STUDY BENEFICIATION OF NICKEL LATERIT ORE FROM GAG ISLAND THROUGH SULPHIDATION AND FLOTATION

• Main Author: RIDWAN SEPTIAWAN (NIM : 22114022), MUHAMMAD
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/23331
• Institution: Institut Teknologi Bandung

Nickel is a metal which if it is alloyed with iron, chrome and other metals, can be produced as stainless steels that hard, slightly ferromagnetic and good conductors of heat and electricity. Nickel metal in a form of alloy is widely used in industry such as stainless steel, chemical, electroplating, and other metal alloy industries. In nature, nickel is usually mined from two main types of ore, namely sulfide and oxide (laterite) ores. Nickel sulfide ore deposit is estimated about 30% of total nickel deposit in the world and the remaining of 70% is nickel oxide. However, in terms of production, nickel is mostly produced from sulfide ore which is about 60% compared to nickel oxide that is about 40%. Indonesia has laterite nickel deposit about 15,7% of all nickel laterite deposit in the world. Currently, the nickel concentration of the ore is still unsuccessful due to the complexity of ore mineralogy, amorphous structure, association with iron oxide and silicate minerals, equitable distribution of particles and very fine size (up to nanometer size) so that beneficiation is physically difficult to carry out. <br /> <br /> <br /> A recent study involving nickel laterite beneficiation using sulphidation method with sulfur as sulfidizing agent then continued by the flotation concentration process revealed that nickel sulphide can be produced by sulphidation with the requirement of sulphidation of nickel > 80% so that through flotation concentration it is possible to produce nickel concentrate. In addition to sulfur, it is known that sodium sulphate (Na2SO4) could be used as an agent in laterite nickel ore sulphidation to produce nickel sulphide but the flotation concentration process of the sulphidation using Na2SO4 results is still unknown. <br /> <br /> <br /> In this studies, sulphidation of laterite nickel ore from Gag Island using Na2SO4 then continued by the process of flotation concentration was investigated. The effects of temperature, amount of N2SO4 added were studied in this study as influential variables in the sulphidation experiment. The sulphidation temperatures used were 600, 700, 800 and 900oC while the amounts of Na2SO4 added were 5, 10, 15 and 20%. For flotation experiments, they were carried out in two methods. The first was a micro flotation experiment and the second was a lab-scale flotation experiment. Flotation micro experiment was aimed to obtain optimal variables such as pH, collector type, feed size and collector dosage which then they were used in lab-scale flotation experiments. pH used in the flotation experiments were varied from 5-12 with the type of collector used were Sodium Isobutyl Xanthate (SIBX), Dithiophosphate (DTP), Flomin C-7931 (Modified Formate/Ester) and Potassium Amyl Xanthate (PAX). The size of the feed used were varied from -100 +200, -200 +400 and -400 Mesh with collector dosages were also varied from 150, 200, 250 and 300 g/ton of feed. Analyses such as Atomic Absorption Spectroscopy (AAS), X-Ray Flourescence (XRF), X-Ray Diffraction (XRD) and Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) were used to observe the results obtained in this study. <br /> <br /> <br /> The results of experiments showed that the laterite nickel ores from Gag Island contained goethite, hematite, krisotil and quartz minerals with nickel was evenly distributed in the ore. The results of the sulphidation experiments showed that Ni sulphidation (%) increased with increasing sulphidation temperature and the addition of Na2SO4 amount. Ni sulphidation increased from 43.18% at 600oC to 76.00% at 900oC and to 93.73% at 900oC with the addition of 20% Na2SO4. An increase of sulphidation temperature made goethite and hematite were transformed into magnetite thus Ni trapped in the structure of goethite and hematite could be free and reacted with Na2SO4 to form iron-nickel sulfide phase such as pentlandite. An increase in the amount of Na2SO4 added to the briquette increased the sulphidation reaction. The results of the the flotation experiments showed that the nickel content increased from 1.69% in the feed to 2.16% in the concentrate with nickel recovery of 33.20%. The presence of olivine was seemingly a major cause of non-significant nickel flotation recovery obtained due to the olivine coating on the surface and suppressed pentlandite as a nickel sulfide phase in the flotation. Overall, the beneficiation process in this study showed that the nickel content increased from 1.97% to 2.16%.