CN108118143B - Method for preparing lithium carbonate by extracting lithium from lepidolite through two-stage chlorination roasting-alkali liquor leaching method - Google Patents

Method for preparing lithium carbonate by extracting lithium from lepidolite through two-stage chlorination roasting-alkali liquor leaching method Download PDF

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CN108118143B
CN108118143B CN201711443400.XA CN201711443400A CN108118143B CN 108118143 B CN108118143 B CN 108118143B CN 201711443400 A CN201711443400 A CN 201711443400A CN 108118143 B CN108118143 B CN 108118143B
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roasting
lepidolite
carbonate
lithium
leaching
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CN108118143A (en
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王接喜
肖晓
李新海
王志兴
郭华军
颜果春
胡启阳
彭文杰
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Central South University
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00Preliminary treatment of ores or scrap
    • C22B1/02Roasting processes
    • C22B1/08Chloridising roasting
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00Preliminary treatment of ores or scrap
    • C22B1/14Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24Binding; Briquetting ; Granulating
    • C22B1/2406Binding; Briquetting ; Granulating pelletizing
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10Obtaining alkali metals
    • C22B26/12Obtaining lithium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/44Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
    • C22B3/46Treatment or purification of solutions, e.g. obtained by leaching by chemical processes by substitution, e.g. by cementation
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/20Recycling

Abstract

The invention discloses a method for preparing lithium carbonate by extracting lithium from lepidolite through a two-stage chlorination roasting-alkali liquor leaching method, which comprises the following steps: (1) grinding lepidolite ore and calcium chloride, adding the ground lepidolite ore and calcium chloride into ammonium chloride solution, mixing uniformly, and pelletizing to obtain green pellets; (2) performing primary roasting on the green pellets obtained in the step (1) at the temperature of 150-; (3) leaching the clinker obtained in the step (2) with water, and filtering to obtain a leaching solution; (4) and (4) adding a carbonate solution into the leaching solution obtained in the step (3), stirring and filtering to obtain mother liquor and filter residues, and collecting the filter residues to obtain lithium carbonate. The steps of the invention are mutually matched and cooperate, and the process of extracting lithium from lepidolite to prepare lithium carbonate is environment-friendly, low in energy consumption, low in cost and high in extraction efficiency, and has wide industrial application prospect.

Description

Method for preparing lithium carbonate by extracting lithium from lepidolite through two-stage chlorination roasting-alkali liquor leaching method
Technical Field
The invention belongs to the field of metallurgy, and particularly relates to a method for preparing lithium carbonate by extracting lithium from lepidolite.
Background
As a new energy and strategic resource, lithium is known as "energy metal promoting world progress", which is widely used in various fields of national economy. Lithium metal plays an important role in the traditional consumption fields such as glass, ceramics, lubricants and the like, and promotes the development of high and new technical fields such as lithium batteries, nuclear energy, aerospace and the like. Fast energy storage device, especially in new energy automobile industry, wearable device and large-scale energy storage deviceWith rapid development, the demand for lithium in the global market is increasing year by year. China has rich lepidolite resources, Li thereof2The O content is generally around 4%. At present, the method for extracting lithium from lepidolite mainly comprises a limestone method, an autoclave method, a sulfuric acid method, a one-step chlorination roasting method and the like.
The limestone method is used for preparing lithium salt from lepidolite, and the lepidolite and limestone are crushed according to the weight ratio of 1: 3, performing mixed grinding in a ball mill in proportion, blending qualified raw slurry, then calcining in a rotary kiln, wherein the calcining temperature is 900-1100 ℃, and performing water quenching, fine grinding, leaching, filtering or settling separation and other processes on clinker to obtain leachate and residue. The lithium hydroxide can be obtained by evaporating, crystallizing and centrifugally separating the leaching solution. But the method has the advantages of large material flow in the production process, generation of a large amount of waste residues, high calcination temperature, long period, high energy consumption, low lithium recovery rate, high production cost when treating low-grade lepidolite ore and difficulty in large-scale production.
The sulfuric acid method mainly comprises the steps of roasting lepidolite concentrate and concentrated sulfuric acid at the temperature of 150-300 ℃, roasting the roasted product at the temperature of 800 ℃ for the second time, soaking the secondary roasted product in water, filtering, and adding sodium hydroxide into filtrate to remove aluminum. The Hunan metallurgy institute firstly removes fluorine from Jiangxi lepidolite through steam roasting, and then extracts lithium from the lepidolite by adopting a sulfuric acid method, wherein the leaching rate of lithium reaches more than 92 percent, and the recovery rate of lithium is about 82 percent. But the method can generate a large amount of sulfuric acid smoke in the roasting process, can pollute the atmosphere, has higher requirement on acid corrosion resistance of equipment, and simultaneously needs to add a large amount of alkali liquor to adjust the pH value in the process of removing aluminum from the leaching solution, so that the residual acid is difficult to recycle and is not economically dominant.
The pressure boiling method is characterized in that the powdered lepidolite concentrate and lime milk are mixed according to a mass ratio of 1: 1.6 compounding, autoclaving at 240 ℃ for 3h, Li2The leaching rate of O can reach more than 95 percent. Wangxiangxi adopts a new process of slaked lime and soda combined pressure cooking to process Lichun lepidolite, the influence of slaked lime dosage, soda dosage, reaction temperature and reaction time on the dissolution behavior of elements such as lithium, potassium, aluminum, silicon, fluorine and the like in the pressure cooking dissolution process is investigated, and the result shows that under the optimal process conditions (calcine:Ca(OH)2:Na2CO3=10:9:2,140℃,3h),Li2the dissolution rate of O is more than 92 percent. However, this method needs to perform calcination transformation and defluorination on lepidolite in advance, so as to prevent the reaction of water vapor and fluorine in lepidolite during autoclaving from generating hydrogen fluoride gas, which causes environmental pollution and corrosion to equipment. Meanwhile, the pressure is high during autoclaving, the high-pressure leaching equipment is high in manufacturing cost, and the autoclave is easy to scar and difficult to separate and wash.
The chloridizing roasting method is a lithium extraction method for converting lithium in lithium ore into lithium chloride through chloridizing roasting, and valuable elements such as potassium, rivet, cesium and the like in the lithium ore are simultaneously converted into chloride during roasting to obtain comprehensive extraction. The method for extracting lithium by the chlorination roasting method has the advantages of short flow, high metal recovery rate, high equipment production capacity, suitability for treating low-grade lithium ores and the like, and has better development prospect. Pacific and brilliant Pacific lepidolite, NaCl and NaCl-CaCl2The experimental results show that the reaction temperature is 800 ℃, the ratio of ore to alkali is 1: the decomposition rate of lithium, rivet and cesium in the lepidolite ore is more than 80% at 1 hour. The Wushifei and the like directly treat the lepidolite with chlorine gas and calcine the lepidolite for 3 hours at 800 ℃, and the extraction rate of lithium can reach 92.49 percent; and (2) carrying out chlorine chlorination roasting on the lepidolite and the calcium oxide in a mass ratio of 1:0.7 for 0.5h, wherein the roasting temperature is 900 ℃, and the extraction rate of lithium is 92.5%. However, the chlorination roasting method has large dosage of chlorinating agent, excessive HCl gas is generated in the chlorination roasting process, the equipment is greatly corroded, the environment pollution is caused, the chlorination roasting temperature is above 800 ℃, and the energy consumption is high.
Therefore, the method for preparing the lithium carbonate by extracting the lithium from the lepidolite is green and environment-friendly, low in energy consumption, low in cost and high in extraction efficiency, and has important significance for the development of the lithium industry in China.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects and defects mentioned in the background technology, and provide a method for preparing lithium carbonate by extracting lithium from lepidolite, which is green and environment-friendly, low in energy consumption, low in cost and high in extraction efficiency. In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a method for extracting lithium from lepidolite to prepare lithium carbonate by a two-stage chloridizing roasting-alkali liquor leaching method comprises the following steps:
(1) grinding lepidolite ore and calcium chloride, adding the ground lepidolite ore and calcium chloride into ammonium chloride solution, mixing uniformly, and pelletizing to obtain green pellets;
(2) performing primary roasting on the green pellets obtained in the step (1) at a low temperature, and performing secondary roasting at a high temperature to obtain clinker;
(3) leaching the clinker obtained in the step (2) by using water (preferably clear water), and filtering to obtain a leaching solution;
(4) adding carbonate solution into the leachate obtained in the step (3), stirring and filtering to obtain mother liquor (solution containing potassium, sodium, rubidium, cesium and the like) and filter residue (mainly lithium carbonate), and collecting the filter residue to obtain lithium carbonate.
The traditional chloridizing roasting is only provided with CaCl2Or NaCl is subjected to chlorination roasting, and the reaction is solid-solid reaction, so that the improvement of the reaction speed is not facilitated, the energy consumption is high, the equipment utilization rate is low, and the reaction is difficult to carry out completely. In the invention, ammonium chloride solution is used for wetting and pelletizing in the step (1), so that the melting point of the whole reactant system is reduced, and a gas phase and a liquid phase are increased, the chlorination roasting reaction in the step (2) is converted from a solid-solid two-phase reaction to a solid-liquid-gas three-phase reaction, and the reaction kinetics of the reaction system is obviously improved. On the other hand, the ammonium chloride can be decomposed to generate hydrogen chloride for pre-chlorinating the ore sample during roasting, so that the chlorination roasting temperature and the roasting period in the whole chlorination process are reduced, and meanwhile, the hydrogen chloride is consumed during chlorination roasting, so that the concentration of the hydrogen chloride in the chlorination stage can be reduced, and the corrosion of excessive hydrogen chloride to production equipment is reduced.
In the invention, two-stage roasting is adopted, wherein the main effect of the first-stage roasting is to decompose ammonium chloride, and the generated hydrogen chloride pre-chlorinates lepidolite (the hydrogen chloride and alkali metal components in the material generate soluble chloride); the secondary roasting mainly has the functions of completing the chlorination of mineral aggregates and the recovery of redundant ammonium chloride and ammonia gas.
In the method for preparing lithium carbonate by extracting lithium from lepidolite through the two-stage chlorination roasting-alkali liquor leaching method, the mass ratio of the lepidolite ore, calcium chloride and ammonium chloride is preferably 1:0.5: 0.3-0.5.
In the method for preparing lithium carbonate by extracting lithium from lepidolite through the two-stage chlorination roasting-alkali liquor leaching method, the particle size of the green ball is preferably 5-20 mm.
In the method for preparing lithium carbonate by extracting lithium from lepidolite through the two-stage chlorination roasting-alkali liquor leaching method, the preferable time of the one-stage roasting is 0.5-1.5h, and the temperature is 150-300 ℃; the time of the second-stage roasting is 1.5-2.5h, and the temperature is 500-800 ℃. The determination of the roasting time is related to the material proportion, and can be determined according to different material proportions in the actual operation process.
In the method for preparing lithium carbonate by extracting lithium from lepidolite through the two-stage chloridizing roasting-alkali liquor leaching method, preferably, the leaching time of leaching the clinker with water is 10-90min, the leaching temperature is 5-90 ℃, and the liquid-solid ratio is controlled to be 1:1-10: 1.
In the method for preparing lithium carbonate by extracting lithium from lepidolite through the two-stage chlorination roasting-alkali liquor leaching method, preferably, the carbonate solution is one or two of sodium carbonate and potassium carbonate, and the mass of the carbonate solution is 110-130% of the theoretical carbonate solution required by converting lithium in lepidolite ore into lithium carbonate.
In the method for preparing lithium carbonate by extracting lithium from lepidolite through the two-stage chlorination roasting-alkali liquor leaching method, the preferable stirring time is controlled to be 1-2.5 hours after the carbonate solution is added.
In the method for preparing lithium carbonate by extracting lithium from lepidolite through the two-stage chlorination roasting-alkali liquor leaching method, preferably, CO is introduced into the mother liquor2Acidifying to obtain acidified liquid, heating and evaporating the concentrated acidified liquid by using furnace gas waste heat in the first-stage roasting and the second-stage roasting, and cooling and crystallizing to separate out carbonate which is used for preparing the carbonate solution in the step (4). Introducing CO into the mother liquor obtained after filtration2Acidification is carried out, and indirect evaporation and concentration are carried out by utilizing the waste heat of the roasting furnace gas, so that the waste heat utilization rate of the roasting furnace gas can be obviously improved. The mother liquor crystallizes on cooling to precipitate carbonate, whichPart of the auxiliary materials can be used for the auxiliary materials of the leaching section, so that the quality of carbonate solution for leaching can be reduced, and the rest part of the auxiliary materials can be used as carbonate byproducts. In addition, the mother liquor left after cooling can be used as raw materials for preparing rubidium cesium salt after extracting sodium and potassium.
In the above two-stage chloridizing roasting-alkali liquor leaching method for preparing lithium carbonate by extracting lithium from lepidolite, preferably, ammonia gas in furnace gas during roasting is recovered by a dilute hydrochloric acid wet method to obtain an ammonium chloride solution, and unreacted ammonium chloride is recovered by a dry method and is used for preparing the ammonium chloride solution in the step (1). The process can reduce the dosage of ammonium chloride in the whole chlorination stage, and can reduce the pollution of furnace gas generated during roasting to the environment while reducing the production cost.
In the method for preparing lithium carbonate by extracting lithium from lepidolite through the two-stage chlorination roasting-alkali liquor leaching method, the first-stage roasting and the second-stage roasting are preferably carried out in the same roasting furnace or two roasting furnaces connected in series.
Compared with the prior art, the invention has the advantages that:
1. when raw pellets are prepared by ingredients, the ammonium chloride solution is used for wetting and pelletizing, so that the melting point of the whole system can be reduced, the gas phase and the liquid phase are increased, the chlorination roasting reaction is forwarded to the solid-liquid-gas three-phase reaction from the solid-solid two-phase reaction, the reaction kinetics of the system is obviously improved, the temperature required during roasting is lower, and the energy consumption is less.
2. The invention adopts two-stage roasting process during roasting, ammonium chloride is decomposed to generate hydrogen chloride during the first-stage low-temperature roasting, and the hydrogen chloride and alkali metal components in the material generate soluble chloride, so that the raw material can be pre-chlorinated, and the energy consumption during the second-stage high-temperature roasting can be reduced.
3. According to the invention, water is used for leaching after roasting, calcium ions can be separated from a solution system by using silicate, aluminate, meta-aluminate and the like in the lepidolite ore, the purity of lithium carbonate obtained in the subsequent steps is higher, and the steps of separating and purifying lithium carbonate can be greatly reduced.
4. The leachate is precipitated and separated by using a carbonate solution, so that the introduction of new impurities is avoided, and the purification load is low. Meanwhile, the pH is adjusted without adding acid and alkali in the whole leaching process, the impurity content is low, and the purification and separation process is simple.
5. The chlorinating agents selected by the invention are ammonium chloride and calcium chloride, the amount of slag after chloridizing roasting is small, the concentration of lithium ions in the leaching solution is high, no further concentration is needed in the lithium extraction process, and the recovery rate of the lithium ions is high.
6. The steps of the invention are mutually matched and cooperate, and the process of extracting lithium from lepidolite to prepare lithium carbonate is environment-friendly, low in energy consumption, low in cost and high in extraction efficiency, and has wide industrial application prospect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic process flow diagram of an embodiment of the present invention.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Example 1:
as shown in fig. 1, a two-stage chloridizing roasting-alkali liquor leaching method for extracting lithium from lepidolite to prepare lithium carbonate comprises the following steps:
(1) mixing Li2Grinding and mixing lepidolite ore with the O content of 3.8% and calcium chloride according to the mass ratio of 1:0.5, wetting and pelletizing by using a certain mass of ammonium chloride solution to obtain raw pellets with the particle size of 15mm (if the raw pellets need to be dried, the waste heat of a roasting section can be used, the drying of the raw pellets can reduce part of water, the energy loss of subsequent chlorination treatment is reduced, water is added for multiple times in the general pelletizing process, the control is carried out according to the principle that water is reduced when the pellets are large and water is added when the pellets are small), and the mass ratio of ammonium chloride to the lepidolite ore is controlled to be 0.3: 1;
(2) roasting the green pellets obtained in the step (1) at 150 ℃ for 1h for the first time, and then roasting the green pellets at 600 ℃ for the second time for 1.5h to obtain clinker (which can be carried out in the same roasting furnace or two roasting furnaces connected in series), wherein ammonia in furnace gas is recovered by a dilute hydrochloric acid solution wet method during roasting to obtain ammonium chloride, and the excess unreacted ammonium chloride is recovered by a dry method and used for preparing an ammonium chloride solution in the step (1);
(3) directly leaching the clinker obtained in the step (2) with clear water, filtering to obtain a leaching solution, controlling the leaching temperature to be 10 ℃, leaching for 60min, wherein the liquid-solid ratio is 3:1, the leaching process can be finished by one or more times of cross flow, and leaching residues are discarded after washing;
(4) adding the leachate obtained in the step (3) into a sodium carbonate and potassium carbonate mixed solution, stirring and leaching for 1.5 hours, controlling the sum of the total amount of sodium carbonate and potassium carbonate to be more than 120% of the theoretical amount required for converting lithium in the lepidolite ore into lithium carbonate, filtering to obtain mother liquor containing potassium, sodium, rubidium, cesium and the like and lithium carbonate filter residue, and collecting the filter residue to obtain lithium carbonate;
(5) introducing CO into the mother liquor obtained in the step (4)2Acidifying, indirectly evaporating and concentrating by using the waste heat of roasting furnace gas, cooling and crystallizing to separate out sodium carbonate and potassium carbonate mixed salt, wherein one part of the mixed salt is used for preparing the sodium carbonate and potassium carbonate mixed solution, the other part of the mixed salt can be used as a byproduct of the sodium carbonate and the potassium carbonate, and the mother liquor after sodium and potassium extraction can be used for preparing rubidium cesium salt.
The lithium recovery in this example was determined to be 95.7% greater.
Example 2:
a method for extracting lithium from lepidolite to prepare lithium carbonate by a two-stage chloridizing roasting-alkali liquor leaching method comprises the following steps:
(1) mixing Li2Grinding and mixing lepidolite ore with the O content of 4.5% and calcium chloride according to the mass ratio of 1:0.5, wetting and pelletizing by using a certain mass of ammonium chloride solution to obtain raw pellets with the particle size of 10mm (if the raw pellets need to be dried, the waste heat of a roasting section can be used, the drying of the raw pellets can reduce part of water and the energy loss of subsequent chlorination treatment, water is added for multiple times in the general pelletizing process, and the mass ratio of the ammonium chloride to the lepidolite ore is controlled to be 0.5:1 according to the principle that water is reduced when the pellets are large and water is added when the pellets are small);
(2) carrying out primary roasting on the green pellets obtained in the step (1) at 200 ℃ for 0.5h, and then carrying out secondary roasting at 650 ℃ for 2.5h to obtain clinker (which can be carried out in the same roasting furnace or two roasting furnaces connected in series), wherein ammonia gas in furnace gas is recovered by a dilute hydrochloric acid solution wet method during roasting to obtain ammonium chloride, and the excess unreacted ammonium chloride is recovered by a dry method and is used for preparing an ammonium chloride solution in the step (1);
(3) directly leaching the clinker obtained in the step (2) with clear water, filtering to obtain a leaching solution, controlling the leaching temperature to be 90 ℃, leaching for 30min, wherein the liquid-solid ratio is 10:1, the leaching process can be finished by one or more times of cross flow, and leaching residues are discarded after washing;
(4) adding the leachate obtained in the step (3) into a sodium carbonate and potassium carbonate mixed solution, stirring and leaching for 2.0 hours, controlling the sum of the total amount of sodium carbonate and potassium carbonate to be more than 130% of the theoretical amount required for converting lithium in the lepidolite ore into lithium carbonate, filtering to obtain mother liquor containing potassium, sodium, rubidium, cesium and the like and lithium carbonate filter residue, and collecting the filter residue to obtain lithium carbonate;
(5) introducing CO into the mother liquor obtained in the step (4)2Acidifying, indirectly evaporating and concentrating by using the waste heat of roasting furnace gas, cooling and crystallizing to separate out sodium carbonate and potassium carbonate mixed salt, wherein one part of the mixed salt is used for preparing the sodium carbonate and potassium carbonate mixed solution, the other part of the mixed salt can be used as a byproduct of the sodium carbonate and the potassium carbonate, and the mother liquor after sodium and potassium extraction can be used for preparing rubidium cesium salt.
The recovery rate of lithium in this example was determined to be 97.8% greater.
Example 3:
a method for extracting lithium from lepidolite to prepare lithium carbonate by a two-stage chloridizing roasting-alkali liquor leaching method comprises the following steps:
(1) mixing Li2Grinding and mixing lepidolite ore with the O content of 4.3% and calcium chloride according to the mass ratio of 1:0.5, wetting and pelletizing by using a certain mass of ammonium chloride solution to obtain raw pellets with the particle size of 10mm (if the raw pellets need to be dried, the waste heat of a roasting section can be used, the drying of the raw pellets can reduce part of water and the energy loss of subsequent chlorination treatment, water is added for multiple times in the general pelletizing process, and the mass ratio of the ammonium chloride to the lepidolite ore is controlled to be 0.4:1 according to the principle that water is reduced when the pellets are large and water is added when the pellets are small);
(2) carrying out primary roasting on the green pellets obtained in the step (1) at 250 ℃ for 0.5h, and then carrying out secondary roasting at 550 ℃ for 1.5h to obtain clinker (which can be carried out in the same roasting furnace or two roasting furnaces connected in series), wherein ammonia gas in furnace gas is recovered by a dilute hydrochloric acid solution wet method during roasting to obtain ammonium chloride, and the excess unreacted ammonium chloride is recovered by a dry method and is used for preparing an ammonium chloride solution in the step (1);
(3) directly leaching the clinker obtained in the step (2) with clear water, filtering to obtain a leaching solution, controlling the leaching temperature to be 50 ℃, leaching for 50min, wherein the liquid-solid ratio is 1:1, the leaching process can be finished by one or more times of cross flow, and leaching residues are discarded after washing;
(4) adding the leachate obtained in the step (3) into a sodium carbonate and potassium carbonate mixed solution, stirring and leaching for 2.5 hours, controlling the sum of the total amount of sodium carbonate and potassium carbonate to be more than 120% of the theoretical amount required for converting lithium in the lepidolite ore into lithium carbonate, filtering to obtain mother liquor containing potassium, sodium, rubidium, cesium and the like and lithium carbonate filter residue, and collecting the filter residue to obtain lithium carbonate;
(5) introducing CO into the mother liquor obtained in the step (4)2Acidifying, indirectly evaporating and concentrating by using the waste heat of roasting furnace gas, cooling and crystallizing to separate out sodium carbonate and potassium carbonate mixed salt, wherein one part is used for preparing sodium carbonate and potassium carbonate mixed solution, and the rest can be used as carbonic acidSodium and potassium carbonate byproducts, and mother liquor obtained after sodium and potassium extraction can be used for preparing rubidium and cesium salt.
The lithium recovery in this example was determined to be 95.8% greater.
Example 4:
a method for extracting lithium from lepidolite to prepare lithium carbonate by a two-stage chloridizing roasting-alkali liquor leaching method comprises the following steps:
(1) mixing Li2Grinding and mixing lepidolite ore with the O content of 3.5% and calcium chloride according to the mass ratio of 1:0.5, wetting and pelletizing by using a certain mass of ammonium chloride solution to obtain raw pellets with the particle size of 10mm (if the raw pellets need to be dried, the waste heat of a roasting section can be used, the drying of the raw pellets can reduce part of water and the energy loss of subsequent chlorination treatment, water is added for multiple times in the general pelletizing process, and the mass ratio of ammonium chloride to lepidolite ore is controlled to be 0.3:1 according to the principle that water is reduced when the pellets are large and water is added when the pellets are small);
(2) carrying out primary roasting on the green pellets obtained in the step (1) at 300 ℃ for 0.5h, and then carrying out secondary roasting at 800 ℃ for 1h to obtain clinker (which can be carried out in the same roasting furnace or two roasting furnaces connected in series), wherein ammonia in furnace gas is recovered by a dilute hydrochloric acid solution wet method during roasting to obtain ammonium chloride, and the excess unreacted ammonium chloride is recovered by a dry method and is used for preparing an ammonium chloride solution in the step (1);
(3) directly leaching the clinker obtained in the step (2) with clear water, filtering to obtain a leaching solution, controlling the leaching temperature to be 60 ℃, leaching for 90min, wherein the liquid-solid ratio is 6:1, the leaching process can be finished by one or more times of cross flow, and leaching residues are discarded after washing;
(4) adding the leachate obtained in the step (3) into a sodium carbonate and potassium carbonate mixed solution, stirring and leaching for 1.0h, controlling the sum of the total amount of sodium carbonate and potassium carbonate to be more than 120% of the theoretical amount required for converting lithium in the lepidolite ore into lithium carbonate, filtering to obtain mother liquor containing potassium, sodium, rubidium, cesium and the like and lithium carbonate filter residue, and collecting the filter residue to obtain lithium carbonate;
(5) introducing CO into the mother liquor obtained in the step (4)2Acidifying, indirectly evaporating and concentrating by using the afterheat of roasting furnace gas, cooling, crystallizing and separating out sodium carbonate and carbonic acidAnd (3) potassium mixed salt, wherein one part of the potassium mixed salt is used for preparing a sodium carbonate and potassium carbonate mixed solution, the other part of the potassium mixed salt can be used as a sodium carbonate and potassium carbonate byproduct, and the mother liquor after sodium and potassium extraction can be used for preparing rubidium cesium salt.
The lithium recovery rate in this example was determined to be 96.5% greater.
Example 5:
a method for extracting lithium from lepidolite to prepare lithium carbonate by a two-stage chloridizing roasting-alkali liquor leaching method comprises the following steps:
(1) mixing Li2Grinding and mixing lepidolite ore with the O content of 3.0% and calcium chloride according to the mass ratio of 1:0.3, wetting and pelletizing by using a certain mass of ammonium chloride solution to obtain raw pellets with the particle size of 20mm (if the raw pellets need to be dried, the waste heat of a roasting section can be used, the drying of the raw pellets can reduce part of water, the energy loss of subsequent chlorination treatment is reduced, water is added for multiple times in the general pelletizing process, the control is carried out according to the principle that water is reduced when the pellets are large and water is added when the pellets are small), and the mass ratio of ammonium chloride to the lepidolite ore is controlled to be 0.35: 1;
(2) roasting the green pellets obtained in the step (1) at 150 ℃ for 1.5h for the first time, and then roasting the green pellets at 700 ℃ for the second time for 1h to obtain clinker (which can be carried out in the same roasting furnace or two roasting furnaces connected in series), wherein ammonia in furnace gas is recovered by a dilute hydrochloric acid solution wet method during roasting to obtain ammonium chloride, and the excess unreacted ammonium chloride is recovered by a dry method and used for preparing an ammonium chloride solution in the step (1);
(3) directly leaching the clinker obtained in the step (2) with clear water, filtering to obtain a leaching solution, controlling the leaching temperature to be 40 ℃, leaching for 60min, wherein the liquid-solid ratio is 2:1, the leaching process can be finished by one or more times of cross flow, and leaching residues are discarded after washing;
(4) adding the leachate obtained in the step (3) into a sodium carbonate and potassium carbonate mixed solution, stirring and leaching for 1.5 hours, controlling the sum of the total amount of sodium carbonate and potassium carbonate to be more than 115% of the theoretical amount required for converting lithium in the lepidolite ore into lithium carbonate, filtering to obtain mother liquor containing potassium, sodium, rubidium, cesium and the like and lithium carbonate filter residue, and collecting the filter residue to obtain lithium carbonate;
(5) introducing the mother liquor obtained in the step (4)CO2Acidifying, indirectly evaporating and concentrating by using the waste heat of roasting furnace gas, cooling and crystallizing to separate out sodium carbonate and potassium carbonate mixed salt, wherein one part of the mixed salt is used for preparing the sodium carbonate and potassium carbonate mixed solution, the other part of the mixed salt can be used as a byproduct of the sodium carbonate and the potassium carbonate, and the mother liquor after sodium and potassium extraction can be used for preparing rubidium cesium salt.
The lithium recovery in this example was determined to be 95.5% greater.

Claims (6)

1. A method for extracting lithium from lepidolite to prepare lithium carbonate by a two-stage chloridizing roasting-alkali liquor leaching method is characterized by comprising the following steps:
(1) grinding lepidolite ore and calcium chloride, adding the ground lepidolite ore and calcium chloride into ammonium chloride solution, mixing uniformly, and pelletizing to obtain green pellets; wherein the mass ratio of the lepidolite ore to the calcium chloride to the ammonium chloride is 1:0.5: 0.3-0.5;
(2) performing primary roasting on the green pellets obtained in the step (1) at a low temperature, and performing secondary roasting at a high temperature to obtain clinker; the time for the first-stage roasting is 0.5h, and the temperature is 250 ℃; the time of the second-stage roasting is 1.5h, and the temperature is 550 ℃;
(3) leaching the clinker obtained in the step (2) with water, and filtering to obtain a leaching solution;
(4) adding a carbonate solution into the leachate obtained in the step (3), stirring and filtering to obtain a mother solution and filter residues, and collecting the filter residues to obtain lithium carbonate;
introducing CO into the mother liquor2Acidifying to obtain an acidified solution, heating and evaporating the concentrated acidified solution by using furnace gas waste heat in the first-stage roasting and the second-stage roasting, and cooling and crystallizing to separate out carbonate for preparing the carbonate solution in the step (4);
and (2) recovering ammonia gas in the furnace gas during roasting by a dilute hydrochloric acid wet method to obtain an ammonium chloride solution, and recovering unreacted ammonium chloride by a dry method and using the unreacted ammonium chloride to prepare the ammonium chloride solution in the step (1).
2. The two-stage chloridizing roasting-alkali liquor leaching method for extracting lithium from lepidolite to prepare lithium carbonate according to claim 1, wherein the particle size of the green pellets is 5-20 mm.
3. The method for preparing lithium carbonate by extracting lithium from lepidolite through the two-stage chloridizing roasting-alkali liquor leaching method according to claim 1 or 2, wherein the leaching time of the clinker by using water is 10-90min, the leaching temperature is 5-90 ℃, and the liquid-solid ratio is controlled to be 1:1-10: 1.
4. The two-stage chloridizing roasting-alkali liquor leaching method for extracting lithium from lepidolite to prepare lithium carbonate according to claim 1 or 2, wherein the carbonate solution is one or two of sodium carbonate and potassium carbonate, and the mass of the carbonate solution is 110% -130% of the theoretical carbonate solution required by lithium in the lepidolite ore to be converted into lithium carbonate.
5. The method for preparing lithium carbonate by extracting lithium from lepidolite through two-stage chloridizing roasting-alkali liquor leaching according to claim 1 or 2, wherein the stirring time is controlled to be 1-2.5 hours after the carbonate solution is added.
6. The two-stage chloridizing roasting-alkali liquor leaching method for extracting lithium from lepidolite to prepare lithium carbonate according to claim 1 or 2, characterized in that the first-stage roasting and the second-stage roasting are carried out in the same roasting furnace or in two roasting furnaces connected in series.
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CN102337399A (en) * 2011-11-21 2012-02-01 江西省科学院应用化学研究所 Method for extracting lithium by processing lepidolite through alkali dissolution process
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