Harmless treatment method and equipment for electrolytic manganese residues

Abstract

The invention relates to a harmless treatment method and equipment for electrolytic manganese residues, and belongs to the technical field of industrial solid waste utilization. The method comprises the following steps: a, mixing the electrolytic manganese residues with an additive, quickly drying at 450-600 DEG C for 3-5 seconds to remove free water, and crushing; b, separating the dried material, levigating coarse powder, enabling the levigated coarse powder and fine powder to pass through a primary suspension preheater and a secondary suspension preheater, feeding the levigated coarse powder and fine powder into a suspension calcining furnace, and calcining at 700-1000 DEG C, so that Mn ions are oxidized, Cd ions form insoluble sulfate, and ammonium salt is decomposed into NHH for recovery; and d, carrying out heat preservation on the calcined slag through a surge bin, carrying out graded cooling through first-stage, second-stage and third-stage suspension coolers, and then conveying and storing. The equipment comprises a raw material treatment unit, a grinding unit, a calcining unit, a cooling unit and a conveying and storing unit to realize continuous treatment. According to the invention, the heavy metal leaching toxicity is reduced by more than 90%, and the comprehensive energy consumption is reduced by 30% by using preheater waste gas drying and cooler hot air combustion supporting; the product dihydrate gypsum is converted into II-type anhydrous gypsum, the specific surface area is larger than or equal to 450 m / kg, and the II-type anhydrous gypsum can replace 30% of cement to be used for building materials.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of industrial solid waste, and in particular to a method and equipment for harmless treatment of electrolytic manganese slag. Background Art

[0002] my country's electrolytic manganese production capacity is primarily concentrated in Ningxia, Guangxi, Guizhou, Hunan, Chongqing, and Xinjiang. Typically, each ton of manganese metal produces 7 to 9 tons of combined slag. However, with increasing ore depletion in some regions of the country, a few companies are producing over 10 tons of slag per ton of manganese. Based on 2021 electrolytic manganese metal production, the nation's annual new slag production is estimated to be over 10 million tons. Based on historical cumulative production, the national inventory of manganese slag has exceeded 170 million tons. Furthermore, with increasing demand for raw materials for lithium batteries such as electrolytic manganese dioxide, high-purity manganese sulfate, and high-purity manganese tetraoxide, the output of this type of manganese slag has also surged.

[0003] Manganese slag is a neutral or weakly acidic waste residue produced during the solid-liquid separation process of manganese ore powder leaching with sulfuric acid to prepare manganese electrolyte. The composition and properties of manganese slag vary depending on the ore and process. Most slag is black, with a few being brownish-gray. After filter pressing, it forms a cake-like shape. After storage, it gradually disperses and becomes a paste due to excessive water absorption. Due to the limitations of the filter pressing process and the water-holding capacity of the slag, the moisture content of newly generated slag is approximately 25% to 30%. The fine particle size of the slag is primarily between 3 and 30 μm, accounting for approximately 70% to 80%.

[0004] Electrolytic manganese slag contains a large amount of NH4 + -N, Mn 2+ 、Cu 2+ 、Zn 2+ Cr 6+ 、Cd 2+ 、Se 4+ , Pb 2+ and Ni 2+ Due to historical and technological issues, these pollutants are prone to migration during the process of reduction, harmlessness and resource utilization, damaging the surrounding ecological environment. At present, the main method of disposing of electrolytic manganese slag is storage. Some slag yards have improper anti-seepage measures, which makes it easy for pollutants in electrolytic manganese slag to enter water bodies, soil and air, disrupting the ecological balance and endangering human health. There is a lack of mature reduction measures for newly generated and stored electrolytic manganese slag, and the comprehensive resource utilization methods are still immature. As a result, the current stockpiles of electrolytic manganese slag are increasing, and the potential ecological and environmental hazards are becoming more and more serious, which has become a bottleneck restricting the development of the electrolytic manganese industry.

[0005] Although researchers at home and abroad have conducted extensive research on the resource utilization of electrolytic manganese slag for building materials and have carried out some industrial demonstrations, the comprehensive utilization of electrolytic manganese slag is small, the utilization rate is low, and the product quality is unstable. There are no successful cases of efficient and scalable application. The main reason is that the high-moisture electrolytic manganese slag contains high levels of ammonia nitrogen and sulfate. The current deamination and desulfurization processes are immature, the pretreatment costs are high, the harmful substances in the electrolytic manganese slag are difficult to detoxify, and the products produced are prone to secondary pollution, which harms the ecological environment. At the same time, due to process limitations, the electrolytic manganese slag production process cannot achieve deep harmlessness. In fact, the harmlessness process will even generate more waste, making it difficult to reduce and harmlessly treat the electrolytic manganese slag.

[0006] Only resource utilization can truly achieve large-scale disposal of electrolytic manganese slag. Building materials, as the main way to dispose of electrolytic manganese slag, can achieve large-scale disposal of electrolytic manganese slag. Therefore, based on the physical and chemical properties, ecological and environmental characteristics, and the current research status of reduction and resource utilization of electrolytic manganese slag, this paper systematically sorts out the current ways and problems of resource utilization of electrolytic manganese slag building materials, and proposes corresponding solutions in a targeted manner. This is of great significance to achieving large-scale utilization of electrolytic manganese slag and ensuring the sustainable development of the electrolytic manganese industry. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method and equipment for harmless treatment of electrolytic manganese slag to achieve the conversion of pollutant resources.

[0008] The technical solution adopted by the present invention to solve the technical problem is a harmless treatment method for electrolytic manganese slag, comprising the following steps:

[0009] a. After mixing the electrolytic manganese slag with the admixture, quickly dry it at 450-600°C for 3-5 seconds to remove free water and simultaneously crush it;

[0010] b. After drying, the material is separated into coarse and fine powders. The coarse powder is ground to a particle size of ≤0.2mm and then collected with the fine powder through a first-stage suspension preheater;

[0011] c. The fine powder passes through the secondary suspension preheater and then enters the suspension calcining furnace for calcination at 700-1000℃;

[0012] d. After calcination, the manganese slag powder is kept warm in the buffer bin, and then cooled in stages through the first-stage suspension cooler, the second-stage suspension cooler and the third-stage suspension cooler, and then transported to the finished product storage warehouse for storage.

[0013] Furthermore, the admixture in step a includes at least one of lime, pyrite or fly ash; in step c, lime oxidizes divalent Mn ions into MnO2 / Mn3O4 and solidifies; pyrite causes divalent Cd ions to form insoluble sulfates at ≥800°C, and volatilized cadmium is captured by a dust treatment unit; ammonium salts are decomposed into NH3 in a primary suspension preheater, and ammonia water is formed and recovered by spraying. The calcination temperature in step c is preferably 800-900°C.

[0014] Furthermore, the drying heat source in step a comes from the high-temperature exhaust gas at the outlet of the secondary suspension preheater, and the drying process is equipped with a safety air distribution device.

[0015] Furthermore, in step b, the coarse powder is fed into a pulverizer, passes through a coarse powder separator and a fine powder separator, and is then collected by a primary suspension preheater together with the original fine powder;

[0016] Furthermore, the hot air flow discharged from the first-stage suspension cooler in step d is used as combustion air for the suspension calciner; if the temperature is lower than 600-650°C, hot air is supplemented by the boiling furnace system.

[0017] The electrolytic manganese slag harmless treatment equipment is applied to the electrolytic manganese slag harmless treatment method, including a raw material processing unit, a grinding unit, a calcining unit, a cooling unit and a transportation and storage unit connected in sequence;

[0018] The raw material processing unit includes a box-type feeding and seasoning machine, a belt conveyor, a permanent magnetic iron remover, a quantitative feeder, a crusher, an air-locking feeder and a dryer connected in sequence;

[0019] The grinding unit includes a coarse powder separator, a pulverizer and a fine powder separator;

[0020] The calcining unit comprises a first-stage suspension preheater, a second-stage suspension preheater and a suspension calcining furnace connected in series;

[0021] The cooling unit includes a calcined material separator, a buffer bin, and a first-stage suspension cooler, a second-stage suspension cooler, and a third-stage suspension cooler connected in series;

[0022] The conveying and storing unit comprises an air-powder mixer, a finished product collector, a cooling induced draft fan, a first air conveying chute, an elevator, a second air conveying chute and a finished product storage.

[0023] Furthermore, a coarse particle sedimentation device is provided at the outlet of the high-efficiency and fast drying machine;

[0024] The hot air outlet of the first-stage suspension cooler is connected to the combustion air inlet of the suspension calciner;

[0025] The boiling furnace system is connected to the combustion air duct on the suspension calciner.

[0026] Furthermore, it also includes a dust processing unit, which includes a system main fan, a dust collector and a dust removal fan connected in series, and the system main fan is connected to the fine powder separator and the first-level suspension preheater respectively.

[0027] Furthermore, a modified pulverizer is provided between the finished product collector and the first air conveying chute.

[0028] Furthermore, the fuel of the suspension calciner is at least one of coal, natural gas, coal gas or fuel coke.

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

[0030] 1. At 800–900℃ calcination temperature, lime oxidizes divalent Mn ions to stable MnO2 / Mn3O4; pyrite promotes Cd² + Insoluble sulfates are formed, and volatile cadmium is captured by the dust treatment unit, reducing leaching toxicity by over 90%. Ammonium salts are decomposed into NH3 in the primary suspension preheater and recycled as ammonia water via spraying, achieving pollutant resource conversion.

[0031] 2. The high-temperature exhaust gas at the outlet of the secondary suspension preheater is used as the heat source for the rapid dryer; the 600-650℃ hot air discharged from the primary suspension cooler is used as the combustion air for the calciner, reducing the overall energy consumption by about 30%.

[0032] 3. Calcination at 700-1000℃ converts dihydrate gypsum into type II anhydrous gypsum, retaining the gelling activity; the silicate mineral content in the calcined slag is increased, and after being processed by a modified grinding mill, the specific surface area is ≥450m² / kg, which can replace 30% of cement for roadbed materials or mine filling. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the present invention.

[0034] Reference numerals: 1-box-type feeder and seasoning machine; 2-belt conveyor; 3-permanent magnetic iron remover; 4-quantitative feeder; 5-crusher; 6-air-locking feeder; 7-dryer; 8-coarse particle settling device; 9-safety air distribution device; 10-coarse powder separator; 11-pulverizer; 12-fine powder separator; 13-primary suspension preheater; 14-secondary suspension preheater; 15-calcined material separator; 16-suspension calcining furnace; 17-Buffer bin; 18-Crusher; 19-First-stage suspension cooler; 20-Second-stage suspension cooler; 21-Third-stage suspension cooler; 22-Air-powder mixer; 23-Finished product collector; 24-Cooling induced draft fan; 25-Modified pulverizer; 26-System main fan; 27-Dust collector; 28-Dust removal fan; 29-First air conveying chute; 30-Elevator; 31-Second air conveying chute; 32-Manganese slag powder storage. DETAILED DESCRIPTION

[0035] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0036] The harmless treatment method of electrolytic manganese slag of the present invention comprises the following steps:

[0037] a. The manganese slag is fed into a box-type feeder and seasoning machine 1. After being metered and dosed with a quantitative feeder 4, it enters a belt conveyor 2. The slag is then removed of impurities such as iron by a permanent magnetic iron remover 3 and fed into a crusher 5. The slag enters a dryer 7 via a wind-locked feeder 6, where it is dried at a temperature of 450-600°C to remove free water. The removal time is preferably 3-5 seconds. The manganese slag is simultaneously pulverized during drying to prevent agglomeration during the suspension calcination process. A coarse particle settling device 8 is installed at the outlet of the dryer 7 to ensure that the outlet manganese slag particle size meets the requirements. The heat source of the dryer 7 is the high-temperature exhaust gas from the outlet of the secondary suspension preheater 14, and a safety air distribution device 9 is installed in the heat source air duct of the dryer 7.

[0038] b. The dry manganese slag powder obtained from the dryer 7 exits and enters the coarse powder separator 10. The coarse powder is fed into the pulverizer 11. After passing through the coarse powder separator 10 and the fine powder separator 12, the powder is collected together with the original fine powder by the primary suspension preheater 13. The exhaust gas at the outlet of the primary suspension preheater 13 is purified by the system main fan 26 and the dust collector 27, and then desulfurized and deaminated by the dust removal fan 28 before being discharged.

[0039] c. The dry manganese slag powder is collected in the primary suspension preheater 13 and discharged into the secondary suspension preheater 14. After heat exchange and separation in the secondary suspension preheater 14, it enters the suspension calciner 16 for calcination. The outlet air temperature of the suspension calciner 16 is regulated by adjusting the fuel supply from the fuel supply system. The hot air flow from the primary suspension cooler 19 serves as the combustion air for the calciner 16 and enters the bottom of the calciner 16. The inlet temperature of the hot air flow entering the bottom of the calciner 16 is required to reach 600-650°C. If the outlet temperature of the hot air flow from the primary suspension cooler 19 falls below 600-650°C, the fluidized bed furnace system provides additional hot air for regulation. The amount of fuel added to the calciner fuel supply system is based on controlling the calcination temperature at 700-1000°C, preferably 800-900°C; lime oxidizes divalent Mn ions into MnO2 / Mn3O4 and solidifies them; pyrite causes divalent Cd ions to form insoluble sulfates at ≥800°C; fly ash and manganese slag powder are fully mixed to retain gelling activity.

[0040] d. The manganese slag powder exiting the suspension calciner 16 is collected by the calcined material separator 15 and enters the buffer bin 17. After a certain period of heat preservation, it is fed into the primary suspension cooler 19. After heat exchange, it enters the secondary suspension cooler 20 for separation. It is then fed into the tertiary suspension cooler 21. Cold air enters through the inlet pipe of the tertiary suspension cooler 21. The manganese slag powder undergoes heat exchange and separation in the tertiary suspension cooler 21. After being collected by the tertiary suspension cooler 21, it enters the air-powder mixer 22, the finished product collector 23, and the cooling induced draft fan 24. The manganese slag powder collected by the finished product collector 23 is ground in the modified pulverizer 25 and then enters the manganese slag powder storage 32 through the first air conveying chute 29, the elevator 30, and the second air conveying chute 31. The manganese slag powder entering the manganese slag powder storage 32 must have a temperature of ≤60°C.

[0041] like Figure 1 As shown, the electrolytic manganese slag harmless treatment equipment is applied to the electrolytic manganese slag harmless treatment method, including a raw material processing unit, a grinding unit, a calcining unit, a cooling unit and a transportation and storage unit connected in sequence;

[0042] The raw material processing unit includes a box-type feeding and seasoning machine 1, a belt conveyor 2, a permanent magnetic iron remover 3, a quantitative feeder 4, a crusher 5, an air-locking feeder 6 and a dryer 7 connected in sequence;

[0043] The grinding unit includes a coarse powder separator 10, a pulverizer 11 and a fine powder separator 12;

[0044] The calcining unit includes a primary suspension preheater 13, a secondary suspension preheater 14 and a suspension calcining furnace 16 connected in series;

[0045] The cooling unit includes a calcined material separator 15, a buffer bin 17, and a first-stage suspension cooler 19, a second-stage suspension cooler 20, and a third-stage suspension cooler 21 connected in series;

[0046] The conveying and storing unit includes an air-powder mixer 22 , a finished product collector 23 , a cooling induced draft fan 24 , a first air conveying chute 29 , an elevator 30 , a second air conveying chute 31 and a finished product storage silo 32 .

[0047] The loader feeds the manganese slag into a box-type feeder and seasoning machine 1, which then feeds it to an air-lock feeder 6 via a belt conveyor 2. A permanent magnetic iron remover 3 is located above the belt conveyor 2; it removes iron-containing impurities from the manganese slag, preventing them from entering the dryer 7. A quantitative feeder 4, located above the belt conveyor 2, adds additives to the manganese slag, each of which is placed in a separate additive bin. A new impact-type wet-frozen clay crusher is used to initially crush large particles of manganese slag to facilitate subsequent drying. The discharge port of the air-locking feeder 6 is connected to the feed port of the dryer 7. The air-locking feeder 6 can input the manganese slag into the dryer 7 while preventing natural wind from entering the dryer 7 and affecting the drying effect. The air-locking feeder 6 ensures that the manganese slag is dried, preheated, calcined and cooled in a closed suspension space, while preventing the hot air from carrying untreated particulate matter and harmful substances to escape into the external environment; the dryer 7 is an efficient and fast dryer for powder, and the manganese slag is crushed while being dried in the dryer 7.

[0048] The coarse powder separator 10 is used to separate the manganese slag dried and crushed by the dryer 7. The manganese slag with a particle size of ≤0.2 mm enters the fine powder separator 12, and the manganese slag with a particle size of >0.2 mm is coarse powder. The coarse powder enters the pulverizer 11, is ground and then separated by the coarse powder separator 10 until all the manganese slag is transported to the fine powder separator 12.

[0049] The calcination unit includes a first-stage suspension preheater 13, a second-stage suspension preheater 14, and a suspension calcining furnace 16 connected in series; the outlet of the fine powder separator 12 is connected to the inlet of the first-stage suspension preheater 13; the discharge port of the first-stage suspension preheater 13 is connected to the inlet of the second-stage suspension preheater 14; and the discharge port of the second-stage suspension preheater 14 is connected to the inlet of the suspension calcining furnace 16; in the first-stage suspension preheater 13, the manganese slag is fully heat-exchanged with hot air and preheated to 450-600°C; the manganese slag preheated for the first time enters the second-stage suspension preheater 14, where it is heated by the hot air from the separator and preheated for a second time to 650-700°C; the manganese slag preheated for the second time enters the suspension calcining furnace 16 for suspension calcination. The first-stage suspension preheater 13 and the second-stage suspension preheater 14 are both cyclone separators that can separate gas and solid substances. They are both provided with an inlet, an outlet and a discharge port. The material discharged from the discharge port of the first-stage suspension preheater 13 is mixed with the preheated gas to form a gas-solid mixture, which then enters the inlet of the second-stage suspension preheater 14.

[0050] The manganese slag powder exiting the suspension calciner 16 is collected by the calcined material separator 15 and enters the buffer bin 17. After a certain period of heat preservation, it is fed into the primary suspension cooler 19, and then enters the secondary suspension cooler 20 for separation after heat exchange; it is then fed into the tertiary suspension cooler 21, and cold air enters from the inlet pipe of the tertiary suspension cooler 21. The manganese slag powder is separated again after heat exchange and the tertiary suspension cooler 21.

[0051] The transport and storage unit includes an air-powder mixer 22, a finished product collector 23, a cooling induced draft fan 24, a first air transport chute 29, an elevator 30, a second air transport chute 31, and a finished product storage depot 32. The feed port of the air-powder mixer 22 is connected to the discharge port of the three-stage suspension cooler 21, the air outlet of the air-powder mixer 22 is connected to the air inlet of the finished product collector 23, and the input end of the cooling induced draft fan 24 is connected to the exhaust port of the finished product collector 23. The cooling induced draft fan 24 facilitates the discharge of the gas phase separated in the finished product collector 23 from the finished product collector 23, thereby improving the gas-solid separation effect in the finished product collector 23. To facilitate air-powder mixing and transportation, a blower is connected to the air-powder mixer 22. The output end of the blower is connected to the air inlet of the air-powder mixer 22. The blower inputs gas into the air-powder mixer 22 for air-powder mixing, and under the propulsion of the gas, the powder is input into the finished product collector 23 for gas-solid separation. Then it is delivered to the finished product storage 32 through the first air delivery chute 29, the elevator 30, and the second air delivery chute 31.

[0052] To prevent excessively large manganese slag particles from entering the coarse powder separator 10, a coarse particle settling device 8 is installed at the outlet of the dryer 7. The hot air outlet of the primary suspension cooler 19 is connected to the combustion air inlet of the suspension calciner 16. The fluidized bed furnace system is connected to the combustion air duct of the suspension calciner 16. The coarse particle settling device 8 has an inlet and an outlet. The inlet of the coarse particle settling device 8 is connected to the outlet of the dryer 7, and the outlet of the coarse particle settling device 8 is connected to the inlet of the suspension preheater. Specifically, the coarse particle settling device 8 is installed above the outlet of the dryer 7. Coarse manganese slag particles entering the coarse particle settling device 8 are filtered, settled, and then returned to the dryer 7 through the outlet of the dryer 7. The hot air flow from the primary suspension cooler 19 serves as the combustion air for the calciner 16, entering the bottom of the calciner 16. The inlet temperature of the hot air flow entering the bottom of the calciner 16 is required to reach 600-650°C. If the outlet temperature of the hot air flow from the primary suspension cooler 19 falls below 600-650°C, the fluidized bed furnace system provides supplemental hot air for regulation.

[0053] To prevent dust pollution, a dust treatment unit is further included. The dust treatment unit comprises a system main fan 26, a dust collector 27, and a dust removal fan 28 connected in series. The system main fan 26 is connected to the primary suspension preheater 13. The exhaust gas at the outlet of the primary suspension preheater 13 is purified by the system main fan 26 and the dust collector 27, and then desulfurized and deammonified by the dust removal fan 28 before being discharged.

[0054] In order to crush the large particles of manganese slag in the finished product collector 23 , a modified pulverizer 25 is further provided between the finished product collector 23 and the first air conveying chute 29 .

[0055] Furthermore, the fuel of the suspension calciner 16 is at least one of coal, natural gas, coal gas or fuel coke.

[0056] Example 1

[0057] Raw material pretreatment

[0058] The electrolytic manganese slag with a moisture content of 25-30% is transported to the box-type feeder and seasoning machine 1, and lime and 5% pyrite are added according to the slag weight. After iron removal by the permanent magnetic iron remover 3, it is pre-crushed by the crusher 5.

[0059] The material enters the dryer 7 through the air-lock feeder 6 and is fed into the 580°C exhaust gas discharged from the secondary suspension preheater 14. The temperature is raised to 550°C within 3 seconds, and the free water removal rate reaches 95%. The material is simultaneously crushed to a particle size of ≤1mm.

[0060] Grinding and preheating

[0061] After drying, the material is sorted by the coarse particle sedimentation device 8, and the coarse powder >0.2mm is sent to the pulverizer 11 and ground to ≤0.2mm, and is collected by the first-level suspension preheater 13 together with the fine powder.

[0062] The powder is subjected to countercurrent heat exchange with the high-temperature flue gas of the calcining furnace in the secondary suspension preheater 14 , and then enters the suspension calcining furnace 16 after the temperature is raised to 650° C.

[0063] Suspension calcination

[0064] Using pulverized coal as fuel, the furnace temperature is controlled at 850±20°C, and the calcination time is 15 seconds: divalent Mn ions are oxidized to Mn3O4; divalent Cd ions react with pyrite to form CdSO4, and volatile cadmium is captured by dust collector 27. After calcination, the material is kept warm in buffer bin 17 for 10 minutes to promote mineral phase transformation.

[0065] Cascade cooling and finished products

[0066] The hot slag powder enters the calcined material separator 15, the buffer bin 17, the primary suspension cooler 19, the secondary suspension cooler 20, and the tertiary suspension cooler 21 in sequence. The 620°C hot air discharged from the primary suspension cooler 19 serves as combustion air for the calciner 16. If the temperature is insufficient, it is supplemented by the fluidized bed furnace. The slag temperature at the outlet of the tertiary cooler 21 drops to 120°C before being cooled to 55°C in the conveying and storage unit. The finished product is ground in the modified pulverizer 25 and stored in the manganese slag powder storage 32.

[0067] Environmental control

[0068] The NH3-containing waste gas discharged from the first-stage suspension preheater 13 is recovered as 15% ammonia water through the spray tower; the system main fan 26 guides the flue gas into the dust collector 27 + activated carbon adsorption unit, and the tail gas Cd concentration is <0.05mg / m³.

[0069] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for harmless treatment of electrolytic manganese slag, characterized in that: The following steps are involved: a. After mixing the electrolytic manganese slag with the admixture, quickly dry it at 450-600°C for 3-5 seconds to remove free water and simultaneously crush it; b. After drying, the material is separated into coarse and fine powders, the coarse powder is ground to a particle size of ≤0.2 mm, and then collected along with the fine powder through a first-stage suspension preheater (13); c. The fine powder passes through a secondary suspension preheater (14) and then enters a suspension calcining furnace (16) and is calcined at 700 to 1000°C; d. After calcination, the manganese slag powder is kept warm in a buffer bin (17), sequentially cooled by a primary suspension cooler (19), a secondary suspension cooler (20), and a tertiary suspension cooler (21), and then transported to a finished product storage warehouse (32) for storage.

2. The harmless treatment method for electrolytic manganese slag according to claim 1, characterized in that: The admixture in step a comprises at least one of lime, pyrite or fly ash; in step c, lime oxidizes divalent Mn ions into MnO2 / Mn3O4 and solidifies; pyrite causes divalent Cd ions to form insoluble sulfate at ≥800°C, and the volatilized cadmium is captured by a dust treatment unit; ammonium salt is decomposed into NH3 in a primary suspension preheater (13), and ammonia water is formed by spraying for recovery. The calcination temperature in step c is preferably 800-900°C.

3. The harmless treatment method for electrolytic manganese slag according to claim 1, characterized in that: The drying heat source of step a comes from the high-temperature exhaust gas at the outlet of the secondary suspension preheater (14), and the drying process is equipped with a safety air distribution device (9).

4. The harmless treatment method for electrolytic manganese slag according to claim 1, characterized in that: In step b, the coarse powder is fed into the pulverizer (11), passes through the coarse powder separator (10) and the fine powder separator (12), and is then collected together with the original fine powder by the first-stage suspension preheater (13).

5. The harmless treatment method for electrolytic manganese slag according to claim 1, characterized in that: In step d, the hot air flow discharged from the first-stage suspension cooler (19) is used as the combustion air for the suspension calciner (16); if the temperature is less than 600-650°C, the hot air is supplemented by the boiling furnace system.

6. Electrolytic manganese slag harmless treatment equipment, applied to the electrolytic manganese slag harmless treatment method according to any one of claims 1 to 5, characterized in that: It includes a raw material processing unit, a grinding unit, a calcining unit, a cooling unit and a transportation and storage unit connected in sequence; The raw material processing unit comprises a box-type feeder and seasoning machine (1), a belt conveyor (2), a permanent magnetic iron remover (3), a quantitative feeder (4), a crusher (5), an air-locking feeder (6), and a dryer (7) connected in sequence; The grinding unit comprises a coarse powder separator (10), a grinding mill (11) and a fine powder separator (12); The calcining unit comprises a first-stage suspension preheater (13), a second-stage suspension preheater (14) and a suspension calcining furnace (16) connected in series; The cooling unit includes a calcined material separator (15), a buffer bin (17), and a first-stage suspension cooler (19), a second-stage suspension cooler (20), and a third-stage suspension cooler (21) connected in series; The conveying and storage unit comprises an air-powder mixer (22), a finished product collector (23), a cooling induced draft fan (24), a first air conveying chute (29), an elevator (30), a second air conveying chute (31) and a finished product storage (32).

7. The harmless treatment equipment for electrolytic manganese slag according to claim 6, characterized in that: The outlet of the high-efficiency fast drying machine (7) is provided with a coarse particle sedimentation device (8); The hot air outlet of the first-stage suspension cooler (19) is connected to the combustion air inlet of the suspension calcining furnace (16); The fluidized bed furnace system is connected to the combustion air duct on the suspension calcining furnace (16).

8. The harmless treatment equipment for electrolytic manganese slag according to claim 6, characterized in that: The system further comprises a dust treatment unit, wherein the dust treatment unit comprises a system main fan (26), a dust collector (27) and a dust removal fan (28) connected in series, wherein the system main fan (26) is connected to the fine powder separator (12) and the first-stage suspension preheater (13) respectively.

9. The harmless treatment equipment for electrolytic manganese slag according to claim 6, characterized in that: A modified pulverizer (25) is provided between the finished product collector (23) and the first air conveying chute (29).

10. The harmless treatment equipment for electrolytic manganese slag according to claim 6, characterized in that: The fuel of the suspension calciner (16) is at least one of coal, natural gas, coal gas or fuel coke.

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