A method for preparing metallic manganese by two-stage pre-purification-liquid preparation electrolysis of high-calcium high-magnesium low-grade rhodochrosite

Abstract

The application discloses a method for preparing metal manganese by two-stage pre-purification-liquid preparation electrolysis coordination from high-calcium high-magnesium low-grade rhodochrosite, and belongs to the field of mineral processing. The method comprises the following steps: crushing rhodochrosite to obtain rhodochrosite particles; conveying the rhodochrosite particles to a sorting machine through a conveying belt to perform pre-selection to obtain pre-selected concentrate; performing grinding on the pre-selected concentrate to obtain a grinding product; preparing the grinding product into a slurry to perform strong magnetic separation to obtain magnetic separation concentrate; performing one-stage reverse flotation-two-stage positive flotation on the magnetic separation concentrate after slurry preparation to obtain flotation concentrate; performing water washing and slurry treatment on the flotation concentrate; reacting the slurry after slurry treatment with sulfuric acid; subsequently, performing filter pressing on the combined slurry, and performing purification, standing and storage treatment on the obtained filtrate to obtain electrolyte meeting electrolysis requirements; performing electrolysis on the electrolyte, and subsequently performing passivation, rinsing, drying and stripping treatment in sequence to finally obtain electrolytic metal manganese products with a purity higher than 99.70%.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing, and specifically relates to a method for producing electrolytic manganese using rhodochrosite as raw material, including raw material pretreatment, wet liquid preparation, purification, electrolysis, and wastewater reuse. Background Technology

[0002] Electrolytic manganese typically uses manganese-bearing minerals as raw materials. In the production process, the ore undergoes pretreatment such as crushing and grinding, then is mixed with process liquid to form a slurry. This slurry is leached in an acidic system to generate a manganese-containing solution. Subsequently, purification and solid-liquid separation are performed to obtain an electrolyte that meets the requirements for electrolysis. Finally, the product is obtained through electrolysis, passivation, rinsing, drying, and stripping. This type of wet process—liquid preparation-purification-electrolysis—is mature, but it is highly sensitive to the properties of the feed. Fluctuations in the grade and impurity composition of the raw materials directly affect leaching efficiency, purification difficulty, electrolyte stability, and system operating costs. In rhodochrosite resources, impurities such as calcium and magnesium are often associated with carbonate minerals such as calcite and magnesium-bearing silicate minerals such as chlorite. When calcite and other carbonate gangues enter an acidic liquid preparation system, they are prone to side reactions, leading to increased acid consumption and an increase in dissolved ions. Clay silicate minerals such as chlorite are prone to mudification and dispersion during grinding and pulping, resulting in increased pulp viscosity, difficulty in solid-liquid separation, and the possibility that components such as magnesium and silicon may enter the solution system, increasing the burden on subsequent purification and impurity removal.

[0003] To address the above issues, existing production lines typically rely on chemical purification and multi-stage pressure filtration in the wet process to ensure electrolyte quality. Since impurities entering the wet process system require treatment through acid addition, chemical sedimentation, flocculation, and filtration, acid and chemical consumption increases significantly when the feed ore contains high levels of carbonate gangue and siliceous silicate. This increases the burden on pressure filtration operation and filter cloth maintenance, and makes filtrate entrainment and electrolyte impurity fluctuations more likely. Furthermore, increased wet process load is often accompanied by increased wastewater generation and treatment load, affecting the overall economic efficiency and stability of the system.

[0004] Therefore, there is an urgent need to provide an electrolytic manganese production method suitable for high-calcium and high-magnesium rhodochrosite raw materials. This method would introduce a pre-selection and purification method that matches the characteristics of the raw materials before the wet process, thereby reducing the adverse effects of impurities such as calcite and chlorite on the electrolyte preparation and purification electrolysis process, reducing acid consumption and purification reagent consumption, alleviating the load on solid-liquid separation and wastewater treatment, and improving electrolyte stability, thus achieving stable operation of the electrolytic manganese production process. Summary of the Invention

[0005] The primary objective of this invention is to provide a method for the synergistic preparation of metallic manganese from high-calcium, high-magnesium, and low-grade rhodochrosite through a two-stage pre-purification and electrolyte preparation process. This method aims to reduce the impact of calcium and magnesium impurities in high-calcium and high-magnesium rhodochrosite, decrease acid and reagent consumption, alleviate the burden of solid-liquid separation and wastewater treatment, improve electrolyte stability, and achieve stable electrolytic manganese production.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for the synergistic preparation of metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite using a two-stage pre-purification and liquid electrolysis process includes the following steps:

[0008] 1. Sample preparation: Rhodochrosite was crushed to obtain rhodochrosite particles with a particle size of less than 100 mm.

[0009] 2. Pre-selection: Rhodochrosite particles are conveyed to a separator via a conveyor belt for pre-selection to obtain pre-selected concentrate and pre-selected tailings.

[0010] 3. Grinding and screening: The pre-selected concentrate is ground, and the content of -0.074 mm particles in the grinding product is controlled to account for more than 75% of the total mass of the product to obtain the grinding product.

[0011] 4. High-intensity magnetic separation: After the grinding products are formulated into slurry, high-intensity magnetic separation is carried out to obtain magnetic concentrate and magnetic tailings.

[0012] 5. Flotation: After adjusting the magnetic concentrate into a pulp, flotation is carried out. The flotation adopts a one-stage reverse flotation-two-stage forward flotation process to obtain flotation concentrate.

[0013] 6. Stabilization preparation of electrolyte: The flotation concentrate is washed with water and pulped; the pulped slurry reacts with sulfuric acid to convert manganese minerals into manganese sulfate and enter the liquid phase; the combined slurry is then filtered by pressure, and the resulting filtrate is purified, allowed to stand, and stored to obtain an electrolyte that meets the requirements of electrolysis.

[0014] 7. Finished product processing: The electrolyte is electrolyzed, followed by passivation, rinsing, drying and stripping treatments to finally obtain electrolytic manganese metal with a purity higher than 99.70%.

[0015] In step 1, the Mn grade in rhodochrosite is 18%~35%, the SiO2 grade is 13%~25%, the Al2O3 grade is 3%~10%, the MgO grade is 5%~16%, and the CaO grade is 5%~18%.

[0016] In step 2, the sorting machine is an X-ray transmission pre-sorter; the conveyor belt width of the X-ray transmission pre-sorter is 1.8 m, the conveyor belt speed is 1.5 m / s, the vibration frequency of the feed hopper is 10 Hz~40 Hz, the light source voltage is 120 kV~180 kV, and the current is 2 mA~4 mA. In step 4, the strong magnetic separation operation adopts a wet high-gradient strong magnetic separator; the magnetic field strength of the wet high-gradient strong magnetic separator is 8000 Oe~25000 Oe.

[0017] In step 5, the flotation adopts a one-stage reverse flotation-two-stage forward flotation process; wherein, the one-stage reverse flotation is used to preferentially remove gangue minerals containing calcium, magnesium, silicon and aluminum, and the two-stage forward flotation is used to further enrich and recover rhodochrosite, thereby reducing the content of weakly magnetic and non-magnetic impurities such as CaO, MgO, SiO2 and Al2O3, and improving the grade of manganese concentrate.

[0018] In step 5, the magnetically separated concentrate is added to a sodium carbonate solution with a mass percentage concentration of 2%–5%, and the slurry is adjusted at room temperature to pH=8, with the slurry concentration controlled at 30%–40%. Then, 800 g / t–1600 g / t of silicate ether amine collector is added over a period of 1–4 minutes for a first-stage reverse flotation, with a skimming time of 5 minutes. After the reverse flotation, the resulting froth product is the first-stage rough reverse flotation tailings, and the product in the tank is the first-stage rough reverse flotation concentrate.

[0019] In step 5, the rough reverse flotation concentrate is added to a sodium carbonate solution with a mass percentage concentration of 2%–5%, and the pulp is adjusted to pH=9 at room temperature. Then, 5 g / t–15 g / t sodium lignosulfonate inhibitor and 300 g / t–700 g / t quaternary ammonium salt collector are added for a second-stage direct flotation to recover manganese minerals. The pulp concentration is controlled at 20%–30%, the reagent addition time is 3 min, and the froth removal time is 5 min–7 min. After the direct flotation is completed, the resulting froth product is dried to obtain the second-stage direct flotation concentrate, and the product in the tank is the second-stage direct flotation tailings.

[0020] In step 6, the reaction between sulfuric acid and the pulped flotation concentrate takes place in a chemical reaction tank; the liquid-to-solid ratio is 4:1 to 8:1, the sulfuric acid concentration is 0.6 mol / L to 1.4 mol / L, the chemical reaction temperature is 40℃ to 90℃, and the chemical reaction time is 30 min to 150 min. In step 6, water washing is used to remove residual reagents and some soluble impurities from the surface of the flotation concentrate; pulping is used to prepare a uniform slurry; the manganese minerals in the pulped flotation concentrate react with sulfuric acid in the chemical reaction tank to generate manganese sulfate, which enters the solution; pressure filtration is used to achieve solid-liquid separation; purification, settling, and storage are used to further stabilize the electrolyte composition and provide continuous electrolyte supply for subsequent electrolysis. The purification process includes one or more of sulfidation purification, neutralization purification, oxidation iron removal, and adsorption purification; preferably, the purification process includes sulfidation purification to remove one or more heavy metal impurities from the filtrate, namely Ni, Co, Zn, Cu, and Pb.

[0021] In step 6, the washing process uses clean water with a liquid-to-solid ratio of 2:1 to 6:1, a washing time of 5 to 30 minutes, and 1 to 3 washes. After washing, the residual reagent content on the surface of the flotation concentrate is reduced. The washing liquid is then filtered and sent to the wastewater treatment plant. The pulp concentration is 20% to 50%, and the pulping time is 5 to 30 minutes.

[0022] In step 6, the wastewater generated during the preparation of the electrolyte is treated in a wastewater treatment plant, which includes a neutralization and sedimentation unit and a filter press unit. During the filter press, the diaphragm bags are cleaned, and the resulting washing wastewater is returned to the wastewater treatment plant. The liquid obtained after filter press enters the membrane treatment system, which separates concentrated water and purified water. The concentrated water is evaporated and disposed of, while the purified water from the membrane treatment is returned to the flotation concentrate washing process to remove residual reagents and soluble impurities from the surface of the flotation concentrate. The washing wastewater and the filter press washing wastewater are returned to the wastewater treatment plant, realizing the recycling of water within the electrolyte preparation and electrolysis system.

[0023] In step 7, the electrolyte is fed into the electrolytic cell for electrolysis at a temperature of 30°C to 50°C and a cathode current density of 300 A / m. 2 ~400 A / m 2 The cathode manganese deposition cycle is 20-30 hours. Compared with existing processing technologies, the features and advantages of this invention are:

[0024] 1. This invention employs a combined separation process of pre-selection, grinding and screening, high-intensity magnetic separation, and flotation to achieve the stepwise removal of coarse-grained gangue and fine-grained impurity minerals from rhodochrosite. Pre-selection removes some low-grade gangue and waste rock under coarse-grained conditions, reducing the subsequent grinding workload; high-intensity magnetic separation further utilizes the differences in mineral magnetic properties to remove weakly magnetic and non-magnetic impurities; and the flotation process deeply separates calcium-, magnesium-, silicon-, and aluminum-containing gangue minerals, thereby improving the grade of manganese concentrate and reducing impurity content.

[0025] 2. This invention effectively connects mineral processing and purification with subsequent electrolyte preparation processes, allowing flotation concentrate to be directly used to prepare electrolyte and further obtain electrolytic manganese metal products. The process flow is complete and has good continuity.

[0026] 3. The flotation process used in this invention is beneficial for reducing the content of impurities such as CaO, MgO, SiO2 and Al2O3, improving the quality of concentrate, and providing raw materials with higher grade and lower impurities for subsequent preparation of electrolyte.

[0027] 4. This invention reuses the clean water from membrane treatment in the flotation concentrate washing process, and returns the washing wastewater and filter press cloth washing wastewater to the wastewater treatment plant for further treatment, thus creating a closed-loop connection between flotation concentrate washing, filter press cloth washing, wastewater treatment, and membrane treatment. This design not only reduces fresh water consumption and wastewater discharge, but also ensures a stable water supply for the flotation concentrate washing process, thereby continuously removing residual reagents and soluble impurities from the surface of the flotation concentrate and reducing their adverse effects on subsequent sulfation, electrolyte stability, and the electrolysis process. Attached Figure Description

[0028] Figure 1 A schematic diagram of the process for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite using a two-stage pre-purification-liquid electrolysis method. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods; the reagents and materials described are commercially available unless otherwise specified, and the steps described are not a limitation on the reaction order; adjustments can be made to the steps after understanding the inventive essence of the present invention.

[0030] Example 1

[0031] A method for the synergistic preparation of metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite using a two-stage pre-purification and liquid electrolysis process, such as... Figure 1 As shown, the specific operation steps are as follows:

[0032] In this embodiment, the Mn grade in rhodochrosite is 18.78%, the SiO2 grade is 22.18%, the Al2O3 grade is 6.34%, the MgO grade is 13.28%, and the CaO grade is 12.76%.

[0033] 1. Sample preparation: Rhodochrosite is fed into a crusher via a conveyor belt and crushed to obtain rhodochrosite particles with a particle size of less than 50 mm.

[0034] 2. Pre-selection: The rhodochrosite particles with a particle size of less than 50 mm obtained in step 1 are fed into an X-ray transmission pre-selection device with a vibration frequency of 15 Hz, a light source voltage of 130 kV, and a current of 2.5 mA to obtain X-ray transmission pre-selected concentrate and tailings.

[0035] 3. Grinding and screening: The pre-selected concentrate obtained in step 2 is fed into a ball mill for grinding, and the content of -0.074 mm particle size in the grinding product is controlled to account for 85% of the total mass of the product, so as to obtain the grinding product.

[0036] 4. High-intensity magnetic separation: The grinding product obtained in step 3 is prepared into a slurry and then fed into a wet high-gradient magnetic separator with a magnetic field strength of 10000 Oe for separation to obtain magnetic concentrate and magnetic tailings.

[0037] 5. Flotation: Add a 3% sodium carbonate solution to the magnetic concentrate obtained in step 4 to adjust the pulp pH to 8 and control the pulp concentration to 35%. Then add 1000 g / t silicate ether amine collector to the pulp over 2 minutes for reverse flotation, with a skimming time of 5 minutes. After reverse flotation, the resulting froth product is the first-stage reverse flotation tailings, and the product in the tank is the first-stage reverse flotation concentrate. Add a 3% sodium carbonate solution to the first-stage reverse flotation concentrate, adjust the pulp pH to 9 at room temperature, then add 8 g / t sodium lignosulfonate depressant and 400 g / t quaternary ammonium salt collector, adjusting the pulp concentration to 20% over 3 minutes for second-stage direct flotation, with a skimming time of 6 minutes. After direct flotation, the resulting froth product is dried to obtain the second-stage direct flotation concentrate, and the product in the tank is the second-stage direct flotation tailings. The concentrate from the second-stage positive flotation has a Mn grade of 37.40%, a SiO2 grade of 3.14%, an Al2O3 grade of 2.17%, an MgO grade of 3.12%, and a CaO grade of 3.88%.

[0038] 6. Stabilization and preparation of electrolyte: The two-stage positive flotation concentrate obtained in step 5 is fed into a washing device for washing treatment. The water-to-solid ratio is 3:1, the washing time is 15 min, and the washing is performed twice to remove residual flotation reagents and some soluble impurities on the surface of the two-stage positive flotation concentrate. The washed material is then fed into a slurry tank for slurrying. The slurrying time is 15 min, and the slurry mass concentration is 25% to ensure uniform dispersion of the material. The slurry after slurrying is then fed into a chemical reaction tank to react with sulfuric acid. The reaction liquid-to-solid ratio is 5:1, the sulfuric acid concentration is 0.86 mol / L, the chemical reaction temperature is 70℃, and the chemical reaction time is 80 min, which converts manganese minerals into manganese sulfate and introduces them into the liquid phase. Subsequently, the chemically reacted slurry is fed into a filter press for solid-liquid separation. The resulting filtrate is purified and then sequentially sent to a settling tank and a high-level tank for settling and storage to reduce fluctuations in electrolyte composition, ultimately obtaining an electrolyte that meets the requirements for electrolysis. In this embodiment, the purification process employs sulfide purification. The washing wastewater from the second-stage direct flotation concentrate washing process and the cloth washing wastewater from the filter press process are returned to the wastewater treatment plant. After neutralization, sedimentation, filter press, and membrane treatment, the resulting purified water is returned to the second-stage direct flotation concentrate washing process as makeup water, while the resulting concentrated water is treated by evaporation.

[0039] 7. Finished Product Processing: The electrolyte obtained in step 6 is fed into an electrolytic cell for electrolysis at a temperature of 40℃ and a cathode current density of 350 A / m.2 The cathode manganese deposition cycle is 24 hours. After electrolysis, the obtained product is successively passivated, rinsed, dried and stripped to finally obtain electrolytic manganese metal product with a purity of 99.90%.

[0040] Example 2

[0041] A method for the synergistic preparation of metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite using a two-stage pre-purification and liquid electrolysis process is described below.

[0042] The method is the same as in Example 1, except that:

[0043] In this embodiment, the Mn grade in rhodochrosite is 22.64%, the SiO2 grade is 19.85%, the Al2O3 grade is 5.72%, the MgO grade is 10.46%, and the CaO grade is 9.38%.

[0044] 1. Sample preparation: Rhodochrosite is fed into a crusher via a conveyor belt and crushed to obtain rhodochrosite particles with a particle size of less than 50 mm.

[0045] 2. Pre-selection: The rhodochrosite particles with a particle size of less than 50 mm obtained in step 1 are fed into an X-ray transmission pre-selection device with a vibration frequency of 20 Hz, a light source voltage of 145 kV, and a current of 3.0 mA to obtain X-ray transmission pre-selected concentrate and tailings.

[0046] 3. Grinding and screening: The pre-selected concentrate obtained in step 2 is fed into a ball mill for grinding, and the content of -0.074 mm particle size in the grinding product is controlled to account for 88% of the total mass of the product, so as to obtain the grinding product.

[0047] 4. High-intensity magnetic separation: The grinding product obtained in step 3 is prepared into a slurry and then fed into a wet high-gradient magnetic separator with a magnetic field strength of 12000 Oe for separation to obtain magnetic concentrate and magnetic tailings.

[0048] 5. Flotation: Add a 2% sodium carbonate solution to the magnetic concentrate obtained in step 4 to adjust the pulp pH to 8 and control the pulp concentration to 33%. Then add 1100 g / t silicate ether amine collector to the pulp over 3 minutes for reverse flotation, with a skimming time of 5 minutes. After reverse flotation, the resulting froth product is the first-stage reverse flotation tailings, and the product in the tank is the first-stage reverse flotation concentrate. Add a 2% sodium carbonate solution to the first-stage reverse flotation concentrate, adjust the pulp pH to 9 at room temperature, then add 8 g / t sodium lignosulfonate depressant and 450 g / t quaternary ammonium salt collector, adjusting the pulp concentration to 24% over 3 minutes for second-stage direct flotation, with a skimming time of 7 minutes. After direct flotation, the resulting froth product is dried to obtain the second-stage direct flotation concentrate, and the product in the tank is the second-stage direct flotation tailings. The concentrate from the second-stage positive flotation has a Mn grade of 38.26%, a SiO2 grade of 1.92%, an Al2O3 grade of 1.94%, a MgO grade of 1.84%, and a CaO grade of 2.72%.

[0049] 6. Stabilization and preparation of electrolyte: The two-stage positive flotation concentrate obtained in step 5 is fed into a washing device for washing treatment. The water-to-solid ratio is 3:1, the washing time is 20 min, and the washing is repeated twice to remove residual flotation reagents and some soluble impurities on the surface of the two-stage positive flotation concentrate. The washed material is then fed into a slurry tank for slurrying. The slurrying time is 15 min, and the slurry mass concentration is 30% to ensure uniform dispersion of the material. The slurry after slurrying is fed into a chemical reaction tank to react with sulfuric acid. The reaction liquid-to-solid ratio is 5:1, the sulfuric acid concentration is 0.90 mol / L, the chemical reaction temperature is 65℃, and the chemical reaction time is 70 min, which converts manganese minerals into manganese sulfate and introduces them into the liquid phase. Subsequently, the chemically reacted slurry is fed into a filter press for solid-liquid separation. The resulting filtrate is purified and then sequentially sent to a settling tank and a high-level tank for settling and storage to reduce fluctuations in electrolyte composition, ultimately obtaining an electrolyte that meets the requirements for electrolysis. In this embodiment, the purification process employs sulfide purification. The washing wastewater from the second-stage direct flotation concentrate washing process and the cloth washing wastewater from the filter press process are returned to the wastewater treatment plant. After neutralization, sedimentation, filter press, and membrane treatment, the resulting purified water is returned to the second-stage direct flotation concentrate washing process as makeup water, while the resulting concentrated water is treated by evaporation.

[0050] 7. Electrolysis and Finished Product Processing: The electrolyte obtained in step 6 is fed into an electrolytic cell for electrolysis at a temperature of 38℃ and a cathode current density of 330 A / m. 2 The cathode manganese deposition cycle is 22 hours. After electrolysis, the obtained product is subjected to passivation, rinsing, drying and stripping treatment in sequence to finally obtain electrolytic manganese metal product with a purity of 99.92%.

[0051] Example 3

[0052] A method for the synergistic preparation of metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite using a two-stage pre-purification and liquid electrolysis process is described below.

[0053] The method is the same as in Example 1, except that:

[0054] In this embodiment, the Mn grade in rhodochrosite is 27.36%, the SiO2 grade is 17.42%, the Al2O3 grade is 4.95%, the MgO grade is 8.62%, and the CaO grade is 7.28%.

[0055] 1. Sample preparation: Rhodochrosite is fed into a crusher via a conveyor belt and crushed to obtain rhodochrosite particles with a particle size of less than 50 mm.

[0056] 2. Pre-selection: The rhodochrosite particles with a particle size of less than 50 mm obtained in step 1 are fed into an X-ray transmission pre-selection device with a vibration frequency of 25 Hz, a light source voltage of 160 kV, and a current of 3.2 mA to obtain X-ray transmission pre-selected concentrate and tailings.

[0057] 3. Grinding and screening: The pre-selected concentrate obtained in step 2 is fed into a ball mill for grinding, and the content of -0.074 mm particle size in the grinding product is controlled to account for 90% of the total mass of the product, so as to obtain the grinding product.

[0058] 4. High-intensity magnetic separation: The grinding product obtained in step 3 is prepared into a slurry and then fed into a wet high-gradient magnetic separator with a magnetic field strength of 16000 Oe for separation to obtain magnetic concentrate and magnetic tailings.

[0059] 5. Flotation: Add a 2% sodium carbonate solution to the magnetic concentrate obtained in step 4 to adjust the pulp pH to 8 and control the pulp concentration to 36%. Then add 1300 g / t silicate ether amine collector to the pulp over 3 minutes for reverse flotation, with a skimming time of 5 minutes. After reverse flotation, the resulting froth product is the first-stage reverse flotation tailings, and the product in the tank is the first-stage reverse flotation concentrate. Add a 2% sodium carbonate solution to the first-stage reverse flotation concentrate, adjust the pulp pH to 9 at room temperature, then add 10 g / t sodium lignosulfonate depressant and 550 g / t quaternary ammonium salt collector, adjusting the pulp concentration to 26% over 3 minutes for second-stage direct flotation, with a skimming time of 7 minutes. After direct flotation, the resulting froth product is dried to obtain the second-stage direct flotation concentrate, and the product in the tank is the second-stage direct flotation tailings. The concentrate from the second-stage positive flotation has a Mn grade of 39.48%, a SiO2 grade of 1.59%, an Al2O3 grade of 1.51%, a MgO grade of 1.76%, and a CaO grade of 2.13%.

[0060] 6. Stabilization and preparation of electrolyte: The two-stage positive flotation concentrate obtained in step 5 is fed into a washing device for washing treatment. The water-to-solid ratio is 4:1, the washing time is 20 min, and the washing is repeated twice to remove residual flotation reagents and some soluble impurities on the surface of the two-stage positive flotation concentrate. The washed material is then fed into a slurry tank for slurrying. The slurrying time is 15 min, and the slurry mass concentration is 35% to ensure uniform dispersion of the material. The slurry after slurrying is then fed into a chemical reaction tank to react with sulfuric acid. The reaction liquid-to-solid ratio is 6:1, the sulfuric acid concentration is 1.00 mol / L, the chemical reaction temperature is 75℃, and the chemical reaction time is 90 min, converting manganese minerals into manganese sulfate and introducing it into the liquid phase. Subsequently, the chemically reacted slurry is fed into a filter press for solid-liquid separation. The resulting filtrate is purified and then sequentially sent to a settling tank and a high-level tank for settling and storage to reduce fluctuations in electrolyte composition, ultimately obtaining an electrolyte that meets the requirements for electrolysis. In this embodiment, the purification process employs sulfide purification. The washing wastewater from the second-stage direct flotation concentrate washing process and the cloth washing wastewater from the filter press process are returned to the wastewater treatment plant. After neutralization, sedimentation, filter press, and membrane treatment, the resulting purified water is returned to the second-stage direct flotation concentrate washing process as makeup water, while the resulting concentrated water is treated by evaporation.

[0061] 7. Finished Product Processing: The electrolyte obtained in step 6 is fed into an electrolytic cell for electrolysis at a temperature of 40℃ and a cathode current density of 350 A / m. 2 The cathode manganese deposition cycle is 24 hours. After electrolysis, the obtained product is successively passivated, rinsed, dried and stripped to finally obtain electrolytic manganese metal product with a purity of 99.95%.

[0062] Example 4

[0063] A method for the synergistic preparation of metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite using a two-stage pre-purification and liquid electrolysis process is described below.

[0064] The method is the same as in Example 1, except that:

[0065] In this embodiment, the Mn grade in rhodochrosite is 30.13%, the SiO2 grade is 14.68%, the Al2O3 grade is 3.82%, the MgO grade is 6.54%, and the CaO grade is 5.92%.

[0066] 1. Sample preparation: Rhodochrosite is fed into a crusher via a conveyor belt and crushed to obtain rhodochrosite particles with a particle size of less than 50 mm.

[0067] 2. Pre-selection: The rhodochrosite particles with a particle size of less than 50 mm obtained in step 1 are fed into an X-ray transmission pre-selection device with a vibration frequency of 30 Hz, a light source voltage of 170 kV, and a current of 3.5 mA to obtain X-ray transmission pre-selected concentrate and tailings.

[0068] 3. Grinding and screening: The pre-selected concentrate obtained in step 2 is fed into a ball mill for grinding, and the content of -0.074 mm particle size in the grinding product is controlled to account for 92% of the total mass of the product, so as to obtain the grinding product.

[0069] 4. High-intensity magnetic separation: The grinding product obtained in step 3 is prepared into a slurry and then fed into a wet high-gradient magnetic separator with a magnetic field strength of 20,000 Oe for separation to obtain magnetic concentrate and magnetic tailings.

[0070] 5. Flotation: Add a 2% sodium carbonate solution to the magnetic concentrate obtained in step 4 to adjust the pulp pH to 8 and control the pulp concentration to 38%. Then add 1500 g / t silicate ether amine collector to the pulp over 3 minutes for reverse flotation, with a skimming time of 5 minutes. After reverse flotation, the resulting froth product is the first-stage reverse flotation tailings, and the product in the tank is the first-stage reverse flotation concentrate. Add a 2% sodium carbonate solution to the first-stage reverse flotation concentrate, adjust the pulp pH to 9 at room temperature, then add 12 g / t sodium lignosulfonate depressant and 650 g / t quaternary ammonium salt collector, adjusting the pulp concentration to 28% over 3 minutes for second-stage direct flotation, with a skimming time of 7 minutes. After direct flotation, the resulting froth product is dried to obtain the second-stage direct flotation concentrate, and the product in the tank is the second-stage direct flotation tailings. The concentrate from the second-stage positive flotation has a Mn grade of 42.12%, a SiO2 grade of 0.61%, an Al2O3 grade of 1.08%, a MgO grade of 0.64%, and a CaO grade of 1.19%.

[0071] 6. Stabilization and preparation of electrolyte: The flotation concentrate obtained in step 5 is fed into a washing device for washing treatment. The water-to-solid ratio is 5:1, the washing time is 30 min, and the washing is repeated 3 times to remove residual flotation reagents and some soluble impurities on the surface of the second-stage positive flotation concentrate. The washed material is then fed into a slurry tank for slurrying. The slurrying time is 15 min, and the slurry mass concentration is 40% to ensure uniform dispersion of the material. The slurry after slurrying is fed into a chemical reaction tank to react with sulfuric acid. The reaction liquid-to-solid ratio is 7:1, the sulfuric acid concentration is 1.20 mol / L, the chemical reaction temperature is 85℃, and the chemical reaction time is 120 min to convert manganese minerals into manganese sulfate and introduce it into the liquid phase. Subsequently, the chemically reacted slurry is fed into a filter press for solid-liquid separation. The resulting filtrate is purified and then sequentially sent to a settling tank and a high-level tank for settling and storage to reduce fluctuations in electrolyte composition, ultimately obtaining an electrolyte that meets the requirements for electrolysis. In this embodiment, the purification process employs sulfide purification. In this embodiment, the washing wastewater generated from the second-stage positive flotation concentrate washing process and the cloth washing wastewater generated during the filter press process are returned to the wastewater treatment plant. After neutralization, sedimentation, filter press, and membrane treatment, the resulting purified water is returned to the second-stage positive flotation concentrate washing process as makeup water, and the resulting concentrated water is treated by evaporation.

[0072] 7. Finished Product Processing: The electrolyte obtained in step 6 is fed into an electrolytic cell for electrolysis at a temperature of 45℃ and a cathode current density of 380 A / m. 2 The cathode manganese deposition cycle is 26 hours. After electrolysis, the obtained product is successively passivated, rinsed, dried and stripped to finally obtain electrolytic manganese metal product with a purity of 99.98%.

[0073] Comparative Example 1

[0074] A method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite, with the same specific operating steps as in Example 1, but with the following differences:

[0075] In step 6, the second-stage direct flotation concentrate obtained in step 5 is not washed with water. Instead, it is directly fed into a pulping tank for pulping for 15 minutes at a pulp concentration of 25% to ensure uniform material dispersion. The pulped concentrate is then fed into a chemical reaction tank to react with sulfuric acid at a liquid-to-solid ratio of 5:1, a sulfuric acid concentration of 0.86 mol / L, a reaction temperature of 70°C, and a reaction time of 80 minutes, converting manganese minerals into manganese sulfate and introducing it into the liquid phase. Subsequently, the resulting slurry is fed into a filter press for solid-liquid separation. The filtrate is purified and then sequentially sent to a settling tank and a high-level tank for settling and storage to obtain the electrolyte. In this comparative example, the purification process uses sulfide purification.

[0076] The resulting electrolyte was fed into an electrolytic cell for electrolysis at a temperature of 40℃ and a cathode current density of 350 A / m. 2 The cathode manganese deposition cycle is 24 hours. After electrolysis, the obtained product is subjected to passivation, rinsing, drying and stripping treatment in sequence to finally obtain electrolytic manganese metal product.

[0077] The purity of the electrolytic manganese product obtained in Comparative Example 1 was 98.70%.

[0078] Compared to Example 1, Comparative Example 1 did not perform water washing on the second-stage direct flotation concentrate. Residual flotation reagents and some soluble impurities on the surface of the concentrate directly entered the pulping and sulfation systems, leading to increased fluctuations in the composition of the resulting filtrate and adversely affecting subsequent purification and electrolysis processes. Ultimately, the purity of the electrolytic manganese product was lower than that of Example 1. This demonstrates that water washing of the second-stage direct flotation concentrate before sulfation helps reduce the adverse effects of residual flotation reagents and soluble impurities on the solution preparation and electrolysis processes, thereby improving the quality and production stability of the electrolytic manganese product.

[0079] Comparative Example 2

[0080] A method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite, with the same specific operating steps as in Example 4, but with the following differences:

[0081] In step 5, the flotation process does not use a single-stage reverse flotation followed by a two-stage forward flotation process, but instead employs a two-stage reverse flotation process. Specifically:

[0082] Add a 2% sodium carbonate solution to the magnetic concentrate obtained in step 4, adjust the slurry pH to 8 and control the slurry concentration to 38% at room temperature; then add 1500 g / t silicate ether amine collector to the slurry over 3 minutes for the first stage of reverse flotation, with a skimming time of 5 minutes. After the first stage of reverse flotation, the resulting froth product is the tailings from the first stage of reverse flotation, and the product in the tank is the concentrate from the first stage of reverse flotation.

[0083] The concentrate from the first stage of reverse flotation was further subjected to a second stage of reverse flotation, with the same pulp conditioning conditions as the first stage. Then, a mixed inhibitor of dextrin and carboxymethyl cellulose (2.5:1 ratio) at 700 g / t was added, along with a calcium-magnesium mixed amine collector at a dosage of 750 g / t. The addition time was 3 min, and the froth removal time was 7 min. After the second stage of reverse flotation, the resulting froth product was the tailings from the second stage. The product in the tank was dried to obtain the concentrate from both stages of reverse flotation.

[0084] The resulting two-stage reverse flotation concentrate had a Mn grade of 40.66%, a SiO2 grade of 1.17%, an Al2O3 grade of 1.43%, a MgO grade of 0.82%, and a CaO grade of 1.28%.

[0085] The two reverse flotation concentrates were then stabilized to prepare an electrolyte according to step 6 of Example 4, namely, water washing, pulping, sulfuric acid reaction, pressure filtration, purification treatment, settling and storage. The finished product was then processed according to step 7 of Example 4 to finally obtain an electrolytic manganese product with a purity of 99.81%.

[0086] Compared to Example 4, Comparative Example 2 employed a two-stage reverse flotation process, resulting in a decrease in the Mn grade of the concentrate from 42.12% to 40.66%, and higher contents of SiO2, Al2O3, MgO, and CaO compared to Example 4. Furthermore, the purity of the final electrolytic manganese product decreased from 99.98% to 99.81%. This demonstrates that the present invention, employing a one-stage reverse flotation followed by a two-stage direct flotation process, can remove calcium-, magnesium-, silicon-, and aluminum-containing gangue minerals while further enriching and recovering rhodochrosite, making the resulting concentrate more suitable for subsequent stabilization, solvent preparation, and electrolytic production of manganese.

Claims

1. A method for the synergistic preparation of metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification and liquid electrolysis process, characterized in that... Includes the following steps: (1) Sample preparation: Rhodochrosite was crushed to obtain rhodochrosite particles with a particle size of less than 100 mm; (2) Pre-selection: Rhodochrosite particles are conveyed to a separator via a conveyor belt for pre-selection to obtain pre-selected concentrate and pre-selected tailings; (3) Grinding and screening: Grind the pre-selected concentrate and control the content of -0.074 mm particle size in the grinding product to account for more than 75% of the total mass of the product to obtain the grinding product; (4) High-intensity magnetic separation: After the grinding products are prepared into slurry, high-intensity magnetic separation is carried out to obtain magnetic concentrate and magnetic tailings; (5) Flotation: The magnetic concentrate is slurry adjusted and then subjected to flotation. The flotation adopts a one-stage reverse flotation-two-stage forward flotation process to obtain flotation concentrate. (6) Stabilization preparation of electrolyte: The flotation concentrate is washed with water and pulped; the pulped slurry reacts with sulfuric acid to convert manganese minerals into manganese sulfate and enter the liquid phase; then the combined slurry is filtered by pressure, and the filtrate is purified, settled and stored to obtain an electrolyte that meets the requirements of electrolysis. (7) Finished product processing: The electrolyte is electrolyzed, and then passivated, rinsed, dried and stripped in sequence to finally obtain electrolytic manganese metal finished product with a purity of more than 99.70%.

2. The method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification-liquid electrolysis process according to claim 1, characterized in that, In step (1), the Mn grade in rhodochrosite is 18%~35%, the SiO2 grade is 13%~25%, the Al2O3 grade is 3%~10%, the MgO grade is 5%~16%, and the CaO grade is 5%~18%.

3. The method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification-liquid electrolysis process according to claim 1, characterized in that, In step (2), the sorting machine is an X-ray transmission pre-sorter; wherein the X-ray transmission pre-sorter has a conveyor belt width of 1.8 m, a conveyor belt speed of 1.5 m / s, a feed hopper vibration frequency of 10 Hz~40 Hz, a light source voltage of 120 kV~180 kV, and a current of 2 mA~4 mA.

4. The method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification-liquid electrolysis process according to claim 1, characterized in that, In step (4), the strong magnetic separation operation adopts a wet high gradient strong magnetic separator; wherein, the magnetic field strength of the wet high gradient strong magnetic separator is 8000 Oe~25000 Oe.

5. The method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification-liquid electrolysis process according to claim 1, characterized in that, In step (5), the flotation adopts a one-stage reverse flotation-two-stage forward flotation process; wherein, the one-stage reverse flotation is used to preferentially remove calcium-containing, magnesium-containing, silicon-containing and aluminum-containing gangue minerals, and the two-stage forward flotation is used to further enrich and recover rhodochrosite minerals, thereby reducing the content of weakly magnetic and non-magnetic impurities such as CaO, MgO, SiO2 and Al2O3, and improving the grade of manganese concentrate.

6. The method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification-liquid electrolysis process according to claim 1, characterized in that, The first stage of reverse flotation process in step (5) is as follows: the magnetic concentrate is added to a sodium carbonate solution with a mass percentage concentration of 2% to 5%, and the slurry is adjusted at room temperature until the pH is 8 and the slurry concentration is controlled at 30% to 40%; then 800 g / t to 1600 g / t of silicate ether amine collector is added for 1 min to 4 min, and the first stage of reverse flotation is carried out, with a frothing time of 5 min; after the reverse flotation is completed, the froth product obtained is the first stage rough reverse flotation tailings, and the product in the tank is the first stage rough reverse flotation concentrate; The two-stage positive flotation process in step (5) is as follows: the first-stage rough reverse flotation concentrate is added to a sodium carbonate solution with a mass percentage concentration of 2% to 5%, and the slurry is adjusted to pH=9 at room temperature; then 5 g / t to 15 g / t sodium lignosulfonate inhibitor and 300 g / t to 700 g / t quaternary ammonium salt collector are added to carry out the second-stage positive flotation to recover manganese minerals. The slurry concentration is controlled at 20% to 30%, the reagent addition time is 3 min, and the froth removal time is 5 min to 7 min; after the positive flotation is completed, the obtained froth product is dried to obtain the second-stage positive flotation concentrate, and the product in the tank is the second-stage positive flotation tailings.

7. The method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification-liquid electrolysis process according to claim 1, characterized in that, In step (6), water washing is used to remove residual reagents and some soluble impurities from the surface of the flotation concentrate; slurrying is used to prepare a uniform slurry; the manganese minerals in the slurry-processed flotation concentrate react with sulfuric acid in a chemical combination tank to generate manganese sulfate, which then enters the solution; pressure filtration is used to achieve solid-liquid separation; purification, settling, and storage are used to further stabilize the electrolyte composition and provide continuous liquid supply conditions for subsequent electrolysis; wherein, purification includes one or more of sulfidation purification, neutralization and impurity removal, oxidation and iron removal, and adsorption and impurity removal, used to remove one or more heavy metal impurities of Ni, Co, Zn, Cu, and Pb from the filtrate.

8. The method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification-liquid electrolysis process according to claim 1, characterized in that, In step (6), the wastewater generated during the preparation of the electrolyte enters the sewage treatment station for treatment. The sewage treatment station includes a neutralization and sedimentation unit and a filter press unit. During the filter press process, the diaphragm bag is cleaned, and the resulting cloth washing wastewater is returned to the sewage treatment station for treatment. The liquid obtained after filter press enters the membrane treatment system, where the membrane treatment system separates concentrated water and clear water. The concentrated water is evaporated and disposed of, while the membrane treatment clear water is returned to the flotation concentrate washing process to remove residual reagents and soluble impurities from the surface of the flotation concentrate. The washing wastewater and the filter press cloth washing wastewater enter the sewage treatment station to realize the recycling of water in the electrolyte preparation and electrolysis system.

9. The method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification-liquid electrolysis process according to claim 1, characterized in that, In step (6), the water washing is carried out with clean water aging treatment, the water washing liquid-solid ratio is 2:1 to 6:1, the water washing time is 5 min to 30 min, and the water washing is repeated 1 to 3 times; after water washing, the content of residual reagents on the surface of the flotation concentrate is reduced, and the washing liquid is filtered by pressure and then enters the sewage treatment station; the slurry mass concentration is 20% to 50%, and the pulping time is 5 min to 30 min; the reaction of sulfuric acid with the pulped flotation concentrate is carried out in the chemical reaction tank, the liquid-solid ratio of the reaction is 4:1 to 8:1, the sulfuric acid concentration is 0.6 mol / L to 1.4 mol / L, the chemical reaction temperature is 40℃ to 90℃, and the chemical reaction time is 30 min to 150 min.

10. The method for preparing metallic manganese from high-calcium, high-magnesium, low-grade rhodochrosite through a two-stage pre-purification-liquid electrolysis process according to claim 1, characterized in that, In step (7), the electrolyte is fed into the electrolytic cell for electrolysis at a temperature of 30°C to 50°C and a cathode current density of 300 A / m. 2 ~400 A / m 2 The cathode manganese deposition cycle is 20 h to 30 h.

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