Search Documents

By A. Galvan

High rate compressible media filter (CMF) tests produced exceptional total suspended solids (TSS) removal at hydraulic loading rates ranging from 97.8 to 122.2 m/h. The compressible media is manufactured from a robust resin fiber that can withstand low pH and temperatures up to 149 °C. The media porosity can be varied by applying compression onto the media. At 40% compression, the CMF can remove particles greater than 4 μ. Three synthetic test-samples were generated by Hazen Research Inc., (Golden, Colorado) to simulate the copper Pregnant Leach Solution (PLS), Raffinate and Electrolyte solutions used for the testwork conducted at their facility. The preliminary results showed that the CMF was very effective in removing TSS without the use of chemical conditioning from the above test-solutions with efficiencies of 98%, 97%, and 96%, respectively. Given the remarkably high hydraulic loading rates, the industrial equipment footprint would be minimized appreciably over conventional clarification and alternative filtration systems.

By Roberto Parra

The classic criteria of the preparation of the charge for the smelting of copper concentrates in at flash furnace considers the mass and energy balance from the chemical and mineralogy composition of the concentrates. The operation parameters fixed with this method don't assure the stability of the operation and the critical problems of the slag quality and dust formation occurs very often. This paper presents the results of a laboratory test that allows the prediction of the behavior of concentrates blends in the view of the minimization of the dust formation and the magnetite control in the slag. The combustion of different copper concentrates and blends were done in a drop tube furnace The results show that the magnetite and dust formation don't have a linear behavior with the weight proportion of the blend and some optimal blends of 2 or 3 types of concentrates can be identified. From the reasonable hypothesis that the qualitative behavior of blends in the drop tube represents the real behavior in the burner, the preparation of the charge with this approach could help to solve those operational problems.

Jan 1, 2003

By L. Xia

Sodium silicate(s), also known as “water glass”, are one of the oldest and most widely used industrial chemicals. Its first use in Canadian operations can be traced back to around 1925, which coincided with early use of xanthates in mineral flotation. Silicate functions as a sulphide and non-sulphide gangue mineral dispersant, depressant and modifying reagent in grinding and flotation operations. It is believed that soluble sodium silicate promotes selectivity of value added sulphides against gangue minerals, resulting in both grade and recovery improvement. This paper seeks to link improved grade/recovery to the interaction characteristics of minerals and the sodium silicate. A systematic study was performed with individual mineral species, an artificially designed model ore and the feed ore from a copper flotation operation. The function of sodium silicate was evaluated in the context of colloidal chemistry and linked to mineral surface chemistry. Measurement of pulp rheology and mineral zeta potential identified that sodium silicate works as a dispersant. The dispersion is accomplished by increasing a mineral’s net surface charge, resulting in a change in slurry viscosity. Bench scale laboratory flotation tests suggest that better dispersion leads to a diminished interaction of chalcopyrite with gangue. The improved Cu grade and recovery then are likely in response to an increased accessibility to collector along with a linked increase in particle bubble attachment resulting in better separation efficiency. ToF-SIMS surface chemical analysis of the flotation samples found a higher proportion of sodium silicate on minerals from the flotation tailings relative to the concentrates. Moreover, attachment of sodium silicate appears to be mineral specific; the data indicates that sodium silicate favours the surface of gangue phases over the value sulphides.

By Walter Curlook

An atmospheric acid leaching process for leaching nickel and cobalt from highly-serpentinized saprolitic fractions of nickel laterite deposits has been developed and patented [I]. The process involves leaching the highly-serpentinized saprolitic portion of the nickel laterite ore profile in strong sulphuric acid solutions at atmospheric pressure and temperatures between 80°C and 100°C, essentially autogenously, to extract over 85% of its contained nickel content and a large proportion of its cobalt content after leaching times of about one hour. The amount of sulphuric acid used in the leaching process is between 80% and 100% by weight of the finely ground highly-serpentinized saprolite ore on a dry weight basis. The metal values are recovered as intermediate products. Key words: Atmospheric Leaching; Nickel Oxide Ores; Laterites

Jan 1, 2004

By Zuhair A. Munir

"The use of self-propagating combustion reactions to synthesize metallic, ceramic, and composite materials is described. The limitation of this process because of the porous nature of its products is discussed. The formation of dense bodies through the simultaneous application of pressure is shown for a metal-matrix composite. The effect of an external electric field on the synthesis of ceramic and composites is described. The nature of the effect of the field on the mechanism of synthesis is analyzed theoretically and experimentally. The use of the self-propagating combustion to synthesize intermetallic thin films is presented for the Ni-Al and Ti-Al cases. The formation of functionally gradient materials (FGM) by centrifugally-assisted self-propagating high-temperature synthesis is described.IntroductionThe use of self-propagating combustion reactions for the synthesis of a large number of simple and complex materials has been described in numerous publications. These have been amply discussed in several review articles [1-4]. The many benefits of this method of materials synthesis are commonly examined in light of its most significant limitation: the porous nature of its products. The porosity in the products of self-propagating high-temperature synthesis (SHS) is an intrinsic characteristic of the process and its elimination has been the focus of numerous attempts. Various experimental methods have been used to accomplish this goal."

Jan 1, 1994

By Hu Meilong, Liu Lu, Bai Chenguang

Extracting perovskite from high titanium-bearing blast furnace (BF) slag is a green and potential method to recover the second titanium resource. The non-isothermal crystallization process of perovskite in synthesized high titanium-bearing slag was studied in situ by confocal scanning laser microscope (CSLM) with cooling rate of 20 K/min. The results showed that perovskite was the primary phase formed during cooling process in the titanium-bearing synthesized slag (TiO2=23%). Perovskite started to precipitate at 1719 K and finally presented an orthogonal straight lines morphology.

Jan 1, 2014

By D. W. Lawler

Prior to the manufacture of sulphuric acid in metallurgical plants, the SO2 rich gas from the smelter, roaster, or furnace must be cleaned to removed particulates, volatile contaminants, SO3, and water. Cleaning is accomplished by contacting the. gas with cooled weak acid. The system is designed so that all the contaminants, originally in the gas are captured in the weak acid, which then becomes an effluent from the plant. Historically, the entire weak acid effluent stream has been treated for disposal, with no attempt to recycle or recover any part if it. This is becoming increasingly environmentally unacceptable, and operators must consider better methods of treatment and recovery. In this paper, Kvaerner Chemetics discuss a number of options that allow the contaminants to 'be separated from the acid' value. This will result in an acid byproduct that can be sold or used elsewhere, and will minimize the volume of hazardous byproducts that must be discharged.

Jan 1, 1998

By Pengfu Tan

A thermodynamic model and computer program, CuModel, has been developed to model the distribution behaviors of Cu, Fe, S, O, Ni, Co, Sn, Pb, Zn, As, Sb, Bi, Au and Ag, copper loss in the slag, and heat balance in copper smelting process, matte converting process and copper con-tinuous smelting process. It can be predicted for any set of controllable process parameters such as feed composition, smelting temperature, degree of oxygen enrichment and volume of oxy-gen-enriched air. This model accounts for physical entrainment between matte and slag phases. It can be used in Isasmelt process, copper flash smelting process, Mitsubishi process, P-S con-verting process and Noranda process. The predictions by the present computer model are com-pared with the known commercial data from Guixi Smelter in China, PASAR Corporation in Philippines, Horne Smelter in Canada, MIM Limited in Australia and Naoshima Smelter in Ja-pan. The agreements between the computer predictions and the commercial data are excellent. In this paper, the applications of CuModel in the copper metallurgical industries have been pre-sented. CuModel has been used by Daye Smelter and Guixi Smelter in China, and by PASAR in Philippines as well.

Jan 1, 2004

By Kazuteru Tozawa

Surface tension, density and viscosity coefficient of acidic copper sulfate solutions simulating electrolyte solution for electrolytic production of copper have been measured and are summarized as a function of the solution composition and temperature. Nickel sulfatc is taken to be a representative coexisting sulfate that affects the physical properties of the copper sulfate electrolyte solution. The sulfates in the solutions, including sulfuric acid, increase the physical properties under consideration. Gelatin, representing organic additives for electrolyte solution, was found to sensitively affect the surface tension of the solution at low concentration of up to 200mgIL. The surface tension was markedly lowered by the addition of gelatin and the increasing concentration of gelatin led to a more pronounced decrease in the observed values. The surface tension gradually increases with time after addition of gelatin and the increase is enhanced by higher acid concentration and higher temperature. The observed change in the surface tension is considered to reflect the preferential adsorption of gelatin to the bubble-solution interface and the decomposition of gelatin due to hydrolysis to form various molecules having smaller molecular weights.

Jan 1, 2003

By Shi Guan-Yong, Niu Li-Ping, Dou Zhi-He

"In the preset work, the viscosity model (named modified KTH model) proposed by Sichen Du and S. Seetharaman et al and extended by Shu Qi-feng was applied to the ESR slag systems. A correlation to predict the viscosities of CaF 2-(CaO)-Al203 slags using interaction coefficients of different cations in the presence of oz-and viscosity interaction coefficients between oz-and F in the presence of different cations has been developed. The interaction coefficient between oz- and F- in the presence of Al3+ was determined from the experimental data as shown in known literatures. The good agreement between the calculated viscosities and the experimental data in the CaF2-(CaO)-Al203 systems has indicated that this approach can be successfully employed to predict the viscosities of ESR slags.IntroductionReliable viscosities data of high-temperature slag melts are important for the modeling and design of high temperature metallurgical processes. Although a number of experimental measurements have been carried out, the available viscosities data is still scarce compared to the needs of today's technology, especially in the case of complex melts. In process simulations, the needs of viscosity descriptions for complex systems which could enable the extrapolation of the data as functions of temperature and composition is strongly felt today."

Jan 1, 2013

By M. R. Baren

Unpublished results obtained by Baren on thermodynamic properties of sulfur in liquid Fe. Co. Ni. Fe-Co. Fe-Ni. and Co-Ni are reevaluated. correlated. and interpreted on the basis of recent developments in thermodynamics of alloys:. Existing reliable data are reviewed and compared with the? present results. Sulfur obeys Henry's law up to 0.04 mol fraction. and in this range the standard Gibbs energy of solution of sulfur is expressed as a linear function of temperature for each pure metal. The activity coefficient of sulfur in each binary metal solvent 1s correlated with the composition of alloy.

Jan 1, 1983

By Yoshinobu Fukumori, Testuya Watanabe, Futoshi Shikata, Hiroyuki Tokumitsu, Hideki Ichikawa, Masahito Miyamoto

Nano-particulate systems have attracted much attention recently in pharmaceutical field as drug carriers and functional components of pharmaceutical dosage forms. This paper describes our approaches in design and preparation of nano-particulate systems, including lipid nano-emulsions, chitosan nanoparticles and thermosensitive acrylic nanoparticles, for certain pharmaceutical applications mentioned below. The lipid nano-emulsions with their particle size smaller than 100 nm were prepared for gadolinium neutron-capture therapy (Gd-NCT) of cancer by a thin-film hydration method with sonication, and intraperitoneally injected into Greene's melanoma (melanotic No. 179)-bearing Syrian hamsters. This provided such a high gadolinium concentraton in tumor as 107 µg/g tumor (wet basis) at 48 h after administration. As an alternative gadolinium nano-carrier for Gd-NCT, biodegradable and highly gadopentetate-loaded chitosan nanoparticles (Gd-nanoCPs, 426 mTI in particle diameter and 9.3% in Gd content) were prepared by a novel emulsion-droplet coalescence technique. A significant tumor-killing effect could be obtained when Gd-nanoCP suspension was injected intratumorally twice 24 and 8 hours before neutron irradiation into B 16Fl O melanoma-bearing mice and subsequently thermalneutron was irradiated toward tumor site with a flux of 2 x 109 n/cm2/sec for 60 min. As one another application of nanoparticles, a novel acrylic composite latex with a hydrophobic core and a thermosenstively swellable shell was designed for fabricating microcapsules showing thermosensitive mode of drug release. The microcapsules with the composite latex-dispersing membranes exhibited an exceptionally rapid on-off response of drug-release in a thermosensitive manner.

Jan 1, 2000

By Minting Li, Hailong Yang, ChangWei, Cunxiong Li, Gang Fan, Xingbin Li, ZhiganDeng

The filtration problems on acid leaching sludge of high silicon zinc ore have been paid extensive attention in zinc hydrometallurgy. It was found that soluble silica can be effectively converted into silica precipitate with good settling, filtration and washing properties, and the filtration rate can be in excess of 800 L/m2 · h under certain leaching conditions. According to investigating on the filtration rate, viscosity and concentration of silica of leaching sludge or liquor, the filtering temperature can tremendously improve the filtration property of pulp. At the same time, the experimental data indicated that the viscosity of leaching liquor was the key factor influencing filtration property of leaching sludge.

Jan 1, 2016

By Takahiro Miki

Soldering material widely used is Sn-Pb alloy, which have low melting point and excellent electrical, strength properties and wettability. However, Pb is one of the toxic elements, which is undesirable due to environmental and safety reasons, thus Pb-free alternative alloy is preferred for new soldering materiaL Sn-Ag and Sn-Zn based alloys have been viewed as very promising candidates, among many potential substitutes. Addition of third element to these alloys will decrease melting point of the alloys. Hence, Sn-Ag-In and Sn-Zn-Mg alloys are expected to be suitable for replacing Sn-Pb solder alloy. In order to dcsign new Pb-free soldering materials, it is crucial to understand precise thermodynamic properties and phase diagrams of alloy systems. In the present work, ion current ratios of Ag to In and Mg to Zn were measured for Sn-Ag-In and Sn-Zn-Mg alloys by mass spectrometry, respectively. Also, the authors reviewed the thermodynamic properties of terminal binary alloys determined by other researchers and evaluated a thermodynamic functions to express the excess Gibbs free energy of each binary alloy. Thermodynamic functions to express the excess Gibbs free energy of liquid Sn-Ag-In and Sn-Zn-Mg ternary alloys were determined, utilizing the assessed Gibbs free energy of terminal binary alloys with the measured ion current ratios using mass speetrometer.

Jan 1, 2003

By Zhang Yongzhu

Sulfoxides are one kind of extractants for precious metals. The structure, the coordination reaction, the extraction behaviour and the precious metals complexes of sulfoxides are summarized. The differences between sulfides, sulfoxides and sulphones are also discussed.

Jan 1, 1992

By Mim Li, Huimin Lu, Lisha Yang

"CuInS2 thin films solar cells have drawn much attention for their low-cost, stability and high conversion efficiency. The electrodeposition of Cu-In precursor films, as the first step in making CuinS2 solar cells electrochemically in the air-and water-stable ionic liquid based on choline chloride/urea eutectic mixture has been investigated at constant potential. Compared with aqueous electrolytes, the large electrochemical window as well as the high thermal stability of this ionic liquid allow the direct electrodeposition of Cu-In precursor films. Then the precursor films were sulfuretted in a tube furnace at different sulfurization temperatures to optimize the films properties. The films obtained were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS).IntroductionCuInS2 is one of the most prospective absorber materials for low cost thin film solar cells, with a high conversion efficiency that exceeds 32% in terms of theory and nearly 13% in laboratory level [1-2]. In addition to its long-term stability, CuinS2 has a band gap energy Eg ranging from 1.3 to 1.55 eV and an optimal optical absorption coefficient reaching 105cm-1 [3-4]. CuinS2 thin films have been prepared by several methods such as spray pyrolysis [5-6], r.f.sputtering [7], vacuum evaporation [8-9] and electrodeposition. Comparing with vacuum methods, electrodeposition has lots of advantages such as less energy consumption, preparation big area thin film, stable system and enabling cheaper films.The electrodeposition of most technologically important metals has been shown to be possible from a wide range of ionic liquids. These ionic liquids are currently applied in a wide variety area. It is reported that the cell efficiency of chalcopyrite absorber layer (CIS, CISeS, and CIGS) via an electrodeposition route in laboratory condition has reached 11.3% [10]. Copper and indium alloy film is regarded as important precursor for the production of compound semiconductors with sulfur. The electrodeposition of the alloy film from room temperature ionic liquid (RTIL) has not been widely investigated. Only few alloy films, such as ZnTe, CdTe, GaAs and AlSb have been electrodeposited."

Jan 1, 2011

By David R. Brosnahan

Increased Cu grades due to chalcopyrite-rich ore from The Doe Run Company's new Casteel Mine prompted a program to increase Cu recovery. Preliminary tests indicated that prohibitive quantities of FeS2 float with chalcopyrite. Point counting of mill stream samples showed that locking was not a major problem, although grinding to finer particle size enhanced the floatability of both chalcopyrite and marcasite. Backscattered electron images and microprobe analyses of FeSz minerals revealed the presence of Pb which appears to occur as solid solution in marcasite, and as a sub-micron particulate Pb phase in pyrite.

Jan 1, 1987

By Andreas Nolte

This paper includes a comprehensive report about the metallurgical utilisation of reusable products from electronic scrap recycling, car shredding industry, used glasses an various waste products, such as slimes and flue dusts, generated in a secondary copper smelter. Depending on the copper content, the type of copper compounds and the characteristics of accompanying substances, the materials are treated by smelting in furnaces, operating under reducing or oxidizing conditions. HKs pyro- and hydrometallurgical processes, blast furnaces, converters anode furnaces, tin lead alloy plant and tankhouse will be outlined. The reusable products are categorized according to the origin of the materials and then presented in the form of quantity and quality balances. Processing methods, process able quantities and quality requirements of inputs are described. The utilization degree of the most important metals (copper, tin, lead and zinc) is described with graphics. The report is rounded by information on operating licence according to the environmental regulations of the Federal Republic of Germany and data concerning supply and contracts

Jan 1, 1997

By Takahiro Miki

Soldering material widely used is Sn-Pb alloy, which have low melting point and excellent electrical, strength properties and wettability. However, Pb is one of the toxic elements, which is undesirable due to environmental and safety reasons, thus Pb-free alternative alloy is preferred for new soldering material. Sn-Ag and Sn-Zn based alloys have been viewed as very promising candidates, among many potential substitutes. Addition of third element to these alloys will decrease melting point of the alloys. Hence, Sn-Ag-In and Sn-Zn-Mg alloys are expected to be suitable for replacing Sn-Pb solder alloy. In order to design new Pb-free soldering materials, it is crucial to understand precise thermodynamic properties and phase diagrams of alloy systems. In the present work, ion current ratios of Ag to In and Mg to Zn were measured for Sn-Ag-In and Sn-Zn-Mg alloys by mass spectrometry, respectively. Also, the authors reviewed the thermodynamic properties of terminal binary alloys determined by other researchers and evaluated a thermodynamic functions to express the excess Gibbs free energy of each binary alloy. Thermodynamic functions to express the excess Gibbs free energy of liquid Sn-Ag-In and Sn-Zn-Mg ternary alloys were determined, utilizing the assessed Gibbs free energy of terminal binary alloys with the measured ion current ratios using mass spectrometer.

Jan 1, 2003

By T. Plikas, L. H. Gunnewiek, L. Oshinowo

"Electric furnace smelting is one of the principal unit operations for ferroalloy production, and increased process intensity, improved availability, minimal maintenance and a longer campaign life are common objectives for electric furnace operation in order to obtain favourable economics of production. Furnace designers have continued to develop innovative solutions, e.g., furnace cooling systems, that have allowed these objectives to be realised and CFD modelling plays a key role in the design process. Enhanced understanding of the energy transfer process in the furnace and the ability to develop, evaluate and optimize components of the crucible design to match process requirements are the key motivators for modelling.This paper provides an overview of recent applications of CFD to the design of electric furnaces. The aim is to illustrate what can be done, and identify areas where further work is needed in this field. Examples include furnace bath simulation, crucible cooling system design, taphole design, baking of Soderberg electrodes, off-gas systems, and fume control and building ventilation. It is argued that the trend is for numerical models to become more encompassing while at the same time more accessible, and therefore further improvements in furnace design will be realised with continued and well validated modelling efforts.IntroductionOne of the main processing steps in ferroalloy production is the smelting of ore in electric furnaces. The three-electrode, AC submerged arc furnace is most prevalent method for smelting in the industry, with shielded-arc and DC plasma arc furnaces achieving limited application (1,2). Commercial furnaces range in size from a few megawatts to more than eighty megawatts of supplied power, and operate with the objective of maximising the return on capital invested. Maximising productivity and energy efficiency are two pathways to achieving this objective, through process intensification, increased availability, minimal maintenance, and increased campaign life for the furnace and associated equipment. Concurrently, the need to reduce the environmental impact of metal production by controlling the emission of particulate emissions, greenhouse gases, and other harmful by-products must also be met."

Jan 1, 2004