Dust classification:

1. According to their physical and chemical properties, dust can be divided into inorganic dust (mineral dust, such as coal and asbestos; metal dust, such as iron and zinc; artificial inorganic dust, such as diamond and cement), organic dust (plant dust, such as cotton and linen; animal dust, such as animal hair and feathers; artificial organic dust, such as used as organic dyes), and mixed dust

2. According to the health status of dust, it is divided into total dust and respiratory dust. Total dust: refers to all dust obtained during the dust sampling process, including dust of various particle sizes. Respiratory dust: refers to fine dust particles with a particle size of less than 5 microns. It can enter the alveolar area through the upper respiratory tract, which is the main cause of pneumoconiosis.

3. According to the content of free silica in mineral powder, silica powder refers to dust with a free silica content greater than 10%. It is the main cause of silicosis, and the rock dust in mines is mostly silica dust. Non silica fume: refers to dust with a free silica content of less than 10%, such as coal mine dust, which is generally non silica fume.

4. According to the existence state of mineral dust, floating mineral dust refers to dust suspended in the air, abbreviated as floating dust. Sedimentary mineral dust: refers to the dust that settles from the air, known as falling dust.

5. According to dust particle size: coarse dust particle size greater than 40 microns, equivalent to the minimum particle size for general screening, is prone to settling fine dust in the air: particle size 10-40 microns. Under strong light, visible to the naked eye, it accelerates the settling in still air. Fine dust: particle size 0.25-10 μ m, visible under an optical microscope, continuously settling in still air. Ultra fine dust: particle size less than 0.25 μ m, can only be observed with an electron microscope, and has diffusion motion in the air.

Dust density: including bulk density and true density. Bulk density, also known as apparent density or bulk density, refers to the mass of particles in a unit loose volume of dust. True density refers to the mass of particles per unit volume (excluding particle spacing, volume of open and closed pores). ρb=ρp（1-ε）

Dust dispersion: Dust dispersion refers to the ratio of the mass or quantity of various particle sizes of dust particles in the dust. According to quality, it is called quality dispersion (i.e. the percentage of each particle's mass to the total mass), and according to quality, it is called quantity dispersion (i.e. the percentage of each particle's quantity to the total particle quantity). The majority of small particles are called highly dispersed

Classification of toxic and harmful gases: According to the harm to the human body, toxic and harmful gases are divided into the following five categories: Class 1: Simple suffocating gases that are not toxic themselves, but with increasing concentration, the oxygen content in the air decreases accordingly, causing suffocation, such as carbon dioxide, methane, nitrogen, etc. Chemical asphyxiation gases undergo chemical reactions when inhaled into the human body. The binding ability of red blood cells to oxygen and red blood cells in the blood is greater than that of oxygen and red blood cells, leading to hypoxia in the human body, such as suffocation of gases such as carbon monoxide and hydrogen cyanide, which stimulates the upper respiratory tract. This gas can irritate the nose, throat, etc., causing inflammation, such as ammonia, hydrogen peroxide, sulfur, etc. Four. Gases that stimulate the lungs, such as phosgene and nitrogen dioxide, strongly stimulate the lungs and cause pneumonia and pulmonary edema. 5 of them. Harmful gases to the central nervous system, such as gasoline, can cause paralysis, anesthesia, and damage to the central nervous system when they enter the human body.

Classification of dust removal system:

① Classify according to the scale and configuration characteristics of the dust removal system (on-site dust removal system, decentralized system, and centralized dust removal system)

② Classification by type of dust collector (dry dust removal system, wet dust removal system)

③ Classify according to the paragraph setting of the dust collector (single-stage dust removal system, multi-stage dust removal system)

④ Classify according to the position of the dust collector in the dust removal system (negative pressure dust removal system (dust collector before ventilation fan), positive pressure dust removal system (dust collector after ventilation fan)