Carbonisation

CARBONISATION

When coal is heated strongly in the absence of air (called destructive distillation) it is converted into lustrous, dense, porous and coherent mass known as coke. This process of converting coal into coke is known as Carbonisation.

Caking coals and coking coals

When coals are heated strongly, the mass becomes soft, plastic and fuses to give a coherent mass. Such type of coals are called Caking Coals.

But if the mass so produced is hard, porous and strong then the coals are called Coking Coals. Coking coals possess lower volatile matter and are used for the manufacture of metallurgical coke.

Thus all coking coals are caking coals but all caking coals are not coking coals.

1. Types of carbonisation

Based on the temperature, used for carbonisation, carbonisation is classified into two types.

1. Low Temperature carbonisation (LTC)

In LTC, carbonisation is carried out at 500 – 700°C.

2. High Temperature carbonisation (HTC)

In HTC, carbonisation is carried out at 900 - 1300°C.

Table 5.2 Differences between LTC and HTC