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The Blast Furnace: Zones and Type

Updated on October 24, 2016

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Blast furnace, types, and zones. The picture introduces the topic to be discussed in details for proper comprehension.
Blast furnace, types, and zones. The picture introduces the topic to be discussed in details for proper comprehension. | Source


What is the definition of a blast furnace? In general, blast furnace is a metallurgical heating and smelting machine used in production of metals. It is very essential in metallurgical companies. Blast furnace is of very great help to engineering departments in so many ways as this assists in daily functions of the engineers. It is of very great help in foundry as it is used for heating and melting of iron. It is used in separation of impure materials from parent metals and makes the metals useful to the society. The processes that take place in blast furnace are much and all must be passed through before any valuable element is recovered. I wonder how the world of today would have been without this great machine called blast furnace.

There are many types of blast furnace. The types of blast furnace that are obtainable in the world of today include non-ferrous blast furnace, iron and lead blast furnace.

There are many zones that take place in blast furnace. These zones have the particular time and temperature ranges for their occurrences, that is to say that it depends on the metal to be heated and melted. The four basic zones that take place in blast furnace are the preheating, reaction/reduction/oxidation, combustion and the melting zones.

Zones/Stages in Blast Furnace

The preheating zone in blast furnace occurs at the lower temperature in the furnace chamber. This is the lowest heating zone in furnace as much heat does not partake in it. The preheating stage in blast furnace is dependent on the metal to be smelted. Free water and moisture in the ore to undergo smelting is driven out at this stage and it occurs at the temperature of about 200 degree Celsius in some cases.

The reaction/reduction/oxidation zone occurs at optimal heat and mass transport. The reduction zone occurs mostly in lead blast furnace as heating in the blast furnace occurs through reduction reaction process and oxidation takes place in Iron blast furnace. This zone occurs at high gas velocity and the resistance to gas flow is low. This zone is a radical zone as the movement of gases is high. Reduction of lead oxide to lead begins at relative low temperatures. Oxygen containing lead species requires more intense reducing conditions. Tin as an ore that contains lead can partly be reduced to lead bullion, and the separation of the two components depends on the solubility and the density of the two.

The combustion zone occurs when the coke in the furnace reacts with the oxygen introduced through the tuyeres. Tuyeres are pores on the body of the furnace that allows forcing in of Oxygen and it is a very important part of furnaces. There is release of high amount of heat in combustion reaction, and that is to say that exothermic reaction takes place. The Carbon (IV) Oxide is further reduced to Carbon (II) Oxide when Carbon reacts with Carbon (IV) Oxide.

Melting zone occurs within a limited time. This is the chamber of blast furnace where melting process takes place after the ore had been heated to its melting temperature. Taking lead containing ore for example, the temperature at which the ore melts is at about 1150 degree Celsius.

Lead Blast Furnace as a type of Blast Furnace and the Processes that Occur

What is Lead Blast Furnace as a type of Blast Furnace? In which Processes does it work?

The blast furnace process is regarded as one of the most complicated process in pyrometallurgy because many parameters are involved, and the interaction between the materials in the furnace and gases. Pyrometallurgy involves extraction and purification of metals from their ores by passing them through intense heating. It can also take the form of roasting of the ore. No one can exactly explain what happens in blast furnaces and that is why many researchers have tried in so many ways to use mathematical expressions to explain what goes on in them and it is not new as many reactions that occur in the study of science are shown through the same method.

Lead blast furnace is used in the production of Lead from their ores. It is used in production of Lead by melting the ore when heated to high temperature and the molten Lead separated from its slag. Lead blast furnace is a portable furnace. It has low energy and project capital cost. It is used in production of soft Lead. The furnace generates high pollution and that is why it is situated far from homes and offices. The internal part of lead blast furnace is lined with fire bricks. The fire bricks are used in maintaining constant internal temperature of the furnace. The internal part of lead blast furnace is charged with coke and other raw materials before any extraction of Lead from its scrap takes place. Damaged Lead battery is an example of Lead scraps and Lead can be extracted from them. A similar furnace to lead furnace is the Imperial smelting furnace where the end products are Zinc and Lead.

Preheating zone in lead blast furnace takes place at the temperature of about two hundred degree Celsius. The ore containing the Lead element when introduced into the furnace is preheated to this temperature, either electrically or through any other heat generating process.

At the reduction stage of the furnace, the ore is further heated up to the temperature of about 900 degree Celsius. The ore undergoes reduction process by passing through series of chemical reactions.

The combustion stage in lead blast furnace involves exothermic reaction where the principle element that causes this reaction is Oxygen, which is introduced through the tuyere. Combustion zone is the last stage in lead blast furnace. Finally, the liquid substance (molten Lead) is collected at the furnace crucible and it is located below the tuyere zone.

Note that there are types of lead blast furnace which are round lead blast furnace and rectangular lead blast furnace. The round lead blast furnace is also known as mushroom furnace, while rectangular is also called rachette furnace. Round lead blast furnace is used for low capacity production, while rectangular furnace is used in standard or high production.

Conclusion of the Topic

A blast furnace is a foundry machine used in production of metals from their ores, mostly production of iron and lead. There are types of blast furnace which includes non-ferrous blast furnace and lead blast furnace. The lead blast furnace is further divided into rectangular and mushroom furnace. The zones that are found in blast furnace include preheating, reaction, combustion and melting zones.


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