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By Minna Rämä

Iron containing leach residues like jarosite and goethite from electrolytic zinc production contain many valuable metals and harmful substances. These metals and substances should be removed in order to obtain an acceptable, stable and reusable product, and maximize economic feasibility as well as minimize environmental footprint. In this work, the processing of jarosite leach residue was studied in laboratory scale experiments under oxidizing and reducing conditions at high temperatures. First, the pretreated material was melted and oxidized to produce a melt of metal oxides. Second, the oxide melt was reduced in CO–CO2 atmosphere. Target after the reduction step was to obtain a clean slag and a liquid metal or speiss phase that collects the valuable metals, such as silver. The kinetics of the thermal processing were studied for determining optimal times and conditions for the aforementioned process steps. The preliminary results show that the process is thermodynamically feasible, and the desired phases can be obtained in the experimental conditions investigated.

By Christoph Zschiesche

Managing complex material streams within a lead smelting/reduction process has a long history at Aurubis. After modernization of the secondary lead smelter in 1991, Aurubis operates an electric furnace and a Peirce Smith converter to process complex secondary materials. This process links the copper and the lead metallurgy allowing Aurubis to properly combine primary and secondary process lines to optimize the processing of complex raw materials and smelter intermediates. However, combination of copper and lead metallurgy processing requires a continuous evaluation as raw material quality and composition varies. This paper describes Aurubis lead smelter processing and provides some fundamental considerations to optimize the lead processing, in particular with aspects related to speiss formation

By Qingguo Xue, Jingsong Wang, Siyang Long, Jun Zhao, Haibin Zuo

In order to effectively use of low rank coal, the thermally dissolve coal (TDC) was extracted from four kinds of low-rank coals by N-2-methyl-2-purrolidinone (NMP) at high temperature and high pressure. The structures of thermally dissolve coal and residues were characterized by element analysis, FT-IR spectra. The effects of temperatures, coal rank, solid-liquid ratio and extraction time on the extraction yields of TDC were studied, respectively. Moreover, the extraction mechanism of TDC at mild conditions is proposed. The results show that the ash contents of TDCs from four raw coals are significantly lower than that of raw coals, and the volatile contents and H/C are significantly improved. For KL coal, with the increase of temperature, the extraction yield of KL-TDC is improved evidently from 33.75% to 56.25% and the ash content is decreased from 0.57% to 0.49% at 350 °C.

Mar 1, 2018

By H. Ikeda

The new Onahama N0.3 tankhouse was put into operation early in 1973. This new tankhouse, which has a capacity of 90,000 metric ton cathode per year, is distinct in many important respects from conventional tankhouses. The major objectives in design were to simplify the construction and ope- ration for reduction of the costs for labor, interest and depreciation and also to reduce the copper inventory in the tankhouse by the use of conti- nuously-cast anodes. As a result, the investment cost was decreased by approximately 30% and the inventory cost by approximately 600, while the production per unit area of the tankhouse was increased by 80 - 100% as compared with the existing conventional-type tankhouses at Onahama. By abolition of cell inspection and maximum mechanization of materials handling the labor cost was decreased by as much as 80%. On the other hand, the new system has some disadvantages, such as increase in anode scrap ratio and increased cost of anode casting. The No.3 tankhouse system is, however, still at its starting point, while conventional methods have been continuously improved over the past years of operation. It is expected that the innovational ideas behind this system will serve as bases for a more efficient electrolytic refining system in future.

Jan 1, 1976

By J. A. Eisele

There is currently much interest in how extraction of gold and silver from ores with acidic thiourea solution compares with extraction using alkaline cyanide solution. Agitation leaching tests were performed by the Bureau of Mines on 14 precious metal ores using sodium cyanide (?NaCN) and thiourea [(NH2)2CS) as extractants. The objective was to compare the results of the two extractants. NaCN was used at a concentration of 2 g/L with and without H202 as an oxidant. (NH2)2CS was used at concentrations of 2 and 20 gjL, and the solution potential was controlled at 390 to 420 mV standard hydrogen electrode (Eh) with Fe2(S04)3. With both reagents a.t 2 g/L extractant levels, NaCN extracted more gold and silver than (NH2liCS from all of the ores. At 20 g/L (NH2)2CS compared with 2 g/L NaCN, (NH2)2CS extracted more gold than NaCN from two ores, the same amount from one ore, and more silver from one ore. NaCN extracted more gold than (NH2 )2CS from 10 ores and more silver from 4 ores.

Jan 1, 1989

By Pengfu Tan

A thermo-chemical model of the copper P-S converter and a viscosity model for the converter slag have been developed to predict the behavior of magnetite in the converter slag, amounts of slag and matte, compositions of slag and matte, volume of the bath, bath temperature, slag blow endpoint determination, SEMTECH OPC signals, and the viscosity of converter slags. The predictions of bath temperature, slag and matte compositions, and magnetite content in the slag have been validated by the industrial data. The effects of fluxing strategy, returns and skim charges, oxygen enrichment, and temperature on the magnetite formation in the slag have been predicted and discussed. The effect of oxygen potential, SiO2/Fe in slag, detection of slag blow endpoint, and temperature on Fe3O4 content in converter slag, slag viscosity, liquidus temperature of converter slag and skimming operation has been modeled and discussed as well. Some applications of the industrial operations have been presented.

Jan 1, 2009

By Dachun Liu, Wenlong Jiang, Guozheng Zha, Liang Hu

In this paper, a novel technique for recovery of gallium and arsenic by thermal decomposition under vacuum is presented. The effects of distillation tem- perature on the volatilization behavior of each component were investigated. Theoretical calculations and experimental studies have shown that the method is feasible. The results show that under optimum conditions, highly pure Ga can be extractedwithadvantagesoverconventionaltechniques,includingsimpleoperation andenvironmentalfriendliness.Forexample,metallicgallium(purity > 99.99%)is obtained at 1273 K after 3 h under 3–8 Pa. Arsenic is obtained in the form of a elementary substance which could be preserved with relative ease. (cid:1) (cid:1)

Mar 1, 2018

By Z. Jing, C. Jun

High-purity Bi2O3 was prepared via extraction-preparation stripping method use BiCl3 leaching solution. Parameters such as oxalic acid concentration, phase ration, aging duration, feeding duration, were examined for their effect on the size and morphology of precipitate. The precipitate was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis, differential scanning calorimetry and thermal gravity analysis (DSC-TGA) and infrared spectroscopy analysis (FT-IR). Bi2O3 was characterized by elements analysis, particle size analysis and scanning electron microscopy (SEM). Bi2O3 product of 680 nm was obtained using 15 g/L oxalic acid, 1/1 phase ration, 0 min aging duration, 0 min feeding duration and calcinating at 500 °C for 2 h.

Mar 1, 2018

By Bin Xu, Qian Li, Xishan Li, Yongbin Yang, Hongwei Li, Tao Jiang, Yan Zhang

The cyanide leaching rate of gold from a multi-refractory gold concentrate (18.05 g/t Au) containing 1.62% As, 20.76% S, 6.95% C and 1.31% Sb was only 1.33%. The enhancement of gold leaching was studied mainly by the pretreatment of oxidative roasting and alkaline sulfide washing. Results showed that after the two-stage roasting (i.e., I stage of 500 °C, 1 h and II stage of 700 °C, 2 h) most of sulfur (93.84%) and carbon (98.27%) were removed, but the gold leaching rate of calcine just reached 71.33% because the residual arsenic (0.63%) and antimony (1.15%) were still high. After alkaline sulfide (i.e., NaOH and Na2S) washing, the residual arsenic and antimony was further decreased to 0.21 and 0.65%, respectively. The gold leaching rate of the treated calcine by cyanidation could increase to 93.52% substantially. Also, the optimized particle size, NaCN concentration and leaching time were −0.045 mm over 85%, 0.1% and 36 h, respectively.

Mar 1, 2017

By M. J. Adam

The Bureau of Mines is investigating the feasibility of partitioning complex sulfide minerals to simpler sulfide phases by sulfidation reactions. Such partitioning can afford opportunity to improve selective extraction of mineral constituents of value. This report describes research involving sulfidation partitioning of byproduct chalcopyrite concentrates from Missouri lead ore processing, and a Utah chalcopyrite concentrate from Cu ore processing. Small chalcopyrite samples were sulfidized with elemental S in glass capsules sealed after evacuating and backfilling with He, by heating for 1 to 24 h at specific temperatures in the range of 250? to 500? C, extending from below to above the boiling point of S (-4450 C).

Jan 1, 1987

By Corby G. Anderson

Hydrometallurgical technology for the pretreatment of refractory gold concentrates has been developed at Sunshine Mining and Refining Company. It employs a patented nitrous-sulfuric acid pressure leaching process which' was proven industrially at the Sunshine refinery. Additionally, pretreatment for removal of antimony and some other impurities is done with alkaline sulfide leaching. This paper will discuss the successful application of these two technologies for pretreatment of a refractory gold concentrate prior to CIL gold recovery. A complex gold concentrate composed of pyrite, arsenopyrite and stibnite was tested. Results of antimony leaching in alkaline sulfide media will be discussed including some details of a novel and selective recovery method for gold leached by polysulfide or thiosulfate" Also, the factors important in and the results of the application of nitrogen species catalyzed pressure leaching to refractory gold concentrates will be detailed.

Jan 1, 1996

By John W. Ahlrichs

Microscope, electron microprobe and x-ray diffraction have been used to provide quantitative evaluation of products from the mill, smelter, refinery and other metallurgical processes. Phase compositions and their quantities are necessary for an adequate understanding of the various products obtained throughout an operation and in laboratory testing. By careful evaluation, important information can be gained in improving recoveries and increasing grades at various stages of processing. Four case histories are discussed in this paper. Quantitative microscopic counting techniques are applied to mill products to determine degrees of locking and liberation of the economic minerals. Rapid, but accurate evaluation aids the metallurgist to develop or improve the grinding and flotation circuits. In the smelter, the identification and quantification of the phases are important for predicting reaction mechanisms and kinetic trends. Mineralogic techniques have been applied to conventional smelter products, and to those obtained in laboratory tests for newly developed innovations to smelting. Small, but important, values of gold occurrences in ore are difficult to determine. Evaluation of gold usually requires special separations into various mineral concentrates, followed by assays and mineralogic determinations of the products. Numerous occurrences of solid solution constituents can be treated as by-products, but often they are deleterious to metallurgical treatment. Most solid solution problems can be unraveled by the mineralogist's tools.

Jan 1, 1981

By Ruiling DU, Jiazhi Zhang, Yong Zhao, Keng Wu

Reaction kinetics of metallurgical physical chemistry which was successfully applied in metallurgy (as ferrous metallurgy, non-ferrous metallurgy) became an important theoretical foundation for subject system of traditional metallurgy. Not only the research methods were very perfect, but also the independent structures and systems of it had been formed. One of the important tasks of metallurgical reaction engineering was the simulation of metallurgical process. And then, the mechanism of reaction process and the conversion time points of different control links should be obtained accurately. Therefore, the research methods and results of reaction kinetics in metallurgical physical chemistry were not very suitable for metallurgical reaction engineering. In order to provide the definite conditions of transmission, reaction kinetics parameters and the conversion time points of different control links for solving the transmission and reaction equations in metallurgical reaction engineering, a new method for researching kinetics mechanisms in metallurgical reaction engineering was proposed ,which was named stepwise attempt method. Then the comparison of results between the two methods and the further development of stepwise attempt method were discussed in this paper. As a new research method for reaction kinetics in metallurgical reaction engineering, stepwise attempt method could not only satisfy the development of metallurgical reaction engineering, but also provide necessary guarantees for establishing its independent subject system.

Jan 1, 2015

By M. R. Baren

Unpublished results obtained by Baren on thermodynamic properties of sulfur in liquid Fe. Co. Ni. Fe-Co. Fe-Ni. and Co-Ni are reevaluated. correlated. and interpreted on the basis of recent developments in thermodynamics of alloys:. Existing reliable data are reviewed and compared with the? present results. Sulfur obeys Henry's law up to 0.04 mol fraction. and in this range the standard Gibbs energy of solution of sulfur is expressed as a linear function of temperature for each pure metal. The activity coefficient of sulfur in each binary metal solvent 1s correlated with the composition of alloy.

Jan 1, 1983

By Zhi-yong Liu

A novel process, which includes hydrochloric acid leaching, iron powder cementation, sulphide precipitation and spray pyrolysis, was proposed to treat iron concentrate recovered from zinc kiln slag for comprehensive utilization. Treated by two-stage hydrochloric acid leaching, the leaching extents of Ag, Pb, Cu, Fe and Zn are 96.78%, 95.14%, 97.72%, 94.51% and 87.74%, respectively. More than 99% Cu and Ag are recovered from the leach liquor when iron powder is 25% higher than the stoichiometric requirement. More than 96% Pb and Zn is removed with three times of theoretical consumption of FeS, and the concentration of impurities of the final solution is less than 500 mg/L. Fe2O3 powder, which is spherical with a mean size of 12 μm and purity of 99%, is prepared with final solution at 700 °C. In this process, not only the metal values can be recovered effectively, but also the iron resources of zinc kiln slag can be converted into high purity Fe2O3, thus, the comprehensive utilization of iron concentrate recovered from zinc kiln slag can be realized.

By Rina Kim

The addition of lead to a gold leaching reactor can effectively accelerate or retard the gold cyanidation reaction. This study explored the effect of lead on the gold dissolution kinetics using cyclic voltammetry (CV) experiments. It was illustrated that the gold leaching kinetics in the cyanide solution enhanced with the addition of lead salt in the low overpotential region (–0.35 V vs. Ag/AgCl). The similar behavior was observed in the presence of ore containing 0.25% galena. In contrast, the gold oxidation kinetics retarded at –0.35 V (vs. Ag/AgCl) in the presence of silicate and lead-bearing mineral under certain conditions. Likewise, the lead addition was not functional for the high sulfur ore. This was attributed to the oxidation of the sulfides to the elemental sulfur, which subsequently formed a passivating layer on the gold surface. The results were evidently affirmed by the electrochemical tests and X-ray photoelectron spectroscopy (XPS) analysis.

By Eric Pirard

Theoretical studies carried out on shape analysis supply mathematical tools to analyze the influence of grain shapes on ore beneficiation. In the case of statistic images like those encountered in applied mineralogy parametrical and harmonical analysis methods are used. It is important that the shape parameters are adapted to the specific processes involved in ore beneficiation, while remaining easy to manipulate. The inertia parameters are considered in the scope of granulometric and gravimetric processes It appears that they are able to distinguish between the resulting products where very popular shape parameters are not. The measured statistics are analyzed through discriminant analysis procedures in order to estimate the importance of morphological differentiation and the aptitude of shape parameters to account for this.

Jan 1, 1989

By Jared Ball, Darren Snashall, Paul Telford, Pengfu Tan, Ben Hogg

"The foamed converter charges were up to 3 8 per month in Xstrata Copper Smelter at Mount Isa. The issue of high converter foamover frequency had remained unsolved for many decades in Mount Isa. A thermodynamic model of copper P-S converter and a viscosity model of converter slag have been developed to simulate the slag blow and copper blow, in order to understand the mechanism of converter foamover. The model predicts the chemistry and viscosity of slag during slag blow and copper blow. The effects of oxygen potential, charge of dirty reverts, slag carryover, under-blowing, over-blowing, and temperature on the foamover and viscosity of slag in copper blow have been discussed. A theory has been developed to understand the mechanism of converter foamover. The practical solutions have also been developed and implemented in Mount Isa Copper Smelter. Some improvements of the industrial operations have been presented. After a series of improvements, the number of foamed charges per month in the converter operations has been decreased significantly from 35 in Aug 2008 to only one per month in 2009/2010.1. IntroductionThe Copper Smelter in Mount Isa receives the concentrate containing about 25% copper and produces anode copper that contains about 99% copper. There are several stages in the process. The first stage carries out in the ISASMELT™ furnace. The ISASMELT™ process produces a molten copper matte containing about 60% copper. An iron-silica slag and a sulfur dioxidebearing off-gas are the by-products of the process. The slag is taken to the slag dams for cooling before it is recycled through the Mount Isa Copper Concentrator.The matte is sent to Peirce-Smith converters. The converters further remove iron and sulphur to produce blister copper which contains about 97% copper. The anode furnaces remove any remaining sulphur and oxygen to produce anode copper that is about 99. 7% pure. This is cast into anodes and sent to the Xstrata Copper Refinery in Townsville for final refining.In the copper pyrometallurgical industrials, slag foaming is an important phenomena which occurs when the gas bubbles have stability and not rupture. Foaming greatly increases the interfacial area between matte, slag and gas and is essential for the operation of high intensity smelting processes. However, foaming or foamover is undesirable in P-S converter since it can damage the equipment and injure the operators. Figure 1 shows that the whole process of a foamover development in a converter."

Jan 1, 2011

By Omid Marzoughi

Chromium has a wide range of applications, including as an alloy addition in various steels and also as a corrosion resistance coating. Carbothermal reduction of chromite ore (FeCr2O4) in a submerged arc furnace is an important industrial process for extracting chromium, but the energy consumption is excessive. It is suggested that one area for future research is the low temperature carbothermic solid state reduction of chromite to produce an intermediate product, which can subsequently be upgraded to ferrochromium. In this regard, a thermodynamic model has been developed to investigate this process and the effects of temperature, carbon additions and ore composition on the recovery of chromium and the grade of the ferrochromium, have been studied. Further development of the model may allow it to be applied to the simulation of other processes for the recovery of chromium from chromite ores.

By Kaixi Jiang, Lan Li, Bang Wei, Haibei Wang, Yaping Feng

"China is currently the world's largest copper producer. In the last five years, 950 kt/y of smelting capacity was commissioned. Currently, about 1200 kt/y smelting capacity is under construction and about 2000 kt/y smelting capacity is under feasibility study. Ausmelt/ISA smelting and flash smelting technologies were commonly adopted in China. After the double-flash-smelter was first adopted in 2004, three new double-flash-smelters are scheduled. Recently, two new copper smelting technologies were developed in China. One is an improved bath side-blown smelting process, and another is the SK.S bottom blowing process. Both technologies have been in practice for over three years and have achieved good technical performance. Approximately 500 kt/y new smelting capacity in China and India will adopt these technologies. Both technologies have the advantages of low investment cost, low energy consumption and high flexibility for complex raw materials. This paper reviews ""green"" copper smelting projects in China and introduces the practices of the two new Chinese smelting technologies.IntroductionPresently, China is the largest copper producer in the world. As far as the smelting of copper is concerned, there are many smelting processes applied in industrial production, such as flash smelting, Noranda smelting, Ausmelt smelting, Isa smelting, the Mitsubishi process, Vanukov smelting, silver copper-smelting, SKS smelting, both side-blown smelting, traditional blast furnace smelting, electric furnace smelting, reverberatery smelting and so on . Except the last three traditional processes that are eliminated because of their failure to meet the requirements for environmental protection, all of the other above-mentioned methods are advanced smelting processes adopted nowadays."

Jan 1, 2012