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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modeling Chromium Leaching From Chromite Ore Processing Waste

Yalcin, Sezgin 01 January 2003 (has links) (PDF)
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. Hask&ouml / 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 Hask&ouml / 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.

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