The Trout Lake Concentrator - Coleraine, MN

"The mill building is commodious and the machinery 
is conveniently arranged." 

The Trout Lake Concentrator circa 1920

The Trout Lake Concentrator is the first in the series of ghost plants that this blog will cover.  Ghost plants are are those industrial complexes that are visibly absent from the landscape, but whose environmental legacies persist - sometimes in ground water, other times in soils - but remain frequently absent from the contemporary heritage discourse.   A goal of my research is to think about how we, as heritage professionals, can act as necromancers and bring  these Ghost plants, and their environmental legacies, back to life within the contemporary heritage discourse.

The first post in the beneficiation plant series features the Oliver Iron Mining Company's (OIMC) flagship plant, The Trout Lake Concentrator.  Completed in 1909 (construction started in 1907) on the eastern shore of Trout Lake, just south of Coleraine, MN, the Trout Lake Concentrator served as a custom beneficiation plant for the OIMC's low-grade iron ore mines of the Western Mesabi.  These mines were mainly open-pit undertakings, rather than the underground mines that produced much of the high-grade, direct shipping ore of the region.

OIMC's 'pilot' concentrating plant at Coleraine

To profitably function,  beneficiation plants, like the Trout Lake Concentrator, required an ample supply of water - almost as much as they needed iron ore.  The plants used water to wash the ore (remove the gangue) and to flush the waste awayIn the case of the Trout Lake Concentrator, the adjacent Trout Lake provided it with a convenient location to deposit its tailings from the beneficiation plant through a system of launders.  The waste from these plants (and all ore processing plants) are called tailings.  The OIMC and other mining companies sought out property near lakes and ponds when planning to develop ore processing plants, as these water bodies also held value as convenient waste receptacles.  In the case of the Trout Lake Concentrator, the adjacent Trout Lake provided it with a convenient location to deposit its tailings, which were pumped into the lake for nearly three decades.  
 
"They began the Coleraine plant in 1909 and completed the fifth unit in the spring of 1911.  Trout Lake provides it with (1) clear water for the power plant, (2) a place to dispose of tailings, and (3) an abundance of wash water through a forty inch four hundred foot steel intake pipe.  The five units of this one large plant produced more than two and a half million tons of concentrate in 1912." (George H. Primmer, "Future of Lake Superior Iron Ore Supply", in Economic Geography, Vol. 10, No. 04, Oct. 1934: 397)

Trout Lake Concentrator - Circa 1940

"This is the first washing plant to be installed in the Mesabi district, and it marks the beginning of a new era in the mining industry, as ores that were heretofore considered worthless will now be made to yield a fair percentage of profit.”  - (Albert H. Fay, "
Iron Mining at Coleraine, Minnesota”, in The Engineering and Mining Journal, Vol.  88, No. 16, pp. 770

The Trout Lake Concentrator was one of many beneficiation plants that soon dotted the landscape of the Western Mesabi, but unlike most of these other processing plants, the Trout Lake Concentrator operated independent of an individual mine.  Low-grade ore from OIMC's Canisteo, King Group, Morrison and Walker mines traveled by rail from the mine pits to the long trestle leading to the concentrator.
Iron Mining at Coleraine, Minnesota”, in The Engineering and Mining Journal, Vol.  88, No. 16, pp. 770

"In 1910, the mill was operated on two eleven-hour shifts.  In 1911, this was cut down to two ten-hour shifts.  The average capacity is nearly 400 tons of crude ore per hour per unit, the maximum being 900 tons.  The largest tonnage washed in one season of six months was over 4,000,000 tons of crude ore.  The mill can not be operated in freezing weather and its operating season coincides with the ore-shipping season.  Nearly 100 men are employed on the day shift, and 75 to 80 on the night shift." (Handbook of Mining in the Lake Superior Region, 1920: 229-230).

In addition to the concentrating machines and construction materials required for the plant itself, the OIMC needed to develop an extensive industrial infrastructure in order for the Trout Lake Concentrator to function.  The first step - and probably the easiest - involved laying railroad tracks from the nearby northern mines  to the concentrator.   Once at the concentrator, the ore needed to be elevated seven stories to the mouth of the crushing level, where once inside, gravity was employed as the flow of ore worked its way towards the surface.  The gradual ramp that led from the surface of the plant to the seventh story was built with overburden, or organic debris, from OIMC's open-pit Canisteo mine. 

"The American Bridge Company was contracted to erect the structure, and a crew of 125 welders and steel workers was moved to the site.  Eleven thousand cubic yards of cement were poured for the foundation, and then the raising of the huge steel girders began.  Massive construction was necessary since the loaded ore trains would discharge their cargo at the top level of the 124 foot high mill.  The structure measured 225 by 162 feet and required the use of 6,100 tons of steel.  A 650 foot long steel trestle was built to connect the the building with the earthen ramp." - From "The Western Mesabi"

OIMC's  Coleraine concentrator continued to use Trout Lake as a tailings basin until 1940, when OIMC was forced to construct a nearby tailings basin to the east of the concentrator.  By 1955, the Trout Lake Concentrator was still the largest washing plant in Minnesota and had undergone a series of remodelings and repairs, such as the employment of heavy-media concentration in addition to the straight washing of the low-grade ore. 

LIDAR Shows faint signs of the former behemoth.

Although it was once home to the largest iron-ore concentrator in the world, visitors passing through Coleraine today are nary aware of the community's industrial past. The Trout Lake Concentrator was scrapped in the late 1970s, and today Trout Lake is a known as a fertile fishing lake, rather than an industrial resource.  Although the building is gone, its environmental legacy continues to play an active role in Coleraine.     

Why do we forget places like the Trout Lake Concentrator?  and How can we better  interpret the big histories of these ghost plants to the public ?