A method for low-temperature acid-free leaching of lithium from clay-type lithium ore

Abstract

The invention discloses a method for low-temperature acid-free leaching of lithium from clay-type lithium ore, and belongs to the technical field of hydrometallurgy of low-grade clay-type lithium ore. The invention uses ammonium persulfate as a roasting aid, and the ammonium persulfate reacts chemically with the minerals in the clay-type lithium ore, changes the composition and structure of the clay-type lithium ore, effectively reduces the roasting temperature and the leaching temperature, and realizes low-temperature acid-free leaching with a roasting temperature of 400-450°C and a leaching temperature of 45-75°C. The invention uses ammonium persulfate as a roasting aid and water as a leaching agent, and has the characteristics of low corrosiveness and safety. The roasting temperature of the invention is 400-450°C and the leaching temperature is 45-75°C, which has the advantage of low temperature and can effectively reduce energy consumption. The leaching rate of aluminum and silicon in the leaching solution of the invention is less than 20%, which effectively reduces the difficulty of subsequent lithium salt preparation and purification.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy of low-grade clay-type lithium ore, and in particular relates to a method for low-temperature acid-free leaching of lithium from clay-type lithium ore. Background Art

[0002] At present, there are problems such as high roasting temperature (600-1000°C) and large amount of acid used in the extraction of lithium from clay-type lithium ore. For example, patent CN202310036262.2 discloses a method for leaching clay lithium ore, which proposes roasting the clay lithium ore, and then mixing the roasted ore powder and water-soluble fluoride salt for leaching. This method can effectively leach lithium from clay lithium ore, but fluoride salt is expensive, and the roasting temperature is 500-600°C, the roasting temperature is high, and the energy consumption is large. For example, patent CN202310797059.7 discloses a method for extracting lithium from clay-type lithium ore, which proposes mixing clay-type lithium ore with acid solution to remove iron, and then mixing iron-removing lithium slag with ammonium sulfate for aging and dissolving to extract lithium. The aging temperature of this method is 300-600°C, which has the advantage of low temperature, but the clay lithium ore needs to be pretreated with acid. The use of a large amount of acid is not only easy to corrode equipment, but also has safety hazards.

[0003] Therefore, there is an urgent need for a lithium extraction method with low roasting temperature and no need for acid leaching to solve the above problems. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a method for low-temperature acid-free leaching of lithium from clay-type lithium ore.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The invention provides a method for leaching lithium from a clay-type lithium ore at low temperature and without acid. The method comprises the following steps: using ammonium persulfate as a roasting aid and water as a leaching agent to roast and leach the clay-type lithium ore to obtain a lithium-containing leachate.

[0007] Preferably, the mass ratio of the clay-type lithium ore to ammonium persulfate is 1:(0.3-0.5).

[0008] Preferably, the calcination temperature is 400-450° C. and the calcination time is 1-2 hours.

[0009] Preferably, the liquid-to-solid ratio of the leaching is (3-5):1.

[0010] Preferably, the leaching temperature is 45-75° C. and the leaching time is 1-2 hours.

[0011] Preferably, the lithium grade of the clay-type lithium ore is ≤0.3%.

[0012] Preferably, particles with a diameter of -0.074 mm account for 70-80% of the clay-type lithium ore.

[0013] Preferably, the leaching rate of lithium in the lithium-containing leaching solution is 70-90%.

[0014] Preferably, the method comprises the following steps:

[0015] (1) crushing and grinding clay-type lithium ore to obtain a grinding product;

[0016] (2) mixing the ground ore product obtained in step (1) with ammonium persulfate uniformly, and then roasting the mixture to obtain a roasted clay-type lithium ore;

[0017] (3) Leaching the calcined clay-type lithium ore obtained in step (2) with water to obtain a lithium-containing leachate.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] The present invention uses ammonium persulfate as a roasting aid, and the ammonium persulfate chemically reacts with minerals in the clay-type lithium ore. The roasting process changes the components and mineral crystal structure of the clay-type lithium ore, effectively reduces the roasting temperature and the leaching temperature, and realizes low-temperature acid-free leaching with a roasting temperature of 400-450°C and a leaching temperature of 45-75°C.

[0020] The invention uses ammonium persulfate as a roasting aid and water as a leaching agent, and has the characteristics of low corrosivity and safety.

[0021] The roasting temperature of the invention is 400-450° C. and the leaching temperature is 45-75° C., which has the advantage of low temperature and can effectively reduce energy consumption.

[0022] The leaching rate of aluminum and silicon in the leaching solution of the present invention is lower than 20%, which effectively reduces the difficulty of subsequent lithium salt preparation and purification. The main gangue minerals in clay-type lithium ore are silicon- and aluminum-containing minerals such as kaolinite and gibbsite. The existing method for enhancing lithium leaching will also enhance the leaching of silicon and aluminum, affecting the subsequent purification.

[0023] The lithium leaching method provided by the present invention has a simple process flow, low energy consumption and cost per unit processing amount, easy control of product properties, and easy realization of large-scale equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0025] Figure 1 This is a process flow chart of the method for low-temperature acid-free leaching of lithium from clay-type lithium ore in Example 1-2. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The embodiment of the present invention provides a method for low-temperature acid-free leaching of lithium from a clay-type lithium ore, wherein ammonium persulfate is used as a roasting aid and water is used as a leaching agent to roast and leach the clay-type lithium ore to obtain a lithium-containing leachate.

[0029] The present invention uses ammonium persulfate as a roasting aid, and the ammonium persulfate reacts chemically with minerals in the clay-type lithium ore, thereby changing the composition and structure of the clay-type lithium ore minerals, effectively reducing the roasting temperature and the leaching temperature, and realizing low-temperature acid-free leaching at a roasting temperature of 400-450° C. and a leaching temperature of 45-75° C. In addition, ammonium persulfate has the characteristics of low corrosivity and safety.

[0030] In a preferred embodiment, ammonium persulfate reacts with minerals in clay-type lithium ore as follows:

[0031] 3(NH4)2S2O8+3AlOOH→3NH4Al(SO4)2+N2+6H2O+NH3

[0032] 6(NH4)2S2O8+3Al2Si2O5(OH)4→6NH4Al(SO4)2+2N2+15H2O+6SiO2+2NH3

[0033] 21(NH4)2S2O8+4LiAl4(Si3Al)O 10 (OH)8→20NH4Al(SO4)2+48H2O+12SiO2+2Li2SO4+8NH3+7N2.

[0034] In a preferred embodiment, the mass ratio of the clay-type lithium ore to ammonium persulfate is 1:(0.3-0.5). The present invention controls the amount of ammonium persulfate within the above range to ensure that the minerals in the clay-type lithium ore react fully with the ammonium persulfate. Too little ammonium persulfate cannot ensure that the minerals react fully, resulting in a low leaching rate. Too much ammonium persulfate will increase costs, aggravate the sintering of gangue minerals, and aggravate the leaching of impurity elements.

[0035] In a preferred embodiment, the calcination temperature is 400-450°C and the time is 1-2 hours. The present invention reduces the calcination temperature, has the advantage of low temperature, and can effectively reduce energy consumption.

[0036] In a preferred embodiment, the liquid-solid ratio of the leaching is (3-5): 1. The present invention uses water as a leaching agent, which has the advantages of low corrosiveness and safety. By controlling the liquid-solid ratio of the leaching within the above range, efficient leaching of lithium in clay-type lithium ore is achieved. Too little use of the leaching agent will weaken the migration of lithium elements, which is not conducive to the balance moving in the leaching direction. Too much use of the leaching agent will increase the processing volume and processing difficulty of subsequent solid-liquid separation.

[0037] In a preferred embodiment, the leaching temperature is 45-75°C and the time is 1-2 hours. The present invention reduces the leaching temperature, has the advantage of low temperature, and can effectively reduce energy consumption.

[0038] In a preferred embodiment, the lithium grade of the clay-type lithium ore is ≤0.3%.

[0039] In a preferred embodiment, particles of -0.074 mm in the clay-type lithium ore account for 70-80%.

[0040] In a preferred embodiment, the leaching rate of lithium in the lithium-containing leaching solution is 70-90%.

[0041] In a preferred embodiment, the steps include:

[0042] (1) crushing and grinding clay-type lithium ore to obtain a grinding product;

[0043] (2) mixing the ground ore product obtained in step (1) with ammonium persulfate uniformly, and then roasting the mixture to obtain a roasted clay-type lithium ore;

[0044] (3) Leaching the calcined clay-type lithium ore obtained in step (2) with water to obtain a lithium-containing leachate.

[0045] In a preferred embodiment, in step (1), the crushing equipment used for crushing includes a high-pressure roller, a jaw crusher or a disc crusher; and the particle size of the clay-type lithium ore after crushing is -10 mm.

[0046] In a preferred embodiment, in step (1), the grinding method is dry grinding; and the particles of -0.074 mm in the grinding product account for 70-80%.

[0047] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0048] Example 1

[0049] The main chemical composition (by mass percentage) of a clay-type lithium ore in Yunnan is: Li 0.12%, SiO2 21.50%, Al2O3 55.97%, Fe 4.44%, CaO 0.16%, TiO2 2.20%, MgO 0.22%, K2O 0.11%, and Na2O 0.15%. The method for leaching lithium is carried out according to the following steps. The process flow is shown in Figure 1 :

[0050] (1) A jaw crusher is used to crush clay-type lithium ore to -5 mm, and then dry grinding is used to grind the ore to -0.074 mm particles accounting for 75%, thereby obtaining a grinding product.

[0051] (2) The ground ore product obtained in step (1) is mixed evenly with ammonium persulfate in a mass ratio of 1:0.4, and then placed in a roasting furnace and roasted at 450° C. for 2 h to obtain a roasted clay-type lithium ore.

[0052] (3) using water to leach lithium from the calcined clay-type lithium ore obtained in step (2), the leaching temperature is 50° C., the leaching time is 2 h, the liquid-to-solid ratio is 5:1, and a leaching solution with a lithium leaching rate of 71%, an aluminum leaching rate of 12%, and a silicon leaching rate of 8% is obtained.

[0053] Example 2

[0054] The main chemical composition (by mass percentage) of a clay-type lithium ore in Guizhou is: Li 0.17%, SiO2 18.75%, Al2O3 53.97%, Fe 5.44%, CaO 0.12%, TiO2 3.20%, MgO 0.34%, K2O 0.18%, Na2O 0.23%. The method of leaching lithium is carried out according to the following steps. The process flow is shown in Figure 1 :

[0055] (1) A jaw crusher is used to crush clay-type lithium ore to -6 mm, and then dry grinding is used to grind the ore to -0.074 mm particles accounting for 80%, thereby obtaining a grinding product.

[0056] (2) The ground ore product obtained in step (1) is mixed evenly with ammonium persulfate in a mass ratio of 1:0.5, and then placed in a roasting furnace and roasted at 400° C. for 2 h to obtain a roasted clay-type lithium ore.

[0057] (3) using water to leach lithium from the calcined clay-type lithium ore obtained in step (2), the leaching temperature is 75° C., the leaching time is 2 h, the liquid-to-solid ratio is 5:1, and a leaching solution with a lithium leaching rate of 81%, an aluminum leaching rate of 18%, and a silicon leaching rate of 13% is obtained.

[0058] Comparative Example 1

[0059] The difference from Example 1 is that ammonium sulfate is used as a roasting aid;

[0060] The method for leaching lithium is carried out according to the following steps:

[0061] (2) The ground ore product obtained in step (1) is mixed evenly with ammonium sulfate in a mass ratio of 1:0.4, and then placed in a roasting furnace for roasting at 500° C. for 2 h to obtain a roasted clay-type lithium ore.

[0062] Step (1) and step (3) are the same as in Example 1, and a leaching solution with a lithium leaching rate of 65%, an aluminum leaching rate of 10%, and a silicon leaching rate of 8% is obtained.

[0063] Comparative Example 2

[0064] The difference from Example 1 is that in step (2), the ground ore product obtained in step (1) and ammonium persulfate are evenly mixed in a mass ratio of 1:0.7, and the rest is the same as Example 1; a leachate with a lithium leaching rate of 72%, an aluminum leaching rate of 30%, and a silicon leaching rate of 25% is obtained.

[0065] Comparative Example 3

[0066] The difference from Example 1 is that in step (2), the ground ore product obtained in step (1) and ammonium persulfate are uniformly mixed in a mass ratio of 1:0.1, and the rest is the same as Example 1; a leaching solution with a lithium leaching rate of 45%, an aluminum leaching rate of 8%, and a silicon leaching rate of 5% is obtained.

[0067] Comparative Example 4

[0068] The difference from Example 1 is that in step (3), the liquid-to-solid ratio is 1:1, and the rest is the same as Example 1; a leaching solution with a lithium leaching rate of 50%, an aluminum leaching rate of 5%, and a silicon leaching rate of 3% is obtained.

[0069] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for low-temperature acid-free leaching of lithium from clay-type lithium ore, characterized in that: It consists of the following steps: (1) crushing and grinding clay-type lithium ore to obtain a grinding product; (2) mixing the ground ore product obtained in step (1) with ammonium persulfate uniformly, and then roasting to obtain a roasted clay-type lithium ore; the roasting temperature is 400-450° C., and the time is 1-2 h; (3) leaching the calcined clay-type lithium ore obtained in step (2) with water to obtain a lithium-containing leaching solution; the liquid-to-solid ratio of the leaching solution is (3-5):1; The mass ratio of the clay-type lithium ore to ammonium persulfate is 1:(0.3-0.5).

2. The method for low-temperature acid-free leaching of lithium from clay-type lithium ore according to claim 1, characterized in that: The leaching temperature is 45-75° C. and the leaching time is 1-2 hours.

3. The method for low-temperature acid-free leaching of lithium from clay-type lithium ore according to claim 1, characterized in that: The lithium grade of the clay-type lithium ore is ≤0.3%.

4. The method for low-temperature acid-free leaching of lithium from clay-type lithium ore according to claim 1, characterized in that: In the clay-type lithium ore, particles with a diameter of -0.074 mm account for 70-80%.

5. The method for low-temperature acid-free leaching of lithium from clay-type lithium ore according to claim 1, characterized in that: The leaching rate of lithium in the lithium-containing leaching solution is 70-90%.

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