(Campbell Centrifugal Jig)
The Campbell Centrifugal Jig (CCJ) is a mechanical device that uses centrifugal force to separate fine heavy mineral and metal particles from waste materials. The CCJ combines jigging and centrifuging to separate these particles from a fluid slurry. TransMar, Inc., owns the patents and rights to the CCJ technology.
Standard jigs separate solids of different specific gravities by differential settling in a pulsating bed and gravitational field. Jigs operating in this mode can recover solids larger than about 150 mesh (105 microns). Centrifuges are effective in separating solids from liquids but are not effective in separating solids from solids.
The CCJ, shown in the figure below, combines the continuous flow and pulsating bed of the standard jig with the high acceleration forces of a centrifuge to segregate and concentrate heavy particles from the waste. The CCJ can recover particles ranging in size from 1 to about 500 microns, depending on whether the particles are sufficiently disaggregated from the host material. The disaggregated particle should have a specific gravity at least 50 percent greater than the waste material. The CCJ does not need chemicals to separate the solids.
Appropriately sized, slurried material is fed into the CCJ through a hollow shaft inlet at the top of the machine. The slurried material discharges from the shaft onto a diffuser plate, which has vanes that distribute the material radially to the jig bed. The jig bed's surface is composed of stainless-steel shot ragging that is slightly coarser than the screen aperture. The jig bed is pulsated by pressurized water admitted through a screen by four rotating pulse blocks. The pulsing water intermittently fluidizes the bed, causing heavier particles to move through the ragging and screen to the concentrate port, while lighter particles continue across the face of the jig bed to the tailings port.
The effectiveness of separation depends on how well the original solids are disaggregated from the waste material and the specific gravity of each solid. The slurried feed material may require grinding to ensure disaggregation of the heavy metals. Operating parameters include pulse pressure, rotation speed or g-load, screen aperture, ragging type and size, weir height, and feed percent solids.
The CCJ produces heavy mineral or metal concentrates which, depending on the waste material, may be further processed for extraction or sale. A clean tailings stream may be returned to the environment.
The CCJ can separate and concentrate a wide variety of materials, ranging from base metals to fine coal ash and fine (1-micron) gold particles. Applications include (1) remediation of heavy metal-contaminated soils, tailings, or harbor areas containing spilled concentrates; (2) removal of pyritic sulfur and ash from fine coal; and (3) treatment of some sandblasting grit.
The CCJ was accepted into the SITE Emerging Technology Program in May 1992. The CCJ was evaluated at the Montana College of Mineral Science and Technology Research Center (Montana Tech). Montana Tech equipped a pilot plant to evaluate the Series 12 CCJ, which has a capacity of 1 to 3 tons per hour. Tests were completed in August 1994 on base-metal mine tailings from various locations in western Montana. A report on these tests is pending.
In addition, under the U.S. Department of Energy (DOE) Integrated Demonstration Program, the CCJ was tested on clean Nevada test site soil spiked with bismuth as a surrogate for plutonium oxide. These tests occurred at the University of Nevada, Reno, during August and September 1994. In the future, the CCJ will be tested for its ability to remove radioactive contamination from soils from several DOE sites.
EPA PROJECT MANAGER:
Jack Hubbard
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7507
Fax: 513-569-7620
TECHNOLOGY DEVELOPER CONTACT:
Gordon Ziesing
Montana College of Mineral Science and Technology
West Park Street
Butte, MT 59701
406-496-4112
406-496-4193
Fax: 406-496-4133