The impact of alkyl dimethyl betaine (ADB) on the collection capacity of sodium oleate (NaOl) at low temperatures was evaluated using flotation tests at various scales. The low-temperature synergistic mechanism of ADB...The impact of alkyl dimethyl betaine (ADB) on the collection capacity of sodium oleate (NaOl) at low temperatures was evaluated using flotation tests at various scales. The low-temperature synergistic mechanism of ADB and NaOl was explored by infrared spectroscopy, X-ray photoelectron spectroscopy, surface tension measurement, foam performance test, and flotation reagent size measurement.The flotation tests revealed that the collector mixed with octadecyl dimethyl betaine (ODB) and NaOl in a mass ratio of 4:96 exhibited the highest collection capacity. The combined collector could increase the scheelite recovery by 3.48% at low temperatures of 8–12℃. This is particularly relevant in the Luanchuan area, which has the largest scheelite concentrate output in China. The results confirmed that ODB enhanced the collection capability of NaOl by improving the dispersion and foaming performance. Betaine can be introduced as an additive to NaOl to improve the recovery of scheelite at low temperatures.展开更多
In this study, the innovative use of ethylenediamine tetramethylene phosphonic sodium(EDTMPS) as a calcite depressant in scheelite flotation was investigated by flotation experiments, and its selective depression mech...In this study, the innovative use of ethylenediamine tetramethylene phosphonic sodium(EDTMPS) as a calcite depressant in scheelite flotation was investigated by flotation experiments, and its selective depression mechanism was revealed by contact angle measurement, FTIR analysis, Zeta potential test and XPS analysis. The flotation experiment results showed that scheelite and calcite could be efficiently separated under the following conditions: pulp p H=9.5, Na OL concentration of 1.5×10^(-4)mol/L, EDTMPS concentration of 3.0×10^(-5)mol/L, a scheelite concentrate with WO3grade of 65.49%, recovery of 83.29%and separation efficiency of 65.29% could be obtained from the artificially mixed minerals. The analysis results of mineral surface properties demonstrated that EDTMPS was strongly adsorbed onto the calcite surface through the reaction between the phosphonate group and the calcium ions, which hindered Na OL adsorption and increased the hydrophilicity of calcite. However, EDTMPS had weak adsorption strength on the scheelite surface, which didn’t affect further adsorption of Na OL, hence, the scheelite remained hydrophobic. Consequently, the selective adsorption of EDTMPS on the two minerals’ surfaces increased a difference in wettability and thus enabling them to be separated by flotation. Finally, the mechanism model of this flotation separation process was established.展开更多
The disposal of fly ash has become a serious problem in China due to its rapid increase in volume in recent years.The most common method of fly ash disposal is solidification-stabilization-landfill,and the most common...The disposal of fly ash has become a serious problem in China due to its rapid increase in volume in recent years.The most common method of fly ash disposal is solidification-stabilization-landfill,and the most common reuse is low-value-added building materials.A novel processing method for preparing ultra-lightweight ceramsite with fly ash was developed.The results show that the optimal parameters for preparation of ultra-lightweight ceramsite are as follows:mass ratio of fly ash:kaolin:diatomite=80:15:5,preheating temperature of 800℃,preheating time of 5 min,sintering temperatiire of 1220℃,and sintering time of 10 min.The expansion agent is perlite,at 10 wt.% addition.Finally,a ceramsite with bulk density of 340 kg/m3,particle density of 0.68 g/cm3,and cylinder compressive strength of 1.02 MPa was obtained.Because of its low density and high porosity,ultra-lightweight ceramsite has excellent thermal insulation performance,and its strength is generally low,so it is usually used in the production of thermal insulation concrete and its products.The formation of a liquid-phase component on the surface,and generation of a gas phase inside ceramsite during the sintering process,make it possible to control the production of the suitable liquid phase and gas in this system,resulting in an optimization of the expansion behavior and microstructure of ceramsite.These characteristics show the feasibility of industrial applications of fly ash for the production of ultralightweight ceramsite,which could not only produce economic benefits,but also conserve land resources and protect the environment.展开更多
Tin is of key importance to daily life and national security;it is considered an essential industrial metal.The United States(US)is the world’s largest economy and consumer of natural resources.Therefore,the analysis...Tin is of key importance to daily life and national security;it is considered an essential industrial metal.The United States(US)is the world’s largest economy and consumer of natural resources.Therefore,the analysis of historical tin use in the US is helpful for understanding future tin use trends in the world as a whole and in developing countries.Time series analysis,regression analysis with GDP or GDP/capita,and historical data fitted with logistic and Gompertz models are employed in this study.Historical tin use in the US shows three stages-increase-constant-decrease,as GDP per capita has increased.Tin use in the US is negatively correlated with the GDP value added by the manufacturing sector,while the use of tin worldwide and in China continues to increase along with the GDP value added by the manufacturing sector.Although a sigmoid curve can fit the US tin use data well,that use is not directly related to the limited tin reserves or resources.Rather,policies,economic restructuring,substitutions,new end-use markets,etc.have played key roles in the changing tin use patterns.This work contributes to understanding future tin use at both the global and national levels:tin use will continue to increase with GDP at the global level,but use patterns of tin at the national level can be changed through human intervention.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.51904339 and No.51974364)the Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources,China (No.2018TP1002)the Co-Innovation Centre for Clean and Efficient Utilization of Strategic Metal Mineral Resources,and the Postgraduate Independent Exploration and Innovation Project of Central South University,China (No.2018zzts224)。
文摘The impact of alkyl dimethyl betaine (ADB) on the collection capacity of sodium oleate (NaOl) at low temperatures was evaluated using flotation tests at various scales. The low-temperature synergistic mechanism of ADB and NaOl was explored by infrared spectroscopy, X-ray photoelectron spectroscopy, surface tension measurement, foam performance test, and flotation reagent size measurement.The flotation tests revealed that the collector mixed with octadecyl dimethyl betaine (ODB) and NaOl in a mass ratio of 4:96 exhibited the highest collection capacity. The combined collector could increase the scheelite recovery by 3.48% at low temperatures of 8–12℃. This is particularly relevant in the Luanchuan area, which has the largest scheelite concentrate output in China. The results confirmed that ODB enhanced the collection capability of NaOl by improving the dispersion and foaming performance. Betaine can be introduced as an additive to NaOl to improve the recovery of scheelite at low temperatures.
基金the National Natural Science Foundation of China(Nos.51604302 and 51574282)the Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources(No.2018TP1002).
文摘In this study, the innovative use of ethylenediamine tetramethylene phosphonic sodium(EDTMPS) as a calcite depressant in scheelite flotation was investigated by flotation experiments, and its selective depression mechanism was revealed by contact angle measurement, FTIR analysis, Zeta potential test and XPS analysis. The flotation experiment results showed that scheelite and calcite could be efficiently separated under the following conditions: pulp p H=9.5, Na OL concentration of 1.5×10^(-4)mol/L, EDTMPS concentration of 3.0×10^(-5)mol/L, a scheelite concentrate with WO3grade of 65.49%, recovery of 83.29%and separation efficiency of 65.29% could be obtained from the artificially mixed minerals. The analysis results of mineral surface properties demonstrated that EDTMPS was strongly adsorbed onto the calcite surface through the reaction between the phosphonate group and the calcium ions, which hindered Na OL adsorption and increased the hydrophilicity of calcite. However, EDTMPS had weak adsorption strength on the scheelite surface, which didn’t affect further adsorption of Na OL, hence, the scheelite remained hydrophobic. Consequently, the selective adsorption of EDTMPS on the two minerals’ surfaces increased a difference in wettability and thus enabling them to be separated by flotation. Finally, the mechanism model of this flotation separation process was established.
基金The authors gratefully acknowledge the financial support by the National Natural Science Foundation of China(Nos.51804342 and 51874356)the Collaborative Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources,and the Scientific Research Starting Foundation of Central South University(No.218041).
文摘The disposal of fly ash has become a serious problem in China due to its rapid increase in volume in recent years.The most common method of fly ash disposal is solidification-stabilization-landfill,and the most common reuse is low-value-added building materials.A novel processing method for preparing ultra-lightweight ceramsite with fly ash was developed.The results show that the optimal parameters for preparation of ultra-lightweight ceramsite are as follows:mass ratio of fly ash:kaolin:diatomite=80:15:5,preheating temperature of 800℃,preheating time of 5 min,sintering temperatiire of 1220℃,and sintering time of 10 min.The expansion agent is perlite,at 10 wt.% addition.Finally,a ceramsite with bulk density of 340 kg/m3,particle density of 0.68 g/cm3,and cylinder compressive strength of 1.02 MPa was obtained.Because of its low density and high porosity,ultra-lightweight ceramsite has excellent thermal insulation performance,and its strength is generally low,so it is usually used in the production of thermal insulation concrete and its products.The formation of a liquid-phase component on the surface,and generation of a gas phase inside ceramsite during the sintering process,make it possible to control the production of the suitable liquid phase and gas in this system,resulting in an optimization of the expansion behavior and microstructure of ceramsite.These characteristics show the feasibility of industrial applications of fly ash for the production of ultralightweight ceramsite,which could not only produce economic benefits,but also conserve land resources and protect the environment.
基金funded by the National Key R&D Program of China(Grant No.2018YFC1902505)Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources(No.2018TP1002)the Co-Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources.
文摘Tin is of key importance to daily life and national security;it is considered an essential industrial metal.The United States(US)is the world’s largest economy and consumer of natural resources.Therefore,the analysis of historical tin use in the US is helpful for understanding future tin use trends in the world as a whole and in developing countries.Time series analysis,regression analysis with GDP or GDP/capita,and historical data fitted with logistic and Gompertz models are employed in this study.Historical tin use in the US shows three stages-increase-constant-decrease,as GDP per capita has increased.Tin use in the US is negatively correlated with the GDP value added by the manufacturing sector,while the use of tin worldwide and in China continues to increase along with the GDP value added by the manufacturing sector.Although a sigmoid curve can fit the US tin use data well,that use is not directly related to the limited tin reserves or resources.Rather,policies,economic restructuring,substitutions,new end-use markets,etc.have played key roles in the changing tin use patterns.This work contributes to understanding future tin use at both the global and national levels:tin use will continue to increase with GDP at the global level,but use patterns of tin at the national level can be changed through human intervention.
