The primary processing plant (PP1) has a capacity of 1.8 million tonnes per annum (mtpa) and consists of an open circuit jaw crusher, coarse ore stockpile, semi-autogenous grinding (SAG) mill and ball mills, two leach tanks, and six carbon adsorption tanks. A three-stage hard rock crushing circuit was later incorporated which included a fine ore bin and an additional ball mill.
A second processing plant (PP2) with capacity of 1.2mtpa was added in 1996 utilizing the original PP1 jaw crusher and coarse ore stockpile and adding SAG and ball mills, two additional leach tanks and six additional carbon adsorption tanks. In 2004, oxide ore sources were exhausted and the crushing and milling components of PP2 were put on care and maintenance.
Safe and efficient tailings management is key to the Plutonic Gold operations. Over its many years of operation, the Plutonic Gold operations have developed a strong tailings management framework, which aims to minimize risks to the environment and surrounding communities. This includes incorporating evolving international best practices into our systems and processes, quality designs, clear accountability and responsibility, sound dam safety practices, comprehensive risk management, and effective emergency response and preparedness systems.
Tailings from the Plutonic processing plant are sent to a paddock style upstream tailings storage facility (TSF). There are currently three paddock -style tailings storage facilities. TSF one is reclaimed, TSF two and three are in operation. Construction of TSF four is expected to commence in 2022. Plutonic routinely monitors groundwater quality of the area surrounding the TSFs.
Tailings Storage Facility Management Disclosure TSF Management.xlsx (superior-gold.com)
The Plutonic Gold operations has well-established and well-run support infrastructure consistent with an operating mine in an isolated area. Plutonic operates as a fly-in/fly-out operation and maintains a camp on site for employees and contractors. The mine can be accessed by aircraft or by road.
Electricity at Plutonic is generated on-site by means of a 16 MW gas-powered generating station which supplies all power requirements within the vicinity of the camp and processing plant. A backup diesel power station is also maintained.
There are currently three general mining methods used at the Plutonic underground: Long hole retreat mining (the main method applied to the vast majority of stoping); Jumbo stripping (slashing); and Airleg (jackleg) mining.
Underground mining operations are divided into a number of operating regions which include:
The Plutonic Main Pit Preliminary Economic Assessment (PEA) was released in December 2020 and is the largest of the current open pit project at Plutonic.
Robust economics with after-tax Net Present Value (5% discount rate) (“NPV5%”) of AUD$120 million and an after-tax Internal Rate of Return (IRR) of 35% at $2,150 per ounce of gold (US$1,505 per ounce)
Low capital intensity project with only AUD$82 million pre-production capital cost net of AUD$22 million of pre-production revenue.
Average production of 60,000 ounces gold per year over six years for 357,000 ounces of total production.
Low life-of-mine (LOM) All-In Sustaining Cost (AISC) of US$863 per ounce gold.
Technically simple project based on a push-back of the existing Plutonic Main Pit utilising existing processing and other existing infrastructure.
Significant leverage to gold price: AUD$265 million NPV5% at US$2,000 per ounce.
Value enhancement potential available through removing open pit constraints, resource expansion and exploration drilling.
Proceeding to a PFS expected to be completed in the first half of 2022.
Plutonic Main Pit project adds 60,000 ounces per year for six years.