Title page for ETD etd-10312005-121330


Document Type Master's Dissertation
Author Strobos, Johannes Gerhardus
URN etd-10312005-121330
Document Title Zinc recovery from baghouse dust generated at Ferrochrome foundries
Degree MEng (Environmental Engineering)
Department Chemical Engineering
Supervisor
Advisor Name Title
Mr J F C Friend
Keywords
  • hydrometallurgy
  • factory and trade waste leaching
  • zink metallurgy
Date 2002-04-21
Availability unrestricted
Abstract
During the production of ferrochrome in electric arc furnaces, a dust is captured in baghouse filters as a means of air pollution control. This dust contains various metals such as chromium, zinc, iron, aluminium and magnesium. Due to the presence of hexavalent chromium in the dust, which is both toxic and carcinogenic, it requires disposal at a hazardous waste disposal site, entailing high cost. The possibility exists that these costs could be reduced if metals such as zinc can be recovered from the dust through, inter alia, leaching. Experiments were performed to determine suitable conditions for the leaching of zinc from such a baghouse dust. A two step leaching procedure was followed which prevented the formation of silica gel. The most favourable conditions for zinc extraction was with a sulphuric acid concentration of 336 g/l and an acid to dust ratio of 0,56. Under these conditions zinc was selectively leached with regard to iron and aluminium. The percentage recovery for zinc was 71,2%, aluminium 1,8% and iron 0,1%. It was concluded that the second step (dilution) of leaching did not have a significant influence on the percentage extraction of metals from the dust.

Consideration of the chemical treatment cost of waste streams produced led to the conclusion that zinc recovery from baghouse dust is not an economically feasible project viewed in isolation. However, compared to disposal at a hazardous waste disposal site such as Holfontein, approximately R467 054,00 per annum (based on a seven day week and baghouse dust production of 3 600 kg/day) can be saved.

2002, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Strobos, JG 2002, Zinc recovery from baghouses dust generated at Ferrochrome foundries, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10312005-121330/ >

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