Synchronous reduction roasting-selective oxidation-magnetic separation treatment method for refractory ferromanganese ore

Abstract

The invention provides a synchronous reduction roasting-selective oxidation-magnetic separation treatment method for refractory ferromanganese ore, and belongs to the technical field of refractory ferromanganese ore beneficiation processes. The method comprises the following steps: (1) feeding and grinding; (2) drying and scattering; (3) fluidized synchronous reduction roasting; (4) cooling and selective oxidation; and (5) carrying out efficient magnetic separation to obtain an iron ore concentrate product and a manganese concentrate product. According to the method, the synchronous reduction roasting of introducing air first and then introducing H2 in the reduction stage and the selective oxidation technology of introducing air in the cooling stage are adopted, so that the refractory ferromanganese ore realizes phase precise regulation and control in the synchronous reduction and cooling oxidation process, and meanwhile, the method is a green low-carbon production process for preparing iron ore concentrate and manganese concentrate, and the method is suitable for industrial production. And the method is more efficient, clean and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory iron-manganese ore dressing process, and specifically relates to a refractory iron-manganese ore synchronous reduction roasting-selective oxidation-magnetic separation treatment method. Background Art

[0002] Iron and manganese are important basic raw materials in industrial production and are also national strategic reserve resources. Manganese plays an important role in steel production. As a key alloying element, desulfurizer and deoxidizer, more than 90% of its annual output is used in the steel industry. The rest of it is used in fields such as dry batteries, chemical products and electronic materials, which is crucial to the development of the national economy. At present, manganese oxide, manganese carbonate and manganese sulfide ores are mainly used in industry. With the rapid growth of China's demand for manganese, the reserves of rich manganese ores have dropped sharply (TMn>35wt%). Iron-containing manganese ore is a poor manganese ore containing both iron and manganese. Its iron content is generally between 10% and 40%, while the manganese content is relatively low, usually between 10% and 20%. Effective use of iron-containing manganese ore can simultaneously obtain iron concentrate and manganese concentrate, which is of great significance for alleviating the contradiction between supply and demand of iron and manganese resources and realizing efficient and clean utilization of resources.

[0003] Iron-containing manganese ore has the characteristics of high gangue content, complex ore composition and mineral phase structure, so it is difficult for traditional mineral processing methods to obtain good technical and economic effects. At present, the treatment of manganese ore mainly includes traditional mineral processing, chemical mineral processing, carbon thermal reduction, microwave reduction, etc. These methods can improve the separation index, but the mineral processing efficiency is low, the process conditions are complex, and the harm to the environment is great. Studies have shown that a hydrogen-based mineral phase transformation technology based on fluidized roasting has the characteristics of uniform heating, high reduction rate, and environmental protection. This process uses clean energy hydrogen as a reducing agent to reduce weakly magnetic minerals to strongly magnetic minerals in a suspended state, and then separate them through subsequent magnetic separation. The cooling process of high-temperature roasting products has an important influence on process indicators. The current industrial cooling method is mainly water seal cooling, but this method not only produces a lot of dust but also has a low efficiency in recovering waste heat, and its application is limited in arid areas. In contrast, air cooling has advantages in environmental protection and energy saving. The study found that when the roasted product of iron-manganese ore is cooled in air, the generated magnetite (Fe3O4) will be oxidized into magnetic hematite (γ-Fe2O3). This behavior can effectively reduce the magnetic agglomeration phenomenon and make the separation of manganese and iron more efficient. Summary of the invention

[0004] In view of the problems existing in the prior art in processing refractory ferromanganese ore, the present invention adopts a synchronous reduction roasting technology of first passing air and then passing H2 in the reduction stage and a selective oxidation technology of passing air in the cooling stage, so that the refractory ferromanganese ore can achieve precise control of the physical phases in the dehydration, synchronous reduction and cooling oxidation processes.

[0005] The present invention provides a method for treating refractory iron and manganese ore by synchronous reduction roasting-selective oxidation-magnetic separation, comprising the following steps:

[0006] (1) Ore feeding and grinding operation:

[0007] Crushing and grinding the refractory iron-manganese ore into powder ore;

[0008] (2) Drying and breaking up:

[0009] Dry, break up and dehydrate the powder ore in air atmosphere;

[0010] (3) Fluidized synchronous reduction roasting:

[0011] First, the powder ore is preheated, roasted and dehydrated in air, and then suspended magnetized roasted in a mixed atmosphere of H2 and N2. The reduction reaction conditions are controlled, and the hematite (α-Fe2O3) and pyrolusite (MnO2) in the powder ore are synchronously reduced and precisely converted to obtain magnetite (Fe3O4) and harzburgite (MnO) reduction products;

[0012] (4) Cooling selective oxidation:

[0013] The reduction product is first cooled down in N2 and then air-cooled to control the oxidation time, so that magnetite (Fe3O4) is selectively oxidized and accurately converted to obtain hematite (γ-Fe2O3). After the oxidation is completed, N2 is introduced to cool it to room temperature to obtain a cooling product.

[0014] (5) High efficiency magnetic separation:

[0015] The cooled product is further finely ground and subjected to efficient magnetic separation by magnetic separation equipment to obtain iron concentrate products and manganese concentrate products.

[0016] Furthermore, in the refractory iron-manganese ore of step (1), the TFe grade is 35.36%-45.54%, and the TMn grade is 11.20%-19.77%.

[0017] Furthermore, in step (1), the refractory iron-manganese ore is ground to a particle size of -0.074 mm or more by a ball mill.

[0018] Furthermore, the chemical reaction principle of step (3) is as follows:

[0019] 3α-Fe2O3(s)+H2(g)=2Fe3O4(s)+H2O(g)

[0020] 2MnO2(s)+H2(g)=Mn2O3(s)+H2O(g)

[0021] 3Mn2O3(s)+H2(g)=2Mn3O4(s)+H2O(g)

[0022] Mn3O4(s)+H2(g)=3MnO(s)+H2O(g)

[0023] Furthermore, in step (3), the temperature of the powder ore preheating roasting is 200°C-450°C, and the time is 1 min-3 min.

[0024] Furthermore, the reduction reaction temperature of step (3) is 500°C-700°C, the volume concentration of H2 in the H2 and N2 mixed gas is 10%-40%, and the reaction time is 15min-60min.

[0025] Furthermore, the chemical reaction principle of step (4) is as follows:

[0026] 4Fe3O4(s)+O2(g)=6γ-Fe2O3(s)

[0027] Furthermore, the reduction product of step (4) is cooled to 100°C-300°C under N2, and the air cooling oxidation time is 5min-10min.

[0028] Furthermore, the cooled product of step (5) is further crushed by a ball mill until it is completely dissociated.

[0029] Furthermore, the high-efficiency magnetic separation equipment in step (5) is a weak magnetic separator with a magnetic field strength of 1000Oe-1300Oe.

[0030] Furthermore, the TFe recovery rate is 80.81%-98.17%, and the TMn recovery rate is 81.47%-91.38%.

[0031] The invention discloses an application of a fluidized synchronous reduction calcination-selective oxidation-high-efficiency magnetic separation treatment method for refractory iron-manganese ore, which is used for separating iron concentrate products and manganese concentrate products from refractory iron-manganese ore, wherein the Fe grade of the iron concentrate product is greater than 55%, and the Mn grade of the manganese concentrate product is greater than 30%.

[0032] In the cooling stage of the present invention, air is used to selectively oxidize the reduction products, wherein a small amount of harzburgite (MnO) is oxidized to hausmannite (Mn3O4) and fusogenite (Mn2O3). The chemical reaction principle is as follows:

[0033] 6MnO(s)+O2(g)=2Mn3O4(s)

[0034] 4Mn3O4(s)+O2(g)=6Mn2O3(s)

[0035] Advantages and effects of the present invention:

[0036] 1. Using H2 as reducing gas to treat refractory iron-manganese ore is a green and low-carbon production method for preparing iron concentrate products and manganese concentrate products from refractory iron-manganese ore; compared with traditional hydrometallurgical reduction and pyrometallurgical processes, the reduction reaction involved in this invention does not produce greenhouse gases, so this technology has significant results in low-carbon emission reduction;

[0037] 2. The present invention uses air cooling in the cooling stage, which can efficiently recover waste heat, save water resources, and reduce dust generated by cooling compared to water cooling; compared to nitrogen cooling, air cooling can accurately control the phase transformation to further optimize the subsequent sorting index, and the mineral structure is looser after air cooling, which can further reduce the subsequent grinding energy consumption;

[0038] 3. The present invention innovatively introduces fluidized roasting technology into the roasting process of refractory iron-manganese ore, realizing accurate control of roasting atmosphere and roasting temperature. Compared with other processes, the fluidized roasting process has high thermal efficiency, low energy consumption, and significantly reduced natural gas consumption. The required amount of air and the amount of flue gas generated are both small, and the flue gas temperature is low, which has a significant effect in reducing carbon emissions;

[0039] 4. The present invention adopts the technology of synchronous reduction roasting in which air is first passed and then H2 is passed in the reduction stage, and the selective oxidation technology of passing air in the cooling stage, so that the difficult-to-select iron-manganese ore can achieve precise control of the physical phases in the synchronous reduction and cooling oxidation processes; the precise conversion of magnetite (Fe3O4) and hematite (γ-Fe2O3) can further optimize the subsequent magnetic separation indicators, and the hematite formed in the cooling stage has strong magnetism and little residual magnetism, which can reduce magnetic agglomeration and reduce the inclusion of gangue minerals, making the magnetic separation more efficient; the precise conversion of harzburgite (MnO) can reduce the formation of high-valent manganese oxides and reduce the impact on subsequent manganese mineral leaching; this treatment method is more efficient, clean, green and environmentally friendly on the basis of further optimizing the separation indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the fluidized synchronous reduction roasting-selective oxidation-high-efficiency magnetic separation treatment method for refractory iron and manganese ore of the present invention. DETAILED DESCRIPTION

[0041] The following is a clear and complete description of the technical solutions in the implementation of the present invention in conjunction with the embodiments and the accompanying drawings. It should be noted that the embodiments described in the present invention are only used to further explain and illustrate, rather than to limit the scope of application. Based on the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the protection scope of the present invention.

[0042] like Figure 1As shown, the present invention is a method for synchronous reduction roasting-selective oxidation-magnetic separation of refractory iron-manganese ore. The method is carried out in the following four stages. The first stage is the ore processing stage: the refractory iron-manganese ore is ground, dried and dispersed; the second stage is the fluidized synchronous reduction stage: the powder ore is first preheated under air to remove adsorbed water, and then hematite and pyrolusite are synchronously reduced under a mixture of H2 and N2, so that hematite (α-Fe2O3) is accurately converted into magnetite (Fe3O4) and pyrolusite (MnO2) is accurately converted into manganese ore (MnO); the third stage is cooling and selective oxidation. Stage: The reduction product is first cooled by N2 and then cooled by air in a timely manner. The newly formed magnetite (Fe3O4) will be oxidized to hematite (γ-Fe2O3); the fourth stage is the high-efficiency magnetic separation stage: grinding magnetism-high-efficiency separation, the cooling product is further finely ground to complete dissociation, and iron concentrate and manganese concentrate products are produced through magnetic separation; this treatment method realizes the precise regulation of the mineral phases in the dehydration, reduction and selective oxidation processes of the difficult-to-select ferromanganese ore by step-by-step introduction of the system atmosphere (air, H2, N2 and air), and has the advantages of low energy consumption, high resource utilization, recoverable waste heat and water saving, and realizes the purpose of efficient and green recovery of iron and manganese resources from difficult-to-select ferromanganese ore.

[0043] A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation is adopted in the following embodiments. A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation comprises the following steps:

[0044] (1) Ore feeding and grinding: feed the raw ore into the ball mill and grind it to the feed particle size;

[0045] (2) Drying and dispersing: The iron-manganese ore grinding products are first dried in the drying and dispersing machine to remove the moisture in the materials. Then the dried materials are dispersed and discharged by the dispersing device set at the discharge port;

[0046] (3) Fluidized synchronous reduction roasting: the dispersed materials enter the ore phase conversion roasting furnace of the reduction roasting system; the powder preheating temperature is controlled at 200°C-450°C, the atmosphere is air, and the time is 1min-3min; the temperature in the ore phase conversion roasting furnace is controlled at 500°C-700°C, and a mixture of H2 and N2 is introduced. The iron-manganese ore materials in the furnace cavity are fluidized under the action of the bottom airflow; the volume concentration of the reducing gas H2 is controlled at 10%-40%, and the reduction time is 15min-60min. After the powder ore reacts in the equipment, magnetite and schistositylite with stable properties are obtained. After the reaction is completed, the reduced product enters the cooling selective oxidation stage;

[0047] (4) Cooling selective oxidation: After the reduction product enters the cooling and regulating stage, N2 is introduced into the cooling furnace chamber to cool it down. The temperature in the furnace is controlled at a specified temperature of 100°C-300°C and then air-cooled. The iron-manganese ore reduction product undergoes selective oxidation for an oxidation time of (5min-10min). After the oxidation is completed, N2 is introduced to cool it to room temperature to obtain a cooling product;

[0048] (5) High-efficiency magnetic separation: The cooled product is finely ground in a ball mill until the minerals are completely dissociated, and then separated by magnetic separation to obtain iron concentrate and manganese concentrate products.

[0049] Example 1

[0050] This embodiment uses a local iron-manganese ore with a TFe grade of 42.26% and a TMn grade of 17.86% as raw material, and is specifically carried out in the following steps:

[0051] (1) Ore feeding and grinding: The raw ore is fed into the ball mill and ground to -0.074 mm, accounting for ≥70%, and then enters the drying and disintegration operation;

[0052] (2) Drying and disintegration: The iron-manganese ore grinding products are dried in a drying and disintegrating machine to remove moisture from the materials;

[0053] (3) Fluidized synchronous reduction roasting: The dispersed materials enter the roasting furnace of the fluid reduction roasting system, the powder preheating temperature is controlled at 200°C, the atmosphere is air, the time is 3 minutes, the temperature in the furnace chamber of the ore phase conversion roasting furnace is controlled to be 500°C, N2 is introduced into the furnace chamber for 25 minutes to exhaust the air in the furnace, and then a mixture of H2 and N2 is introduced. The iron-manganese ore materials in the furnace chamber are fluidized under the action of the bottom airflow. The H2 concentration of the reducing gas is controlled at 20% and the reduction time is 25 minutes. After the powder ore reacts in the equipment, magnetite and schistosityrite with stable properties are obtained. After the reaction is completed, the reduction product enters the cooling and regulation stage;

[0054] (4) Cooling selective oxidation: After the reduction product enters the cooling control stage, N2 is introduced into the cooling furnace chamber for 25 minutes to control the temperature in the furnace at a specified temperature of 200°C, and then air-cooling is performed, wherein the iron manganese ore reduction product undergoes selective oxidation for 5 minutes. After the oxidation is completed, N2 is introduced to cool it to room temperature to obtain a cooling product;

[0055] (5) High-efficiency magnetic separation: The cooled product is finely ground by a ball mill until the minerals are completely dissociated, and then magnetically separated by a weak magnetic separator at a magnetic field strength of 1000 Oe to obtain iron concentrate and manganese concentrate products. The final product is an iron concentrate product with an Fe grade of 69.66% and a TFe recovery rate of 98.17%; a manganese concentrate product with a Mn grade of 51.60% and a TMn recovery rate of 88.48%.

[0056] Example 2

[0057] This embodiment uses a local iron-manganese ore with a TFe grade of 35.36% and a TMn grade of 19.77% as raw material, and is specifically carried out in the following steps:

[0058] (1) Ore feeding and grinding: The raw ore is fed into the ball mill and ground to -0.074 mm, accounting for ≥70%, and then enters the drying and disintegration operation;

[0059] (2) Drying and disintegration: The iron-manganese ore grinding products are dried in a drying and disintegrating machine to remove moisture from the materials;

[0060] (3) Fluidized synchronous reduction roasting: The dispersed materials enter the roasting furnace of the fluid reduction roasting system, the powder preheating temperature is controlled at 300°C, the atmosphere is air, the time is 2 minutes, the temperature in the furnace chamber of the ore phase conversion roasting furnace is controlled to be 560°C, N2 is introduced into the furnace chamber for 25 minutes to exhaust the air in the furnace, and then a mixture of H2 and N2 is introduced. The iron-manganese ore materials in the furnace chamber are fluidized under the action of the bottom airflow. The H2 concentration of the reducing gas is controlled to be 40% and the reduction time is 30 minutes. After the powder ore reacts in the equipment, magnetite and schistosityrite with stable properties are obtained. After the reaction is completed, the reduction product enters the cooling and regulation stage;

[0061] (4) Cooling selective oxidation: After the reduction product enters the cooling control stage, N2 is introduced into the cooling furnace chamber for 25 minutes to control the temperature in the furnace at a specified temperature of 200°C, and then air-cooling is performed, wherein the iron manganese ore reduction product undergoes selective oxidation for 5 minutes. After the oxidation is completed, N2 is introduced to cool it to room temperature to obtain a cooling product;

[0062] (5) High-efficiency magnetic separation: The cooled product is finely ground by a ball mill until the minerals are completely dissociated, and then magnetically separated by a weak magnetic separator at a magnetic field strength of 1100 Oe to obtain iron concentrate and manganese concentrate products. The final product is an iron concentrate product with an Fe grade of 64.07% and a TFe recovery rate of 94.59%; a manganese concentrate product with a Mn grade of 51.69% and a TMn recovery rate of 87.81%.

[0063] Example 3

[0064] This embodiment uses a certain iron manganese ore with a TFe grade of 43.72% and a TMn grade of 11.20% as raw material, and is specifically carried out in the following steps:

[0065] (1) Ore feeding and grinding: The raw ore is fed into the ball mill and ground to -0.074 mm, accounting for ≥70%, and then enters the drying and disintegration operation;

[0066] (2) Drying and disintegration: The iron-manganese ore grinding products are dried in a drying and disintegrating machine to remove moisture from the materials;

[0067] (3) Fluidized synchronous reduction roasting: The dispersed materials enter the roasting furnace of the fluid reduction roasting system, the powder preheating temperature is controlled at 400°C, the atmosphere is air, the time is 1 min, the temperature in the furnace chamber of the ore phase conversion roasting furnace is controlled to be 520°C, N2 is introduced into the furnace chamber for 25 min to exhaust the air in the furnace, and then a mixture of H2 and N2 is introduced. The iron-manganese ore materials in the furnace chamber are fluidized under the action of the bottom airflow, the H2 concentration of the reducing gas is controlled at 25%, and the reduction time is 20 min. After the powder ore reacts in the equipment, magnetite and schistositylite with stable properties are obtained. After the reaction is completed, the reduction product enters the cooling and regulation stage;

[0068] (4) Cooling selective oxidation: After the reduction product enters the cooling control stage, N2 is introduced into the cooling furnace chamber for 25 minutes to control the temperature in the furnace at a specified temperature of 100°C, and then air cooling is performed, wherein the iron manganese ore reduction product undergoes selective oxidation for 5 minutes. After the oxidation is completed, N2 is introduced to cool it to room temperature to obtain a cooling product;

[0069] (5) High-efficiency magnetic separation: The cooled product is finely ground by a ball mill until the minerals are completely dissociated, and then magnetically separated by a weak magnetic separator at a magnetic field strength of 1150 Oe to obtain iron concentrate and manganese concentrate products. The final product is an iron concentrate product with an Fe grade of 67.38% and a TFe recovery rate of 87.14%; a manganese concentrate product with a Mn grade of 30.51% and a TMn recovery rate of 87.02%.

[0070] Example 4

[0071] This embodiment uses a local iron-manganese ore with a TFe grade of 45.54% and a TMn grade of 16.86% as raw material, and is specifically carried out in the following steps:

[0072] (1) Ore feeding and grinding: The raw ore is fed into the ball mill and ground to -0.074 mm, accounting for ≥70%, and then enters the drying and disintegration operation;

[0073] (2) Drying and disintegration: The iron-manganese ore grinding products are dried in a drying and disintegrating machine to remove moisture from the materials;

[0074] (3) Fluidized synchronous reduction roasting: The dispersed materials enter the roasting furnace of the fluid reduction roasting system, the powder preheating temperature is controlled at 450°C, the atmosphere is air, the time is 1 min, the temperature in the furnace chamber of the ore phase conversion roasting furnace is controlled to be 570°C, N2 is introduced into the furnace chamber for 25 min to exhaust the air in the furnace, and then a mixture of H2 and N2 is introduced. The iron-manganese ore materials in the furnace chamber are fluidized under the action of the bottom airflow, the H2 concentration of the reducing gas is controlled at 20%, and the reduction time is 15 min. After the powder ore reacts in the equipment, magnetite and schistosityrite with stable properties are obtained. After the reaction is completed, the reduction product enters the cooling and regulation stage;

[0075] (4) Cooling selective oxidation: After the reduction product enters the cooling control stage, N2 is introduced into the cooling furnace chamber for 25 minutes to control the temperature in the furnace at a specified temperature of 200°C, and then air-cooling is performed, wherein the iron manganese ore reduction product undergoes selective oxidation for 8 minutes. After the oxidation is completed, N2 is introduced to cool it to room temperature to obtain a cooling product;

[0076] (5) High-efficiency magnetic separation: The cooled product is finely ground in a ball mill until the minerals are completely dissociated, and then passed through a weak magnetic separator. Under a magnetic field strength of 1200 Oe, magnetic separation is performed to obtain iron concentrate and manganese concentrate products. The final product is an iron concentrate product with an Fe grade of 69.73% and a TFe recovery rate of 93.44%; a manganese concentrate product with a Mn grade of 48.30% and a TMn recovery rate of 91.38%.

[0077] Example 5

[0078] This embodiment uses a certain iron manganese ore with a TFe grade of 37.82% and a TMn grade of 18.80% as raw material, and is specifically carried out in the following steps:

[0079] (1) Ore feeding and grinding: The raw ore is fed into the ball mill and ground to -0.074 mm, accounting for ≥70%, and then enters the drying and disintegration operation;

[0080] (2) Drying and disintegration: The iron-manganese ore grinding products are dried in a drying and disintegrating machine to remove moisture from the materials;

[0081] (3) Fluidized synchronous reduction roasting: The dispersed materials enter the roasting furnace of the fluid reduction roasting system, the powder preheating temperature is controlled at 380°C, the atmosphere is air, the time is 2 minutes, the temperature in the furnace chamber of the ore phase conversion roasting furnace is controlled to be 700°C, N2 is introduced into the furnace chamber for 25 minutes to exhaust the air in the furnace, and then a mixture of H2 and N2 is introduced. The iron-manganese ore materials in the furnace chamber are fluidized under the action of the bottom airflow, the H2 concentration of the reducing gas is controlled at 10%, and the reduction time is 60 minutes. After the powder ore reacts in the equipment, magnetite and schistosityrite with stable properties are obtained. After the reaction is completed, the reduction product enters the cooling and regulation stage;

[0082] (4) Cooling selective oxidation: After the reduction product enters the cooling control stage, N2 is introduced into the cooling furnace chamber for 25 minutes to control the temperature in the furnace at a specified temperature of 300°C, and then air-cooling is performed, wherein the iron manganese ore reduction product undergoes selective oxidation for 10 minutes. After the oxidation is completed, N2 is introduced to cool it to room temperature to obtain a cooling product;

[0083] (5) High-efficiency magnetic separation: The cooled product is finely ground in a ball mill until the minerals are completely dissociated, and then passed through a weak magnetic separator. Under a magnetic field strength of 1300 Oe, magnetic separation is performed to obtain iron concentrate and manganese concentrate products. The final product is an iron concentrate product with an Fe grade of 55.50% and a TFe recovery rate of 80.81%; a manganese concentrate product with a Mn grade of 44.55% and a TMn recovery rate of 81.47%.

[0084] Comparative Example 1

[0085] This comparative example uses a local iron-manganese ore with a TFe grade of 42.26% and a TMn grade of 17.86% as raw material, and is specifically carried out in the following steps:

[0086] (1) Ore feeding and grinding: The raw ore is fed into the ball mill and ground to -0.074 mm, accounting for ≥70%, and then enters the drying and disintegration operation;

[0087] (2) Drying and disintegration: The iron-manganese ore grinding products are dried in a drying and disintegrating machine to remove moisture from the materials;

[0088] (3) Fluidized synchronous reduction roasting: The dispersed materials are put into the roasting furnace of the fluid reduction roasting system, the temperature in the furnace chamber is controlled to be 500°C, N2 is introduced into the furnace chamber for 25 minutes to exhaust the air in the furnace, and then a mixture of H2 and N2 is introduced. The iron-manganese ore materials in the furnace chamber are fluidized under the action of the bottom airflow. The H2 concentration of the reducing gas is controlled to be 20% and the reduction time is 25 minutes. After the powder ore reacts in the equipment, magnetite and schistositylite with stable properties are obtained. After the reaction is completed, the reduction product enters the cooling and regulation stage;

[0089] (4) Water cooling: cooling the reduction product to room temperature with water to obtain a cooling product;

[0090] (5) High-efficiency magnetic separation: The cooled product is finely ground by a ball mill until the minerals are completely dissociated, and then magnetically separated by a weak magnetic separator at a magnetic field strength of 1000 Oe to obtain iron concentrate and manganese concentrate products. The final product is an iron concentrate product with an Fe grade of 65.66% and a TFe recovery rate of 94.17%; a manganese concentrate product with a Mn grade of 49.60% and a TMn recovery rate of 84.31%;

[0091] Compared with Example 1, the sorting indicators are reduced, the Fe grade of the iron concentrate product is reduced by 6.09%, the TFe recovery rate is reduced by 4.25%, the Mn grade of the manganese concentrate product is reduced by 4.03%, and the TMn recovery rate is reduced by 4.95%; the possible reason is that during the magnetic separation process, the strong magnetic iron minerals have magnetic agglomeration phenomenon, which will cause certain manganese minerals to be mixed in the iron ore, thereby affecting the separation of iron and manganese; and compared with Example 1, water cooling will waste more water resources and generate a lot of dust, which is not easy to implement in water-scarce areas.

[0092] Comparative Example 2

[0093] This comparative example uses a local iron-manganese ore with a TFe grade of 42.26% and a TMn grade of 17.86% as raw material, and is specifically carried out in the following steps:

[0094] (1) Ore feeding and grinding: The raw ore is fed into the ball mill and ground to -0.074 mm, accounting for ≥70%, and then enters the drying and disintegration operation;

[0095] (2) Drying and disintegration: The iron-manganese ore grinding products are dried in a drying and disintegrating machine to remove moisture from the materials;

[0096] (3) Fluidized synchronous reduction roasting: The dispersed materials are put into the roasting furnace of the fluid reduction roasting system, the temperature in the furnace chamber is controlled to be 500°C, N2 is introduced into the furnace chamber for 25 minutes to exhaust the air in the furnace, and then a mixture of H2 and N2 is introduced. The iron-manganese ore materials in the furnace chamber are fluidized under the action of the bottom airflow. The H2 concentration of the reducing gas is controlled to be 20% and the reduction time is 25 minutes. After the powder ore reacts in the equipment, magnetite and schistositylite with stable properties are obtained. After the reaction is completed, the reduction product enters the cooling and regulation stage;

[0097] (4) N2 cooling: cooling the reduced product N2 to room temperature to obtain a cooling product;

[0098] (5) High-efficiency magnetic separation: The cooled product is finely ground by a ball mill until the minerals are completely dissociated, and then magnetically separated by a weak magnetic separator at a magnetic field strength of 1000 Oe to obtain iron concentrate and manganese concentrate products. The final product is an iron concentrate product with an Fe grade of 68.14% and a TFe recovery rate of 97.35%; a manganese concentrate product with a Mn grade of 50.12% and a TMn recovery rate of 86.52%.

[0099] Compared with Example 1, the sorting index is slightly reduced, the Fe grade of the iron concentrate product is reduced by 2.23%, the TFe recovery rate is reduced by 0.84%, the Mn grade of the manganese concentrate product is reduced by 2.95%, and the TMn recovery rate is reduced by 2.27%; the possible reason is that during the magnetic separation process, the strongly magnetic iron minerals have magnetic agglomeration phenomenon, which will cause certain manganese minerals to be mixed in the iron ore, thereby affecting the iron-manganese separation, and after air cooling, part of the magnetite will be accurately converted into magnetic hematite, which reduces the hysteresis phenomenon to a certain extent, thereby reducing the magnetic agglomeration phenomenon and further improving the sorting index.

Claims

1. A method for simultaneous reduction roasting-selective oxidation-magnetic separation of refractory iron and manganese ore, characterized in that: The following steps are involved: (1) Ore feeding and grinding operation: Crushing and grinding the refractory iron-manganese ore into powder ore; (2) Drying and breaking up: Dry, break up and dehydrate the powder ore in air atmosphere; (3) Fluidized synchronous reduction roasting: First, the powder ore is preheated, roasted and dehydrated in air, and then suspended magnetized roasted in a mixed atmosphere of H2 and N2. The reduction reaction conditions are controlled, and the hematite α-Fe2O3 and pyrolusite MnO2 in the powder ore are synchronously reduced and precisely converted to obtain magnetite Fe3O4 and harzburgite MnO reduction products; (4) Cooling selective oxidation: The reduction product is first cooled down in N2, and then air-cooled to control the oxidation time, so that the magnetite Fe3O4 is selectively oxidized and accurately converted to obtain the magnetic hematite γ-Fe2O3. After the oxidation is completed, N2 is introduced to cool it to room temperature to obtain a cooling product; (5) High efficiency magnetic separation: The cooled product is further finely ground and subjected to efficient magnetic separation by magnetic separation equipment to obtain iron concentrate products and manganese concentrate products.

2. A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation as claimed in claim 1, characterized in that: Step (1) The TFe grade of the refractory iron-manganese ore is 35.36%-45.54%, and the TMn grade is 11.20%-19.77%.

3. A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation as claimed in claim 1, characterized in that: Step (1) grinding the refractory iron-manganese ore to -0.074 mm with a ball mill, accounting for ≥70%.

4. A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation as claimed in claim 1, characterized in that: In step (3), the temperature of preheating and roasting the powder ore is 200°C-450°C, and the time is 1min-3min.

5. A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation as claimed in claim 1, characterized in that: The reduction reaction temperature of step (3) is 500°C-700°C, the volume concentration of H2 in the H2 and N2 mixed gas is 10%-40%, and the reaction time is 15min-60min.

6. A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation as claimed in claim 1, characterized in that: In step (4), the reduction product is cooled to 100°C-300°C under N2, and the air cooling oxidation time is 5min-10min.

7. A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation as claimed in claim 1, characterized in that: The cooled product of step (5) is further crushed by a ball mill until it is completely dissociated.

8. A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation as claimed in claim 1, characterized in that: The high-efficiency magnetic separation equipment in step (5) is a weak magnetic separator with a magnetic field strength of 1000Oe-1300Oe.

9. A method for treating refractory iron and manganese ore by simultaneous reduction roasting-selective oxidation-magnetic separation as claimed in claim 2, characterized in that: The Fe grade of the iron concentrate product is 55.50%-69.73%, and the TFe recovery rate is 80.81%-98.17%. The Mn grade of the manganese concentrate product is 30.51%-51.69%, and the TMn recovery rate is 81.47%-91.38%.

10. An application of the fluidized synchronous reduction roasting-selective oxidation-high-efficiency magnetic separation treatment method for refractory iron and manganese ore according to claim 1, characterized in that: It is used for separating iron concentrate products and manganese concentrate products from refractory iron-manganese ores, wherein the Fe grade of the iron concentrate products is greater than 55%, and the Mn grade of the manganese concentrate products is greater than 30%.

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