Dust hazard and protection

Water absorption of dust: the water absorption of dust is determined by the composition, size, charged state, temperature and air pressure of dust. The water absorption increases with the increase of pressure, decreases with the increase of temperature and decreases with the decrease of dust particles. The dust easily wetted by water is called hydrophilic dust, on the contrary, it is called hydrophobic dust. Wet dedusting is not suitable for hydrophobic dust. Some dust absorbs water and forms hard scale insoluble in water, which is called hydraulic dust. Hard scale can cause blockage and failure of the dust removal system.

Personal protection: carry out specific personal protection according to the hazard mode and hazard mode of dust to human body. There are three ways for dust (or poison) to harm human body: one is inhalation, which enters human body through respiratory tract; The other is through sweat glands, sebaceous glands and hair follicles on the surface of the human body; The third is ingestion, which enters the body through the digestive tract. Then, the personal protection countermeasures of injury path: first, cut off the way of dust entering the respiratory system. Different types of dust masks and gas masks shall be selected according to different dust properties (gas masks shall also be worn for some toxic dust); The second is to prevent dust from contacting the skin. Correctly wear work clothes (some need to wear one-piece clothes and hooded work clothes), helmets (people's head is where sweat glands, skin fat and hair follicles are concentrated), glasses, etc.: III. It is forbidden to wait at the operation site of eating, smoking and drinking water.
Dust source treatment and personal protection
The dust control strategy shall be optimized and combined with technical measures such as process, process equipment, materials, operating conditions and methods, occupational health protection facilities and personal protective articles, and comprehensive management shall be adopted.

Eliminate or reduce dust sources: in terms of processes and materials, selecting processes that do not produce dust and selecting harmless or less harmful materials is the fundamental way to eliminate or reduce dust hazards, that is, eliminate the source of dust. Dust removal through process and material selection. For example, resin sand is used instead of casting sand, and wet production process is used instead of dry production process (such as water mill instead of dry mill, hydraulic cleaning, electro-hydraulic cleaning instead of mechanical cleaning, water mist arc welding gouging, etc.)

Limit and restrain dust and dust diffusion: adopt closed pipeline transportation, closed equipment processing, or semi closed, shielding and isolation facilities that do not interfere with operating conditions to prevent dust escape or restrict dust diffusion to local areas and reduce diffusion: reduce blanking and dust; For hydrophilic and weakly viscous materials and dust, measures such as humidification, spraying and steam spraying shall be taken as far as possible to reduce the diffusion of dust during transportation, crushing, screening, mixing and cleaning.
Ventilation and dust removal: ventilation and dust removal can be divided into full mechanical ventilation and local mechanical ventilation according to the workplace and environmental conditions. Ventilation is to continuously deliver clean and fresh air to the workplace, dilute the dust concentration in the air, discharge the polluted air outdoors, and dilute the harmful dust in the workplace to the corresponding maximum allowable concentration. During ventilation and exhaust, airflow containing harmful substances shall not pass through the breathing belt of the operator.
Add dust collection and purification equipment: select appropriate dust collection and purification equipment according to the nature, concentration, distribution and quantity of dust to eliminate and purify dust in the air and prevent secondary dust.