Production of pigments for concrete based on iron-containing industrial waste

Iron-containing industrial waste (Fe-waste) can be used as secondary raw materials for the production of iron oxide pigments (PIO). The basis of PIO is hematite Fe2O3 (red), goethite FeOOH (yellow), magnetite Fe3O4 (black). Pyrite cinders, spent iron oxide catalysts, waste of synthesis pigment TiO2, acid mine waters, gas cleaning sludge of converter production, waste from processing bauxite into alumina, spent pickling solutions and others can be used for processing into PIO. The main consumer of PIO is the construction industry. A variety of colors, resistance to sunlight, atmospheric factors, alkalis and weak acids, good hygienic characteristics will make it possible to use PIO as fillers for painting concrete, brick, paving slabs, tiles in various shades of red, yellow, orange, brown. The color range of PIO can be expanded due to the inclusion of additives in the composition of pigments: oxides of various metals, organic chromophores and others. The classic processes of Laux and Penniman, methods of precipitation and thermal decomposition, simplified process solutions based on the calcination of iron-rich waste can be used for convert waste into pigments. Pigments obtained by classical methods are characterized by a stable composition and higher quality than pigments obtained by simplified methods. The advantages of simplified technologies are the minimum amount of secondary waste generated, low costs for the introduction of technologies into practice, and the moderate cost of the resulting PIO. The main disadvantage of the classical and simplified technological solutions proposed by various authors is the poor study of issues related to the disposal of the resulting secondary waste. Rational way out of this problem will make it possible to successfully implement an integrated approach to the processing of raw materials and return thousands of tons Fe-waste stored at landfills to the economic turnover.