Coal Preparation

Coal preparation process starts with crushing and screening freshly mined coal, removing some of the non-coal material.When it comes to coal preparation, our operators at RPM Solutions bring a deep wealth of mining and machining experience to every project. We differentiate ourselves through our advanced skills and preparation. RPM Solutions’ commitment to detail is the most important component of our success.

Coal preparation is the removal of undesirable material from the run-of-mine (ROM) coal by employing separation processes which are able to differentiate between the physical and surface properties of coal and the impurities. Through proper coal preparation, a uniform product is achieved.

Typical steps in coal preparation include:

  • Crushing
  • Screening into different size factions
  • Physical, chemical or mechanical processing to remove undesired impurities
  • Dewatering
  • Thermal drying
  • Blending
  • Agglomeration

With coal preparation, raw coal is cleaned using different physical processes, with or without any chemical reagents, to get a product which can be sold in the market. Coal preparation process starts with crushing and screening of freshly mined coal, which removes some of the non-coal material. Washing is actually the process of separation of non-coal materials. Washing or cleaning of coal represents the most important step of coal preparation. Coal is washed in order to decrease the ash content and thus producing three different streams of products: clean coal, middlings and rejects. The raw run-of-mine (ROM) coal requires some selective qualitative and quantitative analysis to determine the most suitable operating condition for cleaning of coal to obtain the desired quality.

Reasons for cleaning coal are to:

  • Remove inorganic material (ash) – thus reducing ash handling in coal plants
  • Increase the heating value of coal
  • Reduce the transportation cost per unit weight of coal
  • Meet customers’ specifications

There are four basic types of operations used when cleaning the coal:

  • Comminution | this is the stage where coal lumps are converted into small manageable sizes so that they can be processed by different equipment.
  • Sizing | the separation of coal into products characterized by differences in size. This can be accomplished by screening or by classifying. Generally, the medium used is water.
  • Concentration | once coal is classified into different size fractions, each size fraction is subjected to different unit operations for cleaning. These processes divide coal into the following three categories:
    • Clean coal – having ash content approximately 7 – 9%
    • Middlings – having ash content approximately 25 – 30%
    • Rejects – having ash content approximately 65 – 70%
  • Dewatering | Coal preparation is carried out in water and much moisture is added into the system. The total moisture content of the final coal product is a major quality control factor and the removal of moisture from both the coarse and the fine coal are serious technical issues.

Why coal preparation is so important:

  • Remove extraneous, non-combustible material
    • Ash reduction
    • Lower particulates
    • Reduced ash handling at power station
    • Sulfur reduction
    • Carbon emission reduction
  • Reduced transportation costs per unit of heat
  • Guaranteed consistent heat value
    • Improved plant efficiency

The efficiency of a coal preparation plant has a major impact on the profitability of a mining operation. RPM Solutions provides a range of technical services to help you optimize efficiency and improve your bottom line performance. For more information about putting the services of RPM Solutions to work regarding effective coal preparation, contact us at