3 M ODEL AND S ETTINGS
All mining operations are different and any benefits from using ReCYN™ will vary from case to case. As a subset of Whittle Consulting’s Enterprise Optimisation consulting work with PT Agincourt Resources, Whittle Consulting assessed ReCYN™ against a comparable fully-optimised ‘Base Case Optimised Plan’ of current operations. The aim was to provide an indication of the magnitude of financial benefit. 3.1 G LOBAL S ETTINGS All revenue and costs were priced in US Dollars. Given the nature of this document, only selected cost items from the base case and ReCYN™ approach will be discussed. All cost and physical modelling for the ReCYN™ process were based on emails and discussions with Mr. Darryn McClelland, Deputy GM Operations at Agincourt Resources. 3.2 O RE B ODY The mine tested was the Martabe Operations. This operation is situated on the western side of Sumatra Island, in the North Sumatra province in the sub-district of Batangtoru, Indonesia. The mine operational area is centred on the Purnama open-cut mine. This is a conventional carbon-in-leach (CIL) gold ore processing plant with capacity of c5.5 million tonnes of ore per annum. Several neighbouring deposits – Barani, Ramba Joring and Tor Uluala – were also included in both the ‘Base Case Optimised Plan’ and the ‘ReCYN™ Optimised Plan.’ 3.3.1 Revenue All GEOVIA Whittle™ and Prober® modelling was undertaken with Gold at US$1,300 / recovered ounce, Silver at US$19 / recovered ounce and, for the ReCYN™ work where a copper product is made, US$6,061 / tonnes per payable tonne of Copper (97% of recovered Copper assumed payable after sales expenses etc; price based on US$2.75/lb). Cyanide Physicals and Cost Modelling The use of Cyanide, by both the current plant and a more intensive usage in a ReCYN™ process scenario to increase silver recovery, was modelled by calculating consumption across four stages: • Cyanide consumed by copper, calculated based on cyanide-soluble copper ppm in the CIL Feed, and this is available for recovery by the ReCYN™ process • Cyanide consumed by Sulphide Sulphur, calculated based on SXS % in the CIL Feed, and this is NOT available for recovery by the ReCYN™ process • Free Cyanide in CIL Tail, calculated based on tonnage, and this is available for recovery by the ReCYN™ process • Free Cyanide lost in Elution circuit, calculated based on tonnage, and this is a direct loss from the system, NOT recoverable by the ReCYN™ process This free cyanide in CIL tail usage had a more intensive application in the two runs with ReCYN™ schedules. This was used to achieve a reduction in silver in the tailings of 1g/t and consequently heightened recovery, as is discussed overleaf. 3.3.2 3.3 A CTIVITY -B ASED C OSTING (ABC) A PPROACH
ReCYN™ Case Study – Martabe Operations
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