Antilles Gold Ltd (ASX:AAU, OTCQB:ANTMF) has received expressions of interest from two parties about the silver-rich, low arsenic, high antimony concentrate it hopes to produce at the proposed La Demajagua mine in Cuba.
Test work at SGS Laboratories earlier this year indicated that with an ore feed of around 800,000 tonnes per annum in the flotation circuit, a total of approximately 65,000 tonnes of concentrate would be produced.
Valuable antimony
Of this quantity, around 54,000 tonnes would be a gold-rich concentrate with minimal silver content but high arsenic (indicated grades of 38.5 g/t gold, 114 g/t silver, 6.6% antimony, and 29 % arsenic) and around 11,000 tonnes would be a silver-rich concentrate with significantly reduced arsenic, and a high level of valuable antimony (indicated grades of 33% antimony, 28 g/t gold, 1,540 g/t silver and 8.8% arsenic).
In addition, the company has received advice that the antimony content could be increased to more than 40% with refinements to the planned flotation circuit.
Indicative price
The indicative price received for the purchase of the antimony-gold-silver concentrate combined with an offer of around 75% of the value of contained gold in the gold-rich concentrate would increase annual revenue above that set out in the initial scoping study for the project, despite annual plant throughput being reduced by 15% to 800,000 tonnes.
While this is all promising, it still needs to be confirmed by further metallurgical test-work and the finalisation of offtake agreements, which is why a decision was recently made to defer completion of the project’s definitive feasibility study (DFS) until March 2023.
Strategic critical mineral
Executive chairman Brian Johnson said that as a strategic critical metal used in munitions and the manufacture of batteries and semiconductors, antimony was in increasing demand. He said its price had doubled in the past two years.
The potential additional revenue for the La Demajagua project from the antimony content in the silver-rich concentrate is expected to have a positive influence on project profitability, further enhancing the project’s financing options.
The scoping study for the project will be revised in December 2022 and will take into account increased JORC resources since the initial scoping study was published, plus the potential income from the antimony, and an extension of the mine life for the planned first-stage open pit operation, from six to seven years.