Practical trainings, student assistants and theses

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. Hydrometallurgical extraction and recovery of Cu and precious metals from concentrated fractions (leaching, solvent extraction, supported liquid membrane)
6. Final characterization of recovered fractions (ICP-MS/OES, TGA, XRF, CHNS, SEM)
7. Conclude with optimizing the economical process for individual metal recovery

• Field of study in process, metallurgy or chemical engineering or similar
• Curious, Interest in experiments, planning and execution
• Basic knowledge about the processes mentioned in the topic
• Good written and oral communication skills in English

• Master thesis
• Start date: by mutual arrangement
• Please upload a short letter of motivation, stating the period of time to start the position, CV, and University certificates

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 (Department 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

• Field of study in process, mechanical or chemical engineering or similar
• Curious, Interest in experimental investigation,
• Good written and oral communication skills in English

• Master thesis
• Start date: by mutual arrangement
• Please upload a short letter of motivation, stating the period of time to start the position
• Please upload all supporting documents with your CV, and university certificates

Nowadays, the processing of secondary resources is becoming more and more important as there is a high demand of critical raw materials. Especially batteries have high amounts of the critical metals Lithium, Cobalt, Manganese and Nickel as oxides used for cathode materials, as well as graphite, which is typically used as anode material. After comminution, these valuable minerals enrich in the fine fraction < 1 mm, which is called black mass. Studies have shown that froth flotation is a suitable technique to separate graphite from the cathode active materials.
In the course of the thesis, the separation of the cathode active materials, i.e. nickel-manganese-cobalt oxides, and the anode material graphite by flotation is investigated, with special focus on the influence of ultrasonication. Flotation tests will be carried out in an Outotec GTK lab cell. The flotation cell is modified in a way that ultrasound (by means of ultrasonication) can be applied during flotation. Therefore, a suitable reagent regime and process parameters for the flotation of black mass have to be established, followed by the development of suitable parameters for ultrasound treatment for this novel cell. Additionally, ultrasound will be tested in a pre-processing step before flotation as an alternative to attritioning by means of intensive shearing. Black mass from real spent lithium-ion batteries that was formerly processed via electrohydraulic fragmentation will be used for the tests. Analysis of the flotation products is done using thermogravimetric analysis and elemental analysis.

• Field of study in process, mechanical or chemical engineering or similar
• Interest in experimental investigation
• Good written and oral communication skills in English
• Please upload a short letter of motivation stating the period of time and your current grade overview to the applicant portal

• Student thesis
• Start date: by arrangement
• We offer an innovative multidisciplinary international research environment with relevance to key issues in resource technology