Quality control of coal plays a crucial role, in affecting the product output of businesses.

Coal is widely used in industries such as textiles, food, and the power industry. Understanding the properties of coal is essential for factories before sourcing coal from any supplier. Let's explore the properties of coal with Thuan Hai to establish a basis for identifying the quality of the input fuel.


1. Chemical Composition of Coal

- Carbon: Carbon is the main combustible component in solid fuels, and the heat released when 1 kg of carbon burns is known as the calorific value. The higher the carbon content, the higher the calorific value. Older coal formations have higher carbon content, leading to stronger coal bonds and increased difficulty in combustion.

- Hydrogen: Hydrogen is a crucial combustible component in solid fuels, releasing 144,500 kJ/kg when burned. However, natural coal has limited hydrogen content.


- Sulfur: Sulfur is a combustible component in coal, existing in three forms: organic sulfur (OS), mineral sulfur (MS), and sulfate sulfur (SS). Organic and mineral sulfur can participate in the combustion process, known as sulfur combustion (SC). Sulfate sulfur usually exists as CaSO4, MgSO4, FeSO4, etc. These forms do not participate in the combustion process and turn into ash. To minimize ash formation, low-sulfur coal, such as that found in Cao Son, Nui Beo, Deo Nai, Thong Nhat mines, is preferred.

- Oxygen and Nitrogen: Oxygen (O2) and nitrogen (N2) are inert components in solid and liquid fuels. Their presence reduces the combustible components and lowers the fuel's calorific value. Nitrogen does not participate in combustion and turns into free gas in the smoke, often seen in Indonesian coal (high ash, low heat, with much smoke).

- Ash Content: Ash is the remaining component after coal combustion.

2. Properties of Coal


- Moisture Content (%): Moisture content in coal refers to the water content in the fuel. The total moisture content is determined by drying the fuel in a cabinet at 105°C until the weight no longer changes. In reality, 105°C is insufficient to completely evaporate moisture, typically requiring temperatures of 5000 - 8000°C.

- Ash Content (%): Substances in mineral form in coal turn into ash when burned. The ash ratio significantly affects coal's combustion characteristics, reducing combustible components, lowering coal calorific value, causing heat-absorbing surface tube erosion, and reducing heat transfer through tube walls.

- Volatile Matter (%): When heated in an oxygen-free environment, organic molecule bonds break down, releasing gases such as Hydrogen, Hydrocarbons, Carbon Monoxide, and Carbon Dioxide. This process is called thermal decomposition. The products of thermal decomposition are gases known as "volatile matter" (%).

- Heat Value (Cal/g): The heat value (Q) of coal is the heat released when burning 1 kg of coal completely. Coal is classified based on its calorific value from high to low.

3. Visual Identification of Good Coal


- Not everyone has the specialized knowledge and equipment to assess coal quality. However, through visual characteristics, it is possible to somewhat evaluate coal quality:

  • Touch: Coal leaves a greasy layer on the hand, challenging to wash off.
  • Smell: Burning coal should not emit an unpleasant odor, indicating low sulfur content.
  • Sight: Coal is black and has a shiny appearance.




Follow Thuan Hai

0395 69 79 89