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By Donna L. Bodine

The ability of oxidized Upper Freeport bituminous coal to adsorb Cu2+, Cd2+ and Mn(VII) from very dilute aqueous solutions has been studied. Low-rank coal is known to adsorb heavy metal ions from dilute, aqueous solutions, probably by ion exchange and/or chelation by acidic functional groups on the coal surface. However, it would be advantageous to use higher rank coals for water treatment. Coal samples were oxidized thermally or by 30% H202 to increase the surface concentration of phenolic and carboxylic groups, then portions were shaken with Cu2+ and Cd2+ solutions. Acidic KMnO4 was also used to oxidize coal, with concurrent sorption of the resulting Mn(IV) and Mn(ll). The effect of oxidation treatment, metal ion concentration, and solution pH on metal uptake kinetics was investigated. Potential applications for treating effluents, especially those containing oxidizing ions, are discussed, along with possible flowsheet options.

Jan 1, 1995

By A. K. Kyllo, N. B. Gray, B. N. McCurry

"Dynamic control of the formation of a solidified layer between a pipe wall and a flowing melt enables the flow rate to be adjusted in real time. This solidified layer can be generated by using a coolant on the outside of the pipe wall to remove the required heat. The coolant, and hence the solidified layer, can be controlled remotely. The dynamic behaviour of the solidified layer was investigated by both physical experiments and mathematical modelling. The mathematical model has been developed using a finite difference technique to describe conduction through the pipe wall and solidified layer. Results from the model were consistent with previous steadystate experimental results using molten lead. Experiments are currently being carried out using molten tin in a recirculating circuit with a cooling system that is instrumented for accurate computer control to validate the model. The circuit is designed for flowrates of up to 24 kg/s (86 tph) of molten tin. Steady-state and dynamic predictions were made for the current rig.Industrial SignificanceThe current method of choice for tapping slags, metals and mattes from many metallurgical furnaces is using an oxygen lance to open the taphole and using a clay plug to close it. There are, however, some significant drawbacks in this method. The heat generated by the oxygen lance erodes the refractory lining of the taphole, as well as the clay plug, and the furnace products themselves corrode the taphole. Using an oxygen lance is also a significant safety hazard to the operators as they must work in close proximity to the furnace and be subjected to a shower of sparks while opening the taphole. Also, the flowrate of material through the taphole cannot be controlled online as the diameter of the opening cannot be varied easily. This feature means that the level of product in a furnace cannot be kept constant."

Jan 1, 1999

By S. M. Hay

The zinc content of blast furnace and basic oxygen furnace dusts is low compared with electric arc furnace dusts and it is generally not economical to treat the dusts to recover zinc. However, they have a high iron content and removal of the zinc would allow recovery of the iron values. A literature review and thermodynamic analysis was undertaken and, as a result, several smelting options were identified. This paper describes experiments undertaken to develop understanding of metallurgical aspects of these processes which are not amenable to theoretical analysis. Dusts from an Australian steelworks were characterised in order to determine their mineralogical make-up and the form of the iron. The processing aspects investigated in the laboratory were slag-metal equilibrium and solid-state pre-reduction using reducing gases of compositions expected from bath-smelting processes. Particular attention. was paid to the deportment of zinc, sodium, potassium, phosphorous and sulfur between the phases formed during smelting and pre-reduction. The smelting results indicate that less than 10% of the zinc, sulphur, sodium and potassium report to the metal. About 99% of the zinc and potassium and about 80% of the sodium could be volatilised from the dusts by reducing them at 1,000°C with mixtures of CO, CO2, H2 and H2O even when metallic iron was not formed. The experiments indicate that smelting of blast furnace and basic oxygen furnace dusts should produce hot-metal of a composition which can be blended into the main stream of hot-metal in the steelworks.

Jan 1, 1994

By Mick O'Meara

Metal Organic Chemical Vapour Deposition (MOCVD) is used in the production of computer circuit boards and metal shapes in nickel, gold, copper, cobalt, etc. All varieties of .MOCVD use the decomposition of a vapour of organometallic compounds to produce different forms of ultra-pure metals, or alloys. CVD Manufacturing's proprietary MOCVD process has been adapted and developed to produce commercially ultra-pure metal shapes, metal powders, and metal foams. Therefore, it is a purification process. The typical process has three steps. First, a volatile metal organic compound is produced from volumetrically contaminated metals, metal oxides, etc. Typical feed materials are metal powders, ores, concentrates, or a slurry of metals and contaminants. Secondly, the volatile. metal organic compound is purified by fractional distillation. Thirdly, the purified metal organic compound is decomposed into different forms of ultra-pure metals, such as net shapes, powders, or metal foams. A mixture of metals can be purified either by the selective production of volatile materials, or a separation can be achieved during the second step, in the fractional distillation stage. The purification and recycling of metals by the MOCVD process will be discussed, particularly with regard to nickel, aluminum, gold, the platinum group and other metals.

Jan 1, 2000

By Stephen W. Paff

The EPA has estimated that there are over 3,000 sites across the United States contaminated with lead. Techniques to remediate these sites include standard stabilization/disposal technologies, reclamation of lead using secondary lead smelters, soil washing, and biological removal technologies. In this paper, the current technologies used for lead remediation will be reviewed. Factors affecting the use of each technology, such as range of applicable concentrations, soil types, interferences from other contaminants, economics, and current technology status will be assessed. The paper will also focus on the results of a recent study completed by the Center for Hazardous Materials Research (CHMR), in conjunction with a major lead smelter, which demonstrates that secondary lead smelters may be used economically to reclaim lead from a wide range of lead-containing materials frequently found at Superfund sites. Such materials include battery case materials, lead dross, and debris containing between 3 and 70% lead. The results of development work completed by CHMR on the Acid Extraction Treatment System (AETS), which has been demonstrated to extract Lead from soils containing up to 30,000 mg/kg lead, will also be presented. The use of these technologies will be compared with other options for the remediation of sites.

Jan 1, 1994

By Yuzura Sato

Viscosity has been measured for various molten binary alloys of nickel with iron, cobalt and chromium in order to clarify the behavior of viscous flow of molten nickel alloys. The entire concentration range for iron and cobalt and 0-67at% of chromium content were studied. The measurement method was an oscillating cup viscometry using an alumina crucible that was precisely machined. The temperature was up to about I 880K for all the measurements. The results represented good Arrhenian relationship although some measurements included overcooled temperatures. The isothermal viscosities increased monotonously with an addition of iron and chromium into nickel. The addition of cobalt increased after stationariness. The isothermal viscosities showed concave curves. Activation energies increased monotonously by adding all the elements into nickel. These phenomena were considered to be related to the thermodynamic properties 'such as the heat of mixing and the structures of mixture melts.

Jan 1, 2003

By I. S. Blair

The introduction of the 36 MVA smelting furnace at Mufulira, and the experience gained during the first five years of operation have been described previously (6). Based on this experience the furnace was rebuilt in 1977., Details of the modifications made during this rebuild are described. Subsequent to the rebuild, refractory failures, particularly in the electrode ring bricks of the sprung arch roof, continued to cause concern, and repair and improved roof control methods are described. Electrode breakages continued, but developments in casing design and electrode preparation have resulted in significant improvements. Modifications in the electric furnace gas handling system are outlined, together with details of further changes to be implemented in the near future. The systems developed for metallurgical control of the furnace and the thermo-dynamics of the process are discussed. The electric furnace at Mufulira is now operating at above design production levels, and has decisively justified the choice of this technology in situations with inexpensive electric power. The potential for further increases in production capacity from the Mufulira unit, and improvements in design for new units are discussed.

Jan 1, 1983

By Jingwei Lou, Bing Li, Suzhen Li, Miao Shen, Jianguo Yu

"As a main impurity in primary lithium metal, magnesium is difficult to remove because of the very close relative volatility of the two metals. Electrochemical refining provides a possibility to completely remove Mg in the LiCl-KCl melt prior to Li reduction. MgCl2 reduction processes in LiCl-KCl- MgCl2 melt were investigated by cyclic voltammetry (CV), square wave voltammetry (SWV), chronoamperometry and chronopotentiometry. Then potentiostatic electrolysis was carried out and Mg (II) ion was reduced onto a liquid lead cathode from the LiCl-KCl-MgCl2 melt at the Mg deposition potential. The results show that Mg ( II ) is reduced in one step with two-electron transfer. The reduction potential of Mg ( II ) was well defined. The reduction of Mg( II) results in Li ( I ) underpotential deposition at 0.2V more negative potential than that of Mg( II) reduction. Therefore, in order to prevent Li ( I ) from codeposition with Mg, accurately controlling Mg ( II) reduction potential during the potentiostatic electrolysis was necessary. Ninety three to 99 % removal rate of MgCl2 was achieved after 8-12 h electrolysis when liquid lead was used as cathode.IntroductionMetallic Li has been widely used in batteries, light weight alloys and in fusion reactors because of its excellent properties. Currently, the only way in industry to produce metallic Li is by electrowinning from molten LiCl-KCl at about 450 °C [l-5]. LiCl-KCl is the only electrolyte used, because they presents a lower eutectic temperature and KCl shows a slightly higher theoretical decomposition voltage than LiCl, as shown in Table l .The produced metallic Li generally contains 1-2 wt% impurities including Na, K, Al, Ca, Mg, Si, etc. [6l, which are derived from the corresponding metal chloride compounds or metal oxide compounds existing in the LiCl and/or KCl raw materials. These impurities have to be removed by subsequent vacuum distillation at high temperatures to meet the requirements for metal Li purity in the final products. Separation of Mg from Li by vacuum distillation is difficult because their relative volatilities are very close, as shown in Table 2."

Jan 1, 2011

By Bora Derin

The partial pressure ratios of sulfur and oxygen for several copper flash smelting plants were derived using the Reddy-Blander (RB) model and predicted dissolved sulfur contents available in the literature. The sulfide capacities (Cs) of six different flash smelting plants (FeO-CuO0.5- CaO-MgO-FeOwAIOl.s?SiO2) slags were calculated. The log (Po2/PS2) versus matte grades of various industrial processes was determined. The PoiPS2 ratio increased with an increase of copper grade. The calculated partial pressure ratios for the copper flash smelting are in good agreement with those of the experimental data.

Jan 1, 2003

By J. E. Dutrizac

Fracture-exposed surfaces of sphalerite samples having five different solid solution iron contents ranging from 0.0 wt% to 14.8 wt% Fe were leached for 15 to 120 s at 100°C in 0.3 M Fe(S04)1.5 -0.3 M H2S04 media. The reacted samples were examined using X-ray photoelectron spectroscopy (XPS) which provides chemical state information on the first few nanometers of the solid surface. Surface compositions show that the leaching rate increases with increasing solid solution iron content of the sphalerite. Detailed evaluation of high resolution S2p spectra show that the leaching progresses via the formation of polysulphide species. Disulphide species were not detected in any of the experiments. Examination of the Zn2p and Fe2p spectra indicate little change in the chemical states of these elements over the duration of the experiments. Longer leaching times resulted in the generation of elemental sulphur. The ratios of elemental sulphur to dissolved ferrous ions and zinc suggest that less than 5% of the sulphide is oxidized to sulphate. Morphological studies showed that the elemental sulphur commonly formed at a few isolated sites, such as the grain boundaries. Furthermore, euhedral sulphur crystals were often identified. These observations suggest that at least part of the elemental sulphur forms via dissolved sulphide species which are oxidized in solution by ferric sulphate.

Jan 1, 2003

By D. A. Milligan

Ammonia leaching of copper sulfide concentrates, matte, scrap or other sources of copper yields copper amnine sulfate solutions which are converted to metal in a two-stage process involving precipitation of inter- mediate sulfites and their thermal decomposition to copper powder of high purity. Processing details and results are given. Considerable simplification in circuitry and cost savings are indicated. Energy requirements are reduced by substitution of copper powder precipitation and ammonium sulfate crystallization for solvent extraction, electrowinning and lime boil.

Jan 1, 1976

By A. S. Rao

In the original roast-leach-electrowin (RLE) circuit at the Chambishi Cobalt Plant, commissioned in 1978, the separation of nickel and zinc from cobalt in aqueous streams was achieved by successive stages of precipitation using lime. However, this technique was not able to meet the increasingly stringent metal quality requirements of customers whilst maintaining acceptable process recoveries. Intensive process development work was carried out and, in July 1988, an ion exchange circuit for nickel removal was commissioned using DOW XFS 4195 resin and for the first time Z.C.C.M. produced high purity cobalt metal containing less than 0.10% nickel. Following further work, a solvent extraction circuit for zinc removal, using DZEHPA, was commissioned in February 1991 in order to enhance cobalt recovery by reducing co-precipitated cobalt losses. This paper outlines the process development, design, commissioning and subsequent operation of these nickel ion exchange and zinc solvent extraction circuits.

Jan 1, 1993

By William Petruk

An investigation was conducted to determine whether mineral liberation data obtained by one image analysis technique are the same as data obtained by another image analysis technique. The liberated vs non-liberated, volume % and weight % techniques for measuring mineral liberations by image analysis were tested. The results show significant differences between the values obtained by the different techniques. The lowest liberation values were obtained by the liberated vs non-liberated technique and highest by the weight % technique. It is interpreted that the weight % technique produces the most realistic results. The weight % technique also produces data that can define mineral associations for the unliberated grains. These include (1) mineral quantities in particles that contain different amounts of unliberated mineral, (2) mineral quantities in particles that have different size ranges, and (3) mineral quantities and degrees of liberation for specific minerals in particles of different size ranges.

Jan 1, 1996

By Jack S. McPartland

The recent developments on the concentration and recovery of gold from leached gold thiosulfate solutions by solvent extraction, reduction-precipitation, and electrochemical deposition are reviewed in this paper. Alkyl phosphorus esters have been found to extract gold only in alkaline thiosulfate solutions, The recovery of gold increases with thiosulfate concentration in the aqueous phase and with alkyl phosphorus esters concentration in the organic phase with aliphatic hydrocarbon diluents. The addition of ammonia improves the extraction. The extraction of gold with amines in either aliphatic or aromatic diluent decreased in the following order: primary>secondary>tertiary amines. Increase in the extractant concentration at high pH increased the extraction of gold. At pH < 9, the primary amine, RR&apos;CHNH2 with 1&apos;9-23 carbon atoms is the main extractant with TBP as the synergistic reagent and at pH >9, the primary amine shows a synergistic effect on the extraction of gold&apos; with TBP. TheAu(I) ions in thiosulfate solution are reduced by sodium borohydride (SBH) to metallic gold, with particles in the sub micron range, At an SBH/ Au ratio of 6.25, pH = 6, and at room temperature, the I e ppm Au(I) in a solution of ] 0 gil thiosulfate was completely reduced to metallic gold in about 60 minutes.

Jan 1, 1999

By T. Wang, R. G. Reddy

"A new eutectic of LiNO3-NaNO3-KNO3 ternary system was calculated by using thermodynamic modeling and the eutectic temperature was predicted to be 389.15K. The melting point was determined using Differential Scanning Calorimetry (DSC). On repeated measurements, it was found that the melting point of the eutectic composition showed excellent reproducibility with the predicted value. The heat capacity was also measured using DSC and the data as function of temperature were fit to polynomial functions. Subsequently, the thermodynamic properties such as enthalpy, entropy and Gibbs energies of this novel ternary eutectic salt mixture were deduced as function of temperature.IntroductionIn these days, the provision of the large amount of energy required in the peak period relies more and more on the parabolic trough solar power plant and it works by utilizing the thermal transfer fluid. Consequently, the development of inoovative thermal transfer fluid with higher energy storage density is paramount to lower the expense for generating energy [1-4]."

Jan 1, 2013

By W. Mueller

The function of a process mineralogist in the operation of a copper mine and plant is to assist in the identification and classification of the operation&apos;s main throughput. These include ore, concentrates, slag and matte, and to a lesser extent, refined products. In addition, a number of other products not normally thought of in association with mineralogy are examined. These include scales from submersible pumps, failed boiler tubes, acid plant, and shaft furnace; characterization of inclusions in failed compressor gear teeth as well as in copper rod; and flue dusts from a smelter, air transported particulates and coatings on passive copper anodes in the refinery. Techniques and equipment required for these studies include simple hand magnets to the high intensity Isodynamic separator, visual examination to electron microscopes, x-ray equipment, DTA, IR, heavy liquid separation, and contracted services of custom laboratories. Several examined products from Magma Copper Company have been selected to illustrate the range of techniques and equipment required by a process mineralogist.

Jan 1, 1981

By A. J. Rigby

Refractory linings in converters or anode furnaces used to over-oxidize the blister copper will suffer rapid deterioration, due to prolonged contact with copper oxide-rich slag. Nitrogen stirring with COP KIN porous plugs and use of SEMTECH OPC in converters and anode refining vessels can considerably reduce both refractory wear and processing times. In addition, careful control of the vessel atmosphere and the use of real-time optical process control minimize both slag volume and contact time with the vessel refractory.

Jan 1, 2005

First, a classification of the various primary sources of feed materials for the production of cobalt is presented from a mineralogical point of view : sulfides, arsenides, sulfo-arsenides and oxide minerals. Each of these cate- gories will be characterized by its behaviour towards concentration methods, taking account of the presence of the associated minerals of other metals and of the nature of the gangue minerals. Then, for each category of cobalt bea- ring ores, typical flowsheets of treatment will be presented and discussed and the characteristics of the cobalt concentrates produced will be under- lined having in view their subsequent processing by pyro - and (or) hydrome- tallurgical methods.

Jan 1, 1988

By Junfu Chen, Jiann-Yang Hwang, Yong Zhou, Lijun Lu, Likun Lia, Jixiong Liu

The sheet-like NiS-ZnS heterostructured composites were prepared by the microwave hydrothermal. The fabrication of the heterojunctions broadened the range of light response of ZnS. The photoexcited electrons of ZnS migrated to the redox potential of NiS/Ni2S under visible light irradiation, which can facilitate the effective separation of photogenerated electrons and holes in space. The visible photocatalytic activity towards hydrogen production for NiS/ZnS nanosheet heterostructed composites without co-catalyst achieved 0.28 mmol h–1, and the quantum efficiency was up to 18.6% under the wavelength with 420 nm visible light irradiation.

Jan 1, 2015

By Emmanuel N. Zevgolis

After the Krupp-Renn process was shown to be unsuitable for treatment of the Greek nickeliferous laterites, the LM process was developed. It involved roasting reduction up to metallic iron in a Rotary Kiln (R/K) and smelting in an Electric Furnace (E/F). Ferronickel (with 15% Ni) produced in the E/F, was upgraded to 90-95% Ni in an 02 converter. Raw Ni was then electrolyzed to pure Ni. The LM process was not applied for very long however, due to various problems. So, the Larco process was developed, i.e., pre-reduction in R/Ks, smelting of the calcine in E/Fs for ferronickel production (15% Ni) and enrichment to 20% Ni, in an O2 converter. Until now, many technological improvements have been invented and applied or adjusted to the process, which have made it a fully reliable and competitive one. sohe of the improvements were the invention and application of a new granulation process for liquid ferronickel, the modification of the existing R/Ks, E/Fs and converters and the design of new ones, and others that are described in the paper. Keywords: Ferronickel, metallurgy, laterites, LM process, Larco process

Jan 1, 2004