Method for treating hexavalent chromium wastewater
A technology for hexavalent chromium and wastewater, applied in filtration treatment, precipitation treatment, chemical instruments and methods, etc., can solve the problems of serious impurity absorption, storage and entrainment, fine particle size of lead chromate precipitation, poor solid-liquid separation, poor purity, etc. , to achieve the effect of improving the process effect, the method is simple and practical, and the process is short.
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Embodiment 1
[0027] Take 10 liters of waste water containing hexavalent chromium, the concentration of hexavalent chromium is 2.6g / L, adjust the initial pH at 3; add 180 grams of lead sulfate powder, control the final pH value between 4, keep stirring, and filter after 14 hours , the content of chromium in the filtrate is 0.3mg / L, and the content of lead is 0.2mg / L; add water to the filtered solid slag to adjust the slurry, the solid-liquid ratio is controlled at 1g / 10mL, add 42 grams of sodium sulfide solid, stir for 12 hours, and filter to obtain The solid slag, whose main component is lead sulfide, is specially piled up for unified treatment; the filtrate is heated to 90 degrees Celsius to evaporate and then cooled to crystallize to obtain sodium chromate crystals, and the evaporated crystallization mother liquor is combined with the next batch of filtrate to evaporate and crystallize to extract chromium Sodium acid.
Embodiment 2
[0029] Take 10 liters of wastewater containing hexavalent chromium, the concentration of hexavalent chromium is 2.6g / L, adjust the initial pH at 3; add 160 grams of lead chloride powder, control the final pH value between 3-5, and keep stirring, 11 Filter after 1 hour, the content of chromium in the filtrate is 0.2mg / L, lead 0.7mg / L,; Add water to the filtered solid slag to adjust the slurry, the solid-liquid ratio is controlled at 1g / 10mL, add 66 grams of potassium sulfide solids, stir for 12 hours, The solid slag obtained by filtration is mainly composed of lead sulfide, which is specially piled up for unified treatment; the filtrate is heated to 90 degrees Celsius and evaporated, then cooled and crystallized to obtain sodium chromate crystals, and the evaporated crystallization mother liquor is evaporated together with the next batch of filtrate Crystallized extraction of sodium chromate.
Embodiment 3
[0031] Take 10 liters of waste water containing hexavalent chromium, the concentration of hexavalent chromium is 2.6g / L, adjust the initial pH at 3; add 180 grams of lead chloride powder, control the final pH value between 3-4, and keep stirring, 6 Filter after 1 hour, the chromium content in the filtrate is 0.3mg / L, and the lead is 0.4mg / L; add water to the filtered solid slag to adjust the slurry, the solid-liquid ratio is controlled at 1g / 10mL, add 35 grams of sodium hydrogen sulfide solid, and stir for 12 hours , the solid slag obtained by filtration, the main component is lead sulfide, which is specially piled up for unified treatment; the filtrate is heated to 90 degrees Celsius, evaporated, cooled and crystallized to obtain sodium chromate crystals, and the evaporated crystallized mother liquor is combined with the next batch of filtrate Sodium chromate is extracted by evaporation and crystallization.
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