The uncommon Mg-rich and Ti-poor Zhaoanzhuang serpentine-magnetite ores within Taihua Group of the North China Craton (NCC) remain unclear whether the protolith was sourced from ultramafic rocks or chemical sediment...The uncommon Mg-rich and Ti-poor Zhaoanzhuang serpentine-magnetite ores within Taihua Group of the North China Craton (NCC) remain unclear whether the protolith was sourced from ultramafic rocks or chemical sedimentary sequences. Here we present integrated petrographic and geochemical studies to characterize the protoliths and to gain insights on the ore-forming processes. Iron ores mainly contain low-Ti magnetite (TiO2 -0.1wt%) and serpentine (Mg#=92.42-96.55), as well as residual olivine (Fo=89-90), orthopyroxene (En=89-90) and hornblende. Magnetite in the iron ores shows lower AI, Sc, Ti, Cr, Zn relative to that from ultramafic Fe-Ti-V iron ores, but similar to that from metamorphic chemical sedimentary iron deposit. In addition, interstitial minerals of dolomite, calcite, apatite and anhydrite are intergrown with magnetite and serpentine, revealing they were metamorphic, but not magmatic or late hydrothermal minerals. Wall rocks principally contain magnesian silicates of olivine (Fo=83-87), orthopyroxene (En=82-86), humite (Mg#=82-84) and hornblende [XMg=0.87--0.96]. Dolomite, apatite and anhydrite together with minor magnetite, thorianite (Th-rich oxide) and monazite (LREE-rich phosphate) are often seen as relicts or inclusions within magnesian silicates in the wall rocks, revealing that they were primary or earlier metamorphic minerals than magnesian silicates. And olivine exists as subhedral interstitial texture between hornblende, which shows later formation of olivine than hornblende and does not conform with sequence of magmatic crystallization. All these mineralogical features thus bias towards their metamorphic, rather than magmatic origin. The dominant chemical components of the iron ores are SiO2 (4.77-25.23wt%), Fe203T (32.9-80.39wt%) and MgO (5.72- 27.17wt%) and uniformly, those of the wall rocks are also SiO2 (16.34-48.72wt%), MgO (16.71- 33.97wt%) and Fe203T (6.98-30.92wt%). The striking high Fe-Mg-Si contents reveal that protolith of the Zhaoanzhuang iron deposit was more likely to be chemical sedimentary rocks. The distinct high-Mg feature and presence of abundant anhydrite possibly indicate it primarily precipitated in a confined seawater basin under an evaporitic environment. Besides, higher contents of AI, Ti, P, Th, U, Pb, REE relative to other Precambrian iron-rich chemical precipitates (BIF) suggest some clastic terrestrial materials were probably input. As a result, we think the Zhaoanzhuang iron deposit had experienced the initial Fe-Mg-Si marine precipitation, followed by further Mg enrichment through marine evaporated process, subsequent high-grade metamorphism and late-stage hydrothermal fluid modification.展开更多
The effect of adding 0.03wt%Ni on the microstructure and mechanical properties of Al–Mg–Si–Cu–Zn alloys was systematically studied.The results reveal that the number density of spherical Fe-rich phases within grai...The effect of adding 0.03wt%Ni on the microstructure and mechanical properties of Al–Mg–Si–Cu–Zn alloys was systematically studied.The results reveal that the number density of spherical Fe-rich phases within grains increases with the addition of Ni,accompanied by the formation of Q(Al3Mg9Si7Cu2)precipitates around the spherical Fe-rich phases.Additionally,Ni addition is beneficial to reducing the grain size in the as-cast state.During the homogenization process,Q phases could be completely dissolved and the grain size could remain basically unchanged.However,compared with the Ni-free alloy,the Fe-rich phase in the Ni-containing alloy is more likely to undergo the phase transformation and further form more spherical particles during homogenization treatment.After thermomechanical processing,the distribution of Fe-rich phases in the Ni-containing alloy was further greatly improved and directly resulted in a greater formability than that of the Ni-free alloy.Accordingly,a reasonable Ni addition positively affected the microstructure and formability of the alloys.展开更多
The recycling of high Fe-content Al-Si alloys is a green industry. Eliminating the harmful effect of Fe, achieving the separation of Al and Fe is one of the key problems. Different from traditional methods for iron re...The recycling of high Fe-content Al-Si alloys is a green industry. Eliminating the harmful effect of Fe, achieving the separation of Al and Fe is one of the key problems. Different from traditional methods for iron removal, a novel method using magnesium melt to separate Al and Fe is proposed. By introducing Al-14Si-5Fe alloy into Mg melt, it was found that the γ-Al3.5FeSi phase evolves to Al3SiFe3.5 and Al5Fe2 through the melting and solidification process. Compared with the primary Al-rich γ-Al3.5FeSi phase, the formation of Fe-rich A13SiFe3.5 is quite beneficial for the separation of Al and Fe. Mg-Si-Al and Mg-Si-Fe alloys can be obtained at the top and bottom of the cooled ingot, respectively. The results in this study provide meaningful suggestions for recycling scrap Al-Si-Fe materials.展开更多
基金funded by the National Natural Science Foundation of China (Grant No. 41672078)
文摘The uncommon Mg-rich and Ti-poor Zhaoanzhuang serpentine-magnetite ores within Taihua Group of the North China Craton (NCC) remain unclear whether the protolith was sourced from ultramafic rocks or chemical sedimentary sequences. Here we present integrated petrographic and geochemical studies to characterize the protoliths and to gain insights on the ore-forming processes. Iron ores mainly contain low-Ti magnetite (TiO2 -0.1wt%) and serpentine (Mg#=92.42-96.55), as well as residual olivine (Fo=89-90), orthopyroxene (En=89-90) and hornblende. Magnetite in the iron ores shows lower AI, Sc, Ti, Cr, Zn relative to that from ultramafic Fe-Ti-V iron ores, but similar to that from metamorphic chemical sedimentary iron deposit. In addition, interstitial minerals of dolomite, calcite, apatite and anhydrite are intergrown with magnetite and serpentine, revealing they were metamorphic, but not magmatic or late hydrothermal minerals. Wall rocks principally contain magnesian silicates of olivine (Fo=83-87), orthopyroxene (En=82-86), humite (Mg#=82-84) and hornblende [XMg=0.87--0.96]. Dolomite, apatite and anhydrite together with minor magnetite, thorianite (Th-rich oxide) and monazite (LREE-rich phosphate) are often seen as relicts or inclusions within magnesian silicates in the wall rocks, revealing that they were primary or earlier metamorphic minerals than magnesian silicates. And olivine exists as subhedral interstitial texture between hornblende, which shows later formation of olivine than hornblende and does not conform with sequence of magmatic crystallization. All these mineralogical features thus bias towards their metamorphic, rather than magmatic origin. The dominant chemical components of the iron ores are SiO2 (4.77-25.23wt%), Fe203T (32.9-80.39wt%) and MgO (5.72- 27.17wt%) and uniformly, those of the wall rocks are also SiO2 (16.34-48.72wt%), MgO (16.71- 33.97wt%) and Fe203T (6.98-30.92wt%). The striking high Fe-Mg-Si contents reveal that protolith of the Zhaoanzhuang iron deposit was more likely to be chemical sedimentary rocks. The distinct high-Mg feature and presence of abundant anhydrite possibly indicate it primarily precipitated in a confined seawater basin under an evaporitic environment. Besides, higher contents of AI, Ti, P, Th, U, Pb, REE relative to other Precambrian iron-rich chemical precipitates (BIF) suggest some clastic terrestrial materials were probably input. As a result, we think the Zhaoanzhuang iron deposit had experienced the initial Fe-Mg-Si marine precipitation, followed by further Mg enrichment through marine evaporated process, subsequent high-grade metamorphism and late-stage hydrothermal fluid modification.
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0300801)the National Natural Science Foundation of China(Nos.51871029,51571023,and 51301016)+2 种基金Beijing Natural Science Foundation(No.2172038)Beijing Laboratory of Metallic Materials and Processing for Modern Transportation(No.FRF-SD-B-005B)The China Scholarship Council for financial support to M.X.Guo
文摘The effect of adding 0.03wt%Ni on the microstructure and mechanical properties of Al–Mg–Si–Cu–Zn alloys was systematically studied.The results reveal that the number density of spherical Fe-rich phases within grains increases with the addition of Ni,accompanied by the formation of Q(Al3Mg9Si7Cu2)precipitates around the spherical Fe-rich phases.Additionally,Ni addition is beneficial to reducing the grain size in the as-cast state.During the homogenization process,Q phases could be completely dissolved and the grain size could remain basically unchanged.However,compared with the Ni-free alloy,the Fe-rich phase in the Ni-containing alloy is more likely to undergo the phase transformation and further form more spherical particles during homogenization treatment.After thermomechanical processing,the distribution of Fe-rich phases in the Ni-containing alloy was further greatly improved and directly resulted in a greater formability than that of the Ni-free alloy.Accordingly,a reasonable Ni addition positively affected the microstructure and formability of the alloys.
基金financially supported by the National Natural Science Foundation of China (No. 51601106)the Fundamental Research Funds of Shandong UniversityChina Postdoctoral Science Foundation (No. 2016M600536)
文摘The recycling of high Fe-content Al-Si alloys is a green industry. Eliminating the harmful effect of Fe, achieving the separation of Al and Fe is one of the key problems. Different from traditional methods for iron removal, a novel method using magnesium melt to separate Al and Fe is proposed. By introducing Al-14Si-5Fe alloy into Mg melt, it was found that the γ-Al3.5FeSi phase evolves to Al3SiFe3.5 and Al5Fe2 through the melting and solidification process. Compared with the primary Al-rich γ-Al3.5FeSi phase, the formation of Fe-rich A13SiFe3.5 is quite beneficial for the separation of Al and Fe. Mg-Si-Al and Mg-Si-Fe alloys can be obtained at the top and bottom of the cooled ingot, respectively. The results in this study provide meaningful suggestions for recycling scrap Al-Si-Fe materials.