Similarity experiment of dust concentration influencing factors at unloading port in multiple level of high ore pass

To control the dust pollution of unloading port in ore pass caused by the impact air flow,the dust generation mechanism in the process of discharge in high ore-pass was analyzed by means of energy exchange,and the dynamic dust generation process was captured by high-speed camera,the influence mechanism of different influencing factors on the dust concentration in unloading port was analyzed. On the basis of geometric similarity,the number of criteria to be satisfied in similar experiment was derived through dimensional analysis,and a visual similar experiment platform for unloading ore in multiple level of high ore pass was established by using acrylic materials,at the same time,the distri- bution law of dust concentration in the unloading port under different conditions was studied. The results show that the feasibility of similar experiment was verified by comparing with field data. Compared with the dust pollution at the discharge ports of the third and fourth levels,the dust pollution at the discharge ports of the first and second levels is smaller after the discharge of the multiple level of high ore pass,the peak dust concentration at the third and fourth levels can reach 295 mg / m3 and 345 mg / m3 respectively,and with the increase of time,the dust concentration first in- creases to the peak and then stabilizes for a period of time and then decreases. Different influencing factors have great influence on the peak concentration duration of the unloading port in the third and fourth middle levels,except for the discharge flow rate of 1. 2 kg / s,the peak duration of dust concentration increases with the increase of discharge flow rate and discharge height,while the peak duration of dust concentration decreases with the increase of ore particle size and water content. The total dust and respirable dust concentration of unloading port are positively correlated with the height of ore discharge and unloading rate,however,the phenomenon of sudden decrease of dust concentration also oc- curs when the flow rate is too large. The total dust and respirable dust concentration negatively correlated with ore par- ticle size and moisture content,when the moisture content reaches 3. 56% ,the concentration of total dust and respira- ble dust in the unloading port basically tends to be stable and no longer decreases. The respirable dust concentration is about 31. 0% -37. 5% of the total dust concentration under different factors.