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By Richard H. De Voto

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

Jan 1, 1998

By Tiejun Chun, Marcus Emrich, Jian Pan, Deqing Zhu, Vinicius Mendes

"Joint projects of studies of hematite acid pellet have been implemented to develop technological solutions for using Vale hematite pellet feed in Chinese palletizing plant. Beneficial improvements on the pellets quality were achieved by adjusting the blends composition and using new technology of pre-treating the blended pellet feed with HPGR (High Pressure Grinding Roller) on rotary kiln pellet technology. The drop strength of green balls increased from 3.4 to 6.0 times from 0.5m height, at the same time, the bentonite dosage decreased from 1.5wt% to 0.7wt%. The compressive strength of roasted pellets reaches 2500 N/pellet. The reduction swelling index of roasted pellets is below 15%.IntroductionWith the fast development of steel industry in China, the production of pellets has been further expanded. Pellets are used as a high quality charge for blast furnace and the annual output is around 80Mt pellets [1]. According to the developmental trend, sinter will be replaced by pellets due to the larger environmental impact of sintering plants when compared to pelletizing plants. For example, the specific CO2 emission in sintering process is around 2.5 times higher than in pelletizing process. However, the steel industry of China has been confronted with a serious shortage of domestic pellet feed due to the low iron grade of Run-of-Mine ore despite of huge reserves of iron ores [2]. Therefore, more pellet feed, mainly hematite, has been imported to make pellets."

Jan 1, 2011

By M. M. Coleman

An investigation of the behaviour of sphalerite, chalcopyrite, galena and pyrite during flotation was conducted on selected circuits in the Brunswick Mining and Smelting Corporation Ltd. concentrator in Bathurst, NB. Samples were collected from 59 locations and analyzed for Zn, Pb, Cu, Ag, Fe, As, Sb, Sn, Bi and S. Metal balances were computed using the CAMP Material Balance Program (MATBAL 5) and the metal recoveries for each cell and circuit were calculated. An automated image analyzer interfaced with an electron microprobe was programmed to measure the size of sphalerite, chalcopyrite, galena and pyrite grains in each sample. The percentage of each mineral occurring as free grains and the relative amount of each mineral present in binary and ternary particles was calculated. The recoveries and losses of Pb, Zn and Cu are compared with the amount of liberated and unliberated galena, sphalerite and chalcopyrite present in the concentrates and tailings.

Jan 1, 1989

By Nobuaki Sato, Tetsuo Fukasawa, Akira Kirishima

To apply the fluoride volatility process for the treatment of fuel debris formed in the damaged nuclear reactors, study on the fluorination behavior of main constituents, such as fuel and cladding is essential. The mixture of uranium and zirconium oxides is formed under severe conditions such as high temperature and oxidizing atmospheres. In this paper, fluorination and volatilization behavior of uranium and zirconium oxides have been studied by TG-DTA method in the presence of fluorine. From the TG-DTA result of UO2 in F2 atmosphere, the weight gradually increased up to 7% at 350 oC followed by rapid weight decrease with exothermic peak showing the vaporization of uranium as UF6. ZrO2 showed similar fluorination behavior to that of UO2. However, fluorination of UO2-ZrO2 seemed to be suppressed with increasing ZrO2 amount. This may be caused by the formation of solid solution.

Jan 1, 2016

By Gennadiy M. Poletayev, Mikhail D. Starostenkov, Alexandra S. Starostenkova

"The process of the combustion synthesis was modeled by computer simulation using the molecular dynamics method. The set of the critical parameters regulating the velocity of the reaction was found from these computer experiments. It was established that the character of structure-energetical transformations at the combustion synthesis in the systems Ni-Al and TiAl depended on the type of boundaries used for the phases delimitation in the bimetal thin films.IntroductionProducing new materials and products, based on the combustion synthesis (CS), is the objective of scientific investigations as one of the most perspective one for industrial applications. But there are several problems connected with theory and experiment. It allows us to forecast the properties of materials. First of all, the main problems are stipulated by structure-energetical transformations taking place at high velocities of the reaction and at high temperatures. It prevents the analyzing of the transformation mechanisms in materials, taking place at microscopic, atomic levels in details.It is evident, that computer simulation allows to decide some problems and to approach to more exact theoretical presentation of structure-energetical reactions taking place at CS. It is known, that the most typical systems, where CS is observed, are bimetals Ni-Al and Ti-Al. The investigation of interphase boundary stability in the systems of Ni-Al and Ni-Fe was made by the method of molecular dynamics in [1]. The bimetal thin film was presented by the packing of atoms in the plane (111) of FCC lattice. It was found that the discrepancy in the sizes of atoms A and B of bimetal was compensated by the formation of 60° top dislocations, set against interphase boundary in the absence of point defects and free volume. The density of top dislocations was proportional to the factor of size discrepancy of atomic components of the bimetal. Diffusional reconstruction of the interphase boundary and areas, situated near it, was observed only at definite concentration of point defects - vacancies, inculcated in the structure of the bimetal at the definite temperature. The atoms of the bimetal component of less size penetrated in the area of the second component with higher velocity. The clusters of intermetallic germs began to form. It led to the growth of the system temperature and acceleration of the process of the diffusional reconstruction of thin film. The following transformations were found: top dislocations splitted into single ones, which climbed from interphase boundary into the zone of more plastic component; the formation of sub grain structures took place."

Jan 1, 2001

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 Santo Ranieri

We will briefly review the nickel market in 2003 and look forward to the supply demand balance for the next few years focusing in on the key factors influencing future price dynamics. On the supply side we will examine slated brownfield and greenfield expansions including the Norilsk factor and the small to mid-range 'supply creep'. We will also review the cost side of the industry and what to expect going forward. On the demand side, we will discuss the stainless steel and non-stainless demand, the China factor and the stainless steel scrap supply cycle. We will conclude by pinpinting where the market is on the current price cycle, and where we believe the mid-term direction is headed.

Jan 1, 2004

The 15m high Inco flash furnace uptake was designed as a reaction chamber with the objective of destroying the H2S contained in the furnace off-gas by combustion with oxygen at about 1300°C. Until recently, the oxygen required for this purpose was injected through afterburners located at the bottom of the uptake. An undesirable side effect of this practice was the formation of build up accretions on the inside walls of the uptake. This buildup had a negative impact on both the furnace on line time and the control of the flash smelting process. In late 200 I, the afterburners were relocated to the roof of the uptake. As a result, about 80% of the uptake accretion buildup disappeared with obvious beneficial effects for the operation of the furnace. This paper discusses key flash smelting aspects that affect the operation of the flash furnace uptake such as the dusting rate, the formation of H2S in the freeboard of the furnace, and the impact of using coke to supply some of the heat required by the process. The mechanism of buildup formation and its dependence 'on uptake afterburners location are also examined. Prof. Yazawa's sulfide smelting thermodynamic relationships proved instrumental in understanding the conditions that influence the formation and the elimination of H2S and uptake buildup.

Jan 1, 2003

By R. G. Reddy

The effect of solid particles on viscosity behavior of Na2O-O-B2O3-SiO2 melts of composition XSio2/XNa2o =0.5 and in the temperature range of 900- 1150 K was studied. Samples were analyzed by X-ray diffraction and optical microscopy. The results showed that a crystalline phase (NaBO2) was formed and its amount increases with decrease in X,, from 0.50 to 0.25. The experimental viscosity values were compared with the predicted values using our viscosity model developed earlier. At low temperatures, for low content of B2O3 , the experimental values exhibits a large deviation from the predicted values. It was concluded that the deviation was due to the formation of solid particles in the molten slags. The existence of these solid particles increased the viscosity values significantly. A new viscosity model was developed to include the effect of solid particles.

Jan 1, 1993

By H. P. Wang, E. M. Perry

"Analytical solutions for investigating the solidification of casting problems with initial superheat and natural boundary conditions have been derived using an integral method. There are two moving interfaces in the solution field, one for the phase change line and the other for the superheat line. Two coupled nonlinear differential equations, representing two moving layers, were calculated by the Runge-Kutta numerical integration scheme. The solutions are in terms of six dimensionless parameters: phase change number, two Biot numbers for interfaces, diffusivity ratio, and dimensionless superheat temperature and time. Parametric studies on these parameters have been conducted to provide generic information about this phase change problem. This analytical information is extremely useful for validating numerical solutions. A simplified I-D finite element model was constructed for the purpose of comparison. The excellent agreement between the analytical and finite element solutions has proven that they are mutually validated.This validated finite element modeling tool was then used for modeling an investment casting process of a super-alloy with a simple geometry: a two-step plate. The nonlinear latent heat release, a common property of alloy materials, was approximated by several piecewise linear segments. The transient temperature response of this 2-D finite element solution, including a metal/mold gap resistance, shows excellent agreement with experimental data.This fundamental work provides a solid basis for further work on the development of a process modeling tool for the complex investment casting process.IntroductionAt present, the investment casting process is used in a variety of industries. In the aircraft engine industry, in particular, investment casting is used to produce parts ranging from turbine blades to engine frames. Because a large single casting can replace many component parts that require machining, fabrication, and assembly, this one-piece casting approach becomes a very cost-effective manufacturing process.The main constraint in using this process for mass production is the long design-to-production lead time. The standard rigging design is still an art, based on the experience of casting experts, rather than on scientific methods. Many trials are often required before making a sound final casting. In order to .reduce the number of expensive casting trials, the development of computer-aided tooling technology is needed.The fundamental physics describing this manufacturing process can be simply described. They reduce to a solid/liquid phase change problem, with two parts - first, the thermal balance of the initial superheat temperature of the molten metal and the preheat temperature of the ceramic shell through heat conduction, and second, the energy release from the mold surface to the ambient by radiation."

Jan 1, 1986

By Liu Chunpeng

The new technological process developed is by means of thermal plasma arc smelting to obtain high grade Ni matte directly from Ni-Cu concentrates containing 6-7% nickel and 3-8% sulfur. In comparising with conventional smelting and converting processes the plasma arc smelting process has many advantages over conventional processes, such as lower energy consumption, lower capital investment and free from SO, pollution by transforming the sulfides into elemental sulfur with microwave irradiation under controlled oxygen potential, moreover, the process is simple and easily controlled due to less magnetite troubles in the operation. Therefore, this new technological process can be used as an alternative way to conventional process for Ni-Cu concentrate smelting. The main economical technical index is summarized in Tabal 1. Table 1 Main Ecnomic-technical Index

Jan 1, 1993

By David J. Krichten

A method of retrofitting air-fuel burners with oxy-fuel capability overcomes the potential problems associated with oxygen combustion in aluminum melting furnaces. The retrofit burner uses the existing combustion air connection, burner housing, and burner tile and replaces the gas tube with an oxy-gas burner. Maintaining a portion of the air flow to the burner reduces the potential for localized overheating. Proper design of the burner reduces NOx emissions by moderating the flame temperature with furnace gas recirculation. Economic analysis of using oxygen shows the benefits are increased productivity and reduced overall unit cost of melting. In practice, the melt rate in rotary furnaces increases by up to 50% and by up to 35% in reverberatory furnaces. Oxygen utilization reduces total melting cost by 112-314 cents per pound of aluminum melted.

Jan 1, 1997

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 R. H. Rubisov

Sulphuric acid pressure leaching of nickeliferous laterites has attracted considerable attention from the nickel industry during the past five years. The process is especially advantageous for limonitic laterites that mostly contain goethite, because iron precipitates releasing acid and thus rendering low acid consumption. It is also applicable to mixtures of limonites and saprolites, although at higher acid consumption due to magnesium. Effective process design requires the solubility of metals that precipitate during the process to be known. In the present work, determination of metal solubilities is based on a simple speciation program that assumes the presence of only one dominant complex for each metal. The thermodynamic data for the precipitation reactions are extracted from high-temperature experiments with monometallic systems published previously. The validity of the approach is then tested against mixed bimetallic systems, and finally applied to calculate the solubility of aluminium, iron and magnesium in laterite leaching effluents "at temperature". In both cases of limonitic feed and limoniticfsaprolitic blends, the prediction closely follows metal solubilities measured experimentally at temperatures from 230 to 270°C and at terminal he acidities ranging from 10 to 75 g/L.

Jan 1, 1999

By Kensuke Sassa, Shigeo Asai, Norihisa Waki

"A new method for separating inclusions from a molten metal using a high magnetic field has been proposed. The principle of this method based on the magnetization force has been confirmed in experiments of separating intermetallic compounds imitating inclusions from molten Al-Si-Mn-Fe and Al-Si alloys. In order to measure a magnetic susceptibility, the Gouy's method has been so modified by using a super-conducting magnetic as to work in a high temperature up to 1473K. A theoretical expression for the magnetization force, which is indispensable to evaluate the magnetic susceptibility, has been derived. The magnetization forces acting on intermetallic compounds which were used in the magnetic separation were measured over the range of liquidous to solidous temperatures and the magnetic susceptibilities of the intermetallic compounds were obtained from measured magnetization forces by use of the theoretical expression.I. IntroductionRecent developments in the technology of super-conducting magnets have given rise to the circumstance that a high magnetic field over a relatively large space is readily available without liquid helium. Then, it has been found that a high magnetic field provides magnetic effects to nonmagnetic substances and various interesting phenomena have been reported in the broad science fields of physics, chemistry and biology1). ""A science related to a high magnetic field"" in which many fields are transversally viewed from the standpoint of a high magnetic field2 ) is going to be established. In particular, new phenomena and functions brought by the science related to a high magnetic field are also useful for Material Science and Engineering so that the creation of Materials Science and Engineering related to a high magnetic field"" has been conceived 3).Now, when a substance regardless of being magnetic or nonmagnetic is put in a magnetic field, it feels a magnetization force, which is familiar to such a force that a magnet attracts iron. The force is in proportion to the product of magnetic field strength, its gradient and susceptibility so that a precipitated substance can be separated from a molten metal based on the difference between susceptibilities of a substance and a melt. This is a basic principle of the magnetic separation. So far the application of the magnetic separation has been limited to the separation of ferromagnetic substances from a nonmagnetic medium. A high magnetic field, however, has enabled to separate nonmagnetic substances from a nonmagnetic medium.In this study, a new method to separate inclusions from a molten metal using a high magnetic field has been proposed. The principle of the method was verified by experimental works and the feasibility on the elimination of inclusions in steelmaking processes has been studied"

Jan 1, 2000

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 Jun Li

Rate processes of silver cyanidation were studied with the objective of understanding the reaction mechanism. The research was divided into three sections: anodic dissolution of silver in cyanide solutions, cathodic reduction of oxygen on silver surfaces and the direct leaching of silver in oxygenated cyanide solutions. The charge transfer steps plus the diffusion of reactants from bulk solutions to the silver surface were identified as rate-limiting and the rates of both anodic and cathodic reactions can be calculated using the Butler-Volmer equation and Fick's first law. Based on mixed potential theory and the results of electrochemical studies, a comparison of the rate obtained from direct leaching with that predicted from the calculation is made. Calculated results agree well with the experimental data.

Jan 1, 1992

By Jae-Chun Lee, Jinki Jeong, Manis Kumar Jha, Divika Gupta, Pankaj Kumar Choubey

Rare metal indium (In) is mostly used as electroluminescent material in liquid crystal displays (LCD) monitors. Present paper describes leaching studies for the recovery of In from waste LCD monitors in presence of different other impurities. The leaching studies showed that more than 85% of In was leached out using 20% sulfuric acid at 60oC in mixing time 30 min at fixed pulp density 25 g/L. The solution could be purified using SX/IX and from the pure solution metal/ salt could be produced by evaporation, precipitation, electrolysis, crystallization processes.

Jan 1, 2014

By Y. Waseda, S. V. Gnyloskurenko

"Present paper reviews the various processes for making of metallic foams. These methods are classified in accordance with the state of initial metals - liquid, powdered and ionized. Liquid metal can be foamed by direct inputting of gas into melt, using gas releasing foaming agents or producing supersaturated metal-gas solutions. This group also includes methods creating voids in the melt. Powder route is based on using powdered matrix metal with foamable precursor materials. Finally Deposition techniques allows making highly porous metallic structures using ionized metal.Experimental study presented shows importance of wettability in bubble formation at gas blowing into melt simulation liquid (water) through holes. Good wettability of injection holes by water ensures formation of bubbles with smaller sizes that effect to the final foam structure.IntroductionOne of the objectives of future production technology is to make of lightweight constructional materials while achieving improved property and good economy as well.The most perspective lightweight materials are cellular or foamed materials that are Wide8pread. in nature and have a growing interest in industry and everyday life.Even metals and metallic alloys can be produced as cellular solids or metal foams beside of the traditional engineering materials such as polymers, ceramics or glass. Recent developments in metal foams, especially aluminium, have produced a new class of lightweight materials."

Jan 1, 2000

By Robert D. Pehlke

"The evolution of oxygen steelmaking is reviewed and new operating processes are described. The developments which could impact this technology are summarized. Staged and continuous steelmaking are considered in the light of new technologies. The future opportunities for oxygen steelmaking processes are overviewed. IntroductionThe use of oxygen in steelmaking was originally brought on the scene by the development of pneumatic steelmaking. Sir Henry Bessemer in England originally conceptualized the use of gaseous oxygen in steelmaking, and then he and William Kelly in Eddyville, Kentucky independently developed the original pneumatic process which involved blowing air through a bath of molten pig iron to oxidize the carbon and silicon and produce steel. This process and many following processes, including those which would use pure oxygen gas, have been proposed.Beginning with the first commercial oxygen steelmaking vessels at Linz, Austria in 1952, the world steelmaking industry has adopted this style of processing. In general, the process has involved the use of steel scrap in amounts from 20 to 35% of the metallic charge with molten pig iron produced in blast furnaces making up the remainder. The impurities in the charge are oxidized through the use of oxygen gas injected into the steelmaking vessel.However, currently being adopted into commerical practice and on the horizon are a number of advances in this process which include the use of iron ores as a source of iron and oxygen, the use of an all scrap charge, incorporation of pre-reduced iron, the use of auxillary fuels to change the balance of cold and liquid iron-base charge materials and numerous refining techniques."

Jan 1, 1988