Institute of Geology of Karelian Research Center of RAS (Petrozavodsk, Russia):

Ilina V. P., Senior Researcher, Candidate of Engineering Sciences, e-mail: ivp@krc.karelia.ru

Popova Т. V., Researcher

The usage of artificial raw materials, which are formed upon the mining or processing of commercial minerals in mining companies, is one of essential environmental problems and a way of utilizing dumps. Finely dispersed quartz-feldspar (fraction is 0.063 mm), is formed upon the pegmatite dressing by magnetic separation at the Chupinsk mining concentration plant. This quartz-feldspar is also an artificial type of raw material.

It should be found out whether the above fraction can be used as an additive in ceramic mass. On the basis of this, there were studied the mineral and particle size composition of the raw material and its effect on the shrinkage, water absorption and strength of ceramic tiles, which are based on polymineral hydromica clay. There were prepared experimental masses and their properties were assessed using generally accepted methods.

The optical microscopy study has shown that the quartz-feldspar raw material consists of grains with 0.015–0.03 mm in size. Grains with 0.2 mm in size are less common. Ore mineral grains (less than 5 %) and individual mica particles are present. This raw material contains more iron oxides (up to 1%), magnesium (twice as much) and alkaline oxides (up to 11%) and less aluminium oxide than the pegmatite concentrate, which is used at plants. Together with smaller grain sizes, these differences contribute to the caking of ceramics. These article researches local polymineral clay from the Voronov deposit, which is used by the Kondopoga Brick Plant, and Cambrian clay from the Chekalovskoye deposit. This clay is necessary for the production of facing building ceramics at the OJSC Nefrit-Keramika (Leningrad region). There were analyzed masses, which contain from 8 to 40 % of artificial quartz-feldspar (the rest is clay). Ceramics, which is based on Chekalovskoye clay and artificial raw material (30–35 %), has a higher strength (32.16 MPa) than the mass produced at the plant (28.35 MPа). Voronov clay-based samples, which are roasted at 1000 °C, are consistent with bricks of 100-150 brand but do not meet the State Standard`s requirements for ceramic tiles. Finely dispersed feldspar from the Chupinsk mining concentration plant can be used for the production of facing ceramic tiles, which are based on Chekalovskoe clay. The brick is based on Voronov clay.

1. Popova Т. V., Lebedeva G. А., Ilina V. P. Stroitelnye materialy - Construction Materials. 2010, No. 4, pp. 41–43.

2. Ilina V. P., Ozerova G. P., Lebedeva G. А. Steklo i keramika − Glass and ceramics. 2005, No. 3, pp. 22–23.

3. Avgustinnik А. I. Keramika (Ceramics). Leningrad : Stroyizdat, 1975, 597 p.