Funding for this research was provided by:
Eti Mine (2014-2017)
Received: 15 November 2018
Accepted: 10 January 2019
First Online: 18 January 2019
Compliance with ethical standards
: The project was funded by Eti Mine. Eti Mine had no influence on the conduct of the study and has not influenced the results and interpretation. Thus, the authors declare no conflict of interest.