Technological Properties of Clay Raw Materials of the Northwest Orenburg Region

The chemical composition and technological properties of clay polymineral raw materials from the northwest of the Orenburg region were studied. On the basis of the chemical composition, the raw material can be attributed to semi-acidic sanded clays with a high content of coloring iron oxide Fe₂O₃ (4.83%). The dependences of the viscosity of clay suspensions at sufficiently high concentrations (up to 0.16 vol.%) are defined; the linear character is confirmed by a high correlation coefficient and plasticity of the raw materials, studied in two ways — by pressing the balls and bending the bands. This indicates a high content of sand. Sintering in the temperature range from 600 to 1000°C did not occur, resulting in the sample cracking. Macroparameters of sintering and color parameters of samples under high temperature, as well as the phase composition, suggest unsatisfactory mechanical characteristics of ceramics from the studied raw materials. Low sorption properties of mineral raw materials with respect to copper and lead ions were established. It is shown that the use of this raw material in the ceramic industry is impractical. It is recommended that the materials be used in road construction, landscaping, and as thinning additives to reduce the plasticity and shrinkage of clays during drying and firing.