Antimony Oxide Reduction Smelting
Antimony (Sb) and its compounds have been used in a range of industrial products, including paints, enamels, alloys, flame retardants and medicines. Antimony oxide (Sb2O3) is the most commonly used form of the element, but it is notoriously difficult to reduce. Due to its high melting point (1115°C) and low solubility in most reducing atmospheres, it is challenging to effectively smelt antimony without the use of specialised processes or advanced equipment.
In antimony oxide reduction smelting, ore or oxidised antimony is reduced in a furnace at high heat at high temperatures, creating a molten metal, commonly antimony and lead. The furnace is loaded with ore, flux, and reducing agent and heated to working temperatures. The reducing agent, such as coal or coke, is used to reduce the oxide to metal. As the process progresses, the reducing agent reacts with the antimony oxide and converts it to metal antimony which is then able to be recovered from the slag or dross formed during the melt process.
The temperature range required for the reduction of antimony oxide is between 1100 and 1250°C and a range of reducing agents can be used. At higher temperatures, the process is completed much faster but is also substantially more expensive. The main challenge of smelting antimony is that it can form various compounds such as antimony trioxide (Sb2O3), antimony tetraoxide (Sb2O4), and antimony pentaoxide (Sb2O5), which require different conditions to reduce.
Once the reduction process is complete, it is usually followed by chilling to form a slag layer and other processes to remove unwanted impurities. After the reduction process, the antimony is ready for the second process which is commonly known as bead making. Beads are made from the molten metal recovered during the smelting process by rolling them into spheres or “beads”. This process is done to improve the strength, ductility and machinability of the resulting product.
Antimony oxide reduction smelting is a complex and demanding process which requires specialised equipment and a deep understanding of metallurgy. Many of the steps must be performed in an oxygen-free environment, such as a vacuum or in an inert atmosphere of inert gases or shielding gases. In addition, the production environment must also be carefully monitored to maintain the required temperature range, reducing agents and other conditions. The resulting products from antimony oxide reduction smelting can have unique properties and are used in a variety of industries including aerospace, automotive, and medical.
