Structural Components
Furnace Body/Shell: The main, often cylindrical, structure that contains the smelting process.
Water Jackets: High-conductivity copper or steel water jackets often make up the walls and shaft of the furnace.
Refractory Lining: A protective lining of fire bricks or similar materials is used, especially in the hearth area.
Tuyeres (Side Blowers): Multiple nozzles are positioned along the sides of the furnace, typically arranged in layers, to inject high-purity, oxygen-enriched air horizontally into the molten bath.
Hearth & Molten Pool: The bottom part of the furnace where the molten metal (matte/bullion) and slag layers separate due to density differences.
Charging Port: An inlet, usually located on the top or side of the furnace, where raw materials (concentrates, fluxes, reductants) are continuously fed.
Tapping Spouts (Tap-holes):
Metal Outlet: A lower tap-hole or siphon is used for continuously or intermittently drawing off the dense molten metal (e.g., lead bullion, copper matte) that settles at the bottom.
Slag Outlet: A separate tap-hole at a higher elevation is used to remove the less dense molten slag that floats on top.
Off-Gas System: A crucial exhaust system located on the furnace roof.
Operating Principle
The core principle involves vigorous stirring and efficient combustion within a molten bath.
Oxygen Enrichment: Air with a high concentration of oxygen (up to or exceeding 70%) is used instead of normal air. This increases combustion efficiency, rapidly raises the internal temperature, and accelerates reaction times.
Side Blowing: The oxygen-enriched air is injected horizontally through tuyeres positioned on the sides of the furnace, below the surface of the molten material. This creates intense agitation and ensures thorough mixing of gases with the molten metal and slag, promoting uniform and complete chemical reactions.
Reactions: The injected oxygen reacts with impurities (e.g., sulfur and carbon) and fuel, forming oxides that are removed as slag or exit as high-concentration SO2 off-gas, suitable for acid production.
Phase Separation: The process allows for quick separation into distinct layers: dense molten metal/matte settles at the bottom and a less dense slag layer floats above it. These are then tapped separately from different elevations.
Features and Benefits
High Efficiency and Productivity: The enhanced combustion leads to faster reaction rates and higher throughput, significantly reducing the time required for smelting and refining processes.
Energy Savings: Improved thermal efficiency reduces overall fuel consumption required to reach desired temperatures, lowering operational costs and energy consumption.
Environmental Performance: The process minimizes fugitive emissions due to enclosed design and effectively captures high-concentration SO2 off-gas for further use (e.g., in sulfuric acid plants). Full combustion of off-gases helps reduce pollutants like dioxins and carbon monoxide.
Flexibility and Control: The furnace can process a wide variety of raw materials, including concentrates, scrap, and residues with varying moisture content. Operators have precise control over oxygen levels and injection rates to optimize performance for different materials.
High Metal Recovery: The intense mixing and efficient reactions result in better impurity removal and high recovery rates of valuable metals like copper, lead, nickel, and zinc.
Application of Furnace
Oxygen-enriched side-blown furnace technology is widely applied in the non-ferrous metallurgical industry:
Copper Smelting and Refining: Used for producing high-purity copper from various copper ores and electronic waste.
Lead and Nickel Production: Efficient for the primary production and recycling of lead (e.g., from lead-acid batteries) and nickel.
Secondary Metal Processing: Suitable for processing a wide range of secondary and recycled materials due to its flexibility.
Zinc Leaching Residue Treatment: Has proven effective in treating zinc-containing residues, achieving high recovery rates for valuable metals.
Refractory Bricks for Furnace
The selection of refractory bricks for the core structure of an oxygen-enriched side-blown furnace is primarily based on the temperature, melt erosion intensity, and scouring degree of each location, as follows:
Heart (including copper tapping and slag tapping areas): Semi-rebonded magnesia-chrome bricks, electrofused magnesia-chrome bricks (prioritized near the slag tapping area).
Furnace body (reaction zone, slag chamber): Directly bonded magnesia-chrome bricks, electrofused magnesia-chrome bricks (lower reaction zone).
Furnace top and charging port: High-alumina bricks (Al₂O₃≥75%), clay bricks (upper low-temperature zone).
Flue system (horizontal flue, rising flue): Directly bonded magnesia-chrome bricks (near the furnace body), high-alumina bricks or sillimanite bricks (far-end flue).
Special areas (copper water jacket inlay area): Wedge-shaped magnesia-chrome bricks, corundum refractory bricks.
