Evaluation of the dustiness of fugitive dust sources using gravitational drop tests

Abstract

Handling of dry granular materials in quarries and mining processes are an important source of atmospheric dust characterized as fugitive sources. Fugitive dust sources may affect the health of operators in the facility or the inhabitants of nearby communities. During handling, the air-particle interaction eases the suspension of large amounts of dust. Some of the dust particles settle near the source while others are carried away by the air. The settled dust may be re-suspended into the air by windblown mechanisms or by traffic activity, increasing the impact on the surroundings. For middle and small-sized quarries in developing countries the direct field measurement of the environmental impact of fugitive sources is not affordable. This work proposes the utilization of a gravitational dustiness test to mimic fugitive dust sources that take place during handling of particulate materials and to evaluate the dustiness of the source. Two different gravitational dustiness tests devices were built and used to evaluate the dustiness of a granular material handling. The tests are simple, require low investment and can be used to study the influence of variables and remedy actions. The utilization of the tests allowed to estimate the amount of dust generated and to know the particle size distribution of the emitted dust. In addition, the tests allowed the exploration of the influence of the relative humidity and temperature of the surrounding air on the dust emission. Results suggest that dust emission is affected by the properties of the surrounding air due to the dependence of adhesion and inter-particle forces on the air humidity and temperature.