Why is a blast furnace called a blast furnace and not a furnace or fire furnace?

Answer 1

The basic concept of a blast furnace hasn't changed in more than 100 yrs. Modern furnaces are of course more complex due to newer technologies. First of all the furnace is basically a steel tank, inside it is lined with brick or gunite. The outside shell is protected from the heat by hundreds of "coolers" which are located around the entire furnace. Coolers are usually made from copper and have water inlets and outlets; water does not enter the inside of the furnace but is circulated in a closed loop system through a network of piping. At the bottom of the furnace are openings called tuyeres (ta-weers) through which hot air is blown into the furnace. The tuyeres are connected to a large brick-lined pipe called a bustle pipe. The bustle pipe is connected to a series of very large stoves. Outside air is fed into the stoves where it is heated. The heated air is then blown into the bustle pipe, through the tuyeres and into the furnace. The tuyeres can also be piped to allow the use of oxygen, pulverized coal, and natural gas to enhance the heat.

Raw material is loaded into the top of the furnace by conveyor or a skip car which runs on a track pulled by cables. The raw materials are iron ore, limestone, coke and alloys chosen by the steelmaker. At the bottom of the furnace is an opening called the tap hole. The tap hole is plugged by a machine called a mud gun, the mud gun is loaded by hand with "mud" which is a high grade refractory that does not melt under the intense heat.

After the materials reach the desired temp (usually about 3500 deg F) another machine called a tap drill drills out the mud to let the molten metal out of the furnace; this is known as "casting". Molten metal and slag are separated by a series of channels, slag (girl) will flow to a pit or slag car to be carried away. The slag is cooled to be used in a variety products such as an additive in concrete. The metal is channeled to bottle cars to be transported to different areas of the mill for processing.

This is a very basic overview of a blast furnace, they are highly complex and very dangerous!

Answer 2

Extracting iron from iron ore using a Blast Furnace

Introduction

The common ores of iron are both iron oxides, and these can be reduced to iron by heating them with carbon in the form of coke. Coke is produced by heating coal in the absence of air.

Coke is cheap and provides both the reducing agent for the reaction and also the heat source - as you will see below.

Iron ores

The most commonly used iron ores are haematite(US: hematite), Fe2O3, and magnetite, Fe3O4.

The Blast Furnace

The heat source

The air blown into the bottom of the furnace is heated using the hot waste gases from the top. Heat energy is valuable, and it is important not to waste any.

The coke (essentially impure carbon) burns in the blast of hot air to form carbon dioxide - a strongly exothermic reaction. This reaction is the main source of heat in the furnace.

The reduction of the ore

At the high temperature at the bottom of the furnace, carbon dioxide reacts with carbon to produce carbon monoxide.

It is the carbon monoxide which is the main reducing agent in the furnace.

In the hotter parts of the furnace, the carbon itself also acts as a reducing agent. Notice that at these temperatures, the other product of the reaction is carbon monoxide, not carbon dioxide.

The temperature of the furnace is hot enough to melt the iron which trickles down to the bottom where it can be tapped off.

The function of the limestone

Iron ore isn't pure iron oxide - it also contains an assortment of rocky material. This wouldn't melt at the temperature of the furnace, and would eventually clog it up. The limestone is added to convert this into slag which melts and runs to the bottom.

The heat of the furnace decomposes the limestone to give calcium oxide.

This is an endothermic reaction, absorbing heat from the furnace. It is therefore important not to add too much limestone because it would otherwise cool the furnace.

Calcium oxide is a basic oxide and reacts with acidic oxides such as silicon dioxide present in the rock. Calcium oxide reacts with silicon dioxide to give calcium silicate.

The calcium silicate melts and runs down through the furnace to form a layer on top of the molten iron. It can be tapped off from time to time as slag.

Slag is used in road making and as "slag cement"

Answer 3

The ingredients that go into a blast furnace are:

• Iron oxide
• Coke (carbon)
• Limestone (calcium carbonate)
• Air (for oxygen)

Several reactions occur:

1. 2 C + O2 --> 2 CO
2. 3 CO + Fe2O3 --> 2 Fe + 3 CO2
3. Excess carbon alloys with the iron, forming cast iron.
4. The limestone melts acting as a flux, collecting impurities forming slag.

Answer 4

It is because hot air is literally blasted in through the bottom of the furnace.

Answer 5

because hot air is coming through the bottom

Answer 6

Iron put in blast furnace from its refining

Answer 7

How_Does_A_Blast_Furnace_Work

Answer 8

to burn the coke

Answer 9

because it blows hot air in it.