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By Nobuaki Sato

The electrical conductivity, k, of pure and sodium doped sulfur melts was measured with and without ultrasonic waves at temperatures ranging from 140 to 340'C by the two probe method using an ultra high resistance meter. The k value of the pure sulfur melt with irradiation jumped at around 170°C by an order of 102 after which it mouutuniocally increased from 10-5 to10-4 A' 1 cm-1 with an increase of the temperature. The addition of the sodium metal to the sulfur melt was found to cause a larger jumping in the K value. The k value increased with the increase of Na proportion in the melt. For a 10mol% Na doped sulfur melt it was as high as max ~30 A 1cm -1 above 180 C under the irradiation of of ultrasconics.

Jan 1, 2003

By Yuri Gelfgat

"This paper presents some results of the investigation of the steady magnetic field influence on hydrodynamics and heat/mass transfer in processes of semiconductor single crystal growth (Si, Ge, InSn). The investigation employed mathematical and physical simulation techniques of relevant processes and full-scale experiments on growth facilities. A number of additional MHD phenomena have been found generated in the melt due to the rearrangement of flow pattern, the formation of specific convective cells, and the origin of MHD boundary and shift layer.IntroductionMagnetohydrodynamic (MHD) means of creating forces by contact-free methods in liquid conducting media have been widely used in the production of volume semiconducting single crystals. The goal of this method is to control convective transfer processes in the melt volume and on the crystallization front [1-3]. This is due to the sufficiently high conductivity of semiconductor melts (s = 104 /106 O1m-1 ) and an obvious relationship between the hydrodynamics in the melt and at interfaces and the conditions of formation of single crystals and their quality [ 1].All types of MHD effects rest upon the generation of volume electromagnetic forces in the melt by various means as well as on the possibility to direct them arbitrary in space and to adjust easily their absolute values. Fig. l presents different means how to implement MHD phenomena during single crystal growth. It should be emphasized that in all the modifications given in Fig. l additional energy introduced into the melt cannot influence directly the crystallization process since it is incomparable to the energy of molecular forces. Both the influence and efficiency of MHD means are determined solely by the change of motion, heat and mass transfer characteristics."

Jan 1, 1998

By Chi-Ming Chang

Alloy powders are commonly used in the purification of zinc sulfate solutions for use in standard electrowinning practice. The primary goal of this research was to study the use of zinc-lead alloys for similar reactions in the galvanic stripping of impurities from organic solutions. The effects of various parameters on the electrochemical behavior of commercially produced zinc-lead alloy powders were determined. A qualitative evaluation and summary of the influence of the more pertinent parameters on iron removal from di-(2-ethylhexyl) phosphoric acid (D2EHPA) by galvanic stripping is given. Water concentration, oxygen content and reaction temperature were the principal factors affecting the reaction rate and process efficiency. Activation energies were also calculated and indicated that the reaction changes from chemical to diffusion control .with increasing temperature in the range of 35" to 45°C. The results showed that zinc-lead alloy gave faster reaction rates with less sensitivity to process variables than SHG zinc as a reducing agent for galvanic stripping. The role of lead could be as cathodic sites for the reaction which enhances the zinc dissolution or anodic half reaction. The morphology of the zinc-lead alloy surfaces, before and after the reactions, supports this assumption.

Jan 1, 1998

By Akira Kaneda

Mitsubishi continuous process employs an electric furnace for settling matte from slag. Electrodes are immersed into the slag layer in the slag-cleaning furnace and the temperature of the melt is maintained at a predetermined level by Joule's heat. Electrodes are immersed to the depth where the current of each electrode is kept at a set value, and they are raised or lowered automatically to compensate for the deviation from it. Because electric resistance of the bath is varied with the matte level in the furnace and the composition and temperature of the slag, the immersion depth of the electrodes is affected by them. Therefore by monitoring the immersion depth and its change with time, abnormal situations in the furnace, such a~ rise of matte level or local abnormal state of melt, can be detected. In this paper, relations between state of the furnace and electrode behavior are discussed based on the plant data, and then a new and simple monitoring method of the condition of the furnace is proposed.

Jan 1, 2001

By W. G. Davenport

Chapter 11 determined the combinations of industrial oxygen, oil and blast preheat that will steadily produce 65% Cu matte from pure chalcopyrite concentrate. It showed that the . combinations are described by a flat plane. It also showed that the minimum energy requirement for making 65% Cu matte occurs with maximum oxygen enrichment, zero oil and zero blast preheat. This chapter examines the, effect of matte grade on industrial oxygen, oil and preheat requirements.

Jan 1, 2001

By Roger Agnew

Sulphide ores mined by Inco Limited in the Sudbury District contain small quantities of cobalt. During beneficiation, cobalt distribution to various streams is similar to nickel. After smelting, nickel is selectively extracted by carbonyl refining and the cobalt remains in the carbonylation residue. This residue is processed in a specialized hydrometallurgical plant to produce precious metal residues, copper cathodes, and a nickel- cobalt carbonate intermediate product. The nickel-cobalt is shipped to Port Colborne where the cobalt is separated as cobaltic hydroxide and refined to metallic cobalt. This paper deals specifically with the recently constructed Electro Cobalt Refinery. The cobaltic hydroxide is dissolved and residual zinc, copper and nickel are removed by ion exchange and organics by a carbon column. The purified cobalt solution is fed to the electrowinning circuit where cobalt rounds are produced on stainless steel mandrels. In the design and construction of the refinery, special attention was directed to materials of construction both for the process equipment and the physical plant, operating control and flexibility, and the quality of the working environment. The end result is an efficient and clean operation which yields a product of excellent quality.

Jan 1, 1988

By Beatriz Amarai Campos, Jorge Alberto Soares Tenorio1, Denise Crocce Romano Espinosa, Adriana Johanny Murcia Santanilla

"The aim of the present work is to investigate the recovery of nickel from obsolete cell phones printed circuit boards. The printed circuit boards were firstly submitted to a grinding process and then leached in sulfuric acid. Nickel was extracted from aqueous solution using Cyanex 272. Aqueous/organic ratio was 1/1. The effect of both pH and modifier addition on selectivity of extraction was investigated.IntroductionCurrently, electric and electronic equipments (EEE) have become a necessity to the modern life. Associated with this necessity comes the continuous and increasing replacement of those equipments by new ones. The accelerated technology advances are responsible for the generation of electric and electronic waste. This waste can be dangerous not only to human health but also to the environment. Waste of electric and electronic equipments (WEEE) has a variety of components and metals in its composition becoming a potential pollutant to the environment when not properly discarded. Its wrong disposal causes a loss of materials that could be recovered and reused. Therefore WEEE treatment is an important matter because it can assist the reduction of waste generated and the recovery of valuable metals.Printed circuit board (PCBs) is an essential component of EEE and is typically very complex from a chemical point of view. Several metals may be present in its composition, such as cooper, nickel, iron, zinc, lead, tin and silver1''. This characteristic hinders the development of a simple treatment, making it necessary the application of chemical and mechanical processing for their recycling'4'. The UN estimates that approximately 20 to 50 million of tonnes of WEEE are generated worldwide each year."

Jan 1, 2011

By Milance Mitovski, Milorad Cirkovic, Vlastimir Trujic, Dragana Živkovic

"In this article, it is analysed the possibilitis and the effects utility waste energy of process sulfuric acid production in the existing technical-technological conditions. The utility second process energy, reduction the fuels consumption, reduction environment pollution and its effects are shown, too. High heat quantity is produced as the result of exothermal reactions in the production process of sulfuric acid in Bor. A part of this heat is sufficient for the process development, and significant part of this heat presents low-temperature heat energy that is irretrievable lost. Investigations were carried out based on production of 485 t of monohydrate/day of sulfuric acid. By recovery of this heat quantity for heating purposes, about 20.000 – 25.000 t of coal/year would be saved, what would significantly improve the power efficiency of the smelter copper production. IntroductionTechnological process of copper production in RTB BOR (Serbia) produces a significant quantities of high temperature secondary (waste) heat energy that is uncontrolled “lost” in the vicinity. Secondary heat energy is produced in pyrometallurgical copper production in quantity of 1,621 kWth/kg of dry concentrate or existing heat (that presents a difference of heat at furnace outlet and heat at temperature over temperature of dew point of sulphuric acid gases) in quantity of 1,315 kWth/kg of dry concentrate. For designed capacity of Copper Smelter in Bor, the existing heat power of secondary energy is 92,111 MWt, what is an equivalent to the power of steam-turbo plant where the Rankine-Clausius heating cycle is done, and that is 28,334 MWe."

Jan 1, 2008

By P. R. Seidl, R. C. C. Ribeiro, J. C. G. Correia

"More than 95% of asphalt pavement materials consist of aggregates. The highway and construction industries consume a huge amount of aggregates annually causing considerable energy and environmental losses. The aggregates are usually produced from neighborhood aggregate quarries or form natural aggregate sources. The use of marble and granite wastes from quarries as aggregates might help meet the increasing demands and slow down any detrimental effects on the environment. Chemical and physical results showed that the use of marble and granite wastes from quarries in the asphalt production is quite fusible. Consequently, granite sawmills would perform a clean technology. This technology would also have an economical impact by not spending on basalt extraction.IntroductionThe granite fines generated from sawmills of ornamental rocks comes as a great problem and it lacks undeletable solutions. This problem involves the preservation of the environmental and constitutes one of the subjects more critical the point of view of social beneficiation of the population. The Cachoeiro de Itapemirim County, Espírito Santo State, Brazil is an example, of this problem. In this area, the granite and marble fines generation is around 15.000 ton/year.The problems generated by these residues affect with more emphasis the animals, such as the cattle, which inhaled the water content fines of granite and this residue accumulate in their lungs. Other great problem observed is the sanded of the river and the reduction of aquatic life.This problem is beginning to be set out due to performance of Center of Mineral Technology (CETEM), and of several other organisms of Rio de Janeiro State, aiding the sawmills owner’s. This help consists of teaching the best procedure of discard the residues and studies for its use, for instance the production of mortars, tiles, bricks and road pavements [1]."

Jan 1, 2008

By René Winand

The paper gives a synthesis of research work performed in the department during the last ten years and dealing with cobalt , copper and manganese electrodeposition in chloride aqueous solutions. Special emphasis is given to electrocrystallization. For copper, properties of the electrolyte such as solubility limits, electrical conductivity and complex ions stability are discussed in connection with leaching, purification of the electrolyte, and metal recovery. When possible, kinetic parameters and probable electrode mechanisms are given. Problems that are still to be solved are also listed.

Jan 1, 1985

By Sharon L. Eyer

"FTIR spectroscopy is employed to define mineable ore deposits based on exploration samples. The RAMBO (Robotic Assessment of Mineable Bauxite Ore) technology is operating successfully at an alumina refinery in K winana, Australia, for assessment of a number of critical ore attributes including available alumina, extractable organic carbon and total iron. Classical methods of analyses for these properties require laboratory-scale digestion of alumina ore (bauxite) or XRF analyses.Multivariate calibration is used in the RAMBO system to generate robust mathematical models that are able to estimate classical data from FTIR spectral data. Furthermore the models can highlight regions of ore that are relatively unusual. Unusual ore may be investigated for potential impacts on refinery processes well in advance of mining.The components of the technology are described and some results for an example application (bauxite) are presented. Challenges and difficulties are discussed. The potential to apply the technique to process control is introduced."

Jan 1, 1999

By Takeo Fujino, Nobuaki Sato, Yarong Wang, Kohta Yamada

"Ternary mixed sulfides of some transition metals MTS3 (M=Ba, ·Pb, T=Ti, Zr) were synthesized by a relatively low temperature process using sulfur melt. The mixture of starting materials, such as, metals and/or binary sulfides and a large excess of sulfur was reacted in a vacuum-sealed Pyrex or quartz ampoule at 350- 600 °C for one to three weeks. After the reaction, the remaining sulfur was completely removed by a process composed of filtration of sulfur melt and followed dissolution in CS2• The binary sulfides impurities coexisted in the products were removed by rinsing the products in water and acetone. By using the above method, BaTiS3, PbTiS3 and BaZrS3 'Were obtained in pure form. The effect of addition of halides on the yields of these ternary sulfides were also discussed.IntroductionThere have been a vast number of studies on the preparation and physical and /or chemical properties of mixed metal oxides. As is well known, some of such compounds exhibit excellent materials properties, causing them for use in mechanical, electronic, magnetic and chemical devices. Not a few mixed metal sulfides show similar physico-chemical properties to those of the corresponding mixed metal oxides. However, the study of the mixed sulfide crystals is rather sparse mainly due to difficulties in preparing these compounds. In various methods which have been adopted for preparing mixed sulfides, the simplest method would be the solid-solid reaction of the component binary sulfides or elements. However, there are always diffusional constraints with regard to the reactions in solid phases causing it necessary to heat the reactants at sufficiently high temperatures, viz. 800-1200°C. On the other hand, some mixed sulfides are unstable at high temperatures or to change their materials properties due to sulfur nonstoichiometry and structural modification depending on temperature, i.e., synthesis of such compounds needs to be made at lower temperatures. Processing in alkali halide melts is hopeful to overcome the above problems but to obtain the halide melts the temperatures above ~ 600 °C is needed. Low temperature reaction has been carried out for the preparation of Hg1.24TiS4, which was formed by the ·combination of TiS2 and molten Hg metal at 320°C[l]. Reaction of WS2 with LiBH4 melt at 350°C yielded LixWS2[2]. These sophisticated methods, however, can be applied only to the vary special cases."

Jan 1, 2000

By Cristiän Vargas, Jaime Simpson, Gerardo Cifuentes

"This paper presents a new process for the precipitation of Sb and Bi present in copper refinery electrolytes in the presence of Pb02 (Chilean Patent No. 45,037). To establish the conditions under which the precipitating compounds form, it was necessary to evaluate the amount of PbCh consumed, antimony extraction efficiency, precipitate stability, reaction kinetics, diffraction analysis and X-ray fluorescence, separation of size, plus observation of the precipitates in the electron microscope. Preliminary tests were carried with synthetic copper refinery electrolyte, and then the final testing was done with electrolytes from Chilean refineries. This process provides a real alternative for the treatment of copper refinery electrolytes for the control of Sb and Bi in solution; it is very simple to operate and is low cost compared with competing processes.Introduction.A high quality copper cathode implies a cathode free of impurities. The electrorefining process seeks to eliminate these impurities from the copper anode (99.5% purity) by its dissolution in an acid electrolyte using chemical and electrochemical reactions. As a result of this process, a cathode (99.99% purity) is obtained. If the concentration of impurities in the electrolyte, from the dissolved anodes, begins to increase; particularly if the antimony concentration in the electrolyte increases up 500 ppm, the formation of floating slimes which are a major cause of contamination of the cathode is favoured. The most important impurities from the point of view of their effect on the quality of the cathode copper, are Ag, As, Sb, Bi, Pb, Se and Te. Silver is necessary for the control of Se and Te. To control all of these impurities, it is necessary to establish different methods or parameters of control in copper electrorefining. These parameters are anode composition, additives, purification of the electrolyte, current density, acidity, etc."

Jan 1, 2012

By Eduard Ouerra, Nuo Jin

"The use of polytetrafluoroethylene, PTFE, as a solid sorbent for elemental sulfur during pressure oxidation of chalcopyrite was investigated. The effects of agitation, PTFE particle size and lingin sulfonate addition were evaluated using leaching conditions that were otherwise similar to those employed in the CESL process. The effects of these factors and their interactions on chalcopyrite oxidation are explained in terms of interfacial forces and solid-solid interactions. Using relatively fine PTFE powder with vigorous agitation resulted in about 100% copper extraction in less than 90 minutes without the need for grinding of the flotation concentrate.IntroductionThe extraction of copper from sulfide ores has always been dominated by the conventional pyrometallurgical smelting process. Though much effort has been made to develop various hydrometallurgical processing routes, smelting remains as the dominant process, treating approximately 80% of the chalcopyrite concentrates worldwide [1]. However, some of recently emerged techniques for treating chalcopyrite through hydrometallurgical routes are showing results that are competitive with smelting in terms of economical feasibility. Representative methods include: Activox Process, CESL Process, Anglo/UBC Process, High Temperature Pressure Oxidation, and Bio-Oxidation. Among these, the CESL processes operate at a medium temperature range (typically 140-150GC) and oxygen pressure of 100 psi, with chloride as a catalyst, and reportedly achieve copper extractions of about 95% with a light regrinding of flotation concentrate to a p95 of 45 ìðé [2]. In spite of this satisfactory extraction result, the leach residues contain significant amounts of conglomerates which contain a small amount of unreacted concentrate [2], The conglomerations are formed because the elemental sulfur generated is liquid and sticky (melting point of sulfur being 119°C), and has a tendency to wet the sulfide mineral surface, a fact which inhibits the oxidation of the minerals. The overall process chemistry of the CESL process may be summarized as follows [3]:"

Jan 1, 2012

By Munyaradzi Kwatara, Ron Schonewille, Edgar Peek, Juzer Tayabally

"The potential recovery of nickel from a South-American saprolitic laterite ore using the segregation roasting technique was investigated. The ore was heated to temperatures that ranged between 900 and 1 000°C in a rotary kiln. In all the tests, the laterite ore was first mixed with a predetermined amount of calcium chloride and either coal or coke. By varying the temperature, calcium chloride and reductant in the different tests, a preliminary set of optimal conditions was established for the specific laterite ore that was tested. A combination of chemical analysis and electron-probe-micro-analysis (EPMA) were used to determine and evaluate the effectiveness of segregation roasting on the recovery of nickel. The present paper describes the test procedure and the results that were obtained.IntroductionIt is known that laterite ore resources account for an estimated 72% of the world's nickel resources, with sulfide sources accounting for the remaining 28%. Yet sulfide resources account for 58% of the world's primary nickel production while laterite resources account for the remaining 42% [I]. There are numerous reasons for this discrepancy, but the most important one is the mineralogical and compositional complexity that is associated with laterite ore deposits. For example, this complexity currently offers only limited opportunities for upgrading, thereby creating capital intensive whole ore processing facilities. It then follows logically that the identification and application of a low-cost processing option for the treatment of laterites could potentially open up an opportunity for exploiting these vast untapped laterite resources.To this end, a preliminary screening investigation was initiated by Xstrata Process Support to evaluate the potential application of the so-called (nickel) segregation process as a unit operation that could potentially be integrated into a laterite processing flow sheet. Laboratory bench tests were performed on this segregation process and this paper details some of the findings from this preliminary investigation."

Jan 1, 2011

By Milton Manrique, Edgar E. Vidal, Patrick R. Taylor

"Ultrafine zirconium carbide powder has been synthesized using zircon concentrate and methane in a thermal plasma reactor. The effect of several experimental variables, such as power used and zircon particle size, on the conversion has been studied. A thermodynamic analysis of the possible reactions and stable compounds was performed. A mathematical model that describes the in-flight decomposition of zircon particles was developed based on a description of the temperature and velocity profiles calculated in the reactor. It was shown that the formation of zirconium carbide from zircon and methane is thermodynamically possible. Complete 'vaporization of zircon in the reactor is predicted when the particle size is below 45flm and the effective power entering the reactor is 15 kW. The powders were collected and characterized by XRD, SEM, TEM and chemical analysis using ICP. Results of the product analysis indicated the presence of zirconium carbide, zirconium oxide, silicon carbide and silicon oxide.IntroductionIn recent years there has been an increased interest in the production of nanometric sized powders of ceramic materials for use in advanced materials applications. One possible method to produce these powders is with a thermal plasma reactor, which offers high temperatures and fast quenching rates. This technology has been called - Thermal Plasma Synthesis - [1].Zirconium Carbide (ZrCx) has typical properties of transition metal carbides: elevated hardness - between alumina and diamond - a high melting temperature of 3420°C and high chemical stability at room temperature [2]. ZrCx has a Bl crystal structure with deficiencies in the number of carbon atoms in the cell with x between 0.6 and 1 [3]. Different methods have been used to produce ZrC, one method is by direct reaction of zirconium hydride or halide with carbon. Other methods used are direct reduction and carburization of zirconium oxide (Zr02) and reaction of metallic zirconium with a caburizing gas such as acetylene [3]. Recently small films of ZrC have been obtained using a sputtering device [4,5]. ZrC has been used in nuclear plants as a low neutron absorbing and high mechanical resistant refractory material and also as a constituent in cathodes made of UC-ZrC [6]. It is also used in the form of tubes, boats and crucibles to handle molten metals and as part of electronic devices used for thermoionic transducers. Recently ZrC has been used along with zirconium diboride (ZrB2) to produce composite materials [7,8]."

Jan 1, 1996

By J. Vander Linden, R. De Ketelaere, M. Verhaege

In this paper, results are presented concerning the search to implement Supported Liquid Membrane (SLM) technology for the recovery of copper from electroplating effluents. Acid copper electroplating rinse solutions or effluents resulting from the post-treatment of, for example, cyanide-containing copper electroplating baths all contain copper (2+) in the lower concentration levels. A thorough study of the influence of the individual parameters and of their combined impact on mass transfer in small scale laboratory SLM modules has been performed, enabling to set forward the appropriate operating conditions for a pilot plant installation. The pilot plant, containing two SLM modules. of 18 m2 of surface area, has been tested extensively, including short and long term runs, with real process solutions. It was demonstrated that this installation is able to treat 40 l/h of acid copper sulphate rinse solutions· containing 500 ppm of copper. The final copper concentration in the effluent can be reduced to a few ppm while copper metal is recovered by electrolysis of the concentrate. This technology is also applicable to the treatment of solutions with low copper content of origins other than plating shops, such as tailings from copper plants or mine waters.

Jan 1, 2000

By R. D. Osmanson

A series of batch roasting tests was performed on minus 1/2 inch gold bearing refractory samples from the Gold Acres deposit, and 67 select particles were polished and the sulfide alterations were examined microscopically. The suite of specimens represents two hour batch roast treatments at 600°C, 700°C, 725°C, 750°c, 800°C, and 900°C. Auriferous pyrites were found to alter sequencially to pyrrhotite, magnetite and finally to hematite. It was found that the decrease in cyanidation extraction with high temperature roasting is likely due to the increas ing stability of magnetite and more crystalline hematite, and the decrease in porosity with these phases which occlude the gold. Gold has been noted to occur very early in the mineralizing sequence, with gold being found in quartz and in clay/carbonate rock matrix. No gold was found in the two pyrite phases, but numerous gold grains were found in pyrrhotite after pyrite and in subsequent iron oxides. Gold mineralization had apparently ended by the time base metals were introduced into the deposit.

Jan 1, 1987

By Richard H. De Voto

The McDonald Gold Project and two satellite gold deposits near Lincoln, Montana, contain at least 9.9 million ounces of gold and 30 million ounces of silver. The McDonald gold deposit alone contains 7.2 million ounces of gold reserves that can be open-pit mined and processed by cyanide heap leaching at a projected cash operating cost of $190 per ounce. The deposit is predominantly oxidized with no chance of acid production, and can be mined, operated, and reclaimed with minimal permanent environmental disturbance other than the creation of an open pit filled with a fresh-water lake which would support trout. The Seven-Up Pete Joint Venture, the owner of the McDonald Gold Project, commenced permitting of an open-pit, heap-leach operation in November 1994. In 1998, Montana citizens passed an anti-cyanide, open-pit mining initiative, 1-137, which banned any new open-pit gold mine which uses cyanide processing, The Venture has conducted extensive studies, including metallurgical testing of the treatability of McDonald ores with alternative lixiviants, and has determined that all other mining and metallurgical treatment systems are vastly uneconomical in the recovery of gold and silver from the McDonald deposit. Therefore, the Venture's proposed open-pit mining and cyanide heap-leach processing is the only technology that can be applied economically to the McDonald deposit. Further, the analyses convincingly demonstrate that the proposed open-pit, cyanide heap leaching technology results in maximum resource conservation of this valuable and unique deposit and poses far less risk to human health and the environment than any of the alternative technologies.

Jan 1, 1998

By Billy W. Osborne

The use or primary dross as a source for aluminum ion in the manufacture of aluminum sulfate offers opportunities for an inexpensive raw material. The aluminum sulfate industry in the US is a mature market with numerous small plants operating close to major users. The majority of manufacturers use either bauxite or aluminum oxide trihydrate as a source for the alum¬inum ion.. However, using process technology developed and patented by IWC, the oxides are removed from primary dross for use in manufacturing aluminum sulfate prior to metal recovery. This process offers the benefit of reducing costs for metal recovery. This paper discusses some of the methodology used in this process.

Jan 1, 1995