STUDIES REGARDING THE RECOVERY POSSIBILITIES OF HEAVY METALS FROM WASTE CATALYSTS RESULTED FROM CO CONVERSION
During CO conversion with water steam, the reaction occurs very slowly even at higher temperatures. In order to increase the reaction rate, catalysts of slow temperature based on copper oxide, zinc oxide, chrome oxide and aluminium oxide are used. A way to reuse these waste catalysts is the extraction of the heavy metals with different acids. In this paper we carried out studies in order to establish the optimum conditions of copper and zinc extraction from waste catalysts. The waste catalyst was separated in four fractions (< 0.5; 0.5 – 1; 1 – 2 and 2 – 4 mm). For the extraction we used HCl, HNO3 and H2SO4 solutions of various concentrations (5, 10, 15, 20 and 30 %), at various stirring times (2.5, 5, 7.5, 10, 12.5, 15, 30, 45 and 60 minutes) and various stirring speeds (200, 400, 600 and 800 rot/min). For all used acids, the optimum conditions for zinc and copper ions extraction from waste catalyst are: dimension of the catalyst particles: <0.5 mm; stirring time: 15 minutes; acid concentration: 30%; stirring speed: 600 rot/min.