Since 2010, SRK has been working with Philex Mining Corporation on their Silangan project, located on Mindanao Island in the Philippines. For this copper-gold project, SRK was requested to investigate block caving as the mining method; a particular challenge considering this is a high rainfall area. However, Philex personnel are very knowledgeable about this mining method since they have used it successfully at their Padcal operation.
One of the features of the Silangan ore is its variable mineralogy, where copper can exist as sulphides, carbonates, oxides and silicates. As block caving must balance many aspects to maintain a steady draw-down of ore, it is not easy to mine certain areas selectively and the process is somewhat inflexible in terms of ore blending. Consequently, the Silangan process flowsheet must be developed to handle a wide range of ore types.
To better estimate the impact of mineralogy on process recovery, copper speciation analysis is being included in the resource block model. Copper speciation analysis estimates the relative amount of non-sulphide (acid soluble) and secondary sulphide (cyanide soluble) copper minerals.
In the figure below, the color shaded surface represents the volume of ore contained in one of the Silangan deposits that has a relatively high, acid-soluble copper content. SRK is using Gemcom’s PCBC™ software to simulate the mixing that is expected to occur as the ore is removed from the drawpoint level beneath the caving zone. The white outline (or footprint) of the drawpoint level, as determined by PCBC is also shown.
The combination of block cave simulation with PCBC, along with copper speciation results collected on drillcore samples, will allow SRK to accurately estimate copper and gold composition and performance for a range of ore types. This information allows more detailed economic analysis of the mine scheduling/planning process.
SRK would like to thank Philex for their permission to discuss the Silangan project in this edition of SRK News.
