Applications of petroleum coke: In downstream industries, the primary use of petroleum coke is in the:

Introduction:
Petroleum coke (green or calcined) is a carbon-rich solid with uses ranging from fuels to critical industrial materials. Understanding its principal market clarifies why refineries invest in delayed coking capacity and calcination facilities. This question asks for the main application associated with petcoke.

Given Data / Assumptions:

• Petcoke grades: fuel-grade and anode-grade (after calcination).
• End-use sectors: aluminium smelting, steelmaking, chemical industries.
• We seek the predominant, high-value use case.

Concept / Approach:
The manufacture of carbon electrodes (particularly anodes for aluminium smelters) is the leading value-added application for suitable petcoke grades. Anode-grade coke is low in metals and sulphur and, after calcination, provides the structural and conductivity properties required for Hall–Héroult cells. While some petcoke is burned as a fuel in cement and power, the question emphasises the primary industrial use beyond simple combustion.

Step-by-Step Solution:

Verification / Alternative check:
Industry reports consistently list aluminium anodes as the dominant non-fuel outlet for higher-quality petcoke, with additional niche uses in graphite electrodes for steel EAFs.

Why Other Options Are Wrong:

• Discoloration of glycerine / sugar refining: Historical adsorbents (e.g., bone char, activated carbon) rather than petcoke in modern practice.
• Blast furnace reductant: Metallurgical coke from coal, not petroleum coke, is the standard BF burden reductant.
• Direct blending into diesel: Not practiced; petcoke is a solid, not a liquid blend component.

Common Pitfalls:
Over-generalising “coke” across petroleum and metallurgical contexts; petcoke’s premium non-fuel pathway is electrode manufacture after calcination.

Final Answer:
Manufacture of carbon electrodes