What is a blast furnace from coal to coke oven?

A blast furnace from coal to coke oven

What is a blast furnace from coal to coke oven: A blast furnace is a type of metallurgical furnace used in the production of iron. 

It is a large, vertical cylindrical structure made of steel and lined with refractory materials.

 The purpose of a blast furnace is to smelt iron ore into iron, which is the primary step in the production of steel.

The process of producing iron in a blast furnace involves several stages, including the preparation of the raw materials and the actual smelting process. 

Here's an overview of the process from coal to coke oven:

Coal Preparation: The first step is the preparation of coal, which is used as a fuel and a reducing agent in the blast furnace. The coal is crushed into small pieces and then heated in the absence of air to remove impurities and volatile components. This process is called coal carbonization.

Coke Production: The carbonized coal, known as coke, is then sent to a coke oven. A coke oven is a large, enclosed chamber where the coal is heated in the absence of air at high temperatures (around 1,000-1,200 degrees Celsius). This process, known as destructive distillation, drives off volatile components and leaves behind a porous, solid mass of coke.

Charging the Blast Furnace: The coke produced in the coke oven, along with iron ore and flux materials, is charged into the top of the blast furnace. Iron ore, usually in the form of iron oxides such as hematite or magnetite, is the primary source of iron. Flux materials, such as limestone, are added to help remove impurities during the smelting process.

Smelting Process: Once the blast furnace is charged, a hot air blast is blown into the furnace through nozzles known as tuyeres located near the bottom. The hot air blast reacts with the coke, generating intense heat and causing the coke to burn. This heat raises the temperature in the furnace to around 2,000 degrees Celsius.

The carbon in the coke acts as a reducing agent, combining with the oxygen in the iron ore to form carbon monoxide. The carbon monoxide then reacts with the iron oxides, reducing them to metallic iron. The molten iron, along with impurities called slag, collects at the bottom of the furnace. The slag is periodically tapped off, while the liquid iron is periodically removed through the tapping hole.

Post-processing: The molten iron produced in the blast furnace is further processed to remove impurities and adjust its composition before being used in steelmaking. This is typically done in a basic oxygen furnace (BOF) or an electric arc furnace (EAF), where the molten iron is refined and converted into steel.

The blast furnace process is a crucial part of the iron and steel industry, providing a primary method for the production of iron on a large scale. It has been widely used for centuries and continues to be a fundamental process in modern steelmaking.

 

 

How Fuel is Baked for the Blast Furnace

coal-chemical coke oven

In the context of a blast furnace, the fuel that is commonly used is coke, which is derived from coal. The process of converting coal into coke involves baking or heating it in a Coke oven. Here's a step-by-step explanation of how the fuel (coal) is baked for the blast furnace:

Coal Preparation: The coal used for coke production is typically high-quality bituminous coal. It undergoes various preparation steps to remove impurities and volatile components. The coal is crushed into small particles and sometimes washed to remove contaminants like sulfur and ash.

Charging the Coke Oven: The prepared coal, known as the coal blend, is charged into a Coke oven. A coke oven is a large, sealed chamber made of refractory materials where the coal undergoes carbonization. The coal is usually charged into the oven through the top using a charging car or conveyor system.

Heating and Carbonization: Once the coal is inside the Coke oven, the oven is sealed to create an airtight environment. Heat is then applied to the oven, raising the temperature to around 1000-1200 degrees Celsius (1832-2192 degrees Fahrenheit). This process is known as destructive distillation or carbonization.

Volatile Component Removal: As the coal is heated, the volatile components, such as water, tar, and gases like methane and hydrogen, are released from the coal and captured for later use. These volatile components are commonly known as coke oven gas.

Coke Formation: The remaining solid carbonaceous material undergoes a process of thermal decomposition, resulting in the formation of coke. The high temperatures cause the coal to lose its volatile components and transform into a porous, solid mass.

Cooling and Quenching: After the carbonization process is complete, the Coke is cooled either by allowing it to cool naturally or by quenching it with water or inert gas. Quenching can help preserve the coke's physical and mechanical properties.

Coke Removal: Once the coke is cooled, the coke oven doors are opened, and the coke is pushed out of the oven using a machine called a coke pusher or by hydraulic systems. The coke is then transported for further processing and storage.

The resulting coke is a solid fuel with high carbon content and low volatile matter. It has desirable properties for use in the blast furnace, such as high carbon strength, porosity, and a high heat value. Coke serves as both a fuel source and a reducing agent in the blast furnace, providing heat and facilitating the reduction of iron ore to iron.