Waste pickling liquor

Pickling done before coating may use a mildly acidic bath such spent liquor is not considered hazardous. Waste pickle liquor flows typically range between 10 and 20 gal/t of pickled product. Rinsewater flows may range from less than 70 gal/t for bar products to more than 1000 gal/t for certain flat-rolled products. The principal pollutants in rinsewater include TSS, dissolved iron, and metals. For carbon steel operations, the principal metals are lead and zinc for specialty and stainless steels the metals include chromium and nickel.15... 

Spent pickle liquor is considered a hazardous waste (K062) because it contains considerable residual acidity and high concentrations of dissolved iron salts. For example, spent pickle liquor and waste acid from the production of stainless steel is considered hazardous. The hazardous constituents in K062 are lead, nickel, and hexavalent chromium. Waste pickle liquor sludge generated by lime stabilization of spent pickle liquor is not considered hazardous unless it exhibits one or more of the characteristics of hazardous waste. An estimated 6 million tons of spent pickle liquor are generated annually in the U.S.1... 

The spent pickling liquor is called waste pickling liquor (WPL), which must be properly treated for disposal or reuse. Wastewaters from pickling include acidic rinse waters, metallic salts, and waste acid. WPL is considered a hazardous waste by the U.S. Environmental Protection Agency (U.S. EPA). 

Lime or alkaline substances are used to neutralize the waste pickle liquor. In addition, 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS),... 

The waste pickle liquor, rinse water discharges, and fume scrubber effluent can be combined in an equalization tank for subsequent treatment. Basically, three methods are used to treat the WPL ... 

Waste pickle liquors from these operations can often be of use to sanitary waste treatment systems for phosphate control and sludge conditioning. Some industrial firms can use spent process waste from pickling operation. Iron in the waste is used as a coagulant in wastewater treatment systems.1415... 

EARS [Enhanced acid regeneration system] A process for recovering hydrochloric acid from the ERMS ilmenite beneficiation process. It may be used also for recovering waste pickle liquor. The acid liquor containing ferrous chloride is evaporated at low temperature to form iron chloride pellets, which are fed to a pyrohydrolysis reactor. This generates hydrochloric acid and iron oxide pellets, which can be used for steel production or disposed of as inert landfill. Developed by E. A. Walpole at the University of Newcastle, Australia, from the early 1990s and piloted by Austpac Gold (now Austpac Resources). 

Ozdemir, T., Oztin, C., and Kincal, N.S. (2006) Treatment of waste pickling liquors Process synthesis and economic analysis. Chem. Eng. Commun., 193 (5), 548-563. 

There are several other groups of insoluble mercury compounds. One plant that included a fluorocarbons unit adopted a different approach to mercury control [108]. The waste HCl from fluorocarbon production was shipped several hundred kilometers to a steel mill for use in pickle liquor. The trucks that carried the waste acid then returned empty. The solution adopted was to fill some of the returned trucks with waste pickle liquor, which is strong in FeCh- This was available at a very low cost and nearly zero incremental freight expense. Combining it with chloride-containing wastewater that had been made alkaline produced the reaction ... 

Hydrochloric acid-sodium chiorate - 737 Hydrochloric acid-sodium chloride - 733 Hydrochloric acid-sulfuric acid - 655 Hydrochloric acid waste pickle liquor - 221, 774 Hydrocyanic acid - 29, 34,49, 53, 56, 67, 80,... 

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