Excellon 2011 AIF NotesLast Fri, Mar 25, Excellon released their 2011 Annual Information Form.
Over the weekend I read through it. These are some notes I made:
EXCELLON RESOURCES INC.
ANNUAL INFORMATION FORM
For the Year Ended December 31, 2010
https://www.stockwatch.com/nocomp/newsit/newsit_sedardoc.aspx?docid=2349391
p.7
Early 2011 exploration drilling is focussed on the Rincon del Caido – 6A/6B Corridor, extending 1.5 km northwest of the 6A/6B Manto, where indications of a proximal environment favourable for the discovery of a large-tonnage deposit were found during 2010.
p.16
In October 2010 Geotech Ltd. of Aurora, Ontario and world leader in airborne electromagnetic geophysical surveying techniques completed a 2,786 line km ZTEM survey at Platosa. The survey covered a large portion of the original Platosa block, almost all of a large concession acquired early in 2010 and a portion of the Sundance Option property. This relatively new type of survey has depth penetration beyond that of most airborne systems and is particularly effective at detecting structures at depth. Structural networks are fundamental controls on the style of CRD being exploited at Platosa and may lead to their proximal source, which is the ultimate object of the Company’s exploration. Final interpreted results of the survey were received in March 2011 at which time Company geologists began ground truthing ZTEM anomalies and planning a drilling campaign.
p.18
Megaw (2002) postulated that these metamorphic and metasomatic fluids related to the deeper-seated portions of this intrusion were dammed below the relatively impermeable Lower Hornfels Formation and were only locally able to ascend into the upper carbonate units along faults and fractures.
p.19
In November 2007, hole EX07-LP422, drilled approximately 250 m northwest of the Guadalupe Manto, intersected marble and felsic intrusive material starting at a depth of 500 m. This was the first time intrusive material had been intersected in drilling on the eastern portion of the property. Excellon and its consultants believe the intrusive is similar to intrusive rocks associated with large-tonnage CRD deposits elsewhere in Mexico and therefore increases the potential to find a large-tonnage source for the Platosa mantos in proximity to the mine. Only limited follow-up drilling has been carried out since 2007 as Excellon concentrated on expanding the high-grade resource near the mine.
p.22
The minimum width for the mineralization used in construction of the
wireframe models was 1.5 m and an NSR incremental cut-off cost of US$86/t was used
p.24
Once a manto has been accessed, mineralized material is mined by a “Pilot and Slash” mining method, using jacklegs. In areas where the width and thickness of the mineralization allows, development and slashing is completed with a single boom jumbo. Depending on the shape and orientation of the manto, the pilot heading can be inclined, declined or flat, to remain in mineralization. Back slashing (breasting), wall slashing, or floor slashing (benching) from the pilot heading may be required to extract all mineralized material. When larger openings are developed, rock bolting has been carried out or a pillar left for support until mining of the area has been completed. Mining to date indicates that the mantos are very irregular in shape and orientation, and are in many cases connected. The ground has been very competent and, in general, very little ground support is required. There has been no problem extracting all the mineralized material (in the mined-out areas). Scott Wilson RPA estimates that dilution is in the order of 10%
p.25
Mineral Processing and Metallurgical Testwork
There is currently no mineral processing carried out at the Platosa site. Excellon crushes the mineralized material to 1/8 inch in a two-stage crushing plant on site and ships it to the beneficially-owned Miguel Auza mill 220 km to the south for processing.
In April 2008 the Excellon Board of Directors approved the construction of an on-site 350 tonne per day flotation concentrator for the production of both silver-lead and silver-zinc concentrates. Final metallurgical testwork and major equipment acquisition were undertaken and largely completed by midOctober. All Mexican government permits required to allow the building of the concentrator and tailings impoundment area were issued in late September and construction began in mid-October. Construction was suspended indefinitely in mid-December 2008 and the suspension remains in effect.