Far West Mining Ltd. (TSX:FWM) has announced that metallurgical test work in progress at SGS Lakefield is returning excellent results.
Batch tests on a new composite representative of the initial five years of production has produced a concentrate of 32% Cu at 89% recovery from a lower head grade (0.45% Cu versus 0.56% Cu) and a coarser primary grind size (160 microns versus 120 microns) than previous tests. The results confirm that the grinding circuit will require less power than predicted to date, resulting in lower operating costs for the project. The Company is continuing to evaluate even coarser primary grind levels.
Far West ("the Company") contracted SGS Lakefield in Ontario to conduct metallurgical test work on sample material from the Santo Domingo deposit. The new composite was designed to be representative of the first five years of production at Santo Domingo. The composite has an average grade of 0.45% Cu and has been used for process development such as determination of primary grind and optimal flotation conditions.
The test work confirms previous results and achieved excellent copper recoveries between 87% and 89% with high copper concentrate grades ranging from 30% to 32%. These excellent results were achieved using a primary grind of 160 microns, significantly coarser than the previously targeted grind of 120 microns. Additional tests are underway to establish whether an even coarser primary grind (180 microns to 200 microns) will further improve the economics of the project. It is important to note that these results were achieved with a composite that has a lower head grade than any previous metallurgical sample (0.45% Cu versus 0.56% Cu previously). This is most encouraging and indicates that previous projections of copper recovery at Santo Domingo, at lower head grades, were too conservative. Further optimisation test work and locked cycle tests are in progress along with variability samples that will define grade and recovery across the whole resource base. Locked cycle tests generally improve results over batch tests as additional material is recovered in a scavenger circuit.
The ability to operate with a coarser primary grind (160 microns compared to 120 microns) will decrease the power consumption of the grinding circuit. Grinding power is the most important contributor to milling costs and this change will lead to a reduction in operating costs.
Iron metallurgical test work continues on magnetite and hematite composites as well as a large number of variability samples. Preliminary results from the magnetite work confirm that production of high iron (+65%) concentrate is readily achievable and work is now focused on optimising regrind size for silica rejection.
The results from these tests will be used to construct a grade-recovery curve for copper and iron that will be used in the ongoing Pre-Feasibility Study for Santo Domingo. The Company will report additional results as they become available.
Due to the late receipt of this data, it is now anticipated that completion of the Pre-Feasibility Study will be delayed until May 2011.
The in-house qualified person responsible for the Project is Richard Zimmer, P. Eng., MBA, Chief Executive Officer, President and a director of the Company who has reviewed and approved the contents of this news release.
Source: Far West Mining Ltd.