How to Control Dust in Coal Crusher
Coal -- An important resource
As one of the most important resources in nature, coal plays a necessary role in people's daily life. Coal is also known as black gold and industrial food. And a large amount of coal is needed for household, electricity generation, building materials, metallurgy, etc.
Recently, the World Heritage Committee has inscribed Ombilin Coal Mine in Sawahlunto, Indonesia on UNESCO's World Heritage List during its 43rd session.
Ombilin Coal Mine as a comprehensive coal mine system can conduct long-hole benching, processing and transportation efficiently. It is seen as the oldest mine in Southeast Asia, the coal storage site of Emmahaven port, and the rail network which combines the mines with coastal areas.
At the same time, Walhi, the local environmental protection organization, has appealed to restrain the coal dust emissions and stop operating the mines that don't meet the environmental requirements.
Coal dust is always produced during the coal crushing process. It is very bad for the workers; lungs and our environment. In 1952, London was hit by the coal dust which caused heavy casualties and there were nearly 4,000 deaths per month.
However, during the crushing process, if choosing the coal crusher with the features of high performance and low dust, dust pollution can be controlled efficiently, while if choosing a coal crusher with bad performance, a large amount of coal dust and coal ash will be generated.
Based on the characteristics of coal, this article will analyze the causes of dust production in the coal crushing process, and analyze how these commonly used coal crusher control dust in the coal crushing process.
How is coal formed and its features
Coal is the solid combustible mineral formed by ancient plants buried in the ground through complex biochemical and physicochemical reactions. According to Ted Pella, one of the most common coal types is anthracite, which has a hardness of about 2.2 when compared to Moh's scale of mineral hardness.
However, since coal doesn't have a completely uniform internal structure, the coal might be harder or softer in different spots.
The reasons for coal dust produced during the crushing process
After the raw coal is transported from belt to coal crusher, the big blocks of coal are crushed while small blocks of coal are screened. All the big coal blocks are crushed to the required size, so their quantity becomes larger, the volume gets smaller and the air contact space increases.
The moisture evaporates faster and faster which reduces the moisture content and results in that a large amount of coal dust separates from the coal.
The external reasons can be divided into three parts: the inductive wind, the bad seal of crusher and the coal accumulation.
- 1The inductive wind which is generated in the crushing process
- During the crushing process, the coal blocks in different shapes and sizes bump each other, producing the inductive wind which will blow dust out of the crusher.
- 2Bad seal of crusher
- Because the inlet of crusher is badly sealed, it makes the coal pipe, crusher inside and the whole feeding channel an opening circulatory system. A large amount of air is brought into the crusher to form inductive wind flow, which is accompanied by dust ejecting from the outlet of the feeding channel.
- 3The accumulation of coal results in massive dust.
- During the crushing process, there may be coal accumulation inside of the crusher because of the performance of crusher or features of coal, which will result in that part of the coal is crushed repeatedly, and the massive dust is produced.
How to control dust during the coal crushing process
In the current market, the most commonly used coal crushers are toothed roller crusher (toothed roller crusher is one of the roll crushers), hammer crusher and jaw crusher, which have advantages in the control of coal dust, and the following will be described in detail.
Toothed roll crusher
- 1Spraying device
- Coal dust is mainly produced in the crushing process. The moisture in the coal is evaporated, making the dust separated from the surface of the coal. Under this condition, the feeding inlet of toothed roll crusher is equipped with spraying devices to control the moisture in the coal and avoid the coal dust pollution from the crusher inside.
- 2Controlling the product size strictly
- Toothed roll crusher adopts fixed center distance to crush the coal forcibly. The structure and size of the toothed roll are designed according to product size which is controlled strictly. The shearing principle is mainly adopted in this crusher.
- The small product can pass through the crusher directly, and only big coal blocks are crushed, which avoids the defect of crushing materials repeatedly and producing more dust.
- 3Advanced load protection device to avoid the accumulation
- The operation of this crusher is easy and convenient, and the rolls are completely symmetrical and can exchange quickly. Toothed roll crusher is equipped with a current overload protection system and the special mechanical protection device, which make the whole machine run reliably. Once the toothed roll crusher is blocked, it will automatically stop and send out an alarm to protect the machine and avoid repeated crushing of dust.
- 1Spraying water to eliminate dust
- During the crushing process, the main parts to produce dust are the feeding opening and discharging opening of jaw crusher. Jaw crusher can crush materials with high moisture, so there can be equipped with two spraying pipes respectively in these parts.
- And the pipes can form a certain angle relative to each other, so as to better control the overall dust concentration and achieve the ideal dust elimination effect.
- 2Deep V-type crushing cavity
- Jaw coal crusher adopts the deep V-type crushing cavity and multiple & small toothed jaws to expand the crushing surface and improve the crushing efficiency. What's more, the deep V-type crushing cavity makes crushing roundly to avoid the accumulation of coal rocks in the cavity, so that to reduce dust production.
- 3Wear-resisting jaw plate
- The jaw plate is made of high manganese steel with toughness. And the tooth in the jaw has a special structure to avoid the sliding of coal, so as to improve the crushing efficiency and reduce the dust.
- 1It can crush high-moisture coal materials
- The hammer of this crusher is wear-resistant and corrosion-resistant, which can crush coal with a moisture content of less than 15%. Therefore, when the coal is fed, it can be humidified to extend the evaporation time of coal moisture in the crushing chamber, and reduce dust production and control dust diffusion.
- 2There is no screen resulting in accumulation
- Hammer crusher has a large crushing ratio and high efficiency. The design of coal hammer crusher has no grate bottom, so there is no problem of material not being discharged in time and repeatedly crushed, so as to reduce the dust production.
- 3The sealing structure restrains dust pollution
- Hammer crusher is shaped like a whistle, and the whole body is sealed perfectly to reduce the leakage of dust. At the same time, the hammer crusher is equipped with an air filter, effectively preventing the dust leakage in the crushing process, to reach the green coal standard.
Different kinds of coal crushers have different characteristics and dust control methods.
In the process of coal crushing, the lower dust rate is, the better working environment will be brought to the workers to prevent them from harm and danger; it can bring investors a greater return because they do not have to install more dust removal equipment and increase the cost; it can also make a contribution to our environment.
These kinds of coal crushing equipment produced by Fote Heavy Machinery (FTM) have been praised by the industry insiders for their high crushing efficiency, low dust emission rate and cheap prices all the time. Therefore, choosing the Fote Heavy Machinery (FTM) will give you a great surprise.
Fote Heavy Machinery (FTM)