STREAMLINED ATOMIC-ABSORPTION PROCEDURES FOR COPPER EXPLORATION AND MINING

Assessment of copper ores requires the establishment of both the total copper (TCu) content and the made of occurrence of the copper, e.g., as oxide or sulfide minerals, In establishing the latter, cyanide solu ble copper (CNCu) and acid soluble copper (ASCu) determinations are im portant, This paper describes flame atomic absorption procedures for d etermining TCu (and, in the same solution, 'partial iron') with 500 mg subsamples (> 85% minus 200 mesh) and CNCU and ASCu with 250 mg subsa mples. Extractions are performed in sealed, vertically secured, 50 ml polypropylene tubes at room temperature with (i) for TCu, a mixture of 3 ml of HCl and 2 ml of 1 + 1 HNO3, (ii) for CNCu, 10 ml of 2% m/v Na CN-0.1% m/v NaOH and (iii) for ASCu, 10 ml of 1 + 19 H2SO4. QA/QC meas ures are described, AAS calibration solutions were prepared by mass, T he 3s limits of detection mere 0.004% TCu, 0.009% CNCu and 0.002% ASCu . For the TCu procedure, the within-laboratory between-batch RSD was < 3% for samples containing between 0.15 and 4.40% TCu. The TCu procedur e was used to determine splitting and subsampling components of typica l copper ore sampling variance; It has yet to be used to determine the variance of sampling particular portions of a copper orebody in situ. The results obtained by these procedures agree weal with those obtain ed by commercial laboratories using their own procedures.