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By E. M. Timoshenko

Autoclave technology can be effectively used for liberation of complex mineral raw materials to transfer valuable constituents into solution for their subsequent recovery or to refine feed material in order to remove deleterious impurities, e.g. arsenic. The high efficiency of autoclave processes is attributed to the fact that they are suitable for processing of refractory raw materials, have low capital costs, high productivity, ensure integrated utilization of the feed materials, produce innovative saleable products, completely eliminate any air emissions, provide low-waste or waste-less technology, mechanization and automation of production processes. In the immediate future, it might be expected that autoclave processes will find use on commercial scale for production of heavy non-ferrous metals in combination with other processes (hydrometallurgical, upgrading, sorption and solvent extraction, electrolytic, etc.) to ensure: - Integrated processing of refractory ores and concentrates (pyrrhotite, zinc, copper-zinc, lead-zinc, nickel-cobalt, copper, pyrite); - Production of metallic powders of base metals as commercial products (copper, cobalt, nickel, etc.), composites on their bases, final products and saleable salts. Processing technologies incorporating autoclave processes, especially at the stage of liberation (chemical upgrading) of raw materials are characterized generally by high overall recoveries of valuable constituents significantly exceeding recoveries common for conventional pyrometallurgical processes (for some elements by several tens of percent).

Jan 1, 2006

By Melvin A. Jennings

Ion-exchange technology for precious metals recovery is at a turning point. Some very exciting technology has been developed in the past five years which should lead to commercialization of the process. Ion-exchange will allow not only for the recovery of gold and silver, but also will allow for the recovery of cyanide form plant tailings. This process may soon be competitive with Merrill-Crowe for silver and once this occurs, it will become the process of choice.

Jan 1, 1991

By Zachery Zanetell

Flotation circuit performance has become increasingly more challenging due to the complexity of available ore sources. To optimize value mineral recovery, the mineralogical composition of the ore should be evaluated and understood. Utilizing a variety of mineralogical and analytical tools, flotation processing challenges can be overcome and potential limitations understood. In this paper, several case studies will be discussed in terms of the value that has been provided through the use of mineralogical analysis to optimize flotation performance.

By William James Middleton

The life-cycle assessment (LCA) approach can be an important tool for the quantification and evaluation of environmental impacts associated with metal production systems. At the conceptual phase of a new metals development project, LCA can: ? Aid project decision making by evaluating the environmental consequences of design decisions ? Support project permitting and reinforce site/process environmental impact assessment ? Allow environmental impact comparisons between alternate flow sheets For existing metals production systems, LCA has been used to aid targeted process improvements by monitoring recent historical trends in environmental performance, either through local or external (externalities) process improvements. This paper discusses the life- cycle assessment methodology, and its application as a supportive tool for environmental decision-making in process design and operation, and for site environmental impact assessment and permitting. Selected examples from a recent LCA performed on the Pressure Acid Leach Process for treating nickel Laterite ores are employed to demonstrate the usefulness of the tool.

Jan 1, 2004

By Pedro Morales

At present the Codelco´s smelter & refinery business have growing complexities, concentrates with lower copper grades, higher impurities contents, and environmental restrictions which have lead to refocus the Codelco business, not only by considering the isolated developments for each of the Codelco´s Smelt & Ref complexes, but also as an integrated corporative complex scheme which improve the economy of scale, optimize the synergies, and include new technologies for higher productivity and lower operational costs. Accordingly, for the 2008-2012 period, Codelco have prepared a Development Plan integrated to the smelters and refineries business units that improve its single potentialities of and include the advances for the Teniente Converter [1] and Continuous Converting [2] Technologies, and also include the concept of uncoupling the smelting process from the converting process allowing a higher operational flexibility, and a better control of its contaminants. Thus, processing the white metal generated in the Teniente Converter unit of the smelter A into the smelter B has comparative advantages. These changes in the business concept allow an overall increment of the smelting capacity by processing only white metal as a final product through a very marginal investment in this way the total or partial conversion of the white metal into blister copper is eliminated allowing to use the available gas capture-treating capacity, and available acid plants for increase smelting capacity as well.

Jan 1, 2006

By Ashok D. Dalvi

Production of nickel from laterite ores has occurred for over 100 years beginning with processing of garnieritic ores from New Caledonia. However, until now the world nickel supply has been predominantly from sulfide sources. Going forward, the authors project that the production of nickel from sulfide ores will remain more or less constant. Most of the expansion in nickel production capacity over the next ten years will come from processing of laterite ores. Thus the capital and operating costs of new laterite projects will have significant impact on the nickel supply and therefore price. The authors have reviewed the history and capital and operating costs of various recent laterite projects and capital and operating costs of these projects and those "on the drawing board". The authors have also evaluated the risk associated with such projects. The paper will discuss the impact of this and the recent history on the future development of laterite nickel projects.

Jan 1, 2004

By Wenying Liu

The effect of aeration on chalcocite heap leaching was studied by analyzing the historical data from two chalcocite heap leach pads located in Chile, one with aeration and the other without aeration. The data showed that the copper leaching kinetics of the aerated heap was greater than that of the unaerated heap within a certain leaching period, after which there was no effect of aeration on the copper leaching kinetics. The total acid consumption per ton of ore processed was higher in the case of aeration, which was supported by the higher pH of the PLS. But the net acid consumption per ton of copper produced was the same in the two cases. Approximately 5% of the total iron added to the unaerated heap was precipitated inside the heap. In contrast, there was no net iron precipitation or generation inside the aerated heap. Bacteria activities were thought to occur even in the unaerated heap, but the extent was much less than in the aerated heap. Given the importance of forced aeration in chalcocite heap bioleaching, mathematical modelling will be applied in the future work to assist the optimization of the aeration system design.

By Ruth Marlene Campomanes Santana, Michel Tieccher, Marcondes Mafacioli Pacheco, Juliano Urach

"IntroductionThe gaseous emissions of fuel burning by mobile sources are responsible for incidence and increase of many lung and cardiovascular diseases (Braga et al., 2007). These implications can watch in morbity as much as mortality, even when the levels of pollution are considerate restrained or lower. (Leite et al., 2002).Sample of mobile sources exhausts contain not only particles directly shaped by burning, but also secondary particles that results of reaction between other compounds (Burtscher, 2004).One of the principal pollutants produced by combustion process with major toxicity and raiser of adverse effects to health is the particulate material. In its constitution there are fine and ultrafine particles that can to extend deep portion of breath system, break epithelial barrier and reach the interstitial of lungs and then, to unleash inflammatory process (Arbex, 2004).The Particulate Material is employed to define a mixture of solid particles and liquid drops suspense in atmosphere. Queiroz et al. (2007) declare that this material can be divided in two types separated by size interval that together, represent the major class of disperse particles: the fine particles type of 2,5 µm de (breath particulate) and the type of earthliness particles, major than 2,5 µm to 10 µm (inhale particle). The difference of size between the particles influences on the physics and chemistry properties. They affirm that exist correlation between size of particle and heavy metals; how many lower was the dimension of particulate materials, major is the concentration of heavy metals.The inhale particulate (MP10) that is object of present study can exhibit in your composition sulfates, nitrates, amoniacal, marine salt (NaCl), soil elements (Al, Ca, Fe, Si, Ti), metals (Cd, Cr, Cu, Ni, Pb, V, Zn) and water (Queiroz et al., 2007).Recent studies have exhibit strong relation between daily levels of particulate material inhale (MP10) with diameter until 10 µm and others pollutants and one infinity of effects to health that go since total mortality of population, sicken for specific causes until congenital bad formation or even difficult win weight by the fern during gestation (Gouveia et al., 2006)."

Jan 1, 2008

By John Frederick Colloghon, O&apos

Bulong remains the only hydrometallurgical process plant in the world that recovers nickel and cobalt directly from high pressure acid leach (HPAL) laterite leach liquors without need for precipitation of an intermediate product (e.g. sulphide, hydroxide or carbonate). Direct solvent extraction (DSX) of both nickel and cobalt in combination with electrowinning of nickel has been operation at Bulong since early 1999. Focus in the first years has been on ramp-up and resolution of commissioning problems. More recently the focus has been on de-bottlenecking and process optimisation. A number of significant process problems have been resolved, the most difficult being the formation of gypsum in the nickel solvent extraction circuit. Sound control of process chemistry is essential to ensure the production of high quality nickel and cobalt products at the lowest possible cost. This paper describes the numerous changes and enhancements to the process chemistry and plant equipment at Bulong and discusses the importance of ore leach chemistry on downstream impurity metal removal. Potential additional enhancements to further reduce unit costs are also presented.

Jan 1, 2004

By Song Ning

The main mineral constituents of phase-transformed chalcopyrite are CuS and FeS2. CuS is more soluble than FeS2 in an acidic CuCl2 solution with presence of excessive NaCl, so that FeS2 could be removed as solid residue from a leached solution. The experimental results showed that the efficiency of the copper leaching is heavily determined by the following two factors: a) The degree of the chalcopyrite phase transformation to CuS and FeS2 b)The concentration of Cl during the leaching, specifically whether there is enough excessive Cl existed. I t was found that when the Cl in the solution is not excessive, the slowest step of the leaching is the dissolution of Cu2Cl2.

Jan 1, 2006

By Paykan Safe

The primary source of fugitive gas emissions in most copper smelters are the Peirce Smith converter operations. The modem trend is towards installation of secondary gas collection systems which are intended to collect fugitive gases from charging, standby, and skimming operations. These have been installed with varying degrees of success. Often, the major source of emissions from the converter area is leakage of process gas from the primary hoods when the converter is blowing. This gas is typically collected by the secondary system and discharged to atmosphere or scrubbed with an alkaline agent. Those smelters considering installation of secondary hoods or scrubbing of gases from secondary systems should first address the issue of gas leakage from the primary hoods. Improving the primary hood gas collection efficiency will often be more cost effective than installing secondary hooding. In the case of secondary gas scrubbing, it will significantly reduce the reagent consumption and operating cost of the scrubbing system. This paper examines the parameters that determine whether or not a primary hood will effectively collect process gases without leakage and demonstrates, using Computational Fluid Dynamics (CFD), the effects of variations in these parameters on the overall performance of the hood. It also looks at the application of CFD techniques in the design of secondary hoods and presents a summary of measured emissions from converter buildings.

Jan 1, 2002

By Jeaneth S. Benedetto

The physical and chemical processes developed for recovery of uranium and phosphor from phosphoro-uraniferous ore bodies consists of three basic steps: concentration of the phosphate bearing uranium by flotation, chemical dissolution of the concentrate by wet phosphoric acid and extraction of uranium by solvent. In this process two products are obtained: 1) uranium and 2) phosphoric acid. The purpose of this work was to develop technological know-how of phosphoric acid purification though an extraction of P2O5 by solvents. It was investigated by two lines of research. In the first one the uranium was extracted before the phosphoric acid purification. In the second, the phosphoric acid was extracted before uranium recovery. The comparison of the two processes is shown in this paper. Experimental work was developed on a laboratory scale to select and optimize the process variables. After the laboratory study, the research of extraction and stripping was continued on a pilot scale in pulsed perforated-plate columns in order to investigate the main operational and process conditions. The first phosphoric acid extraction experiments showed good results using a raffinate sample obtained from the uranium extraction process. It was possible to obtain a high purity phosphoric acid.

Jan 1, 2003

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By N. D. Schupp

The Doe Run Company's Herculaneum, Missouri lead smelter has existed in continuous operation since 1892. Throughout the history of the plant extensive developments have been made to improve throughput, increase productivity, decrease operational costs and improve technology, while remaining an environmentally responsible producer of high quality primary lead in the international market. This paper provides an overview of the Herculaneum smelter, focusing on the most recent configuration of the operations. The paper includes discussion on all the aspects of primary lead production at the Herculaneum smelter.

Jan 1, 2000

By Jitka Jandová

A laboratory process based on simple and environmental friendly operation, aimed at recycling of spent Li/MnO2 batteries, is described in this study. This process involves roasting Li/MnO2 batteries in a vacuum furnace at 650°C, followed by selective leaching Li2CO3 from calcined electrode material in distilled water at ambient temperature and controlled crystallization of pure Li2CO3.

Jan 1, 2006

By C. L. Kusik

Environmental issues are having a significant impact on how automobiles are designed and ultimately disposed of at the end of their lives. On one hand, increasing concerns about landfill disposal have resulted in greater attention being focused on recycling materials and components from old junk autos. On the other hand, corporate average fuel economy (CAFE) requirements have led to downsizing, use of coatings, materials substitution and other measures that often make recycling more difficult. Automobile makers have responded to Corporate Average Fuel Economy (CAFE) Standards in a variety of ways such as: Downsizing; Designing of more fuel efficient engines; Reducing aerodynamic drag by sleeker body designs; Redesigning by using thinner gauges of coated steels; and Substituting material such as lightweight plastic or aluminum parts for steel. Other driving forces affecting production techniques, choice of materials and recycling issues include the Clean Air Act and its amendments, RCRA. and other environmental legislation. The variety of materials used in automobiles makes the recycling issue extremely complex. Not only does one have different materials used in different automobiles for making similar parts, but changing designs, evolving environmental issues, landfill closures affecting solid waste disposal, and increasing raw material quality standards have created a complex set of dependencies related to materials use and recycling.

Jan 1, 1994

By A. N. Aposhian

The electronics industry generates tin/lead bearing by-products that can be recycled for their metal value. This paper will cover the processes used to recycle these tin/lead bearing byproducts from the plating, circuit-board fabrication and assembly industries. Though these processes are well known to the companies who do the recycling, few outside the industry including the generators of the by-products, understand the processes or needs of the industry. This paper will give a broad overview of these processes, and describe the services provided by this industry. The paper will also touch upon the future of the recycling industry, including the legislative and environmental push for the elimination of lead from electronics.

Jan 1, 2000

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By H. Kurama

In this paper, utilization of fly ash as a value added product in areas such as novel materials, waste management, fillers and agriculture is reviewed with the aim of helping the expand of the usage of fly ash and reduce the environmental and economic impacts of disposal. The used unburned carbon benefication/treatment methods such as low temperature combustion, froth flotation, partical size classification and electrostatic separations to remove unburned carbon particles from fly ash are also discussed.

Jan 1, 2006

By Tang Chaobo

Employing manganese carbonate ore and zinc oxide dust as material, Mn-Zn compound oxide powder for soft magnetic ferrite was prepared by a serial methods, as follows: leaching by using sulfuric acid, removing aluminium and silicon by neutralization and flocculation method, using ammonium bicarbonate to co-precipitating Mn and Zn, calcinations and washing to removing impurity content. The optimal technical condition was obtained by experiments. The difficulty of removing impurity such as Si, Al, Ca, Mg, from leaching solution was solved. The impurity content in the production meets with the preparation standard of high quality soft magnetic ferrite. The compound oxide powder obtained in the experiment was made into lower power loss magnetic ferrite, the quality of magnetic ferrite meet the standard of PC40 which was established by TDK corporation.

Jan 1, 2006