Q1: Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity ?

ANS:D - coke breeze

Coke breeze is a carbonaceous material that is produced during the process of coke manufacturing. It consists of fine particles of coke and is commonly used as a fuel in various industrial processes, particularly in the steel industry. Here's an explanation of coke breeze:

1. Production: Coke breeze is produced during the coke-making process in a coke oven. Coke is a porous, carbon-rich material that is obtained by heating coal in the absence of air to drive off volatile components. During this process, coke is formed as a solid residue, and coke breeze is the fine particles that break off from the larger coke pieces.
2. Composition: Coke breeze primarily consists of carbon, with small amounts of volatile matter, ash, and moisture. It has a porous structure, which provides a large surface area for heat transfer and combustion.
3. Properties:
   • High Carbon Content: Coke breeze is primarily composed of carbon, which gives it a high calorific value and makes it an efficient fuel for combustion processes.
   • Porosity: The porous structure of coke breeze allows for efficient combustion and heat transfer. It provides a large surface area for contact with oxygen during combustion, leading to rapid and complete combustion.
   • Low Volatile Content: Coke breeze has a low volatile content compared to coal, which means it produces fewer emissions during combustion.
   • High Heat Absorptivity: Due to its black color and high carbon content, coke breeze has high absorptivity for radiant energy. This means it can efficiently absorb heat from radiation sources, making it useful in applications where heat absorption is important.
4. Uses: Coke breeze is commonly used as a fuel in various industrial processes, including:
   • Steelmaking: It is used as a fuel and reductant in blast furnaces and other steelmaking processes. Coke breeze provides the necessary heat and carbon for the reduction of iron ore to produce molten iron.
   • Foundry: Coke breeze is used as a fuel and carbon source in foundry operations for melting and casting metals.
   • Other Industrial Applications: It may also be used in other industrial processes where a carbon-rich fuel is required for combustion.

In summary, coke breeze is a carbonaceous material produced during coke manufacturing, primarily composed of carbon with a porous structure. It has high absorptivity for radiant energy and is commonly used as a fuel in steelmaking and other industrial processes requiring a carbon-rich fuel source.