A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of oper...A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and 4）.55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results.展开更多
The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respective...The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respectively,as a single depressant and their mixture as a combined depressant.Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant(>80%)within the studied dosage range.Galena flotation was severely depressed with descending depressing order as follows:combined depressant﹥sodium silicate﹥sodium sulfite.Electrochemical analysis confirmed the high affinity of depressants on the galena surface,resulting in the formation of hydrophilic species,such as lead sulfite,lead sulfate,and lead orthosilicate.The oxidation of chalcopyrite surface and depressants did not exhibit any signals;conversely,the self-oxidation of chalcopyrite was depressed.The results of cyclic voltammograms well agreed with flotation results,demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.展开更多
The leaching kinetics of selenium from selenium-tellurium-rich materials in sodium sulfite solutions was studied. The morphologies of selenium-tellurium-rich materials are mainly spheroid and columnar bodies and the r...The leaching kinetics of selenium from selenium-tellurium-rich materials in sodium sulfite solutions was studied. The morphologies of selenium-tellurium-rich materials are mainly spheroid and columnar bodies and the range of particle size of selenium-tellurium-rich materials is between 17.77μm and 56.58μm, which contain 41.73%selenium and 40.96%tellurium. The ranges of experimental elements are 126-315 g/L of sodium sulfite concentration, 100-400 r/min of agitation speed, 23-95 ℃ of reaction temperature, 7：1-14：1 of liquid-solid ratio and 17.77-56.58μm of average particle size. The results show that the leaching rate increases with increasing the sodium sulfite concentration, agitation speed, reaction temperature or liquid-solid ratio and the leaching rate decreases with increasing the particle size. The reaction temperature has the significant effects on the selenium leaching rate which increases from 21%to 67%with increasing temperature from 23 ℃ to 95 ℃. The experimental data agree quite well with the Avrami model for leaching, with model parameter of 0.235 and apparent activation energy of 20.847 kJ/mol.展开更多
基金Preoject supported by the Hi-Tech Research and Development Program (863) of China (No. 2001AA642030-1)the Key Research Project of Zhejiang Province (No. 2004C23028)New Century Excellent Scholar Program of Ministry of Education of the People's Republic of China (No.NCET-04-0549)
文摘A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and 4）.55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results.
基金Project(51374247)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China+1 种基金Project(B14034)supported by the National“111”Project,ChinaProject supported by the Open Sharing Fund for Large-scale Instruments and Equipment of Central South University and Collaborative Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources,China。
文摘The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respectively,as a single depressant and their mixture as a combined depressant.Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant(>80%)within the studied dosage range.Galena flotation was severely depressed with descending depressing order as follows:combined depressant﹥sodium silicate﹥sodium sulfite.Electrochemical analysis confirmed the high affinity of depressants on the galena surface,resulting in the formation of hydrophilic species,such as lead sulfite,lead sulfate,and lead orthosilicate.The oxidation of chalcopyrite surface and depressants did not exhibit any signals;conversely,the self-oxidation of chalcopyrite was depressed.The results of cyclic voltammograms well agreed with flotation results,demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.
基金Project(2011B0508000033)supported by the Special Foundation of Guangdong Province Major Science&Technology Program of China
文摘The leaching kinetics of selenium from selenium-tellurium-rich materials in sodium sulfite solutions was studied. The morphologies of selenium-tellurium-rich materials are mainly spheroid and columnar bodies and the range of particle size of selenium-tellurium-rich materials is between 17.77μm and 56.58μm, which contain 41.73%selenium and 40.96%tellurium. The ranges of experimental elements are 126-315 g/L of sodium sulfite concentration, 100-400 r/min of agitation speed, 23-95 ℃ of reaction temperature, 7：1-14：1 of liquid-solid ratio and 17.77-56.58μm of average particle size. The results show that the leaching rate increases with increasing the sodium sulfite concentration, agitation speed, reaction temperature or liquid-solid ratio and the leaching rate decreases with increasing the particle size. The reaction temperature has the significant effects on the selenium leaching rate which increases from 21%to 67%with increasing temperature from 23 ℃ to 95 ℃. The experimental data agree quite well with the Avrami model for leaching, with model parameter of 0.235 and apparent activation energy of 20.847 kJ/mol.
