2014-Sustainable Industrial Processing Summit
SIPS 2014 Volume 2: Mineral Processing
| Editors: | Kongoli F |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2014 |
| Pages: | 446 pages |
| ISBN: | 978-1-987820-04-1 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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N-carboxymethyl chitosan in differential flotation of galena and chalcopyrite
Yahui Xiang1; Qi Liu1; Kaipeng Wang1;1UNIVERSITY OF ALBERTA, Edmonton, Canada;
Type of Paper: Regular
Id Paper: 18
Topic: 2
Abstract:
In the differential metal sulphide ore flotation, it is desirable to replace the toxic inorganic depressants with environmentally benign chemicals. Chitosan, as a natural and non-toxic material, has been proven to be an efficient depressant for chalcopyrite, while allowing galena to be floated by xanthate collectors. However, the poor solubility of chitosan limits its potential applications as the flotation could only be carried out at pH 4, where chitosan is soluble.
A carboxymethyl derivative of chitosan, named N-carboxymethyl chitosan (N-CMC), was synthesized by replacing the amino groups of chitosan with carboxymethyl groups. The substitution improved significantly the solubility of chitosan.
The structure of N-CMC was investigated and compared with chitosan via Fourier transform infrared spectroscopy (FTIR). Both micro and batch froth flotation tests were performed on single minerals and mineral mixtures (with weight ratio of 1:1) with the addition of appropriate amount of potassium ethyl xanthate (KEX, a collector) and N-CMC to study the selectivity of N-CMC between chalcopyrite and galena. The solution pH was varied from neutral to alkaline. The flotation concentrates and tailings were collected and analysed for the content of copper and lead by using an atomic absorption spectrometer (AAS).
The results of FTIR showed new peaks of C=O stretching of -COOH and N-H deformation of -NH- appeared in N-CMC, which proves that the carboxymethyl groups were introduced and amino groups were the sites for substitution. The flotation tests at pH 7 and pH 10 showed interesting depressive functions of the N-CMC. At pH 7, chalcopyrite was depressed by N-CMC and galena was floated, whereas at pH 10, galena was depressed by N-CMC and chalcopyrite was floated. The results did not seem to be affected by the sequence of KEX or N-CMC addition. Therefore, the N-CMC is potentially useful in Cu-Pb sulphide separation following a bulk Cu-Pb sulphide flotation.