AISI 300 SERIES STAINLESS STEEL PRODUCTION FROM NICKEL LATERITIC ORE AND CHROMITE ORE USING HYDROGEN PLASMA SMELTING REDUCTION (HPSR)

• Main Author: Taimullah, Abrar
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/85263
• Institution: Institut Teknologi Bandung

Stainless steel is an alloy with extensive applications due to its superior corrosion resistance and mechanical properties. Conventionally, it is produced through the duplex process utilizing ferronickel (FeNi), ferrochromium (FeCr), and steel scrap as raw materials. FeNi is produced by reducing saprolite nickel ore using carbon through the rotary kiln-electric furnace (RK-EF) technology, and FeCr is produced by reducing chromite ore using carbon in a submerged arc furnace (SAF). Subsequently, these raw materials are melted in an electric arc furnace (EAF) and decarburized using argon-oxygen decarburization (AOD). This conventional process is lengthy and generates significant CO2 emissions due to the use of fossil carbon as a reductant. This study aims to develop a more environmentally friendly method for producing AISI 300 series stainless steel using Hydrogen Plasma Smelting Reduction (HPSR) in a single-stage reduction. The raw materials used in this study are laterite nickel ore and chromite ore. Two methods are employed: thermodynamic calculations using FactSage 8.2 and experimental study using hydrogen plasma smelting reduction. Thermodynamic calculations were conducted using the FactPS, FToxid, and FTmisc databases available in FactSage 8.2. The thermodynamic calculations aim to identify the potential phase formation of the calcined laterite nickel and chromite ore mixture when reduced with hydrogen gas and to compare the calculated results with the experimental outcomes using hydrogen plasma. Experimental studies vary the proportion of chromite ore in the mixture, the total gas flow rate, and the reduction time to examine their effects on the composition of the produced metals and oxides. The chromite ore proportion is varied from 10% to 50% of the mixture. Gas flow rate variations are set at 3, 4, and 5 L/min of H2/Ar gas mixture, and the reduction time is varied from 60 to 240 seconds. All experiments are conducted using hydrogen and argon gases with an H2:Ar ratio of 4:1. The results show that increasing the proportion of chromite ore in the mixture results the higher chromium content and lower nickel content in the metals. Increasing the hydrogen gas flow rate from 3 L/min to 5 L/min produces metal with higher chromium content and oxide with lower chromium content. The composition of AISI 300 series stainless steel is achieved from a mixture containing 30% chromite ore, with a gas flow rate of 5 L/min, and a reduction time of 120 seconds. The chemical composition of the resulting stainless steel is 64.36% Fe, 21.92% Cr, 10.08% Ni, and 0.61% Si. However, the Cr2O3 content in the oxide remains high at 15.52%. The estimated recovery rates for Fe, Cr, and Ni are 90%, 43%, and 100%, respectively. Thermodynamic calculations using FactSage 8.2 show similar trends with the experimental variations, especially at 1800°C. Additionally, the hydrogen requirement for stainless steel production using HPSR can save up to 43% of hydrogen consumption compared to the FactSage 8.2 calculations. This study demonstrates that HPSR technology has significant potential as an environmentally friendly and sustainable alternative for stainless steel production.