Physiography

TNM Project Area

 

 

Pacific Rim Cobalt’s TNM project area is located close to the provincial capital of Jayapura in a region situated along the south and west slopes of the Cyclops Mountain Range. This prominent physiographic feature in the Cyclops-Sentani area is 40 Km long and 10-15 Km wide and extends from Cape Tanah Merah on the west to Humboldt Bay on the east. On the south and south-west, the slopes are equally steep, but gravels and coarse sediments have accumulated along the toe giving that part of the profile a more gentle contour.

These outwash fans extend southward into an irregular shaped basin occupied by the 25 Km long Lake Sentani, the surface of which is at an elevation of 70 meters. To the south of the lake are numerous smooth, rounded and grassy hills with elevations of 200 to 250 meters. The south slopes of Cyclops have remnants of wave ­cut cliffs and terraces, from 10 to 50 meters above the present lake surface, indicating former and higher lake levels. The Sentani airport is situated on a part of the former lake bed.

The Cyclops Range itself is blanketed with a heavy forest cover down to sea level on the north slopes and almost down to the level of Lake Sentani on the south. All of the Tanah Merah and a part of the TNM laterite areas are covered  with only a light growth of bush and grass. Drainage from the south slopes of Cyclops flows into Lake Sentani and thence to the ocean at Humboldt Bay through the Jafoeri River drainage system. Drainage in the Tablasufa areas is intermittent and passes directly into the sea.

— Geo/. Soc. Malaysia, Bulletin 6, July I 97 3; pp. 309-323

Laterite Formations

Laterites are a type of soil, rich (in this case) with cobalt-bearing nickel ore that formed through prolonged chemical and mechanical weathering in wet, warm, tropical environments. Indonesia contains 12% of the world’s Ni-Co laterite formations. Grades of cobalt in laterite deposits vary widely in the range 0.1 – 1.5% Co.

Cobalt currently mined economically in 4 different geological settings

  • Cobalt is dispersed in silicates and sulphides within the host rock and is remobilized and deposited in weathered layers mainly as hydroxides and oxides near the surface and as silicates at deeper levels
  • Nickeliferous mineral garnierite is formed at deeper levels
  • Grades of cobalt in laterite deposits vary widely in the range 0.1 – 1.5% Co
  • Laterites are mined for nickel with cobalt as a by-product

Processing Options

Smelting (FeNi and Matte)

  • Well proven low risk technology
  • Strong energy dependence

HPAL

  • Proven but high risk technology
  • High capital exposure
  • 85-90% Cobalt recovery

Ni Pig Iron

  • Well proven low risk technology
  • Low capex costs but high operating costs
  • Production will be Ni price dependent
  • Environmental concerns
  • Trend to higher quality product reduces unit cost

Atmospheric Leach

  • Acid-key capital and operating cost driver
  • Capex & Opex – lower than HPAL

Heap Leach

  • Ore type critical for heap permeability
  • Capex & Opex – lower than HPAL

Emerging Technologies

  • Direct Nickel
  • Direct reduction nickel (DRN)