Showing papers in "Hydrometallurgy in 2008"

TL;DR: In this paper, atmospheric leaching of nickel laterite ores with sulphuric acid was examined, specifically the limonite, smectite (clay) and saprolite fractions.

TL;DR: A review of the literature on chalcopyrite leaching with ferric sulphate in acid medium is presented in this paper, where several parameters (ferric salt anion, oxidant concentration, pH and temperature) are examined and possible explanations are offered for the passivation of this sulphide during dissolution.

TL;DR: In this article, the NTB-modified adsorbent presented with broader peaks of inner O and inner Si-O centers, which fit very well with the Langmuir adsorption model.

TL;DR: In this article, the effect of redox potential on chalcopyrite leaching was evaluated in stirred Erlenmeyer flasks with 0.5 g of pure chal copyrite and 100mL of a Fe 3+ /Fe 2+ sulphate solution.

TL;DR: Most existing hydrometallurgical processes for the leaching of nickel laterites employ sulphuric acid. Alternative technologies that utilize other leaching agents such as hydrochloric acid and various organic acids are currently being examined and developed, and are the topics of as discussed by the authors.

TL;DR: In this paper, the results indicated that sorption was endothermic and spontaneous in nature, and the Langmuir monolayer capacity of the sorbent is 28.65mg g−1 and 32.05mg g −1 for La and Ce(III), respectively.

TL;DR: Cyanogenic Chromobacterium violaceum, Pseudomonas fluorescens, and P plecoglossicida were able to mobilize silver, gold, and platinum when grown in the presence of various metal-containing solids such as gold-containing electronic scrap, silver-containing jewelry waste, or======platinum-containing automobile catalytic converters as mentioned in this paper.

TL;DR: A mixture of rare earth double sulfates was produced from a Turkish bastnasite-containing pre-concentrate by sulfuric acid baking, subsequent water leaching and precipitation with sodium sulfate as discussed by the authors.

TL;DR: The first International Biohydrometallurgy Symposia was held in Braunschweig, Germany in 1977 as mentioned in this paper, which was the predecessor for the International Bio-Chemical Symposiums.

TL;DR: In this paper, the effect of redox potential in chalcopyrite bio-leaching in the presence of iron- and sulphur-oxidizing bacteria was investigated, and it was shown that the overoxidation of the leaching solution, due to the activity of acidithiobacillus ferrooxidans, Leptospirillum ferrooxideidans and Sulfolobus BC, favored the precipitation of jarosite on chal copyrite surfaces followed by passivation.

TL;DR: The first commercial implementation of nickel sulfide heap leaching is likely to be the operation at Talvivaara, Finland as discussed by the authors, where mixed microbial populations grew actively over many months in the presence of up to 400mM nickel (23g/L).

TL;DR: A new atmospheric scorodite synthesis process was investigated in this paper, where a large size and good crystalline scordite was precipitated at 95°C even in a short time of 1 to 7h when ferrous ions were oxidized by oxygen gas in the presence of As(V) ion with concentrations as high as 50g/L As in sulfuric acid solution.

TL;DR: The aims of this study were to isolate and characterize phosphate-solubilizing bacteria associated to a highphosphorous iron ore located in the Brazilian region of Minas Gerais and to determine the mechanisms by which they solubilize phosphorous moieties.

TL;DR: The sulfobacilli are moderately thermophilic acidophiles that grow in sulfurous and sulfidic environments with broad geographical distribution, across a range of temperatures and solution pH relevant to bio-leaching as mentioned in this paper.

TL;DR: In this article, the acid dissolution of waste dross rich in alumina value was taken for acid dissolution studies to recover alumina values, and the results obtained therefore, showed that aluminium dross could be utilized to prepare alumina chemicals and thereby avoiding stockpiling.

TL;DR: In this paper, the effects of concentrations of cane molasses and sulfuric acid, leaching temperature as well as reaction time were discussed, and the results showed that high manganese recovery with low Fe and Al extraction yield could be obtained by analyzing the leaching efficiencies of Mn, Fe, and Al during leaching process.

TL;DR: In this paper, the dissolution of a manganese dioxide ore in dilute sulfuric acid facilitated by Fe metal in the form of powdered sponge iron was investigated, and it was concluded that the usage of metallic iron for the reductive leaching of manganous dioxide was superior to that of ferrous ion as far as dissolution rate and efficiency were concerned.

TL;DR: In this paper, a feasible and applicable method for the extraction of zinc and lead that are present in the disposed Cinkur leach residues having 12.43% Zn, 15.51% Pb and 6.27% Fe was proposed.

TL;DR: In this paper, the combined effect of molar ratio Al/Li, pH and stirring time on lithium trapping at 25°C was investigated and optimized using response surface methodology (RSM), and the optimum values of these factors were found to be 4.7, 7.2 and 3.2 respectively.

TL;DR: Several responses appear to be especially characteristic of autotrophic microorganisms and may have direct implications for metabolic processes of critical relevance to the understanding of how these microorganisms survive and proliferate in extreme environments, including industrial bioleaching operations.

TL;DR: In this paper, the adsorption properties of 4-amino-1,2,4-triazole resin (4-ATR) for Re(VII) were investigated by static and dynamic measurements with ultraviolet-visible spectroscopy.

TL;DR: In this article, the effects of reaction temperature (95, 70, 50°C) and the oxidizing agent (air, pure oxygen gas) to optimize scorodite formation in a practical process were examined.

TL;DR: In this paper, the authors investigated the effect of solution composition on the optimum redox potential of chalcopyrite (CuFeS2) by Fe3+ in H2SO4 solutions.

TL;DR: In this article, a mechanically activated Panzhihua ilmenite in hydrochloric acid for the preparation of synthetic rutile was investigated and the results demonstrate that the mechanical pretreatment can take the place of the traditional high temperature pretreatment of ilmenites and avoid the dissolution being conducted under a pressurized condition.

TL;DR: In this paper, a soda ash roasting process for upgrading titania slag product of Rosetta ilmenite to a high grade titanium dioxide (TiO 2 ) is presented, which is carried out at moderate to high temperatures to yield a reaction product that would be easily decomposed by subsequent leaching procedures.

TL;DR: In this article, the authors characterize iron precipitates formed in liquid media inoculated with iron-oxidizing acidophiles (Acidithiobacillus ferrooxidans) by X-ray diffraction, elemental analysis, specific surface area, color, and scanning electron microscopy.

TL;DR: In this paper, the rate data per unit surface area of gold, silver, and gold-silver alloys based on electrochemical or chemical dissolution of rotating discs or foils of constant surface area in aerated cyanide solutions at ambient temperatures are analysed on the basis of the Levich equation.

TL;DR: In this paper, inorganic and organic acids produced by cultures of A thiooxidans or Aspergillus niger respectively were used to study the extraction of Co and Ni from laterite tailings.

TL;DR: In this article, a process of transformation of red mud, by treatment in acid and saline medium, into a concentrated liquid or solid but soluble product, containing high amounts of Al and Fe that is usable as a coagulant for water/wastewater treatment was described.

TL;DR: In this article, the main purpose of this study was to characterize and extract germanium from the ground copper cake of Cinkur Zinc Plant, which contained 15.33% Cu, 15.63% Zn, 1.6% As, 0.18% Sb and 3.42% SiO 2.