It is possible to mine an orebody selectively by combining the use of the SSW probe with a quick and inexpensive mining method like the VCR (vertical crater retreat). Thanks to the use of the SSW probe, mining operators will be able to mine orebody's without the dilution that is generally associated to VCR. Already, quick and substantial savings have been obtained.
At their mines in Sudbury and Raglan, Falconbridge have demonstrated that the SSW probe can log nickel, copper and iron sulfides in percussion blast holes. They have raised the grade and reduced dilution by outlining the limits of the ore before selectively loading explosives in the blast holes. By lowering the probe, a profile of the ore content is instantly measured and recorded. Logging cored diamond drill holes at the mine have demonstrated that the ore content (nickel, copper, cobalt, PGM) as assayed is proportional to the intensity of the probe's electromagnetic response (EM), probably because the nickel / pyrrhotite ratio is uniform within a given orebody. The probe also measures the intrinsic conductivity of the sulfides and the percentage of magnetite. All probe readings are displayed and automatically stored at a 10 cm interval within the same reading unit. A 30-meter percussion drill hole takes less than 2 minutes to survey. The whole kit is light (11 kg) and very simple to use. One operator can carry the SSW system and survey either down or up-holes. The probe works from -400 C to +500 C.
Plotting the measurements of the SSW probe in percussion drill holes (2-3-4-6-10 inches diameter) before blasting allows to determine the exact shape of the orebody within the waste and uneconomic low-grade ore. Thus, only the portion of the holes that contains ore is blasted. The dilution is much reduced and, by leaving the waste and low-grade ore in place, the mine saves on transportation, blasting, crushing, backfilling, milling, etc. Thousands of dollars are thus saved. Some savings may also be achieved during the development of stopes by guiding development drifts and by replacing diamond drilling by percussion drilling. In some circonstances, when the probe suggests than some of the rich ore was not drilled-off, additional blast holes before loading explosives can allow to recover pockets of rich ore that otherwise would have been abandoned in the walls of a stope.
