Complex sentence: At its early days the Aluminium Reduction Plant employed some 700 people but, although producing some of the highest grade aluminium, its small size in comparison to modern smelters (US), led to its closure in 2000.
Split into simpler sentences: At its early days the Aluminium Reduction Plant employed some 700 people. Although producing some of the highest grade aluminium, its small size in comparison to modern smelters (US) led to its closure in 2000.