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By L. M. Abrantes, A. P. Paiva

"A brief review of some innovative methods for the direct recovery of metals from loaded organic phases is presented; emphasis is given to electroreductive stripping and cementation, which are described and illustrated by examples: of current research. The recovery of silver using a two-phase electrolysis - by direct application of an electrical potential to a mixture of a metal loaded organic phase· containing Cyanex 471X, obtained by solvent extraction, and a stabilized sodium thiosulfate solution - is more extensively discussed. The overall efficiencies are analyzed and compared with data obtained by conventional stripping procedures. Some preliminary results achieved for the recovery of the precious metal using galvanic stripping, applied directly to similar organic solutions and involving zinc and iron powders as reducing agents, are also evaluated.Introductory ReviewThe application of hydrometallurgical methods to the recovery of metal values from ores and concentrates has been receiving a growing interest, either from researchers or from the mining industry [1].For the concentration / purification of the relatively low concentrated metallic solutions resulting from the leaching of those raw materials, solvent extraction (SX) is a well established technique [2]; the loaded organic solvent is then conventionally contacted with a suitable aqueous solution, the metal in its final form being usually recovered from this solution by electrowinning.As an efficient and / or selective stripping is sometimes difficult to achieve, depending on the specific characteristics of the system under consideration, some alternative procedures have been analyzed in order to overcome this problem. One of the chosen routes, mainly developed by Hirai and Komasawa, is to promote the reduction of the desired metal species in the organic phase, in such a way that the stripping stage becomes feasible; for the selective stripping of vanadium from a solvent containing a mixture of vanadium and molybdenum, the authors successfully used reductive [3], electro-reductive [4,5] and photo-reductive [6] techniques. The two latter methodologies have also been applied to the recovery of europium from a solvent containing europium, samarium and gadolinium [7,8].However, further processing is necessary to recover the metal in its solid state; therefore, methods causing the direct reduction of the metal species in the organic phase to their fmal metallic form would be of interest, as an intermediate step would be avoided"

Jan 1, 1997

By E. V. Redin, B. A. Dubrovsky, E. V. Knyazev, A. I. Starikov

"Ti-V magnetite is one of the most abundant composite ore resources in the world. This ore cannot be fully processed via blast furnace technology because of high content of Ti02. According to the investigations carried out in the USA and Japan ITmk3 RHF (Rotary Hearth Furnace) technology is a breakthrough in Ironmaking. Reduction, melting and slag removal can be achieved in just 10 min. The main objective of the investigation is to establish optimum operation conditions for the production of iron nuggets from Ti-V magnetite ore via the ITmk3 by means of the lab scale testing. Samples of ore from the Maly Kuybas deposit (Southern Ural), carbon reductant and fluxes were chemically analyzed. Green pellets were processed via a lab chamber furnace to simulate RHF conditions. The nuggets and slag were chemically analyzed. This preliminary test work provides valuable information which may be used for large-scale testing in a commercially sized RHF.IntroductionThe ITmk3 process upon which this paper focuses was developed by Kobe Steel in its research facilities [l]. After pilot testing at Kobe Steel's Kakogava Works in 1999-2004 the pilot demonstration plant was built and operations were successfully carried out by Mesabi Nugget joint venture in 2002-2004. Steel Dynamics put into operation the commercial plant at the Mesabi Nugget site in Hoyt Lakes (Minnesota) in 2010. Results were consistent with nugget characteristics confirming ITmk3' s flexibility with respect to raw material inputs. At the same time, no research in the field of nugget from the Ti-V magnetite bearing ore with high content of Ti02 and Alz03 has been done. It is well known, if a lot of Ti02 and Alz03 enter the blast furnace, slag becomes viscous. The viscous slag is obstacle for stable operation of the blast furnace. Besides, high content of Alz03 raises the melting temperature of gangue minerals disturbing the coalescence of reduced iron to the nuggets."

Jan 1, 2013

By M Pernechele, U König

Most of the operating steelmaking capacity currently relies on conventional, coal-based steelmaking processes. Currently, direct reduced iron (DRI) is only produced in regions where energy is available at low cost. To align with net-zero emissions goals, steelmaking capacity must transition to loweremissions steelmaking technology. Direct reduction of iron ore will get one of the preferred methods in the future due to its high technology readiness. New reduction technologies include hydrogenbased direct reduction processes. To ensure optimal efficiency during DRI production and to cope with newly developed technologies, processes need to be monitored more frequently and accurate. Traditionally quality control of raw materials and DRI has relied on time consuming physical testing, wet chemistry or the analysis of the elemental composition. The mineralogy of DRI that defines its properties is not frequently monitored. Process monitoring and quality control of DRI is possible by using modern X-ray diffraction (XRD) methods. In addition to the metallic iron content (Femet), metallisation (Metn) and the total carbon content (Ctot), XRD analysis also identifies the overall mineralogical phase composition. This allows additional information about the reduction process and enables fast counteractions on changing raw material mixtures. The benefits of the quantitative determination of the phase composition and the calculation of process critical parameters to produce DRI will be demonstrated with a case study

Sep 18, 2023

By Eugene A. Thiers, William V. Morris

INTRODUCTION Direct reduction processes reduce the various commercial forms of iron oxide (pellets, concentrate, fines, etc.) to metallic iron at temperatures lower than that of molten iron. Thus, this technology includes practically, all iron reduction processes other than blast furnaces and electric pig iron furnaces (whose output in terms of world production is negligible). The product of these processes which is known as direct reduced iron (DRI), or sponge iron, is primarily used as a source of metallic iron in steel-making operations. Interest in DRI, which has been significant since the early 1960s, increased significantly in recent years with the rapid growth of DRI installed capacity throughout the world. The importance of the subject for the Circum-Pacific region stems directly from the influence that DRI has on iron ore consumption and on future steel development for this region. Although there is widespread agreement that electric furnaces will continue to increase their share of global steel output, and especially so in the countries of the Pacific Steel community, some doubts exist about future scrap supplies being adequate to support growth at past rates. The authors believe that such doubts are soundly based. As this paper points out, the total supply of all metallics used in electric furnaces may not be adequate to support the extrapolated rapid growth in electric furnace steel production. This paper seeks to provide perspective on the global and Circum-Pacific prospects for DRI in light of recent energy price developments and the current recession. In this regard, the demand for DRI within the context of recent evolutionary patterns in steel-making, the outlook of DRI supply in terms of prevailing production costs, and the prospects of new technology are discussed. THE DEMAND FOR DRI Although several reports published in the last 10 years predict high rates of growth in DRI, the subject remains a controversial one. Significant growth has indeed occurred, but not to the extent anticipated in the studies summarized in Table 1. The substantial difference between previous expectations and present reality can be ascribed primarily to: (1) lower growth in steel production than formerly anticipated; (2) numerous cancellations of DRI facilities that were previously announced; and (3) a fundamental and probably irreversible change in the economics of DRI production. Note that DRI capacity at the end of 1980 was about 16 million tonnes, a significantly lower figure than any of the projections above. In addition, DRI production was only about half of capacity, reflecting the abnormally low rates of capacity utilization in this industry. [ ] Before examining the current outlook in steel, it is pertinent to note that the market for DRI is usually different in the industrialized countries of the West from that in developing countries. In the former, the available infrastructure and industry's diversification extends DRI's potential markets to numerous steelmaking, foundry, and other industrial applications, although competition from scrap and other forms of metallic iron is constant. Scrap is generally available in these countries and, therefore, DRI competes with it in electric furnace steelmaking, basic oxygen steelmaking (as a coolant), cupola foundry operations, or as an additive in the metallic charge for open hearth and blast furnaces. On the other hand, DRI in developing countries is often allocated exclusively to domestic electric furnace steelmaking or, when capacity exceeds domestic captive requirements, to export. Notwithstanding quality considerations, DRI is being and is likely to continue to be used predominantly as a source of metallics in iron and steel-making. Other uses of DRI, such as in copper cementation represent a marginal market in terms of overall tonnage and can be ignored at this point. Therefore, DRI demand is-determined by the overall availability of metallic scrap in its various forms--a function of steel production and its probable evolution. The Global Steel Outlook Given the present recession, an objective appraisal of the long-term outlook for steel is particularly difficult. On the one hand, historical trends and, especially, the inertial forces associated with such a basic industry as steel must be recognized; such trends suggest that the current stagnation with

Jan 1, 1982

By K. Sadrnezhaad

Industrial and experimental induction furnaces are used for melting various types of iron ingots, returned scraps and DRI sponge pellets to produce high purity cast-iron and steel heats. The lowest consumption of the electrical energy is determined for continuous feeding operation to be 0.3 KWH/Kg for production of cast-iron in 1.5-ton industrial furnace and 0.45 KWH/Kg for production of steel in 25-Kg experimental furnace. The optimum feeding rate for lowest energy consumption is obtained to be 12.5 grams per second for continuous feeding of DRI in 25-Kg induction furnace. Similar measurements show that the optimum size of the DRI pellets is around 8 millimeter.

Jan 1, 1988

By A. G. Oppegaard

Most iron ores treated by the R-N direct reduction process yield metallic iron products considerably lower in titanium, manganese, and chromium oxides and alkaline metal sulfates/sulfides than were contained in the original ores. These metallic iron products are suitable as feed stock for the open hearth and electric steel-making furnaces. The elements which are rejected in part are acceptable in the product since the product is designed to by-pass the blast furnace. R-N reduction conditions (PCO+H2-1 atmosphere, 1830° to 2150° F.) are adjusted for each ore. The iron ore which is reduced to 90 to 95 percent metallic iron is then subjected to the conventional beneficiation techniques. Under these conditions, 55 to 80 percent of titanium oxides, 75 to 95 percent of manganese oxides, 60 to 90 percent of chromium oxides and up to 97 percent of alkaline metal sulfates contained in the ore are rejected with the gangue to the non- magnetic tailings. The metallic iron products illustrated in this work contained 89 to 96 percent total iron, one to five percent TiO2, 0.2 to one percent MnO, 0.3 to 1.6 percent Cr2O3 and/or up to one percent alkaline metal sulfide. Usually only one of these components was present. Recoveries ranged from 80 to 96 percent of the iron in ore.

Jan 1, 1958

By Roberto Parra

The selective reduction smelting of Cu2O in Cu2O-FeOx-SiO2 melts has been studied at laboratory level, using as a feed a dead roasted calcine from a copper concentrate. The purpose of the study was to evaluate the kinetic and mechanisms of the indirect reduction with CO and the direct reduction with graphite from 1260°C to 1350°C. The reduction rate by CO was found to be 10-2 to 10-1 mole Cu2O m-2s-1. The graphite reduction macrokinetics for FeO and. Fe2O3 containing melts, was found to be a first order reaction with respect to the Cu2O concentration, with a kinetic constant of 104 to 10-3 s-1. The reduction rate was not sensitive to temperature nor to stirring, in the range studied. The measured reduction rate is almost one order of magnitude larger than the observed rate for the direct reduction of FeO.

Jan 1, 1999

By Alex Stewart

Most iron bearing ores treated by the R=N Direct Reduction Process yield products lower in phosphorus than the initial ores. The sulfur is also removed and generally is in the range of 0.02 to 0.05 percent in the final R=N product, independent of the sulfur content of both the ore and carbon fuel used. The mechanism and thermodynamic justification of the principal reactions leading to the removal of both phosphorus and sulfur and the control of sulfur in the iron concentrate produced are discussed and supported by the results of laboratory experiments. In substantially all iron ores (containing up to 4% sulfur as sulfate) and solid carbon fuels (containing sulfur from 1 to 8%) tested, the rejection of sulfur has been in the order of 90-95%, with not more than 0.02 0.05% sulfur in the final metallic iron product. With respect to phosphorus-bearing iron ores ranging up to 0.70% P205, the rejection to tailings has been in the order of 70-95%, resulting in not more than 0.03 - 0.07% phosphorus in the final product.

Jan 1, 1958

By M. Ramachandran, R. G. Reddy

"A direct route for the reduction of magnesium oxide to magnesium using thermal plasma processing, with methane as the reducing gas, has been systematically evaluated. A feasibility study of the reduction reaction has been performed on the MgO-CH4 system at different methane concentrations and temperatures. The effects of changes in the key process parameters, such as the oxide-to-methane ratio and plasma power, on the yield of magnesium have been systematically evaluated. A maximum yield of about 61 mol% Mg was obtained using power of 20.0 kW and a molar ratio of MgO:CH4=1:1. Phase, morphological, elemental and binding energy analyses were performed on the product powders to understand the reduction reaction. Surface oxidation was observed in smaller magnesium particles in all the experiments, while the in-situ sintering of magnesium rods was observed at a molar ratio of MgO:CH4=1:1.5. Magnesium carbide (Mg2C3) was observed in the product, and its mechanism of formation is proposed using phase equilibrium data and a predominance diagram.IntroductionMagnesium has an excellent combination of low density and high strength. These properties have increased worldwide demand for and use of magnesium. Two major processes are used in the commercial synthesis of magnesium metal. The first method is electrolytic reduction and the second is thermal reduction using Pidgeon process. These processes can be classified as traditional techniques, but there are numerous emerging technologies that aim at reducing the production cost of Mg, its environmental impact and energy consumption. Thermal plasma processing is one emerging technique that has great potential in all the abovementioned key areas of magnesium production.Traditional reduction techniques. Two major reduction techniques, namely electrolytic and thermal reduction, have been used in the commercial production of magnesium. Electrolytic reduction is typically carried out in electrolytic cells from magnesium chloride (obtained from seawater or well and lake brines) (Tripp, 2009). The following simplified reaction shows the reduction of magnesium chloride to liquid magnesium and chlorine gas:"

Jan 1, 2015

By Lee H. G, El-Rahaiby S. K

The literature relating to reduction of sulphides by carbon using lime as sulphur-absorbent is reviewed. A stage-wise thermodynamic model is employed to evaluate the practical feasibility of the direct reduction smelting of galena (PbS) concentrates with a carbon reductant in the presence of lime; a coke-rate of 65 kg/ton Pb is predicted by the model. The experimental data on the reduction of PbS:4CaO:4C mixtures under nitrogen were correlated by means of a finite difference numerical method and the values of the intrinsic rate constant I1 were derived. The results for the uncatalysed reduction are represented satisfactorily with log I1 = 1.247(±0.522) - 5540(±610)T-1.The catalysed PbS:4CaO:4C mixtures contained 2.5 wt% of ternary (K, Li, Na)2CO3 catalyst. For the catalysed reduction it was found that log I1 = 3.981 (±0.301) -7790(±353)T-1, where I1 (in both relations) is expressed in moles.(g.C.)-1.atm-1.s -I. The catalytic enhancement faclor was found to be quite large in the 1068 to 1262°K temperature range investigated here.

Jan 1, 1991

By Ryosuke O. Suzuki

A combined process of electrolysis of CaO in the molten CaCl2 and of calciothermic reduction, so-called OS process, was applied to prepare metallic vanadium directly from V2O3. The fine metallic powder containing 1860 mass ppm oxygen was obtained using 0.5mol%CaO-CaCl2 melt for 10.8 ks at 1173 K. The oxygen level did not decrease further even when twice electricity was applied. Because the metallic vanadium could be electrochemically deoxidized to the level of 10 ppm oxygen from 1.48 %, the large amount of by-product, CaO, due to reduction and the large surface area of the fine particles are the reasons of high oxygen content in the reduced powder.

Jan 1, 2006

By Clements R. J, Davey J. M

Development of the process from the pilot stage to the current operation of the Capel, WA plant is briefly described.The design criteria for a larger sized plant are discussed together with factors that relate suitable feedstocks and coal types to the capital cost, capacity and product grade of future plants at locations other than Capel. The application of the process to the direct reduction of iron ores is briefly discussed including its commercial application at Rockwood, Tennessee.

Jan 1, 1980

By Clements R. J, Davey J. M

Development of the process from the pilot stage to the current operation of the Capel, W.A. plant is briefly described. The design criteria for a larger sized plant are discussed together with factors that relate suitable feedstocks and coal types to the capital cost, capacity and product grade of future plants at locations other than Capel. The application of the process to the direct reduction of iron ores is briefly discussed including its commercial application at Rockwood, Tennessee.

Jan 1, 1979

By K. O. R. Gebhard

Direct reduction-are we moving in the right direction? by K. o. R. GEBHARD INTRODUCTION Numerous forecasts predict a rapid growth rate for direct-reduction processes. The figures quoted are so impressive that many a top manager must fear that he will fall behind in technical development if he does not base a substantial part of his future steelmaking for mass production on direct reduction.

Jan 2, 1974

By Jack R. Miller

This session has been organized to suggest to you that the development of direct reduction is important to the iron ore mining and coal mining industries. The papers presented this morning will include a discussion of the costs of making direct reduced iron (DRI), the iron ore and coal supplies needed to produce DRI, the financing of direct reduction (DR) projects and, probably most important, the impact of the DR development on the iron ore and coal industries. For starters, this opening presentation offers a brief statement about DR practice and DRI, under the title that should surprise no one: "Direct Reduction: What Is It?" There is always the chance? that a brief statement may become long and complicated. But, by mixing some slides borrowed from Hal Lownie with a larger number of photographs accumulated from other sources, I hope to avoid such pitfalls.

Jan 1, 1978

Direct seeding or regeneration of vegetation in Australia has been occurring in nature for about 400 million years! From the 1870's till the 1930's, direct seeding by man was used in the south-west of Victoria as a method of re-establishing native vegetation on broadacre farmland. The introduction of improved exotic pasture grasses and the wide-spread use of superphosphate from the 1930's lead to its demise as a farmland revegetation technique.

Jan 1, 1992

By T. J. Goff, G. M. Denton

Mintek has developed the EnviroplasTM process for the treatment of solid wastes from the metallurgical industry, especially steel plant dusts, without requiring agglomeration to produce inert slag and at the same time recover metal values such as nickel, chromium and zinc. The products that are generated in the plasma-arc process are usually a metal and a non-toxic slag, which are tapped from the furnace in liquid form. The metal is mainly composed of chromium, nickel and manganese. During the production of stainless steel between 30 and 70 kg of dust and fine waste is generated per ton of steel. Mintek has successfully processed around 1000t of AOD/EAF dust on a toll treatment basis in order to recover the contained Cr and Ni. The metal produced contained 18.5 per cent Cr, and 5.5 per cent Ni. All slag samples tested conformed to US EPA regulations for disposal. The chromium and nickel recovery to metal was 90 and 98 per cent respectively, on a once through basis i.e. no baghouse dust recycle. Slag tapping temperatures varied between 1650°C and 1750°C. The average actual energy requirement excluding furnace heatlosses of smelting steel plant dust with anthracite as reductant was 1.36MWh/ ton of dust. The total mass of feed reporting to the off-gas stream was 10 per cent. The average ZnO content of the fume was 35.5 per cent.

Jan 1, 2004

By Rui-Qing Li, John G. Peacey, Peter J. Hancock

"Noranda has been investigating a pyrometallurgical process for the direct recovery of zinc from zinc concentrate and zinc and iron containing residues. The process consists of injecting dry zinc concentrate and secondary zinc materials into a molten iron oxysulphide bath, volatilizing metallic zinc into furnace off gas essentially free of sulphur or S02, fixing sulphur contained in the feed materials as iron oxysulphide matte which is disposed, and recovering metallic zinc in an ISP type lead splash condenser. Combustion of petroleum coke with air or oxygen enriched air inside the oxygen containing matte supplies part of the heat, and the products of combustion dilute the zinc-laden gas to a desired level.This paper describes the process concept, thermodynamic background, experimental tests, mass and heat balance calculation for a conceptual flowsheet, environmental stability of the residue and advantages and disadvantages of the process. Experimental tests have successfully proved the process concept and thermodynamic predictions. Direct smelting of zinc concentrate and residues inside an iron oxysulfide bath has a great potential to become a cost effective and flexible zinc smelting process.1. INTRODUCTIONZinc is mainly produced by a roast-leach-electrowinning process route, which accounts for about 80% of the world primary zinc production. This process produces high quality zinc with very high zinc recovery (>95%) but suffers from several major drawbacks such as using high cost electricity as reductant, producing environmentally problematic iron containing leach residue (jarosite or goethite) and the difficulty in treating secondary zinc feed materials containing high impurity levels, such as electric arc furnace dusts from the steel industry, and other complex sources. Also in some areas, markets for sulphuric acid are distant resulting in negative realizations on acid sales.The Imperial Smelting Furnace (ISF) process is the major pyrometallurgical process to treat zinc-lead concentrate. The advantage of this process over the electrolytic zinc process is its flexibility in treating high-lead, bulk concentrates with high recoveries of lead, copper and precious metals. However, this is a two-stage process involving sintering of Zn-Pb concentrates followed by blast furnace reduction. The process requires large amounts of high-quality coke which is a major operation cost, and the sintering process which results in serious environmental problems."

Jan 1, 1996

By W. K. Connor, O&apos

Thermal Treatment Technology Division Albany Research Center, U.S. Dept. of Energy Oregon. This evaluation included a characterization study and direct smelting tests conducted in a bench-scale electric arc furnace (EAF). In contrast to other thermal treatment technologies considered for these wastes (i.e., fluidized bed combustion), direct smelting in the EAF can process 100% of the wastes without prior beneficiation, and utilizes solid oxidant additions (in this case iron ore) rather than air to oxidize the carbon. This solid oxidant addition is advantageous because it results in the production of several value-added furnace products. These products include cast iron resulting from the reduction of the iron oxides, baghouse dust containing virtually all of the zinc from the residues, and a clean (nonhazardous) slag product suitable for recycle as concrete aggregate or construction fill. Offgas from the smelting furnace also holds potential as fuel gas for cogeneration. The direct smelting tests conducted thus far were successful at producing the desired furnace products, exhibiting the potential for complete recycle of the waste pile. A cast iron product of comparable quality to conventional cast irons was produced, at nearly 80% iron recovery to the metal. The slag product was determined to be nonhazardous, based on the EPA TCLP. Lead and zinc partitioning to the dust product was greater than 99%. The material balance over the furnace indicates that for every ton of feed processed, 540 lb. of cast iron, 600 lb. of slag, and 150 lb. of dust would be produced. Energy consumption was roughly 1.10 kWxh/lb of feed material. Prior experience suggests that these figures measured in the bench-scale furnace would translate to 0040 to 0.50 kWxh/lb at the industrial-scale.

Jan 1, 2000

By Walter Weeks

THE subject of the flow of air through a mine under the influence of natural ventilation has proved an elusive one. To my knowledge only cut and try algebraic solutions have been used where multiple paths are involved. The object of this paper is to present a method for the graphi-cal determination of the flow induced by the natural ventilation pressure (N.V.P.) alone or in combination with a fan. The N.V.P., measured in pounds per square foot, induced by two columns of air between two horizontal planes at different elevations, is equal to the difference in weight of the two columns, assuming each to have a cross-sectional area of 1 sq. ft. Pressure in pounds per square foot is converted into inches of water by dividing by 5.19. Methods of calculating the N.V.P. have been discussed in the litera-ture. In this paper, for simplification of exposition, the change in pres-sure due to the weight of superimposed air will be assumed directly proportional to the length of the column. The actual methods of cal-culating the N.V.P. do not affect the solutions to be presented. It must be realized that the precision to be obtained from the small-scale, inked diagrams presented is not as great as would be obtained from large-scale, penciled curves that would he used in practice. The accuracy of the curves does not warrant reading "volumes" closer than the nearest thousand cubic feet per minute.

Jan 1, 1938