The polymetallic mineralization at the San Vicente Property is present as vertically continuous fault hosted veins, replacements of brecciated faults, and mineralization in dacitic dikes. The mineralized structures are on the order of one to five metres wide, dip moderately to steeply, and trend generally towards the northwest.

The San Vicente Property contains a polymetallic deposit formed by hydrothermal systems associated with repeated calc-alkaline intrusions and their extrusive products forming vein type and disseminated polymetallic deposits. Mineralization in the district is known to cover an area of three by four kilometres to a depth of 300 metres. It consists of replacement veins filling preexisting faults, replacements in brecciated conglomerates in the San Vicente fault, and mineralization in dacitic dikes. Wide veins form in the west-northwest trending structures, with widths of between two and six metres, while veins present in the northwest structures are thinner and shorter. The widest and highest grade veins form in northeast trending faults.

The underground mining method used at San Vicente is primarily long hole open stoping with waste backfill as well as conventional shrinkage stoping. Access to the mine for workers and equipment is provided by ramps and the Pelayo shaft while waste and ore material is brought to the surface using both haul trucks on the ramp and hoisting at the Pelayo shaft. Locomotives are used to move broken ore and waste on the levels in the conventional areas of the mine.

Crushing
The ore is transported from the mine using trucks to a stockpile with a capacity of 5,000 tonnes located next to the crushing plant. The ore is fed into a bin after passing through a static screen with 20 inch openings. Ore from the bin is fed to the crusher by an apron feeder that discharges onto a three inch aperture static screen. Screen oversize is fed to an 800 by 600 millimetre jaw crusher, and the crusher product is combined with the screen undersize and transported by two conveyors 24 inches wide by nine metres and 30 metres long respectively. The crushing circuit product goes to being fed to the grinding circuit.

Grinding
The grinding circuit consists of two stages of grinding to produce a final product of 75% passing 140 mesh (106 microns) that feeds the flotation circuit. The primary grinding is a closed circuit 14 foot diameter by five foot long semi-autogenous grinding mill with a 525 horsepower motor discharging onto a two foot by five foot vibratory screen. The secondary grinding is a nine foot diameter by 14 foot long ball mill with a 525 horsepower motor in closed circuit with a 15 inch diameter hydrocyclone. The secondary grinding product and undersize screen material from the semi-autogenous grinding mill is combined in a box that feeds the hydrocyclone using a pump with a 75 horsepower motor.

The underflow from the hydrocyclone is fed back to the ball mill and the overflow goes to a box passing through an automated sampler before being pumped to the flotation circuit by a horizontal pump of three inches by four inches with a 25 horsepower motor.

The mill flowsheet consists of one-stage crushing, a semi-autogenous grinding/ball mill grinding circuit, and selective flotation followed by filtration of concentrates.

Flotation
The flotation circuit includes an initial stage of depression of sphalerite and pyrite, flotation of silver and lead, followed by cleaning of the silver-lead concentrate and reactivation of the sphalerite to float and clean the zinc-silver concentrate.

The depressants are added in the ball mill, and the flotation of the silver-lead concentrates is conducted in a ten cubic metre flash cell followed by a three metre diameter by three metre high conditioning tank and five 10 cubic metre rougher cells. Cleaning of the silver-lead concentrate is conducted in two stages, each stage in 1.5 cubic metre cells to produce the final silver-lead concentrate, and the cleaning tails are recirculated to the second rougher cell.

The zinc-silver circuit begins with the activation of the s ........