PRODUCTION OF DIOPSIDE BASED ON RICE HUSK ASH BY SOLID-PHASE SYNTHESIS METHOD

VGKBHK

Abstract

The effectiveness of using diopside in the formulation of ceramic and other building materials, as well as for filling polymer compositions, and the simultaneous difficulties in its industrial extraction and processing make it relevant to synthesize diopside based on available starting components, for example, the carbonization product of rice production waste. At the same time, to obtain this mineral it is promising to use a fairly simple and cheap solid-phase synthesis of rice husk ash and dolomite as an accessible source of calcium and magnesium.

Optimization of the ratio of the initial components in the charge was carried out on the basis of an analysis of the phase composition of the solid-phase reaction product using the XRF method, in order to obtain the maximum diopside content of the synthesized calcium magnesium silicate. Melting was carried out for 3 hours at 1100 ^oC. A decrease in the temperature of solid-phase synthesis was achieved by adding flux - boric acid. It has been established that the maximum content of diopside (96%) is provided by the composition of the charge (%): flux - 5, rice husk ash - 37, dolomite - 58. The tail impurities in this case are cristobalite and ackermanite (crystalline silicon oxides). The need for a significant excess of dolomite in relation to rice husk ash is due to the fact that during the synthesis of diopside, dolomite decomposes with the release of carbon dioxide, which leads to the porosity of the resulting product, which is relatively low. A sample of the optimal composition has a fairly uniform structure, according to electron microscopic analysis.

The homogeneity of its structure is also indicated by the unimodal, relatively narrow distribution of particle sizes, the maximum number of which has a diameter of about 1 μm. Synthetic diopside has close to neutral pH values, probably due to the use of boric acid in its preparation, and low oil absorption values due to the relatively small total pore volume.