Automated contact time apparatus and measurement procedure for bubble-particle interaction analysis

Abstract

The novel Automated Contact Time Apparatus (ACTA) presented in this paper serves as a diagnostic tool that allows the detection of changes in bubble-particle attachment probability and therefore floatability caused by alterations in the chemical environment and particle properties. The apparatus consists of six identical capillaries where bubbles with defined size are produced simultaneously in a measurement chamber. The bubbles at the needle tips are placed in contact with the submerged particle bed for specific time periods, controlled with the help of automatic actuators. The advantage of the instrument is that hundreds of bubbleparticle contacts can be measured automatically within a short time period. Microscopy pictures of each measured bubble are taken while recording the movement of the bubble before, during and after contact with the solid particles. The recorded pictures can be used to determine the actual bubble size and its corresponding deviation, and to detect the attachment of particles. The attached particles are collected in a detachable chamber for subsequent characterization. Furthermore, the device is portable and can be taken to the mineral processing plants for quick evaluation of particle-bubble attachment efficiency with particles and process water sampled directly from real processes.

Towards a quantitative analysis of the wettability of microparticles using an automated contact timer apparatus

“…For the determination of tatt, the ACTA was used. The design and operation of ACTA has been detailed in a previous publication (Aspiala et al 2018) and is represented schematically in Figure 1. Briefly, the ACTA is a programmable induction timer apparatus built in-house, capable of producing hundreds of particle-bubble attachment events in relatively short periods of time.…”

“…Recently, our research group developed an automated contact timer apparatus (ACTA) that permits the analysis of hundreds of bubble-particle contact events in a short period of time (Aspiala et al 2018).…”

A Study on the Electric Surface Potential and Hydrophobicity of Quartz Particles in the Presence of Hexyl Amine Cellulose Nanocrystals and Their Correlation to Flotation

“…In a review published by Verrelli and Albijanic (2015), the strengths and weaknesses of several methods to measure the induction time were summarized. To overcome the current limitations of the previously available experimental methods, a novel automated contact timer apparatus (ACTA) was engineered by our research group (Aspiala et al, 2018). This apparatus offers various technical advantages, such as a controlled preparation of a particle bed, the ability of setting and recording contact times, approach and receding speeds, and the measurement of hundreds of individual attachment events in a few hours.…”

The Influence of Specific Ions and Oxyhydroxo Species in Plant Water on the Bubble–Particle Attachment of Pyrrhotite

“…It is important to mention that another mechanism, which could be important to consider, is related to the effects of inorganic electrolytes on bubble coalescence, affecting the bubble size, which would in turn affect the bubble surface area on which bubble–particle contact occurs. A study by Lessard and Zieminski showed that multivalent cations and anions have a greater ability to inhibit bubble coalescence, while Craig reported that solutions containing single salts of NaNO 3 and Ca­(NO 3 ) 2 inhibited bubble coalescence; this, in turn, resulted in small bubble diameters. It is also well known that high concentrations of electrolytes, as with frothers, have bubble-size-reducing ability. , Although in this study, the total ionic strength was maintained constant at 0.1205 M for all salt solutions, the NaNO 3 solution exhibited a higher molarity of 0.1205 M compared to Ca­(NO 3 ) 2 and CaSO 4 , which exhibited molarities of 0.0402 and 0.0301 M, respectively.…”