Parral Tailings Project
Location: Hidalgo del Parral, Chihuahua, Mexico
Status: First Bar Poured; Commercial Production Target Q4 2014
Reserves: 35 Million oz Silver Equivalent (50:1)
The 141 hectare Parral Tailings site is host to 21.3 million tonnes of tailings left over from 340 years of mining operations. Located near the heart of the city, the tailings have become a nuisance to residents and an impediment to development. Fortunately, inefficient historic recovery processes left significant amounts of silver and gold in the tailings which GoGold is now recovering.
GoGold poured its first dore bar at Parral on June 3, 2014. The operation will continue to ramp up to an expected commercial production of 5,000 tonnes per day with an expected average annual yield of 1.2 million oz. silver and 11,000 oz. gold.
As of September 2014, performance had met or exceeded pre-feasibility expectations based on the following performance indicators:†
Capex - Construction completed for approximately $32.5 million versus our pre-feasibility budget of $35 million.
Head Grade - Average increase of 20% over the original resource block model grade of the Red Hill material of 69 g/t Ag (“grams per tonne”) as determined in the Pre-feasibility study. The average resource grade for the mined areas of the block model from the report is 65 g/t Ag. The plant head grade as determined by the plant is currently averaging 83 g/t Ag. This represents a significant increase in recoverable metal early in the project.
Agglomerate Quality - The agglomerate quality has been good and percolation through the heap is occurring within expectations.
Metal Recovery - The silver solution grades have been well within the design parameters which clearly indicate the expected cyanide leaching reaction is occurring. Actual recovery calculations will be done once sufficient amounts of material have been leached and residue samples collected and assayed. All material stacked (195,000 tonnes) is under leach with 300,000 tonnes expected to be under leach by Q4 2014.
Reagent Consumptions - All reagents to date are well within the forecast consumptions for the material being treated. The cyanide, which is the major consumable, has been well below forecasted consumption which should represent significant savings going forward. The main by-product which is leached along with the silver is copper. The amounts of copper leached have been within the expected range and have not overly impacted cyanide consumption.
Dore Quality - The dore produced has averaged 85% silver with minor amounts of gold, copper and zinc. The quality falls within the assay range accepted by the refineries. Dore bars totaling 41,223.34 ounces of silver and 76.46 ounces of gold have already been shipped to the refinery for treatment.
Average Cost per Tonne - Mining and processing has averaged $6.50 - $8.50 per tonne which represents a significant reduction from the pre-feasibility study predicted cost per tonne of $12.
† Source: GoGold PR#17-2014