HYDROGEN GAS UTILIZATION AS A REDUCING AGENT IN THE FERRONICKEL PRODUCTION PROCESS FROM SAPROLITE NICKEL ORE

• Main Author: Kamal, Fauzan
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/80806
• Institution: Institut Teknologi Bandung

Nickel is one of the metals that has significantly contributed to the advancement of civilization. In 2022, the global nickel consumption reached 3.03 million tons and is predicted to increase annually. Nickel laterite ore dominates the world's nickel resources, accounting for 70% of the total. Nickel laterite ore is divided into two types: saprolite nickel ore and limonite nickel ore. Saprolite nickel ore is generally processed using rotary kiln electric furnace (RKEF) technology which utilizes coal as a reductant then resulting in CO2 emissions. Currently, more environmentally friendly reductants, such as hydrogen gas, are being developed. The use of hydrogen gas as a reductant does not produce CO2 emissions but instead produces water vapor. Additionally, hydrogen gas can be generated through the electrolysis of water. This research aims to further study the use of hydrogen gas in the production process of ferronickel from saprolite nickel ore. A series of experiments have been conducted to investigate the production of ferronickel from saprolite nickel ore using hydrogen gas. The experiments involved the preparation and characterization of saprolite nickel ore samples, reduction of the ore in a horizontal tube furnace (HTF) to produce calcine, melting of the calcine in a vertical tube furnace (VTF), and characterization of the experimental results. The saprolite nickel ore was reduced in the HTF at varying reduction temperatures (500-900°C), reduction times (15-180 minutes), and hydrogen gas percentages (25-100%). The calcine produced from the reduction process was melted in the VTF at 1550°C for two hours under a flow of argon gas to maintain an inert atmosphere. The weight loss after the reduction process was analyzed for each experimental variation. The calcine was analyzed using x-ray diffraction (XRD) to identify the phases formed. The VTF-melted calcine was analyzed using scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) to determine the chemical composition of each phase formed. The experimental results showed that increasing the temperature increased the reduction rate based on the weight loss data after the reduction process which reached 12.92% at a temperature of 900°C. According to the XRD analysis of the calcine, the intensity peak of the ferronickel phase began to be detected at a temperature of 600°C and continued to strengthen with increasing reduction temperature. The iron content in the metal increased in the range of 500-700°C. The reduction rate increased with increasing reduction time, as indicated by the decreasing FeO content in the slag. At a reduction time of 60-180 minutes, the nickel content in the metal approached the nickel content of industrial ferronickel. Increasing the hydrogen gas percentage resulted in a higher reduction rate, as indicated by the decreasing FeO content in the slag. The ferronickel produced with coal and hydrogen gas at 700°C for 60 minutes had similar compositions.