May 21 st – 23 rd 2014, Brno, Czech Republic, EU CHEMICAL, PHASE COMPOSITION AND MORPHOLOGY OF COPPER CAKE AS A SECOND MATERIAL FOR PURE COPPER ELECTROEXTRACTION Gyunver HODJAOGLU, Ivan IVANOV Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, “Acad. G. Bonchev” Str., bl. 11, 1113 Sofia, Bulgaria, e-mal: gyunver@ipc.bas.bg Abstract In this study were investigated the surface morphology, chemical content and phase composition of two sorts of copper cakes from zinc plant of KCM-Plovdiv, Bulgaria. The aim of this research is the utilization of valuable copper from copper cakes and reduction the amounts of the specific secondary wastes from hydrometallurgy plants. The copper cake with low chlorine content was tested for leaching with diluted 12% sulfuric acid. The very first results indicate that at simple leaching the cake suspension with the mineral acid generates a substancial amount of dissolved copper sulfate. The leaching process, respectivelly the concentration of the copper sulphate, has the potential to be further optimized for direct formation of copper sulphate electrolytes from this specific waste product. Keywords: copper cake, surface morphology, cuprite, sulphuric acid leaching 1. INTRODUCTION The copper and copper-Cl cake under investigation are dense red-brown color filtrates from zinc plant of KCM-Plovdiv, Bulgaria. The first type cake is a product from roasting line of the zinc plant and contains predomonantly 66% cuprous (I) oxide (Cu2O). The second type waste is a product from “Waelz“ zinc line and contains 45% Cu2O and 4% CuCl [1, 2]. The copper (I) oxide forms the mineral cuprite which is a raw material in mine industry. In principle, copper cakes are product of cementation process and they consist of very small submicron particle aggregates [1, 2]. These specific wastes have very complex chemical composition including mainly different copper, zinc and lead compounds, as well as a large variety of metal impurities. Most of them formulate in the cake different oxide-, sulphate- and mixed chemical structures. Fig. 1 Crystallization products from copper cakes Fresh copper cakes contain large amount of water and have grease consistency. After deposition they loose water rapidly by capillary mechanism. The process of water evaporation is very intensive especially on the cake surface or in open flaws and this leads to appearance of different crystallization products (fig. 1, 1-3). This fact as well as the complex chemistry, they specify the copper cakes as a dynamic hazardous waste products at storage conditions. For example the main component copper (I) oxide is extremely toxic for aqua species [3]. Presently, the Bulgarian piro- and hydrometallurgy industry does not utilize the copper cakes from KCM zinc plant [1, 2]. The company for pure zinc and lead metal production disposes the copper cake 1. Unidentified green crystals 4. CuSO4/H2SO4 3. CaO/SiO2/H2SO4 2. SiO2/H2SO4