Theta Gold Mines Ltd (ASX:TGM) has passed a key milestone with the successful completion of trial mining at its TGME Gold Project in South Africa, which it describes as a "critical de-risking event".
Trial mining confirms that long hole mechanised mining and 15-metre-long mining panels are suitable to mine the narrow gold reef system (0.60-6.0 metres) present across the TGME goldfields.
Promisingly, this demonstrated a cost reduction with the redesign of the drilling and blasting systems to achieve optimal fragmentation.
“Major milestone”
Theta chairman Bill Guy said: “Successful trial mining at TGME is a critical de-risking event and major milestone for Theta as it confirms that long hole mechanised mining methods can effectively mine these large tabular shallow dipping (3-7 degrees) narrow gold reef systems.
“The reef varies greatly in thickness from 0.24 metres to 6 metres.
"The ability to mine at 0.6 metres or narrower means reduced dilution and delivery of a higher ore grade to the plant.
“As the reef system is tabular, the Beta and CDM combined complex strikes over 8.2 kilometres with a downdip extension of more than 2,500 metres.”
Trial mining
Trial mining at Frankfort is now complete, with the Beta, Frankfort and CDM mines, all of which form part of the Central Northern Area, collectively referred to as the TGME Underground (UG) Project.
The project that started in September 2021 focused on rock engineering and mine support systems, drilling and blasting technics as well as cleaning of broken ore in support of a definitive feasibility study being prepared by Minxcon for delivery in the March quarter of 2022.
A total of 34 horizontal blast holes were drilled at various lengths across the span of the trial mining block; 85% of blasted rocks were cast into the cleaning drive.
Importantly, the rock engineering support system performed to the expected specifications with gold-bearing ore extracted with minimal dilution from the foot or hanging wall
As part of the ongoing trial mining within the project scope, investigations were undertaken in accessing suitable equipment to allow for bulk gravity gold sampling for exploration work in targeted areas across the concession.
Long holes drilled during the trial mining.
“Reduced costs”
Guy adds: “The trial mining has assisted with confirming initial costs and mine design.
"The reef is relatively soft in relation to the surrounding host rock, reducing anticipated drilling and explosive costs.
“The competence of the host sedimentary rock was again experienced as no uncontrolled fall of ground took place during the blasting operations, as observed in other parts of the mine where excavations mined over 100 years ago are still standing up.”
Forward plan
Both the Phase 1 underground DFS and Rietfontein PFS is ongoing and progressing well with the expected completion of the PFS by end of December 2021 and a DFS by the first quarter of 2022 respectively.
Guy adds: “The next two quarters will deliver exciting news as the Rietfontein PFS, TGME underground DFS together with an updated JORC (2012) resource statement will be completed.
“Underground sampling, bulk gravity gold sampling and further metallurgical test-work continue throughout Christmas and New Year into 2022.”