Process for smelting manganese-rich slag from magnetically roasted manganese ore

Abstract

The application provides a process for smelting manganese-rich slag from magnetized roasted manganese ore, and belongs to the technical field of manganese-rich slag production. The process comprises a preheater, a rotary kiln, a cooler and a blast furnace smelting process. After the manganese ore is magnetized and roasted in the rotary kiln, the cooled and magnetically separated and proportioned material is sent into the blast furnace for smelting, fire enrichment, separation and extraction to produce the manganese-rich slag. The application changes the production process, and performs hot melting roasting on low-grade polymetallic symbiotic and associated difficult-to-select primary lean manganese ore to produce the manganese-rich slag through fire enrichment, separation and extraction.

Description

Technical Field

[0001] This invention belongs to the field of production technology of manganese-rich slag, and particularly relates to a process for smelting manganese-rich slag by magnetizing roasted manganese ore. Background Technology

[0002] Currently, the main application area of ​​manganese ore is the steel industry. With the continuous expansion of the steel industry and the breakthrough in the technology of new ternary battery cathode materials, my country has become the world's largest consumer, producer, processor and exporter of manganese ore, with an import dependence rate of over 95%. In the foreseeable future, the import dependence rate of China's manganese ore market will remain high.

[0003] In terms of quality, my country's manganese ore is mostly low-grade, with complex mineral composition, often consisting of associated minerals. The mineral particles are fine and difficult to beneficiate, resulting in low commercial value. However, pyrometallurgical enrichment can fully utilize these resources. Pyrometallurgical enrichment of manganese ore is a sorting method for processing high-phosphorus, high-iron, and difficult-to-beneficiate low-grade manganese ore, generally known as the rich-manganese slag method.

[0004] Traditional blast furnace smelting of manganese-rich slag requires the manganese ore powder to be batched, mixed, and then fed into a sintering machine to form lumps. The sintered ore is then fed into a blast furnace for selective reduction smelting. However, this sintering-blast furnace selective reduction smelting process suffers from problems such as dust pollution, high consumption of auxiliary materials, and the need for large amounts of coke and electricity, resulting in relatively high production costs. It is difficult to address the issue of sintering the ore powder before feeding it into the blast furnace, as the use of coke in sintering leads to significant pollution, high energy consumption, and low production efficiency. Furthermore, the blast furnace smelting process for manganese-rich slag can only remove iron, phosphorus, and other non-ferrous metals, but cannot remove gangue; additionally, the coke introduces ash, increasing the impurity content.

[0005] In the past, the rotary kiln + blast furnace process for producing manganese-rich slag also had inherent disadvantages such as material melting during the smelting process, slag being pasty and easy to stick, often leading to rotary kiln ring formation failures, severe furnace lining erosion, and high energy consumption, resulting in limited application of the process. Summary of the Invention

[0006] Based on the above, this invention discloses a process for smelting manganese-rich slag from magnetized roasted manganese ore. The process employs a preheater + rotary kiln + cooler + blast furnace smelting process. After the manganese ore is magnetized and roasted in the rotary kiln, it is cooled, magnetically separated, and then fed into the blast furnace for smelting. The process involves pyrometallurgical enrichment, separation, and extraction to produce manganese-rich slag. This invention changes the production process by using hot-melt roasting to pyrometallurgical enrichment, separation, and extraction of low-grade, polymetallic, and difficult-to-process primary manganese ore to produce manganese-rich slag.

[0007] The process for smelting manganese-rich slag from magnetized roasted manganese ore according to the present invention includes the following steps: (1) The manganese ore is fed into the preheater and the ore is preheated by the flue gas from the tail of the rotary kiln; the preheated ore is then directly fed into the rotary kiln. (2) The manganese ore is roasted in a rotary kiln; (3) After roasting, the manganese ore is continuously discharged from the rotary kiln into the cooler for cooling; (4) After cooling, the manganese ore is screened to obtain oversize lumps and undersize powder; the oversize lumps are magnetically separated to obtain gangue and iron-manganese ore. (5) The iron-manganese ore is mixed with coke and flux and then fed into a blast furnace for smelting to obtain liquid slag and molten iron. After slag formation, molten iron and manganese-rich slag are obtained.

[0008] Preferably, the manganese content in the manganese ore in step (1) is ≤12%; the particle size of the manganese ore is 20-50mm.

[0009] Preferably, the temperature of the kiln tail flue gas in step (1) is 500-550℃; and the temperature of the preheated ore is 200℃-300℃.

[0010] Preferably, in step (2), the rotary kiln speed is 0.2 to 1.85 rpm, the fuel is blast furnace gas, the roasting temperature is 1150℃ to 1200℃, and the roasting time is 1.5h to 3h.

[0011] More preferably, the blast furnace gas comprises the following volume fractions: CO 26%–32%, N2 55%–65%, CO2 8%–12%, H2 1.0%–3.0%, CH4 0.2%–0.8%, and O2 0.2%–0.5%.

[0012] Preferably, the outlet temperature of the cooler in step (3) is ≤100℃.

[0013] Preferably, the sieve aperture size of the sieve in step (4) is 8~10mm.

[0014] Preferably, the intensity of magnetic separation of the sieve block material in step (4) is 8000~10000 Oersted, and the magnetic separation time is 5~20s.

[0015] Preferably, in step (5), the mass ratio of the iron-manganese ore to coke and flux is 100:28-35:0-3, the flux is limestone, and the coke has more than 82% fixed carbon.

[0016] Preferably, the smelting temperature in step (5) is 1250℃~1350℃.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention uses low-grade manganese ore as raw material and employs a preheater + rotary kiln pre-reduction + cooler + blast furnace smelting process. After pre-reduction and magnetization in the rotary kiln, CO2 and water of crystallization in the manganese ore are effectively removed. After cooling, further screening and magnetic separation remove gangue and powder, resulting in a high manganese content in the furnace feed, with manganese and iron grades increased by 12%–14%. The blast furnace smelting process is short, energy-saving, and reduces pollution. During the rotary kiln pre-reduction roasting process of this invention, some phosphorus and sulfur in the manganese ore can be separated with the hot flue gas and discharged and treated through the flue gas at the tail of the rotary kiln. The waste heat of the hot flue gas at the kiln tail is used as the heat source for the preheater, which increases the temperature of the manganese ore entering the rotary kiln and shortens the residence time of the manganese ore in the rotary kiln. After the cooler cools the roasted material, the hot air is used as secondary air in the rotary kiln, increasing the temperature of the secondary air, reducing the amount of gas used, saving energy, and reducing pollution. These process modifications can effectively reduce the roasting time in the kiln during manganese ore roasting, reduce ring formation, improve the strength of the roasted ore, and lower the loss on ignition. Specifically, due to the above measures, the increased preheating ensures that the internal and external temperatures of the manganese ore are higher when it enters the high-temperature calcination zone than without preheating. This allows for a reduction in roasting temperature by 50-100℃ during production, preventing ring formation and ensuring smooth production. Through these process improvements, the strength of the roasted ore is increased, and the loss on ignition can be reduced to less than 3%. This invention belongs to the pyrometallurgical enrichment process, which is simple and stable in production. Through reduction roasting and magnetic separation using a preheater, rotary kiln, and cooler, it can smelt low-manganese ore and effectively separate gangue, phosphorus, and iron from the ore, thereby improving the grade of manganese-rich slag and obtaining manganese-rich, low-iron, and low-phosphorus manganese-rich slag. This manganese-rich slag generally contains 24% to 45% Mn, 2% to 5% Fe, and P / Mn < 0.002, making it a high-quality manganese alloy raw material.

[0018] This invention improves the grade and activity of the feed material. The preheated rotary kiln roasting process involves gradual, slow heating, dehydration followed by decomposition, resulting in uniform temperature, intact pore structure, and high phase activity. The resulting roasted ore exhibits high porosity, large specific surface area, reasonable roughness, good particle size distribution, no over-burning, and easy phase reduction. It also offers advantages such as energy saving, low pollution, high production efficiency, and low production cost. Detailed Implementation

[0019] The process for smelting manganese-rich slag by magnetized roasting manganese ore according to the present invention comprises the following steps: (1) Manganese ore with a particle size of 20-50mm (manganese content in the ore ≤12%) is fed into the preheater and preheated with the flue gas from the rotary kiln tail at 500-550℃ to obtain preheated ore at 200℃-300℃; the preheated ore is then directly fed into the rotary kiln through the transfer chute of the preheater. (2) The manganese ore is roasted in a rotary kiln (rotary kiln speed is 0.2 to 1.85 rpm, fuel is blast furnace gas (CO: 26% to 32%), N2: (55% to 65%), CO2: (8% to 12%), H2: (1.0% to 3.0%), CH4: (0.2% to 0.8%), O2: (0.2% to 0.5%)) at 1150℃ to 1200℃ for 1.5 to 3 hours; during the roasting process in the rotary kiln, sulfur and phosphorus in the manganese ore are partially separated from the ore and discharged with the hot flue gas through the tail gas of the rotary kiln; the manganese ore is magnetized and pre-reduced; (3) After roasting, the manganese ore is continuously discharged from the rotary kiln into the cooler for cooling, and the discharge temperature is ≤100℃; the waste heat of the heat exchange hot air in the cooler can be used as secondary air for the rotary kiln, which reduces energy consumption and is energy-saving and environmentally friendly. (4) After cooling, the manganese ore is screened through a 10mm sieve to obtain oversize lumps and undersize powder; the oversize lumps are magnetically separated (using a 10000 Oersted strong magnet for 5-20 seconds) to obtain gangue and iron-manganese ore; the undersize powder is magnetically separated (using a 10000 Oersted strong magnet for 5-20 seconds) to obtain gangue and manganese powder; the gangue and powder are sent to the gangue silo and powder silo respectively. (5) The iron-manganese ore is mixed with coke and flux in a mass ratio of 100:28-35:0-3 and then fed into a blast furnace for smelting at 1250℃-1350℃ to obtain liquid slag-iron molten iron. After slag formation, molten iron and manganese-rich slag are obtained; the reduced manganese content in the molten iron is reduced and the amount of manganese added to the slag is increased; the flux is limestone; the fixed carbon in the coke is greater than 82%.

[0020] The technical solution of the present invention will be described in detail below with reference to embodiments and comparative examples.

[0021] Example 1 A process for smelting manganese-rich slag by magnetizing roasted manganese ore, comprising the following steps: (1) The manganese ore material (raw ore) with a particle size of 20-50mm is fed into the preheater and the ore material is preheated by the 500℃ rotary kiln tail flue gas to obtain the 260℃ preheated ore material; the preheated ore material is directly fed into the rotary kiln through the transfer chute of the preheater. (2) The manganese ore is roasted at 1150℃ for 2.5h in a rotary kiln to obtain roasted ore (roasted sand); the rotary kiln speed is 1.2 rpm, and the fuel is blast furnace gas (CO 31%, N2: 55%, CO2: 10%, H2: 3.0%, CH4: 0.5%, O2: 0.5%); during the roasting process in the rotary kiln, sulfur and phosphorus in the manganese ore are partially separated from the ore and discharged with the hot flue gas through the tail gas of the rotary kiln; the manganese ore is magnetized and pre-reduced; (3) The roasted ore (750℃) is continuously discharged from the rotary kiln into the cooler for cooling, and the discharge temperature is ≤100℃; (4) After cooling, the manganese ore is screened through a 10 mm sieve to obtain oversize lumps and undersize powder; the oversize lumps are magnetically separated (using a 10,000 Oersted strong magnet for 20 seconds) to obtain gangue and iron-manganese ore; the undersize powder is magnetically separated (using a 10,000 Oersted strong magnet for about 20 seconds) to obtain gangue and manganese powder; the gangue and powder are sent to the gangue silo and powder silo respectively. (5) The iron-manganese ore is mixed with coke (fixed carbon greater than 82%) and flux (limestone) in a mass ratio of 100:30:2 and then fed into a blast furnace for smelting at 1300℃ to obtain liquid slag iron. After slag formation, molten iron and manganese-rich slag are obtained.

[0022] Comparative Example 1 A process for smelting manganese-rich slag by magnetizing roasted manganese ore, with the same steps as in Example 1, is as follows: (1) The low-grade manganese ore material (raw ore) with a particle size of 20-50mm is fed into the rotary kiln tail chute via a conveyor belt and enters the rotary kiln; (2) The manganese ore was roasted in a rotary kiln at 1200℃ for 3.0h to obtain roasted ore; (3) The roasted ore (750℃) is continuously discharged from the rotary kiln and naturally stored for cooling; (4)~(5) Same as Example 1.

[0023] Comparative Example 2 A process for smelting manganese-rich slag by magnetizing roasting manganese ore, with the same steps as in Example 1, except that Comparative Example 2 does not have a preheater and a cooler. The steps are as follows: (1) The low-grade manganese ore material (raw ore) with a particle size of 20-50mm is fed into the rotary kiln tail chute via a conveyor belt and enters the rotary kiln; (2) The manganese ore was roasted in a rotary kiln at 1150℃ for 2.5h to obtain roasted ore (roasted sand). (3) The roasted ore (750℃) is continuously discharged from the rotary kiln and naturally stored for cooling; (4)~(5) Same as Example 1.

[0024] Example 1 uses a preheater and a cooler, which reduces the high-temperature roasting time and lowers the roasting temperature, resulting in more uniform roasting, a lower powder content, and therefore less ring formation. Comparative Example 2, however, does not include a preheating process and uses the same roasting parameters as Example 1, leading to uneven roasting. Specifically, compared to Comparative Example 2, which lacks a preheater and cooler, the roasting parameters result in a lower roasting temperature, shorter time, and incomplete sintering of the roasted ore.

[0025] Therefore, Comparative Example 1 was set up, which increased the roasting temperature and roasting time based on Comparative Example 2 to ensure complete roasting. However, the method in Comparative Example 1 was prone to ring formation.

[0026] A. The chemical composition and properties of the lean manganese ore and the roasted ore obtained in step (2) in Example 1 and Comparative Example 1 are shown in Table 1.

[0027] Table 1

[0028] The chemical composition of the manganese-rich slag in Example 1 and Comparative Example 1 is shown in Table 2.

[0029] Table 2

[0030] Analysis of Table 1 leads to the following conclusions: the roasting drum index and roasting intensity of the calcined ore in Example 1 are increased, and the loss on ignition is reduced to less than 3%. The S and P contents are low and meet the standards; the grades of manganese and iron can be increased by 12% to 14%. Analysis of Table 2 leads to the following conclusions: the manganese content in the manganese-rich slag of Example 1 is increased.

[0031] B. The moisture (H2O) and carbon dioxide (CO2) parameters of the medium-calcined sand in Example 1 and Comparative Example 1 are compared in Table 3 below: Table 3

[0032] Analysis conclusion: ① Differences in moisture control In Example 1, the rotary kiln with preheating slowly raises the temperature in the preheating section (200-600℃), which can remove adsorbed water from the surface and inside of the material (dehydration efficiency reaches 96%). In contrast, the process without preheating in Comparative Example 1 directly enters the high-temperature zone (above 950℃), and the rapid evaporation of water leads to local overheating, resulting in a dehydration efficiency of only 87%.

[0033] ② CO2 generation mechanism In Example 1, the preheating process decomposes manganese carbonate (MnCO3) into MnO and CO2 in the preheating section (200-600℃). The high-temperature section further promotes the complete reaction, and the total CO2 release reaches 94 kg / t of ore. In Comparative Example 1, the process without preheating has a short residence time in the high-temperature section, and the total CO2 release is only 75 kg / t of ore.

[0034] ③ Desulfurization effect Example 1, with its preheating process, promotes the oxidation of sulfur (such as FeS2) to SO2 through uniform heating, increasing the desulfurization rate to 70%, while the desulfurization rate of Comparative Example 1 without preheating is only 40%, and the SO2 concentration in the flue gas is higher.

[0035] ④ Process energy consumption and environmental friendliness Example 1, with its preheating process, improves thermal energy utilization by 15%-20% through waste heat recovery (reducing flue gas temperature to below 200°C), while in Comparative Example 1, without preheating, energy consumption increases by approximately 18% because the high-temperature flue gas carries away a large amount of latent heat (including water vapor and CO2).

[0036] C. Phases and activity in Example 1 and Comparative Example 1 Example 1, with preheating, involves a gradual and slow heating process, followed by dehydration and decomposition, resulting in uniform temperature, intact pore structure, and high phase activity. Comparative Example 1, without preheating, involves cold material being violently impacted by high temperature, causing sudden heating and cracking, local over-burning and under-burning, pore damage, particle pulverization, and inconsistent activity.

[0037] Example 1: Roasted ore roasted in a preheating kiln: High porosity, large specific surface area, reasonable roughness, good particle size distribution, no over-burning, easy phase reduction, and overall quality and activity are far superior to those of the rotary kiln without preheating in Comparative Example 1.

[0038] The physical properties of the manganese ore roasted in Example 1 and Comparative Example 1 are shown in Table 4.

[0039] Table 4

[0040] Phase analysis (in the following conclusions, preheating indicates the method of Example 1, and no preheating indicates the method of Comparative Example 1): Pore ​​structure optimization The preheated rotary kiln reduces sintering shrinkage through uniform heating, significantly increasing the proportion of micropores (10-50nm) to over 80% and improving porosity to 45%. In contrast, the process without preheating results in partial sintering closure due to localized high temperatures, leading to a porosity of only 35%.

[0041] ② Specific surface area and adsorption performance BET with preheating process has a specific surface area of ​​25 m² 2 / g, which is 5 times that of the original ore, and the pore volume is increased to 0.5 cm. 3 / g, significantly enhancing adsorption capacity.

[0042] ③ Particle refinement and surface smoothness The preheated calcined sand has a uniform particle size (50-150μm) and its roughness is reduced to 0.5-2μm.

[0043] ④ Process stability Preheated rotary kilns reduce the risk of ring formation by controlling temperature (kiln temperature fluctuation ≤ ±15℃), while processes without preheating are more prone to ring formation due to temperature variations. Large temperature gradients can easily lead to ring formation on the kiln body.

[0044] Process Analysis: ① Slow, gradual heating prevents cracking and pore formation. Without preheating: When room temperature ore is directly injected into a high-temperature zone above 900℃, manganese carbonate decomposes instantly and violently. CO2 rushes in rapidly, micropores collapse directly, interconnecting pores are destroyed, local instantaneous sintering occurs, and a hard shell forms on the surface, resulting in a significant decrease in activity.

[0045] With preheating: The temperature is gradually increased in the preheating section to remove free water and crystal water first, and then CO2 is slowly decomposed to gradually generate the pore structure and preserve the complete honeycomb mesopores. The porosity and specific surface area are higher, and the activity is naturally higher.

[0046] ② Remove moisture and volatile substances in advance to prevent internal pressure and clumping. No preheating: Wet material and attached water directly enter the high-temperature zone, causing internal water vapor to instantly vaporize and pressurize, resulting in bubbling, caking, and localized granulation. It melts and clumps together, resulting in poor air permeability and partial overheating.

[0047] With preheating: The preheating section thoroughly removes moisture, adsorbed gas, and light volatiles, so that the material is dry and structurally stable before entering the high-temperature roasting section, without bubbling, clumping, or hardening.

[0048] ③ The temperature field is uniform, with no local under-burning or local over-burning. Rotary kiln without preheating: When cold material is fed into the kiln, the kiln temperature fluctuates greatly, resulting in some areas not being fully burned and others being over-burned, leading to inconsistent product activity.

[0049] Preheating: The material is preheated before entering the high-temperature roasting zone, resulting in uniform overall material temperature and synchronous decomposition, with almost no over-burning or under-burning, and extremely stable batch quality.

[0050] ④ The phase transition is mild, and the proportion of easily reducible active phase is high. Rapid burning without preheating: Local overheating easily leads to the formation of stable and difficult-to-reducible crystalline phases, complete Mn3O4, with regular lattice passivation, making it difficult to reduce during smelting.

[0051] Preheating and slow burning: The phases transform gradually, mainly consisting of highly active MnO and low manganese oxides. There are many crystal defects and reactive sites, resulting in faster smelting and reduction and lower energy consumption.

[0052] ⑤ Good particle integrity, no pulverization, and better particle size distribution. Sudden heating without preheating: The thermal stress is enormous, the particles crack and pulverize, there is a lot of fine powder, and the air permeability in the furnace is poor.

[0053] Preheating gradient heating: thermal stress is released gradually, particles do not crack, have complete morphology, and reasonable particle size distribution. After roasting, they do not pulverize or form hard lumps, and the permeability of the smelting material layer is better.

[0054] ⑥ Effectively avoid the defect of "irreversible overheating" Kilns without preheating are most prone to: instantaneous over-burning on the surface and under-burning inside; kilns with preheating maintain a uniform temperature rise and stable temperature throughout the process, strictly staying within the optimal activity range, without exceeding the temperature or time limit, thus eliminating over-burning at the source.

[0055] D. The reactions that occur during the roasting process determine the magnetism. ① Thermal decomposition of manganese carbonate (MnO): weakly magnetic, very weakly magnetic.

[0056] ② At high temperatures, it is oxidized by air (key point) and further oxidized to form Mn3O4 (manganese tetroxide) or Mn2O3; Mn3O4 (manganese tetroxide) has strong ferrimagnetism, almost the same as the magnetic principle of magnetite, and is the main source of the magnetism of manganese ore after roasting. The higher the temperature and the more complete the oxidation, the more Mn3O4 is generated, and the stronger the magnetism.

[0057] ③ Different roasting temperatures conform to the law of magnetic strength. Low temperature <750℃: Incomplete decomposition, less → very weak magnetism; Calcination at 800–860℃: Large amounts of Mn3O4 are generated → moderately strong magnetism; Calcination > 900℃: crystal recrystallization, more complete crystal phase → strongest magnetism.

[0058] Therefore, the calcination temperature of Embodiment 1 and Comparative Example 1 of the present invention is >900℃, which enhances the magnetism and facilitates magnetic separation.

[0059] Example 2 A process for smelting manganese-rich slag by magnetizing roasted manganese ore, with the same steps as in Example 1.

[0060] Comparative Example 3 A process for smelting manganese-rich slag by magnetizing roasting manganese ore, with the same steps as Comparative Example 1.

[0061] The chemical composition and properties of the low-grade manganese ore and roasted ore in Example 2 and Comparative Example 3 are shown in Table 3.

[0062] Table 3

[0063] The chemical composition of the manganese-rich slag in Example 2 and Comparative Example 3 is shown in Table 4.

[0064] Table 4

[0065] Analysis results of Examples 1 and 2 and Comparative Examples 1 and 3: Compared to the process without a preheater, under the same roasting process parameters, the roasting temperature is increased by 50-100℃, the roasting time is shortened by 40min to 1 hour, the roasted sand drum strength parameters are 58% to 62%, and the pulverization rate is 5%; the sintering process requires crushing, the drum strength is 60% to 65%, and the pulverization rate is 8%; the roasted sand drum strength in the rotary kiln process without preheating is 45% to 55%, and the pulverization rate is 6%.

[0066] Compared to the process without a preheater, the probability of ring formation in the high-temperature section of the rotary kiln is reduced by 50%. Ring formation is related to the particle size and powder ratio of the material, the calcination temperature, the refractory material, and the ring treatment method (which can be done without stopping the kiln).

[0067] Analysis of the above examples shows that the chemical activity (subsequent reduction and leaching rates and reaction time) and physical activity (pore structure and porosity, surface roughness, and wide particle size distribution) of the roasted sand produced by the rotary kiln roasting process are superior to those of sintered ore.

[0068] Quality and cost analysis: Compared with direct-fired kilns without preheating, rotary kilns with preheating produce better quality roasted sand and have lower costs.

[0069] Table 5 shows a quantitative comparison of the costs and indicators of Example 1 and Comparative Example 1. Table 5

[0070] To further demonstrate the low cost of using a preheated rotary kiln, ores with different manganese grades were processed, and the smelting costs at different loss on ignition were recorded: Calculation of basic conditions: Smelting process: Blast furnace smelting of manganese-rich slag Coke price: 1900 yuan / ton Industrial electricity price: 0.55 yuan / kWh Benchmark Comparison: Using manganese ore with 14% manganese content and 2% loss on ignition as the cost benchmark. Calculation scope: Only blast furnace smelting and processing costs are calculated (excluding the original purchase price of ore). Costs are shown in Table 6: Table 6

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for smelting manganese-rich slag from magnetized roasted manganese ore, characterized in that, Includes the following steps: (1) The manganese ore is fed into the preheater and the ore is preheated by the flue gas from the tail of the rotary kiln; the preheated ore is then directly fed into the rotary kiln. (2) The manganese ore is roasted in a rotary kiln; (3) After roasting, the manganese ore is continuously discharged from the rotary kiln into the cooler for cooling; (4) After cooling, the manganese ore is screened to obtain oversize lumps and undersize powder; Magnetic separation of the oversize material obtained from the screen yields gangue and iron-manganese ore. (5) The iron-manganese ore is mixed with coke and flux and then fed into a blast furnace for smelting to obtain liquid slag and molten iron. After slag formation, molten iron and manganese-rich slag are obtained.

2. The process for smelting manganese-rich slag from magnetized roasted manganese ore according to claim 1, characterized in that, The manganese content in the manganese ore in step (1) is ≤12%; the particle size of the manganese ore is 20-50mm.

3. The process for smelting manganese-rich slag from magnetized roasted manganese ore according to claim 1, characterized in that, The temperature of the kiln tail flue gas in step (1) is 500-550℃; the temperature of the preheated ore is 200℃~300℃.

4. The process for smelting manganese-rich slag from magnetized roasted manganese ore according to claim 1, characterized in that, In step (2), the rotary kiln speed is 0.2 to 1.85 rpm, and the fuel is blast furnace gas; the roasting temperature is 1150℃ to 1200℃, and the roasting time is 1.5h to 3h.

5. The process for smelting manganese-rich slag from magnetized roasted manganese ore according to claim 4, characterized in that, The blast furnace gas comprises the following components by volume fraction: CO 26%–32%, N2 55%–65%, CO2 8%–12%, H2 1.0%–3.0%, CH4 0.2%–0.8%, and O2 0.2%–0.5%.

6. The process for smelting manganese-rich slag from magnetized roasted manganese ore according to claim 1, characterized in that, The outlet temperature of the cooler in step (3) is ≤100℃.

7. The process for smelting manganese-rich slag from magnetized roasted manganese ore according to claim 1, characterized in that, The sieve aperture size in step (4) is 8~10mm.

8. The process for smelting manganese-rich slag from magnetized roasted manganese ore according to claim 1, characterized in that, In step (4), the magnetic separation intensity of the sieve block material is 8000~10000 Oersted, and the magnetic separation time is 5~20s.

9. The process for smelting manganese-rich slag from magnetized roasted manganese ore according to claim 1, characterized in that, In step (5), the mass ratio of the iron-manganese ore to coke and flux is 100:28-35:0-3, and the flux is limestone; the coke has more than 82% fixed carbon.

10. The process for smelting manganese-rich slag from magnetized roasted manganese ore according to claim 1, characterized in that, The smelting temperature in step (5) is 1250℃~1350℃.

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