Arthur Fahrenwald made significant contributions to the beneficiation of ores during his ten years with the U.S. Bureau of Mines and thirty-plus years with the University of Idaho. As an outstanding educator, he sent well-trained metallurgical engineers to the mining industry.​

He designed the Fahrenwald Hydraulic Classifier in 1920 and the Fahrenwald Sub-A-Flotation Machine (1923). These machines, incorporating his designs, dominated ore-dressing for decades. By the mid-1950s, Denver Equipment Company had sold over 35,000 units of their Sub-A machine to 4,800 plants worldwide. Flotation machines incorporating Fahrenwald’s concepts are still being manufactured.​

Born in Yankton County, South Dakota, of immigrant parents from Norway, he attended the South Dakota School of Mines, receiving a B.S. degree in Metallurgical Engineering in 1916. From 1915 to 1917, he taught at the New Mexico School of Mines. In 1919, he joined the U.S. Bureau of Mines Field Station at the University of Idaho, where he was appointed to the faculty in 1929 and was Dean of the School of Mines and Director of the Idaho Bureau of Mines and Geology from 1934 to 1954, retiring in 1960. He was awarded 17 patents related to crushing, grinding and flotation.​

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