Method for industrially eliminating toxic ingredients in chromium slag

Abstract

The invention relates to an industrial method for eliminating the toxic components of chromium slag, which comprises the following steps in turn: (1) countercurrently countercurrently countercurrently 1-2 times the chromium slag with 1-5‰ KMnO4 or NaClO2 solution, and simultaneously grinds the chromium slag to a particle size below 1mm; ( 2) Use 2 to 5 times of industrial water to wash the ground chromium slag in countercurrent in a spiral washing machine; (3) collect chromium slag, and use a conical hydraulic classifier and a hydrocyclone to separate the solid from the cleaning liquid; ( 4) Collect the cleaning solution, adjust the pH of the cleaning solution between 6-8, add saturated CaCl2 or BaCl2 solution until no precipitation occurs; (5) Collect the precipitate, and the resulting precipitate is calcium chromate or chromic acid Barium, the supernatant was recycled. The chromium slag detoxification process of the present invention not only eliminates Cr(VI), but also completely reduces total chromium, fully meeting environmental protection requirements.

Description

technical field [0001] The invention relates to an industrial method for eliminating toxic components of chromium slag, in particular to a method for preparing calcium chromate or barium chromate from chromium slag so as to reduce the total chromium content in chromium slag and simultaneously eliminate toxic hexavalent chromium components in chromium slag Methods. Background technique [0002] Chromium slag refers to the gray residue left after chromite, soda ash and calcium filler are mixed in a certain proportion during the production process of chromium salt, calcined at high temperature, and sodium chromate is leached with water. Chromium slag contains Na 2 CrO 4 , CaCrO 4 The toxicity of Cr(Ⅵ) compounds, in addition to their strong oxidative properties, also enters the human body and animals through the skin, digestive tract and respiratory tract, and can induce a series of carcinogenesis. The amount of chromium slag discharged in my country is about 400,000 tons ev...

AI Technical Summary

Problems solved by technology

[0006] method principle application practice features dry method Mix chromium slag with a particle size of less than 4mm and coal particles at a ratio of 100:15, and perform reduction roasting at high temperature to reduce Cr(Ⅵ) to Cr(Ⅲ) Refining glass colorant, calcium magnesium phosphate fertilizer flux, ironmaking auxiliary agent, cast stone and cement, etc. Valuable products can be obtained, but the processing cost is high, the amount of slag eaten is small, and the detoxification of chromium slag is not complete wet method Add Na 2 S, FeSO 4 and other reducing agents to reduce Cr(Ⅵ) to Cr(Ⅲ) Combined application with reducing papermaking waste liquid and monosodium glutamate waste liquid can achieve the purpose of treating waste with waste Cr(Ⅵ) after treatment≤2×10 -6 , but the treatment cost is high, so it is not suitable to deal with bulk chromium slag curing method Add a certain amount of FeSO after pulverizing the chromium slag 4 , inorganic acid and cement, add water and stir, so that the chromium slag is sealed in the cement and cannot be dissolved

Mainly cement curing, there is also a small amount of asphalt, lime, fly ash, and chemical reagents for curing applications where a large amount of curing agent is added, and the cost is extremely high

Images