The article presents the first data on biotite-hornblende lamprophyres discovered at the Peshchernoe gold deposit. We consider the geological position of lamprophyre dikes in the deposit structure and the relationship of these rocks with tectonically weakened and mineralized zones. The data on the structural position of mineralized zones, faults, dike bodies, metasomatic halos, and host volcanogenic-sedimentary rocks confirm the tectonic nature of the Peshchernoe deposit alteration system. Lamprophyre dikes are pre-ore, as evidenced by the superimposed metasomatic mineral associations. We assume that dikes of andesitic rocks, lamprophyres, and subsequently hydrothermal fluids, including ore-bearing ones, were intruded along the fault zone of northeastern strike at different geological times. The description of mineralogical and chemical transformations of lamprophyres, which occurred as a result of alteration, is given. Two stages of metasomatism are distinguished: carbon dioxide (beresitization-listvenitization) and subsequent alkaline (sodic metasomatism). During carbon dioxide metasomatism, dark-coloured minerals are replaced by chlorite, albitization and sericitization of plagioclase occur, and ferruginous dolomite is formed under the influence of a signifi-cant supply of CO 2 . Alkaline (sodic) metasomatism is superimposed on the mineral metasomatic paragenesis of the first stage. We consider metasomatic zoning during sodic metasomatism, manifested in one of the spessartite dikes. Chlorite and relics of magmatic dark-coloured minerals are replaced by magnesite, the supply of Na leads to the appearance of newly formed albite, and the supply of S leads to the formation of pyrite, which concentrates iron from other minerals. As a result of the sodic metasomatism, iron content in carbonates decreases in the direction from the outer metasomatic zone to the inner one. We conclude that it was the alkaline-sulphide sodium solutions that performed the ore-bearing function, and beresitization and listvenitization prepared a favourable environment for ore deposition.
One of the ways to improve cement production in the complex processing of nepheline concentrates is the activation of the raw mix on the basis of waste bleached sludge. The ultimate goal of activation is to increase the rate of charge sintering, to reduce the clinker formation temperature and, as a result, to reduce the cost of the clinker burning process for a number of cost items (fuel consumption, repair costs, refractory consumption, etc.). Hydrochemical activation of sludge with carbon dioxide seems to be the most promising from the point of view of capital costs and the effect obtained. To determine the role of certain technological factors in the activation process, experimental studies were carried out, establishing a correlation between these factors and the chemical composition of activated sludge. Evaluation of the activity of nepheline slime obtained as a result of carbon dioxide treatment was carried out by firing it to cement clinker under standard technological conditions. Roasting was carried out in the high-temperature region with quenching of samples at temperatures from 10OO to 1400 °С. The efficiency of mineralizing effect of the active component of the charge was estimated by the rate and temperature of the beginning of formation of the most important clinker mineral - elite (3Ca0-Si02), as well as by the completeness of calcium oxide assimilation in accordance with the stoichiometry of mineral formation. The obtained results create the necessary prerequisites for reducing the firing temperature and improving the technical and economic indicators of the conversion.
