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Pyrite depression by dextrin in flotation with xanthates. Adsorption and floatability studies

López-Valdivieso A., Sanchez-Lopez A. A., Padilla-Ortega E., Robledo-Cabrera A., Galvez E., Cisternas L.

Physicochemical Problems of Mineral Processing

2018

Vol. 54, iss. 4

1159--1171

Depression of pyrite by dextrin in flotation with xanthates has been studied. The adsorption of dextrin and xanthates at the pyrite/aqueous solution interface has been investigated through electrokinetics, Raman spectroscopy and batch adsorption studies using oxidized pyrite. Microflotation studies were undertaken to evaluate the pyrite depression with dextrin using ethyl and propyl xanthates as the collector. The surface density of ferric hydroxide on pyrite depended on pH and was highest about the iep (pH 7.5) of the oxidized pyrite. Dextrin adsorption was directly related to the surface density of ferric hydroxide and took place through two steps suggesting two adsorption mechanisms on ferric hydroxide. Xanthate adsorption as dixanthogen occurred along with ferric hydroxide dissolution causing partial dextrin desorption from the pyrite surface; consequently, co-adsorption of xanthate and dextrin occurred on the surface. Depression of pyrite flotation with xanthate was determined by the oxidation level of the pyrite surface. Floatability of pyrite with xanthate was highly impaired by dextrin at pH 8 only when the surface density of ferric hydroxide on the pyrite surface was very high.

The influence of flotation reagents on sulfur-oxidizing bacteria Acidithiobacillus thiooxidans

Pacholewska M., Cwalina B., Steindor K.

Physicochemical Problems of Mineral Processing

2008

Vol. 42

37-46

It has been demonstrated that various flotation reagents influence, in a different manner, the metabolic activity of the sulfur-oxidizing bacteria Acidithiobacillus thiooxidans (strain C1 being isolated from the Fe-Zn tailings water) growing in the Waksman/Joffe (W/J) liquid culture medium that contains thiosulfate as a sole energy source for bacteria growth. The ethyl- and amyl xanthates as well as the frothing reagent stimulated, to a limited extent, the tested C1-bacteria metabolic activity. The very well documented bacterially-influenced acidification of the W/J solution supplemented with the ethylor the amyl xanthates suggests the possibility of these substances effective acid-degradation in the post-industrial environments rich in various flotation reagents, mainly xanthates. Both the activator containing the carbamate ethyl-derivative and the modifier composed of Cu(II)-ions caused a complete inactivation of the A. thiooxidans C1-metabolism. It is suggested that some unexpected chemical reactions may proceed in the tested systems, as a result of interactions between the culture medium components, flotation reagents, their decomposition products, and also the products of bacterial metabolism.