II. CESL™ TESTING
Three concentrates from the Twin Metals project were successfully processed through Teck's hydrometallurgical research facility utilizing the CESL™ process for approximately a six week period in Q1 of 2013. The concentrates processed through the pilot plant consisted of three different concentrates from the Twin Metals resource. The first concentrate was a bulk concentrate (all metals floated in one concentrate) made from a mixed sample of material from the Maturi and Birch Lake deposits. The second concentrate was a bulk concentrate made from material derived from the western portion of the Maturi deposit. The third concentrate was a nickel concentrate derived as one of two products from the ALS flotation pilot plant during the period when a separate copper and nickel concentrate was being produced from ore from the western portion of the Maturi deposit.
The concentrate characteristics were:
- Maturi Bulk #1 - produced from Maturi East and Birch Lake deposits (17.0 % Cu, 3.7 % Ni and 20.4 g/t TPM (Total Precious Metals or TPM = Platinum+Palladium+Gold));
- Maturi Bulk #2 - produced from Maturi West deposit (15.5 % Cu, 4.1% Ni and 9.0 g/t TPM);
- Maturi Ni-Cu - produced from Maturi West deposit after separation of a high grade Cu concentrate ( 6.9 % Cu, 8.0 % Ni and 10.6 g/t TPM).
The main goals for each of the concentrates were to determine optimal base metal extraction while also recovering precious metals. Multiple variables were tested in the leaching circuits to determine the optimal operating conditions for recovery of metals.Overall CESL™ pilot plant metal recoveries from concentrate are presented in Table 1. The results for the two bulk samples are combined due to limited run time for the second sample.
Table 1: Maturi Metal Recoveries from Concentrate Concentrate Metal Recovery % Cu % Ni Maturi Bulk #1 93.7 96.1 Maturi Bulk #2 Maturi Ni-Cu 91.2 97.6Recovery of Precious Metals from CESL™ residue