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With the goal of improving the leaching behavior of chromite in sulfuric acid solution, Geveci et al. used perchloric acid as the catalyst in the leaching process at atmospheric pressure, achieving 83% chromium …
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Another processes are based on aqueous leaching of manganese ore in the presence of sufur dioxide (Herring and Ravitz, 1965). Hydrochloric acid leaching of manganese nodules was reported by Kanungo (Kanungo and Jena, 1988). Sulfuric acid leaching with charcoal (Das et al, 1989), under oxygen pressure (Anand et al, 1980) was also applied.
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The experimental results confirmed that under the optimal alkaline roasting and water leaching conditions of the mass ratio of ferronickel slag to Na 2 O 2 of 1, roasting temperature of 600 °C ...
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Kinetics analysis revealed that the leach-ing process is controlled by a chemical reaction under the employed experimental conditions and the activation energy of the reaction is 48 kJ·mol–1. Keywords: chromite ore treatment; sulfuric acid; leaching kinetics; physical models 1. Introduction Global demand for chromium salts has tended to increase
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The acid leaching process is a mature method for the extraction of metal elements from ores and secondary resources, which is commonly used in the treatment of nickel ore (Thubakgale et al., 2013), copper ore (Li and Zhou, 2009), uranium ore (Hu et al., 2009) and iron ore (Wang et al., 2012).
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The sulfuric acid leaching process is widely considered to be a cleaner technology to prepare chromium salt from natural chromite as no Cr (VI)-bearing wastes are generated or discharged. However, some insoluble anhydrous chromium sulfate could precipitate causing a serious chromium resource loss and potential pollution problems.
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Batch leaching studies on chromite ore processing residue (COPR) were performed using acids to investigate leaching of hexavalent chromium, Cr(VI), with respect to particle size, reaction time ...
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DOI: 10.1089/ees.2018.0047 Corpus ID: 239831715; Chemistry and Leaching Behavior of Chromite Ore Processing Residue from the Soda Ash Process @article{Du2018ChemistryAL, title={Chemistry and Leaching Behavior of Chromite Ore Processing Residue from the Soda Ash Process}, author={Yaguang Du and Maria …
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And the other leaching process is the oxalic acid leaching. In this process more than 99% of Li and less than 1% of Co were dissolved at the condition of 3M oxalic acid, 80°C reaction temperature ...
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Chromite ore processing residue (COPR) is the solid residue produced by high lime process and classified as a hazardous waste for having 1–2% hexavalent chromium [Cr(VI)] (Kowalski and Gollinger-Tarajko, 2003). ... This paper proposes a detoxification process of two-stage sulfuric acid leaching accompanied by biomass …
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For example, most of the chromite mines in the Philippines and Vietnam are chromite sand. After desliming by washing, the grade of chromite sand will rise greatly, and it will be further improved by jigs and shaking tables. 2. Concentration. The predominant method to concentrate chromite stone is gravity separation.
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The sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly … Expand
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A high grade chromite concentrate obtained from the Pinarbasi region of Kayseri province in Turkey was reacted with a solution of sulfuric acid and perchloric …
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The sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly ...
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Abstract. In order to improve the chromate salts cleaner production technology, a pressure leaching process for chromite ore in 50 wt% KOH solution was studied for the first time and the results were presented in this manuscript. It was found out that the chromium extraction rate increased significantly with the increase of temperature …
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The sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly ...
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Chromium ore processing residue (COPR) is classified as hazardous solid waste because of the leachable Cr(VI). Cementitious materials are often used to solidify and stabilize heavy metals. However, most of them focus on the leaching concentration of particles after solidification and stabilization and lack research on leaching …
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During the roasting process, the chromium-containing phase ((Fe0.6Cr0.4)2O3) reacted with Na2CO3 and formed Na2CrO4, and then leached out in the water leaching …
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The sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly ...
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Leaching characteristics of chromium ore processing residue (COPR) for the long term (simulating a 20-year leaching scenario) were investigated using laboratory flow-through column testing with ...
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Key words: leaching; kinetics; hydrofluoric acid; hexavalent chromium; chromite ore processing residue 1 Introduction Chromite ore processing residue (COPR) is a solid residue produced by the so-called high lime process. COPR was classified as a hazardous waste for containing 1%−2% hexavalent chromium (Cr(VI)) [1], which is a mutagenic ...
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Abstract The effects of the nitric acid concentration, leaching time, leaching temperature, and solid-to-liquid ratio on leaching efficiency were examined. From those …
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chromite ore processing residue (COPR) is an inevitable solid emission in chromite salt production. It is an industrial waste produced during the extraction of Cr(VI) from a chromite ore using the high-temperature roasting process.11 In general, the COPR is alkaline (pH > 12),5,7 and because of the presence of partially water-soluble ...
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The Fe content in the FeCr produced depends on the chromite spinel Cr/Fe ratio. Therefore, the selective removal of Fe from the chromite spinel using different combinations of chromite pre-oxidation, pre-reduction, and sulphuric acid leaching was investigated. The Cr/Fe ratio of the case study ores could be increased from 1.57 up to …
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The sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly understood. In this work, binary spinels of Mg–Al, Mg–Fe, and Mg–Cr in the powdered and lump states were synthesized and used as raw …
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The manganese leaching study used a -200 mesh way kanan manganese ore that was reacted with sulfuric acid at concentrations of 0.1 M, 0.5 M, and 1 M, as well as corncob as a reductant. To separate the dissolved iron in the leaching process, the manganese sulfate solution was purified with sodium hydroxide and then filtered to have a …
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The leaching process of acid-soluble Cr(VI) from COPR is controlled by the diffusion through the product layer. The apparent activation energy is 8.696 kJ/mol and the reaction orders with respect to HF concentration and particle size is 0.493 8 and −2.013 3, respectively. ... Leaching kinetics of acid-soluble Cr(VI) in chromite ore processing ...
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The optimum parameters for COPR leaching were as follows: mechanical ball-milling time of 120 min, sulfuric acid concentration (w/w % H 2 SO 4) of 60%, …
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In industry, chromite is firstly converted to chromate solution (such as Na 2 CrO 4 or K 2 CrO 4 ) by soda ash roasting and leaching. Then, the chromate is converted to Cr 2 O 3 by acidification ...
DetailsThe sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly ...
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The optimum process conditions of leaching treatment were found to be a temperature of 176 °C, a dichromic acid/chromite mass ratio of 0.12, and a sulfuric acid concentration of 81%.
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1. Introduction. Chromite ore processing residue (COPR) is an industrial solid waste [1].It has been reported that 2–3 t of COPR is generated in the production of 1 t chromic salts [2].Accumulation of COPR takes up considerable land, and when the leached hexavalent chromium flows into the water after rainfall, it pollutes the water and the soil …
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Semantic Scholar extracted view of "Effects of particle size and acid addition on the remediation of chromite ore processing residue using ferrous sulfate." ... Leaching kinetics of acid-soluble Cr(VI) in ... was caused by anion exchange of sulfates for chromate in the layered double hydroxide mineral hydrocalumite, a process for which scanning ...
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In this study, the liquid-phase oxidation process of chromite ore in 50 wt% KOH solution was investigated, and it was found out that chromite ore could be efficiently …
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The chromite mineral phase in COPR has a formula of (Fe, Mg)Cr 2 O 4, it is difficult to determine the exact portion of substituted Fe(II) in chromite, thus we studied the contribution rate of Cr(III) and sulfuric acid to Mn leaching by using pure chromium oxide (Cr 2 O 3) to eliminate the influence of existed Fe(II). The contribution rate of ...
DetailsThe sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly ...
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