THE KEY ROLE OF MINERALOGY AND ORE CHEMISTRY IN OPTIMIZING METALLURGICAL PROCESS OF NICKEL LATERITE

PROCEEDINGS PIT IAGI RIAU 2006
The 35^th IAGI Annual Convention and Exhibition
Pekanbaru – Riau, 21 – 22 November 2006

THE KEY ROLE OF MINERALOGY AND ORE CHEMISTRY IN OPTIMIZING
METALLURGICAL PROCESS OF NICKEL LATERITE

Agus Superiadi^1
1Superintendent of Ore Quality Assurance, PT INCO Sorowako, South Sulawesi

ABSTRACT

PT INCO processing plant requires consistent ore feed to maximize its production capacity. The consistency of the feed is really driven by mineralogy and ore chemistry of the nickel laterite ore. To extract nickel from laterite ore, PT Inco is using a pyrometallurgy process to produce nickel matte (78% nickel content). Most of the constraints in the Processing Plant are on Electrical Furnaces where the smelting processes occur to separate nickel matte and slag. The processing plant must produce on- specification Electrical Furnace Slag and also on-specification Electrical Furnace Matte. Ore blending efforts at the mine must focus on producing: 25-28% Ni in matte, 9-10% S and the balance is Fe and also producing slag with 16-20% Fe and 2.05-2.25 SiO2/MgO ratio. The variability of Fe and SiO2/MgO ratio are playing the most important role in controlling the melting point and viscosity of the slag, which is very critical for electrical furnace operation. The olivine content of the ore for electrical furnace feed must also be controlled at minimum level to prevent smelting problem since olivine has very high melting temperature. The precipitated olivine in the slag-matte contact will reduce the heat transfer from the slag to the matte that may also cause tapping/skimming difficulties.

In summary to maximize process plant throughput, the ore chemistry and mineralogy must be controlled in such a way that the ore would be able to melt easily, the furnace wall would be protected, and electrical furnace matte and slag are produced on desired chemistry specification. To achieve this, complete geological knowledge of the ore body particularly on mineralogy and ore chemistry is really important to manage mining, ore blending, and metallurgical processing of the ore.