Complex sentence: After feasibility studies for an open pit operation by a consortium of companies led by the Broken Hill Proprietary Company Limited, mining started in 1984 and the first copper processing facilities were commissioned in 1987.
Split into simpler sentences: After feasibility studies for an open-pit operation, by a consortium of companies led by the Broken Hill Proprietary Company Limited, mining started in 1984. The first copper processing facilities were commissioned in 1987.