Unraveling dry jigging : insights into pulsation, energy consumption, and stratification dynamics

Abstract

The increasing concerns regarding water usage in mineral processing have led to a growing interest in dry jigging in recent years. However, there is still a need for a more comprehensive examination of the operational aspects of the technique. In this sense, this study focused on three main elements: (a) examining the air pulse pattern during dry jig operation; (b) assessing the evolution of the stratification profile over time using partition analysis; and (c) evaluating the specific energy consumption of batch dry jigging during operation. Also, an innovative operational strategy known as “transient pulsing” was proposed and analyzed, involving varying the intensity and frequency of the air pulse throughout the stratification process. All tests were conducted using density tracers spread across 11 density ranges (0.4–2.4 g/cm3) and a base bed (gravel) to analyze their separation in a batch, pilot-scale dry jig. Pressure drop and active power data were collected to measure the pulse characteristics and energy consumption. The airflow curves, obtained through pressure drop data, indicated that the pulsation process is more unstable as the airflow increases, possibly due to the pressure fluctuations experienced by air during valve closure. For the pulsation conditions used in the tests, the specific energy consumption was 10.66 Wh/kg of jigged material, with most of it related to the blower drive system. Analysis of the stratification evolution over time showed an oscillatory behavior, alternating between states of better (Ep < 0.1) and worse (Ep > 0.1) separation, especially for the near-gravity material (NGM). Results of the transient pulsation tests suggested that progressively increasing the vertical displacement of the bed during stratification resulted in slightly better segregation levels and more stable jigging evolution over time in comparison to stationary pulse conditions.