Flotation tailings were successfully flocculated in the presence of cationic polyacrylamide and silica gel.The effects of various parameters such as polymer weight,charge density,and pH on the rate of flocculation wer...Flotation tailings were successfully flocculated in the presence of cationic polyacrylamide and silica gel.The effects of various parameters such as polymer weight,charge density,and pH on the rate of flocculation were also investigated in the current study.The flocculation mechanism of the flocculant on tailings was investigated using zeta potential and Fourier transform infrared(FTIR)measurements.The results obtained reveal that 1)sodium silicate gel,used as a binder for the consolidation of tailings form primary flocs,acts as an anchor and the adsorption of polymer flocculant on these anchors results in the formation of larger flocs and,consequently,enhanced settling rate;2)flocculation in the presence of silica gel and polymer has a faster settling rate than single-polymer flocculation owing to the mechanisms of charge neutralization and bridging as identified using zeta potential and FTIR measurements.A pilot level study was conducted to investigate the influence of processed water on the flotation of scheelite.The results show that the proposed tailing disposal method could improve scheelite recovery by 2%(approximately)and could reduce the daily operation costs of the plant by approximately 108.57 USD.展开更多
The linear potential sweep voltammetry and electrochemical methods were used to study the mechanism and kinetics of gold dissolution in thiourea solution in the absence and presence of sodium sulphite.The results show...The linear potential sweep voltammetry and electrochemical methods were used to study the mechanism and kinetics of gold dissolution in thiourea solution in the absence and presence of sodium sulphite.The results show that in the absence of sodium sulfite the dissolution rate of gold in thiourea solution is relatively slow and it increases with the increase of the concentration of thiourea and decreases with pH. Thiourea is easily oxidized to formamidine disulphide, which reduces the leaching efficiency and increases reagent consumption. In the presence of sodium sulphite, the effective concentration of thiourea is increased and the dissolution rate of gold in thiourea solution is greatly increased. The activation energy required for gold dissolution in thiourea solution with sodium sulphite is 20.9 kJ·mol -1 which is much lower than 55.0 kJ·mol -1 in the absence of sodium sulphite. It is evident that sodium sulphite has a significant effect on the electrochemical reaction kinetics of gold in thiourea solution.展开更多
Background Due to the quick rhythm of life and work pressure, more and more people suffer from sleep quality problems. In this study, we investigated the effect of electroacupuncture on sleep quality of chronic insomn...Background Due to the quick rhythm of life and work pressure, more and more people suffer from sleep quality problems. In this study, we investigated the effect of electroacupuncture on sleep quality of chronic insomniacs and the safety of electroacupuncture therapy. Methods Four courses of electroacupuncture treatment were applied to 47 patients. With pre-treatment and post-treatment self-control statistical method, Pittsburgh sleep quality index （PSQI） scores were used for evaluating sleep quality. Polysomnogram was used for detecting insomniacs＇ changes in sleep architecture. The safety of electroacupuncture was evaluated by monitoring the self-designed adverse events and side effects during treatment and post-treatment. Results Electroacupuncture considerably improved insomniacs＇ sleep quality and social function during the daytime. Electroacupuncture had certain repairing effect on the disruption in sleep architecture. At the same time, electroacupuncture prolonged slow wave sleep （SWS） time and relatively rapid eye movement sleep （REM sleep） time. There was no hangover, addiction or decrements in vigilance during the daytime （incidence rate was 0）. However, insomnia rebound rate was about 23% within one month. Conclusions These results suggest that electroacupuncture has beneficial effect on sleep quality improvement in the patients with chronic insomnia, which may be associated with repairing sleep architecture, reconstructing sleep continuity as well as prolonging SWS time and REM sleep time. Electroacupuncture treatment for chronic insomnia is safe. Therefore, electroacupuncture therapy could be a promising avenue of treatment for chronic insomnia.展开更多
基金Project(2016zzts109)supported by the Innovation Driven Plan of Central South University,ChinaProject(2015CX005)supported by the Innovation driven Program of National Basic Research Program of ChinaProject(B14034)supported by the Program of Introdution Talents of Discipline to Universities,China(111 Project)
文摘Flotation tailings were successfully flocculated in the presence of cationic polyacrylamide and silica gel.The effects of various parameters such as polymer weight,charge density,and pH on the rate of flocculation were also investigated in the current study.The flocculation mechanism of the flocculant on tailings was investigated using zeta potential and Fourier transform infrared(FTIR)measurements.The results obtained reveal that 1)sodium silicate gel,used as a binder for the consolidation of tailings form primary flocs,acts as an anchor and the adsorption of polymer flocculant on these anchors results in the formation of larger flocs and,consequently,enhanced settling rate;2)flocculation in the presence of silica gel and polymer has a faster settling rate than single-polymer flocculation owing to the mechanisms of charge neutralization and bridging as identified using zeta potential and FTIR measurements.A pilot level study was conducted to investigate the influence of processed water on the flotation of scheelite.The results show that the proposed tailing disposal method could improve scheelite recovery by 2%(approximately)and could reduce the daily operation costs of the plant by approximately 108.57 USD.
文摘The linear potential sweep voltammetry and electrochemical methods were used to study the mechanism and kinetics of gold dissolution in thiourea solution in the absence and presence of sodium sulphite.The results show that in the absence of sodium sulfite the dissolution rate of gold in thiourea solution is relatively slow and it increases with the increase of the concentration of thiourea and decreases with pH. Thiourea is easily oxidized to formamidine disulphide, which reduces the leaching efficiency and increases reagent consumption. In the presence of sodium sulphite, the effective concentration of thiourea is increased and the dissolution rate of gold in thiourea solution is greatly increased. The activation energy required for gold dissolution in thiourea solution with sodium sulphite is 20.9 kJ·mol -1 which is much lower than 55.0 kJ·mol -1 in the absence of sodium sulphite. It is evident that sodium sulphite has a significant effect on the electrochemical reaction kinetics of gold in thiourea solution.
文摘Background Due to the quick rhythm of life and work pressure, more and more people suffer from sleep quality problems. In this study, we investigated the effect of electroacupuncture on sleep quality of chronic insomniacs and the safety of electroacupuncture therapy. Methods Four courses of electroacupuncture treatment were applied to 47 patients. With pre-treatment and post-treatment self-control statistical method, Pittsburgh sleep quality index （PSQI） scores were used for evaluating sleep quality. Polysomnogram was used for detecting insomniacs＇ changes in sleep architecture. The safety of electroacupuncture was evaluated by monitoring the self-designed adverse events and side effects during treatment and post-treatment. Results Electroacupuncture considerably improved insomniacs＇ sleep quality and social function during the daytime. Electroacupuncture had certain repairing effect on the disruption in sleep architecture. At the same time, electroacupuncture prolonged slow wave sleep （SWS） time and relatively rapid eye movement sleep （REM sleep） time. There was no hangover, addiction or decrements in vigilance during the daytime （incidence rate was 0）. However, insomnia rebound rate was about 23% within one month. Conclusions These results suggest that electroacupuncture has beneficial effect on sleep quality improvement in the patients with chronic insomnia, which may be associated with repairing sleep architecture, reconstructing sleep continuity as well as prolonging SWS time and REM sleep time. Electroacupuncture treatment for chronic insomnia is safe. Therefore, electroacupuncture therapy could be a promising avenue of treatment for chronic insomnia.
