Cokeless cupola furnace - description of operation

After the ceramic bedding has been fed on the water-cooled grate, the empty furnace is preheated for about 45 minutes. Then the cokeless cupola furnace is loaded with metallic charge and slag-forming constituents.

The hot flue gas of the burner, which runs on natural gas, flows through and overheats the layer of ceramic spheres and ensures that the charge column is thoroughly preheated. Afterwards the exhaust gas is cooled in a gas/air exchanger and cleaned by means of a dry filter. The charge material melts, is overheated while it is in contact with the ceramic bedding and drips into the melting bath. In the siphon, slag and iron are separated.

Using this method the melting process already begins while the furnace is still being filled. Roughly 15 minutes later, the first iron pours out of the siphon into the electrically heated superheater. Here the desired iron temperature is regulated electrically and the composition is adjusted by adding the appropriate alloy.

The use of a gas-fired furnace leads to a considerable reduction in slag compared with a coke-fired furnace. The first slag does not flow until two hours after the melting process has begun. It can harden in slag pots or it can be granulated. The energy source for cokeless cupola furnaces is natural gas (or heating fuel). Consequently, neither will an addition of sulphur happen nor is a desulphurization necessary. The molten iron is particularly suited for the manufacture of nodular cast iron. It is possible to use up to 40 % steel scrap in the manufacture of molten iron.

This cokeless cupola furnace is the result of a decade of development and it has proved its worth as a dependable and economic production aggregate in melting processes in years of use.