Why Should Coal Be Washed?

Why Should Coal Be Washed? Coal from coal mine is a complex material mixture with multiple physical properties. In addition to coal itself, this mixture also contains rocks, sand and various minerals. Therefore, coal must be cleaned before being sold to consumers. The cleaning process includes a series of steps, and finally produces products that are particularly suitable for specific consumer needs. The earliest of these steps is crushing and sorting. These two processes can reduce coal to the form required by consumers.

The coal washing plant has improved the coal washing process and quality, thereby increasing the price. Coal washing technology also helps reduce emissions from combustion.

Coal Washing Machine

How to wash coal?

There are two main coal preparation methods, one is density separation and the other is froth flotation. Both processes depend on the fact that the particles from which the coal sample is made have different densities. For example, when water is added to the sample, the particles will sink to different depths according to their density. In this way, the various components of the sample can be separated from each other.

Coal cleaning is a process by which impurities such as sulfur, ash, and rock are removed from coal to upgrade its value. Coal cleaning processes are categorized as either physical cleaning or chemical cleaning. Physical coal cleaning processes, the mechanical separation of coal from its contaminants using differences in density, are by far the major processes in use today. Chemical coal cleaning processes are currently being developed, but their performance and cost are undetermined at this time. Therefore, chemical processes are not included in this discussion.

The scheme used in physical coal cleaning processes varies among coal cleaning plants but can generally be divided into four basic phases: initial preparation, fine coal processing, coarse coal processing, and final preparation.

In the initial preparation phase of coal cleaning, the raw coal is unloaded, stored, conveyed, crushed, and classified by screening into coarse and fine coal fractions. The size fractions are then conveyed to their respective cleaning processes.

Fine coal processing and coarse coal processing use similar operations and equipment to separate the contaminants. The primary difference is the severity of operating parameters. The majority of coal cleaning processes use upward currents or pulses of a fluid such as water to fluidize a bed of crushed coal and impurities. The lighter coal particles rise and are removed from the top of the bed. The heavier impurities are removed from the bottom. Coal cleaned in the wet processes then must be dried in the final preparation processes.

Final preparation processes are used to remove moisture from coal, thereby reducing freezing problems and weight and raising the heating value. The first processing step is dewatering, in which a major portion of the water is removed by the use of screens, thickeners, and cyclones. The second step is normally thermal drying, achieved by any one of three dryer types: fluidized bed, flash, and multilouvered. In the fluidized bed dryer, the coal is suspended and dried above a perforated plate by rising hot gases. In the flash dryer, coal is fed into a stream of hot gases for instantaneous drying.

The dried coal and wet gases are both drawn up a drying column and into a cyclone for separation. In the multilouvered dryer, hot gases are passed through a falling curtain of coal, which is then raised by flights of a specially designed conveyor.

Purpose of coal washing equipment:

1. Reduce water and energy-intensive coal production

The coal washing program includes factory installation and independent modules to optimize beneficiation capacity. In other words, this means maximizing the ore recovery rate while using less water, energy or other consumables in the process.

Another important feature is water conservation. By enhancing water conservation, zero discharge of wastewater and reducing carbon emissions, this solution helps to achieve a more sustainable process.

2. A more sustainable process helps reduce operating costs

To meet the needs of customers for greater flexibility and efficiency in terms of sustainability. Our philosophy is to provide comprehensive solutions for the industry.

Structural characteristics of coal washer:

1. Standard length valve body can be used, and the combined shape can be selected according to needs.

2. Coal washing technology-the use of CNC pneumatic valve, high degree of automation of coal washing.

3. Coal preparation method-double-amplitude pulsed water flow, good bed stratification effect and high clean coal yield.

We are a coal washing equipment supplier. If you are interested in our products, please contact us now!