UTILIZATION OF RED SLUDGE IN TECHNOLOGY OF INORGANIC PIGMENTS: THERMODYNAMIC ASPECTS

Abstract

It has been established that the industrial waste of alumina production: high-iron, high-aluminum-containing red sludge can be used as a raw material for the synthesis of inorganic pigments of the brown-ocher range with an equivalent replacement of pure oxides of the color-forming metals Ferrum and Aluminum for the waste. A thermodynamic analysis was carried out using the concepts of enthalpy, entropy and Gibbs energy of the transition of ions from the tetrahedral positions of the spinel oxygen framework to the octahedral positions and the principle of series-parallel reactions. Determination of the coefficients of distribution and transition of ions in complex spinels in the process of formation of spinel structures of inverted and mixed type proved the possibility of using red sludge in the processes of creating continuous series of solid solutions and formation of stable brown and ocher color.