Effect of different collector dose rates on cobalt segregation

Nkana Concentrator is the most important mineral processing unit of Zambia Consolidated Copper Mines (ZCCM) (soon to be privatised) which contributes about 65% of cobalt concentrates treated at the Nkana and Chambeshi Cobalt plants to produce high purity cobalt metal. However, it has of late been experiencing problems with the segregation of the bulk concentrates which contain an appreciable amount of copper which overloads the performance of the cobalt tankhouses. effort to improve the copper/cobalt separation at segregation stage, a number of new collectors have been put on trial tests with a view of replacing the traditional Sodium Ethyl Xanthate (SEX) which has been in use since the sixties. The intention is to possibly isolate a collector that will give improved recoveries and grades of both copper and cobalt to their respective concentrates at different flotation stages. s work, a series of laboratory testworks were conducted using Senkol 26, a Xanthic ester, Senkol 45, a blend of alkyl dithiophosphate and Xanthates and Senkol 700, a thionocarbomate type, which were supplied by SENMIN of South Africa on Nkana Concentrator feed materials. The feed materials are from four different sources namely; Mindola, Chibuluma, South Ore Body (S.O.B.) and Central shafts. The tests were carried out to compare the performance of the collectors based on their dose rates and later their performance compared to the collector currently being used at Nkana Concentrator. the dose rates of 20 and 30 g/t gave lower cobalt loses of 17 and 11.2 %TCo respectively, whilst grades were also very low at 0.25 and 0.19 %TCo respectively. nkol collectors exhibited poor separation of cobalt from copper at all dose rates except for Senkol 26 which gave loses of 8 %TCo at grade 0.14 %TCo at 50 g/t of collector which was much better than the SEX. ork has also shown that there is no incentive in increasing the dose rate of SEX beyond 30 g/t as there was no improved separation of cobalt from copper at an optimum depressant dosage and pH. On the other hand, the separation performance of Senkol 26 improved with increasing collector dose rate. Senkol 45 exhibited an increase in the of cobalt lost to the copper concentrate as the dose rate of the collector increased while no significant changes were noted with Senkol 700.