The question asks which industry is not classified as a public utility service under the First Schedule of the Industrial Disputes Act, 1947. The options given are:

1. Chemical Fertilizer Industry
2. Pyrites Mining
3. Manufacturing of Alumina and Aluminium
4. Tea Plantation

The Industrial Disputes Act, 1947, is an important piece of legislation in India that aims to ensure industrial peace and harmony by providing machinery and procedures for the investigation and settlement of industrial disputes. Certain industries are classified as public utility services to provide uninterrupted services to the public.

Let's analyze each option:

• Chemical Fertilizer Industry: This industry is often essential for agriculture and is considered a public utility service, as disruptions can impact food security.
• Pyrites Mining: This industry can also be classified under public utility services, given its importance in certain industrial processes.
• Manufacturing of Alumina and Aluminium: This is a critical industry providing materials for other manufacturing processes and thus is considered a public utility service.
• Tea Plantation: While significant for the economy, particularly in specific regions, tea plantations do not fall under the category of essential services requiring classification as public utility services under the Act.

Based on the above analyses, the Tea Plantation industry does not satisfy the criteria for public utility services under the First Schedule of the Industrial Disputes Act, 1947.

Conclusion: Therefore, the correct answer is Tea Plantation, as it is not considered a public utility service under the said Act.