A method for accurately controlling the directional transformation of spodumene crystal forms

Abstract

The invention relates to the field of ore processing, and in particular to a method for accurately controlling the directional transformation of spodumene crystal forms, comprising S1, raw material preparation: obtaining spodumene raw materials with a diameter of less than 3 mm; S2, raw material preheating: heating by multiple cyclone separators to quickly make the temperature of spodumene reach 300-500 DEG C; S3, raw material heating: heating the preheated spodumene raw materials to quickly raise the temperature to 900-1000 DEG C; S4, precise temperature control-crystal form transformation: feeding into a dense phase fluidized bed, adding 100-1000g / t of calcium oxide, calcium carbonate or carbide slag at the same time, controlling the insulation time to 5-30min, and realizing precise control of the material temperature by external compensation electromagnetic heating at the same time, and controlling the temperature to between 950-1100 DEG C; S5, waste heat recovery: recovering the residual heat of the spodumene raw materials to cool the materials to 50-200 DEG C. The present invention realizes the directional crystal transformation of α-spodumene to β-spodumene, and has the characteristics of high conversion rate, low energy consumption, high operation rate, easy promotion and application, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of ore processing and treatment, and specifically relates to a method for accurately controlling the directional transformation of spodumene crystal forms. Background Art

[0002] Due to its excellent performance, lithium is widely used in batteries, automobiles, nuclear fusion, glass, ceramics and other fields, and runs through seven major industries: energy conservation and environmental protection, new generation information technology, biology, high-end equipment manufacturing, new energy, new materials and new energy vehicles.

[0003] Since spodumene in nature mainly exists in the form of α-spodumene, it has stable chemical properties and is difficult to react with acids and alkalis at room temperature and pressure. However, α-spodumene undergoes a crystal transformation under high temperature conditions to β-spodumene with a looser structure and poorer chemical stability, and then is leached after sulfuric acid aging to achieve the extraction and utilization of lithium resources. The traditional resistance heating method has a large thermal hysteresis and is not easy to accurately control the temperature. When the temperature is too high, it is easy to over-sinter the ring and then generate γ-spodumene, making it difficult to leach spodumene. During the roasting process of spodumene, a small amount of low-melting-point substances are heated at the same time. Its melting point is generally 900-1100℃, and its main components are iron-containing mica, low-melting-point feldspar, etc. During the roasting process of spodumene feldspar, these low-melting-point substances accumulate and are prone to "ringing" or "scarring" in the dead corners or side walls of the equipment, resulting in low roasting efficiency.

[0004] At present, the transformation roasting of spodumene mainly adopts traditional methods such as rotary kiln roasting. There are also patents that use suspension roasting or fluidized bed reactors to transform spodumene. For example, patent CN107739847A discloses a crystal transformation method of natural spodumene by suspension roasting, which discloses that natural α-spodumene is ground into a certain particle size and then put into a secondary suspension roasting furnace for fluidized drying and preheating. The preheated spodumene powder is then passed through a secondary cyclone dust collector and a dust collector for gas-solid separation, and then put into a primary suspension roasting furnace. High-temperature gas is used for suspension roasting to make the stone powder undergo preliminary crystal transformation. After separation in a primary cyclone dust collector, the obtained high-temperature mineral powder is placed in an insulation tank to complete the crystal transformation, and finally transferred to a cooler for cooling to obtain β-spodumene. Although the suspension roaster of the patent can achieve a good conversion rate, on the one hand, due to the small particle size of the grinding, grinding is the main energy-consuming unit in the field of mineral processing, so there are disadvantages such as high energy consumption and high dust in the production environment; on the other hand, the core of the patent is the suspension roaster + insulation tank, but the heating speed of the suspension roaster is fast, and the insulation time of the insulation tank is long, resulting in the need for a very large insulation tank to meet the needs of industrial continuous production, otherwise the suspension roaster can only be intermittent production. In addition, industrial insulation tanks are often columnar. With the accumulation of high-temperature mineral powder in the insulation tank, γ-spodumene is easily converted under high temperature and high pressure conditions. In addition, the patent does not solve the fundamental problem that low-melting-point substances are easy to form rings during the roasting of spodumene.

[0005] Patent CN102906022B discloses a method for processing spodumene, which uses oxygen-containing gas as fluidizing gas to process concentrate or ore with a particle size of 20-1000 μm in a fluidized bed reactor at a temperature of 800-1000°C. The patent only records the theoretical energy consumption, so it is only a theoretical design, and the result of the design is to avoid the generation of more than 15% of the molten phase; data show that the conversion temperature of β-spodumene requires 1050°C, so the theoretical design is not in line with reality, and the effect of the theoretical design is not good.

[0006] Existing technologies generally have problems such as high energy consumption and low crystal conversion rate. Improving the crystal conversion process of spodumene is of great significance to improving the resource utilization rate of spodumene. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for accurately controlling the directional transformation of spodumene crystal forms.

[0008] The object of the present invention is achieved through the following technical solutions: a method for accurately controlling the directional transformation of spodumene crystal forms, the transformation method is implemented based on a device formed by sequentially connecting a preheating system, a hot air circulation heating furnace, a dense phase fluidized bed, and a waste heat recovery system;

[0009] The preheating system is composed of a spiral feeder and a plurality of cyclone separators connected in series;

[0010] The dense phase fluidized bed comprises a reaction chamber cavity, a feed inlet and a discharge port are respectively arranged on both sides of the reaction chamber cavity, a spiral doser is arranged near the feed inlet of the reaction chamber cavity, a baffle extending from bottom to top is arranged in the middle of the reaction chamber cavity along the direction from the feed inlet to the discharge port, so as to increase the flow time of the ore raw material in the reaction chamber cavity, an electromagnetic heating ring surrounding the outside of the reaction chamber cavity and a thermoelectric extending into the reaction chamber cavity are arranged on the reaction chamber cavity, a gas permeable plate is arranged in the gap on the upper side of the inner bottom surface of the reaction chamber cavity, and an air inlet is arranged at the bottom of the dense phase fluidized bed;

[0011] The waste heat recovery system is composed of a plurality of cyclone separators connected in series;

[0012] The transformation method comprises the following steps:

[0013] S1. Raw material preparation: crushing and grinding the spodumene raw material to obtain spodumene raw material with a particle size of less than -3 mm;

[0014] S2, raw material preheating: the spodumene raw material is fed into the preheating system through a screw feeder, and the flue gas of multiple cyclone separators is heated to quickly reach a temperature of 300-500° C.;

[0015] S3, raw material heating: using a hot air circulation heating furnace to heat the preheated spodumene raw material with hot air, so that the temperature of the spodumene raw material is quickly raised to 900-1000°C;

[0016] S4, precise temperature control - crystal transformation: the heated spodumene raw material is fed into a dense phase fluidized bed, and 100-1000 g / t of calcium oxide, calcium carbonate or carbide slag is added through a spiral dosing machine. The material is placed in a highly turbulent state under the action of hot air, and the hot air introduction speed is 0.02 m / s-2 m / s. At the same time, the material temperature is precisely controlled by external compensation electromagnetic heating, and the temperature is controlled to between 950 and 1100 ° C. At the same time, the air introduction amount is controlled to control the material insulation time in the crystal transformation chamber to 5-30 min;

[0017] S5, waste heat recovery: The residual heat of the spodumene raw material is recovered through the waste heat recovery system, and the material is cooled to 50-200° C. The spodumene after the crystal transformation also carries a large amount of heat. The heat of the material is recovered in step (5) through a cyclone waste heat recovery device or a waste heat boiler to reduce energy consumption.

[0018] Furthermore, the spodumene raw material includes: spodumene ore with a Li2O content of 0.5% to 8%, spodumene intermediates and spodumene concentrates obtained during the spodumene processing. The roasting particle size is closely related to the processing process. Generally, the concentrate obtained by direct roasting of the ore or heavy medium separation can control the particle size below -3mm, and the lithium concentrate or intermediates obtained by flotation generally have a particle size below 0.1mm, so there is no need to crush it again.

[0019] Furthermore, the specific components and connection modes of the preheating system are as follows:

[0020] The preheating system is composed of a spiral feeder and three cyclone separators connected in series, wherein the three cyclone separators are respectively a first-stage cyclone separator, a second-stage cyclone separator and a third-stage cyclone separator, wherein the material outlet end of the spiral feeder is connected to the flue gas duct of the second-stage cyclone separator and is connected to the inlet of the first-stage cyclone separator, the spodumene raw material enters the first-stage cyclone separator after being mixed with the flue gas, the flue gas duct of the first-stage cyclone separator enters the flue gas treatment system, the material leg of the first-stage cyclone separator is connected to the flue gas duct of the third-stage cyclone separator and is connected to the inlet of the second-stage cyclone separator, the spodumene raw material enters the second-stage cyclone separator after being mixed with the flue gas, the material leg of the second-stage cyclone separator is connected to the heated hot flue gas and is connected to the inlet of the third-stage cyclone separator, the spodumene raw material enters the third-stage cyclone separator after being mixed with the flue gas, and the material of the third-stage cyclone separator leg is the preheated spodumene raw material.

[0021] Furthermore, the hot flue gas used by the preheating system comes from the hot flue gas exhausted from the hot air circulation heating furnace.

[0022] Furthermore, the hot air used in the hot air circulation heating furnace comes from: burning liquefied gas, coal powder, and petroleum fuel to generate high-temperature hot air, which is used to heat the preheated spodumene, rapidly raising its temperature to 900-1000°C.

[0023] Furthermore, a small amount of compressed air is introduced into the air inlet of the dense phase fluidized bed, and the material temperature is quickly heated to 950-1100° C. through the electromagnetic heating ring around the dense phase fluidized bed.

[0024] Furthermore, the specific components and connection methods of the waste heat recovery system are as follows:

[0025] The waste heat recovery system is composed of three cyclone separators connected in series, namely the first cyclone separator, the second cyclone separator and the third cyclone separator. After the spodumene raw material is transformed into a dense fluidized bed, it is connected to the flue gas duct of the second cyclone separator and connected to the inlet of the first cyclone separator. The flue gas duct of the first cyclone separator produces hot air used by the hot air circulation heating furnace. The material leg of the first cyclone separator is connected to the flue gas duct of the third cyclone separator and connected to the inlet of the second cyclone separator. The material leg of the second cyclone separator is connected to cold air and connected to the inlet of the third cyclone separator. The three-stage cyclone separator legs are cooling products.

[0026] Furthermore, the following steps are included: S6, airflow crushing: the cooled material is directly introduced into the airflow crusher to crush the material to less than 0.1 mm. Since the particle size required for the spodumene leaching process is about -0.1 mm, the airflow crusher is an efficient powder crushing equipment, and there is no need to consider the dust removal problem during the crushing process.

[0027] The main features of the present invention are: separating the heating process of spodumene from the crystal transformation process, the heating process is lower than the melting point of the low-melting-point substance in the spodumene, which can ensure that the process does not produce ringing or scarring, adding an inhibitor of the low-melting-point substance in the high-temperature area to inhibit the melting of the iron-containing and potassium-sodium-containing low-melting-point substances, thereby ensuring that no ringing or scarring occurs in the high-temperature crystal transformation chamber; precise temperature control is achieved through electromagnetic heating in the crystal transformation process, and at the same time, high-speed gas is used to put the material in a high-speed turbulent state, thereby avoiding the problem of excessive local temperature, achieving precise directional transformation of spodumene, and then adjusting the gas size to achieve the residence time of the material in the crystal transformation device, and through control of multiple means, efficient and precise directional transformation of α-spodumene into β-spodumene is achieved.

[0028] Through multi-stage preheating and waste heat recovery, the heat is circulated internally as much as possible, thereby effectively reducing the energy consumption of roasting. Considering the particle size required for spodumene leaching, combined with the characteristics of spodumene becoming fluffy and easy to grind after transformation roasting, high-speed airflow pulverization is used to prepare spodumene products suitable for leaching.

[0029] The beneficial effects of the present invention are:

[0030] 1. It can effectively improve the crystal form conversion rate of spodumene, which is more conducive to leaching of spodumene. The crystal form conversion rate of spodumene roasted in a traditional rotary kiln is only about 90%. After the precise crystal form conversion of the present invention, the crystal form conversion rate of spodumene can reach more than 95%.

[0031] 2. Lower roasting energy consumption and high operating rate. The traditional rotary kiln has high energy consumption for roasting. After multi-stage waste heat recovery, the new roasting method can reduce energy consumption by more than 20%. At the same time, it avoids the ring formation phenomenon during the roasting process of the rotary kiln, and the roasting operating rate is significantly improved.

[0032] 3. Wide application scope. Spodumene is the main mining target of lithium resources in my country. It is mainly distributed in eight lithium belts, including the Songpan-Ganzi lithium belt, the Altai lithium belt, the Qinling lithium belt, and the South China lithium belt in Sichuan and Xinjiang. With the rapid development of my country's new energy industry, the demand for lithium resources is increasing, and the imbalance between supply and demand of lithium resources is becoming more and more serious. Therefore, the efficient extraction of spodumene will have more and more application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of the crystal transformation device of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of the preheating system of the present invention;

[0035] Figure 3 This is a schematic diagram of the structure of the waste heat recovery system of the present invention;

[0036] In the figure, 1. feed inlet, 2. discharge outlet, 3. air permeable plate, 4. air inlet, 5. electromagnetic heating coil, 6. baffle, 7. thermocouple, 8. reaction chamber cavity, 9. spiral dosing machine, 10. spiral feeder, 11. cyclone separator. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0038] Example 1

[0039] Reference Figure 1-3 , a device for precisely controlling the directional conversion of spodumene crystal forms, which is formed by sequentially connecting a preheating system, a hot air circulation heating furnace, a dense phase fluidized bed, and a waste heat recovery system;

[0040] The preheating system is composed of a spiral feeder 10 and a plurality of cyclone separators 11 connected in series; preferably, the preheating system is composed of a spiral feeder 10 and three cyclone separators 11 connected in series, the three cyclone separators 11 are respectively a first-stage cyclone separator, a second-stage cyclone separator and a third-stage cyclone separator, the material outlet end of the spiral feeder 10 is connected to the flue gas duct of the second-stage cyclone separator and is connected to the inlet of the first-stage cyclone separator, and the spodumene raw material is mixed with the flue gas and enters the first-stage cyclone separator. The flue gas duct of the first-stage cyclone separator enters the flue gas treatment system, the feed leg of the first-stage cyclone separator is connected to the flue gas duct of the third-stage cyclone separator and is connected to the inlet of the second-stage cyclone separator. The spodumene raw material and the flue gas are mixed and enter the second-stage cyclone separator. The feed leg of the second-stage cyclone separator is connected to the heated hot flue gas and is connected to the inlet of the third-stage cyclone separator. The spodumene raw material and the flue gas are mixed and enter the third-stage cyclone separator. The leg of the third-stage cyclone separator is the preheated spodumene raw material.

[0041] The hot air circulation heating furnace is a commonly used ore powder heating equipment. The preheated spodumene raw material needs to be heated again by the hot air circulation heating furnace to obtain the heated spodumene raw material.

[0042] The dense phase fluidized bed comprises a reaction chamber cavity 8, a feed port 1 and a discharge port 2 are respectively arranged on both sides of the reaction chamber cavity 8, a spiral doser 9 is arranged near the feed port 1 of the reaction chamber cavity 8, a baffle 6 extending from bottom to top is arranged in the middle of the reaction chamber cavity 8 along the direction from the feed port 1 to the discharge port 2, so as to increase the flow time of the ore raw material in the reaction chamber cavity 8, an electromagnetic heating coil 5 surrounding the outside of the reaction chamber cavity 8 and a thermocouple 7 extending into the reaction chamber cavity 8 are arranged on the reaction chamber cavity 8, a breathable plate 3 is arranged in the upper gap of the inner bottom surface of the reaction chamber cavity 8, and an air inlet 4 is arranged at the bottom of the dense phase fluidized bed; the heated spodumene raw material is transformed through the dense phase fluidized bed to obtain a transformation product. Compared with a conventional fluidized bed, the dense phase fluidized bed of the present invention mainly differs in the design of the spiral doser 9 and the electromagnetic heating coil 5, and the structural design of other control systems and the like can refer to the conventional fluidized bed.

[0043] The waste heat recovery system is composed of multiple cyclone separators 11 connected in series; preferably, the waste heat recovery system is composed of three cyclone separators 11 connected in series, namely the first cyclone separator, the second cyclone separator and the third cyclone separator, the transformation product is connected to the flue gas duct of the second cyclone separator and is connected to the inlet of the first cyclone separator, the flue gas duct of the first cyclone separator produces hot air used by the hot air circulation heating furnace, the material leg of the first cyclone separator is connected to the flue gas duct of the third cyclone separator and is connected to the inlet of the second cyclone separator, the material leg of the second cyclone separator is connected to the cold air and is connected to the inlet of the third cyclone separator, and the three-stage cyclone separator leg is the cooling product.

[0044] If the particle size of the cooled product is larger than 0.1 mm, the cooled product can be passed into a jet mill to crush the material to less than 0.1 mm to meet the particle size requirement for spodumene leaching.

[0045] Example 2

[0046] The spodumene ore from a Sichuan ore dressing plant with a Li2O content of 3.00% was crushed and ground to obtain ore powder with a diameter of -0.074 mm and a proportion of 65%. The ore powder was evenly fed into the preheating system through a screw feeder, preheated to 500°C, and then entered the hot air circulation heating furnace to be heated to 950°C, and then entered the dense phase fluidized bed, where 200g / t of calcium oxide was added, the temperature was controlled at 1050°C, the gas flow rate was 0.5m / s, and the residence time was 20min; then the ore powder entered the waste heat recovery system to be cooled to 50°C and discharged from the system. The product is leached by sulfuric acid aging. The sulfuric acid aging conditions are: the amount of sulfuric acid is 1.4 times the theoretical value, the aging temperature is 250℃, and the aging time is 30min. The aging material is then immersed in water for 30min at a liquid-solid ratio of 2:1mL / g, 25℃, and 200rpm. Finally, the lithium-rich solution and leached residue are obtained by filtration. The Li2O content in the leached residue is only 0.23%, and the lithium leaching rate reaches 95.43%.

[0047] Example 3

[0048] The spodumene reselection concentrate from Xinjiang is used, with a Li2O content of 3.50% and a particle size of -3mm. The ore powder is evenly fed into the preheating system through a screw feeder, preheated to 300℃, and then enters the hot air circulation heating furnace to heat to 1000℃, and then enters the dense phase fluidized bed, adds 500g / t of calcium carbonate, controls the temperature to 1070℃, the gas flow rate to 1m / s, and the residence time to 30min; then enters the cooling system to cool to 100℃, and then is crushed to -0.1mm by a gas flow mill and discharged from the system. The product is leached by sulfuric acid aging, and the sulfuric acid aging conditions are: the amount of sulfuric acid is 1.4 times the theoretical value, the aging temperature is 250℃, and the aging time is 30min. The aging material is then immersed in water for 30min under the conditions of liquid-solid ratio 2:1mL / g, 25℃, and 200rpm. Finally, the lithium-rich solution and leached slag can be obtained by filtration. The Li2O content in the leached slag is only 0.21%, and the lithium leaching rate reaches 96.25%.

[0049] Example 4

[0050] The raw spodumene ore of Africa is used, with a Li2O content of 1.20% and a particle size of -2mm. The ore powder is evenly fed into the preheating system through a screw feeder, preheated to 400℃, and then enters the hot air circulation heating furnace to heat to 900℃, and then enters the dense phase fluidized bed, adds 1000g / t of calcium carbide slag, controls the temperature to 1020℃, the gas flow rate to 1.5m / s, and the residence time to 10min; then enters the cooling system to cool to 200℃, and then is crushed to -0.1mm by a gas flow mill and discharged from the system. The product is leached by sulfuric acid aging, and the sulfuric acid aging conditions are: the amount of sulfuric acid is 1.4 times the theoretical value, the aging temperature is 250℃, and the aging time is 30min. The aging material is then immersed in water for 30min under the conditions of liquid-solid ratio 2:1mL / g, 25℃, and 200rpm. Finally, the lithium-rich solution and leached slag can be obtained by filtration. The Li2O content in the leached slag is only 0.11%, and the lithium leaching rate reaches 97.49%.

[0051] Example 5

[0052] A spodumene flotation concentrate from Sichuan was used, with a Li2O content of 5.50% and a particle size of -0.075mm accounting for 75%. The ore powder was evenly fed into the preheating system through a screw feeder, preheated to 500℃, and then entered the hot air circulation heating furnace to heat to 1000℃, and then entered the dense phase fluidized bed, added 500g / t of calcium oxide, controlled the temperature to 1080℃, the gas flow rate to 0.8m / s, and the residence time to 15min; then entered the cooling system to cool to 100℃ and discharged from the system. The product was leached by sulfuric acid aging, and the sulfuric acid aging conditions were: sulfuric acid dosage was 1.4 times the theoretical value, aging temperature was 250℃, aging time was 30min, and the aging material was then immersed in water for 30min under the conditions of liquid-solid ratio 2:1mL / g, 25℃, and 200rpm. Finally, lithium-rich solution and leached slag were obtained by filtration. The Li2O content in the leached slag was only 0.18%, and the lithium leaching rate reached 98.13%.

[0053] Comparative Example 1

[0054] The only difference between Comparative Example 1 and Example 2 is that the spiral dosing machine is not started, that is, calcium oxide is not added, and other conditions are the same. The lithium-rich solution and leached residues finally obtained have a Li2O content of 0.34% in the leached residues and a lithium leaching rate of 92.24%. In addition, Example 2 does not produce obvious ring formation, while Comparative Example 1 produces slight ring formation.

[0055] Comparative Example 2

[0056] The difference between Comparative Example 2 and Example 2 is that the electromagnetic heating coil 5 is not provided in the dense phase fluidized bed, and a conventional heat exchange device is used. The lithium-rich solution and leached slag obtained finally have a Li2O content of 0.37% and a lithium leaching rate of 91.67%. In addition, the ring formation phenomenon in Comparative Example 2 is more obvious than that in Comparative Example 1.

[0057] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for accurately controlling the directional transformation of spodumene crystal forms, characterized in that: The conversion method is realized based on a device formed by sequentially connecting a preheating system, a hot air circulation heating furnace, a dense phase fluidized bed, and a waste heat recovery system; The preheating system is composed of a screw feeder (10) and a plurality of cyclone separators (11) connected in series; The dense phase fluidized bed comprises a reaction chamber cavity (8), wherein a feed port (1) and a discharge port (2) are respectively arranged on both sides of the reaction chamber cavity (8), a spiral dosing machine (9) is arranged near the feed port (1) of the reaction chamber cavity (8), a baffle (6) extending from bottom to top is arranged in the middle of the reaction chamber cavity (8) in the direction from the feed port (1) to the discharge port (2) to increase the flow time of the ore raw material in the reaction chamber cavity (8), an electromagnetic heating ring (5) surrounding the outside of the reaction chamber cavity (8) and a thermocouple (7) extending into the reaction chamber cavity (8) are arranged on the reaction chamber cavity (8), a gas permeable plate (3) is arranged in the gap on the upper side of the inner bottom surface of the reaction chamber cavity (8), and an air inlet (4) is arranged at the bottom of the dense phase fluidized bed; The waste heat recovery system is composed of a plurality of cyclone separators (11) connected in series; The transformation method comprises the following steps: S1. Raw material preparation: crushing and grinding the spodumene raw material to obtain spodumene raw material with a particle size of less than -3 mm; S2, raw material preheating: the spodumene raw material is fed into a preheating system through a screw feeder (10), and the temperature of the spodumene raw material is quickly raised to 300-500° C. through heating by a plurality of cyclone separators (11); S3, raw material heating: using a hot air circulation heating furnace to heat the preheated spodumene raw material with hot air, so that the temperature of the spodumene raw material is quickly raised to 900-1000°C; S4, precise temperature control - crystal transformation: the heated spodumene raw material is fed into a dense phase fluidized bed, and 100-1000 g / t of calcium oxide, calcium carbonate or carbide slag is added through a spiral dosing machine (9). The material is placed in a highly turbulent state under the action of hot air, and the hot air introduction speed is 0.02 m / s-2 m / s. At the same time, the material temperature is precisely controlled by external compensation electromagnetic heating, and the temperature is controlled to between 950 and 1100° C. At the same time, the air introduction amount is controlled to control the material insulation time in the crystal transformation chamber to 5-30 min; S5, waste heat recovery: the residual heat of the spodumene raw material is recovered through the waste heat recovery system to cool the material to 50-200°C; The spodumene raw materials include: spodumene ore with a Li2O content of 0.5% to 8%, spodumene intermediate ore and spodumene concentrate obtained during the spodumene processing.

2. A method for accurately controlling directional transformation of spodumene crystal forms according to claim 1, characterized in that: The specific composition and connection mode of the preheating system are as follows: The preheating system is composed of a spiral feeder (10) and three cyclone separators (11) connected in series. The three cyclone separators (11) are respectively a first-stage cyclone separator, a second-stage cyclone separator and a third-stage cyclone separator. The material outlet end of the spiral feeder (10) is connected to the flue gas duct of the second-stage cyclone separator and is connected to the inlet of the first-stage cyclone separator. After the spodumene raw material is mixed with the flue gas, it enters the first-stage cyclone separator. The flue gas duct of the first-stage cyclone separator enters the flue gas treatment system. The feed leg of the first-stage cyclone separator is connected to the flue gas duct of the third-stage cyclone separator and is connected to the inlet of the second-stage cyclone separator. After the spodumene raw material is mixed with the flue gas, it enters the second-stage cyclone separator. The feed leg of the second-stage cyclone separator is connected to the heated hot flue gas and is connected to the inlet of the third-stage cyclone separator. After the spodumene raw material is mixed with the flue gas, it enters the third-stage cyclone separator. The material of the third-stage cyclone separator is the preheated spodumene raw material.

3. A method for accurately controlling directional transformation of spodumene crystal forms according to claim 2, characterized in that: The hot flue gas used by the preheating system comes from the hot flue gas discharged from the hot air circulation heating furnace.

4. A method for accurately controlling directional transformation of spodumene crystal forms according to claim 1, characterized in that: The hot air used in the hot air circulation heating furnace comes from: burning liquefied gas, coal powder, and petroleum fuel to produce high-temperature hot air, which is used to heat the preheated spodumene, rapidly raising its temperature to 900-1000°C.

5. A method for accurately controlling directional transformation of spodumene crystal forms according to claim 1, characterized in that: A small amount of compressed air is introduced into the air inlet (4) of the dense phase fluidized bed, and the material temperature is rapidly raised to 950-1100° C. through the electromagnetic heating ring (5) around the dense phase fluidized bed.

6. A method for accurately controlling directional transformation of spodumene crystal forms according to claim 1 or 5, characterized in that: The specific composition and connection method of the waste heat recovery system is as follows: The waste heat recovery system is composed of three cyclone separators (11) connected in series, namely the first cyclone separator, the second cyclone separator and the third cyclone separator. After the spodumene raw material is transformed into a dense phase fluidized bed, it is connected to the flue gas duct of the second cyclone separator and connected to the inlet of the first cyclone separator. The flue gas duct of the first cyclone separator produces hot air used by the hot air circulation heating furnace. The feed leg of the first cyclone separator is connected to the flue gas duct of the third cyclone separator and connected to the inlet of the second cyclone separator. The feed leg of the second cyclone separator is connected to cold air and connected to the inlet of the third cyclone separator. The three-stage cyclone separator leg is the cooling product.

7. A method for accurately controlling directional transformation of spodumene crystal forms according to claim 6, characterized in that: The following steps are also included: S6. Airflow pulverization: The cooled material is directly fed into the airflow pulverizer to pulverize the material to less than 0.1 mm.

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