آخرین محصولات

Leaching of Valuable Elements from the Waste Chromite Ore …

Chromite ore processing residue (COPR) is a hazardous waste due to the presence of highly mobile Cr (VI). In this paper, the redn./immobilization of COPR using composite …

Sulfuric acid leaching of South African chromite. Part 1: …

The leaching behavior of both the silicate and the spinel phases was investigated in the current study. Before the test, a chromite lump was polished by polisher and several types of abrasive paper to get two smooth flat surfaces. 100 mL 80 wt.% sulfuric acid and 1 g oxidant were mixed in a glass beaker on an automatic temperature …

A clean and efficient leaching process for chromite ore

To establish a cleaner production technology of chromium salt, the pressurized leaching process of chromite ore in 60 wt.% NaOH solution, subsequent separation of a chromium salt from the leached ...

Advances towards a Clean Hydrometallurgical …

First, the chromite was decomposed and leached by sulfuric acid solution in the presence of an oxidant. Then, iron was hydrothermally removed from the acid solution as the precipitate of …

(PDF) Leaching of Valuable Elements from the Waste Chromite …

The major process factors and conditions that were employed in these studies involved acid concentration (40-85% v/v), temperature (140-210°C), leaching time (1-6 hr.), solid to liquid ratio (1: ...

A clean and efficient leaching process for chromite ore

At present, the high-cost leaching method is the main method to recycle the chromium in HCFS (Chen et al., 2014; Spooren et al., 2016).

Chromium Remediation or Release? Effect of Iron (II) …

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 ...

Leaching of Valuable Elements from the Waste Chromite Ore …

The COPR from the calcium roasting process is the residue of water leaching after mixing chromite, sodium carbonate (Na 2 CO 3 ), and dolomite and …

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 Leaching Characteristics of Chromite ore Processing …

This paper focused on the treatment of vanadium–chromium reducing residue with a two-step alkaline leaching process: electro-oxidation leaching of vanadium and H2O2 as well as oxidation leaching ...

Direct leach approaches to Platinum Group Metal (PGM) …

The major portion of platinum and palladium produced today from primary sources originates from the Bushveld Igneous Complex in South Africa. The most important reefs mined are the Merensky, Upper Group Two (UG-2) and Platreef (Cramer, 2001).Ore grades range from 3 to 8 g/t PGM, with associated nickel and copper in the 0.1–0.2% …

Chemistry and Leaching Behavior of Chromite Ore …

DOI: 10.1089/ees.2018.0047 Corpus ID: 239831715; Chemistry and Leaching Behavior of Chromite Ore Processing Residue from the Soda Ash Process @article{Du2018ChemistryAL, title={Chemistry and Leaching Behavior of Chromite Ore Processing Residue from the Soda Ash Process}, author={Yaguang Du and Maria …

CFD Simulation of a New Dynamic-Static Stirred …

In the liquid phase oxidation leaching process of chromite salt, a new dynamic-static combined stirred mode is proposed. That is, a static cylindrical baffle is fixedly installed at a certain ...

Remediation of chromite ore processing residue by pyrolysis process

Thermo-gravimetry (TG) and derivative thermo-gravimetry (DTG) curves for the sewage sludge are presented in Fig. 1.Major and minor peaks in the DTG curve (reaction rates) were observed at around 224–345. °C (40.9% reduction) and 526–681 °C (24.7% reduction), respectively.. The weight loss as exhibited by the two peaks could be …

Immobilization of chromium ore processing residue by alkali …

Chromium ore processing residue (COPR) is classified as hazardous solid waste because of the leachable Cr(VI). Cementitious materials are often used to solidify and stabilize heavy metals. However, most of them focus on the leaching concentration of particles after solidification and stabilization and lack research on leaching …

Valorization From Waste: Combined Reduction of Chromite …

Chromite ore processing tailings and low-grade manganese ores are typically considered waste due to their limited or negligible utility, leading to environmental and storage concerns. Researchers globally have explored various methods to utilize or upgrade these wastes, particularly because dumping chromite ore has been linked to …

Long-Term Leaching Behavior of Chromite Ore Processing …

Amorphous compounds may be a vital sink related to the release of the Cr from COPR, which can explain the higher release of Cr from HB COPR (33.2% and 22.5% cumulative leaching in groundwater and rainwater, respectively) than that from GB COPR (21.3% and 19.8% cumulative leaching in groundwater and rainwater, respectively).

Leaching Process

Leaching process describes the release of organic and inorganic contaminants or radionuclides from a solid phase into a water phase when influenced by processes such as desorption, complexation, and mineral dissolution. The Leaching process is a universal process – Water will leach the components of any material it comes in contact with, …

Comparative study of alkali roasting and leaching of chromite …

For the last 40 years, global economic growth has resulted in a rapid increase in the demand for a range of metals and metal oxides for high technology applications, including titanium dioxide (TiO 2) and chromium oxide (Cr 2 O 3) (Brown et al., 2015).This has led to a rise in the consumption of their mineral oxides, TiO 2 and Cr 2 O 3, derived …

Leaching mechanisms of Cr (VI) from chromite ore …

Batch leaching tests, qualitative and quantitative x-ray powder diffraction (XRPD) analyses, and geochemical modeling were used to investigate the leaching mechanisms of Cr(VI) from chromite ore processing residue (COPR) samples obtained from an urban area in Hudson County, New Jersey. The pH of the …

Acid leaching of chromite

Keywords Chromite, leaching INTRODUCTION The conventional method for the production of chromium chemicals involves the roasting of chromite with soda ash at high temperatures in the presence of oxygen to form sodium chromate(Na2CrO4) [1]. ... The high activation energy, Ea confirms that the leach process is chemically controlled. …

Chromium Remediation or Release? Effect of Iron (II) Sulfate …

Chromite ore processing residue (COPR), derived from the so-called high lime processing of chromite ore, contains high levels of Cr(III) and Cr(VI) and has a pH between 11 and 12. Ferrous sulfate, which is used for remediation of Cr(VI) contamination in wastewater and soils via reduction to Cr(III) and subsequent precipitation of iron(III)/chromium(III) …

Leaching Mechanisms of Cr(VI) from Chromite Ore …

Batch leaching tests, qualitative and quantitative x-ray powder diffraction (XRPD) analyses, and geochemical modeling were used to investigate the leaching mechanisms of Cr(VI) from chromite ore processing residue (COPR) samples obtained from an urban area in Hudson County, New Jersey.

Free Full-Text | (Bio)leaching Behavior of Chromite Tailings

Chromite beneficiation operations in Sukinda valley (India) produce large amounts of tailings, which are stored in open air. In this study, bioleaching experiments were carried out in batch reactors with Acidithiobacillus thiooxidans or Pseudomonas putida in order to determine the potential leachability of metals contained in these tailings due …

Thermodynamics of chromite ore oxidative roasting process

To explicate the thermodynamics of the chromite ore lime-free roasting process, the thermodynamics of reactions involved in this process was calculated and the phrases of sinter with different roasting times were studied. The thermodynamics calculation shows that all the standard Gibbs free energy changes of the reactions to form …

Leaching | Definition, Concept & Process

The leaching process can be explained using tea or instant coffee as an example. When making tea, hot water usually comes in contact with a teabag, and the beverage changes from hot water to tea.

Identification and geochemical modeling of processes controlling

Chromite ore processing residue (COPR) contains very high levels of chromium as Cr(III) and Cr(VI) and has a pH of ∼11.5 to 12. Millions of tonnes of COPR have in the past been deposited in ...

Remediation of lime-free roasting chromite ore processing residue …

Remediation process and utilization treatment of chromite ore processing residue (COPR) is an environmental issue which is not solved completely. ... After water leaching, the Cr (VI) content reduced to 312 mg/kg. The removal rate was 72.3%. Pyrolysis parameters, including heating temperature, sawdust ratio, heating time, were …

Pressure oxidative leaching of Indian chromite ore in …

A novel process for leaching chromite ore has been proposed. Compared to the traditional alkaline roasting process, the new hydrometallurgical process lowers effectively the reaction temperature and enhances the leaching efficiency through pressure oxidative leaching with pure oxygen (O 2) in concentrated sodium hydroxide …

Long-Term Leaching Behavior of Chromite Ore Processing …

Leaching characteristics of chromium ore processing residue (COPR) for the long term (simulating a 20-year leaching scenario) were investigated using …

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