印尼典型海砂矿的工艺矿物学及固态还原特性

Mineralogy and solid-state reduction features of typical ironsands from Indonesia

  • 摘要: 以经典工艺矿物学研究方法为基础,结合化学物相分析、矿物解离分析(MLA)、X射线衍射、光学显微镜、扫描电镜-X射线能谱仪(SEM-EDS)等手段对印尼典型海砂矿的矿物学及其固态还原特征进行了系统研究。结果表明:印尼海砂矿的矿物组成主要为钛磁铁矿、次为少量假象赤铁矿、赤铁矿、钛铁矿以及辉石等。绝大部分钛磁铁矿呈致密单体或铁的富连生体产出,偶有由固熔体分离析出形成的微细钛铁矿片晶。赋存于钛磁铁矿中的铁占总铁的89.79%、钛为85.42%、钒则高达97.97%。海砂矿在C/Fe摩尔比1.2、温度1300 ℃条件下还原60 min可较好实现金属化。其还原历程遵循:Fe2.75Ti0.25O4 → FeTiO3, (Fe, Mg)Ti2O5 → (Fe, Mg)Ti2O5 → Fe,稳定的黑钛石相是影响金属化程度的主要因素。经固态还原处理Fe元素最终富集于金属相,V、Ti则赋存于渣中富钛相,为后续的分离提取创造了有利条件。

     

    Abstract: With over 100 billion tons of reserves, the ironsands resource is mainly distributed along the “Belt and Road” countries, such as Indonesia. It is the second largest marine resource inferior to petroleum and natural gas. Ironsands mainly comprise vanadium, titanium, and iron. With advantages of easy mining, low cost, and abundance in polymetallic minerals, the ironsands resource has attracted extensive attention for its extremely high comprehensive recycling value. According to previous studies, solid-state reduction is an efficient approach to a number of processes in complex mineral resources such as ironsands, especially in vanadium-bearing titanomagnetite treatments. In this paper, the process mineralogy and direct reduction characteristics of typical ironsands from Indonesia were studied based on the classical mineralogy method combined with various characterization techniques such as chemical phase analysis, MLA, X-ray diffraction, particle size analysis, optical microscopy, and SEM-EDS. Results show that the mineral composition of the ironsands is mainly titanomagnetite, followed by a small amount of pseudo-hematite, hematite, ilmenite, pyroxene, plagioclase, and others. Most titanomagnetites exist as compact monomers or iron-rich aggregates with occasional fine ilmenite flakes formed through solid-melt separation. The iron contained in titanomagnetite phase accounts for 89.79% of the total iron in the ironsands, while titanium and vanadium account for 85.42% of the total titanium and 97.97% of the total vanadium content, respectively. Ironsands can achieve high metallization ratio when they are reduced at 1300 ℃ for 60 min with C/Fe mole ration of 1.2. The reduction course is as follows: Fe2.75Ti0.25O4 → FeTiO3, (Fe, Mg)Ti2O5 → (Fe, Mg)Ti2O5 → Fe. Results reveal that the stable anosovite ((Fe, Mg)Ti2O5) phase is the main factor affecting the final metallization degree of the reduced samples. With solid state reduction treatment, iron is enriched in the metal phase while vanadium and titanium elements are distributed in the titanium-rich phase in the slag. These create favorable conditions for the subsequent separation and extraction process, which consequently lay a firm foundation for the comprehensive utilization of the ironsands.

     

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