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treatment of chromite ore

Chromite - Mine To Metal - LinkedIn

Chromite (FeO.Cr2O3) is a member of the spinel group of minerals and has the general formula R+2O. R+32O3, where R+2 stands for a bivalent metal (mainly ferrous iron and magnesium) and R+3 ...

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Evaluation of ettringite-related swelling mechanisms for treated ...

The field and laboratory samples were treated with ferrous sulfate at a ferrous-to-Cr 6+ molar stoichiometric ratios of eight (8×) and five (5×). X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX) analyses were used to investigate the mineralogical changes upon treatment.

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Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass ...

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior By Da-Lei Zhang, Mei-Yi Zhang, Chu-Hui Zhang, Ying-Jie Sun, Xiao Sun and Xian-Zheng Yuan

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(PDF) Importance of Mineralogy in the Geoenvironmental Characterization ...

product of chromite ore processing to isolate and extract chro- COPR was widely used as a structural fill because of its physi- mium. Numerous chromite ore processing plants operated cal resemblance to a sandy soil that was considered suitable for

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Treatment of Chromite Ore-Processing Solid Waste Using a - US EPA

Laboratory batch studies indicated that ferrous iron (as ferrous sulfate) in the presence of sodium hydrosulfite was highly effective in treating the chromite ore-processing solid waste sediments, while sodium hydrosulfite alone was ineffective.

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Chemical and mineralogical characterization of chromite ore processing ...

The chromate ore process residues (COPR) polluted soil was physically separated into coarse sand, fine sand and silt to clay sized fraction and the results indicated that Cr was bearing both in COPR parent minerals and hydrated products and was dominated by Cr (III) in three size-fractions. Expand 3 Save Alert

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Alteration of chrome-to-iron ratio in chromite ore by chlorination

Although South Africa holds three quarters of the world's chromite ore reserves, the chrome-to-iron (Cr-to-Fe) ratio of the local chromite ores is relatively low (1.47 to 1.55), compared to other deposits in the world (2.6 to 3.5). ... the effect of adding only NaCI during high temperature treatment of chromite was investigated. The material ...

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How to Recover Chromite - Metallurgist & Mineral Processing Engineer

To improve chromite recovery with the Humphrey's spiral, a sample of Emma Bell ore was ball mill ground to minus 100 mesh and then processed with the spiral (table 11). This procedure improved the concentrate grade (splits 1 and 2) to 21.6 pct Cr2O3 from 17 pct for the minus 28-mesh test (see table 9), but did not decrease the grade in the ...

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Advances towards a Clean Hydrometallurgical Process for Chromite - MDPI

Because of the acute toxicity of Cr(VI)-bearing substances, the pollution problem caused by chromite process residue has become a worldwide concern. In the view of relevant studies, the technologies based on the alkali treatment cannot fundamentally resolve the pollution problem, because the oxidation of Cr(III) to Cr(VI) is unavoidable during chromite decomposition.

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Chromate adsorption from chromite ore processing residue ... - DeepDyve

Environmental contextChromate (CrO42)-containing waste is illegally dumped in some places in the state of Uttar Pradesh, north India, although CrO42 is known to be toxic and carcinogenic. Because CrO42 is leached from the landfills, this study investigated the adsorption of CrO42 by soils. The results indicated that CrO42 is highly leachable and adsorption is inhibited, which leads to ...

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Chromite Ore Processing Residue (COPR): Hazardous ... - Geosyntec

Chromite ore processing residue (COPR), which contains hexavalent chromium (Cr6+) at concentrations typically in the range of thousands of milligrams/kilograms, was deposited over a timeframe of 50 years as fill at a site referred to as SA7 in New Jersey. Significant surface heaving associated with COPR weathering-induced mineralogical ...

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Chromite Ore Processing Procedure

Pyrolysis Treatment Of Chromite Ore Processing Residue. Feb 10, 2016 The pyrolysis treatment with biomass is a promising technology for the remediation of chromite-ore-processing residue COPR. However, the mechanism of this process is still unclear. In this study, the behavior of pyrolysis reduction of CrVI by cellulose, the main component of ...

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Chromite Ore - What is the difference between ferrous and non-ferrous ...

Chromite ore Cromite is a mineral that is an iron chromium oxide. It has a chemical formula of FeCr2O4. The chemical composition of chromite is Fe2+Cr3+2O4. Chromite, when presented as an ore, or in massive form, forms as fine granular aggregates.

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Advances towards a Clean Hydrometallurgical Process for Chromite

Because of the acute toxicity of Cr(VI)-bearing substances, the pollution problem caused by chromite process residue has become a worldwide concern. In the view of relevant studies, the technologies based on the alkali treatment cannot fundamentally resolve the pollution problem, because the oxidation of Cr(III) to Cr(VI) is unavoidable during chromite decomposition.

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A new method for the treatment of chromite ore ... - ResearchGate

Chromite ore processing residue (COPR), a waste produced in high lime chromium salt production process using chromite, contains a fraction of leachable Cr(VI) which is harmful to humans and ...

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Microstructural Analyses of Cr(VI) Speciation in Chromite Ore ...

The speciation and distribution of Cr(VI) in the solid phase was investigated for two types of chromite ore processing residue (COPR) found at two deposition sites in the United States: gray-black (GB) granular and hard brown (HB) cemented COPR. COPR chemistry and mineralogy were investigated using micro-X-ray absorption spectroscopy and micro-X-ray diffraction, complemented by laboratory ...

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Chromite Ore Processing Residue (COPR): Hazardous Contaminated Soil or ...

Chromite ore processing residue (COPR), which contains hexavalent chromium (Cr 6+) at concentrations typically in the range of thousands of milligrams/kilograms, was deposited over a timeframe of 50 years as fill at a site referred to as SA7 in New Jersey.Significant surface heaving associated with COPR weathering-induced mineralogical expansion has been observed at the site over time.

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Reduction and immobilization of hexavalent chromium in chromite ore ...

In this paper, the treatment method of Cr (VI). PDF View 2 excerpts, cites background Efficient extraction of slowly-released Cr (vi) from nano-sized ion channels in Cr (vi)-ettringite from reduced chromite ore processing residue Weizhen Liu, Yao Song, +4 authors Zhang Lin Materials Science 2020

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Treatment of Hexavalent Chromium in Chromite Ore Processing Solid Waste ...

We investigated a method for delivering ferrous iron into the subsurface to enhance chemical reduction of Cr(VI) in chromite ore processing solid waste (COPSW) derived from the production of ferrochrome alloy. The COPSW is characterized by high pH (8.5−11.5) and high Cr(VI) concentrations in the solid phase (up to 550 mg kg-1) and dissolved phase (3−57 mg L-1).

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Hydrogarnet: A Host Phase for Cr(VI) in Chromite Ore Processing Residue ...

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior. ... Immobilization of chromite ore processing residue with alkali-activated blast furnace slag-based geopolymer. Ceramics International 2016, 42 (8), 9538-9549. DOI: 10.1016/j.ceramint.2016.03.033. ...

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Preparation of Superconcentrate and Chromium Powder from Chromite Ore ...

One method for activating chromite is thermal activation. Previous tests have shown that during oxidation heating of chromite in air at 900°C from chrome spinelid (FeO·Cr 2 O 3) first iron enters into the reaction

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CastTherm Chromite - HA-International

Our high-quality CastTherm Chromite product is available in multiple grades from 45 to 80 GFN. The controlled mining, multi-stage cleaning, drying, screening, and packaging into bulk bags ensure for low moisture, consistent screen distribution, and low turbidity. The benefits of CastTherm CR Chromite

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the ore chromite is - Collegedunia

The difference in physical or chemical properties of the ore and the impurities determines the procedures used to remove impurities from the ores. Methods of Concentration of Ore: Hand-picking - It was the traditional system of directly concentrating ore with the hands. With the use of a hammer, the gangue or adhering solid matrix is removed ...

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Calcium polysulfide remediation of hexavalent chromium contamination ...

Ore treatment Engineering & Materials Science 87%. Remediation Engineering & Materials Science 80%. ... AB - Past disposal of high-lime chromite ore processing residue (COPR) from a chemical works in S.E. Glasgow, UK, has led to continuing release of toxic and carcinogenic hexavalent chromium (Cr(VI)) to groundwaters which are highly ...

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Pre-oxidation treatment of Indian chromite ores: kinetics and phase ...

Oxidation treatment of chromite ores is a commercially applied process for producing mechanically strong pellets for smelting operation in submerged arc furnace. The oxidation behaviour of chromite ores which essentially determines pellet quality bears a strong relationship with ore chemistry, heat treatment, temperature and time.

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Method of treatment, stabilization and heave control for chromite ore ...

COPR is produced during the process of extracting chromium (i.e., chromite (Cr 2 O 3)) from its ore. The extraction process involves roasting the chromite ore to oxidize the chromium therein from the trivalent to the hexavalent state, then treating the oxidized chromium with soda ash (i.e., Na 2 CO 3) to form sodium chromate (Na 2 CrO 4).

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Importance of Mineralogy in the Geoenvironmental Characterization and ...

The geoenvironmental characterization of COPR at two deposition sites (New Jersey and Maryland) included geotechnical, chemical, mineralogical, and leaching analyses of three main chromite ore processing residue (COPR) types [gray-black (GB), hard brown (HB), clayey (C)].

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"An Investigation of the Geochemical Properties and Treatment of Soda A ...

Chromite Ore Processing Residue (COPR) contains high concentrations of hexavalent chromium (Cr(VI)), a human carcinogen, and is a hazardous waste that requires intensive treatment prior to disposal. China has banned the lime roasting process since 2013 and an alternative process using soda ash as roasting and complexing agent has replaced it in the larger factories. The process still produces ...

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Swelling related to ettringite crystal formation in chromite ore ...

Investigation of barium treatment of chromite ore processing residue (COPR). may be potentially accomplished via a site/cell Journal of ASTM International, 3 (6), doi: 10.1520/ flooding program or soil mixing processes. JAI13314. Darrie, R. G. (2001).

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The chemical treatment of the ore for concentration is done in the case ...

The chemical treatment of the ore for concentration is done when ore is required in very pure form . This method is used for the purification of bauxite (A l 2 O 3 an ore of aluminum ) which contains ferric oxide, titanium oxide and silica as impurities.It is also used for the treatment of gold, silver and copper.

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Chromite Ore Processing Plants | Chromite Ore Processing | Star Trace ...

Chromite Ore Processing Plant. ... been achieved in grinding circuits where coarse heavy minerals or waste material have been recovered for preferential treatment prior to over grinding. The mineral jig operated to recover free gold, sulphides, native copper, native silver, tin/tantalum, diamonds and garnet. ...

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WO2020188527A1 - Recovery of pgms and chromite from mixed pgm ... - Google

Tharisa screens the run-of-mine ore for primary gravity separation at a coarse grind size where spirals recovery of chromite is efficient. This is followed by further milling, PGM conventional...

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Chromium (Cr) Toxicity: What Is Chromium? | Environmental Medicine | ATSDR

wood treatment; smaller amounts in catalysts, copy machine toner, corrosion inhibitors, drilling muds, magnetic tapes, photographic chemicals, safety matches, and water treatment. Refractory uses of chromium include magnesite-chrome firebrick for metallurgical furnace linings and granular chromite for various other heat-resistant applications.

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Chemistry and Leaching Behavior of Chromite Ore Processing Residue from ...

Abstract 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 available in deionized water and thus the ...

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The fusion of chromite ore (FeCr2O4) with Na2CO3 in air gives a yellow ...

The fusion of chromite ore (FeCr 2O 4) with Na 2CO 3 in air gives a yellow solution upon addition of water. Subsequent treatment with H 2SO 4 produces an orange solution. The yellow and orange colours, respectively, are due to the formation of: A Na 2CrO 4 and Na 2Cr 2O 7 B Cr(OH) 3 and Na 2Cr 2O 7 C Cr 2(CO 3) 3 and Fe 2(SO 4) 3 D

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Field-Scale Evaluation of In-Situ and Ex-Situ Treatment Technologies ...

Abstract A field-scale pilot program was conducted to evaluate treatment options to reduce hexavalent chromium [Cr (VI)] concentrations and pH levels in chromite ore processing residue (COPR). The treatment performance objectives were to: (i) reduce Cr (VI) concentrations to less than 240 mg/kg; and (ii) reduce the pH of the COPR to less than 9.5.

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Treatability of chromite ore processing waste by leaching

The data obtained from the experimental studies were analysed to assess the treatability of chromite ore processing waste (COPW) by leaching and to identify the leaching strategies that enhance mass removal rates of chromium species.

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Towards holistic technology solution to chromite ore ... - SpringerLink

Jan 4, 2021Sodium chromate is obtained by treating the chromite ore with soda-lime, whereas aluminum present along with ore is precipitated as Al (OH) 3 through pH adjustments. Then, Sodium chromate (Na 2 CrO 4) upon acid treatment is converted into Sodium di chromate (Na 2 Cr 2 O 7).

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Chrome Ore Beneficiation Process | Chromite Processing - JXSC Mining

The dissociation degree of chromite monomer in the sample is 95.11%, the magnetism can be used to separate the chromite from the nonmagnetic ores. The gangue minerals, such as enstatite, tremolite, diopside, biotite, also have weak magnetism, affect the grade of magnetic concentrate. It is better to separate it by using gravity separation.

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Long-term treatment issues with chromite ore processing residue (COPR ...

Commonly used to reduce Cr 6+ to Cr 3+, ferrous sulfate heptahydrate (FeSO 4 ·7H 2 O) also provides a sulfate source for the potential formation of ettringite in COPR materials. Formation of ettringite in COPR materials can take as little as 1 h upon addition of very small amounts of sulfate (<0.1%, w/w) [8].

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