Strontianite-rich carbonatite,containing over 30 vol%carbonate minerals predominantly composed of strontianite(SrCO3),is identified in the Zhengjialiangzi ore segment of the Muluozhai rare earth element(REE)deposit,we...Strontianite-rich carbonatite,containing over 30 vol%carbonate minerals predominantly composed of strontianite(SrCO3),is identified in the Zhengjialiangzi ore segment of the Muluozhai rare earth element(REE)deposit,western Sichuan Province,China.It exhibits a unique mineral assemblage dominated by strontianite,fluorite,bastnäsite,barite,calcite and dolomite,distinguishing it from conventional calcio-,magnesio-,ferro-,or natro-carbonatites.The rock shows extreme enrichment in REEs(ΣREE=47335-64367 ppm),with strong LREE/HREE fractionation[(La/Yb)N=1151-2119]and notably high concentrations of high-value critical REEs(e.g.,Pr,Nd,Tb,Dy),5-10 times greater than those in local calcite-dominated carbonatites.Trace element patterns indicate significant enrichment in REEs,Sr,and Ba,along with depletion in high-field-strength elements(HFSEs;e.g.,Nb,Ta,Zr,Hf).In-situ Sr isotopes of strontianite[(^(87)Sr/^(86)Sr)i=0.706190-0.707305]indicate an enriched mantle source(EMI-EMII).Sr enrichment is attributed to initial mantle source enrichment and extensive fractional crystallization,possibly accompanied by minor wall-rock assimilation.We propose that the strontianite-rich carbonatite formed from a highly evolved,Sr-and REEs-rich carbonatitic magma that intruded into shallow structural breccias,followed by rapid cooling.Its formation is associated with a continuous melt-fluid evolutionary process that is characteristic of carbonatitic systems.展开更多
Liberation. as an attribute of mineralogy characteristic. whose impacts on finely disseminated Canadian rare earth ore was studied with microwave pretreatment. Samples of a light rare earth ore along with mostly anker...Liberation. as an attribute of mineralogy characteristic. whose impacts on finely disseminated Canadian rare earth ore was studied with microwave pretreatment. Samples of a light rare earth ore along with mostly ankerite and biotite as dominant gangue minerals as well as bastnaesite, strontianite and goethite as dominated minerals were exposed to further comminution by ball mill and microwave pretreatment fragmentation. Mineralogical characteristics were analyzed by using a mineral liberation analyzer（MLA）.The results indicated that tight association mutually penetrates among dominated minerals in the range size of -300 ＋ 212 μm and 212 ＋ 150 μm and gangue minerals in the form of adjacent type. fine vein type. shell type and packing type. Temperature in the ore samples pre-treated by microwave can rapidly rise to 250 ℃ with microwave power of 0-1.5 kW and microwave time of 0-2 min. Applying the microwave pretreatment merely reduces the hardness of the ore causing the fracture of rare earth ore, but this does not transform or change the original mineralogy characteristics of the ore samples. On the basis of above study. the liberation value of bastnaesite, strontianite and goethite with microwave pretreatment is greater than with conventional comminution when the liberation class is above 75%. The distribution of particle size of rare earth ore samples is better with microwave pretreatment than with conventional comminution for particle size of 7.4 × 10^（-5） m. With microwave pretreatment, the theoretical grade-recovery of bastnaesite. strontianite and goethite in the rare earth ore attains better results than with conventional comminution at a given grade.展开更多
基金the National Natural Science Foundation of China(Grant No.42203073 and 41472072)Basic Scientific Research Fund of the Institute of Geology,CAGS(Grant No.J2317)Sichuan Science and Technology Program(Grant No.2023NSFSC0272).
文摘Strontianite-rich carbonatite,containing over 30 vol%carbonate minerals predominantly composed of strontianite(SrCO3),is identified in the Zhengjialiangzi ore segment of the Muluozhai rare earth element(REE)deposit,western Sichuan Province,China.It exhibits a unique mineral assemblage dominated by strontianite,fluorite,bastnäsite,barite,calcite and dolomite,distinguishing it from conventional calcio-,magnesio-,ferro-,or natro-carbonatites.The rock shows extreme enrichment in REEs(ΣREE=47335-64367 ppm),with strong LREE/HREE fractionation[(La/Yb)N=1151-2119]and notably high concentrations of high-value critical REEs(e.g.,Pr,Nd,Tb,Dy),5-10 times greater than those in local calcite-dominated carbonatites.Trace element patterns indicate significant enrichment in REEs,Sr,and Ba,along with depletion in high-field-strength elements(HFSEs;e.g.,Nb,Ta,Zr,Hf).In-situ Sr isotopes of strontianite[(^(87)Sr/^(86)Sr)i=0.706190-0.707305]indicate an enriched mantle source(EMI-EMII).Sr enrichment is attributed to initial mantle source enrichment and extensive fractional crystallization,possibly accompanied by minor wall-rock assimilation.We propose that the strontianite-rich carbonatite formed from a highly evolved,Sr-and REEs-rich carbonatitic magma that intruded into shallow structural breccias,followed by rapid cooling.Its formation is associated with a continuous melt-fluid evolutionary process that is characteristic of carbonatitic systems.
基金Project supported by the National Natural Science Foundation of China(41472071)
文摘Liberation. as an attribute of mineralogy characteristic. whose impacts on finely disseminated Canadian rare earth ore was studied with microwave pretreatment. Samples of a light rare earth ore along with mostly ankerite and biotite as dominant gangue minerals as well as bastnaesite, strontianite and goethite as dominated minerals were exposed to further comminution by ball mill and microwave pretreatment fragmentation. Mineralogical characteristics were analyzed by using a mineral liberation analyzer（MLA）.The results indicated that tight association mutually penetrates among dominated minerals in the range size of -300 ＋ 212 μm and 212 ＋ 150 μm and gangue minerals in the form of adjacent type. fine vein type. shell type and packing type. Temperature in the ore samples pre-treated by microwave can rapidly rise to 250 ℃ with microwave power of 0-1.5 kW and microwave time of 0-2 min. Applying the microwave pretreatment merely reduces the hardness of the ore causing the fracture of rare earth ore, but this does not transform or change the original mineralogy characteristics of the ore samples. On the basis of above study. the liberation value of bastnaesite, strontianite and goethite with microwave pretreatment is greater than with conventional comminution when the liberation class is above 75%. The distribution of particle size of rare earth ore samples is better with microwave pretreatment than with conventional comminution for particle size of 7.4 × 10^（-5） m. With microwave pretreatment, the theoretical grade-recovery of bastnaesite. strontianite and goethite in the rare earth ore attains better results than with conventional comminution at a given grade.
