Complex Metallurgical Problems Solved with DENVER PILOT MILL. This Denver Pilot Mill was built to work out a new metallurgical problem on a particular ore. The results were so successful that the equipment was used for experimental purposes on other ores. By utilizing this flexible method of developing new flowsheets, the loss of time and expense of typing up a large milling plant was eliminated and possible improvements and economies were indicated. The universal acceptance of Denver Test Units by mining companies, governments departments and schools, is due to the fact that test results are accurate, reliable and results can be duplicated in actual practice.