Abstract
The hydrophilic flocculation of pyrite fines in aqueous suspensions with corn starch was studied by measuring particle size distribution, microscopy observation and micro-flotation. Furthermore, the interaction of corn starch with pyrite was investigated by determining the adsorption density and based on zeta potential measurements and X-ray photoelectron spectrometer (XPS) analysis in this work. The results of the particle size distribution measurement show that corn starch can effectively aggregate pyrite fines, and the pyrite floccules (flocs) are sensitive to mechanical stirring. The micro-flotation results suggest that the mechanical entrainment of pyrite fines in flotation can be effectively eliminated through the formation of large-size flocs. The zeta potential of pyrite particles decreases with the addition of corn starch. The XPS results prove that carboxyl groups are generated on the digested corn starch, and both iron hydroxyl compounds and ferrous disulfide on the pyrite surface can chemically interact with the corn starch digested by sodium hydroxide.
Highlights
In froth flotation, mineral particles are floated through two methods: true flotation and mechanical entrainment
Many reports have investigated the depression of pyrite with particle size larger than 30 μm in flotation; they indicate that several depressants such as dextrin, carboxy methyl cellulose (CMC), starch and tannins can significantly depress pyrite in the corresponding conditions because hydrophilic surfaces form on the pyrite [8,9,10,11,12,13,14]
The hydrophilic flocculation of pyrite fines in aqueous suspensions was conducted in a stirring tank (Xing Rui experimental equipment business department, Nantong, China) of 42-mm inner diameter and 100-mm height with a bladefines impeller
Summary
Mineral particles are floated through two methods: true flotation and mechanical entrainment. The former is a selective separation process, by which hydrophobic mineral particles are attached to bubbles and transferred into the froth product. The entrainment is the primary mechanism, by which liberated and dispersed gangue fines (minus 30 μm) enter the froth products [3], which leads to a poor concentrate in grade. It was reported that the formation of hydrophilic flocs of gangue mineral fines before the flotation was an effective method to eliminate the entrainment [4,5,6,7]. If the sulfide ore is finely disseminated (the grain size is smaller than 30 μm), the pyrite is recovered using mechanical entrainment. Few works report on reducing the entrainment of pyrite fines using hydrophilic flocculation
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