Mintek carried out test work on core samples selected from four drill holes identified by SRK as being reasonably representative of the Voskhod deposit on the basis of preliminary studies. The tests included the crushing, screening, washability, characterisation and concentration of the chrome ore into products to generate the necessary data for the design of the process flow sheet for the commercial plant. The results showed that very high grade chrome ore of typically 48% Cr2O3 and a chrome concentrate of up to typically 57% Cr2O3 can be readily produced from Voskhod. The test work and process flow sheet information from Mintek was supplied to DRA-I to support the design and determination of the processing plant capital and operating costs.
The DRA-I plant design comprises a crusher and screen to reduce the 300mm ROM ore feed to less than 150mm, DMS (Dense Media Separation) drum and DMS cyclone stages for coarse and fine chrome ore fractions, respectively and a spiral concentration plant for the fine ore of less than 1mm. The tailings are thickened for disposal in the tailings dam.
Tailings will be stored in a lined facility with deposition planned over 14 years at an average rate of 148,000 tonnes per annum pumped slimes and 216,000 tonnes per annum of trucked coarse material. The height of the facility at closure will be 25m.
The plant has been designed with flexibility to handle the expected variations in ROM feed over the life of the mine and has scope for future optimisation. DRA-I estimated the capital and operating costs for the plant and in addition, certain costs related to the associated infrastructure.
The expected Voskhod yield is projected at 69.8% and split into products as 52.3% lumpy (typically + 10 - 150mm), 9.9% chip (typically + 1 - 10mm) and 7.6% fines (typically -1mm) concentrate expressed as a percentage of the ROM feed.
