New Jersey Mining Company recently announced that efforts to widen the open pit at its Golden Chest Mine project have resulted in a significant expansion, including a 14-fold increase in tonnage and a 12-fold increase in mineable ounces of gold.
The company used blast hole assays, and geologic modeling to test the viability of expanding its open pit mine. Approximately 450 blasthole assays from the current mining operation were used to supplement previous core drilling data to update the block model. The study used current operating costs, metallurgical recoveries achieved at its New Jersey Mill, current concentrate contract terms, and a gold price of $1,200 per ounce.
The study concluded that the pit can be widened further to the west and deepened, with the expanded pit design containing 180,000 tonnes of ore at a gold grade of 4.26 grams per tonne (gpt), totaling 24,600 ounces of gold, with an overall stripping ratio of 5.1 to 1.
An environmental permit for the pit expansion was submitted to the Idaho Department of Lands (IDL) and the company anticipates approval within the next 30 to 60 days.
NJMC President John Swallow stated, “We have clearly moved beyond our initial business plan, which was confined to the limits of existing data and ore already blocked out by prior operators. The over 10-fold increase in the size of our open pit provides a great start to our mine-life expansion efforts and our objective to perpetually have 3 to 5 years of production ahead of us. ”
The Golden Chest gold mine is part of the Coeur d'Alene Mining District and is situated approximately two miles east of Murray, Idaho, US. It is a shallow underground mining operation with potential for open pit mining.
First ore from the mine was produced in November 2014 and delivered to the New Jersey mill for processing in mid-December. Since then, the mill processed approximately 3,500t of ore at an average gold recovery rate of approximately 94%. The first shipment of concentrate to the smelter was made in February 2015.