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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 Kurt Westerlund

The design of the economically most profitable and technically most feasible smelter process gas handling .and treatment as an integrated part of the total metallurgical process is discussed and exemplified, with alternative flow sheets including material and energy balances, investment and operating costs. Retrofitting and de-bottlenecking of existing gas handling lines will be described and exemplified. Methods of increasing total gas handling line availability will be described.

Jan 1, 1992

By Esa J. Peuraniemi

Copper smelting to form blister in one single step has been possible for a long time even from low grade concentrates. In spite of obvious benefits, it has been economically viable only with few special raw materials having high enough Cu/Fe and Cu/S ratio. Outokumpu Blister Flash Smelting is currently applied at three operations, and three others will be commissioned in the near future. With typical chalcopyrite concentrates two main obstacles have prevented wider adaptation of direct blister processing: slag formation and heat generation. Oxygen potential in the reaction shaft must be high in order to produce blister with targeted sulfur content below 1%. When large amount of iron is oxidized, as well as sulfur, copper is inevitably also oxidized into slag. High copper amount in substantial tonnages of slag lead on to costly down stream recovery operations to obtain discardable slag. Almost complete oxidation of sulfur and iron releases a high amount of heat which traditionally has been solved by lowering oxygen enrichment of the blast leading on to oversized off-gas line and acid plant. One challenge in direct blister smelting relates to the attack of aggressive high-copper containing slag against furnace refractory lining. In continuously operated Outokumpu Direct Blister Flash Smelting this is taken care of by preventing vigorous melt movement in the settler. Stable bath conditions and stationary slag against refractory lining enable the formation of a protective autogenous layer between aggressive slag and vulnerable refractory. These direct blister smelting challenges are addressed from equipment and process development point of view. New solutions to overcome the obstacles are presented and discussed.

Jan 1, 2006

By Bryn Harris

Much has been written over the past twenty years on the removal and chemical stabilization of arsenic from metallurgical process solutions. This paper reviews again the latest developments in this field, and concludes as before that the high-iron arsenical ferrihydrites, together with the high temperature arsenic minerals, scorodite and Type II, remain as the best and most viable vehicles for industrial control and disposal. However, a cautionary note is introduced, in that chemical environments cannot be considered in isolation, and that cogniscence has to be taken of microbiological activity in determining the disposal method. Data are also presented on a survey of industrial practice, which shows that arsenical ferrihydrite is by far the most widely-practiced and accepted method used worldwide. Finally, the disaster in Bangladesh is briefly discussed with reference to lessons that the metallurgical community might learn from this.

Jan 1, 2003

By J. P. Rodier

Despite the good years that the non-ferrous business is now enjoying, one should not forget that in this business growth rates are low, fixed assets are high and prices are more cyclical than in other businesses. Increasing environmental concern puts the industry under pressure. Lead and zinc companies are now profitable and profitability in the next ten years will depend on size of units, location, and choice between new technology and upgrading current ones. Implementation of Metaleurope was a strategic move. It produced a company of sufficient size to achieve new steps in cost cutting and yet remain flexible enough to deal with rising variety of primary and secondary raw materials.

Jan 1, 1990

By Guilian Gao

TbFeCo is a common choice for many rare-earth transition metal films currently used as the magneto-optic layer for magneto-optical: recording devices. Since the environmental stability of RE-TM alloys is typically poor compared with traditional metal oxide particle media, such devices rely on multiple functional overlayers (metallic and/or dielectric) and organic coatings for durability. This paper presents an electrochemical evaluation of the degree of protection of several candidates for the reflective layer, Al, AlCr and AIPt and for the dielectric layer, SiN, AISIN and AIN. Cyclic voltammetry In 0.2M K2SO4 solutions at room temperature revealed that AIPt film offers superior corrosion protection compared to Al and AICr films. Of the three dielectric layers examined, SIN seems to be the most corrosion resistant. Examination by optical and scanning electron microscope confirm the findings of electrochemical experiments. The corrosion resistance of single layers of Al, AICr and AIPt has also been examined and factors affecting their performance are discussed.

Jan 1, 1992

By Asok Kumar Das

"In steel making ferroalloys occupies a commanding role for production of varied quality of steel. Ferroalloys enable alloying elements such as chromium, silicon, manganese, vanadium etc to be safely and economically introduced into metallurgical processes thus giving certain desirable properties of the alloyed metal. Their importance grew with the progress of the steel metallurgy which implied more diversified alloying elements, in better controlled quantities, in purer steel. The ferroalloy industry became a key supplier to the steel industry. Production of ferroalloys generally involves the use of Electric Arc furnace(EAF) into which raw materials(e.g. various metal ores, quartz, coke, lime etc ) with relatively fluctuating physical compositions are loaded. Due to this, one of the major environmental impacts of producing ferroalloys is the emission of dust and fume from the smelting process. INTRODUCTIONFerro Alloys are essential ingredients used for refining, de-oxidation, desulphurization and alloying addition in the production of different types of steel and hence Ferro Alloy industry forms a back bone of iron and steel in the world. Indian ferro alloy industry is more than 45 years old. It produces most of the bulk ferro alloys and a large number of special ferro alloys. The present installed capacity of the Indian ferro alloy industry is sufficient to meet the requirement of existing level of indigenous steel production of about 46 million tonnes. Revised National Steel Policy – 2008 envisages production of more than 100 million tonnes of steel by the year 2011-12, at proportionate annual growth rate per annum. The focus of the policy is to achieve global competitiveness not only in terms of cost, quality and product-mix but also in terms of global benchmarks of efficiency and productivity. In order to achieve the objectives of National Steel Policy and also to meet the requirement of ferro alloys, the Indian Ferro Alloy Industry has to gear up in terms of enhancement in production capacity, sourcing of raw materials, up gradation of technology, improvement in productivity, automation / mechanization, customer satisfaction etc."

Jan 1, 2008

By R. M. Luna-Sánchez

Electrochemical studies, particularly Evans? diagrams, have been employed in hydrometallurgy to simulate and explain the redox phenomena that take place at mineral and metal surfaces during operations such as leaching and cementation. However, despite their utility, in some cases, the combination of the cathodic and anodic branches, determined separately, does not reproduce the chemical environment present when both processes occur simultaneously on a specific surface. In the present paper, limitations of Evans? diagrams are analyzed through two examples: silver sulfide cyanidation and gold cementation on zinc. In both cases, the surface kinetics are sensitive to the local pH and cyanide levels. When the electrochemical oxidation of silver sulfide or the reduction of gold are performed in the absence of its corresponding redox reaction, the local pH obtained does not simulate the real situation and the combined reaction kinetics may be very different from those determined from the Evans? diagrams.

Jan 1, 2003

By Magdelinka Padenkova-Yaneva, Emilia Christova Kostakeva

"Environmental protection is becoming over the years an increasingly significant problem of mankind. Up to the last decade the only way to make the domestic waste harmless in Bulgaria was deposition on uncontrolled landfills without undertaking actions for protection of the soils. This also caused pollution to spread into the surface and underground waters and that is why actions are now undertaken for remediation of contaminated soils. This is achieved by developing projects for the closing down of polluted sites. In the present paper some projects for closing down of polluted areas are discussed. The actual conditions are examined and project decisions for preventing the surface waters from penetrating into the waste are presented. In this way the pollution of the soil is stopped and the soils are gradually remediate.IntroductionSoil is the topmost layer of the earth crust. It consists of mineral particles, organic substances, water, air and living organisms and is an extremely complex and changing living environment. Soil is a non-renewable natural resource which is of considerable importance in a number of crucial processes (production of foods, storing, filtrating and turnover of many substances, including water, carbon and nitrogen). It also serves as a basis for human activities, shaping the landscape, ground on which cultural heritage is built, and source of raw materials. These functions of soil must be protected both because of their social and economic significance and from the point of view of environmental protection.The processes of erosion, loss of organic substances, compaction, salination and contamination contribute to the degrading of soils accompanied by a negative impact on human health, natural ecosystems and changes in climate, as well as on the economy. All these make it necessary to protect soils from contamination. Over the last years intensive work started in Bulgaria for the construction of controlled sanitary landfills for rendering municipal solid waste harmless. Pursuant to Bulgarian legislation, in these controlled sanitary landfills measures are undertaken for protecting the soils from contamination through appropriate project decisions – the filtration of the products from the biological decomposition of waste into the adjacent sites (soils) and, therefore, the contamination of the surface and underground waters is prevented. At the same time the purity of air is maintained, human health is protected and conditions are created for including the controlled sanitary landfills into the surrounding landscape."

Jan 1, 2008

By C. A. Landolt

Inco pioneered the use of tonnage oxygen in non ferrous metallurgy when it commissioned the first .industrial oxygen flash smelting process for the treatment of copper concentrates in the early fifties. This technological innovation was followed by other applications of technical oxygen. Inco is currently implementing a Sulfur Dioxide Abatement Program designed to reduce S02 emissions from the smelter by 60% in 1994. The new flowsheet includes new equipment for the oxygen flash smelting of Cu-Ni concentrates and for flash conversion of chalcocite. Oxygen smelting and converting technology will lead to a substantial decrease in use of fossil fuels and to generation of high strength S02 off gases suitable for efficient fixation in a new acid plant.

Jan 1, 1992

By W. John Rankin

Professionals, technical and non-technical, working in the mineral and metal commodity industries need to understand the concept of sustainability and its implications for the industry. Undergraduate courses have not done this well in the past. Much has been written in this field, and there have been great advances in understanding. However, much of what has been published is superficial and sometimes misleading, and there is as yet no coherent, single account that can serve as an introduction or overview for mineral industry graduates. This paper presents an outline which can guide readers in developing an understanding of the topic and its relevance to their work. Key references are provided, particularly those accessible on the internet, which will serve to introduce the reader to the important principles and understandings. The guide should also be useful to academics preparing students to work in the minerals and metal production sectors.

Jan 1, 2010

By Christian Ludwig, Virginie Silberstein, Rizlan Bernier-Latmani, Simona Regenspurg

"Residues from waste incineration (bottom ashes) form large amounts of heavy metal-rich waste. Theoretically, heating and the addition of chloride to the ashes could remove these metals by formation of volatile metal chlorides. The remaining heavy metal-poor ashes could be used, for example, as cement additives. In the proposed process of our study we used bypass dust from the cement industry as chloride additives to the bottom ashes. We aim to determine experimentally the optimal conditions to remove heavy metals from ashes and to simulate this process by thermo- chemical modeling. In our experiment we investigate heavy metal flows by heating of differently composed mixtures of bottoms ash and bypass dust in dependence of different furnace temperatures (500-1200 °C). Furthermore, we investigate the reactivity (leaching characteristic) of the resulting product in order to predict if secondary residues can be landfilled in agreement to Swiss regulations for inert materials.IntroductionThe incineration of garbage is generally considered as the most environmentally friendly method for the reduction of municipal solid waste. This is because, compared to traditional storage of waste on landfills, incineration produces less greenhouse gases and destroys toxic organic compounds. The released exothermic energy can be recuperated and the residues from the combustion chamber (bottom ash) are strongly reduced in volume. However, they still form about 600 kt of waste per year in Switzerland, which needs to be landfilled. However, these residues could be potentially used as construction materials after mechanically recovering ferrous and non-ferrous metals. However, the resulting ashes (discharged dry or wet) still contain increased amount of heavy metals (exceeding state regulation) requiring them to be finally deposed on a hazardous waste site. A thermal treatment of these ashes could enable both, to separate and recuperate the remaining heavy metals and an inorganic heavy-metal poor material. The evaporation of metals depends on temperature and can be lowered by addition of chlorides, which would lower the boiling point of most metals by formation of metal chlorides (table 1)."

Jan 1, 2008

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 David M. Beckwith

Increased globalization and outsource manufacturing complicate the procurement and enforcement of intellectual property rights on a worldwide basis. Recent legislative and case law developments in the United States highlight the importance of a multinational intellectual property strategy. IP lawyers David Beckwith and John Hankins will discuss planning and pitfalls in this rapidly changing trans-border environment. Topics to be discussed include harmonization with international patent laws, protecting your technology and market space with a comprehensive approach to IP, and patent enforcement issues relating to import/export of products and components in the United States.

Jan 1, 2006

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 P. G. West-Sells

Recovery of gold from thiosulfate leachates can be accomplished by adsorption of the gold thiosulfate complex by a strong base resin. Two of the most significant impurities that can decrease this gold adsorption are tetrathionate and trithionate, which are produced as oxidation products of thiosulfate during gold leaching. This paper investigates gold adsorption on a strong base resin (Purolite A500C) as a function of the concentration of these impurities. It is shown that concentrations of tetrathionate and trithionate as low as 150 mg/L can decrease gold loading by an order of magnitude, and that of the two ions, tetrathionate has a stronger detrimental effect. The resin and solution gold concentration profiles were successfully fit using a Freundlich isotherm, which further shows the strong effect of tetrathionate. To counteract the decrease in gold adsorption by tetrathionate, a novel process was proposed. Sulfite was added to the solution to oxidize tetrathionate to trithionate, and a nitrogen blanket was added to ensure that no further oxidation of thiosulfate could take place. It is shown that by incorporating this process, gold adsorption was doubled from both synthetic and real gold thiosulfate leachates.

Jan 1, 2003

By Y. Mori, K. Kawanaka

The permeability changes during the sintering of the feed for the Imperial Smelting Process (ISP) were investigated using an experimental sintering pot, as well as with a mathematical model. The results obtained were as follows. The blowing resistance in the sintering bed changes as the sintering reaction proceeds. It increases at the beginning of the reaction when the temperature of the bed is still low. Then it decreases as the reaction continues, accompanied by an increase of the bed temperature. The increase of the blowing resistance in the bed during the sintering process mainly occurred in the drying zone, and was comparatively small in the reaction and cooling zones. Based on Erugen's equation, the change of the permeability during sintering is explained by the decrease of the apparent fractional void volume in the drying zone of the bed.

Jan 1, 2000

By L. Salinas

Lance injection of gas and particles into a molten bath is currently practised in metallurgical processes (Mitsubishi lances for example). Several experimental and theorical studies have been conducted in the past on this topic. However, neither detailed calculations nor experimental studies of local flow patterns have been published. In the present work, a numerical simulation of the interaction of a gaseous vertical descending jet and a liquid surface was done, using the turbulence k-e model. There is a fair agreement between the calculated and the experimental values. The results of this study demonstrate that it is crucial that the gas jet velocity profile and turbulent characteristic are correctly formulated in order to correctly simulate the system.

Jan 1, 1999

By K. Rajani Kanth

Environmental problem is the major concern for any industry and there is a great need to that along green lines. Sangam Dairy being one of the most famous and wide spread Dairies in India, produces wide spectrum of milk products. The BOD levels of effluent water of this industry with MIF treatment were found to be around 100 ppm. Lot of research has been expended in the past to bring down the BOD levels to bare minimum. The main objective of the present study is to minimize the BOD level to the required level stipulated by environmental standards by employing various seeding materials. For this purpose microbes like Bacillus Subtiles, Pseudomonas, Aspergillas, Staphylococcus, and Pencilium have been employed and BOD levels were analyzed. Various Reagents, solutions with different dilution levels have been successfully prepared. Initial and final Dissolved Oxygen levels were determined before and after incubation. From the DO data, BOD was evaluated for all samples and comparison analysis of various seeding material was carried to suggest the efficient seeding material for the ETP plant. In the process, solutions of different dilutions have been prepared using difficult reagents. These samples are treated with above mentioned microbes and BOD levels are estimated. It has been observed that staphylococcus and Pseudomonas proved to be the best seeding materials. When there microbes have employed BOD levels fall to less than 10 and 20 ppm respectively

Jan 1, 2006

By F. Nava-Alonso, O. Alonso-González, A. Uribe-Salas, R. Pérez-Garibay

"Cyanidation is the most used method to recover gold and silver from their ores. In this process, other metals besides gold and silver may sometimes dissolve and interfere with the efficiency of extraction. Copper is one of those metals, reaching concentrations as high as 1000 mg/L in some cyanidation plants, making difficult the extraction and purification processes, and increasing the operating costs.This preliminary work was intended to study the feasibility of using amines to form a precipitate and to eliminate copper from a synthetic solution containing high copper and cyanide concentrations, as is the case of some cyanidation effluents. The solid formed is removed from the solution using conventional filtration techniques. Seven amines were evaluated at different pH values and amine additions. Up to 90% of copper present may be removed at the natural pH of the effluent (alkaline). The remaining copper would permit to recycle the solution back to the cyanidation process. IntroductionCopper is generally considered the most problematic metal in gold leaching due to the rapid formation of copper cyanide complexes when some readily-soluble minerals are processed (e.g., azurite, malaquite, cuprite, chalcocite and bornite). The copper solubilization as cuprous cyanide complexes leads to a significant economic penalty in terms of excessive cyanide consumption and high cost for cyanide elimination. When activated carbon is used to recover gold and silver, the copper-cyanide complexes decrease the efficiency of the process because of the competition of the cuprocyanides with the aurocyanide for the adsorptive sites on the activated carbon (Rees and Deventer, 1999).Several techniques have been developed to attempt to overcome the problems caused by the copper presence in cyanidation solutions, notably: acidification-volatilization-regeneration (AVR), ion exchange-electrolysis or solvent extraction-electrowinning (Lu et al., 2002). In this work the use of some amines is proposed to remove the copper-cyanide complexes by precipitation of a copper-cyanide-amine solid. The process was evaluated for different amine additions and pH values, using copper-cyanide synthetic solutions of composition similar to that presented by some cyanidation plants with high copper."

Jan 1, 2008