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By Zhang Hengzhong

Ni-P-Fe slag is the by-product in the production of phosphate fertilizer in blast furnace with nickel contained serpentine ore as the raw material. It contains nearly 5-7% Ni, 65-7( Fe, and 10-12% P. The slag is very hard to process, it neither dissolves in aqueous ammonia, nor in sulphate acid. In the stiff the technique to treat the slag in order to extract valuable nickel was developed, it essentially consisted of the processes of roasting, leaching, separation and purification. Nickel sulphate was prepared with this method.

Jan 1, 1993

By José C. Escobedo B.

A kinetic study of nitrogen dissolution in a. electromagnetically stirred Co-Cr-Mo alloy bath was made. The experiments were carried out at 1693, 1723 and 1743K of temperature, with a nitrogen pressure of 0.67 atm. The mass transfer coefficients were obtained, finding that their values increase as temperature grows. The true kinetic constants were calculated. It was found that at 1693K of temperature, the kinetics of the nitrogen dissolution process is controlled by a mixed mechanism involving both transport processes and chemical reaction, while at 1723 and 1743K of temperature, the kinetics is controlled only by transport processes mechanisms.

Jan 1, 1995

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 Takeshi Yoshikawa

For the sake of effective control of titanium-compound inclusions in the steel-making processes, especially for stainless steel production, the influences of alloying elements of chromium, nickel, manganese, molybdenum, copper and oxygen on the thermodynamic property of titanium in molten iron were investigated at 1873K. At a certain titanium potential controlled by the coexistence of Ti3O5 and Ti2O3 doubly saturation of steels, the interaction parameters between alloying elements and titanium in molten iron were determined as follows. [ ] From the investigations on the equilibrium of titanium deoxidation in molten iron, the activity coefficient of titanium and the first order interaction parameter between oxygen and titanium were determined as follows. [ ] Also, deoxidation equilibrium for titanium in molten 304 stainless steel was measured and compared with the calculated results using the determined interaction parameters.

Jan 1, 2006

By J. A. Voigt

In an effort to determine the optimum conditions for preparing high purity, fine particle size high temperature superconducting oxide powder, we have investigated how calcination conditions influence the conversion of a chemically prepared hydroxycarbonate precursor powder to YBa2Cu307. We find that the precursor can be converted to phase pure YBa2Cu307 in either oxygen or synthetic air (20% 02. 80% N2) at 850°C. This temperature is substantially lower than the temperature (>900°C) normally used for the calcination of mixed-oxide powders. The lower calcination temperature prevents particle sintering and maintains the desired fine particle size. Powder processed in synthetic air shows a low degree of crystallinity indicating it may be more sinterable than the highly crystalline powders produced when an oxygen atmosphere is used. Intimate contact between powder particle surfaces and a flowing gas atmosphere promotes the reaction between the BaCO3 component of the precursor powder and the Y and Cu constituents.

Jan 1, 1989

By F. Guevara

The paper presents results of physical and turbulent three-dimensional numerical simulation of the gas flow in the wind box and reaction shaft of the concentrate burner of a flash furnace. Physical simulation work was carried out in a 1:5 linear scale model, where the velocity field was measured using a Pitot tube. The mathematical model consists of the three-dimensional averaged Navier-Stokes equations, turbulent kinetic energy and dissipation of turbulent kinetic energy using the Renormalization Group (RNG) theory for the k-e turbulence model. Computations were performed using FLUENT, based in a finite- volume code. The geometry of the concentrate burner was separated in two sections: wind box and reaction tower. Results obtained at the exit of the wind box were used as boundary conditions for the reaction shaft. The effect of boundary conditions on the numerical results was also studied. Results of physical and numerical simulations show an asymmetry of the velocity field at the exit of wind box. This asymmetry is possibly due to existence of a separated flow in the back of the exit ring. The agreement of physical and numerical results assess the capacity of the turbulence RNG k-e model to reproduce correctly the behaviour of the velocity field at the exit of the concentrate burner.

Jan 1, 1999

By P. R. Seidl, R. C. C. Ribeiro, J. C. G. Correia

"More than 95% of asphalt pavement materials consist of aggregates. The highway and construction industries consume a huge amount of aggregates annually causing considerable energy and environmental losses. The aggregates are usually produced from neighborhood aggregate quarries or form natural aggregate sources. The use of marble and granite wastes from quarries as aggregates might help meet the increasing demands and slow down any detrimental effects on the environment. Chemical and physical results showed that the use of marble and granite wastes from quarries in the asphalt production is quite fusible. Consequently, granite sawmills would perform a clean technology. This technology would also have an economical impact by not spending on basalt extraction.IntroductionThe granite fines generated from sawmills of ornamental rocks comes as a great problem and it lacks undeletable solutions. This problem involves the preservation of the environmental and constitutes one of the subjects more critical the point of view of social beneficiation of the population. The Cachoeiro de Itapemirim County, Espírito Santo State, Brazil is an example, of this problem. In this area, the granite and marble fines generation is around 15.000 ton/year.The problems generated by these residues affect with more emphasis the animals, such as the cattle, which inhaled the water content fines of granite and this residue accumulate in their lungs. Other great problem observed is the sanded of the river and the reduction of aquatic life.This problem is beginning to be set out due to performance of Center of Mineral Technology (CETEM), and of several other organisms of Rio de Janeiro State, aiding the sawmills owner’s. This help consists of teaching the best procedure of discard the residues and studies for its use, for instance the production of mortars, tiles, bricks and road pavements [1]."

Jan 1, 2008

Environmental and public concerns and the banned use of cyanide for the recovery of gold in some parts of the world have heightened the search for an alternative lixiviant to cyanide. Thiosulfate appears to be the most promising alternative to cyanide due to thiosulfate being non-toxic, relatively cheap compared to cyanide and generally gold recoveries are similar to those of cyanide. The most widely researched thiosulfate process is one where copper ions and ammonia are added to the solution. This paper reviews the leaching of gold in thiosulfate solutions and the contributions of the research at Monash University to the understanding of the gold oxidation reaction in thiosulfate solutions, the solution chemistry when copper ions, ammonia and oxygen are present, the influence of the changing solution chemistry on the gold leach kinetics, and the application of thiosulfate in the leaching of gold from ores. It is clearly shown that the gold oxidation rate is hindered in thiosulfate solutions. In the presence of copper ions the gold oxidation rate though is significantly enhanced and thus is why copper(II) is more effective than other oxidants in the thiosulfate leach system. The copper-ammonia-thiosulfate leach solution chemistry is shown to be very complex, especially in the presence of oxygen as the rate of thiosulfate oxidation increases and the majority of the copper ions are not maintained in the copper(II) oxidation state. The thiosulfate oxidation rate must also be maintained low as an intermediate thiosulfate oxidation product hinders gold leaching. In optimising the recovery of gold from ores with copper-ammonia-thiosulfate leach solutions it is important to evaluate and minimise any negative effect an ore may have on the leach solution chemistry and hence gold leaching.

Jan 1, 2003

By Chu Yong Cheng

Synergists can be used in solvent extraction to improve the selectivity of extractants for metals. Research work carried out by the SX group at the AJ Parker Cooperative Research Centre for Hydrometallurgy / CSIRO Minerals has shown that the pH isotherm of nickel with Versatic 10 was significantly lowered by the addition of the synergist Acorga CLX50. The paper discusses how this synergistic shift can be used to alleviate a gypsum formation problem at Bulong nickel laterite operation in Western Australia. Metal pH isotherms were obtained with Versatic 10 and synergist CLX50 using synthetic leach solutions. In terms of pH50, the extraction order of the metals with 0.5 M Versatic 10 alone was Cu > Zn > Ni > Co > Mn > Ca > Mg, whilst the extraction order with Versatic 10 and 20% by volume CLX50 was Cu > Ni Zn > Co > Mn > Ca > Mg with the pH50 (Mn-Co) significantlyincreased. This is significant because the isotherms of valuable metals Ni, Cu, Co and Zn shift more towards low pH than those of the waste metals Mn, Mg and Ca, resulting in a possible good separation of Ni, Cu, Co and Zn from Mn, Mg and Ca. The use of intermediate precipitation, solids/liquid separation and re-leach in the three Western Australian nickel plants make these processes complicated and costly in capital and operation. The research work carried by the SX groupat the AJ Parker Centre has led to the development of direct SX (DSX) processes to recover nickel and cobalt from leach solutions using synergistic organic systems. Semi-continuous tests with a BHP Billiton pilot plant leach solution showed that Ni and Co together with Zn and Cu were separated from the major impurities, Mn, Mg, Ca, and Cl, in the first SX circuit. The co-extracted impurities were easily scrubbed. After stripping, Ni and Co together with Zn and Cu were concentrated, resulting in a much smaller second SX circuit in the down stream processes.

Jan 1, 2003

By Z. S. Wronski

In rapidly solidified Fe-Nd-B permanent magnet alloys, the content and distribution of Nd-rich intermetallic and Fe-phases determine coercivity Hc and remanence Br. Consequently, microstructure plays a crucial role in deter- mining the (BH) max-product of permanent magnets fabricated from these alloys. A study has been initiated to investigate changes in microstructure and the effects on magnetic properties as the material is processed from arc-melted ingot to melt-spun flakes and finally to a product consolidated by hot-forming. Anisotropic magnetization behaviour has been observed in rapidly solidified flakes after low-temperature annealing.

Jan 1, 1989

By V. A. Shumsky, I. P. Polyakov, N. M. Ospanov, M. A. Lyamina, N. N. Ushakov

Studies on the kinetics of the competitive processes of PbS volatilization and PbS oxidation, as applied to the heat and mass transfer conditions in the flame of the Kivcet furnace, revealed that the rate-determining factor is the supply of heat. Therefore, low yields of fume in the autogenous flash smelting of lead sulphide feeds are noted despite the high volatility of PbS at 1,300-1,400°C. Dust formation in the autogenous flash smelting of Kivcet-smelters does not exceed 5-7%, of which fumes amount to ~ 80%. Using extra fuel during autogenous smelting involves the mismatch of the sulphide oxidation rate and the release of heat in the flame, and increases the fume yield. This is a major cause of the high dust formation in pilot plant trials. The analysis of dust formation in the Kivcet smelting of oxidized lead feeds in an industrialscale smelter shows an overall increase of dust formation (up to 10% of the feed), with fumes constituting ~ 80% of the dust. A pronounced increase of the zinc component of the fumes is also noted. Lead

Jan 1, 2000

By Sharon K. Young

What might an ideal leach-to-cathode/product system look like in the next century? The paper looks at the synergies of the 60's and 70's that led to the highly effective copper leach SX-EW system of the 90's. Standing in the year 2020 focuses on what breakthrough technologies might make possible a next generation leach/extraction/metal recovery system. Many of the pieces of such a technology have been developed, even piloted: in situ leaching, enhanced bioleaching, heap leaching of fine particles, resin in pulp, ion exchange, alternate anode reaction electrowinning, novel anode coatings. With nearly non-existent research on the part of individual large companies, the greatest challenge may not be inventing the technologies but rather inventing an industry "will to create."

Jan 1, 1999

By Leszek Blacha

Since several years aog there is noted an increasing importance of the metallurgical vacuum technologies. This refers mainly to the extra furnace steel treatment processes, melting of steel and special alloys in the induction and arc vacuum furnaces, as well as refining processes of nonferrous metals. In the presented work, there is discussed a phenomenon of evaporation of volatile components of metal bath under reduced pressure with description of kinetics of this process. In this article are presented are the evaluation of the mass transfer coefficients in the melt and gaseous phase. Based on results of our own research on removal rate of impurities from liquid copper (bismuth, lead) in vacuum refining process, it is determined the thickness of hypothetical boundary layer in the gas phase. This allowed to formulate a general kinetic equation defining the evaporation rate of gaseous components from metal bath. The values of mass transfer coefficients determined from this equation were compared with experimental results by other authors working on the evaporation effect of melt components of metal alloys.

Jan 1, 2006

By John A. Gisby

Phase equilibria for multi-component systems can be calculated reliably from critically assessed thermodynamic data for sub-systems using software packages like MTDATA, developed by the National Physical Laboratory, UK (NPL). Models and data resulting from an ongoing Mineral Industry Research Organisation (MIRO) project make such calculations possible for the complex systems encountered during sulphide smelting, involving interactions between matte, slag, metal, and gas phases. Predictive calculations can be made that are directly relevant to industrial processes, covering composition and temperature ranges beyond the scope of hard- copy phase diagram compilations, allowing the feasibility of more economic and environmentally sound routes to be explored, better choice of materials to be made, and pilot plant studies to ,be directed more efficiently. Current applications include the selection of suitable fluxing practices in copper and nickel smelting, analysing the operation of the Kennecott copper smelter, optimising the recovery of precious metals and investigating refractory wear.

Jan 1, 2002

By Steven Wright

BHP Billiton?s Olympic Dam copper flash smelter employs the direct to blister process for smelting high grade copper concentrates. SO2 evolution during tapping gives rise to safety concerns. A thermodynamic model for the blister copper (Cu-Fe-S-O) was used to predict the volumes of SO2 evolved. The Multiple Phase Equilibria Model (MPE) was used to evaluate the slag chemistry inside the furnace. The blister copper model was used to explore the relationship between %S and %O in the copper and the amount of SO2 evolved on cooling. The volume of SO2 evolved was sensitive to the O content with reduction to levels below 0.2 ? 0.15% likely to suppress SO2evolution on cooling. Concentrations of S and O in copper samples from trials generally lay above the equilibrium line calculated for an average temperature of 1275C and a partial pressure of SO2 of 1 atm. Consequently there is a thermodynamic driving force for SO2evolution when cooling to this temperature during tapping. A number of potential process options to suppress SO2 evolution on tapping were investigated thermodynamically. Some of the options require treatment of the blister in a forehearth or separate furnace, while others impact on current practises in the flash furnace with slag present. The opportunities that these options present are discussed.

Jan 1, 2006

By Liping Li

A comprehensive three-dimensional two-phase mathematical model was developed to represent a channel type reactor with intense bottom gas agitation. Tracer dispersion and particle tracing methods were used to conduct the analysis based on the solution of the Navier-Stokes equations. Different operational parameters, such is gas volume flow rate. bubbler separation aspect ratios and liquid Input flow rates, were investigated for the purpose of reactor optimization. The numerical calculations were compared with experimental results obtained at the University of Missouri and a good general agreement was observed. Relatively low longitudinal mixing was observed characterizing the system as a "plug-flow" type reactor, in contrast to the intense vertical mixing, under the conditions investigated. Some general mixing characteristics are also discussed In connection to the behavior of other metallurgical reactors.

Jan 1, 1996

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 S. Kurama

Incorporation of de-watering sieve waste of borax (TSW) from Etibor Kirka Borax Company (Turkey) on the mechanical and physical properties of a commercial floor tile composition was investigated. In order to achieve this aim, TSW was partially employed in place of feldspar in the standard composition up to 20 wt %. The formulated compositions were wet milled, dried, shaped and then fired at 1190C for a total firing time of 38 minutes (from cold to cold) under industrial conditions. It was found that using of TSW up to 15 wt % improved the physical and mechanical properties of final product. The results indicated a good prospect for TSW as a co-flux in floor tile formulations.

Jan 1, 2006

By Andrew A. Fyfe

The start-up and operating results obtained at Zia Technology Inc.'s first commercial operating facility at Caldwell, Texas are described. The operation which stated in early 1991 is the first to employ the patented Inclined Rotary Reduction System (IRRS') with the associated 'all-metallic retort for the recovery of all metallics contained in EAF dust.

Jan 1, 1992

By Raymond PoIick

The Demag Electric Slag Cleaning Furnace installed at the Asarco Smelter in Hayden Arizona is one of the few rectangular electric furnaces now operating. The long transition times from charge to tap allow exceptionally clean skims (high recovery); however, the furnace design is complex. Additional Asarco requirements for rapid installation and commissioning further complicated the design. When operating and wear effects accumulated after two years of use, steps were taken to rebuild the furnace with enhanced durability based on the design parameters experience in actual use.

Jan 1, 1993