Paper Title:
Acid Leaching of Leather Tanning Sludges: Metals Behaviour
  Abstract

Sludges generated in leather tanning processing are very complex wastes with potential deleterious effect on the environment and its management constitutes a high cost for the companies. In this work, sludges from a Portuguese tanning company were characterized and leached with acid solutions in order to evaluate the metals removal yields. The sludges contain, as main metals, 15% Ca, 5% Fe and 2.2 % Cr, in a dry basis. Other minor elements namely Al, Ti, Zn, Pb and Cu were also detected. The leaching experiments were carried out with two types of acids – hydrochloric and sulfuric – and the effects of the reaction time, temperature and leachant concentration were evaluated. The reaction conditions strongly affected the chromium leaching yields, being temperature and acid concentration highly significant (confidence level above 99.9%). About 90% of Cr was leached using the higher levels of the factors (4h, 80°C and 2M H+, with both acids). Concerning the other major metals, iron leaching was very efficient (yields usually above 90%) whatever the conditions tested while calcium behaviour was quite different, depending on the type of acid used for the same H+ concentration: H2SO4 leaching efficiency was generally lower than HCl, probably due to the formation of less soluble calcium sulfate. The maximum calcium removal achieved was near 75%. The leaching process developed can be useful not only as a decontamination step of the tanning sludges, but also as a process for metals recovery to be potentially applied in an integrated recycling system, where several metal wastes from different sources could be processed.

  Info
Periodical
Materials Science Forum (Volumes 587-588)
Edited by
António Torres Marques, António Fernando Silva, António Paulo Monteiro Baptista, Carlos Sá, Fernando Jorge Lino Alves, Luís Filipe Malheiros and Manuel Vieira
Pages
758-762
DOI
10.4028/www.scientific.net/MSF.587-588.758
Citation
P. C. Oliveira, M.C. Rosa, L. Gonçalves, M. A. Trancoso, C. A. Nogueira, "Acid Leaching of Leather Tanning Sludges: Metals Behaviour", Materials Science Forum, Vols. 587-588, pp. 758-762, 2008
Online since
June 2008
Export
Price
$32.00
Share

In order to see related information, you need to Login.

In order to see related information, you need to Login.

Authors: Cheng Jun Liu, Jie Qi, Mao Fa Jiang
Chapter 6: Metallurgical Engineering
Abstract:Utilizing Pakistan chromite as raw material, the rapid leaching of chromium and iron could be realized by the sulfuric acid leaching process...
628