Smelting the Ore - Anaconda, MT - Montana Historical Markers on Waymarking.com

View waymark gallery

Smelting the Ore - Anaconda, MT

in Montana Historical Markers

Posted by:  T0SHEA

12T E 350804 N 5109543

Anaconda Stack State Park is on the far eastern edge of the city of Anaconda, an extension of Fourth Street East.

This park was constructed in 2000, predominantly by Anaconda Job Corps students and staff. It is as much a memorial park as anything, with many, many memorial pavers and plaques, primarily in memory of past employees of the Anaconda Copper Company, builder of the smelter where the smokestack still stands.

There are several plaques in the park which elucidate upon the history of the smelter and the smokestack as well as the NRHP plaque, outlining the smokestack's place on the National Register of Historic Places.

This plaque outlines the actual operation of the smelter, or how a smelter operated a century ago. Smelting processes are today much cleaner, eliminating the huge amounts of water, air and ground pollution created back then. Pollution from the Anaconda smelters created the largest Superfund site in the US and cost several hundred million dollars to clean up.

Extracting pure copper from the ores mined in Butte was a complex process. First, the useless waste rock was separated from the valuable ore, and the high-grade material was separated from the low-grade material. Next, the lower-grade ore was concentrated by crushing and mechanically separating the heavier metal particles from the lighter waste rock. Copper concentrates were "roasted" in furnaces to remove part of the sulphur. Roasted concentrates were then smelted in a blast or reverberatory furnace to further remove impurities. This process formed molten copper matte and slag, a waste material made up of iron oxide and silica (sand). Slag was poured off and run through water to cool and granulate it. Molten matte was smelted in converter furnaces to create crude "blister" copper and more slag. At this point slag itself contained copper and was recycled rather than discarded. Blister copper was further refined in the casting furnaces, cast into anodes, and shipped to Great Falls, where the remaining impurities, metals such as gold and silver, were removed. These valuable by-products were collected and marketed. The massive black hill near the entrance to Anaconda, directly east of this site, is a slag pile.

During the copper smelting process, the stack acted as a chimney to carry off the smoke and gases produced as by-products. Exhaust from the individual roasting, smelting and refining furnaces traveled first through a series of dust chambers and flues and then up and out through the stack. Research and development conducted at the smelter resulted in more efficient methods at each stage of the copper smelting process. The Washoe Smelter contributed to the growth of Montana's copper industry and ensured the name "Anaconda" was recognized as a world leader in metallurgy.
From the Plaque