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By G. R. Palmer

The success of future electric vehicles will depend greatly upon the power supply choices made today. Research is presently being conducted by automotive engineers and electrochemists to determine what battery type may be the most promising. Not only are product production and application efficiencies being evaluated but also environmental concerns of reclamation and recycling. Rechargeable batteries using nickel-metal hydride electrodes are strong candidates for these electric vehicle applications. The U.S. Bureau of Mines is investigating hydrometallurgical technology that separates and recovers purified metallic components present in nickel-metal hydride battery scrap. Sulfuric, hydrochloric, and nitric acids are all capable of dissolving the battery electrode alloys given the proper operating conditions. Solvent extraction of the leach solutions using D2EHPA removes iron, and selective precipitation shows promise of recovering the other metals in the H2SO4 and HNO, systems.

Jan 1, 1994

By Heikki K. Jalkanen

Thermodynamic properties of copper-iron mattes and slag-matte distribution of copper and some minor matte constituents (Ni, Co, Mo, As, Sb and Bi) are discussed on? the basis of equilibrium measurements: a change from. oxidic to sulfidic solubility as the predominant form of dissolution of copper takes place as matte grade decreases. Distribution coefficients of minor matte constituents are complex functions of sulfur and/or oxygen potentials?. The distribution behaviour of different? metals can be qualitatively derived from their affinities to copper and stabilities. of their sulfides and oxides. The equilibrium results are compared with commercially observed values. from Outokumpu.Oy flash smelting furnace.

Jan 1, 1983

By Raymond F. Dalton

Despite the ready availability of numerous zinc sources, the process of solvent extraction- electrowinning (SX-EW) has as yet found little favour in the zinc industry. It is suggested that this is largely due to the previous lack of availability of suitable selective reagents having the particular features required to enable them to fit in to a solvent extraction-electrowinning based process for zinc, particularly with regard to strength and selectivity for zinc over iron. This paper describes work on the development of new selective extractants for the recovery of zinc from both sulfate and chloride aqueous solutions and suggests how they might be integrated into new zinc processes.

Jan 1, 1994

By Hiroyuki Matsuura, Fumitaka Tsukihashi

"Emission of CO2 gas from steelmaking industry covers more than 12 % of total CO2 emission in Japan. Though many efforts have been made to curtail energy consumption and high energy efficiency of Japanese steel production process has been achieved so far, further reduction of CO2 emission is strongly requested to develop sustainable steel production process and produce “green material”. Recently, authors have proposed the innovative hydrogen production process, in which water vapor is reacted with discharged steelmaking slag to produce hydrogen gas. This reaction can be achieved without any external energy source and operated by huge thermal energy associated with steelmaking slag and FeO or unrecovered Fe droplets that are relatively rich in the slag. In this paper, thermodynamic calculation results with various initial conditions in terms of hydrogen productivity were presented. Laboratory-scale experiments were also conducted to clarify the validity of thermodynamic calculation and the reaction rate in realistic conditions.IntroductionIronmaking and steelmaking process from iron ore through blast furnace and BOF is an essential steel production route for Japanese steel industries to supply high quality steel products in large quantity to society stably. Blast furnace – BOF process requires huge amount of fossil fuels such as mainly coal, resulting the emission of considerable amount of CO2 gas. Since the emission of CO2 gas from steel industries, about 147 Mt (FY2011), accounts for approximately 12 % of domestic CO2 gas emission in Japan (FY2011),[1] it is an urgent issue for steel industries to develop environmental-friendly ironmaking and steelmaking process and reduce CO2 emission. Various kinds of gases and by-products generated from ironmaking and steelmaking processes have been recycled as much as possible at present. Enormous thermal energy is also generated from processes and released to surrounding atmosphere as various forms such as sensible heats of gases, molten steels or by-products, and as heat losses. However, these energies are not utilized before final dissipation to atmosphere. Although various technologies to utilize thermal energy from ironmaking and steelmaking processes have been attempted to develop, practical application of these technologies has not been achieved because the thermal energy is not always useful as an energy source. In steelmaking process by BOF, fluxing agent such as CaO is added during reefing and thus about 100 kg/t-steel of steelmaking slag are generated. Since the steelmaking slag is discharged at temperature range between 1873 and 1923 K after discharge of refined molten steel, it also has large thermal energy. Amount of generated BOF slag is 11.0 Mt/y (FY2012) in Japan.[2] Assuming the amount of steelmaking slag is 10 Mt/y and its average heat capacity from room temperature to 1923 K is 1 kJ/kg·K,[3] unutilized heat is estimated to be 16 PJ/y, which is equal to annual energy consumption of 420 thousand families in Japan.[4]"

Jan 1, 2014

By Michael B. Mooiman, David J. Kinneberg, Philippe Cettou, Leo W. Simpson, Pierre Ramoni

"The demand for high purity precious metals began with certain industrial applications having uncompromising requirements for quality and performance. As industrial uses proliferated and as the jewelry industry became increasingly sophisticated, the demand for high purity gold has reached the point where 99.99% is now the standard in the marketplace. A similar evolution is expected for other precious metals.In this paper, we examine both the production and use of high purity precious metals, specifically gold, silver, platinum and palladium. After defining what is meant by ""high purity"", we discuss the various analytical techniques used for measuring impurity concentrations. Next, we review process strategies employed by extractive metallurgists to produce high purity precious metals. Lastly, we describe some of the principal applications for high purity materials including thick films, thin films, bonding wire, thermocouples and jewelry manufacture.Precious metals have unique physical properties that, despite their expense (and the ever-continuing search for more economical alternatives), make substitution difficult if not impossible. These physical properties are dramatically affected by small concentrations of certain impurities. As long as manufacturers continue to demand quality and performance, there will be a need for high purity precious metals.IntroductionIn the precious metals industry, the qualifier ""high purity"" describes any specification over and above commodity grade. High purity specifications delineate lower limits on overall metal purity or upper limits on individual impurities or both. Sometimes, if these special requirements become commonplace, either because of improved refining technology or because of market pressures, yesterday's ""high purity"" material becomes tomorrow's commodity. This transition is now occurring with gold bullion and probably will soon occur with platinum and palladium as industrial use of these materials grows."

Jan 1, 1998

By Fathi Habashi

The recovery of uranium from wet process phosphoric acid was applied on industrial scale in the 1940's by using octylpyrophosphoric acid as an extractant. Later, more efficient reagents were used, e.g., di(2-ethylhexyl) phosphoric acid and actylphenyl phosphoric acid. In the 1970's the rare earths in Kola phosphate were recovered in Finland and recently (1997) in Norway using HNO, as a leaching agent and di(2-ethylhexyl) phosphoric acid as solvent. It was demonstrated later on laboratory scale that both uranium and rare earths could be extracted from the rock by tributyl phosphate but at different pH values provided that the rock is leached with nitric or hydrochloric acids instead of the commonly used sulfuric. This new concept opens the way to the possibility of treating phosphate rock by in-situ, dump, or vat leaching for the recovery of phosphate values as well as uranium and the rare earths. Another solvent extraction process is used industrially for the purification of phosphoric acid using butyl and amyl alcohols.

Jan 1, 1998

By T. R. A. Davey

A simple model for metal solution behaviour may be derived, on the basis of dilute solution solubilities (where? log concentration of solute varies linearly with reciprocal temperature) and not-so-dilute region solubilities (where the log of the alpha-function at saturation frequently varies linearly with reciprocal temperature) and assuming activity to vary according to the quadratic formalism in between. Matte binary systems usually exhibit regular .solution behaviour when the constituent species are chosen appropriately. In many recent papers, metal solubilities in .slags are expressed as the sum of several different and supposedly independant molecular species (e.g. oxides, sulfides, chlorides), Such a view is untenable because of the now proven ionic nature of slags. Some possible reasons for the great effect of sulfur on copper solubilities in slags are discussed.

Jan 1, 1985

By Edgar Peek

Lixiviant regeneration is by definition a precondition for any hydrometallurgical process. In chloride hydrometallurgy either HCl or Cl2 has to be regenerated in order to establish an economically viable metallurgical process. One such regeneration process is widely used with steel pickling where HC1 is regenerated through the thermal decomposition of ferrous chloride in either spray roasters or fluid bed pyrohydrolyzers. This standard HC1 regeneration process deserves to be considered as a potential separation process, since thermodynamic calculations show that a fluid bed pyrohydrolyzer can function as a ferrous-nonferrous separator. Several nonferrous,metals such as zinc, lead and cadmium can be volatilized as a chloride under ferrous chloride pyrohydrolysis conditions. If such a nonferrous metal volatilization could be achieved in the case of slurry feeding of "contaminated" iron oxides, then this would increase the Fe/H2O ratio of the (process) feed and thus save on fuel per ton of iron, while yielding a marketable iron oxide product. Previous test work on synthetic materials revealed that the near-complete separation of zinc, lead and cadmium from iron oxide was possible in a pyrohydrolytic atmosphere, even if zinc was present as zinc ferrite (more than 99.5%). This investigation, which was carried out in a tube furnace at 1100 K has now been extended to treat synthetic zinc minerals and also franklinite ore. For the latter, it was found that 85% zinc volatilization could be achieved in 4 hours at 1300 K. It is postulated that complete zinc volatilization could not be attained due to the formation and/or presence of gahnite and hardystonite, which might be stable in HCl/H2O atmospheres at 1100 K. The effect of adding small amounts of calcium chloride to react with gahnite and hardystonite to give zinc chloride and both calcium aluminates and silicates is being discussed. Test work on slurry feeding of this complex ore in a recently constructed 4-inch diameter fluid bed pilot unit has been planned for the near future.

Jan 1, 1995

By Zemin Ma

A novel chromate [Cr(VI)] reducing bacterium was isolated from chromite ore processing residue disposal site of China and identified as a Leucobacter sp. by 16S rRNA gene sequence homology. The minimum inhibitory concentration of strain CRB1 was 820 mg l-1 of Cr(VI). The reduction of Cr(VI) occurred only under aerobic conditions. With an initial concentration of 2.5×108 cells ml-1, 1800 mg l-1 of Cr(VI) was reduced entirely within 38 h under the optimum conditions, at 30 °C and pH 9.0. Increasing Cr(VI) concentrations prolonged reduction process and higher cell densities meant quicker reduction. A blue precipitate was produced during chromate reduction of strain CRB1, which was binding to the surface of bacterial cells and determined as trivalent chromium with electron paramagnetic resonance (EPR) spectrometry. The conspicuous chromate reduction ability of Leucobacter sp. CRB1 suggested a potential for bioremediation of Cr(VI) containing wastes.

Jan 1, 2008

By H. Soto, J. Jara, F. Nava

A method has been developed to recover cyanide and copper from solutions containing copper complexes and thiocyanate. Copper is precipitated as copper thiocyanate or as copper cyanide depending on pH and the concentrations of thiocyanate and cyanide in the effluent. The copper precipitate assays over 50% copper and presents good dewatering characteristics. After settling it can be separated from the effluent by filtration. The solution containing the bulk of the cyanide is then oxidized with ozone to transform the remaining thiocyanate into cyanide. This results in a regenerated solution rich in free cyanide that can be recycled to the cyanidation process. Careful control of the pH of the solution is required. First, pH of the effluent is lowered to optimize the precipitation and oxidation stages, then the pH is restored to an alkaline value to regenerate the cyanide solution. Recoveries of over 96% copper and cyanide were obtained in laboratory tests using industrial solutions. With this procedure, cyanocidic gold/copper ores could be treated economically by heap leaching, since the cyanide consumed by the copper impurities could be regenerated at very low cost (most of the cost of cyanide regeneration would be compensated by the copper credits). In order to achieve this, a bleed of the barren solution could be treated by the proposed method, and then recycled to the leaching step. The volume of solution to be treated should be large enough to keep a cyanide/copper molar ratio higher than 3:1. This would assure that copper does not cause undue interferences in the leaching or the carbon adsorption stages. If the thiocyanate content is low, the oxidation stage can be avoided, and the solution can be recycled to the leaching stage directly after the solid-liquid separation stage.

Jan 1, 1997

By Aïda Espinola

Decontamination of synthetic solutions containing cadmium ions using coconut fibers in natura was investigated in laboratory scale. Cadmium ions, a serious pollutant of water ways, where it is detrimental to the environment, may be absorbed by fish and mollusk used as food, which will, eventually, poison humans; these ions are usually present in minero-metallurgical and electroplating industrial effluents. Usually employed for the aqueous effluents treatment are chemical precipitation, adsorption and electrolytic processes. Precipitation is not effective for cadmium removal, because of the high KpS of the cadmium hydroxide, which requires high pH; only sulfide would be efficient in cases of very small amounts. Some vegetal refuses have shown to be practical for absorption processes of several metallic ions. We have applied coconut (Cocos nucifera) shells, which are extremely abundant over most of the extensive Brazilian coast, in the removal of cadmium: it has been verified, in our laboratory, that the surface of the fiber of this coconut is rich in chemical compounds which are active scavengers for Cd2+. For the optimization of the process, hydrosoluble components existing on the surface of the fiber, which may be deleterious, were previously washed out by water, and variables, such as the pH and the proportion of mass of fiber to volume of solution, were adjusted. As much as 99% of the initial contaminant metallic ion has been eliminated, resulting a solution to be discarded which contains ca. 0.1 ppm; this attends to the maximum impurity legally admitted by the environmental control agency of Rio de Janeiro, FEEMA, for cadmium ions in aqueous effluents to be disposed in rivers and in the Guanabara Bay area.

Jan 1, 1998

By Stig Petersson

Slag from the converting of copper matte is usually recirculated to the smelting furnace. This recirculation generally causes disadvantages as magnetite-build-up in the furnace, accumalation of impurities as antimony, lead, nickel etc in the process. The treatment of converter slag in a separate furnace in order to recover the copper and nickel content would be of advantage from several points of view. At the Mining and Metals Division, Boliden, testwork has been carried out to treat converter slag from the PS-converters in a separate furnace. The tests have been performed in laboratory and pilot plant scale. The pilot plant tests have been carried out in a TBRC with charges of 5 tons. Based on these tests a full scale TBRC has been projected in order to treat the slag from the PS-converters. This slag will be reduced with copper concentrates to give a matte and a final slag low in copper and nickel. The background and data from the testwork are presented. Also the lay out, technical data and flowsheets for the projected process are shown as well as some production data from the Rönnskär smelter.

Jan 1, 1976

By Maria K. Kojo

The interaction between various slags and a nickel concentrate containing pyrite, pentlandite, and violarite were investigated by submerging concentrate pellets in molten slags. The slags were contained in MgO-A12O3 spinel crucibles. The slag oxidizes the iron sulfides in the concentrate, resulting in a nickel matte. The amount of S02 gas formed during reaction was measured to determine the oxidation reactivity of the slags. The experimental variables included temperature, the ferric/ferrous ratio of slag, and other slag properties such as the FeO/SiO2 ratio and the MgO and NiO contents. The reactivity of the slag depended in a complex manner on its oxidizing power, viscosity, and interfacial tension. The slag composition for the greatest reactivity was determined to be Fe3+/Fe2+ = 0.3, Fe/SiO2 = 1.3, and % MgO = 2. This slag, however, caused substantial foaming. Increasing the MgO content to 10% or replacing it by 5% MgO + 8% NiO eliminated at a slight decrease in reactivity. The implications of the findings from this work in the bath smelting of nickel sulfide concentrates are discussed.

Jan 1, 1995

By Xuling Chen, Zhiyun Ji, Min Gan, Tao Jiang, Liang Yin, Xiaohui Fan

Straw char exhibited considerably faster burning speed than coke breeze for its porosity, which significantly degraded sinter quality when it replacing coke breeze as sintering fuel. In this investigation, preforming technology has been employed to densify raw straw. The properties of straw char preformed show that its density was increased, and the structure was also densified, which made the difference of combustibility between the straw char and coke breeze smaller. The proper preforming temperature, residence time and pressure were 200℃, 1min and 120MPa respectively. Sinter pot trials show that the product carbonized from preformed straw made the proper replacement ratio to coke breeze increase from 20% to 40%, and the emission reduction of SOx, NOx in flue gas increase from 11.50%, 14.15% to 37.85%, 23.60% respectively, compared with non-preformed straw char.

Jan 1, 2015

By N. Tsuchida

Sumitomo Metal Mining Co. Ltd. (SMMC) is currently developing the flowsheet to treat stockpiled limonite, a type of laterite ore, at Rio Tuba on southern Palawan Island, Philippines. The new plant will be commissioned at the end of 2004. Rio Tuba Nickel Mining Corporation (RTNMC) has been mining saprolite since 1977, and the limonite ore located above the saprolite ore body has been stockpiled separately according to nickel and magnesium content. Ore from these stockpiles will be blended and used for the operation. The annual production of nickel will be 10,000 metric tons for the next twenty years. The proposed process consists of ore preparation, high pressure acid leach (HPAL), counter- current decantation wash, impurity removal and sulfide precipitation. Precipitated mixed sulfide will be processed to electrolytic nickel by the Matte Chlorine Leach Electrowinning (MCLE) process at Niihama, Japan. SMMC has established new technologies during the process development, such as zinc removal and sulfide precipitation. Applying this technology, preferential removal of zinc can be achieved by hydrogen sulfide gas with negligible loss of nickel. Precipitation of nickel by hydrogen sulfide gas is carried out at low temperature. Slow kinetics is selected for control of the particle size of the precipitated mixed sulfide. Keywords: HPAL, Zinc Removal, MS Production

Jan 1, 2004

By Rodney J. Ishak

The reduction of Mn3O4 to MnO has been investigated in a thermobalance apparatus. The charge was composed of manganese ore (decomposed by heating/calcination or pre-reduction to mainly Mn304) and coke. The material was charged to a crucible, which was suspended in the balance. CO-gas was distributed through a grid in the bottom of the crucible. Two sizes of ores were used; 2.4-4.8 mm and 6.7-9.5 mm. Coke particles were in the size range 4.8-6.7 mm. Experiments were conducted in the 900-1100°C temperature range. The composition of the product gas was monitored continuously. External mass transport between bulk gas and particle surface does not seem to limit the rate of reduction. Assuming that both diffusion through product layer and chemical reaction at the interface between MnO and Mn304 are rate controlling, the data was tried both in a shrinking core model and in a grain model using regression. The grain model gives the best physical description of the process, because the reactant is in fact a porous medium. With this model the effective diffusivity was calculated to be in the 1.5-6.10-5 m2/s range. The pore size was mainly between 0.1 and 10 um.

Jan 1, 2003

By Zhenjun Tan, Lei Zhang, Jigang Li, Yifang Zheng, Jilai Xue

"Water electrolysis in 0.4 mol/L NaOH solution for hydrogen generation was carried out with ultrasound introduced through the anode. It was found that the cell voltage reduced by 150-300 mV in the current range of 20 mA to 40 mA with ultrasound frequency at 25.3 kHz. The cell operation became unstable when the cell current was larger than 75 mA with ultrasound. This reduction in cell voltage was due to removal of the gas bubbles on the electrode surface, which can be directly observed in the see-through cell of water electrolysis. Ultrasound with frequency of 33.3 Hz was also tried, but no better effect was obtained. The results suggest that ultrasound assisted water electrolysis can have potential in energy savings for hydrogen production.IntroductionIn electrolytic process, the electrode that the bubbles generated on its surface usually covered a thin gas film, which can be caused an additional voltage about 0.15-0.25V[l,2], especially in aluminum electrolysis. To solve the problem, loading the ultrasound removes the gas bubbles from the electrodes, this subject had been researched in recent years. From 1995 Jilai Xue et al[3,4,5]. applied the ultrasound in aluminum electrolysis in lab. The results from Sheng-De Li et al.[6] reveals that can decrease the cell voltage and have influences about the hydrogen and oxygen's output ratio. Although there are many paper about the applying of ultrasound such as in electrolysis[5,6], deposition[7,8], plating[9,10], oxidation of salts substance on the surface of electrodes[l 1] and so on, the effect of different frequencies ultrasound hadn't been investigated deeply.We focus on the anode voltage by different frequencies ultrasound and the bubble behaviors in this paper. The environment of this experiment is in alkaline solution. Through this exploration it can offer a basis for the applying of ultrasound in electrolysis."

Jan 1, 2011

By Pekka Hanniala

The Outokumpu Flash Smelting process today is the most feasible method for copper matte smelting. The economic feasibility of the process has always been one of the main decision making criteria in smelter projects. Thus, today about 50 % of the world primary copper production utilizes Outokumpu Flash Smelting Technology. However, in the future, environmental criteria will have stronger and stronger impact on decision making. Flash Smelting technology offers the best pollution control features of any process. today. It is foreseen that, in the near future, the global trend will be that all the smelters must decrease their emissions at an accelerating rate, compelling the smelters to make increasingly larger investments on environmental protection. In most of smelters ?today, Peirce-Smith converting and transfer of the molten material in ladles are the number one pollution source. The key today for copper converting and minimizing emissions is the Kennecott-Outokumpu Flash Converting process, which has proven to be the most effective converting method in terms of pollution control and, production efficiency including capital and operational costs. Outokumpu Flash Smelting technology is applicable also for small to medium scale smelters but the most interesting area is the upper capacity limit for smelting in one line, which has not yet been reached. We predict that by the year 2000 to 2005, there will be at least one smelter which produces 500,000 tonnes of Cu per year based on one Flash Smelting and Flash. Converting unit. The current state-of-the-art of the Outokumpu Flash Smelting - Flash Converting process is presented in this paper as well as some new options for copper production to be utilized in the near future but which are available already today.

Jan 1, 1998

By Bo Liang, Hongmin Zhu, Kai Huang, Shafiq Alam

A new approach of recovering platinum and palladium from electronic wastes by hydrochloric acid leaching followed by selective adsorption on low-cost and environmentally benign biomass sorbent prepared from easily available agriculture waste is suggested. The obtained adsorbents were prepared by a combination of chemical modification and hydrothermal carbonization process with (NH4)2C2O4. It was found that the maximum adsorption capacity of hydrothermal carbonized garlic peel for Pt( ) and Pd( ) was 1.64 and 0.42 mol/kg respectively. The Langmuir adsorption isotherm was applied to describe the adsorption process. Kinetics of the Pt( ) and Pd( ) ions adsorption was found to follow pseudo-second-order rate equation. The adsorbents were examined by scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FT-IR). Based on the characterization results, a possible mechanism of Pt( ) and Pd( ) ions adsorption with the hydrothermal carbonized garlic peel was proposed. This study provides a promising adsorbent with efficient adsorption property for platinum and palladium recovery from the leach solution of electronic wastes.

Jan 1, 2016

By Rodney L. Williamson

Optimal estimation theory has been applied to the problem of estimating process variables during vacuum arc remelting (V AR), a process widely used in the specialty metals industry to cast large ingots of segregation sensitive and/or reactive metal alloys. Four state variables were used to develop a simple state-space model of the V AR process: electrode gap (G), electrode mass (M), electrode position (X) and electrode melting rate (R). The optimal estimator consists of a Kalman filter that incorporates the model and uses electrode feed rate and measurement based estimates of G, M and X to produce optimal estimates of all four state variables. Simulations show that the filter provides estimates that have error variances between one and three orders-of-magnitude less than estimates based solely on measurements. Examples are presented that verify this for electrode gap, an extremely important control parameter for the process.

Jan 1, 2001