Previously it was proven that dry milling of chromite ore (and other Cr containing materials) leads to Cr(VI) formation (Beukes and Guest, 2001, Glastonbury et al., 2010). Although not common, some chromite ores, chromite of the Sukinda belt of Orissa (India) might contain Cr(VI) that occurs naturally (Section 2 ) ( Godgul and Sahu, 1995 ...
Hu et al. [18] [19] [20] studied the alloying effect of special precursor made up of chromite ore, mill scale, and carbon, and pointed out that the Cr/(Cr + Fe) of the alloy precursor had ...
The effect of the prereduction level achieved at different temperatures and retention times on the Cr/Fe ratio and Cr recovery of pelletized prereduced metallurgicalgrade chromite ore (after milling and hot acid leaching, Section ) is presented in Fig. 3. Download : Download highres image (358KB) Download : Download fullsize image ...
The present study clarifies the possibility of using a mixture of chromite ore, mill scale and coke as the precursor for direct chromium alloying. This method offers an alternative process route with cheaper raw materials and fewer process steps (by avoiding the step of ferrochrome production) for producing high chromium iron or steel alloys. ...
Chromite ore can be separated in a highstrength field, despite the presence of iron impurities. The choice of method depends on several factors, primarily the type of the gangue. ... Chromite ore with a small amount of coke is ground wet in a ball mill, after which the resulting slurry is dewatered. It is mixed with a binder before being fed ...
Under the condition of ball milling speed of 600 rpm, ball milling time of 2 h, WM dosage of % of the COPR quality, and BPR of 12, the total Cr concentration of TCLP can be below 5 mg/L to meet the USEPA regulation. The total Cr(VI) content and the TCLP total Cr content of the COPR after reduction by WM ball milling are mg/kg and. Notes
This trend is also observed in the chromiterich sulfide ores of the PCMZ ore horizon, in which the PCMZ_HG ore type (36% orthopyroxene) requires the longest milling times (3140 min) and the MCHR ore (% orthopyroxene, but with 63% chromite) requires the shortest milling times (1530 min) to achieve the required grinds, which by ...
Domestic Production and Use: In 2019, the United States was expected to consume 4% of world chromite ore production in various forms of imported materials, such as chromite ore, chromium chemicals, chromium ferroalloys, chromium metal, and stainless steel. Imported chromite ore was consumed by one chemical firm to produce chromium chemicals.
Prepared by Ruth F. Schulte [(703), rschulte] CHROMIUM (Data in thousand metric tons of contained chromium unless otherwise noted) Domestic Production and Use: In 2021, the United States was expected to consume 5% of world chromite ore production in various forms of imported materials, such as chromite ore, chromium chemicals, chromium ferroalloys,
Idiomorphic chromite is the only ore mineral appearing in economic quantities. The average content of the ore is 26% Cr 2 O 3 and the Cr/Fe ratio is The Kemi chromium mine is an openpit mine with a waste rock to ore ratio of :1. At Kemi, the ore from the mine contains 11% iron and % Cr 2 O 3.
List of tables Table 1 World chromite ore reserves and production details ... Fine coke (<4 mm) is added to the ore concentrate before milling. In the milling circuit, the concentrate mixture is wet milled in an open circuit ball mill. The purpose of milling is to mill the mixture to a particular grain size distribution, ...
Hexavalent chromium in soda ash Chromite Ore Processing Residue (COPR) is harmful to the environment, it is imperative to develop a low cost, efficient, and effective treatment. Herein, a new method (ball milling+sodium sulfide) was developed for mechanochemical treatment of waterleached COPR (WCO .
Abstract. In this investigation, we optimize the grinding circuit of a typical chromite beneficiation plant in India. The runofmine ore is reduced to a particle size of less than 1 mm in the ...
Hu et al. [18][19] [20] studied the alloying effect of special precursor made up of chromite ore, mill scale, and carbon, and pointed out that the Cr/(Cr + Fe) of the alloy precursor had important ...
Under a milling speed of 500 rpm, milling time of 2 h, BPR of 9 and CPS dosage of 3%, the Cr(VI)leaching concentration significantly decreased from 115 mg L ⁻¹ to mg L ⁻¹, much lower ...
In the past, the secondary milling of UG2 ore was conducted with ball mills. However, ... smelting of PGM ores, chromite needs to be kept below about % in the feed to the. furnace [62].
PGE bearing chromite ore was ground in a HPGR/ball mill and HPGR/stirred mill. • HPGR was found to be more energy saving advanced comminution equipment. • Optimization analysis of grinding mill for low grade PGE bearing chromite ore. • About 40% of energy can be saved using stirred mill than the ball mill. •
Chromite ore processing residue (COPR), derived from the socalled highlime processing of chromite ore, contains a significant fraction of a leachable Cr(VI) which is harmful to human being and other organisms. In recent years, the concern over environmental pollution from the waste residue containing Cr(VI) has become a major problem for the chromium chemical industry.
The experimental results show that the mill scale in the alloying mixture is reduced to high active iron first and disseminated around the chromite ore particles; the reduction of chromite ore is enhanced with the addition of mill scale especially at temperatures higher than 1623 K, and the enhancing effect increased with increasing mill scale ...
The lowgrade siliceous chromite ore from Ghutrigaon, Odisha, India, containing ~ 16% Cr2O3, with Cr/Fe ratio of and ~ 55% of SiO2, does not find any use in metallurgical industry and hence considered as waste. Mineralogical investigation indicates the presence of chromite and quartz as major minerals with minor fuchsite and kaolinite. The beneficiation studies reveal that the product can ...
stringers from the heavier chromite reef before milling and flotation. In one of the older converted plants, mills as small as 8' x 8' (350 HP) are still in regular use but the more
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The experimental results show that steel scrap can be alloyed with chromium by the chromite ore in the briquettes and the Cr yield from the chromite ore increases with the increase in mill scale addition to the briquettes: the more mill scale is added to the briquettes, the lower the mass ratio of Cr to (Cr + Fe) would be, leading to a higher ...
The soda ash roasting process produces Chromite Ore Processing Residue (COPR) containing mg/kg carcinogenic hexavalent chromium (Cr(VI)) due to the industrial incomplete leaching ... Under the action of high energy ball milling, about 10% of chromite grains were liberated, and chromite grains larger than µm were reduced to ...
Traditional wet and dry Chromite Ore Processing Residue (COPR) detoxification methods consume acid for pH adjustment and produce greenhouse gasses (CO 2), yielding potential secondary is imperative to develop an environmentallyfriendly, efficient, and effective method for COPR treatment. This study reported the onestep natural pyriteassisted mechanochemical detoxification of Cr ...
Traditional wet and dry Chromite Ore Processing Residue (COPR) detoxification methods consume acid for pH adjustment and produce greenhouse gasses ... This study performed all mechanochemical experiments using a planetary ballmill apparatus (PM 100, RETSCH, Germany). Certain amounts of soda ash COPR and pyrite were mixed evenly and placed into ...
Grinding experiments were conducted in a laboratoryscale stirred mill on a lowgrade PGE bearing chromite ore. HighPressure Grinding Rolls (HPGR) product of −1 mm was used as feed material to ...
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