砕石プラントにおける粉じんの実態
1972 年 88 巻 1007 号 p. 23-28
詳細
1972 年 88 巻 1007 号 p. 23-28
This paper gives the results of dust survey taken place in 79 rock crushing plants in Tokai District. The airborne dust concentrations were surveyed with a high volume air sampler, the size distribution of airborne dust were calculated with an optical microscope attached a Patterson-Cawood graticule and the free silica contents of dust were analysed by the modified phosphoric acid method. The main results of the survey are as follows:-
1. On the airborne dust concentration......Among various equipments, the third or more higher order crushing unit produces the highest concentration. The dust concentration in the leeward from the origin decreases in accordance with the following formula,
C=C0e-0.072T/0.01369x2+0.314x+1
where, C=airborne dust concentration at distance x m and time T sec C0=airborne dust concentration at the origin
2. On the size distribution of dust particles.........The mode of size distribution of deposit dust differs according to the kind of equipments. On the contrary the airborne dust from every kind of equipment has the nearly same size distribution. The average respirable dust concentration below 5 micron surveyed near the origin is about 2.5% in weight.
3. On the free silica content.........The maximum content is 76.22%(silicated sandstone) and the minimum 0.22%(peridotite). Most parts of sample contain between 30-50% free silica.
