{"title":"Apatite-rich zones in the Uppermost Upper Zone, Northern Limb, Bushveld Complex: Possible non-conventional source of REE and TiO2","authors":"Hakundwi Mandende , Themba Mothupi","doi":"10.1016/j.gexplo.2024.107498","DOIUrl":null,"url":null,"abstract":"<div><p>The uppermost Upper Zone of the Bushveld Complex is known as a potential host of significant apatite-ilmenite resources. Recent exploration studies have delineated two apatite-rich zones representing a huge potential resource of phosphate. A detailed mineralogical and geochemical study of the two apatite-rich zones is undertaken to demonstrate that in addition to phosphate, apatite and ilmenite could be important saleable by-products for REE and Ti. In the Lower Apatite Zone (LAZ), the average concentrations of apatite, ilmenite, and titano-magnetite are 11%, 6%, and 18%, respectively. Grades of about 30 wt% combined apatite, ilmenite, and titano-magnetite can be recovered from the Upper Apatite Zone (UAZ), of which apatite and granular ilmenite constitute 9 and 10%, respectively. There is an association between diamagnetic (apatite), paramagnetic (mostly silicates and ilmenite), ferromagnetic (titano-magnetite) minerals and, to a lesser extent, sulphides. In addition, the majority of the targeted minerals; apatite, ilmenite, and titano-magnetite are relatively coarse, with a median value ranging between 270 μm and 931 μm. In-situ trace element data obtained on apatite demonstrate an increase in Light Rare Earth Elements (LREE) stratigraphically, grading from an average of 3180 ppm Total Rare Earth Elements (TREE+Y) in the LAZ to an average of 4068 ppm TREE+Y in the UAZ, indicating a sub-economic potential of REE that may be economically viable as by-product to phosphate. Preliminary resource estimations show that ~1,405,560 t and ~1,798,056 t of TREE can be exploited from the LAZ and UAZ, respectively. The discrete ilmenite grains are an attractive additional by-product considering their higher average >50% TiO<sub>2</sub> and lower concentration of impurities such as <1.06% MgO, <1.21% MnO, <0.08% Al<sub>2</sub>O<sub>3</sub>, <0.02% V<sub>2</sub>O<sub>5</sub> and <0.01% Cr<sub>2</sub>O<sub>3</sub>. These results suggest that apatite-rich layers in mafic layered intrusions are viable prospects for economic extraction of REE in conjunction with titanium as other by-products that can be recovered from phosphate rocks.</p></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"263 ","pages":"Article 107498"},"PeriodicalIF":3.4000,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geochemical Exploration","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0375674224001146","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
The uppermost Upper Zone of the Bushveld Complex is known as a potential host of significant apatite-ilmenite resources. Recent exploration studies have delineated two apatite-rich zones representing a huge potential resource of phosphate. A detailed mineralogical and geochemical study of the two apatite-rich zones is undertaken to demonstrate that in addition to phosphate, apatite and ilmenite could be important saleable by-products for REE and Ti. In the Lower Apatite Zone (LAZ), the average concentrations of apatite, ilmenite, and titano-magnetite are 11%, 6%, and 18%, respectively. Grades of about 30 wt% combined apatite, ilmenite, and titano-magnetite can be recovered from the Upper Apatite Zone (UAZ), of which apatite and granular ilmenite constitute 9 and 10%, respectively. There is an association between diamagnetic (apatite), paramagnetic (mostly silicates and ilmenite), ferromagnetic (titano-magnetite) minerals and, to a lesser extent, sulphides. In addition, the majority of the targeted minerals; apatite, ilmenite, and titano-magnetite are relatively coarse, with a median value ranging between 270 μm and 931 μm. In-situ trace element data obtained on apatite demonstrate an increase in Light Rare Earth Elements (LREE) stratigraphically, grading from an average of 3180 ppm Total Rare Earth Elements (TREE+Y) in the LAZ to an average of 4068 ppm TREE+Y in the UAZ, indicating a sub-economic potential of REE that may be economically viable as by-product to phosphate. Preliminary resource estimations show that ~1,405,560 t and ~1,798,056 t of TREE can be exploited from the LAZ and UAZ, respectively. The discrete ilmenite grains are an attractive additional by-product considering their higher average >50% TiO2 and lower concentration of impurities such as <1.06% MgO, <1.21% MnO, <0.08% Al2O3, <0.02% V2O5 and <0.01% Cr2O3. These results suggest that apatite-rich layers in mafic layered intrusions are viable prospects for economic extraction of REE in conjunction with titanium as other by-products that can be recovered from phosphate rocks.
期刊介绍:
Journal of Geochemical Exploration is mostly dedicated to publication of original studies in exploration and environmental geochemistry and related topics.
Contributions considered of prevalent interest for the journal include researches based on the application of innovative methods to:
define the genesis and the evolution of mineral deposits including transfer of elements in large-scale mineralized areas.
analyze complex systems at the boundaries between bio-geochemistry, metal transport and mineral accumulation.
evaluate effects of historical mining activities on the surface environment.
trace pollutant sources and define their fate and transport models in the near-surface and surface environments involving solid, fluid and aerial matrices.
assess and quantify natural and technogenic radioactivity in the environment.
determine geochemical anomalies and set baseline reference values using compositional data analysis, multivariate statistics and geo-spatial analysis.
assess the impacts of anthropogenic contamination on ecosystems and human health at local and regional scale to prioritize and classify risks through deterministic and stochastic approaches.
Papers dedicated to the presentation of newly developed methods in analytical geochemistry to be applied in the field or in laboratory are also within the topics of interest for the journal.