STUDY ON THE EFFECT OF FLUX ON NICKEL SAPROLITE OREWITH VARIOUS SIO2/MGO RATIOS ON THE INTERACTIONBETWEEN SLAG AND REFRACTORY

• Main Author: Khusnaini Permata P, Nandhya
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/73107
• Institution: Institut Teknologi Bandung

The utilization of nickel in various sectors and Indonesia's significant nickel reserves make nickel processing highly beneficial. One of the pyrometallurgical routes for extracting nickel from lateritic nickel ores is the Rotary Kiln Electric Furnace (RKEF) technology. However, a current challenge is the availability of ore with a suitable SiO2/MgO ratio under 2 that does not cause adverse interactions between the slag and refractories. The addition of additives is one alternative to reduce this issue. This research aims to study the interaction mechanisms between slag and refractories, investigate the influence of additive addition, and explore the phases formed during the interaction between slag and refractories. The experiment in this study begins with the preparation and characterization of nickel ore, coal, and flux. Next, nickel ore, coal, and flux are placed in a horizontal tube furnace at a temperature of 800°C for 3 hours under inert conditions with argon to simulate the partial reduction stage in the rotary kiln. The mixture is then formed into briquettes and placed into a cup-shaped refractory, which is melted in a vertical tube furnace at a temperature of 1550°C for 2 hours under inert conditions with argon to simulate the smelting stage in the electric furnace. The resulting slag and refractories from the smelting process are analyzed using scanning electron microscopy-electron dispersive spectroscopy (SEM-EDS). The smelting results with an SiO2/MgO ore ratio of 2.36 and final slag ratios of CaO/MgO of 0.08 and 0.91 indicate the formation of olivine phase at the interface between slag and refractory. The final slag ratio of CaO/MgO of 0.88, 2.30, and 2.48 indicates that the slag is only in equilibrium with monoxide (refractory). The smelting results with an SiO2/MgO ore ratio of 3.02 and final slag ratios of CaO/MgO of 0.09, 0.11, 0.29, and 0.89 indicate the formation of olivine phase at the interface between the slag and refractory. The final slag ratio of CaO/MgO of 3.96 indicates that the slag is in equilibrium with monoxide (refractory). Olivine phase at the interface between slag and refractory can form a protective layer that can protect the refractory from interactions with the slag. From the experimental results, it is known that the interaction between slag and refractories will cease when the slag is saturated or unable to dissolve MgO further from both the additives and the refractories. Increasing the Al2O3 content in the slag and reducing the melting temperature result in quicker saturation of the slag, and it will not interact significantly with the refractories. The addition of MgO flux is considered more effective than the addition of CaO flux.