Selection of operational parameters for a smart spraying system to control airborne PM10 and PM2.5 dusts in underground coal mines

Abstract

Airborne dust in underground hard coal mines is an ongoing explosion and respiratory health hazard. The latest design solution for controlling dusts, the smart spraying system, is described. From the results of stand tests, the main factors determining the efficiency of the new device are: 1) the integrated real-time acquisition of dust particle size and concentration data, determined using a new optical dust meter; 2) the fractional distribution of water droplets; and 3) the selection of droplet size to capture PM10 and PM2.5. The latter two factors are automatically controlled, based on dust measurements, by varying the pressure of water and compressed air supplied to the sprayer nozzles. The effects of varying these parameters and the results of stand tests are presented. The spraying device was tested for the effectiveness of PM2.5 dust and PM10 dust reduction in underground conditions in the KWK Pniówek mine. The tests were based on the following Polish Standards: PN-91/Z-04030/05 and PN91/Z-04030/06, which define the methodology for measurements of inhalable and respirable dust at workplaces using the filtration-weighing method to determine the concentration of inhalable and respirable dust with the spraying system on and off. The results showed that the assumed objective, i.e. development of a dust control device that would reduce PM2.5 dust (by min. 25 %) and PM10 dust (by min. 20 %) more effectively than the currently used solutions, was achieved in the project. At the same time, the device, due to application of dust sensor, continuously adjusts the parameters of spraying streams to the dust concentration level, optimizing the consumption of water and compressed air. Similar results in reduction of PM10 and PM2.5 dust, with an average effectiveness of over 60 % is the undoubted advantage of the device.