Virtual Museum of Canada
 
Click to view flowchart of the mill process
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The Mill Process

Ball Mills.
Ball mills.
1936. BCMM# 13484
Prior to the stock market crash in October 1929, the Mill at Britannia produced peak volumes of chalcopyrite (the major ore of copper) and wealth for both the British Columbian and Canadian economies.During this period, the Mill was processing up to 6500 tons (14,000,000 pounds) of rock daily. That’s as much weight as 480 elephants every day!

The main function of the Mill was to separate the waste rock from the minerals (mainly chalcopyrite) that the mining company wanted to sell. All the ore was ground up to the consistency of flour and put through a chemical process known as froth flotation, which causes the valuable minerals to rise to the top and the waste rock to fall to the bottom.

The ore at Britannia Beach was rich in copper. It contained an average of 1.25% copper or 25 pounds of copper for every ton of ore. After the ore went through the Mill, the end product was 26% copper, or 520 pounds per ton. This was very efficient. Britannia’s froth flotation process was so widely used that it became known as the Britannia deep cell method.

The more ore that was processed the more money the mine made. To maximize profits, the methods of separation within the Mill were constantly being updated and improved. Every year the process would change slightly to yield greater amounts of ore. The Britannia Mines Mill earned a reputation as one of the most productive mills in the world.
BCMM 13521. Froth Flotation cells. Date unknown. BCMM 12816. Inside the Mill. Date unknown BCMM 12818. The trestle at the top of the mill. c. 1974 BCMM 13521. Froth Flotation cells. Date unknown. BCMM 12815. Inside the Mill. c. 1974