A method for preparing manganese concentrate, iron concentrate and pyrolysis carbon by reducing iron-manganese ore with biomass

Abstract

This invention discloses a method for preparing manganese concentrate, iron concentrate, and pyrolytic char from iron-manganese ore by biomass roasting and reduction, belonging to the fields of mineral processing and environmental protection technology. The method includes the following steps: crushing, grinding, screening, and acid leaching the iron-manganese ore to obtain activated iron-manganese ore; drying, grinding, and sieving the biomass to obtain pretreated biomass powder; separately placing the activated iron-manganese ore and the pretreated biomass powder in the same sealed container and performing two-stage stepped roasting under a protective atmosphere; cooling, grinding, and magnetically separating the roasted iron-manganese ore to obtain manganese concentrate and iron concentrate; the roasted biomass is pyrolytic char. This invention utilizes a synergistic process system of "acid leaching activation pretreatment - two-stage stepped roasting - separate placement of reactants - biomass reduction," employing a reduction roasting method, and achieving high-grade manganese and iron concentrates through magnetic separation, with both manganese and iron yields reaching high levels.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing and environmental protection technology, and specifically relates to a method for preparing manganese concentrate, iron concentrate and pyrolytic carbon by biomass roasting and reducing iron-manganese ore. Background Technology

[0002] Manganese is an indispensable alloying element in steel production, significantly improving the hardness, ductility, toughness, and wear resistance of steel. Iron, on the other hand, is a fundamental raw material in the steel industry, widely used in steel manufacturing and alloy production. Iron-manganese ore, as an important associated mineral, is a major source of both iron and manganese. However, due to the similar chemical properties of iron and manganese, and the presence of isomorphous substitution and fine-grained embedding in the ore, efficient separation of the two is extremely difficult, becoming a long-standing technical bottleneck in the metallurgical field.

[0003] Currently, the development and utilization of iron-manganese ore mainly employs pyrometallurgical enrichment or hydrometallurgical processes. In pyrometallurgical processes, traditional reduction roasting relies heavily on fossil fuels such as coal and coke as reducing agents. This method has the following significant drawbacks: First, the direct contact between coal and ore easily leads to localized over-reduction, resulting in excessive depletion of iron and manganese or the formation of alloy phases that are difficult to separate. Furthermore, harmful impurities such as sulfur and phosphorus in the coal can easily enter the mineral lattice, reducing the quality of the concentrate. Second, uneven distribution of the reducing atmosphere and temperature field during roasting results in insufficient or excessive reduction of valuable metals, leading to low concentrate grade and recovery rate. Third, the large-scale use of fossil fuels is accompanied by high carbon emissions and the release of pollutants such as sulfur oxides and nitrogen oxides, which does not meet environmental protection requirements. Finally, coal prices are greatly affected by market fluctuations, and the low thermal energy utilization rate of traditional processes leads to persistently high production costs. Summary of the Invention

[0004] Based on the above-mentioned technical problems, this invention proposes a method for preparing manganese concentrate, iron concentrate and pyrolytic carbon by biomass roasting and reducing iron-manganese ore.

[0005] The technical solution adopted in this invention is: A method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore includes the following steps: (1) The iron-manganese ore is crushed, ground and screened to obtain pretreated iron-manganese ore; (2) The pretreated iron-manganese ore obtained in step (1) is added to an organic acid aqueous solution for stirring and acid leaching, followed by filtration, water washing and drying to obtain activated iron-manganese ore; (3) The biomass is dried, ground and sieved in sequence to obtain pretreated biomass powder; (4) The activated iron-manganese ore obtained in step (2) and the pretreated biomass powder obtained in step (3) are placed separately in the same sealed container and roasted in two stages under a protective atmosphere (nitrogen or argon atmosphere). (5) After cooling, grinding and magnetic separation of the roasted iron-manganese ore, manganese concentrate (product 1) and iron concentrate (product 2) are obtained; the roasted biomass is pyrolytic char (product 3).

[0006] Preferably, in step (1): the particle size of the pretreated iron-manganese ore is controlled at -150 mesh.

[0007] Preferably, in step (2): the organic acid is selected from one or more of citric acid, malic acid and acetic acid.

[0008] The above-mentioned organic acids were selected for the following reasons: First, organic acids can gently dissolve impurities, selectively strip the passivation film, and do not damage the main mineral lattice; second, organic acid anions have a complexing effect, which can assist in surface modification and promote subsequent reduction.

[0009] Preferably, in step (2): the concentration of the organic acid aqueous solution is 0.1~0.2 mol / L, and the ratio of the amount of pretreated iron-manganese ore to the organic acid aqueous solution is 1g:10~20mL.

[0010] Preferably, in step (3): the drying temperature is 70~105℃ and the time is 3~24h; the moisture content of the biomass after drying is less than 5%; the sieve size in the sieving process is 150~325 mesh.

[0011] Preferably, in step (4): the mass ratio of the activated iron-manganese ore to the pretreated biomass powder is 1~2:1~5.

[0012] Preferably, the two-stage stepped roasting in step (4) specifically includes the following steps: first, heating to 200-350℃ at 5-10℃ / min and holding at that temperature for 60-90min; then heating to 600-800℃ at 5-15℃ / min and holding at that temperature for 30-90min.

[0013] In the two-stage roasting process described above, the first stage of low-temperature roasting removes adsorbed water and some oxygen-containing functional groups from the biochar under an inert atmosphere, completing preliminary deoxygenation and preventing the char body from cracking due to rapid vaporization of moisture in the subsequent high-temperature stage. Simultaneously, it lowers the initial O / C ratio of the carbonaceous matrix, ensuring a stable reducing atmosphere during the 600-800℃ high-temperature reduction stage. This step improves the reduction efficiency of the iron-manganese ore and ensures the regularity of the pyrolysis char product structure. Furthermore, after the completion of the first stage of low-temperature roasting, the small amount of water vapor, CO2, and other gases generated in this stage are discharged with the protective gas (nitrogen or argon), providing a stable reducing atmosphere for the subsequent high-temperature roasting reduction.

[0014] Preferably, in step (4): during the roasting process, biomass undergoes pyrolysis to produce H2, CO, and C. x H x Reducing gas and pyrolytic carbon; the reducing gas converts MnO2 and Mn2O3 in iron-manganese ore into MnO, and converts Fe2O3 and FeO(OH) in iron-manganese ore into Fe3O4 and γ-Fe2O3; the pyrolytic carbon is used as an adsorbent, soil conditioner or catalyst carrier.

[0015] C x H x This typically refers to low-carbon hydrocarbons, primarily methane (CH4), and may also include small amounts of ethylene (C2H4), propylene (C3H6), etc.

[0016] Preferably, the magnetic separation in step (4) specifically includes the following steps: after the roasted material is cooled and ground to dissociate, the manganese component and the iron component obtained by roasting and reduction are separated by a weak magnetic field magnetic separation to obtain manganese concentrate and iron concentrate respectively.

[0017] Preferably, in step (5), the iron-manganese ore is cooled to below 60°C in an inert atmosphere to prevent it from oxidizing after contact with air at high temperatures.

[0018] Preferably, the biomass is selected from lignocellulosic biomass, starch biomass, or a combination thereof; more preferably, the biomass is selected from one or more of sawdust, peanut shells, straw, fruit shells, and corn starch.

[0019] The main reactions involved in the roasting of iron-manganese ore and biomass powder under a protective atmosphere in this invention are as follows: Biomass → Pyrolysis char (adsorbent, catalyst, etc.) + CO, H2, C x H x Reducing gases; Fe2O3 / FeO(OH) (weakly magnetic) + CO, H2, C x H xReducing gases → Fe3O4 / γ-Fe2O3 (strongly magnetic) + CO2 + H2O; MnO2 / Mn2O3 (weakly magnetic) + CO, H2, C x H x Reducing gases → MnO (weakly magnetic) + CO2 + H2O; In the roasting process under a protective atmosphere, biomass undergoes pyrolysis at high temperatures to produce H2, CO, and C. x H x Under a reducing atmosphere, gases with reducing properties transform weakly magnetic iron minerals in iron-manganese ore into strongly magnetic iron minerals, while the manganese minerals retain their weak magnetism after transformation. Simultaneously, when biomass is heated under a protective atmosphere, its complex organic polymer structure undergoes bond breaking and recombination, forming carbon-rich solid residues, i.e., pyrolysis char.

[0020] After the iron-manganese ore is reduced and roasted using biomass, the manganese and iron minerals are then separated by weak magnetic separation.

[0021] The beneficial technical effects of the present invention are as follows: This invention successfully solves the problems of low iron and manganese recovery and concentrate depletion in traditional pyrometallurgical processes through a synergistic process system of "acid leaching activation pretreatment - two-stage stepped roasting - separate placement of reactants - biomass reduction". Specifically: (1) The present invention innovatively adopts the strategy of "separate placement of reactants + two-stage stepped roasting" to precisely control the reduction process and avoid excessive reduction and sintering. Separate placement of reactants avoids excessive carbonization and carbon encapsulation caused by direct contact between biochar and minerals, effectively preventing the pollution of manganese, iron concentrate and pyrolysis char products by biomass ash, and ensuring the purity and performance of each product. At the same time, in the two-stage stepped roasting, the initial deoxygenation is completed by low-temperature roasting. This step not only ensures the regularity of the structure of pyrolysis char products, but also provides a stable reducing atmosphere for the high-temperature roasting in the second stage, further improving the reduction efficiency of iron and manganese ore.

[0022] (2) The present invention introduces an acid leaching activation step before roasting. This pretreatment method can effectively dissolve and peel off the passivation film and impurities on the surface of the iron-manganese ore powder, exposing more highly active reaction sites. This can improve the uniformity and sufficiency of the reaction between the reducing gas and the active components in the iron-manganese ore, thereby further improving the grade and recovery rate of the product. It can be seen that acid leaching activation is a key prerequisite for the high performance of this process.

[0023] (3) The present invention can affect the efficiency of the reduction reaction and the quality of the product by adjusting the temperature. It utilizes the reducing gas generated during the roasting of biomass to reduce manganese and iron in iron-manganese ore. It can obtain pyrolysis char products without the need for an external carbon source, achieving two goals at once. Pyrolysis char can be widely used as an adsorbent, catalyst, soil conditioner or remediation agent and chemical carrier, etc.

[0024] (4) The process flow of the present invention includes steps such as raw material preparation, reduction reaction and magnetic separation. The process is simple, easy to operate and easy to industrialize. The temperature of the reduction reaction stage is controlled within a reasonable range, which ensures the efficient progress of the reduction reaction, while reducing the complexity of equipment and the difficulty of operation. It has significant industrial promotion value and application prospects.

[0025] (5) The present invention uses biomass roasting to generate reducing gas, without the need for an external carbon source. Biomass is widely available and low in cost. It is mainly composed of components such as cellulose, hemicellulose and lignin, and has a high carbon content, making it a high-quality potential reducing agent. Currently, a large amount of biomass waste has not been fully utilized, which has caused resource waste and environmental pollution problems. Using it in the reduction process of iron and manganese ore can not only help reduce production costs, but also realize the high-value utilization of agricultural waste and reduce environmental pressure. Attached Figure Description

[0026] Figure 1 This is a flowchart of the method for preparing manganese concentrate, iron concentrate and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to the present invention. Detailed Implementation

[0027] This invention proposes a method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore, such as... Figure 1As shown, the method is carried out according to the following steps: crushing, grinding, and screening the iron-manganese ore to obtain a suitable particle size; adding the pretreated iron-manganese ore powder to an organic acid aqueous solution for stirring and acid leaching, followed by filtration, washing, and drying to obtain activated iron-manganese ore; sequentially drying, grinding, and sieving the biomass to obtain pretreated biomass powder; placing the activated iron-manganese ore and biomass powder separately in a certain mass ratio and placing them together in a roasting furnace; subjecting the separately placed iron-manganese ore and biomass powder to two-stage step roasting under a protective atmosphere; cooling after roasting, then grinding the iron-manganese ore and separating it by magnetic separation to obtain manganese concentrate (product 1) and iron concentrate (product 2); simultaneously, pyrolytic carbon (product 3) is obtained in the container holding the biomass powder. This invention creatively combines "acid leaching activation pretreatment - two-stage stepped roasting - separate placement of reactants - biomass reduction," using biomass as a reducing raw material. It efficiently utilizes the reducing gases generated during biomass roasting to reduce manganese and iron minerals in iron-manganese ore without the need for an external carbon source. Furthermore, the reduced iron and manganese minerals can be separated by weak magnetic separation. Simultaneously, biomass pyrolysis char is obtained in situ. This invention features a simple process, low cost, and is suitable for widespread application.

[0028] The present invention will be further described below with reference to specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means.

[0029] Example 1 (1) Grind the raw iron-manganese ore with a TMn grade of 33.22% and a TFe grade of 21.15% to a particle size of -200 mesh.

[0030] (2) The above-ground iron-manganese ore powder is added to a 0.2mol / L citric acid aqueous solution at a solid-liquid ratio of 1:10 (g / mL). The mixture is stirred and acid-leached at room temperature for 30 min. Then the slurry is transferred to a Buchner funnel, and a circulating water vacuum pump is turned on to filter until no obvious droplets seep out. The mixture is washed with deionized water and filtered until the filtrate is neutral. The filter cake is dried in a forced-air dryer at 80℃ for 4-6 h. Then it is gently ground to obtain activated iron-manganese ore powder with a particle size of -200 mesh.

[0031] (3) Dry the peanut shells (biomass) until the moisture content is less than 5% and crush them to a particle size of -150 mesh.

[0032] (4) Weigh the activated iron-manganese ore powder and peanut shell powder at a mass ratio of 1:1 and place them in different ceramic boats. Then place them in a roasting furnace for two-stage step roasting under a nitrogen atmosphere: first, set the heating rate of the roasting furnace to 8℃ / min, heat to 250℃ and keep at this temperature for 60min to remove water from the biochar and preliminarily complete the deoxygenation of the carbonaceous matrix; then set the heating rate to 10℃ / min, heat to 700℃ and carry out the reduction reaction at this temperature for 60min.

[0033] (5) After roasting and cooling to room temperature, grind the roasted product (which needs to be cooled to below 60°C in an inert atmosphere to prevent oxidation upon contact with air at high temperatures) and separate the manganese concentrate and iron concentrate using a weak magnetic separation method. The residual carbon in the container holding the peanut shell powder is the pyrolysis carbon. This pyrolysis carbon can be used as an adsorbent for heavy metal ions Pb. 2+ The adsorption removal rate was 89.84%.

[0034] Example 2 (1) Grind the raw iron-manganese ore with a TMn grade of 20.89% and a TFe grade of 34.56% to a particle size of -150 mesh.

[0035] (2) The above-ground iron-manganese ore powder is added to a 0.2mol / L acetic acid aqueous solution at a solid-liquid ratio of 1:15 (g / mL). The mixture is stirred and acid-leached at room temperature for 30 min. Then the slurry is transferred to a Buchner funnel, and a circulating water vacuum pump is turned on to filter until no obvious droplets seep out. The mixture is washed with deionized water and filtered until the filtrate is neutral. The filter cake is dried in a forced-air dryer at 80℃ for 4-6 h. The activated iron-manganese ore powder with a particle size of -150 mesh is obtained by gently grinding.

[0036] (3) Dry the wood chips (biomass) to a moisture content of less than 4% and crush them to a particle size of -200 mesh.

[0037] (4) Weigh the activated iron-manganese ore and wood powder at a mass ratio of 1:2 and place them in different ceramic boats. Then place them in a roasting furnace for two-stage step roasting under a nitrogen atmosphere: first, set the heating rate of the roasting furnace to 8℃ / min, heat to 250℃ and hold at this temperature for 60min to remove water from the biochar and preliminarily complete the deoxygenation of the carbonaceous matrix; then set the heating rate to 5℃ / min, heat to 750℃ and carry out the reduction reaction at this temperature for 90min.

[0038] (5) After roasting and cooling to room temperature, grind the roasted product (which needs to be cooled to below 60°C in an inert atmosphere to avoid oxidation after contact with air at high temperatures) and separate the manganese concentrate and iron concentrate using a weak magnetic separation method. The residual char in the container holding the sawdust powder is the pyrolysis char. This pyrolysis char can be used as a soil conditioner. When mixed into the soil, it can reduce soil acidity and improve its water and fertilizer retention capacity.

[0039] Example 3 (1) Grind the raw iron-manganese ore with a TMn grade of 17.78% and a TFe grade of 41.56% to a particle size of -200 mesh.

[0040] (2) The above-ground iron-manganese ore powder is added to a 0.2mol / L malic acid aqueous solution at a solid-liquid ratio of 1:10 (g / mL). The mixture is stirred and acid-leached at room temperature for 30 min. Then the slurry is transferred to a Buchner funnel, and a circulating water vacuum pump is turned on to filter until no obvious droplets seep out. The mixture is washed with deionized water and filtered until the filtrate is neutral. The filter cake is dried in a forced-air dryer at 80℃ for 4-6 h and then gently ground to obtain activated iron-manganese ore powder with a particle size of -200 mesh.

[0041] (3) Dry the corn starch (biomass) to a moisture content of less than 4% and crush it to a particle size of -200 mesh.

[0042] (4) Weigh the activated iron-manganese ore and corn starch at a mass ratio of 2:1 and place them in different ceramic boats. Then place them in a roasting furnace for two-stage step roasting under a nitrogen atmosphere: first, set the heating rate of the roasting furnace to 8℃ / min, heat to 250℃ and keep at this temperature for 60min to remove water from the biochar and preliminarily complete the deoxygenation of the carbonaceous matrix; then set the heating rate to 15℃ / min, heat to 700℃ and carry out the reduction reaction at this temperature for 60min.

[0043] (5) After roasting and cooling to room temperature, grind the roasted product (which needs to be cooled to below 60°C in an inert atmosphere to prevent oxidation upon contact with air at high temperatures) and separate the manganese concentrate and iron concentrate using a weak magnetic separation method. The residual carbon in the container holding the corn starch is the pyrolysis carbon. This pyrolysis carbon has a high specific surface area, rich pore structure and good thermal stability, and can effectively load and disperse catalytically active substances such as metals, and can be used as a catalyst carrier.

[0044] Comparative Example 1 The preparation steps are the same as in Example 1. The difference is that the activation step (2) is not performed.

[0045] Comparative Example 2 The preparation steps are the same as in Example 2. The difference is that the two-stage stepped calcination in step (4) is replaced with a single-stage constant temperature calcination: the heating rate of the calcination furnace is set to 10℃ / min, heated to 750℃, and the reduction reaction is calcined at this temperature for 90min.

[0046] Comparative Example 3 The preparation steps are the same as in Example 3. The difference is that in step (4), the activated iron-manganese ore is uniformly mixed with corn starch and then subjected to two-stage step roasting.

[0047] Table 1 shows the indicators of the products obtained in Examples 1-3 and Comparative Examples 1-3, including the manganese grade and recovery rate of manganese concentrate, and the iron grade and recovery rate of iron concentrate.

[0048] Table 1. Results of manganese grade and recovery rate of manganese concentrate and iron grade and recovery rate of iron concentrate.

[0049] The data in Table 1 show that the grade and yield of the products obtained in Examples 1-3 are significantly improved based on the grade of the raw ore, which fully verifies the feasibility and advanced nature of the synergistic process system of "acid leaching activation pretreatment - two-stage step roasting - separate placement of reactants - biomass reduction".

[0050] Compared to Example 1, Comparative Example 1 omitted the acid leaching activation treatment in step (2), resulting in the failure to effectively remove the passivation film on the surface of the iron-manganese ore powder. During subsequent roasting, this hindered the sufficient contact between the reducing gas and the active mineral components (such as MnO2, Mn2O3, Fe2O3, FeO(OH)), leading to incomplete reduction reaction and ultimately a significant decrease in the manganese / iron grade and recovery rate of the resulting product.

[0051] Compared with Example 2, Comparative Example 2 changed the two-stage stepped roasting in step (4) to a single-stage isothermal roasting, which resulted in a significant decrease in the manganese / iron grade and recovery rate of the obtained product. The main reason is that the single-stage isothermal roasting cannot remove the moisture in the biochar and complete the deoxidation treatment of the carbonaceous matrix in the low-temperature stage, which makes it easy for the iron and manganese minerals to be over-sintered or the reduction kinetics to be limited and the reduction insufficient in the high-temperature reduction stage, ultimately affecting the effective enrichment of metals and the efficiency of magnetic separation.

[0052] Compared to Example 3, Comparative Example 3, which uniformly mixed activated iron-manganese ore with corn starch before roasting, showed a significant decrease in both the manganese / iron grade and yield of the resulting product. The main reasons are as follows: Firstly, the direct contact between biochar and iron-manganese ore during heating easily leads to localized over-reduction, and the generated carbon readily forms an amorphous carbon coating on the mineral particles, severely hindering the effective identification and separation of magnetic particles during subsequent weak magnetic separation, resulting in the loss of valuable metals. Secondly, the ash generated during biomass pyrolysis migrates and mixes with the iron-manganese mineral phase during roasting, causing mineral lattice contamination, which not only reduces the concentrate grade but also further deteriorates the magnetic separation effect.

[0053] In Examples 1-3, activated iron-manganese ore and biomass were placed separately in the same sealed container for roasting. The CO, H2, and low-carbon hydrocarbon reducing gases generated by biomass pyrolysis acted on the iron-manganese ore in the gas phase, achieving gas-solid reduction roasting. On the one hand, this avoided excessive reduction and amorphous carbon coating caused by direct contact between solid carbon and iron-manganese ore, controlled the valence state of iron and manganese, and obtained roasted ore mainly composed of strongly magnetic Fe3O4 / γ-Fe2O3 and active manganese oxides, thus improving the efficiency of subsequent magnetic separation and the grade of manganese and iron concentrates. On the other hand, it reduced the doping and contamination of biomass ash into the iron-manganese mineral phase, and the resulting pyrolysis carbon had higher purity.

[0054] For any parts not mentioned in the above embodiments, existing technologies can be adopted or referenced.

[0055] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above embodiments. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore, characterized in that, Includes the following steps: (1) The iron-manganese ore is crushed, ground and screened to obtain pretreated iron-manganese ore; (2) The pretreated iron-manganese ore obtained in step (1) is added to an organic acid aqueous solution for stirring and acid leaching, followed by filtration, water washing and drying to obtain activated iron-manganese ore; (3) The biomass is dried, ground and sieved in sequence to obtain pretreated biomass powder; (4) The activated iron-manganese ore obtained in step (2) and the pretreated biomass powder obtained in step (3) are placed separately in the same sealed container and roasted in two stages under a protective atmosphere. (5) After cooling, grinding and magnetic separation of the roasted iron-manganese ore, manganese concentrate and iron concentrate are obtained; the roasted biomass is pyrolytic carbon.

2. The method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to claim 1, characterized in that, In step (1): the particle size of the pretreated iron-manganese ore is controlled at -150 mesh.

3. The method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to claim 1, characterized in that, In step (2): the organic acid is selected from one or more of citric acid, malic acid and acetic acid.

4. The method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to claim 1, characterized in that, In step (2): the concentration of the organic acid aqueous solution is 0.1~0.2 mol / L, and the ratio of the amount of pretreated iron-manganese ore to the organic acid aqueous solution is 1g:10~20mL.

5. The method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to claim 1, characterized in that, In step (3): the drying temperature is 70~105℃ and the time is 3~24h; after the biomass is dried, the moisture content is less than 5%; the sieve size in the sieving process is 150~325 mesh.

6. The method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to claim 1, characterized in that, In step (4): the mass ratio of the activated iron-manganese ore to the pretreated biomass powder is 1~2:1~5.

7. The method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to claim 1, characterized in that, The two-stage calcination in step (4) specifically includes the following steps: first, raise the temperature to 200-350℃ at 5-10℃ / min and hold at that temperature for 60-90min; then raise the temperature to 600-800℃ at 5-15℃ / min and hold at that temperature for 30-90min.

8. The method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to claim 1, characterized in that, In step (4): During the roasting process, biomass undergoes pyrolysis to produce H2, CO, and C. x H x Reducing gas and pyrolytic carbon; the reducing gas converts MnO2 and Mn2O3 in iron-manganese ore into MnO, and converts Fe2O3 and FeO(OH) in iron-manganese ore into Fe3O4 and γ-Fe2O3; the pyrolytic carbon is used as an adsorbent, soil conditioner or catalyst carrier.

9. The method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to claim 8, characterized in that, The magnetic separation in step (4) specifically includes the following steps: After the roasted material is cooled and ground, the manganese and iron components obtained by roasting and reduction are separated by a weak magnetic field to achieve manganese-iron separation, thereby obtaining manganese concentrate and iron concentrate respectively.

10. The method for preparing manganese concentrate, iron concentrate, and pyrolytic carbon by biomass roasting and reducing iron-manganese ore according to claim 1, characterized in that, The biomass is selected from lignocellulose biomass, starch biomass, or combinations thereof.

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