Complex sentence: The first sulphide pulp mill in the Dominion of Canada was constructed along the East River in 1885; however, it was closed in 1891 due to high sulphide importing prices.
Split into simpler sentences: The first sulphide pulp mill in the Dominion of Canada was constructed along the East River in 1885. However, it was closed in 1891, due to high sulphide importing prices.