Light-Colored Ceramic Products from Red-Burning Clay Raw Materials

This article reveals the results of the conducted research on the production of ceramic products of light shades based on red-burning clay raw materials of the Doroganovskoye deposit. Based on the analysis of literary sources, it was found that the most common way to lighten a ceramic shard is the introduction of dispersed chalk into the mass. During the research, chalk was introduced into the composition of the mass in an amount of 10–30%. However, this led to a decrease in strength and an increase in water absorption in burnt products. In order to obtain light-colored ceramic products with high physical and mechanical properties, a modifying additive was additionally introduced into the composition of the masses, in addition to chalk. It was determined that this additive makes it possible to intensify the firing processes and makes it possible to obtain light-colored samples with a lower content of carbonate-containing material in the charge. X-ray phase studies have established that the mineralizing effect of this additive occurs due to its sufficiently low melting point. Due to this, the dark-colored mineral hematite is involved in the formation of new minerals characterized by low-intensity coloring, which ensures the production of light yellow samples. In addition, an increased content of anorthite and helenite is formed in the shard, which leads to an increase in the strength of the samples. Thus, laboratory studies have shown that it is possible to obtain light-colored ceramic products from the red-burning clay raw materials of the Doroganovskoye deposit by semi-dry pressing. The optimal composition of the ceramic mass and the production parameters for this are as follows: the amount of chalk in the mass should be 20%, the content of the mineralizing additive should be 1%, the preparation of the press powder should be carried out with preliminary plastic processing of the mass, the specific pressure of pressing samples is 20 MPa, the firing temperature is 1000 °C. This will make it possible to obtain burnt samples of light yellow color with a compressive strength of 36.1 MPa and a water absorption of 14.6%.