Practical trainings, student assistants and theses

Froth flotation is a widely applied physicochemical process for the enrichment of valuable metals in mineral processing. It operates by exploiting both inherent and induced differences in the surface properties of mineral particles. The efficiency of the process relies on the synergistic use of various reagents, including collectors, frothers, and promoters, which collectively modify surface characteristics and enhance selective separation. Particle size distribution is a critical parameter influencing flotation performance, as it governs the selective recovery of valuables from gangue. Therefore, for the true flotation process, a feed size distribution in the range of 20 μm - 150 μm is generally considered optimal. Which makes recovery for finer (< 20 μm) and coarser size range (> 150 μm) poor due to several reasons.
Glass bubbles (GB) are low-density hollow glass spheres which, upon hydrophobization under controlled conditions, act as an ultrafine particle (< 10 μm) collection vesicle enhancing the rate of the recovery process in froth flotation by means of carrier flotation. Recently hydrophobized GB have attracted attention (still only limited studies are available) in flotation due to their low density, structure stability, and tunable surface hydrophobicity, enabling their effective use as carrier particles for improving the particle recovery. This novel concept, carrier flotation exhibits a high potential for application in the flotation of various fine-ultrafine ores.
In this project, at HIF-HZDR (Dept. of mineral processing) we will pursue the following steps:
1.Characterization of hollow glass bubbles (LD, optical microscopy, SEM)
2.Systematic modification (esterification) and surface characterization (Contact angle measurements and FTIR)
3.Study the effect of HGB in froth flotation (magnetite-quartz-apatite flotation system)
4.Quantitative analysis and characterization of recovered fractions (XRF, ICP-MS/OES, TGA)
5.Optimization and development of a flowsheet for improved recovery and grades.
6.Batch flotation and pilot scale testing

• Second year Masters’ student with background of mechanical and process engineering /chemistry/ mineral Processing/ material science
• Basic idea about the importance of the topic and physical processes mentioned in the text
• Sound knowledge about analytical methods mentioned for feed characterization

• Independent and team worker, solution oriented, flexible with work environment

In recycling of end-of-life electronic waste (WEEE), copper is recovered as a major metallic component alongside precious metals such as gold, silver, palladium, and platinum. Although a significant portion of this waste consists organic materials (polymers) and invaluable inorganic fillers, it remains highly valuable due to presence of these precious and base metals making their recovery very important. During PCB manufacturing, processing, or disposal, dust generated also contain these valuable metals. Such fine dust (20 μm – 315 μm) makes recovery of precious metals challenging. Systematic separation and analysis of these precious metals from PCB dust can offer both economic benefits and reduction in environmental impact. The present thesis focuses on detailed feed characterization of the fine PCB waste fractions. Physicochemical and particle-based methods for metal identification, extraction, and refining will be designed and developed. This approach aims to valorize fine dust classified as hazardous waste through strategies aligned with the principles of the circular economy approach.
In this thesis project, at HIF, HZDR (Department of mineral processing and process metallurgy) we will pursue the innovation along following steps:
1.Pre-processing of PCB dust (comminution, dry/wet sieving and splitting)
2.Pre-characterization in order to know about the size distribution, elemental assay, present phases using (LD, ICP-OES/MS, XRF, SEM)
3.Liquid-liquid particle separation- optimization of the developed process
4.Froth flotation- optimization of the developed process
5.Extraction and recovery of Cu and precious metals from concentrated fractions
6.Final characterization of recovered fractions (ICP-MS/OES, TGA, XRF, CHNS, SEM)
7.Conclude with optimizing the economical process for individual metal recovery

• Masters’ student with background of chemistry/ mineral Processing/process metallurgy
• Basic idea about the importance of the topic and physical processes mentioned in the text
• Sound knowledge about analytical methods mentioned for feed characterization
• Independent and/ team worker, solution oriented, flexible to different work environment

Master thesis work