Method for efficiently removing impurities and purifying high-calcium and high-magnesium rhodochrosite

Abstract

The invention discloses a method for efficiently removing impurities and purifying high-calcium and high-magnesium rhodochrosite, and belongs to the technical field of mineral processing. According to the method, calcium and magnesium impurities are removed through X-ray intelligent separation and magnetic separation, then rhodochrosite is converted into manganese chloride through a chloridized ore phase conversion technology, and then the manganese chloride is placed in deionized water to be leached; by adding a manganese sulfate solution, calcium ions are promoted to form precipitates, and calcium impurities in the solution are removed; and meanwhile, an ammonium fluoride solution is added, magnesium ion impurities are further removed, a precipitator is added into the obtained manganese chloride leaching solution, and after the reaction, high-purity rhodochrosite is obtained through precipitation, washing and drying. According to the method, efficient deep impurity removal and purification of the high-calcium and high-magnesium rhodochrosite are achieved, efficient cyclic utilization of resources is achieved, the overall cost of the process and the environmental influence are reduced, the method is suitable for large-scale continuous production, and industrial popularization is convenient to achieve.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing, and in particular relates to a method for efficiently removing impurities and purifying high-calcium and high-magnesium rhodochrosite. Background Art

[0002] Electrolytic manganese is an important metal material, widely used in steel manufacturing, alloys, chemical products and batteries. In the production process of electrolytic manganese, rhodochrosite becomes one of the main raw materials due to its high manganese content and good solubility. However, the high content of calcium and magnesium in rhodochrosite will significantly affect the production efficiency. These impurities enter the electrolyte together with manganese ions, reducing the effective concentration of manganese, resulting in a decrease in reduction efficiency and metal yield. In addition, in an acidic environment, calcium and magnesium may form insoluble salts (such as calcium sulfate and magnesium sulfate), forming precipitation, increasing the difficulty of solid-liquid separation, and even clogging the electrolytic cell. These problems restrict the preparation efficiency and quality of electrolytic manganese metal products. Therefore, it is crucial to control the content of calcium and magnesium.

[0003] Relevant scholars have conducted a lot of research on the purification of rhodochrosite. Patent CN104928469A discloses a method for removing magnesium by leaching rhodochrosite with sulfuric acid, and leaching rhodochrosite with concentrated sulfuric acid, which significantly reduces the magnesium content. However, concentrated sulfuric acid is highly corrosive to equipment during the leaching process, and rhodochrosite usually contains a high concentration of calcium ions, but this method fails to effectively solve the problem of calcium removal. Patent CN101985365A proposes a method for preparing manganese carbonate, by adjusting the pH of an acidic manganese solution to 7-8 using ammonia water, and then passing carbon dioxide, thereby obtaining manganese carbonate with less impurity content. However, although this method effectively reduces the sodium content, other impurities are still high, and the purification efficiency is limited.

[0004] In response to the sustainable development policy, improving the purity of rhodochrosite to reduce the waste generated in the process of preparing electrolytic manganese metal is an effective way to achieve green production. Therefore, it is particularly important to develop a deep impurity removal process for rhodochrosite that can efficiently remove impurities such as calcium and magnesium. In view of this situation, the present invention proposes an efficient impurity removal and purification method suitable for high-calcium and high-magnesium rhodochrosite. Summary of the invention

[0005] The primary purpose of the present invention is to provide a method for pre-deep impurity removal of rhodochrosite, aiming to improve the leaching rate of manganese in subsequent leaching operations of rhodochrosite, and ultimately produce high-quality manganese concentrate.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for efficiently removing impurities and purifying high-calcium and high-magnesium rhodochrosite comprises the following steps:

[0008] Coarse crushing: crush the rhodochrosite to a particle size of ≤140mm;

[0009] Intelligent pre-selection: The crushed products are pre-selected in an X-ray intelligent sorter to obtain intelligent pre-selected concentrates and pre-selected tailings;

[0010] Fine crushing and grinding: Grind the intelligent pre-selected concentrate to a particle size of ≤0.2mm to obtain a crushed product, wherein the -0.074mm ore powder in the crushed product accounts for ≥60% of the total mass of the X-ray intelligent pre-selected concentrate;

[0011] Magnetic separation: The crushed and ground products are subjected to magnetic separation to obtain magnetically separated manganese concentrate and magnetically separated tailings;

[0012] Chloride ore phase conversion: After the magnetically separated manganese concentrate is dried, it is conveyed to the mixing bin through a conveyor belt, and ammonium chloride is added to mix the materials. Then, it is conveyed to the ore phase conversion furnace through a conveyor belt for chloride ore phase conversion;

[0013] Cooling: The material discharged from the ore phase conversion furnace is cooled once through a multi-stage cooling cyclone; during the primary cooling process, the material exchanges heat with the protective gas and the temperature is reduced to below 150°C; the product after primary cooling is fed into a fluidized bed cooler for secondary cooling, and the temperature of the product after secondary cooling is reduced to below 60°C, thereby obtaining a secondary cooled chlorinated ore phase conversion product;

[0014] Leaching: The chloride ore phase conversion product after secondary cooling is subjected to leaching operation, and the leached product is filtered to obtain leaching liquid and leaching residue;

[0015] Purification and impurity removal: add manganese sulfate solution to the leachate to form calcium sulfate precipitation, and then perform solid-liquid separation; add ammonium fluoride solution to the liquid obtained by solid-liquid separation, stir and stand it for solid-liquid separation to deeply remove calcium and magnesium impurities, and obtain manganese chloride purified liquid;

[0016] Preparation of high-purity rhodochrosite: Add ammonium bicarbonate solution to the manganese chloride purification solution and let it stand to allow it to fully react. After filtration, washing and drying, high-purity rhodochrosite is obtained.

[0017] Furthermore, the composition of the rhodochrosite includes, by mass percentage, 23.00 wt% to 33.50 wt% of Mn, 12.00 wt% to 28.50 wt% of SiO2, 3.00 wt% to 12.00 wt% of MgO, and 4.00 wt% to 13.00 wt% of CaO.

[0018] Furthermore, during the intelligent pre-selection process, the conveyor belt width of the X-ray intelligent sorting machine is 1.2m to 2m, and the conveyor belt speed is 2m / s to 4m / s.

[0019] Furthermore, the pre-selected tailings and the magnetically separated tailings are pre-thrown tailings.

[0020] Furthermore, the magnetic field strength during the magnetic separation process is 8000Oe to 16000Oe.

[0021] Furthermore, the mass ratio of ammonium chloride to rhodochrosite added during the chloride ore phase transformation process is (0.5:1) to (1.5:1), the chloride ore phase transformation temperature is 400°C to 700°C, the chloride ore phase transformation time is 10min to 40min, and nitrogen is used as a protective gas during the chloride ore phase transformation process.

[0022] Furthermore, the chemical reactions occurring during the phase transformation of the chloride ore include:

[0023]

[0024] Furthermore, during the leaching process, deionized water is used to leach the chloride ore phase transformation product after secondary cooling, the leaching temperature is 25°C to 60°C, the leaching time is 0.5h to 1.5h, and the leaching liquid-solid ratio is 3mL / g to 10mL / g.

[0025] Furthermore, during purification and impurity removal, the molar ratio of the added manganese sulfate to the calcium ions in the leaching solution is n(Ca 2+ ): n(MnSO4) = 1: (1.0-2.0), the concentration of manganese sulfate solution is 0.5 mol / L-1.5 mol / L; the molar ratio of the added ammonium fluoride to the magnesium ion in the leaching solution is n(Mg 2+ ): n(NH4F) = 1: (1.5-3.0), the concentration of ammonium fluoride solution is 0.2 mol / L-1.2 mol / L.

[0026] Furthermore, when preparing high-purity rhodochrosite, the NH3HCO3 concentration is 1 mol / L to 2 mol / L, the solution pH is 6.6 to 7.3, and the reaction time is 0.8 h to 1.2 h.

[0027] Furthermore, when preparing high-purity rhodochrosite, the chemical reactions that occur include:

[0028]

[0029] The present invention provides a method for efficiently removing impurities and purifying high-calcium and high-magnesium rhodochrosite, and its principle and key technical points are: the core technology of the present invention is to efficiently remove calcium and magnesium impurities in rhodochrosite through a chemical process flow, thereby preparing high-purity rhodochrosite. The present invention first uses X-ray intelligent sorting technology to pre-select ores with low calcium and magnesium content to improve the efficiency of subsequent processing; before the chloride ore phase transformation, the calcium and magnesium impurities are secondary removed by a magnetic separation process; the rhodochrosite is converted into manganese chloride through a chloride ore phase transformation process and then placed in deionized water for leaching; in the subsequent leaching process, by adding manganese sulfate solution, calcium ions are precipitated to remove calcium impurities in the solution; at the same time, ammonium fluoride solution is added to effectively remove magnesium ion impurities, and finally a purified manganese chloride solution is obtained. Finally, the precipitant NH4HCO3 is added to the manganese chloride leaching solution to promote Mn 2+ With CO3 2- The present invention precisely controls the reaction conditions of the solution and depends on the solubility product conditions of manganese carbonate to make Mn 2+ and CO3 2- After the crystal nucleus is formed, the ions are continuously precipitated to the surface of the crystal nucleus through diffusion, and finally high-purity rhodochrosite is formed.

[0030] Compared with the existing electrolytic manganese waste slag treatment process, the characteristics and advantages of the present invention are:

[0031] 1. The present invention realizes the efficient deep impurity removal and purification of high-calcium and high-magnesium rhodochrosite, obtains a high-purity rhodochrosite product, significantly improves the manganese grade, and has significant effects on calcium and magnesium removal.

[0032] 2. The CO2, NH3 and HCl tail gases generated in the phase conversion process of the chloride ore of the present invention can be recycled. Among them, NH3 and CO2 can be used to supplement ammonium bicarbonate, NH4Cl can be used as an additive for the phase conversion of the chloride ore, and HCl can be recycled to prepare industrial hydrochloric acid, thereby achieving efficient recycling of resources and reducing the overall cost and environmental impact of the process.

[0033] 3. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite proposed in the present invention has a simple process, smooth connection, relatively mature related technology, is suitable for large-scale continuous production, and is easy to achieve industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The figure is a schematic flow chart of the method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite of the present invention. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the accompanying drawings and examples. The test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described can be obtained from commercial channels unless otherwise specified, and the preferred embodiments described are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0036] The composition of the high-calcium and high-magnesium rhodochrosite used in the present invention includes, by mass percentage, 23.00wt% to 33.50wt% of Mn, 12.00wt% to 28.50wt% of SiO2, 3.00wt% to 12.00wt% of MgO, and 4.00wt% to 13.00wt% of CaO.

[0037] In the method provided by the present invention, during the phase transformation of the chloride ore, the mass ratio of the added ammonium chloride to the rhodochrosite is (0.5:1) to (1.5:1); the phase transformation temperature of the chloride ore is 400°C to 700°C, the time is 10min to 40min, and nitrogen is used as a protective gas during the phase transformation of the chloride ore. The tail gas generated by the reaction contains CO2, NH3 and HCl, and the tail gas can be recovered, and the NH3 and CO2 therein are introduced into the manganese chloride solution in the process of preparing high-purity rhodochrosite, thereby reducing the amount of NH3HCO3; the HCl is recovered and used to prepare industrial hydrochloric acid.

[0038] In the method for efficiently removing impurities and purifying high-calcium and high-magnesium rhodochrosite provided by the present invention, the conveyor belt width of the adopted X-ray intelligent sorting machine is 1.2m-2m, and the conveyor belt speed is 2m / s-4m / s.

[0039] In the high-efficiency impurity removal and purification method of high-calcium and high-magnesium rhodochrosite provided by the present invention, the pre-selection tailings and the magnetic separation tailings are combined into the pre-throwing tailings.

[0040] The present invention uses deionized water to carry out leaching operation on the chloride ore phase conversion product after secondary cooling, the leaching temperature is 25°C to 60°C, the leaching time is 0.5h to 1.5h, and the leaching liquid-solid ratio is 3mL / g to 10mL / g.

[0041] In the method for efficiently removing impurities and purifying high-calcium and high-magnesium rhodochrosite provided by the present invention, the amount of manganese sulfate solution added during the purification and impurity removal process is n(Ca 2+ ): n(MnSO4)=1:(1.0~2.0), the concentration is 0.5mol / L~1.5mol / L; the amount of ammonium fluoride solution added is n(Mg 2+ ):n(NH4F)=1:(1.5~3.0), concentration is 0.2mol / L~1.2mol / L.

[0042] Embodiment 1:

[0043] A method for efficiently removing impurities and purifying high-calcium and high-magnesium rhodochrosite, such as Figure 1 As shown, the following steps are included:

[0044] The rhodochrosite in this embodiment comes from the Akto-Wuqia area of ​​Xinjiang, wherein the Mn content is 28.87wt%, the SiO2 content is 16.39wt%, the MgO content is 5.14wt%, and the CaO content is 6.64wt%.

[0045] Coarse crushing: The rhodochrosite ore is fed into the coarse crusher for crushing to obtain a crushed product with a particle size less than 100 mm.

[0046] Intelligent pre-selection: The crushed products are pre-selected in an X-ray intelligent sorting machine to obtain intelligent pre-selected concentrates and pre-selected tailings.

[0047] Fine crushing and grinding: The intelligent pre-selected concentrate is crushed to a particle size of less than 0.2 mm, of which -0.074 mm ore powder accounts for 60% of the total mass.

[0048] Magnetic separation: The crushed samples are sent into a vertical ring high-intensity magnetic separator with a magnetic field strength of 13000Oe to obtain magnetic concentrate and magnetic tailings. The magnetic tailings and pre-selected tailings are combined into pre-thrown tailings.

[0049] Chloride ore phase conversion; After the magnetic concentrate is dried, it is conveyed to a mixing bin via a conveyor belt, and ammonium chloride is added to mix ammonium chloride and rhodochrosite in a mass ratio of 0.8:1. It is then conveyed into an ore phase converter via a conveyor belt for chloride ore phase conversion. The temperature in the ore phase converter is stabilized at 450°C, and the roasting time is 20 minutes, so that rhodochrosite and ammonium chloride react fully under a nitrogen protective atmosphere. The HCL produced during the reaction is collected by a gas recovery device and used to prepare industrial hydrochloric acid. CO2 and NH3 gases are introduced into the manganese chloride solution described in step 9, thereby reducing the amount of NH4HCO3 used.

[0050] Cooling: The material discharged from the mineral phase conversion furnace is cooled once through a multi-stage cooling cyclone. The material exchanges heat with the protective gas and the temperature is reduced to below 150°C. The product after primary cooling is fed into the fluidized bed cooler, and the product temperature is reduced to below 60°C to obtain the chloride mineral phase conversion product.

[0051] Leaching: The cooled chloride ore phase conversion product was leached in water, the leaching temperature was set to 30°C, the leaching time was 0.6h, and the liquid-solid ratio was 4mL / g. The leached product was filtered to obtain the leaching solution and leaching residue respectively.

[0052] Purification and impurity removal: Add 0.8 mol / L manganese sulfate solution to the leaching solution, according to the calcium ion (Ca 2+) and manganese sulfate (MnSO4) in a molar ratio of 1:1.5. Calcium sulfate precipitate is formed by adjusting the pH to 5.5 with ammonia water and keeping the solution temperature at 35°C, and solid-liquid separation is performed. Ammonium fluoride solution with a concentration of 0.6 mol / L is added to the separated liquid. 2+ ) and ammonium fluoride (NH4F) in a molar ratio of 1:2. Stir for 1 hour and let stand for 1 hour before solid-liquid separation to deeply remove calcium and magnesium impurities.

[0053] Preparation of high-purity rhodochrosite: Add 1.2 mol / L ammonium bicarbonate solution to the manganese chloride purification solution, adjust the solution pH to 6.8 and let it stand for 0.8h to allow it to react fully. After filtration, washing and drying, a high-purity rhodochrosite product with a Mn grade of 45.10%, a SiO2 content of 0.02%, a CaO content of 0.08% and a MgO content of 0.06% is finally obtained.

[0054] Embodiment 2:

[0055] The rhodochrosite used in this embodiment has a Mn content of 30.12 wt %, a SiO2 content of 12.78 wt %, a MgO content of 6.66 wt %, and a CaO content of 5.10 wt %.

[0056] Coarse crushing: The rhodochrosite ore is fed into the coarse crusher for crushing to obtain a crushed product with a particle size less than 100 mm.

[0057] X-ray intelligent pre-selection: The crushed products are pre-selected in an X-ray intelligent sorting machine to obtain intelligent pre-selected concentrates and pre-selected tailings.

[0058] Fine crushing and grinding: The intelligent pre-selected concentrate is crushed to a particle size of less than 0.2 mm, of which -0.074 mm ore powder accounts for 65% of the total mass.

[0059] Magnetic separation: The crushed samples are sent into a vertical ring high-intensity magnetic separator with a magnetic field strength of 14000Oe to obtain magnetic concentrate and magnetic tailings. The magnetic tailings and pre-selected tailings are combined into pre-thrown tailings.

[0060] Chloride ore phase conversion; After the magnetic concentrate is dried, it is conveyed to a mixing bin via a conveyor belt, and ammonium chloride is added to mix ammonium chloride and rhodochrosite in a mass ratio of 0.9:1. It is then conveyed into an ore phase converter via a conveyor belt for chloride ore phase conversion. The temperature in the ore phase converter is stabilized at 480°C, and the roasting time is 30 minutes, so that rhodochrosite and ammonium chloride react fully. The HCL produced during the reaction is collected by a gas recovery device and used to prepare industrial hydrochloric acid. CO2 and NH3 gases are introduced into the manganese chloride solution described in step 9, thereby reducing the amount of NH4HCO3 used.

[0061] Cooling: The material discharged from the mineral phase conversion furnace is cooled once through a multi-stage cooling cyclone. The material exchanges heat with the protective gas and the temperature is reduced to below 150°C. The product after primary cooling is fed into the fluidized bed cooler, and the product temperature is reduced to below 60°C to obtain the chloride mineral phase conversion product.

[0062] Leaching: The cooled chloride ore phase conversion product was leached in water, and the leaching temperature was set to 35°C, the leaching time was 0.6h, and the liquid-solid ratio was 4mL / g. The leached product was filtered to obtain the leaching liquid and leaching residue respectively.

[0063] Purification and impurity removal: Add 0.7 mol / L manganese sulfate solution to the leaching solution, according to the calcium ion (Ca 2+ ) and manganese sulfate (MnSO4) in a molar ratio of 1:1.6. Adjust the pH to 5.7 with ammonia water and keep the solution temperature at 35°C to form calcium sulfate precipitation, which is then separated into solid and liquid. Add ammonium fluoride solution with a concentration of 0.8 mol / L to the separated liquid, and adjust the concentration of magnesium ions (Mg 2+ ) and ammonium fluoride (NH4F) in a molar ratio of 1:2. Stir for 1 hour and let stand for 1 hour before solid-liquid separation to deeply remove calcium and magnesium impurities.

[0064] Preparation of high-purity rhodochrosite: Add 1.2 mol / L ammonium bicarbonate solution to the purified manganese chloride solution, adjust the solution pH to 6.7 and let it stand for 0.9 h to allow it to react fully. After filtration, washing and drying, a high-purity rhodochrosite product with a Mn grade of 45.69%, a SiO2 content of 0.01%, a CaO content of 0.05% and a MgO content of 0.07% is finally obtained.

[0065] Embodiment 3:

[0066] The rhodochrosite used in this embodiment has a Mn content of 29.38 wt %, a SiO2 content of 14.16 wt %, a MgO content of 5.32 wt %, and a CaO content of 6.27 wt %.

[0067] Coarse crushing: The rhodochrosite ore is fed into the coarse crusher for crushing to obtain a crushed product with a particle size less than 100 mm.

[0068] Intelligent sorting: The crushed products are pre-selected in an X-ray intelligent sorting machine to obtain intelligent pre-selected concentrates and pre-selected tailings.

[0069] Fine crushing and grinding: The intelligent pre-selected concentrate is crushed to a particle size of less than 0.2 mm, of which -0.074 mm ore powder accounts for 65% of the total mass.

[0070] Magnetic separation: The crushed samples are sent into a vertical ring high-intensity magnetic separator with a magnetic field strength of 14000Oe to obtain magnetic concentrate and magnetic tailings. The magnetic tailings and pre-selected tailings are combined into pre-thrown tailings.

[0071] Chloride ore phase conversion: After the magnetic concentrate is dried, it is conveyed to a mixing bin via a conveyor belt, and ammonium chloride is added to mix ammonium chloride and rhodochrosite in a mass ratio of 1:1. It is then conveyed into an ore phase converter via a conveyor belt for chloride ore phase conversion. The temperature in the ore phase converter is stabilized at 500°C, and the roasting time is 35 minutes, so that rhodochrosite and ammonium chloride react fully. The HCL produced during the reaction is collected by a gas recovery device and used to prepare industrial hydrochloric acid. CO2 and NH3 gases are introduced into the manganese chloride solution described in step 9, thereby reducing the amount of NH4HCO3 used.

[0072] Cooling: The material discharged from the mineral phase conversion furnace is cooled once through a multi-stage cooling cyclone. The material exchanges heat with the protective gas and the temperature is reduced to below 150°C. The product after primary cooling is fed into the fluidized bed cooler, and the product temperature is reduced to below 60°C to obtain the chloride mineral phase conversion product.

[0073] Leaching: The cooled chloride ore phase conversion product is leached in water, the leaching temperature is set to 30°C, the leaching time is 1h, and the liquid-solid ratio is 6mL / g. The leached product is filtered to obtain the leaching liquid and leaching residue respectively.

[0074] Purification and impurity removal: Add 1.0 mol / L manganese sulfate solution to the leaching solution, according to the calcium ion (Ca 2+ ) and manganese sulfate (MnSO4) in a molar ratio of 1:1.8. Calcium sulfate precipitate is formed by adjusting the pH to 5.7 with ammonia water and maintaining the solution temperature at 45°C, and solid-liquid separation is performed. Ammonium fluoride solution with a concentration of 1.0 mol / L is added to the separated liquid. 2+ Ammonium fluoride (NH4F) was added in a molar ratio of 1:2.5. After stirring for 1 hour and standing for 1 hour, solid-liquid separation was performed to deeply remove calcium and magnesium impurities.

[0075] Preparation of high-purity rhodochrosite: Add 1 mol / L ammonium bicarbonate solution to the purified manganese chloride solution, adjust the solution pH to 7.0 and let it stand for 1.0h to allow it to react fully. After filtration, washing and drying, a high-purity rhodochrosite product with a Mn grade of 45.57%, a SiO2 content of 0.02%, a CaO content of 0.05% and a MgO content of 0.04% is finally obtained.

[0076] Embodiment 4:

[0077] The rhodochrosite used in this embodiment has a Mn content of 33.59 wt %, a SiO2 content of 12.37 wt %, a MgO content of 4.77 wt %, and a CaO content of 5.55 wt %.

[0078] Coarse crushing: The rhodochrosite ore is fed into the coarse crusher for crushing to obtain a crushed product with a particle size less than 100 mm.

[0079] Intelligent pre-selection: The crushed products are pre-selected in an X-ray intelligent sorting machine to obtain intelligent pre-selected concentrates and pre-selected tailings.

[0080] Fine crushing and grinding: The intelligent pre-selected concentrate is crushed to a particle size of less than 0.2 mm, of which -0.074 mm ore powder accounts for 65% of the total mass.

[0081] Magnetic separation: The crushed samples are sent into a vertical ring high-intensity magnetic separator with a magnetic field strength of 14000Oe to obtain magnetic concentrate and magnetic tailings. The magnetic tailings and pre-selected tailings are combined into pre-thrown tailings.

[0082] Chloride ore phase conversion; After the magnetic concentrate is dried, it is conveyed to a mixing bin via a conveyor belt, and ammonium chloride is added to mix ammonium chloride and rhodochrosite in a mass ratio of 1.1:1. It is then conveyed into an ore phase converter via a conveyor belt for chloride ore phase conversion. The temperature in the ore phase converter is stabilized at 500°C, and the roasting time is 35 minutes, so that rhodochrosite and ammonium chloride react fully. The HCL produced during the reaction is collected by a gas recovery device and used to prepare industrial hydrochloric acid. CO2 and NH3 gases are introduced into the manganese chloride solution described in step 9, thereby reducing the amount of NH4HCO3 used.

[0083] Cooling: The material discharged from the mineral phase conversion furnace is cooled once through a multi-stage cooling cyclone. The material exchanges heat with the protective gas and the temperature is reduced to below 150°C. The product after primary cooling is fed into the fluidized bed cooler, and the product temperature is reduced to below 60°C to obtain the chloride mineral phase conversion product.

[0084] Leaching: The cooled chloride ore phase conversion product was leached in water, the leaching temperature was set to 60°C, the leaching time was 1.4h, and the liquid-solid ratio was 9mL / g. The leached product was filtered to obtain the leaching liquid and leaching residue respectively.

[0085] Purification and impurity removal: Add 1.0 mol / L manganese sulfate solution to the leaching solution, according to the calcium ion (Ca 2+ ) and manganese sulfate (MnSO4) in a molar ratio of 1:2.0. Adjust the pH to 5.7 with ammonia water and keep the solution temperature at 45°C to form calcium sulfate precipitation, which is then separated into solid and liquid. Add ammonium fluoride solution with a concentration of 1.0 mol / L to the separated liquid, and adjust the concentration of magnesium ions (Mg 2+Ammonium fluoride (NH4F) was added in a molar ratio of 1:2.8. After stirring for 1 hour and standing for 1 hour, solid-liquid separation was performed to deeply remove calcium and magnesium impurities.

[0086] Preparation of high-purity rhodochrosite: Add 1 mol / L ammonium bicarbonate solution to the purified manganese chloride solution, adjust the solution pH to 7.2 and let it stand for 1.2 hours to allow it to react fully. After filtration, washing and drying, a high-purity rhodochrosite product with a Mn grade of 45.93%, a SiO2 content of 0.01%, a CaO content of 0.02% and a MgO content of 0.02% is finally obtained.

Claims

1. A method for efficiently removing impurities and purifying high-calcium and high-magnesium rhodochrosite, characterized in that: The following steps are involved: Coarse crushing: crush the rhodochrosite to a particle size of ≤140mm; Intelligent pre-selection: The crushed products are pre-selected in an X-ray intelligent sorter to obtain intelligent pre-selected concentrates and pre-selected tailings; Fine crushing and grinding: Grind the X-ray intelligent pre-selected concentrate to a particle size of ≤0.2mm to obtain a crushed product; Magnetic separation: The crushed and ground products are subjected to magnetic separation to obtain magnetically separated manganese concentrate and magnetically separated tailings; Chloride ore phase conversion: After the magnetically separated manganese concentrate is dried, it is conveyed to the mixing bin through a conveyor belt, and ammonium chloride is added to mix the materials. Then, it is conveyed to the ore phase conversion furnace through a conveyor belt for chloride ore phase conversion; Cooling: The material discharged from the mineral phase conversion furnace is cooled once through a multi-stage cooling cyclone; the product after the primary cooling is fed into a fluidized bed cooler for secondary cooling to obtain a chloride mineral phase conversion product; Leaching: The chloride ore phase conversion product after secondary cooling is subjected to leaching operation, and the leached product is filtered to obtain leaching liquid and leaching residue; Purification and impurity removal: add manganese sulfate solution to the leachate to form calcium sulfate precipitation, and then perform solid-liquid separation; add ammonium fluoride solution to the liquid obtained by solid-liquid separation, stir and stand it for solid-liquid separation to deeply remove calcium and magnesium impurities, and obtain manganese chloride purified liquid; Preparation of high-purity rhodochrosite: Add ammonium bicarbonate solution to the manganese chloride purification solution and let it stand to allow it to fully react. After filtration, washing and drying, high-purity rhodochrosite is obtained.

2. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite according to claim 1, characterized in that: The composition of rhodochrosite includes, by mass percentage, 23.00 wt% to 33.50 wt% of Mn, 12.00 wt% to 28.50 wt% of SiO2, 3.00 wt% to 12.00 wt% of MgO, and 4.00 wt% to 13.00 wt% of CaO.

3. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite according to claim 1, characterized in that: The conveyor belt width of the X-ray intelligent sorting machine is 1.2m~2m, and the conveyor belt speed is 2m / s~4m / s.

4. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite according to claim 1, characterized in that: The -0.074mm mineral powder in the crushed and ground products accounts for ≥60% of the total mass of the intelligent pre-selected concentrate.

5. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite according to claim 1, characterized in that: The magnetic field strength during magnetic separation is 8000Oe~16000Oe; The magnetic separation tailings and pre-separation tailings are combined into pre-discharge tailings.

6. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite according to claim 1, characterized in that: The mass ratio of ammonium chloride to rhodochrosite added during the phase conversion of chloride ore is (0.5:1) to (1.5:1); The phase transformation temperature of the chloride ore is 400°C to 700°C, the time is 10min to 40min, and nitrogen is used as the protective gas during the phase transformation process of the chloride ore.

7. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite according to claim 1, characterized in that: During the primary cooling process, heat exchange occurs between the material and the protective gas, and the temperature drops below 150°C; The product temperature after secondary cooling drops to below 60°C.

8. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite according to claim 1, characterized in that: Deionized water is used to leach the chloride ore phase conversion product after secondary cooling, the leaching temperature is 25°C to 60°C, the leaching time is 0.5h to 1.5h, and the leaching liquid-solid ratio is 3mL / g to 10mL / g.

9. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite according to claim 1, characterized in that: The concentration of the added manganese sulfate solution is 0.5 mol / L to 1.5 mol / L, and the molar ratio of manganese sulfate to calcium ions in the leaching solution is n(Ca 2 + ): n(MnSO4)=1: (1.0~2.0); The concentration of the added ammonium fluoride solution is 0.2 mol / L to 1.2 mol / L, and the molar ratio of ammonium fluoride to magnesium ions in the leaching solution is n(Mg 2+ ): n(NH4F)=1: (1.5~3.0).

10. The method for efficient impurity removal and purification of high-calcium and high-magnesium rhodochrosite according to claim 1, characterized in that: When preparing high-purity rhodochrosite, the concentration of NH3HCO3 solution is 1 mol / L to 2 mol / L, the pH of the solution is 6.6 to 7.3, and the reaction time is 0.8 h to 1.2 h.

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