A method for pressure leaching of lithium residue

Abstract

The present application provides a kind of lithium residue autoclave leaching method, comprising the following steps: S1: lithium residue and acid solution are carried out autoclave displacement reaction under saturated vapor pressure to obtain lithium leaching residue;Lithium residue and the acid solution do not directly contact;S2: the lithium leaching residue is mixed with water and is beaten to pulp, and then filtration is carried out to obtain lithium-rich brine and silicon-aluminum-rich leaching residue.The lithium residue autoclave leaching method provided by the present application solves the problem of high liquid-solid ratio under high-temperature pressure conditions, which can effectively improve the acid leaching efficiency and reduce the acid and alkali consumption.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of comprehensive utilization of lithium residue, and particularly relates to a lithium residue autoclave leaching method. BACKGROUND

[0002] The lithium residue is mainly leaching residue produced by composite sulfate roasting and leaching of spodumene or lepidolite ore, and mainly contains aluminosilicate, calcium sulfate, cesium and rubidium salt, and lithium-containing ore which is not fully sulfated, with lithium content of 0.1%-0.2%. According to statistics, 30-40 tons of lithium residue are produced for every ton of lithium carbonate product. Although the lithium residue has no acid and alkali corrosion, it has a great pollution risk to the environment due to the soluble thallium and beryllium. Meanwhile, the lithium residue is produced in a large amount, occupies a large amount of land resources, and urgently needs a stable and reliable bulk resource utilization technology. Therefore, developing an efficient lithium residue leaching technology is a research hotspot and difficulty. Some research provides a method for high liquid-solid ratio hot acid multi-step leaching of lithium residue, with pH value controlled at 0-2 and temperature at 60-65℃. The process flow is long, the leaching pH value is low, and the acid consumption is large. Some research provides a method for high liquid-solid ratio high-pressure alkali leaching of mica ore, and then leaching lithium by dilute acid after high-pressure alkali leaching. The high-pressure alkali leaching parameters of the method are not clear, but the acid and alkali consumption is large, and the process is complex. Some research provides a method for high liquid-solid ratio carbon acid hot pressure leaching of lithium-containing material, with temperature at 140-320℃ and reaction pressure at 0.6-12.5MPa. The process has a high temperature, uses a pressure vessel, and is difficult to be popularized and applied on a large scale. Some research provides a method for high liquid-solid ratio hot acid hot salt high-pressure leaching of lepidolite roasting material, with sodium chloride and hydrochloric acid as leaching agents, pH value controlled at 2-3, reaction temperature at 150-180℃, and reaction time of 4-8h. The process has a low leaching pH value, a high temperature, and a long reaction time, and has a large acid and alkali consumption. The above methods all have problems of limited treatment capacity, large acid and alkali consumption, and high energy consumption due to high liquid-solid ratio, high temperature, or long reaction time under high pressure conditions or low pH value.

[0003] In view of the above, there is an urgent need to provide a method for comprehensively recovering calcium and arsenic from calcium arsenic residue with low energy consumption. SUMMARY

[0004] The present application aims to at least solve one of the above technical problems in the prior art. To this end, the present application provides a lithium residue autoclave leaching method, which solves the problem of high liquid-solid ratio under high pressure conditions restricting the treatment capacity, and can effectively improve the acid leaching efficiency and reduce the acid and alkali consumption.

[0005] The first aspect of the present application provides a lithium residue autoclave leaching method, comprising the following steps:

[0006] S1: carrying out autoclave displacement reaction of lithium residue and an acid solution under saturated vapor pressure to obtain lithium leaching residue;

[0007] The lithium residue and the acid solution do not directly contact;

[0008] S2: mixing and beating the lithium leaching residue and water to obtain lithium-rich brine and silicon-aluminum-rich leaching residue after filtration.

[0009] The mechanism of the method is as follows:

[0010] The lithium residue and the acid are subjected to autoclave displacement reaction under a closed condition, so that lithium in the lithium residue is released by the action of the concentrated acid, while avoiding the reaction of the concentrated acid with the lithium residue at room temperature, ensuring the effectiveness and safety of the reaction. Under autoclave displacement reaction, the hydrogen ion (H + ) in the concentrated acid reacts with the lithium ion (Li + ) in the lithium compound (such as lithium aluminum mineral or lithium salt) to form a soluble lithium salt (such as LiCl, Li2SO4, etc.), while other ions (such as sodium, potassium, calcium, etc.) can also be displaced by anions (such as chloride ion Cl-, sulfate ion SO4 2- , nitrate ion NO3 - , etc.) in the concentrated acid to form other soluble salts. Due to the elevated steam pressure of the autoclave displacement reaction, the reaction is accelerated, and the generation of steam provides sufficient energy to fully react the lithium compound with the acid, while helping to dissolve the generated lithium salt in the liquid phase. After the displacement reaction is completed, water is added and stirred to leach the products after the reaction. After the reaction is completed, water is added to dilute the reaction products. The addition of water helps to further dissolve and extract the lithium salt to form a lithium-rich brine solution, while the solid residue (such as silicon-aluminum-rich residue) is separated.

[0011] According to the embodiments of the first aspect of the application, at least the following beneficial effects are achieved:

[0012] In the present application, the lithium residue and the acid do not directly contact, avoiding the reaction of the concentrated acid with the lithium residue at room temperature, and providing the minimum amount of water according to the filling degree of the materials in the container to achieve the required saturated steam pressure in the container. Through comparison experiments, it is proved that the leaching effect of autoclave displacement is improved by more than 10% compared with hydrothermal displacement under the same temperature and pressure. Through the autoclave leaching method, the problem of high liquid-solid ratio under hot pressure conditions is solved, which can effectively improve the acid leaching efficiency and reduce the consumption of acid and alkali.

[0013] According to some embodiments of the present application, in step S1, the autoclave displacement reaction is carried out under heating conditions.

[0014] According to some embodiments of the present application, in step S1, the heating method includes at least one of electric heating, oil bath, microwave and electromagnetic heating.

[0015] According to some embodiments of the present application, in step S1, the acid solution comprises at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0016] According to some embodiments of the present application, in step S1, when the acid solution is hydrochloric acid, the concentration is 36-38wt%.

[0017] According to some embodiments of the present application, in step S1, when the acid solution is sulfuric acid, the concentration is 96-98wt%.

[0018] According to some embodiments of the present application, in step S1, when the acid solution is nitric acid, the concentration is 68-70wt%.

[0019] According to some embodiments of the present application, in step S1, before the reaction, the method further comprises regulating the water content of the lithium residue to be no more than 25%.

[0020] The above water content increases the solubility of lithium and other metal ions, promotes effective leaching reaction, maintains stable reaction conditions, and avoids the generation of side reactions.

[0021] According to some embodiments of the present application, in step S1, the regulating method comprises wetting the surface of the lithium residue particles with water.

[0022] Wetting the surface of the lithium residue particles with water can improve reaction contact, improve flowability and uniformity, enhance heat conduction, and control reaction rate, etc.

[0023] According to some embodiments of the present application, in step S1, the mass ratio of the lithium residue to the acid solution is 1:002-0.1, based on the dry weight of the lithium residue.

[0024] According to some embodiments of the present application, in step S1, the temperature of the autoclaving displacement reaction is 100-120℃.

[0025] According to some embodiments of the present application, in step S1, the time of the autoclaving displacement reaction is 15-120min.

[0026] According to some embodiments of the present application, in step S1, the pH value of the lithium leaching residue is 3-4.

[0027] According to some embodiments of the present application, in step S1, the solid-liquid ratio of the lithium residue to the water is 1:(0.5-2), based on the dry weight of the lithium residue.

[0028] According to some embodiments of the present application, in step S1, the method further comprises adjusting the pH value of the lithium leaching residue to be above 4.

[0029] Under the above conditions, the pH value above 4 can effectively reduce the dissolution of fluorine, aluminum, etc., and ensure the purity of the lithium-rich brine.

[0030] According to some embodiments of the present application, the lithium-rich brine is further purified.

[0031] According to some embodiments of the present application, the purification method comprises concentrating and purifying lithium extraction.

[0032] According to some embodiments of the present application, the silicon and aluminum-rich leaching residue is added to step S1 for autoclave replacement reaction.

[0033] In step S2, the lithium-rich brine can be further concentrated, purified and extracted for lithium, and the residual liquid after lithium extraction is recycled for leaching. The thallium, beryllium, sodium and potassium in the residual liquid are enriched to a certain extent and then removed by step-by-step purification. After ball milling, the silicon and aluminum-rich residue is treated again by step S1 and step S2, further improving the leaching rate of lithium. The final leaching residue can be used as concrete aggregate, ceramic raw material, cement clinker raw material, etc. DETAILED DESCRIPTION

[0034] The concept and technical effects of the present application will be described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0035] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0036] Unless otherwise specified, "room temperature" in the present application means 25℃±5℃.

[0037] Unless otherwise specified, "about" in the present application means that the allowable error is within ±2%.

[0038] Unless otherwise specified, the specific conditions in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not marked with the manufacturer, which are conventional products that can be purchased on the market.

[0039] The first aspect of the embodiments of the present application provides a lithium residue autoclave leaching method, comprising the following steps:

[0040] S1: performing a steam pressure replacement reaction on the lithium residue and an acid solution under saturated vapor pressure to obtain a lithium leaching residue;

[0041] The lithium residue and the acid solution do not directly contact;

[0042] S2: mixing and beating the lithium leaching residue and water, and then filtering to obtain lithium-rich brine and silicon-aluminum-rich leaching residue.

[0043] It should be noted that in the existing process, high liquid-solid ratio hot-pressing conditions, or too low pH value, or high temperature, or long reaction time, there are problems of limited processing capacity, large acid and alkali consumption, and high energy consumption. In the present application, the lithium residue and the acid are subjected to a steam pressure replacement reaction under a closed condition, so that the lithium in the lithium residue is released by the action of the concentrated acid, while avoiding the reaction of the concentrated acid with the lithium residue at room temperature, ensuring the effectiveness and safety of the reaction. Under the steam pressure replacement reaction, the concentrated acid reacts with the lithium compounds (such as lithium aluminum minerals or lithium salts) in the lithium residue. The hydrogen ions (H + ) in the concentrated acid react with the lithium ions (Li + ) in the lithium compounds to form soluble lithium salts (such as LiCl, Li2SO4, etc.), while releasing other ions (such as sodium, potassium, calcium, etc.) which can also be replaced by anions (such as chloride ions Cl - , sulfate ions SO4 2- , nitrate ions NO3 - , etc.) in the concentrated acid to form other soluble salts. Due to the elevated steam pressure of the steam pressure replacement reaction, the reaction is accelerated, and the generation of steam provides sufficient energy to allow the lithium compounds to fully react with the acid, while helping to dissolve the generated lithium salts in the liquid phase. After the replacement reaction is completed, water is added and stirred to leach the products after the reaction. After the reaction is completed, water is added to dilute the reaction products. The addition of water helps to further dissolve and extract lithium salts to form lithium-rich brine solution, while the solid residue (such as silicon-aluminum-rich residue) is separated.

[0044] In combination with the first aspect, in some embodiments of the present application, in step S1, the steam pressure replacement reaction is performed under heating conditions.

[0045] In combination with the first aspect, in some embodiments of the present application, in step S1, the heating method includes at least one of electric heating, oil bath, microwave, and electromagnetic heating.

[0046] In combination with the first aspect, in some embodiments of the present application, in step S1, the acid solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0047] In combination with the first aspect, in some embodiments of the present application, in step S1, when the acid solution is hydrochloric acid, the concentration is 36-38wt%.

[0048] With reference to the first aspect, in some embodiments of the present application, in step S1, when the acid solution is sulfuric acid, the concentration is 96-98 wt%.

[0049] With reference to the first aspect, in some embodiments of the present application, in step S1, when the acid solution is nitric acid, the concentration is 68-70 wt%.

[0050] With reference to the first aspect, in some embodiments of the present application, in step S1, before the reaction, the moisture content of the lithium residue is regulated to be no more than 25%.

[0051] The above moisture content improves the solubility of lithium and other metal ions, promotes effective leaching reaction, maintains the stability of the reaction condition, and avoids the generation of side reactions.

[0052] With reference to the first aspect, in some embodiments of the present application, in step S1, the regulation method comprises wetting the surface of the lithium residue particles with water.

[0053] Wetting the surface of the lithium residue particles with water can improve the reaction contact, improve the flowability and uniformity, enhance the heat conduction, and control the reaction rate, etc.

[0054] With reference to the first aspect, in some embodiments of the present application, in step S1, the mass ratio of the lithium residue to the acid solution is 1:002-0.1, based on the dry weight of the lithium residue.

[0055] With reference to the first aspect, in some embodiments of the present application, in step S1, the temperature of the autoclave replacement reaction is 100-120°C; and / or, the time of the autoclave replacement reaction is 15-120 min.

[0056] With reference to the first aspect, in some embodiments of the present application, in step S1, the pH value of the lithium leaching residue is 3-4.

[0057] With reference to the first aspect, in some embodiments of the present application, in step S1, the solid-liquid ratio of the lithium residue to the water is 1:(0.5-2), based on the dry weight of the lithium residue.

[0058] With reference to the first aspect, in some embodiments of the present application, in step S1, the pH value of the lithium leaching residue is regulated to be no more than 4.

[0059] Under the above conditions, the silicon and aluminum in the lithium-rich brine are purified, and at the same time, under the same conditions, the pH of the leaching slurry produced by the conventional leaching method is lower than that of the lithium leaching residue after the autoclave replacement reaction in the present application, indicating that the replacement reaction of hydrogen lithium, etc. is more effective and thorough under the saturated autoclave environment.

[0060] With reference to the first aspect, in some embodiments of the present application, it further comprises removing impurities from the lithium-rich brine.

[0061] With reference to the first aspect, in some embodiments of the present application, the method for removing impurities comprises concentrating the lithium removal.

[0062] With reference to the first aspect, in some embodiments of the present application, the method further comprises adding the silicon and aluminum enriched leaching residue into step S1 for autoclave replacement reaction.

[0063] With reference to the first aspect, in some embodiments of the present application, in step S2, the lithium-rich brine can be further concentrated to remove impurities and extract lithium, and the residual liquid after lithium extraction can be recycled for leaching. When the thallium, beryllium, sodium and potassium in the residual liquid reach a certain enrichment level, they can be removed by step-by-step purification. After ball milling, the silicon and aluminum enriched residue is treated again by steps S1 and S2, thereby further improving the leaching rate of lithium. The final leaching residue can be used as concrete aggregate, ceramic raw material, cement clinker raw material, etc.

[0064] Example 1

[0065] The present embodiment provides a lithium residue autoclave leaching method, specifically:

[0066] S1: Take 200g of lithium residue from a certain enterprise in Jiangxi, control the water content of the lithium residue to be 25%, and transfer it into a 1L pressure container. Add 15g of concentrated hydrochloric acid (mass concentration 68%) into the container. The concentrated hydrochloric acid is at the bottom of the lithium residue and does not directly contact the lithium residue. Add 10mL of deionized water into the container to form a saturated vapor pressure. Seal the container and heat it to 105℃ in an oil bath for 15min for replacement reaction.

[0067] S2: After the reaction is completed, add 750mL of deionized water and stir at 60rpm for 5min. Filter to obtain leaching liquid and leaching residue. Wash the leaching residue and use the washing liquid to make the leaching liquid to a constant volume of 800mL. Detect the pH value and lithium ion concentration, calculate the leaching rate, and detect the lithium content of the washed and dried leaching residue. The test results are shown in Table 1.

[0068] Example 2

[0069] The present embodiment provides a lithium residue autoclave leaching method, specifically:

[0070] S1: Take 200g of lithium residue from a certain enterprise in Jiangxi, control the water content of the lithium residue to be 25%, and transfer it into a 1L pressure container. Add 15g of concentrated hydrochloric acid (mass concentration 68%) into the container. The concentrated hydrochloric acid is at the bottom of the lithium residue and does not directly contact the lithium residue. Add 10mL of deionized water into the container to form a saturated vapor pressure. Seal the container and heat it to 105℃ in an oil bath for 15min for replacement reaction.

[0071] S2: After the reaction, 750 mL of deionized water was added, and the leaching was stirred at 60 rpm for 5 min, and then the leaching liquid and leaching residue were obtained by filtration. The leaching residue was washed, and the leaching liquid was diluted to 800 mL with the washing liquid. The pH value and lithium ion concentration were detected, the leaching rate was calculated, and the lithium content of the leaching residue was detected after drying. The test results are shown in Table 1.

[0072] Comparative Example 1

[0073] The other conditions of the present comparative example 1 are the same as those of Example 1, except that only 10 mL of deionized water is not supplemented.

[0074] The comparison results are shown in Table 1, and the results show that the leaching efficiency of lithium, sodium and potassium is reduced without the appropriate amount of water to ensure the corresponding saturated steam pressure in the container.

[0075] Comparative Example 2

[0076] The other conditions of the present comparative example are the same as those of Example 1, except that 750 mL of deionized water and concentrated acid are added at the same time, and the lithium residue is directly immersed in the acid solution.

[0077] The comparison results are shown in Table 1, and the results show that the leaching efficiency of lithium, sodium and potassium is reduced when the steam pressure leaching is replaced by immersion leaching, and at the same time, silicon and aluminum are also leached due to the low end point pH of the leaching liquid.

[0078] Comparative Example 3

[0079] The other conditions of the present comparative example 3 are the same as those of Example 2, except that the container is opened to maintain a normal pressure environment in the container.

[0080] The comparison results are shown in Table 1, and the results show that the leaching efficiency of lithium, sodium and potassium is reduced without the corresponding saturated steam pressure in the container.

[0081] Comparative Example 4

[0082] The other conditions of the present comparative example 4 are the same as those of Example 2, except that deionized water is used instead of concentrated sulfuric acid.

[0083] The comparison results are shown in Table 1. The results show that the leaching efficiency of lithium, sodium and potassium is significantly reduced when the lithium residue is directly leached by steam pressure with water.

[0084] Test Example

[0085] Table 1. Element content detection of examples and comparative examples

[0086]

[0087] From the test results in the comparative example 1, it can be seen that the leaching efficiency of lithium, sodium and potassium is decreased without appropriate amount of water to ensure the corresponding saturated vapor pressure in the container. From the test results in the comparative example 2, it can be seen that the leaching efficiency of lithium, sodium and potassium is decreased when the steam pressure leaching is changed into immersion leaching, and at the same time, silicon and aluminum are also leached due to the low end point pH of the leaching solution. From the test results in the comparative example 3, it can be seen that the leaching efficiency of lithium, sodium and potassium is decreased without the corresponding saturated vapor pressure in the container. From the test results in the comparative example 4, it can be seen that the leaching efficiency of lithium, sodium and potassium is significantly decreased when the lithium residue is directly leached by steam pressure with water.

Claims

1. A pressure leaching process for lithium residue, characterized by, The method comprises the following steps: S1: performing autoclave displacement reaction of lithium residue and acid solution under saturated vapor pressure to obtain lithium leaching residue; before the reaction, the moisture content of the lithium residue is regulated to be not higher than 25%, and the method for regulating the moisture content comprises wetting the particle surface of the lithium residue with water; the lithium residue and the acid solution do not directly contact; the acid solution comprises at least one of hydrochloric acid, sulfuric acid and nitric acid; when the acid solution is hydrochloric acid, the concentration is 3 6-38wt%; when the acid solution is sulfuric acid, the concentration is 9 6-98wt%; when the acid solution is nitric acid, the concentration is 6 8-70wt%; The temperature of the autoclave displacement reaction is 100-120℃; The pH value of the lithium leaching residue is 3-4; S2: mixing and beating the lithium leaching residue and water, and then filtering to obtain lithium-rich brine and silicon-aluminum-rich leaching residue.

2. The method of claim 1, wherein, In step S1, the time of the autoclave displacement reaction is 15-120min.

3. The method of claim 1, wherein, The solid-liquid ratio of the lithium residue and the water is 1: (0.5-2) based on the dry weight of the lithium residue.

4. The method of claim 1, wherein, The lithium-rich brine is further purified; and / or, the method for purifying the lithium-rich brine comprises concentrating and purifying to extract lithium.

5. The method of claim 1, wherein, The silicon-aluminum-rich leaching residue is further added to step S1 to perform autoclave displacement reaction.

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