ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Sludges generated in leather tanning processing are very complex wastes with potentialdeleterious 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 acidsolutions 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 werealso detected. The leaching experiments were carried out with two types of acids – hydrochloric andsulfuric – and the effects of the reaction time, temperature and leachant concentration wereevaluated. The reaction conditions strongly affected the chromium leaching yields, beingtemperature and acid concentration highly significant (confidence level above 99.9%). About 90%of Cr was leached using the higher levels of the factors (4h, 80ºC 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 typeof acid used for the same H+ concentration: H2SO4 leaching efficiency was generally lower thanHCl, probably due to the formation of less soluble calcium sulfate. The maximum calcium removalachieved was near 75%. The leaching process developed can be useful not only as adecontamination step of the tanning sludges, but also as a process for metals recovery to bepotentially applied in an integrated recycling system, where several metal wastes from differentsources could be processed
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/19/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.587-588.758.pdf
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