Which Factor Explains Why Coal Dust Is Explosive

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Which Factor Explains Why Coal Dust Is Explosive?

Coal dust suspended in air is explosive—coal dust has far more surface area per unit weight than lumps of coal and is more susceptible to spontaneous combustion. As a result a nearly empty coal store is a greater explosion risk than a full one.

How are dust explosions caused?

There are five necessary conditions for a dust explosion:

A combustible dust.
The dust is dispersed in the air at a sufficiently high concentration.
There is an oxidant (typically atmospheric oxygen)
There is an ignition source.
The area is confined—a building can be an enclosure.

What are the five factors needed to cause a dust explosion?

If the event is confined by an enclosure such as a building room vessel or process equipment the resulting pressure rise may cause an explosion. These five factors (oxygen heat fuel dispersion and confinement) are known as the Dust Explosion Pentagon.

What type of hazard is coal dust?

Exposure to coal dust can cause a person to develop coal worker’s pneumoconiosis also known as black lung disease. High exposure to respirable crystalline silica dust causes silicosis a lung disease that can lead to serious breathing difficulties lung cancer and loss of life.

Is coal dust a combustible dust?

Examples of combustible dust:

Metal Dust – Such as Aluminum and Magnesium. Wood Dust. Coal and Other Carbon Dusts. Plastic Dust and Additives.

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Why is grain dust explosive?

Grain produces dust when it moves. This dust is suspended in the air inside the elevator creating a combustible mixture that is highly flammable. All it takes is one spark and the whole elevator can explode. Static electricity a light switch or friction can create a spark that can lead to an explosion.

What is flammable dust?

Essentially a combustible dust is any fine material that has the ability to catch fire and explode when mixed with air. Combustible dusts can be from: most solid organic materials (such as sugar flour grain wood etc. ) many metals and. some nonmetallic inorganic materials.

What is dust explosion class?

Ashok: Combustible dusts are ranked into one of four classes ST0 ST1 ST2 ST3. The level of explosion violence increases with the class number. The only dust that has zero risk of explosion is an ST0 dust. All other dusts have an explosion hazard.

Why is there a danger of explosions in coal mines?

The danger of a violent explosion is enhanced by dust is not sufficiently inerted by rock dust. In most coal mines the methane flammable limit and render the s processes within the coal itself may reduce the atmospheric oxygen thereby further reducing the flammability in the sealed atmosphere.

What can cause an explosion?

Many explosions occur when gases are exposed to a source of heat– such as fire sparks even static elec- tricity-or an increase in pressure. Explosions can also be caused by chemical reactions. For instance when two or more incompatible substances are combined they may explode.

What does coal dust cause?

Exposure to coal mine dust causes various pulmonary diseases including coal workers’ pneumoconiosis (CWP) and chronic obstructive pulmonary disease (COPD). 2. Coal miners are also exposed to crystalline silica dust which causes silicosis COPD and other diseases.

Why is dust a hazard?

Exposure to dust can cause irritation to the eyes skin and respiratory tract and prolonged exposure can lead to a range of serious lung diseases including silicosis coal workers’ pneumoconiosis (CWP) chronic obstructive pulmonary disease (COPD) and lung cancer.

How do coal mine explosions happen?

Coal mine explosions are generally caused by either methane or coal dust. … Explosions happen when the methane comes in contact with a heat source. The combustion process causes air inside the mine to expand which can create a shock wave. The most common method to control methane levels in coal mines is ventilation.

Is dust flammable or combustible?

Any combustible material can burn rapidly when in a finely divided form. If such a dust is suspended in air in the right concentration under certain conditions it can become explosible.

Why is iron dust combustible?

When they come in contact with a heat source the small shavings of metal dust are able to easily become hot enough to ignite since the heat does not have anywhere to dissipate. This heat causes the high surface area of the metal to rapidly oxidize by burning which consumes the oxygen that is present.

Why Is weather a factor in combustible dust explosions?

When the air is cold and dry in the winter dust contains less moisture. This means it can become airborne more easily. Clouds of dry airborne dust can ignite quickly. … A combustible dust explosion is more likely to occur any time that the air is dry.

Why is grain so flammable?

Because grain dust particles are extremely small there doesn’t have to be a lot of it for an explosion to happen. of surface area and that surface area being exposed to oxygen makes it extremely flammable.”

Can dust particles explode?

Dust explosions are the result of high concentrations of combustible dust particles rapidly combusting inside an enclosed space. … This will mix the dust with the oxygen in the air which will make the explosion bigger and potentially fuel a second dust explosion – or even several.

How flammable is grain dust?

Grain dust is highly combustible so a fire or an explosion can happen at a large grain-handling facility or in a grain-storage area on a local farm or ranch. Four basic elements must be present for a grain dust explosion to occur: fuel oxygen confinement and an ignition source.

What is a Class 4 explosive?

Class 4 dangerous goods include flammable solids substances liable to spontaneous combustion and substances which in contact with water emit flammable gases. … Division 4.2: Substances liable to spontaneous combustion. Division 4.3: Substances which in contact with water emit flammable gases.

What is a secondary dust explosion?

Secondary explosions occur when there is a rapid combustion of fine combustible dust particles suspended in the air. Secondary dust explosions can occur where any combustible material in dust form is suspended in the atmosphere in a high enough concentration that allows combustion with a source of ignition.

How can dust explosion be prevented?

Help Prevent Dust Explosions

KNOW THAT MOST DUSTS ARE COMBUSTIBLE. …
PROVIDE ACCESS TO ALL HIDDEN AREAS OF YOUR PLANT. …
REGULARLY INSPECT FOR DUST BUILDUP. …
CLEAN AT REGULAR INTERVALS. …
MOVE DUST COLLECTORS OUTSIDE. …
ENSURE ELECTRICAL WIRING AND EQUIPMENT IS APPROVED FOR USE IN YOUR DUST HAZARD CONDITIONS.

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Is my dust explosive?

A value over 0 and below 200 could result in a “weak explosion.” A value between 200 and 300 could result in a “strong explosion.” These substances might include cellulose or wood flour. A value over 300 could see a “very strong explosion.” These materials might include aluminum or magnesium dust.

What is KST and Pmax?

Kst value and Pmax are explosive properties measured in the laboratory to quantify the severity of a dust explosion. … A weighed quantity of combustible dust is placed into the dust container. The main explosion chamber is then evacuated to 0.4 bar absolute.

What is KST test?

KST the deflagration index of a dust is a generalized number used to estimate the anticipated behavior of dust deflagration or explosion. It indicates a dust’s approximate explosive power compared to other dusts.

Are coal mines explosive?

There are two main types of coalmine explosions: methane and coal dust. … Likewise fine particles of coal dust in the right concentration that contact a source of heat can also be explosive. Hybrid explosions consisting of a combination of methane and coal dust can also occur.

What factor affects the rate of chemical reaction in a coal dust explosion happen in mines?

The factors that affect reaction rates are: surface area of a solid reactant. concentration or pressure of a reactant. temperature.

Which is mainly responsible for explosion in coal mines?

Since the inception of underground coal mining the release of methane from coal beds (“coal gas”) has been a hazard to mining safety. When methane combines with air it forms a combustible mixture which has been the cause of countless mine explosions.

Which gas causes explosion in coal mines?

Methane explosions

Methane explosions occur when methane gas from mining is built up and cannot escape because of high pressure. Coal dust is also highly inflammable in nature and causes explosions.

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What is explosion give example?

countable noun. An explosion is a sudden violent burst of energy for example one caused by a bomb. A second explosion came minutes later and we were enveloped in a dust cloud. Three people have been killed in a bomb explosion in northwest Spain. Synonyms: blast crack burst bang More Synonyms of explosion.

What causes an explosion during a fire?

Explosions: Explosions can be the result of combustion chemical reaction or mechanical failure. For combustion or fire-related explosions ARCCA engineers and fire investigators investigate the explosion much like a fire (i.e. explosion cause and explosion origin) using many of the same methodologies.

What is pneumoconiosis caused by?

The pneumoconioses are a group of interstitial lung diseases caused by the inhalation of certain dusts and the lung tissue’s reaction to the dust. The principal cause of the pneumoconioses is work-place exposure environmental exposures have rarely given rise to these diseases.

Is coal dust a targeted or systemic toxicant?

Coal dust is an established toxicant.

Is coal dust a chemical or physical toxicant?

Physical toxicants are substances that due to their physical nature interfere with biological processes. Examples include coal dust asbestos fibres or finely divided silicon dioxide all of which can ultimately be fatal if inhaled.