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Comparing cyclohexyl hydroxamic acid and benzohydroxamic acid in cassiterite flotation under lead nitrate activation

Yang Hao, Ou Leming

Physicochemical Problems of Mineral Processing

2023

Vol. 59, iss. 6

art. no. 174673

This paper investigates the flotation behavior of Cyclohexyl hydroxamic acid (CHA) and benzhydroxamic acid (BHA) on cassiterite under lead nitrate activation conditions and elucidates the adsorption mechanism of CHA on the cassiterite surface. Microflotation experiments were performed to compare the capturing efficiency of CHA and BHA at pH values ranging from 4 to 12. Results showed that CHA exhibited superior capability in capturing cassiterite compared to BHA. The recovery of cassiterite in the hydroxamic acid-based flotation system correlated positively with the adsorption of hydroxamic acid on the cassiterite surface. Adsorption experiments revealed an increase in adsorption quantity with an increase in hydroxamic acid dosage, with CHA exhibiting significantly higher adsorption amount than BHA on the cassiterite surface. To analyze the adsorption mechanism of CHA on the cassiterite surface, both infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis were conducted, both before and after lead nitrate activation. IR spectra and XPS results indicated that lead ion activation enhanced the adsorption of CHA on the cassiterite surface, resulting in an increased number of active sites for CHA interaction. Additionally, chemisorption of CHA occurred on the cassiterite surface.

The effect of sodium carboxymethyl cellulose on the entrainment of zoisite in flotation

Zhang Zhengjun, Ou Leming, Jin Saizhen, Zhou Hao

Physicochemical Problems of Mineral Processing

2021

Vol. 57, iss. 2

34--47

During flotation, fine gangue minerals can enter the concentrate through mechanical entrainment, which seriously affects the quality of concentrate. In this work, the effect of sodium carboxymethyl cellulose (CMC) on the flotation performance of zoisite, a silicate mineral, was studied. The role of CMC in reducing zoisite entrainment was investigated by dynamic foaming tests, surface tension measurements, rheology measurements, sedimentation tests, and optical microscopy experiments. The flotation results showed that zoisite mainly entered the concentrate by entrainment; the addition of low dosages of CMC decreased zoisite entrainment and efficiently separated cassiterite from zoisite; moreover, the concentrate grade and recovery of SnO2 increased by 1.27 % and 5.63 %, respectively, by using CMC in closed-circuit flotation tests. Dynamic foaming studies on the two-phase and three-phase foam/froth revealed that the presence of CMC decreased the froth ability and froth stability, and greatly altered the three-phase froth structure. Basically, the bubbles in the foam were larger after adding CMC. For the two-phase foam, the change of foam property had little to do with surface activity and bulk viscosity. For the three-phase froth, the froth property was strongly affected by the interaction of CMC and zoisite. The results of the sedimentation test and microscopy experiment demonstrated that CMC can cause zoisite to flocculate and enlarge the particle size, which was the main reason for the decrease of froth stability and entrainment. This study indicates that the side effects of depressants should not be overlooked when discussing the role of depressants in flotation.