIG. 1 Technological scheme of the method of producing ultrapure lithium carbonate from industrial Li ₂ CO ₃ .

FIG. 2. The circuit circuit of the apparatus for the implementation of the technological scheme.

Information confirming the feasibility of the invention is presented in FIG. 1 with the following description and examples.

According to the scheme (Fig. 1), the implementation of the method for producing ultrapure lithium carbonate from industrial Li ₂ CO ₃ begins with the operation of preparing pulp of technical lithium carbonate from anhydrous Li ₂ CO ₃ and demineralized water by mixing them. Next, the pulp of industrial Li ₂ CO _{3 is} subjected to carbonization with carbon dioxide to transfer the calculated amount of the solid phase Li ₂ CO ₃ in a solution of LiHCO ₃ . The process is described by reaction (1). The carbonization process is carried out in excess of the solid phase Li ₂ CO ₃ . The amount of excess depends on the particle size distribution of the initial Li ₂ CO ₃ , which determines the phase contact surface. For example, the use of SQM lithium carbonate as a raw material, in order to exclude the operation of preliminary mechanical activation grinding while maintaining high productivity of the process of obtaining a LiHCO ₃ solution, requires a 4-fold excess of Li ₂ CO ₃ in the carbonized pulp. The carbonization process proceeds over the entire length at a constant pressure of CO ₂ not exceeding atmospheric pressure by no more than 200 Pa at the inlet to the main carbonizing device, which is used as an ejector. The working fluid in this case is the aqueous pulp of lithium carbonate, which is constantly circulating through the ejector by means of a console pump. Due to the vacuum created in the ejector, carbon dioxide is intensively supplied to its mixing chamber, where an intense turbulent 3-phase flow is formed with a highly developed phase contact surface under conditions of high CO ₂ concentration. The carbonization process is considered complete when the concentration of LiHCO ₃ in the liquid phase reaches its maximum, i.e. 60-63 g / l.

The resulting slurry Li ₂ CO ₃ in LiHCO ₃ solution is sent for thickening, the condensed phase is returned to the preparation of the initial pulp by replenishment with technical Li ₂ CO ₃ and demineralized water, and the clarified solution is filtered and subjected to ion exchange purification of Ca, Mg impurities and heavy metals on polyampholite Lewatit TP 208 in Li-form. In the process of ion exchange, impurities accumulate in the ion exchanger, lithium passes into solution in accordance with ion exchange reactions:

The spent polyampholyte is regenerated in two stages: in the first stage, with acid, the polyampholyte is converted to H-form in accordance with the reactions:

in the second stage, with a LiHCO ₃ solution that has passed the stage of ion exchange purification or with a LiOH solution in accordance with the reactions:

Utilization of spent acidic regenerates, which are acidic solutions, mainly salts of MgCl ₂ , CaCl _{2 is} carried out in two ways. The first, of which involves their processing into a solution of hydrochloric acid, first by reacting them with soda, converting calcium and magnesium into precipitates by the reactions:

The precipitates are separated from the NaCl solution by filtration, the NaCl solution is evaporated until crystals of sodium chloride are isolated.

The disposal of spent acidic regenerates according to the second embodiment is carried out by their chemical conversion to HCl solution, first by reacting them in the first stage with a mixture of Ba (OH) ₂ and BaCO ₃ , accompanied by neutralization of the acid and precipitation of calcium and magnesium in accordance with the reaction:

and then after separating the precipitates by filtration with barium sulfate precipitation from a solution of BaCl ₂ according to the reaction:

The resulting solution is returned to the acid regeneration of the ion exchange resin (e.g. Lewatit TP 208) or used for acidification.

, Cl^-, $$N{O}_3^{-}$$

и др. после отделения Li₂CO₃ центрифугированием остаются в растворе, после промывки осажденный Li₂CO₃ соответствует квалификации ультрачистый. Фугат операции декарбонизации, представляя раствор Li₂CO₃ с различными примесями, направляют на глубокое упаривание с целью утилизации Li₂CO₃ высаливанием. Высоленный Li₂CO₃ после промывки деминерализованной водой направляют на операцию приготовления пульпы технического Li₂CO₃, промывная вода также поступает на упаривание. После отделения твердой фазы Li₂CO₃, упаренный карбонатный фугат операции декарбонизации очищают от основных примесей: сульфат-ионов, фтора и бора реагентной обработкой раствора CaO и BaCl₂ с переводом в нерастворимые соединения по реакциям:In turn, the LiHCO ₃ solution, which underwent ion-exchange purification, is heated to 70-90 ° C with vigorous stirring until the lithium bicarbonate is completely decomposed to form the Li ₂ CO ₃ solid phase according to reaction (2). Since, such impurities as Na ⁺ , K ⁺ , $$S{O}_{\mathrm{four}}^{2-}$$

, Cl ^- , $$N{O}_3^{-}$$

and others. After separation of Li ₂ CO _{3 by} centrifugation, they remain in solution, after washing, the precipitated Li ₂ CO ₃ corresponds to ultrapure qualification. The decarbonization operation centrifuge, presenting a Li ₂ CO ₃ solution with various impurities, is sent for deep evaporation in order to utilize Li ₂ CO _{3 by} salting out. Salted Li ₂ CO ₃ after washing with demineralized water is sent to the operation for preparing pulp of industrial Li ₂ CO ₃ , washing water also flows to evaporation. After separation of the solid phase Li ₂ CO ₃ , one stripped off carbonate centrate, the decarbonization operations are purified from the main impurities: sulfate ions, fluorine and boron by reagent treatment of a solution of CaO and BaCl ₂ with translation into insoluble compounds by the reactions:

After separating the precipitates by filtration, the resulting carbonate-alkaline solution is acidified with hydrochloric acid, converting it into a chloride solution. The resulting chloride solution containing, along with LiCl, mainly sodium and potassium chlorides, is evaporated, concentrating the solution on LiCl to its content of 450 g / l while salting out NaCl and KCl. Crystals of NaCl mixed with KCl are separated from the evaporated solution, washed and dried. Wash water is directed to evaporation in a mixture with a chloride solution. The evaporated LiCl solution is diluted twice with water and lithium is precipitated in the form of carbonate with soda. Carbonate after separation from the mother liquor of soda deposition is washed and sent to the preparation of pulp technical Li ₂ CO ₃ . Wash water and the mother liquor of soda deposition are sent for evaporation in a mixture with the mother liquor of the decarbonization operation.

The proposed technology has a closed cycle for lithium, the total loss of which does not exceed 0.4%. There is no liquid or gaseous waste. The level of solid waste generation is determined by the level of impurities in the technical Li ₂ CO ₃ (in this case, not more than 1% wt.). Solid industrial waste is either waste of the 5th hazard class and can be used as fillers for concrete and other building mixtures (insoluble compounds of lithium, calcium and heavy metals), or are market reagents for the preparation of disinfecting agents by the electrochemical method or regeneration solutions in ion-exchange plants water softeners (table salt).

Obtaining ultrapure lithium carbonate from industrial Li ₂ CO ₃ in the installation of FIG. 2 is as follows. Bags with technical lithium carbonate are opened in a boring device (1), pour lithium carbonate into the hopper of the feeding and dosing device (2), with which the necessary amount of Li ₂ CO _{3 is} loaded into a cooled reactor to prepare the pulp (3). After the calculated even volume of demineralized water is pumped into the reactor (3) by a pump (5) from the source of demineralized water (6) and / or an intermediate tank (9) for collecting demineralized water, the mixer is turned on, pulping the contents of the reactor (3). The finished aqueous pulp of technical lithium carbonate with a pulp pump (4) is fed into a cooled reactor-carbonizer (7), providing 50% filling of its volume, include a stirrer and a pulp pump (8) operating in the circulation mode. The lithium carbonate pulp passing through the ejection device (78) installed inside the carbonizer reactor (7), due to the discharge pulp created by the stream, flows through the suction pipe into the mixing chamber of the ejection device, and carbon dioxide is fed into the reactor (7), which is filled with the upper gas zone of the carbonizer reactor. Since the gas zone of the carbonization reactor is connected to a gas holder (10) filled with carbon dioxide from a source of CO ₂ (11) through a pipeline, a constant CO ₂ pressure of 100-200 Pa above atmospheric pressure is maintained in it. The mixing chamber ejecting device provided "perfect mixing" regime contacting phases, followed by reacting the Li ₂ CO ₃ with carbon dioxide and conversion to the LiHCO ₃ solution. The carbonization process continues in the lower zone of the reactor after the pulp leaves the ejection device. Unreacted carbon dioxide returns spontaneously to the gas zone of the carbonizer reactor. As a result of the fact that the solid phase of Li ₂ CO ₃ is in excess, the criterion for the carbonization process is the maximum achieved concentration of LiHCO ₃ in the liquid medium of the carbonizable pulp, which is in the range of 61-63 g / l. The estimated volume of pulp with a limiting LiHCO ₃ content in the liquid phase is constantly removed from the carbonizer reactor to a cooled thin-layer pulp thickener (12), the output of the pulp volume from the carbonizer reactor is compensated by the volume of the initial pulp supplied from the reactor (3). Phase separation occurs in the cooled thickener, while the clarified phase of the LiHCO ₃ solution enters the acceptance tank of the clarified carbonized solution (14), and the condensed phase Li ₂ CO _{3 is} returned to the carbonization reactor for carbonization by the pulp pump (13). Thus, they ensure the continuity of the production process of LiHCO ₃ solution with the maximum driving force of the carbonization process. From the tank (14), the clarified carbonated LiHCO ₃ solution is pumped (15) through a fine filter (16) to the acceptance tank of the filtered LiHCO ₃ solution (18) and is pumped (19) for ion exchange cleaning to the lower inlet of the ion exchange column (20) cooled by a refrigerant from a heat exchanger (33). The filter cake, which is a solid phase of Li ₂ CO ₃ , is discharged from position (16) into a container (17) and then returned to the repulpator (3) for processing. The purified LiHCO ₃ solution is removed from the cooled ion-exchange column through the upper outlet pipe, through a fine filter (30), heated in a heat recuperator (34) and poured into a steam heated reactor-decarbonizer with a stirrer (35). When heated and vigorously stirred, dissolved LiHCO ₃ decomposes to form the solid phase of ultrapure Li ₂ CO ₃ and carbon dioxide. To complete the decomposition of LiHCO ₃ , pulp circulation is provided by a pulp pump (36) with a calculated volume supplied to a heated mold (38), in which, during the pulp circulation, the pulp pump (39) deeply removes carbon dioxide and thickens the Li ₂ CO ₃ pulp. Carbon dioxide generated in the heated reactor-decarbonizer and crystallizer, gas blower (79) is sent to the gas holder (10). Estimated volume of pulp ultrapure Li ₂ CO ₃ Pulp pumps (39) is output to centrifugation through the dipstick (41) to the centrifuge (42) in which the precipitate is Li ₂ CO ₃ was washed with demineralized water from a position (40). The centrate of the mother liquor of the decarbonization operation, after separation from the crystals of ultrapure Li ₂ CO _{3, is} poured into a container for receiving the centrate of the mother liquor of decarbonization (43). The scheme also provides for the possibility of returning the centrate of the decarbonization mother liquor to the circulating water collector (9) for reuse upon receipt of a batch of high-purity Li ₂ CO ₃ instead of ultrapure. The centrate of the decarbonization mother liquor is transported to the tank (43) through a heat recuperator (34) to heat the LiHCO ₃ solution supplied to the decarbonization. An emergency overflow of the cooled solution from the mold (38) to the container (43) is also provided. After washing with demineralized water, ultrapure lithium carbonate is transferred to a dryer (51) for drying. The resin spent in the column (20) is regenerated in three stages: first, the residual LiHCO ₃ solution is displaced from the column (22) using the pump (21) with demineralized water to the container (18), then with a hydrochloric acid solution from the container (24) using pump (23), displacing the wash solution into an intermediate container for collecting lithium-containing wash water (27), and at the last stage with LiHCO ₃ solution from the tank (26) using a pump (25) to displace the liquid phase in the column (20) into the reactor with a mixer for precipitating calcium and magnesium from displaced waste nnogo hydrochloric acid regenerant (28) and catching in the CO ₂ gas tank (10). The lithium-containing wash water from position (27) is sent by a pump (80) to a container (69).

The disposal of the spent hydrochloric acid regeneration solution is carried out in two ways. Or, by treating the contents of the reactor with soda and then supplying the resulting suspension with a pump (29) for filtration to a press filter (30) to separate carbonate-alkaline sediments from the resulting NaCl solution, which is sent to the reactor with a stirrer (64) for the conversion of the carbonate centrate into the chloride solution. Or by treating the contents of the reactor with a mixture of Ba (OH) ₂ and Ba ₂ CO ₃ , followed by feeding the resulting suspension with a pump (29) to separate carbonate-alkaline sediments from the BaCl ₂ solution into the press filter (30) and then into the reactor with a stirrer for BaCl conversion ₂ into the HCl solution (31) by introducing sulfuric acid into the reactor (31) from a source of sulfuric acid (32). After separating the Ba ₂ SO ₄ precipitate on the press filter (30), the HCl solution is returned either to the resin recovery tank (24) or to the reactor (64) to convert the carbonate-alkaline solution to chloride.

Drying of ultrapure Li ₂ CO ₃ in a steam-heated dryer (51) is carried out as follows. Dry carrier gas (atmospheric air) through a gas blower (54) through the heating circuit of the exhaust gas heat recuperator (52) enters through the inlet pipe to the dryer, which is heated by the carrier, which is hot and extremely humid, from the dryer through the outlet pipe (exhaust gas), from the dryer to the cooled recuperator circuit (52). When the extremely moist exhaust gas stream is cooled, condensation of water vapor occurs, which is removed from the reactor in the form of condensate. Further, the gas carrier is cooled in a refrigerator-condenser (53), where there is a deeper condensation of water vapor. From the condenser, the gas stream passes the mist eliminator (55) and enters the gas blower inlet (54). Thus, the drying of ultrapure lithium carbonate is carried out in a closed loop of the carrier gas, which minimizes the likelihood of contamination from the outside. Dried ultrapure lithium carbonate from the dryer (51) enters a cooled device consisting of a hopper and a screw (48), and then into a filling device (49) and is packed in a container (50).

In turn, the centrate of the mother liquor of the carbonization operation from the tank (43) is pumped to the inlet of the evaporator (45) from the tank (43). When this solution is evaporated and the lithium concentration is increased, Li ₂ CO ₃ crystals precipitate, which can no longer be classified as “ultrapure” and the resulting pulp is removed to the crystallizer (46). In the mold (46), the pulp thickens. The thickened pulp with a pulp pump (47) is discharged into the measuring device of the evaporated and condensed pulp (57) and then to the centrifuge (58) to separate and rinse with demineralized water from the tank (56) the solid phase Li ₂ CO ₃ from the evaporated and condensed pulp. The carbonate residue of the residue is sent to a container for collecting the carbonate residue of the residue (59) and then pump (60) into the reactor with a stirrer for the reactive purification of the carbonate residue from boron and sulfate ions (61). The suspension formed as a result of the reagent treatment, containing BaSO ₄ and CaB ₄ O ₇ precipitates in the form of a solid phase, is pumped (62) to a filtration filter to remove BaSO ₄ and CaB ₄ O ₇ precipitates from the filtered suspension (63) and then into a reactor with a stirrer for the conversion of the carbonate centrate purified from impurities to a chloride solution (64). The chloride solution resulting from the hydrochloric acid acidification of the contents of the reactor (64) is then pumped (65) to an evaporator to evaporate the chloride solution (66). As a result of evaporation of the chloride solution, LiCl is concentrated and NaCl is salted out. In this case, the resulting pulp is removed from the evaporator (66) into the crystallizer to separate NaCl and KCl crystals from the LiCl solution (67). The clarified LiCl solution from the crystallizer (67) is poured into a container to receive the clarified concentrated LiCl solution (69), and the thickened pulp containing NaCl crystals, pulp pump (68) is sent to the pulp meter of NaCl crystals mixed with KCl crystals in LiCl solution (72) and then to a centrifuge (73) to separate NaCl crystals mixed with KCl from LiCl solution. KCl-doped NaCl crystals are washed with demineralized water coming from the measuring unit (71), discharged from a centrifuge, and used to prepare regeneration solutions in ion-exchange water softeners, and the centrate and wash solution are returned to the reactor (64). The scheme also provides emergency overflow from the mold (67) to the reactor (64). The concentrated clarified LiCl solution from the tank (69) is pumped (70) to a heated reactor with a stirrer for soda deposition of Li ₂ CO ₃ (76). Soda solution is metered into the reactor (76) from a source of soda solution (74). The pulp Li ₂ CO ₃ formed in the reactor (76) in a NaCl solution (soda mother liquor) by a pulp pump (75) is filtered on a press filter (77), separating Li ₂ CO ₃ from the mother soda precipitate and washed with demineralized water. The mother liquor of soda deposition and the washing solution are poured into the reactor (64). Obtained as a result of soda deposition of Li ₂ CO ₃ return to the head of the process for the preparation of the original pulp of industrial lithium carbonate.

As a heating agent, acute steam coming from a source of hot steam is used (37). The equipment is cooled with a liquid refrigerant coming from a source of refrigerant (78). Steam condensates formed during the production process are discharged into a collection of circulating demineralized water (9) and used in production.

In the future, the invention is confirmed by specific examples taken from the results of practical verification of the proposed solutions.

Example 1. Various samples of technical Li ₂ CO ₃ firm (SQM) samples, differing in granule size and weight, were placed in a stirred reactor filled with demineralized water. The reactor volume was 1 liter with pulp filling up to 0.5 liter. The contents of the reactor were carbonized with carbon dioxide GOST 8050-86, maintaining a constant excess pressure of CO ₃ at the inlet of the reactor 2-3 Pa and feeding it into the lower zone of the reactor under the mixer. The concentration of lithium in the carbonized pulp was controlled by sampling through a filter and then analyzing them for lithium content by atomic absorption spectrometry. All experiments were carried out at a temperature of 20 ° C using temperature control. Samples with different granule sizes were prepared by grinding the starting technical carbonate (granule size of at least 400 μm), followed by sieving. Various methods were used to increase the contact surface of the phases: grinding and increasing the ratio of the excess Li ₂ CO ₃ . For grinding, a ball mill was used. One of the samples was subjected to mechanical activation grinding (according to the prototype), which corresponded to an energy intensity of 14.5 kW. per kilogram of product. The speed of rotation of the stirrer in the reactor is 60 rpm. The results obtained are summarized in table 1.

Table 1 The change in the concentration of lithium in the liquid phase from the time of carbonization with an increase in the contact surface of the phases by various methods Carbonation time, min Samples of Li ₂ CO ₃ with different particle sizes and different contents of lithium carbonate Mechanical activation grinding, size <50 μm stoichiometric content of Li ₂ CO ₃ Ball mill grinding, size 150-200 microns stoichiometric content of Li ₂ CO ₃ Original lithium carbonate with a granule size of up to 400 microns and above without grinding Stoichiometer. Li ₂ CO ₃ content 2 times hut Li ₂ CO ₃ 3 times hut Li ₂ CO ₃ 4 times hut Li ₂ CO ₃ 5 times hut Li ₂ CO ₃ The concentration of lithium in the liquid phase, g / l. thirty 3.5 3.4 2.8 3.0 3.2 3.4 3.4 60 4.7 3.9 3.0 3.1 3.4 3.9 3.9 90 5.5 5.3 3.6 3.9 4.2 4.9 5.0 120 6.0 5.9 3.8 4.2 5.0 6.4 6.3 150 6.4 6.0 4.9 5.3 5.8 6.4 6.4 180 6.6 6.2 5.0 5.4 5.9 6.4 6.4 240 6.6 6.4 5.1 5.5 6.0 6.6 6.5

From the contents of the table it follows that the rate of transition of lithium into the liquid phase depends not only on the size of its particles, but also on the size of the total surface of the particles during the carbonization of the pulp Li ₂ CO ₃ , carbon dioxide. At the same time, it is inexpedient to spend energy on mechanical activation grinding. To ensure the rate of interaction of lithium carbonate with CO _{2 at} the same level as with crushed Li ₂ CO ₃ , a 4-fold excess of lithium carbonate in the carbonized pulp is sufficient.

Example 2. In the upper zone of the reactor with a stirrer described in Example 1, an ejection device was installed through which the Li ₂ CO ₃ pulp was pumped in a circulation mode from the lower zone of the reactor, while ejecting carbon dioxide supplied from the cylinder to the upper zone of the reactor . Under these conditions, a series of experiments was carried out on the carbonization of aqueous pulp of the initial technical lithium carbonate with its various contents in the pulp. The results obtained are summarized in table 2.

table 2 The change in the concentration of lithium in the liquid phase with increasing turbulence during carbonization of the pulp Li ₂ CO ₃ The time interval from the beginning to the end of the interaction, min A sample of Li ₂ CO ₃ , g per 500 ml of distilled water (pressure 102-103 kPa) The concentration of lithium in the liquid phase, g / l 17 7.5 2.8 25 10.0 3.8 29th 12.5 4.7 38 15.0 5.7 52 17.5 6.6

Comparing the contents of tables 1 and 2, we can make an unambiguous conclusion that increasing the turbulence of the carbonization regime due to the ejection device increases the interaction rate, ceteris paribus, at least 2 times.

Example 3. At the installation described in example 2, a series of experiments was conducted on the carbonization of an aqueous pulp of lithium carbonate at various pressures of CO ₂ in the upper zone of the reactor. The results obtained are summarized in table 3.

An unambiguous conclusion follows from the table that the pressure of carbon dioxide at the inlet to the phase contact zone substantially determines the rate of interaction of lithium carbonate. An increase in pressure in the upper zone of the reactor from 50 to 100 kPa accelerates the carbonization process by almost 2 times. However, the overpressure in the upper zone of the reactor should not be higher than 3 kPa in order to avoid the need to develop equipment for safe operation at high pressure.

Table 3 The change in the concentration of lithium in the liquid phase with a change in pressure during carbonization of the pulp Li ₂ CO ₃ The time interval from the beginning to the end of the interaction, min A portion of Li ₂ CO ₃ , g per 500 ml of demineralized water The concentration of lithium in the liquid phase, g / l, at various pressures of carbon dioxide in the upper zone of the reactor Pressure kPa 102-103 70-80 45-55 17 7.5 2.8 2.2 1.6 25 10.0 3.8 3.0 1.8 29th 12.5 4.7 3.6 2.3 38 15.0 5.7 4.3 2.9 52 17.5 6.6 4.9 3.5

Example 4. At enlarged laboratory setup, constructed in accordance with the scheme (Figure 2) was checked suitability of the proposed technology for obtaining ultrapure Li ₂ CO ₃ of technical lithium carbonate (Figure 1). After the installation was brought to a stable operating mode (steady state), balance tests were carried out. For this purpose, a fixed amount of technical Li ₂ CO ₃ (500 g) (analysis results are given in Table 4), weighed to the 4th decimal place, was converted to ultrapure lithium carbonate. As a result of processing, a total of 493.1 g of ultrapure lithium was obtained, the analysis results of which are given in Table 5. From the contents of table 5 it follows that a high-quality product with a yield of 98.6% is obtained. The total loss of lithium does not exceed 0.5% wt.

Table 4 The content of Li ₂ CO ₃ and basic impurities in the initial sample of technical carbonate from SQM Ingredient Definition The content of ingredients,% wt. By certificate Actual Li ₂ CO ₃ (basic substance) 99,000 99.120 Cl 0.020 0.020 Na 0.120 0.070 TO 0.050 0.040 Ca 0.040 0.028 Mg 0.011 0.08 SO ₄ 0.100 0.050 B 0.060 0.060 Not soluble 0.030 less than 0.005 0.020 0.016

Table 5 The content of Li ₂ CO ₃ and basic impurities in ultrapure lithium carbonate obtained from industrial Li ₂ CO ₃ Ingredient Definition The content of ingredients,% wt. Standard requirement Actual Li ₂ CO ₃ (basic substance) 99.990 99.9950 Al 0.0003 less than 0.00010 Na 0.0010 0.00060 K 0.0010 0.00030 Ca 0.0010 less than 0.00100 Mg 0.0005 0.0001 Ba 0.0005 0.00003 Fe 0.0003 less than 0.00003 Ni 0.0001 less than 0.00005 Cu 0.0001 less than 0.00003 Pb 0.0001 less than 0.00005 Co 0.0001 less than 0.00003 Cr 0.0001 less than 0.00004 Zn 0.0003 0.0001 Si 0.0010 less than 0.0005 F 0.005 0.0006

Industrial applicability

In connection with the rapid development of new technology, it is becoming increasingly important to obtain highly pure and ultrapure inorganic substances that can be used in the space, military, chemical, metallurgical, electronic, and other industries. In particular, ultrapure lithium carbonate can be used to produce lithium metal, high-purity lithium salts, and highly conductive cathode materials.

The present invention, which includes a method for producing ultrapure lithium carbonate and an apparatus for its implementation, makes it possible to obtain ultrapure lithium carbonate from technical Li ₂ CO ₃ on an industrial scale with a high yield of the resulting product - 98.6%, which is three times higher than the existing methods. This ensures a reduction in the energy intensity of the proposed method by 1.6 times in comparison with the prototype and an increase in the productivity of the technology for producing ultrapure lithium carbonate by 1.8 times due to the organization of a continuous mode during its implementation.

The inventive method and installation for producing ultrapure lithium carbonate can be the basis for the design of an industrial enterprise.

Information sources

1. Pat. US 6,207,126 Recovery of lithium compound from brines / Boryta, Kullberg. At March 27, 2001 (prototype installation).

2. Pat. RU No. 2283283. A method of producing lithium carbonate of high purity from lithium chloride brines / Titarenko V.I., Ryabtsev A.D., Menzherez L.T. and other publ. 09/10/2001. Bull. Number 25.

3. Pat. RU No. 2243157. A method of obtaining highly pure lithium carbonate from industrial Li ₂ CO ₃ / Aleksandrov A.B., Mukhin V.V., Shemyakina I.V. and other publ. 12/27/2004. Bull. Number 36. (prototype method).

Claims (7)

1. A method of producing ultrapure lithium carbonate from industrial lithium carbonate, including obtaining ultrapure lithium Li ₂ CO ₃ by increasing the active surface of technical Li ₂ CO ₃ , carbonizing the aqueous pulp of technical lithium carbonate with carbon dioxide while stirring to obtain a lithium bicarbonate solution, purifying the lithium bicarbonate solution from insoluble impurities by filtration, ion-exchange purification of the filtrate from impurity cations on Lewatit TP208 resin in lithium form with two-stage regeneration of the spent resin, removal of by transferring the resin to the H-form in the first stage and transferring the resin from the H-form to the Li-form in the second stage, decarbonizing the lithium bicarbonate solution by heating with the release of carbon dioxide, which is returned to the carbonization of the pulp of technical lithium carbonate, and obtaining the carbonate pulp lithium, separation of lithium carbonate from the mother liquor carbonate solution, washing it with hot water and drying, characterized in that the increase in the contact surface of the phases is carried out during the operation of carbonization of the pulp of technical carbonate l it with a 4-fold excess of the solid phase Li ₂ CO ₃ , the residue of which, after the completion of the carbonization operation, is separated from the obtained lithium bicarbonate solution and returned to the preparation of the initial Li ₂ CO ₃ pulp as a condensed pulp, and the carbonate solution of the decarbonization of lithium bicarbonate solution, formed after separation of the phase of ultrapure Li ₂ CO ₃ , evaporated by crystallization of the solid phase Li ₂ CO ₃ to form a pulp W: T = 0.80-0.85, the pulp is centrifuged, the obtained solid phase Li ₂ CO _{3 is} washed with demineralized water and They charge technical Li ₂ CO ₃ to the carbonization operation, the centrate is purified from boron and sulfate ions by transferring them into insoluble compounds CaB ₄ O ₇ and BaSO ₄ , sequentially introducing CaO and BaCl ₂ into the centrate, the alkaline lithium-containing solution formed after separation of the precipitate is neutralized with hydrochloric acid to pH = 6.0-6.5, obtaining a lithium chloride solution, which is evaporated, bringing the concentration of LiCl in the evaporated chloride solution to 400-450 g / l, salting out NaCl crystals, NaCl crystals are separated from the evaporated chloride solution, washed with demineralized water, apravlyaya the spent wash solution to evaporation operation chloride solution The evaporated chloride solution was diluted with demineralized water to a LiCl 190-200 g / liter and precipitated lithium carbonate is soda solution; Li ₂ CO _{3 is} separated from the solution and, after washing with demineralized water, is directed to the carbonization of technical Li ₂ CO ₃ , and the mother liquor of soda deposition is mixed with an alkaline lithium-containing solution formed after separation of the precipitates CaB ₄ O ₇ and BaSO ₄ ; After converting the Lewatit TP208 resin to the H ⁺ form, the regenerating hydrochloric acid solution is processed to obtain a sodium chloride solution, which is mixed with the chloride solution supplied to evaporation, or to obtain a hydrochloric acid solution, which is used to regenerate the resin and neutralize the alkaline lithium-containing solution after cleaning the centrate evaporation operations. 2. The method according to p. 1, characterized in that the carbonization of the pulp of technical lithium carbonate with carbon dioxide is carried out in a cooled reactor with a stirrer when the degree of filling of the reactor with pulp 50% and a constant close to atmospheric pressure of carbon dioxide in the upper zone of the reactor, providing a constant level over time the carbon dioxide content in the carbonized pulp by continuously ejecting carbon dioxide from the upper zone of the reactor in communication with the CO ₂ source into a stream of lithium carbonate pulp continuously circulating from the lower th zone of the reactor to its upper zone through the ejection device. 3. The method according to claim 1, characterized in that the conversion of the Lewatit TP208 resin from the H-form to the Li-form is carried out by treating the resin with a lithium bicarbonate solution that has passed the ion exchange purification step, followed by the use of the spent bicarbonate solution in a mixture with washing solutions formed in the washing stages Li ₂ CO ₃ obtained in the process of processing the mother liquor of the decarbonization operation, as a liquid phase in the operation of preparation of technical Li ₂ CO ₃ pulp and its carbonization. 4. The method according to p. 1, characterized in that the regenerating hydrochloric acid solution of Lewatit TP208 resin, containing the residual amount of acid and chloride of magnesium, calcium and heavy metals, is subjected to reagent treatment with soda, introduced in an amount that provides a solution pH of 9.5-10 0; precipitates are separated from the liquid phase by filtration to obtain a NaCl solution or subjected to reagent purification with a mixture of Ba (OH) ₂ and BaCO ₃ ; precipitates are separated from the solution by filtration, sulfuric acid is added to the resulting BaCl ₂ solution at the rate of 1 mol of H ₂ SO ₄ per 1 mol of BaCl ₂ , precipitating from the solution of barium in the form of BaSO ₄ and obtaining a solution of hydrochloric acid. 5. Installation for producing ultrapure Li ₂ CO ₃ from technical lithium carbonate, including a dosing and supplying device Li ₂ CO ₃ coupled to a pulp preparation reactor connected by one of the upper pipes through pipelines to a source of demineralized water and the lower pipe through a pulp pump with upper pipe-cooled carbonation reactor fitted with a stirrer, baffle crystal Li ₂ CO _3, heated calciner reactor equipped with a stirrer, a row of nozzles whose Sequence no through heat exchanger, a filter and a pump through a conduit connected to the nozzle output solution LiHCO _{3-carbonation} reactor, another upper carbon dioxide output by the flue pipe is connected to the input nozzle carbon dioxide carbonation reactor and a source of carbon dioxide, and the lower nozzle output reaktora- pulp the decarbonizer is connected through a pump through a pipeline to a device for separating solid and liquid phases, connected by a pipe for unloading a solid phase with a container for receiving crystals of Li ₂ CO _3, nozzle output mother liquor decarbonation means of a conduit through recuperator heat with one of the upper pipes of the reactor-carbonation and directly with the receiver-accumulator relief mother decarbonization solution nozzle entering the wash water through a conduit with a mother liquor wash water, and nozzle withdrawal of spent wash solution with a receiver accumulator of spent washing solution, characterized in that the installation further comprises a cooled thin layer thicken l pulps that have passed the carbonization stage, a pulp pump for pumping thickened pulp from the lower thickener zone to the carbonizer, a clarification tank for clarified carbonized solution coming from the upper thickener zone, a pump for supplying clarified solution to the filtration, a filter for fine filtering of clarified solution, a filtered reception tank a solution, a pump for supplying a filtered solution to a cooled ion-exchange column filled with polyampholyte in Li-form, a tank with demineralized wash water, a pump for odachi washing with demineralized water cooled ion exchange column, a tank with a hydrochloric acid solution, a pump for conveying the acid solution, the container with a regeneration solution LiHCO _3, a pump for supplying a solution LiHCO _3-cooled ion exchange column, a heated mold for thickening pulp ultrapure Li ₂ CO _3, formed in-calciner reactor, the pulp pump for transporting pulp Li ₂ CO ₃ in a centrifuge, a centrifuge for separating crystals ultrapure Li ₂ CO ₃ from the mother liquor decarbonation dipstick Ulpia ultrapure Li ₂ CO _3, dipstick demineralized water dryer wet ultrapure Li ₂ CO _3, a discharge device with a cooled feeder bagger apparatus, the container with the finished product, a blower to remove moisture, heat recuperator exhaust gas refrigerator-capacitor capacitance for receiving centrate of decarbonization mother liquor, a pump for feeding the mother liquor of decarbonization to the residue, an evaporator for evaporation of the mother liquor of decarbonization, a crystallizer for thickening Li ₂ CO ₃ from the pulp, forming during evaporation of the mother liquor of decarbonization, a pulp pump for feeding evaporated and condensed pulp in the mold, a measuring device for evaporated and condensed pulp, a centrifuge for separating the solid phase Li ₂ CO ₃ from evaporated and condensed pulp, a container for collecting the carbonate evaporation residue, a pump for feeding carbonate the centrate of the residue in the reactor with a stirrer for reactive purification, the reactor with a stirrer for reactive purification of the carbonate centrate from boron and sulfate ions, a pump for feeding the suspension formed in the reactive purification reactor to filtration into a press filter, a press filter to remove CaB ₄ O ₇ and BaSO ₄ from the suspension to be filtered, a reactor with a stirrer for converting the carbonate centrate purified from impurities into a chloride solution, a pump for feeding the chloride solution to the evaporation, an evaporator for evaporating the chloride solution and salting out NaCl crystals, a crystallizer for separating NaCl crystals from an evaporated chloride solution, a pulp pump for removing pulp of NaCl crystals in a LiCl solution, a centrifuge to separate NaCl crystals from LiCl solution, a container for receiving clarified of concentrated LiCl solution coming from the upper zone of the NaCl crystallizer, a pump for feeding the evaporated LiCl solution to the reactor, a heated reactor with a stirrer for soda deposition of Li ₂ CO ₃ from LiCl solution, a pulp pump for feeding pulp Li ₂ CO ₃ deposited with soda from one stripped off LiCl solution, a filter press for separating precipitated Li ₂ CO ₃ from the mother liquor of soda precipitation, a source of soda solution, and also a reactor with a mixer for precipitating calcium and magnesium from the spent hydrochloric acid regeneration solution with soda or mixture sue Ba (OH) ₂ and BaCO ₃ , a pump for feeding the resulting suspension to the filtration, a filter press for separating carbonate-alkaline sediments from a NaCl or BaCl ₂ solution, a reactor with a stirrer for converting a BaCl ₂ solution to an HCl solution, a source of sulfuric acid, an intermediate container for collecting lithium-containing wash water, gas blowing for transporting carbon dioxide to a gas holder containing carbon dioxide, a source of carbon dioxide, a source of demineralized water, a recycle water collector, an unloading device for opening bags from a technical lithium carbonate, a source of steam, a source of coolant. 6. Installation according to claim 5, characterized in that the cooled reactor-carbonizer, equipped with a stirrer, has one upper branch pipe connected to a gas tank by means of a pipeline, and a pipe through a pulp pump, shut-off and control valve and another upper pipe connected to an ejector, installed inside in the upper zone of the carbonization reactor, and through the pulp pump and shut-off and control valve with the inlet pipe of a thin-layer thickener, the thin-layer pulp thickener Li ₂ CO ₃ with your lower pipe the course of the thickened pulp through the pulp pump through a pipeline is connected to the nozzle of the reactor for the preparation of pulp of technical Li ₂ CO ₃ , and the outlet for clarified carbonated solution is supplied through a pipeline with a clarified carbonated solution receiving tank, and the clarified carbonized lithium bicarbonate solution is received through a pump connected to the inlet of the filter for fine cleaning solution LiHCO _3, the output conduit connections which are connected to the receiving tank is filtered th solution LiHCO _3, acceptance tank filtered solution LiHCO ₃ via a pipe through a pump and control valve is connected to the inlet cooled ion exchange column, and through a conduit and control valve to the inlet of the filter for fine purification LiHCO ₃ solution, cooled ion exchange column his the inlet by means of pipelines through shut-off and control valves and pumps is connected to the outlet of the wash water tank, to the outlet of the regeneration tank acid solution with an outlet tank regenerant LiHCO _3, its outlet nozzle through piping and control valve connected to the intermediate vessel collecting lithium-containing washing water, to the inlet of the reactor for precipitation of calcium and magnesium from the spent hydrochloric acid regenerant and the inlet of the fine filter cleaning and with its blow-off pipe by means of a gas duct through a gas blower with a gas holder, an intermediate container for collecting lithium-containing washing d through a pipeline through a pump and shut-off and control valves connected to the inlet pipe of the water collector, with the inlet pipe of the reactor for the conversion of the carbonate centrate into the chloride solution and with the inlet pipe of the tank for receiving the evaporated LiCl solution, a fine filter of the LiHCO ₃ solution that has passed ion exchange, through the pipeline, the outlet pipe is connected to the inlet pipe of the heated circuit of the heat recuperator and through the pipeline through the shut-off and control valve with the tank inlet pipe the regenerator insulating solution LiHCO _3, heat recuperator outlet pipe heated circuit via a conduit connected to the inlet of the heated-calciner reactor inlet cooling circuit with an outlet of the centrifuge and the outlet of the cooling circuit to the inlet tank for receiving the mother decarbonization solution, heated crystallizer its sduvochnym the pipe is connected via a pipe to the discharge pipe of a heated decarbonizer reactor and by means of pipelines through a gas blower with a gas holder, the heated decarbonizer reactor with its lower pipe outlet for pulp through the pulp pump through a pipeline and shut-off and control valves is connected to its upper pipe and pipe for the inlet of the heated crystallizer pulp, the lower pipe for which pulp exit through the pulp pump through the pipeline and shut-off and control valves connected to the pulp meter and the upper pipe of the heated reactor-decarbonizer, and the upper pipe to exit svetlennogo decarbonated solution via a conduit connected to a tank receiving clarified decarbonated solution container receiving clarified decarbonated solution through a conduit across the pump is connected to the inlet of the evaporator for evaporation of the decarbonated solution and a collection of recycled water and directly with the nozzle exit Li ₂ CO ₃ clarified evaporated decarbonated crystallizer solution which is connected by a pipeline with its inlet pipe to the outlet Deck evaporator for evaporating the decarbonated solution and at its lower pipe for outlet of the pulp through the pulp pump and measuring tank via a conduit connected to the centrifuge dryer ultrapure Li ₂ CO ₃ nozzle discharging the dried product connected to the hopper of a cooled feeder, which discharge pipe is joined with bagger apparatus, the inlet of the dry carrier gas inlet with the outlet of the heated gas circuit of the heat recuperator of the wet gases leaving the dryer, the outlet of the exhaust drying wet gas dryer with an inlet pipe of the cooled gas circuit of the exhaust gas heat recuperator, the exhaust gas heat recuperator is connected to the inlet pipe of the gas circuit of the refrigerator-condenser with its outlet pipe of the cooled gas circuit, and connected to the inlet pipe of the heated gas circuit through the gas blower via the outlet pipe of the mist eliminator, which is connected by its inlet pipe to the outlet pipe of the gas circuit of the refrigerator-con a centrifuge, a centrifuge for separating Li ₂ CO ₃ crystals from an evaporated decarbonized solution, is connected via a pipeline through shut-off valves to a washing water meter, a container for collecting carbonate evaporation residue and an intermediate container for collecting lithium-containing washing water, a container for collecting carbonate evaporation residue the pipeline through a pump and a shut-off and control valve is connected to the reactor with a stirrer for the reactive purification of the carbonate centrate of the residue from boron and sulfate ions, Torr stirred for reagent purification carbonate of supernatant residue at its lower pipe to exit the slurry through the pump via a conduit and a control valve connected to its upper pipe and inlet filter press for the removal of filterable slurry solids CaB ₄ O ₇ and BaSO _4, which through its outlet pipe is connected to the inlet pipe of the reactor for the conversion of the carbonate concentrate from the evaporation into a chloride solution, the other upper pipes of which are connected by a pipe water with a press filter outlet for removing calcium and magnesium carbonate precipitates from the spent regeneration solution after its reagent treatment, an intermediate container for collecting lithium-containing wash water and an overflow nozzle for crystallizing NaCl crystals from the evaporated chloride solution, and a lower reactor nozzle for converting carbonate the evaporation centrate of the chloride solution through the pump through a pipeline connected to the inlet of the evaporator for evaporation of the chloride solution of the creator, an evaporator for evaporating the chloride solution with its pipe for exiting the evaporated chloride solution through a pipeline is connected to the inlet of the crystallizer for separating NaCl crystals from the evaporated chloride solution, a crystallizer for separating NaCl crystals from the evaporated chloride solution with its lower pipe for exiting the condensed pulp through the pipe through the meter is connected to the inlet of the centrifuge, and the side pipe for the exit of the clarified concentrated LiCl solution with a container for receiving a clarified concentrated LiCl solution, a centrifuge for separating NaCl crystals from an evaporated chloride solution with its own pipe for exiting a centrate through a pipe connected to a receiving pipe for a centrate of a NaCl crystallizer, a container for receiving a clarified concentrated LiCl solution through a pipe is connected to an intermediate container for collecting lithium-containing wash water and through a conduit through a pump to the reactor soda deposition Li ₂ CO ₃ from the clarified concentrated stretching ora LiCl, reactor soda deposition of Li ₂ CO ₃ from the clarified concentrated solution of its bottom nozzle exit pulp Li ₂ CO ₃ through a pump and control valve via a conduit connected to the inlet of a press filter to separate Li ₂ CO ₃ from the mother liquor the operation of soda deposition, and the upper nozzle for entering the soda solution with a source of soda solution, a press filter for separating Li ₂ CO ₃ from the mother liquor; the operation of soda deposition with its nozzle the outlet of the filtrate containing impurity Li ₂ C O ₃ , through a pipe connected to one of the upper nozzles of the reactor for converting the carbonate concentrate of the residue into a chloride solution, the source of soda solution through a pipe through a shut-off valve connected to the inlet of the soda solution of the reactor for precipitation of calcium and magnesium from the spent hydrochloric acid regeneration solution, blow-off the nozzle of which is connected to the gas holder through a gas blower by means of a pipeline, and the lower nozzle for the outlet of the suspension through valves and a pump the ohm of pipelines is connected to the inlet pipe of the press filter for separating precipitation from NaCl or HCl solutions and through a pipe with the outlet pipe of the reactor for converting BaCl ₂ solution to HCl, a filter press for separating precipitation from NaCl or HCl solutions resulting from the reagent treatment of spent hydrochloric acid regeneration solution, through its outlet pipe through pipelines and shut-off and control valves connected to a tank for a solution of hydrochloric acid and a reactor with a stirrer for the conversion of carbonate a centrate in a chloride solution; a reactor for converting a BaCl ₂ solution into an HCl solution is connected to a sulfuric acid source through a pipeline and a shut-off and control valve. 7. Installation according to paragraphs. 5, 6, characterized in that the cooling circuits of the reactor for the preparation of Li ₂ CO ₃ pulp, a carbonizer reactor, a thin-layer thickener, a condenser refrigerator, a filling device feeder are connected via pipelines to a cooling source circulating in the coolant circuits; heating circuits of a decarbonization reactor, crystallizer for separating ultrapure Li ₂ CO ₃ from a decarbonization LiHCO ₃ solution, an ultrapure Li ₂ CO ₃ dryer, a soda deposition reactor Li ₂ CO ₃ from a concentrated LiCl solution, an evaporation apparatus for evaporating the decarbonization mother liquor, an evaporator for evaporation of the chloride solution through pipelines connected to a source of sharp heating steam, and condensate collectors of the above steam-heated equipment through pipelines connected with a recycle water collector connected via pipelines to a source of demineralized water.

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