Removal of cobalt and nickel from zinc sulphate solutions using activated cementation

Abstract

The influence of different parameters (duration, temperature, zinc dust quantity, concentration of activators - copper and antimony) on the process of activated cementation of Co and Ni has been studied. We have worked with industrial zinc sulphate solutions. During the process of activated cementation of Co and Ni, copper (involved as CuSO4.5H2O) and antimony (involved as Sb2O3) were used as activators. The lowest values of Co content have been obtained at a temperature of 80-85 oC, CCu = 200-300 mg/dm3 and 18 multiple surplus of zinc dust. After adding Cu to the solution, mainly the cementation of Ni is activated, and that of Co is activated to a lower degree. It was found that when GSb : GCo ratio is between 0.5 : 1 and 2 : 1, the solution is purified from Co and Ni to a great degree. After intensive stirring and increasing the duration of the process the cement sediments dissolve reversely. This holds true of Co to a greater extent, as compared to Ni. The results obtained will be used to establish optimal conditions for the carrying out of activated cementation in Zinc Production Plant in KCM SA, Plovdiv

Recycling Zinc from Metal Oxide Varistors Through Leaching and Cementation of Cobalt and Nickel

“…At higher copper concentrations, the zinc surface was covered in copper eliminating the reaction sites available for cementation to take place. The results in this work are in agreement with Boyanov et al [18] in that the addition of copper did not significantly improve cobalt cementation.…”

“…Parameters that are known to affect cementation reactions are pH, temperature, activator concentration, and zinc dust quantity [12,13,[17][18][19][20][21]. Van der Pas et al [17] concluded that the optimal conditions for cementation in a solution containing 30 mg/L cobalt were 30 mg/L copper and 1.5 mg/L antimony (both as activators) as well as addition of 4 g/L zinc at a solution temperature of 70°C.…”

“…According to their work [21], maximum removal of cobalt and nickel occurs when the Sb:Co ratio is between 0.5:1 and 2:1. 18,20]. In the present work, the investigation was extended to solutions with cobalt concentrations of approximately 400 mg/L.…”

“…The aim was to investigate the feasibility of using cementation as a means for MOV leachate purification to make it suitable for zinc electrowinning. Since the MOV leaching solution contains 400 mg/L cobalt and 100 mg/L nickel, the optimal conditions from other studies [17,18,20,21] were scaled up for this investigation. Present investigations included studies of the influence of temperature, pH, activator concentration, and zinc dust surface area on the rate and extent of cobalt and nickel cementation.…”

“…Boyanov et al [18] determined that when the Sb:Co molar ratio is between 0.5:1 and 2:1, the solution is purified from cobalt and nickel to the greatest degree. In this work, a 1:1 (Sb:Co) molar ratio was used and the results obtained are shown in Fig.…”