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By T. Tamagawa

A gaseous chlorination process for hydrometallurgical treatment of a chalcopyrite concentrate was investigated. The overall process is visualized to consist of low temperature chlorination-selective oxidation, followed by aqueous chloride leaching and SX-EW for producing electrolytic copper, elemental sulfur and ferric oxide. In this article, the chlorination phase of the processes is described. Initially, the chlorination behavior of chalcopyrite-concentrate micro-pellets was investigated using a small batch-type fluidized bed reactor. The optimum conditions thereby established was used in continuous chlorination tests. The chlorinated products thus prepared were used in the selective oxidation phase of the investigation.

Jan 1, 1999

By T. Tamagawa, N. S. Fu, I. Iwasaki, M. Kobayashi

A 3-stage fluidizing bed process of chlorination, selective oxidation and sulfur chloride conversion was tested for processing of a chalcopyrite concentrate. It was found that the use of excess oxygen was essential to a stable operation in the oxidation reactor. The oxygen-excess gas will inevitably cause the oxidation of the sulfide concentrate in the chlorination and sulfur chloride conversion reactors. A new flowsheet is proposed to separate the chlorination and the selective oxidation steps with separate flow paths of the fluidizing gases, thereby preventing the passage of oxygen-excess gas in the chlorination and sulfur chloride conversion reactors. The feasibility of the proposed flowsheet was demonstrated in a laboratory-scale fluidizing bed setup.

Jan 1, 2000

By T. Tamagawa

A gaseous chlorination process for hydrometallurgical treatment of a chalcopyrite concentrate was investigated. The overall process is visualized to consist of low temperature chlorination-selective oxidation, followed by aqueous chloride leaching and SX-EW for producing electrolytic copper elemental sulfur and ferric oxide. In this article, the chlorination phase of the processes is described. Initially, the chlorination behavior of chalcopyrite-concentrate micro-pellets was investigated using a small batch-type fluidized bed reactor. The optimum conditions thereby established was used in continuous chlorination tests. The chlorinated products thus prepared were used in the selective oxidation phase of the investigation.

Jan 1, 1999

By J. E. Sepulveda

Tar sand deposits in the. Stare of Utah contain more than 25 billion barrels of in-place bitumen, Although thirty times smaller than the well-known Athabasca tar sands, Utah tar sands do represent a significant domestic energy resource comparable to the national crude oil reserves (31.3 billion barrels), The term "tar sand" refers to a consolidated mixture of bitumen and sand, Based upon a detailed analysis of the physical and chemical properties of both the bitumen and the sand, a hot-water extraction process for Utah tar sands is currently being developed in our laboratories at the University of Utah. This process involves intense agitation of the tar sand in a hot caustic solution and subsequent separation of the bitumen by a modified froth flotation technique., Experimental results indicated that, for a given tar sand sample, percent solids and caustic concentration were the two most important variables controlling the performance of the digestion stage, These variables were identified by means of an experimental, factorial design, in which coefficients of separation greater than 0.90 were realized. Although preliminary in nature, the experimental evidence gathered in this investigation seems to indicate that a hot-water extraction process for Utah tar sands would allow for the efficient utilization of this important energy resource.

Jan 1, 1978

By T. Tamagawa, S. H. Tabaian, I. Iwasaki, N. X. Fu, M. Kobayashi

A gaseous chlorination process for the hydrometallurgical treatment of a chalcopyrite concentrate was investigated. The overall process is visualized to consist of low-temperature chlorination -selective oxidation, followed by aqueous chloride leaching and SX-EW for producing electrolytic copper, elemental sulfur and ferric oxide. In this article, the chlorination phase of the process is described. Initially, the chlorination behavior of chalcopyrite concentrate micropellets was investigated using a small batch-type fluidized bed reactor. The optimum conditions thereby established were used in continuous chlorination tests. The chlorinated products thus prepared were used in the selective oxidation phase of the investigation.

Jan 1, 2000

By T. Tamagawa, I. Iwasaki, N. X. Fu, M. Kobayashi

A low-temperature-chlorination selective oxidation followed by aqueous chloride leaching and SX-EW for producing electrolytic copper, elemental sulfur and ferric oxide was investigated for hydrometallurgical processing of a chalcopyrite concentrate. In this article, the selective oxidation phase of the process is described. The selective oxidation requires a temperature well above the CuCl-FeCl3 eutectic points. The test procedure was developed with a batch reactor and then tested with a continuous reactor. The process was initiated by adding small amounts of chlorinated samples to a fluidizing bed of dead-roasted sulfide concentrate micropellets. The selectively oxidized samples thus prepared were shown to fully dissolve copper, while virtually all the iron remained undissolved.

Jan 1, 2000

By T. Tamagawa, I. Iwasaki, N. X. Fu, M. Kobayashi

A three-stage fluidizing-bed process consisting of chlorination, selective oxidation and sulfur chloride conversion was tested for processing chalcopyrite concentrate. It was found that the use of excess oxygen was essential for the stable operation of the oxidation reactor. The excess-oxygen gas inevitably causes the oxidation of the sulfide concentrate in the chlorination and sulfur chloride conversion reactors. A new flowsheet is proposed to separate the chlorination and selective oxidation steps with separate flow paths of the fluidizing gases, thereby, preventing the passage of excess-oxygen gas in the chlorination and sulfur chloride conversion reactors. The feasibility of the proposed flowsheet was demonstrated in a laboratoryscale fiuidizing bed setup.

Jan 1, 2002

By Michael Moats, Weston Hartzell

The stable domestic supply of gallium, indium, and germanium has been identified as a critical need for the USA. Electric arc furnace dusts processed to recover zinc produce a process residue that could be a potential source of these critical materials. An industrial zinc leach residue was characterized to determine the predominant mineral phases and leached with common mineral acids. Atmospheric agitated leaching using sulfuric acid and hydrochloric acid were examined to determine the extractions of gallium, indium, and germanium as a function of concentration, temperature, and time. Extractions of gallium were found to be similar to iron in all experiments. The maximum percentage of Ga, Ge, and In leached into solution were 82%, ~100%, and 89%, respectively.

Aug 8, 2023

By M. S. Moats, W. C. Hartzell

The stable domestic supply of gallium, indium, and germanium has been identified as a critical need for the United States. Electric arc furnace dusts, processed to recover zinc, produce a residue that could be a potential source of these critical materials. An industrial zinc leach residue was characterized to determine its particle size, chemical composition, and predominant mineral phases. Heated, atmospheric, agitated leaching using sulfuric acid and hydrochloric acid was examined to determine the extractions of gallium, indium, and germanium as a function of concentration and temperature. Extractions of gallium were found to be similar to iron in all experiments. The maximum percentage of Ga, Ge, and In leached into solution were 71%, 63%, and 48%, respectively.

Feb 1, 2023

By C. R. Zegarra

Extraction of manganese, gold, and silver from a low-grade manganiferous-silver ore was investigated by thiourea leaching followed by standard cyanidation. The levels of reagent concentrations in this investigation were 0.0 -1.0 M thiourea and 0.0 -1.0 M sulfuric acid. Temperature and agitation speed were maintained at Z5 °c and 300 rpm, respectively. The dissolution of gold, and silver was shown to be dependent mainly on sulfuric acid and thiourea concentrations. In general, 50.0 % Ag, 98.0 % Au, and 75 % Mn were recovered from a Mn-Ag ore by thiourea leaching. Overall silver extraction of 98.0 % was obtained by cyanidation after thiourea leaching. Thiourea leaching of sodium bisulfite leach residues was also studied, and the total extraction of gold and silver were 97 % and 40 %, respectively. Finally, a two-stage thiourea leach was also investigated.

Jan 1, 1988

By R. A. Pyper, J. L. Hendrix

Laboratory leaching experiments were conducted to ascertain the effectiveness of acidic solutions of thiourea, CS(NH2)2, for dissolving gold from finely disseminated gold ores. The ore tested was from the Chipmunk ore body of the Northumberland mining district in Nye County, Nevada, USA. Extractions of up to 90% were attained from the ore. Extraction was shown to be dependent on thiourea concentration, ferric sulfate oxidant concentration, acid concentration, and leaching time. Optimum conditions were an ambient temperature leach near pH 1.0 utilizing 100 to 200 kg/ton thiourea and 50 kg/ton ferric sulfate for 8 to 24 hours.

Jan 1, 1981

By R. A. Pyper

Laboratory leaching experiments were conducted to ascertain the effectiveness of acidic solutions of thiourea, CS(NH2)2, for dissolving gold from finely disseminated gold ores. The ore tested was from the Chipmunk orebody of the Northumberland mining district in Nye County, Nevada, USA. Extractions of up to 90 percent were attained from the ore. Extraction was shown to be dependent on thiourea concentration, ferric sulfate oxidant concentration, acid concentration, and leaching time. Optimum conditions were an ambient temperature leach near pH 1.0 utilizing 100-200 kg/t thiourea and 50 kg/t ferric sulfate for 8 to 24 hours.

Jan 1, 1981

By Kenneth N. Han, Xinghui Meng

The leaching of gold and silver from various ores in ammoniacal solutions conta1mng various oxidants has been investigated. The samples tested included elemental gold, sulfidic as well as carbonaceous refractory ores, and tellurides. When pure elemental gold powders were used, the maximum amount of gold dissolved under the conditions studied was 16.3 ppm, 42.4 ppm, 82.0 ppm, and 152.2 ppm, respectively, at 140°C, 160° C, 180° C, and 200°C. Five different refractory ore samples were also tested. The recoveries of gold and silver from these refractory ores were typically 92% and 95%, respectively.

Jan 1, 1992

By Yeonuk Choi, Patrick R. Taylor, Lyle Cunningham

Laboratory experiments have been performed to evaluate the potential for metal removal and recovery from river bed tailings by ferric chloride leaching. The lead, zinc, silver and other metals in the river bed occur due to the old method of dumping mill tailings into rivers. This was practiced prior to the introduction of tailings impoundments. The effects of the leaching method, leaching time, pulp density, ferric chloride concentration, and leaching temperature on the rates and recoveries of lead, zinc and silver were studied. The effects of pulp density and leaching temperature were significant on the extraction rates of lead, zinc and silver. The lead content in the leached tailing was reduced to 0.023 percent, when using an 353O K leaching temperature and 0.384 g of FeC13/1 g of sample.

Jan 1, 1992

By D. B. Dreisinger, H. J. Sohn, J. S. Sohn, G. A. Kordosky

The transport of lithium through a supported liquid membrane was studied with a mixture of D2EHPA and TBP in kerosene as a mobile carrier. In the flat- sheet supported liquid membrane(SLM) system, experiments were carried out to investigate the effects of concentration of mobile carriers in the membrane solution, hydrogen ion in the feed solution, and temperature on the transport of lithium. Experimental results agreed well with a transport model for permeating lithium across the liquid membrane. The permeation rates of lithium can be explained in terms of diffusion of a Li-complex through the membrane phase. For a practical application of an SLM method, a hollow fiber module has been used and lithium can be concentrated more than three times in 24 hours.

Jan 1, 1993

By P. K. Naik, S. C. Das

Leaching studies of low-grade manganese ore containing 31.77% Mn and 23.71 % Fe from Nishikhal, India, were carried out using pyritiferous lignite as a reductant in sulfuric acid medium. The variables studied were quantity of lignite, sulfuric acid concentration and temperature. Regression equations for the extraction of manganese and potassium were determined from 23 full factorial design data. The experimental conditions for the extraction of manganese were optimized using the steepest-ascent method. It was found that 99.03% of the manganese could be extracted in three hours with an ore to lignite ratio of 1:1.8, a sulfuric acid concentration of 1.9 M and a temperature of 99°C. Key words: Leaching, Manganese ore, Lignite, Statistical design

Jan 1, 2003

By X. Cai, L. Jiang, G. Fu

A process for recovering manganese from low-grade manganese oxide ore through a reduction acidolysis-selective leaching method is investigated. Two types of biomass, sawdust and straw, were used as reductants. Reduction acidolysis, using concentrated sulfuric acid, was used to disrupt the structure of the biomass, allowing the biomass to be hydrolyzed into monosaccharides. Analysis by X-ray diffraction revealed that Mn2O3 was reduced to MnSO4. Then, in the selective leaching process, iron was removed through the formation of goethite. The optimized experimental parameters are as follows: reductant to ore mass ratio of 0.4, sulfuric acid to ore mass ratio of 0.9, water to ore ratio of 0.5, aging time of 18 h, leaching temperature of 95 °C, leaching time of 90 min, and solution pH of 2.5 to 2.8. Under these conditions and using sawdust as the reductant, the manganese leaching efficiency and iron removal efficiency were 91.8 and 99.2 percent, respectively.

By K. Osseo-Asare

LIX63 in combination with DNNS selectively extracts nickel and/or cobalt from acidic leach liquors with pH values as low as 1.0. Nickel/cobalt and cobalt/nickel selectivities are achieved by varying the relative concentrations of LIX63 and DNNS. Increasing LIX63 concentration retards both extraction and strip-ping rates while DNNS has the opposite effect. Slope analyses of equilibrium data indicate that both LIX63 and DNNS are present in the extracted complexes. Examples of possible flowsheets are presented.

Jan 1, 1978

By B. R. Reddy, Y. V. Swamy, B. V. R. Murthy

Chromitiferous overburden containing nickel in oxide form is reduced with CO-CO2-N2 gas mixtures. This converts the nickel oxide to metallic nickel and restricts the iron oxide to the magnetite state to extract the nickel. Reduction experiments were carried out on 500-g samples in a bench-scale vertical reactor. The tests were run to establish the process parameters, including the optimum partial pressure of CO, the reducing gas flow rate, granule size and roasting time. The reduced calcine is then subjected to an ammonia-ammoniacal carbonate leach to extract nickel selectively as its amine complex. More than 90% of the nickel could be extracted with a volumetric CO/(CO+CO2) ratio of 0.57 at 750°C and a roasting time of 90 min. The addition of 2.5% (by weight) charcoal to the granules improved nickel extraction by 11 % to 19%. Nickel leaching efficiency with ammoniacal solution is compared to the bromine-methanol method.

Jan 1, 2000

By R. W. Bartlett

High salinity geothermal brines typically contain up to several hundred parts per million of valuable heavy metals, and because of the large potential flow of geothermal brines from future power plants, metal production as a by-product could be significant A-planned 55-MW demonstration plant near Niland, California should generate enough spent brine to contain approximately $670,000 per year in gross metal values. Lawrence Livermore Laboratory estimates (1) a Salton Sea Geothermal potential of 1300 to 8700 MW, which would translate to possible yearly heavy metal values between $5,800,000 and .$l05,000,000. Since these estimates were made on a conservative basis, this geothermal reservoir is potentially a large ore deposit. The heavy metals in order of decreasing abundance in high salinity brines from the Salton Sea geothermal field are usually manganese, zinc, iron, lead, and silver. All but manganese and iron are valuable enough to be of commercial interest. Minor amounts of copper and arsenic are also present. Although heavy metal precipitates, particularly lead, have been found in scales within pipelines and obtained from steam flashing, most of the metals remain soluble during steam production; hence removal of the valuable metals from the spent brine before reinjection in ground reservoirs is indicated. Because the heavy metal concentrations are low, a very simple and inexpensive process is required. The heavy metal value in Niland brine is only ' about $1 per 1000 gallons; see Table 1. The brine composition shown in Table 1 was taken from one of the brine samples used in our study. Projected post-flash brine from a steam plant has somewhat higher Zn and Pb values, but the gross heavy metal value is still less than $2 per 1000 gallons.

Jan 1, 1980