Pilot Scale Demonstration and Evaluation of Innovative Non-deslimed Non-classified Gravity-fed HM Cyclone

Grants and Contracts Details


The heavy medium (HM) process has long been recognized as one of the most efficient gravity concentration methods, and is widely used to clean coal. Different HM devices work effectively only with a certain size fraction of coal. The crushed raw coal has to be sized and deslimed prior to cleaning by different HM processes. In a typical coal preparation plant, the raw coal is usually crushed to a top size of 5-6 in. (125-150 mm) and then sized and deslimed into +1/4 in. (or 3/8 in.) coarse fraction, -1/4 in. (or -3/8 in.) + 0.5 mm intermediate fraction, and -0.5 mm fine fraction, which are often cleaned by static heavy medium vessels, conventional HM cyclones, and froth flotation, respectively. More recently spirals, TBS, or similar separators have been used to clean the 1-0.15 mm size fraction, which is sometimes referred to as coarse fines, to reduce the feed to the costly froth flotation process. The conventional heavy medium cyclones are fed with a mixture of heavy medium and raw coal under pressure and produce a significant amount of secondary fines. They only work well with deslimed feed coal. The innovative gravity-fed GTC heavy medium cyclone technology is remarkably different from the conventional cyclones and consists of a cylindrical cyclone and a specially designed conical cyclone. It can work very efficiently with non-deslimed nonclassified raw coal down to 0.074 mm with minimal secondary fines. The proposed technology can also eliminate the need for low efficiency gravity separators such as spirals or TBS for coarse fine coal in the washing circuit and minimize the amount of coal fines that have to be cleaned by froth flotation. As a result, the GTC cyclone can greatly simplify the plant flowsheet, improve separation efficiency, save energy consumption and reduce the capital and operating costs by over 20%. The proposed research program is intended to demonstrate and evaluate the innovative GTC gravity-fed non-deslimed non-classified gravity-fed HM cyclone separation process. A systematic study of the proposed technology will be performed using a pilot scale GTC HM cyclone (8 inch. in diameter) with a capacity of 8 tph under different process conditions to investigate the effects of major process parameters on separation performance and identify optimum conditions for a typical Illinois coal. The process parameters to be examined include feed particle size, feed rate, heavy medium flow rate and pressure, vortex finder insertion depth, etc. The separation performance will be evaluated in terms of recovery, separation S.G., organic separation efficiency, probable error, and by-pass on a particle size-by-size basis. Density differential between overflow and underflow will be determined to understand the medium stability and its influence on performance. The magnetite consumption will be measured during the testing program and compared to the conventional HM cyclones. (Keywords: Coal, classification, cyclone, flowsheet, heavy medium, magnetite consumption, separation efficiency)
Effective start/end date7/1/1312/31/14


  • Illinois Clean Coal Institute: $124,966.00


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