A salt melt pre-coating mineral particle suspension roasting system and method of a clay type lithium ore
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UNIV OF SCI & TECH BEIJING
- Filing Date
- 2024-10-31
- Publication Date
- 2026-06-26
Smart Images
Figure CN119433189B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium ore smelting and extraction technology, and specifically relates to a salt-melting pre-coated mineral particle suspension roasting system and method for clay-type lithium ore. Background Technology
[0002] Clay-type lithium ore, as an unconventional lithium resource, has received increasing attention in recent years. Currently, the main methods for extracting lithium from clay-type lithium ore fall into two categories: the sulfuric acid process and the sulfate mixed roasting method, similar to the existing processing methods for hard-rock lithium ore. Chinese patent CN 103849761A discloses a method for extracting lithium from low-grade lithium-bearing clay ore. The lithium-bearing clay ore is ground to 2 mm and mixed in a mass ratio of lithium-bearing clay ore: calcium sulfate: calcium fluoride: sodium sulfate = 1:0.7:0.2:0.5. The mixture is then roasted at 800℃ for 2-3 hours, followed by granulation and heap leaching of the roasted ore. The highest lithium leaching rate is 91.78%. This technology is complex, involves high roasting temperatures, and has high energy consumption. Chinese patent CN 114892024A discloses a method for extracting lithium from lithium-bearing clay ore through low-temperature roasting. 98% concentrated sulfuric acid is mixed with lithium-containing clay ore at an acid-to-ore ratio of 0.5:1 to 1:2, and then roasted at 180–250 °C. The roasted product is then leached with water to obtain a lithium-containing solution with a lithium leaching rate of 89.32%. This technique produces a lithium-containing leachate with high acidity and complex composition, requiring complex subsequent purification and impurity removal processes, resulting in high lithium extraction costs. Chinese patent CN 113104867A discloses a method for preparing lithium carbonate by acidifying and roasting lepidolite with composite sulfates. Lithium mica ore powder is mixed with at least two of the following sulfates: potassium sulfate, sodium sulfate, calcium sulfate, barium sulfate, and ferric sulfate, as well as additives such as barium carbonate and calcium carbonate, at a mass ratio of lithium mica ore powder:composite sulfate:additives = 1:0.39-0.64:0.03-0.09. The mixture is then mechanically activated in a high-performance ball mill. 1-4% (by mass) of concentrated sulfuric acid is added and mixed thoroughly. The mixture is then calcined in a rotary kiln at 830-880℃. The calcined product is then pulverized, leached in water, and impurities are removed to prepare lithium carbonate. This technology involves a large amount of composite sulfate, requires mechanical activation in a high-performance ball mill after mixing, has a complex process, and consumes a lot of energy during calcination in the 830-880℃ rotary kiln. Zhu Lingyan et al. (Zhu Lingyan, Liang Xianzhe, Liu Yuelong et al. Lithium extraction process from low-grade lepidolite by Na2SO4-H2SO4 mixed roasting. Nonferrous Metals Engineering, 2021, 11(11): 48-55.) disclosed a lithium extraction process from low-grade lepidolite by Na2SO4-H2SO4 mixed roasting, which includes the following steps: weighing a certain amount of lepidolite ore, adding it to a pre-prepared sulfuric acid solution at a mass ratio of 1:1, adding a certain mass of sodium sulfate, mixing thoroughly, and then roasting it in a muffle furnace at 280℃ for 2 hours. After the roasted ore is crushed, it is further roasted in a muffle furnace at 800-1000℃ for 2 hours. After the roasted ore is cooled, it is crushed, ground, and leached with hot water. The lithium leaching rate can reach 90%, but due to the use of two-stage roasting, the process is complex and energy consumption is high. Chinese patent CN 116790911 A discloses a method for lithium extraction from clay-type lithium ore.Clay-type lithium ore powder, sulfates (sodium sulfate and / or potassium sulfate), and concentrated sulfuric acid are mixed uniformly in a mass ratio of 1:0.03-0.25:0.18-0.6, and then roasted at 480-750℃ for 2-8 hours. The roasted ore is then ground and leached in water to obtain a lithium leachate. This technology uses less sulfate and concentrated sulfuric acid, has a low roasting temperature, low energy consumption, low acidity of the leachate, and a lithium leaching rate of up to 90%. As can be seen from the above analysis, by incorporating highly active sulfates (such as sodium sulfate) during the roasting process of clay-type lithium ore, and utilizing the characteristics of alkali metal ions at high temperatures to destroy the silicate crystal structure of clay minerals and affect the amorphous phase transformation temperature of materials, it is possible to effectively break down and decompose fine-grained lithium minerals encapsulated by clay minerals such as kaolinite and illite at low temperatures. In addition, the roasted sand obtained after salt roasting can be used for simple water leaching lithium extraction. Compared with the traditional sulfuric acid method for lithium extraction, the resulting lithium leachate has low acidity and simple solution composition, which makes it easier to purify the solution and remove impurities and prepare high-purity lithium carbonate products.
[0003] Suspension roasting is an energy-saving and efficient roasting technology. Compared with traditional rotary kiln roasting processes, it can achieve efficient decomposition of difficult-to-decompose minerals at lower temperatures and faster speeds, thus reducing roasting costs. Chinese Patent CN 107739847 A discloses a crystal transformation method for suspension roasting of natural spodumene. Natural α-spodumene is ground to a certain particle size and then fed into a two-stage suspension roasting furnace. High-temperature exhaust gas separated from the first-stage cyclone dust collector is used for fluidized bed drying and preheating. The preheated spodumene powder is then passed through the second-stage cyclone dust collector along with the high-temperature exhaust gas for gas-solid separation. The separated exhaust gas is then subjected to gas-solid separation again. The collected spodumene powder, along with the preheated spodumene powder separated in the second-stage cyclone dust collector, is introduced into the first-stage suspension roasting furnace. High-temperature gas is used for suspension roasting, causing the spodumene powder to undergo preliminary crystal transformation. After separation by the first-stage cyclone dust collector, the resulting high-temperature mineral powder is kept at a constant temperature in an insulated tank for a certain period to complete the crystal transformation. Finally, it is transferred to a cooler for cooling to obtain β-spodumene. Compared with traditional rotary kiln roasting for spodumene crystal transformation, this technology has advantages such as low energy consumption, large processing capacity, easy control of crystal transformation temperature, and more complete crystal transformation. Chinese patent CN 108034839 B discloses a method for defluorination of lepidolite through suspension roasting. Crushed lepidolite is fed into a suspension roasting furnace, where it is mixed with hot gases generated from combustion at the furnace bottom and water vapor introduced from a preheated steam recovery system for rapid roasting and defluorination. After roasting, the hot gases carry the mineral powder into a cyclone separator for gas-solid separation. The mineral powder is then transferred to an insulated tank for further defluorination. After defluorination, the mineral powder is cooled in a cooler to obtain the defluorinated lepidolite product. Compared with traditional rotary kiln roasting, this invention has lower energy consumption, shorter residence time of lepidolite powder in the equipment, larger powder throughput per unit time, more uniform temperature control within the suspension roasting furnace, and stable and thorough defluorination. Chinese patent CN 111439762 A discloses a method for lithium extraction through spodumene suspension roasting. Spodumene concentrate is ground and introduced into a suspension roasting furnace. A mixed gas is introduced into the bottom of the furnace, heating it to 1000–1100 °C. Mineral powder is suspended and heated under airflow, resulting in crystal transformation to form roasted clinker. The roasted product is ground and mixed with sulfuric acid solution, then acidified and roasted in an acidification kiln at 190–220 °C. After acidification and roasting, the product is leached in water, and the filtrate is neutralized, purified, and then lithium is precipitated to obtain lithium carbonate. Compared to traditional rotary kiln crystal transformation roasting, this technology has lower energy consumption, easier temperature control within the furnace, larger processing capacity, and higher lithium leaching rate. Chinese patent CN 114349031 A discloses a method for suspension roasting of spodumene concentrate. Using suspension roasting technology to roast spodumene, compared to conventional rotary kiln or tunnel kiln roasting, suspension roasting can precisely control the roasting temperature and temperature field distribution within the furnace, resulting in high heat and mass transfer efficiency, and can quickly, efficiently, and completely transform spodumene from the α-phase to the β-phase.The suspension roasting process has low energy consumption, significantly shortened reaction time, and a large processing capacity per unit time. Furthermore, due to the high conversion rate achieved through suspension roasting technology during crystal transformation, excessive sulfuric acid is not required during subsequent acid roasting, reducing reaction time and equipment corrosion. Chinese Patent CN114812179 A discloses a suspension roasting furnace apparatus and method for spodumene ore powder. The apparatus includes a dispersion dryer, a first separator, a cyclone preheater, a suspension roasting furnace, a second separator, a phase change reactor, a cyclone cooler, a powder waste heat boiler, a waste gas purifier, and an induced draft fan. Spodumene is ground to a certain particle size and continuously fed into the dispersion dryer. After dispersion and drying, it enters the first separator and cyclone preheater, where it exchanges heat with hot air before entering the suspension roasting furnace. Suspension heating generates pre-phase change ore powder, which then enters the second separator and phase change reactor, where fluidizing air is introduced to generate fully phase change ore powder. The mineral powder is fed into a cyclone cooler along with air, and the pre-cooled powder enters the waste heat boiler to generate low-temperature powder before being discharged. This technology features a fast reaction speed, high calcination and crystallization efficiency, full utilization of waste heat, low heat consumption, large processing capacity per unit time, and low calcination cost.
[0004] From the publicly available suspension roasting technologies, it is clear that suspension roasting has significant advantages over traditional rotary kiln and other kiln roasting processes. However, current suspension roasting processes are mostly applied only to the direct oxidation roasting of lithium ore powder and cannot be coupled with the salt roasting process for clay-type lithium ore. Due to the significant differences in the physicochemical properties between clay-type lithium ore powder and sulfate particles, even if the clay-type lithium ore powder and sulfate particles are mixed before suspension roasting, the mixture of the two solid materials is difficult to achieve effective contact in a suspended state after entering the suspension roasting furnace. Because solid-solid phase reactions are difficult to occur, the added sulfate cannot react with the clay-type lithium ore particles, failing to achieve the effect of salt roasting of clay-type lithium ore particles in traditional kilns. Summary of the Invention
[0005] To address the aforementioned problems, the present invention aims to provide a salt-melted pre-coated ore particle suspension roasting system and method for clay-type lithium ore, thereby achieving the effects of static roasting in traditional rotary kilns and other furnaces during the suspension roasting process, and better leveraging the advantages of salt-roasting for lithium extraction from clay-type lithium ore. To achieve this objective, the present invention utilizes the following technical solutions to realize the above objectives and methods:
[0006] A suspension roasting system for pre-coated clay-type lithium ore particles via salt fusion, the system comprising a mixer, a preheating furnace, a dispersion dryer, a first cyclone separator, a cyclone preheater, a suspension roasting furnace, a second cyclone separator, a cyclone cooler, an air cooler, a bag filter or electrostatic precipitator, a tail gas treatment device, an induced draft fan, a first screw feeder, and a second screw feeder, wherein:
[0007] The mixer is used to mix mineral powder and mixed salt. The upper part of the mixer is provided with a feed inlet for mineral powder and mixed salt of alkali metal sulfate and nitrate. The lower discharge port of the mixer is connected to the feed inlet of the preheating furnace through a first screw feeder.
[0008] The preheating furnace is used to preheat the mixture output from the mixer to obtain salt-melted pre-coated mineral powder. The outlet of the preheating furnace is connected to the inlet of the dispersion dryer through the second screw feeder.
[0009] The disperser uses hot air from the cyclone cooler to disperse and dry the mineral powder output from the preheating furnace. The air inlet of the disperser is connected to the air outlet of the cyclone cooler through a pipe; the discharge outlet of the disperser is connected to the feed inlet of the first cyclone separator.
[0010] The first cyclone separator is used to perform gas-solid separation on the discharge of the dispersion dryer. The air outlet of the first cyclone separator is connected to the air inlet of the preheating furnace. The discharge outlet of the first cyclone separator is connected to the air outlet pipe of the second cyclone separator through the feed pipe, and is also connected to the feed inlet of the cyclone preheater.
[0011] The cyclone preheater uses the exhaust gas from the second cyclone separator as a heat source to preheat the mineral powder output from the first cyclone separator to obtain preheated mineral powder. The solid phase outlet of the cyclone preheater is connected to the feed inlet of the suspension roasting furnace; the exhaust gas outlet of the cyclone preheater is connected to the inlet of the bag filter or electrostatic precipitator.
[0012] The bag filter or electrostatic precipitator is used to perform gas-solid separation on the gas phase discharge of the cyclone preheater and to transport the separated solid products back to the cyclone preheater. The lower outlet of the bag filter or electrostatic precipitator is connected to the feed inlet of the cyclone preheater; the upper outlet of the bag filter or electrostatic precipitator is connected to the inlet of the exhaust gas treatment device.
[0013] The exhaust gas treatment device is used to treat the gas phase discharge from the cyclone preheater and the bag filter or electrostatic precipitator. The induced draft fan is used to discharge the exhaust gas generated by the exhaust gas treatment device. The exhaust gas treatment device outlet is connected to the induced draft fan inlet.
[0014] The suspension roasting furnace is used to roast the solid output of the cyclone preheater. The mineral powder is in a fluidized suspension state in the suspension roasting furnace. The discharge port of the suspension roasting furnace is connected to the inlet of the second cyclone separator. The lower part of the suspension roasting furnace is provided with a fuel inlet for fuel to be introduced.
[0015] The second cyclone separator is used to perform gas-solid separation on the discharge from the suspension roasting furnace, and the discharge port of the second cyclone separator is connected to the inlet of the cyclone cooler.
[0016] The cyclone cooler is used to cool the solid phase discharge of the second cyclone separator and to separate the gas and solid phases. The discharge port of the cyclone cooler is connected to the inlet of the air cooler. The air outlet of the cyclone cooler is connected to the air inlet of the dispersion dryer through a pipe.
[0017] The air cooler is used to further cool the solid phase output of the cyclone cooler and introduce the separated hot air into the suspension roasting furnace as combustion air; the air inlet of the suspension roasting furnace is connected to the air outlet of the air cooler through a pipe, and the roasted clinker outlet is provided below the air cooler.
[0018] The present invention also provides a method for suspension calcination using the system, comprising the following steps:
[0019] (1) The clay-type lithium ore or its concentrate is ground into mineral powder and mixed with a mixture of alkali metal sulfates and nitrates in a mixer to obtain a mixture;
[0020] (2) The mixture obtained in step (1) is fed into the preheating furnace using the first screw feeder. The mixture is preheated and kept warm in the range of 300~400℃ using the residual heat of the tail gas from the first cyclone separator to obtain salt melt pre-coated mineral powder.
[0021] (3) Air is introduced into the air inlets of the cyclone cooler and the air cooler. The salt-melted pre-coated mineral powder obtained in step (2) is conveyed to the dispersion dryer by the second screw feeder. Hot air at 300~400℃ from the air outlet of the cyclone cooler is introduced into the air inlet at the bottom of the dispersion dryer. The hot air is mixed with the mineral powder to disperse and dry the mineral powder. The dried mineral powder is discharged from the outlet of the dispersion dryer along with the hot air and enters the first cyclone separator, where it is separated from the gas. Under the condition of starting the induced draft fan, the dried mineral powder enters the cyclone preheater before the suspension roasting furnace along with the hot air at 500~600℃ from the air outlet of the second cyclone separator.
[0022] (4) The dried mineral powder obtained in step (3) is placed in a cyclone preheater and exchanged with the 500 ~ 600 ℃ tail gas from the outlet of the second cyclone separator to form preheated mineral powder, which is discharged from the outlet of the cyclone preheater and enters the suspension roasting furnace.
[0023] (5) Hot air from the air cooler is introduced into the bottom air inlet of the suspension roasting furnace, and fuel is introduced into the fuel inlet of the bottom burner of the suspension roasting furnace. The fuel is burned in the furnace chamber of the suspension roasting furnace to further heat the preheated mineral powder from step (4) to a temperature range of 600 ~ 700℃. The mineral powder is in a fluidized suspension state in the suspension roasting furnace under the action of airflow for roasting.
[0024] (6) The mineral powder obtained after suspension roasting in step (5) is transported by hot air into the second cyclone separator connected to the suspension roasting furnace for gas-solid separation. The obtained mineral powder is then transported into the cyclone cooler for air cooling and gas-solid separation. The mineral powder is discharged from the bottom discharge port of the cyclone cooler and sent to the air cooler for further air cooling to obtain roasted clinker. The preheated air in the air cooler is introduced into the burner at the bottom of the suspension roasting furnace as combustion air.
[0025] (7) The 500-600℃ tail gas obtained by the second cyclone separator in step (6) is introduced into the cyclone preheater in step (4) as heating gas to preheat the mineral powder; the tail gas of the cyclone preheater is treated by a bag filter or electrostatic precipitator and then discharged after meeting the standards; the mineral powder collected by the bag filter or electrostatic precipitator is returned to the cyclone preheater and sent back to the suspension roasting furnace for further roasting.
[0026] Further, in the mineral powder described in step (1), the portion with a particle size of -0.074 mm accounts for 60-90% of the total mass of the mineral powder. Preferably, the mass percentage of Li2O in the clay-type lithium ore is 0.4-0.5%; and the mass percentage of Li2O in the clay-type lithium concentrate is 0.6-1.0%. The moisture content by weight in the clay-type lithium ore or its concentrate is 1-5%.
[0027] Further, in step (1), the added alkali metal sulfate is sodium sulfate and / or potassium sulfate, and the added alkali metal nitrate is sodium nitrate and / or potassium nitrate. The mass ratio of the clay-type lithium ore powder to the mixed salt (i.e., alkali metal sulfate and nitrate) is 1:0.05 ~ 1:0.3, and the mass ratio of sulfate to nitrate in the mixed salt of alkali metal sulfate and nitrate is 2:1 ~ 1:2. Since nitrate has a low melting point, it softens and melts preferentially when heated and held at 300 ~ 400 °C in the preheating furnace. After the nitrate melts and softens, it erodes the surface of the mineral particles, which helps the high-melting-point sulfate to embed into the layered lattice of the mineral particles, forming a pre-coating of the mineral particles. When the pre-coated mineral particles are preheated at 500 ~ 600 °C in the cyclone preheater, the nitrate on the surface will completely decompose and volatilize, preventing the nitrate from entering the suspension roasting furnace and affecting the suspension roasting reaction. Therefore, the mass ratio of sulfate to nitrate needs to be controlled within the above range. If the amount of nitrate added is too small, the added sulfate will not be able to form an effective pre-coating on the mineral particles, and the sulfate and mineral particles will still be in a state of not being able to combine. If the amount of nitrate added is too large, the nitrate will not be able to completely decompose and volatilize in the cyclone preheater, affecting the subsequent suspension roasting reaction.
[0028] Furthermore, in step (2), the preheating time of the mixture is 0.5 to 2 hours.
[0029] Further, in step (2), the mixture obtained in step (1) is fed into a preheating furnace using a first screw feeder. The mixture obtained in step (1) is preheated and kept at a temperature of 300-400℃ using the residual heat from the tail gas of the first cyclone separator. The purpose is to pre-melt and soften the nitrate-sulfur mixed salt within the temperature range of 300-400℃. Sodium nitrate has a melting point of 307℃, a boiling point of 380℃, and a decomposition temperature of 380℃. Sodium sulfate has a melting point of 884℃, a boiling point of 1404℃, and a decomposition temperature of 1100℃. Potassium nitrate has a melting point of 334℃, a boiling point of 400℃, and a decomposition temperature of 670℃. Potassium sulfate has a melting point of 1067℃, a decomposition temperature of 1067℃, and a boiling point of 1689℃. The melting point of nitrate is relatively lower than that of sulfate, so it will be softened and melted preferentially. The erosion of the mineral particle surface by the melting and softening of nitrates helps the high-melting-point sulfates to embed into the layered lattice of the mineral particles for pre-encapsulation.
[0030] Further, in step (3), the salt-melted pre-coated mineral powder obtained in step (2) is fed into the dispersion dryer by the second screw feeder. Hot air at 300~400℃ is introduced into the air inlet at the bottom of the dispersion dryer. The purpose is to mix the hot air with the mineral powder, disperse and dry the mineral powder, and prevent the nitrate on the surface of the mineral particles from sticking to the mineral particles, which is not conducive to the particle size requirements of the mineral powder entering the subsequent suspension roasting furnace.
[0031] Furthermore, the dispersion dryer mentioned in step (3) is a Venturi dryer, a flash dryer, or a drying and dispersing machine.
[0032] Further, in step (4), the dried mineral powder obtained in step (3) is placed in a cyclone preheater and exchanged with hot air from the second cyclone separator at 500 ~ 600 ℃. The purpose is to further increase the temperature to the range of 500 ~ 600 ℃, so as to promote the further decomposition and volatilization of nitrate on the salt melt pre-coated surface, and obtain mineral particles coated with sulfate on the surface, so as to facilitate the subsequent suspension roasting process in which sulfate enters the interior of the mineral particle lattice and opens the layered lattice to encapsulate the fine lithium mineral particles.
[0033] Further, in step (5), the preheated mineral powder from step (4) is heated in a suspension roasting furnace at a temperature range of 600 ~ 700 ℃. The mineral powder is in a fluidized suspension state in the suspension roasting furnace under the action of airflow. The purpose is to use sodium sulfate and / or potassium sulfate wrapped on the surface of clay minerals to erode and destroy the interlayer structure of clay minerals such as kaolinite and illite. The alkali metal ions in the sulfates erode and destroy the aluminosilicate crystal structure in the clay minerals, release the fine lithium minerals "bound" in the layered lattice structure and expose them. They react with sodium salts and / or potassium salts and decompose into water-soluble lithium sulfate salts, so that they can be effectively leached in neutral water in the subsequent process, thereby improving the lithium extraction yield.
[0034] Further, in step (5), the residence time of the mineral powder in the suspension roasting furnace is 10 to 30 minutes, and the aeration rate per kilogram of mineral powder is 500 to 800 mL / min.
[0035] Furthermore, in step (5), the fuel used in the burner of the suspension roasting furnace is an alkane fuel, including but not limited to one or more of heavy oil, natural gas, liquefied petroleum gas or water gas.
[0036] Further, in step (6), the cyclone cooler separates exhaust gas with a temperature range of 300~400℃, and in step (3), the second cyclone separator separates exhaust gas with a temperature range of 500~600℃.
[0037] Furthermore, to verify the suspension roasting effect, the roasted clinker obtained in step (6) was ground until the particle size of -0.074 mm accounted for 60 to 90% of the total mass, and roasted powder was prepared. The roasted powder was mixed with water at a solid-liquid mass ratio of 1:3 to 1:4 and stirred and soaked in water at 20 to 100°C for 0.5 to 2 hours to obtain water-soaked material. The water-soaked material was filtered to separate lithium-containing leachate and filter residue. The lithium-containing leachate and filter residue were sampled and sent for analysis to detect the lithium content.
[0038] The method of this invention adopts the principle of fluidized bed roasting of powdered minerals, which can process clay lithium ore powder with a particle size of 0.074 ~ 0.08 mm. It has a short roasting time, precise temperature control, high roasting efficiency, stable roasting product quality, full utilization of waste heat, low energy consumption, and low process cost.
[0039] Compared with other disclosed technical solutions, the present invention has the following beneficial effects:
[0040] (1) The new method can take advantage of the salt roasting of clay-type lithium ore: within a certain temperature range, it can effectively remove the hydroxyl groups that connect the basic units of aluminum-oxygen octahedron and silicon-oxygen tetrahedron in clay minerals such as kaolinite and illite, destroy the basic structure of the layered chain silicate of clay minerals, and release the fine lithium minerals "bound" in the layered silicate structure to react with sulfates and be converted into soluble sulfates.
[0041] (2) The new method also leverages the advantages of suspension roasting: it precisely controls the dissociation, mineral phase transformation, and decomposition behavior of clay minerals and lithium-containing mineral aggregates at the microscale during roasting; and it achieves efficient decomposition of fine-grained lithium minerals embedded in the clay mineral lattice at a lower temperature and faster speed. Compared with traditional rotary kilns, tunnel kilns, and other kiln roasting methods, it has lower energy consumption, lower roasting cost, larger processing capacity, and more uniform temperature field control in the suspension roasting furnace, resulting in stable and thorough roasting.
[0042] (3) The new method organically integrates the advantages of static kiln salt roasting and dynamic suspension roasting. The roasting temperature of suspension dynamic roasting is precisely controlled, with the roasting temperature fluctuating within ±5℃. Compared with traditional kiln static roasting, it can better control over-burning and is conducive to regulating the changes in the mineral phase structure during the roasting process, resulting in better selective leaching of lithium in the roasted sand. The roasted sand after salt suspension roasting by the new process can achieve efficient selective leaching of low-grade lithium in clay-type lithium ore and effective suppression of impurity elements by direct neutral water leaching, which greatly reduces the burden of subsequent purification and impurity removal. Attached Figure Description
[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments are briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0044] Figure 1 This is a schematic diagram of the structure of a salt-melting pre-coated mineral particle suspension roasting system for clay-type lithium ore according to the present invention;
[0045] In the diagram, 1. Mixer; 2. Preheater; 3. Dispersion dryer; 4. First cyclone separator; 5. Cyclone preheater; 6. Suspension roasting furnace; 7. Second cyclone separator; 8. Cyclone cooler; 9. Air cooler; 10. Bag filter or electrostatic precipitator; 11. Exhaust gas treatment device; 12. Exhaust fan; 13. First screw feeder; 14. Second screw feeder.
[0046] A. Clay-type lithium ore or its concentrate powder; B. Mixed salts of alkali metal sulfates and nitrates; C. Fuel; D. Roasted clinker; E. Air; F. Exhaust gas. Detailed Implementation
[0047] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows. Those skilled in the art should understand that these embodiments are merely illustrative of the present invention and should not be considered as specific limitations thereof.
[0048] Example 1
[0049] A salt-melted pre-coated ore particle suspension roasting system for clay-type lithium ore, the structure of which is shown in the figure below. Figure 1 As shown. The system includes a mixer 1, a preheating furnace 2, a dispersion dryer 3, a first cyclone separator 4, a cyclone preheater 5, a suspension roasting furnace 6, a second cyclone separator 7, a cyclone cooler 8, an air cooler 9, a bag filter or electrostatic precipitator 10, a tail gas treatment device 11, an induced draft fan 12, a first screw feeder 13, and a second screw feeder 14, wherein:
[0050] The mixer 1 has an inlet at the top for mineral powder A and a mixed salt of alkali metal sulfate and nitrate B; the outlet at the bottom of the mixer 1 is connected to the inlet of the preheating furnace 2 via a first screw feeder 13; the outlet of the preheating furnace 2 is connected to the inlet of the dispersion dryer 3 via a second screw feeder 14; the air inlet of the dispersion dryer 3 is connected to the air outlet of the cyclone cooler 8 via a pipe; the outlet of the dispersion dryer 3 is connected to the inlet of the first cyclone separator 4; the air outlet of the first cyclone separator 4 is connected to the air inlet of the preheating furnace 2; the outlet of the first cyclone separator 4 is connected to the air outlet pipe of the second cyclone separator 7 via a feed pipe, and is also connected to the inlet of the cyclone preheater 5.
[0051] The solid discharge port of the cyclone preheater 5 is connected to the feed port of the suspension roasting furnace 6; the air outlet of the cyclone preheater 5 is connected to the inlet of the bag filter or electrostatic precipitator 10; the lower outlet of the bag filter or electrostatic precipitator 10 is connected to the feed port of the cyclone preheater 5; the upper air outlet of the bag filter or electrostatic precipitator 10 is connected to the air inlet of the exhaust gas treatment device 11; the air outlet of the exhaust gas treatment device 11 is connected to the air inlet of the induced draft fan 12, and the exhaust gas F is discharged from the air outlet of the induced draft fan 12.
[0052] The discharge port of the suspension roasting furnace 6 is connected to the inlet of the second cyclone separator 7; the lower part of the suspension roasting furnace 6 is provided with a fuel inlet for introducing fuel C; the discharge port of the second cyclone separator 7 is connected to the inlet of the cyclone cooler 8; the discharge port of the cyclone cooler 8 is connected to the inlet of the air cooler 9; the air outlet of the cyclone cooler 8 is connected to the air inlet of the dispersion dryer 3 through a pipe; the air inlet of the suspension roasting furnace 6 is connected to the air outlet of the air cooler 9 through a pipe, and the air cooler 9 is provided with a discharge port for roasted clinker D below it. Air E is introduced into the air inlets of the cyclone cooler and the air cooler.
[0053] The method for salt-melted pre-coated ore particles suspension roasting using the system described above is as follows:
[0054] (1) 1000 kg of raw clay-type lithium ore (with a Li2O mass percentage of 0.4% and a moisture weight percentage of 5%) is ground to a particle size of -0.074 mm, accounting for 90% of the total mass, to form mineral powder. This powder is then mixed with a mixture of sodium sulfate and sodium nitrate in mixer 1 to obtain a mixture. The mass ratio of the raw clay-type lithium ore powder to the mixed sodium sulfate and sodium nitrate is 1:0.3, and the mass ratio of sodium sulfate to sodium nitrate is 2:1.
[0055] (2) The mixture obtained in step (1) is fed into the preheating furnace 2 by the first screw feeder 13. The mixture obtained in step (1) is preheated and kept at a temperature of 300~400℃ using the waste heat from the tail gas of the first cyclone separator 4, and the temperature is kept at 2h to obtain salt melt pre-coated mineral powder.
[0056] (3) The salt-melted pre-coated mineral powder obtained in step (2) is fed into the dispersion dryer 3 by the second screw feeder 14. The exhaust gas at 300~400℃ from the outlet of the cyclone cooler 7 is introduced into the air inlet at the bottom of the dispersion dryer. The exhaust gas is mixed with the mineral powder to disperse and dry the mineral powder. The dried mineral powder is discharged from the outlet of the dispersion dryer 3 along with the hot air and enters the first cyclone separator 4, where it is separated from the gas. Under the condition of starting the induced draft fan 12, the dried mineral powder enters the cyclone preheater 5 before the suspension roasting furnace 6 along with the 500~600℃ hot air from the outlet of the second cyclone separator 7.
[0057] (4) The dried mineral powder obtained in step (3) is placed in the cyclone preheater 5 and exchanged with the 500 ~ 600 ℃ tail gas from the outlet of the second cyclone separator 7 to form preheated mineral powder, which is discharged from the outlet of the cyclone preheater 5 and enters the suspension roasting furnace 6.
[0058] (5) Hot air from the air cooler 9 is introduced into the bottom air inlet of the suspension roasting furnace 6, and natural gas is introduced into the fuel inlet of the burner at the bottom of the suspension roasting furnace 6. The natural gas is burned in the furnace chamber of the suspension roasting furnace 6 to further heat the preheated mineral powder from step (4) to a temperature range of 600 ~ 700 ℃. The mineral powder is in a fluidized suspension state in the suspension roasting furnace under the action of airflow for roasting. The residence time of the mineral powder in the suspension roasting furnace is 10 min, and the air flow rate is 500 mL / min per kilogram of mineral powder.
[0059] (6) The mineral powder obtained after suspension roasting in step (5) is transported by hot air into the second cyclone separator 7 connected to the suspension roasting furnace 6 for gas-solid separation. The obtained mineral powder is transported into the cyclone cooler 8 for air cooling and gas-solid separation. The mineral powder is discharged from the bottom discharge port of the cyclone cooler 8 and sent to the air cooler 9 for further air cooling to obtain roasted clinker. The preheated air in the air cooler 9 is introduced into the burner at the bottom of the suspension roasting furnace 6 as combustion air.
[0060] (7) The 500℃ ~ 600℃ tail gas separated by the second cyclone separator 7 in step (6) is introduced into the cyclone preheater 5 in step (4) as heating gas to preheat the mineral powder; the tail gas of the cyclone preheater 5 passes through the bag filter 10 and then enters the tail gas treatment device 11 for treatment to meet the standards before being discharged; the mineral powder collected by the bag filter 10 is returned to the cyclone preheater 5 and sent back to the suspension roasting furnace 6 for further roasting.
[0061] To test the suspension roasting effect, the roasted clinker obtained in step (6) was ground until 90% of the particle size was -0.074 mm, and roasted powder was prepared. The roasted powder was mixed with water at a solid-liquid mass ratio of 1:3 and stirred and soaked in water at 20 °C for 2 h to obtain water-soaked material. The water-soaked material was filtered to separate lithium-containing leachate and filter residue. The lithium concentration in the lithium-containing leachate was analyzed and found to be 1.08 g / L. The filter residue was dried and weighed, and the mass percentage of Li2O was analyzed and found to be 0.03%, and the lithium leaching rate was 93.1%.
[0062] Example 2
[0063] The structure of the suspension roasting system is the same as in Example 1. The suspension roasting method is as follows:
[0064] (1) 600 kg of clay-type lithium ore concentrate (with a Li2O mass percentage of 0.83% and a moisture weight percentage of 3%) is ground to a particle size of -0.074 mm, accounting for 60% of the total mass, and made into mineral powder. This powder is then mixed with a mixture of sodium sulfate and sodium nitrate in mixer 1. The mass ratio of the clay-type lithium ore concentrate powder to the sodium sulfate and sodium nitrate mixture is 1:0.05, and the mass ratio of sodium sulfate to sodium nitrate is 1:2.
[0065] (2) The mixture obtained in step (1) is fed into the preheating furnace 2 by the first screw feeder 13. The mixture obtained in step (1) is preheated and kept at a temperature of 300~400℃ using the waste heat from the tail gas of the first cyclone separator 4. The mixture is then kept at a temperature of 0.5h to obtain salt-melted pre-coated mineral powder.
[0066] (3) The salt-melted pre-coated mineral powder obtained in step (2) is fed into the dispersion dryer 3 by the second screw feeder 14. The exhaust gas at 300~400℃ from the outlet of the cyclone cooler 7 is introduced into the air inlet at the bottom of the dispersion dryer. The exhaust gas is mixed with the mineral powder to disperse and dry the mineral powder. The dried mineral powder is discharged from the outlet of the dispersion dryer 3 along with the hot air and enters the first cyclone separator 4, where it is separated from the gas. Under the condition of starting the induced draft fan 12, the dried mineral powder enters the cyclone preheater 5 before the suspension roasting furnace 6 along with the 500~600℃ hot air from the outlet of the second cyclone separator 7.
[0067] (4) The dried mineral powder obtained in step (3) is placed in the cyclone preheater 5 and exchanged with the 500 ~ 600 ℃ tail gas from the outlet of the second cyclone separator 7 to form preheated mineral powder, which is discharged from the outlet of the cyclone preheater 5 and enters the suspension roasting furnace 6.
[0068] (5) Hot air from the air cooler 9 is introduced into the bottom air inlet of the suspension roasting furnace, and a mixture of natural gas and water gas is introduced into the fuel inlet of the burner at the bottom of the suspension roasting furnace 6. The mixture of natural gas and water gas is burned in the furnace of the suspension roasting furnace 6 to further heat the preheated mineral powder from step (4) to a temperature range of 600 ~ 700 ℃. The mineral powder is in a fluidized suspension state in the suspension roasting furnace under the action of airflow for roasting. The residence time of the mineral powder in the suspension roasting furnace is 30 min, and the air flow rate is 800 mL / min per kilogram of mineral powder.
[0069] (6) The mineral powder obtained after suspension roasting in step (5) is transported by hot air into the second cyclone separator 7 connected to the suspension roasting furnace 6 for gas-solid separation. The obtained mineral powder is transported into the cyclone cooler 8 for air cooling and gas-solid separation. The mineral powder is discharged from the bottom discharge port of the cyclone cooler 8 and sent to the air cooler 9 for further air cooling to obtain roasted clinker. The preheated air in the air cooler 9 is introduced into the burner at the bottom of the suspension roasting furnace 6 as combustion air.
[0070] (7) The 500℃ ~ 600℃ tail gas separated by the second cyclone separator 7 in step (6) is introduced into the cyclone preheater 5 in step (4) as heating gas to preheat the mineral powder; the tail gas of the cyclone preheater 5 passes through the bag filter 10 and then enters the tail gas treatment device 11 for treatment to meet the standards before being discharged; the mineral powder collected by the bag filter 10 is returned to the cyclone preheater 5 and sent back to the suspension roasting furnace 6 for further roasting.
[0071] To test the suspension roasting effect, the roasted clinker obtained in step (6) was ground until the particle size of -0.074 mm accounted for 60% of the total mass, and roasted powder was prepared. The roasted powder was mixed with water at a solid-liquid mass ratio of 1:4 and stirred and soaked in water at 90 °C for 0.5 h to obtain water-soaked material. The water-soaked material was filtered to separate lithium-containing leachate and filter residue. The lithium concentration in the lithium-containing leachate was analyzed and found to be 1.03 g / L. The filter residue was dried and weighed, and the mass percentage of Li2O was analyzed and found to be 0.05%, and the lithium leaching rate was 95.1%.
[0072] Example 3
[0073] The suspension roasting system has the same structure as in Example 1, and the suspension roasting method is as follows:
[0074] (1) 1200 kg of clay-type lithium ore (with a Li2O mass percentage of 0.5% and a moisture weight percentage of 3%) is ground to a particle size of -0.074 mm, accounting for 80% of the total mass, and is made into mineral powder. This powder is then mixed with a mixture of potassium sulfate and potassium nitrate in mixer 1. The mass ratio of the clay-type lithium ore powder to the potassium sulfate and potassium nitrate mixture is 1:0.1, and the mass ratio of potassium sulfate to potassium nitrate is 1:1.
[0075] (2) The mixture obtained in step (1) is fed into the preheating furnace 2 by the first screw feeder 13. The mixture obtained in step (1) is preheated and kept at a temperature of 300~400℃ using the residual heat of the tail gas from the first cyclone separator 4, and the temperature is kept at 1 h to obtain salt melt pre-coated mineral powder.
[0076] (3) The salt-melted pre-coated mineral powder obtained in step (2) is fed into the dispersion dryer 3 by the second screw feeder 14. The exhaust gas at 300~400℃ from the outlet of the cyclone cooler 7 is introduced into the air inlet at the bottom of the dispersion dryer. The exhaust gas is mixed with the mineral powder to disperse and dry the mineral powder. The dried mineral powder is discharged from the outlet of the dispersion dryer 3 along with the hot air and enters the first cyclone separator 4, where it is separated from the gas. Under the condition of starting the induced draft fan 12, the dried mineral powder enters the cyclone preheater 5 before the suspension roasting furnace 6 along with the 500~600℃ hot air from the outlet of the second cyclone separator 7.
[0077] (4) The dried mineral powder obtained in step (3) is placed in the cyclone preheater 5 and exchanged with the 500 ~ 600 ℃ tail gas from the outlet of the second cyclone separator 7 to form preheated mineral powder, which is discharged from the outlet of the cyclone preheater 5 and enters the suspension roasting furnace 6.
[0078] (5) Hot air from the air cooler 9 is introduced into the bottom air inlet of the suspension roasting furnace, and heavy oil is introduced into the fuel inlet of the burner at the bottom of the suspension roasting furnace 6. The heavy oil is burned in the furnace chamber of the suspension roasting furnace 6 to further heat the preheated mineral powder from step (4) to a temperature range of 600 ~ 700 ℃. The mineral powder is in a fluidized suspension state in the suspension roasting furnace under the action of airflow for roasting. The residence time of the mineral powder in the suspension roasting furnace is 20 min, and the air flow rate is 700 mL / min per kilogram of mineral powder.
[0079] (6) The mineral powder obtained after suspension roasting in step (5) is transported by hot air into the second cyclone separator 7 connected to the suspension roasting furnace 6 for gas-solid separation. The obtained mineral powder is transported into the cyclone cooler 8 for air cooling and gas-solid separation. The mineral powder is discharged from the bottom discharge port of the cyclone cooler 8 and sent to the air cooler 9 for further air cooling to obtain roasted clinker. The preheated air in the air cooler 9 is introduced into the burner at the bottom of the suspension roasting furnace 6 as combustion air.
[0080] (7) The 500℃ ~ 600℃ tail gas separated by the second cyclone separator 7 in step (6) is introduced into the cyclone preheater 5 in step (4) as heating gas to preheat the mineral powder; the tail gas of the cyclone preheater 5 passes through the electrostatic precipitator 10 and then enters the tail gas treatment device 11 for treatment to meet the standards before being discharged; the mineral powder collected by the electrostatic precipitator 10 is returned to the cyclone preheater 5 and sent back to the suspension roasting furnace 6 for further roasting.
[0081] To test the suspension roasting effect, the roasted clinker obtained in step (6) was ground until the particle size of -0.074 mm accounted for 80% of the total mass, and roasted powder was prepared. The roasted powder was mixed with water at a solid-liquid mass ratio of 1:4 and stirred and soaked in water at 70 °C for 1 h to obtain water-soaked material. The water-soaked material was filtered to separate lithium-containing leachate and filter residue. The lithium concentration in the lithium-containing leachate was analyzed and found to be 0.82 g / L. The filter residue was dried and weighed, and the mass percentage of Li2O was analyzed and found to be 0.06%, and the lithium leaching rate was 89.8%.
[0082] Comparative Example 1
[0083] The suspension roasting system has the same structure as in Example 1, and the suspension roasting method is as follows:
[0084] (1) 1000 kg of clay-type lithium ore (with a Li2O mass percentage of 0.4% and a moisture weight percentage of 5%) is ground to a particle size of -0.074 mm, accounting for 90% of the total mass, to form ore powder. This powder is then mixed with sodium sulfate in mixer 1 to obtain a mixture. The mass ratio of clay-type lithium ore powder to sodium sulfate is 1:0.3.
[0085] Steps (2)-(7) are the same as in Example 1.
[0086] To test the suspension roasting effect, the roasted clinker obtained in step (6) was ground until 90% of the particle size was -0.074 mm, thus forming roasting powder. The roasting powder was mixed with water at a solid-liquid mass ratio of 1:3 and stirred and soaked in water at 20 °C for 2 h to obtain water-soaked material. The water-soaked material was filtered to separate lithium-containing leachate and filter residue. The lithium concentration in the lithium-containing leachate was analyzed to be 0.13 g / L. The filter residue was dried and weighed, and the mass percentage of Li2O was analyzed to be 0.42%, with a lithium leaching rate of only 6.5%. The results show that when nitrate is not added, only sulfate is added and mixed with clay-type lithium ore powder for suspension roasting, which cannot achieve the implementation effect described in this invention.
[0087] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for salt-melted pre-coated mineral particle suspension roasting of clay-type lithium ore, characterized in that, Includes the following steps: (1) The clay-type lithium ore or its concentrate is ground into mineral powder and mixed with a mixture of alkali metal sulfates and nitrates in a mixer to obtain a mixture; (2) The mixture obtained in step (1) is fed into the preheating furnace using the first screw feeder. The mixture is preheated and kept warm in the range of 300~400℃ using the residual heat of the tail gas from the first cyclone separator to obtain salt melt pre-coated mineral powder. (3) Air is introduced into the air inlets of the cyclone cooler and the air cooler. The salt-melted pre-coated mineral powder obtained in step (2) is conveyed to the dispersion dryer by the second screw feeder. Hot air at 300~400℃ from the air outlet of the cyclone cooler is introduced into the air inlet at the bottom of the dispersion dryer. The hot air is mixed with the mineral powder to disperse and dry the mineral powder. The dried mineral powder is discharged from the outlet of the dispersion dryer along with the hot air and enters the first cyclone separator, where it is separated from the gas. Under the condition of starting the induced draft fan, the dried mineral powder enters the cyclone preheater before the suspension roasting furnace along with the hot air at 500~600℃ from the air outlet of the second cyclone separator. (4) The dried mineral powder obtained in step (3) is placed in a cyclone preheater and exchanged with the 500-600℃ tail gas from the outlet of the second cyclone separator to form preheated mineral powder, which is discharged from the outlet of the cyclone preheater and enters the suspension roasting furnace. (5) Hot air from the air cooler is introduced into the bottom air inlet of the suspension roasting furnace, and fuel is introduced into the fuel inlet of the bottom burner of the suspension roasting furnace. The fuel is burned in the furnace chamber of the suspension roasting furnace to further heat the mineral powder from step (4) to a temperature range of 600 ~ 700℃. The mineral powder is in a fluidized suspension state in the suspension roasting furnace under the action of airflow for roasting. (6) The mineral powder obtained after suspension roasting in step (5) is transported by hot air into the second cyclone separator connected to the suspension roasting furnace for gas-solid separation. The obtained mineral powder is then transported into the cyclone cooler for air cooling and gas-solid separation. The mineral powder is discharged from the bottom discharge port of the cyclone cooler and sent to the air cooler for further air cooling to obtain roasted clinker. The preheated air in the air cooler is introduced into the burner at the bottom of the suspension roasting furnace as combustion air. (7) The 500-600℃ tail gas obtained by the second cyclone separator in step (6) is introduced into the cyclone preheater in step (4) as heating gas to preheat the mineral powder; the tail gas of the cyclone preheater is treated by a bag filter or electrostatic precipitator and then discharged after meeting the standards; the mineral powder collected by the bag filter or electrostatic precipitator is returned to the cyclone preheater and sent back to the suspension roasting furnace for further roasting.
2. The salt-melting pre-coated ore particle suspension roasting method for clay-type lithium ore according to claim 1, characterized in that, A suspension roasting system for pre-coated clay-type lithium ore particles using salt fusion is employed. The system includes a mixer, a preheating furnace, a dispersion dryer, a first cyclone separator, a cyclone preheater, a suspension roasting furnace, a second cyclone separator, a cyclone cooler, an air cooler, a bag filter or electrostatic precipitator, a tail gas treatment device, an induced draft fan, a first screw feeder, and a second screw feeder, wherein: The mixer has an inlet at the top for feeding mineral powder and a mixture of alkali metal sulfates and nitrates; the outlet at the bottom of the mixer is connected to the inlet of the preheating furnace via a first screw feeder; the outlet of the preheating furnace is connected to the inlet of the dispersion dryer via a second screw feeder; the air inlet of the dispersion dryer is connected to the air outlet of the cyclone cooler via a pipe; and the outlet of the dispersion dryer is connected to the inlet of the first cyclone separator. The outlet of the first cyclone separator is connected to the inlet of the preheating furnace; the outlet of the first cyclone separator is connected to the outlet pipe of the second cyclone separator through the feed pipe, and is also connected to the inlet of the cyclone preheater; the solid phase outlet of the cyclone preheater is connected to the inlet of the suspension roasting furnace; the outlet of the cyclone preheater is connected to the inlet of the bag filter or electrostatic precipitator; the lower outlet of the bag filter or electrostatic precipitator is connected to the inlet of the cyclone preheater; the upper outlet of the bag filter or electrostatic precipitator is connected to the inlet of the exhaust gas treatment device; the outlet of the exhaust gas treatment device is connected to the inlet of the induced draft fan. The discharge port of the suspension roasting furnace is connected to the inlet of the second cyclone separator; the lower part of the suspension roasting furnace is equipped with a fuel inlet for fuel introduction; the discharge port of the second cyclone separator is connected to the inlet of the cyclone cooler; the discharge port of the cyclone cooler is connected to the inlet of the air cooler; the air outlet of the cyclone cooler is connected to the air inlet of the dispersion dryer through a pipe; the air inlet of the suspension roasting furnace is connected to the air outlet of the air cooler through a pipe, and the roasted clinker discharge port is located below the air cooler.
3. The salt-melting pre-coated ore particle suspension roasting method for clay-type lithium ore according to claim 1, characterized in that, In step (1), the portion of the mineral powder with a particle size of -0.074 mm accounts for 60-90% of the total mass of the mineral powder.
4. The salt-melting pre-coated ore particle suspension roasting method for clay-type lithium ore according to claim 1, characterized in that, The mass percentage of Li2O in the clay-type lithium ore in step (1) is 0.4 to 0.5%, the mass percentage of Li2O in the clay-type lithium ore concentrate is 0.6 to 1.0%, and the weight percentage of moisture in the clay-type lithium ore or its concentrate is 1 to 5%.
5. The method for salt-melted pre-coated ore particle suspension roasting of clay-type lithium ore according to claim 1, characterized in that, In step (1), the added alkali metal sulfate is sodium sulfate and / or potassium sulfate, and the added alkali metal nitrate is sodium nitrate and / or potassium nitrate. The mass ratio of the clay-type lithium ore powder to the mixed salt is 1:0.05 ~ 1:0.3, and the mass ratio of sulfate to nitrate in the mixed salt of alkali metal sulfate and nitrate is 2:1 ~ 1:
2.
6. The method for salt-melted pre-coated ore particle suspension roasting of clay-type lithium ore according to claim 1, characterized in that, In step (2), the preheating time of the mixture is 0.5 to 2 hours.
7. The method for salt-melted pre-coated ore particle suspension roasting of clay-type lithium ore according to claim 1, characterized in that, The dispersion dryer mentioned in step (3) is a Venturi dryer, a flash dryer, or a drying and dispersing machine.
8. The method for salt-melted pre-coated ore particle suspension roasting of clay-type lithium ore according to claim 1, characterized in that, In step (5), the residence time of the mineral powder in the suspension roasting furnace is 10 to 30 minutes, and the air flow rate is 500 to 800 mL / min per kilogram of mineral powder.
9. The method for salt-melted pre-coated ore particle suspension roasting of clay-type lithium ore according to claim 1, characterized in that, In step (5), the fuel used in the burner of the suspension roasting furnace is an alkane fuel, including one or more of heavy oil, natural gas, and liquefied petroleum gas.
10. The method for salt-melted pre-coated ore particle suspension roasting of clay-type lithium ore according to claim 1, characterized in that, To test the suspension roasting effect, the roasted clinker obtained in step (6) was ground until the particle size of -0.074 mm accounted for 60 to 90% of the total mass, and roasted powder was prepared. The roasted powder was mixed with water at a solid-liquid mass ratio of 1:3 to 1:4 and stirred and soaked in water at 20 to 100°C for 0.5 to 2 hours to obtain water-soaked material. The water-soaked material was filtered to separate lithium-containing leachate and filter residue. The lithium-containing leachate and filter residue were sampled and sent for analysis to detect the lithium content.