Beneficiation of secondary Novoselitsy kaolin

Abstract

The secondary kaolins of the Novoselitsy deposits are used mainly for the production of dense chamotte brick for the high-temperature part of blast-furnace stacks [I, 2]. The special-grade Novoselitsy kaolin is the best raw material of Soviet origin for the production of the high-quality refractories of porosity below 12% for the 5000-m ~ blast furnace at the Krivoi Rog Metallurgical Plant [3,4].The high nonhomogeneity of the grain size, mineral, and chemical compositions of the Novoselitsy kaolins are the main source of the technological difficulties encountered in the roasting of the kaolin to chamotte and the manufacture of high-performance refractory products. Even a small amount of quartz sand in the kaolin increases the water absorption and porosity of the chamotte [5, 6]. Among the other impurities which produce an adverse affect on the quality of the chamotte are sulfur compounds of iron which during roasting in a rotary kiln do not dissociate completely, the result being that the refractory product undergoes bloating during firing; and titanium compounds which form a significant proportion of the melt and reduce the service durability of the product [7, p. 210].The most critical refractories are produced from the special grade KN--O of Novoselitsy kaolin. The yield of this grade in the extraction operations is falling constantly so that the Ural Institute of Beneficiation and the Mechanical Processing of Minerals initiated research in a benefieiation technology for low-grade Novoselitsy kaolin with a view to obtaining a concentrate finer than 0.056 mm containing at least 43% A1203 and not over 1.3% Fe203 (on the calcined substance).The sample of kaolin of grade KN-2 conformed to TU 14-8-160--75 and contained 34.48% A1203 (in terms of the dry substance), 49.18% SiO2, 1.30% Fe20~, 1.46% TiO2, 0.12% K~O + Na20, 0.20% CaO, and 0.06% MgO; calcination loss 12.97%. The mineral composition of the sample was as follows: 76.5% kaolinite, 9.5% quartz, and 11% hydromica with the accessory minerals marcasite (0.7%), rutile (0.8%), iron hydroxides (0.2%), and a carbonlike substance (0.7%).A fractlonwise chemical analysis of the Novoselitsy kaolin (Table i) showed that in terms of the clay content the fractions finer than 2 ~ are the purest:. The fractions coarser than 2 ~ contain more Fe20~ and free quartz; the high iron oxide content is attributable to the presence of marcasite.An analysis of the separation curves (Fig. i) suggested that Novoselltsy kaolin can be beneficiated by separating it into grain sizes. For a beneficiated kaolin of grade KN-O conraining at least 43% Ala03 for the limiting grain size is 100-200 ~. A smaller grain size of separation offers no advantages because it gives a significantly lower yield of concentrate and less extracted A1203 although the AI~03 content is then slightly higher and the Fe20~ content lower.An investigation was carried out of the wet gravitational beneficia~ion of the kaolin in high-density suspensions [8]. The separation of high-concentration clay suspensions into graln-...

Beneficiating refractory clays from the Suvorovsk and Ul'yanovsk deposits

“…Starting from data from a study of the substance compositions, for the beneficiation of Suvorovsk and Ul'yanovsk clays we used a separation technique in highly concentratred suspensions [2,3], which includes disintegration of the raw materials to obtain sand--clay suspensions possessing high mobility, and subsequent separation of the material into sizes on screens, mechanical classifiers, and in hydrocyelones.…”