Chromium has been widely used in many industrial applications. As a result of chromite ore processing, large amounts of chromite ore processing waste (COPW) material that can be classified as hazardous have been produced and released into the environment.
Therefore, knowledge of migration behavior and leaching rates of chromium through waste materials and soils are of primary concern for environmentally sound management
of land-disposal hazardous wastes. Haskö / k (1998) experimentally studied leaching rates
of total Cr and Cr(VI) using laboratory columns packed with chromium COPW material produced by a sodium chromite plant. Based on the experimental results of Haskö / k (1998), present study aim, through mathematical modeling, to understand the dissolution
kinetics of chromium during leaching of COPW material and to investigate the
effectiveness of intermittent leaching involving a sequence of batch (dissolution) and
leaching (mass flushing) operational modes. Obtained results show that a coupled system of two first order differential equations was able to capture the essential characteristics of leaching behavior of COPW material. In addition, the kinetics of chromium dissolution from COPW appeared to be controlled by the difference between
aqueous phase concentration and a saturation concentration, by the mass fraction of dissolvable chromium remaining in the solid phase, and finally by the contribution of a constant dissolution rate manifested as a steady-state tailing behavior. As a result of
performed simulations it was seen that intermittent leaching could be 65%and 35% more effective than continuous leaching for total Cr and Cr(VI), respectively.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/4/1053412/index.pdf |
| Date | 01 January 2003 |
| Creators | Yalcin, Sezgin |
| Contributors | Unlu, Kahraman |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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