In some cases, it is often difficult to distinguish the boundaries of aerosols of tiny solid particles such as dust, smoke, fly ash, black smoke, etc. According to the habits of our country, the solid particle aerosols formed in metallurgical processes and chemical processes are generally called soot; Fly ash and black smoke produced during fuel combustion are also referred to as soot when they are not distinguished. In other cases, as well as when referring to aerosols with small solid particles, they are commonly referred to as dust. From the perspective of air pollution control, according to the ** and physical properties of aerosols, they can be divided into the following types.
1) Dust generally refers to the microparticles suspended in a gaseous medium.
Small solid particles that settle under gravity but remain suspended for a period of time (or even quite a long time). It is usually formed by mechanical processes such as crushing, grinding, grading, and conveying solid substances, or natural processes such as weathering of soils and rocks. The shape of the particles tends to be irregular. The size of the particles generally ranges from about 1 200 m. There are many types of air pollutants belonging to the dust category, such as clay dust, quartz dust, coal dust, cement dust, various metal dusts, etc.
2) Fume generally refers to the aerosol of solid particles formed by metallurgical processes. It is produced by the condensation of gaseous substances formed by the volatilization of molten substances, and is always accompanied by chemical reactions such as oxidation reactions in the formation process. The size of the smoke particles is very small, generally 001 1 m or so. The production of smoke is relatively common, such as lead oxide smoke and zinc oxide smoke produced in the process of non-ferrous metal smelting, and calcium oxide smoke in nuclear fuel reprocessing plants.
3) Fly ash generally refers to the dispersed and finely dispersed ash discharged with the flue gas produced by fuel combustion.
4) Smoke generally refers to visible aerosols produced by fuel combustion.
5) Fog is a general term for droplet suspension in a gas. In meteorology, it refers to a suspended body of small water droplets with a visibility of less than 1 km. In engineering, fog generally refers to the suspension of small liquid particles, which may be formed due to the condensation of liquid vapor, the atomization of liquid and chemical reactions, such as water mist, acid mist, etc. In China's "Ambient Air Quality Standard" (GB3095-2012), dust particles are also divided into total suspended particles (particles that can be suspended in the air with an aerodynamic equivalent diameter of 100 m), inhalable particles (particles that can be suspended in the air and have an aerodynamic equivalent diameter of 10 m) and fine particulate matter ( fineparticles, can be suspended in the air, aerodynamic equivalent diameter 25 m of particulate matter).