The Relationship of Grain Size to Nickel Grade at Saprolite Zone of Lateritic Nickel Deposite in Moronopo Site, East Halmahera Regency, North Maluku

Abstract

The research was conducted at the Dinding A and Dinding B, Moronopo Site PT Antam Tbk, East Halmahera, North Maluku which is a block that has been opened for the mining process. Generally the stratigraphy of laterite nickel deposits, from top (young) to bottom (old) consists of overburden, limonite, saprolite and bedrock. The saprolite zone is an economical ore layer for Ni content. This research aims to determine the relationship between grain size of ore and the mineralogy and economical Ni content. The research methods used include the grain size fractionation method with sizes of -5 cm, +5 cm, +10 cm, +15 cm, +20 cm and +25 cm, and XRF analysis to determine the Ni content. The result of this study shows the rocks in the saprolite zone containing minerals such as olivine, serpentine, garnierite and chrysoprase. The XRF analysis result shows the highest Ni content is found in the finest grain fraction (-5 cm) i.e. 2.4% and the lowest Ni content found in the coarsest grain fraction (+25 cm) i.e. 1.87 % but is still classified as economic.