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The oxidation of zinc vapour plays a very important part in the operation of the Imperial Smelting Process. The kinetics of the reoxidation of zinc vapour by carbon dioxide and water vapour onto quartz and zinc oxide substrates is qualitatively understood and this pertains to the conditions found as the gases are being transferred from the furnace to the splash condenser. However, re-oxidation also occurs in the shaft of the furnace where the solid substrates are sinter and metallurgical coke. It was found that there was a threefold increase in the rate of oxidation on sinter, compared to quartz and a 30 to 300 increase in rate on the coke. This was attributed to the high surface area offered by these materials.

Jan 1, 2003

By Yoshihiko Maeda

"Although Japanese mining industry once had been a polluter of toxic heavy metals and gasses, it has been struggling for improvement of environment at mining and smelting facilities under the strict Japanese regulations. Through these efforts, the industry has developed various environmental technologies to be applied in other industries and society.Recycling of metal scraps, for example, has been conducted at smelting facilities. Treatment of hazardous waste, cleanup of contaminated soil and management of landfill are other examples of application of mining and smelting technologies and facilities. In accordance with the worldwide environmental concerns, the industry has become one of the leading industries to promote ""Sustainable Development"", and it is expected further contribution in reducing various environmental burdens to earth by utilizing its mining and smelting technologies and facilities. Some of the examples of these applications are presented in this paper.IntroductionDowa Mining Co., Ltd., established in 1984, is known as one of the ~op Japanese producer of nonferrous metals. Base on its special expertise in the mining and smelting of complex ores, it has expanded its business areas to downstream activities ranging from highly purified metals and alloys, electronics materials, chemicals and related various businesses. Dowa Mining now is becoming more active in the field of waste treatment and recycling.Dowa Mining had operated some mines until 1980th, located at the western part and northern part of Honshuu Island in Japan; the former is pyrite mine while the later is ""Black Ore"" mine,· a complex sulfide ore composed of high grade of copper,· silver, lead and zinc. However, due to the strong yen began in1985; Dowa Mining closed its mining operation in 1994, and has sifted to mining operations in Mexico."

Jan 1, 2000

By D. H. H. Quon

Results of a study conducted to determine the properties of iron ore pellets made from Mount Wright and Carol Lake ore concentrate fines with partial and full substitution of bentonite by several organic binders are presented. Carboxy methyl celluloses 7H and 6TL, hydroxy ethyl cellulose (natrosol) and modified guar gum all produce pellets of acceptable wet, green and dry strength. However, when fully substituted, an inorganic binder such as calcium carbonate is required for satisfactory strength development after induration. Mixing the Carol Lake ore with Mount Wright ore in a 50-50 ratio also achieves the same result. The failure of the Carol Lake ore in the pelletization process is attributed to the low hematite content of the ore. The results are very similar to those from the extrusion studies reported earlier (8).

Jan 1, 1989

By Gervais Soucy

During mineral and industrial processing, contaminated wastewater can be generated such as cyanide liquors (free species or in complex form). This paper presents the treatment of cyanide solution derived from the aluminum industry, by direct contact of the solution with thermal plasma in a novel reactor. The reacation energy is provided by a plasma submerged in solution which allows direct contact between the plasma and the solution to be treated. The scope of this' study was to determine the feasibility of treating free and complex cyanides in solution through mini-pilot scale operations. An innovative reactor was designed and fabricated to provide stable: process operating conditions. Many parameters were studied. These experiments permitted the evaluation of the kinetics of complex cyanides decomposition under thermal plasma conditions. At atmospheric pressure (temperature about 100°C), the rate of cyanide decomposition by thermal plasma was 12 times greater than that of thermal hydrolysis in a plug flow reactor et the same temperature. The improvements in the decomposition rates are attributed to high thermal gradients at the plasma liquid interface and photocatalysis induced by the plasma UV radiation.

Jan 1, 1998

By Qiang Zhong, Qian Li, Yongbin Yang, Tao Jiang

Thermogravimetric analysis (TGA) has been used to research the pyrolysis and combustion processes of coal used in rotary kiln of iron ore oxide pellet. Furthermore, the effects of air flow and oxygen concentration on the combustion behavior of coal were examined with TGA. The results showed that two individual stages can be distinguished for the pyrolysis of coal, the water evaporation stage and the de-volatilization stage. And the information on ignition and burnout characteristics can be obtained from the combustion process analyzed by TGA. Large air flow almost has no effect to the combustion process except that it enhances combustion intensity. However, the combustion process is further accelerated under oxygen-enriched conditions. With all experimental results, it could provide an attractive approach of analyzing coal for the rotary kiln process.

Jan 1, 2016

By Naiyi Li, Henry Hu, Alfred Yu

"In the past few years, various squeeze cast aluminum components have been developed and successfully implemented in various vehicles by the automotive industry because of their superior engineering performance. However, fundamental understanding of the formation of air gap during squeeze casting processes is still very limited despite of its significant influence on the extent of heat transfer between the casting and mould. In this paper, a mathematical model has been developed to simulate phenomena of air gap between the casting and mold' during squeeze casting of aluminum alloys. The model considers the effect of process parameters such as applied pressures and mold temperatures on the events of air gap formation. The predication indicates that the occurrence of highly enhanced heat transfer in squeeze casting of aluminum alloys primarily results from the presence of excess applied pressures.IntroductionA number of squeeze cast Al components has been developed and used in mass-produced vehicles in the past few years, such as steering knuckles, Road wheel, Engine Block etc. This is attributed to their superior engineering performance. In squeeze casting, the cooling rate can be increased by applying high pressure during solidification which results in the noted refinement in the micro structure scale leading to better casting properties. However, the excessive pressure increased interfacial heat transfer coefficient is affected during the solidification by air gap formation and die surface condition etc., which is believed to increase thermal resistance at the casting/die interface [l - 4]."

Jan 1, 2004

By P. Koskinen

Outokumpu Oy has 30 years' experience in nickel production. It is mainly based on the technology developed within the company. The production chain starts from the mines reaching to the high-grade cathode nickel and the stainless steel manufacturing. As a multi-metal producer Outokumpu has the advantage to exploit from nickel raw materials also other valuable metals and intermediate products which can be processed at the company's various plants. The main source of nickel concentrate is nowadays the Enonkoski Mine started up in early 1986. It is the most modern mine in Finland being provided with the latest Finnish high-tech systems. Nickel concentrates are smelted at the Harjavalta Works using Outokumpu's internationally well-known flash smelting method. Also nickel containing residues and secondaries' are used as raw materials. The high-grade nickel matte from the smelter is then refined at the nickel refinery in a hydrometallurgical process, which was also developed by the company's own research staff. These processes have been continually improved and capacities gradually enlarged to 18 000 mtpy of cathode nickel. Besides plating, melting and superalloying purposes part of the nickel ends in stainless steel at the Tornio Works. The production was started in 1976 and has reached an established position on the European market.

Jan 1, 1988

By J. B. Wiskel, H. Henein

"A study was conducted to establish the effective heat transfer coefficient for a single molten droplet moving in a gaseous medium. Towards this objective, a series of quench experiments were performed on molten droplets of AA6061 aluminum generated with the Impulse Atomization technique (IAP). IAP is a single fluid atomization process capable of producing powders with a predictable mean particle size and a relatively tight standard deviation under controlled atmospheric conditions. Microstructure analysis of the atomized powder was used to establish the extent of pre-quench solidification. A mathematical model was then employed to correlate the Ranz-Marshall and Whitaker equations with the observed particle cooling behaviour. These equations were found to provide a reasonable estimation of the heat transfer conditions only when the variation in gas thermophysical properties across the boundary layer was accounted for in the model. This model formulation of droplet heat transfer has important implications with regards to active sprays and atomization processing operations IntroductionAn understanding of droplet cooling is important in atomization powder production. It is well understood that dendrite arm spacing is inversely proportional to cooling rate during solidificationl1l. Through modification of the heat transfer conditions during metal atomization, the microstructure of a powder maybe tailored to the end user. However, owing to the complexity of gas flow it is difficult to determine a heat transfer coefficient for a moving droplet. This difficulty is further compounded when complex jets and/or streams and their interactions are considered. To provide a base for these more complicated types of analyzes, two approaches have been employed to calculate the effective heat transfer conditions for a single droplet. In one approach, Megardis [ZJ developed a numerical model to investigate the heat transfer process of a free falling droplet undergoing laminar convective cooling. The effective heat transfer coefficient as a function of angular position was determined by numerically solving the fluid and energy equations for the system."

Jan 1, 1999

By Marco Olper

Zinc bearing materials containing chlorides and fluorides of alkali metals, such as EAF dust, Waelz oxides, galvanizing ashes, zinc & brass foundry fumes and converter fumes are little attractive, both technically and economically for processing in ISF plant or in a conventional zinc sulphate electrolysis works. The Ezinexm Process allows for the recovery of high purity zinc in cathode form, from these materials, regenerating the leaching liquor. The process is based on a new electrochemical system which depolarizes the anode reaction with reduction of the cell voltage, compared with the traditional sulphate electrolysis method. The electrolyte, based on a chloroamrnino complex, allows for the recovery of other valued metals present in the zinc bearing materials such as lead, copper and silver, these being recovered as a metallic cement consequently improving the economics of the process.

Jan 1, 1994

By E. Krystad, G. Tranell

"The kinetics of boron removal from liquid silicon during slag refining, as a process step in the production of solar grade silicon, has been investigated by means of small scale mass transfer experimental series at 1600°C, using a graphite crucible. The slags were SiO2-CaO based, with or without addition of approx. 19 wt% MgO. Experiments were carried out at slag-metal ratios of 1 or 2, where the silicon initially contained approx. 250 ppm boron. The metal-slag mass transfer coefficients for boron were found to be in the order of 1-3 · 10-6 m/s and were largely influenced by slag composition. The mass transfer rate was higher for the MgO-containing slag than the slags without MgO. The final equilibrium distribution of boron between metal and slag, LB, was determined to be in the order of 2.3-3.3.I. INTRODUCTIONRecent years have seen a race in industry and research aimed at obtaining a reliable metallurgical route for production of silicon for solar cells (SoG-Si) from metallurgical grade (MG) silicon. Metallurgical routes can successfully challenge the traditional chemical routes for production of SoG-Si if they generate metal of sufficient purity while being less expensive in terms of production cost and energy consumption. Efficient removal of boron is one of the greatest obstacles in the refining of silicon by a metallurgical route, because the segregation coefficient of boron in silicon makes directional solidification unfeasible; in addition, the vapour pressure of boron is not high enough for removal by vacuum refining. However, the thermodynamic properties of boron makes removal from silicon by oxidation possible, and thus the process of slag refining of silicon has been receiving increasing attention as a method for boron removal."

Jan 1, 2012

By Dirk van Zyl

As part of the North American regional activities during the Mining, Minerals and Sustainable Development Project (MMSD) one project focused on the development of sustainability evaluations at the operations level. Engagement was identified as one of the seven important questions to be addressed. Engineers and scientists employed in the mining, minerals and materials production arenas must understand the importance of stakeholder engagement, both within and outside the operations as it is essential in the ongoing activities required to contribute to sustainable development. After developing the awareness that a social license can only be contemplated if engagement is in place, they also have to develop skills in engagement processes. This presentation will present the business case for engagement as well as an approach to motivate undergraduate mining engineers to embrace it. The presentation will also review some recent and ongoing research to improve the engagement process.

Jan 1, 2010

By Hiroyuki. Fukuyama

The pseudo-binary phase diagram of the cuspidine (3CaO2?SiO2?CaF2) - CaF2 system has been studied by electron probe microanalysis (EPMA) and X-ray diffractometry (XRD). To prevent fluorine loss in the form of a HF gas by a reaction of CaF2 with water vapor at elevated temperatures, the equilibrium experiments were conducted with the sample hermetically sealed in a platinum tube. By employing this technique, it was successfully revealed that cuspidine exists as a stable phase and congruently melts at 1684 ± 1 K, and the cuspidine - CaF2 system presents a simple eutectic type of phase diagram, of which eutectic temperature has been estimated to be around 1540 K, corresponding to the composition of 40 mass% 3CaO?2SiO2 - 60 mass% CaF2?

Jan 1, 1999

By A. M. Alfantazi, M. Boissoneault, D. B. Dreisinger, J. Synnott

Acid mist generation is a major concern in zinc, copper and nickel electrowinning industries and there is a strong environmental drive to control its emission into the work environment. Foaming reagents are typically added to the electrolyte to alleviate this problem. In zinc electrowinning, Licorice and Saponin are examples of foaming reagents used for this purpose. In order for the foaming reagent to be effective, its foaming behavior must be determined. In this work, a test procedure was developed to study the foaming characteristics of various surfactants for use as foaming agents to control acid mist in aqueous metal electrowinning. This new test was termed as "mini-flotation test" and it was used to study the foaming behavior of a large number of reagents in an industrial zinc sulfate electrolyte under simulated zinc electrowinning conditions (gas sparging). In addition, the influence of important process parameters such as current density, electrolyte temperature, reagent addition level and sulfuric acid concentration on the foaming characteristics of the electrolyte for each surfactant were investigated. The results of this study have identified the most important factors that influence foam formation, growth and stability. This method could be used as a process control for reagent addition in the cellhouse by generating a calibration curve for the optimum electrolyte conditions.

Jan 1, 1997

By W. K. Choi

Stainless steel exposed to wet environments at ambient temperature is subject to the formation of a surface biofilm. Depending upon the prevailing environmental conditions (dissolved oxygen, pH, Eh, concentration of cationic/anionic species), the biofilm may stimulate corrosion through formation of differential aeration zones and concentration cells. Corrosion significantly impacts the United States economy, since on a yearly basis, corrosion induced losses are estimated to be over $200 billion. A large portion of this corrosion is imputable to bacterial activity, and basic information is needed for a better understanding and control of the biocorrosion phenomenon. The present study has investigated the influence of Thiobacillus ferrooxidans in the corrosion of American Iron and Steel Institute (AISI) 304, 316 and 416 stainless steel samples. The formation of biofilm and microstructural changes on the surface of stainless steel samples and their weldments were assessed by microscopic examination, and the changes in the mechanical properties by stress-strain measurements. The significance of the results will be discussed.

Jan 1, 1993

By J. A. Innes

"""The oxygen, next uniting with the carbon, sent up an ever-increasing stream of sparks and a voluminous white flame. Then followed a succession of mild explosions, throwing molten slags and splashes of metal high up into the air, the apparatus becoming a veritable volcano in a state of active eruption.""IntroductionHenry Bessemer F.R.S(An autobiography, 1905)Thank you Mr Chairman for the opportunity to speak: at this, the opening session of your International Symposium on the subject of ""Injection in Pyrometallurgy"". Judging from the list of papers to be presented over the next three days, the Symposium promises to provide a most valuable addition to our existing knowledge base in what is now an extremely active area of R&D investigations. Whilst we have obviously come a long way since Sir Henry Bessemer's pioneering experiments of the mid-19th century, there is still much for us to learn.Most importantly, the Symposium offers a further opportunity to acknowledge the many significant technical contributions made in this field by the Organising Committee's special guest, Professor Howard Worner - one of this country's most respected research leaders.When first approached to give this talk I had two areas of concern. Firstly, I was not entirely clear just what injection metallurgy was meant to cover. How should the overall scope of this particular subject be defined?My second concern related to Howard Worner himself - a man for whom I have the highest personal regard and who, in fact, played a most influential role in respect of shaping my own career. Having already spoken about Howard's achievements on earlier occasions, I wondered what I could sensibly add.Notwithstanding these personal reservations, I am delighted to be here with you this morning. If my thoughts on the meaning and scope of injection metallurgy appear to be slightly off-course, and if Howard should perhaps recognise some repetition in my remarks, then I hope I can be forgiven."

Jan 1, 1996

By Lijun Liu, Yingwei Li, Jianhua Liu, Jinhui Peng

"As essential equipment in the metallurgical industry, current air heat exchangers cannot meet the requirements of high temperature heat transfer. In this paper, an energy efficient air heat exchanger, based on accumulation of the heat generated by microwave absorbing materials, is presented according to heat transfer theory and principles of the microwave field. A tubular shaped heat exchanger was designed and built up through temperature-rising curve, and experimental research of microwave high-temperature air heat exchangers was carried out. It was found from experiments that the tubular shaped heat exchanger fabricated using material B could be used for high temperature heat transfer system, and equilibrium temperatures could reach up to 457—485?.IntroductionHeating or cooling of air by heat exchangers is commonly practiced in a wide range of industries including construction, chemical, machinery, textile, printing, and dyeing [1-3]. Generally such heating or cooling of air is achieved in pipe heat exchangers. There are several drawbacks for such heat exchangers, namely, (i) the limitation of temperature to which the pipes can be heated, (ii) tendency to oxidize at high temperature, and (iii) poor strength of metallic pipes at high temperature. These limitations do not allow pipe heat exchangers to be operated at high temperatures [4-6].Microwave heating of inert solids, which are stable at high temperature, is a possible solution to achieve high temperature of the medium in air heat exchangers. It is well-known that microwave heating is an efficient, clean, safe, easy-to-control heating method. Microwave heating utilizes the dielectric and magnetic properties of a material. When microwaves penetrate and spread into the dielectric material, electrons, ions, etc move in the internal electromagnetic field, while the elasticity of inertia and friction impede these movements. This results in a significant thermal effect, increasing the surface temperature rapidly [7-8]. This paper studies mainly design and experimental research of microwave high-temperature air heat exchanger."

Jan 1, 2011

By Elizabeth Carvalho L. Cardoso, Ademar B. Lugão, Sandra R. Scagliusi

This research investigated how gamma-radiation affected PP/HMSPP structural foams filled with biodegradable synthetic polyester PLA in terms of thermal properties, biodegradability and infrared spectrum. Polymers are used in various applications providing enormous quantities of wastes in environment and contributing with 20–30% of total volume of solid residues. Besides, shortage of plastics resins obtained from fossil base is addressing research and development toward alternative materials; environmental concerning in litter reduction is being directed to renewable polymers for manufacturing of polymeric foams. Biodegradable polymers, a new generation of polymers produced from various natural resources, environmentally safe and friendly, can contribute for pollution reduction. PLA (poly(lactic) acid)) was chosen to be blended with PP/HMSPP. Blends thereof were subjected to gamma radiation at 50, 100, 150, 200 and 500 kGydoses.Soilburialtestpointedtowardapartialbiodegradationofirradiated PLA-PP/HMSPP foams; other characterizations involved TG/DTG technique and FTIR assessments.

Mar 1, 2017

By Ricardo A. Valls

The Sechol Nickel-Cobalt Laterite Project is located in East-Central Guatemala, 140 km northeast from Guatemala City. In-situ resources in the immediate Sechol area, including those on other mining concessions contain 133 million tonnes of mineralization, grading 1.5 1% nickel. Considering the ever-increasing market for these metals, and the potential quick return on the initial investment, Jaguar Nickel Inc. is confident that by late 2006, it will be producing the first nickeltcobalt hydroxides from Guatemala. The path from now until the production stage passes through a pre-feasibility study, scheduled for completion by mid 2004, and bankable feasibility by mid 2005. Jaguar's objective, however, is not only to have a producing nickel-cobalt mine by late 2006, but also to continue with the exploration work in order to make Guatemala one of the world's leading nickel-cobalt producers. The Sechol group of deposits is conformed of several lateritic pockets, delimited by tectonic faults, and hosted by ultramafic rocks of the Sierra de Santa CW. ophiolitic belt that intruded the Maya Continental Block during the Early Tertiary age. The intrusive is mainly represented by a layered sequence of dunites, peridotites, and pyroxenites, usually strongly serpentinized. Existing data indicate that these rocks underwent fractional crystallization, and probably some degree of magma mixing and contamination previous to their main tectonic event. The most complete profiles are usually present over weathered dunites and serpentinites, while on top of the less altered pyroxenites, there is usually the formation of only a limonitic zone. The relative complexity of the ophiolitic belt explains the variety of mineral resources in the area, which include Ni-Co-Fe laterite, chromite, bauxite, magnesia, and also has the potential for gold, PGMs, and precious and semi-precious stones such as jade, nephrite, and chrysoprase. Metal recovery from the Sechol deposit will be based on an atmospheric chloride process, followed by solution purification, production of an intermediate nickellcobalt hydroxide suitable for sale, and finally acid and magnesia recovery by standard spray roasting technology. The chloride process will allow exploitation of the whole lateritic profile to produce 20,000 Mt of nickel hydroxide and 800 Mt of cobalt hydroxide per year. The exploration work completed to date has concentrated mostly on the Sechol group of deposits, representing less than 5% of the current land position of Jaguar in Guatemala. Within Sechol, the company has identified a large pocket of more than 5 Mt of laterites grading 2.1% nickel and 0.08 % cobalt as a startup pit "El Inicio". Including the work previously completed Keywords: Laterite deposits, Ophiolitic Belts, Central Guatemala, Nickel, Cobalt

Jan 1, 2004

By D. G. Hattingh, A Els-Botes

"Considerable information is available on the factors influencing the iron-zinc reaction rate at 450° C of low carbon steels, in comparison there is a scarcity _of similar fundamental information of spheroidal graphite irons. This can be attributed to the more complex microstructure and ferrous alloy chemical analysis of spheroidal graphite irons. Hot-dip galvanizers have identified the complexity in controlling and predicting the thickness of the galvanized coating formed on commercial cast irons, which has serious financial implications for both the galvanizer and customer.Commercial hot-dip galvanizing has been in use for over 160 years and yet an elementary understanding of the dynamics associated with the hot-dip galvanizing of spheroidal graphite cast iron is still insufficient. To allow the. process to become a modem surface engineering technology, the fundamental aspects of the process must be thoroughly understood.When a clean iron or steel article is dipped into the molten zinc, zinc initially solidifies around the steel or iron. As heat is transferred to the article form the bath, this initial solidified zinc layer remelts and a series of iron-zinc alloy is formed by the reaction of the zinc with the surface of the article; on removal from the bath, some of the molten zinc is taken out on top of the alloy layers. At normal galvanizing temperature (450 °C), the reaction between iron and zinc is usually parabolic with time. The rate of reaction is rapid at first but then slows down and the coating thickness does not increase greatly if the article is immersed in the bath for longer times(1)."

Jan 1, 2000

By D. E. Roberts

Over 425 million used automotive oil filters are discarded in the United States each year. Estimates prior to this research claim that 10% are recycled with the remainder typically being landfillcd. Surveys conducted with ferrous scrap users and oil filter processors as part of this research reveal that at least 15% are currently being recycled as ferrous scrap. Oil filter scrap is not being used by many operations because of concerns with scrap consistency and quality. These concerns stem from trials conducted in the infancy of the oil filter recycling movement. Consistent scrap quality depends both on the content of the used oil filters and the processing technique used to produce the scrap. Technology has advanced since the first recycling trials were conducted by steelmakers. Several different types of scrap are available, including pucks, bricks, cubes, and shred. This research conducted at the University of Missouri-Rolla investigated the content of used oil filters and compares the recyclability of different oil filter sizes and designs. Filters vary by application and vary between manufacturers for a particular application. An understanding of the scrap itself as well as the concerns and problems of both oil filter recyclers and oil filter processors is necessary to increase the number of used oil filters being recycled.

Jan 1, 1996