Dry Beneficiation of Kyanite Ores
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Vol. 54, No. 3, September, 2013
DRY BENEFICIATION OF KYANITE ORES A. I. Urvantsev1 and I. D. Kashcheev2 Translated from Novye Ogneupory, No. 6, pp. 10 – 12, June, 2013.
Original article submitted February 4, 2013. The beneficiation of kyanite ores by a new dry technology is studied. Compared to the flotation method, the method reduces energy consumption from 300 – 400 to 15 – 25 kWh/ton. Dry electroseparation has made it possible to obtain concentrates with an Al2O3 content of 59 – 60% while also producing pure quartz (“tailings”). Keywords: kyanite, beneficiation, energy efficiency, electroseparation.
Metastable minerals of the sillimanite group (andalusite, sillimanite, and kyanite), having the general formula Al2O3·SiO2 and theoretical contents of Al2O3 and SiO2 respectively equal to 62.9 and 37.1 mass %, are widely used as an alumosilicate raw material in the refractories industry. The volumes of andalusite, sillimanite, and kyanite increase 4, 8, and 16 – 18% during roasting. Thus, the first two minerals are used directly in refractories production, while kyanite needs to undergo a preliminary roasting operation. A large percentage of the deposits of metastable minerals in the world are mined by opencast method. The average content of the useful component in the ores is 10 – 15% and the reserves total 1 million tons. The methods of beneficiation that are used include crushing, classification, separation based on density, and flotation (which is the most effective method of obtaining high-quality concentrates). The commercial product contains 56 – 59% Al2O3, 38 – 40% SiO2, and less than 3% impurities. The main producers of concentrates of minerals in the sillimanite group are South Africa, the U. S., India, France, and Brazil. In Russia, most of the kyanite reserves are located in the Urals and Karelia. The projected reserves of kyanite in the Karabash deposit are estimated to be 10 million tons and have a mineral content ~25%. The total volume of the ore is approximately 40 million tons. By its very nature, wet beneficiation invariably entails the consumption of large quantities of water, and subsequent washing of the converter requires the use of heat to remove the moisture. The use of water and fuel has an unavoidable negative impact on the economics of the production process. 1 2
Thus, the elimination of wet beneficiation and its replacement by dry beneficiation is an important problem in the processing of kyanite concentrate. The main method employed in Russia for the beneficiation of kyanite ores is based on flotation and entails the use of flotation reagents to remove sulfides in the initial part of the process and subsequent flotation of kyanite from sulfide flotation tailings. The reagents used in the sulfide flotation are xanthogenate and aerofoil, while the reagent in the kyanite flotation is sulfonate in an acid medium (in the presence of sulfuric acid). The number of operations performed in sulfide flotation reaches six [1, pp. 203 – 207]. The flotation operation is complicated by the presence
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