Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study,...Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.展开更多
Cathode material LiMn2O4 for lithium ion battery was successfully prepared by low heating solid state coordination method. Mixed precursors were tested by TG-DTA to confirm the temperature of thermal decomposition. Th...Cathode material LiMn2O4 for lithium ion battery was successfully prepared by low heating solid state coordination method. Mixed precursors were tested by TG-DTA to confirm the temperature of thermal decomposition. The products from thermal decomposition, LiMn2O4 powders were characterized by XRD, TEM. The results showed that the samples were composed of nanorods assembled by small nanoparticles. The as-prepared LiMn2O4 was of high purity in a good crystal form with a spinel structure type. The powders had uniform chemical composition. The charge-discharge property of LiMn2O4 was also tested. The first charge and discharge capacities for LiMn2O4 were 125.4 mAh·g-1 and 115.3 mAh·g-1, respectively. The efficiency of charge-discharge could be up to 91.95%. In conclusion, LiMn2O4 with better electrochemical property could be obtained by low heating solid state coordination method.展开更多
Ultra-fine powders are difficult to be fluidized due to the strong particle to particle cohesiveness.However,the authors’experiments showed that the ultra-fine powder CaCO 3 could be stably fluidized in a spouted bed...Ultra-fine powders are difficult to be fluidized due to the strong particle to particle cohesiveness.However,the authors’experiments showed that the ultra-fine powder CaCO 3 could be stably fluidized in a spouted bed with a draft tube.The effects of geometric and operating parameters on solid circulation rate of ultra-fine powder CaCO 3 were investigated in a 120 mm diameter transparent semicircular spouted bed with a draft tube.Three draft tubes with different sizes were used in this study.It was found that the solids circulation rate was mainly dependent on the drawing rate of the gas jet from the nozzle, then on the gas transport capacity in the draft tube.With increasing gas feed rate, distance between the nozzle and the draft tube inlet and draft tube diameter,the solids circulation rate could be increased.Based on the jet theory,a quantitative correlation was proposed for predicting the solid circulation rate of ultra-fine powders in a spouted bed with a draft tube by taking into account the gas transport capacity in the draft tube.展开更多
基金supported by the National Key Technology R&D Program (Nos. 2012BAC02B01, 2012BAC12B05, 2011BAE13B07, and 2011BAC10B02)the National High Technology Research and Development Program of China (No. 2012AA063202)+2 种基金the National Natural Science Foundation of China (Nos. 51174247 and 51004011)the Science and Technology Program of Guangdong Province, China (No. 2010A030200003)the Ph.D. Programs Foundation of the Ministry of Education of China (No. 2010000612003)
文摘Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.
文摘Cathode material LiMn2O4 for lithium ion battery was successfully prepared by low heating solid state coordination method. Mixed precursors were tested by TG-DTA to confirm the temperature of thermal decomposition. The products from thermal decomposition, LiMn2O4 powders were characterized by XRD, TEM. The results showed that the samples were composed of nanorods assembled by small nanoparticles. The as-prepared LiMn2O4 was of high purity in a good crystal form with a spinel structure type. The powders had uniform chemical composition. The charge-discharge property of LiMn2O4 was also tested. The first charge and discharge capacities for LiMn2O4 were 125.4 mAh·g-1 and 115.3 mAh·g-1, respectively. The efficiency of charge-discharge could be up to 91.95%. In conclusion, LiMn2O4 with better electrochemical property could be obtained by low heating solid state coordination method.
文摘Ultra-fine powders are difficult to be fluidized due to the strong particle to particle cohesiveness.However,the authors’experiments showed that the ultra-fine powder CaCO 3 could be stably fluidized in a spouted bed with a draft tube.The effects of geometric and operating parameters on solid circulation rate of ultra-fine powder CaCO 3 were investigated in a 120 mm diameter transparent semicircular spouted bed with a draft tube.Three draft tubes with different sizes were used in this study.It was found that the solids circulation rate was mainly dependent on the drawing rate of the gas jet from the nozzle, then on the gas transport capacity in the draft tube.With increasing gas feed rate, distance between the nozzle and the draft tube inlet and draft tube diameter,the solids circulation rate could be increased.Based on the jet theory,a quantitative correlation was proposed for predicting the solid circulation rate of ultra-fine powders in a spouted bed with a draft tube by taking into account the gas transport capacity in the draft tube.
