Mineral flotation and patentable utility

摘要

Mineral flotation is a commonly used method to separate a mineral from a gangue material and produce a mineral concentrate. The mineral feed to a flotation device is ground quite finely, and is usually treated with flotation reagents, which improve the mineral separation process. In 1925, this method of mineral flotation with reagent assistance was in its infancy and Mineral Separation North America Corporation was issued Canadian Patent CA 247,576 (the '576 patent) entitled "Froth Flotation Concentration of Ores." Mineral Separation subsequently licenced their patent to many of the biggest mining companies of the day, including International Nickel Co. and Hudson Bay Mining & Smelting. However, several other Canadian mining companies, including Noranda Mines, refused to take out licences. Mineral Separation sued Noranda Mines for infringement of their patent. In their defence, Noranda Mines contended that the patent was invalid, and therefore, could not be infringed.