Guyana Goldfields Increasing Production at Aurora Mine

By selectively mining high-grade stopes underground, the Aurora gold mine is expected to increase production to 270,000 oz/y.
Guyana Goldfields has developed an optimized life-of-mine (LOM) plan for its Aurora gold mine in northern Guyana that will increase average annual production from 242,000 ounces per year (oz/y) to 270,000 oz/y for the period 2018 to 2022. The plan is based on increased mineral reserves of 12% after net depletion during 2017 and assumes accelerated selective underground mining of higher-grade stopes concurrent with open-pit operations, along with an expansion of the current processing facility to maintain throughput of 7,500 mt/d when processing hard-rock ore.

Guyana Goldfields President and CEO Scott Caldwell said, “The company is in a strong position financially to fund the underground development and mill expansion internally and looks forward to the immediate advancement of these initiatives to deliver the attractive growth profile that this optimized LOM plan envisages.”

The plan considers mining 43 million metric tons (mt) of ore grading 2.87 g/mt gold. Total recovered gold production over a 16-year mine life is estimated at 3.8 million oz. Production is expected to peak in 2022 at 313,000 oz. Of the 3.8 million oz recovered over the LOM, 1.7 million oz are sourced from open-pit operations and 2.1 million oz are sourced from underground.

The open pit has a mine life of 13 years based on 19 million mt of ore mined at an average grade of 2.74 g/ mt. Approximately 55% of the ore will be sourced from Rory’s Knoll and 30% from Aleck Hill. The remainder will be sourced from the Walcott Hill, Mad Kiss and North Aleck Hill satellite deposits. Mining activity over the near term will be focused on fresh-rock ore at Rory’s Knoll.

Following a two-year preproduction period, underground mining at Rory’s Knoll is expected to be fully ramped up in 2022. Longhole open stoping will initially target higher-grade material below the bottom of the pit. In 2023, the crown pillar will be blasted, and mining will transition to sublevel caving for the remainder of the mine life at an estimated average mining rate of 4,700 mt/d.

An improved mine schedule is expected to provide supplemental feed from satellite deposits later in the mine life. Accelerating underground development is also expected to provide an ideal platform to potentially upgrade and expand the underground resource, especially at East Walcott, where limited historical drilling has produced exceptional results. Initial underground mine development will be conducted primarily by contract mining. An extensive training and development program will allow the transition to a company underground workforce of approximately 80% Guyanese nationals over the life of the underground operations.

The existing process circuit has a capacity for 5,600 mt/d. The proposed expansion to 7,500 mt/d will be completed in two phases. The first phase is nearing completion and is expected to increase the hard-rock throughput rate from 5,600 to 6,600 mt/d. This phase consists of debottlenecking the back end of the circuit and includes the addition of three leach tanks, a pre-leach thickener, carbon management systems, and expansion of the elution circuit. Due to additional retention time within the leaching circuit, the phase one project is expected to increase recoveries by approximately 1% to an estimated average recovery of 92.5%.

The second phase of the expansion will allow the continued processing of 7,500 mt/d of hard-rock ore and is slated for completion by the end of the fourth quarter of 2018. It includes utilization of a pre-crushing circuit and ball mill from a previously purchased 1,000-mt/d modular processing plant. Once completed, the company expects overall gold recovery to significantly increase to approximately 95%. In addition, a significant increase in gravity recoveries results in lower overall reagent consumption. Guyana Gold has awarded the engineering and procurement contract for the phase two mill expansion to JDS Mining.

As featured in Womp 2018 Vol 04 -