The two-stage approach was developed through the company’s ongoing expansion definitive feasibility study (DFS) and provides a simple low-capital route to allow gold production from Blackham’s substantial sulphide reserves.
Stage one mining will focus on Blackham’s highest margin reserves and will target 100,000-120,000 ounces a year with costs well below the current free milling operation.
This first stage will focus on the high-grade underground inventory which supports an initial 6-year mine life.
The second stage will be de-risked through stage-one production and will increase throughput to about 250,000 ounces a year via the conversion of the 4-million-ounce reserve
A flotation circuit will be added to produce the 100-120,000 ounces in the first stage, comprising 100,000 ounces of concentrate (about 46,000 tonnes at 70 g/t gold) and about 20,000 ounces of Wiltails processing.
The existing two ball mills and refurbished rod mill combined with the new flotation plan will allow the facility to process 750,000 tonnes per year, with 90% flotation recovery producing around 46,000 tonnes a year of gold concentrate.
Once the second stage has begun, Blackham will incorporate comminution, flotation and leach circuits to lift processing to 2.2-3.3 million tonnes per year.
Second-stage all-in sustaining costs will reduce to about $1,050-$1,150 an ounce.
The Matilda-Wiluna operation has 4.4 million ounces of historical production and four separate large gold systems over 1,440 square kilometres of tenure and 55 kilometres of strike.
The project has resources of 96 million tonnes at 2.2 g/t containing 6.7 million ounces (58% of which is indicated) and reserves of 26 million tonnes at 1.8 g/t for 1.53 million ounces with a plus-10 year mine life.
Calendar year 2018 demonstrated the mine had attained operational stability, producing 78,000 ounces at an all-in sustaining cost of $1,441 an ounce.