Abstract
The activation of scheelite and wolframite by lead nitrate with benzohydroxamic acid (BHA) as collector was investigated by means of micro flotation test, zeta potential measurement, X-ray photoelectron spectroscopy (XPS) analyses and density functional theory (DFT) calculation. The flotation results confirmed that the addition of lead nitrate can markedly enhance the recovery of scheelite and wolframite. In the zeta potential curves obvious positive shifts were observed with the presence of lead nitrate. Lead was detected on mineral surface in microscopic analysis and the survey XP spectra. Both the electrokinetic study and XPS analyses indicated that lead ion can be adsorbed onto mineral surface. In DFT calculation, the coordination model of BHA with metal hydroxyl ions (Ca(OH)+, Mn(OH)+, Fe(OH)+ and Pb(OH)+) was simulated and their binding energy were also calculated. The calculated results revealed that the binding ability of BHA and Pb(OH)+ is the strongest, indicating that BHA can preferentially coordinate with Pb ion compared with Ca, Mn and Fe ions.
Highlights
Scheelite and wolframite ores are the most widely occurring tungsten minerals and have become the major raw materials in the tungsten industry
When hydroxamic acids are employed in the flotation of scheelite and wolframite, lead nitrate is widely applied as the activating agent
We have examined the floatability of scheelite and wolframite by means of micro flotation, electrokinetic study and X-ray photoelectron spectroscopy (XPS) with quantum chemistry calculation as innovative approach to discuss the activation mechanism of lead nitrate experimentally and theoretically
Summary
Scheelite and wolframite ores are the most widely occurring tungsten minerals and have become the major raw materials in the tungsten industry. The chelating performance of hydroxamic acids with transition metals including Fe, Ni, Cu and Zn has been studied through theoretical and experimental methods [4,5,6]. When hydroxamic acids are employed in the flotation of scheelite and wolframite, lead nitrate is widely applied as the activating agent. In spite of a large number of studies conducted in the past, there are few reports about the DFT research for the coordination between hydroxamic acids and metal ions, much less for the activation of minerals, so the activation of scheelite and wolframite by lead nitrate is not yet well understood. We have examined the floatability of scheelite and wolframite by means of micro flotation, electrokinetic study and X-ray photoelectron spectroscopy (XPS) with quantum chemistry calculation as innovative approach to discuss the activation mechanism of lead nitrate experimentally and theoretically
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