CN109943715B

CN109943715B - Heap leaching method for lepidolite

Info

Publication number: CN109943715B
Application number: CN201910341933.XA
Authority: CN
Inventors: 杨志平; 李大炳
Original assignee: Beijing Research Institute of Chemical Engineering and Metallurgy of CNNC
Current assignee: Beijing Research Institute of Chemical Engineering and Metallurgy of CNNC
Priority date: 2019-04-26
Filing date: 2019-04-26
Publication date: 2021-04-13
Anticipated expiration: 2039-04-26
Also published as: CN109943715A

Abstract

The invention relates to the technical field of lithium extraction from ores, and particularly discloses a lepidolite dump leaching method, which comprises the following steps: grinding ore; ② acid mixing; mixing water and silicofluoric acid; fourthly, curing; crushing and piling; sixthly, heap leaching; and collecting the leaching solution. The method does not need high-temperature calcination for defluorination, low-temperature roasting and pressure leaching, reduces equipment investment, and has low energy consumption, little environmental pollution, simplicity and high efficiency.

Description

Heap leaching method for lepidolite

Technical Field

The invention belongs to the technical field of lithium extraction from ores, and particularly relates to a lepidolite heap leaching method.

Background

Due to the development of electric vehicles, the demand of lithium batteries in the global market is rising, so that the demand of lithium carbonate is rising rapidly. How to develop and utilize various lithium resources to prepare lithium carbonate to meet the demand of the market for lithium carbonate is an urgent task in front of us.

Lithium exists in nature mainly in two forms of solid mineral resources and liquid ore deposit resources, and the solid mineral resources are mainly divided into spodumene minerals and lepidolite minerals. The mineral resources of spodumene in China are relatively short, the lepidolite is abundant, the storage capacity of the lepidolite in the areas which are in the spring of Jiangxi province is large, and the storage capacity of lithium is 257.8 ten thousand tons in terms of lithium oxide, so that the lepidolite is used as a raw material to extract lithium carbonate, and the method has wide market prospect and good economic benefit.

The existing lithium extracting method from lepidolite mainly comprises three major types, namely an acid method, an alkali method and a salt method. The acid method mainly uses sulfuric acid as a leaching agent, generally high-temperature defluorination roasting is needed in advance to destroy the mica structure, or sulfuric acid is added for roasting and then leaching, and the defects of high energy consumption for calcination and defluorination, large environmental pollution, large sulfuric acid consumption, high residual acid in leaching solution, high yield of neutralized slag and the like exist.

The alkali method comprises the traditional limestone sintering method, the roasting defluorinated lime pressure boiling method, the direct lime milk pressure boiling method and the like, wherein 80 tons of dry residues are generated when 1 ton of lithium carbonate is produced by the limestone sintering method, the residue yield is very high, and the energy consumption is high. The lime milk pressure boiling method has large liquid-solid ratio, the lithium concentration of the leaching liquid is low, and the filtering is difficult.

The salt method is to mix sulfate, chloride and the like with lepidolite uniformly and then calcine the mixture at high temperature to react and extract lithium, wherein the sulfate method generally uses potassium sulfate, and has high price and high reagent cost. Chlorine gas is generated by roasting by a chloride method, the environmental pollution is large, the equipment is seriously corroded, and the chlorine radical in the lithium carbonate product is easy to exceed the standard.

The patent CN101885496A discloses a process for extracting lithium from lepidolite by fluorine chemistry, wherein lepidolite is added with sulfuric acid and fluosilicic acid, pre-reacted for 1h at 50-150 ℃, then reacted for 1-4 h at 150-350 ℃ in a rotary kiln, and then leached by water. The conversion rate, leaching rate and total recovery rate of lithium are not disclosed, and after concentration and impurity removal, sodium carbonate is added for precipitation, so that only a crude lithium salt product with the concentration of more than 80% is obtained.

Patent CN102337399A discloses a method for extracting lithium by treating lepidolite through an alkali dissolution method, which comprises the steps of mixing the lepidolite with strong alkali liquor, reacting for more than 6 hours at 150 ℃ under the pressure of 8 kilograms, and leaching residues for secondary leaching under the same conditions, wherein the patent does not disclose the leaching rate of lithium.

Patent CN102586587A discloses a new method for treating lepidolite ore, which comprises calcining lepidolite ore at 900 ℃ for defluorination, grinding, mixing with lime and alkali metal salt for autoclaving and leaching, and autoclaving at 150 ℃ for about 2 hours under low pressure, wherein leaching rates are Li 90%, K80% and Rb 70%.

Patent CN101736169A discloses a method for extracting lithium from lepidolite by defluorination roasting chlorine salt pressure cooking, which comprises the steps of mainly calcining at 900 ℃ for defluorination, grinding, adding calcium oxide and sodium chloride, and pressure cooking in an autoclave.

Patent CN103145158A discloses a method for preparing lithium carbonate from lepidolite by a sulfuric acid roasting method, which comprises the steps of mainly calcining at 900 ℃ for defluorination, grinding with acid for roasting, and then leaching in two stages, wherein the leaching rate of lithium is more than 96%.

The above-mentioned patents all require high-temperature calcination and defluorination in combination with low-temperature sulfuric acid roasting or high-pressure leaching, and have the disadvantages of long process flow, large equipment investment, high energy consumption and complex operation.

Patent CN106086471A discloses a method for lepidolite defluorination and valuable metal leaching, which is to grind lepidolite concentrate to 70% to pass through 200 meshes, then mix with sulfuric acid to cure for 20-30 hours, ensure defluorination to reach more than 95%, and then add water to leach. Although the high-temperature calcination link is reduced, the lepidolite concentrate must be ground to 70% to pass through 200 meshes, so the grinding cost is high; in addition, in order to ensure that the defluorination reaches more than 95%, the heat preservation and curing are carried out for 20-30 hours, the curing time is long, so that the energy consumption is high, and the equipment productivity is low.

Disclosure of Invention

The invention aims to provide a lepidolite heap leaching method, which can efficiently and economically decompose and destroy lepidolite and leach lithium in the lepidolite.

The technical scheme of the invention is as follows:

a lepidolite heap leaching method comprises the following steps:

grinding ore

Grinding the lepidolite concentrate to ensure that the proportion of-200 meshes accounts for 30-70%;

② acid mixing

Adding concentrated sulfuric acid into the finely ground lepidolite concentrate, and quickly stirring and uniformly mixing;

③ mixing with water and silicofluoric acid

Adding water and silicofluoric acid, and quickly and uniformly stirring;

ripening

Preserving heat, sealing and curing the lepidolite ore mixed with the acid and the water;

fifthly, crushing and piling

Crushing the cured materials, and then transferring the crushed materials to a heap leaching pool for heaping;

(iii) heap leaching

Spraying a leaching agent on the ore heap to perform heap leaching operation;

seventhly, collecting the leaching solution

Collecting heap leaching liquid in a segmented mode according to the outflow sequence;

the first-stage effluent liquid has high acidity, and the volume of the first-stage effluent liquid is 0.1-0.3 time of the lepidolite ore; the effluent liquid of the second stage is a qualified leachate, and the volume of the leachate is 0.5-1.0 time of the lepidolite amount; the third stage is a barren leaching solution, and the volume of the barren leaching solution is 0.5-1.5 times of the amount of the lepidolite ore.

In the step I, the lepidolite concentrate is ensured to be ground to more than 90% and less than 60 meshes.

In the second step, the adding amount of concentrated sulfuric acid is 0.5-1 time of the mass of the mineral powder.

In the third step, the addition amount of water is 0.1-0.5 times of the mass of the mineral powder, and the consumption amount of silicofluoric acid is 0.02-0.1 times of the mass of the mineral powder.

The stirring and mixing time in the second step is 10-30 min, and the stirring and mixing time in the third step is 2-20 min.

In the fourth step, the curing temperature is 100-200 ℃, and the curing time is 4-20 hours.

In the fifth step, the crushed materials are 5-50 mm in block shape, and the stacking height is 3-5 m.

Sixthly, the spraying temperature is 20-40 ℃, and the spraying strength is 20-100L/m²H, the total spraying amount of the leaching agent is 0.5-2.5 times of the original lepidolite amount.

And sixthly, spraying in an intermittent mode.

The leaching agent in the step (sixthly) is water or the returned barren leaching solution is collected in the step (seventhly);

collecting the effluent of the first section in the step (c), returning to the step (c) to replace water and adding the water into the lepidolite ore;

collecting the qualified leaching solution, and then, recovering lithium in the next process.

The invention has the following remarkable effects:

(1) the method does not need high-temperature calcination for defluorination or low-temperature roasting, and has the advantages of low equipment investment, low energy consumption and little environmental pollution.

(2) The method has less acid consumption, adopts acid-mixing curing to treat the lepidolite, can obtain high acid concentration due to less water addition amount and reduces the acid consumption, and is favorable for breaking the lepidolite structure; and the acid concentration of the leaching solution is high, so that the leaching solution can be returned to participate in the next acid mixing and curing, and the acid consumption is reduced.

(3) The method has low ore grinding energy consumption and low requirement on the granularity of the lepidolite concentrate, the proportion of the lepidolite concentrate is only 30-70% when the lepidolite concentrate is smaller than 200 meshes, and the granularity of the lepidolite concentrate is lower than the requirement that the lepidolite concentrate is 70% when the lepidolite concentrate is smaller than CN106086471A granularity-200 meshes, so that the ore grinding energy consumption and the cost are greatly reduced.

(4) The method adopts a heap leaching mode, does not need pressure leaching, reduces the investment of leaching equipment, and eliminates the operations of filtering and washing.

(5) The method is simple and efficient, the obtained qualified leachate has small volume and high lithium concentration, and the energy consumption of evaporation and concentration is greatly reduced.

(6) The addition of the fluosilicic acid in the method enhances the cracking effect on the lepidolite, so that the sulfuric acid curing process has no special requirement on the removal of fluorine, and the defluorination is ensured to be more than 95 percent unlike the requirement of patent CN 106086471.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

A lepidolite heap leaching method comprises the following steps:

grinding ore

And grinding the lepidolite concentrate to more than 90% and less than 60 meshes, and ensuring that the proportion of-200 meshes accounts for 30-70%.

② acid mixing

Mixing concentrated sulfuric acid with the concentration of 92-98% into the ground lepidolite concentrate, and stirring and mixing uniformly;

wherein the adding amount of concentrated sulfuric acid is 0.5-1 time of the mass of the mineral powder, and the mixing time is 10-30 min.

③ mixing with water and silicofluoric acid

Adding water and silicofluoric acid, and quickly and uniformly stirring;

wherein the adding amount of water is 0.1-0.5 times of the mass of the mineral powder, the using amount of silicofluoric acid is 0.02-0.1 times of the mass of the mineral powder, and the stirring and mixing time is 2-20 min.

Ripening

Preserving heat, sealing and curing the lepidolite ore mixed with the acid and the water, wherein the curing temperature is 100-200 ℃, and the curing time is 4-20 hours;

the reactions that occur during the maturation process are as follows:

KLi₂Al(Si₄O₁₁)(F,OH)₂+H₂SO₄→

Li₂SO₄+K₂SO₄+Al₂(SO₄)₃+Si₂O·Al₂O₃+H₂O+HF↑+SiF₄↑。

fifthly, crushing and piling

And crushing the cured materials into blocks of 5-50 mm, and then transferring the blocks to a heap leaching pool for heaping, wherein the heaping height is 3-5 m.

(iii) heap leaching

Spraying a leaching agent to the ore heap for heap leaching, wherein the leaching agent is water and returned barren leaching solution;

wherein the temperature is 20-40 ℃, and the spraying strength is 20～100L/m²And h, stopping the spraying for 2 hours every 4 hours, wherein the total spraying amount of the leaching agent is 0.5-2.5 times of the original lepidolite amount.

Seventhly, collecting the leaching solution

the effluent liquid of the first stage has higher acidity, is collected and then returns to the step III, and is added into the lepidolite ore instead of water, wherein the volume of the lepidolite ore is 0.1-0.3 time of the lepidolite ore; collecting the qualified leachate of the second-stage effluent, and then returning to the next working procedure to recover lithium, wherein the volume of the leachate is 0.5-1.0 time of the lepidolite ore; and the third stage is a barren leaching solution, and the barren leaching solution is collected and returned to the step (sixthly) to participate in the next ore heap leaching and is used as spray water, wherein the volume of the barren leaching solution is 0.5-1.5 times of the lepidolite amount.

Example one

Certain lepidolite mineral sample compositions were as follows:

composition (I)	Li₂O	SiO₂	Al₂O₃	K₂O	Fe₂O₃	MnO	F	Rb₂O	Na₂O	Cs₂O
											Content%	3.17	48.7	22.6	7.8	2.2	0.40	4.5	0.86	0.87	0.06

The method comprises the following steps:

100Kg of lepidolite is ground into fine powder, and the ground powder is 6.1 percent of plus 60 meshes and 70 percent of minus 200 meshes;

adding 90Kg of concentrated sulfuric acid with the concentration of 96% into the ground lepidolite ore sample, uniformly stirring, adding 10Kg of water and 5Kg of silicofluoric acid, rapidly and uniformly stirring, and then putting into an oven at 180 ℃ for curing for 4 hours;

thirdly, crushing the cured material to 5-20 mm, and then filling the material into a heap leaching column with the diameter of 200 multiplied by 3500, wherein the height of a material layer is 3.2 m;

fourthly, spraying water to the ore heap for heap leaching operation, wherein the water temperature is 25 ℃, and the spraying intensity is 40L/m²H, stopping for 2 hours every 4 hours of spraying, wherein the total spraying amount of the leaching agent is 240L;

collecting the leachate in a sectional manner according to the outflow sequence, wherein the volume of the effluent liquid in the first section is 20L, and the acid concentration is 540g/L, and returning to the step II after collection to participate in the next lepidolite ore acid mixing and curing; the second-stage effluent liquid is 100L, is qualified leachate, has the Li concentration of 9.3g/L, and is collected and then sent to the next working procedure to recycle lithium; the third stage is barren leachate with the volume of 70L, and the barren leachate is collected and returned to the step (IV) to participate in the next heap leaching of the ore heap to be used as spray water.

92.1kg of leaching residue is finally obtained, the Li content is 0.094%, and the lithium leaching rate reaches 94.2%.

Example two

Certain lepidolite mineral sample compositions are as follows:

composition (I)	Li₂O	SiO₂	Al₂O₃	K₂O	Fe₂O₃	MnO	F	Rb₂O	Na₂O
										Content%	2.87	54.6	23.5	8.3	1.54	0.39	4.1	0.93	0.83

The method comprises the following steps:

125Kg of lepidolite is ground into powder, and the powder is ground into powder with 9.3 percent of 60 meshes and 35 percent of-200 meshes;

adding 100Kg of 97% concentrated sulfuric acid into the ground lepidolite ore sample, uniformly stirring, adding 20L of the first-stage effluent liquid collected in the first embodiment and 3Kg of silicofluoric acid, rapidly and uniformly stirring, and then placing the mixture into an oven at 150 ℃ for curing for 12 hours;

thirdly, crushing the cured material to 10-30 mm, and then filling the crushed material into a heap leaching column with the diameter of 200 multiplied by 3500, wherein the height of a material layer is 4 m;

fourthly, the effluent liquid of the third section collected in the first embodiment is firstly sprayed on the ore heap, and then water is added for spraying after the effluent liquid is used up, the temperature is 35 ℃, and the spraying intensity is 60L/m²H, stopping for 2 hours every 4 hours of spraying, wherein the total spraying amount of the leaching agent is 320L;

obtaining 260L of leachate, collecting the leachate in a sectional manner according to the outflow sequence, wherein the volume of the effluent liquid in the first section is 25L, the acid concentration is 560g/L, and returning to the step II after collection to participate in the next lepidolite ore acid mixing and curing; 105L of second-stage effluent is qualified leachate, the concentration of Li is 9.8g/L, and the second-stage effluent is collected and then sent to the next working procedure to recycle lithium; the third stage is barren leachate with the volume of 130L, and the barren leachate is collected and returned to the step (IV) to participate in the next heap leaching of the ore heap to be used as spray water.

110.4kg of leaching residue is finally obtained, the Li content is 0.102%, and the lithium leaching rate reaches 93.3%.

EXAMPLE III

Certain lepidolite mineral sample compositions are as follows:

composition (I)	Li₂O	SiO₂	Al₂O₃	K₂O	Fe₂O₃	MnO	F	Rb₂O	Na₂O
										Content%	3.36	47.3	23.8	8.8	3.45	0.44	4.8	1.04	0.98

The method comprises the following steps:

3000Kg of lepidolite is ground into fine powder, and the ground powder is 5.4% of plus 60 meshes and 56% of minus 200 meshes;

adding 2400Kg of 93 percent concentrated sulfuric acid into the ground lepidolite ore sample, uniformly stirring, adding 450L of the first-stage effluent liquid collected under the same conditions and 200Kg of silicofluoric acid, rapidly and uniformly stirring, transferring to a curing pool, charging 120 ℃ hot air, and carrying out heat preservation curing for 15 hours;

crushing the cured material to 5-50 mm, and then loading the material into a heap leaching tower of 900 x 5500, wherein the height of a material layer is 5 m;

fourthly, spraying the third section effluent liquid collected in the previous operation on the ore heap, adding water for spraying after the third section effluent liquid is used up, wherein the temperature is 40 ℃, and the spraying strength is 80L/m²H, stopping for 2h every 4h of spraying, wherein the total spraying amount of the leaching agent is 8000L;

obtaining 6600L of leachate, collecting leachate by stages according to outflow sequence, wherein the volume of effluent liquid in the first stage is 600L, the acid concentration is 575g/L, and returning to the second step after collection to participate in the next lepidolite ore acid mixing and curing; the second-stage effluent liquid 2400L is a qualified leachate, the Li concentration is 12.6g/L, and the collected second-stage effluent liquid is sent to the next working procedure to recover lithium; the third stage is lean leaching solution with the volume of 3600L, and the lean leaching solution is collected and returned to the step (IV) to participate in the next heap leaching of ore piles for spraying water.

2813kg of leaching residue is finally obtained, the Li content is 0.117 percent, and the lithium leaching rate reaches 93.0 percent.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and the technical essence of the present invention is to use acid-mixed curing to destroy the lepidolite structure, without high-temperature calcination, low-temperature calcination, and pressure leaching, and any simple modification, equivalent change, and modification of the above embodiments according to the technical essence of the present invention are all within the protection scope of the technical solution of the present invention.

Claims

1. A lepidolite heap leaching method is characterized in that: the method comprises the following steps:

grinding ore

② acid mixing

③ mixing with water and silicofluoric acid

Adding water and silicofluoric acid, and quickly and uniformly stirring;

ripening

fifthly, crushing and piling

(iii) heap leaching

Spraying a leaching agent on the ore heap to perform heap leaching operation;

seventhly, collecting the leaching solution

the first-stage effluent liquid has high acidity, and the volume of the first-stage effluent liquid is 0.1-0.3 time of the lepidolite ore; the effluent liquid of the second stage is a qualified leachate, and the volume of the leachate is 0.5-1.0 time of the lepidolite amount; the third stage is a barren leaching solution, and the volume of the barren leaching solution is 0.5-1.5 times of the amount of the lepidolite ore;

2. A lepidolite heap leach process according to claim 1 wherein: in the step I, the lepidolite concentrate is ensured to be ground to more than 90% and less than 60 meshes.

3. A lepidolite heap leach process according to claim 2 wherein: in the second step, the adding amount of concentrated sulfuric acid is 0.5-1 time of the mass of the mineral powder.

4. A lepidolite heap leach process according to claim 3 wherein: in the third step, the addition amount of water is 0.1-0.5 times of the mass of the mineral powder, and the consumption amount of silicofluoric acid is 0.02-0.1 times of the mass of the mineral powder.

5. A lepidolite heap leach process according to claim 4 wherein: the stirring and mixing time in the second step is 10-30 min, and the stirring and mixing time in the third step is 2-20 min.

6. A lepidolite heap leach process according to claim 5 wherein: in the fourth step, the curing temperature is 100-200 ℃, and the curing time is 4-20 hours.

7. A lepidolite heap leach process according to claim 6 wherein: in the fifth step, the crushed materials are 5-50 mm in block shape, and the stacking height is 3-5 m.

8. A lepidolite heap leach process according to claim 7 wherein: and sixthly, spraying in an intermittent mode.

9. A lepidolite heap leach process according to any one of claims 1 to 8 wherein: the leaching agent in the step (sixthly) is water or the returned barren leaching solution is collected in the step (seventhly);