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By Nickolas J. Themelis

The role of copper in the economy will not diminish in the 21st century. Following the tenets of industrial ecology, production and use of copper must take into account both human needs and also how to minimize "collateral" effects on the environment. Dispersive uses will be phased out and post-use recovery of copper will increase. This will result into an advantage for smelting processes that can accommodate mixed metal scrap and waste streams. The bath smelting processes of Noranda and Mitsubishi will continue to make progress but the dominance of the Outokumpu flash smelting will not be challenged until the Noranda reactor overcomes the obstacles to the direct production of copper, thus eliminating the need for a converter.

Jan 1, 1999

By Sridhar Seetharuman

Sulfur and oxygen dissolved in nickel and cupronickel melts can be removed as gaseous oxides of sulfur by a vacuum treatment. Presented in this paper is a new matched thermochemical diagram that permits direct evaluation of the equilibrium partial pressure of SO, as a function of temperature over an alloy of specified composition. The matched thermochemical diagram consists of a central plot which shows the integral Gibbs' energy of mixing for the binary system S-O2, at different temperatures. The central plot is flanked on either side by terminal plots of the chemical potentials of oxygen and sulfur, as functions of temperature, for different alloy compositions. By projecting the chemical potentials of oxygen and sulfur from the terminal plots on to the central diagram, the equilibrium pressure of SO2,can be directly read on the nomograms on the central plot at different temperatures. The matched thermochemical diaerams are - useful in assuring the efficiency of vacuum refining.

Jan 1, 1993

By Valentine A. Chanturiya

The aim of this paper is basically to show progress in the study of nanosecond processes involved in the disintegration and breaking-up of mineral complexes with fine noble metals. We studied the influence of nanosecond High-Power Electromagnetic Pulses (HPEMP) on the physical and technological properties of refractory gold-containing ores and beneficiation products. Experimental data are presented to confirm the formation of breakdown channels and selective disintegration of mineral complexes as a result of pulse irradiation, which makes for efficient access of lixiviant solutions to precious metal grains and enhanced precious metal recovery into lixivia during leaching. Preliminary processing of gravity concentrate with a HPEMP resulted in significant increase of gold and silver extraction into lixivia during the cyanidation stage, with gold recovery increased by ~31% (from 51.2% in a blank test to 82.3% after irradiation). Gold recovery from stale gold-containing dressing tailings products increased after pulses-irradiation from 8-12% to 80-90%.

Jan 1, 2006

By Ruiqing Li

It is possible to purify some liquid metals by exploiting the difference between the vapour pressure of the bulk metal and the minor constituents or impurities. The rates of purification can be improved by carrying out the process under reduced pressure, that is, so called, vacuum. Some commercial examples of vacuum refining are the purification of molten tin to eliminate trace amounts of lead and the refining of cobalt, also to remove lead. The objective of this paper is to review the basic theory behind vacuum refining technology in order to show how the feasibility of vacuum refining can be determined simply for a particular system by evaluating Olette's Volatility Refining Criteriont.

Jan 1, 1991

By Paul S. Korinko, Simona E. Hunyadi Murph

To address a radiological contamination event, a materials and process project was initiated. During the course of this project, processes and materials were developed that successfully captured zinc vapors physically and chemically, respectively. However, the physical traps were placed in an undesirable area and it was determined that the chemically captured zinc reactions was reversible. Consequently, advanced nanomaterials are being developed to capture zinc vapors. The current state of the art of the science and engineering of these materials and their efficacy for zinc capture and retention is discussed in this paper.

Jan 1, 2015

By G. L. Watt

Fine sized titanium diboride (TiB2) powders have been synthesized in a thermal plasma reactor. Precursor for the synthesis were rutile, boron oxide, and methane. The effect of plasma gas type, precursor ratio, and input power on the synthesis was studied. The produced powders were characterized by X-ray diffraction and chemical analysis. The purified powders were CIP'd, HIP'd, sintered and characterized for porosity, hardness, and microstructure and the results compared with a commercially available TiB2 powder sample.

Jan 1, 1995

By David C. Lynch

The molecular form of trace elements in matte has been shown to depend on the chemical potential of sulfur and the propensity of the trace element to form a sulfide. Of the four trace elements (As, Sb, Bi and Pb) arsenic and lead behave nearly as opposites, with lead readily forming a sulfide while arsenic forms complexes with free copper and ion in the matte. Antimony and bismuth both display the dissolution characteristics as As and Pb, suggesting that these elements dissolve in matte in multiple forms of significant concentration. While in the present investigation the dissolution characteristics of all four trace elements are examined, the primary focus is on the multiple dissolution behavior of Sb and Bi.

Jan 1, 1995

By Mike Santaluce

Smelting furnace rebuild projects often require a significant capital expenditure and an extended smelter outage. Smelter operators are increasingly searching for methods and initiatives to shorten furnace rebuild schedules, maintain manageable cost levels, enhance furnace performance and achieve excellent safety results. This paper describes the ?MEPC? Model for furnace rebuilds; a project driven approach which Auburn has developed in response to the need for improving furnace rebuild project outcomes. The ?MEPC? (Management, Engineering, Procurement and Construction) approach better addresses the unique challenges presented by furnace rebuild projects when compared to the traditional EPCM (Engineering, Procurement, Construction Management) model widely in use for these projects today. One key feature of the MEPC model is that a dedicated project management team with representation from all of the major project stakeholder groups is put in place at the onset of the project. The project management team has ownership and accountability for meeting overall project goals over the entire lifecycle of the furnace rebuild project. A second key aspect of the model is emphasis on project management as a completely separate project function with its own specific skill sets, techniques, tools and best practices. These features of the MEPC model offer several advantages in terms of improved planning, coordination, communication and alignment with project goals which contribute to the overall success of furnace rebuild projects. Similar MEPC concepts have been used to deliver excellent project results in other industries and the MEPC approach has been successfully utilized on furnace rebuild projects.

Jan 1, 2006

By Yi Tan, Kazuki Morita, Yaqiong Li

Molten Si-Al alloy, with the addition of Sn, was used for metallurgical grade Si purification by a low-temperature solidification method, with the aim of improving the recovery rate of Si. In this ternary melt, bulk Si was grown with a planar front by a directional solidification process under a well-controlled thermal gradient and growth rate conditions, thereby reducing the contamination of solvent metals. Effects of cooling rate, amount of Sn addition, and temperature gradient on the quality of bulk Si were determined. The criterion for constitutional supercooling for single-phase growth from multicomponent melts was employed to evaluate the growth process.

Jan 1, 2015

By Chr. Kersch

This project further develops supercritlcal fluid extraction as an industrial soil remediation process. Heavy metals are removed from sand using CO2, The effect of the type of complexing ligands, pressure and water content on the extraction efficiency is investigated.

Jan 1, 1999

By Guangqing Zhang

The paper presents results of a systematic study of synthesis of titanium oxycarbide and its chlorination. Titanium oxycarbide was produced by carbothermal reduction of titania in hydrogen, argon and helium. Formation of titanium oxycarbide started at 1200°C in all gases. The reduction was the fastest in hydrogen. Formation of titanium oxycarbide in hydrogen was close to completion in 120 min at 1300°C, 60 min at 1400°C and less than 30 min at 1500°C. Reduction in argon and helium progressed at a similar rate and reached 90-95% after 300 min at 1400-1500°C. The chlorination of titanium oxycarbide was ignited at 150-200°C. Chlorine partial pressure and gas flow rate strongly affected the chlorination rate. Chlorination of titanium oxycarbide produced with carbon to titania molar ratio 2.5 at 235-400°C was close to 100% in 30 min.

Jan 1, 2009

By James P. Bennett, Jasper Kwong

As concerns about the environment and the disposal of industrial wastes increase, the utilization of spent refractories from electric arc furnaces (EAF) is receiving more attention. Longer service life of refractories in an EAF can be achieved by foaming MgO saturated slag. The refractory wastes removed from a melt shop can be utilized as a part of these slags. The Albany Research Center is conducting research on recycling spent basic refractory materials as EAF slag conditioners. A good foaming slag should be a creamy, MgO saturated slag, which contains some solid particles (MgO-FeO). A computer model was developed to calculate the dual saturated slag chemistry with respect to CaO and MgO, the MgO saturated slag chemistry, and the solid content in solution. The effects of C/S ratio, AhO3 and temperature on the MgOsaturated slag as calculated by the model will be discussed.

Jan 1, 2000

By Zeljka Pokrajcic

Crushing and grinding, or comminution, circuits are the most energy intensive process of a mineral processing plant. Comminution involves the physical size reduction of an orebody to a particle size sufficient for recovery of the mineral values. However, the comminution process remains inherently inefficient. The inefficiency is a result of the operating nature of comminution devices such as grinding mills, where transfer of energy between grinding media and particles in unconstrained and completely random. New comminution circuit design strategies are presented in this paper. The aim of the new strategies is to improve the overall efficiency of the comminution process and reduce the total energy consumption of a comminution circuit. The energy efficient strategies include the: ? rejection of coarse size liberated gangue from the comminution circuit and further downstream size reduction ? use of more efficient grinding and crushing equipment ? the selection of coarser particle product sizes to alleviate the increased energy intensity required to achieve finer product sizes Singularly and when combined, these energy efficient strategies can significantly decrease the overall energy consumption of a comminution circuit. This paper also explores the financial impact of certain energy efficient strategies using an analysis tool called EcoNomics?. It shows that substantial financial gains can be made by including more efficient technologies and methods in comminution circuit design.

Jan 1, 2010

By William Petruk

The primary requisite for a successful extractive metallurgy operation is to grind an ore fine enough to liberate the minerals so that they can be concentrated, or to expose mineral surfaces so that the minerals can be leached. The ease or difficulty of liberating or exposing the mineral grains is dependent upon the mineral textures such as grain size, crystallinity and bonding between mineral grains. In particular, mineral grains with straight grain boundaries and a weak bonding to other minerals are easily liberated and readily concentrated into high grade concentrates. In contrast mineral grains that have re-entrant boundaries and are strongly bonded to their neighbours are not easily liberated and will not produce high grade concentrates, even with regrinding. Similarly, inclusions that occur along fractures and grain boundaries can be readily exposed and leached. Whereas minute random inclusions in large grains will not be liberated or exposed unless they occur along planes of weakness.

Jan 1, 1995

By Joel F. Flurnerfelt

Molten Al and Al alloys containing si, Mn, Ti, and y have been lanced with nitrogen-bearing gases. These lancing experiments provided the means for observing what phases form during exposure to nitrogen-bearing gases for finite periods of time, <2 minutes, at high temperatures, >1290oC. The experiments were conducted in sn induction heated drop tube furnace apparatus. The overall premise of these experiments was to select those Al alloys and gas compositions that show promise of forming secondary dispersoid phases, particularly AIN, in the Al matrix. The alloys selected will be atomized using gas atomization reaction synthesis (GARS) using the most favorable conditions. In this case, the chosen Al alloy will be atomized with a nitrogen-bearing gas, such that the Al and gaseous nitrogen species react to form a dispersoid phase within each powder particle. The powder particles that result from this "aggressive" GARS-process would be essentially Al metal-matrix composites within a uniform distribution of dispersoids. To date, only high-purity Al has been atomized using a mild GARS reaction. This work is funded by the Materials Science Division of DOE-BES under contract number W-7405-Eng-82.

Jan 1, 1996

By Pratheesh George

Solid state galvanic cell with CaF2 as the electrolyte was employed for determining the thermodynamic properties of Nb-Al binary alloys in the temperature range of 973-1073 K. The activities and activity coefficients of Al in NbAl3 were determined. The experimental procedure and the design and construction of the experimental setup have been also explained in detail. Aluminum activity in NbAl3 increased with increase in temperature and shows a strong negative deviation from ideality. The activities of aluminum in NbAl3 were determined to be 0.0165 and 0.0289 at 973 and 1073 K respectively. The stability of NbAl3 has been compared with other available intermetallic systems.

Jan 1, 2006

By O. E. Omotoso

This study is part of an ongoing investigation to understand the mechanism of stabilization/solidification of hazardous chromium wastes in ordinary Portland cement (OPC). Tricalcium silicate (C3S*),a major component of OPC is mixed with reagent grade Cr(lll) and Cr(VI) solutions, to simulate complex cementiCr waste systems. Scanning electron microscopy (SEM) and energy disperse spectrometry (EDS) were employed to provide microstructural and chemical information. Transmission electron microscopy (TEMlEDS), apart from complimenting the SEM, was used to probe the distribution of Cr in the hydration products of C3S and to provide crystallographic information. 29Si MAS NMR (magic angle spinning - nuclear magnetic resonance) Was used to characterize the influence of Cr on the hydrated silicate structure.

Jan 1, 1995

By Yongqi Sun, Zuotai Zhang

Our study investigated the influence of P2O5 and B2O3 on the viscosity and crystallization behavior of Ti-bearing blast furnace (Ti-BF) slags for the purpose of Ti extraction. The investigation of the crystallization behaviors were carried out using a single hot thermocouple technique (SHTT) and the viscosity was obtained by rotating cylinder method. For the viscosity, the results showed that P2O5 substantially increased the slag viscosity. P2O5 is a network-forming oxide, which increased the degree of polymerization of slags and accordingly increased the slag viscosity. However, both of slag viscosity and apparent activation energy for viscous flow remarkably decreased with B2O3 addition. As a typical network forming oxide, B2O3 was introduced into the network and existed dominantly as 2-D structure, BO3 triangular, which caused a simpler structure and a decreasing slag viscosity. As for the crystallization behaviors of Ti-BF slags, both P2O5 and B2O3 enhanced the crystallization trend of rod-shape rutile and suppressed the crystallization trend of dendrite CaTiO3. Therefore the added P2O5 and B2O3 caused the primary phase change from CaTiO3 to rutile. Additionally, it was found that the rod-shape rutile showed a 1-D growth, whereas the dendrite CaTiO3 showed a 3-D growth style.

Jan 1, 2015

By Takahiko Okura

"It is said that the energy and resources crisis will come before long because the lifetime of known deposits of crude oil and common metals such as Pb, Zn, Cu is estimated to be less than 50 years. Establishing the sustainable society by means of resources-recycling has become an absolute necessity.The non-ferrous metals industry in Japan has been involved in the resource- recycling business for many years, along with the introduction and enforcement of various legislations to preserve the environment and natural resources. Including process-linkage during various manufacturing activities, the non-ferrous metals industry, the iron-making and cement industries are treating considerable amounts of recycled materials and wastes, in an environmentally-sound and economic manner.The Mining and Materials Processing Institute of Japan has submitted “The present and issues in Japanese non-ferrous metals and recycling industries.”The topic of the paper is to highlight the actual conditions within the resources-recycling structures and the present issues.IntroductionGlobalization has been changing the world, introducing the spike of energy and metals price. In addition, the preservation of the environment has also been strongly facing the crisis and many people have been aggrieved by both shortage and the increment in the price of the meals.In the world of metals, even though their reserves are coming depleted, the production rates are increasing, and then the industry has to enhance their productivity under stricter environmental regulations. The Japanese industry experimented the same scenario some 40 years ago, facing big pollution problems, but concurred them and enhanced the technology to overcome the more severe regulations. It will be fruitful to present the current situation in the Japanese industry for the world. The present issues are also presented."

Jan 1, 2008

By T. Taniguchi

The existing Mitsubishi Process line at Naoshima Smelter and Refinery has been operating successfully since 1991, and its present production capacity is 270,000tpy of copper. Furnace relining works have been carried out every two years to coincide with the compulsory bi-yearly boiler inspection, but the next target is to extend the furnace refractory life to four years, while still undergoing the mandatory boiler inspection every two years. Although the damage of hearth bricks beneath lances in the Smelting furnace was a matter of concern, it was reduced by controlling gas velocity and evening solid distribution to each lance. The life of bath level bricks in the Converting furnace was also a concern, but four-years continuous use of the bricks was achieved in the course of the last two campaigns. Several other improvements were also carried out to the cooling systems during the shutdown in 2005 to ensure longer campaign life. This paper summarizes recent improvements implemented to enhance the advantages of the Mitsubishi Process.

Jan 1, 2006