Improving Coal Washing Efficiency: The Role of Advanced Desliming Screens!

In general, we often consider a coal washing process successful if the desliming consumption is below 0.5 kg/t.

Recently, during a discussion with a friend, he raised an interesting point: typically, a desliming consumption exceeding 0.5 kg/t is not considered successful. This statement touches upon two key themes.

Firstly, there is no absolute standard in most cases. Desliming consumption is closely related to the coal slurry content and its properties. Higher slurry content implies finer particles, increased surface area, and greater difficulty in desliming. If desliming is not properly executed, it significantly raises the amount of material entering the magnetic separation process, resulting in more medium being carried away in the tailings. This is determined by the coal quality. Secondly, he has set his own standard, believing that anything above 0.5 kg/t is not successful. Such statements reflect his values and influence his actions.

Those who do not care or take coal washing processes seriously usually do not set such standards. We should commend these dedicated coal washing professionals.

This year, I visited several coal washing plants, both new and old. The reasons for high desliming consumption are quite similar and typically involve one or more of the following:

• Insufficient preliminary desliming;
• Inadequate desliming screen capacity;
• Lack of water dams on the desliming screen;
• High or easily clogged feed concentration in magnetic separators;
• Inappropriate partitioning.

1. First and foremost, preliminary desliming is essential and must be thorough. The absence of preliminary desliming can lead to high desliming consumption. In some newly designed plants, a common issue is the inadequate area allocated for preliminary desliming. There are two types of preliminary desliming equipment: fixed screens and curved screens. The desliming capacity of fixed screens is significantly affected by slurry content, slurry properties, and screen aperture width, making them suitable for preliminary desliming of lump coal and final coal desliming. For processes that do not require desliming, curved screens are a better fit due to their more stable desliming performance. Adequate preliminary desliming is crucial as insufficient preliminary desliming can result in an excessive amount of suspension entering the desliming screens, leading to increased consumption. Therefore, it is essential to ensure thorough preliminary desliming to improve the processing capacity of the screens. The key lies in preliminary desliming, as thorough preliminary desliming allows for a thicker material layer on the desliming screens, thus reducing desliming consumption. On the contrary, in a certain coal washing plant, due to insufficient preliminary desliming, the desliming consumption exceeded 3 kg/t, serving as a warning.

Another positive example is the XXX Coal Washing Plant, where their preliminary desliming is relatively adequate, and the maintenance of fixed screens is minimal, which is worth promoting.

2. Secondly, insufficient capacity of the desliming screens is usually caused by significant changes in coal quality, such as increased gangue content. Solutions include increasing preliminary desliming, reducing water addition to the medium barrel, increasing water addition to gangue preliminary desliming, and possibly converting single-layer screens into double-layer screens to reduce material layer thickness on the screens. In addition, consider enlarging the screen aperture size of the gangue desliming screen appropriately, but do not exceed 0.75mm to avoid clogging of the magnetic separators.

3. Thirdly, the absence of water dams on the desliming screens is another issue. Although water dams significantly assist in desliming and dewatering, their specific effectiveness can vary depending on the actual situation.

4.Fourthly, high feed concentration in magnetic separators typically occurs in processes that do not involve desliming because nearly all the slurry comes from the magnetic tailings. It is crucial to ensure that the feed concentration to magnetic separators does not exceed the standard.

5.Fifthly, partitioning is the primary means of adjusting the slurry content of the medium, but it needs to be done cautiously. In processes without desliming, moderately increasing partitioning can significantly improve desliming on the desliming screens, but it is essential to ensure an adequate number of magnetic separators.

Additionally, we would like to introduce the advanced desliming screen technology from HOT, which is a leading manufacturer in the field of desliming screens, and our screens offer the following advantages:

• Efficient Desliming: HOT Company's desliming screens are meticulously designed for efficient removal of medium, reducing desliming consumption.
• Water Dams: Each HOT desliming screen is equipped with efficient water dams, ensuring thorough dewatering of materials during processing.
• High Concentration Processing: HOT Company's desliming screens can handle high-concentration feeds, maintaining efficient operation without clogging.
• Customized Solutions: HOT Company provides customized desliming screen solutions to meet the specific needs of different manufacturers.

If you are interested in HOT's desliming screen technology or need more information, please feel free to contact us, and we will be happy to provide you with detailed information and consultation services.

Get in touch:

Tiffany Chen

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