Carbonisation of Coal – Product from 500° to 700°C (Low-Temperature Range) When coal is carbonised in the lower temperature range of about 500° to 700°C in limited air, the product formed is commonly called soft coke (low-temperature coke).

Introduction / Context:
Coal carbonisation temperature directly controls the nature of the coke produced. Industrial practice distinguishes low-temperature carbonisation (domestic or soft coke) from high-temperature carbonisation (metallurgical or hard coke), each suited to different applications.

Given Data / Assumptions:

• Carbonisation range: about 500°–700°C.
• Oxygen-limited (destructive distillation) environment.
• Objective: identify the principal solid product name.

Concept / Approach:

At 500°–700°C, coal releases volatiles but not as completely as at higher temperatures. The resulting coke retains more volatile matter, is more reactive, and is mechanically weaker, hence called soft coke. By contrast, hard (metallurgical) coke is produced at roughly 900°–1100°C and has higher strength and lower volatile content, appropriate for blast furnace use.

Step-by-Step Solution:

Verification / Alternative check:

Materials and fuel handbooks consistently classify 500°–700°C carbonisation yields as soft coke with higher volatiles, suitable for domestic heating or gas production by-products.

Why Other Options Are Wrong:

Hard coke requires ~900°–1100°C. Pulverised coal is not a product of carbonisation. Bituminous and anthracite are starting coal ranks, not outcomes of this process.

Common Pitfalls:

Confusing coal rank (geological) with coke type (process outcome); assuming higher temperature always better without considering end-use requirements.

Final Answer:

soft coke