Extraction of Lateritic Nickel Ore

(Hydrometallurgical Route)

Genesis And Types Of Nickel Laterites

Usually, nickel ore type in the world are sulphide and oxide minerals. In East Indonesia, we often see nickel oxide mineral that is called nickel laterite. Lateritic nickel ores formed by intensive tropical weathering of ultramafic rocks above all serpentinites which consist largely of the magnesium silicate serpentine and contains approx. 0,3% nickel. This initial nickel content is strongly enriched in the course of lateritization. Two kinds of lateritic nickel ore have to be distinguished: limonite types and silicate type.
1. Saprolite : Low iron (Fe), contains generally 1.5-2.5% nickel and consists largely of Mg- depleted serpentine in which nickel is incorporated. In pockets and fissures of the serpentinite rock green garnierite can be present in minor quantities, but with high nickel contents – Mostly 20-40%

Picture 1. Garnierite Picture

Picture 2. Serpentine

2. Limonite : High iron (Fe), consist largely of goethite and contain 1-2% nickel incorporated
in goethite.

Picture 3. Goethite

Route of Lateritic Nickel Ore Processing

There are 3 routes of lateritic nickel ore processing:
Pyrometallurgical route
1. Electric Smelting Furnace Technology
2. Krupp Renn Technology
3. Blast Furnace Technology

Hydro-Pyrometallurgical route
1. Caron Process
2. Modified Caron Process

Hydrometallurgical route
1. Atmosferic Leach
2. High Pressure Acid Leach (HPAL)
3. Acid Heap Leach
4. Chloride Leach

Comparation of these processes can be seen in table1.

Table 1. Comparation of Nickel Processing Technology

Experiments still be done by researcher to get the best process for limonitic ores. Until now, Caron Process & modified and HPAL is used by industry to extract nickel from limonitic ores. Flow diagram for Caron Process and HPAL can be seen in Figure 1-3.

Figure 1. Caron Process Flow Diagram

Figure 2. Modified Caron Process Flow Diagram

Figure 3. HPAL Process Flow Diagram