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By Florian Kongoli

The so-called "fayalite" slag, despite problems associated with it, is the most widely used slag in copper smelting processes. Thirty years ago, in order to overcomes some drawbacks of this slag a new "calcium ferrite" slag was proposed especially for continuous copper converting. Since both slags have strong and weak points depending on the field of their application about 8 years ago another new "ferrous calcium silicate" slag was proposed that is expected to solve the drawbacks of each slag. This new slag is defined as mainly consisting of FeOx, CaO and SiO2 as its main components but it can practically have several combinations of these constituents. In order to determine the best area of this slag for possible industrial application the quantification of phase relations is an important subject. In this paper the work carried out by the authors in quantifying through an original physical model the phase relations, liquidus surface, liquidus regions, behavior of solid phases and the effect of minor components is reviewed. Several special compositions of this slag have been identified and discussed for possible applications in the industrial practice.

Jan 1, 2006

By Jose F. Hevia

This study is part of a broader project on the hydrothermal conversion of copper concentrates to metallic copper by solid state reactions in which the copper remains localized in the solid phases. The kinetics of the solid/solid hydrothermal hydrogen reduction of tenorite (CuO) and cuprite (Cu,O) to metallic copper are presented. After an induction period, the process is governed initially by a nucleation step followed by rapid solid state reduction. Nucleation promoter agents decrease the induction period and control the particle morphology. Separate nucleation and reduction rate processes have been identified. Following nucleation, reduction follows a shrinking core process.

Jan 1, 1994

By Maria de Campos

The pre-reduction behaviour of chromite particles in methane-argon and methane-hydrogen gas mixtures was investigated between 1050°C and 1250°C. Loose bed of chromite particles were reacted in a vertical tube furnace under a pre-set gas mixture predetermined time intervals. Metallization results were obtained for the Cr and Fe components by chemically analyzing the reaction products. SEM-EDAX techniques and X-ray diffraction were employed to elucidate the reduction mechanism. It was found that higher reduction kinetics and higher Cr:Fe ratios in the metal phase would be achieved when hydrocarbon gas was used in comparison to classical carbothermic reduction at a given temperature. The reduction rate was generally bulk gas mass transfer controlled to the reaction site for initial stages which then was followed by ionic diffusion rate control. It is proposed that methane did not partake directly in the reduction but cracked, presenting the reaction site with hydrogen gas and atomic carbon, which was able to immediately react at the immediate area of reduction regeneration CO and H2 and thus maintaining a low partial pressure of oxygen at the reaction site.

Jan 1, 2006

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 John W. Graydon

Incineration is an attractive alternative to the disposal of MSW in landfill sites. However, the process of incineration generates fly ash which contains significant levels of leachable heavy metals - particularly cadmium, lead, and zinc - and it is essential to manage this fly ash in an environmentally sound manner. The compositions, phases, textures, morphologies and size of fly ash particles have been studied by light microscopy, scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. The detailed spatial relationships and speciation of the environmentally significant constituents have received particular emphasis. The information obtained is useful in understanding how fly ash is formed during incineration, in understanding the leaching behavior of untreated fly ash if it is disposed of in a landfill and, most importantly, in guiding the development of the best treatment strategies for fly asti to mitigate its environmental impact.

Jan 1, 1992

By Chen Zhang

Polycrystalline Ti-rich NiTi thin films have been deposited from a single NiTi target using a DC magnetron sputtering system. Free standing film was obtained by using a single crystal silicon substrate. Thickness ofthe thin films is controlled at around 12 pm. In this investigation, the effect of deposition temperature on the microstructure and transformation temperatures of the thin films is studied. Influence of post heat treatment temperatures on the properties of the thin films is also investigated. Transformation temperatures of the thin films are determined by differential scanning calorimetry (DSC). The surface microstructure of the thin films is studied using a scanning electron microscope (SEM), and the crystallinity is determined using x-ray diffractometry. It is found that the thin film deposited on a hot substrate is crystalline even when the substrate temperature is as low as 300°C, while the normal crystallization temperature for an amorphous thin film is around 500°C. The microstructure of the film deposited on a hot substrate shows a very fine grain size. The grain size increases with increasing substrate temperature during deposition. The effect of post deposition heat treatment on grain size is minimal.

Jan 1, 1999

By B. Mishra

The major waste product of the alkaline extraction of alumina from bauxite [Bayer Process] is known as red-mud. Approximately, a ton of red-mud is produced for every two tons of bauxite that is mined. The red-mud produced from Jamaican bauxite is rich in hematite, alumina and titanium oxide. It has been shown that over 90 wt. pct. alumina can be recovered from red-mud by soda-ash sintering and caustic leaching. Hematite can be carbothermically reduced with a degree of metallization of over 94 pct. At this stage, the product could be charged through the tuyeres in an iron blast furnace or smelted to produce pig iron. The mineralogical characteristics of the reduced product are not amenable to magnetic separation for iron recovery. The problems associated with the use of reduced red-mud as an alternative to direct-reduced iron [DRI] has also been discussed. Special attention has been paid to lower the alkali content of the reduced material. If smelted, the concentration of titanium oxide in the slag will be significantly high justifying its recovery by an acid-leach process. This paper describes the successful efforts of iron and alumina recovery.

Jan 1, 2000

Sanes are utilized to make molds for metal castings in the foundry industry. Approximately a half ton of sand is disposed of for each ton of metal cast in this country. The purpose of this investigation was to study and develop a process to separate chromite sand and silica sand from reclaimed sands for a steel foundry. Physical separations were utilized to yield silica and chromite sands with desirable molding properties. Several different separation methods, including electrostatic, magnetic, and various gravitational approaches were examined. Experimental results are presented. A method was developed to separate chromite sand from silica sand after mechanical or thermal reclamation. The reclaimed sands are passed through a rare earth magnetic separator to separate chromite sand and magnetic impurities from non-magnetic silica sand. Chromite sand can be recovered from magnetic silica sand or magnetic impurities very effectively using a wet concentrating table. The applicabilities of the separation methods are discussed.

Jan 1, 1995

By E. N. Mounsey

The paper addresses the design of the Zhong Tiao Shan Company (ZTS) Houma Ausmelt Technology copper smelter in People's Republic of China. The smelter represents the third copper smelter development using Ausmelt Technology, the first large scale (35,000 tpy blister copper) and the first smelter to use the Ausmelt Technology smelting and converting process steps in separate TSL vessels in a continuously operated process. The project will be realised through the combined efforts of ZTS, Ausmelt and ENFI, the Beijing Non-Ferrous Engineering Institute who provided partial detail engineering services in China. Ausmelt will provide the technology licence, basic and detailed furnace engineering packages and additional technical services including cold commissioning support and hot commissioning supervision.

Jan 1, 1999

By Gordon D. Jarvinen

Polymer Filtration (PF) Is an innovative, selecthle metal removal technology. Chelating, water-soluble polymers are used to selectively bind the desired metal ions and ultrafiltration is used to concentrate the polymer-metal complex producing a permeate with low levels of the targeted metal ion. When applied to the treatment of, Industrial metal-bearing aqueous process streams, the permeate water can often be reused within the process and the metal ions reclaimed. This technology is applicable to many types of industrial aqueous streams with widely varying chemistries. Application of PF to 'aqueous streams from nuclear materials processing and electroplating operations will be described.

Jan 1, 1999

By William Petruk

The behaviour of sphalerite during mineral beneficiation of base metal ores has been studied at CANMET and other institutes for at least 15 years by determining the liberations of sphalerite in mill products and calculating the recoveries of liberated and unliberated sphalerite in zinc concentrates. Sphalerite in base metal ores commonly occurs as layers and as interstitial material between pyrite. Layered sphalerite is generally liberated during primary grinding, but interstitial sphalerite requires re-grinding to achieve liberation. Around 95% of liberated sphalerite is generally recovered in zinc concentrates frau zinc circuit feeds. A series of tests was conducted on sphalerite in the ore of Brunswick Mining and smelting during a continuous fine tuning operation of the concentrator. It was found that a grind of 80% minus 37 micrometres was required to liberate the interstitial sphalerite. The fine grind increased Zn recoveries from 75% to 78-80%, but produced liberated slimed sphalerite which was lost. Since regrinding to a fine grain size is needed to obtain the desired sphalerite liberation, a method of recovering the slimed sphalerite is required.

Jan 1, 1990

By H. J. Roorda

With an increasing need to obtain metals by processing complex fine intergrown ores, the use of electron-optical techniques will become more important as a tool for mineralogical studies. Electron images enable a higher spacial resolution than can be obtained by optical microscopy and thus provide a powerful and necessary aid for the examination of small grains and finely locked particles. In this paper the mineralogy of Meggen ore was investigated. Both light-optical and electron-optical techniques were used to evaluate the mill feed and products of the concentrator. Detailed examination by reflected-light microscopy to assess the comportment of galena in the complex pyritic ore was inconclusive in establishing the cause for low lead recovery of only forty percent of the ore's lead content. Electron microprobe analyses indicated that the majority of the lead lost to the tailings was accounted for by extreme fine (often smaller than one micron) and complex intergrowths of galena in pyrite. The remainder was lost as fine free galena grains.

Jan 1, 1987

By Kenneth L. Driggs

The 1988 shift in primary smelting facilities from low grade matte (35%) reverberatory furnaces to high grade matte (63%) flash smelting heavily impacted a very stable and successful converter operation. Low matte grade converter campaigns averaged 36,000 short tons of copper and revert production/consumption was in balance. The conversion to high matte grades necessitated oxygen enrichment of converter blast and revisions in operating practices. After two years of operational development, campaign life has risen to over 40,000 short tons and revert production/consumption is again in balance.

Jan 1, 1991

By Wenjun Duan, Zongliang Zuo, Qingbo Yu, Qin Qin, Junxiang Liu

Moving bed has been widely used in the field of heat and mass transfer and reaction between solid particles and gas. In order to enhance the heat exchange coefficient, there will be tube banks inserted in the moving bed. In the process of drying ammoniates particles or heat recovery from high-temperature particles with moving bed, the particles flow behavior around the tube banks is significant. In this paper, the particles flow behavior around the tube banks is investigated, and all the results can provide guidance for the design and operation of a moving bed.

Jan 1, 2016

Rotary kiln incinerators are widely used in the incineration of various types of hazardous wastes. However, the complex transport processes within the incinerator are not well understood. Due to large variations in waste types and difficulties in feed characterization, the incineration process meets great challenges in a smooth operation, and expects uncertainties in the process chemistry and emission control. In order to get better understanding of the incineration process, process simulation was made on the kiln behavior by using Computational Fluid-dynamics (CFD) to characterize gas flow, temperature distribution and waste combustion in the incinerator. Temperature measurement was conducted in an operating incinerator to validate the CFD model. This paper addresses the environmental issues related to the hazardous incineration process, and reports the recent simulation results on gas flow and mixing, combustion heat transfer, and potentials to reduce emissions.

Jan 1, 2002

By Congcong Yang, Jian Pan, Deqing Zhu, Yang Zhong

A study of pelletization of one imported chromite concentrate with coarse site, poor ballability and refractory roasting performance was conducted in small scale tests, and high pressure grinding rollers (HPGR) was used to improve the pelletization. The mechanism of HPGR was revealed by means of SEM images and optical microscopy. Compared with the ball milling pretreatment, HPGR pretreatment can not only enhance the ballability of pellet feed but also drop the roasting temperature. Fired pellets, containing proper chemical compositions with high compressive strength of 2917N/pellet and good metallurgical performances, have been manufactured. The mechanism of HPGR reveals that chromite particle surface turns to more irregular after HPGR treatment and more new surface being formed because of more cracks, sharp corners and edges appearing, resulting in higher surface chemical activity, all of which improve the ballability of the chromite concentrate and contribute to the consolidation of fired pellets.

Jan 1, 2015

By R. W. Smith

The flotation response and electrokinetic behavior of Chlorella vulgaris and Chlamydomonas sp . when using dodecylamine hydrochloride as collector were studied in the absence and presence of Pb(I1). Also, an electron microscopy study was made of the algae after Pb accumulation. The flotation behavior of the organisms after Pb accumulation appears at least partially related to the location of the abstracted Pb onto or into the organisms.

Jan 1, 1991

By Lamar S. Todd

The direct production of metal from a sphalerite concentrate is an attractive route for primary zinc. A series of operations and conditions have been selected to efficiently cause the following overall exothermic reaction. The process uses a continuous circulation of molten copper for material and energy transfer between the unit operations. Sulfide concentrate is reduced with an excess of superheated copper to make a copper alloy and white metal. The alloy is stripped of volatile metals under vacuum and some metals can be separately condensed. The residual copper and the white metal are fed into a copper converter to be blown with oxygen for desulfurizing and the superheated copper is recycled. The paper will include a detailed material flow sheet for the process, discussion of the operating conditions of the individual units, behavior of minor elements, and zinc quality.

Jan 1, 1999

By Karl-Michael Zett, Marcus Kirschen, Ashraf Hanna

"Bottom purging systems are well established practice in refining metallurgy and an increasingly important technology for the EAF process in steel industry. Direct bottom purging provides efficient mixing of the entire melt volume, increases turbulence intensity in the melt, and improves mass exchange of alloy additions or oxygen. Continuously rising columns of dispersed gas bubbles helps to increase removal of volatile components carbon monoxide and hydrogen avoiding boiling retardation. Direct purging (DPP) systems provide cost benefits especially for EAF processes where metallurgical constraints have to be considered, e.g. for alloyed and stainless steel production, foundries. Case studies are presented.IntroductionCurrent EAF Technology and Production Constraints in Steel IndustryApproxinlately 30 % of steel, 446 Mio. tonnes in 2011, was melted in the electric arc furnace (EAF) with increasing tendency due to its large flexibility in production volume and raw materials. With recent increase of prices for ferrous raw materials the requirements for production of high quality steels from low quality scrap, direct reduced iron (DRI) and blends of ferrous raw material in various qualities increased. Maximum yield of ferrous raw material, oxygen, carbon, and alloys and minimum energy costs are of high importance. At modem high productivity levels even small process improvements provide considerable cost savings. Such improvements are caused, e.g., by efficiency increase of mass and energy transfer in the EAF. Optimization of flow pattern in the steel bath is therefore important for efficient melting of scrap and DRI and high homogeneity of the melt [1-4]."

Jan 1, 2013

By D. J. Murdock

Cominco Ltd. has developed a number of innovative technologies for electrowinning. The paper discusses the application of these technologies to the copper industry. Tankhouse and cell design will be discussed in addition to anode cleaning and cathode handling. Specific examples of the application of this technology to the copper industry are cited.

Jan 1, 1987