With the repeal of the travel restrictions in September 2021 the ReWoRK-team immediately began planning the resumption of their field work with the Brazilian partners. It was crucial to the team to achieve the needed progress as fast as possible before any travel restrictions could be implemented again. Still pending was the detailed exploration of the residual materials on the grounds of the project partner Mineração Tomaz Salustino SA in Currais Novos/RN, Brasil. Although there had been superficial probing’s in the last stays, the information about the composition of the residual materials in greater depth had still been missing at that time.With the repeal of the travel restrictions in September 2021 the ReWoRK-team immediately began planning the resumption of their field work with the Brazilian partners. It was crucial to the team to achieve the needed progress as fast as possible before any travel restrictions could be implemented again. Still pending was the detailed exploration of the residual materials on the grounds of the project partner Mineração Tomaz Salustino SA in Currais Novos/RN, Brasil. Although there had been superficial probing’s in the last stays, the information about the composition of the residual materials in greater depth had still been missing at that time.

Due to the applied process, two different types of tailings are produced on the grounds: the coarser-grained residues that remain after scheelite-extraction using wet separation tables, and the finer tailings which sediment in the course of the process water treatment and are deposited elsewhere as sludge. In two different exploration campaigns the residual materials are supposed to be split from another, sampled and analysed specifically.

At first the coarser-grained tailings were sampled by means of percussion core probing and subsequently analysed in Germany by the partner BGR. This was done in close cooperation with employees of the partner MTS and students of the UFRN and the used probes were preferred to originate from older residues. Estimated were tungsten contents in the range of 0.1 to 0.15%. While the older tailings had partly significantly higher concentrations, the contents of the newer residuals were considerably smaller. However, the concentrations alone are not the only important attribute, other factors like degree of adhesion or particle size distribution are also of considerable importance.

In January the exploration of the finer tailings followed. This time additionally and voluntarily supported by employees of the Geoparque Seridó (the Geoparque has been was raised to an UNESCO-geopark just recently, congratulations once again! Check: https://geoparqueserido.com.br/). The probes from this campaign were analysed in the following by the partner BGR as well. On the basis of the received results, spots for a representative removal of material on a tonne scale, as required for the trials, could be identified.

After Easter the extensive sampling for the processing experiments took place. Both the coarser-grained as well as the finer-grained tailings were probed in a multi-day campaign on a tonne scale and placed in bigbags. As a safety-measure additional cores were taken from the sampling points for later analysis. A small speciality was the accompaniment of students from the local mining-school as part of an internship.

Particularly demanding was the transport of the material from Brazil to Germany. Because of the still disrupted logistic chains and the lack of containers the offers of German shipping companies for the transport were higher than the calculated and estimated costs. At this point the Brazilian partners jumped in, first and foremost our partner Equilibrium Engenharia e Meio Ambiente from Porti Alegre, and organised the transport for us to the port of Hamburg. This lowered the costs for at least a part of the transport. A couple of days ago the bigbags finally arrived in the CUTEC research centre where the processing tests can now begin.