HYDROGEN GAS AS A REDUCING AGENT FOR IRON EXTRACTION FROM LATERITE NICKEL ORE LEACHING RESIDUE

• Main Author: Qonita Azmi, Ailsa
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/82308
• Institution: Institut Teknologi Bandung

Nickel is utilized globally as a raw material for stainless steel, metal alloys, and batteries. The demand for nickel as a raw material for electric vehicle batteries increases by 30% annually. The precursor material for lithium battery cathodes is nickel sulfate (NiSO4), produced using the high-pressure acid leach (HPAL) process. Additionally, another process under development is step-temperature acid leaching (STAL). HPAL plants can produce 128 tons of dry processing residue (DPR) per ton of nickel produced, necessitating large storage areas. Dry DPR contains approximately 38% Fe, which can be utilized as a raw material for the iron and steel industry. The iron and steel industry typically uses coal as a reductant, leading to CO2 emissions. Therefore, more environmentally friendly reductants, such as hydrogen gas, are being developed. This research is conducted to utilize the leaching residue of laterite nickel ore as a secondary raw material source for the iron and steel industry that is environmentally friendly and carbon-free. A series of experiments involving the preparation and characterization of initial samples, the reduction process in a horizontal tube furnace (HTF), the smelting of calcined solids in a vertical tube furnace (VTF), and the characterization of experimental results have been conducted. The leaching residue of laterite nickel ore is reduced in HTF by varying the reduction temperature between 500-900°C, the reduction duration between 15-150 minutes, and the hydrogen gas composition between 60-93%. The calcined solids produced during the reduction process are smelted in VTF at 1550°C for 120 minutes. Weight loss after the reduction process is calculated to analyze the effect of each parameter. The calcined solids are analyzed using X-ray diffraction (XRD), inductively coupled plasma-mass spectrometry (ICP-MS), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The smelting results of the calcined solids in VTF are analyzed with SEM-EDS to determine the chemical composition of the formed phases. The experimental results showed that increasing the reduction temperature, reduction duration, and hydrogen gas composition increased the reduction level based on the weight loss data after the reduction process and ICP-MS analysis. The iron phase begins to be detected at a temperature of 500°C. According to SEM-EDS analysis, the metal has an iron content of 97.26% at a temperature of 800°C, a duration of60 minutes, and 93% hydrogen gas composition. Increasing the reduction temperature, reduction duration, and hydrogen gas composition reduces the sulfur content in the melted metal. The sulfur content reaches 0% at a temperature of 900°C, a duration of 60 minutes, and 80% hydrogen gas.