To date, three types of samples have been collected: small (0.2 – 5kg) samples taken from chimneys by the arms of remote operated vehicles; larger sea bed samples (up to 3 tonnes) taken by a grab system in holes up to 5m deep; and drilling samples from sea bed mounds. After splitting these samples on the ship, a proportion of each sample is retained for archive purposes and the balance sent to independent laboratories in Australia for assaying and possible metallurgical testing.
At these laboratories, the samples are dried, crushed to -3.35mm sizes and sub-sampled. Some sub-samples are pulverized and sent on to an internationally accredited assay laboratory for a broad range of elements including copper, lead, zinc, silver and gold.
Other -3.35mm sub-samples are taken to provide bulk composites for subsequent metallurgical testing.
Initial laboratory metallurgical tests have been carried out on bulk samples from some of the discoveries in the Solomon Islands, Tonga and New Zealand.
Conventional sulfide flotation tests in the laboratory have indicated that recoveries between 80% and 95% of the main valuable metals, (copper, zinc, silver and/or gold) in saleable concentrates could be achieved.
As the Company’s samples to date are amenable to conventional sulfide processing plants, it is feasible that Neptune Minerals’ ore could be treated in existing plants.