Nippon Dragon’s thermal fragmentation tech gets to work at Rocmec 1

Nippon Dragon Resources says it is using its thermal fragmentation technology on the Talus vein at its Rocmec 1 gold mine, in Quebec, Canada.

In a progress report this week, Nippon Dragon said thermal fragmentation operations had begun on the Talus vein – “probably a secondary sub parallel branch structure to the McDowell vein”, the company says – where grades range from 0.03-61.58 g/t Au and widths vary from 0.05-3.04 m, according to sampling.

Alongside this, the company said development of a raise and a sub-level on level 39 within the Talus mineralised structure had started from level 50. At the same time, development of two drifts in the mineralised vein on level 50 of the McDowell structure, which has the longest gold-bearing structure on the property, had begun.

It added: “Employee training on the thermal fragmentation units continues in an accelerated mode.”

Nippon has an exclusive licence for the thermal fragmentation mining process for narrow vein mining. The process involves drilling a series of 6 in (15 cm) pilot holes into the vein with a conventional drill. Thermal fragmentation (thermal head, compressed air and water) is then inserted and spalls the rock, quickly increasing the diameter of the hole to 30-110 cm. After this, ore can be extracted in 0-13 mm fragments. The leftover rock between fragmented holes is then broken to recover the remaining ore.

This precision allows for the extraction of high-grade precious and base metal veins without dilution, according to Nippon.

To date, Nippon Dragon has invested approximately C$33 million ($25 million) in rehabilitating the Rocmec 1 property, surface and underground infrastructure, diamond drilling, equipment and drifting. The property includes a 100 m deep two compartment shaft, an 844 m decline allowing access to five levels (50, 70, 90, 110 and 130 m). On these levels, a total of 1,700 m (drifts and cross-cut drifts) were driven.

A 2010 NI 43-101 report by SGS using a cutoff grade of 3 g/t Au reported a measured and indicated mineral resources of 570,300 t grading 6.52 g/t for 119,500 oz of gold and 1.51 Mt of inferred resources at 7.4 g/t Au for 359,600 oz of gold.