15 Jan 2010 07:00
XTIERRA REPORTS METALLURGICAL RESULTS ON OXIDE RESOURCES AT BILBAO
Dublin, 15 January 2010 - Minco plc (AIM - "MIO"), the Irish exploration and development company announces that its TSXV quoted subsidiary, Xtierra Inc., yesterday reported it has completed oxide metallurgical test work as part of a Feasibility Study being conducted on Xtierra's 100% owned Bilbao silver-zinc-lead-copper deposit located in the Central Mineral Belt of Mexico in the State of Zacatecas and is now proceeding to implement a pilot plant test program. The work was carried out at the Metallurgical Institute in San Luis Potosí.
Commenting on the Bilbao Oxide Metallurgical Test Results, Xtierra's President & CEO, Terence McKillen said, "The oxide test results are extremely positive and indicate that we have a practical and economic solution to the processing and recovery for the oxide resources which represent approximately 40% of the total resource potential at Bilbao. More importantly, it allows us to focus on open pit mining methods for the initial development of Bilbao, including all of the oxide and transition resources with the potential of extracting a significant portion of the sulphide resources before underground development."
The objective of the oxide metallurgical study was to develop a process for the recovery of silver, zinc, lead, copper and gold to commercially acceptable levels. The process involves crushing and grinding all run-of-mine material to 80% -200 mesh and then removal of 40-50% of the volume of material (pre-concentrating) using a high intensity magnetic separator (HIMC). This results in a significant reduction in the material requiring downstream processing. The non-magnetic concentrate, containing the majority of the payable metals, is then subject to processing including sulphuric acid leaching to recover copper and zinc metal; flotation to recover lead and silver in a concentrate; and cyanide leaching to recover gold and silver.
The flow sheet design exhibits a number of advantages which are anticipated to impact positively on operating and capital costs. Acid consumption represents one-third of that required without the HIMC process. Transportation and smelting costs are reduced as lead concentrate is the only product requiring smelting and it will contain only lead and a percentage of the silver. All of the other contained metals are recovered as direct metal products and doré. Savings in capital cost result from a 40-50% reduction in the size capacity of downstream processing equipment. In addition, the 40-50% magnetic reject from the HIMC process contains 35% iron oxide which may be a marketable product to the cement industry.
The metal recoveries from the metallurgical test work on the oxide material include:
Zinc 61.2%
Lead 41.0%
Silver 66.7%
Copper 71.0%
Gold 55.0%
Even though these appear to be low recoveries relative to recoveries in a conventional flotation process on sulphide ores, the resulting gross values are expected to be similar since pure metal is produced in all cases other than lead and the smelting/refining process is circumvented. Additional optimization will occur during the pilot plant test program which will begin in February 2010. Test work on the primary sulphide and transition (mixed oxide and sulphide) resources is currently in progress with encouraging results to date. Sulphide resources will be processed utilizing a conventional flotation flow sheet.
Qualified Person
The above information has been reviewed and verified by Mr. Terence N McKillen, B.A. (MOD), M.A., M.Sc., P.Geo, Chief Executive Officer. Mr. McKillen is the Qualified Person for the purposes of the AIM Guidance Note on Mining, Oil and Gas Companies dated March 2006. Mr. McKillen is a graduate in Natural Sciences (Geology) from Trinity College Dublin and holds a Master of Science degree in Mineral Exploration and Mining Geology from the University of Leicester. He has 40 years of exploration experience in Ireland and internationally.
About Xtierra Inc.
Xtierra Inc. is a Toronto based exploration and development company listed on the TSX Venture Exchange. Xtierra's shares trade under the symbol "XAG". Xtierra has 49,862,003 shares issued and outstanding. Xtierra is conducting a feasibility study on its 100% owned Bilbao silver‐zinc‐copper project in Zacatecas, Mexico. Xtierra's objective is to become a mid‐tier producer of precious and base metals through the development of its Bilbao and Laguna projects, both located in the Central Mexican Mineral Belt in the State of Zacatecas, as well as through exploration, organic growth and M & A opportunities.
About Minco
Minco PLC is an AIM quoted precious and base metals exploration and development company engaged in zinc exploration on the Pallas Green property in Ireland in a joint venture with Xstrata Zinc and investments in zinc-silver projects in Mexico through its 60% shareholding in Xtierra Inc. listed on the TSX Venture Exchange (Toronto) under the symbol "XAG".
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| Terence McKillen: Chief Executive | +1 416 362 8243 |
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