Separation of Particles Based Upon Adhesive Forces with Controlled Relative Air Humidity

Author: Bernardo Moreno Baqueiro Sansao, Materials Engineering and Science Graduate Program

Mentor: Dr. Jon Kellar, Department of Materials and Metallurgical Engineering

Mentor: Dr. William Cross, Department of Materials and Metallurgical Engineering

Mentor: Dr. Albert Romkes, Department of Mechanical Engineering

The mineral industry uses tremendous amounts of water every year in the processing of ores. Sustainable practices associated with the processing of ores is of critical importance. This investigation evaluates the separation process based upon adhesive forces under controlled relative air humidity (RH). Glass spheres were chosen to represent silicate minerals, the most abundant type of minerals found in mineral deposits. Glass disks were used as substrate and beads were plasma cleaned and surface treated with trichloro(octadecyl)silane (TCOD). A horizontal impact test was used to determine the adhesion force between glass spheres and glass disk substrate. It was observed that RH contributes to the adhesive forces to hold particles on the substrate. Impact tests performed under a range of RH showed that separation of plasma cleaned and TCOD treated particles can be achieved in 80% of the tests at humidity levels between 45% and 55%. The recovery of plasma cleaned particles was five times greater than TCOD treated particles at humidity levels between 50% and 55%. Tests with naturally hydrophilic (quartz, microcline) and naturally hydrophobic minerals (molybdenite) were also performed.