Ira Boyd Humphreys (“I.B.” was preferred), the mechanical genius of the famed Humphreys family, was the sole inventor of the Humphreys Spiral Concentrator. Its economical concentration permitted the utilization of low-grade ores previously regarded as having no value.
I.B. observed that gold and black sands collected on the inside of curves in rivers. If this concentration of heavy minerals could be drawn off, he reasoned, one would have a simple and efficient, large-scale prospector’s pan.
Working in his garage in Denver, in 1941 he used old rubber tires, and later sheet lead beaten into shape, to fashion a trough through which water flowed in a circle. The heavy minerals were drawn off at ports on the inside of the channel; the light minerals flowed to the outside.
The first spirals, made of iron, proved successful in a 1943 chromite beach sand operation in Oregon. In 1944, the Humphreys Gold Corporation (later renamed Humphreys Mining Company) installed 192 spirals near Jacksonville, Florida. The operation mined ancient beach sands and produced ilmenite and rutile-sources of titanium.
The success of I.B. and his brother, A.E. Humphreys, Jr., in the venture caught the attention of E.I. du Pont de Nemours and Company. The brothers managed operations for du Pont in Florida and Georgia, in which batteries of more than 1,400 spirals were used.
The 1960s was the peak decade for the spiral concentrator. About two-thirds of all applications were for the iron ore industry. Several large engineering and construction companies designed and built spiral plants, under agreement with Humphreys, to process iron ore in Canada, West Africa, and the United States. Spirals also proved effective in the efficient treatment of anthracite, barite, copper, gold, lead, manganese, mica, phosphate rock, tin, and tungsten.
I.B. Humphreys had little formal engineering education; he developed his mechanical talents in solving technical problems of the family’s numerous enterprises. For his simple invention, he was given the Robert H. Richards Award by the AIME in 1964 for his contribution to the advancement of the minerals industry.
