阅读说明：本技术 锂精矿焙烧料先分离再经酸化或碱化制备锂盐的方法 (Method for preparing lithium salt by first separating lithium concentrate roasted material and then acidifying or alkalizing lithium concentrate roasted material ) 是由 李放来 范钦芳 刘建林 于 2021-06-04 设计创作，主要内容包括：本发明涉及新能源锂材料技术领域,具体涉及锂精矿焙烧料先分离再经酸化或碱化制备锂盐的方法。锂辉石矿经焙烧、分散、分离后,再进行酸化或碱化反应制备锂盐；分散是通过机械研磨、高速搅拌或气流粉碎,将焙烧料分散为150目以下的细粉料和150目以上的粗粉料,细粉料即为锂盐生产用β型锂精矿粉；所述粗粉料即为含锂长石粉；分离是将细粉料和粗粉料分开,只将150目以下的细粉料进行酸化或碱化反应制备锂盐,而150目以上的粗粉料则作为副产物另作他用。本发明使焙烧料中65％的含锂长石粉分离出来,不再参加酸化或碱化反应,节省了大量的费用,而离出的β型锂精石粉品位提升,细度150目以上,锂金属回收率达85％以上。(The invention relates to the technical field of new energy lithium materials, in particular to a method for preparing lithium salt by firstly separating a lithium concentrate roasted material and then acidifying or alkalifying the lithium concentrate roasted material. Roasting, dispersing and separating the spodumene ore, and then carrying out acidification or alkalization reaction to prepare lithium salt; the dispersion is that the roasted material is dispersed into fine powder below 150 meshes and coarse powder above 150 meshes by mechanical grinding, high-speed stirring or jet milling, and the fine powder is beta type lithium concentrate powder for producing lithium salt; the coarse powder is lithium-containing feldspar powder; the separation is to separate the fine powder from the coarse powder, only the fine powder below 150 meshes is subjected to acidification or alkalization reaction to prepare lithium salt, and the coarse powder above 150 meshes is used as a byproduct for other purposes. The invention separates 65% lithium-containing feldspar powder in the roasting material, does not participate in acidification or alkalization reaction, saves a large amount of cost, improves the grade of the separated beta-type lithium concentrate powder, has the fineness of more than 150 meshes, and has the lithium metal recovery rate of more than 85%.)

1. A method for preparing lithium salt by first separating a lithium concentrate roasted material and then acidifying or alkalifying the lithium concentrate roasted material is characterized by comprising the following steps of: roasting, dispersing and separating the spodumene ore, and then carrying out acidification or alkalization reaction to prepare lithium salt; the dispersion is to disperse the spodumene roasting material into fine powder below 150 meshes and coarse powder above 150 meshes by mechanical grinding, high-speed stirring or airflow crushing, wherein the fine powder is beta-type lithium concentrate powder for lithium salt production; the coarse powder is lithium-containing feldspar powder; the separation is to separate the fine powder from the coarse powder, only the fine powder below 150 meshes is subjected to acidification or alkalization reaction to prepare lithium salt, and the coarse powder above 150 meshes is used as a byproduct for other purposes.

2. The method of preparing a lithium salt according to claim 1, comprising the steps of:

s1, roasting: placing spodumene ore in a roasting furnace, heating to 1000-1100 ℃, and sintering for 0.5-1h to obtain a roasted material;

s2, crushing and separating: crushing and separating the roasted material obtained in the step S1 through a crushing and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on a 150-mesh sieve is lithium-containing feldspar powder;

s3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by a 150-mesh sieve and sulfuric acid;

s4, roasting, transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at the temperature of 280-300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5-6 by using calcium carbonate; adjusting pH to 7.5-8 with calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate.

3. The method of preparing a lithium salt according to claim 1, comprising the steps of:

s1, roasting: placing spodumene ore in a roasting furnace, heating to 1000-1100 ℃, and sintering for 0.5-1h to obtain a roasted material;

s2, grinding and separating: grinding and separating the roasted material obtained in the step S1 through a grinding and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on a 150-mesh sieve is lithium-containing feldspar powder;

s3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by a 150-mesh sieve and sulfuric acid;

s4, roasting, transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at the temperature of 280-300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5-6 by using calcium carbonate; adjusting pH to 7.5-8 with calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate.

4. The method of preparing a lithium salt according to claim 1, comprising the steps of:

s1, roasting: placing spodumene ore in a roasting furnace, heating to 1000-1100 ℃, and sintering for 0.5-1h to obtain a roasted material;

s2, high-speed stirring and separation: the roasted material obtained in the step S1 is stirred and separated at a high speed through a stirring and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on a 150-mesh sieve is lithium-containing feldspar powder;

s3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by a 150-mesh sieve and sulfuric acid;

s4, roasting, transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at the temperature of 280-300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5-6 by using calcium carbonate; adjusting pH to 7.5-8 with calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate.

5. The method for preparing a lithium salt according to any one of claims 2 to 4, further comprising the steps of: and (4) adding sodium carbonate into the lithium sulfate solution obtained in the step (S7), and carrying out alkalization calcium removal, filtration, evaporation, concentration, lithium precipitation, washing and drying to prepare lithium carbonate.

6. The method of preparing a lithium salt according to claim 5, further comprising the steps of: and carrying out causticization reaction on the prepared lithium carbonate to prepare the lithium hydroxide.

7. The method for preparing a lithium salt according to claim 2, wherein the crushing and separating system in the step S2 is a jet crushing and separating system comprising a crushing classifier, and the gas pressure of the jet crushing and separating system is 1 to 10kg/cm²The power supply frequency is 20-50 Hz.

8. The method for preparing a lithium salt according to claim 3, wherein the milling and separating system in step S2 comprises a mill and a cyclone, the mill does not require a milling medium and has a rotation speed of 60 to 1500r/min, and the cyclone has a wind pressure of 3000 to 10000 pa.

9. The method for preparing a lithium salt according to claim 4, wherein the agitation separation system in the step S2 comprises a high speed agitator and an air classifier, the agitation speed of the high speed agitator is 40-300r/min, and the air pressure of the cyclone is 3000-10000 pa.

Technical Field

The invention relates to the technical field of new energy lithium materials, in particular to a method for preparing lithium salt by separating a lithium concentrate roasted material and then acidifying or alkalifying the lithium concentrate roasted material.

Background

Lithium is a rare precious metal and has very little reserve in nature. The content of lithium oxide in the domestic spodumene raw ore is 0.8-1.4%, and the spodumene raw ore is mainly produced in the lithium-rich granite pegmatite. Wherein, the symbiotic minerals comprise quartz, albite, microcline feldspar and the like, as long as the chemical components are as follows: li₂O、AL₂O₃、SiO₂And Na⁺、Mg²⁺、Ca²⁺、K⁺、Fe²⁺、Mn²⁺、Zn²⁺The plasma can not be directly used in normal state, and Li in raw ore must be removed₂And O is subjected to crystal form conversion, namely, the monoclinic system alpha type is converted into the tetragonal system beta type, so that effective chemical reaction can be carried out. This high temperature calcined ore material is generally referred to as a converted or calcined material. The traditional lithium salt preparation method is that the roasted material is cooled and then ball-milled to 150-200 meshes, acid or alkali is added for leaching, and qualified lithium salt products are produced through a series of chemical processes.

About 6 tons of spodumene raw ore is used for the mine to select 1 ton of Li by gravity separation, flotation or other methods₂Lithium concentrate powder with O content not less than 5 percent, and about 5 tons of flotation slag (solid waste) are discarded; lithium salt factory uses about 8 tons of lithium concentrate powder to produce 1 ton of lithium salt product, and produces about 10 tons of leaching residue (Li)₂O is less than or equal to 0.4 percent). These solid wastes cause environmental pollution. Particularly, the current state emphasizes the green environmental protection and sustainable development and strictly prohibits the discharge of three wastes. The treatment of solid wastes causes enterprises to face huge cost pressure! The market competitiveness is greatly reduced. Particularly, the leaching slag produced in the production of lithium salt continues to use the traditional process, consumes a large amount of acid and alkali and has the cost of labor costValuable resources are changed into 'solid wastes' (the 'solid wastes' are generally applied to being used as fillers for cement plants, and basically lose economic value), the chemical method is simple, practical and effective in impurity removal, but a large amount of useless slag participates in reaction, and no benefit is obtained except that the production cost is increased.

Therefore, the existing lithium salt production process has the technical problems of great environmental pollution caused by solid wastes and high production cost. How to improve the lithium salt production process, reduce the solid wastes in the production and reduce the production cost becomes a technical problem to be solved urgently in lithium salt enterprises nowadays.

Disclosure of Invention

In view of the technical problems of great environmental pollution and high production cost caused by solid wastes in the conventional lithium salt production process, the invention provides a method for preparing lithium salt by separating a lithium concentrate roasted material and then acidifying or alkalifying the lithium concentrate roasted material. The invention can effectively reduce solid waste, reduce production cost and has great economic benefit and environmental protection benefit.

The invention aims to provide a method for preparing lithium salt by separating a lithium concentrate roasted material and then acidifying or alkalifying the lithium concentrate roasted material, which is characterized in that lithium stilbite ore is roasted, dispersed and separated, and then is subjected to acidification or alkalinization reaction to prepare lithium salt; the dispersion is to disperse the spodumene roasting material into fine powder below 150 meshes and coarse powder above 150 meshes by mechanical grinding, high-speed stirring or airflow crushing, wherein the fine powder is beta-type lithium concentrate powder for lithium salt production; the coarse powder is lithium-containing feldspar powder; the separation is to separate the fine powder from the coarse powder, only the fine powder below 150 meshes is subjected to acidification or alkalization reaction to prepare lithium salt, and the coarse powder above 150 meshes is used as a byproduct for other purposes.

Further, the method for preparing a lithium salt includes the steps of:

s1, roasting: placing spodumene ore in a roasting furnace, heating to 1000-1100 ℃, and sintering for 0.5-1h to obtain a roasted material;

s2, crushing and separating: crushing and separating the roasted material obtained in the step S1 through a crushing and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on a 150-mesh sieve is lithium-containing feldspar powder;

s3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by a 150-mesh sieve and sulfuric acid;

s4, roasting, transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at the temperature of 280-300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5-6 by using calcium carbonate; adjusting pH to 7.5-8 with calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate.

Further, the method for preparing a lithium salt includes the steps of:

s1, roasting: placing spodumene ore in a roasting furnace, heating to 1000-1100 ℃, and sintering for 0.5-1h to obtain a roasted material;

s2, grinding and separating: grinding and separating the roasted material obtained in the step S1 through a grinding and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on a 150-mesh sieve is lithium-containing feldspar powder;

s3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by a 150-mesh sieve and sulfuric acid;

s4, roasting, transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at the temperature of 280-300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5-6 by using calcium carbonate; adjusting pH to 7.5-8 with calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate.

Further, the method for preparing a lithium salt includes the steps of:

s1, roasting: placing spodumene ore in a roasting furnace, heating to 1000-1100 ℃, and sintering for 0.5-1h to obtain a roasted material;

s2, high-speed stirring and separation: the roasted material obtained in the step S1 is stirred and separated at a high speed through a stirring and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on a 150-mesh sieve is lithium-containing feldspar powder;

s3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by a 150-mesh sieve and sulfuric acid;

s4, roasting, transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at the temperature of 280-300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5-6 by using calcium carbonate; adjusting pH to 7.5-8 with calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate.

Further, the method for preparing a lithium salt further comprises the steps of: and (4) adding sodium carbonate into the lithium sulfate solution obtained in the step (S7), and carrying out alkalization calcium removal, filtration, evaporation, concentration, lithium precipitation, washing and drying to prepare lithium carbonate.

Further, the method for preparing a lithium salt further comprises the steps of: and carrying out causticization reaction on the prepared lithium carbonate to prepare the lithium hydroxide.

Further, the pulverizing and separating system in the step S2 is a jet pulverizing and separating system, which includes a pulverizing classifier, and the gas pressure of the jet pulverizing and separating system is 1-10kg/cm²The power supply frequency is 20-50 Hz.

Further, the grinding and separating system in the step S2 includes a grinder and a cyclone separator, the grinder does not need a grinding medium, the rotating speed of the grinder is 60-1500 r/min, and the wind pressure of the cyclone separator is 3000-10000 pa.

Further, the stirring and separating system in the step S2 includes a high speed stirrer and an airflow classifier, the stirring speed of the high speed stirrer is 40-300r/min, and the wind pressure of the cyclone separator is 3000-10000 pa.

In the invention, aFirstly, spodumene ore is placed in a roasting furnace to be roasted, so that the monoclinic system alpha type of the spodumene is converted into the tetragonal system beta type, and in the process, the density of the spodumene is from 3.15g/cm³Reduced to 2.4g/cm³The roasted Lijing stone is 50.5% of over 140 meshes, 12.5% of 120-140 meshes, 10.13% of 80-120 meshes, 15.14% of 40-80 meshes and 11.67% of 20-40 meshes, and Li in each grain diameter section is₂The difference of O content is large, how to screen Li from the roasted material₂The key point of the invention is that the lithium concentrate with higher O content is used for producing lithium salt. The applicant does a lot of work, but found in experiments that most of lithium-containing granules have low hardness (about 2-3 degrees) and other gangue minerals have high hardness (about 6-7 degrees), and by utilizing the characteristic, the grinding strength is controlled, so that the Li is selected₂The lithium concentrate with high O content is used for producing lithium salt. The applicant combines the aerodynamic principle and the boiling bed principle, and makes the pulverized roasting material undergo the process of air flow separation in a specific chamber by using supersonic kinetic energy of compressed air, and the fineness can be up to above 200 meshes. The invention combines the airflow separation and the crushing system, thereby not only realizing the grinding effect, but also playing a role in separation. The applicant utilizes the principle of poor hardness of lithium-containing granules and other gangue minerals, adopts a grinding and separating system or a stirring and separating system to well disperse the roasted material into fine powder under a 150-mesh sieve and coarse powder on the 150-mesh sieve, and effectively separates the fine powder and the coarse powder, so that about 65% of lithium-containing feldspar powder in the roasted material is separated out without participating in acidification or alkalization reaction, a large amount of cost is saved, the grade of the separated beta-type lithium concentrate powder is improved, the fineness is more than 150 meshes (can be adjusted), and the recovery rate of lithium metal is more than 85%.

Drawings

FIG. 1 is a flow chart of a process for preparing lithium sulfate according to the present invention.

FIG. 2 is a flow chart of a conventional lithium salt sulfuric acid method production process.

Fig. 3 is a schematic diagram of a crushing and separating system for beta-type lithium refined powder according to the present invention.

Illustration of the drawings:

1. an air compressor; 2. a gas storage tank; 3. a cold dryer; 4. a feed system; 5. a crushing classifier; 6. a cyclone dust collector; 7. a dust remover; 8. an induced draft fan; 9. a control cabinet.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1

A method for preparing lithium salt by separating concentrate roasted material and then acidifying or alkalizing the concentrate roasted material comprises the following steps:

s1, roasting: mixing 100 g of Li₂Placing spodumene ore with O content of 5% in a roasting furnace, heating to 1050 ℃, and sintering for 40min to obtain a roasted material;

s2, crushing and separating: crushing and separating the roasted material obtained in the step S1 through an airflow crushing and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on the 150-mesh sieve is lithium-containing feldspar powder. The airflow crushing and separating system comprises an airflow crusher and an airflow classifier; the gas pressure of the jet milling and separating system is 7kg/cm²The power supply frequency is 40 Hz.

After separation, 65 g of lithium-containing feldspar powder and 33 g of beta-type lithium fine stone powder for lithium salt production (Li of the beta-type lithium fine stone powder) are obtained₂The O content is 14.37%; li of Limonite powder₂O content 0.28%, which was used directly in ceramic production).

S3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by 150 meshes with 93-95% of sulfuric acid;

s4, roasting, namely transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at 300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5 by using calcium carbonate; then adjusting the pH value to 7.5 by using calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate. The leaching residue is filtered to obtain 41.5 g (leaching residue Li)₂O content 0.38%)).

Example 2

A method for preparing lithium salt by separating concentrate roasted material and then acidifying or alkalizing the concentrate roasted material comprises the following steps:

s1, roasting: mixing 100 g of Li₂Placing spodumene ore with the O content of 5% in a roasting furnace, heating to 1000 ℃, and sintering for 1h to obtain a roasted material;

s2, grinding and separating: grinding and separating the roasted material obtained in the step S1 through a grinding and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on a 150-mesh sieve is lithium-containing feldspar powder;

separating to obtain 62 g of lithium-containing feldspar powder and 33 g of beta-type lithium fine stone powder for lithium salt production (Li of the beta-type lithium fine stone powder)₂The O content is 14.62%; li of Limonite powder₂The content of O is less than or equal to 0.27 percent and the O is directly used for ceramic production).

S3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by 150 meshes with 93-95% of sulfuric acid;

s4, roasting, namely transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at 300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5 by using calcium carbonate; then adjusting the pH value to 7.5 by using calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate. The leaching residue was filtered to obtain 43 g (Li)₂O content 0.35%).

Example 3

A method for preparing lithium salt by separating concentrate roasted material and then acidifying or alkalizing the concentrate roasted material comprises the following steps:

s1, roasting: mixing 100 g of Li₂Placing spodumene ore with the O content of 5% in a roasting furnace, heating to 1000 ℃, and sintering for 1h to obtain a roasted material;

s2, high-speed stirring and separation: the roasted material obtained in the step S1 is stirred and separated at a high speed through a stirring and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on a 150-mesh sieve is lithium-containing feldspar powder;

64 g of lithium-containing feldspar powder and 31 g of beta-type lithium fine stone powder for lithium salt production are obtained after separation (Li of the beta-type lithium fine stone powder)₂The O content is 15.37%; li of Limonite powder₂O content 0.27, which was used directly in ceramic production).

S3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by 150 meshes with 93-95% of sulfuric acid;

s4, roasting, namely transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at 300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5 by using calcium carbonate; then adjusting the pH value to 7.5 by using calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate. The leaching residue is filtered to obtain 40.2 g (the leaching residue Li)₂O content 0.37%).

Example 4

A method for preparing lithium salt by separating concentrate roasted material and then acidifying or alkalizing the concentrate roasted material comprises the following steps:

s1, roasting: mixing 100 g of Li₂Placing spodumene ore with the O content of 5.8% in a roasting furnace, heating to 1000 ℃, and sintering for 1h to obtain a roasted material;

s2, crushing and separating: crushing and separating the roasted material obtained in the step S1 through an airflow crushing and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on the 150-mesh sieve is lithium-containing feldspar powder. The airflow crushing and separating system comprises an airflow crusher and an airflow classifier; the gas pressure of the jet milling and separating system is 1kg/cm²The power supply frequency is 50 Hz.

After separation, 72 g of lithium-containing feldspar powder and 27 g of beta-type lithium fine stone powder for lithium salt production (Li of the beta-type lithium fine stone powder) are obtained₂The O content is 20.37%; li of Limonite powder₂The O content is 0.27 percent, and the ceramic is directly used for ceramic production)。

S3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by a 150-mesh sieve and 93-95% sulfuric acid in a double-helix mixer;

s4, roasting, namely transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at 300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5 by using calcium carbonate; then adjusting the pH value to 7.5 by using calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate. The leaching residue was filtered to obtain 43.5 g (leaching residue Li)₂O content 0.37%)).

Example 5

A method for preparing lithium salt by separating concentrate roasted material and then acidifying or alkalizing the concentrate roasted material comprises the following steps:

s1, roasting: mixing 100 g of Li₂Placing spodumene ore with the O content of 5.8% in a roasting furnace, heating to 1000 ℃, and sintering for 1h to obtain a roasted material;

s2, crushing and separating: crushing and separating the roasted material obtained in the step S1 through an airflow crushing and separating system; the fine powder material sieved by a 150-mesh sieve is beta-type lithium fine stone powder for producing lithium salt; the coarse powder on the 150-mesh sieve is lithium-containing feldspar powder. The airflow crushing and separating system comprises an airflow crusher and an airflow classifier; the gas pressure of the jet milling and separating system is 10kg/cm²The power supply frequency is 20 Hz.

Separating to obtain 62 g of lithium-containing feldspar powder and 34 g of beta-type lithium fine stone powder for lithium salt production (Li of the beta-type lithium fine stone powder)₂The O content is 14.37%; li of Limonite powder₂O content 0.27%, which was used directly in ceramic production).

S3, mixing acid, namely uniformly mixing the fine lithium fine powder which is obtained in the step S2 and is sieved by a 150-mesh sieve and 93-95% sulfuric acid in a double-helix mixer;

s4, roasting, namely transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at 300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5 by using calcium carbonate; then adjusting the pH value to 7.5 by using calcium hydroxide;

s7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate. The leaching residue was filtered to obtain 43.5 g (leaching residue Li)₂O content of 0.38%) or less).

Example 6: adding sodium carbonate into the lithium sulfate solution prepared in the example 1, and carrying out the steps of alkalization calcium removal, filtration, evaporation, concentration, lithium precipitation, washing and drying to prepare lithium carbonate.

Example 7: lithium carbonate prepared in example 6 was subjected to causticization reaction to prepare lithium hydroxide.

Example 8: adding sodium carbonate into the lithium sulfate solution prepared in the example 2, and carrying out the steps of alkalization to remove calcium, filtration, evaporation, concentration, lithium precipitation, washing and drying to prepare lithium carbonate.

Example 9: lithium carbonate prepared in example 8 was subjected to causticization to prepare lithium hydroxide.

Example 10: adding sodium carbonate into the lithium sulfate solution prepared in the example 3, and carrying out the steps of alkalization to remove calcium, filtration, evaporation, concentration, lithium precipitation, washing and drying to prepare lithium carbonate.

Example 11: lithium carbonate prepared in example 10 was subjected to causticization to prepare lithium hydroxide.

Example 12: adding sodium carbonate into the lithium sulfate solution prepared in the example 4, and carrying out the steps of alkalization to remove calcium, filtration, evaporation, concentration, lithium precipitation, washing and drying to prepare lithium carbonate.

Example 13: lithium carbonate prepared in example 12 was subjected to causticization to prepare lithium hydroxide.

Example 14: adding sodium carbonate into the lithium sulfate solution prepared in the example 5, and carrying out the steps of alkalization to remove calcium, filtration, evaporation, concentration, lithium precipitation, washing and drying to prepare lithium carbonate.

Example 15: lithium carbonate prepared in example 14 was subjected to causticization to prepare lithium hydroxide.

In the embodiments 1 and 4, the implementation method of the step S2 is specifically described as follows with reference to fig. 3:

the airflow crushing and separating system comprises an air compressor (1), an air storage tank (2), a cold dryer (3), a feeding system (4), an airflow crushing classifier (5), a cyclone dust collector (6), a dust collector (7), an induced draft fan (8) and a control cabinet (9); the air storage tank (2) is respectively connected with the compressor (1) and the cold dryer (3) through air pipes, the cold dryer (3) is connected with the bottom of the air flow crushing classifier (5) through another air pipe, the middle lower part of the air flow crushing classifier (5) is connected with the feeding system (4), the top of the air flow crushing classifier (5) is connected with the cyclone dust collector (6) through a pipeline, the lower end of the cyclone dust collector (6) is provided with a discharge port, the top end of the cyclone dust collector (6) is connected with the dust collector (7) through a pipeline, the lower end of the dust collector (7) is provided with a discharge port, the upper end part of the dust collector (7) is connected with the induced draft fan (8) through a pipeline, the control cabinet (9) is connected with the air compressor (1), the air storage tank (2), the cold dryer (3), the feeding system (4), the airflow crushing classifier (5), the cyclone dust collector (6), the dust collector (7) and the induced draft fan (8) through signals.

Compressing air by an air compressor (1), injecting the compressed air into an air storage tank (2), cooling and drying the compressed air by a cooling dryer (3), feeding the compressed air and a roasting material from a feeding system (4) into a crushing classifier (5), regulating and controlling the rotating speed of the classifier of the crushing and classifying system (5) by air pressure and air flow from the air compressor (1), sending beta-type lithium fine powder meeting the granularity requirement into a cyclone dust collector (6), and separating large particles from the lower end of the cyclone dust collector (6) after the large particles are settled, namely separating the large particles from the lower end of the cyclone dust collector (6), namely Li₂Lithium-containing feldspar powder with O less than or equal to 0.3 percent; the beta-type lithium fine powder with the fineness of 150-. All the operations can be controlled and adjusted through the control cabinet (9).

Cooling the roasted material, passing through a feeding system (4), meeting with oil-containing, cooled and dried 1-10 compressed air from an air compressor (1) in an air flow crushing classifier (5), fluidizing, roastingThe burning material particles are subjected to violent collision, friction, shearing and extrusion, because the hardness of the beta-type lithium concentrate powder in the burning material is greatly lower than that of the quartz feldspar minerals, the beta-type lithium concentrate powder can easily reach the crushed particle size of 150-200 meshes under the self-grinding action of the minerals, and then the beta-type lithium concentrate powder is sent into a cyclone dust collector (6) by ascending air flow, and about 65 percent of Li is sent into a cyclone dust collector (6)₂The lithium-containing feldspar powder discharging system with O less than or equal to 0.3 percent achieves the purpose of crushing and separating beta type lithium refined stone powder.

Comparative example:

the traditional lithium salt sulfuric acid method comprises the following steps:

s1, roasting: mixing 100 g of Li₂Placing spodumene powder with O content of 5% in a roasting furnace, heating to 1050 ℃, and sintering for 40min to obtain a roasted material;

s2, ball milling: and (4) placing the roasted material obtained in the step (S1) into a ball mill, and grinding the roasted material to about 200 meshes by using steel balls as a dispersion medium to obtain the roasted material fine powder for acidification in lithium salt production.

S3, mixed acid: uniformly mixing the spodumene roasting material fine powder obtained in the step S2 and 93-95% sulfuric acid in a double-helix mixer;

s4, roasting, namely transferring the mixed material obtained in the step S3 to an acidification roasting kiln, and roasting for 1h at the temperature of 280-300 ℃;

s5, curing, namely stacking the roasted material obtained in the step S4 for 12 hours for curing;

s6, leaching, namely adding water into the cured material obtained in the step S5, pulping, and adjusting the pH value to 5.5-6 by using calcium carbonate; adjusting pH to 7.5-8 with calcium hydroxide;

and S7, filtering, namely filtering the mixture obtained in the step S6 to obtain filtrate, namely lithium sulfate. Through filtration, 125 g of leaching residue (leaching residue Li) is obtained₂O content 0.38%).

The main component of the leaching slag is calcium sulfate, and the leaching slag can only be used for production in cement plants, so that the economic benefit is basically not high.

According to the lithium salt preparation method, the roasting material is dispersed into fine powder under a 150-mesh sieve and coarse powder on the 150-mesh sieve, and effective separation is carried out, so that 65% of lithium-containing feldspar powder in the roasting material is separated, acidification or alkalization reaction is not carried out, a large amount of cost is saved, the grade of the separated beta-type lithium argillite powder is improved, the fineness is more than 150 meshes, and the recovery rate of lithium metal is more than 85%.

The following outstanding technical effects of the invention can be seen from the examples 1-5 and the comparative example, which are shown in the attached drawings 1 and 2:

(based on 1 ton of lithium salt produced)

1. Firstly, a ball milling system is completely replaced, and the consumption cost of steel balls, lining plates, manpower, electric power, filter cloth and the like is saved by at least 350 yuan;

2. about 65 percent of the lithium-containing feldspar powder in the roasting material is separated, and does not participate in the acidification reaction any more, so that 0.8 ton of sulfuric acid is saved, and the cost is saved by 400 yuan;

3. li-containing feldspar powder Li separated by the invention₂The content of O is less than or equal to 0.3 percent, and Li is leached out from the traditional leaching residue₂The O content is less than or equal to 0.4 percent, so the invention does not increase the loss of lithium, but the lithium-containing feldspar powder separated by the invention can be directly sold to the ceramic industry as a byproduct, the separated slag per ton is more than 200 yuan more than the leached slag, and the profit can be increased by 1040 yuan according to the separation of 5.2 tons per ton of lithium salt; if the magnetic separation treatment is carried out, the magnetic separation material can be used as a raw material in the glass industry, and the profit is turned over;

4. the calcium carbonate is saved by about 520kg, and the cost is reduced by 150 yuan;

5. the material flux is reduced by about 2/3, the total cost can be reduced by about 2000 yuan/ton (lithium salt product) after the conversion roasting, and the capacity is enlarged by 1.85 times compared with the traditional acidification leaching procedure;

6. the method of the invention is used for building a project, the investment can be saved by more than 20-50% in the same scale, and the method is particularly suitable for autoclave production;

7. the production of leaching slag (solid waste) is reduced on the original basis, and great environmental protection benefit is achieved;

8. the separation process of the invention can be intelligently controlled in the whole process, the operation is simple, the operation is carried out under negative pressure, and the invention is clean and civilized;

9. the grade of the beta-type lithium fine stone powder separated by the method is improved, the fineness is more than 150 meshes (can be adjusted), and the recovery rate of lithium metal is more than 85%.

According to incomplete statistics in 2020, 17 ten thousand tons of lithium salt products are produced by a national mining method, wherein at least 12 ten thousand tons of spodumene is used as a raw material. If the separation method of the lithium refined powder is adopted, the cost of each ton of lithium salt products can be directly reduced by about 2000 yuan, and the profit can be increased by 2.4 million yuan throughout the country. But also optimizes the traditional process flow, reduces the discharge of three wastes and has great economic benefit and environmental protection benefit.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention. Various modifications and alterations of this invention will occur to those skilled in the art, and any such modifications, equivalents, and improvements that fall within the spirit and scope of the invention are intended to be embraced therein.