Shorokhov M. Resource-saving technology for utilization of Cr6+ containing wastewater

Object: the process of utilization of chromium (VI) containing spent low-concentration solutions to obtain barium (II) chromate; objective: development of local reagent technology for utilization of chromium (VI) containing spent low-concentrated solutions to obtain marketable of barium (II) chromate; methods: theoretical and experimental research methods: pH-metry, conductometry, photocolorimetry, X-ray phase analysis; novelty: determined the effect of preliminary alkalization of H2CrO4 and H2SO4 solutions with alkaline Са2+ - containing solutions, including aqueous extract from soda production sludge, on the reduction of residual concentration of CrO42- and SO42- in the formation of sparingly soluble ВаCrO4 and ВаSO4 by precipitation of Ва(ОН)2 solutions; рroved the possibility of automated dosing of reagents based on the pH value of solutions, this creates the preconditions for the organization of a continuous process of purification of Cr (VI) -containing wastewater, which is especially important for the processes of washing products after electrochemical chromium plating, chromatization and passivation; еstablished the dependence of the deposition rate of BaCrO4 on the initial concentration of Н2CrO4 and the degree of supersaturation has been, which allows to calculate the residual concentration of CrO42- in the deposition process; еstablished the dependence of the average particle size of the solid phase of suspensions on the rate of their stratification from the molar ratio "Ba" , mixing speed and temperature, which allows to optimize the filtration process and obtain precipitates of a given particle size distribution; results of the study: developed the technological scheme and technological mode of the process of reagent wastewater treatment containing Cr6+ compounds; рroposed a model of material balance of the purification process, which takes into account the total salt content in fresh water, which enters the washing of products after chromium plating and the change of the total salt content in the purified water; it is established that the physical and chemical properties and technical characteristics of the sludge formed as a result of the developed technology of reagent treatment of Cr6+ -containing wastewater, satisfies the characteristics of pigments used for the manufacture of passivating primers and enamels; the branch: chemical engineering.