Synthesis of red iron oxide pigment on the basis of converter steelmaking slag for construction industry

The article presents a method for producing a red iron oxide pigment with the use of converter steelmaking slag as the main iron-containing component without magnetic separation stage. To fulfill the task, the slag was subjected to preliminary processing operations in order to obtain a powdery material and remove impurities, by dissolving iron and its compounds with sulfuric acid to form a solution of iron (II) sulfate and by further thermal decomposition at a temperature of 650 ºС (copperas red process). It has been found thatthe iron oxide pigment obtained by the proposed method consists of α-Fe2O3 hematite (93-95 %), has high quality and coloring characteristics, and an extremely low content of undesirable substances that worsen its properties. Phosphoric anhydride (Р2О5), being a constituting element of the slag, had a favorable effect on the process of pigment synthesis as a mineralizing additive. The degree of extraction of iron, calcium and magnesium is extremely high (97, 99.3 and 97 respectively), what indicates at the high efficiency of this method. This research work is of great importance for the construction industry, especially in the field of decorative concrete and mortars.