قائمة الطعام
The sulfuric acid leaching process is widely considered to be a cleaner technology to prepare chromium salt from natural chromite as no Cr(VI)-bearing wastes are generated or discharged.
WhatsApp: +86 18221755073
In order to improve the chromate salts cleaner production technology, a pressure leaching process for chromite ore in 50 wt% KOH solution was studied for the first time and the results were presented in this manuscript.It was found out that the chromium extraction rate increased significantly with the increase of temperature and …
WhatsApp: +86 18221755073
The L/S is a very crucial factor in the acid-leaching process of an ore or residue. 33 To figure out the influence of L/S, ... Study on mechanisms of different sulfuric acid leaching technologies of chromite. Int. J. Miner., Metall. Mater. 2017, 24, 983–990. 10.1007/s12613-017-1486-2.
WhatsApp: +86 18221755073
The sulfuric acid leaching behavior of the chromite in Zhao et al. 's study can be illustrated as shown in Figure 3, where four types …
WhatsApp: +86 18221755073
The sulfuric acid leaching kinetics of South African chromite was investigated. The negative influence of a solid product layer constituted of a silicon-rich phase and chromium-rich sulfate was eliminated by crushing the chromite and by selecting proper leaching conditions. The dimensionless change in specific surface area and the …
WhatsApp: +86 18221755073
A process flow diagram indicating the likely process steps to be utilized for pelletized pre-reduction before acid leaching to improve the Cr/Fe ratio of chromite. In this general process flow diagram ( Fig. 1 ), Process steps 1–5 are based on the currently applied pelletized chromite pre-reduction process.
WhatsApp: +86 18221755073
Batch tests were conducted to assess the potential use of ferrous sulfate and calcium polysulfide for the remediation of chromite ore processing residue (COPR). The remediation process entails addition of ferrous sulfate or calcium polysulfide to chemically reduce hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] in slurry form and pH …
WhatsApp: +86 18221755073
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 … Expand
WhatsApp: +86 18221755073
Leaching of Light Rare Earth Elements from Sichuan Bastnaesite: A Facile Process to Leach Trivalent Rare Earth Elements Selectively from Tetravalent Cerium. …
WhatsApp: +86 18221755073
The L/S is a very crucial factor in the acid-leaching process of an ore or residue. 33 To figure out the influence of L/S, a series of experiments with varying L/S …
WhatsApp: +86 18221755073
African chromite ore is processed for the extraction of chro- stoichiometric amount of sodium carbonate required for the mium as sodium chromate. The oxide constituents of South formation of sodium chromate. The mixture was roasted African chromite ore were determined by chemical analysis; isothermally in an alumina crucible in a temperature-con-
WhatsApp: +86 18221755073
The leaching kinetics study indicated that the leaching process of chromium was controlled by the surface chemical reaction between the chromite ore …
WhatsApp: +86 18221755073
Batch leaching studies on chromite ore processing residue (COPR) were performed using acids to investigate leaching of hexavalent chromium, Cr(VI), with respect to particle size, reaction time, and type of acid (HNO 3 and H 2 SO 4).Aqueous Cr(VI) is maximized at approximately 0.04 mol Cr(VI) per kg of dry COPR at pH 7.6–8.1.
WhatsApp: +86 18221755073
(b) being treated by HF acid process of the acid-soluble Cr(VI) in COPR further depends on kinetic data. 3.2 Effect of stirring rate The stirring rate (N) has little influence on the leaching efficiency of acid-soluble Cr(VI) in COPR (Fig.3). When the leaching time (t) is 60 min, Cr(VI) leaching efficiency with a stirring rate of 800 r/min is
WhatsApp: +86 18221755073
Roasted ilmenite samples were treated in a two-stage leaching process, where the first step involved water leaching and this was followed by organic acid (mixture of 0.25 M oxalic and 0.01 M ascorbic acid) leaching for 2 h, so as to obtain TiO 2-rich residue. During the acid leaching, the leachates were sampled at different times for …
WhatsApp: +86 18221755073
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 …
WhatsApp: +86 18221755073
Two most common hydrometallurgical processes are high pressure acid leaching (HPAL) and reduction roast-ammoniacal leach (Caron process). ... (nearly 8–10 times that of the ore) that is generated during chromite mining and dumped nearby has found a very little use so far. The mineralogical studies indicated that there was no …
WhatsApp: +86 18221755073
This chapter contains sections titled: Introduction Crystal Structure of Chromite Minerals Thermal Decomposition of Chromites Alkali Roasting of Chromites …
WhatsApp: +86 18221755073
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 ...
WhatsApp: +86 18221755073
The Fe content in the FeCr produced depends on the chromite spinel Cr/Fe ratio. Therefore, the selective removal of Fe from the chromite spinel using different combinations of chromite pre-oxidation, pre-reduction, and sulphuric acid leaching was investigated. The Cr/Fe ratio of the case study ores could be increased from 1.57 up to …
WhatsApp: +86 18221755073
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 as raw …
WhatsApp: +86 18221755073
Key words: leaching; kinetics; hydrofluoric acid; hexavalent chromium; chromite ore processing residue 1 Introduction Chromite ore processing residue (COPR) is a solid …
WhatsApp: +86 18221755073
during the leaching process and what impact dichromic acid has on it. It was found that the breakdown efficiency was strongly influenced by the Fe(II) concentration of the chromite and that dichromic acid acted as an oxidant and a catalyst in the leaching process. According to another study by Shi et al. (2017), the sulfuric acid leaching
WhatsApp: +86 18221755073
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 ...
WhatsApp: +86 18221755073
This chapter contains sections titled: Introduction Crystal Structure of Chromite Minerals Thermal Decomposition of Chromites Alkali Roasting of Chromites Leaching of Chromite Minerals Ch...
WhatsApp: +86 18221755073
Sulfuric acid-based leaching is a promising cleaner method to produce chromium salts, but its feasibility for treating low Fe(II)-chromite still remains to be proven. A Box–Behnken design (BBD)-based set of experiments for sulfuric acid leaching of low Fe(II)-chromite was utilized in this work for generating an experimental dataset for …
WhatsApp: +86 18221755073
A new leaching process for preparing chromium oxide from chromite was studied in this paper, using Cr(VI) extracted from the remediation treatment of chromite ore processing residue (COPR) as an oxidant. Thus, the "detoxification" of deposited COPR could be achieved and no new Cr(VI)-bearing substances would be generated in …
WhatsApp: +86 18221755073
Chromite ore processing residue (COPR) is a waste byproduct of chromate production that contains high levels of hexavalent chromium (Cr[VI]). Although the high temperature chromite process was ...
WhatsApp: +86 18221755073
In summary, the following kinetic equation can be applied to describe the pressure leaching process for chromite ore in 50 wt% KOH solution: (3) 1 - ( 1 - x) 1 / …
WhatsApp: +86 18221755073
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 …
WhatsApp: +86 18221755073حقوق النشر ©2000- 2024 شركة شنغهاي زينيث
