RE:RE:RE:RE:RE:RE:Connecting Otso Gold
The mill throughput has averaged 200tph, an annualised throughput of 1.5Mt. The goal for the plant should to be able to produce the design throughput of 250tph, equating to approximately 2.0 Mtpa. A number of key issues related to the performance of the Process Plant, which has been addressed in the 8x punt have been identified. Capacity of the tailings pumping is restricting feed rate to 200tph/400m3/h. Before getting into Investment/Business Model issues, understanding of these technical issues is important.
Rock hardness: Design capacity of the mill is 250tph. However, the hardness of the rock means capacity is restricted to 150tph. A pre-crusher operated by a contractor could be added to deliver finer material to the mill to allow an increase to 200-210tph.
Grinding capacity : The comminution circuit has insufficient grinding capacity. There is a limitation in the pebble crushing circuit that stops it from crushing the material to the design size of less than 9mm. This results in coarse material being sent back to the AG Mill which then requires additional power to grind further.
Grinding flows : Throughput of the grinding circuit could be significantly improved and the load better balanced between the AG mill and the pebble mill (too much flow to AG mill with spare capacity in the pebble mill).
Crush Forward” approach. : Given the hard nature of the Laiva ore, the most efficient way to reduce the size of the coarse primary crushed ore particles is by crushing them in a crusher rather than by seeking to break them by impact breakage in a tumbling mill; There is spare capacity in the pebble mill crushing circuit; and There is currently a significant recycle load in the AG circuit, whereas the pebble mill circuit has spare capacity (low recirculating load). The concept is therefore to maximise the amount of pebble crushing undertaken, and to move as much of the AG circuit pebble stream – once crushed – forward to the pebble mill. By implementing this scheme, one can expect that it should be possible to achieve the 250 tph target throughput, albeit at the cost of a likely coarser grind size feeding the remainder of the circuit.
Now why is this relevant : From a risk investment perspective , all this means a damn. Coz operational risks in the mine and in the mill is not visible. Thus risks are ridden with uncertainty. Point being made, is risk investor having seen 8 years of operational history of this mine will NOT take a risk exposure on Uncertain, Invisible Risks. Such risks are defined by Management Punts at best to fund agency costs. Risk Investors WILL ONLY INVEST ON VISIBLE RISKS WHICH HAVE CERTAINTY AND WHICH ARE KNOWN PARAMETERS. Visible risks defining certainty are visible over the ground and not under the ground.
Stay tuned for more articles coming up! :)