Calcination of activated raw mixes based on nepheline sludge

Abstract

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.