Impurity and slag removal treatment system in lithium carbonate production and lithium carbonate production system

Abstract

The utility model discloses an impurity and slag removal treatment system in lithium carbonate production and a lithium carbonate production system, and solves the technical problems of lithium loss and insufficient utilization of colloid precipitates such as Fe (OH) 3 and Al (OH) 3 in the prior art. The impurity and slag removal treatment system in lithium carbonate production comprises a roasting furnace used for roasting impurity and slag removal and outputting roasted materials; the first size mixing tank is used for adding water into the roasted material for size mixing and outputting first size; and the first filtering equipment is used for filtering the first slurry and outputting first filter residues and first filtrate.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium carbonate production, and specifically, to an impurity removal slag treatment system in lithium carbonate production and a lithium carbonate production system. Background Art

[0002] At present, the main process for preparing lithium carbonate from spodumene raw materials by the acid method is as follows: roasting spodumene raw materials to obtain spodumene clinker → acidifying spodumene clinker to obtain spodumene acidified material → adjusting the slurry with water → purification → lithium extraction.

[0003] In the roasting section:

[0004] First of all, the chemical composition of spodumene is K{Li 2-x Al 1+x [Al 2x Si 4-2x O 10 (OH,F)2}(x = 0 - 0.5), and generally contains 2 - 7% of fluorine element. The main function of roasting is to remove the fluorine element in the spodumene raw materials. Steam defluorination uses the reaction between spodumene raw materials and steam in the roasting kiln under high temperature conditions to generate high-temperature hydrogen fluoride gas, and the fluorine element is removed from the spodumene raw materials in the form of hydrogen fluoride gas. The defluorination flue gas generated during the steam defluorination process contains hydrogen fluoride gas and steam. Therefore, the defluorination flue gas has the dual characteristics of high temperature and high corrosion, resulting in a complex design and high cost of the hydrogen fluoride recovery system when the defluorination flue gas is directly applied to hydrogen fluoride production.

[0005] Secondly, in the traditional roasting section, natural gas is directly burned and heated into the roasting kiln. Due to the influence of various factors such as air flow and material position on the heating elements in the kiln, it is usually difficult to achieve precise temperature control. This not only leads to uneven temperature distribution in the kiln, where hot spots and cold spots may exist simultaneously, thus affecting product quality and consistency, but also easily causes a large amount of heat energy loss, increasing energy consumption. Moreover, the combustion of natural gas causes an increase in the content of pollutants such as HF, NO X , SO2, etc. in the defluorination flue gas output from the roasting kiln, and the flue gas volume is large. To meet the standard environmental emissions, the defluorination flue gas needs to be treated for dust removal, denitrification, and desulfurization, which increases the pollution control difficulty, project investment, and operation cost at the treatment end.

[0006] In the acidification section:

[0007] First, the lithium in the lithium mica clinker is converted into soluble lithium through acidification roasting, and then the soluble lithium can be leached out by adding water to adjust the slurry. The traditional acidification section is to directly burn and heat the acidification kiln by introducing natural gas. Since the heating elements in the kiln are affected by many factors such as airflow and material position, it is usually difficult to achieve accurate temperature control, which not only leads to uneven temperature distribution in the kiln, but also hot spots and cold spots may exist at the same time, thus affecting product quality and consistency, and easily causing a large amount of heat energy loss, increasing energy consumption. At the same time, the combustion of natural gas causes the acidification kiln to output a large amount of acidification flue gas, which contains acid mist, and the subsequent treatment equipment is large, with high investment and large land occupation.

[0008] Secondly, during the acidification and roasting process, because other elements are leached out with the lithium element at the same time, the amount of acid added will far exceed the theoretical amount of acid required for leaching lithium. The large amount of acid used will increase production costs, is not friendly to environmental protection, and increase the subsequent treatment pressure of the acidic liquid.

[0009] In the water adding and slurry mixing section:

[0010] In order to improve the lithium leaching rate, the traditional process requires the lepidolite raw material or lepidolite clinker to be ground to a finer particle size (usually less than 200 mesh) to obtain a higher lithium leaching rate in the acidification stage, so that it can be dissolved into the liquid phase in the water addition and slurry mixing stage. However, the grinding process not only increases the complexity of the process, but also increases the energy consumption of the entire process, and also increases the difficulty of subsequent filtration.

[0011] In the purification section:

[0012] The traditional purification process is to use a pump to transport the slurry into the neutralization tank after adding water and adjusting the slurry. Calcium oxide or calcium hydroxide is added to the neutralization tank to neutralize the residual acid in the lithium mica acidified material and adjust the pH to about 6.5. After the neutralization and pH adjustment are completed, the slurry is pumped to the pressing system for solid-liquid separation. The liquid phase is the leachate and the solid phase is the impurity removal residue.

[0013] First, the use of calcium oxide or calcium hydroxide alone cannot achieve deep purification. The resulting purified liquid still contains a large amount of impurity metal ions, especially calcium ions. The leaching liquid must be further purified later, which is complex, energy-intensive, and requires a large amount of reagents. In order to precipitate Fe and Al as much as possible, excessive calcium ions are usually added, which will generate more calcium sulfate precipitation in the sulfuric acid method, increase the amount of slag, and thus increase the cost of subsequent waste slag disposal.

[0014] Secondly, during the neutralization and pH adjustment process, colloidal precipitates such as Fe(OH)3 and Al(OH)3 are generated. These precipitates have adsorbability to lithium ions, not only directly entraining lithium salts, but also easily clogging the filter pores, causing difficulties in pressing and dewatering, increasing the moisture content of the impurity-removed slag obtained by dewatering, increasing the amount of lithium salts carried away, and further increasing the loss of lithium. Therefore, the impurity-removed slag needs to be washed repeatedly to reduce the loss of lithium. However, this will not only increase the water consumption and energy consumption of the system, but also part of the lithium salts entrained by the impurity-removed slag are difficult to be washed out, and the lithium loss is still relatively high. Moreover, the resources of colloidal precipitates such as Fe(OH)3 and Al(OH)3 in the impurity-removed slag are not fully utilized. Utility Model Content

[0015] In the first aspect, the main purpose of the present utility model is to provide the first roasting system for lithium mica raw materials to solve the technical problem of high cost in treating defluorination flue gas in the prior art. The technical solution is as follows:

[0016] The first roasting system for lithium mica raw materials includes: a condensation component for condensing the defluorination flue gas generated by the roasting kiln and outputting a gas-liquid-solid mixture; the condensation component includes a condensation pipe and a cooling jacket connected to the flue gas outlet of the roasting kiln; a buffer component for temporarily storing the gas-liquid-solid mixture; the buffer component includes a buffer tank connected to the condensation pipe; an absorption component for absorbing the non-condensable substances in the buffer tank; the absorption component includes an absorption device connected to the non-condensable substances in the buffer tank; a reflux component for refluxing the tail gas to the buffer tank when the hydrogen fluoride in the tail gas discharged from the absorption component exceeds a preset value; the reflux component includes a hydrogen fluoride detection device provided at the tail gas outlet of the absorption device and a reflux pipe connecting the buffer tank and the downstream pipeline of the hydrogen fluoride detection device.

[0017] As a further improvement of the above-mentioned roasting system for lithium mica raw materials: the condensation pipe is made of polytetrafluoroethylene pipe, or the inner wall of the condensation pipe has a polytetrafluoroethylene coating.

[0018] As a further improvement of the above-mentioned roasting system for lithium mica raw materials: the condensation pipe is inclined, and the connection of the condensation pipe to the flue gas outlet of the roasting kiln is higher than the connection of the condensation pipe to the buffer tank.

[0019] As a further improvement of the above-mentioned roasting system for lithium mica raw materials: the absorption component includes at least two absorption devices arranged in series.

[0020] As a further improvement of the above-mentioned roasting system for lithium mica raw materials: the treatment system further includes a neutralization reaction component for reacting the condensate in the buffer tank with an alkali solution, and the neutralization reaction component includes a neutralization reaction tank.

[0021] As a further improvement to the above-mentioned roasting system for lepidolite raw materials: The treatment system further includes a solid-liquid separation component for performing solid-liquid separation on the solid-liquid mixture output from the buffer tank and the absorption component or on the solid-liquid mixture output from the neutralization reaction tank and the absorption component.

[0022] As a further improvement to the above-mentioned roasting system for lepidolite raw materials: A liquid level gauge is provided on the buffer tank, and a first valve interlocked with the liquid level gauge is provided on the connecting pipe between the buffer tank and the neutralization reaction component or on the connecting pipe between the buffer tank and the solid-liquid separation component.

[0023] As a further improvement to the above-mentioned roasting system for lepidolite raw materials: The solid-liquid separation component is a filtering device or a centrifugal device.

[0024] As a further improvement to the above-mentioned roasting system for lepidolite raw materials: A second valve and a third valve interlocked with the hydrogen fluoride detection device are respectively provided on the downstream pipeline and the reflux pipeline.

[0025] In the second aspect, the main object of the present invention is to provide a second roasting system for lepidolite raw materials to solve the technical problems caused by direct heating with natural gas in the prior art. The technical solution is as follows:

[0026] The second roasting system for lepidolite raw materials includes a roasting kiln for roasting lepidolite raw materials. The roasting system for lepidolite raw materials further includes: a heating jacket for the roasting kiln to heat the roasting kiln; a first heat exchanger for performing heat exchange between the dried lepidolite raw materials to be fed into the roasting kiln and the first defluorinated flue gas output from the roasting kiln; a second heat exchanger for performing heat exchange between the second defluorinated flue gas output from the first heat exchanger and the defluorinating agent to be fed into the roasting kiln; and a third heat exchanger for performing heat exchange between the primary cold air output from the heating jacket of the roasting kiln and the cold air.

[0027] As a further improvement to the above-mentioned roasting system for lepidolite raw materials: The first heat exchanger is a cyclone preheater.

[0028] As a further improvement to the above-mentioned roasting system for lepidolite raw materials: The roasting system for lepidolite raw materials further includes a first dust collector, an arsenic recovery unit, and a hydrogen fluoride recovery unit for sequentially treating the third defluorinated flue gas output from the second heat exchanger.

[0029] As a further improvement to the above-mentioned roasting system for lepidolite raw materials: The roasting system for lepidolite raw materials further includes a buffer bin for dried lepidolite raw materials. The particulate matter intercepted by the first dust collector flows into the buffer bin for dried lepidolite raw materials, and the buffer bin for dried lepidolite raw materials outputs dried lepidolite raw materials to the first heat exchanger for heat exchange with the first defluorinated flue gas output from the roasting kiln.

[0030] As a further improvement of the above-mentioned roasting system for lepidolite raw materials: The lepidolite raw material roasting system further includes a lepidolite raw material bin for storing lepidolite raw materials and a drying kiln for drying the lepidolite raw materials. The hot air obtained after the third heat exchanger processes the cold air flows into the drying kiln as a heat source, and the dried lepidolite dry material after being dried by the drying kiln flows into the lepidolite buffer bin.

[0031] As a further improvement of the above-mentioned roasting system for lepidolite raw materials: The lepidolite raw material roasting system further includes a second dust collector for dust removal treatment of the lepidolite dust gas output by the drying kiln, and the particulate matter intercepted by the second dust collector flows into the lepidolite raw material bin.

[0032] As a further improvement of the above-mentioned roasting system for lepidolite raw materials: The lepidolite raw material roasting system further includes a roasting kiln hot blast stove for heating the energy gas and outputting the jacket gas for heating the roasting kiln to the heating jacket of the roasting kiln. The secondary cold air obtained after the third heat exchanger processes the primary cold air flows into the roasting kiln hot blast stove as the energy gas.

[0033] As a further improvement of the above-mentioned roasting system for lepidolite raw materials: The lepidolite raw material roasting system further includes a roasting kiln cooler for cooling the lepidolite clinker output by the roasting kiln and a lepidolite clinker storage tank for storing the lepidolite clinker.

[0034] In the third aspect, the main object of the present invention is to provide a lepidolite clinker acidification system to solve the technical problems caused by direct heating with natural gas in the prior art. The technical solution is as follows:

[0035] The lepidolite clinker acidification system includes an acidification kiln for acidifying the lepidolite clinker. The lepidolite clinker is obtained by roasting lepidolite raw materials. The lepidolite clinker acidification system further includes: a filter for filtering the acidification flue gas output by the acidification kiln and outputting dust and low-dust gas; an acidification kiln heating jacket for heating the acidification kiln; an acidification kiln hot blast stove for inputting the jacket gas for heating the acidification kiln into the acidification kiln heating jacket; wherein, a part of the cold air output by the acidification kiln heating jacket flows into the acidification kiln hot blast stove as the energy gas.

[0036] As a further improvement of the above-mentioned lepidolite clinker acidification system: The lepidolite clinker acidification system further includes an acid storage tank, a lepidolite clinker storage tank, and a mixed acid machine for mixing the lepidolite clinker and acid.

[0037] As a further improvement of the above-mentioned lepidolite clinker acidification system: The lepidolite clinker acidification system further includes a salt storage tank, and the mixed acid machine is used to mix the lepidolite clinker, acid, and salt.

[0038] As a further improvement of the above-mentioned lepidolite clinker acidification system: The dust output by the filter flows into the mixed acid machine.

[0039] As a further improvement of the above-mentioned acidification system for lepidolite clinker: the acidification system for lepidolite clinker further includes a deacidification device for deacidifying the low-dust gas output by the filter.

[0040] As a further improvement of the above-mentioned acidification system for lepidolite clinker: the deacidification device is a spray tower.

[0041] As a further improvement of the above-mentioned acidification system for lepidolite clinker: the acidification system for lepidolite clinker further includes an acidification kiln cooler for cooling the lepidolite acidified material output by the acidification kiln and a lepidolite acidified material storage tank for storing the lepidolite acidified material.

[0042] Fourthly, the main object of the present utility model is to provide a method for pretreating lepidolite raw materials to solve the technical problems caused by high acid consumption in the prior art. The technical solution is as follows:

[0043] A method for pretreating lepidolite raw materials for leaching lithium elements in the lepidolite raw materials. The pretreatment method includes steps: roasting the lepidolite raw materials to obtain lepidolite clinker; roasting the lepidolite clinker, salt and acid to obtain lepidolite acidified material.

[0044] As a further improvement of the above-mentioned method for pretreating lepidolite raw materials: roasting the mixture of lepidolite clinker, salt and acid at 200-320 °C for 0.5-1.5 h, and cooling to obtain lepidolite acidified material.

[0045] As a further improvement of the above-mentioned method for pretreating lepidolite raw materials: first roasting the mixture of lepidolite clinker and salt at 800-900 °C for 0.5-1.5 h, then cooling to 200-320 °C, adding acid and continuing to keep warm for 0.5-1.5 h, and cooling to obtain lepidolite acidified material.

[0046] As a further improvement of the above-mentioned method for pretreating lepidolite raw materials: the acid is sulfuric acid; the salt is any several of potassium sulfate, sodium sulfate, calcium sulfate.

[0047] As a further improvement of the above-mentioned method for pretreating lepidolite raw materials: the mass ratio of sulfate to lepidolite clinker is (0.03-0.15):1.

[0048] As a further improvement of the above-mentioned method for pretreating lepidolite raw materials: the mass ratio of sulfuric acid to lepidolite clinker is (0.2-0.45):1.

[0049] As a further improvement of the above-mentioned method for pretreating lepidolite raw materials: the pretreatment method further includes a step of ball-milling and mixing the lepidolite clinker and salt.

[0050] As a further improvement of the above-mentioned pretreatment method of lepidolite raw materials: the lepidolite raw materials are calcined at 800-1000 °C.

[0051] As a further improvement of the above-mentioned pretreatment method of lepidolite raw materials: it further includes the steps of:

[0052] Water is added to the acidified lepidolite material to form a slurry, and then high-speed stirring is carried out to obtain a slurry;

[0053] After solid-liquid separation of the slurry, a leaching solution and leaching residues are obtained.

[0054] Fifthly, the main purpose of the present invention is to provide a lepidolite raw material pretreatment system to solve the technical problems caused by grinding treatment of lepidolite raw materials or lepidolite clinker in the prior art. The technical solution is as follows:

[0055] The lepidolite raw material pretreatment system includes: a lepidolite raw material calcination system for calcining lepidolite raw materials and outputting lepidolite clinker; the lepidolite raw material calcination system includes a calcination kiln; a lepidolite clinker acidification system for acidifying lepidolite clinker and outputting acidified lepidolite material; the lepidolite clinker acidification system includes an acidification kiln; a lepidolite acidified material slurry preparation system for preparing a slurry of the acidified lepidolite material by adding water and outputting a lithium leaching solution; the lepidolite acidified material slurry preparation system includes a high-speed dispersion device for performing high-speed dispersion treatment on the lithium leaching solution. Among them, the lepidolite raw material calcination system is preferably the lepidolite raw material calcination system described in the second aspect above, and the lepidolite clinker acidification system is preferably the lepidolite clinker acidification system described in the third aspect above.

[0056] Sixthly, the main purpose of the present invention is to provide a lepidolite acidified material leaching system to solve the technical problems of lithium loss and filter hole blockage caused by first neutralizing and adjusting the pH and then filtering in the prior art. The technical solution is as follows:

[0057] The lepidolite acidified material leaching system includes, connected in sequence: a lepidolite acidified material slurry preparation system for preparing a slurry of the acidified lepidolite material by adding water and outputting a turbid lithium leaching solution; a primary filtration component for filtering the turbid lithium leaching solution and outputting a clear lithium leaching solution and leaching residues; a washing and filtration component for washing the leaching residues and outputting a lithium washing solution and washed lithium residues, and the lithium washing solution is used as the lithium leaching solution.

[0058] As a further improvement of the above-mentioned lepidolite acidified material leaching system: the lepidolite acidified material slurry preparation system includes a lepidolite acidified material slurry preparation tank and / or includes a high-speed dispersion device for performing high-speed dispersion treatment on the turbid lithium leaching solution.

[0059] As a further improvement of the above-mentioned lepidolite acidified material leaching system: the primary filtration component includes a primary plate and frame filter press.

[0060] As a further improvement of the above-mentioned leaching system for acidified spodumene material: The washing and filtering assembly includes:

[0061] A primary pulp mixing tank for mixing the leaching residue with water to form a primary pulp and outputting the primary pulp;

[0062] A primary filtering device for filtering the primary pulp to output a primary filter residue and a primary filtrate.

[0063] As a further improvement of the above-mentioned leaching system for acidified spodumene material: The washing and filtering assembly further includes:

[0064] A secondary pulp mixing tank for mixing the primary filter residue with water to form a secondary pulp and outputting the secondary pulp;

[0065] A secondary filtering device for filtering the secondary pulp to output a secondary filter residue and a secondary filtrate.

[0066] As a further improvement of the above-mentioned leaching system for acidified spodumene material: It further includes an intermediate tank for storing the clear lithium leaching solution, and both the primary filtrate and the secondary filtrate flow into the intermediate tank as lithium washing solutions and are used as lithium leaching solutions.

[0067] In a seventh aspect, the main purpose of the present utility model is to provide a method and a system for treating impurity removal slag in lithium carbonate production to solve the technical problems of lithium loss and insufficient utilization of colloidal precipitates such as Fe(OH)3 and Al(OH)3 in the prior art. The technical solution is as follows:

[0068] A method for treating impurity removal slag in lithium carbonate production includes the following steps:

[0069] (1) Roasting the impurity removal slag to obtain a roasted material;

[0070] (2) Mixing the roasted material with water to form a pulp and then filtering to obtain a filter residue and a filtrate, and the filtrate is used as a lithium leaching solution.

[0071] As a further improvement of the above-mentioned method for treating impurity removal slag in lithium carbonate production: It further includes drying the impurity removal slag before roasting.

[0072] As a further improvement of the above-mentioned method for treating impurity removal slag in lithium carbonate production: The roasting temperature is 200 - 400 °C, and the roasting time is 20 - 80 minutes.

[0073] As a further improvement of the above-mentioned method for treating impurity removal slag in lithium carbonate production: The liquid-solid ratio in mixing with water is (1 - 3):1, and after stirring at 30 - 80 °C for 20 - 60 minutes, it is filtered.

[0074] As a further improvement to the method for treating impurity removal slag in the above lithium carbonate production: Step (2) includes: adding water to the calcined material to adjust the pulp, followed by filtration to obtain a first filter residue and a first filtrate; adding water to the first filter residue to adjust the pulp, followed by filtration to obtain a second filter residue and a second filtrate.

[0075] As a further improvement to the method for treating impurity removal slag in the above lithium carbonate production: Step (2) further includes: adding water to the second filter residue to adjust the pulp, followed by filtration to obtain a third filter residue and a third filtrate; the first filtrate, the second filtrate, and the third filtrate are combined as the filtrate and used as the lithium leaching solution.

[0076] As a further improvement to the method for treating impurity removal slag in the above lithium carbonate production: The preparation of the impurity removal slag includes the steps:

[0077] (1) Adding an alkali solution to the lithium leaching solution until the pH is 2 - 3;

[0078] (2) Continuing to add crystal seeds to the lithium leaching solution, where the crystal seeds include Al2O3 and / or Fe2O3;

[0079] (3) Continuing to add an alkali solution to the lithium leaching solution until the pH is 6 - 8 to obtain a solid-liquid mixture;

[0080] (4) Filtering the solid-liquid mixture to obtain the impurity removal slag and the purified solution.

[0081] As a further improvement to the method for treating impurity removal slag in the above lithium carbonate production: The crystal seeds are the third filter residue.

[0082] As a further improvement to the method for treating impurity removal slag in the above lithium carbonate production: The preparation of the impurity removal slag includes the steps:

[0083] (1) Adding hydrogen peroxide to the lithium leaching solution to obtain an oxidation solution;

[0084] (2) Adding an alkali solution to the oxidation solution until the pH is 6 - 8 to obtain a first solid-liquid mixture;

[0085] (3) Filtering the first solid-liquid mixture to obtain a first impurity removal slag and a filtrate;

[0086] (4) Adding an alkali solution to the filtrate until the pH is 10 - 12, and then adding a soluble carbonate to obtain a second solid-liquid mixture;

[0087] (5) Filtering the second solid-liquid mixture to obtain a second impurity removal slag and a purified solution; the impurity removal slag includes at least the first impurity removal slag. For example, it can contain only the first impurity removal slag, or it can be a mixture of the first impurity removal slag and the second impurity removal slag.

[0088] The impurity removal slag treatment system in lithium carbonate production includes: a roasting furnace for roasting the impurity removal slag and outputting roasted materials; a first slurry mixing tank for mixing the roasted materials with water to form a first slurry; and a first filtering device for filtering the first slurry to output a first filter residue and a first filtrate.

[0089] As a further improvement to the above impurity removal slag treatment system in lithium carbonate production: it further includes a drying device for drying the impurity removal slag.

[0090] As a further improvement to the above impurity removal slag treatment system in lithium carbonate production: it further includes:

[0091] A second slurry mixing tank for mixing the first filter residue with water to form a second slurry;

[0092] A second filtering device for filtering the second slurry to output a second filter residue and a second filtrate.

[0093] As a further improvement to the above impurity removal slag treatment system in lithium carbonate production: it further includes:

[0094] A third slurry mixing tank for mixing the second filter residue with water to form a third slurry;

[0095] A third filtering device for filtering the third slurry to output a third filter residue and a third filtrate.

[0096] As a further improvement to the above impurity removal slag treatment system in lithium carbonate production: it further includes an intermediate tank, and the first filtrate, the second filtrate, and the third filtrate flow into the intermediate tank and are used as lithium leaching solution.

[0097] As a further improvement to the above impurity removal slag treatment system in lithium carbonate production: it further includes a filter residue storage tank for storing the third filter residue.

[0098] As a further improvement to the above impurity removal slag treatment system in lithium carbonate production: the roasting furnace is an external heat type roasting furnace.

[0099] In the eighth aspect, the main purpose of the present utility model is to provide a first lithium leaching solution purification method and a lithium leaching solution purification system to solve the technical problem of incomplete purification caused by simply using calcium oxide or calcium hydroxide in the prior art. The technical solution is as follows:

[0100] First, a lithium leaching solution purification method, including the following steps:

[0101] (1) Adding hydrogen peroxide to the lithium leaching solution to obtain an oxidation solution;

[0102] (2) Adding an alkali solution to the oxidation solution until the pH is 6 - 8 to obtain a first solid-liquid mixture;

[0103] (3) Filter the first solid-liquid mixture to obtain the first impurity removal residue and the filtrate;

[0104] (4) Add alkali solution to the filtrate until the pH is 10 - 12, and then add soluble carbonate to obtain the second solid-liquid mixture;

[0105] (5) Filter the second solid-liquid mixture to obtain the second impurity removal residue and the purified liquid.

[0106] As a further improvement of the above lithium leaching solution purification method: In step (1): The dosage of hydrogen peroxide is 1.1 - 1.4 times the mass of Fe in the lithium leaching solution. Hydrogen peroxide is prepared as a solution with a mass fraction of 22% - 30% and used. After reacting for 10 - 30 minutes, an oxidation solution is obtained. 2+ After reacting for 10 - 30 minutes, an oxidation solution is obtained.

[0107] As a further improvement of the above lithium leaching solution purification method: In step (2): The alkali solution is potassium hydroxide and / or sodium hydroxide. After adjusting the pH to 6 - 8 and reacting for another 10 - 30 minutes, the first solid-liquid mixture is obtained.

[0108] As a further improvement of the above lithium leaching solution purification method: In step (4): The alkali solution is potassium hydroxide and / or sodium hydroxide. After adding soluble carbonate and reacting for 10 - 30 minutes, the second solid-liquid mixture is obtained.

[0109] As a further improvement of the above lithium leaching solution purification method: Steps (2) and (4) are carried out at 40 - 60 °C; Flocculants are also used in steps (2) and (4).

[0110] As a further improvement of the above lithium leaching solution purification method: In step (4): The carbonate is potassium carbonate and / or sodium carbonate, and its dosage calculated as carbonate ion is 1.05 - 1.1 times the molar amount of Ca in the filtrate. 2+ 1.05 - 1.1 times the molar amount.

[0111] As a further improvement of the above lithium leaching solution purification method: It further includes step (6): Carry out resin adsorption treatment on the purified liquid.

[0112] As a further improvement of the above lithium leaching solution purification method: In step (6), first expand the resin with water, then wash the resin with a hydrochloric acid solution with a mass fraction of 4 - 5%, and finally wash the resin to neutral with a potassium hydroxide and / or sodium hydroxide solution with a mass fraction of 2 - 4%.

[0113] As a further improvement of the above lithium leaching solution purification method: The purification method further includes a step of filtering the lithium leaching solution obtained by adding water to adjust the slurry of the lepidolite acidified material.

[0114] First type, a lithium leaching solution purification system, comprising: a first reaction assembly for reacting a lithium leaching solution, hydrogen peroxide, and an alkali solution to form a first solid-liquid mixture; the first reaction assembly includes a first reaction tank, a hydrogen peroxide dosing device for adding hydrogen peroxide to the first reaction tank, a first alkali dosing device for adding an alkali solution to the first reaction tank, a first pH detector for detecting the pH of the material in the first reaction tank, and a first stirrer for stirring the material in the first reaction tank; a first filtration assembly for filtering the first solid-liquid mixture and outputting a first impurity removal residue and a purified solution; a second reaction assembly for reacting the filtrate, an alkali solution, and a carbonate to form a second solid-liquid mixture; the second reaction assembly includes a second reaction tank, a second alkali dosing device for adding an alkali solution to the second reaction tank, a carbonate dosing device for adding a carbonate to the second reaction tank, a second pH detector for detecting the pH of the material in the second reaction tank, and a second stirrer for stirring the material in the second reaction tank; a second filtration assembly for filtering the second solid-liquid mixture and outputting a second impurity removal residue and a purified solution.

[0115] As a further improvement of the above lithium leaching solution purification system: the first reaction assembly further includes a first flocculant dosing device for adding a flocculant to the first reaction tank.

[0116] As a further improvement of the above lithium leaching solution purification system: the second reaction assembly further includes a second flocculant dosing device for adding a flocculant to the second reaction tank.

[0117] As a further improvement of the above lithium leaching solution purification system: the first filtration assembly includes a first plate and frame filter press.

[0118] As a further improvement of the above lithium leaching solution purification system: the second filtration assembly includes a second plate and frame filter press and a precision filter connected in sequence.

[0119] As a further improvement of the above lithium leaching solution purification system: the purification system further includes a resin adsorption device for performing resin adsorption treatment on the purified solution.

[0120] As a further improvement of the above lithium leaching solution purification system: the purification system further includes a primary filtration assembly for filtering the lithium leaching solution obtained by adding water to the acidified material of lepidolite for slurry adjustment.

[0121] As a further improvement of the above lithium leaching solution purification system: the primary filtration assembly includes a primary plate and frame filter press.

[0122] In the ninth aspect, the main purpose of the present utility model is to provide a second lithium leaching solution purification method and a lithium leaching solution purification system to solve the technical problem of incomplete purification caused by simply using calcium oxide or calcium hydroxide in the prior art. The technical solution is as follows:

[0123] The second kind is a method for purifying lithium leaching solution, including the following steps:

[0124] (1) Add alkali solution to the lithium leaching solution until the pH is 2 - 3;

[0125] (2) Continue to add seed crystals to the lithium leaching solution, and the seed crystals include any several of Al2O3, Fe2O3, Fe(OH)3, and Al(OH)3;

[0126] (3) Continue to add alkali solution to the lithium leaching solution until the pH is 6 - 8 to obtain a solid - liquid mixture;

[0127] (4) Filter the solid - liquid mixture to obtain impurity - removed slag and purified solution.

[0128] As a further improvement of the above - mentioned method for purifying lithium leaching solution: in step (1), the alkali solution is potassium hydroxide and / or sodium hydroxide; step (1) is carried out at a rotation speed of 200 - 400 revolutions per minute.

[0129] As a further improvement of the above - mentioned method for purifying lithium leaching solution: in step (2), the mass of the seed crystals added to every 1 L of lithium leaching solution is 0.05% - 0.5% of the liquid volume.

[0130] As a further improvement of the above - mentioned method for purifying lithium leaching solution: the preparation method of the seed crystals includes the steps of adding alkali solution to the lithium leaching solution until the pH is 6 - 8, collecting the generated precipitation slag, and performing roasting treatment on the precipitation slag to obtain the seed crystals.

[0131] As a further improvement of the above - mentioned method for purifying lithium leaching solution: when pH ≤ 3, the stirring rate is 200 - 400 revolutions per minute, when pH > 3, the stirring rate ≤ 100 revolutions per minute; after the pH is adjusted, the reaction lasts for 20 - 40 minutes for liquid - solid separation.

[0132] As a further improvement of the above - mentioned method for purifying lithium leaching solution: the preparation method of the seed crystals includes the steps of performing roasting treatment on the impurity - removed slag, then adding water to adjust the slurry and filtering, and the obtained filter residue is the seed crystals.

[0133] As a further improvement of the above - mentioned method for purifying lithium leaching solution: the roasting temperature is 200 - 400 °C, and the roasting time is 20 - 80 minutes.

[0134] As a further improvement of the above - mentioned method for purifying lithium leaching solution: step (3) is carried out at a rotation speed of 50 - 150 revolutions per minute; the reaction duration in step (3) is 30 - 120 minutes; a flocculant is also used in step (3).

[0135] As a further improvement of the above - mentioned method for purifying lithium leaching solution: it further includes step (5): performing resin adsorption treatment on the purified solution.

[0136] Second, a lithium leaching solution purification system, comprising: a reaction assembly for reacting a lithium leaching solution, an alkali solution and seeds to form a solid-liquid mixture; the reaction assembly includes a reaction tank, an alkali solution dosing device for adding the alkali solution into the reaction tank, a seed dosing device for adding seeds into the reaction tank, a pH detector for detecting the pH of the material in the reaction tank, and a stirrer for stirring the material in the reaction tank; a filtration assembly for filtering the solid-liquid mixture and outputting impurity slag and purified liquid.

[0137] As a further improvement of the above lithium leaching solution purification system: the reaction assembly further includes a flocculant dosing device for adding a flocculant into the reaction tank.

[0138] As a further improvement of the above lithium leaching solution purification system: the filtration assembly includes a plate and frame filter press and a precision filter connected in sequence.

[0139] As a further improvement of the above lithium leaching solution purification system: the purification system further includes a resin adsorption device for performing resin adsorption treatment on the purified liquid.

[0140] As a further improvement of the above lithium leaching solution purification system: the purification system further includes a primary filtration assembly for filtering the lithium leaching solution obtained by adding water for slurry adjustment.

[0141] As a further improvement of the above lithium leaching solution purification system: the primary filtration assembly includes a primary plate and frame filter press.

[0142] In the tenth aspect, the main object of the present invention is to provide a lithium carbonate production method and a lithium carbonate production system with simple process, low energy consumption, high lithium recovery rate and good product quality. The technical solutions are as follows:

[0143] The lithium carbonate production system includes any several of the systems described in the above nine aspects.

[0144] The lithium carbonate production method uses the above lithium carbonate production system.

[0145] The following further describes the present invention in conjunction with the drawings and specific embodiments. The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0146] The drawings constituting a part of the present invention are used to assist in understanding the present invention. The content provided in the drawings and the related description in the present invention can be used to explain the present invention, but do not constitute an improper limitation to the present invention.

[0147] In the drawings:

[0148] Figure 1 The structural schematic diagram of the first embodiment of the roasting system for lepidolite raw materials of the present utility model.

[0149] Figure 2 The structural schematic diagram of the second embodiment of the roasting system for lepidolite raw materials of the present utility model.

[0150] Figure 3 The structural schematic diagram of the third embodiment of the roasting system for lepidolite raw materials of the present utility model.

[0151] Figure 4 The structural schematic diagram of the first embodiment of the acidification system for lepidolite clinker of the present utility model.

[0152] Figure 5 The structural schematic diagram of the second embodiment of the acidification system for lepidolite clinker of the present utility model.

[0153] Figure 6 The structural schematic diagram of the embodiment of the pretreatment system for lepidolite raw materials of the present utility model.

[0154] Figure 7 The structural schematic diagram of the embodiment of the leaching system for acidified lepidolite materials of the present utility model.

[0155] Figure 8 The structural schematic diagram of the embodiment of the impurity removal slag treatment system in lithium carbonate production of the present utility model.

[0156] Figure 9 The structural schematic diagram of the first embodiment of the purification system for lithium leaching solution of the present utility model.

[0157] Figure 10 The structural schematic diagram of the second embodiment of the purification system for lithium leaching solution of the present utility model.

[0158] Figure 11 The structural schematic diagram of the optimal embodiment of the lithium carbonate production system of the present utility model.

[0159] The relevant markings in the above-mentioned drawings are as follows:

[0160] 1111 - Condenser tube, 1112 - Cooling jacket, 112 - Buffer tank, 1121 - Liquid level gauge, 1122 - First valve, 113 - Absorption device, 1141 - Hydrogen fluoride detection device, 1142 - Return pipe, 1143 - Second valve, 1144 - Third valve, 115 - Neutralization reaction assembly, 116 - Solid-liquid separation assembly, 1210 - Roaster heating jacket, 1211 - First heat exchanger, 1212 - Second heat exchanger, 1213 - Third heat exchanger, 1221 - First dust collector, 1222 - Second dust collector, 123 - Arsenic recovery unit, 124 - Hydrogen fluoride recovery unit, 1251 - Lepidolite dry material buffer bin, 1252 - Lepidolite raw material bin, 126 - Drying kiln, 127 - Roaster hot blast stove, 128 - Roaster cooler, 129 - Lepidolite clinker storage tank, 131 - Filter, 132 - Acidification kiln heating jacket, 133 - Acidification kiln hot blast stove, 1341 - Acid storage tank, 1342 - Salt storage tank, 135 - Mixed acid machine, 136 - Deacidification device, 137 - Acidification kiln cooler, 138 - Lepidolite acidified material storage tank, 200 - Lepidolite raw material roasting system, 300 - Lepidolite clinker acidification system, 400 - Lepidolite acidified material pulp preparation system, 510 - Primary filtration assembly, 520 - Washing and filtration assembly, 521 - First pulp preparation tank, 522 - First filtration equipment, 523 - Second pulp preparation tank, 524 - Second filtration equipment, 600 - Intermediate tank, 700 - Impurity residue treatment system, 800 - Lithium leaching solution purification system, 900 - Lithium extraction system, 710 - Drying equipment, 720 - Roaster, 731 - First pulp preparation tank, 732 - First filtration equipment, 741 - Second pulp preparation tank, 742 - Second filtration equipment, 751 - Third pulp preparation tank, 752 - Third filtration equipment, 760 - Filter residue storage tank, 810 - First reaction tank, 811 - First lye dosing device, 812 - Hydrogen peroxide dosing device, 813 - First pH detector, 814 - First stirrer, 815 - First flocculant dosing device, 820 - First plate and frame filter press, 830 - Second reaction tank, 831 - Second lye dosing device, 832 - Carbonate dosing device, 833 - Second pH detector, 834 - Second stirrer, 835 - Second flocculant dosing device, 841 - Second plate and frame filter press, 842 - Precision filter, 843 - Plate and frame filter press, 850 - Resin adsorption device, 860 - Reaction tank, 861 - Lye dosing device, 862 - Seed crystal dosing device, 863 - pH detector, 864 - Stirrer, 865 - Flocculant dosing device. Detailed implementation manners

[0161] The following clearly and completely describes the present utility model with reference to the accompanying drawings. Those of ordinary skill in the art will be able to implement the present utility model based on these descriptions. Before describing the present utility model with reference to the accompanying drawings, it should be particularly noted that:

[0162] In the present utility model, the technical solutions and technical features provided in each part including the following description can be combined with each other without conflict.

[0163] In addition, the embodiments of the present utility model involved in the following description are usually only a part of the embodiments of the present utility model, rather than all embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative work shall fall within the protection scope of the present utility model.

[0164] Regarding the terms and units in the present utility model. The terms "comprising", "having" and any variations thereof in the specification, claims and relevant parts of the present utility model are intended to cover non-exclusive inclusion.

[0165] Figure 1 It is a schematic structural diagram of the first embodiment of the lithium mica raw material roasting system of the present utility model.

[0166] As Figure 1 shown, the lithium mica raw material roasting system includes a condensation component, a buffer component, an absorption component, a reflux component, a neutralization reaction component 115 and a solid-liquid separation component 116.

[0167] The condensation component is used for condensing the defluorinated flue gas and outputting a gas-liquid-solid mixture; the condensation component includes a condensation pipe 1111 connected to the flue gas outlet of the roasting kiln and a cooling jacket 1112; the condensation pipe 1111 is a pipe made of polytetrafluoroethylene, or the inner wall of the condensation pipe 1111 has a polytetrafluoroethylene coating, thereby avoiding softening or corrosion of the pipe caused by high-temperature hydrogen fluoride gas and water vapor.

[0168] The buffer component is used for temporarily storing the gas-liquid-solid mixture; the buffer component includes a buffer tank 112 connected to the condensation pipe 1111; thereby, on the one hand, preventing the lye in the absorption component from being sucked back into the roasting kiln due to the decrease in pressure in the roasting kiln, and on the other hand, enabling part of the slag entering the buffer component along with the defluorinated flue gas to settle in the buffer tank 112. A liquid level gauge 1121 is provided on the buffer tank 112, and a first valve 1122 interlocked with the liquid level gauge 1121 is provided on the connecting pipe between the buffer tank 112 and the neutralization reaction component 115. The condensation pipe 1111 is inclined, and the connection part of the condensation pipe 1111 with the flue gas outlet of the roasting kiln is higher than the connection part of the condensation pipe 1111 with the buffer tank 112, thereby enabling the defluorinated flue gas to enter the buffer tank 112 by using the gas pressure and height difference after cooling in the cooling jacket 1112.

[0169] The absorption assembly is used to absorb the non-condensable substances in the buffer tank 112, mainly including uncondensed hydrogen fluoride gas, water vapor and a small amount of dust; the absorption assembly includes an absorption device 113 connected to the non-condensable substances in the buffer tank 112; the absorption assembly includes at least two absorption devices 113 arranged in series to achieve the purpose of completely absorbing hydrogen fluoride. The absorption device 113 uses an alkaline absorbent, which can be but is not limited to any several of sodium hydroxide solution, calcium hydroxide solution, potassium hydroxide solution. The absorption device 113 can be but is not limited to a spray tower.

[0170] The reflux assembly is used to reflux the tail gas to the buffer tank 112 when the hydrogen fluoride in the tail gas discharged from the absorption assembly exceeds the preset value, thereby further maintaining the pressure stability of the system. The reflux assembly includes a hydrogen fluoride detection device 1141 provided at the tail gas outlet of the absorption device 113 and a reflux pipe 1142 connecting the buffer tank 112 and the downstream pipeline of the hydrogen fluoride detection device 1141; a second valve 1143 and a third valve 1144 interlocked with the hydrogen fluoride detection device 1141 are respectively provided on the downstream pipeline and the reflux pipe 1142.

[0171] The neutralization reaction assembly 115 is used to react the condensate in the buffer tank 112 with the alkali solution. The neutralization reaction assembly 115 includes a neutralization reaction tank, and the alkaline absorbent in the neutralization reaction tank can be but is not limited to any several of sodium hydroxide solution, calcium hydroxide solution, potassium hydroxide solution.

[0172] The solid-liquid separation assembly 116 is a solid-liquid separation assembly 116 used to perform solid-liquid separation on the solid-liquid mixture output from the neutralization reaction tank and the absorption assembly. The solid-liquid separation assembly 116 is a filtering device or a centrifugal device.

[0173] In addition to the condenser tube 1111, the equipment and pipelines through which the material containing hydrogen fluoride flows are also preferably made of polytetrafluoroethylene or have a polytetrafluoroethylene coating on the inner wall.

[0174] Figure 2 It is a schematic structural diagram of the second embodiment of the lithium mica raw material roasting system of the present invention.

[0175] Compared with the first embodiment, the difference of the lithium mica raw material roasting system in this embodiment is that: as Figure 2 shown, the neutralization reaction assembly 115 is not provided. Among them, water is used as the absorbent in the absorption device 113. The solid-liquid separation assembly 116 is used to perform solid-liquid separation on the solid-liquid mixture output from the buffer tank 112 and the absorption assembly. A first valve 1122 interlocked with the liquid level gauge 1121 is provided on the connecting pipe between the buffer tank 112 and the solid-liquid separation assembly 116. Thus, the obtained clear liquid is enriched with more hydrogen fluoride and can be used for the recycling of hydrogen fluoride.

[0176] The first embodiment and the second embodiment of the roasting system for lepidolite raw materials of the present utility model fully consider the characteristics of the defluorination flue gas. Through multi-stage treatments such as condensation, buffering, and absorption, the emissions of pollutants are effectively reduced, and at the same time, the recycling efficiency of resources is improved, which has positive significance for enhancing the environmental protection and economy of the entire technological process. Compared with the system design in the prior art that directly uses the defluorination flue gas to produce hydrogen fluoride, the structures of the first embodiment and the second embodiment of the roasting system for lepidolite raw materials of the present utility model are simpler, with lower input costs, and different implementation modes can be selected according to the hydrogen fluoride content, having stronger practicability. The object of action of the treatment system of the above embodiments of the present utility model has universality, and it can be either the defluorination flue gas generated by an internal heating roasting kiln (i.e., directly introducing natural gas into the roasting kiln) or the defluorination flue gas generated by an external heating roasting kiln (using jacket heating or electric heating).

[0177] Figure 3 It is a schematic structural diagram of the third embodiment of the roasting system for lepidolite raw materials of the present utility model.

[0178] As Figure 3 shown, the lepidolite raw material roasting system includes a roasting kiln for roasting lepidolite raw materials, a roasting kiln heating jacket 1210, a first heat exchanger 1211, a second heat exchanger 1212, a third heat exchanger 1213, a first dust collector 1221, an arsenic recovery unit 123, a hydrogen fluoride recovery unit 124, a lepidolite dry material buffer bin 1251, a lepidolite raw material bin 1252, a drying kiln 126, a second dust collector 1222, a roasting kiln hot blast stove 127, a roasting kiln cooler 128, and a lepidolite clinker storage tank 129.

[0179] The roasting kiln heating jacket 1210 is used to heat the roasting kiln.

[0180] The first heat exchanger 1211 is used to conduct heat exchange between the lepidolite dry material to be fed into the roasting kiln and the first defluorination flue gas output from the roasting kiln; the first heat exchanger 1211 is a cyclone preheater. The particulate matter intercepted by the first dust collector 1221 flows into the lepidolite dry material buffer bin 1251, and the lepidolite dry material buffer bin 1251 outputs lepidolite dry material to conduct heat exchange with the first defluorination flue gas output from the roasting kiln in the first heat exchanger 1211.

[0181] The second heat exchanger 1212 is used to conduct heat exchange between the second defluorination flue gas output from the first heat exchanger 1211 and the defluorinating agent to be fed into the roasting kiln.

[0182] The third heat exchanger 1213 is used to exchange heat between the primary cold air output from the roasting kiln heating jacket 1210 and the cold air. The roasting kiln hot blast stove 127 is used to heat the energy gas and output the gas for heating the jacket of the roasting kiln to the roasting kiln heating jacket 1210. The secondary cold air obtained after the third heat exchanger 1213 processes the primary cold air flows into the roasting kiln hot blast stove 127 as the energy gas (except for the recycled secondary cold air, the main component is natural gas).

[0183] The first dust collector 1221, the arsenic recovery unit 123, and the hydrogen fluoride recovery unit 124 sequentially process the third de-fluorinated flue gas output from the second heat exchanger 1212. Among them, the first dust collector 1221 can not only recover the lepidolite dust but also improve the purity of the arsenic oxide and hydrogen fluoride recovered subsequently. The arsenic recovery unit 123 preferably but not limited to adopts the condensation method to recover arsenic oxide. The hydrogen fluoride recovery unit 124 preferably but not limited to adopts the condensation and / or absorption method to recover hydrogen fluoride.

[0184] The lepidolite raw material bin 1252 is used to store the lepidolite raw material. The drying kiln 126 is used to dry the lepidolite raw material. The hot air obtained after the third heat exchanger 1213 processes the cold air flows into the drying kiln 126 as the heat source. The dried lepidolite dry material after passing through the drying kiln 126 flows into the lepidolite buffer bin. The second dust collector 1222 is used to remove dust from the lepidolite dust gas output from the drying kiln 126. The particulate matter intercepted by the second dust collector 1222 flows into the lepidolite raw material bin 1252.

[0185] The roasting kiln cooler 128 is used to cool the lepidolite clinker output from the roasting kiln. The lepidolite clinker storage tank 129 is used to store the cooled lepidolite clinker.

[0186] Thus, the lepidolite raw material roasting system of the third embodiment of the present utility model has the following advantages:

[0187] 1. An enclosed roasting kiln is adopted, and the lepidolite raw material is indirectly heated in the roasting kiln without directly contacting the flame or flue gas. Therefore, it can not only reduce the safety risks such as fire and explosion, but also reduce the pollution of the lepidolite raw material, and at the same time reduce the emission of harmful substances in the de-fluorinated flue gas, which is more in line with the environmental protection requirements.

[0188] 2. The jacket structure makes the heat distribution in the roasting kiln more uniform. On the one hand, it enables the lepidolite raw materials to be heated evenly, reduces the thermal stress of the lepidolite raw materials during the heating process, and lowers the risk of explosion of the lepidolite raw materials. On the other hand, it reduces the high-temperature area inside the roasting kiln and reduces the safety risk for the operators. By controlling the heating temperature and heating rate of the heating jacket 1210 of the roasting kiln, precise temperature control can be achieved, and it is easier to control the temperature and reaction rate inside the roasting kiln. Therefore, the roasting process can be better controlled, which helps to reduce the consumption of defluorinating agents, achieve efficient defluorination, improve the quality and stability of the lepidolite clinker, and has more extensive uses and flexibility. It can reduce the temperature difference stress inside the roasting kiln, reduce the damage of thermal shock and thermal fatigue to the roasting kiln, and thus extend the service life of the roasting kiln. The jacket structure can reduce the heat dissipation to the external environment, help to reduce energy consumption, and improve energy utilization efficiency.

[0189] 3. The primary cold air output from the heating jacket 1210 of the roasting kiln preheats the cold air entering the hot blast stove 127 of the roasting kiln and is used as the heat source for the drying kiln 126 for drying the lepidolite raw materials, realizing the recovery and utilization of waste heat.

[0190] 4. The high-temperature first defluorination flue gas preheats the defluorinating agent to be fed into the kiln, increases the temperature of the defluorinating agent entering the kiln, reduces the heat demand of the roasting kiln, and realizes energy conservation and consumption reduction.

[0191] 5. Only the defluorinating agent is introduced into the roasting kiln, and there is no introduction of natural gas combustion flue gas, making the defluorination tail gas have a single composition, which is beneficial to the recovery and utilization of arsenic oxides and hydrogen fluoride, and reduces the land occupation and investment of the tail gas treatment device.

[0192] Figure 4 This is a schematic structural diagram of the first embodiment of the lepidolite clinker acidification system of the present utility model.

[0193] As Figure 4 shown, the lepidolite clinker acidification system includes an acidification kiln for acidifying the lepidolite clinker, a filter 131, an acidification kiln heating jacket 132, an acidification kiln hot blast stove 133, an acid storage tank 1341, a lepidolite clinker storage tank 129, a mixed acid machine 135, a deacidification device 136, an acidification kiln cooler 137, and a lepidolite acidified material storage tank 138. The lepidolite clinker is obtained by roasting lepidolite raw materials.

[0194] The acidification kiln heating jacket 132 is used to heat the acidification kiln.

[0195] The acidification kiln hot blast stove 133 is used to input the jacket gas for heating the acidification kiln into the acidification kiln heating jacket 132. Part of the cold air output from the acidification kiln heating jacket 132 flows into the acidification kiln hot blast stove 133 as energy gas (mainly composed of natural gas), and part is directly discharged.

[0196] The mixed acid machine 135 is used to mix the spodumene clinker and acid.

[0197] The filter 131 is used to filter the acidified flue gas output from the acidification kiln and output dust and low-dust gas. Among them, the dust output by the filter 131 flows into the mixed acid machine 135.

[0198] The deacidification device 136 is used to perform deacidification treatment on the low-dust gas output by the filter 131, and the deacidification device 136 is a spray tower.

[0199] The acidification kiln cooler 137 is used to cool the spodumene acidified material output from the acidification kiln, and the spodumene acidified material storage tank 138 is used to store the cooled spodumene acidified material.

[0200] Figure 5 It is a schematic structural diagram of the second embodiment of the spodumene clinker acidification system of the present invention.

[0201] Compared with the first embodiment, the difference of the spodumene clinker acidification system in this embodiment is that: as Figure 5 shown, it further includes a salt storage tank 1342, and the mixed acid machine 135 is used to mix the spodumene clinker, acid and salt. The acid storage tank 1341 preferably stores sulfuric acid, and the salt storage tank 1342 preferably stores any several of potassium sulfate, sodium sulfate, and calcium sulfate. Thus, by acidifying the spodumene clinker with sulfuric acid and sulfates at the same time, the acid aging time can be saved, the sulfuric acid consumption can be significantly reduced, and the lithium leaching rate can be improved.

[0202] It can be seen that the spodumene clinker acidification system of the above embodiment of the present invention has the following advantages:

[0203] 1. An enclosed acidification kiln is adopted, and the spodumene clinker is indirectly heated in the acidification kiln without directly contacting the flame or flue gas. Therefore, both the safety risks such as fire and explosion can be reduced, the pollution of the spodumene clinker can be reduced, and at the same time, the emission of harmful substances in the acidified flue gas can be reduced, which is more in line with environmental protection requirements.

[0204] 2. The jacket structure makes the heat distribution in the acidification kiln more uniform. On the one hand, it enables the spodumene clinker to be heated evenly, reduces the thermal stress of the spodumene clinker during the heating process, and lowers the risk of explosion of the spodumene clinker. On the other hand, it reduces the high-temperature area inside the acidification kiln and reduces the safety risk of operators. By controlling the heating temperature and heating rate of the heating jacket 132 of the acidification kiln, precise temperature control can be achieved, and it is easier to control the temperature and reaction rate inside the acidification kiln. Therefore, the roasting process can be better controlled, the quality and stability of the acidified spodumene material can be improved, and then the lithium leaching rate can be increased, with more extensive uses and flexibility. It can reduce the temperature difference stress inside the acidification kiln, reduce the damage of thermal shock and thermal fatigue to the acidification kiln, and thus extend the service life of the acidification kiln. The jacket structure can reduce the heat dissipation to the external environment, contribute to reducing energy consumption, and improve energy utilization efficiency.

[0205] 3. The introduction of natural gas combustion flue gas into the acidification kiln is avoided, making the volume of the acidification flue gas small and the composition single, reducing the land occupation and investment of the tail gas treatment device.

[0206] 4. The cold air output by the heating jacket 132 of the acidification kiln circulates back to the hot blast stove 133 of the acidification kiln, enabling full utilization of heat energy and low energy consumption.

[0207] The first embodiment of the method for pretreating spodumene raw materials of the present utility model is for leaching lithium elements in spodumene raw materials, including the steps of:

[0208] Roasting the spodumene raw materials at 800 - 1000 °C for 0.5 - 1.5 h to obtain spodumene clinker;

[0209] Roasting the mixture of spodumene clinker, salt and acid at 200 - 320 °C for 0.5 - 1.5 h to obtain acidified spodumene material;

[0210] Adding water to the acidified spodumene material to form a slurry to obtain a slurry;

[0211] Performing solid-liquid separation on the slurry to obtain a leaching solution and leaching residue.

[0212] In the roasting process of the traditional method for preparing lithium carbonate from lepidolite by the salt method, the lepidolite raw material is mixed with salt and then roasted at high temperature. The cations in the salt can displace the lithium in the lepidolite raw material, enabling the lithium to combine with the acid radical ions to form soluble lithium salts. Then, water is directly added to adjust the slurry and filtered to obtain the leaching solution. However, if a high lithium leaching rate is to be achieved by this method, the amount of salt used needs to be increased. The large amount of salt used results in a significant increase in the amount of slag, which in turn leads to an increase in the amount of water for slurry adjustment and further increases the treatment pressure of the leaching solution and leaching residue after filtration. Similarly, in the acidification roasting process of preparing lithium carbonate from lepidolite by the acid method, since other elements are leached by acid simultaneously with lithium, the amount of acid added will far exceed the amount of acid required for theoretically leaching lithium. The large amount of acid used increases the production cost, is not environmentally friendly, and increases the treatment pressure of the subsequent acidic liquid.

[0213] The pretreatment method of the lepidolite raw material in the above embodiment of the present invention first realizes defluorination and crystal transformation through high-temperature roasting, which helps the leaching of lithium. Then, through the synergistic effect of salt and acid, not only the lithium leaching rate is increased, but also the amount of leaching agents (i.e., acid and salt) used is effectively reduced compared with the traditional salt method and acid method, and the amount of water for slurry adjustment and the amount of acidic liquid are less, thereby reducing the raw material cost and subsequent treatment cost. It has been verified that the pretreatment method of the lepidolite raw material in the above embodiment of the present invention can ensure a lithium leaching rate of more than 75%, and the amount of acid used can be reduced by more than 30% compared with the traditional method.

[0214] The second embodiment of the pretreatment method of the lepidolite raw material of the present invention is for leaching the lithium element in the lepidolite raw material, and includes the steps:

[0215] Roast the lepidolite raw material at 800 - 1000 °C for 0.5 - 1.5 h to obtain lepidolite clinker;

[0216] First, roast the mixture of lepidolite clinker and salt at 800 - 900 °C for 0.5 - 1.5 h, then cool down to 200 - 320 °C and add acid and continue to keep warm for 0.5 - 1.5 h to obtain acidified lepidolite;

[0217] Add water to the acidified lepidolite to form a slurry to obtain a slurry;

[0218] Perform solid-liquid separation on the slurry to obtain a leaching solution and leaching residue.

[0219] Compared with the first embodiment, the second embodiment of the pretreatment method of the lepidolite raw material uses salt and acid separately. First, the salt and lepidolite clinker are fully reacted at a higher temperature, and then acid solution is injected for secondary leaching when the kiln temperature automatically drops to a lower temperature, finally realizing the deep leaching of lithium.

[0220] The third embodiment of the pretreatment method for lithium mica raw materials of the present utility model is for leaching lithium elements in lithium mica raw materials, including the steps:

[0221] Roast the lithium mica raw materials at 800 - 1000 °C for 0.5 - 1.5 h to obtain roasted lithium mica clinker;

[0222] Mix the roasted lithium mica clinker and salt by ball milling, then add acid, and roast the mixture of roasted lithium mica clinker, salt and acid at 200 - 320 °C for 0.5 - 1.5 h to obtain acidified lithium mica material;

[0223] Add water to the acidified lithium mica material to form a slurry, and then carry out high-speed stirring at 800 - 2000 revolutions per minute for 50 minutes to obtain a slurry;

[0224] After solid-liquid separation of the slurry, leachate and leached residue are obtained.

[0225] Compared with the first embodiment, in the third embodiment of the pretreatment method for lithium mica raw materials, first, the roasted lithium mica clinker and salt are fully mixed by ball milling, which helps the salt to leach lithium in the roasted lithium mica clinker at low temperature and reduces the heat consumption of the acidification kiln. Secondly, by carrying out high-speed stirring on the slurry after adjusting the slurry with water, high-speed stirring can provide greater kinetic energy, which is not only beneficial to the rapid dissolution of soluble lithium, but also makes the collision between particles of the acidified lithium mica material more intense and frequent, and also plays a role in grinding the acidified lithium mica material to a certain extent, reducing the particle size of the acidified lithium mica material and increasing the dissolution rate.

[0226] In the three embodiments of the above-mentioned pretreatment method for lithium mica raw materials, the acid and salt preferably have the same acid radical ions to avoid introducing too many impurity ions. Preferably, the acid is sulfuric acid, and the salt is any of potassium sulfate, sodium sulfate, and calcium sulfate. When the mass ratio of the sulfate to the roasted lithium mica clinker is (0.03 - 0.15):1, and the mass ratio of sulfuric acid (using concentrated sulfuric acid with a mass fraction of 98%) to the roasted lithium mica clinker is (0.2 - 0.45):1, the best lithium leaching rate can be obtained.

[0227] In the three embodiments of the above-mentioned pretreatment method for lithium mica raw materials, the roasting treatment of the lithium mica raw materials is preferably carried out using Figures 1 - 3 any of the lithium mica raw material roasting systems 200 shown in Figure 4 or Figure 5 shown in the lithium mica clinker acidification system 300.

[0228] Figure 6 It is a schematic structural diagram of an embodiment of the pretreatment system for lithium mica raw materials of the present utility model.

[0229] As shown in Figure 6As shown, the lepidolite raw material pretreatment system includes a lepidolite raw material roasting system 200, a lepidolite clinker acidification system 300, and a lepidolite acidified material slurry preparation system 400.

[0230] The lepidolite raw material roasting system 200 is used to roast the lepidolite raw material and output lepidolite clinker; the lepidolite raw material roasting system 200 is preferably Figures 1 - 3 the lepidolite raw material roasting system 200 shown in any one of

[0231] The lepidolite clinker acidification system 300 is used to acidify the lepidolite clinker and output lepidolite acidified material; the lepidolite clinker acidification system 300 is preferably Figure 4 or Figure 5 the lepidolite clinker acidification system 300 shown in

[0232] The lepidolite acidified material slurry preparation system 400 is used to add water to the lepidolite acidified material to prepare a slurry and output a lithium leaching solution; the lepidolite acidified material slurry preparation system 400 includes a high-speed dispersion device for performing high-speed dispersion treatment on the lithium leaching solution; the high-speed dispersion device refers to a stirring device with a stirring speed reaching above 800 revolutions per minute, and any one of a double-shaft high-speed disperser, a concentric double-shaft high-low speed disperser, a disc-type double-shaft stirring disperser, and a disc-type three-shaft stirring disperser can be used but is not limited to these.

[0233] The lepidolite raw material pretreatment system of the above embodiment of the present invention no longer uses the traditional low-speed anchor stirring (which requires stirring for 3 to 5 hours), but uses a high-speed dispersion device to perform high-speed stirring on the slurry after adding water to prepare a slurry. High-speed stirring can provide greater kinetic energy, which is not only beneficial to the rapid dissolution of soluble lithium, but also can make the collisions between lepidolite acidified material particles more intense and frequent. To a certain extent, it also plays a role in grinding the lepidolite acidified material, reducing the particle size of the lepidolite acidified material and increasing the dissolution rate. It has been verified that the lepidolite raw material pretreatment system of the above embodiment of the present invention can not only reduce the leaching and stirring time to less than 60 minutes, but also no longer perform fine grinding on the lepidolite raw material or lepidolite clinker. It can be directly acidified when the particle size is about 100 to 200 mesh, reducing the leaching time and greatly increasing the leaching efficiency.

[0234] Figure 7 It is a schematic structural diagram of an embodiment of the lepidolite acidified material leaching system of the present invention.

[0235] As Figure 7 shown, the lepidolite acidified material leaching system includes a lepidolite acidified material slurry preparation system 400, a primary filtration assembly 510, and a washing and filtration assembly 520 connected in sequence.

[0236] The lithium mica acidified material slurry mixing system 400 is used to mix the lithium mica acidified material with water to form a slurry and output a turbid lithium leaching solution. The lithium mica acidified material slurry mixing system 400 includes a lithium mica acidified material slurry mixing tank and / or a high-speed dispersion device for performing high-speed dispersion treatment on the turbid lithium leaching solution.

[0237] The primary filtration assembly 510 is used to filter the turbid lithium leaching solution and output a clear lithium leaching solution and leaching residue. The primary filtration assembly 510 includes a primary plate and frame filter press.

[0238] The washing and filtration assembly 520 is used to wash the leaching residue and output a lithium washing solution and washed lithium residue. The lithium washing solution is used as the lithium leaching solution. The washing and filtration assembly 520 includes a first-stage slurry mixing tank 521, a first-stage filtration device 522, a second-stage slurry mixing tank 523, and a second-stage filtration device 524. The first-stage slurry mixing tank 521 is used to mix the leaching residue with water to form a first-stage slurry. The first-stage filtration device 522 is used to filter the first-stage slurry and output a first-stage filter residue and a first-stage filtrate. The second-stage slurry mixing tank 523 is used to mix the first-stage filter residue with water to form a second-stage slurry. The second-stage filtration device 524 is used to filter the second-stage slurry and output a second-stage filter residue and a second-stage filtrate. The first-stage filtrate and the second-stage filtrate flow into an intermediate tank 600 and are combined with the clear lithium leaching solution and then used as the lithium leaching solution.

[0239] The lithium mica acidified material leaching system of the above embodiments of the present invention directly performs filtration and washing under acidic conditions after adding water to form a slurry, and has the following advantages: First, the leaching residue does not contain colloidal substances, and solid-liquid separation can be efficiently performed, minimizing the water content of the leaching residue. The reduction of the water content of the leaching residue means that the lithium salt carried away by the leaching residue is reduced, which not only reduces lithium loss, but also the leaching residue only needs to be washed 1 to 2 times to wash out the lithium salt entrained in the leaching residue, reducing the number of washing times compared to the traditional process and reducing water consumption and energy consumption. Second, since there are no colloidal substances, the liquid phase is more likely to pass through the filter pores, the filtration effect is better, and the filter medium is cleaner after the cake is unloaded, and the cleaning frequency is lower, which is beneficial to improving the filtration effect and stability of the primary filtration assembly 510. It has been verified that the lithium mica acidified material leaching system of the above embodiments of the present invention can increase the lithium recovery rate by at least 3% compared to the lithium recovery rate of the traditional process, and the number of washing times of the leaching residue can be reduced by at least 2 times.

[0240] An embodiment of the method for treating impurity removal residue in the production of lithium carbonate of the present invention is to recover the impurity removal residue. The impurity removal residue can be obtained by adding water to the lithium mica acidified material for slurry mixing - purification, or can be obtained by adding water to the lithium mica acidified material for slurry mixing - filtration - purification. The purification process is preferably the Figure 9 or Figure 10 shown lithium leaching solution purification method and purification system; the method for treating impurity removal residue includes the following steps:

[0241] (1) Roast the impurity-removed slag to obtain a roasted material; the roasting temperature is 200-400 °C, and the roasting time is 20-80 minutes; dry the impurity-removed slag before roasting.

[0242] (2) Slurry the roasted material with water and then filter to obtain a first filter residue and a first filtrate.

[0243] (3) Slurry the first filter residue with water and then filter to obtain a second filter residue and a second filtrate.

[0244] (4) Slurry the second filter residue with water and then filter to obtain a third filter residue and a third filtrate; the first filtrate, the second filtrate, and the third filtrate are combined as the filtrate and used as the lithium leaching solution.

[0245] Among them, in steps (2)-(4), the liquid-solid ratio in the water slurry is (1-3):1, and after stirring at 30-80 °C for 20-60 minutes, filtration is carried out. In this way, the water consumption is small and the washing effect is good.

[0246] Figure 8 It is a schematic structural diagram of an embodiment of the impurity-removed slag treatment system in the production of lithium carbonate of the present utility model.

[0247] As Figure 8 shown, the treatment system adopted in the embodiment of the above-mentioned impurity-removed slag treatment method includes a drying device 710, a roasting furnace 720, a first slurry tank 731, a first filtering device 732, a second slurry tank 741, a second filtering device 742, a third slurry tank 751, and a third filtering device 752. The drying device 710 dries the impurity-removed slag. The roasting furnace 720 is used to roast the impurity-removed slag and output the roasted material; the roasting furnace 720 is an external heat type roasting furnace 720, such as electric heating or jacket heating. The first slurry tank 731 is used to slurry the roasted material with water and output a first slurry; the first filtering device 732 is used to filter the first slurry and output a first filter residue and a first filtrate. The second slurry tank 741 is used to slurry the first filter residue with water and output a second slurry; the second filtering device 742 is used to filter the second slurry and output a second filter residue and a second filtrate. The third slurry tank 751 is used to slurry the second filter residue with water and output a third slurry; the third filtering device 752 is used to filter the third slurry and output a third filter residue and a third filtrate. The first filtrate, the second filtrate, and the third filtrate flow into an intermediate tank 600 and are used as the lithium leaching solution. The third filter residue is stored in a filter residue storage tank 760.

[0248] In the traditional process, only about 30% of lithium is washed out of the impurity slag in the background technology after washing, and the lithium loss is relatively high. In comparison, the impurity slag treatment method and impurity slag treatment system 700 of the above embodiment of the utility model have the advantages of: aluminum hydroxide is converted into aluminum oxide by roasting. Aluminum oxide is non-colloidal in nature and has poor adsorption to lithium salts, so that the adsorbed lithium salts are easily washed out by water, and at least 60% of lithium can be washed out, and the lithium recovery rate can be greatly improved. The obtained lithium washing solution can be directly sent to the lithium extraction system 900, or can be sent to the lithium leaching solution purification system 800. The main components of the modified impurity removal slag (i.e., the third filter residue) are mainly aluminum oxide and iron oxide. In particular, when the impurity removal slag is obtained by slurrying, filtering, and purification of lithium mica acidified material with water (i.e., the lithium leaching solution outputted from the above-mentioned lithium mica acidified material leaching system is obtained after purification), the slag content in the modified impurity removal slag is small and mainly composed of metal oxides. Therefore, it is convenient for subsequent use, for example, it is used as a seed in the second embodiment of the lithium leaching solution purification method and purification system below, thereby realizing the deep recycling of impurity removal slag resources.

[0249] The first embodiment of the lithium leaching solution purification method of the utility model is to purify the lithium leaching solution. The lithium leaching solution can be obtained by adding water to the lepidolite acidified material to make a slurry, or by adding water to the lepidolite acidified material to make a slurry-filtered material. The most preferred one is from the above-mentioned intermediate tank 600 (i.e. Figure 7 The lithium leachate outputted from the lithium mica acidification material leaching system is shown in FIG. 1 ); the lithium leachate purification method comprises the following steps:

[0250] (1) adding hydrogen peroxide to the lithium leaching solution to obtain an oxidation solution; the amount of hydrogen peroxide used is 2+ The mass of hydrogen peroxide is 1.1 to 1.4 times, and the mass fraction of hydrogen peroxide is prepared into a solution with a mass fraction of 22% to 30%. After reacting for 10 to 30 minutes, an oxidizing solution is obtained.

[0251] (2) adding an alkali solution to the oxidizing solution until the pH value is 6 to 8 to obtain a first solid-liquid mixture; the alkali solution is potassium hydroxide and / or sodium hydroxide, and after the pH value is adjusted to 6 to 8, reacting at 40 to 60° C. for 10 to 30 minutes to obtain the first solid-liquid mixture.

[0252] (3) filtering the first solid-liquid mixture to obtain a first impurity-removed residue and a filtrate.

[0253] (4) adding alkali solution to the filtrate until the pH value is 10 to 12, and then adding soluble carbonate to obtain a second solid-liquid mixture; the alkali solution is potassium hydroxide and / or sodium hydroxide; the carbonate is potassium carbonate and / or sodium carbonate; wherein, in order to avoid lithium loss caused by lithium element conversion to lithium carbonate precipitation as much as possible, the temperature is 40 to 60° C., and the amount of carbonate used is calculated as the amount of Ca in the filtrate based on carbonate ions. 2+1.05 to 1.1 times the molar amount; after adding soluble carbonate and reacting for another 10 to 30 minutes, a second solid-liquid mixture is obtained.

[0254] (5) Filter the second solid-liquid mixture to obtain a second impurity removal residue and a purified liquid.

[0255] (6) Perform resin adsorption treatment on the purified liquid. Before adsorption, first expand the resin with water, then wash the resin with a hydrochloric acid solution with a mass fraction of 4 to 5% to remove inorganic impurities, and finally wash the resin to neutral with a potassium hydroxide and / or sodium hydroxide solution with a mass fraction of 2 to 4% to remove organic impurities.

[0256] Preferably, flocculants are also used in steps (2) and (4), which can improve the reaction efficiency and facilitate filtration.

[0257] Figure 9 It is a schematic structural diagram of the first embodiment of the lithium leaching solution purification system of the present invention.

[0258] As Figure 9 shown, the lithium leaching solution purification system 800 adopted in the first embodiment of the above lithium leaching solution purification method includes a first reaction component, a first filtration component, a second reaction component, a second filtration component, and a resin adsorption device 850.

[0259] The first reaction component is used to react the lithium leaching solution, hydrogen peroxide, and alkali solution to generate a first solid-liquid mixture; the first reaction component includes a first reaction tank 810, a hydrogen peroxide dosing device 812 for adding hydrogen peroxide to the first reaction tank 810, a first alkali dosing device 811 for adding alkali solution to the first reaction tank 810, a first pH detector 813 for detecting the pH of the material in the first reaction tank 810, a first stirrer 814 for stirring the material in the first reaction tank 810, and a first flocculant dosing device 815 for adding flocculant to the first reaction tank 810.

[0260] The first filtration component is used to filter the first solid-liquid mixture and output a first impurity removal residue and a impurity removal liquid; the first filtration component includes a first plate and frame filter press 820.

[0261] The second reaction component is used to react the filtrate, alkali solution, and carbonate to generate a second solid-liquid mixture; the second reaction component includes a second reaction tank 830, a second alkali dosing device 831 for adding alkali solution to the second reaction tank 830, a carbonate dosing device 832 for adding carbonate to the second reaction tank 830, a second pH detector 833 for detecting the pH of the material in the second reaction tank 830, a second stirrer 834 for stirring the material in the second reaction tank 830, and a second flocculant dosing device 835 for adding flocculant to the second reaction tank 830.

[0262] The second filtering component is used to filter the second solid-liquid mixture and output the second impurity-removed residue and purified liquid; the second filtering component includes a second plate-frame filter press 841 and a precision filter 842 connected in sequence.

[0263] The resin adsorption device 850 is used to perform resin adsorption treatment on the purification liquid.

[0264] The first embodiment of the lithium leachate purification method and lithium leachate purification system 800 of the utility model has the following advantages:

[0265] 1. First, by using hydrogen peroxide, divalent iron ions can be oxidized to trivalent iron ions, and finally converted into iron hydroxide precipitation, so that iron impurities are deeply removed. Secondly, first neutralize to a pH of 6-8 to remove most impurities such as Fe and Al, and then adjust to a pH of 10-12 to allow impurities such as Ca, Mg, and Mn to react with hydroxide and precipitate, and then use potassium carbonate and / or sodium carbonate to deeply remove impurity ions that are not precipitated in the form of carbonates. Finally, adding resin adsorption can further improve the recovery rate of lithium.

[0266] The above-mentioned step-by-step operation is conducive to selective precipitation of impurities and reducing lithium loss. In addition, the combination of hydroxide and carbonate not only reduces the cost of reagents, but also allows for thorough removal of impurities. The Al, Fe, Ca, Mg, Mn, Ni, Cu, and Zn in the resulting purified solution meet the electrical grade standards. By controlling the carbonate dosage and reaction temperature, most impurities can be precipitated while avoiding lithium co-precipitation as much as possible, which is conducive to improving the reaction rate and selectivity.

[0267] 2. Lepidolite itself has a lot of potassium. Using potassium hydroxide and / or sodium hydroxide instead of traditional calcium oxide or calcium hydroxide can reduce the introduction of impurity ions, and the generated byproduct K2SO4 or Na2SO4 (acidification with sulfuric acid) has good solubility, which not only reduces the amount of precipitation (calcium sulfate precipitation generated when there is no sulfuric acid method), but also can be further purified by evaporation and crystallization before lithium extraction to prepare high-purity K2SO4 or Na2SO4 products, thereby realizing the resource utilization of high-potassium lepidolite raw materials. The traditional process will introduce too much calcium ions, and the excess calcium ions need to be removed by adding carbonate, which increases the amount of carbonate, prolongs the process, and increases the cost of reagents.

[0268] The second embodiment of the lithium leaching solution purification method of the utility model is to purify the lithium leaching solution, and the lithium leaching solution can be obtained by adding water to the lithium mica acidified material to make a slurry, or by adding water to the lithium mica acidified material to make a slurry-filtered material, and the most preferred one is from the above-mentioned intermediate tank 600 (i.e. Figure 7(The lithium leaching solution output by the shown lepidolite acidified material leaching system); The method for purifying the lithium leaching solution includes the following steps:

[0269] (1) Add alkali solution to the lithium leaching solution until the pH is 2 - 3; The alkali solution is potassium hydroxide and / or sodium hydroxide; It is carried out at a rotation speed of 200 - 400 revolutions per minute.

[0270] (2) Continue to add seed crystals to the lithium leaching solution. The seed crystals include any several of Al2O3, Fe2O3, Fe(OH)3, and Al(OH)3; The mass of the seed crystals added per 1 L of the lithium leaching solution is 0.05% - 0.5% of the liquid volume.

[0271] (3) Continue to add alkali solution to the lithium leaching solution until the pH is 6 - 8 to obtain a solid-liquid mixture.

[0272] (4) Filter the solid-liquid mixture to obtain impurity removal slag and purified liquid.

[0273] (5) Carry out resin adsorption treatment on the purified liquid. Before adsorption, first expand the resin with water, then wash the resin with a hydrochloric acid solution with a mass fraction of 4 - 5% to remove inorganic impurities, and finally wash the resin to neutral with a potassium hydroxide and / or sodium hydroxide solution with a mass fraction of 2 - 4% to remove organic impurities.

[0274] Among them, the seed crystals can be purchased externally or prepared by using intermediate products in lithium carbonate production.

[0275] When the seed crystals include Fe(OH)3 and Al(OH)3, they can be prepared by the following preparation method: Add alkali solution to the lithium leaching solution until the pH is 6 - 8, and collect the generated precipitation slag, which is the seed crystals.

[0276] In the above-mentioned lithium leaching solution purification method and seed crystal preparation method, it is preferably to control the pH and stirring speed as follows: When pH ≤ 3, the stirring rate is 200 - 400 revolutions per minute; when pH > 3, the stirring rate ≤ 100 revolutions per minute; After pH adjustment, react for 20 - 40 minutes for liquid-solid separation. The reason for such control is: When pH < 3, Fe 3+ and Al 3+ are in a dissolved state. At this time, a higher stirring rate (200 - 400 revolutions per minute) is required to enhance the reaction kinetics effect and accelerate the reaction between metal ions in the solution and OH -The contact promotes the precipitation reaction. When pH ≥ 3, a large amount of Fe(OH)3 and Al(OH)3 start to precipitate. At this time, a relatively low stirring rate (≤ 100 revolutions per minute) is required to reduce the mechanical breakage of the precipitate particles and avoid the generation of too small colloidal particles. Because larger particles are easier to precipitate and filter, which is beneficial to improving the efficiency of subsequent solid-liquid separation and can also reduce the adsorption of lithium ions in the solution, thereby reducing the co-precipitation loss of lithium. In summary, by jointly controlling the pH and stirring rate, the precipitation kinetics and crystal growth behavior of Fe(OH)3 and Al(OH)3 can be regulated to obtain a precipitate product with larger particles, which is of great significance for subsequent solid-liquid separation and lithium recovery.

[0277] When the seed crystal includes Al2O3 and Fe2O3, it can either adopt the above-mentioned impurity removal slag treatment method and the third filter slag in the impurity removal slag treatment system 700, or be obtained by roasting the above-mentioned precipitation slag.

[0278] Preferably, step (3) is carried out at a rotation speed of 50 - 150 revolutions per minute, the reaction duration is 30 - 120 minutes, and a flocculant is also used, which can improve the reaction efficiency and facilitate filtration.

[0279] Figure 10 It is a schematic structural diagram of the second embodiment of the lithium leaching solution purification system of the present invention.

[0280] As Figure 10 shown, the lithium leaching solution purification system adopted in the second embodiment of the above-mentioned lithium leaching solution purification method includes a reaction component, a filtration component, and a resin adsorption device 850.

[0281] The reaction component is used to react the lithium leaching solution, the alkali solution, and the seed crystal to generate a solid-liquid mixture; the reaction component includes a reaction tank 860, an alkali solution dosing device 861 for adding the alkali solution into the reaction tank 860, a seed crystal dosing device 862 for adding the seed crystal into the reaction tank 860, a pH detector 863 for detecting the pH of the material in the reaction tank 860, a stirrer 864 for stirring the material in the reaction tank 860, and a flocculant dosing device 865 for adding the flocculant into the reaction tank 860.

[0282] The filtration component is used to filter the solid-liquid mixture and output the impurity removal slag and the purified liquid; the filtration component includes a plate and frame filter press 843 and a precision filter 842 connected in sequence.

[0283] The resin adsorption device 850 is used to perform resin adsorption treatment on the purified liquid.

[0284] The advantages of the second embodiment of the lithium leaching solution purification method and the lithium leaching solution purification system 800 of the present invention are:

[0285] 1. By adding a small amount of seed crystals as the growth sites for the precipitate, it helps the rapid growth of the precipitate and increases the size of the precipitate, thereby enhancing the purification reaction rate and filtration efficiency. When the seed crystals include Al2O3 and Fe2O3, the adsorption effect on lithium salts is small, which can reduce lithium loss. In particular, the seed crystals adopted can directly use the third filter residue in the above-mentioned impurity removal slag treatment method and impurity removal slag treatment system 700, or can be directly prepared from the lithium leaching solution by a simple method, realizing internal circulation, reducing the generation of solid waste, and significantly saving the production cost of lithium carbonate.

[0286] 2. Lepidolite itself contains a relatively large amount of potassium. Using potassium hydroxide and / or sodium hydroxide instead of traditional calcium oxide or calcium hydroxide can reduce the introduction of impurity ions, and the by-products K2SO4 or Na2SO4 generated (sulfuric acid is used for acidification treatment) have good solubility. This not only reduces the amount of precipitation (the calcium sulfate precipitation generated without the sulfuric acid method), but also can further purify and prepare high-purity K2SO4 or Na2SO4 products by evaporation crystallization before the lithium extraction system 900, thereby realizing the resource utilization of high-potassium lepidolite raw materials. In the traditional process, too many calcium ions are introduced, and excess calcium ions still need to add carbonate to remove them, increasing the consumption of carbonate, prolonging the process, and increasing the chemical agent cost.

[0287] The optimal embodiment of the lithium carbonate production method and production system of the present utility model is obtained by Figures 1 - 9 combining the methods and systems shown as follows:

[0288] Figure 11 is a schematic structural diagram of the optimal embodiment of the lithium carbonate production system of the present utility model.

[0289] As Figure 11 shown, the lithium carbonate production system includes Figure 6 the lepidolite raw material pretreatment system shown as Figure 7 the lepidolite acidified material leaching system shown as, and the lithium extraction system 900. Specifically, it includes Figures 1 - 3 any one of the lepidolite raw material roasting systems 200 shown as Figure 4 or Figure 5 the lepidolite clinker acidification system 300 shown as Figure 8 the impurity removal slag treatment system 700 shown as Figure 9 or Figure 10The lithium leaching solution purification system 800 shown. The lithium extraction system 900 is used to perform lithium extraction treatment on the purified solution and output lithium carbonate, which can be achieved by conventional methods. For example, an evaporation concentration system, a lithium precipitation system, and a lithium washing system can be used. First, most of the water is removed by evaporation concentration, significantly increasing the lithium concentration in the solution. Then, the concentrated lithium solution is reacted with carbonate ions by adding alkaline raw materials such as potassium carbonate and / or sodium carbonate to precipitate lithium carbonate. The addition amount of the carbonate needs to be controlled at 1.05 - 1.1 times the theoretical value to minimize lithium loss. Finally, the precipitated lithium carbonate is filtered and separated, and the lithium carbonate is washed multiple times to remove residual impurity ions therein.

[0290] The lithium carbonate production method and production system of the present utility model have the advantages possessed by each of the above-mentioned sections. In particular, when the above-mentioned method and system are organically combined into one, it can achieve the advantages of the lowest energy consumption, the least solid waste, the highest degree of resource utilization, the least lithium loss, the highest product purity, and the lowest production cost.

[0291] The above has described the relevant content of the present utility model. Those of ordinary skill in the art will be able to implement the present utility model based on these descriptions. Based on the above content of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present utility model.

Claims

1. A slag treatment system for removing impurities in lithium carbonate production, characterized by: The processing system includes: A roasting furnace (720) is used to roast the impurity-removed slag and output the roasted material; A first slurry mixing tank (731) is used to mix the roasted material with water to output a first slurry; A first filtering device (732) is used to filter the first slurry and output a first filter residue and a first filtrate; The second slurry mixing tank (741) is used to mix the first filter residue with water to output a second slurry; A second filtering device (742) is used to filter the second slurry and output a second filter residue and a second filtrate; The third slurry mixing tank (751) is used to mix the second filter residue with water and output the third slurry; The third filtering device (752) is used to filter the third slurry and output a third filter residue and a third filtrate.

2. The impurity removal slag treatment system in lithium carbonate production according to claim 1, characterized in that: The invention also includes a drying device (710) for drying the impurity-removed residue.

3. The impurity removal slag treatment system in lithium carbonate production according to claim 1, characterized in that: The method further comprises an intermediate tank (600), wherein the first filtrate, the second filtrate and the third filtrate flow into the intermediate tank (600) and are used as lithium leaching solution.

4. The impurity removal slag treatment system in lithium carbonate production according to claim 1, characterized in that: Also included is a filter residue storage tank (760) for storing the third filter residue.

5. The impurity removal slag treatment system in lithium carbonate production according to claim 1, characterized in that: The roasting furnace (720) is an externally heated roasting furnace (720).

6. A lithium carbonate production system, characterized in that: include: A lepidolite raw material roasting system (200) is used to roast the lepidolite raw material and output lepidolite clinker; The lepidolite clinker acidification system (300) is used to acidify the lepidolite clinker and output the lepidolite acidified material; The lepidolite acidified material slurry mixing system (400) is used to mix the lepidolite acidified material with water and output lithium leaching solution; A lithium leaching solution purification system (800) is used to purify the lithium leaching solution and output impurity-removed slag and purified solution; The impurity removal slag processing system (700) according to any one of claims 1 to 5; The lithium extraction system (900) is used to extract lithium from the purified liquid and output lithium carbonate.

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