Desenvolvimento de um túnel para secagem e emissão de minério em condições ambientais controladas

Abstract

A dust emission is present in the various stages of the mineral industry, from extraction in mines to ship loading in ports. Transport in train wagons, storage in stockpiles and handling are three major sources of particulate emissions into the atmosphere. Suspended dust does not only affect the local environment, as the wind transports the particulates and brings disturbances to urban centers close to railway networks and ports. Larger particles are deposited on surfaces, outperforming visual surfaces, and smaller, unresearched particles with a size between 10 and 2.5μm are easily inhaled and lodge in lung tissue, potentially causing irritation or necrosis. Dust emission is enhanced by local atmospheric conditions, which cause the evaporation of surface moisture from the wet ore, breaking the liquid bridges that keep the particles linked together. Aiming at studying the dynamics of drying ore, a drying tunnel was designed and built, comprising a wind tunnel, cooling, heating and humidification equipment that are interconnected by a supervision and control system. The use of the bench for drying studies using sinter feed is known to be satisfactory, as the temperature remained stabilized at the setpoint during the drying time, reflecting the good calibration of the temperature PID controller. Moisture and ore mass were automatically measured using a scale and a capacitive moisture sensor positioned in the test section of the bench. The constant rate and descending rate drying curves only in the lightest weather conditions. The biggest limitations and variations were observed only in the period with decreasing drying rate, showing the influence of environmental conditions on the drying dynamics. Therefore, this work leaves as a contribution the preparation tunnel for future research and an experimental database for the calibration of numerical models and models of mathematical models for prediction prediction.