| The flotation behaviors of salicylhydroxamic acid,benzohydroxamic acid and octanohydroxamic acid on fine cassiterite,quartz and calcite were studied in this paper.Meanwhile,the effects of common inhibitors and metal ions on flotation of cassiterite were studied with octanohydroxamic acid as collector.The interaction mechanism of octanohydroxamic acid and cassiterite and the effect of metal ions on flotation of cassiterite were studied by adsorption experiments,contact angle measurement,fourier transform infrared spectroscopy?FTIR?measurement,zeta???-potential measurement,X-ray photoelectron spectroscopy?XPS?,and atomic force microscopy?AFM?imaging.The flotation test results showed that the collecting ability of three hydroxamic acid collectors for cassiterite is as follows:octanohydroxamic acid>benzohydroxamic acid>salicylhydroxamic acid.Using octanohydroxamic acid as collector,sodium hexametaphosphate can act as inhibitor for the separation of cassiterite and calcite.Only lead ions can activate the flotation of cassiterite.Calcium,magnesium,and iron ions all have a strong inhibitory effect on the floatation of cassiterite.The collecting mechanism of octanohydroxamic acid on cassiterite showed that the adsorption amount of octanohydroxamic acid on cassiterite surface increased firstly and then decreased with the increase of pH,when the concentration of octanohydroxamic acid reached 45 mg/L,octanohydroxamic acid formed multi-layer adsorption on cassiterite surface.The contact angle of cassiterite surface increased with the addition of octanohydroxamic acid.The results of infrared spectroscopy showed that octanohydroxamic acid could coordinate strongly with tin,and octanohydroxamic acid reacted with cassiterite to form five-membered cyclic compounds.?-potential test results showed that octanohydroxamic acid negatively shifted the point of zero charge of cassiterite and decreased the?-potentials of cassiterite.The results of solution chemistry of octanohydroxamic acid showed that the ionic octanohydroxamic acid co-adsorbed with molecular octanohydroxamic acid on the cassiterite surface in the pH range with the highest recovery of cassiterite.XPS analysis indicated that chemisorption of octanohydroxamic acid on cassiterite surface changed the chemical environment of the elements on it.The mechanism of metal ions on cassiterite flotation showed that The addition of lead ions enhanced the adsorption of octanohydroxamic acid on cassiterite,and the addition of lead ions increased the contact angle of cassiterite surface.The addition of calcium,magnesium,and iron ions made the contact angle significantly smaller and the wettability of cassiterite decreased.?-Potential measurements and solution chemistry analyses confirmed that flotation recovery of the cassiterite increased due to Pb?OH?+and Pb3?OH?42+sites on the cassiterite surface,the components of calcium,magnesium and iron ions that inhibited cassiterite flotation should be CaOH+,Mg2+.and MgOH+,Fe?OH?3.XPS results indicated the adsorption of lead ions and calcium ions on the cassiterite surface was chemisorption.FTIR measurements confirmed that the presence of calcium ions,magnesium ions,and iron ions made the characteristic peaks produced by the action of cassiterite and octanohydroxamic acid become weak or disappear,thus inhibited the floatation of cassiterite.AFM images concluded that the Fe?OH?3 colloids on cassiterite impeded the adsorption of octanohydroxamic acid. |
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