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By O. G. Yeremin

The Joint Venture "Inter-S" jointly with the Gintsvetmet Institute have developed a technology for manufacturing of sulphoconcrete and sulphoasphalt. The sulphoconcrete manufacturing technology comprises preliminary production of modified sulphur, which is blended in liquid form at a temperature of 120°C with an inert material preheated to the same temperature. The second promising area for the use of sulphur is partial substitution of modified sulphur for more expensive bitumen. The sulphoasphalt manufacturing process comprises preliminary production of a sulphur and bitumen mixture with a sulphur content of 30% to 40%, which is then blended with inert materials using conventional techniques. Sulphoasphalt manufactured at a full-scale plant meets all requirements set to its strength properties for road paving. Technology has been developed for production of high-purity sulphur based on rectification of liquid sulphur in a packed column. A commercial-scale plant with a capacity of up to 15 tonnes per year for production of sulphur with an impurities level of about 110-6 % by mass has been put into operation.

Jan 1, 2006

Iron(II), sulphur dioxide and sugars such as lactose are potential reducing agents for manganese dioxide to produce manganese(II) for subsequent hydrometallurgical treatment. The leaching of limonitic laterite and manganiferrous ores with sulphur dioxide produces iron(II) which in turn can catalyse the leaching of manganese dioxide in acid media. This paper presents a critical analysis of the kinetics of reductive dissolution of synthetic manganese dioxide and manganese ore to compare and contrast the effect of sulphur dioxide and iron(II) in acid media containing sulphate or perchlorate anions. Both one-electron and two-electron mechanisms are considered in the case of sulphur dioxide. The current knowledge on chemical speciation is used to construct an Eh-pH diagram to show the effect of complexation of Mn(II), Fe(II) and Fe(III) with sulphate. Heterogeneous and electrochemical reaction kinetic models are combined to propose reaction mechanisms which rationalize the dissolution kinetics.

Jan 1, 2003

By Ali Akbar Mottahedi

It is known for a long time that the reaction of oxygen with carbon, silicon, iron and many other elements is exothermic. The heat of released from these kind of reactions can decrease the time of fusion of iron and steel for metallurgical purposes in the electrical arc furnaces. By decreasing the time of fusion, we increase the rate of process and the amount of production. So, by blowing oxygen in to the furnace, we can reduce the consumption of electricity and save cost. There are many problems in the procedure of the oxygen blowing. In this project, the theoretical aspect of the oxygen blowing and its side effects into the arc electric furnaces are investigated. An oxygen blowing system into the arc electrical furnace of metallurgy department of Machine Sazi factory was also set up. This process reduced the consumption of electricity up to 22% and increases the rate of production, by reducing tap ? to ? tap time up to 15%. In this project; all oxygen blowing systems and its control were set up.

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 Larry Southwick

In the early 1940's, the Caron ammonia ? ammonia carbonate leach process was used to produce nickel from Mayari ores at the Nicaro plant in Oriente Province, Cuba. While plant operation was generally successful, it was not broadly economical and was shut down. The plant was later restarted in the 1950's and a number of investigations initiated to resolve the more serious operational and performance issues. Processing steps studied included iron reduction (chemistry ? nickel and iron, reductant, equipment), ore variability (homogeneity and consistency of mineral concentrations, serpentine vs. laterite), leach solution strength, nickel recovery (temperature ? reduction and leaching, reoxidation) and a variety of other topics. These studies and their findings will be discussed. Caron himself obtained good results on these ores in the laboratory. They could not be duplicated in the field, the reasons for which will be reviewed. (Note: the ore looked like garden dirt; charcoal made from palm trees was one of the reductants attempted; and ammonia was the leach solution. Mixing the three, so to speak, was to yield nickel.)

Jan 1, 2006

By Bernhard J. Ralph

In refractory gold ores much of the gold occurs in sub-microscopic form in sulfide minerals, most commonly pyrite and arsenopyrite Bacterial leaching is being developed as a pretreatment for these minerals to aid the liberation of gold and a variety of extracting reagents. This paper reviews the nature of the principal micro-organisms involved, the effects of various physico-chemical factors on the rate and extent of extraction, and likely mechanisms involved.

Jan 1, 1989

By N. L. Piret, E. N. Mounsey

Ausmelt technology is successfully used to process primary and secondary materials to produce lead in large-scale commercial operations and to meet stringent environmental standards. The development and commercial data covering these applications and the results with respect to metallurgical, cost and environmental performance are reviewed in commercial operations. A new smelter is scheduled for commissioning in 2000 at Korea Zinc's Onsan site to process lead fume and other secondary materials to produce 50,000 tonnes per annum of lead bullion. The unique features of Ausmelt technology also allow for the efficient processing of polymetallic concentrates and secondary materials, particularly copper and lead, through the effective separation of these elements into metal, slag and fume species. This capability has been successfully demonstrated at a commercial scale and the results and implications for the industry are discussed.

Jan 1, 2000

By Kurt Westerlund

Three years operating experience of the FLUXFLOW waste heat boiler (WHB) 20.000 nm3/0h at Boliden Rönnskär Sweden on a TBRC smelting galena (PbS). Operating experience from the Kivset flash WHB 11.900 nm3/h at Samim, Porto Vesme, Sardinia, Italy. Conceptual features of the 93.600 nm3/h FLUXFLOW (WHB) on the Isasmelt smelting in melt furnace for 180.000 t Cu/a at Mount Isa, Australia.

Jan 1, 1992

By Lætitia H. Delmau

SXFIT is the latest in a series of programs developed in our group to model solvent extraction systems of increasing complexity. SXFIT permits the user complete freedom to define the constituents from which the composition of each phase is to be specified in the data and from which all species of a model for a system are assumed to be formed. Activity coefficients in the nonaqueous and aqueous phases, water activity, apparent molar volumes of aqueous species, and solution density needed for the conversion of concentration from the molarity to the molarity scale are all taken into account by the program. Several extraction systems relevant to nuclear-waste treatment were modeled successfully using this program. As an example, the cesium extraction efficiency of the CSSX process chosen by the USDOE for cesium removal from high-level waste stored at the Savannah River Site can be predicted correctly for varying feed composition.

Jan 1, 2003

By Michael J. Nicol

One of the preferred methods for the recovery of gold from refractory gold ores and concentrates involves pressure oxidation in acidic solutions. The main refractory gold-containing minerals are pyrite and arsenopyrite and there is evidence that the presence of even small amounts of chloride can inhibit the oxidation of these minerals and also substantially reduce the recovery of gold. In this paper, the results of a study of the anodic (oxidation) and cathodic (reduction) behaviour of pyrite electrodes in acidic sulfate solutions containing ferric ions at different chloride concentrations and temperatures up to 200oC and pressures of 2000KPa are presented. The electrochemical studies have been complemented by pressure oxidation experiments on a refractory gold concentrate. Results have shown that, as the chloride concentration increases, the anodic reactivity of pyrite is largely unaffected but the rate of the cathodic reduction of iron(III) decreases. The rate of oxidation of a sulfide concentrate and the recovery of gold by cyanidation of the residues decreases at high concentrations of chloride.

Jan 1, 2003

By Kamal Adham

Hydrochloric acid is used as lixiviant in such hydrometallurgy processes as synthetic rutile production and nickel extraction. The intermediary metal chloride is normally roasted to release gaseous HCl and a solid metal oxide. A large amount of fuel is required for this thermal regeneration, mainly to vaporize the water content of the feed solution. To conserve fuel, some energy recovery from the off-gas is currently achieved, but the fuel costs can further be reduced by process optimization and energy recovery from the gaseous, aqueous and solid products of the regenerator. Here, first the existing limitations to fuel efficiency in the industrial scale HCl regeneration roasters are described. Then, for the case of a dilute feed solution, options for pre-evaporation and fuel minimization are modeled and compared. Finally, energy recovery technologies including heat pumps, acid heat exchangers and solid waste heat boilers are described, and their potentials as the heat source for pre-evaporation of the feed are evaluated.

Jan 1, 2003

By Hiroyuki Matsuura

Treatment of electric arc furnace (EAF) dusts has become an important issue from the viewpoint of the environmental protection and recycling of variable resources because these dusts contain considerable amount of zinc and lead. A new recovery process of these metals has been proposed, in which the metals in the dusts react with waste polyvinyl chloride to form metal chlorides. Therefore, it is important to clarify the physicochemical properties and behaviors of zinc, lead and those chlorides and oxychlorides. In the present study, the kinetics of chlorination of ZnO, PbO and ZnFe2O4 mainly contained in the EAF dusts were investigated at 1023 K to 1273 K with Ar-O2-Cl2 gas. Based on these results, the selective chlorination and evaporation process of zinc and lead from the mixture of Fe2O3-ZnFe2O4-ZnO-PbO was examined and the high efficiency of selectivity has been demonstrated.

Jan 1, 2006

By Alex Mezei

Experimental rheology data are needed to produce design criteria for mass and energy transfer processes. Large throughput plants operate under continuous flow mode. The capital cost is determined by the accuracy of the rheology data used for design. The operating cost is dictated by the energy required to sustain the flowing conditions of various process slurries. Typically, rheology investigations are carried out during the final stages of metallurgical testwork, which is too late to set the design criteria for the pilot plant. This leads to increased testwork cost, and sometimes lowers confidence in the quality of the data produced. In addition, the engineering and feasibility studies are often delayed because of the lack of pertinent rheology data. One of the objectives of this paper is to emphasize the importance of timely planning and execution of the rheology study, which is shown to be a critical component of the overall testwork program. Various applications are discussed, including elaboration of process and equipment design criteria. In this paper, the emphasis is placed on gold and nickel laterite hydrometallurgy applications.

Jan 1, 2003

By J. Tang

The major problem with the Nd-Fe-B magnet is its low operating temperature, i.e., the coercivity decreases so rapidly with increasing temperature that the practical maximum operating temperature-is only 100 °C. Meanwhile, it has been reported that nitrogen addition can drastically increase the Curie temperature of both R2Fe17 and RTiFe11 (R = rare earths). A reasonable question is, then, can one see a similar effect in Nd-Fe-B system? Experiments have been conducted to examine how magnetic properties of Nd-Fe-B magnet are affected by the nitrogen addition. Our results show that part of Nd2Fe14B maintains its original crystal structure and no substantial change in To, due to such N2 treatment is found. However, part of the sample decomposes into a-Fe and, possibly, Nd nitride as a result of nitrogen treatment.

Jan 1, 1992

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 V. L. Stolyarova

The high-temperature Knudsen effusion method was used to study partial pressures of vapour species, activities of components and the Gibbs free energies in the DyF3-Dy2O3 system at the temperature (1357±5) K. Partial pressures of vapour species were obtained by the ion current comparison method, with the DyF3 partial vapour pressure over pure DyF3 as a standard. The equilibrium constant of the gaseous reaction DyF3 + DyOF = Dy2OF4 is evaluated. Thermodynamic data obtained are in a agreement with the available phase diagram of the DyF3-Dy2O3 system. Results of the present study illustrate the negative deviations from the ideal behaviour in the system.

Jan 1, 1997

By Xiaorong Liu

Interfacial emulsion generated in copper solvent extraction is an inhomogeneous O/W emulsion that consists of organic phase, aqueous phase and solid particles. In order to determine what kind of components in organic phase promotes the emulsion, the organic phase separated from the interfacial crud provided by Dexing Copper Mine in Jiangxi, China was analyzed for its components by combined gas chromatography-mass spectroscopy. It was found that many kinds of emphiphiles containing such hydrophilic groups as carbonyl, carboxyl, or acylamine existed in organic phase, most of which were originated from the reagent degradation. Conclusively, Lix984N would degrade gradually during a long-term contact with the acidic aqueous feed and strip reagents. Lix84 and nonylphenol, as effective components of Lix984N, degraded almost completely after long-term recycling. As a result, the effective components of Lix984N were far lower in concentration than the dense-aromatic impurities derived from the diluent and the degradation products in total. The degradation of Lix984N would deteriorate solvent extraction, disengagement performance and result in more serious interfacial emulsion.

Jan 1, 2006

By Larry Southwick

This paper covers technical and other developments during the first 20 years of Peirce-Smith converting. There were numerous mechanical and process ideas and concepts already being developed and used by others that had possible application within the converter that Peirce and Smith were moving ahead with. There were also other converter configurations in which the basic lining and larger size concepts could function. Finally, as awards and honors began to accumulate, there were those who felt that contributions of other early workers were being ignored. The working out of these conflicts and differing directions will be described.

Jan 1, 2009

By J. F. Elliott

The thermodynamic behavior of sulfur and oxygen in copper matte has been measured by equilibration of the melt 00 a gas consisting of CO, SO2 and Ar. The oxygen potential ranges from 10-9 to 10-7 and that for sulfur from 10-4 to 10-2 atm. The work is a continuation of the earlier study by Luraschi and Elliott in our laboratory. A model has been developed that permits extra-polation of the results to ascertain compositions of the matte that are saturated with various oxides of iron.

Jan 1, 1983

By D. P. Briand

Falconbridge Limited operates a smelter in Sudbury, consisting of fluid bed roasters, acid plant, electric furnaces and Peirce-Smith converters, to treat local concentrate and other custom materials. The products are a low iron, nickel- copper-cobalt matte and sulphuric acid. This paper describes the operation and highlights some of the recent efforts to improve human resource effectiveness, to reduce sulphur dioxide emissions and ground level concentration excursions, to develop and expand the custom feed business, to improve productivity and performance in safety and hygiene, and to improve furnace integrity and process control.

Jan 1, 1993