The possibility of obtaining brown pigments with the use of blast furnace slag from waste water containing nickel is justified. The scheme of the main reactions is proposed. The kinetics of the reactions is studied. The contribution of the chemical interaction into the overall degree of treatment is established by potentiometric titration. The influence of the main factors on the degree of nickel extraction is determined. The phase composition of the formed pigment is established with the help of X-ray analysis. Rheological properties of the pigment particles are set.