Physicochemical properties of fuel shales

Abstract

Current economic conditions call for innovative products such as coke for the electrode industry, graphite, and fullerenes. To that end, the physicochemical properties of fuel shales must be determined. Attention focuses on shales from the Pribaltiisk Basin (Leningrad field). The goals of the experiment are to determine the physical properties of the shales (moisture content, ash content, actual and apparent density, porosity), the optimal briquetting conditions, and the calorific value of the briquets. The influence of the fractional composition and moisture content on briquet strength is studied. The influence of the heating conditions on the physicochemical properties in the shales is considered. The briquets are heated in pipe furnaces with uncontrolled and controlled atmospheres, in the temperature range 200–1000°C. It is found that the increasing the briquetting pressure (from 10 to 15 MPa) and moisture content (from 11.6 to 37%) improves the briquet strength, while adding coal fines (4 wt %) and reducing the moisture content (to 23%) improves the calorific value of the briquets. Semicoking begins at 400°C. Further heating increases the yield of gases and reduces the yield of semicoke. After pressing, the shale fines may expediently be processed by heat treatment to obtain a graphite material.