Electricity, gas and suspension three-composite lithium ore roasting kiln system and technology

Abstract

The invention discloses an electricity, gas and suspension three-composite lithium ore roasting kiln system and process. The alpha-type spodumene is converted into the beta-type spodumene through constant-speed drying and preheating of a suspension preheating device, primary roasting of an electric heating kiln and secondary roasting of a gas kiln. Compared with traditional transformation roasting of spodumene in a rotary kiln with natural gas as fuel, the method has the advantages that the temperature of spodumene is increased to 600-800 DEG C through preheating of the suspension preheating device and one-time roasting of the electric heating kiln, only the rear-section temperature rising work needs to be completed in the gas kiln, a large amount of natural gas resources can be saved, meanwhile, emission of carbon dioxide is reduced, and the production cost is reduced. The device accords with the national carbon neutralization policy, and is very suitable for being used in areas which are lack of natural gas, rich in electric power reserve or low in electricity price and high in environmental protection requirement.

Description

Technical Field

[0001] The invention relates to the field of lithium ore roasting kilns, and in particular to an electric, gas and suspension three-composite lithium ore roasting kiln system and process. Background Art

[0002] In industrial production, spodumene is mainly used as the raw material for lithium extraction by sulfuric acid method. Before acid roasting, spodumene needs to be transformed in a roasting kiln to transform the α-type spodumene with high density and stable chemical properties into β-type spodumene with low density, loose structure and the ability to react with acid and alkali. The quality of the transformation roasting directly affects the lithium extraction rate.

[0003] At present, natural gas or pulverized coal is mostly used as fuel for the transformation roasting of spodumene. The rotary kiln is heated by fuel combustion, so that the air in the kiln is heated to above 1100℃ to roast spodumene, realizing the transformation of spodumene from α crystal form to β crystal form. However, there are many problems with the above production method. First, the distribution of natural gas resources is uneven. For areas lacking natural gas but with sufficient electricity resources, if a rotary kiln (hereinafter referred to as "gas kiln") using natural gas as fuel is used to roast spodumene, it will incur very high natural gas procurement, transportation and storage costs; secondly, the natural gas combustion process will produce a large amount of carbon dioxide gas, which is not in line with the national "energy conservation and emission reduction" policy guidelines when discharged into the air; in addition, the gas kiln used for spodumene roasting often needs to be tens of meters long, and the burner spray at the kiln head cannot ensure uniform heat transfer in the entire kiln, resulting in unstable temperature in the burning zone, affecting the transformation effect of spodumene; and the cylinder is too long, which will also cause unnecessary heat loss in the waste heat recovery process of the internal circulation system, thereby increasing the overall energy consumption of the system.

[0004] The existing electric heating rotary kiln mainly uses the thermal effect of electric current or the principle of electromagnetic induction to heat the spodumene material in the kiln. Although it reduces carbon emissions to a certain extent and the temperature field in the kiln is relatively stable, whether it is through the thermal effect of electric current or electromagnetic heating, the rotary kiln cylinder itself will be heated. During the spodumene transition roasting process, the rotating cylinder is continuously heated at a high temperature of more than 1100°C. The existing conventional cylinder materials cannot guarantee the cylinder strength during industrial continuous production. At present, in the spodumene pyrometallurgical process, electric heating kilns are only used in the acidification roasting stage with a temperature requirement of 250-280°C, and cannot be used as transition roasting kilns. Summary of the invention

[0005] In order to overcome the deficiencies in the above-mentioned prior art, the present invention provides an electric, gas, and suspension three-composite lithium ore roasting kiln system and process, wherein the ore is dried in the suspension preheating section, the electric heating kiln completes the ore heating process, and the high-temperature roasting is achieved by the gas kiln. The above-mentioned process flow provides an efficient and stable temperature field for lithium ore roasting while ensuring the use of natural gas as little as possible, thereby improving the efficiency of lithium ore roasting.

[0006] The specific technical solutions are as follows: An electric, gas and suspension three-composite lithium ore roasting kiln system comprises a silo, a metering device, a suspension preheating device, a lithium ore conveyor, an electric heating kiln, a scraper conveyor, a lock valve, a gas kiln, a combustion device, a grate cooler and a roasting material conveying device which are connected in sequence.

[0007] The suspension preheating device includes a primary cyclone preheater and a secondary cyclone preheater; the primary cyclone preheater includes a primary cyclone, a drying tube and a primary discharge pipe, and the secondary cyclone preheater includes a secondary cyclone, a heat exchange tube and a secondary discharge pipe; wherein a primary cyclone smoke outlet is arranged at the top of the primary cyclone, a primary cyclone smoke inlet is arranged on the side wall of the primary cyclone, and a primary discharge pipe is arranged at the bottom of the primary cyclone. A secondary cyclone smoke outlet is arranged at the top of the secondary cyclone, a secondary cyclone smoke inlet is arranged on the side wall of the secondary cyclone, and a secondary discharge pipe is arranged at the bottom of the secondary cyclone.

[0008] A drying pipe is arranged between the smoke inlet of the first cyclone and the smoke outlet of the second cyclone, one end of which is connected to the smoke inlet of the first cyclone and the other end is connected to the smoke outlet of the second cyclone. A heat exchange pipe is arranged between the smoke inlet of the second cyclone and the tail of the gas kiln, one end of which is connected to the smoke inlet of the second cyclone and the other end is connected to the tail of the gas kiln; the discharge port of the first feeding pipe is arranged above the lithium ore conveyor, and the discharge port of the second feeding pipe is connected to the tail of the gas kiln.

[0009] A silo discharger is set at the bottom of the silo to ensure uniform feeding of sticky and wet lithium ore. The metering device is set below the silo discharger, and the unloading position of the metering device is set above the feeding port of the drying tube. When the system is working, the lithium ore is discharged from the silo discharger at the bottom of the silo, weighed and transported by the metering device, and enters the primary cyclone preheater through the drying tube; the lithium ore is blown away by the hot flue gas from the secondary cyclone preheater in the drying tube, suspended in the gas, dried and preheated, and brought into the primary cyclone for gas-solid separation; the gas in the flue gas is discharged along the flue gas outlet of the primary cyclone, and the lithium ore enters the lithium ore conveyor from the primary unloading pipe; the temperature of the lithium ore after drying and preheating is about 200℃, and the water content is not more than 1%.

[0010] Furthermore, the metering device of the roasting kiln system is preferably a belt scale.

[0011] The discharge end of the lithium ore conveyor is connected to the kiln tail of the electric heating kiln through a pipeline; the heating temperature range of the electric heating kiln is controlled at 700-800℃; the lithium ore between the electric heating kiln and the gas kiln is transported by a scraper conveyor; the air lock valve is set at the discharge port of the scraper conveyor, and the gas in the electric heating kiln and the gas in the gas kiln are isolated from each other. The lithium ore that has completed drying and preheating is transported to the electric heating kiln by the lithium ore conveyor, heated to 650-750℃ by the electric heating kiln, and transported to the gas kiln by the scraper conveyor. The air lock valve ensures that the material can be transported from the electric heating kiln to the gas kiln, and effectively isolates the hot flue gas in the electric heating kiln and the gas kiln, preventing the high-temperature flue gas of the gas kiln from entering the electric heating kiln and affecting the stable temperature field of the electric heating kiln. The stable temperature field is helpful for the temperature control of the electric heating kiln.

[0012] The combustion device includes a burner and an external fan. The burner is inserted from the kiln head of the gas kiln. The gas kiln includes a feeding section, a firing section and a cooling section arranged in sequence. The temperature of the firing section is controlled at 1100-1200°C. The combustion device continuously supplies heat to the gas kiln. The lithium ore enters the gas kiln and is pushed from the feeding section to the firing section. At a heating temperature of 1100-1200°C, roasted material is generated. The temperature of the roasted material out of the kiln is controlled at about 1000°C. The hot flue gas generated by the gas kiln enters the suspension preheating device along the heat exchange tube to dry and preheat the subsequent lithium ore.

[0013] The grate cooler feed port is set below the gas kiln head discharge port, and the roasted material conveying device is set below the grate cooler discharge port. The high-temperature roasted material enters the grate cooler and is cooled to 100°C, and is sent to the next process through the roasted material conveying device.

[0014] Furthermore, the roasting kiln system of the present invention also includes an exhaust gas treatment device, which includes a high-temperature bag dust collector, an external exhaust fan and a chimney connected in sequence; the air inlet of the high-temperature bag dust collector is connected to the flue gas outlet of the first-stage cyclone through a pipeline, the air outlet is connected to the external exhaust fan, and the ash discharge port is connected to the feed port of the lithium ore conveyor. The flue gas discharged from the flue gas outlet of the first-stage cyclone enters the high-temperature bag dust collector for dust removal, and the smoke is discharged from the ash discharge port into the lithium ore conveyor. The dust-removed smoke is blown into the chimney by the external exhaust fan and discharged to the outside of the system.

[0015] The residual air of the traditional grate cooler is directly discharged into the dust collector, and the heat of the residual air is not effectively utilized. Therefore, the grate cooler of the roasting kiln system of the present invention further includes a residual heat recovery device. A residual heat air duct is provided at the tail of the grate cooler. One end of the residual heat recovery device is connected to the residual heat air duct, and the other end is connected to the secondary cyclone preheater. The high-temperature residual air generated by the grate cooler enters the heat exchange tube from the residual heat air duct along the residual heat recovery device, providing a heat source for the suspension preheating device, thereby realizing the recovery and utilization of the heat of the high-temperature residual air generated by the grate cooler to cool the high-temperature roasted material.

[0016] Furthermore, the waste heat recovery device is a cyclone dust collector; the cyclone dust collector is provided with a hot gas outlet, a hot gas inlet and a smoke outlet; the hot gas inlet is connected to the waste heat air duct, the hot gas outlet is connected to the heat exchange pipe, and the smoke outlet is arranged above the roasting material conveying device; a waste heat fan is also arranged between the cyclone dust collector and the heat exchange pipe, and the waste heat fan can provide power for the waste air of the grate cooler. The high-temperature waste air generated by the grate cooler cooling the high-temperature roasting material enters the cyclone dust collector from the waste heat air duct for dust removal, and the smoke is discharged to the next process through the roasting material conveying device; the high-temperature waste air after dust removal is blown into the secondary cyclone preheater through the waste heat fan, mixed with the high-temperature flue gas generated by the gas kiln, and provides a heat source for the suspension preheating device.

[0017] Furthermore, an exhaust valve is provided at the kiln head of the electric heating kiln, and the exhaust valve is connected to the air inlet of the high-temperature bag dust collector through a pipeline. The heating of spodumene in the electric heating kiln itself does not produce a large amount of flue gas. The gas produced in the electric heating kiln is mainly a small amount of water vapor, so it will not cause a strong change in the air pressure of the electric heating kiln. The exhaust valve is opened or closed regularly according to the air pressure in the electric heating kiln to keep the air pressure in the kiln stable, which can ensure the stable operation of the electric heating kiln.

[0018] Furthermore, the drying tube of the present invention adopts a "vertical tube + inverted U-shaped tube" structure. When the cyclone smoke inlet height is the same, compared with the traditional "vertical tube + horizontal short tube" structure, the "vertical tube + inverted U-shaped tube" structure can make the material stay longer, thereby improving the material preheating and drying effect.

[0019] Furthermore, after the hot flue gas generated from the gas kiln enters the suspended preheating device along the heat exchange pipe, the secondary cyclone separates the flue gas into gas and solids. After the gas-solid separation, the solids in the flue gas will enter the gas kiln again along the secondary discharge pipe. Since the solids are already roasted lithium ore, the above operation avoids the energy consumption in the suspended preheating device and the electric heating kiln during recirculation, thereby reducing the heat loss in the system.

[0020] Furthermore, the heating components of the electric heating kiln include an electromagnetic coil, a power supply and a control system. The electromagnetic coil is spirally wound on the outside of the kiln body, and the two ends form a closed loop with the power supply. The control system controls the current size, thereby controlling the heating temperature change of the electric heating kiln.

[0021] Furthermore, the drying tube of this system can be replaced by a flash dryer. The flue gas outlet of the flash dryer is connected to the flue gas inlet of the first-stage cyclone, and the flue gas inlet of the flash dryer is connected to the flue gas outlet of the second-stage cyclone; the unloading position of the metering device is set above the feeding port of the flash dryer. When the system is working, the lithium ore is discharged from the silo discharger at the bottom of the silo, weighed and transported by the metering device, and enters the first-stage cyclone preheater through the flash dryer; the lithium ore is dried by the hot flue gas from the second-stage cyclone preheater in the flash dryer, and is brought into the first-stage cyclone for gas-solid separation; the gas in the flue gas is discharged along the flue gas outlet of the first-stage cyclone, and the lithium ore enters the lithium ore conveyor through the first-stage unloading pipe; the temperature of the lithium ore after drying and preheating is about 200°C, and the water content is not more than 1%.

[0022] An electric, gas and suspension three-composite lithium ore roasting process comprises the following steps: Step S1. Suspended preheating device uniform drying preheating: Lithium ore is put into the suspension preheating device from the silo, and is dried and preheated by the hot flue gas from the gas kiln and the grate cooler in the suspension preheating device, so that the temperature of spodumene rises to 200°C and the water content is not more than 1%. This process is mainly carried out in the inverted U-shaped tube part of the drying tube. Compared with the vertical tube and the horizontal tube, the flow speed of lithium ore and hot flue gas is relatively stable, forming a uniform drying and preheating.

[0023] Step S2. Primary calcination in an electric heating kiln: The dried and preheated spodumene is sent to the electric heating kiln for roasting through a lithium ore conveyor. The heating temperature is controlled at 700-800°C, so that the spodumene outlet temperature reaches 650-750°C.

[0024] Step S3. Secondary calcination in a gas kiln: The spodumene heated by the electric heating kiln is sent to the gas kiln via a scraper conveyor for further transformation and roasting. The heating temperature is controlled at 1100-1200°C. The spodumene is transformed from α type to β type to generate roasted material. The roasted material exits the kiln at a temperature of 1000°C. The hot flue gas generated by the gas kiln enters the suspension preheating device along the heat exchange tube to dry and preheat the subsequent spodumene.

[0025] Step S4. roasting material cooling: After the high-temperature roasted material leaves the kiln, it enters the grate cooler for cooling. The roasted material temperature drops to 100°C and is sent to the next process through the roasted material conveying device.

[0026] Furthermore, the specific process of preheating by the suspension preheating device in step S1 is as follows: Lithium ore is discharged from the silo unloader at the bottom of the silo, weighed and transported by a metering device, and enters the primary cyclone preheater through a drying tube; the lithium ore is blown away by the hot flue gas from the secondary cyclone preheater in the drying tube, suspended in the gas, dried and preheated, and brought into the primary cyclone for gas-solid separation; the gas in the flue gas is discharged along the flue gas outlet of the primary cyclone, and the lithium ore enters the lithium ore conveyor through the primary discharge pipe; the temperature of the lithium ore after drying and preheating is about 200°C, and the water content is not more than 1%.

[0027] Furthermore, the roasting process of the present invention further comprises: step S5. tail gas treatment: In step S1, the flue gas discharged from the flue gas outlet of the primary cyclone enters the high-temperature bag dust collector for dust removal, and the smoke is discharged into the lithium ore conveyor from the ash discharge port. The smoke after dust removal is blown into the chimney by the external exhaust fan and discharged outside the system.

[0028] Furthermore, the roasting process of the present invention further comprises: Step S6. Waste heat recovery: The high-temperature residual air generated by the grate cooler cooling the high-temperature roasted material enters the cyclone dust collector through the residual heat air duct for dust removal. The smoke and dust solids are discharged and then sent to the next process through the roasted material conveying device. The high-temperature residual air after dust removal is blown into the secondary The cyclone preheater mixes with the high-temperature flue gas produced by the gas kiln to provide heat source for the suspension preheating device, and the residual gas produced by the grate cooler Heat is used efficiently.

[0029] Furthermore, the electric heating kiln primary roasting in step S2 further includes the following operations: The exhaust valve at the kiln head of the electric heating kiln opens or closes regularly according to the air pressure in the electric heating kiln to keep the air pressure in the kiln stable. The exhaust gas is treated with dust removal by the exhaust gas treatment device.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The roasting kiln system and process disclosed in the present invention realizes the conversion of spodumene from α type to β type by uniform drying and preheating with a suspended preheating device, primary roasting in an electric heating kiln, and secondary roasting in a gas kiln. Compared with the traditional transformation roasting of spodumene in a rotary kiln fueled by natural gas, the present invention has raised the temperature of spodumene to 650-750°C by preheating with a suspended preheating device and primary roasting in an electric heating kiln. Only the post-heating work needs to be completed in the gas kiln, which can save a lot of natural gas resources and reduce carbon dioxide emissions at the same time, in line with the national "carbon neutrality" policy, and is very suitable for use in areas with a lack of natural gas but abundant electricity reserves or cheap electricity prices and high environmental protection requirements. In addition, the electric heating kiln can use green electricity generated by solar energy and wind power, further reducing carbon emissions during the power generation process.

[0031] (2) Compared with the prior art that can only use electric heating kilns in the acidification roasting stage of spodumene pyrometallurgy, the present invention innovatively uses the electric heating kiln as an intermediate heating process in the transition roasting process, indirectly solving the problem that the existing electric heating kiln barrel material cannot continuously withstand high-temperature roasting at 1100°C, and fully utilizing the advantages of the electric heating kiln, such as uniform heat transfer, stable temperature field, and easy temperature control, thereby improving the system working efficiency.

[0032] (3) The conventional single rotary kiln solution requires a longer kiln body. If the waste heat generated by the grate cooler is to be transferred to the preheating device, it needs to pass through the length of the grate cooler and the rotary kiln, and a lot of heat will be lost. Generally, an external boiler is used to recover the waste heat, but this method is not conducive to the internal circulation of system heat. The present invention uses a combined kiln solution of "electric heating kiln + gas kiln", which effectively reduces the length of a single kiln body. Since the length of the gas kiln is shorter, the distance that the hot air generated at the tail of the grate cooler passes through the grate cooler and the gas kiln becomes shorter, and the heat loss is less. Therefore, the present invention connects the waste heat air duct of the grate cooler with the preheating device, so that the heat can be fully circulated inside the system, thereby improving the thermal efficiency of the system.

[0033] (4) The present invention provides an air lock valve between the electric heating kiln and the gas kiln, so that the smoke generated by the gas kiln cannot enter the electric heating kiln. The gas in the electric heating kiln and the gas kiln are isolated from each other. The heating of the lithium ore in the electric heating kiln itself does not generate a large amount of flowing smoke. A relatively uniform heating is formed in the electric heating kiln, which ensures the stability of the temperature field of the electric heating kiln and facilitates the control of the temperature in the kiln.

[0034] (5) The suspension preheating device of the present invention is provided with a secondary cyclone. When the hot flue gas generated from the gas kiln and the high-temperature residual wind of the grate cooler enter the suspension preheating device along the heat exchange pipe, the secondary cyclone separates the mixed flue gas into gas and solid. After the gas-solid separation, the solid in the flue gas will enter the gas kiln again along the secondary discharge pipe. Since the solid is already spodumene that has undergone transformation roasting, the above operation avoids the energy consumption by recirculating it in the preheating device and the electric heating kiln, thereby reducing the heat loss in the system.

[0035] (6) The drying tube of the present invention adopts a "vertical tube + inverted U-shaped tube" structure. When the height of the cyclone smoke inlet is the same, compared with the traditional "vertical tube + horizontal short tube" structure, the drying tube structure of the present invention has a longer material residence time and a more stable smoke flow rate, thereby improving the material preheating and drying effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of the roasting kiln system of the present invention; Figure 2 It is a structural schematic diagram of the suspension preheating device of the present invention; Figure 3It is a structural schematic diagram of the gas kiln of the present invention; Figure 4 A comparison diagram of the drying tube structure of the present invention and a conventional structure; Figure 5 This is the flow direction diagram of the high-temperature flue gas generated by the gas kiln.

[0037] Among them: 1. Silo; 1-1. Silo unloader; 2. Metering device; 3. Suspension preheating device; 31-1. First-stage cyclone; 31-11. First-stage cyclone smoke outlet; 31-12. First-stage cyclone smoke inlet; 31-13. First-stage discharge pipe; 31-2. Drying pipe; 32-1. Second-stage cyclone; 32-11. Second-stage cyclone smoke outlet; 32-12. Second-stage cyclone smoke inlet; 32-13. Second-stage discharge pipe; 32-2. Heat exchange pipe; 4-1. Waste heat fan; 4-2. Cyclone dust collector; 4- 21. Hot air outlet; 4-22. Hot air inlet; 4-23. Smoke and dust outlet; 5. Combustion device; 6. Grate cooler; 6-1. Waste heat air duct; 7. Roasting material conveying device; 8. Gas kiln; 8-1. Feeding section; 8-2. Firing section; 8-3. Cooling section; 91. Air lock valve; 10. Electric heating kiln; 10-1. Exhaust valve; 11. Lithium ore conveyor; 12-1. High-temperature bag dust collector; 12-11. Air inlet; 12-12. Air outlet; 12-13. Ash discharge port; 12-2. External exhaust fan; 12-3. Chimney. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings. The following is a preferred embodiment of the present invention, which is intended to provide a basic understanding of the present invention, but is not intended to confirm the key or decisive elements of the present invention or to limit the scope of protection.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the implementation manner of the present invention is not limited thereto.

[0041] Embodiment 1: See attached Figure 1-3The present embodiment discloses an electric, gas, and suspension three-composite lithium ore roasting kiln system, which includes a silo 1, a metering device 2, a suspension preheating device 3, a lithium ore conveyor 11, an electric heating kiln 10, a scraper conveyor, a wind lock valve 91, a gas kiln 8, a combustion device 5, a grate cooler 6, and a roasting material conveying device 7 connected in sequence.

[0042] The suspension preheating device 3 includes a primary cyclone preheater and a secondary cyclone preheater. The primary cyclone preheater includes a primary cyclone barrel 31-1, a drying tube 31-2 and a primary discharge pipe 31-13. The secondary cyclone preheater includes a secondary cyclone barrel 32-1, a heat exchange tube 32-2 and a secondary discharge pipe 32-13. A primary cyclone barrel smoke outlet 31-11 is arranged at the top of the primary cyclone barrel 31-1, a primary cyclone barrel smoke inlet 31-12 is arranged on the side wall of the primary cyclone barrel 31-1, and the primary discharge pipe 31-13 is arranged at the bottom of the primary cyclone barrel 31-1. A secondary cyclone barrel smoke outlet 32-11 is arranged at the top of the secondary cyclone barrel 32-1, a secondary cyclone barrel smoke inlet 32-12 is arranged on the side wall of the secondary cyclone barrel 32-1, and the secondary discharge pipe 32-13 is arranged at the bottom of the secondary cyclone barrel 32-1.

[0043] One end of the drying pipe 31-2 is connected to the first-level cyclone smoke inlet 31-12, and the other end is connected to the second-level cyclone smoke outlet 32-11; one end of the heat exchange pipe 32-2 is connected to the second-level cyclone smoke inlet 32-12, and the other end is connected to the tail of the gas kiln 8; the discharge port of the first-level feed pipe 31-13 is arranged above the lithium ore conveyor 11, and the discharge port of the second-level feed pipe 32-13 is connected to the tail of the gas kiln 8.

[0044] A silo discharger 1-1 is provided at the bottom of the silo 1 to ensure uniform feeding of the wet lithium ore. The metering device 2 is provided below the silo discharger 1-1, and the unloading position of the metering device 2 is provided above the feeding port of the drying pipe 31-2. When the system is working, spodumene is discharged from the silo discharger 1-1 at the bottom of the silo 1, weighed and transported by the metering device 2, and enters the primary cyclone preheater through the drying pipe 31-2; the spodumene is blown away by the hot flue gas from the secondary cyclone preheater in the drying pipe 31-2, suspended in the gas, dried and preheated, and brought into the primary cyclone 31-1 for gas-solid separation; the gas in the flue gas is discharged along the flue gas outlet 31-11 of the primary cyclone, and the spodumene enters the lithium ore conveyor 11 through the primary unloading pipe 31-13; the temperature of the spodumene after drying and preheating is about 200°C, and the water content is not more than 1%.

[0045] Furthermore, the metering device 2 of the roasting kiln system is preferably an electronic belt scale.

[0046] The discharge end of the lithium ore conveyor 11 is connected to the kiln tail of the electric heating kiln 10 through a pipeline; the heating temperature range of the electric heating kiln 10 is controlled at 700-800°C; the spodumene is transported between the electric heating kiln 10 and the gas kiln 8 through a scraper conveyor; the air lock valve 91 is set at the unloading port of the scraper conveyor, and the gas in the electric heating kiln 10 and the gas in the gas kiln 8 are isolated from each other. The spodumene that has completed drying and preheating is transported to the electric heating kiln 10 by the lithium ore conveyor 11, heated to 650-750°C by the electric heating kiln 10, and transported to the gas kiln 8 through the scraper conveyor. The air lock valve 91 is set to ensure that the material can be transported from the electric heating kiln 10 to the gas kiln 8, and the hot flue gas in the electric heating kiln 10 and the gas kiln 8 are effectively isolated, preventing the high-temperature flue gas of the gas kiln 8 from entering the electric heating kiln 10 to affect the stable temperature field of the electric heating kiln 10. The stable temperature field is conducive to the temperature control of the electric heating kiln 10.

[0047] The combustion device 5 includes a burner and an external fan. The burner is inserted into the cylinder of the gas kiln 8 from the kiln head of the gas kiln; the gas kiln 8 includes a feeding section 8-1, a firing section 8-2 and a cooling section 8-3 arranged in sequence, and the temperature of the firing section 8-2 is controlled at 1100-1200°C. The combustion device 5 continuously supplies heat to the gas kiln 8, and spodumene enters the gas kiln 8 and is pushed from the feeding section 8-1 to the firing section 8-2. At a heating temperature of 1100-1200°C, spodumene is converted from α type to β type to generate roasted material, and the temperature of the roasted material out of the kiln is controlled at about 1000°C. The hot flue gas generated by the gas kiln 8 enters the suspension preheating device 3 along the heat exchange pipe 32-2 to dry and preheat the subsequent spodumene.

[0048] The feed port of the grate cooler 6 is arranged below the discharge port of the kiln head of the gas kiln 8, and the roasting material conveying device 7 is arranged below the discharge port of the grate cooler 6. The high-temperature roasting material enters the grate cooler 6 and is cooled to 100°C, and is sent to the next process through the roasting material conveying device 7.

[0049] More specifically, the roasting kiln system of this embodiment also includes an exhaust gas treatment device, which includes a high-temperature bag dust collector 12-1, an external exhaust fan 12-2 and a chimney 12-3 connected in sequence; the air inlet 12-11 of the high-temperature bag dust collector 12-1 is connected to the primary cyclone flue gas outlet 31-11 through a pipeline, the air outlet 12-12 is connected to the external exhaust fan 12-2, and the ash discharge port 12-13 is connected to the inlet of the lithium ore conveyor 11. The flue gas discharged from the primary cyclone flue gas outlet 31-11 enters the high-temperature bag dust collector 12-1 for dust removal, and the smoke is discharged from the ash discharge port 12-13 into the lithium ore conveyor 11. The dust-removed flue gas is blown into the chimney 12-3 by the external exhaust fan 12-2 and discharged to the outside of the system.

[0050] The residual air of the traditional grate cooler is directly discharged into the dust collector, and the heat of the residual air is not effectively utilized. Therefore, the grate cooler 6 of the roasting kiln system of this embodiment further includes a residual heat recovery device. A residual heat air duct 6-1 is provided at the tail of the grate cooler 6. One end of the residual heat recovery device is connected to the residual heat air duct 6-1, and the other end is connected to the secondary cyclone preheater. The high-temperature residual air generated by the grate cooler 6 enters the heat exchange pipe 32-2 from the residual heat air duct 6-1 along the residual heat recovery device, providing a heat source for the suspension preheating device 3, and realizing the recovery and utilization of the heat of the high-temperature residual air generated by the grate cooler 6 to cool the high-temperature roasted material.

[0051] More specifically, the waste heat recovery device is a cyclone dust collector 4-2; the cyclone dust collector 4-2 is provided with a hot gas outlet 4-21, a hot gas inlet 4-22 and a smoke outlet 4-23; the hot gas inlet 4-22 is connected to the waste heat air duct 6-1, the hot gas outlet 4-21 is connected to the heat exchange tube 32-2, and the smoke outlet 4-23 is arranged above the roasting material conveying device 7; a waste heat blower 4-1 is also arranged between the cyclone dust collector 4-2 and the heat exchange tube 32-2, and the waste heat blower 4-1 can provide power for the waste air of the grate cooler 6. The high-temperature residual air generated by the grate cooler 6 cooling the high-temperature roasting material enters the cyclone dust collector 4-2 from the waste heat air duct 6-1 for dust removal. After the smoke and dust are discharged, they are sent to the next process via the roasting material conveying device 7; the high-temperature residual air after dust removal is blown into the secondary cyclone preheater via the waste heat blower 4-1, mixed with the high-temperature flue gas generated by the gas kiln 8, and provides a heat source for the suspension preheating device 3.

[0052] More specifically, an exhaust valve 10-1 is provided at the kiln head of the electric heating kiln 10, and the exhaust valve 10-1 is connected to the air inlet 12-11 of the high-temperature bag dust collector 12-1 through a pipeline. The heating of spodumene in the electric heating kiln 10 itself does not generate a large amount of flue gas, and the gas generated is mainly a small amount of water vapor, so the air pressure of the electric heating kiln 10 will not change drastically. The exhaust valve 10-1 is regularly opened or closed according to the air pressure in the electric heating kiln 10 to keep the air pressure in the kiln stable, thereby ensuring the stable operation of the electric heating kiln 10.

[0053] More specifically, see Appendix Figure 5 In this embodiment, the drying tube 31-2 adopts a "vertical tube + inverted U-shaped tube" structure. When the cyclone smoke inlet height is the same, compared with the traditional "vertical tube + horizontal short tube" structure, the "vertical tube + inverted U-shaped tube" structure can make the material stay longer, thereby improving the material preheating and drying effect.

[0054] More specifically, after the hot flue gas generated from the gas kiln 8 enters the suspension preheating device 3 along the heat exchange pipe 32-2, the secondary cyclone 32-1 performs gas-solid separation on the flue gas, and the solid in the flue gas will enter the gas kiln 8 again along the secondary discharge pipe 32-13 after gas-solid separation. Since the solid is already spodumene that has undergone transformation roasting, the above operation avoids the energy consumption in the suspension preheating device 3 and the electric heating kiln 10 during recirculation, thereby reducing the heat loss in the system.

[0055] More specifically, the electric heating kiln 10 includes an electromagnetic coil, a power supply and a control system. The electromagnetic coil is spirally wound outside the kiln body, and both ends form a closed loop with the power supply. The control system controls the current size, thereby controlling the heating temperature change of the electric heating kiln.

[0056] More specifically, the drying tube 31-2 of this embodiment can be replaced by a flash dryer. The smoke outlet of the flash dryer is connected to the smoke inlet 31-12 of the first-stage cyclone, and the smoke inlet of the flash dryer is connected to the smoke outlet 32-11 of the second-stage cyclone; the unloading position of the metering device 2 is set above the feeding port of the flash dryer. When the system is working, spodumene is discharged from the unloading silo feeder 1-1 at the bottom of the silo 1, weighed and transported by the metering device 2, and enters the first-stage cyclone preheater through the flash dryer; spodumene is dried by the hot flue gas from the second-stage cyclone preheater in the flash dryer, and is brought into the first-stage cyclone 31-1 for gas-solid separation; the gas in the flue gas is discharged along the smoke outlet 31-11 of the first-stage cyclone, and spodumene enters the lithium ore conveyor 11 through the first-stage unloading pipe 31-13; the temperature of the lithium ore after drying and preheating is about 200°C, and the water content is not more than 1%.

[0057] Embodiment 2: This embodiment provides a three-composite lithium ore roasting process of electricity, gas and suspension, see the attached Figure 4 , including the following steps: Step S1. Suspended preheating device uniform drying preheating: Spodumene is put into the suspension preheating device 3 from the silo, and is preheated and dried by the hot flue gas from the gas kiln 8 and the grate cooler 6 in the suspension preheating device 3, so that the temperature of the spodumene is preheated to 200°C and the water content is not more than 1%; this process is mainly carried out in the inverted U-shaped tube part of the drying tube 31-2, and the flow speed of the spodumene and the hot flue gas is relatively stable compared with the vertical tube and the horizontal short tube.

[0058] Step S2. Primary calcination in an electric heating kiln: The dried and preheated spodumene is sent to the electric heating kiln 10 for roasting through the lithium ore conveyor 11, and the heating temperature is controlled at 700-800°C, so that the spodumene kiln temperature reaches 650-750°C; Step S3. Secondary calcination in a gas kiln The spodumene heated by the electric heating kiln 10 is transported to the gas kiln 8 through the scraper conveyor 11 for further transformation roasting. The heating temperature is controlled at 1100-1200°C. The spodumene is transformed from α-type to β-type to generate roasted material. The roasted material outlet temperature is 1000°C. The hot flue gas generated by the gas kiln 8 enters the suspension preheating device 3 along the heat exchange pipe 32-2 to dry and preheat the subsequent spodumene. Step S4. roasting material cooling: After the high-temperature roasted material is discharged from the kiln, it enters the grate cooler 6 for cooling treatment, the roasted material is reduced to 100° C., and is sent to the next process through the roasted material conveying device 7.

[0059] More specifically, the specific process of drying and preheating by the suspension preheating device in step S1 is as follows: Spodumene is discharged from the silo discharger 1-1 at the bottom of the silo 1, weighed and transported by the metering device 2, and enters the primary cyclone preheater through the drying pipe 31-2; the spodumene is blown away by the hot flue gas from the secondary cyclone preheater in the drying pipe 31-2, suspended in the gas, dried and preheated, and brought into the primary cyclone 31-1 for gas-solid separation; the gas in the flue gas is discharged along the primary cyclone flue gas outlet 31-11, and the spodumene is entered into the lithium ore conveyor 11 through the primary discharge pipe 31-13; the temperature of the lithium ore after drying and preheating is about 200°C, and the water content is not more than 1%.

[0060] More specifically, the roasting process of this embodiment further includes: Step S5. Tail gas treatment: In step S1, the flue gas discharged from the primary cyclone flue gas outlet 31-11 enters the high-temperature bag dust collector 12-1 for dust removal, and the smoke is discharged into the lithium ore conveyor 11 through the ash discharge port 12-13. The dust-removed flue gas is blown into the chimney by the external exhaust fan 12-2 and discharged outside the system.

[0061] More specifically, the roasting process of this embodiment further includes: Step S6. Waste heat recovery: The high-temperature residual air generated by the grate cooler 6 cooling the high-temperature roasting material enters the cyclone dust collector 4-2 from the waste heat air duct 6-1 for dust removal. After the smoke and dust solids are discharged, they are sent to the next process via the roasting material conveying device 7; the high-temperature residual air after dust removal is blown into the secondary cyclone preheater through the waste heat blower 4-1, mixed with the high-temperature flue gas generated by the gas kiln 8, and provides a heat source for the suspension preheating device 3, and the waste heat generated by the grate cooler 6 is effectively utilized.

[0062] More specifically, step S2 of the electric heating kiln primary roasting also includes the following operations: The exhaust valve 10-1 at the kiln head of the electric heating kiln 10 is opened or closed regularly according to the air pressure in the electric heating kiln 10 to keep the air pressure in the kiln stable; the exhaust flue gas is dust-removed by the tail gas treatment device.

[0063] The roasting kiln system in Example 1 can be used to implement the roasting process of this example.

[0064] In this article, the directional words such as front, back, top, and bottom involved are defined by the positions of the parts in the drawings and the positions of the parts relative to each other, just for the sake of clarity and convenience in expressing the technical solution. It should be understood that they are relative concepts and can change accordingly according to different ways of use and placement. The use of the directional words should not limit The scope of protection requested by this application.

[0065] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electric, gas and suspension composite lithium ore roasting kiln system, characterized in that: It comprises a silo (1), a metering device (2), a suspension preheating device (3), a lithium ore conveyor (11), an electric heating kiln (10), a scraper conveyor, an air lock valve (91), a gas kiln (8), a combustion device (5), a grate cooler (6), and a roasting material conveying device (7) which are connected in sequence; The suspension preheating device (3) comprises a primary cyclone preheater and a secondary cyclone preheater. The invention comprises a primary cyclone (31-1), a drying tube (31-2) and a primary discharge pipe (31-13); the secondary cyclone preheater comprises a secondary cyclone (32-1), a heat exchange tube (32-2) and a secondary discharge pipe (32-13); the top of the primary cyclone (31-1) is provided with a primary cyclone smoke outlet (31-11); the side wall of the primary cyclone (31-1) is provided with a primary cyclone smoke inlet (31-12); the primary discharge pipe (31-13) is provided at the bottom of the primary cyclone (31-1); the top of the secondary cyclone (32-1) is provided with a secondary cyclone smoke outlet (32-11); the secondary A secondary cyclone smoke inlet (32-12) is arranged on the side wall of the cyclone (32-1), and the secondary discharge pipe (32-13) is arranged at the bottom of the secondary cyclone (32-1); one end of the drying pipe (31-2) is connected to the primary cyclone smoke inlet (31-12), and the other end is connected to the secondary cyclone smoke outlet (32-11); one end of the heat exchange pipe (32-2) is connected to the secondary cyclone smoke inlet (32-12), and the other end is connected to the kiln tail of the gas kiln (8); the discharge port of the primary discharge pipe (31-13) is arranged above the lithium ore conveyor (11), and the discharge port of the secondary discharge pipe (32-13) is connected to the kiln tail of the gas kiln (8); The bottom of the silo (1) is provided with a silo discharger (1-1), a metering device (2) is provided below the silo discharger (1-1), and a discharge position of the metering device (2) is provided above the feed inlet of the drying tube (31-2); the discharge end of the lithium ore conveyor (11) is connected to the kiln tail of the electric heating kiln (10) through a pipeline; the heating temperature range of the electric heating kiln (10) is controlled within a range of 700 to 800° C. The lithium ore is transported between the electric heating kiln (10) and the gas kiln (8) through a scraper conveyor; and a wind lock valve (91) is provided at the discharge port of the scraper conveyor, so that the gas in the electric heating kiln (10) and the gas kiln (8) are isolated from each other; The combustion device (5) comprises a burner and an external fan, and the burner is inserted into the gas kiln cylinder from the kiln head of the gas kiln; the gas kiln (8) comprises a feeding section (8-1), a firing section (8-2) and a cooling section (8-3) which are arranged in sequence, and the temperature of the firing section (8-2) is controlled at 1100-1200°C; the feeding port of the grate cooler (6) is arranged below the discharge port of the kiln head of the gas kiln (8), and the roasting material conveying device (7) is arranged below the discharge port of the grate cooler (6).

2. The electric, gas and suspension three-composite lithium ore roasting kiln system according to claim 1 is characterized in that: The lithium ore roasting kiln system also includes an exhaust gas treatment device, which includes a high-temperature bag dust collector (12-1), an external exhaust fan (12-2) and a chimney (12-3) connected in sequence; the air inlet (12-11) of the high-temperature bag dust collector (12-1) is connected to the primary cyclone flue gas outlet (31-11) through a pipeline, the air outlet (12-12) is connected to the external exhaust fan (12-2), and the ash discharge port (12-13) is connected to the feed port of the lithium ore conveyor (11).

3. The electric, gas and suspension three-composite lithium ore roasting kiln system according to claim 1 is characterized in that: The grate cooler (6) further comprises a waste heat recovery device. A waste heat air duct (6-1) is arranged at the rear of the grate cooler (6). One end of the waste heat recovery device is connected to the waste heat air duct (6-1), and the other end is connected to the secondary cyclone preheater.

4. The electric, gas and suspension three-composite lithium ore roasting kiln system according to claim 3 is characterized in that: The waste heat recovery device comprises a cyclone dust collector (4-2); the cyclone dust collector (4-2) is provided with a hot air outlet (4-21), a hot air inlet (4-22) and a smoke outlet (4-23); the hot air inlet (4-22) is connected to the waste heat air duct (6-1), the hot air outlet (4-21) is connected to the heat exchange pipe (32-2), and the smoke outlet (4-23) is arranged above the roasting material conveying device (7).

5. The electric, gas and suspension composite lithium ore roasting kiln system according to any one of claims 2 to 4, characterized in that: An exhaust valve (10-1) is provided at the kiln head of the electric heating kiln (10), and the exhaust valve (10-1) is connected to an air inlet (12-11) of a high-temperature bag dust collector (12-1) through a pipeline.

6. The electric, gas and suspension three-composite lithium ore roasting kiln system according to claim 1 is characterized in that: The drying tube (31-2) comprises a vertical tube and an inverted U-shaped tube, the top end of the vertical tube is connected to one end of the inverted U-shaped tube, and the other end of the inverted U-shaped tube is connected to the primary cyclone (31-1).

7. An electric, gas, and suspension three-composite lithium ore roasting process, which is realized based on the electric, gas, and suspension three-composite lithium ore roasting kiln system according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1. Suspended preheating device uniform drying preheating: The spodumene is fed from the silo (1) into the suspension preheating device (3), and is preheated and dried in the suspension preheating device (3) by hot flue gas from the gas kiln (8) and the grate cooler (6), so that the temperature of the spodumene is preheated to 200° C. and the water content is not more than 1%; Step S2. Primary calcination in an electric heating kiln: The dried and preheated spodumene is sent to an electric heating kiln (10) for roasting via a lithium ore conveyor (11). The heating temperature is controlled at 700 to 800° C., so that the temperature of the spodumene out of the kiln reaches 650 to 750° C.; Step S3. Secondary calcination in a gas kiln: The spodumene heated by the electric heating kiln (10) is transported to the gas kiln (8) via the lithium ore conveyor (11) for secondary transformation roasting. The heating temperature is controlled at 1100-1200°C, so that the spodumene is transformed from α-type to β-type to generate roasted material. The temperature of the roasted material out of the kiln is 1000°C. The hot flue gas generated by the gas kiln (8) enters the suspension preheating device (3) along the heat exchange pipe (32-2) to dry and preheat the subsequent spodumene. Step S4. roasting material cooling: After the roasted material is discharged from the kiln, it is transported to a grate cooler (6) for cooling so that the temperature of the roasted material is reduced to 100° C., and then it is transported to the next process through a roasted material transport device (7).

8. The electric, gas and suspension three-composite lithium ore roasting process according to claim 7 is characterized in that: The step S5 also includes tail gas treatment: In step S1, the flue gas discharged from the flue gas outlet (31-11) of the primary cyclone enters the high-temperature bag dust collector (12-1) for dust removal, and the smoke is discharged from the ash discharge port (12-13) into the lithium ore conveyor (11). The smoke after dust removal is blown into the chimney by the external exhaust fan (12-2) and discharged outside the system.

9. The electric, gas and suspension three-composite lithium ore roasting process according to claim 7 is characterized in that: The step S6 also includes waste heat recovery: The high-temperature residual air generated by the grate cooler (6) cooling the high-temperature roasted material enters the cyclone dust collector (4-2) through the residual heat air duct (6-1) for dust removal, and the smoke and dust solids are discharged and sent to the next process through the roasted material conveying device (7); the high-temperature residual air after dust removal is blown into the secondary cyclone preheater through the residual heat blower (4-1), mixed with the high-temperature flue gas generated by the gas kiln, and provides a heat source for the suspension preheating device (3), so that the residual heat generated by the grate cooler (6) is effectively utilized.

10. The electric, gas and suspension three-composite lithium ore roasting process according to claim 7 is characterized in that: Step S2: the electric heating kiln primary roasting also includes the following operations: An exhaust valve (10-1) at the kiln head of the electric heating kiln (10) is opened or closed regularly according to the air pressure in the electric heating kiln (10) to keep the air pressure in the kiln stable; the exhaust flue gas is dust-removed by the exhaust gas treatment device.

Images