Understanding Coal Testing

Understanding Coal Testing

Coal testing encompasses a range of analytical techniques used to evaluate the properties and composition of coal. These tests are essential for determining coal’s quality, energy potential, and suitability for various applications. Learn more about various definitions associated with Coal/Coke testing and why they are performed.

Gross & Net Calorific Value 

The Calorific Value is a measure of the energy released during the complete combustion of a specified amount of coal. It is expressed in units like kcal/kg, kJ/kg, J/mol, Btu/m³. The Calorific Value is determined using a ‘Bomb Calorimeter’ and is influenced by the coal’s rank and the composition of macerals and minerals.

Proximate Analysis 

This common chemical analysis includes the determination of:

• Moisture: The inherent and extraneous water in coal.
• Volatile Matter: Gaseous fuels released at high temperatures.
• Ash: Inorganic residue after burning.
• Fixed Carbon: Combustible mass remaining after volatile materials are removed.

These factors help ascertain coal’s rank and the ratio of combustible to incombustible constituents, indicating its heating value.

Ultimate Analysis 

The Ultimate Analysis identifies the elemental makeup of coal, including carbon (C)©, hydrogen (H), nitrogen (N), oxygen (O), and sulfur (S). This information is crucial for combustion processes and environmental impact assessments.

Coke Reactivity Test 

This test evaluates the quality of coke produced from coal, assessing its reactivity and strength after reaction. The Coke Reactivity Index (CRI) and Coke Strength after Reaction (CSR) are key metrics derived from this test.

Hard-grove Grindability Index (HGI) 

The HGI measures coal’s resistance to pulverization, indicating the ease of grinding. It is influenced by moisture, ash content, and the coal’s rank and petrographic nature.

Porosity 

Porosity refers to the volume of voids within coal, affecting its surface area and behaviour in processes like coke production and gasification.

Density and Angle of Repose 

These physical properties are important for coal storage and handling, influencing its flow in conveyors and feed hoppers.

Reflectivity 

Reflectivity, or Vitrinite Reflectance, measures coal’s ability to reflect light, providing insights into its rank and coking potential.

Crucible Swelling Index/Free Swelling Index 

This test assesses coal’s caking behaviour, crucial for coke manufacturing.

Ash Fusion Temperature 

Monitoring the behaviour of coal’s ash at high temperatures helps select suitable coals for boilers and other industrial applications.

Chemical Composition of ash

This test is used to ascertain the 'Rank' of coals, and also to establish the ratio of combustible to incombustible constituents. These data give substantial indication about the heating/fuel value of coal, which is a very important indicator in the process of selling and buying of coals.

The primary reason for analyzing coal chemistry is to determine specific application for reservoir characterization especially for gas content and adsorption analyses.

Ash Analysis

Standards:

ASTM D 5865,3171 to 3176, 3180, 1857,5373,4239,6349,3682 IS : all parts of 1350,1355,4433,33, & ISO tests methods.

Instrumentation

• Bomb Calorimeter: Measures the Calorific Value of coal.
• Proximate Analyzer: Estimates moisture, volatile matter, fixed carbon (By difference), and ash content.
• Ash Fusion Tester: Analyses the fusibility of coal’s ash.
• CHNS/Ultimate Analyser:  Estimates Carbon, Hydrogen, Nitrogen,  and Sulphur
• ICP-OES – All major and minor elemental analysis such as – Fe, Al, Ca,Na,K,Mg,Mn,V, Zn, Si,Ba,Ti etc.

Eurofins Spectro’s laboratory is equipped with state-of-the-art instruments and follows stringent standards to provide accurate coal testing services.

Understanding these tests helps companies make informed decisions regarding coal utilization and management.