DOME:-
It consists of a cylindrical steel housing with its interior lined with heat-resistant refractory bricks. After closing, there is a folding door at the bottom where suitable sand bed can be prepared. This sand bed provides suitable refractory bottom for molten metal and coke. Above the sand bed there is a metal hole that will initially be closed with clay known as “bot”. Opposite and above the metal hole is a slag hole where the slag gets trapped. Above the slag hole, there is a wind box that is connected to air blowers. Air enters the dome through the tuyeres. Above the loading platform there is a loading hole through which the load is placed into the dome. The cargo consists of pig iron, scrap, coke and fluxes.
dome furnace diagram Operation:-
First, the hanging door at the bottom is closed. The sand bed sloping towards the tap hole is compacted. A coke bed of suitable height is prepared above the sand bed and ignited through the tap hole. After proper ignition, alternating layers of charge, flux and coke are fed through the charge port. Then the charge is absorbed by heat and the air jet is turned on. Within 5 to 10 minutes, the molten metal is collected through the tap hole. When enough metal is collected in the dome pit, the slag is drained through the slag hole. The molten metal is then collected in the pans and transported to the molds with minimal loss of time.
Fluxes are added to the charge to remove oxides and other impurities present in the metal. The commonly used flux is limestone (CaCO3) in a proportion of 2 to 4% of the metal charge. Other fluxes used are dolomite, sodium carbonate, calcium carbide. The flux reacts with oxides to form lighter, low-melting compounds, so it will float in the pool of metal.
Billing Calculations: –
Carbon:-
When the charge passes through the coke bed, a certain amount of carbon is captured by the metal, depending on the temperature and time the metal is in contact with the coke. It is on the order of 0.15% carbon.
Silicon:-
It is oxidized in the dome and there will be a loss of 10% of silicon. It can reach 30%. To increase the silicon content, ferrosilicon is added to the metal.
Manganese:-
There is a loss of 15 to 20% of manganese during the melting process. The manganese content can be increased by adding ferromanganese.
Sulfur-
There will be a sulfur uptake in the range of 0.03 to 0.05%.
Other ovens:
Other ovens include
- Open fireplace oven
- Rotary kiln
- crucible furnace
- Immersion heated oven
Based on the heating source they can be classified as
