Treatment method of hydrochloric acid waste liquid from steel pickling

Abstract

The invention relates to the technical field of steel pickling waste liquid, and especially relates to a treatment method of hydrochloric acid waste liquid from steel pickling. The iron grade in the treated waste residue reaches 44-50% and can meet the requirements of steel mills on the iron grade quality, and a calcium chloride solution can meet the requirements of other enterprises. Zero pollution emission after hydrochloric acid waste liquid treatment is achieved, and resources are recycled. An oxidation neutralization method is improved and upgraded to enable liquid calcium, calcium chloride dihydrate, anhydrous calcium chloride and sludge produced after the treatment to meet the standard requirements and the industrial demands, so as to recycle the resources. The project investment is little, the treated products can be used in industrial production to both achieve zero emission of treated pollution wastes and recycle the resources, and moreover the operation cost is low, so that the treatment method is suitable for the development demands of small and medium-sized enterprises.

Description

technical field [0001] The invention relates to the technical field of steel pickling waste liquid treatment, in particular to a method for treating steel pickling waste hydrochloric acid liquid. Background technique [0002] Pickling is a very important process used by wire product manufacturers to remove scale on the surface of steel. A large amount of pickling waste liquid will be produced after pickling of steel products. In my country, nearly one million tons of such waste hydrochloric acid liquid are discharged every year, and it will increase with the increase of steel production. There are 0.05-0.5g / L hydrogen ions and 60--250g / L ferrous ions in waste hydrochloric acid, which have been included in the "National Hazardous Waste List" due to its severe corrosion. If the hydrochloric acid waste liquid is not properly treated, it will pollute the environment and waste precious resources. For this reason, researchers from many domestic and foreign companies have long bee...

AI Technical Summary

Problems solved by technology

This method requires an investment of hundreds of millions of yuan, and high-temperature heating devices are required during operation, and the operating cost is relatively high. It is not suitable for the operation and development of small and medium-sized enterprises, and the regenerated hydrochloric acid cannot be used in the pickling process, which is likely to cause new pollution.

[0005] Oxidative neutralization method: use calcium hydroxide, the product of calcium carbide slag digestion reaction, for neutralization. After neutralization, the pH value can meet the requirements, but the produced calcium water and sludge are difficult to meet the standard requirements and easily cause secondary pollution, which needs to be developed. Improved production process to produce liquids and sludges that can be recycled to commercial grade