Spent pickle liquor

Use closed-loop systems for pickling regenerate and recover acids from spent pickling liquor using resin bed, retorting, or other regeneration methods such as vacuum crystallization of sulfuric acid baths. 

Cleaned steel products (e.g., sheets, plates, bars, pipe) Process wastewater containing mill scale, oils, other pollutants, and low levels of metals Wastewater sludge Air pollution control (APC) dust Spent pickle liquor (K062)... 

Spent pickle liquor rinse water sludge... 

Reuse minimal K062, Spent pickle liquor Hazardous components lead, nickel, chromium Total generation about 6 million t/yr Reuse some recycled... 

Spent pickle liquor in the acid pickling wastewaters is listed as hazardous waste K062, regulated under RCRA, as it contains considerable residual acidity and high concentrations of dissolved iron salts.2 Exhausted pickling baths are mainly composed of nitrate (150 to 180 g/L), fluoride (60 to 80 g/L), iron (III) (30 to 45 g/L), chromium (III) (5 to 10 g/L), and nickel (II) (3 to 5 g/L). 

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... 

Flydrochloric acid regeneration. This process is used to treat the spent pickle liquor containing free hydrochloric acid, ferrous chloride, and water that is obtained from steel finishing operations. The liquor is concentrated by heating to remove some of the water, followed by thermal decomposition in a roaster at temperatures (925 to 1050°C) sufficient for complete evaporation of water and decomposition of ferrous chloride into iron oxide (ferric oxide, Fe203) and hydrogen chloride (HC1) gas.19 The iron oxide is separated for offsite recovery or... 

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). 

Through the late 1980s, spent pickle liquor was traditionally land disposed by steel manufacturers after lime neutralization. The lime neutralization process raises the pH of the spent acid and makes heavy metals in the sludge less likely to leach into the environment. Today, however, some of the spent pickle liquor can be recycled or regenerated on-site by steel manufacturers.5... 

An acid regeneration system has been installed to regenerate spent pickle liquor for reuse on-site. 

The above equation constitutes the theoretical or stoichiometric amount of liquid hydrochloric acid needed to pickle 1 ton of steel. Stoichiometric means as per chemical formula, using absolutely pure materials with no losses.16 In practice, it is not possible to use up all the acid in the pickle tank if pickling is to be complete in any acceptable time. Depending on the pickling equipment, between 70% and 80% of the free acid will be used up in dissolving the scale, and 20-30% will remain as free acid in the spent pickle liquor.16... 

A pilot plant, containing two pulsed columns, one for extraction and one for stripping, and batchwise evaporation was in operation in Sweden during 1981. Pilot plant operations have also been performed in Holland (Fig. 14.6) and Germany. The experience from these tests shows that the process concept is technically practicable and well proven. The economics of the process, however, are strongly dependent on the cost for disposal of spent pickling liquors. 

McCoy. September/October 1988. "Bipolar Membranes Applied to Spent Pickle Liquor Recovery." The Hazardous Waste Consultant. McCoy and Associates, Inc. Lakewood, CO. Pp. 1-18 to 1-21. 

Listed Waste K062 Spent pickle liquor generated by steel finishing operations of plants that produce iron or steel August 8, 1988... 

Ion-exchange membranes also show some promise in the solution of waste problems, inter alia the treatment of spent pickle liquors by electrodialysis is discussed (80). A very high degree of deionization can be achieved with ion-selective membranes. P. Cohen investigated the electrodialysis of simulated pressurized water reactor coolant (34). The specific resistance of the treated water was as low as 0.5 to 3,0 Mi cm. 

Sulfuric acid is number one in synthetic chemical production. It is used to produce phosphate fertilizer, high octane gasoline, and a wide variety of inorganic and organic chemicals. Large quantities are consumed to pickle steel (cleaning and removal of surface oxides) disposal of spent pickling liquor can be a problem. 

Bipolar membrane synthesis also holds promise for regenerating spent pickling liquors in stainless steel manufacture. As shown in Fig. 43(b), waste acid laden with metal ions can be continuously neutralized, filtered to remove the precipitated metal oxide, and the clarified salt solution split into its acid and base components in a bipolar membrane unit [Type (IV) shown in Table IX], As much as 95% of the hydrofluoric and nitric acid used are returned to the pickling bath, thereby solving a waste... 

H.C. Bramer and J. Coull, Electrolytic regeneration of spent pickling solution, Ind. Eng. Chem., 1955, 47, 67-70 C. Homer, A.G. Winger and G.W. Bodamer, R. Kunin, Electrolytic treatment of waste sulfate pickle liquor using anion exchange membranes, Ind. Eng. Chem., 1955, 47, 1121 D.J. Lewis and F.L. Tye, Treatment of spent pickle liquors by electrodialysis, J. Appl. Chem., 1959, 9, 279-292. 

K062. . Spent pickle liquor from steel finishing operations Secondary Lead ... 

The cost of ferric chloride on treatment is determined by consumption of FeCl 3. The cost of ferric chloride depends on location of the treatment plant (transport cost), quality of the ferric chloride (solid/liquid/imported/purity) and quantity purchased. Quoted prices (per kg FeCl 3) ranged from about 0,29 US /kg for a 20 ton local delivery of liquid FeCls to US 7.10/kg for imported, high purity and low quantity FeCl3. It should be noted here that experiments in this smdy were performed with analytical grade FeCls. The impurities in FeCls produced from spent pickle liquor from iron and steel production may not be of concern when used for conventional treatment, but for membrane applications this effect should be investigated. For this reason both ends of the range are used for comparison. 

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