High-carbon Ferromanganese Research Articles

Eco-friendly low-carbon manganese ferroalloy production for cleaner steel technologies

Global steel production, a major contributor to anthropogenic carbon dioxide, heavily relies on manganese, a key ingredient that significantly impacts the carbon footprint during the production of high-carbon ferromanganese. A single-step generation of low-carbon ferromanganese (LC-FeMn) from manganese ore in an electric arc furnace (EAF) was investigated. The theoretical and experimental investigations helped to balance the required and supplied energy. The process sustainability was predicted based on the enthalpy of the reaction. Pre-reduction of manganese ore decreased energy consumption in the smelting process and saved raw materials costs. The simulation studies revealed a significant effect of lime and silica on the slag-metal equilibrium. It further confirmed the best-reducing condition with the basicity 1.5–1.77 by smelting tests in EAF. Experimental results showed an optimal charge mixture comprising appropriate ratios of ore:SiMn:lime ratio, producing a standard-grade product. Simultaneous melting and smelting sensibly used the exothermic heat, consuming 410–880 kWh/ton, much lower than the international benchmark, i.e. approximately 2000 kWh/ton. The characterization of resulting slags corroborated the advantages of the manganese ore pre-reduction on the energy and reductant consumption, alloy grade, and slag characteristics. The present study's findings can potentially contribute to the ongoing low-carbon initiatives of steel.

The effect of petrographically determined parameters on reductant reactivity in the production of high-carbon ferromanganese

In pyrometallurgical processes, metal oxides are reduced from molten slag through carbothermic reduction. It is of interest to evaluate the reactivity of the carbonaceous materials towards substances such as slag. Characterization techniques such as coal petrography can provide insight into the influence of feed coal properties and how they potentially dictate reductant performance. This study aimed to compare the petrographically determined organic composition of coal to reductant reactivity. Two South African medium-rank C bituminous coals and one anthracite sample were investigated together with high-carbon ferromanganese industrial slag. The reductant reactivity tests were conducted at 1500°C in a muffle furnace to assess the potential of carbonaceous reductant in reacting with the main slag components. SEM-EDS was applied to understand the extent of MnO (and to a lesser extent, SiO2) reduction from the slag. Coal 2, consisting of a greater proportion of vitrinite (59.5 vol% on a mineral matter-free basis and 54.7 vol% including mineral matter) was the most reactive reductant. The anthracite sample, with the highest inert maceral proportions (71.8 vol% including mineral matter and 76.8 vol% on a mineral matter-free basis), was the least reactive reductant.

Oxidation and Fume Formation from Liquid Silicomanganese Alloys Exposed to Atmospheres Containing Moisture

In industrial applications and laboratory studies, it has been shown that the use of water spray may significantly reduce the amount of fume generated from the oxidation process of liquid high carbon ferromanganese alloy. However, in our recent study, it was shown that the oxidation rate of liquid silicon alloy increases with increasing water content in the atmosphere. Therefore, in this paper, the effect of moisture on the oxidation and fume formation of a liquid silicomanganese alloy was investigated. The fuming rate, fume characteristics, and experimental observations from wet air experiments on the silicomanganese melt were compared with those obtained from dry air experiments, and with the results of wet air experiments conducted on high carbon ferromanganese and silicon melts. In addition, the oxidation process of the silicomanganese and high carbon ferromanganese melts was modeled under the experimental conditions, using FactSage 8.1 thermochemical software, to better understand the equilibrium thermodynamic principles of the experimental results. In general, there was good agreement between the simulated and experimentally observed oxidation behavior of silicomanganese and high carbon ferromanganese melts under moist air conditions.

THERMODYNAMIC SIMULATION OF SILICOTHERMAL METHOD FOR PRODUCTION OF MEDIUM CARBON MANGANESE IN A CONVERTER

The widespread use of manganese in the production of steel somewhat limits its use in the deoxidation of low-carbon steel grades due to the use of manganese, mainly in the form of high-carbon ferromanganese. Thermodynamic modeling of equilibrium in a complex heterogeneous Mn-Si-Fe-P-O-C slag-metal-gas system was carried out for a detailed study of the behavior of metal and slag components for each period separately using the technology of silicothermal reduction of manganese oxides from slag in an envelope with bottom blast. An analysis of the calculated data showed a decrease in the silicon content from 16.05% in the starting material to 0.7 in the final ferromanganese. The carbon content decreases slightly from 1.72 to 1.28%. The manganese content increases from 67.25% in the starting material to 83.8% in the final ferromanganese. For phosphorus, an increase in content is observed in all periods. To achieve acceptable concentrations of phosphorus in the metal, it is necessary to use low-phosphorus initial charge materials. The results of theoretical studies indicate the prospects for further development of the technology for decarburization of high-carbon manganese melts using blowing with gaseous oxygen and treatment with slag melts of a certain composition.

Primary Study on Medium and Low Carbon Ferromanganese Production by Blowing CO2-O2 Mixtures in Converter

The production of medium- and low-carbon ferromanganese (M-LCFeMn) using the converter method has not been industrialized to date in China due to the high manganese loss and serious erosion of the furnace lining. To solve the above problems and to improve the refining technology of M-LCFeMn, the introduction of CO2 gas into the traditional converter process is proposed. In this study, the oxidation behavior of C and Mn in various conditions was analyzed by blowing different proportions of CO2-O2 mixed gas into the high-carbon ferromanganese (HCFeMn) melt. The results showed that it is feasible to make M-CFeMn by blowing CO2-O2 mixtures, and the Mn loss can be effectively reduced during the decarburization process. It is considered that when the proportion of CO2 reaches 25%, the mixed gas has the best effect on the decarburization and manganese preservation under current experimental situation. Two hypotheses and corresponding rate formulas of decarburization kinetics by using pure oxygen are put forward, and the effect of CO2 on the kinetics of decarburization was studied according to different hypotheses.

Study of Manganese Recovery in the CaO-SiO<sub>2</sub>-MgO-Al<sub>2</sub>O<sub>3</sub>-MnO-Fe<sub>2</sub>O<sub>3</sub> System by Thermodynamic Simulation

The results of thermodynamic simulation of the manganese recovery in the CaO-SiO2-MgO-Al2O3-MnO-Fe2O3 system by carbon are presented. Parameters of the initial system are temperature range 1400-at a step of , a total pressure of 0.1 MPa, and N2. The composition of the oxide system is corresponded by the manganese ore (wt %) 1.1 MnO2, 44.3 MnO, 28.4 CaO, 9.3 SiO2, 5.4 MgO, 0.3 Al2O3, 11.2 Fe2O3 and silicomanganese slag. It contains (wt %) 16.3 MnO, 18.4 CaO, 52 SiO2, 7.8 MgO, 5.26 Al2O3, and 0.24 FeO. The amount of silicomanganese slag in the system was 0, 5, 12, and 25%. Carbon is used as a reducing agent. Its consumption is increased by 5% from the stoichiometry for the recovery of Fe and Mn and by 8% of the metal mass for the formation of iron, manganese, and silicon carbides. The simulation is carried out using HSC Chemistry 6.12 () software package. The thermodynamic characteristics of the Fe3C, Fe2O3, FeO, MnO2, Mn, Mn3C, Mn5C2, Mn7C3, Mn23C6, and SiC compounds existing in the database are refined. It was determined that an increase in the melt temperature from 1400 to increases the degree of manganese recovery (ηMn) for all compositions of the systems. An increase of the silicomanganese slag content in the mixture from 0 to 25% decreases ηMn from 89.3 to 85% at and from 95.8 to 91.5% at . The chemical composition of the high-carbon ferromanganese alloy is (wt %): 71.9-72.8 Mn, 16.6-17.9 Fe, 0.015-1.64 Si, and 9-. The simulation results can be used to develop a technology for producing a high-carbon ferromanganese when silicomanganese slag is involved in metallurgical processing.

Smelting of metallic manganese and manganese alloys in the gas-oxygen refining converter

The purpose of the work is the substantiation and development of technological solutions for smelting metallic manganese and its alloys based on the duplex technology "arc electric steel-smelting furnace-converter of gas-oxygen refining." Methods: thermodynamic analysis by stage reactions and phase transformations of starting substances involved in chemical reactions; laboratory and industrial research; chemical analysis. Scientific innovation: when converting low-phosphorous manganese slag and involving recycled silicomanganese, the possibility of obtaining metallic manganese is shown when pulverized lime is introduced during blowing. The possibility of smelting low-carbon ferromanganese and metallic manganese in the converter of gas-oxygen refining by the silicothermal method is substantiated. Practical value: In semi-industrial and industrial gas-oxygen refining converters, technologies for obtaining low- and medium-carbon ferromanganese and metallic manganese by the silicothermal method and blowing high-carbon ferromanganese with gaseous oxygen have been tested. The silicothermal method provided high productivity, ease of metallurgical redistribution, high manganese extraction, minimal manganese "hits" with evaporation and transition of manganese to slag.

Correction to: Oxidation-Enhanced Evaporation in High-Carbon Ferromanganese

Correction to: Oxidation-Enhanced Evaporation in High-Carbon Ferromanganese

Oxidation-Enhanced Evaporation in High-Carbon Ferromanganese

Thermal fume formation is a problem in manganese ferroalloy production and the metal production industry at large. A better understanding of the mechanisms of fume formation and the operational parameters affecting the fume formation rate may help in reducing and managing fuming. This paper aims to investigate the effects of oxygen content and gas flow rate on the fuming rate and fume particulate properties for liquid high-carbon ferromanganese. The fuming rates were attained experimentally by measuring the fume flux with respect to oxygen content and gas velocity above the metal melt. The generated fumes were also characterized in terms of particle size and element distribution between fume and melt. The fuming rates were found to steadily increase with increasing oxygen content and flow rate of the gas up to a point where the curve flattens, following theoretical predictions. However, the highest flux values measured were above the theoretical limitations of the evaporation flux in vacuo given the alloy bulk composition. It is hypothesized that the high rate of fuming is caused by an increased manganese activity at the alloy surface due to local decarburization of the alloy in contact with the oxidizing gas.Graphical

Aluminothermic Reduction of Manganese Oxide from Selected MnO-Containing Slags.

The aluminothermic reduction process of manganese oxide from different slags by aluminum was investigated using pure Al and two types of industrial Al dross. Two types of MnO-containing slags were used: a synthetic highly pure CaO-MnO slag and an industrial high carbon ferromanganese slag. Mixtures of Al and slag with more Al than the stoichiometry were heated and interacted in an induction furnace up to 1873 K, yielding molten metal and slag products. The characterization of the produced metal and slag phases indicated that the complete reduction of MnO occurs via the aluminothermic process. Moreover, as the Al content in the charge was high, it also completely reduced SiO2 in the industrial ferromanganese slag. A small mass transport of Ca and Mg into the metal phase was also observed, which was shown to be affected by the slag chemistry. The obtained results indicated that the valorization of both Al dross and FeMn slag in a single process for the production of Mn, Mn-Al, and Mn-Al-Si alloys is possible. Moreover, the energy balance for the process indicated that the energy consumption of the process to produce Mn-Al alloys via the proposed process is insignificant due to the highly exothermic reactions at high temperatures.

Recycling of Mn-rich ore fines, dust and sludge briquettes in Mn alloys production

From mining operations to the production of metal alloys, mining and pyrometallurgical industries generate wastes such as sludge and dust. These manganese-rich co-products are currently mostly landfilled. Landfilling has an important impact, both environmentally and economically. ERAMET manganese alloy production plants and other metal industries seek to minimize those effects by recycling such co-products in the Submerged Arc Furnace (SAF). R&D work has been carried out to address this issue through briquetting agglomeration of manganese-rich co-products. These briquettes were used as raw material in the EXCALIBUR (Experimental Campaign of the Limit of Briquette Usage in Recycling) pilot campaign. It aimed at producing High Carbon Ferro Manganese (HCFeMn) in a pilot scale SAF. This study’s main objective is to assess the process stability during briquette recycling. Briquette quality was characterized by measuring fines formation and breakage during transport. Briquette recycling’s impact on the smelting process was quantified by dust generation, furnace stability and overall process performance. These briquette recycling tests in a pilot-scale SAF are part of the feasibility study of this process at an industrial scale.

Extent of Ore Prereduction in Pilot-scale Production of High Carbon Ferromanganese

Three pilot-scale experiments have been conducted at SINTEF/NTNU in a 440 kVA AC electric furnace to demonstrate the process operation, energy requirements and CO2 emissions in the production of high carbon ferromanganese alloys. Comilog, UMK and Nchwaning (Assmang) ores blended with other materials, such as sinter and flux, thus achieving different charge mixtures have been utilized in the experiments. In the prereduction zone, higher manganese oxides in the ore are reduced to MnO through solid-gas exothermic reactions and at a temperature around 800oC, the unwanted endothermic Boudouard reaction is also active. As such, the total coke and energy consumption is highly dependent on if the prereduction occurs by CO gas or solid C. The pilot furnace has been excavated after each experiment and the extent of prereduction of the ore has been investigated by collecting samples from specific regions in the prereduction zone. In addition, material, and energy balance calculations for the three pilot experiments have been calculated using HSC Chemistry software. The HSC material and energy balance calculations have shown that the slag/alloy ratios, metal analyses, carbon consumption and the overall energy consumption are mainly affected by the composition of the charge mixtures. The relationship between the specific carbon consumption, the off-gas CO2/(CO2+CO) ratio and energy consumption to produce 1 tonne of HCFeMn alloy is discussed for the three different pilot-scale scenarios.

Pre-Heating Manganese Ore in a Pilot-Scale Rotary Kiln

The production of high carbon ferromanganese alloys is traditionally carried out by smelting oxidized ores in electric furnaces using carbonaceous material as reducing agent, generating CO2 emissions which contribute to climate change. The actual carbon consumption is not optimal, there is an overconsumption linked to an incomplete decomposition and prereduction of manganese oxides inside the submerged arc furnace (SAF), where the reactions kinetics can be difficult to control. In the PREMA project, the considered solution consists in optimizing ores heating and pre-reduction before the SAF in a separate unit in order to reduce its electricity consumption as well as its CO2emissions. After preliminary tests in a lab scale rotary kiln have been performed, the pre-heating of raw materials in a continuous pilot scale rotary kiln was studied during a campaign at Eramet Ideas. The objective was to study the kinetics of thermal decompositions of two different Mn ores. The evolution of the ore composition was assessed with chemical analysis and by the study of the phases thanks to the XRD and Qemscan analyses.

Recycling of Waste Slag Upon Production of Manganese Ferroalloys

The mineral resources base of manganese ores is sufficiently large in Russia. However, their mining capacity is almost absent. This is due to the low quality of domestic manganese ores and the high content of phosphorus. To date, Russia has been obliged to import the commercial manganese ore, manganese-containing ferroalloys, metallic manganese, and manganese dioxide. To produce the high-carbon ferromanganese the composition of charge was developed. The optimum variant was that where 10–15% of manganese-containing raw materials were changed for waste slag. In this case, the phosphorus content in the high-carbon ferromanganese is lower by approximately 20 rel. % in comparison with the production of ferromanganese only from the manganese-containing raw materials. About 50–60 rel. % of manganese can be extracted from the waste slag of silicon-thermal production. To produce the hot metal, the composition of iron-bearing burden material was developed. The optimum variant was that where 100% of manganese raw materials were changed for the waste slag. In this case, upon production of hot metal, the specific consumptions of manganese raw materials and limestone were decreased by 100 and 20%, respectively. The phosphorus concentration in metal was lower by about 10 rel. % as compared to the production of hot metal only from the manganese raw materials. Up to 55% of manganese can be extracted from the waste slag of silicothermic production, which is irretrievably lost at present.
 Keywords: manganese ferroalloys, manganese-containing raw materials, waste slag, hot metal

High-carbon ferromanganese smelting on high-base slags

The article presents the results of laboratory trials for the smelting of high-carbon ferromanganese on highly-basic slags. Laboratory trials have confirmed that an increase in the basicity of ferromanganese production slags has a positive effect on the reduction of manganese to the metal and a decrease in the concentration of silicon in it. However, the high basicity makes the slag high-melting and tough, leading to large losses of manganese with the slag. The use of on borate fluxes solves this problem by affecting the physical and chemical properties of the final slags, which allows the process to be carried out at high basicities with the achievement of optimal technological indicators. The obtained positive results of laboratory experiments served as the basis for approbation the developed technology on a semi-industrial scale with the smelting of high-carbon ferromanganese by the flux method from the manganese ore of the «Bogach» Deposit. As a result of studying the smelting of carbonaceous ferromanganese in large-scale laboratory conditions, the possibility of converting manganese ores on highly-basic slags with appropriate regulation of the transport properties of slag to a standard metal with high technical and economic indicators was established. The best results are achieved when the CaO/SiO2 ratio in the slag is 1.8 and the boron oxide content in the slag is 0.8%. It is established that under these conditions, the obtained boron-containing highly-basic slags of carbonaceous ferromanganese are not subject to slaking.

Selective Carbothermic Reduction and Smelting (SCRS) Process for Beneficiation of Low-grade Iron-manganese Mineral Deposits

This study reports preliminary feasibility investigations for utilization of the selective carbothermic reduction and smelting (SCRS) processing scheme to beneficiate low-grade iron-manganese (Fe-Mn) mineral deposits from MN, USA. The study includes laboratory-scale demonstrations using an induction furnace and production of various products by manipulation of operational parameters. The products include alternative iron (Alt Fe), high carbon ferromanganese (HC FeMn), alternative silicomanganese (Alt SiMn), and upgraded manganese concentrate (Mn conc). All of these products have commercial value and can be used in various applications as raw materials.

Volatilization Behavior of Manganese from Molten Steel with Different Alloying Methods in Vacuum

The volatilization loss of manganese during the vacuum smelting process is one of the key factors that determines the manufacturing cost and quality of manganese steel. In this study, the laboratory experiments and thermodynamic calculations were performed to investigate volatilization behavior of manganese from molten steels with different alloying methods in vacuum process. Based on the thermodynamic analysis, with the increase of manganese content, the partial vapor pressure of the manganese component increased, resulting in manganese being easily volatilized from molten steel. The carbon content in the steel shows an evident influence on partial vapor pressure of manganese component, and a higher carbon content in steel leads to a lower partial vapor pressure of manganese, but it not influenced by the silicon content. Compared with the alloying method of high carbon ferromanganese, the volatilization loss of manganese in the alloying method of silicon manganese presents faster decay, agreeing well with the thermodynamic analysis. Besides, the volatile fraction generated in the alloying method of high-carbon ferromanganese is composed of a large amount of MnO nanorods with a lateral length approximately 500 nm and a small number of Mn3O4/Mn nanoparticles with a diameter less than 500 nm. Additionally, the volatile fraction generated in the alloying method of silicon manganese shows Mn3O4 nanoparticles as the main phase. It can be inferred that the existence of the manganese oxide phase is attributed to the high chemical activity of nanoscale particles within air.

Problem of manganese in Russian metallurgy

Ferrous metallurgical industry is the main consumer of m nese. The production volume of manganese ferroalloys in the world is approximately 1 % of steel production. After the collapse of the Soviet Union, Russian Federation found itself without any manganese ore base. At present, only high-carbon ferromanganese and ferrosilicomanganese are smelted from imported ore in Russia in a limited quantity. The mineral and raw base of manganese ores in Russia is quite large: the balance reserves of manganese ores are about 230 million tons (approximately 2 % of the world), forecast resources – more than 1 billion tons. Quality of the manganese ores is lower than the manganese ores of most major producing countries. Average manganese content in Russian ores is 9 – 23 %. Basis of mineral and raw base of these manganese ores are carbonate ores, share of which is more than 77 %. Manganese ore mining in Russia is sporadic and does not exceed 66 thousand tons per year. Demand of Russian ferroalloy plants, producing manganese ferroalloys, in manganese ores and concentrates is covered by imports. The problem of accelerating the creation of domestic manganese ore base from the position of economic security seems to be very important. It is necessary to solve a number of issues related to the enrichment of poor manganese ores, development of effective technologies for manganese ferroalloys smelting from concentrates obtained after the enrichment of these ores, as well as creation of more advanced methods of manganese concentrates dephosphorization. In the production of manganese ferroalloys from ore to finished alloys, about 50 % of manganese mined from the subsoil is lost; a large number of by-products are formed (sludges of enrichment, slags, screenings of small fractions of ore raw materials and finished products, sludges of smelting process and dust). The use and processing of them allow not only to reduce the consumption of initial mineral raw materials, but also to increase the efficiency of main production and to reduce environmental pollution. Additional extraction of manganese from industrial wastes and improvement of the technological processes for manganese ferroalloys smelting are the ways to increase the through extraction of manganese.

The Problem of Phosphorus in the Production of Manganese Ferroalloys

Ferrous metallurgy is the main consumer of manganese. The mineral resource base of manganese ores in Russia is quite extensive: the reserve of manganese ores amounts to 283.7 million tons (~2% of the world’s), and the expected reserves amounting to more than 1 billion tons. The quality of manganese ores in Russia is lower than that of manganese ores in most major producing countries. The average manganese content in Russian ores ranges from 9 to 23%. The Russian domestic manganese ores contain an increased amount of hazardous impurities, which are primarily phosphorus (from 0.2 to 0.8%). To involve domestic manganese ores into production, it is necessary to develop perfect methods for dephosphorizing manganese concentrates. Studies regarding a novel method for the dephosphorization of manganese-containing products are underway. In order to eliminate the manganese loss together with associated metal, as occurring in the case of the currently used dephosphorization method, this method consists in phosphorus reduction from the oxide melt by using gaseous carbon monoxide CO blown through the oxide manganese-containing melt, rather than using solid carbon. A novel process has been developed for smelting high-carbon ferromanganese and ferrosilicomanganese based on manganese concentrates with an increased phosphorus content. The process is carried out in a two-zone furnace equipped with a third zone intended for dephosphorization. Exhaust gases from the reduction zone containing 80–85% of carbon monoxide serve as the source of carbon monoxide required for performing dephosphorization. Methods have also been developed intended for smelting medium-carbon and low-carbon ferromanganese, as well as metallic manganese. These methods are based on a similar way for the phosphorus reduction from the oxide melt.

Manganese Problem in Russian Metallurgy

The main manganese consumer is ferrous metallurgy. The global volume of manganese ferroalloys production is ~1% of the volume of steel production. After the collapse of the Soviet Union, Russia was cut off from a manganese ore base. Currently, only high-carbon ferromanganese and ferrosilicomanganese are smelted in Russia from imported ore in a limited amount. The mineral resource base of manganese ores in Russia is quite large: the balance reserves of manganese ores are about 230 million tons (~2% of the world), the projected resources are more than 1 billion tons. The quality of the manganese ores in Russia is lower than that of manganese ores in most of the main producing countries. The average manganese content in Russian ores is 9–23%. The mineral resource base of the manganese ores is made up of carbonate ores, which account for more than 77%. Recovery of manganese ores in Russia is carried out irregularly and does not exceed 66 thousand tons/year. The demand of Russian ferroalloy plants producing manganese ferroalloys for manganese ores and concentrates is covered by imports. The acceleration of the creation of the domestic manganese ore base from the standpoint of economic security is quite a pressing issue. It is necessary to solve a number of issues related to the following: the treatment of poor manganese ores, the development of effective technologies for smelting manganese ferroalloys from concentrates obtained after the treatment of these ores, as well as the creation of more advanced methods for dephosphorization of manganese concentrates. In the production of manganese ferroalloys from ore to finished alloys, about 50% of manganese extracted from the subsoil is lost, a large amount of by-products is formed (treatment sludge, slags, screenings of fine fractions of ore raw materials and finished products, sludge from the smelting process and dust), its utilization makes it possible not only to reduce the consumption of raw mineral materials, but also to increase the efficiency of the main production, as well as to reduce environmental pollution. Additional recovery of manganese from industrial waste and improvement of technological processes for smelting manganese ferroalloys are ways to increase the through manganese recovery.