Laguna (100% owned by Xtierra)
All of Minco's Mexican interests are held indirectly through its investment (29%) in Xtierra Inc., a company whose shares are listed on the TSX Venture Exchange in Toronto.
The Laguna tailings re-treatment project is located on the outskirts of the city of Zacatecas, Mexico. Micon International, of Toronto, completed a feasibility study on the 1.2 million tonne a year operation to recover silver and mercury from 7.9 million tonnes (measured and indicated resource) grading 58.8g/t silver, 0.31g/t gold and 318g/t mercury. This resource contains approximately 15 million ounces silver (30.39 million ounces silver equivalent).
Over a 7 year project life the project would produce 390,000 kilograms of silver and 2,349,000 kilograms of mercury.
The tailings accumulated as a result of historic mining during the Spanish
colonial period. Mineral treatment during this period relied on the use
of mercury to recover precious metals from their ores. The Laguna material
contains significant remnant mercury and Minco is convinced that a re-treatment
process must ensure that any leakage of this material is fully contained.
Metallurgical test work seeking alternative processing methods has been
unsuccessful to date and alternative
sites for the tailings disposal, planned
to adjoin the main highway into Zacatecas has not been resolved. Unseasonably
dry conditions in recent years also requires a re-assessment of the proposed
floating dredge method for extraction of the tailings.
Xtierra is currently evaluating a lower capital method of metallurgical processing for the Laguna project and at the same time is in negotiation with the leadership of a local village for acquisition of the necessary land for project development.