Biotechnological Approach for Recovery of Rare Earth Elements and Precious Metals from E-waste – (BIOREEs)

Project Management:M.Sc. Mehmet Ali Kücüker
M.Sc. Nils Wieczorek
Prof. Dr.-Ing. Kerstin Kuchta
Client / Funding:BMBF
Project Partners:Bogazici University (TR), Suleyman Demirel University (TR), Karadeniz Technical University (TR), Exitcom Recycling GmbH (TR), TCMG GmbH (DE)
Duration:36 Months
Running Time:08/2014 - 09/2017

Waste of electrical and electronic equipments (WEEE) makes up to 5% of the total municipal solid waste generated worldwide, which is nearly the same amount as all plastic packaging. Simultaneously, it has been observed that the WEEE harbours substantially appreciable quantities of base metals, precious metals and rare earth elements (REEs) with potentially high economic values. The tonnage of discarded electronic devices that ends up in the waste stream, collectively called ‘e-waste’ can be used as a secondary resource for the recovery of REEs. Overwhelming demand coupled with limited exports has resulted with a dramatic price rise in the rare earth elements over the past two years. Therefore, attentions have been shifted from mining process towards recycling of secondary resources for the recovery of REEs. The reason for the shifting of REEs recovery from primary resources to secondary resources like e-waste is due to its easy accessibility as well as feasibility together with environmental benefits due to the recycling process.

There are several metallurgical processes for recovery of metals from e-waste such as pyrometallurgical processing, hydrometallurgical and biohydrometallurgical processing. It is believed that Biohydrometallurgy has been one of the most successful and promising technologies with regards to metal recovery from primary metal resources for Copper, Nickel, Gold and Silver in full scale operation today. Bio-/hydrometallurgical processes are considered to be relatively low-cost, environmentally friendly and suitable for both large scale as well as small scale applications. There has been substantial growth in the understanding of the microbial process together with the underlying mechanisms operating during the metal recovery process. However there is still much to understand with regard to the microbial processes involved in both the pretreatment (Biooxidation) of the metal sulphides (FeS2, FeAsS, MoS2 etc.) and metal recovery (Bioleaching) from metal sulphides (Cu2S, CuS, CuFeS2, NiS, PbS etc.). Most of the developments in Biohydrometallurgy starting from lab scale research to full scale operations have been carried out in last 20-25 years.

The research focus on biohydrometallurgy has slightly deviated from the mainstream of complete dependence on primary metal resources (Ores and Concentrates) to secondary metal resources (e-waste, Lithium batteries, spent catalysts, Industrial wastes, Low grade ores etc). The reason for shifting of the focus from primary to secondary resources is due two important reasons. First, due to the depilation of primary resources at an alarming rate leading to closing down of the mining operations due to the fall in the grades of the ores. Secondly, unbelievably huge tonnage of waste materials from several sources such as steel industry, Petroleum industry, paper and pulp Industry, municipality waste incineration and most importantly e-waste. The proposed research work deals with the treatment of WEEE using biohydrometallurgical approach. However, the complete process begins with physical separation (pre-treatment) followed by biohydrometallurgical (bioleaching and biosorption) as well as Hydrometallurgical steps for the recovery of base metals, nanoscale REEs and precious metals from WEEE.

Mechanical treatment for the separation/recovery of valuable metals (Cu, Au, Ag, Pd and REEs), in particular, prior to the extraction processes can be employed to reduce the quantity of material for treatment and hence to improve the process economics. A two-stage process based on bioleaching of base metals followed by leaching of precious metals and REEs will be developed for the biohydrometallurgical treatment of e-waste. However, further research is required to evaluate the deportment of REEs during such a two-stage process or to develop a suitable bio/-leaching process or to refine existing ones for the recovery of REEs in addition to base and precious metals within an innovative, cost effective and environmentally friendly approach. The lab-scale microalgae cultivation plant will be installed in order to produce microalgae for biosorption process at Bogazici University in support by TUHH. The green microalgae Chlorella Vulgaris and the brown microalgae Phaeodactylum Tricornutum will be used as a biosorbent in this study.