Method and system for steam fluidization roasting of lepidolite

Abstract

The invention discloses a lepidolite steam fluidization roasting method and system, and belongs to the technical field of treatment methods of lithium-containing minerals. The roasting method provided by the invention comprises the following steps: S1, mixing lepidolite mineral powder with a sulfate auxiliary agent to prepare a roasted raw material, adding a fluorine fixing auxiliary agent, and mixing to prepare a mixture; s2, the mixture and fluidizing gas are subjected to preheating treatment; s3, the preheated mixture and the preheated fluidizing gas are fed into a fluidized bed roasting furnace to be subjected to a fluidized roasting reaction, and roasting clinker, a fluorine fixing auxiliary and thallium-containing tail gas are obtained through separation; and S4, carrying out cyclone preheating and wet defluorination on the thallium-containing tail gas, and reacting the thallium-containing tail gas with metal sulfide to prepare thallium sulfide. The method is environment-friendly and efficient, the lithium smelting slag amount and loss of harmful elements can be remarkably reduced, the utilization rate of lithium resources is increased, and the problem that hydrofluoric acid corrodes equipment in the acid leaching process is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of processing methods of lithium-containing minerals, and particularly relates to a lithium mica steam fluidization roasting method and system. BACKGROUND

[0002] Lithium and its compounds are widely used in the industrial fields of lithium batteries, ceramics, glass, aluminum smelting, medicine, etc. In recent years, with the wide application of lithium ion batteries in portable electronic devices, electric vehicles, space technology and national defense industry, the demand for lithium is increasing. China has rich lithium mica resources, but the grade is low, and the Li2O content is generally lower than 2wt%, which leads to the production of 30-60 tons of slag per ton of lithium carbonate. Moreover, a large amount of toxic elements such as fluorine, beryllium and thallium are left in the lithium smelting slag, causing serious environmental and safety risks. Therefore, how to reduce the amount of lithium mica smelting slag and the content of easily lost toxic components from the source is of great significance to the green and high-quality utilization of lithium resources in China.

[0003] At present, the commonly used lithium mica lithium extraction technology often adds a large amount of roasting additives (>35%), which leads to problems such as large amount of slag (30-60 tons of slag per ton of lithium carbonate), high energy consumption (950-1100℃), and low lithium recovery rate (<80%). In addition, high-temperature roasting (>950℃) also causes the transformation of toxic components such as fluorine, beryllium and thallium, which makes them easily enter the gas phase or liquid phase, increasing the difficulty of environmental management. Incomplete defluorination roasting also leads to the synchronous leaching of F ions during acid leaching, causing serious equipment corrosion problems.

[0004] Therefore, it is urgent to develop a more environmentally friendly and efficient method that can significantly reduce the amount of lithium smelting slag and the loss of harmful elements, and improve the utilization rate of lithium resources. SUMMARY

[0005] Therefore, the application provides a lithium mica steam fluidization roasting method and system, which is environmentally friendly and efficient, can significantly reduce the amount of lithium smelting slag and the loss of harmful elements, improve the utilization rate of lithium resources, and avoid the corrosion problem of hydrofluoric acid to equipment during the acid leaching process.

[0006] In a first aspect, the application provides a lithium mica steam fluidization roasting method, which comprises the following steps:

[0007] Step S1: mixing lithium mica powder with sulfate additives to prepare roasting raw materials, adding fluorine fixation additives, mixing to prepare mixed materials;

[0008] Step S2: preheating the mixed materials and fluidizing gas respectively to prepare preheated mixed materials and preheated fluidizing gas;

[0009] Step S3: sending the preheated mixed material and the preheated fluidizing gas to a fluidized bed calciner for fluidized calcination reaction, and separating to obtain calcined clinker, fluorine-fixing additive, and thallium-containing tail gas; the calcined clinker and fluorine-fixing additive are discharged from the upper layer and the bottom of the fluidized bed calciner, respectively;

[0010] Step S4: subjecting the thallium-containing tail gas to cyclone preheating and wet defluorination, and reacting it with metal sulfide to produce thallium sulfide.

[0011] By adopting the above technical solution, the steam fluidized roasting method of lepidolite provided by the present invention can realize the in-situ selective separation of roasted clinker and fluorine-fixing auxiliary agent, reduce the amount of smelting slag from the source, and recover toxic metals such as thallium.

[0012] The present application significantly improves the utilization efficiency of lithium resources through specific steps, and is environmentally friendly and efficient. Step S1 ensures the effective conversion of lithium and the fixation of fluorine in subsequent reactions by mixing lithium mica ore powder with sulfate additives and solid fluorine additives. Step S2 improves energy utilization efficiency and creates ideal conditions for fluidized roasting by preheating the mixture and fluidizing gas. Step S3 uses high-temperature steam as a fluidizing medium. Under the premise of adding specific additives, the lithium mica undergoes a selective roasting reaction, effectively converting lithium into a soluble form of lithium sulfate, while fluorine is captured and fixed by the solid fluorine additive to prevent it from entering the liquid phase or gas phase, thereby reducing the amount of smelting slag and reducing environmental risks. In addition, the in-situ separation of the roasted clinker and the solid fluorine additive reduces the generation of waste slag from the source and effectively recovers toxic metals such as thallium. Finally, step S4 further purifies the tail gas through cyclone preheating, wet defluorination and reaction with metal sulfides to generate thallium sulfide, preventing hydrofluoric acid from corroding the equipment. The present application uses sulfate additives to promote the conversion of lithium, thereby improving the lithium roasting conversion rate and subsequent leaching efficiency, and significantly improving the utilization rate of lithium resources.

[0013] Optionally, the heat of the roasted clinker is cooled and recovered and used to preheat water vapor to generate high-temperature steam.

[0014] By adopting the above technical solution, the present application recovers the heat of roasting clinker to preheat water vapor, which can improve energy utilization efficiency, reduce energy consumption, and promote environmental protection.

[0015] Optionally, the method further comprises: step S5: cooling the roasted clinker, leaching the cooled roasted clinker with sulfuric acid, and filtering to obtain a leaching solution containing lithium, rubidium, and cesium and a leaching residue;

[0016] Step S6: adding a complexing agent to the lithium-containing rubidium-cesium leachate to obtain aluminum salt particles and a lithium-rich solution;

[0017] Step S7: leaching the aluminum salt particles with dilute sulfuric acid to obtain aluminum sulfate and the complexing agent.

[0018] By adopting the technical scheme, the calcined clinker after cooling in step S5 is easier to follow-up leaching operation, and the leaching efficiency is high by using sulfuric acid leaching. The complexing agent in step S6 is coordinated with aluminum ions to form micron-sized aluminum salt particles with low specific surface area, and the adsorption amount of lithium ions is low, effectively reducing the loss of lithium. The aluminum salt particles in step S7 can react with dilute sulfuric acid to obtain the complexing agent again, realizing recycling.

[0019] Optionally, in step S1, at least one of the following conditions is met:

[0020] (1) the weight ratio of the lepidolite powder and the sulfate additive is 1:0.1-0.5;

[0021] (2) the particle size of the calcined raw material is 0.03mm-0.45mm;

[0022] (3) the sulfate additive is a sulfate of Na, K, Ca or Fe;

[0023] (4) the fluorine fixation additive is a mixture of at least one of oxides, hydroxides of Ca, Al, Mg, Zn, Fe, Cu, Ni, Co, Ti, W, Mo.

[0024] By adopting the technical scheme, the weight ratio of the lepidolite powder and the sulfate additive is controlled, the reaction efficiency is improved, unnecessary impurity ions are avoided, and by-products are reduced, thereby facilitating subsequent processing. The particle size of the calcined raw material is controlled, so that it has a proper specific surface area, which is beneficial to the rapid transfer of heat and gas, accelerates the calcination reaction, and at the same time avoids uneven fluidization, affecting the efficiency. The sulfate additive used in the present application can promote the release of lithium to meet the subsequent leaching requirements. The fluorine fixation additive of the present application can stabilize and solidify fluorine in the solid product, significantly reducing the volatilization and migration of fluorine, avoiding entering the tail gas or leaching liquid, and producing hydrofluoric acid to corrode the equipment and pollute the water body. And multi-component complex is used, which can further enhance the solidification ability and improve the fluorine fixation stability.

[0025] Optionally, in step S1, the particle size of the fluorine fixation additive is 0.5mm-3mm.

[0026] By adopting the technical scheme, the particle size of the fluorine fixation additive is controlled, which can maintain a good fluidization state and ensure uniform distribution, thereby improving the overall reaction efficiency.

[0027] Optionally, in step S2, the temperature of the preheated mixture is 800℃-1000℃; and the temperature of the preheated fluidizing gas is 950℃-1200℃.

[0028] By adopting the technical scheme, the temperatures of the preheated mixture and the fluidizing gas are controlled respectively, energy consumption is reduced, lithium conversion rate and fluorine fixation rate are improved by optimizing reaction kinetics conditions.

[0029] Optionally, step S3 satisfies at least one of the following conditions:

[0030] (1) the content of water vapor in the preheated fluidizing gas is > 10 vol%;

[0031] (2) the reaction temperature of the calcination reaction is 900-1100℃, and the reaction time is 0.1-0.5h;

[0032] (3) the linear velocity of the preheated fluidizing gas is 0.2-1.2m / s.

[0033] By adopting the technical scheme, the content of water vapor in the preheated fluidizing gas is controlled, the fluidization state is improved, heat is transferred more uniformly, and the calcination reaction is promoted. The calcination reaction temperature and time are controlled, which is conducive to promoting effective conversion of lithium and ensuring stable solidification of fluorine, while avoiding volatilization of toxic metals. The linear velocity of the preheated fluidizing gas is controlled, so that the calcined raw material is in a turbulent fluidization region, the reaction is more complete, while the fluorine fixation aid is in a bubbling fluidization region, which is convenient for removal from the bottom, realizes selective fluidization and in-situ separation, and does not require additional separation equipment.

[0034] Optionally, step S4 satisfies at least one of the following conditions:

[0035] (1) the metal sulfide includes at least one of WS2, MoS2, FeS2, NiS2, CoS2, TiS2, CuS, and ZnS;

[0036] (2) the particle size of the metal sulfide is 0.1-3mm, and the reaction temperature is 120-500℃;

[0037] (3) the wet defluorination includes: using a metal hydroxide solution to absorb HF gas and generate a metal fluoride, and the reaction temperature is 50-200℃.

[0038] By adopting the technical scheme, the metal sulfide selected by the application can effectively convert thallium ions in thallium-containing tail gas into Tl2S3 or Tl2S, thereby realizing fixation of thallium. The particle size and reaction temperature of the metal sulfide are further controlled, which helps to increase the specific surface area and promote contact and reaction between thallium and the metal sulfide. The wet defluorination can efficiently remove HF gas, avoiding fluorine pollution and corrosion of equipment.

[0039] Optionally, in step S5, the sensible heat of the calcined clinker during cooling can be used to preheat the fluidizing gas in step S2.

[0040] The concentration of the sulfuric acid is 0.1-5 mol / L; the solid-liquid ratio of the leaching process is 0.05-0.5:1, and the leaching time is 0.5-3 h.

[0041] By using the above technical solution, the sensible heat of the calcined clinker during cooling is used to preheat the fluidizing gas, which can improve the energy utilization rate and reduce the energy consumption. The application controls the concentration of sulfuric acid to ensure effective leaching of lithium while avoiding unnecessary side reactions. The appropriate solid-liquid ratio and leaching time help to improve the leaching efficiency.

[0042] Optionally, in step S7, the concentration of the dilute sulfuric acid is 0.5-1.6 mol / L.

[0043] By using the above technical solution, the application controls the concentration of dilute sulfuric acid in step S7, which can realize the reuse of aluminum salt while avoiding the destruction of the coordination agent, and also ensures the recycling of the coordination agent.

[0044] In a second aspect, the application provides a system for lithium mica steam fluidized calcination, comprising:

[0045] A mixer for mixing calcination raw materials and fluorine fixation aids;

[0046] A feeding subsystem for conveying the material mixed by the mixer, the feeding subsystem being connected to the mixer;

[0047] A preheating subsystem for preheating the mixed material, the preheating subsystem being connected to the feeding subsystem;

[0048] A fluidized calcination subsystem for fluidized calcination reaction of the preheated mixed material, the fluidized calcination subsystem being connected to the preheating subsystem;

[0049] A leaching subsystem for leaching the calcined clinker to obtain leaching liquid and leaching residue;

[0050] An aluminum removal subsystem for removing aluminum from the leaching liquid to obtain aluminum salt particles and a lithium-rich solution;

[0051] A lithium precipitation subsystem for lithium precipitation treatment of the lithium-rich solution to obtain lithium carbonate products.

[0052] By adopting the technical scheme, the lithium mica fluidized roasting system can directly process fine lithium mica ore, can broaden the particle size range of the processed lithium mica ore powder, can couple a sulfate additive to strengthen the roasting reaction efficiency of the lithium mica, and can realize in-situ selective separation of the roasting clinker and the added solid fluorine additive, thereby reducing the smelting slag quantity from the source.

[0053] The system integrates multiple functional modules from raw material mixing, preheating, roasting reaction to subsequent lithium extraction by leaching, aluminum removal and purification, and final lithium precipitation to prepare lithium carbonate products. First, the mixer performs preliminary mixing to provide a good basis for subsequent roasting reaction. The feeding subsystem delivers the mixed material prepared by the mixer to the preheating subsystem. The preheating subsystem preheats the mixed material and fluidizing gas respectively, saving energy and improving overall thermal efficiency. The fluidized roasting subsystem causes the lithium mica to undergo roasting reaction under the action of high temperature and fluidizing gas, generates roasting clinker, and realizes in-situ separation of the solid fluorine additive and the roasting clinker.

[0054] The leaching subsystem performs sulfuric acid leaching on the roasting clinker to extract valuable metals such as lithium, rubidium and cesium, and obtains a lithium-containing leaching solution and a leaching residue. By controlling the acid concentration, solid-liquid ratio and leaching time, efficient lithium extraction is realized. The aluminum removal subsystem adds a complexing agent to the leaching solution to selectively remove aluminum ions and separate to obtain a lithium-rich solution. Finally, the lithium precipitation subsystem performs lithium precipitation treatment on the lithium-rich solution to obtain lithium carbonate products.

[0055] Optionally, it further comprises a gas absorption subsystem connected to the fluidized roasting subsystem for removing thallium from the thallium-containing tail gas.

[0056] A roasting clinker cooling subsystem connected to the fluidized roasting subsystem for cooling the roasting clinker.

[0057] An air induction subsystem comprising an air induction fan connected to the gas absorption subsystem for discharging the purified gas generated after the thallium is removed from the thallium-containing tail gas into the atmosphere.

[0058] By adopting the above technical scheme, the application further comprises a gas absorption subsystem, which can significantly reduce the concentration of thallium in the tail gas, realize resource recycling of toxic metals, and reduce environmental risks. The roasting clinker cooling subsystem can recover waste heat to preheat the fluidizing gas, improve energy utilization, and reduce energy consumption, while creating suitable temperature conditions for subsequent sulfuric acid leaching. The air induction fan can ensure that the tail gas is discharged smoothly and prevent harmful gas leakage.

[0059] Optionally, at least one of the following conditions is met:

[0060] (1) the fluidized roasting subsystem comprises a feeding valve, a fluidized bed roaster (5), a roaster cyclone separator, and a discharging valve, the feeding port of the fluidized bed roaster (5) is connected with the feeding subsystem through the feeding valve, the discharging port of the fluidized bed roaster (5) is connected with the roasting clinker cooling subsystem through the discharging valve, the gas inlet of the roaster cyclone separator is connected with the gas outlet of the fluidized bed roaster (5), and the gas outlet of the roaster cyclone separator is connected with the gas inlet of the first combustion chamber (11);

[0061] (2) the gas absorption subsystem further comprises a thallium absorption device (14), the thallium absorption device (14) is connected with the tail gas outlet of the bag-type dust collector (13), and the gas outlet of the thallium absorption device (14) is connected with the gas inlet of the induced draft fan (15);

[0062] (3) the fluidized bed roaster (5) is a multi-stage structure fluidized bed, and a transverse baffle internal component is arranged in the bed, preferably 2-5 transverse baffles, for regulating and realizing the separation of lithium mica powder and roasting additives;

[0063] (4) the powder preheating subsystem comprises a first combustion chamber (11), a cyclone preheater (4), and a cyclone separator, the gas outlet of the first combustion chamber (11) is connected with the gas inlet of the cyclone preheater (4), the gas outlet of the cyclone preheater (4) is connected with the gas inlet of the cyclone separator, the feeding port of the cyclone preheater (4) is connected with the feeding subsystem, and the discharging port of the cyclone preheater (4) is connected with the roasting subsystem through a valve;

[0064] (5) the cyclone preheater (4) is a 2-4 stage cyclone preheater;

[0065] (6) the discharging port of the cyclone separator is connected with the feeding port of the cyclone preheater (4), and the gas outlet of the cyclone separator is connected with the gas inlet of the bag-type dust collector (13);

[0066] (7) the bag-type dust collector (13) is connected with the feeding subsystem through a discharging machine;

[0067] (8) the feeding subsystem comprises a mixer (1), a raw material bin (2), and a screw feeder (3), the discharging port of the mixer (1) is connected with the feeding port of the raw material bin (2), the discharging port of the raw material bin (2) is connected with the feeding port of the screw feeder (3), and the discharging port of the screw feeder (3) is connected with the roasting raw material preheating subsystem;

[0068] (9) the gas absorption subsystem comprises a thallium absorption device (14), the thallium absorption device (14) is connected with the tail gas outlet of the bag-type dust collector (13), and the gas outlet of the thallium absorption device (14) is connected with the gas inlet of the induced draft fan (15);

[0069] (10) The air outlet of the cyclone preheating subsystem (4) is connected to the induced draft fan (15) through the bag filter (13) and the thallium absorption device (14);

[0070] (11) The roasting clinker cooling subsystem (6) includes a cyclone cooler and a cyclone cooling separator. The feed port of the cyclone cooler is connected to the fluidized bed roasting furnace (5) through a discharge valve, and the air outlet of the cyclone cooler is connected to the air inlet of the cyclone cooling separator.

[0071] (12) The gas outlet of the cyclone cooling separator is connected to the gas inlet of the fluidized bed roaster, and the discharge port of the cyclone cooling separator is connected to the cyclone cooler;

[0072] (13) The induced draft subsystem includes an induced draft fan (15);

[0073] (14) The roasted clinker discharge outlet of the roasted clinker cooling subsystem (6) is connected to the material inlet of the leaching unit (7), the outlet of the leaching unit (7) is connected to the inlet of the filtration unit (8), the outlet of the filtration unit (8) is connected to the inlet of the aluminum removal unit (9), and the outlet of the aluminum removal unit (9) is connected to the inlet of the lithium precipitation unit (10).

[0074] In summary, the present invention includes at least one of the following beneficial technical effects:

[0075] 1. The present invention provides a steam fluidized roasting method for lepidolite, which can achieve in-situ selective separation of roasted clinker and fluorine-fixing additive, reduce the amount of smelting slag from the source, and recover toxic metals such as thallium.

[0076] 2. The fluidized calcination system for lepidolite provided by the present invention can directly process fine-grained lepidolite ore, thereby broadening the particle size range of lepidolite ore powder that can be processed, and can enhance the calcination reaction efficiency of lepidolite by coupling calcination with sulfate additives.

[0077] 3. The present invention adopts a coordination dealuminization method to remove aluminum ions from the leachate to form aluminum salt particles with low specific surface area, which can reduce the loss of lithium ions during the leaching and dealuminization process; at the same time, through simple dilute sulfuric acid leaching, the coordination agent can be recycled to reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 This is a schematic structural diagram of a system for steam fluidized roasting of lepidolite provided in Example 1 of the present application.

[0079] Wherein: 1, mixer; 2, raw material bin; 3, screw feeder; 4, cyclone preheater; 5, fluidized bed roaster; 6, calcine cooling subsystem; 7, leaching unit; 8, filtration unit; 9, aluminum removal unit; 10, lithium precipitation unit; 11, first combustion chamber; 12, second combustion chamber; 13, bag filter; 14, thallium absorption device; 15, induced draft fan. DETAILED DESCRIPTION

[0080] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0081] Lithium in lepidolite ore exists in the form of complex fluorine aluminum silicate, and the mineral structure is very dense, which usually needs high temperature roasting to change it into loose structure. In theory, fine-grained lepidolite ore is conducive to promoting valuable elements such as lithium, rubidium, cesium, and toxic elements such as fluorine, beryllium and thallium into soluble salts or gaseous compounds. However, the existing mainstream salt roasting process (CN200910226661.5) generally uses a rotary kiln / tunnel kiln reactor, and air and natural gas combustion is used for steam roasting. Since the raw material used in the rotary kiln / tunnel kiln is millimeter-sized pellets or centimeter-sized lumps, the contact between water vapor and lepidolite material is not sufficient, which inhibits the adsorption of water vapor on the surface of lepidolite, the inward diffusion or migration of lithium-containing substances, resulting in low defluorination rate and incomplete phase dissociation of lithium ore. Therefore, it is necessary to increase the reaction temperature, and add a large amount of roasting additives (>35%), which leads to problems such as large amount of slag (30-60 tons of slag per ton of lithium carbonate), high energy consumption (950-1100℃), low lithium recovery rate (<80%) and so on. A large amount of lithium smelting slag containing toxic elements such as fluorine, beryllium and thallium cannot be utilized on a large scale and can only be temporarily stored in the factory, which has become a prominent problem in the development of salt roasting technology. In addition, high temperature roasting (>950℃) also causes the transformation of toxic components such as fluorine, beryllium and thallium, which makes them easily enter the gas phase or liquid phase, increasing the difficulty of environmental management. How to treat the roasting tail gas containing fluorine, beryllium and thallium and reduce the environmental risk is also a problem faced by the existing process technology.

[0082] Patents (CN106987708, CN105385844) disclose a method of adding CaO to strengthen the fluidization roasting of lepidolite, but the CaO and lepidolite roasting ore are mixed together after roasting, which leads to an increase in lithium smelting slag and a low utilization rate of fluorine resources. In addition, the calcine obtained by the above method needs to be roasted by sulfuric acid or leached by acid to obtain a high lithium leaching rate. However, due to incomplete defluorination roasting, F ions are leached simultaneously during acid leaching, which leads to serious equipment corrosion problems.

[0083] In order to solve the above problems, the present application proposes a steam fluidized calcination method for lepidolite in a first aspect, comprising the following steps:

[0084] Step S1: mixing lepidolite ore powder and sulfate additive to prepare roasted raw meal, adding fluorine-fixing additive, and mixing to prepare a mixture;

[0085] Step S2: preheating the mixed material and the fluidizing gas to obtain a preheated mixed material and a preheated fluidizing gas;

[0086] Step S3: sending the preheated mixed material and the preheated fluidizing gas to a fluidized bed calciner for fluidized calcination reaction, and separating to obtain calcined clinker, fluorine-fixing additive, and thallium-containing tail gas; the calcined clinker and fluorine-fixing additive are discharged from the upper layer and the bottom of the fluidized bed calciner, respectively;

[0087] Step S4: preheating the thallium-containing tail gas by cyclone and wet defluorination, and reacting the tail gas with metal sulfide to produce thallium sulfide.

[0088] In some embodiments, the method further comprises: step S5: cooling the roasted clinker, leaching the cooled roasted clinker with sulfuric acid, and filtering to obtain a leachate containing lithium, rubidium, and cesium and a leach residue;

[0089] Step S6: adding a complexing agent to the lithium-rubidium-cesium leaching solution to obtain aluminum salt particles and a lithium-rich solution;

[0090] Step S7: Leaching the aluminum salt particles with dilute sulfuric acid to obtain aluminum sulfate and a complexing agent.

[0091] In some embodiments, the weight ratio of the lepidolite mineral powder to the sulfate additive is 1:0.1-0.5, preferably 1:0.1-0.3, and more preferably 1:0.1-0.2.

[0092] In some embodiments, the particle size of the roasted raw meal is 0.03 mm to 0.45 mm.

[0093] In some embodiments, the sulfate builder is a sulfate of Na, K, Ca, or Fe.

[0094] In some embodiments, the fluorine-fixing auxiliary agent is a mixture of at least one of oxides and hydroxides of Ca, Al, Mg, Zn, Fe, Cu, Ni, Co, Ti, W, and Mo.

[0095] In some embodiments, in step S1 , the particle size of the fluorine-fixing auxiliary agent is 0.5 mm to 3 mm, preferably 0.5 mm to 2 mm, and more preferably 0.5 mm to 1 mm.

[0096] In some embodiments, in step S2, the temperature of the preheated mixture is 800-1000°C; and the temperature of the preheated fluidizing gas is 950-1200°C.

[0097] In some embodiments, the content of water vapor in the preheated fluidizing gas is >10 vol%.

[0098] In some embodiments, the reaction temperature of the calcination reaction is 900-1100°C, and the reaction time is 0.1-0.5 h.

[0099] In some embodiments, the linear velocity of the preheated fluidizing gas is 0.2-1.2 m / s, preferably 0.3-1.0 m / s, and further preferably 0.4-0.6 m / s.

[0100] In some embodiments, the metal sulfide comprises at least one of WS2, MoS2, FeS2, NiS2, CoS2, TiS2, CuS, and ZnS.

[0101] In some embodiments, the particle size of the metal sulfide is 0.1-3 mm, preferably 0.3-2 mm, and further preferably 0.5-1 mm.

[0102] In some embodiments, the reaction temperature is 120-500°C, preferably 150-400°C, and further preferably 180-300°C.

[0103] In some embodiments, the wet defluorination comprises: absorbing HF gas with a metal hydroxide solution to generate a metal fluoride, and the reaction temperature is 50-200°C, preferably 80-180°C, and further preferably 120-150°C.

[0104] In some embodiments, in step S5, the sensible heat of the calcined mixture when cooled can be used to preheat the fluidizing gas in step S2.

[0105] In some embodiments, the concentration of sulfuric acid is 0.1-5 mol / L, preferably 0.3-3 mol / L, and further preferably 0.5-1.5 mol / L.

[0106] In some embodiments, the solid-liquid ratio of the leaching process is 0.05-0.5:1.

[0107] In some embodiments, the leaching time is 0.5-3 h, preferably 0.5-2 h, and further preferably 0.5-1 h.

[0108] In a second aspect, the present application also provides a system for steam fluidized calcination of lepidolite, comprising:

[0109] A mixer for mixing raw material and fluorine-fixing auxiliary;

[0110] A feeding subsystem for conveying the mixed material from the mixer, the feeding subsystem being connected to the mixer;

[0111] A preheating subsystem for preheating the mixed material, the preheating subsystem being connected to the feeding subsystem;

[0112] A fluidized roasting subsystem for fluidized roasting the preheated mixed material, the fluidized roasting subsystem being connected to the preheating subsystem;

[0113] A leaching subsystem for leaching the roasted material to obtain leaching liquid and leaching residue;

[0114] An aluminum removal subsystem for removing aluminum from the leaching liquid to obtain aluminum salt particles and lithium-rich solution;

[0115] A lithium precipitation subsystem for precipitating lithium from the lithium-rich solution to obtain lithium carbonate product.

[0116] In some embodiments, a gas absorption subsystem is further included for removing thallium from the thallium-containing tail gas, the gas absorption subsystem being connected to the fluidized roasting subsystem.

[0117] In some embodiments, a roasted material cooling subsystem is further included for cooling the roasted material, the roasted material cooling subsystem being connected to the fluidized roasting subsystem.

[0118] In some embodiments, an air induction subsystem is further included, comprising an air induction fan for discharging the purified gas produced after the thallium removal of the thallium-containing tail gas into the atmosphere, the air induction fan being connected to the gas absorption subsystem.

[0119] In some embodiments, the fluidized roasting subsystem comprises a feeding valve, a fluidized bed roasting furnace (5), a roasting furnace cyclone separator, and a discharging valve, the feeding port of the fluidized bed roasting furnace (5) being connected to the feeding subsystem through the feeding valve, the discharging port of the fluidized bed roasting furnace (5) being connected to the roasted material cooling subsystem through the discharging valve, the gas inlet of the roasting furnace cyclone separator being connected to the gas outlet of the fluidized bed roasting furnace (5), and the gas outlet of the roasting furnace cyclone separator being connected to the gas inlet of the first combustion chamber (11).

[0120] In some embodiments, the gas absorption subsystem further comprises a thallium absorption device (14), the thallium absorption device (14) being connected to the tail gas outlet of the bag-type dust collector (13), and the gas outlet of the thallium absorption device (14) being connected to the gas inlet of the air induction fan (15).

[0121] In some embodiments, the fluidized bed roaster (5) is a multi-stage structure fluidized bed, with transverse baffle internal components arranged in the bed, preferably 2-5 stages of transverse baffles, for regulating and achieving separation of the lithium mica powder and the roasting additives.

[0122] In some embodiments, the powder preheating subsystem includes a first combustion chamber (11), a cyclone preheater (4), and a cyclone separator, the gas outlet of the first combustion chamber (11) is connected to the gas inlet of the cyclone preheater (4), the gas outlet of the cyclone preheater (4) is connected to the gas inlet of the cyclone separator, the feed inlet of the cyclone preheater (4) is connected to the feed subsystem, and the feed outlet of the cyclone preheater (4) is connected to the roasting subsystem through a feed valve.

[0123] In some embodiments, the cyclone preheater (4) is a 2-4 stage cyclone preheater.

[0124] In some embodiments, the feed outlet of the cyclone separator is connected to the feed inlet of the cyclone preheater (4), and the gas outlet of the cyclone separator is connected to the gas inlet of the bag-type dust collector (13).

[0125] In some embodiments, the bag-type dust collector (13) is connected to the feed subsystem through a feeder.

[0126] In some embodiments, the feed subsystem includes a mixer (1), a raw material bin (2), and a screw feeder (3), the feed outlet of the mixer (1) is connected to the feed inlet of the raw material bin (2), the feed outlet of the raw material bin (2) is connected to the feed inlet of the screw feeder (3), and the feed outlet of the screw feeder (3) is connected to the roasting raw material preheating subsystem.

[0127] In some embodiments, the gas absorption subsystem includes a thallium absorption device (14), the thallium absorption device (14) is connected to the tail gas outlet of the bag-type dust collector (13), and the gas outlet of the thallium absorption device (14) is connected to the gas inlet of an induced draft fan (15).

[0128] In some embodiments, the gas outlet of the cyclone preheating subsystem (4) is connected to the induced draft fan (15) through the bag-type dust collector (13) and the thallium absorption device (14).

[0129] In some embodiments, the roasting clinker cooling subsystem (6) includes a cyclone cooler and a cyclone cooling separator, the feed inlet of the cyclone cooler is connected to the fluidized bed roaster (5) through a feed valve, and the gas outlet of the cyclone cooler is connected to the gas inlet of the cyclone cooling separator.

[0130] In some embodiments, the gas outlet of the cyclone cooling separator is connected to the gas inlet of the fluidized bed roaster, and the feed outlet of the cyclone cooling separator is connected to the cyclone cooler.

[0131] In some embodiments, the air induction system comprises an air induction fan (15).

[0132] In some embodiments, the calcine cooling system (6) is connected to the material inlet of the leaching unit (7), the outlet of the leaching unit (7) is connected to the inlet of the filtering unit (8), the outlet of the filtering unit (8) is connected to the inlet of the aluminum removal unit (9), and the outlet of the aluminum removal unit (9) is connected to the inlet of the lithium precipitation unit (10).

[0133] The scheme of the present application is described below in combination with the following specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments are all from ordinary commercially available products, and the devices or equipment used are all purchased from conventional market sales channels. Specific embodiments

[0135] Embodiment 1

[0136] The structural schematic diagram of the system used in this embodiment for the steam fluidization roasting of lepidolite is shown in Figure 1 .

[0137] The system comprises a mixer, a feeding subsystem, a preheating subsystem, a fluidized roasting subsystem, a leaching subsystem, an aluminum removal subsystem, and a lithium precipitation subsystem. The mixer is connected to the feeding subsystem, the feeding subsystem is connected to the preheating subsystem, the preheating subsystem is connected to the fluidized roasting subsystem;

[0138] It also comprises a gas absorption subsystem, a calcine cooling subsystem, and an air induction fan. The gas absorption subsystem and the calcine cooling subsystem are connected to the fluidized roasting subsystem, and the air induction fan is connected to the gas absorption subsystem;

[0139] The fluidized roasting subsystem comprises a feeding valve, a fluidized bed roasting furnace 5, a roasting furnace cyclone separator, and a discharging valve. The feeding port of the fluidized bed roasting furnace 5 is connected to the feeding subsystem through the feeding valve, the discharging port of the fluidized bed roasting furnace 5 is connected to the calcine cooling subsystem through the discharging valve, the gas inlet of the roasting furnace cyclone separator is connected to the gas outlet of the fluidized bed roasting furnace 5, and the gas outlet of the roasting furnace cyclone separator is connected to the gas inlet of the first combustion chamber 11;

[0140] The gas absorption subsystem further comprises a thallium absorption device 14, which is connected to the tail gas outlet of the bag-type dust collector 13, and the gas outlet of the thallium absorption device 14 is connected to the gas inlet of the air induction fan 15;

[0141] The fluidized bed roasting furnace 5 is a multi-stage structure fluidized bed, and a transverse baffle internal component is arranged in the bed, which is a 4-stage transverse baffle, used for regulating and realizing the separation of lepidolite powder and roasting aids;

[0142] The ore powder preheating subsystem includes a first combustion chamber 11, a cyclone preheater 4, and a cyclone separator. The air outlet of the first combustion chamber 11 is connected to the air inlet of the cyclone preheater 4, the air outlet of the cyclone preheater 4 is connected to the air inlet of the cyclone separator, the feed port of the cyclone preheater 4 is connected to the feed subsystem, and the discharge port of the cyclone preheater 4 is connected to the roasting subsystem through a material valve; the cyclone preheater 4 is a four-stage cyclone preheater;

[0143] The discharge port of the cyclone separator is connected to the feed port of the cyclone preheater 4, and the air outlet of the cyclone separator is connected to the air inlet of the bag dust collector 13; the bag dust collector 13 is connected to the feeding subsystem via the discharge machine;

[0144] The feeding subsystem includes a mixer 1, a raw material bin 2 and a screw feeder 3. The discharge port of the mixer 1 is connected to the feed port of the raw material bin 2, the discharge port of the raw material bin 2 is connected to the feed port of the screw feeder 3, and the discharge port of the screw feeder 3 is connected to the roasting raw meal preheating subsystem;

[0145] The gas absorption subsystem includes a thallium absorption device 14, which is connected to the tail gas outlet of the bag filter 13, and the air outlet of the thallium absorption device 14 is connected to the air inlet of the induced draft fan 15;

[0146] The air outlet of the cyclone preheating subsystem 4 is connected to the induced draft fan 15 through the bag filter 13 and the thallium absorption device 14;

[0147] The roasting clinker cooling subsystem 6 includes a cyclone cooler and a cyclone cooling separator. The feed port of the cyclone cooler is connected to the fluidized bed roaster 5 through a discharge valve, and the air outlet of the cyclone cooler is connected to the air inlet of the cyclone cooling separator; the air outlet of the cyclone cooling separator is connected to the gas inlet of the fluidized bed roaster, and the discharge port of the cyclone cooling separator is connected to the cyclone cooler.

[0148] The induced draft subsystem includes an induced draft fan 15;

[0149] The clinker discharge outlet of the clinker cooling subsystem 6 is connected to the material inlet of the leaching unit 7, the outlet of the leaching unit 7 is connected to the inlet of the filtration unit 8, the outlet of the filtration unit 8 is connected to the inlet of the aluminum removal unit 9, and the outlet of the aluminum removal unit 9 is connected to the inlet of the lithium precipitation unit 10.

[0150] The above system is used to steam fluidize roasting and leaching lithium from lepidolite, including the following steps:

[0151] Step S1: the calcined raw material prepared from lithium mica powder + sulfate additive and fluorine fixation additive are mixed uniformly in a mixer 1 to prepare a mixture, which is fed into a raw material bin 2, and then fed into a cyclone preheater 4 through a screw feeder 3; natural gas and air in a first combustion chamber 11 are fully contacted to produce a high-temperature flue gas through combustion reaction; the high-temperature flue gas is fed into the cyclone preheating subsystem to preheat the mixture, so that the temperature of the mixture reaches 790 DEG C; wherein the weight ratio of lithium mica powder to sulfate additive is 1:0.1; the particle size of the calcined raw material is 0.1 mm; the sulfate additive is potassium sulfate; the fluorine fixation additive is calcium oxide, and the particle size of the fluorine fixation additive is 0.5 mm;

[0152] Step S2: natural gas and air in a second combustion chamber 12 are fully contacted to produce a high-temperature flue gas through combustion reaction, and the high-temperature flue gas is mixed with water vapor and air from a calcined clinker cooling subsystem; the temperature of the mixed gas reaches 1000 DEG C, and the mixed gas is fed into a fluidized bed calciner 5;

[0153] Step S3: the mixture discharged from the bottom outlet of the cyclone preheating system 4 is fed into the fluidized bed calciner 5 through a feeding valve, and is contacted with water vapor from the bottom of the fluidized bed calciner 5 to react; a plurality of supplemental heating burners are arranged in the fluidized section to control the reaction temperature at 980 DEG C; after 0.2 h of calcination reaction, calcined clinker and thallium-containing tail gas are obtained; at the same time, HF gas generated in the lithium mica calcination process reacts with the fluorine fixation additive to generate fluoride, which is discharged from the first-stage bottom discharge outlet of the fluidized bed calciner 5; the calcined defluorinated clinker generated in the fluidized bed calciner 5 is fed into a cyclone cooling subsystem 6 through a discharge valve, and the calcined defluorinated clinker is discharged after cooling; the heat generated during the cooling process is used for preheating air; wherein the content of water vapor in the preheated fluidized gas is 50 vol%; the linear velocity of the preheated fluidized gas is 0.6 m / s;

[0154] Step S4: the thallium-containing tail gas generated in the fluidized bed calciner 5 is separated by a calciner cyclone separator; the solid particles generated in the separation are returned to the fluidized bed calciner 5 for further calcination reaction; the gas generated in the separation is fed into the first combustion chamber 11; the thallium-containing tail gas from which dust is removed by a bag filter is fed into a thallium absorption device 14 for thallium removal; the thallium absorption device is loaded with a metal sulfide thallium adsorbent, and the temperature is 185 DEG C; the purified gas generated after the thallium removal is discharged into the atmosphere through an induced draft fan 15; wherein the metal sulfide is MoS2, and the particle size of the metal sulfide is 0.1 mm;

[0155] Step S5: the calcined clinker discharged from the calcined clinker cooling system 6 is fed into a leaching unit 7 for acid leaching using sulfuric acid; after the leaching, the leaching unit is fed into a filtration unit 8 to generate leaching residue and leaching solution; the leaching residue is washed with water to obtain a water washing liquid and a smelting residue; the water washing liquid is returned to the leaching unit for recycling after being supplemented with acid; wherein the concentration of sulfuric acid is 1.8 mol / L; the solid-liquid ratio in the leaching process is 0.1:1, and the leaching time is 2 h.

[0156] Step S6: The leaching solution discharged from the filtering unit 8 is sent to the aluminum removal unit 9 for aluminum removal. The coordination preparation is added to the filtrate, and the aluminum ions in the filtrate are controlled by coordination to form low specific surface area aluminum salt particles and a lithium-rich solution. The lithium-rich solution produced by aluminum removal is sent to the lithium precipitation unit to obtain lithium carbonate products.

[0157] Step S7: The low specific surface area aluminum salt particles produced by aluminum removal are washed with water and then added into a dilute sulfuric acid solution. The reaction of the low specific surface area aluminum salt particles with the dilute sulfuric acid can regenerate the coordination preparation, which is returned to the aluminum removal unit 9 for recycling. The concentration of the dilute sulfuric acid is 1.8 mol / L.

[0158] In this embodiment, the lithium leaching rate is 93%, the lithium comprehensive recovery rate is 85%, the rubidium and cesium leaching rate is 92%, the fluorine and thallium resource utilization rate is 90%, and the slag amount is reduced by 30%.

[0159] Example 2

[0160] The same system as in Example 1 is used for lithium mica steam fluidized roasting and leaching to extract lithium, including the following steps:

[0161] Step S1: The roasting raw material prepared from lithium mica powder + sulfate additive and the fluorine fixation additive are mixed uniformly in the mixer 1 to obtain a mixture, which is added to the raw material bin 2 and sent to the cyclone preheater 4 through the screw feeder 3. The natural gas in the first combustion chamber 11 is fully contacted with air to produce a high-temperature hot flue gas through combustion reaction. The high-temperature hot flue gas is sent to the cyclone preheating subsystem to preheat the mixture to a temperature of 880°C. The weight ratio of lithium mica powder to sulfate additive is 1:0.2. The particle size of the roasting raw material is 0.03 mm. The sulfate additive is calcium sulfate. The fluorine fixation additive is calcium oxide, and the particle size of the fluorine fixation additive is 0.8 mm.

[0162] Step S2: The natural gas in the second combustion chamber 12 is fully contacted with air to produce a high-temperature hot flue gas through combustion reaction, and the high-temperature hot flue gas is mixed with water vapor and air from the roasting clinker cooling subsystem. The temperature of the mixed gas reaches 1080°C, and the mixed gas is introduced into the fluidized bed roasting furnace 5.

[0163] Step S3: The mixture discharged from the bottom outlet of the cyclone preheating system 4 enters the fluidized bed roaster 5 through the feeding valve, and is contacted with and reacted with water vapor from the bottom of the fluidized bed roaster 5. A plurality of reheating burners are arranged in the fluidized section to control the reaction temperature at 980℃. After 0.2h of roasting reaction, roasted clinker and thallium-containing tail gas are obtained. At the same time, the HF gas generated in the lithium mica roasting process reacts with the fluorine-fixing additive to generate fluoride, which is discharged from the first bottom outlet of the fluidized bed roaster 5. The roasted defluorinated clinker generated in the fluidized bed roaster 5 enters the cyclone cooling subsystem 6 through the discharging valve, and the roasted defluorinated clinker after cooling is discharged. The heat generated in the cooling process is used for preheating air. The content of water vapor in the preheated fluidizing gas is 40vol%; the linear velocity of the preheated fluidizing gas is 0.8m / s;

[0164] Step S4: The thallium-containing tail gas generated in the fluidized bed roaster 5 is separated by the roaster cyclone separator. The solid particles generated in the separation are returned to the fluidized bed roaster 5 for further roasting reaction. The gas generated in the separation enters the first combustion chamber 11. The thallium-containing tail gas after dust removal by the bag-type dust collector enters the thallium absorption device 14 for thallium removal. The thallium absorption device is loaded with metal sulfide thallium adsorbent, and the temperature is 185℃. The purified gas generated after thallium removal is discharged into the atmosphere by the induced draft fan 15. The metal sulfide is CuS, and the particle size of the metal sulfide is 0.3mm.

[0165] Step S5: The roasted clinker discharged from the roasting clinker cooling system 6 is sent to the leaching unit 7 for acid leaching using sulfuric acid. After leaching, it is sent to the filtering unit 8 to generate leaching residue and leaching solution. After water washing, the leaching residue generates water washing liquid and smelting residue. The water washing liquid returns to the leaching unit after supplementing acid liquid for recycling. The concentration of sulfuric acid is 1.2mol / L. The solid-liquid ratio in the leaching process is 0.05:1, and the leaching time is 0.5h.

[0166] Step S6: The leaching solution discharged from the filtering unit 8 is sent to the aluminum removal unit 9 for aluminum removal. The coordination preparation is added to the filtrate to form low specific surface area aluminum salt particles and lithium-rich solution by coordination control method. The lithium-rich solution generated in the aluminum removal is sent to the lithium precipitation unit to obtain lithium carbonate product.

[0167] Step S7: The low specific surface area aluminum salt particles generated in the aluminum removal are washed with water and added into dilute sulfuric acid solution. The reaction with dilute sulfuric acid can re-obtain the coordination preparation, which returns to the aluminum removal unit 9 for recycling. The concentration of dilute sulfuric acid is 1.2mol / L.

[0168] In this embodiment, the lithium leaching rate is 95%, the lithium comprehensive recovery rate is 85%, the rubidium and cesium leaching rate is 92%, the fluorine and thallium resource utilization rate is 95%, and the residue amount is reduced by 15%.

[0169] Example 3

[0170] Lepidolite steam fluidized roasting and leaching for lithium was carried out using the same system as in Example 1, including the following steps:

[0171] Step S1: The roasting raw material prepared from the mixture of lepidolite ore powder and sulfate additive and the fluorine fixation additive were mixed uniformly in the mixer 1 to prepare a mixture, which was added into the raw material bin 2 and sent to the cyclone preheater 4 through the screw feeder 3. The natural gas was fully contacted with air in the first combustion chamber 11 to produce a high-temperature hot flue gas. The high-temperature hot flue gas was sent to the cyclone preheating subsystem to preheat the mixture, so that the temperature of the mixture reached 900℃. The weight ratio of the lepidolite ore powder to the sulfate additive was 1:0.3. The particle size of the roasting raw material was 0.2 mm. The sulfate additive was a mixture of potassium sulfate and calcium sulfate with a ratio of 1:3. The fluorine fixation additive was aluminum oxide, and the particle size of the fluorine fixation additive was 1.5 mm.

[0172] Step S2: The natural gas was fully contacted with air in the second combustion chamber 12 to produce a high-temperature hot flue gas, which was mixed with water vapor and air from the roasting clinker cooling subsystem. The temperature of the mixed gas reached 1200℃, and the mixed gas was introduced into the fluidized bed roaster 5.

[0173] Step S3: The mixture discharged from the bottom outlet of the cyclone preheating system 4 was introduced into the fluidized bed roaster 5 through the feeding valve and contacted with water vapor from the bottom of the fluidized bed roaster 5 to react. Multiple reheating burners were arranged in the fluidization section to control the reaction temperature at 1100℃. After 0.2 h of roasting reaction, the roasting clinker and the thallium-containing tail gas were obtained. At the same time, the HF gas generated in the lepidolite roasting process reacted with the fluorine fixation additive to generate fluoride, which was discharged from the first-stage bottom discharge outlet of the fluidized bed roaster 5. The roasting defluorination clinker generated in the fluidized bed roaster 5 was introduced into the cyclone cooling subsystem 6 through the discharge valve. The cooled roasting defluorination clinker was discharged. The heat generated during the cooling process was used for preheating air. The content of water vapor in the preheated fluidization gas was 30 vol%. The linear velocity of the preheated fluidization gas was 1.2 m / s.

[0174] Step S4: The thallium-containing tail gas generated in the fluidized bed roaster 5 was separated by the roaster cyclone separator. The solid particles generated in the separation were returned to the fluidized bed roaster 5 for further roasting reaction. The gas generated in the separation was introduced into the first combustion chamber 11. The thallium-containing tail gas after dust removal by the bag filter was introduced into the thallium absorption device 14 for thallium removal. The thallium absorption device was loaded with metal sulfide thallium adsorbent, and the temperature was 185℃. The purified gas generated after the thallium removal was discharged into the atmosphere through the induced draft fan 15. The metal sulfide was WS2, and the particle size of the metal sulfide was 3 mm.

[0175] Step S5: The roasted clinker discharged from the roasted clinker cooling system 6 is sent to the leaching unit 7 for acid leaching using sulfuric acid, and after leaching, it is sent to the filtering unit 8 for filtration to produce leaching residue and leachate; the leaching residue is washed with water to obtain water washing liquid and smelting slag, and the water washing liquid is returned to the leaching unit for recycling after being supplemented with acid; wherein, the concentration of sulfuric acid is 3 mol / L; the solid-liquid ratio of the leaching process is 0.5:1, and the leaching time is 1 hour.

[0176] Step S6: The leachate discharged from the filtration unit 8 is sent to the aluminum removal unit 9 for aluminum removal, and a coordination agent is added to the filtrate to coordinate the aluminum ions in the filtrate to form low specific surface area aluminum salt particles and a lithium-rich solution; the lithium-rich solution produced by aluminum removal is sent to the lithium precipitation unit to obtain a lithium carbonate product;

[0177] Step S7: The low specific surface area aluminum salt particles produced by aluminum removal are washed with water and added to a dilute sulfuric acid solution to react with the dilute sulfuric acid to obtain a complexing agent, which is returned to the aluminum removal unit 9 for recycling; wherein the concentration of the dilute sulfuric acid is 1.6 mol / L.

[0178] In this embodiment, the lithium leaching rate is 95.6%, the comprehensive lithium recovery rate is 86.5%, the rubidium and cesium leaching rate is 92.5%, the fluorine and thallium resource recovery rate is 94.5%, and the slag volume is reduced by 21%.

[0179] Example 4

[0180] The same system as in Example 1 was used to steam-fluidize lepidolite for calcination and leaching to extract lithium, comprising the following steps:

[0181] Step S1: The calcined raw meal prepared by lepidolite ore powder + sulfate additive and the fluorine-fixing additive are uniformly mixed in a mixer 1 to prepare a mixture, which is added to a raw material bin 2 and sent to a cyclone preheater 4 via a screw feeder 3. The natural gas and air in the first combustion chamber 11 are fully in contact with each other to generate a combustion reaction to produce high-temperature hot flue gas, which is sent to a cyclone preheating subsystem to preheat the mixture to a temperature of 1000°C. The weight ratio of the lepidolite ore powder to the sulfate additive is 1:0.5; the particle size of the calcined raw meal is 0.45mm; the sulfate additive is a mixture of calcium sulfate and sodium sulfate in a ratio of 10:1; the fluorine-fixing additive is zinc oxide, and the particle size of the fluorine-fixing additive is 1mm;

[0182] Step S2: In the second combustion chamber 12, natural gas and air are fully contacted to generate combustion reaction to produce high-temperature hot flue gas, which is mixed with water vapor and air from the clinker cooling subsystem. The mixed gas reaches a temperature of 1050°C and is passed into the fluidized bed roasting furnace 5;

[0183] Step S3: The mixture discharged from the bottom outlet of the cyclone preheating system 4 enters the fluidized bed roaster 5 through the feeding valve, and is contacted with and reacted with water vapor from the bottom of the fluidized bed roaster 5. A plurality of reheating burners are arranged in the fluidized section to control the reaction temperature at 1000℃. After the roasting reaction for 0.2h, roasted clinker and thallium-containing tail gas are obtained. At the same time, the HF gas generated in the lithium mica roasting process reacts with the fluorine-fixing additive to generate fluoride, which is discharged from the first bottom outlet of the fluidized bed roaster 5. The roasted defluorinated clinker generated by the fluidized bed roaster 5 enters the cyclone cooling subsystem 6 through the discharging valve, and the roasted defluorinated clinker after cooling is discharged. The heat generated during the cooling process is used for preheating air. The content of water vapor in the preheated fluidizing gas is 20vol%; the linear velocity of the preheated fluidizing gas is 0.2m / s;

[0184] Step S4: The thallium-containing tail gas generated by the fluidized bed roaster 5 is separated by the roaster cyclone separator. The solid particles generated by the separation are returned to the fluidized bed roaster 5 for further roasting reaction. The gas generated by the separation enters the first combustion chamber 11. The thallium-containing tail gas after dust removal by the bag-type dust collector enters the thallium absorption device 14 for thallium removal. The thallium absorption device is loaded with metal sulfide thallium adsorbent, and the temperature is 185℃. The purified gas generated after the thallium removal is discharged into the atmosphere by the induced draft fan 15. The metal sulfide is FeS2, and the particle size of the metal sulfide is 0.1mm.

[0185] Step S5: The roasted clinker discharged from the roasting clinker cooling system 6 is sent to the leaching unit 7 for acid leaching using sulfuric acid. After leaching, it is sent to the filtering unit 8 to generate leaching residue and leaching solution. After water washing, the leaching residue generates water washing liquid and smelting residue. The water washing liquid returns to the leaching unit after adding acid solution for recycling. The concentration of sulfuric acid is 5mol / L. The solid-liquid ratio of the leaching process is 0.3:1, and the leaching time is 0.6h.

[0186] Step S6: The leaching solution discharged from the filtering unit 8 is sent to the aluminum removal unit 9 for aluminum removal. The coordination preparation is added to the filtrate to form low specific surface area aluminum salt particles and lithium-rich solution by coordination control method. The lithium-rich solution generated by the aluminum removal is sent to the lithium precipitation unit to obtain lithium carbonate product.

[0187] Step S7: The low specific surface area aluminum salt particles generated by the aluminum removal are washed with water and added into dilute sulfuric acid solution. The reaction with dilute sulfuric acid can re-obtain the coordination preparation, which returns to the aluminum removal unit 9 for recycling. The concentration of dilute sulfuric acid is 1.6mol / L.

[0188] In this embodiment, the lithium leaching rate is 96%, the lithium comprehensive recovery rate is 87%, the rubidium and cesium leaching rate is 92%, the fluorine and thallium resource utilization rate is 95%, and the residue amount is reduced by 23%.

[0189] Example 5

[0190] The same system as in Example 1 was used to steam-fluidize lepidolite for calcination and leaching to extract lithium, comprising the following steps:

[0191] Step S1: The calcined raw meal prepared by lepidolite ore powder + sulfate additive and the fluorine-fixing additive are uniformly mixed in a mixer 1 to prepare a mixture, which is added to a raw material bin 2 and sent to a cyclone preheater 4 via a screw feeder 3. The natural gas and air in the first combustion chamber 11 are fully in contact with each other to generate a combustion reaction to produce high-temperature hot flue gas, which is sent to a cyclone preheating subsystem to preheat the mixture to a temperature of 1000°C. The weight ratio of the lepidolite ore powder to the sulfate additive is 1:0.1; the particle size of the calcined raw meal is 0.3mm; the sulfate additive is a mixture of potassium sulfate and sodium sulfate in a ratio of 1:3; the fluorine-fixing additive is a mixture of magnesium oxide and calcium oxide in a ratio of 1:5, and the particle size of the fluorine-fixing additive is 1.5mm.

[0192] Step S2: In the second combustion chamber 12, natural gas and air are fully contacted to generate combustion reaction to produce high-temperature hot flue gas, which is mixed with water vapor and air from the clinker cooling subsystem. The mixed gas reaches a temperature of 1200°C and is passed into the fluidized bed roasting furnace 5;

[0193] Step S3: The mixed material discharged from the bottom outlet of the cyclone preheating system 4 enters the fluidized bed roaster 5 through the feed valve, contacts and reacts with the water vapor from the bottom of the fluidized bed roaster 5, and a plurality of supplementary heat burners are provided in the fluidized section to control the reaction temperature at 1050°C. After the roasting reaction for 0.2h, roasted clinker and thallium-containing tail gas are obtained; at the same time, the HF gas generated during the roasting process of the lepidolite reacts with the fluorine-fixing auxiliary agent to generate fluoride, which is discharged from the first-stage bottom outlet of the fluidized bed roaster 5; the roasted defluorinated clinker produced by the fluidized bed roaster 5 enters the cyclone cooling subsystem 6 through the discharge valve, and the roasted defluorinated clinker is discharged after cooling, and the heat generated during the cooling process is used as preheated air; wherein, the water vapor content in the preheated fluidized gas is 40vol%; and the linear velocity of the preheated fluidized gas is 0.7m / s;

[0194] Step S4: The thallium-containing tail gas generated by the fluidized bed roaster 5 is separated by a cyclone separator of the roaster, and the solid particles generated by the separation are returned to the fluidized bed roaster 5 to continue the roasting reaction, and the gas generated by the separation enters the first combustion chamber 11; the thallium-containing tail gas from which the dust is removed by the bag filter enters the thallium absorption device 14 for thallium removal, and the thallium absorption device is loaded with a metal sulfide thallium adsorbent at a temperature of 185°C; the purified gas generated after thallium removal is discharged into the atmosphere through an induced draft fan 15; wherein the metal sulfide is ZnS, and the particle size of the metal sulfide is 0.5 mm;

[0195] Step S5: The roasted clinker discharged from the roasted clinker cooling system 6 is sent to the leaching unit 7 for acid leaching using sulfuric acid, and after leaching, it is sent to the filtering unit 8 for filtration to produce leaching residue and leachate; the leaching residue is washed with water to obtain water washing liquid and smelting slag, and the water washing liquid is returned to the leaching unit for recycling after being supplemented with acid; wherein, the concentration of sulfuric acid is 0.5 mol / L; the solid-liquid ratio of the leaching process is 0.1:1, and the leaching time is 3 hours.

[0196] Step S6: The leachate discharged from the filtration unit 8 is sent to the aluminum removal unit 9 for aluminum removal, and a coordination agent is added to the filtrate to coordinate the aluminum ions in the filtrate to form low specific surface area aluminum salt particles and a lithium-rich solution; the lithium-rich solution produced by aluminum removal is sent to the lithium precipitation unit to obtain a lithium carbonate product;

[0197] Step S7: The low specific surface area aluminum salt particles produced by aluminum removal are washed with water and added to a dilute sulfuric acid solution to react with the dilute sulfuric acid to obtain a complexing agent, which is returned to the aluminum removal unit 9 for recycling; wherein the concentration of the dilute sulfuric acid is 0.5 mol / L.

[0198] In this embodiment, the lithium leaching rate is 96.5%, the comprehensive lithium recovery rate is 87.5%, the rubidium and cesium leaching rate is 95%, the fluorine and thallium resource recovery rate is 98%, and the slag volume is reduced by 35%.

[0199] According to the results of the above embodiments, the steam fluidized roasting method and system for lithium mica provided in the present application effectively promote the conversion of lithium, improve the roasting conversion rate and leaching rate of lithium, significantly improve the utilization rate of lithium resources, and also improve the resource utilization rate of fluorine and thallium, and significantly reduce the amount of smelting slag.

[0200] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the principles of the present application should be included in the scope of protection of the present application.

Claims

1. A steam fluidized calcination method for lepidolite, characterized in that: The following steps are involved: Step S1: mixing lepidolite ore powder and sulfate additive to prepare roasted raw meal, adding fluorine-fixing additive, and mixing to prepare a mixture; Step S2: preheating the mixed material and the fluidizing gas to obtain a preheated mixed material and a preheated fluidizing gas; Step S3: sending the preheated mixed material and the preheated fluidizing gas to a fluidized bed calciner for fluidized calcination reaction, and separating to obtain calcined clinker, fluorine-fixing additive, and thallium-containing tail gas; the calcined clinker and fluorine-fixing additive are discharged from the upper layer and the bottom of the fluidized bed calciner, respectively; Step S4: subjecting the thallium-containing tail gas to cyclone preheating and wet defluorination, and reacting it with metal sulfide to produce thallium sulfide.

2. The method according to claim 1, characterized in that Also includes: Step S5: cooling the roasted clinker, leaching the cooled roasted clinker with sulfuric acid, and filtering to obtain a leaching solution containing lithium, rubidium, and cesium and a leaching residue; Step S6: adding a complexing agent to the lithium-containing rubidium-cesium leachate to obtain aluminum salt particles and a lithium-rich solution; Step S7: Leaching the aluminum salt particles with dilute sulfuric acid to obtain aluminum sulfate and the coordination agent.

3. The method according to claim 1, characterized in that The step S1 satisfies at least one of the following conditions: (1) The weight ratio of the lepidolite powder to the sulfate additive is 1:0.1-0.5; (2) The particle size of the roasted raw material is 0.03 mm to 0.45 mm; (3) The sulfate adjuvant is a sulfate of Na, K, Ca or Fe; (4) The fluorine-fixing auxiliary agent is a mixture of at least one of oxides and hydroxides of Ca, Al, Mg, Zn, Fe, Cu, Ni, Co, Ti, W, and Mo.

4. The method according to claim 1 or 3, characterized in that In the step S1, the particle size of the fluorine-fixing auxiliary agent is 0.5 mm to 3 mm.

5. The method according to claim 1, wherein In step S2, the temperature of the preheated mixed material is 800°C to 1000°C; the temperature of the preheated fluidizing gas is 950°C to 1200°C.

6. The method according to claim 1, characterized in that Step S3 satisfies at least one of the following conditions: (1) The water vapor content in the preheated fluidizing gas is greater than 10 vol%; (2) The reaction temperature of the calcination reaction is 900° C. to 1100° C., and the reaction time is 0.1 h to 0.5 h; (3) The linear velocity of the preheated fluidizing gas is 0.2 m / s to 1.2 m / s.

7. The method according to claim 1, characterized in that The step S4 satisfies at least one of the following conditions: (1) The metal sulfide includes at least one of WS2, MoS2, FeS2, NiS2, CoS2, TiS2, CuS, and ZnS; (2) The particle size of the metal sulfide is 0.1 mm to 3 mm; the reaction temperature is 120° C. to 500° C.; (3) The wet defluorination process includes: using a metal hydroxide solution to absorb HF gas and generate metal fluoride, and the reaction temperature is 50°C to 200°C.

8. The method according to claim 2, characterized in that In step S5, the sensible heat of the roasted clinker during cooling can be used to preheat the fluidizing gas in step S2; The concentration of the sulfuric acid is 0.1 mol / L to 5 mol / L; the solid-liquid ratio of the leaching process is 0.05 to 0.5:1, and the leaching time is 0.5 to 3 hours.

9. A system for steam fluidized roasting of lepidolite, characterized in that: include: Mixer, used to mix roasted raw meal and fluorine-fixing additive; A feeding subsystem, used for conveying the materials mixed by the mixer, wherein the feeding subsystem is connected to the mixer; A preheating subsystem, used for preheating the mixed material, wherein the preheating subsystem is connected to the feeding subsystem; A fluidized calcination subsystem is used to perform a fluidized calcination reaction on the preheated mixed material, and the fluidized calcination subsystem is connected to the preheating subsystem; A leaching subsystem, used for leaching the roasted clinker to obtain a leachate and a leach residue; an aluminum removal subsystem, for removing aluminum from the leachate to obtain aluminum salt particles and a lithium-rich solution; The lithium precipitation subsystem is used to perform lithium precipitation treatment on the lithium-rich solution to obtain a lithium carbonate product.

10. The system according to claim 9, characterized in that Also includes: A gas absorption subsystem, used for removing thallium from the thallium-containing tail gas, wherein the gas absorption subsystem is connected to the fluidized bed roasting subsystem; A clinker cooling subsystem, used for cooling the clinker, wherein the clinker cooling subsystem is connected to the fluidized bed clinker subsystem; The induced draft subsystem includes an induced draft fan, which is used to discharge the purified gas generated after the thallium-containing tail gas is dethallized into the atmosphere. The induced draft fan is connected to the gas absorption subsystem.

11. The system according to claim 9, wherein: At least one of the following conditions is met: (1) The fluidized roasting subsystem includes a feed valve, a fluidized bed roasting furnace (5), a roasting furnace cyclone separator and a discharge valve, wherein the feed port of the fluidized bed roasting furnace (5) is connected to the feed subsystem via the feed valve, the discharge port of the fluidized bed roasting furnace (5) is connected to the roasting clinker cooling subsystem via the discharge valve, the air inlet of the roasting furnace cyclone separator is connected to the air outlet of the fluidized bed roasting furnace (5), and the air outlet of the roasting furnace cyclone separator is connected to the air inlet of the first combustion chamber (11); (2) The gas absorption subsystem further includes a thallium absorption device (14), the thallium absorption device (14) is connected to the tail gas outlet of the bag filter (13), and the air outlet of the thallium absorption device (14) is connected to the air inlet of the induced draft fan (15); (3) The fluidized bed roasting furnace (5) is a multi-stage fluidized bed, and a transverse baffle internal component is set in the bed, preferably 2-5 levels of transverse baffles, for regulating and realizing the separation of the lepidolite ore powder and the roasting aid; (4) The mineral powder preheating subsystem includes a first combustion chamber (11), a cyclone preheater (4) and a cyclone separator, the air outlet of the first combustion chamber (11) is connected to the air inlet of the cyclone preheater (4), the air outlet of the cyclone preheater (4) is connected to the air inlet of the cyclone separator, the feed port of the cyclone preheater (4) is connected to the feed subsystem, and the discharge port of the cyclone preheater (4) is connected to the roasting subsystem through a material valve; (5) The cyclone preheater (4) is a 2-4 stage cyclone preheater; (6) The discharge port of the cyclone separator is connected to the feed port of the cyclone preheater (4), and the air outlet of the cyclone separator is connected to the air inlet of the bag dust collector (13); (7) The bag dust collector (13) is connected to the feeding subsystem via a feeder; (8) The feeding subsystem includes a mixer (1), a raw material bin (2) and a screw feeder (3), the discharge port of the mixer (1) is connected to the feed port of the raw material bin (2), the discharge port of the raw material bin (2) is connected to the feed port of the screw feeder (3), and the discharge port of the screw feeder (3) is connected to the roasting raw material preheating subsystem; (9) The gas absorption subsystem includes a thallium absorption device (14), the thallium absorption device (14) is connected to the tail gas outlet of the bag filter (13), and the air outlet of the thallium absorption device (14) is connected to the air inlet of the induced draft fan (15); (10) The air outlet of the cyclone preheating subsystem (4) is connected to the induced draft fan (15) through the bag filter (13) and the thallium absorption device (14); (11) The roasting clinker cooling subsystem (6) includes a cyclone cooler and a cyclone cooling separator. The feed port of the cyclone cooler is connected to the fluidized bed roasting furnace (5) through a discharge valve, and the air outlet of the cyclone cooler is connected to the air inlet of the cyclone cooling separator. (12) The gas outlet of the cyclone cooling separator is connected to the gas inlet of the fluidized bed roaster, and the discharge port of the cyclone cooling separator is connected to the cyclone cooler; (13) The induced draft subsystem includes an induced draft fan (15); (14) The roasted clinker discharge outlet of the roasted clinker cooling subsystem (6) is connected to the material inlet of the leaching unit (7), the outlet of the leaching unit (7) is connected to the inlet of the filtration unit (8), the outlet of the filtration unit (8) is connected to the inlet of the aluminum removal unit (9), and the outlet of the aluminum removal unit (9) is connected to the inlet of the lithium precipitation unit (10).

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