Irkutsk National Research State Technical University, Irkutsk, Russia:

A. I. Nizhegorodov, Head of a Chair, Doctor of Engineering Sciences, nastromo_irkutsk@mail.ru

The technological aspects of production of expanded vermiculite and thermally activated sungulite from dumped overburden at Kovdor phlogopite–vermiculite deposit in the Murmansk Region are discussed in the article. The mentioned objective is successfully reached using a power and processing unit designed for thermal activation of sungulite and expansion of vermiculite in the mode of thermal shock at a heating rate of 150–200 °С/s. The feature of the power and processing unit is that the thermal energy recuperated by a treated material is used for the implementation of the specified processes as the material passes auxiliary non-electrified modules. Efficiency of the auxiliary modules has experimentally been proved—their application allows power consumption to be reduced by 25 %. After thermal treatment in the power and processing unit, sungulite loses up to 18 % in weight while the accompanying olivine–pyroxene phase remains unchanged. Therefore, after air separation of vermiculite, the residue is subjected to vibro-segregation with respect to density until ultimate removal. As a result, sungulite concentrate with the target product content of 85–90 % and expanded vermiculite are produced. The final stage is ageing of sungulite under the temperature of 700–750 °С for 20–25 min. By estimates, from 1000 kg of vermiculite–sungulite waste, it is possible to produce round 100 kg of sungulite and up to 1.5 m3 of expanded vermiculite, as well as 420 kg of mason’s sand.

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