WO2021143809A1 - Method for extracting lithium from lithium-containing low-magnesium brine - Google Patents

Method for extracting lithium from lithium-containing low-magnesium brine Download PDF

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WO2021143809A1
WO2021143809A1 PCT/CN2021/072040 CN2021072040W WO2021143809A1 WO 2021143809 A1 WO2021143809 A1 WO 2021143809A1 CN 2021072040 W CN2021072040 W CN 2021072040W WO 2021143809 A1 WO2021143809 A1 WO 2021143809A1
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lithium
magnesium
brine
containing low
solution
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PCT/CN2021/072040
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French (fr)
Chinese (zh)
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刘丽慧
林佳静
张如歌
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意定(上海)信息科技有限公司
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Publication of WO2021143809A1 publication Critical patent/WO2021143809A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10—Obtaining alkali metals
    • C22B26/12—Obtaining lithium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the invention relates to the technical fields of extraction chemistry and chemical engineering, in particular to a method for extracting lithium from lithium-containing low-magnesium brine.
  • Lithium is the metal with the smallest density and is widely used in batteries, greases, electronics and pharmaceuticals. In recent years, the widespread application of lithium-ion batteries has promoted the rapid growth of lithium demand, and the annual consumption of lithium is 20%. The speed of the left and right increases.
  • Lithium resources mainly exist in salt lakes. 85% of China's lithium resources exist in salt lakes, and ore resources account for only 15%.
  • the key issue for extracting lithium from salt lakes is how to separate lithium ions from the complex composition of brine.
  • the prior art processes for extracting lithium from brine include a calcination method, an adsorption method, a membrane separation method, a solar pond method, and a solvent extraction method.
  • the calcining method is to calcin the salt after evaporating and crystallizing brine to form insoluble MgO and easily soluble LiCl, and then precipitate to prepare Li 2 CO 3 after selective leaching.
  • MgCl 2 due to the decomposition of MgCl 2 during the calcination process, HCl gas is generated, causing serious environmental pollution.
  • the existing adsorption method uses an adsorbent that specifically adsorbs lithium ions to separate Li + from high-concentration Mg 2+ brines.
  • the specific process is to separate impurities such as magnesium, sodium, potassium, and boron to desorb the lithium-containing solution.
  • This method has been industrialized by Lanke Lithium. This method is more suitable for lower lithium ion concentration. Lithium is extracted from brine, but the adsorption method has the problems of large investment and large power consumption in subsequent equipment such as nanofiltration, reverse osmosis, and MVR.
  • the membrane separation method is to realize the separation of Li + and Mg 2+ through a monovalent cation exchange membrane to reduce the concentration ratio of Mg 2+ and Li + in the solution, that is, the ratio of magnesium to lithium. This process also has a large investment in subsequent equipment and power consumption.
  • the solar pond method is suitable for lithium carbonate salt lakes.
  • the method has low production cost, but the comprehensive yield of lithium is low, the production cycle is long, and the product quality is poor.
  • the purpose of the present invention is to provide a method for extracting lithium from lithium-containing low-magnesium brine.
  • the method provided by the invention can extract lithium from low-magnesium brine, and the lithium yield is high, the purity is high, the cost is low, the investment is small, and the material recycling rate is high.
  • the present invention provides a method for extracting lithium from lithium-containing low-magnesium brine, including the following steps:
  • the concentration of lithium in the lithium-containing low-magnesium brine is 0.2-2.5 g/L, and the concentration of magnesium is less than 6 g/L.
  • the lithium-containing low-magnesium brine in the step (2) includes lithium-containing low-magnesium salt lake brine, a salt lake brine adsorption method to remove impurities and lithium-concentrated lithium-containing low-magnesium desorption liquid, salt lake brine adsorption method to remove impurities and combine
  • the lithium-containing low-magnesium concentrate obtained by the desorption solution prepared after the lithium concentration is further reverse osmosis, the lithium-containing low-magnesium electrodialysis concentrate obtained by the monovalent ion selective electrodialysis treatment of the salt lake brine, and the salt lake brine are obtained by the treatment of magnesium removal by nanofiltration Any one of lithium-containing low-magnesium nanofiltration solution, high-magnesium brine and sodium carbonate or sodium bicarbonate to remove magnesium, lithium-containing low-magnesium brine, underground brine, lithium precipitation mother liquor, lithium battery waste leachate and lithium ore leachate Or several.
  • the addition amount of Na 2 CO 3 in the step (1) is 5-100% excessive compared to the theoretical addition amount calculated according to the chemical reaction with CaO.
  • the composite organic extraction system in the step (3) includes a neutral extractant and a chelating extractant
  • the neutral extractant is tributyl phosphate TBP, dimethyl heptyl methyl phosphate P350, trioctyl phosphine oxide TOPO, trioctyl/hexyl phosphine oxide Cyanex 923 and N,N two-(1-methylheptyl) Group) any one or more of acetamide N503;
  • the chelating extractant is 2-hydroxy-5-nonylacetophenone oxime LIX84, dodecylphenyl-methyl- ⁇ -diketone LIX54 and 2-hydroxy-5-nonylbenzaldehyde oxime LIX860 Any one or more of.
  • the acidic aqueous solution in the step (4) is carbonic acid, phosphoric acid, nitric acid, acetic acid, citric acid, hydrochloric acid or sulfuric acid.
  • the delithiated organic phase obtained in the step (4) is used as the composite organic extraction system in the step (3).
  • the CaCO 3 solid after the CaCO 3 solid is obtained in the step (1), it further includes calcining the CaCO 3 solid to obtain regenerated CaO and CO 2 .
  • it further includes using the regenerated CaO in the reaction of step (1); the CO 2 is used to prepare the acidic aqueous solution in step (4) or pass into the raffinate in step (3) to adjust the The pH value of the raffinate allows the raffinate to be discharged.
  • the CO 2 is passed into the raffinate of step (3) to prepare sodium bicarbonate; sodium carbonate is prepared from the sodium bicarbonate, and the prepared sodium carbonate is used as the reaction raw material in step (1).
  • the prepared sodium bicarbonate or sodium carbonate is also used for removing magnesium from high-magnesium brine.
  • the present invention provides a method for extracting lithium from lithium-containing low-magnesium brine, including the following steps: (1) CaO, water and excess Na 2 CO 3 are mixed for reaction, and the resulting reaction solution is filtered to obtain an alkaline solution and CaCO 3 solid; (2) adding the alkaline solution to the lithium-containing low-magnesium brine, gradually adjusting the pH of the lithium-containing low-magnesium brine to 11 or more, and respectively depositing basic magnesium carbonate and Mg(OH) 2 precipitates to obtain Lithium-containing brine after magnesium removal; (3) Using a composite organic extraction system to extract lithium in the lithium-containing brine after magnesium removal to obtain a loaded organic phase and a raffinate; (4) Combining the loaded organic phase with acid The aqueous solution is mixed, and the lithium in the loaded organic phase is back-extracted to the aqueous phase to obtain a lithium-containing aqueous solution and a delithiation organic phase.
  • the present invention adopts the reaction of excess Na 2 CO 3 and CaO to produce an alkali solution, and gradually adjusts the pH of the brine to above 11.
  • Sodium hydroxide and excess sodium carbonate in the alkali solution react with a small amount of Mg 2+ in the brine to form a basic formula
  • Magnesium carbonate and magnesium hydroxide are used to remove a small amount of Mg 2+ in the brine while meeting the need for alkalinity in the extraction of lithium by the extraction method of the present invention.
  • the method provided by the present invention has high removal efficiency of Mg 2+ , good pH adjustment effect, and low alkali consumption, especially in the presence of sulfate radicals, the alkali consumption and solid waste generation are greatly reduced (better than traditional Calcium oxide), the cost is significantly reduced.
  • the method provided by the invention can extract lithium from low-magnesium brine, with high lithium yield, high purity, low cost and low investment.
  • the present invention is to produce calcium carbonate CaO recycling solid after calcination, while the tail gas CO 2 generation, for stripping off-gas CO 2 Li, or into the raffinate to lower the pH, when the sodium ions in the raffinate And when the concentration of carbonate ions is high, sodium bicarbonate can be prepared and then sodium carbonate can be prepared to realize the recycling of sodium carbonate; in addition, the prepared sodium bicarbonate or sodium carbonate can also be used for removing magnesium from high-magnesium brine, thereby achieving both The coordinated development of various types of brines to extract lithium, such as the coordinated development of Cambodia’s Jieze Chaka low-magnesium carbonated salt lake brine and Longmu Co high-magnesium salt lake brine.
  • the material of the present invention has high recycling rate, low cost, small amount of waste residue, and is environmentally friendly. It is particularly suitable for remote locations and places with high raw material transportation costs (sodium hydroxide is a higher transportation cost for dangerous chemicals), such as the salt lakes in Egypt and South America. .
  • the present invention provides a method for extracting lithium from lithium-containing low-magnesium brine, including the following steps:
  • the loaded organic phase is mixed with the acidic aqueous solution, and the lithium in the loaded organic phase is back-extracted to the aqueous phase to obtain a lithium-containing aqueous solution and a delithiated organic phase.
  • the added amount of Na 2 CO 3 is preferably 5-100% excess, more preferably 10-70% excess compared to the theoretical addition calculated according to the chemical reaction with CaO.
  • the mixing is preferably stirring and mixing.
  • the present invention has no special requirements on the speed of the stirring and mixing, and the stirring speed known to those skilled in the art may be used.
  • the temperature of the reaction is preferably 40 to 95°C, more preferably 80 to 90°C, and the time is preferably 2 to 24 hours, more preferably 5 to 20 hours; the reaction formula of the reaction is shown in Formula 1. .
  • the present invention also preferably drying the obtained solid phase to obtain a CaCO 3 solid.
  • the drying temperature is preferably 150°C.
  • the present invention has no special requirements on the drying time, as long as the moisture in the CaCO 3 can be removed.
  • the present invention has no special requirements on the source of the CaO and Na 2 CO 3 , and commercially available products known to those skilled in the art can be used.
  • salt lake resource areas such as China’szhou region, are rich in carbonated salt lakes (the lithium-containing carbonated salt lakes are not necessarily used).
  • Sodium carbonate can be prepared by direct salt field drying or used in brines with high sodium ion concentration and carbonate ion concentration. Passing in CO 2 produces NaHCO 3 precipitation (sodium bicarbonate has low solubility and can be precipitated from brine) and then heating to prepare Na 2 CO 3.
  • the reaction process is as shown in formulas (2) and (3).
  • the present invention adds the alkaline solution to the lithium-containing low-magnesium brine, adjusts the pH value of the lithium-containing low-magnesium brine to about 9.5, first precipitates the basic magnesium carbonate precipitate, and then filters the basic carbonate The pH value of the brine after magnesium precipitation is adjusted to above 11, and then Mg(OH) 2 is precipitated to obtain lithium-containing brine after magnesium removal.
  • the concentration of lithium in the lithium-containing low-magnesium brine is preferably 0.2-2.5 g/L, and the concentration of magnesium is preferably ⁇ 6 g/L.
  • the concentration of lithium in the lithium-containing low-magnesium brine can be increased through salt field evaporation and concentration.
  • the desorption solution containing lithium and low magnesium can be prepared by removing magnesium by adsorption and concentrating the lithium, and even further reverse osmosis of the desorption solution to obtain a concentrated solution containing lithium and low magnesium;
  • the electrodialysis concentrated solution containing lithium and low magnesium can be obtained by monovalent ion selective electrodialysis treatment; the solution containing lithium and low magnesium can also be obtained by the treatment of magnesium removal by nanofiltration; or sodium carbonate or sodium bicarbonate can be added to remove magnesium to obtain lithium-containing solution.
  • the present invention can use the adsorption method to remove magnesium, sodium, potassium, boron, calcium and other impurity elements. It has the advantage of being able to appropriately concentrate the low-concentration lithium ions in the original brine, or electrodialysis, nanofiltration, chemical methods The advantages of being able to remove a large amount of magnesium ions, combined with the advantages of the extraction method of the present invention that are particularly good at separating lithium from sodium, potassium, boron and other impurity elements, and the advantages of the extraction method that can concentrate lithium ions with high multiples, thereby saving expensive and high energy consumption And the high operating cost of nanofiltration, reverse osmosis, electrodialysis, MVR and other equipment.
  • the pH value is preferably adjusted to 12-13.
  • the method of the present invention has high Mg 2+ removal efficiency, good pH adjustment effect, and low alkali consumption, especially in the presence of sulfate radicals, the alkali consumption and solid waste generation are greatly reduced (better than traditional calcium oxide ), the cost is significantly reduced.
  • the present invention uses a composite organic extraction system to extract the lithium in the magnesium-removed lithium-containing brine to obtain a loaded organic phase and a raffinate.
  • the composite organic extraction system preferably includes a neutral extractant and a chelating extractant.
  • the neutral extractant is preferably tributyl phosphate TBP, dimethylheptyl methyl phosphate P350, trioctyl phosphine oxide TOPO, trioctyl/hexyl phosphine oxide Cyanex 923 and N, N di- (1-methylheptyl) any one or more of acetamide N503;
  • the chelating extractant is preferably 2-hydroxy-5-nonylacetophenone oxime LIX84, dodecylphenyl-methyl Any one or more of 2-hydroxy-5-nonylbenzaldehyde oxime LIX54 and 2-hydroxy-5-nonylbenzaldehyde oxime LIX860.
  • the present invention does not have special requirements for the source of the composite organic extraction system, and it is sufficient to use a composite organic extraction system that is well-known to those skilled in the art; the present invention has no special requirements on the specific operation method of the extraction, and the technology in the field is adopted. The method familiar to the personnel is sufficient.
  • the present invention achieves high-efficiency separation of impurity elements such as Na, K and B in the brine through extraction (the extraction of the present invention is not suitable for separating lithium ions from magnesium ions and calcium ions), namely A loaded organic phase (containing lithium) and a raffinate (impurity phase) are obtained.
  • the present invention mixes the loaded organic phase with the acidic aqueous solution, and strips the lithium in the loaded organic phase to the aqueous phase to obtain a lithium-containing aqueous solution and a delithiated organic phase.
  • the acidic aqueous solution is preferably carbonic acid, phosphoric acid, nitric acid, acetic acid, citric acid, hydrochloric acid or sulfuric acid. After the stripping, an aqueous solution containing lithium and an organic phase for lithium removal are obtained.
  • the delithiated organic phase is preferably used as a composite organic extraction system in the above-mentioned extraction technical solution to form an extraction cycle.
  • the loaded organic phase is also preferably fed with carbon dioxide to obtain a lithium bicarbonate solution and then heated to generate a lithium carbonate product.
  • the present invention can realize the recycling of CaO and Na 2 CO 3. Specifically, after CaO, water and Na 2 CO 3 react to obtain CaCO 3 solids, the present invention also preferably calcinates the CaCO 3 solids to obtain regenerated CaO and CO. 2 .
  • the regenerated CaO is continuously used to react with Na 2 CO 3 to prepare NaOH solution and CaCO 3 solid; the CO 2 is used to prepare acidic aqueous solution (carbonic acid) for stripping or pass into the raffinate after extraction Adjust the pH value of the raffinate in the liquid so that the raffinate can be discharged.
  • sodium bicarbonate can also be prepared by passing the CO 2 into the raffinate; sodium carbonate can be further prepared from the sodium bicarbonate by heating and decomposing; the obtained sodium carbonate is continuously used to react with CaO Prepare NaOH solution and CaCO 3 solid.
  • the main composition of the original brine of Jieze Chaka Salt Lake in Vietnam is (g/L): Li, 0.17; Mg, 0.3; Na, 39; K, 2.3; SO 4 2- , 2.8; Ca, 0.004; Cl, 58; CO 3 2- , 2.06.
  • the salt field evaporation method is used to increase the concentration of lithium in the brine to form old brine, the main composition of which is (g/L): Li, 0.5; Mg, 0.1; Na, 121; K, 10.3; SO 4 2- , 12.8; Ca, 0.004; Cl, 180; CO 3 2- , 8.61.
  • the back-extraction rate of Li was 99.0%.
  • the extracted organic phase is returned to the extraction of Li to form an extraction cycle.
  • the Li stripping solution was heated to 80°C, and 98 mL of 2.0M Na 2 CO 3 solution was added, followed by stirring for 2 hours to obtain 10.5 g of Li 2 CO 3 with a purity of 99.2%.
  • the CO 2 gas produced in the above calcination step is passed into the remaining liquid after extraction, and 162 g of solids containing 87% NaHCO 3 are precipitated.
  • the main composition of the original brine from Longmucuo Salt Lake in Vietnam is (g/L): Li, 0.13; Mg, 11.33; Na, 30; K, 3; SO 4 2- , 6.42; Ca, 0.3; Cl, 78.
  • the desorption solution containing lithium and low magnesium is prepared by the adsorption method of aluminum adsorbent to remove magnesium and concentrate the lithium.
  • the main composition of the desorption solution is (g/L): Li, 0.3; Mg, 0.3; Na, 0.8; K, 0.08; SO 4 2- , 0.17; Ca, 0.008; Cl, 3.6.
  • the desorbed liquid is further reverse osmosis to obtain a concentrated liquid containing lithium and low magnesium.
  • the main composition of the concentrated liquid is (g/L): Li, 2.1; Mg, 2.1; Na, 5.6; K, 0.56; SO 4 2- , 1.19; Ca, 0.056; Cl, 25.2.
  • Na 2 CO 3 comes from sodium bicarbonate produced by passing CO 2 gas into the brine of Jieze Chaka Salt Lake beside Longmu Co Salt Lake, and Na 2 CO 3 produced by further decomposing sodium bicarbonate.
  • the Li stripping solution (aqueous solution of lithium bicarbonate) contains Li in the lithium bicarbonate solution at a concentration of 7.65g/L.
  • the lithium bicarbonate stripping solution is heated to 80°C and kept for 5.0h to obtain 74.9g Li 2 CO 3 .
  • the purity is 99.5%.
  • a salt lake brine the brine obtained by evaporation and concentration from salt fields is mainly composed of (g/L): Li, 1.5; Mg, 4.8; Na, 92; K, 4; SO 4 2- , 34.
  • the Li stripping solution (aqueous solution of lithium bicarbonate) contains Li concentration of 7.52g/L.
  • the lithium bicarbonate stripping solution is heated to 80°C and kept for 6.0h to obtain 70.2g Li 2 CO 3 with a purity of 99.6% .
  • the extraction method provided by the present invention can extract lithium from low-magnesium brine and can even be combined with techniques such as adsorption to achieve rapid industrialization of high-magnesium-lithium than salt lake raw brine, and the yield of lithium High, high purity, low cost and high material utilization rate.

Abstract

Disclosed is a method for extracting lithium from lithium-containing low-magnesium brine, relating to the technical field of chemistry and chemical engineering. The method comprises the following steps: mixing CaO, water and excess Na2CO3 for a reaction, and filtering a resulting reaction liquid to obtain a basic solution and a CaCO3 solid; adding the basic solution into lithium-containing low-magnesium brine, gradually adjusting the pH of the lithium-containing low-magnesium brine to 11 or more, and precipitating basic magnesium carbonate and a Mg(OH)2 precipitate to obtain a lithium-containing brine from which magnesium is removed; carrying out extraction on the lithium-containing brine from which magnesium is removed by using a complex organic extraction system, to obtain a loaded organic phase and an extraction raffinate; and mixing the loaded organic phase with an acid aqueous solution, and reverse extracting lithium in the loaded organic phase to obtain a lithium-containing aqueous solution and a lithium-removed organic phase. By means of the method, lithium can be extracted from lithium-containing low-magnesium brine, and the yield of lithium is high, the purity is high, and the cost is low, and same requires a small investment and has a high material cyclic utilization rate.

Description

一种从含锂低镁卤水中提取锂的方法Method for extracting lithium from lithium-containing low-magnesium brine
本申请要求于2020年01月19日提交中国专利局、申请号为202010081517.3、发明名称为“一种从含锂低镁卤水中提取锂的方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。This application claims the priority of a Chinese patent application filed with the Chinese Patent Office on January 19, 2020, the application number is 202010081517.3, and the invention title is "a method for extracting lithium from lithium-containing low-magnesium brine", the entire content of which is approved The reference is incorporated in this application.
技术领域Technical field
本发明涉及萃取化学、化工技术领域，特别涉及一种从含锂低镁卤水中提取锂的方法。The invention relates to the technical fields of extraction chemistry and chemical engineering, in particular to a method for extracting lithium from lithium-containing low-magnesium brine.
背景技术Background technique
锂是密度最小的金属，被广泛的应用于电池、润滑脂、电子和制药等领域，近些年锂离子电池的广泛应用推动了锂需求量的迅速增长，锂的消费量以年化20％左右的速度增加。Lithium is the metal with the smallest density and is widely used in batteries, greases, electronics and pharmaceuticals. In recent years, the widespread application of lithium-ion batteries has promoted the rapid growth of lithium demand, and the annual consumption of lithium is 20%. The speed of the left and right increases.
锂资源主要存在于盐湖之中，中国85％的锂资源存在于盐湖中，矿石资源仅占15％。盐湖提锂的关键问题是如何从复杂组成的卤水中分离锂离子。现有技术中卤水提锂工艺有煅烧法、吸附法、膜分离法、太阳池法、溶剂萃取法。Lithium resources mainly exist in salt lakes. 85% of China's lithium resources exist in salt lakes, and ore resources account for only 15%. The key issue for extracting lithium from salt lakes is how to separate lithium ions from the complex composition of brine. The prior art processes for extracting lithium from brine include a calcination method, an adsorption method, a membrane separation method, a solar pond method, and a solvent extraction method.
煅烧法是通过煅烧卤水蒸发结晶后的盐，形成难溶MgO和易溶的LiCl，选择性浸出后沉淀制备Li 2CO 3，但由于煅烧过程MgCl 2分解产生HCl气体，环境污染严重。现有吸附法是利用对于锂离子具有特异性吸附的吸附剂来实现从高浓度Mg 2+卤水中分离Li +，具体过程为分离镁、钠、钾、硼等杂质后对含锂解吸液进行纳滤、反渗透甚至电渗析，然后用MVR将锂离子浓度浓缩到20g/L左右，再加碳酸钠制备碳酸锂，此法已经由蓝科锂业工业化，该方法比较适合锂离子浓度比较低的卤水提锂，但吸附法存在后续的纳滤、反渗透、MVR等设备投资大、耗电量大的问题。膜分离法是通过一价阳离子交换膜实现Li +和Mg 2+的分离来降低溶液中的Mg 2+和Li +的浓度比即镁锂比，这一工艺也存在后续设备投资大、耗电量大的问题。太阳池法适合于碳酸锂型盐湖，该方法生产成本低，但锂的综合收率低、生产周期长、产品品质差。溶剂萃取法淡水用量少、设备和材料投资少、 耗电量少，但目前溶剂萃取技术仅适用于Mg 2+浓度高的老卤，对于低Mg 2+浓度的卤水适应性差。 The calcining method is to calcin the salt after evaporating and crystallizing brine to form insoluble MgO and easily soluble LiCl, and then precipitate to prepare Li 2 CO 3 after selective leaching. However, due to the decomposition of MgCl 2 during the calcination process, HCl gas is generated, causing serious environmental pollution. The existing adsorption method uses an adsorbent that specifically adsorbs lithium ions to separate Li + from high-concentration Mg 2+ brines. The specific process is to separate impurities such as magnesium, sodium, potassium, and boron to desorb the lithium-containing solution. Nanofiltration, reverse osmosis and even electrodialysis, and then use MVR to concentrate the lithium ion concentration to about 20g/L, and then add sodium carbonate to prepare lithium carbonate. This method has been industrialized by Lanke Lithium. This method is more suitable for lower lithium ion concentration. Lithium is extracted from brine, but the adsorption method has the problems of large investment and large power consumption in subsequent equipment such as nanofiltration, reverse osmosis, and MVR. The membrane separation method is to realize the separation of Li + and Mg 2+ through a monovalent cation exchange membrane to reduce the concentration ratio of Mg 2+ and Li + in the solution, that is, the ratio of magnesium to lithium. This process also has a large investment in subsequent equipment and power consumption. The amount of the problem. The solar pond method is suitable for lithium carbonate salt lakes. The method has low production cost, but the comprehensive yield of lithium is low, the production cycle is long, and the product quality is poor. Fresh water with less solvent extraction method, equipment and materials less investment, less power consumption, but the solvent extraction technique is only applicable to high concentrations of Mg 2+ bittern, brine adaptability to low Mg 2+ concentration difference.
发明内容Summary of the invention
有鉴于此，本发明目的在于提供一种从含锂低镁卤水中提取锂的方法。本发明提供的方法能够从低镁卤水中提取锂，锂的收率高、纯度高，且成本低、投资少、材料循环利用率高。In view of this, the purpose of the present invention is to provide a method for extracting lithium from lithium-containing low-magnesium brine. The method provided by the invention can extract lithium from low-magnesium brine, and the lithium yield is high, the purity is high, the cost is low, the investment is small, and the material recycling rate is high.
为了实现上述发明目的，本发明提供以下技术方案：In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:
本发明提供了一种从含锂低镁卤水中提取锂的方法，包括以下步骤：The present invention provides a method for extracting lithium from lithium-containing low-magnesium brine, including the following steps:
(1)将CaO、水和过量Na 2CO 3混合进行反应，将所得反应液过滤得到碱溶液和CaCO 3固体； (1) Mix CaO, water and excess Na 2 CO 3 to react, and filter the resulting reaction solution to obtain an alkali solution and a CaCO 3 solid;
(2)将所述碱溶液加入含锂低镁卤水中，将所述含锂低镁卤水的pH调节到11以上，析出碱式碳酸镁和Mg(OH) 2沉淀，得到除镁后的含锂卤水； (2) The alkaline solution is added to lithium-containing low-magnesium brine, the pH of the lithium-containing low-magnesium brine is adjusted to 11 or more, and basic magnesium carbonate and Mg(OH) 2 are precipitated to obtain the magnesium-containing brine after removal of magnesium. Lithium brine
(3)采用复合有机萃取体系萃取所述除镁后的含锂卤水中的锂，得到负载有机相和萃余液；(3) Using a composite organic extraction system to extract lithium in the lithium-containing brine after magnesium removal to obtain a loaded organic phase and raffinate;
(4)将所述负载有机相与酸性水溶液混合，将负载有机相中的锂反萃到水相，得到含锂的水溶液和脱锂有机相。(4) Mixing the loaded organic phase with an acidic aqueous solution, and back-extracting lithium in the loaded organic phase to the aqueous phase to obtain a lithium-containing aqueous solution and a delithiated organic phase.
优选地，所述含锂低镁卤水中锂的浓度为0.2～2.5g/L，镁的浓度<6g/L。Preferably, the concentration of lithium in the lithium-containing low-magnesium brine is 0.2-2.5 g/L, and the concentration of magnesium is less than 6 g/L.
优选地，所述步骤(2)中的含锂低镁卤水包括含锂低镁盐湖卤水、盐湖卤水吸附法除杂并浓缩锂后制备的含锂低镁解吸液、盐湖卤水吸附法除杂并浓缩锂后制备的解吸液进一步反渗透得到的含锂低镁浓缩液、盐湖卤水通过一价离子选择性电渗析处理获得的含锂低镁电渗析浓缩液、盐湖卤水通过纳滤除镁处理获得的含锂低镁纳滤溶液、高镁卤水加入碳酸钠或碳酸氢钠除镁后获得的含锂低镁卤水、地下卤水、沉锂母液、锂电池废料浸出液和锂矿石浸出液中的任意一种或几种。Preferably, the lithium-containing low-magnesium brine in the step (2) includes lithium-containing low-magnesium salt lake brine, a salt lake brine adsorption method to remove impurities and lithium-concentrated lithium-containing low-magnesium desorption liquid, salt lake brine adsorption method to remove impurities and combine The lithium-containing low-magnesium concentrate obtained by the desorption solution prepared after the lithium concentration is further reverse osmosis, the lithium-containing low-magnesium electrodialysis concentrate obtained by the monovalent ion selective electrodialysis treatment of the salt lake brine, and the salt lake brine are obtained by the treatment of magnesium removal by nanofiltration Any one of lithium-containing low-magnesium nanofiltration solution, high-magnesium brine and sodium carbonate or sodium bicarbonate to remove magnesium, lithium-containing low-magnesium brine, underground brine, lithium precipitation mother liquor, lithium battery waste leachate and lithium ore leachate Or several.
优选地，所述步骤(1)中Na 2CO 3的加入量相比按照与CaO化学反应计算的理论加入量过量5～100％。 Preferably, the addition amount of Na 2 CO 3 in the step (1) is 5-100% excessive compared to the theoretical addition amount calculated according to the chemical reaction with CaO.
优选地，所述步骤(3)中的复合有机萃取体系包括中性萃取剂和螯合萃取剂；Preferably, the composite organic extraction system in the step (3) includes a neutral extractant and a chelating extractant;
所述中性萃取剂为磷酸三丁酯TBP、甲基磷酸二甲庚酯P350、三辛基 氧化膦TOPO、三辛基/已基氧化膦Cyanex923和N,N二-(1-甲基庚基)乙酰胺N503中的任意一种或几种；The neutral extractant is tributyl phosphate TBP, dimethyl heptyl methyl phosphate P350, trioctyl phosphine oxide TOPO, trioctyl/hexyl phosphine oxide Cyanex 923 and N,N two-(1-methylheptyl) Group) any one or more of acetamide N503;
所述螯合萃取剂为2-羟基-5-壬基苯乙酮肟LIX84、十二烷基苯基-甲基-β-二酮LIX54和2-羟基-5-壬基苯甲醛肟LIX860中的任意一种或几种。The chelating extractant is 2-hydroxy-5-nonylacetophenone oxime LIX84, dodecylphenyl-methyl-β-diketone LIX54 and 2-hydroxy-5-nonylbenzaldehyde oxime LIX860 Any one or more of.
优选地，所述步骤(4)中的酸性水溶液为碳酸、磷酸、硝酸、醋酸、柠檬酸、盐酸或硫酸。Preferably, the acidic aqueous solution in the step (4) is carbonic acid, phosphoric acid, nitric acid, acetic acid, citric acid, hydrochloric acid or sulfuric acid.
优选地，所述步骤(4)得到的脱锂有机相作为步骤(3)中的复合有机萃取体系。Preferably, the delithiated organic phase obtained in the step (4) is used as the composite organic extraction system in the step (3).
优选地，所述步骤(1)中得到CaCO 3固体后，还包括对所述CaCO 3固体进行煅烧，得到再生CaO和CO 2。 Preferably, after the CaCO 3 solid is obtained in the step (1), it further includes calcining the CaCO 3 solid to obtain regenerated CaO and CO 2 .
优选地，还包括将所述再生CaO用于步骤(1)的反应；所述CO 2用于制备步骤(4)中的酸性水溶液或通入步骤(3)中的萃余液中调节所述萃余液的pH值，使萃余液能够排放。 Preferably, it further includes using the regenerated CaO in the reaction of step (1); the CO 2 is used to prepare the acidic aqueous solution in step (4) or pass into the raffinate in step (3) to adjust the The pH value of the raffinate allows the raffinate to be discharged.
优选地，所述CO 2通入步骤(3)的萃余液中制备出碳酸氢钠；由所述碳酸氢钠制备碳酸钠，制备得到的碳酸钠用作步骤(1)的反应原料。 Preferably, the CO 2 is passed into the raffinate of step (3) to prepare sodium bicarbonate; sodium carbonate is prepared from the sodium bicarbonate, and the prepared sodium carbonate is used as the reaction raw material in step (1).
优选地，制备到的碳酸氢钠或碳酸钠还用于高镁卤水的除镁。Preferably, the prepared sodium bicarbonate or sodium carbonate is also used for removing magnesium from high-magnesium brine.
本发明提供了一种从含锂低镁卤水中提取锂的方法，包括以下步骤：(1)将CaO、水和过量的Na 2CO 3混合进行反应，将所得反应液过滤得到碱溶液和CaCO 3固体；(2)将所述碱溶液加入含锂低镁卤水中，将所述含锂低镁卤水的pH逐步调节到11以上，分别析出碱式碳酸镁和Mg(OH) 2沉淀，得到除镁后的含锂卤水；(3)采用复合有机萃取体系萃取所述除镁后的含锂卤水中的锂，得到负载有机相和萃余液；(4)将所述负载有机相与酸性水溶液混合，将负载有机相中的锂反萃到水相，得到含锂的水溶液和脱锂有机相。本发明采用过量的Na 2CO 3与CaO反应产生碱溶液，并逐步调节卤水的pH到11以上，碱溶液中的氢氧化钠和过量的碳酸钠与卤水中的少量Mg 2+反应生成碱式碳酸镁和氢氧化镁，从而除去卤水中少量的Mg 2+同时满足本发明萃取法提取锂对碱度的需要。本发明提供的方法对Mg 2+去除效率高，pH值调节效果好，碱耗量低，特别是在有硫酸根存在的情况下，碱耗量及固体废物产生量大大减少(优于传统的氧化钙)，成本明显降低。 本发明提供的方法能够从低镁卤水中提取锂，锂的收率高、纯度高，且成本低、投资少。 The present invention provides a method for extracting lithium from lithium-containing low-magnesium brine, including the following steps: (1) CaO, water and excess Na 2 CO 3 are mixed for reaction, and the resulting reaction solution is filtered to obtain an alkaline solution and CaCO 3 solid; (2) adding the alkaline solution to the lithium-containing low-magnesium brine, gradually adjusting the pH of the lithium-containing low-magnesium brine to 11 or more, and respectively depositing basic magnesium carbonate and Mg(OH) 2 precipitates to obtain Lithium-containing brine after magnesium removal; (3) Using a composite organic extraction system to extract lithium in the lithium-containing brine after magnesium removal to obtain a loaded organic phase and a raffinate; (4) Combining the loaded organic phase with acid The aqueous solution is mixed, and the lithium in the loaded organic phase is back-extracted to the aqueous phase to obtain a lithium-containing aqueous solution and a delithiation organic phase. The present invention adopts the reaction of excess Na 2 CO 3 and CaO to produce an alkali solution, and gradually adjusts the pH of the brine to above 11. Sodium hydroxide and excess sodium carbonate in the alkali solution react with a small amount of Mg 2+ in the brine to form a basic formula Magnesium carbonate and magnesium hydroxide are used to remove a small amount of Mg 2+ in the brine while meeting the need for alkalinity in the extraction of lithium by the extraction method of the present invention. The method provided by the present invention has high removal efficiency of Mg 2+ , good pH adjustment effect, and low alkali consumption, especially in the presence of sulfate radicals, the alkali consumption and solid waste generation are greatly reduced (better than traditional Calcium oxide), the cost is significantly reduced. The method provided by the invention can extract lithium from low-magnesium brine, with high lithium yield, high purity, low cost and low investment.
进一步地，本发明将碳酸钙固体煅烧分解后产生CaO循环使用，同时产生CO 2尾气，CO 2尾气用于反萃Li，或通入萃余液中降低pH值，当萃余液中钠离子和碳酸根离子浓度高时，可以制备碳酸氢钠进而制备碳酸钠，实现碳酸钠的循环利用；此外制备得到的碳酸氢钠或碳酸钠还可以用于高镁卤水的除镁，从而可以实现两种类型卤水的协同开发提锂，比如西藏结则茶卡低镁碳酸型盐湖卤水和龙木错高镁盐湖卤水的协同开发。本发明材料循环利用率高，成本低，废渣量小，环境友好，特别适合地理位置偏远，原材料运输成本高的地方(氢氧化钠是危险化学品运输成本更高)，比如西藏和南美的盐湖。 Further, the present invention is to produce calcium carbonate CaO recycling solid after calcination, while the tail gas CO 2 generation, for stripping off-gas CO 2 Li, or into the raffinate to lower the pH, when the sodium ions in the raffinate And when the concentration of carbonate ions is high, sodium bicarbonate can be prepared and then sodium carbonate can be prepared to realize the recycling of sodium carbonate; in addition, the prepared sodium bicarbonate or sodium carbonate can also be used for removing magnesium from high-magnesium brine, thereby achieving both The coordinated development of various types of brines to extract lithium, such as the coordinated development of Tibet’s Jieze Chaka low-magnesium carbonated salt lake brine and Longmu Co high-magnesium salt lake brine. The material of the present invention has high recycling rate, low cost, small amount of waste residue, and is environmentally friendly. It is particularly suitable for remote locations and places with high raw material transportation costs (sodium hydroxide is a higher transportation cost for dangerous chemicals), such as the salt lakes in Tibet and South America. .
具体实施方式Detailed ways
本发明提供了一种从含锂低镁卤水中提取锂的方法，包括以下步骤：The present invention provides a method for extracting lithium from lithium-containing low-magnesium brine, including the following steps:
(1)将CaO、水和过量的Na 2CO 3混合进行反应，将所得反应液过滤得到碱溶液和CaCO 3固体； (1) Mix CaO, water and excess Na 2 CO 3 to react, and filter the resulting reaction solution to obtain an alkali solution and a CaCO 3 solid;
(2)将所述碱溶液加入含锂低镁卤水中，将所述含锂低镁卤水的pH逐步调节到11以上，分别析出碱式碳酸镁和Mg(OH) 2沉淀，得到除镁后的含锂卤水； (2) The alkaline solution is added to lithium-containing low-magnesium brine, the pH of the lithium-containing low-magnesium brine is gradually adjusted to above 11, and basic magnesium carbonate and Mg(OH) 2 are precipitated to obtain the magnesium-removed brine. Of lithium-containing brine;
(3)采用复合有机萃取体系萃取所述除镁后的含锂卤水中的锂，得到负载有机相和萃余液；(3) Using a composite organic extraction system to extract lithium in the lithium-containing brine after magnesium removal to obtain a loaded organic phase and raffinate;
(4)将所述负载有机相与酸性水溶液混合，将负载有机相中的锂反萃到水相，得到含锂的水溶液和脱锂有机相。(4) The loaded organic phase is mixed with the acidic aqueous solution, and the lithium in the loaded organic phase is back-extracted to the aqueous phase to obtain a lithium-containing aqueous solution and a delithiated organic phase.
本发明将CaO、水和过量的Na 2CO 3混合进行反应，将所得反应液过滤得到碱溶液和CaCO 3固体。在本发明中，所述Na 2CO 3的加入量优选相比按照与CaO化学反应计算的理论加入量过量5～100％，更优选过量10～70％。 In the present invention, CaO, water and excess Na 2 CO 3 are mixed for reaction, and the obtained reaction liquid is filtered to obtain an alkali solution and a CaCO 3 solid. In the present invention, the added amount of Na 2 CO 3 is preferably 5-100% excess, more preferably 10-70% excess compared to the theoretical addition calculated according to the chemical reaction with CaO.
在本发明中，所述混合优选为搅拌混合，本发明对所述搅拌混合的速度没有特别的要求，采用本领域技术人员公知的搅拌速度即可。在本发明中，所述反应的温度优选为40～95℃，更优选为80～90℃，时间优选为2～24h，更优选为5～20h；所述反应的反应式如式1所示。In the present invention, the mixing is preferably stirring and mixing. The present invention has no special requirements on the speed of the stirring and mixing, and the stirring speed known to those skilled in the art may be used. In the present invention, the temperature of the reaction is preferably 40 to 95°C, more preferably 80 to 90°C, and the time is preferably 2 to 24 hours, more preferably 5 to 20 hours; the reaction formula of the reaction is shown in Formula 1. .
所述过滤后，本发明还优选对所得固相进行干燥，得到CaCO 3固体。在本发明中，所述干燥的温度优选为150℃，本发明对所述干燥的时间没有特别的要求，能够将CaCO 3中的水分去除即可。 After the filtration, the present invention also preferably drying the obtained solid phase to obtain a CaCO 3 solid. In the present invention, the drying temperature is preferably 150°C. The present invention has no special requirements on the drying time, as long as the moisture in the CaCO 3 can be removed.
本发明对所述CaO和Na 2CO 3的来源没有特别的要求，采用本领域技术人员公知的市售产品即可。此外，盐湖资源地区，如中国西藏地区碳酸型盐湖资源丰富(不一定要用含锂的碳酸型盐湖)，可以通过直接盐田晒制备碳酸钠或向钠离子浓度和碳酸根离子浓度高的卤水中通入CO 2产生NaHCO 3沉淀(碳酸氢钠溶解度小，可从卤水中析出)再加热制备Na 2CO 3，反应过程如式如(2)和式(3)所示。 The present invention has no special requirements on the source of the CaO and Na 2 CO 3 , and commercially available products known to those skilled in the art can be used. In addition, salt lake resource areas, such as China’s Tibet region, are rich in carbonated salt lakes (the lithium-containing carbonated salt lakes are not necessarily used). Sodium carbonate can be prepared by direct salt field drying or used in brines with high sodium ion concentration and carbonate ion concentration. Passing in CO 2 produces NaHCO 3 precipitation (sodium bicarbonate has low solubility and can be precipitated from brine) and then heating to prepare Na 2 CO 3. The reaction process is as shown in formulas (2) and (3).
Na 2CO 3+CaO+H 2O＝2NaOH+CaCO 3↓         (式1) Na 2 CO 3 +CaO+H 2 O=2NaOH+CaCO 3 ↓ (Equation 1)
Na 2CO 3(卤水成分)+CO 2+H 2O＝2NaHCO 3↓   (式2) Na 2 CO 3 (brine component) + CO 2 + H 2 O = 2NaHCO 3 ↓ (Equation 2)
2NaHCO 3(加热)＝Na 2CO 3+H 2O+CO 2↑       (式3) 2NaHCO 3 (heating)=Na 2 CO 3 +H 2 O+CO 2 ↑ (Equation 3)
得到碱溶液后，本发明将所述碱溶液加入含锂低镁卤水中，将所述含锂低镁卤水的pH值调节到9.5左右，先析出碱式碳酸镁沉淀，再将过滤碱式碳酸镁沉淀后的卤水的pH值调节到11以上，再析出Mg(OH) 2沉淀，得到除镁后的含锂卤水。在本发明中，所述含锂低镁卤水中锂的浓度优选为0.2～2.5g/L，镁的浓度优选<6g/L。当含锂低镁卤水中锂的浓度低于所述范围值时，可通过盐田蒸发浓缩提高卤水中锂的浓度。当卤水中镁的浓度高于所述范围值时，可以通过吸附法除镁并浓缩锂后制备含锂低镁的解吸液甚至将解吸液进一步反渗透得到含锂低镁的浓缩液；也可以通过一价离子选择性电渗析处理获得含锂低镁的电渗析浓缩液；也可以通过纳滤除镁处理获得含锂低镁的溶液；也可以加入碳酸钠或碳酸氢钠除镁获得含锂低镁的卤水。针对高镁卤水，本发明可以利用吸附法除镁、钠、钾、硼、钙等杂质元素能力强同时能将原卤水中低浓度的锂离子适当浓缩的优势或者电渗析、纳滤、化学法能除大量镁离子的优势，结合本发明的萃取法特别擅长将锂与钠、钾、硼等杂质元素分离的优势以及萃取法能将锂离子浓缩的倍数高的优势从而节约昂贵、能耗高且运行成本高的纳滤、反渗透、电渗析、MVR等设备。在本发明中，所述pH值优选调节至12～13。本发明的方法Mg 2+去除效率高，pH值调节效果好，碱耗量低，特别是在有硫酸根 存在的情况下，碱耗量及固体废物产生量大大减少(优于传统的氧化钙)，成本明显降低。 After the alkaline solution is obtained, the present invention adds the alkaline solution to the lithium-containing low-magnesium brine, adjusts the pH value of the lithium-containing low-magnesium brine to about 9.5, first precipitates the basic magnesium carbonate precipitate, and then filters the basic carbonate The pH value of the brine after magnesium precipitation is adjusted to above 11, and then Mg(OH) 2 is precipitated to obtain lithium-containing brine after magnesium removal. In the present invention, the concentration of lithium in the lithium-containing low-magnesium brine is preferably 0.2-2.5 g/L, and the concentration of magnesium is preferably <6 g/L. When the concentration of lithium in the lithium-containing low-magnesium brine is lower than the range value, the concentration of lithium in the brine can be increased through salt field evaporation and concentration. When the concentration of magnesium in the brine is higher than the value in the range, the desorption solution containing lithium and low magnesium can be prepared by removing magnesium by adsorption and concentrating the lithium, and even further reverse osmosis of the desorption solution to obtain a concentrated solution containing lithium and low magnesium; The electrodialysis concentrated solution containing lithium and low magnesium can be obtained by monovalent ion selective electrodialysis treatment; the solution containing lithium and low magnesium can also be obtained by the treatment of magnesium removal by nanofiltration; or sodium carbonate or sodium bicarbonate can be added to remove magnesium to obtain lithium-containing solution. Low-magnesium brine. For high-magnesium brines, the present invention can use the adsorption method to remove magnesium, sodium, potassium, boron, calcium and other impurity elements. It has the advantage of being able to appropriately concentrate the low-concentration lithium ions in the original brine, or electrodialysis, nanofiltration, chemical methods The advantages of being able to remove a large amount of magnesium ions, combined with the advantages of the extraction method of the present invention that are particularly good at separating lithium from sodium, potassium, boron and other impurity elements, and the advantages of the extraction method that can concentrate lithium ions with high multiples, thereby saving expensive and high energy consumption And the high operating cost of nanofiltration, reverse osmosis, electrodialysis, MVR and other equipment. In the present invention, the pH value is preferably adjusted to 12-13. The method of the present invention has high Mg 2+ removal efficiency, good pH adjustment effect, and low alkali consumption, especially in the presence of sulfate radicals, the alkali consumption and solid waste generation are greatly reduced (better than traditional calcium oxide ), the cost is significantly reduced.
得到除镁后的含锂卤水后，本发明采用复合有机萃取体系萃取所述除镁后的含锂卤水中的锂，得到负载有机相和萃余液。在本发明中，所述复合有机萃取体系优选包括中性萃取剂和螯合萃取剂。在本发明中，所述中性萃取剂优选为磷酸三丁酯TBP、甲基磷酸二甲庚酯P350、三辛基氧化膦TOPO、三辛基/已基氧化膦Cyanex923和N,N二-(1-甲基庚基)乙酰胺N503中的任意一种或几种；所述螯合萃取剂优选为2-羟基-5-壬基苯乙酮肟LIX84、十二烷基苯基-甲基-β-二酮LIX54和2-羟基-5-壬基苯甲醛肟LIX860中的任意一种或几种。本发明对所述复合有机萃取体系的来源没有特别的要求，采用本领域技术人员熟知来源的复合有机萃取体系即可；本发明对所述萃取的具体操作方法没有特别的要求，采用本领域技术人员熟知的方法即可。除掉镁离子、钙离子之后，本发明通过萃取实现锂与卤水中Na、K和B等杂质元素的高效分离(本发明所述萃取不适合将锂离子与镁离子、钙离子分离)，即得到负载有机相(含锂)和萃余液(杂质相)。After the magnesium-removed lithium-containing brine is obtained, the present invention uses a composite organic extraction system to extract the lithium in the magnesium-removed lithium-containing brine to obtain a loaded organic phase and a raffinate. In the present invention, the composite organic extraction system preferably includes a neutral extractant and a chelating extractant. In the present invention, the neutral extractant is preferably tributyl phosphate TBP, dimethylheptyl methyl phosphate P350, trioctyl phosphine oxide TOPO, trioctyl/hexyl phosphine oxide Cyanex 923 and N, N di- (1-methylheptyl) any one or more of acetamide N503; the chelating extractant is preferably 2-hydroxy-5-nonylacetophenone oxime LIX84, dodecylphenyl-methyl Any one or more of 2-hydroxy-5-nonylbenzaldehyde oxime LIX54 and 2-hydroxy-5-nonylbenzaldehyde oxime LIX860. The present invention does not have special requirements for the source of the composite organic extraction system, and it is sufficient to use a composite organic extraction system that is well-known to those skilled in the art; the present invention has no special requirements on the specific operation method of the extraction, and the technology in the field is adopted. The method familiar to the personnel is sufficient. After removing magnesium ions and calcium ions, the present invention achieves high-efficiency separation of impurity elements such as Na, K and B in the brine through extraction (the extraction of the present invention is not suitable for separating lithium ions from magnesium ions and calcium ions), namely A loaded organic phase (containing lithium) and a raffinate (impurity phase) are obtained.
得到负载有机相后，本发明将所述负载有机相与酸性水溶液混合，将负载有机相中的锂反萃到水相，得到含锂的水溶液和脱锂有机相。在本发明中，所述酸性水溶液优选为碳酸、磷酸、硝酸、醋酸、柠檬酸、盐酸或硫酸。反萃后，得到含锂的水溶液和脱锂有机相。After obtaining the loaded organic phase, the present invention mixes the loaded organic phase with the acidic aqueous solution, and strips the lithium in the loaded organic phase to the aqueous phase to obtain a lithium-containing aqueous solution and a delithiated organic phase. In the present invention, the acidic aqueous solution is preferably carbonic acid, phosphoric acid, nitric acid, acetic acid, citric acid, hydrochloric acid or sulfuric acid. After the stripping, an aqueous solution containing lithium and an organic phase for lithium removal are obtained.
在本发明中，所述脱锂有机相优选作为复合有机萃取体系用于上述萃取的技术方案中，形成萃取循环。In the present invention, the delithiated organic phase is preferably used as a composite organic extraction system in the above-mentioned extraction technical solution to form an extraction cycle.
所述负载有机相还优选通入二氧化碳得到碳酸氢锂溶液再加热生成碳酸锂产品。The loaded organic phase is also preferably fed with carbon dioxide to obtain a lithium bicarbonate solution and then heated to generate a lithium carbonate product.
本发明能够实现CaO和Na 2CO 3的循环利用，具体地，CaO、水和Na 2CO 3反应得到CaCO 3固体后，本发明还优选对所述CaCO 3固体进行煅烧，得到再生CaO和CO 2。在本发明中，所述再生CaO继续用于和Na 2CO 3反应制备NaOH溶液和CaCO 3固体；所述CO 2用于制备反萃用的酸性水溶液(碳酸)或通入萃取后的萃余液中调节所述萃余液的pH值，使萃余液能够排放。在本发明具体实施例中，所述CO 2通入萃余液中还可制备出碳酸氢钠；由 所述碳酸氢钠进一步通过加热分解制备出碳酸钠；所得碳酸钠继续用于和CaO反应制备NaOH溶液和CaCO 3固体。 The present invention can realize the recycling of CaO and Na 2 CO 3. Specifically, after CaO, water and Na 2 CO 3 react to obtain CaCO 3 solids, the present invention also preferably calcinates the CaCO 3 solids to obtain regenerated CaO and CO. 2 . In the present invention, the regenerated CaO is continuously used to react with Na 2 CO 3 to prepare NaOH solution and CaCO 3 solid; the CO 2 is used to prepare acidic aqueous solution (carbonic acid) for stripping or pass into the raffinate after extraction Adjust the pH value of the raffinate in the liquid so that the raffinate can be discharged. In the specific embodiment of the present invention, sodium bicarbonate can also be prepared by passing the CO 2 into the raffinate; sodium carbonate can be further prepared from the sodium bicarbonate by heating and decomposing; the obtained sodium carbonate is continuously used to react with CaO Prepare NaOH solution and CaCO 3 solid.
下面结合实施例对本发明提供的从含锂低镁卤水中提取锂的方法进行详细的说明，但是不能把它们理解为对本发明保护范围的限定。The method for extracting lithium from lithium-containing low-magnesium brine provided by the present invention will be described in detail below in conjunction with examples, but they cannot be understood as limiting the scope of protection of the present invention.
实施例1Example 1
西藏结则茶卡盐湖原卤水主要组成为(g/L)：Li，0.17；Mg，0.3；Na，39；K，2.3；SO 4 2-，2.8；Ca，0.004；Cl，58；CO 3 2-，2.06。为了降低本发明提锂的成本，对结则茶卡原卤水用盐田蒸发的方法提高卤水中锂的浓度，形成老卤水，其主要组成为(g/L)：Li，0.5；Mg，0.1；Na，121；K，10.3；SO 4 2-，12.8；Ca，0.004；Cl，180；CO 3 2-，8.61。 The main composition of the original brine of Jieze Chaka Salt Lake in Tibet is (g/L): Li, 0.17; Mg, 0.3; Na, 39; K, 2.3; SO 4 2- , 2.8; Ca, 0.004; Cl, 58; CO 3 2- , 2.06. In order to reduce the cost of extracting lithium in the present invention, the salt field evaporation method is used to increase the concentration of lithium in the brine to form old brine, the main composition of which is (g/L): Li, 0.5; Mg, 0.1; Na, 121; K, 10.3; SO 4 2- , 12.8; Ca, 0.004; Cl, 180; CO 3 2- , 8.61.
取1700g Na 2CO 3(过量10％)，加入7.2L水搅拌，然后缓慢加入814g CaO，升温到80℃，继续搅拌5h，停止搅拌，过滤得到含184g/L NaOH的碱溶液6.1L，并得到1962g含水的CaCO 3固体，CaCO 3固体150℃下干燥，然后煅烧得到850g固体，主要成分为CaO。 Take 1700g Na 2 CO 3 (excess 10%), add 7.2L water and stir, then slowly add 814g CaO, warm up to 80℃, continue stirring for 5h, stop stirring, filter to obtain 6.1L alkali solution containing 184g/L NaOH, and Obtained 1962 g of water-containing CaCO 3 solid, and the CaCO 3 solid was dried at 150° C., and then calcined to obtain 850 g of solid, the main component of which was CaO.
取5.0L上述老卤水，加入215mL过滤后的含NaOH的碱溶液，过滤后的溶液中的Mg和Ca均小于0.2ppm(ICP-AES检查限)，pH＝12.5。然后采用TOPO和LIX860混合形成的复合萃取剂，控制TOPO与LIX860的体积比为1:1，相比A/O＝2：1，室温下连续两级逆流萃取，Li萃取率为96.1％，Na、K等其它杂质萃取率<0.01％。萃取后负载有机相采用6.0M HCl在相比A/O＝1：43下反萃，得到含Li 40.9g/L的反萃液(氯化锂的水溶液)，Li反萃率99.0％，反萃后的有机相返回Li的萃取形成萃取循环。Li的反萃液加热到80℃，并加入2.0M Na 2CO 3溶液98mL，保温搅拌2h得到Li 2CO 3 10.5g，纯度为99.2％。将上述煅烧步骤产生的CO 2气体通入萃取后的余液，析出162g含NaHCO 3 87％的固体，干燥后加热到300℃，生成主要含Na 2CO 3的固体，固体循环到与CaO的反应步骤，从而实现Na 2CO 3循环利用甚至可以制备多余的Na 2CO 3用于高镁卤水的除镁。 Take 5.0L of the above-mentioned old brine, add 215mL of filtered alkaline solution containing NaOH, the Mg and Ca in the filtered solution are both less than 0.2ppm (ICP-AES inspection limit), pH=12.5. Then use the composite extractant formed by mixing TOPO and LIX860, control the volume ratio of TOPO and LIX860 to 1:1, compared with A/O=2:1, continuous two-stage countercurrent extraction at room temperature, the extraction rate of Li is 96.1%, Na , K and other impurities extraction rate <0.01%. After extraction, the loaded organic phase was back-extracted with 6.0M HCl at a ratio of A/O=1:43 to obtain a back-extraction solution containing Li 40.9g/L (aqueous solution of lithium chloride). The back-extraction rate of Li was 99.0%. The extracted organic phase is returned to the extraction of Li to form an extraction cycle. The Li stripping solution was heated to 80°C, and 98 mL of 2.0M Na 2 CO 3 solution was added, followed by stirring for 2 hours to obtain 10.5 g of Li 2 CO 3 with a purity of 99.2%. The CO 2 gas produced in the above calcination step is passed into the remaining liquid after extraction, and 162 g of solids containing 87% NaHCO 3 are precipitated. After drying, they are heated to 300°C to produce solids mainly containing Na 2 CO 3. The solids are recycled to the CaO In the reaction step, Na 2 CO 3 can be recycled and even excess Na 2 CO 3 can be prepared to remove magnesium from high-magnesium brine.
实施例2Example 2
西藏龙木错盐湖原卤水主要组成为(g/L)：Li，0.13；Mg，11.33；Na，30；K，3；SO 4 2-，6.42；Ca，0.3；Cl，78。用铝系吸附剂的吸附法除 镁并浓缩锂后制备含锂低镁的解吸液，解吸液主要组成为(g/L)：Li，0.3；Mg，0.3；Na，0.8；K，0.08；SO 4 2-，0.17；Ca，0.008；Cl，3.6。然后将解吸液进一步反渗透得到含锂低镁的浓缩液，浓缩液主要组成为(g/L)：Li，2.1；Mg，2.1；Na，5.6；K，0.56；SO 4 2-，1.19；Ca，0.056；Cl，25.2。 The main composition of the original brine from Longmucuo Salt Lake in Tibet is (g/L): Li, 0.13; Mg, 11.33; Na, 30; K, 3; SO 4 2- , 6.42; Ca, 0.3; Cl, 78. The desorption solution containing lithium and low magnesium is prepared by the adsorption method of aluminum adsorbent to remove magnesium and concentrate the lithium. The main composition of the desorption solution is (g/L): Li, 0.3; Mg, 0.3; Na, 0.8; K, 0.08; SO 4 2- , 0.17; Ca, 0.008; Cl, 3.6. Then, the desorbed liquid is further reverse osmosis to obtain a concentrated liquid containing lithium and low magnesium. The main composition of the concentrated liquid is (g/L): Li, 2.1; Mg, 2.1; Na, 5.6; K, 0.56; SO 4 2- , 1.19; Ca, 0.056; Cl, 25.2.
取1430g Na 2CO 3(过量20％)，加入4.0L水搅拌，然后缓慢加入630g CaO，40℃继续搅拌24h，停止搅拌，过滤得到含220g/L NaOH的碱溶液3.68L，并得到1355g含水的CaCO 3固体，CaCO 3固体150℃下干燥，然后煅烧得到682g固体，主要成分为CaO。CaO循环使用，煅烧时产生的CO 2气体也循环使用。其中Na 2CO 3来自于将CO 2气体通入龙木错盐湖旁边的结则茶卡盐湖卤水中制得的碳酸氢钠，进一步将碳酸氢钠分解后制得的Na 2CO 3。 Take 1430g Na 2 CO 3 (excess 20%), add 4.0L water and stir, then slowly add 630g CaO, continue stirring for 24h at 40°C, stop stirring, filter to obtain 3.68L alkali solution containing 220g/L NaOH, and obtain 1355g water the solid CaCO 3, CaCO 3 solid at 150 deg.] C, and then calcined to give 682g solid, mainly composed of CaO. CaO is recycled and the CO 2 gas generated during calcination is also recycled. Among them, Na 2 CO 3 comes from sodium bicarbonate produced by passing CO 2 gas into the brine of Jieze Chaka Salt Lake beside Longmu Co Salt Lake, and Na 2 CO 3 produced by further decomposing sodium bicarbonate.
取10L上述浓缩液，加入上述过滤后的含NaOH的碱溶液1L，分别析出碱式碳酸镁和Mg(OH) 2沉淀，溶液中的Mg和Ca均小于0.2ppm(ICP-AES检查限)，pH＝12.5。过滤，分离除去碱式碳酸镁和Mg(OH) 2沉淀,然后采用Cyanex923和LIX54混合形成的复合萃取剂，控制Cyanex923与LIX54的体积比为2:1，相比A/O＝1：2，室温下连续两级逆流萃取，Li萃取率为95.4％，Na、K等其它杂质萃取率<0.01％。萃取后负载有机相加入水，使有机相与水的体积比为5.5：1，并将CO 2气体通入体系搅拌30min，Li被反萃到水相，反萃率92.2％，反萃后的有机相返回Li的萃取形成萃取循环。Li的反萃液(碳酸氢锂的水溶液)碳酸氢锂溶液中含Li浓度为7.65g/L，碳酸氢锂反萃液加热到80℃，并保温5.0h，得到74.9g Li 2CO 3，纯度为99.5％。 Take 10L of the above concentrated solution and add 1L of the filtered alkaline solution containing NaOH to separate out basic magnesium carbonate and Mg(OH) 2 precipitates. The Mg and Ca in the solution are both less than 0.2ppm (ICP-AES inspection limit). pH=12.5. Filter, separate and remove basic magnesium carbonate and Mg(OH) 2 precipitation, and then use a composite extractant formed by mixing Cyanex923 and LIX54 to control the volume ratio of Cyanex923 to LIX54 to 2:1, compared with A/O=1:2, Continuous two-stage countercurrent extraction at room temperature, the extraction rate of Li is 95.4%, and the extraction rate of other impurities such as Na and K is <0.01%. After extraction, load the organic phase and add water to make the volume ratio of organic phase to water 5.5:1, and pass CO 2 gas into the system and stir for 30 minutes. Li is back-extracted to the water phase. The back-extraction rate is 92.2%. The extraction of the organic phase back to Li forms an extraction cycle. The Li stripping solution (aqueous solution of lithium bicarbonate) contains Li in the lithium bicarbonate solution at a concentration of 7.65g/L. The lithium bicarbonate stripping solution is heated to 80°C and kept for 5.0h to obtain 74.9g Li 2 CO 3 . The purity is 99.5%.
实施例3Example 3
一种盐湖卤水，通过盐田蒸发浓缩后得到的卤水主要组成为(g/L)：Li，1.5；Mg，4.8；Na，92；K，4；SO 4 2-，34。 A salt lake brine, the brine obtained by evaporation and concentration from salt fields is mainly composed of (g/L): Li, 1.5; Mg, 4.8; Na, 92; K, 4; SO 4 2- , 34.
取10L浓缩后的老卤，加入实施例2中制备的过滤后的含NaOH的碱溶液0.7L，分别析出碱式碳酸镁和Mg(OH) 2沉淀，溶液中的Mg和Ca均小于0.2ppm(ICP-AES检查限)，pH＝12.3。过滤，分离除去碱式碳酸镁和Mg(OH) 2沉淀,然后采用TBP和LIX84混合形成的复合萃取剂，控制TBP与LIX84的体积比为0.2:1，相比A/O＝1：1，室温下连续两级逆流萃取，Li萃取率为98.4％，Na、K等其它杂质萃取率<0.01％。萃取后负载有机相加入水，使有机相与 水的体积比为5.5：1，并将上述高温煅烧步骤产生的CO 2气体通入体系搅拌30min，Li被反萃到水相，反萃率93.2％，反萃后的有机相返回Li的萃取形成萃取循环。Li的反萃液(碳酸氢锂的水溶液)中含Li浓度为7.52g/L，碳酸氢锂反萃液加热到80℃，并保温6.0h，得到70.2g Li 2CO 3，纯度为99.6％。 Take 10L of concentrated old brine and add 0.7L of the filtered alkaline solution containing NaOH prepared in Example 2 to separate out basic magnesium carbonate and Mg(OH) 2 precipitates. The Mg and Ca in the solution are both less than 0.2ppm (ICP-AES inspection limit), pH=12.3. Filter, separate and remove basic magnesium carbonate and Mg(OH) 2 precipitation, and then use a composite extractant formed by mixing TBP and LIX84 to control the volume ratio of TBP to LIX84 to 0.2:1, compared with A/O=1:1, Continuous two-stage countercurrent extraction at room temperature, the extraction rate of Li is 98.4%, and the extraction rate of other impurities such as Na and K is <0.01%. After extraction, load the organic phase and add water to make the volume ratio of organic phase to water 5.5:1, and pass the CO 2 gas generated in the high-temperature calcination step into the system and stir for 30 minutes. Li is back-extracted to the water phase. The back-extraction rate is 93.2 %, the organic phase after back extraction returns to the extraction of Li to form an extraction cycle. The Li stripping solution (aqueous solution of lithium bicarbonate) contains Li concentration of 7.52g/L. The lithium bicarbonate stripping solution is heated to 80°C and kept for 6.0h to obtain 70.2g Li 2 CO 3 with a purity of 99.6% .
由以上实施例可以看出，本发明提供的萃取法能够从低镁卤水中提锂甚至还可以与吸附法等技术结合起来实现高镁锂比盐湖原卤水的工业化快速提锂，锂的收率高、纯度高，且成本低、材料利用率高。It can be seen from the above examples that the extraction method provided by the present invention can extract lithium from low-magnesium brine and can even be combined with techniques such as adsorption to achieve rapid industrialization of high-magnesium-lithium than salt lake raw brine, and the yield of lithium High, high purity, low cost and high material utilization rate.
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (11)

  1. 一种从含锂低镁卤水中提取锂的方法，其特征在于，包括以下步骤：A method for extracting lithium from lithium-containing low-magnesium brine, which is characterized in that it comprises the following steps:
    (1)将CaO、水和过量Na 2CO 3混合进行反应，将所得反应液过滤得到碱溶液和CaCO 3固体； (1) Mix CaO, water and excess Na 2 CO 3 to react, and filter the resulting reaction solution to obtain an alkali solution and a CaCO 3 solid;
    (2)将所述碱溶液加入含锂低镁卤水中，将所述含锂低镁卤水的pH调节到11以上，析出碱式碳酸镁和Mg(OH) 2沉淀，得到除镁后的含锂卤水； (2) The alkaline solution is added to lithium-containing low-magnesium brine, the pH of the lithium-containing low-magnesium brine is adjusted to 11 or more, and basic magnesium carbonate and Mg(OH) 2 are precipitated to obtain the magnesium-containing brine after removal of magnesium. Lithium brine
    (3)采用复合有机萃取体系萃取所述除镁后的含锂卤水中的锂，得到负载有机相和萃余液；(3) Using a composite organic extraction system to extract lithium in the lithium-containing brine after magnesium removal to obtain a loaded organic phase and raffinate;
    (4)将所述负载有机相与酸性水溶液混合，将负载有机相中的锂反萃到水相，得到含锂的水溶液和脱锂有机相。(4) The loaded organic phase is mixed with the acidic aqueous solution, and the lithium in the loaded organic phase is back-extracted to the aqueous phase to obtain a lithium-containing aqueous solution and a delithiated organic phase.
  2. 根据权利要求1所述的方法，其特征在于，所述含锂低镁卤水中锂的浓度为0.2～2.5g/L，镁的浓度<6g/L。The method according to claim 1, wherein the concentration of lithium in the lithium-containing low-magnesium brine is 0.2-2.5 g/L, and the concentration of magnesium is less than 6 g/L.
  3. 根据权利要求1或2所述的方法，其特征在于，所述步骤(2)中的含锂低镁卤水包括含锂低镁盐湖卤水、盐湖卤水吸附法除杂并浓缩锂后制备的含锂低镁解吸液、盐湖卤水吸附法除杂并浓缩锂后制备的解吸液进一步反渗透得到的含锂低镁浓缩液、盐湖卤水通过一价离子选择性电渗析处理获得的含锂低镁电渗析浓缩液、盐湖卤水通过纳滤除镁处理获得的含锂低镁纳滤溶液、高镁卤水加入碳酸钠或碳酸氢钠除镁后获得的含锂低镁卤水、地下卤水、沉锂母液、锂电池废料浸出液和锂矿石浸出液中的任意一种或几种。The method according to claim 1 or 2, wherein the lithium-containing low-magnesium brine in the step (2) comprises lithium-containing low-magnesium salt lake brine, and lithium-containing brine prepared by removing impurities from salt lake brine and concentrating lithium. Lithium-containing low-magnesium concentrate obtained by low-magnesium desorption solution and salt lake brine adsorption method to remove impurities and concentrate lithium. Lithium-containing low-magnesium concentrate obtained by reverse osmosis, salt lake brine through monovalent ion selective electrodialysis treatment Concentrate, salt lake brine, lithium-containing low-magnesium nanofiltration solution obtained by the treatment of magnesium removal by nanofiltration, high-magnesium brine, lithium-containing low-magnesium brine obtained after adding sodium carbonate or sodium bicarbonate to remove magnesium, underground brine, lithium precipitation mother liquor, lithium Any one or more of battery waste leaching solution and lithium ore leaching solution.
  4. 根据权利要求1所述的方法，其特征在于，所述步骤(1)中Na 2CO 3的加入量相比按照与CaO化学反应计算的理论加入量过量5～100％。 The method according to claim 1, wherein the addition amount of Na 2 CO 3 in the step (1) is 5-100% more than the theoretical addition amount calculated according to the chemical reaction with CaO.
  5. 根据权利要求1所述的方法，其特征在于，所述步骤(3)中的复合有机萃取体系包括中性萃取剂和螯合萃取剂；The method according to claim 1, wherein the composite organic extraction system in step (3) comprises a neutral extractant and a chelating extractant;
    所述中性萃取剂为磷酸三丁酯TBP、甲基磷酸二甲庚酯P350、三辛基氧化膦TOPO、三辛基/已基氧化膦Cyanex923和N,N二-(1-甲基庚基)乙酰胺N503中的任意一种或几种；The neutral extractant is tributyl phosphate TBP, dimethyl heptyl methyl phosphate P350, trioctyl phosphine oxide TOPO, trioctyl/hexyl phosphine oxide Cyanex 923 and N,N two-(1-methylheptyl) Group) any one or more of acetamide N503;
    所述螯合萃取剂为2-羟基-5-壬基苯乙酮肟LIX84、十二烷基苯基-甲基-β-二酮LIX54和2-羟基-5-壬基苯甲醛肟LIX860中的任意一种或几种。The chelating extractant is 2-hydroxy-5-nonylacetophenone oxime LIX84, dodecylphenyl-methyl-β-diketone LIX54 and 2-hydroxy-5-nonylbenzaldehyde oxime LIX860 Any one or more of.
  6. 根据权利要求1所述的方法，其特征在于，所述步骤(4)中的酸性水溶液为碳酸、磷酸、硝酸、醋酸、柠檬酸、盐酸或硫酸。The method according to claim 1, wherein the acidic aqueous solution in the step (4) is carbonic acid, phosphoric acid, nitric acid, acetic acid, citric acid, hydrochloric acid or sulfuric acid.
  7. 根据权利要求1所述的方法，其特征在于，所述步骤(4)得到的脱锂有机相作为步骤(3)中的复合有机萃取体系。The method according to claim 1, wherein the delithiated organic phase obtained in step (4) is used as the composite organic extraction system in step (3).
  8. 根据权利要求1所述的方法，其特征在于，所述步骤(1)中得到CaCO 3固体后，还包括对所述CaCO 3固体进行煅烧，得到再生CaO和CO 2。 The method according to claim 1, characterized in that, after the CaCO 3 solid is obtained in the step (1), it further comprises calcining the CaCO 3 solid to obtain regenerated CaO and CO 2 .
  9. 根据权利要求8所述的方法，其特征在于，还包括：将所述再生CaO用于步骤(1)的反应；所述CO 2用于制备步骤(4)中的酸性水溶液或通入步骤(3)中的萃余液中调节所述萃余液的pH值，使萃余液能够排放。 The method according to claim 8, characterized in that it further comprises: using the regenerated CaO for the reaction of step (1); and using the CO 2 for preparing the acidic aqueous solution in step (4) or introducing step ( 3) Adjust the pH value of the raffinate in the raffinate so that the raffinate can be discharged.
  10. 根据权利要求8所述的方法，其特征在于，所述CO 2通入步骤(3)的萃余液中制备出碳酸氢钠；由所述碳酸氢钠制备碳酸钠，制备到的碳酸钠用作步骤(1)的反应原料。 The method according to claim 8, wherein the CO 2 is passed into the raffinate of step (3) to prepare sodium bicarbonate; sodium carbonate is prepared from the sodium bicarbonate, and the prepared sodium carbonate is used As the reaction material of step (1).
  11. 根据权利要求10所述的方法，其特征在于，制备得到的碳酸氢钠或碳酸钠用于高镁卤水的除镁。The method according to claim 10, wherein the prepared sodium bicarbonate or sodium carbonate is used for removing magnesium from high-magnesium brine.
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