Chemical beneficiation of chromite ore to improve the chromium …
1. Introduction. The international market for chromite ore (synthetic formula – FeO.Cr 2 O 3), the only commercially viable source of new chromium (Cr) units, is predominantly driven by the global demand for ferrochrome (FeCr).Secondary FeCr markets comprise of the Cr chemicals-, abrasives-, refractories-, and foundry sand industries and …
Sufficient extraction of Cr from chromium ore
Chromium ore processing residue (COPR) is a hazardous waste generated during the production of chromate. Currently, approximately 10% of Cr 2 O 3 cannot be extracted after chromite sodium roasting and remains in COPR, wasting valuable Cr resources. In this study, Mg was selectively removed by using (NH 4) 2 SO 4 roasting in …
BENEFICIATION OF MAGNETITE RICH CHROMITE ORE …
Chromite ores contain a variety of gangue. minerals such as serpentines and olivine. Therefore, concentration of chromite is. required. The most commonly used. beneficiation methods for chromite ...
Mineral processing: leaching process of chromium and
The current strategy reports the recovery of precious group metals (PGMs) from Na2CO3 roast of Saudi Arabian ophiolitic chromite ore at 1160 °C under atmospheric O2. The influence of roasting temperature (960–1200 °C) and leaching agents (H2O, HCl, H2SO4) and their concentrations on the recovery of PGMs was studied. Chromite roast …
A cleaner method for preparation of chromium oxide from chromite
A new leaching process for preparing chromium oxide from chromite was studied for this paper, using Cr (VI) extracted from the remediation treatment of chromite ore processing residue (COPR) as an ...
Mineralogical Analysis of a Chrome Ore from South Africa
Table 2 and Fig. 2 show that chromite particles are in the crystal form, whose the monomer dissociation is 92.66%, the remaining part of chromite particles are associated with other minerals. Figure 3 shows that particle shapes are very angular after grinding. Some chromite particles are wrapped by chlorite, part of the chlorite exists …
Efficient immobilization and utilization of chromite ore …
Chromium exists in the nature chromite ore, which is a magnetic composite spinel phase containing FeCr 2 O 4 and Fe 3 O 4 (Arai et al., 2020; Burkhard, 1993). As the extremely stable chromium-bearing mineral phase in nature, the formation of chromite requires hundreds of years of hydrothermal mineralization on the earth ( Arai et …
Modeling of Knelson Concentrator Operating Parameters by …
Abstract In this study, modeling and optimization tests were conducted on enrichment of chromite ore by Knelson concentrator. For this purpose, the three-level Box–Behnken experimental design method was applied. The analysis of variance (ANOVA) was used at 95% confidence interval to test the significance of independent variables …
Chromite mining pollution, environmental impact, toxicity …
Chromite mining activities are indispensable for production of goods and services. Sukinda is a major mining site of Odisha, India, polluted by chromium, which is highly toxic in its hexavalent form. The Sukinda valley is a rich source of chromites, amounting to almost 95% of Cr available in India, and is the fourth most polluted site …
Basics of Geochemistry and Mineralogy of Chromium
Chromite (Fe,Mg)(Cr,Al) 2 O 4 containing up to ~55 wt% Cr 2 O 3 is the major ore mineral of chromium and is an accessory mineral in many ultramafic rocks. Chromitite forms Cr-rich ore bodies, in which the content of chromite exceeds 30 vol.%; this results in local increase in the chromium concentration in the Earth's mantle.
In chromite ore, the oxidation number of iron and chromium …
Concentration of Ore. Question. In chromite ore, the oxidation number of iron and chromium reapectively, are: + 3, + 2 + 3, + 6 + 2, + 6; ... In chromite ore, the oxidation number of iron, and chromium are respectively. View Solution. Q4.
Acid leaching of chromite
The reaction between chromite and sulphuric acid was studied in the temperature range 140- 210oc. The leaching time varied from 2 to 6 hours and the sulphuric acid concentration from 60 to 90 percent by weight. A solid liquid ratio of 1:25 and particle size of -90 +75 I-tm was kept constant in all experiments.
Characterisation of South African Chromite Middle …
with Fe, Si, Mg, and Al elements. Most dominant phases are that of chromite and magnetite in all the samples. The amount of chromium element by % weight in all seams ranged between 20% to 28 % as obtained from the EDS. The particle size of the grains in the ore ranged between 20 to 420µm, with majority being between 150 and 200µm.
Electrokinetic removal of chromium from chromite ore
Chromite ore processing residue (COPR) contaminates farmland and groundwater around storage fields through the release of chromium leachate. Graphite particle-supported nanoscale zero-valent iron (GP-nZVI) synthesized by an impregnation-reduction pathway was used as a microelectrode in a three-dimensional electrochemical …
Remediation of hexavalent chromium contamination in chromite ore …
1. Introduction. Chromite ore processing residues (COPR) are hazardous industrial wastes which have been disposed in surface soils at many commercial and industrial sites in the USA, UK, China, Japan, India and in many other countries (Dhal et al., 2013).One of the biggest threats of COPR to the environment is the release of …
Distribution characteristics of minerals and elements in chromite ore …
In this paper, environmental scanning electron microscopy (ESEM) is applied to characterizing the mineral and element distribution of chromite ore processing residue (COPR). The test results show that Cr-bearing brownmillerite occurs in the rim of COPR particle, while hydroandradite with Cr(VI) in its structure presents inside the COPR …
Modeling and optimization of spiral concentrator for …
1. Introduction. Chromite ore is the main source of chromium metal, chemical and refractory industry. Based on certain physical and chemical properties, the ore is categorized for different user industries [1].During the beneficiation of chromite ore, about 50% of the total feed is discarded into tailing which consist of huge quantity of the …
Environmental status of groundwater affected by chromite ore …
Chromite ore processing residue (COPR) is generated by the roasting of chromite ores for the extraction of chromium. Leaching of carcinogenic hexavalent chromium (Cr(VI)) from COPR dumpsites and contamination of groundwater is a key environmental risk. The objective of the study was to evaluate Cr(VI) contamination in …
Decomposition of chromite ore by oxygen in molten …
Effect of chromite ore particle size on chromium extraction was studied at a temperature of 370 °C, liquid-to-ore ratio of 4:1, mass content of NaNO 3 of 25% in liquid, and oxygen flow rate of 1 L/min. The chromite ore with particle size of 58–74 μm, 45–58 μm, and 25–45 μm was used, and the results are presented in Fig. 9. It is ...
Fate and Transport of Chromium Contaminant in Environment
There are two types of physical process by which chromium are carried in the fluids, bulk fluid movement from one site to another (advection), and random mixing within the fluids (diffusion and dispersion) (Zhang et al. 2016). 3.1 Advection. Advection refers to the transport of matter by the motion of a fluid (Fig. 12.1).The water will flow …
Research on the environmental stability performance of …
performance of chromite ore processing residue solidified products† Ming Xia, *abc Pengyue Su,a Hao Wang,a Huicheng Lu,a Haiyu Chen,a Shujie Zhao*d and Dongwei Li*e Chromite ore processing residue (COPR) is a hazardous waste because of leachable chromium, especially Cr(VI). Therefore, ascorbic acid (AA) and blast furnace slag (BFS) …
What is chromite (chrome) ore and where is it …
Chromium is extracted from chromite ore. Chromite is an oxide mineral composed of chromium, iron, and oxygen (FeCr 2 O 4).. Companies in South Africa supply chrome ore from the lower and middle group …
Leaching Mechanisms of Cr(VI) from Chromite Ore …
The pH of the leaching solutions was adjusted to cover a wide range between 1 and 12.5. The concentration levels for total chromium (Cr) and Cr(VI) in the leaching solutions were virtually identical for pH values >5. For pH values <5, the concentration of total Cr exceeded that of Cr(VI) with the difference between the two attributed to Cr(III).
(PDF) Characterization of Chromite Ore …
The COPR samples from nine sites can be divided into two groups, one with high concentration of iron oxide (20-33%) in a form of spinel having magnetic property, and another with low concentration ...
Mineralogy and pre-concentration of the chromite
The areas of focus for this chapter are ore body knowledge (gold mineralogy), comminution, pre-concentration and ore beneficiation, cyanidation, oxidative pretreatment, heap leaching and ...
Effects of particle size and acid addition on the remediation …
Chromite ore processing residue (COPR) is the solid residue left after the extraction of hexavalent chromium [Cr(VI)] from chromite ore using the high lime process. ... The total Cr concentrations in COPR are up to 5%, including hexavalent chromium [Cr(VI)] concentration up to 2% on dry weight basis [9], [10], [11].
Evaluation of chromium bioaccessibility in chromite ore processing
1. Introduction. Chromite ore processing residue (COPR) is a solid waste generated during the production of hexavalent chromium (Cr(VI)) by alkaline high-temperature roasting and leaching [1].Millions of tons of COPR have been deposited in urban areas around the world including UK, USA, India, Pakistan and China [2], [3], …
Stratiform Chromite Deposit Model
potential of chromite deposits depends mainly on the thickness, continuity, and grade of ore. The most important uses of chromium are in stainless steels, nonferrous alloys, and chromium plating. Chemical-grade chromium is widely used in chemicals and pigments. Chromium also is an important component in refractories.
A cleaner method for preparation of chromium oxide from chromite ore
The chromium (Cr) leaching efficiency reaches 99% with ore particle size of 40 to 50 μm, NaOH-to-ore mass ratio of 4:1, NaOH concentration of 60 wt%, O2 partial pressure of 3.2 MPa, and reaction ...
Remediation of hexavalent chromium contamination in chromite ore …
Large 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 (Na 2 S 2 O 4) was used to reduce Cr(VI) to Cr(III) in COPR containing …