A pilot-scale treatment study was implemented at a deposition site of chromite ore processing residue (COPR) in New Jersey. Ferrous sulfate heptahydrate (FeSO47H2O) was employed to reduce hexavalent chromium in two dosages with three types of soil mixing equipment. XANES analyses of treated samples cured for 240 days indicated that all treatment combinations failed
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05.11.2018Abstract This study presents chemical, mineralogical, and leaching characterization of chromite ore processing residue (COPR) derived from the soda ash process, which is currently replacing the lime-based process in China, the world's largest chromite processor. Results indicated that, while soda ash COPR had 8,500 mg/kg Cr(VI), 90% of that was readily
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01.11.2008In dynamic droplet leaching tests, the Cr leaching concentrations were less than 50 μg/L; the mechanism of Cr leached from solidified materials was mainly a combination of wash-off and diffusion.
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11.04.2007Leaching of Cr (VI) especially occurs in the pond sediments, which are low in OC, CEC and clay content, under acidic and neutral pH conditions (e.g. up to ∼2,230 mg/kg Cr (VI) leached from a sample containing a total concentration of Cr 12,200 mg/kg).
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Leaching of hexavalent chromium from young chromite ore processing residue Katrin Matern1 Harald Weigand2 Ruben Kretzschmar3 Tim Mansfeldt1 1Faculty of Mathematics and Natural Sciences, Dep. of Geosciences, Institute of Geography, Univ. of Cologne, Albertus-Magnus-Platz, Kln, D-50923, Germany 2ZEuUS, THM Univ. of Applied Sciences,
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leaching process for chromite. chrome ore acid leaching somalia xclusivedirectorycoza Feb 28 2006Occupational Exposure to Hexavalent Chromium 71 10099 10385Value of 100 mu g m3 for chromic acid and chromates as Cr2O3 Ex5 37 in this state in ores such as ferrochromite or chromite ore FeCr2O4 less water soluble chromates eg calcium chromate in
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This study aims to provide information on the leaching characteristics of COPR, focusing on the geochemical parameters(e.g.pH)and the most important mineral phases which may control chemical behaviour.It will be shown that chromium re-lease is dominated by a small proportion of soluble chromium phases,independent of the bulk chromium content of the material.This
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Experimental results suggested that Cr(VI) solubility is controlled partially by Cr( VI)-hydrocalumite at pH 10.5 and by hydrotalcites at pH8 in addition to adsorption of anionic chromate species onto inherently present metal oxides and hydroxides at pH 8.5. Batch leaching tests, qualitative and quantitative x-ray powder diffraction (XRPD) analyses, and geochemical modeling were
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Abstract. This study reports on the leaching characteristics of COPR from the soda ash roasting process that contained 8,500 mg/kg of Cr (VI), indicating poor recovery during the leaching process. To this end, leaching with different extraction solutions was studied as a function of time. The DI water, 0.1M NaOH and 1M NaOH leaching results
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Xiao, Kai, Li, Guo Cheng (2012) Leaching Mechanism of Cr(VI) from Chromite Ore Processing Residue with Nitric Acid. Advanced Materials Research, 450. 764-768 doi:10.
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The majority of ferrochrome (FeCr) is produced through the carbothermic reduction of chromite ore. In recent years, FeCr producers have been pressured to curve carbon emissions, necessitating the exploration of alternative smelting methods. The use of hydrogen as a chromite reductant only yields water as a by-product, preventing the formation of carbon monoxide (CO)
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01.01.2006As a result of chromite ore processing, large amounts of chromite ore processing residue (COPR) material that can be classified as hazardous have been produced and released into the environment. Therefore, knowledge of migration behavior and leaching rates of chromium through waste materials are of primary concern for environmentally sound
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01.04.2011Leaching kinetics of acid-soluble Cr(VI) in chromite ore processing residue (COPR) using hydrofluoric (HF) acid solution as a leaching agent was investigated for potential remediation of COPR with
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05.08.20211. Introduction. The soda ash roasting process produces Chromite Ore Processing Residue (COPR) containing 1130–8500 mg/kg carcinogenic hexavalent chromium (Cr(VI)) due to the industrial incomplete leaching (Du and Chrysochoou, 2018, Chrysochoou et al., 2009).Compared with the lime-based roasting process, soda ash as the complexing agent
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Chromite ore processing residue (COPR) is a waste derived from the chromate extraction from roasted ores and is deposited in some countries in landfills. The objective of this study was to investigate the leaching characteristics of hexavalent Cr [Cr(VI)] from two COPR samples obtained from unlined Show more
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18.11.2021The leaching of Cr (VI) into groundwater can be further elaborated using the thermodynamic model of Ball et al. [ 73] for the Cr-minerals (oxides, hydroxides, etc.) in the aqueous medium as given in Eq. 1 – 3 and Fig. 2. Cr (OH)_ {3} + H^ { + } to Cr (OH)_ {2}^ { + } + H_ {2} O (1) Cr_ {2} O_ {3} + 2H^ { + } + H_ {2} O to 2Cr (OH)_ {2}^ { + }
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： Leaching kinetics of acid-soluble Cr(VI) from chromite ore processing residue with hydrofluori. Leaching kinetics of acid-soluble Cr(VI) from chromite ore processing residue with hydrofluori. J Ce t S u h Un v T c n 1 f 0 8 3 9 4 5 . n .
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Leaching Mechanism of Cr(VI) from Chromite Ore Processing Residue with Nitric Acid - Kai Xiao, Guo Cheng Li
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The leaching behavior of hexavalent chromium (Cr(VI)) and major metal elements relevant to Cr(VI) leaching from chromite ore processing residue (COPR) to HNO3 are investigated by batch leaching tests. According to the test results, aqueous Cr(VI) accounted for 70-80% of the content of total Cr. Cr(VI) concentration was controlled by the dissolution degree of Cr(VI)
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Chromate salts can be produced by roasting chromite ore with lime in a kiln under oxidizing conditions. This con-verts a portion of the Cr(III) in the ore to Cr(VI).1 Much of the water-soluble Cr(VI) is then extracted from the roasted ore by leaching with an aqueous solution. The residual material, chromite ore processing residue (COPR), is highly
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Remediation of hexavalent chromium contamination in chromite ore processing residue by sodium dithionite and sodium phosphate Toxicity Characteristic Leaching Procedure (TCLP Cr) Khan and Puts, 2003). The general mechanism of Cr(VI) treatment in Na 2 S 2 O 4 applications involves the conversion of Fe(III) present in the Cr-containing . 4
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1 Recycling treatment of wastewater containing hexavalent chromium [Cr (VI)] has always been an important environmental issue. In this paper, taking advantage of the natural affinity of CrO 4 2-and lead ions, lead carbonate was selected as a precipitant to recover Cr (VI) in the form of chrome yellow (PbCrO 4).Firstly, the variation of Cr (VI) and lead species in K +-CrO 4 2-Pb
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Leaching Mechanisms of Cr(VI) from Chromite Ore Processing Residue . Close Log In. Log in with Facebook Log in with Google. or. Email. Password. Remember Leaching Mechanisms of Cr(VI) from Chromite Ore Processing Residue. Journal of Environment Quality, 2008. C. Christodoulatos. Download Download PDF.
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Weng, C.H.: 1994, Transport of chromium in porous media: Chemical behavior of chromite ore processing waste relating to chromium leachability and transport in CH., Huang, C. Sanders, P.F. Effect of pH on Cr(VI) Leaching from Soil Enriched in Chromite ore Processing Residue. Environmental Geochemistry and Health 23, 207–211
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01.05.1991Chromite ore processing residue occurs at over 130 sites in Hudson County, New Jersey. Many of these sites are in urban residential areas. This waste is a result of 70 years of chromate and bichromate chemical manufacturing. At least 15% of the sites contain total chromium concentrations greater than 10,000 mg/kg, with hexavalent content ranging from
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A Clean And Efficient Leaching Process For Chromite Ore. Jun 01, 2014 In summary, the following kinetic equation can be applied to describe the pressure leaching process for chromite ore in 50 wt KOH solution 3 1 - 1 - x 1 3 20537 P O 2 1.16 e - 64020 RT t.
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Publication date: Available online 26 November 2019Source: Chinese Chemical LettersAuthor(s): Xiaofeng Mo, Jin Zhou, Le Lin, Zuqi Zhong, Shaohua Yang, Xueming Liu, Zhenqing Shi, Dongye Zhao, Zhang LinAbstractThe effective extracting Cr(VI) from chromite ore processing residue (COPR) is the key to achieve COPR detoxification and recovery. We developed an effective
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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 synthetic rainwater and groundwater for 250 pore volumes of flow (PVFs).
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01.11.2021Chromium leaching behavior in soil derived from chromite ore processing waste Sci. Total Environ., 154 ( 1 ) ( 1994 ), pp. 71 - 86, 10.1016/0048-9697(94)90615-7 Article Download PDF View Record in Scopus Google Scholar
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26.04.2011Leaching kinetics of acid-soluble Cr(VI) in chromite ore processing residue (COPR) using hydrofluoric (HF) acid solution as a leaching agent was investigated for potential remediation of COPR with industrial waste water containing HF. The results show that HF can effectively destabilize the Cr(VI)-bearing minerals, resulting in the mobilization of Cr(VI) from
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The great challenge of remediation of chromite ore processing residue (COPR) lies in how to effectively eliminate or extract in COPR. After the treatment, the Cr(VI) concentration in the leachate by toxicity characteristic leaching procedure (TCLP) markedly decreased to 1.1 mg L-1, well below the regulatory limit of 1.5 mg L-1 (GB 16889
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01.01.2002Batch 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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This study investigates the leaching behavior of hexavalent chromium (Cr S.C. Jagupilla, D.H. Moon, C. Christodoulatos, A. Koutsospyros, Leaching mechanism of Cr(VI) from chromite ore processing residue, J P.F. Sanders, Chromium leaching behavior in soil derived from chromite ore processing waste, Sci. Total Enviro. 154 (1994) 71-86
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13.07.2022The mineralogical and chemical composition of chromite ore processing residue (COPR) from a site in the north of France (Lille) was investigated. The mineralogical composition was obtained by X
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The results from this study indicate a need for efficient leaching methodologies in chromite ore processing plants to decrease the non-detrital fractions of chromium in the residue. Speciation and recovery of chromium from chromite ore processing residues. K. J. Sreeram and T. Ramasami, J. Environ. Monit., 2001, 3
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26.02.2013Chromite ore processing residues (COPR) is the source of the Cr(VI) contamination in the environment. Pannonibacter phragmitetus BB was used to treat two different types of COPRs in this research. The water-soluble Cr(VI) of COPR A and B is 3,982.9 and 1,181.4 mg/kg, respectively. In the column biotreatment process, P. phragmitetus BB can
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11.08.2016Long-term leaching characteristics of chromium ore processing residue (COPR) (≈ 250 pore volumes of flow, PVF) was investigated using laboratory flow-through column testing with synthetic groundwater (GW).
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01.09.2011Chromite ore processing residue (COPR), derived from the so-called high lime processing of chromite ore, contains high levels of Cr(III)
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05.07.20191. Introduction. Chromite ore processing residue (COPR) is an industrial waste generated during the extraction of Cr(VI) from chromite ore using the high-temperature lime-based roasting process [,, ].When COPR undergoes weathering reactions during the deposition process, it would release highly toxic and mobile Cr(VI) due to the destabilization and
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01.05.2017Large amounts of chromite ore processing residue (COPR) wastes have been deposited in many countries worldwide, generating significant contamination issues from the highly mobile and toxic hexavalent chromium species (Cr(VI)). In this study, sodium dithionite (Na2S2O4) was used to reduce Cr(VI) to Cr(III) in COPR containing high available Fe, and
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