Furnace Tapping

Furnace tapping or tapping system, also referred to as casting or drainage, which is a process that removes hot metal and slag from submerged arc furnace hearth. Tapping process critically determines in-furnace gas pressure and residual amounts of iron and slag in the hearth.

Furnace tapping is a key operation steps of submerged arc furnace smelting. Firstly, use arc burner or things alike to open tapping hole, and enlarge the hole so than hot metal can flow to ladle smoothly. Secondly, slag can be removed during this process also in form of dry or water slag as depends. And then, closed the tapping hole as soon as finished. Materials and method of tapping hole close are very important.

In submerged arc furnace, liquid metal is produced from processed ores in a continual smelting process. Submerged arc furnace generates heat of over 2000 degrees Celsius in order to melt metals from ores. To reach this temperature, coke is used as fuel. Also, limestone is sometimes added for purpose of bonding impurities. Submerged arc furnace is filled from above in order to build alternating layers of coke and metal ore. The part deeper in SAF has highest temperature. Molten metals flows to bottom with slag floating on top.
Every two hours the furnace is tapped: a tap hole is bored by means of a large drill or arc burner. Out of it flow both slag and glowing yellow molten metal at approximately 1500 ~1700°C. When outflow changes to slag only, tapping hole is closed up again by use of a mudgun.
After tapping, hot metal is transported to casting mold where it is processed into blocks.