Production of black iron oxide from red mud

Abstract

Production of inorganic pigments was studied, and specifically that of iron oxide black pigment, which can be used in paint-and-varnish industry and in manufacture of building and other pigmented materials. Results are presented of phase and chemical analyses of raw materials and final product. A technological scheme is suggested and production parameters of the black pigment from red mud are recommended. The pigment is produced from the −0.045 mm fraction of red mud, a waste from alumina industry. It is recommended to perform calcination at 850°C in a controlled atmosphere with deficiency of oxygen. This method yields an iron oxide pigment of purely black color with a coverage power of 8–10 g m⁻² from a waste produced in manufacture of alumina, red mud (up to 90%), without additional additives and provides reduction of Fe(III) to Fe(II) by the sulfide sulfur present in the starting mud.