Recovery of iron and copper from spent HCl used to clean up dirty car radiators

This paper discusses a method to recover copper and iron and some of their valuable salts from spent hydrochloric acid used to clean up dirty car radiators and to recycle the acid. The spent acid is 6.18 M in concentration and contains low concentrations of iron and copper. Factors affecting the efficiency of the method have been investigated. Results show that the blowing of atmospheric air at a flow rate of 5 ml s(-1) 1 acid volume(-1) into the hot, diluted spent acid oxidizes about 90% of the ferrous ions to insoluble goethite. Hydrogen peroxide increases the extent of iron oxidation. Copper is extracted by solvent extraction using LIX 860 and stripped with 1 M HCl. Copper hydroxide is prepared by reacting the stripped copper chloride with lime water, Polyacrylamide A100 flocculant helps agglomeration of Cu(OH)(2) to a sludge that is easy to filter. Different copper salts were prepared based on the market needs and price, Electrodeposition of copper by electrolysis is favoured at low bath temperature (30 degrees C), addition of nitric acid and gelatin. Copper powder is deposited using a low copper ion concentration( less than or equal to 10 g copper ion/l) and high cathode current density of approximate to 2000 A/m(2). The remaining HCl acid is suitable for recycling, Pyrometallurgical recovery of copper involves reducing copper oxide with hydrogen or carbon at 1250 degrees C. A preliminary cost study shows that the prices of the products are competitive with the local market prices. (C) 2000 Published by Elsevier Science B.V. All rights reserved.