I helped to close it
I was Quality Manager of an Engineering and foundry company. New to the job.
For decades, They'd been importing train loads of hematite Iron ore from Portugal, to use in the heat treatment of the castings.
After increasing complaints from the engineering shops, that the castings were too hard to machine, I sent samples from each rail wagon for analysis. The first couple of trucks were OK, but the ones behind them were of too low a grade.
We changed to a different supplier.
When I visited the Minas, I realised the cruel, evil regime that had made the workers, and their families so badly treated and the disgraceful effects on the neighbourhood.
The museum is worth a visit.