EXTRACTION OF SULPHURIC ACID FROM TECHNOLOGICAL SOLUTION OF HYDROXYLAMINE SULPHATE SK96K0041 Maciej Wisniewski, Mariusz Bogumil Bogacki and Jan Szymanowski Poznan University of Technology, Institute of Chemical Technology and Engineering, PL M. Sklodowskiej Curie 2, 60-965 Poznan, Poland In chemical industry waste liquid streams contain often mineral acids alone or in the presence of various salts. The concentration of these acids can differ significantly. However, this concentration is usually too small to obtain commercially acceptable products. Thus, such streams are neutralised with lime and dumped. They are also neutralised with ammonia forming appropriate ammonium salts which are used as low quality fertilizers. Important amounts of ammonium sulphate are produced in caprolactam plants in Poland. Cyclohexanone is oximated with hydroxylamine sulphate and the obtained oxime gives caprolactam by Beckmann rearrangement carried out in concentrated sulphuric acid. Sulphuric acid is neutralised with ammonia to ammonium sulphate. Recovery of sulphuric acid from post reaction mixture is one of the main factors which could permit to improve the economy of the process. Sulphuric acid is also present in hydroxylamine sulphate solution. In Nitrogen Chemical Plants in Pulawy and Tarnow, Poland the hydroxylamine sulphate is obtained by catalytic hydrogenation of nitrogen(II) oxide earned out in the presence of sulphuric acid. Ammonium sulphate is formed as the by-product. The technological solution contains 305-315 g/dm^ hydroxylamine sulphate, 35-45 g/dnP sulphuric acid and 10-20 g/dm^ ammonium sulphate. The aim of this work is to study the recovery of sulphuric acid from such technological solution. Cyanex 923 which contains trialkyl phosphine oxide as the active substance is used for sulphuric acid extraction. Water is used for stripping. Effects of temperature, salt concentration and stripping are studied. It is found that sulphuric acid can be successfully recovered using 3 and 2 stages in countercurrent extraction and stripping, respectively. 87 k „ b L J.