摘要
微米级磁性矿物在黄土-古土壤序列中含量不足1%,为了满足多种测试的需要,要尽可能地富集磁性矿物。介绍一种富集方法,即程序地采用浸泡-搅拌(转速为5900r/min)-湿法磁选(磁场梯度范围为0.8～2.5T)-重液分选(d≥2.5)-干法磁选(激磁电流在1～2A之间)的方法,从西峰和段家坡第五层古土壤(分别简称为XS和DS)的上浮物和沉砂中富集出6个不同磁性的矿物组分。经磁化率(MS-2)、磁滞回线(MICROMag2900)测定、高倍显微镜(MPV-3)及扫描电镜(S-3500N)观测,矿物的分散度与磁性分选良好,精选的强磁性组分(XS-4J和DS-4J)中磁性矿物含量约占该组分的30%,富集的磁性矿物种类多,包括含铁粘土、碎屑状磁性矿物和自生磁性矿物,磁选出的矿物代表性强并能满足多项分析测试的需要。湿法磁选(程序3)是流程中操作最复杂的一步,根据XS样的实测结果,这一步磁选的回收率为87.2%。
Micron grade magnetic minerals are less than 1%of total minerals in the loess paleosol sequences. To satisfy requirements of a lot of kind of measurement, it needs to enrich the magnetic minerals. An enrichment method isintroduced, that is step by step to dip stir (5900 r/min) wet magnetic separation (magnetic field gradient: 0.8～2.5 T) heavy liquid separation (d ≥2.5) dry magnetic separation (excitation electric current: 1～2 A). Six different magnetic components have been separated, respectively from two samples, which is from the fifth paleosol in Xifen section and Duanjiapo section (XS5 1 andDS5 1, or XS and DS). Susceptibility and magnetic hysteresis have been measured for separated products (magnetic components No.1～5) by Bartington MS 2 and MICRO Mag 2900, and the magnetic component No.4 is observed by microscope (MPV 3) or SEM (S 3500N). The results show that the magnetism sorting and dispersion of magnetic mineral particles are good. The magnetic mineral is about 30%in the well separated magnetic components, with an increase of magnetic mineral about 2 grade by this method. The enriched magnetic minerals include Fe bearing clay, clastic magnetic minerals and authigenic magnetic minerals. The separated products are well representative and can satisfied requirements of a lot ofkind of research. Wet magnetic separation is the most complex step. The rate ofrecovery in the step is 87%based on actual measured data.
出处
《地球化学》
CAS
CSCD
北大核心
2003年第1期97-101,共5页
Geochimica
基金
国家自然科学基金(40073029)
