Blast Furnace Processing, part 1 of 2: Systems and Components used in Blast Furnaces
How work blast furnaces? How is blast furnace coke used?
Modern blast furnaces are equipped with an array of various supporting facilities which increase total efficiency of processing. One of them is for example an ore storage yard, used for unloading barges. The raw materials are transferred by ore bridges (or transfer cars or rail hoppers) to the stockhouse complex. Computer controlled weight hoppers or rail-mounted scales cars weigh out the various raw materials to yield the desired hot metal and unwanted slag chemistry. The raw materials are brought via a skip car (powered by winches or conveyor belts) to the top of the blast furnace.
There are many different ways in which the raw materials can be charged into the blast furnace. Some furnaces use so called “double bell” systems where two “bells” are used to control the entry of the raw material into the furnace. Two bells are much better than one bell because they minimize the loss of hot gases in the furnace. First the raw materials are emptied into the upper or small bell. The large bell is rotated then a predetermined amount in order to distribute the charge more accurately. The small bell opens then and empties the charge into the large bell. After this the small bell is being closed, sealing the blast furnace, During this sealing process the large bell dispenses the charge into the blast furnace. The most modern designs use a “bell-less” system, which uses multiple hoppers to contain each raw material and discharged it then into the blast furnace through the valves. These valves are more accurate at controlling how much of each constituent is added, as compared to the skip or conveyor system, thereby increasing the efficiency of the furnace. For precise control of the charge place, some of these bell-less systems implement also a chute. And then comes the blast furnace coke.