Ann: Cape Lambert Finalises the Joint Venture Agreement, page-58

The mines where kids & usually their family work are smaller artisan mines and they happen to be able to enter their product into the supply chain. Small mines are littered all over the DRC with towns around them like gold rush days in a developing country.

The larger multinationals that mine on a larger scale to best practice and run professional businesses may at least be able to guarantee product to be free of child labour. It is up to the manufacturers where they purchase their raw materials from and whether to purchase it from reputable larger organisations or from unknown sources possibly using child labour.

Take a look at the below pic, I'm sure kids wouldn't be working there. The workers accommodation is visible at the top right of the photo.