|November 20, 2008|
Trevali receives highly positive hard-rock metallurgical results from Santander silver-lead-zinc mine project in Peru
|Recoveries: Silver 84.5%, Lead 95% and Zinc 91%|
Vancouver, British Columbia... Trevali Resources Corp. ("Trevali" or the "Company") (CNSX: TV, Frankfurt: 4TI, Pink Sheets: TREVF) is pleased to announce it has received highly positive results from initial independent metallurgical testing of its high-grade Magistral Norte zone on the Santander silver-lead-zinc mine project in Peru. Recoveries to the separate rougher concentrates are: silver 84.5%, lead 95% and zinc 91%, and display excellent separation of the silver-lead and zinc mineralization. These initial results are vast improvements over the historic recoveries of 85% for lead and zinc and 70% for silver respectively that have been used for internal modeling purposes and will dramatically increase project economics. Furthermore the Company anticipates additional improvements to these positive results with future ongoing test-work.
The work, conducted by Resource Development Inc. of Denver, Colorado, was designed to establish the basic Mineral Processing Plant grinding mill flow sheet, determine the comparative work index of the ore and provide basic flotation test-work in order to optimize eventual saleable concentrate parameters. These early results have been described by Holland and Holland Consultants in the UK as "extremely positive" and "encouraging", for the Magistral resource.
Metallurgical Test Results
Trevali provided a representative composite 'run-of-mine' sample from the Magistral Norte Zone that assayed 4.4 oz (137 g/t) silver, 4.23% lead, 6.07% zinc and 0.14% copper. This sample was subjected to grinding and flotation test-work. The grinding test determined a comparative work index, from which future crushing and grinding requirements can be determined. The flotation tests simulate the liberation of the mineralization from the crushed ore and determines the percentage recovery of each metal to the respective concentrate. The ultimate aim of the mineral processing is to produce saleable silver-lead and zinc concentrates. The flotation tests are critical to the project as high recovery of metal from the ore has an extremely positive effect on project economics by increasing project revenues.
1. Grinding Test
The comparative Bond Ball-Mill Work Index is calculated to be 11.73 at 100 mesh product sizing. This equates to an 'average' ore-hardness typical of the deposit type and will result in conventional milling requirements for the current on-site milling circuit.
2. Flotation Test
Following crushing and grinding the ore is mixed with various reagents in order to liberate or 'float' off the various payable metals. Basic flotation test work was conducted at differing primary grinds in order to examine the differential flotation of the lead-silver and zinc. The preliminary results demonstrate excellent separation of the silver-lead and zinc mineralization with the initial first-pass concentrates showing improved recoveries at finer grinds (P80 - 200 Mesh).
The lead mineralization shows the potential for upgrading to acceptable concentrate grades without re-grinding - returning 40 oz/t (1,250 g/t) silver and 42.6% lead to a concentrate with 84.5% silver and 95% lead recoveries. To put these positive results into context, silver recoveries typically vary from 60 to 85% in this deposit type consequently these results are very significant.
Zinc mineralization shows improved grades and recoveries at finer grinds with an ultimate 91% recovery. However, the test-work indicates that a re-grind is required on the rougher scavenger concentrate ahead of the cleaners to achieve high-grade concentrates at high recoveries. These results are typical for early stage test-work and the Company is highly confident of further positive results from the ongoing work in progress.
Such grades and recoveries are excellent for preliminary test-work results and future test-work will seek to improve upon this.
Finally, the flowsheet presently developed for the flotation circuit and the reagent suite used for the separation is relatively simple which will result in a low operating cost for the overall process plant.
The Company commenced exploration at Santander in November 2007 - and to date has completed 98 diamond drill-holes, discovering three new high-grade silver-lead-zinc replacement and massive sulphide bodies. Most recently, deep drilling has intersected the continuation of all three Magistral bodies to 350 metres vertical depth with mineralization remaining open. Elsewhere, out-cropping high-grade silver mineralization with values up to 17.9 oz (558 g/t silver) at Puajanca is a high-priority drill target.
Substantial site infrastructure at the formerly-producing operation includes a fully refurbished 200-man camp and associated support facilities, an ore processing / concentrator plant (including various crushers, mills, flotation cells and filters) able to produce zinc, lead-silver and copper concentrates that is currently undergoing a refurbishment program, and the Tingo hydroelectric power-station located some 17-km down-valley to the west. The Santander project and the considerable existing infrastructure form a highly strategic asset in this mining district.
Qualified Person and Quality Control/Quality Assurance
EurGeol Dr. Mark D. Cruise, Trevali's President and CEO and a qualified person as defined by National Instrument 43-101, has supervised the preparation of the scientific and technical information that forms the basis for this news release. Dr. Cruise is not independent of the Company, as he is an officer and shareholder.
The metallurgical work programs at Santander were designed by, and are supervised by Holland and Holland Consultants, U.K. who are responsible for all aspects of the work, including the quality control/quality assurance program. On-site personnel at the project rigorously collected and tracked the Magistral Norte composite sample which was security sealed and shipped to Resource Development Inc's Metallurgical Laboratory, Denver, for testwork. Resultant concentrates were security sealed and shipped to ALS Chemex Laboratories, Vancouver, for assay. ALS - Chemex's quality system complies with the requirements for the International Standards ISO 9001:2000 and ISO 17025: 1999. Analytical accuracy and precision are monitored by Trevali's Senior Geochemist via the analysis of reagent blanks, reference material and replicate samples. Quality control is further assured by the use of international and in-house standards. Blind certified reference material is inserted at regular intervals into the sample sequence by Trevali personnel in order to independently assess analytical accuracy. Finally, representative blind duplicate samples are routinely forwarded to an ISO compliant third party laboratory for additional quality control.
About Trevali Resources Corp.
The Company is currently exploring and conducting various scoping level studies on the former Santander polymetallic mine in Peru to ascertain as best as possible the feasibility of re-commencing mining and milling operations in a timely manner upon successful exploration and engineering studies.
The common shares of the Company are currently listed on the CNSX (symbol TV). For further details on the Company readers are referred to the Company's web site (www.trevaliresources.com) and to Canadian regulatory filings on SEDAR at www.sedar.com.
On Behalf of the Board of Directors of
TREVALI RESOURCES CORP.
"Mark D. Cruise" (signed)
Mark D Cruise, President
Steve Stakiw, Manager - Corporate Communications
Phone: (604) 488-1661 / Fax: (604) 408-7499
The CNSX has not reviewed and does not accept responsibility for the adequacy or accuracy of this release.
You can view the Next News item: Wed Dec 3, 2008, Additional silver-rich intersections expand Trevali's Magistral Central sulphide body on the Santander Silver-Lead-Zinc mine project in Peru
You can view the Previous News item: Tue Nov 18, 2008, Trevali defines high-grade tailings at Llacsacocha on Santander Silver-Lead-Zinc mine project in Peru
You can return to the main News page, or press the Back button on your browser.