Keywords: Environment, Corrosion, Magnesia-chromite refractory, Alkali leaching The interactions of magnesia-chromite refractory brick with Cu-Na 2 O·2SiO 2 and CuO-Na 2 O·2SiO 2 melts are studied and the chemical durability of corrosion products in water is evaluated. The corrosion tests confirm intensive infiltration of the
The leaching behavior of chromite by sulfuric acid in the presence of oxidant was studied experimentally in this work where most tests were carried out at 160 °C The results indicated that magnesium and aluminum were leached out together from the silicate phase and porous amorphous silica was produced as a product layer while the spinel .
leaching model of chromium from EAFS. This work was aimed at assessing the leachability of chromium in EAFS and exploring its leaching mecha-nism. X-ray diffraction (XRD) was used to determine the mineralogical composition of EAFS. Scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS) microscope system was used to observe the
Dec 30, 2005· Therefore, knowledge of migration behavior and leaching rates of chromium through waste materials are of primary concern for environmentally sound management of hazardous wastes. Leaching rates of total Cr and Cr(VI) were studied experimentally using laboratory columns packed with COPR material produced by a sodium chromite plant.
(2017). Heterotrophic leaching of metals from Indian chromite mining overburden. International Journal of Mining, Reclamation and Environment: Vol. 31, No. 1, pp. 66-77.
Dec 11, 2016· The extraction of chromate from chromite via the sulfuric acid leaching process has strong potential for practical use because it is a simple and environmentally friendly process. This paper aims to study the sulfuric acid leaching process using chromite as a raw material via either microwave irradiation or in the presence of an oxidizing agent. The results show that the main phases in ...
Apr 26, 2011· Leaching 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 COPR into the leachate. Particle ...
The chromite ore is heated with a mixture of calcium carbonate and sodium carbonate in the presence of air. The chromium is oxidized to the hexavalent form, while the iron forms the stable Fe 2 O 3 . The subsequent leaching at higher elevated temperatures dissolves the …
Jun 01, 2014· The leaching process was controlled by inner diffusion, and the activation energy was calculated to be 55.6 kJ/mol in the temperature range of 280–370 °C. Download : Download full-size image; Fig. 10. Arrhenius plot for the leaching process of Philippine chromite ore.
Chromite is a crystalline mineral composed primarily of iron(II) oxide and chromium(III) oxide compounds. It can be represented by the chemical formula of FeCr 2 O 4.It is an oxide mineral belonging to the spinel group.The element magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite (MgCr 2 O 4). A substitution of the element aluminium can ...
Development of an empirical model of a nickeliferous chromite leaching system by means of genetic programming. Greeff D.J.; Aldrich C. (1998) Article. By making use of genetic programming, empirical models for metallurgical processes can be evolved that are more cost-effective than models determined by means of classical statistical techniques ...
Aug 01, 2017· To study the system further leaching tests were performed using the chromite. In these tests 10 g of -325 mesh chromite (aged in air either 2 weeks or 3 months) were placed in 1 liter of 0.1N HCl. In figure 7 are shown concentrations of Fe, Ca, Mg and Cr as a function of leaching …
The only important ore mineral of chromium is the chromite – FeO.Cr 2O3 (68% Cr 2O3, 32% FeO) which crystallizes in the isometric system. The hardness value is 5.5 on Mohr scale and its specific gravity is 4.6. In colour, it is iron – black to brownish –black. Pure chromite with composition FeCr 2O4 is rare because magnesium usually ...
Apr 25, 2007· This underscores the dramatic impact that the aluminum leaching can have on the entire system. A comprehensive view of leaching and the downstream impacts must therefore be considered prior to implementation. Many laboratory scale tests for aluminum and chromium dissolution have been run on Hanford wastes, with samples from 46 tanks tested.
General Chromite Information : Chemical Formula: Fe++Cr2O4 : Composition: Molecular Weight = 223.84 gm Chromium 46.46 % Cr 67.90 % Cr 2 O 3: Iron 24.95 % Fe 32.10 % FeO: Oxygen 28.59 % O: 100.00 % 100.00 % = TOTAL OXIDE
From Roasting Of Nickel Ore To Leaching. Leaching Processleaching Process For Chromite. Hot products used for 2 step leaching and roasting process chromite chromite is an iron chromium oxide in metallurgical processes tank leaching is a from roasting of nickel ore to leaching mar 18, 2013 recovery of valuable metals from a lowgrade nickel ore using an ammonium sulfate roastingleaching process ...
MODELING CHROMIUM LEACHING FROM CHROMITE ORE PROCESSING WASTE A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES OF THE MIDDLE EAST TECHNICAL UNIVERSITY BY ... system of two first order differential equations was able to capture the essential characteristics of leaching behavior of COPW material. In addition, the …
The efficacious treatment and resource utilization of the chromite ore processing residue (COPR) is important for chromate salt production. In this study, the leaching of valuable elements from the waste COPR was investigated. X-ray diffraction (XRD) analysis showed that the COPR mainly contained periclase (MgCr2O4), magnesiochromite ((Fe, Mg) (Cr, Fe)2O4), Fe (Cr, Al)2O4, and MgFeAlO4.
Jul 20, 2017· The average grade of the metallurgical chromite ore was 43.4 pct Cr2O3, with 52 pct of the ore having a chromium-to-iron ratio of 3:1 or over, 17.6 pct having a ratio between 2:1 and 3:1, and 30.4 pct having a ratio less than 2:1. Chemical-grade chromite ore generally ranged from 40 to 46 pct Cr2O3 with a chromium-to-iron ratio of 1.5:1 to 2:1.
Jun 17, 2021· Sodium hydroxide leaching [13, 14] and the consequent hydrometallurgical extraction of chromate from the lean chromite ores have also been reported. Chromium extraction from the unreacted material that remains after soda-ash roasting of high grade chromite ores, are also reported [ 9 ].
chromium, the leaching conditions of a domestic ore (48.79 Cr203 and 12.69 FeO) in sulfuric acid containing small amount of (NH4)2Cr2O7 were studied. Sample : The chromite ore from Numaoshi in Hokkaido was crushed by a Engelbach crusher, and sieved by a stuandare Tyler sieve.
Extraction of metals (Ni, Co) from chromite overburden of Sukinda mines of Orissa, India, with the culture filtrate of Aspergillus niger was studied. Results showed that the amounts of metals leached varied directly with reaction temperature and period of fermentation. The culture filtrate was analy …
Aug 19, 2018· If lime is added to the system in the 1.5 to 2.0 CaO:SiO2 region, two phase boundaries are crossed near the 2.0 ratio and Cr2O3 is converted to CaO·Cr2O3 (calcium chromite). Oxidation of CaO·Cr2O3 CaO·Cr2O3 not greatly soluble in acid, but in the presence of air and CaO at elevated temperatures it is readily oxidized to acid-soluble CaCrO4 ...
leaching after mixing chromite, sodium carbonate (Na 2 CO 3), and dolomite and calcining at high temperatures.15 This residue contains a large amount of calcium and a small amount of iron, aluminum, chromium, etc. However, the COPR from the non-calcium-roasting process always contains a higher
1. Write the equation for the extraction of silver by leaching with sodium cyanide and show that the leaching process is a redox reaction. XII U1 Metallurgy - Jerald.indd 5 4/2/2019 11:26:56 AM Untouchability is Inhuman and a Crime
Jul 03, 2021· 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).
Jul 10, 2014· Fig. 3 shows SEM images of the original surface of the chromite lump and the surface after leaching at 190 °C for 90 min.The results indicated that many sulfate particles smaller than 5 μm had been precipitated in the sample, while there were hardly any such particles in the samples leached below 180 °C.This phenomenon can be attributed to the significant effect of temperature on the ...
Rakshit et al.: Assessment of efficacy of clayey soil as liner material in retarding sub-surface leaching of chromium 535 and the saturated hydraulic conductivity of the soil was K s = 6.37×10–8 cm/s which is very low. Hence, the studied soil can be considered as a promising candidate for using as