Skibum wrote
Regarding your first item......cesl (cominco engineering services ltd) COPPER AND GOLD HYDROMETALLURGICAL EXTRACTION FROM CONCENTRATES In 2007, CESL conducted exploratory tests to investigate copper and gold hydrometallurgical extractions. The tests used the CESL proprietary leaching technology, including pressure oxidation of the copper concentrate followed by pressure cyanidation of the copper leach residue. Two-thirds cleaner bulk copper- molybdenum concentrates produced from the PRA test work, assaying 26.3 and 24.9% copper, were used for the testing. The preliminary tests produced high copper extractions in the range of 96 to 98%, indicating that Schaft Creek copper concentrates were amenable to the CESL process. These copper extractions were achieved at 15 to 30 minutes of retention time as compared to a typical requirement of 60 min normally required for a chalcopyrite concentrate. Pressure cyanidation tests extracted between 89 and 92% of the gold and between 81 and 88% of the silver from the copper leach residue. Sodium cyanide consumption was approximately 3 kg/t due to the high thiocyanate and other metal cyanate compounds formed.
The difference in the recovery rates compared to the BFS is 11% better for copper, 20% better for gold, and 66% better for silver. Plus twice as fast recovery time than normal.
It's been stated that 1% improvement in recoveries would have a large impact on the NPV. Can anybody tally up these differences?
Why was it reported so low in the BFS when tests had already been done. Am I missing something here?
GLTA, canoehead
