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Through controlling the phase transformation and chromium species under hydrothermal condition, the Cr(VI) was extracted fully from hazardous Cr( VI)-containing gypsum sludge, with a very high efficiency. Through controlling the phase transformation and chromium species under hydrothermal condition, the Cr(VI) was extracted fully …
The present study provides a useful set of data on the production of basic chromium sulphate from chromite ore. The percent yield of sodium chromate is …
The chromium bearing constituents of chromite ore are MgCr 2 O 4 and FeCr 2 O 4, which thermally decompose over a range of redox conditions, as identified earlier 9,20,44–46 before combining with alkali. The computed values of Gibbs free energy change over a range of temperatures between 0 °C and 1400 °C are plotted as a function …
For the extraction of chromium, fusion of chromite ore with sodium or potassium carbonate in excess of air is done. What exactly happens in this 'fusion' process? According to my textbook (class XII ... NCERT): d- and f-block element, extraction of chromite ore. According to the dictionary: To melt or fuse (ores) in order to separate the ...
The effective extracting Cr(VI) from chromite ore processing residue (COPR) is the key to achieve COPR detoxification and recovery. We developed an effective method to extract Cr(VI) from COPR via controlling the phase transformation of Cr(VI)-containing minerals. Characteristic analysis showed that Cr(VI) was mainly incorporated in the …
Extraction of Chromium from Chromite Ore Table of Contents Chromium has a wide variety of applications in the modern world. Its major uses are in stainless …
The processing of chromite ore is associated with the generation of large quantities of solid wastes containing chromium, which have been disposed of as landfill for many years. …
Tabling of the ore followed by upgrading the tabled chromite concentrate using magnetic separation to remove magnetite gave far superior results. The results and discussion of gravity-magnetic …
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 …
Chromite. Chromite is an oxide of iron and chromium = Combination of chromium, iron and oxygen. It is the only economic ore of chromium. The chromium extracted from chromite is used in chrome plating and alloying for production of corrosion resistant super alloys, nichrome, and stainless steel. Used in many other metallurgical, …
The traditional route for manufacturing chromium products is based on the extraction of chromium oxide as sodium chromate via the oxidative alkali roasting of chromite ores, in air or oxygen. The generic chemical reaction for chromite to sodium chromate may be explained by considering the oxidation of iron chromite (FeCr 2 O 4 ), …
Conclusions. A new approach using sulfuric acid leaching for chromium oxide preparation from chromite was studied in this paper, in which recovered Cr 2 O 7 2 − -bearing leachate obtained from a COPR remediation process was used as an oxidant. An Eh-pH diagram of Cr–Fe–H 2 O at 160 °C was produced and experiments using …
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 landfills in the Kanpur area of …
3.3 Recovery of PGM's from chromite roast. Solvent extraction has a wide and well defined use in separation and/or preconcentration of PGMs ... The present study provides a useful set of data on the production of basic chromium sulphate from chromite ore. The percent yield of sodium chromate is strongly dependent on the roasting time ...
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 …
DOI: 10.1016/j.jhazmat.2022.129754 Corpus ID: 251507844; Sufficient extraction of Cr from chromium ore processing residue (COPR) by selective Mg removal. @article{Zhang2022SufficientEO, title={Sufficient extraction of Cr from chromium ore processing residue (COPR) by selective Mg removal.}, author={Jing Zhang and Wenyu …
chromite, relatively hard, metallic, black oxide mineral of chromium and iron (FeCr 2 O 4) that is the chief commercial source of chromium.It is the principal member of the spinel series of chromium oxides; the other naturally occurring member is magnesiochromite, oxide of magnesium and chromium (MgCr 2 O 4).Chromite is commonly found as brittle …
Chromite is a mineral that contains chromium. It is considered a strategic mineral, which generally means that it is necessary for military and industrial use during periods of national emergency. The strategic mineral concept was created during World War I and became law just prior to World War II with the passage of the Strategic Minerals Act ...
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 …
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 …
The transition temperature changes with substitution of the iron and chromium in the chromite. Above the Curie temperature, chromite is paramagnetic. Pure chromium oxides (Cr 2 O 3 and CrO 2) are ferromagnetic. ... (2013) to reduce or eliminate problems caused by extraction of chromite ore in the Kunar area of eastern Afghanistan. 1.
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 …
By exposing chromite ore to aboveground conditions that promote weathering and oxidation, Cr-III may be converted to mobile Cr-VI. Dry milling (grinding) of chromite ore is now known to convert Cr-III to Cr-VI and efforts are required to avoid producing and spreading hexavalent chromium during mining activity.
Chromite is an oxide mineral composed of chromium, iron, and oxygen (FeCr 2 O 4 ). Chromite is the only ore mineral of chromium (Edwards, 2012). Further, in Balochistan, Pakistan, it occurs in in a rock series called the Muslim Bagh Ophiolite (Ahmad and Abbas, 1979). The major application of chromite is in production of stainless steel.
Process of extracting chromium from a chromium ore or concentrate by oxidation, which comprises suspending the chromium ore or concentrate in a bath of molten salts and introducing an oxygen-containin ... 20 parts of chromite ore were added, and the mixture was heated in an electric furnace. When the temperature reached 900°C., mechanical ...
Chromite ore processing residue. Hydrothermal treatment. Sodium silicate. Extraction and oxidation of chromium. 1. Introduction. Chromite ore processing residue …
The main raw material which is used for the extraction of chromium in China is chromite ore (Moon et al., 2009, Xu, 2011, Yu et al., 2015). The process involves conversion of insoluble Cr (III) in chromite ore to water soluble Cr(VI), thus separating chromium from other impurities (Qi, 2011).
Non-traditional metallurgical technology of comprehensive processing of Sevan chromite (with a 43–46% Cr 2 O 3 content) is developed allowing chromium extraction from local chromite in the form of more expensive chromium powder. The process of increasing the reactivity of chromite concentrate (with a Cr 2 O 3 content of …
