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Microstructural analyses of Cr(VI) speciation in chromite ore processing residue from the soda ash process. J. Hazard Mater., 393 (2020), Article 122385. ... Visible light accelerates Cr(III) release and oxidation in Cr-Fe chromite residues: an overlooked risk of Cr(VI) reoccurrence. Environ. Sci. Technol., 56 (2022), pp. 17674-17683.
Remarkably, the findings revealed that chromite ore could be significantly upgraded via magnetizing roasting in a hybrid microwave system, achieving an impressive 67.9% …
Our study provides a new insight into Cr (VI) reoccurrence in rCOPR and helps in predicting its environmental risk in nature. Keywords: Cr (III)−Fe (III) hydroxides; Cr (VI) …
Development of a rapid and simple digestion method of freshwater sediments for as, Cd, Cr, cu, Pb, Fe and Zn determination by inductively coupled plasma-optical emission spectroscopy (ICP-OES): An evaluation of dilute nitric acid. ... Weigand H, Singh A, Mansfeldt T. Environmental status of groundwater affected by chromite ore processing ...
Chromite sand sample obtain from Konowe-Southeast Sulawesi have low grade, so it needs process to enrichment Cr:Fe Ratio. Cr:Fe ratio feed was 0.55, after the process for size variation, roll ...
After tabling under optimized conditions, chromite concentrate contained 1.91 Cr/Fe ratio, 46.02% of Cr2O3 with 65.95% recovery.
The reduced chromite ore processing residue (rCOPR) deposited in environments is susceptible to surrounding factors and causes reoccurrence of Cr(VI). However, the impact of natural sunlight on the stability of rCOPR is still unexplored. Herein, we investigated the dissolution and transformation behaviors of Cr(III)–Fe(III) hydroxide, a typical Cr(III)-containing …
Around 90% of mined chromite ore is converted into different grades of ferrochrome by the metallurgical industry. Stainless steel industry consumes about 80% of ferrochrome produced (mainly high-carbon/charge grade). Chromite varies widely in composition according to the chemical formula (Mg, Fe +2) (Cr, Al, Fe +3) 2 O 4. Chromium occurs as ...
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 ∼23.4.
Thus, based on the ore-forming principle of natural mineral chromite, this study proposed a new FeSO 4 hydrothermal treatment to transform the unstable and toxic Cr(VI) in COPR into the magnetic spinel phase Fe 2+ (Cr 3+ X, Fe 3+ 2-x)O 4 (Fe Cr spinel substance), which could be recovered by further magnetic separation. In this process, FeSO 4 acted as …
Photomicrograph and back-scattered scanning electron microscope images of Lowther Creek thin section, including a) sharp contact between partially serpentinized dunite (LC-1B) and chromite-rich layer with olivine and secondary pyroxene (LC-1A); b) secondary Cpx filling fractures of chromite grains (SEM); c) Serpentinized contact between ...
1.. IntroductionHistorical processing of chromite ore involved mixing dry-milled ore with lime (CaO) and soda ash (Na 2 CO 3), followed by roasting at high temperatures to promote oxidation of the trivalent chromium, Cr(III), within the ore.Hexavalent chromium, Cr(VI), was then recovered as soluble sodium chromate (Na 2 CrO 4).The waste from this process, …
Several carbides can form preferentially to the metallic Cr and Fe during the reduction process of chromite ores. Cr/Fe ratio plays a role in the determination of the C content of the Fe-Cr. As Cr has higher affinity to form carbides than Fe, a higher Cr/Fe ratio means a higher C content in the Fe-Cr. Properties of Fe-Cr
Chromium processing, preparation of the ore for use in various products. Chromium (Cr) is a brilliant, hard, refractory metal that melts at 1,857 °C (3,375 °F) and boils at 2,672 °C (4,842 °F). In the pure state it is resistant to ordinary …
39% Cr 203 lump 1,49 45% Cr 2 03 concentrate 1,55 EASTERN SIDE (SOLID THICK SEAMS) ROM Product Product Chrome grade Cr/Fe 37% Cr203average 39% Cr20dumps 1,51 45% Cr 2 0 3 concentrate 1,57 Overall Yield 70% Overall Yield 85% The platinum mines waste UG-2 can be upgraded to the following typical analysis : Chrome grade Cr/Fe
In this study, we developed an eco-friendly and practical technology for effectively stabilizing and recovering Cr (VI) in COPR via combining FeSO 4 reducing agent and the …
Chromite ore processing residue (COPR) is a byproduct produced in chromite processing at high temperature (1000–1200 °C) ... From the C-Fe-Cr alloy phase diagram in Fig. 3, it could be seen that (Cr, Fe) 23 C 6 would be generated in the …
As our working hypothesis, it is contemplated that the CaCl 2-assisted DRC process involves incongruent dissolution of chromite in molten CaCl 2 followed by in situ reduction and metallization of Fe and Cr species on solid carbon particles. 8−10 There are, however, significant gaps in knowledge on the kinetics and mechanism of the DRC process ...
In this paper, the enhancement of the Cr:Fe ratio of a chromite ore was investigated by reprocessing via gravity separation and magnetic separation. A number of experiments were carried out by varying the critical …
Biogenic nano-magnetite and nano-zero valent iron treatment of alkaline Cr(VI) leachate and chromite ore processing residue . × Close Log In. Log in with Facebook Log in with Google ... XPS was also used to probe the chemistry of the uppermost 5– in shape to the reference spectra for chromite, Fe(II)Cr(III)2O4. 10 nm of the particles (Crean ...
Treatment of methyl orange with MIL-53(Fe, Al, Cr) prepared from chromite ore processing residue Volume 12, Issue 3, pp: 344-354 A Peer Reviewed referred Journal _____ Editor-In-Chief Impact Factor : 7.52 ... (Fe, Al, Cr) prepared from chromite ore processing residue Volume 12, Issue 3, pp: 344-354
The Cr/Fe ratio achieved coupled with the corresponding Cr recovery will have a significant influence on the economic feasibility of implementing a process to selectively …
Chromite ore is geologically associated with gangue materials which have lower density compared to pure chromite (FeO.Cr2O3). Gravity separation techniques are very suitable for …
Chromite Ore Processing. Low-grade ore obtained from an open cut trench at a chromite deposit near Auburn, ... Semiquantitative weight-percent data were collected for four elements, namely Cr, Fe, Al, and Mg, and they are shown as part of the figures in the form of ratios, with the most abundant element being assigned a value of 1. As can be ...
Highly reactive nano-scale biogenic magnetite (BnM), synthesized by the Fe(III)-reducing bacterium Geobacter sulfurreducens, was tested for the potential to remediate alkaline Cr(VI) contaminated waters associated with chromite ore processing residue (COPR).The performance of this biomaterial, targeting aqueous Cr(VI) removal, was compared to a …
Theoretically it contains 46.5%Cr and 25.8%Fe and their oxides. The technology of obtaining chromite is based on the principle of gravity separation and agglomeration.
1. 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 [[1], [2], [3]].When COPR undergoes weathering reactions during the deposition process, it would release highly toxic and mobile Cr(VI) due to the destabilization …
The microstructure and mechanical strength variations of chromite pellets preheated and roasted in air were studied systematically. The results show that the chromite (Fe,Mg)(Cr,Fe,Al) 2 O 4 is oxidized to magnesium-rich (Mg,Fe)(Cr,Fe,Al) 2 O 4 and ferrochromium complex oxide (Cr,Fe,Al) 2 O 3 in the preheating process over 500 °C. When …
Chromite ore processing residue (COPR), derived from the so-called high-lime processing of chromite ore, contains a significant fraction of a leachable Cr(VI) which is harmful to human being and other organisms. In recent years, the concern over environmental pollution from the waste residue containing Cr(VI) has become a major problem for the chromium …
The Soda-Ash Roasting of Chromite Ore Processing Residue for the Reclamation of Chromium M.P. ANTONY, V.D. TATHAVADKAR, C.C. CALVERT, and A. JHA ... The transmittance of the solution (Eh-pH) diagram was constructed for the Fe-Cr-H2O system was measured at 365 to 370 nm. The amount of chromium at room temperature using a thermochemical computational
1. Introduction. Hexavalent chromium (Cr(VI)) is highly mobile, severely toxic (Shahid et al., 2017) and highly carcinogenic to humans (IARC, 2010).Chromite ore processing residue (COPR) is a type of hazardous industrial waste (Mills et al., 2017; Moon et al., 2008; Wu et al., 2015) that contains a large amount of residual Cr (2000–40,000 mg/kg).). Furthermore, …
The investigations carried out by Bhima Rao et al. (1997), reveals that Cr/Fe ratio of off-grade chromite samples of Orissa, India, can be improved to 1.85–3.0 with a recovery …
Pakistan's chromite quality is considered to be amongst the best in the world due to ore size and its Cr:Fe ratio. Chromite mining and processing in Pakistan have always been active. Research shows an increase in chromite production from 100516 million tons to 121, 435 million tons in the country (Pakistan Economic Survey, 2021).
The present paper focuses on the recovery of metal values, primarily Cr and Fe, from electric arc furnace slag and chromite ore. The impact of different factors to the dissolution of slag, such as temperature, holding time, flux content and weight ratio of flux/slag was studied.
This study is promoting the concepts of value-added processing and energy conservation by eliminating the energy-intensive processes used in the conventional route of steelmaking through direct smelting of low grade chromite, nickel laterite …