The Electromagnet Separates Iron Ore

 

In his study of the Crown Point Iron Industry, Dr. Eugene Barker writes about the separating of iron from ore.

" The ore, after being mined, was drawn to large open kilns, about 300 tons of it being piled upon twenty-five cords of wood. Heat caused the stone to loose its hold from the iron. The ore was then generally put through the water process of separation. It was placed in troughs with grate bottoms, in which it was stumped and screened, the passed through sieves through which water rose from the bottom. The iron being heavier, sank through holes in the bottom of the sieve into a trough, while the pulverized rock was raised and carried off by the current of the water, often together with a considerable amount of the iron in fine particles."

This was a wasteful process and so a separator came to be used in Crown Point. It was a cylinder about 5 feet in length and 2 1/2 feet in diameter studded with magnetized bars on its surface. It revolved in a trough into which ore was shoveled. The iron particles were attracted to the magnetic charge of the bars and came out of the trough on them as the cylinder revolved. Stationary brushes then wiped the bars clean and the iron fell into waiting receptacles. After awhile the magnetic bars would lose strength and need to be re-charged by the electromagnet.

He goes on to say that the electromagnet in use at Crown Point was secured in 1831 from Professor Henry of the Albany Academy at Albany, NY (who later became Director of the Smithsonian Museum). It was worked by a galvanic cell (wet battery) for recharging the bar magnets of the separator and for detecting iron and steel from brass and copper scrap metal.

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