Beneficiating refractory clays from the Suvorovsk and Ul'yanovsk deposits

Abstract

The Suvorovsk source of refractory clays is a raw material base for the production of chamotte by the Suvorovsk mining commission. The stocks of high-quality clays from the source are gradually becoming exhausted. As a result geologists of the Tsentrgeologiya PGO are developing the nearby Ul'yanovsk deposits of clays as reserves [i].The low-grade firec!ays from the Suvorovsk and Ul'yanovsk deposits, which have the same geological age and apparently the same genesis, are characterized by high concentrations of iron minerals of secondary generation which consist mainly of pyrites. It has an extensive presence in the mineral mass in the form of coarse nodules and concretions, and also average grain and powdered material. In the strongly ferruginous varieties the pyrites content reaches 8-10%.Pyrites sharply reduce the grade and quality of the clays, and as a result the quality of the resulting chamotte. The presence of nodules and pockets of pyrites during firing causes the formation of a skin in the sintering zone of the kilns, which involves emergency stoppage of the equipment. Moreover, the firing of the clays is accompanied by the formation of sulfur dioxide, the emission of which leads to premature destruction of the plant and contamination of the atmosphere.The "Uralmekhanobr" Institute has carried out laboratory studies of the enrichability of fireclays from the above two areas. In developing a beneficiation technology provision was made for the removal of pyrites from the clays.Two samples of clays from each deposit were subjected to investigation; one of them consisted of plastic clay, and the other of argillitelike (dry) clay which is not easily broken up in water. The chemical composition of the samples is shown in Table i.Kaolinite is the main valuable rock-forming mineral in the samples.Its concentration in the samples varies from 53.8 to 89.8%. The samples of Ul'yanovsk clay also contain up to 16.5% finely dispersed clay minerals, consisting mainly of hydrargillite, hydrated micas, and boehmite. The clay minerals are concentrated in the fine fractions. The mass proportion of alumina on the calcined weight in fractions minus 56 um is 41-45%.The original samples contained from 3.8 to 25.8% fragmented material in the form of quartz, and from 1.9 to 7.9% pyrites a large part of which was located in fractions coarser than 56 ~m. Hence, the coarse-grained part of the pyrites and the quartz can be removed from the clays by the rather simple methods of mechanical dressing, e.g., by separating the material into sizes.Another part of the contaminating mineral impurities containing iron (hydroxides, hematite, magnetite, siderite), titanium (ilmenite, futile) and also alkaline and alkalineearth metals (feldspars, gypsum, barytes, carbonates, etc.) is closely associated in the original samples with finely dispersed clay minerals, and mechanical methods of beneficiation cannot be effectively used.Starting from data from a study of the substance compositions, for the beneficiation of Suvorovsk and Ul'yanovsk clays we...