Complex sentence: It operated many coal mines until the last one shut down in 1934, as well as the St. Louis brick company, which burnt down in the 1930s, then right after being rebuilt, it burnt down again and never rebuilt after that.
Split into simpler sentences: It operated many coal mines until the last one shut down in 1934. Another industry was the St. Louis brick company, which burnt down in the 1930s; then, right after being rebuilt, it burnt down again and was never rebuilt after that.