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 conversion rate of the chromite were observed to exhibit a ...

The optimum process conditions of leaching treatment were found to be a temperature of 176 °C, a dichromic acid/chromite mass ratio of 0.12, and a sulfuric acid concentration of 81%.

Under the optimum leaching conditions of sulfuric acid concentration of 220 g/L, leaching temperature of 110°C, leaching time of 2 h, and mass ratio of liquid to solid of 5, 91.5% of Ni was ...

Acid concentration, leaching temperature, leaching time, and solid ratio were investigated as leaching parameters and optimized. Maximum magnesium extraction yield was determined to be nearly 98% for both acids under optimum leaching parameters which leaching temperature was 85°C, solid ratio was 20wt.%, leaching time was 120 minutes, and acid ...

Meanwhile, the internal diffusion was dominant mechanism in the leaching process with an activation energy of 9.796 kJ/mol. Mohagheghi and Askari used sulfuric acid and ozone for leaching of copper from a reverberatory furnace flue dust and achieved a liquor containing 27.11 g/L Cu and 0.9 g/L Fe could be after 3 h leaching time at 0.5 initial ...

with the amount of chromite corisumed in the United states. In 1948 the total domestic production was estimzted at 3,500 tons of metallure;ical-grade chr-omtt.e-o-ChrQl.lite having a chr-omer iron ratio of 3:l--whereas, the total consUJ:11ptionwas 380,000 tons. The il'lported ors, in decreasing order of receipts, cafle from the U.S.S.R.,

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 phase gradually shrank with the duration of …

The leaching liquid used for in-situ leaching contains the leaching agent ammonium carbonate for example, or - particularly in Europe - sulfuric acid. This method can only be applied if the uranium deposit is located in porous rock, confined in impermeable rock layers.

12%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 …

The optimum process conditions of leaching treatment were found to be a temperature of 176 °C, a dichromic acid/chromite mass ratio of 0.12, and a sulfuric acid concentration of 81%. Furthermore ...

Reclamation of acid sulfate soils requires the use of materials. SWAN-gypsum (secondary waste acid neutralization gypsum), a waste from a sulfuric acid, titanium oxide refining process, contains ≈10% CaCO₃, as well as CASO₄·2 H₂O (gypsum) and Fe oxides.

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 materials to investigate the decomposition mechanism of …

The initial results of the investigation of sulfuric acid leaching of South African chromite are reported in part 1 of this study (Zhao et al., 2014). Results given in the present part showed that the extraction yield of chromium exhibited an increasing trend with temperature until 180 °C was reached. Above this temperature sulfates, including ...

The source of sulphuric acid for leaching is usually a major consideration for small plants. If the plant is located in an area where acid can be purchased at low cost, one of the greater items of capital expense can be avoided. For most plants the acid must be produced. PRODUCTION OF SULPHURIC ACID

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.

TurkishJ.Eng.Env.Sci. 30(2006),375–380. c TUB¨ ITAK˙ Hot Filtration: A Way to Enhance the Recovery of Chromite in Sulfuric Acid Leaching, with or without the Addition of Perchloric

mineral processing plant diagram process flow chromite . Chromite spinel (FeCr2O4) is the main mineral phase of the chromite ore 44 . of chromite in sulfuric acid solution a potential (E)-pH diagram for the . acid leaching solution of chrome cake using the goethite process.

Experimental Study on Sulfuric Acid Leaching Behavior of ... Utilizing Pakistan chromite as raw material, the rapid leaching of chromium and iron could be realized by the sulfuric acid leaching process on the condition of ...

In this research work the sulfuric acid leaching of a typical Turkish chromite concentrate was studied. The following was concluded considering the experimental results: 1. In the absence of perchloric acid, the maximum chromium extraction was about 58% under the conditions of 175 °C, 70 vol% H 2 SO 4 (81.4 wt.%) and 2 h.

A high aluminum concentration tends to slow the reaction. A slow leach reaction may become a very fast leach reaction when sulfuric acid is added, so care must be exercised. Once the leach reaction has finished, the addition of sulfuric acid is generally accompanied by moderate effervescence unless a significant amount of carbonate is present.

to solid ratio of 10 at 120 °C for 90 minutes; sulfuric acid leaching with30 %ammonium hydrosulfate solution and gravity concentration on centrifugal separator. The final chromite concentrate contained 59.2 % Cr 2 O 3, with a recovery of 86.8 %. Keywords: beneficiationof sludge tails, chromite, concentrate, centrifugal separator, autoclave.

A roast-leach procedure has been applied to Stillwater flotation concentrate9. The material was roasted at 1050°C to convert BMS to oxides and PGM sulphides to metals. After pre-leaching with sulphuric acid to remove soluble minerals, the PGM were leached at ambient temperature with 6M HCl in the presence of oxidant (hydrogen peroxide, chlorine,

When leaching activity has subsided, slide the cover aside slightly and slowly add about 25 mL of 1:1 sulfuric acid solution. Reclose the cover and wait for the completion of any further leaching action. Remove and rinse the cover glass, and rinse down the beaker sides. Place a glass stirring rod in the beaker and stir the contents thoroughly.

Hydrochloric acid, nitric acid and sulfuric acid are the three acids commonly used in industry. In order to figure out which acid is more conducive to separation of magnesium and chromium, the experiments were carried out under the conditions: acidity of 5 mol/L, particle size of −74 + 38 μm, liquid-solid ratio of 5:1, leaching temperature ...

In the sulfuric acid leaching process for chromite, a strong oxidizing environment is maintained by the presence of oxidant and the employment of concentrated sulfuric acid. From Fig. 1 it can be confirmed that Cr 2 (SO 4 ) 3 could precipitate from the solutions and be stable under leaching conditions (area delimited by the dotted box), while ...

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 ...

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 leaching behavior of chromite by sulfuric acid in the presence of oxidant was studied experimentally in this work, where most tests were carried o…

1) Vat Leaching: Also known as "agitated tank" leaching, the lixiviant comes into contact with the metal material in large vats or tanks, which can be stirred, enhancing the reaction kinetics. The metal containing solid, such as concentrate, ore, residue, or slag, often undergoes size reduction via crushing and grinding prior to leaching.

A new method of altered ilmenite processing has been studied. In this method, sulfuric acid is used as the reaction medium of the process, and fluoride ions are activators of the dissolving process of the rutile part of the ore raw material. The regression model of the sulfate–fluoride leaching process was developed and analyzed by using the response surface method of 23 matrix.

The leaching behavior of chromite by sulfuric add in the presence of oxidant was studied experimentally in this work, where most tests were carried out at 160 degrees 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 ...

A process is provided for heap leaching ore to recover nickel. The process is particularly effective for ores that have a tangible clay component (i.e., greater than 10 % by weight). The process includes sizing the ore (where necessary), forming pellets by contacting ore with a concentrated sulfuric acid lixiviant and agglomerating. The pellets are formed into a heap and leached with a ...

Estimated electricity requirements for the production of chromite ore products (lump, chip, and fines of chemical, metallurgical, and foundry grade chromite) from underground room and pillar mining and gravity beneficiation .....31 Table 11.

The sulfuric acid leaching processes with different temperature were systematically studied by . Chat Online; Chromite (Cr2FeO4) CrFeO4PubChem. Since silica sand is common and inexpensive it is the most commonly used mineral. Imported chromite ore was consumed by one chemical firm to produce chromium Mine dust was the prime cause of the ...

A chromite concentrate with 45.29wt% Cr 2 O 3 and a Cr:Fe mass ratio of 1.85 can be produced from these low-grade chromite ore beneficiation plant rejects. Roasting-induced phase change and its influence on phosphorus removal through acid leaching for high-phosphorus iron ore