The mineralogical characteristics of tantalumniobium ores from Songzi were investigated using mineral liberation analyzer （MLA） and chemical analysis. In particular, the chemical composition, phase composition, part...The mineralogical characteristics of tantalumniobium ores from Songzi were investigated using mineral liberation analyzer （MLA） and chemical analysis. In particular, the chemical composition, phase composition, particle size, and dissemination characteristics of the ores were studied in detail. Results show that Ta2O5 and Nb2O5 have grades of 0.013 % and 0.011%, respectively. The main valuable minerals in the ores are tantalite, col- umbite, tantalum-niobite, and microlite, and the gangue minerals associated with tantalum-niobium minerals mainly include quartz, kaolinite, illite, feldspar, and mica among others. The minerals are embedded in a complex manner. Tantalum-niobium minerals with most particle sizes of -0.040 mm are disseminated in minerals, such as mica, illite, quartz, and partially intergrown with topaz and zircon, where they could not be easily liberated. Thus, the ores are classified as low-grade, micro-fine, and refractory tantalum-niobium ores. Based on this consideration, the process of classification-gravity concentration-magnetic separation-middlings regrinding and gravity concentration are finally determined and satisfactory indices are obtained. Two rough concentrates are produced： Concentrate I has Ta2O5 and Nb2O5 grades of 7.0292 % and 3.546 %, respectively, as well as recovery of 49.42 % and 35.46 %. By comparison, Concentrate Ⅱ has Ta2O5 and Nb2O5 grades of 7.0292 % and 3.546 %, respectively, as well as recovery of 49.42 % and 35.46 %.展开更多
Quartz was studied with respect to its silicon isotopic composition and cathodoluminescence in micro-fine disseminated gold deposits in SW Guizhou and NW Guangxi. The resultsshowed that quartz in wall rocks, ores and ...Quartz was studied with respect to its silicon isotopic composition and cathodoluminescence in micro-fine disseminated gold deposits in SW Guizhou and NW Guangxi. The resultsshowed that quartz in wall rocks, ores and that in association with hydrothermal silicificationare distinctive in silicon isotopes and cathodoluminescence characters. Quartz in association withprimary silicification is non-luminescent while that in wall rocks and associated with secondarysilicification exhibits striking luminescence. Based on the dynamic fractionation of silicon isotopes, it is suggested that the mineralization was accompanied by rapid transport of a primarysiliceous fluid along the major deep fault system into subordinate faults before ore componentsdeposited in favorable strata via penetration and metasomatism. Therefore, a deep origin is implicit for gold deposits of this type.展开更多
Jinlongshan gold orebelt, a newly discovered one in sedimentary rock region in southern Qinling Mountains, is mainly located in upper Devonian and lower Carboniferous calcareous siltstone and argillic silty limestone ...Jinlongshan gold orebelt, a newly discovered one in sedimentary rock region in southern Qinling Mountains, is mainly located in upper Devonian and lower Carboniferous calcareous siltstone and argillic silty limestone of later Paleozoic era. Typical disseminated gold mineralization occurred in calcareous siltstone, which is major host rock and mainly composed of silt (SiO2 mostly varies from 38% to 73%) and calcite (CaO mostly varies from 10% to 25%). Pyrite created by living beings in Nanyangshan formation may be poor in gold. Faults and favorable layers jointly control disseminated gold mineralization. The significance of this opinion is very great for gold exploration.展开更多
An experimental investigation on the boiling heat transfer and frictional pressure drop of R245fa in a 7 mm horizontal micro-fin tube was performed.The results show that in terms of flow boiling heat transfer characte...An experimental investigation on the boiling heat transfer and frictional pressure drop of R245fa in a 7 mm horizontal micro-fin tube was performed.The results show that in terms of flow boiling heat transfer characteristics,boiling heat transfer coefficient(HTC)increases with mass velocity of R245fa,while it decreases with the increment of saturation temperature and heat flux.With the increase of vapor quality,HTC has a maximum and the corresponding vapor quality is about 0.4,which varies with the operating conditions.When vapor quality is larger than the transition point,HTC can be promoted more remarkably at higher mass velocity or lower saturation temperature.Among the four selected correlations,KANDLIKAR correlation matches with 91.6%of experimental data within the deviation range of±25%,and the absolute mean deviation is 11.2%.Also,in terms of frictional pressure drop characteristics of flow boiling,the results of this study show that frictional pressure drop increases with mass velocity and heat flux of R245fa,while it decreases with the increment of saturation temperature.MULLER-STEINHAGEN-HECK correlation shows the best prediction accuracy for frictional pressure drop among the four widely used correlations.It covers 84.1%of experimental data within the deviation range of±20%,and the absolute mean deviation is 10.1%.展开更多
Metal fibers have been widely used in many industrial applications due to their unique advantages.In certain applications,such as catalyst supports or orthopedic implants,a rough surface or tiny outshoots on the surfa...Metal fibers have been widely used in many industrial applications due to their unique advantages.In certain applications,such as catalyst supports or orthopedic implants,a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed.However,it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing.In this paper,a special multi-tooth tool composed of a row of triangular tiny teeth is designed.The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting.As a result,several stainless steel fibers with periodic micro-fins are produced simultaneously.Morphology of periodic micro-fins is found to be diverse and can be classified into three categories:unilateral plane,unilateral tapering and bilateral.There are two forming mechanisms for the micro-fins.One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth;the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached.Influence of cutting conditions on formation of micro-fins is investigated.Experimental results show that cutting depth has no significant effect on micro-fin formation,high cutting speed is conducive to micro-fin formation,and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins.This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.展开更多
Using near-azeotropic refrigerant R410A as the working fluid, the experimental studies on the horizontal micro-fin tubes were conducted. Several factors affecting heat transfer coefficients were analyzed, and the char...Using near-azeotropic refrigerant R410A as the working fluid, the experimental studies on the horizontal micro-fin tubes were conducted. Several factors affecting heat transfer coefficients were analyzed, and the characteristics of flow boiling of the refrigerant in the horizontal micro-fin tubes were discussed. The local heat transfer coefficients increase with mass flux, heat flux and quality. And the heat transfer enhancement factor of those testing tubes is about 1.6 to 2.2.展开更多
Micro-finance is providing financial services to poor people, who traditionally lack access to banking and related services. In India, the population of Muslims is about 180 million and the majority of them live below...Micro-finance is providing financial services to poor people, who traditionally lack access to banking and related services. In India, the population of Muslims is about 180 million and the majority of them live below poverty line. The regions where poor Muslims are in majority are marked as negative for providing loans by the banks. Study on interest-free （Islamic） micro-finance for implementation in a country like India can be very helpful in eradicating poverty and developing micro-enterprises together with sustainable development of poor and country as a whole. The primary aim of Islamic teachings （economics） is social justice to all irrespective of caste, creed, race, colour, and religion. Due to this reason, interest （riba） is prohibited not only in Islam but also in Christianity. This paper studies an Islamic micro-finance institution （Anjuman Islahul Muslemeen） situated in Bhopal （Madhya Pradesh）, India. The institution was registered in 1918 by a group of Muslims to help the poor. Today, about 98 years have passed by and all group members have changed but the organization is still growing with the aim of the well-being of poor people, not only Muslims but non-Muslims as well and is serving the humanity.展开更多
基金financially supported by the National Science Foundation of China(No.51104034)the Fundamental Research Funds for the Central Universities(No.N130601003)the Program for New Century Excellent Talents in University of Ministry of Education of China
文摘The mineralogical characteristics of tantalumniobium ores from Songzi were investigated using mineral liberation analyzer （MLA） and chemical analysis. In particular, the chemical composition, phase composition, particle size, and dissemination characteristics of the ores were studied in detail. Results show that Ta2O5 and Nb2O5 have grades of 0.013 % and 0.011%, respectively. The main valuable minerals in the ores are tantalite, col- umbite, tantalum-niobite, and microlite, and the gangue minerals associated with tantalum-niobium minerals mainly include quartz, kaolinite, illite, feldspar, and mica among others. The minerals are embedded in a complex manner. Tantalum-niobium minerals with most particle sizes of -0.040 mm are disseminated in minerals, such as mica, illite, quartz, and partially intergrown with topaz and zircon, where they could not be easily liberated. Thus, the ores are classified as low-grade, micro-fine, and refractory tantalum-niobium ores. Based on this consideration, the process of classification-gravity concentration-magnetic separation-middlings regrinding and gravity concentration are finally determined and satisfactory indices are obtained. Two rough concentrates are produced： Concentrate I has Ta2O5 and Nb2O5 grades of 7.0292 % and 3.546 %, respectively, as well as recovery of 49.42 % and 35.46 %. By comparison, Concentrate Ⅱ has Ta2O5 and Nb2O5 grades of 7.0292 % and 3.546 %, respectively, as well as recovery of 49.42 % and 35.46 %.
文摘Quartz was studied with respect to its silicon isotopic composition and cathodoluminescence in micro-fine disseminated gold deposits in SW Guizhou and NW Guangxi. The resultsshowed that quartz in wall rocks, ores and that in association with hydrothermal silicificationare distinctive in silicon isotopes and cathodoluminescence characters. Quartz in association withprimary silicification is non-luminescent while that in wall rocks and associated with secondarysilicification exhibits striking luminescence. Based on the dynamic fractionation of silicon isotopes, it is suggested that the mineralization was accompanied by rapid transport of a primarysiliceous fluid along the major deep fault system into subordinate faults before ore componentsdeposited in favorable strata via penetration and metasomatism. Therefore, a deep origin is implicit for gold deposits of this type.
文摘Jinlongshan gold orebelt, a newly discovered one in sedimentary rock region in southern Qinling Mountains, is mainly located in upper Devonian and lower Carboniferous calcareous siltstone and argillic silty limestone of later Paleozoic era. Typical disseminated gold mineralization occurred in calcareous siltstone, which is major host rock and mainly composed of silt (SiO2 mostly varies from 38% to 73%) and calcite (CaO mostly varies from 10% to 25%). Pyrite created by living beings in Nanyangshan formation may be poor in gold. Faults and favorable layers jointly control disseminated gold mineralization. The significance of this opinion is very great for gold exploration.
基金Project(51606162)supported by the National Natural Science Foundation of ChinaProject(2018JJ2399)supported by the Natural Science Foundation of Hunan Province,China
文摘An experimental investigation on the boiling heat transfer and frictional pressure drop of R245fa in a 7 mm horizontal micro-fin tube was performed.The results show that in terms of flow boiling heat transfer characteristics,boiling heat transfer coefficient(HTC)increases with mass velocity of R245fa,while it decreases with the increment of saturation temperature and heat flux.With the increase of vapor quality,HTC has a maximum and the corresponding vapor quality is about 0.4,which varies with the operating conditions.When vapor quality is larger than the transition point,HTC can be promoted more remarkably at higher mass velocity or lower saturation temperature.Among the four selected correlations,KANDLIKAR correlation matches with 91.6%of experimental data within the deviation range of±25%,and the absolute mean deviation is 11.2%.Also,in terms of frictional pressure drop characteristics of flow boiling,the results of this study show that frictional pressure drop increases with mass velocity and heat flux of R245fa,while it decreases with the increment of saturation temperature.MULLER-STEINHAGEN-HECK correlation shows the best prediction accuracy for frictional pressure drop among the four widely used correlations.It covers 84.1%of experimental data within the deviation range of±20%,and the absolute mean deviation is 10.1%.
基金Supported by National Natural Science Foundation of China(Grant No.51375176)Guangdong Provincial Natural Science Foundation of China(Grant No.2014A030313264)Fundamental Research Funds for the Central Universities,SCUT,China(Grant No.2013ZZ017)
文摘Metal fibers have been widely used in many industrial applications due to their unique advantages.In certain applications,such as catalyst supports or orthopedic implants,a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed.However,it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing.In this paper,a special multi-tooth tool composed of a row of triangular tiny teeth is designed.The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting.As a result,several stainless steel fibers with periodic micro-fins are produced simultaneously.Morphology of periodic micro-fins is found to be diverse and can be classified into three categories:unilateral plane,unilateral tapering and bilateral.There are two forming mechanisms for the micro-fins.One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth;the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached.Influence of cutting conditions on formation of micro-fins is investigated.Experimental results show that cutting depth has no significant effect on micro-fin formation,high cutting speed is conducive to micro-fin formation,and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins.This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.
基金Shanghai Leading Academic Discipline Project(No.T0503)
文摘Using near-azeotropic refrigerant R410A as the working fluid, the experimental studies on the horizontal micro-fin tubes were conducted. Several factors affecting heat transfer coefficients were analyzed, and the characteristics of flow boiling of the refrigerant in the horizontal micro-fin tubes were discussed. The local heat transfer coefficients increase with mass flux, heat flux and quality. And the heat transfer enhancement factor of those testing tubes is about 1.6 to 2.2.
文摘Micro-finance is providing financial services to poor people, who traditionally lack access to banking and related services. In India, the population of Muslims is about 180 million and the majority of them live below poverty line. The regions where poor Muslims are in majority are marked as negative for providing loans by the banks. Study on interest-free （Islamic） micro-finance for implementation in a country like India can be very helpful in eradicating poverty and developing micro-enterprises together with sustainable development of poor and country as a whole. The primary aim of Islamic teachings （economics） is social justice to all irrespective of caste, creed, race, colour, and religion. Due to this reason, interest （riba） is prohibited not only in Islam but also in Christianity. This paper studies an Islamic micro-finance institution （Anjuman Islahul Muslemeen） situated in Bhopal （Madhya Pradesh）, India. The institution was registered in 1918 by a group of Muslims to help the poor. Today, about 98 years have passed by and all group members have changed but the organization is still growing with the aim of the well-being of poor people, not only Muslims but non-Muslims as well and is serving the humanity.
