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By Gunther Klamp

Disposal of arsenic compounds from washing acid in metallurgical plants is becoming a severe problem when using lime neutralization. A further problem is the disposal of relatively large quantities of gypsum which is produced during this neutralization step and which Is also conta-minated with other toxic metal compounds. The Sachtleben-Lurgi process removes arsenic and other metals from washing acid in the form of insoluble sulphides. The purified acid contains less than 0.5 ppm of arsenic and can be used for standard sulphuric acid applications. The process Is demonstrated commercially at Sachtleben's acid plant since more than five years.

Jan 1, 1992

By Sun Ying, Zhang Jing, Li Qiu-ju, Wang Yan-ze

Copper smelter slag was leached using sulphuric acid solutions under atmospheric conditions. Base on the composition and phase of copper slag, the effect of the concentration of sulfuric acid and leaching temperature to the leaching growth rate of Fe, Cu, Co and Ni in the copper slag were investigated in this paper. Simultaneously, the influence of sulfuric acid concentration, leaching time, leaching temperature and the amount of sulfuric acid (solid-liquid ratio) to the leaching rate of these metal elements were researched. Experimental results showed that: with the increasing temperature, the dissolution rates of the metals elements increased first and then decreased. Due to the influence of silica gel which was obtained in beginning of leaching, the higher the concentration of sulfuric acid is not conducive to dissolution of the valuable metal elements. The dissolution degree of Fe, Cu, Co and Ni were 92.83% 96.76% 93.62% and 63.41% respectively.

Jan 1, 2016

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 Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

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 Dirk Bergmann

During the spray forming process, a continuous molten metal stream is atomized by impinging high speed inert gas jets. In the generated spray cone, the resulting metal droplets are rapidly cooled by the huge temperature difference to the surrounding gas phase and thereby partly solidified during flight. After a certain flight and residence time inside the spray cone, the droplets impinge onto the solid substrate and form the product (deposit) by compaction. Material properties of this preform strongly depend on several process parameters and especially on the thermal and kinetic state of the deposited droplets at the point of impingement. Smaller droplets may cool very fast due to their low mass and impinge onto the product in a completely solidified state as solid metal powder particles. Larger droplets with big mass contain a higher amount of thermal energy and impact during the state of phase change or still as completely liquid. It is obvious, that a certain amount of liquid content in the droplets is needed for forming a homogeneous deposit. Therefore, the thermal history of metal droplets during flight in the spray cone is of great importance for overall process modelling and control. Modelling the effects of the impinging droplet mass on the formation and heat balance of the deposit, the thermal conditions of the droplet stream need to be temporary and spatially averaged at different locations. Averaging may be achieved in different ways, giving alternative results. A first method is averaging over the droplets total enthalpy which consists of the thermal content and the remaining latent heat of fusion within the droplets. A second method may yield the average over the heat content and the solid fraction separately. Results of these two methods depend on the application and the kind of information which one wants to achieve and show some deviations, which will be discussed in terms of consolidation and energy conservation of the deposit.

Jan 1, 1999

By Peter A. Spencer

Bacterial oxidation technology has the ability to selectively attack sulphide minerals. Selectivity allows oxidation of more reactive minerals and the extraction of valuable metals while leaving the bulk of the sulphide component unreacted. Partial oxidation can be used on arsenopyrite to recover gold and for the leaching of base metals, such as copper and nickel, from pyritic ore and concentrate without generation of large quantities of acidic iron solution, which must be neutralized. Thus, rejection of pyrite during the oxidation process can considerably reduce treatment costs. Acid generation in tailings dams would be minimal, compared with most Thiobacillus cultures, as the optimum growth temperature of Bactechts culture is above ambient.

Jan 1, 1992

By Chao Zhang, Kexin Jiao, Yi Qian, Jianliang Zhang

Now low-grade iron ore were widely used. However, one prominent problem is that the content of trace elements is higher than that in high quality iron ore. For the requirement of the content of Mn, Cr, Ni, Cu, and Ti in hot-rolled steel sheet and strip, the upper limits of these elements in sinter will be studied in this paper. Using the activity model of aggregation of electronic phased slag composition, the distribution ratio of each element in converter is analyzed and the content of each element in hot metal is calculated. Furthermore, through the thermodynamics method, the distribution ratio of each element in BF is analyzed and the content of each element in raw material is calculated. The upper limits of Mn, Cr, Ni, Cu, and Ti in sinter can be determined by calculating, the values are as follows: Mn 0.767%; Cr 0.552%; Ni 0.055%; Cu 0.159%; Ti 0.108%.

Jan 1, 2015

By Tatsuki Uzawa, Takashi Nagai

The consumption of Nd and Dy is increasing dramatically because of an exceptionally high demand for Nd-Fe-B-(Dy) magnets and a significant amount of the magnets are wasted. It is important to develop a recycle process the elements from the wasted magnets. In this study, Nd and Dy were extracted from the magnets by silver at high temperature. Nd can be extracted more than 70 % by silver. However, Dy is extracted only 25 % in the same experimental condition.

Jan 1, 2014

By Xu Zhong

The theoretical limit to smelting rate and possibly the size of a smelter is dependent on the rate of heat transfer, and the chemical kinetics of both sulfur removal and minor element volatilization. The fundamental kinetics of volatilization of minor elements such as As, Sb, Bi, and Pb from matte and white metal is being investigated. It has been shown that the molecular form of trace elements in matte depends on the chemical potential of sulfur and the propensity for the minor element to form a sulfide. The impact of the variable molecular form of the minor elements on the volatilization kinetics is unknown and is under investigation in this study. The experimental technique is reviewed and preliminary results are reported in this manuscript.

Jan 1, 1995

By Luis G. S. Sobral, Gabrielle N. Bard

Copper sulphides Concentrates, from the flotation process of copper primary ore; contain, commonly, small amounts of precious metals, such as gold and silver. During the smelting process of those concentrate all gold and silver are practically in the blister copper, which is cast into anodes. Those copper anodes are electrorefined in an electrolytic system, where the electrolyte is an acid copper sulphate solution, where a high purity electrolytic copper is produced (>999,9/1000). The slime when submitted to an oxidative leaching process, using sodium hypochlorite and hydrogen peroxide as oxidizing agents, turn those metals into solution. This research practical work, apart from concentrating effort on the digestion of the anode slime, aims at evaluating the efficiency of the cementation process of the metals of interest for the separation of them to take place. 141

Jan 1, 2008

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By Jeffrey F. Adams

Gypsum fouling is a common problem in the hydrometallurgical industry. It is a particular problem in free sulphuric acid neutralization, or iron removal operations where sulphates are removed from aqueous solutions by the addition of calcium-containing bases. Previous work revealed a strong correlation between the degree of gypsum supersaturation in the reactor and the rate of scale growth indicating that scale formation and growth are primarily controlled by chemical phenomena. However, the chemical behaviour of gypsum is variable and unpredictable with solution chemistry and temperature. Many of the "rules of thumb" that are used to predict its behaviour (and avoid fouling) are in fact based on gypsum solubility in water, rather than on real mixed metal sulphate systems. However, despite this unconventional solubility behaviour, we have been able to accurately model it in Ni, Mg, and Zn containing solutions over a wide range of temperature (25°C-90°C) and solution concentration (0-6 m) using the OLI simulation software. Furthermore, by studying fouling rates in a simulated continuous neutralization reactor, the relationship between process conditions and fouling rates were explained for the first time. This has led to an understanding of how techniques for minimizing gypsum fouling work.

Jan 1, 2003

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified

Jan 1, 2006

By L. Dornelles, M. H. Prediger, R. de C. de S. Schneider, D. A. R. Lopez

In this work it was evaluated the environmental impact of sunflower plantation for biodiesel production. It was considered, for life cycle analysis (LCA) of sunflower in familiar agriculture in the South of Brazil, data collected in 23 experimental farmings with sowing in the period from August to November (2006 -2007). The LCA has considered the plantation conditions, energetic efficiency, man power, diesel volume, type of machines, fertilizers and pesticides used. From the analysis carried through it was evidenced that the sunflower produced in small scale does not need the use of tractors to have an excellent productivity and low impact. Therefore, the sunflower can be cultivated, with the necessary cares, in periods that do not compromise the man power for other cultures and the sunflower is an alternative so that the familiar property can produce biodiesel.

Jan 1, 2008

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 Roberto Javier Santiago

This paper tries to make a study about the use of calcium carbide during the tapping in replacement of part of the aluminum used in the furnace tapping, analyzing theoretical consumptions and then transfering the practice to the plant.

Jan 1, 2006

By He De-wen

The influence of coal desulphurization by fungus was experimentally studied. The present results suggest that fungus can effectively remove inorganic and organic sulfur in coal. The main factors that influence the desulphurization by fungus such as pH value, temperature, coal slurry concentration and coal granularity are studied by orthodox experiment and the optimal experimental conditions are as follows: pH value 6, temperature 45 C, coal slurry concentration 10% and coal granularity 100 m. Under the above conditions, fungus can remove up to 44.96 total sulfur and 54.87 inorganic sulfur within two days and their desulphurization rates will increase along with time. Compared to sulfolobas, desulphurization by fungus is steady and more effective and has the advantage of high speed.

Jan 1, 2006

By David Langberg

Recovery of dissolved copper from discard slags is a critical consideration affecting the economics of copper smelting. Slag cleaning is frequently carried out in electric furnaces, however reduction by injection of natural gas in a holding furnace may offer a lower cost alternative in some circumstances. As the residence time of the injected gas is short, the factors controlling the rate of reduction need to be clarified in order to optimise the design of the slag cleaning furnace. A series of medium scale (200 kg) reduction tests to investigate the rate of reduction of copper-containing slags by injection of natural gas-nitrogen mixtures between 1150-1250C was carried out by CSIRO Minerals. The composition of the gas in the top-space of the reactor was found to be significantly more reducing than the slag, indicating that thermodynamic equilibrium was not established between the slag and the gas in the bubble plume. An apparent first order rate law was observed between the rate of oxygen elimination from the bath and the magnetite concentration of the bath. The dissolved copper concentration was closely correlated with the oxygen potential of the slag, suggesting a partial equilibrium between the dissolved components of the slag. The utilisation efficiency of the natural gas decreased as the natural gas flow rate was increased. The results of the tests tend to indicate that the rate is controlled by a mixed reaction kinetics/ mass transport mechanism. The work was supported by Xstrata Copper ? Mt Isa Mines.

Jan 1, 2006