The invention discloses a method for treating stainless steel
pickling waste liquor and recovering iron,
chromium and
nickel. According to the method, a
sodium hydroxide solution is adopted to control the pH of the stainless steel
pickling waste liquor to achieve the purpose of
recovery of iron,
chromium and
nickel through
fractional precipitation. Because pH ranges of deposition of the iron,
chromium and
nickel elements are overlapped, part of
iron oxide-
hydroxide is precipitated firstly in a separation and
recovery process, residual iron and chromium elements are co-precipitated out, and then chromium is precipitated and dissolved under the strong alkaline condition to realize final separation of iron and chromium. Due to presence of
ammonia water and a
reducing agent, the nickel element exists in the form of ions or a nickel ammine complex, is dissolved in the waste liquor, and finally reacts with a
sulfide to precipitate NiS. The method has the characteristics of low cost, easiness in control, high separation and
recovery rate of the iron, chromium and nickel elements and the like. The method can treat the stainless steel
pickling waste liquor effectively, and the
natural environment cannot be polluted after emission; the recovered
metal elements have the recycling
economic benefits, and the method has high application value and important technological innovation meaning.