Electrolytic Manganese Metal Production Research Articles

Highly efficient CO2 mineralization: Mechanisms and feasibility of utilizing electrolytic manganese residue as a feedstock and implementing ammonia recycling

Electrolytic manganese residue (EMR) and CO2 emissions from the electrolytic manganese metal (EMM) production process present significant challenges to achieving cleaner production within the industry. Given the high capacity for CO2 sequestration and the stability of the sequestered forms, CO2 mineralization methods utilizing minerals or industrial residues have garnered considerable research interest. The efficacy of such methods is fundamentally dependent on the properties of the materials employed. EMR, due to its calcium sulfate dihydrate (CaSO4·2H2O) content, possesses an intrinsic potential for CO2 solidification. In this study, we propose a novel method for CO2 mineralization utilizing EMR, coupled with NH3·H2O recycling. Experimental results indicated that under conditions of a reaction temperature of 55 °C and a pH of approximately 8, each ton of EMR can sequester 0.16 t of CO2, with equilibrium achieved within 10 min. The mineralization mechanism was elucidated using SEM, TG curves, and XRD analyses, which revealed that Ca2+ ions are initially leached from CaSO4·2H2O in the EMR, subsequently precipitating with CO32− ions to form CaCO3. This CaCO3 layer effectively covers the surface of CaSO4·2H2O, inhibiting further Ca2+ release and stabilizing the reaction equilibrium. Furthermore, the ammonia in the solution is regenerated into NH3·H2O, facilitating its reuse and preventing secondary pollution. The utilization of EMR for CO2 mineralization not only mitigates carbon emissions in the EMM production process but also promotes environmentally sustainable practices in the industry. This study highlights a promising pathway towards achieving carbon neutrality and cleaner production in electrolytic manganese production.

Life cycle assessment of electrolytic manganese metal production

Manganese is an indispensable metal widely used in various fields. China ranks as the fourth-largest producer of manganese ore and the largest producer of electrolytic manganese metal (EMM). However, EMM production is linked to high energy consumption and pollution. This study conducts a life cycle assessment (LCA) of EMM production in the Manganese Triangle region of China to comprehensively evaluate its environmental impact. Results show that Human carcinogenic toxicity, mainly from electricity generation (65.3 %) and mining activities (24.4 %), is the most significant environmental impact. Chromium (VI) is identified as the predominant hazardous substance, contributing up to 91 % to Human carcinogenic toxicity. Endpoint results estimate that the production of 1 t of EMM results in 1.01E-02 DALY of harm to human health, 1.97E-05 species.yr of harm to the ecosystem, and $227.15 worth of resource depletion. Simulation scenarios demonstrate that replacing thermal power with hydropower can reduce environmental pollution by over 90 %. Finally, based on the findings, technical measures for promoting clean production of EMM were proposed.

Enhanced removal of Pb from electrolytic manganese anode slime and preparation of chemical MnO2

ABSTRACT Electrolytic manganese anode slime (EMAS) is produced during the production of electrolytic manganese metal. In this study, a method based on vacuum carbothermal reduction was used for Pb removal in EMAS. A Pb-removal efficiency of 99.85% and MnO purity in EMAS of 97.34 wt.% were obtained for a reduction temperature of 950°C and a carbon mass ratio of 10% for a holding time of 100 min. The dense structure of the EMAS was destroyed, a large number of multidimensional pores and cracks were formed, and the Pb-containing compound was reduced to elemental Pb by the vacuum carbothermal reduction. A recovery efficiency for chemical MnO2 of 36.6% was obtained via preparation from Pb-removed EMAS through the ‘roasting-pickling disproportionation’ process, with an acid washing time of 100 min, acid washing temperature of 70°C, H2SO4 concentration of 0.8 mol·L−1, liquid–solid mass ratio of 7 mL·g−1, calcination temperature of 60°C and calcination time of 2.5 h. Moreover, the crystal form of the prepared chemical MnO2 was found to be basically the same as that of electrolytic MnO2, and its specific surface area, micropore volume and discharge capacity were all higher than that of electrolytic MnO2. This study provides a new method for Pb removal and recycling for EMAS. Highlights Vacuum carbothermal reduction method was used for Pb removal in EMAS. The removal efficiency of Pb was 99.85%. Chemical MnO2 with excellent discharge performance was prepared using treated EMAS. This study provides a new method for EMAS resource utilization.

Efficient and clean manganese electrowinning in an anion-exchange membrane electrolyzer by pulse current electrodeposition method

Manganese electrolysis experiments were carried out in an anion-exchange membrane (AEM) electrolyzer employing pulse current (PC) to develop a novel approach for Mn electrowinning. The effects of pulse frequency, duty radio, average cathodic current density, SeO2 concentration and electrolysis time on electrowinning indices were investigated. The morphology, crystalline structure, element distribution and chemical composition of Mn deposits were analyzed employing field emission scanning electron microscopy, X-ray diffraction, electron probe microanalysis, inductively coupled plasma/optical emission spectroscopy and energy dispersive spectroscopy. The experimental results indicated that the electrolysis conditions affected the surface morphology in varying degrees, while all the Mn deposits showed α-Mn structure. By optimizing the electrolysis conditions, the mass transfer limitation of Mn2+ was significantly relieved, the deposition of metallic Mn was obviously improved, and the current efficiency (CE) of 86.45% and the specific energy consumption (SEC) of 4284 kW h t−1 were obtained after electrowinning for 12 h. Compared with the traditional electrowinning technology, the CE increased by about 15%, the SEC declined by about 23% and the per unit yield was promoted by about 56% after employing the approach proposed in this work, which would realize a significant reduction in the waste and pollutant generated during the electrolytic manganese metal production process. The approach of Mn electrowinning in an AEM electrolyzer by PC electrodeposition is recommended as an efficient and clean way.

Hazard-free treatment of electrolytic manganese residue and recovery of manganese using low temperature roasting-water washing process

A combined low-temperature-roasting and water-washing process is investigated as a hazard-free method to treat electrolytic manganese residue (EMR) and recover manganese. In this study, the phase transformation characteristics and a thermodynamics analysis of the low temperature roasting process of EMR are evaluated. In addition, the effects of temperature and time on the phase transformation of EMR in the roasting process and the washing characteristics of roasted EMR samples are also investigated. Results reveal that some unstable phases within EMR are transformed into more stable phases depending on the treatment time/temperature conditions used and EMR roasted for 60 min at 600 °C (R60min/600°C) exhibit the highest rate of manganese recovery, 67.12 %. After 25 min of deionized water washing, the concentration of manganese in solution from R60min/600°C material become stable, whereas after 6 washing cycles the concentration of manganese in the solution is < 0.005 g/L. The R60min/600°C material with three wash cycles results in a manganese-water solution concentration that is suitable for use in electrolytic manganese metal production. Finally, toxicity leaching tests show that the concentrations of ions present in the leaching solution are all lower than the regulatory limits mandated by the Chinese Integrated Wastewater Discharge Standard GB 8978−1996.

Pure water leaching soluble manganese from electrolytic manganese residue: Leaching kinetics model analysis and characterization

Electrolytic manganese residue (EMR) is a solid waste that generated in electrolytic manganese metal production, which would not only contaminate the environment due it contains soluble manganese, but occupy a large amount of farmlands as well. Hence, recovering manganese from EMR using economical method is the key to achieve the targets of resource recycling and solid waste harmless treatment. In this paper, pure water was used to leach soluble manganese out from EMR. Leaching kinetics model of manganese were established and examined, characteristics of EMR before and after leaching were analyzed by XRF, XRD, EPMA-WDS and SEM. The results revealed that the apparent activated energy (E) during the leaching processes was 11.17 ± 2.02 kJ/mol and the slope in fitting line of Arrhenius equation was −1.343, which indicated that the leaching kinetic model was appropriate and the rate determining step was diffusion process, that is, Mn2+ migrate into bulk solution from diffusion layer. The main crystal phases in EMR are quartz (SiO2) and calcium sulfate (CaSO4·nH2O) (n = 0.5 or 2), but the distribution relationship between SiO2 and CaSO4·nH2O was not regular. Mn is in the form of “film” covered in CaSO4 bar in EMR. High temperature and high volume of water could promote Mn2+ transport process. The optimal leaching condition was S:L (Solid : Liquid)1:4, temperature was 24 °C and the agitation rate was 300 r/min when combined the cost and efficiency, and 83.35 % soluble manganese can be leached out from EMR.

Life cycle assessment of electrolytic manganese metal production

Electrolytic manganese metal is widely used in various industrial fields, especially in the steel industry because of its characteristics. However, Electrolytic manganese metal production is one of the industries with high resource and energy consumption and substantial waste discharge. The study quantified the environmental performance of electrolytic manganese metal production by conducting a life cycle assessment using the ReCiPe2016 method. Uncertainty analysis via Monte-Carlo simulation was also implemented. Environmental burden was mainly ascribed to manganese resource-related production processes and electricity generation. Although production in China has progressed compared with the previous years, a gap remains compared with South Africa’s use of selenium-free technology. Analysis of coal-based electricity generation replaced by other renewable energy sources showed considerable environmental benefits. This study aims to provide information for the improvement of electrolytic manganese metal production. The reduction of the environmental burdens of electrolytic manganese metal production can be achieved by utilizing an advanced production technology to control the amount of raw materials and improve resource efficiency, recycling resources in waste, and converting coal-based electricity into other renewable alternatives (e.g., hydropower, wind, and solar energy).

Novel hydro-electrometallurgical technology for simultaneous production of manganese metal, electrolytic manganese dioxide, and manganese sulfate monohydrate

The main stages of a novel hydro-electrometallurgical technology for simultaneous production of electrolytic manganese metal, electrolytic γ-MnO2, and manganese sulfate monohydrate (MnSO4∙H2O) were tested at a large laboratory scale. The unified flow sheet comprised large and small process loops. The large loop included: concentrated sulfuric acid leaching of ore obtained by high-temperature reduction of manganese oxide ore; hydrolytic and sulfide purification of MnSO4 solution; production of crystalline manganese sulfate monohydrate obtained by high-temperature autoclave treatment of purified concentrated MnSO4 solution; feeding of hot spent MnSO4 solution from the autoclave as anolyte to an AMI-7001S anion membrane-separated electrochemical reactor where γ-MnO2 was produced on titanium anodes. The small process loop included preparation and correction of the catholyte composition using MnSO4∙H2O crystallized in the autoclave, from which electrolytic manganese metal was deposited on titanium cathodes. A heat pump was used to maintain the necessary temperature difference between the anolyte and catholyte. The energy consumed by the heat pump was half that obtained using an electrical current heating device. Electrical power consumptions for the production of manganese metal, manganese dioxide, and manganese sulfate monohydrate were 9.67 Wh/g, 3.75 Wh/g, and 0.884 Wh/g, respectively.

Reductive recovery of manganese from low-grade manganese dioxide ore using toxic nitrocellulose acid wastewater as reductant

The hydrometallurgical strategy of extracting Mn from low-grade Mn ores has attracted attention for the production of electrolytic manganese metal (EMM). In this work, the reductive dissolution of low-grade MnO2 ores using toxic nitrocellulose acidic wastewater (NAW) as a reductant was investigated for the first time. Under the optimized conditions of an MnO2 ore dosage of 100 g·L−1, an ore particle size of −200 mesh, concentrated H2SO4-to-NAW volume ratio of 0.12, reaction temperature of 90°C, stirring speed at 160 r·min−1, and a contact time of 120 min, the reductive leaching efficiency of Mn and the total organic carbon (TOC) removal efficiency of NAW reached 97.4% and 98.5%, respectively. The residual TOC of 31.6 mg·L−1 did not adversely affect the preparation of EMM. The current process offers a feasible route for the concurrent realization of the reductive leaching of Mn and the treatment of toxic wastewater via a simple one-step process.

Enhanced discharge performance of electrolytic manganese anode slime using calcination and pickling approach

Electrolytic manganese anode slime (EMAS) is a solid waste found in the anode chamber during the production of electrolytic manganese metal, which mainly contains high concentration of manganese and other impurities. In EMAS, γ-MnO2 and δ-MnO2 turned into α-MnO2 after calcination, and the oxide can be dissolved by pickling. The results showed that the specific surface area of EMAS increased from 33.11m2·g−1 to 93.53m2·g−1, and the micropore volume increased from 0.0129cm3·g−1 to 0.0362cm3·g−1, as well as the specific capacity and the Open Circuit Voltage (OCV) of EMAS were 249.65 mAh·g−1 and 1.60V, respectively, under the condition of calcination temperature 400°C, calcination time 1h, sulfuric acid 1mol·L−1, pickling temperature 25°C, pickling time 0.5h, and liquid-to-solid ratio 8:1.

Mn bio-dissolution from low-grade MnO2 ore and simultaneous Fe precipitation in presence of waste electrolytic manganese anolyte as nitrogen source and iron scavenger

A bioleachate containing high-content Mn and low-content Fe is required for the production of electrolytic manganese metal (EMM). To produce the qualified bioleachate, bioleaching of Mn from a low-grade MnO2 ore by a mixed autotrophic culture in presence of combined energy matters of pyrite and sulfur and simultaneous removal of Fe using waste electrolytic manganese anolyte (WEMA) containing high concentration of NH4+ as both nitrogen source and iron scavenger were investigated. The optimal conditions for both the maximum Mn release from the MnO2 ore and the maximum Fe precipitation from the bioleachate were determined via Plackett-Burman design, Steepest Ascent design and Box-Behnken design, which were listed as follows: 6% (v/v) of WEMA addition, 140 rpm of shaking speed, 250 mesh of ore particle size, 1.0 g L−1 of KH2PO4, pH value adjustment at 2.4, ratio of pyrite to sulfur at 14:10 (g·L−1), incubation temperature at 31 °C, and bioleaching period of 14 days at a fixed pulp density of 100 g L−1. The predicted values were 79.6% for the Mn extraction efficiency and 0.69 g L−1 for the total Fe residual concentration respectively, being very close to the measured values of 78.5% and 0.73 g L−1 in the confirmation experiments. The addition of 6% WEMA instead of (NH4)2SO4 resulted in an increase of 41% in the cell density from 1.20 × 108 to 1.69 × 108 mL−1 after 14 days of culture, displaying that the WEMA was competent to be an nitrogen source for the bioleaching. On the other hand, the addition of WEMA enhanced the formation of more ammoniojarosite to greatly reduce the Fe residual concentration from 2.19 to 0.73 g L−1, accompanying 7% of loss rate in Mn extraction due to possible Mn adsorption onto the ammoniojarosite. The present study demonstrated that the WEMA as a byproduct of EMM industry is qualified to be both the nitrogen source for efficient bioleaching of low grade MnO2 ore and the Fe scavenger for simultaneous removal of Fe from the bioleachate, which is advantageous for both reduction of bioleaching cost and the closed loop recycling of waste in preparation of EMM.

Simultaneous oxidative degradation of toxic acid wastewater from production of nitrocellulose and release of Mn2+ from low-grade MnO2 ore as oxidant

BACKGROUND To develop low cost and simple treatment process is necessary for the toxic organic effluents. This work investigated the feasibility of the oxidative degradation of toxic nitrocellulose acid wastewater (NAW) using low-grade MnO2 ore as a cheap oxidant and the simultaneous release of Mn2+ for preparation of electrolytic manganese metal (EMM). RESULTS Under optimal conditions of 100 g L−1 MnO2 ore, 200-mesh ore particles, concentrated H2SO4 to NAW ratio of 0.12:1, contact time of 120 min, stirring speed of 160 rpm and temperature of 90 °C, the total organic carbon (TOC) removal of the NAW and Mn release efficiency reached 98% and 97%, respectively. The TOC removal was significantly correlated with the release of Mn. The inert layer model best described the extraction behavior of Mn and apparent activation energy was 54.1 kJ mol −1. Concomitant with TOC removal, the degradation of polysaccharide, phenol, protein and nitrocellulose occurred; meanwhile, the MnO2 totally dissolved owing to reductive extraction of Mn. CONCLUSION A highly significant correlation occurred between TOC removal and Mn2+ release, suggesting a reciprocal causation. The present process was competent to simultaneously realize oxidation degradation of NAW and reductive dissolution of Mn2+ for EMM production, displaying a promising application prospect.

Electrolytic manganese metal production from manganese carbonate precipitate

The recovery of manganese metal from manganese carbonate precipitate by leaching–purification–electrowinning was studied. The manganese carbonate precipitate from Baja Mining Corp.'s El Boleo project was readily leached into acidic ammonium sulfate solution. The manganese extraction reached 99.7%. The manganese leachate was purified using ammonium sulfide to remove harmful impurities (Ni, Co, Cd, Cu and etc.). Manganese electrowinning was conducted in a diaphragm cell designed to eliminate edge effects and improve manganese deposition. The addition of polyacrylamide polymer had a significant leveling effect on manganese electrodeposition. However it increased the deposit internal stress and even resulted in cracking of manganese deposits at a high dosage. With increasing polyacrylamide polymer concentration, current density, and pH, the manganese current efficiency first increased, reached a maximum value and finally decreased. The manganese current efficiency decreased with increasing deposition time as the deposit became rougher and the real current density deviated from its ideal value. A reasonable catholyte circulation rate is important to maintain the optimum manganese electrodeposition. The presence of chloride in solution has a little effect on manganese deposition in its concentration range from 0 to 2g/L. The diaphragm selection as an important part of the cell design was analyzed.

On the influence of solution composition and operating conditions on the of anodic dissolution of ferromanganese in the process of the production of electrolytic manganese metal

On the influence of solution composition and operating conditions on the of anodic dissolution of ferromanganese in the process of the production of electrolytic manganese metal

Utilization of Electrolytic Manganese Residues in Production of Porous Ceramics

Electrolytic manganese residues (EMR) are one of industrial by‐products generated during the production of electrolytic manganese metal. To reduce the EMR hazard to environment and invent value‐added materials, porous ceramics were prepared by the pore‐forming method with EMR and various additives. The influences of the incorporation of different additives, sintering temperature, and molding pressure on properties of porous ceramics were investigated. Properties such as apparent porosity, water absorption, bulk density, and compression strength have been measured. The EMR‐based porous ceramics were also characterized by XRD, SEM, BET‐specific surface area, and BJH pore size distribution measurement. It revealed that the appropriate mode was the sample containing 20 wt% carbon powder, 7.5 wt% dolomite, and 5 wt% kaoline, under which the ceramics with the properties of high apparent porosity (69.70%), high compressive strength (6.97 MPa), and good acidity–alkali stability were obtained successfully. The comprehensive performance of EMR‐based porous ceramics makes them advantageous to use as nonhazardous and valuable materials showing promising potential applications, which not only is a promising new approach to improve the resource utilization of EMR but also can promote the manganese industry's sustainable and healthy development and protect and improve ecological environment.

The Process and Mechanism of Electrolytic Manganese Anode Slime Lead Removal

Production of electrolytic manganese metal inevitably produces a certain amount of solid wasteelectrolytic manganese anode slime, with a high manganese content, but its difficult to recycle due to the presence of other impurities. Firstly, the washing method was used to remove the anode slime soluble salts, then its chemical composition and phase were analyzed. The flame atomic absorption spectrometer and X-ray fluorescence (XRF) analysis showed the anode slime mainly contained Mn, Pb, Ca, Fe, Cr, K, Se and other metal elements, with the average manganese content 45% and the lead 3.5%;X-ray diffraction (XRD) preliminary analysis showed that the anode slime was a colloidal system mainly containing the spinel structure of MnO2 and complex salts PbMn8O16xH2O phase, by high temperature roasting, the anode slime transformed from hexagonal system to cubic system , and the basic structure unit from edges connection to surfaces connection,the change of length,angle and fracture of manganese-oxygen bond provided the channel for the lead leaching;TG-DTA analysis showed that anode slime was dominated by water loss below 400°C,and started to lose oxygen beyond 425°C, and clear endothermic peak was observed at 500°C and 700°C, which showed the anode slime crystal structure changed at 500°C, anode slime weight loss tending to be gentle with some Mn2O3 generation at 700°C, and roasted crystal stabilizing to Mn2O3. Preliminary roasting and leaching purification technology route was proposed according to the above analysis results, and analysis of the purification process related factors was made. Under the condition of natural ventilation, anode slime was roasted at 700°C, and fully leached in 2mol/L HAc , with liquid-solid ratio 10:1, then leached anode slime was characterized by XRD and flame atomic absorption test, the results showed that anode slime manganese content increased from 45% to 67.5%, the lead content decreased from 3.5% to 0.1%, XRD indicated that the anode slime existing phase was Mn2O3. Anode slime after purification treatment can be further used for battery manganese source material, which provides an effective approach for the recovery of manganese anode slime utilization.

Analysis of pollution materials generated from electrolytic manganese industries in China

There are 202 electrolytic manganese metal (EMM) industries in China with a total capacity of 1.88 million tons in 2008. This accounts for 98.58% of the world's overall capacity of EMM production. The industries generate a huge number of pollutants. To ascertain the factors causing these pollutants in the EMM industries in China, and cost-effective ways to reduce this pollution, a study was carried out at one of the largest Chinese EMM industries with the best operation practice from September 2005 to June 2007. Material and substance balances were established on the basis of gathering data through on-site measurement and auditing. Analyses of the pollution materials were subsequently conducted. The results showed: (1) for manganese, 71.9% enters the product, i.e. electrolytic manganese, 12.6% enters anode mud, 13.7% enters residues and 1.8% enters wastewater (before treatment); (2) for chromium, 2.4% enters the product and 97.6% enters wastewater; (3) for selenium, 60.7% enters the product, 22.3% enters anode mud and 17% enters residues; (4) for ammonia, 52.36% enters wastewater, 1.19% enters anode mud, 44.09% enters residues and 2.36% was evaporated and (5) for SO 4 2−, 44.5% enters wastewater, 0.2% enters anode mud and 55.3% enters residues. Manganese residues are the largest and most dangerous waste stream of the EMM industry. Use of selenium in large quantities constitutes potentially severe environmental risks. The best way to curtail environmental pollution from the industry is to apply new and modern technologies to cut off the pollution before it is generated.