Chlorine salt acid system prior complexing-selective iron precipitation chromium-iron separation method

Abstract

The invention discloses a chlorine salt acid system prior complexing-selective iron precipitation chromium-iron separation method. Sodium formate and the like are used as a complexing agent; and the proper complexing agent is selected to perform prior complexing for iron in hydrochloric acid solution to change the ion existence form so as to prevent quick mass hydrolytic precipitation of iron in the precipitating phase and the caused chromium inclusion loss. The method improves the iron ion complexing effect through adjusting the complexing agent and the use level thereof, the original solution pH, the complexing temperature and the complexing time, and adjusts the solution pH value through such alkali mediums as magnesium oxide to realize prior iron hydrolytic precipitation and effective chromium separation. The chromium solution after solid-liquid separation can be directly used for preparing different chromium salts. Compared with other traditional technologies, the method is simple in operation process, needs no special complex equipment, and is a new method with economy, effectiveness and operation easiness.

Description

technical field [0001] The invention relates to the field of nonferrous metal hydrometallurgy, in particular to a method for efficiently separating chromium and iron in a hydrochloric acid solution. Background technique [0002] Chromium and its compounds are widely used in industrial production, and are essential raw materials for metallurgical industry, metal processing, electroplating, leather manufacturing, paint, printing and dyeing, and even modern high-tech industry, national defense technology and other cutting-edge technology fields. While consuming a large amount of chromium in these fields, a large amount of chromium-containing wastewater is discharged every day. As a strategic resource, chromium reserves are not abundant in the world. Therefore, based on the fact that chromium is a scarce resource and has huge environmental risks, the comprehensive recovery of chromium in secondary resources has more practical economic and social benefits. Cr and Fe in electropl...

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Problems solved by technology

Among them, with P204 as extraction agent, under the condition of pH value of 1.5 in the aqueous phase material liquid, the extraction rate of iron can reach more than 99%, but the chromium will be obviously co-extracted, and the loss rate of chromium is relatively large; 1. The initial concentration of iron is required, and the adaptability to raw materials is poor; the ferrous oxalate precipitation method needs to strictly control the amount of oxalic acid added, the process conditions are not easy to control, and the process cost is high; although the mohr salt crystallization method has a light load on solution neutralization, However, the evaporation takes a long time and the cooling operation is not easy; the selective phosphoric acid precipitation method achieves the purpose of efficiently separating chromium and iron through selective phosphoric acid precipitation under the premise of reducing the chromium and iron in the solution to a low-valence state, but this method consumes Large amount of reducing agent, high process cost