GREENWOOD VILLAGE, Colo., Sept. 22 /PRNewswire/ -- Metalline Mining Company (NYSE Amex: MMG; TSX: MMZ) is pleased to provide an update on progress at the Sierra Mojada Project, located in Coahuila, Mexico. A new power point presentation is posted to the web, which is being used in investor presentations going forward beginning this week.
The Company has received a report on the deportment of silver and zinc from a sample taken from the shallow silver-zinc resource from the San Salvador shaft area at approximately 100 meters depth along section 631500E, a cross section of which was posted to the web earlier. The deportment study demonstrates the likely methods for recovery of silver, zinc, and lead.
The head grade of the sample was 568 gpt Ag, 4.2% Zn, and 1% Pb. This is higher than expected average grade but was chosen to make sure there were ample quantities of silver and zinc to recover. Silver is contained mostly in acanthite (Ag2S) and silver halides, both of which are very soluble in cyanide. Silver extractions in cyanide were 80% (at -100 mesh) to 91% (at -250 mesh), depending upon grind size and the degree of liberation of the silver-bearing minerals. Zinc is contained almost exclusively in smithsonite (ZnCO3). Separately, smithsonite was concentrated by heavy media (HML) separation to remove the silicates, then separated from both cerrusite (PbCO3) and limestone/dolomite fractions using a super-panner on the HML heavy mineral separate. Zinc concentrate grades of 25-31% were achieved, with a total recovery of ~75%. Much work remains on complete separation of zinc and silver to maximize recovery of both metals. Lead should be recoverable by either gravity or flotation methods due to the higher density of cerrusite compared with that of smithsonite and the carbonate gangue minerals.