Diagram of cupola
There are two main methods of melting iron. The oldest is through a blast furnace, known as a cupola where a bed of coke is ignited.
Above, where the air comes into the furnace, are layers of coke and metal.
The air is forced into the furnace through vents  ( Tuyeres ) and the oxygen in the air super heats the coke to above 1500 deg. C..
This heat travels up the furnace and melts the layer of metal above the coke.
When the metal melts it flows down through the coke into the well at the bottom.
When one layer of metal is melted the next layer of coke drops down and melts the metal layer above.
This happens continuously with new metal being charged at the top.
Our furnace melts at 3 tonnes/hour.
When there is sufficient metal in the well below the tuyeres it is removed through the tapping hole, flows down a trough and into the ladle.
The tapping hole is then bunged with a piece of clay on the end of a rod, which in turn is removed when more metal is collected.
1997 saw the arrival of a new cupola to replace the original which had celebrated its 40th Birthday.
Environmental controls meant we had to have a water gas scrubber fitted to the top, unfortunately  the existing structure was not strong enough to take the weight.
The cupola is basically just a steel shell with various holes for blast air in, metal and coke in, molten metal and slag out. The new furnace arrived in 3 basic parts and was erected and bolted together, it stands 45 feet into the air with the latter sections lifted into place by a mobile crane.
To stop the shell from melting when the heat is on,  ceramic bricks, forming a circle, are used to line the inside of the furnace building up to form an internal chimney. This in turn is sealed by gannister, a clay and aggregate mixture used to fill the cracks between the bricks.
Metal ,when it is molten, stills weighs the same, so the head pressures can squeeze the liquid through the tiniest of gaps. This can then weaken the outer shell allowing the extremely hot metal to cut through the thin outer shell, like the proverbial hot knife through butter.
So we take all precautions to ensure the furnace is sealed and have an effective method developed in case of emergencies.
Finally. the furnace area was treated to a new roof to shelter the operatives. 
The swelling at the top forms the water spray and collection area, it is accessed by the ladder on the left hand side. The furnace sways in the wind, but the climb to the top allows a good view up and down the valley.
Diagram of electric furnace
Electric melting.
This is more like cooking and gives a greater control of the metal chemistry than with cupola melting. What you put in you can get out, with predictable losses of certain elements. It is more suitable for producing SG and Nickel Irons.
The material is loaded into a ceramic pot. Electrical coils surrounding the pot induce a frequency into the metal causing excitation of the molecules. Temperature increases causing the iron to melt. Cooling water coils surround the pot to stop the coils from melting.
Similar to the cupola the the electric furnace is constructed with an internal chimney and lined with a ceramic powder which is fused into position to form a pot. Our electric furnaces are raised above ground level for ease of filling,  a platform for material storage and instruments surround the furnaces

When the metal has reached the correct chemistry and temperature the whole floor and pot section is tilted forward to pour the metal into ladles attached to craneage. The ladles are then taken to various moulds for casting.