ZHANG Ling¹, DONG Fa-qin², HE Xiao-chun²

(1. School of Chemical Engineering, Xuzhou College of Industrial Technology, Xuzhou 221000, China;
2. School of Environmental Resource and Engineering, Southwest University of Science and Technology, Mianyang 621002, China)

Abstract: This article describes the characteristics of natural, artificial and industrial dusts, such as mineral phases, their chemical components, morphological observations and size. Quartz and calcite are the main phases in natural and industrial dusts with high SiO₂ and CaO and low K₂O and Na₂O in chemical composition. Natural dusts consist mainly of irregular shapes particulates, with some aggregated particles made of smaller dusts on the surface of larger dust particles. Industrial dusts are more sphericular, while artificial dusts are columnar and fibrous. The particles mainly range 0.3 to 5 μm in size, with over 99% smaller than 5 μm. Under the condition of a simulated human body temperature (37 ℃), the dissolution and electrochemical behaviour of dust in aqueous glutamic acid were being investigated for 32 hours. Changes of the pH values and conductivity for all types of dust were similar, increasing slowly in the first 8 hours, then the pH values increased rapidly. The total amount of dissolved K, Ca, Na and Mg ions were in the range of 35.4 to 429 mg/L – particularly Ca, which has a maximum range of 20 to 334 mg/L. The total amount of dissolved Fe, Zn, Mn, Pb and Ba ions were in the range of 0.18 to 5.59 mg/L, while Al and Si were within 3.0 to 21.7 mg/L range. Each element dissolved relatively rapidly in the first 16 hours. The order of relative solubility of the various types of dust examined with glutamic acid is: wollastonite>serpentine> sepiolite; cement plant industrial dust>natural dust>power plant industrial dust. Wollastonite dust and power plant industrial dust have the highest solubility (with high content of CaO) and display poorer corrosion-resistance and lower bio- resistance. Sepiolite and cement plant industrial dust have the lowest degree of solubility (with high contents of SiO₂) and display higher corrosion- resistance and stronger bio- resistance.