The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pel...The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pellets require higher preheating temperature and longer preheating time to attain required compression strength of pellets compared with the common magnetite oxidized pellets. It is found that when the hematite concentrates are pretreated by high pressure roll grinding （HPRG）, the compression strengths of preheated and roasted oxidized hematite pellets get improved even with lower preheating and roasting temperatures and shorter preheating and roasting time. The mechanism for HPRG to improve roasting properties of oxidized pellets were investigated and the cause mainly lies in the increase of micro-sized particles and the decrease of dispersion degree for hematite concentrates, which promotes the hematite concentrate particles to be compacted, the solid-phase crystallization, and finally the formation of Fe203 bonding bridges during subsequent high temperature roasting process.展开更多
Cosmogenic Ne isotopes are stable and are routinely used for constraining the timing of events and the rate of surface change beyond the limit that can be studied with radionuclides ^10Be, ^26Al, and ^36Cl. Cosmogenic...Cosmogenic Ne isotopes are stable and are routinely used for constraining the timing of events and the rate of surface change beyond the limit that can be studied with radionuclides ^10Be, ^26Al, and ^36Cl. Cosmogenic Ne analysis can be used in quartz and in a range of other minerals. Analysis typically requires significantly less material than do cosmogenic ^10Be and ^26Al, opening up the technique for small samples--individual pebbles in fiver sediments, for example. Analysis is easier and faster than for radionuclides, not least because Ne measurements do not require significant chemical procedures. However, the presence of other sources of Ne in minerals tends to restrict the use of cosmogenic ^21Ne to old landscapes and long exposure durations. In this review we briefly outline the background of cosmogenic Ne production in rocks and minerals at the Earth＇s surface, then document the key uses of the technique by highlighting some earlier studies, and finish with a short perspective on the future of the technique.展开更多
Zinc silicate ore was characterized mineralogically and the results showed that zinc exists mainly as hemimorphite and smithsonite in the sample.Sulfuric acid pressure leaching of zinc silicate ore was carried out to ...Zinc silicate ore was characterized mineralogically and the results showed that zinc exists mainly as hemimorphite and smithsonite in the sample.Sulfuric acid pressure leaching of zinc silicate ore was carried out to assess the effect of particle size,sulfuric acid concentration,pressure,reaction time and temperature on the extraction of zinc and the dissolution of silica.Under the optimum conditions employed,up to 99.25% of zinc extraction and 0.20% silica dissolution are obtained.The main minerals in leaching residue are quartz and small amounts of undissolved oxide minerals of iron,lead and aluminum are associated with quartz.展开更多
A6×19 point-contact hoisting cable was used as our research object to examine the progress of corrosion of steel wires in a laboratory,simulating the actual working conditions in a coalmine.An electrochemical met...A6×19 point-contact hoisting cable was used as our research object to examine the progress of corrosion of steel wires in a laboratory,simulating the actual working conditions in a coalmine.An electrochemical method was used to investigate the corrosion behavior of steel wires with different surface treatments of a corrosive acid solution.The results show that anode activation of steel wire mainly occurs during pre-corrosion,where the anode activation process of bare steel wires is the fastest as is their corresponding corrosion speed,while the anode activation process of oil coated steel wires and their corresponding corrosion speed are the lowest.During the intermediate and late immersion periods, a passive film is generated on the surface of steel wires,which are gradually damaged with the passage of time.Local pitting corrosion occurs easily on the surface of steel wires with a high-polarization potential. Suitable equivalent circuits were chosen to fit the electrochemical impedance spectroscopy（EIS）of steel wires over various corrosive times and different surface treatments,which indicate good fitting results. The double electrical layer charge-transfer resistance increases in the sequence：bare steel wire, untreated steel wire and oil coated steel wire and their corrosion resistance decreases in turn,which is consistent with their polarization curves.The oil layer provides a certain protective effect on untreated steel wires,but its effect is not entirely clear.展开更多
The aim of this study is to evaluate the influence of Tooth Mousse （TM） application, smear layer removal, and storage time on resin-dentin microtensile bond strength （pTBS）. Dentin specimens were divided into two ...The aim of this study is to evaluate the influence of Tooth Mousse （TM） application, smear layer removal, and storage time on resin-dentin microtensile bond strength （pTBS）. Dentin specimens were divided into two groups： （1） smear layer covered; （2） smear layer removed using 15% EDTA for 90 s. In each group, half the specimens were treated once with TM for 60 min. After bonding procedures using a two-step self-etching adhesive （Clearfil SE Bond （CSE）; Kuraray Medical, Tokyo, Japan）, an all-in-one adhesive （G-Bond （GB）; GC Corp, Tokyo, Japan）, and a total-etch adhesive （Adper Single Bond 2 （SB）; 3M ESPE, St. Paul, MN, USA）, the specimens were stored for 3 d or 6 months in deionized water at 37 ℃, and pTBS was tested and analyzed. With the exception of SB （no TM application） and GB, the pTBS was significantly increased for CSE and SB using EDTA pre-conditioning and 3 d of storage （P≤0.001）. Bond strength of GB decreased significantly when using EDTA （3 d storage, P〈0.05）. TM application only increased the pTBS of GB （no EDTA） and SB （with EDTA） after 3 d （P≤0.02）. Comparing the adhesives after 3 d of storage, CSE exhibited the greatest pTBS values followed by GB and SB （P≤0.02）. The factors of adhesive, EDTA, and TM did not show any significant impact on pTBS when specimens were stored for 6 months （P〉0.05）. The additional application of TM and EDTA for cavity preparation seems only to have a short-term effect, and no influence on pTBS of dentin bonds after a period of 6 months.展开更多
基金Project(50725416) supported by the National Natural Science Funds for Distinguished Young Scholars of China
文摘The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pellets require higher preheating temperature and longer preheating time to attain required compression strength of pellets compared with the common magnetite oxidized pellets. It is found that when the hematite concentrates are pretreated by high pressure roll grinding （HPRG）, the compression strengths of preheated and roasted oxidized hematite pellets get improved even with lower preheating and roasting temperatures and shorter preheating and roasting time. The mechanism for HPRG to improve roasting properties of oxidized pellets were investigated and the cause mainly lies in the increase of micro-sized particles and the decrease of dispersion degree for hematite concentrates, which promotes the hematite concentrate particles to be compacted, the solid-phase crystallization, and finally the formation of Fe203 bonding bridges during subsequent high temperature roasting process.
基金supported by the basic scientific research fund, Institute of Geology, China Earthquake Administration (Grant Nos. IGCEA1504 and IGCEA1417)
文摘Cosmogenic Ne isotopes are stable and are routinely used for constraining the timing of events and the rate of surface change beyond the limit that can be studied with radionuclides ^10Be, ^26Al, and ^36Cl. Cosmogenic Ne analysis can be used in quartz and in a range of other minerals. Analysis typically requires significantly less material than do cosmogenic ^10Be and ^26Al, opening up the technique for small samples--individual pebbles in fiver sediments, for example. Analysis is easier and faster than for radionuclides, not least because Ne measurements do not require significant chemical procedures. However, the presence of other sources of Ne in minerals tends to restrict the use of cosmogenic ^21Ne to old landscapes and long exposure durations. In this review we briefly outline the background of cosmogenic Ne production in rocks and minerals at the Earth＇s surface, then document the key uses of the technique by highlighting some earlier studies, and finish with a short perspective on the future of the technique.
基金Project(2007CB613605) supported by the National Basic Research Program of China
文摘Zinc silicate ore was characterized mineralogically and the results showed that zinc exists mainly as hemimorphite and smithsonite in the sample.Sulfuric acid pressure leaching of zinc silicate ore was carried out to assess the effect of particle size,sulfuric acid concentration,pressure,reaction time and temperature on the extraction of zinc and the dissolution of silica.Under the optimum conditions employed,up to 99.25% of zinc extraction and 0.20% silica dissolution are obtained.The main minerals in leaching residue are quartz and small amounts of undissolved oxide minerals of iron,lead and aluminum are associated with quartz.
基金supported by the National Natural Science Foundation of China(No.50875252)the Program for New Century Excellent Talents in University(No.NCET-06-0479).
文摘A6×19 point-contact hoisting cable was used as our research object to examine the progress of corrosion of steel wires in a laboratory,simulating the actual working conditions in a coalmine.An electrochemical method was used to investigate the corrosion behavior of steel wires with different surface treatments of a corrosive acid solution.The results show that anode activation of steel wire mainly occurs during pre-corrosion,where the anode activation process of bare steel wires is the fastest as is their corresponding corrosion speed,while the anode activation process of oil coated steel wires and their corresponding corrosion speed are the lowest.During the intermediate and late immersion periods, a passive film is generated on the surface of steel wires,which are gradually damaged with the passage of time.Local pitting corrosion occurs easily on the surface of steel wires with a high-polarization potential. Suitable equivalent circuits were chosen to fit the electrochemical impedance spectroscopy（EIS）of steel wires over various corrosive times and different surface treatments,which indicate good fitting results. The double electrical layer charge-transfer resistance increases in the sequence：bare steel wire, untreated steel wire and oil coated steel wire and their corrosion resistance decreases in turn,which is consistent with their polarization curves.The oil layer provides a certain protective effect on untreated steel wires,but its effect is not entirely clear.
基金Project supported by the National Natural Science Foundation of China(Nos.81271955 and 30973350)the Zhejiang Provincial Natural Science Foundation of China(No.Y2080338)
文摘The aim of this study is to evaluate the influence of Tooth Mousse （TM） application, smear layer removal, and storage time on resin-dentin microtensile bond strength （pTBS）. Dentin specimens were divided into two groups： （1） smear layer covered; （2） smear layer removed using 15% EDTA for 90 s. In each group, half the specimens were treated once with TM for 60 min. After bonding procedures using a two-step self-etching adhesive （Clearfil SE Bond （CSE）; Kuraray Medical, Tokyo, Japan）, an all-in-one adhesive （G-Bond （GB）; GC Corp, Tokyo, Japan）, and a total-etch adhesive （Adper Single Bond 2 （SB）; 3M ESPE, St. Paul, MN, USA）, the specimens were stored for 3 d or 6 months in deionized water at 37 ℃, and pTBS was tested and analyzed. With the exception of SB （no TM application） and GB, the pTBS was significantly increased for CSE and SB using EDTA pre-conditioning and 3 d of storage （P≤0.001）. Bond strength of GB decreased significantly when using EDTA （3 d storage, P〈0.05）. TM application only increased the pTBS of GB （no EDTA） and SB （with EDTA） after 3 d （P≤0.02）. Comparing the adhesives after 3 d of storage, CSE exhibited the greatest pTBS values followed by GB and SB （P≤0.02）. The factors of adhesive, EDTA, and TM did not show any significant impact on pTBS when specimens were stored for 6 months （P〉0.05）. The additional application of TM and EDTA for cavity preparation seems only to have a short-term effect, and no influence on pTBS of dentin bonds after a period of 6 months.
