Q1: The specific gravity of coal depends mainly on its __________ content.

ANS:D - moisture

Moisture content in coal refers to the amount of water present in the coal sample. It is one of the significant factors affecting the properties and quality of coal. Here's an explanation of the role of moisture content in coal:

1. Presence of Water: Moisture content in coal refers to the water trapped within the coal matrix or present on the surface of coal particles. This water can exist in various forms, including free moisture (on the surface) and inherent moisture (within the coal structure).
2. Effect on Combustion: Moisture in coal affects its combustion characteristics. The presence of moisture reduces the calorific value of coal, as energy is required to evaporate the water during combustion. This leads to decreased efficiency in energy production processes such as power generation.
3. Handling and Transportation: High moisture content in coal can lead to handling and transportation issues. Wet coal tends to be sticky and can cause blockages in conveyors and chutes. Additionally, it increases the risk of spontaneous combustion during storage and transportation.
4. Storage Stability: Moisture content influences the storage stability of coal. Excess moisture can promote microbial growth and contribute to the deterioration of coal quality over time. Proper moisture control is essential to maintain the stability and quality of stored coal.
5. Environmental Impact: Burning coal with high moisture content results in increased emissions of greenhouse gases and pollutants. The combustion of moist coal produces more water vapor, which can contribute to atmospheric moisture levels and impact local weather patterns.
6. Analysis and Quality Assessment: Moisture content is a key parameter in the analysis and quality assessment of coal. It is often measured through laboratory testing methods such as air-drying or oven-drying techniques. Determining the moisture content allows for accurate assessment of coal quality and helps in determining its suitability for various industrial applications.

In summary, moisture content plays a significant role in determining the properties, handling characteristics, combustion behavior, and environmental impact of coal. Controlling and managing moisture content is essential for optimizing coal utilization processes and maintaining quality standards in coal-related industries.