The Occurrence Characteristics of Nickel and Molybdenum in Sedimentary Exhalative Polymetallic Deposit
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摘要: 喷流沉积型矿床是矿床地质学研究的前沿课题，查明矿石中重要组分(镍和钼)的赋存状态是该类矿床地质学研究的重要内容。湘黔地区天鹅山—黄家湾、大坪—大浒镍钼矿带是典型的海底喷流沉积矿床，本文采集该矿区的样品，应用化学和光谱定量分析、偏光显微镜和X射线衍射、扫描电镜、电子探针等大型现代仪器相结合的分析手段，研究了矿石中镍和钼的赋存状态。化学和光谱分析确定矿石中镍含量为3.76％，钼含量为4.99％；偏光显微镜下观察发现金属矿物零星分布，颗粒细小，结晶程度差，光学特征极不明显，晶体形貌特征难以观察，初步推断矿石矿物以胶状形式存在，但在光学显微镜下很难为这些矿物定名和描述；X射线衍射分析验证了偏光显微镜鉴定结果，印证了样品中存在很多非晶质矿物，仅有钨钼钙矿和镍黄铁矿两种矿物含有镍钼，且矿物含量很低(分别为0.4%和0.8%)，对比化学分析结果，可推断样品还存在其他富含镍钼元素的矿物。进一步对富集镍钼元素的区域进行电子探针分析，最终确定了镍除了赋存于辉砷镍矿、方硫镍矿中，在胶状黄铁矿和磁黄铁矿边缘呈蠕虫状花边的镍黄铁矿中也有富集；钼主要赋存于碳硫钼矿中。矿石中的镍钼主要赋存于由胶态向结晶态过渡的金属矿物中，研究成果为该类矿床的矿石矿物学研究、选矿、冶炼及矿石综合利用提供重要的信息和依据。
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关键词:
- 喷流沉积型多金属矿床 /
- 镍钼赋存状态 /
- 电子探针 /
- 线扫描分析 /
- 面扫描分析
Abstract: Exhalative sedimentary polymetallic deposit is an attractive subject in the study of mineral deposit geology. Ascertaining the occurrence state of main ore components (nickel, molybdenum) is the important study focus for this kind of mineral deposit. The Swan Hill-Huangjiawan and Daping-Dahu nickel molybdenum ore belts of Xiang-Qian area are typical submarine exhalative sedimentary deposits. In this article, an account of samples that were collected from the ore district, and analyzed using large modern instruments including those for chemical and spectral analysis, Optical Microscope and X-ray Diffraction, Scanning Electron Microscope and Electron Probe is given, to study the occurrence states of nickel and molybdenum in the ores. The content of nickel was 3.76%, and the content of molybdenum was 4.99% using chemical and spectral analysis. Observations were made of the metal minerals in the polished section, which were distributed sporadically and occurred as fine particles. Since there is weak crystalline degree, low reflectivity and unclear crystal morphology under the polarizing microscope, it was preliminary inferred that the ore mineral existed in colloidal form, but it is difficult to name and describe these ore minerals. The X-ray Diffraction analysis results for the samples supported the observation under the Polarizing Microscope, which confirmed that there were many amorphous minerals hosted in the analyzed samples. The nickel and molybdenum occurred mainly in the tungsten-powellite and pyrrhotite with low contents of 0.4% and 0.8%, respectively. Comparing with the results of chemical analysis, it is hinted that there are other minerals which enrich nickel and molybdenum. Further analysis by electron microprobe in the nickel molybdenum enriched area indicate that nickel not only occurs in gersdorffite and vaesite, but is also concentrated in the edge of colloidal pyrite and pyrrhotite within a worm-like lace. Molybdenum mainly occurred in the carbon sulphur molybdenum ore. The nickel and molybdenum mainly occurred in the transition ore minerals from colloidal to crystalline. The research results provided important information and the basis for the study of ore mineralogy, mineral processing, smelting and comprehensive utilization of the mineral ores for this kind of deposit. -
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表 1 样品中主次量元素分析
Table 1. Analytical results of major and minor elements in samples
测试元素 化学定量分析wB/% 测试元素 光谱半定量分析wB/(μg·g-1) S 21.90 As 9706 TFe 19.64 Sr 302 SiO2 15.70 Ba 245 CaO 10.80 V 211 P2O5 5.13 Y 190 Mo 4.99 Cr 164 Ni 3.76 Co 70.5 MgO 3.18 Nb 48.1 Al2O3 2.44 Zr 31.3 
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表 2 电子探针定量分析结果和矿物定名
Table 2. EPMA quantitative analysis results and mineral naming
样品编号 基本特征 wB/% 矿物名称 Ni Mo Fe S As 1 隐晶质条带上端富含镍砷硫元素的条带 34.833 0.417 1.389 21.436 42.672 辉砷镍矿 2 隐晶质条带下端富含镍砷硫元素的条带 33.439 0.535 1.496 21.484 43.423 辉砷镍矿 3 同心圆状矿物外环 32.674 0.647 1.007 20.773 44.684 辉砷镍矿 4 圆粒状矿物间裂隙 32.354 0.409 1.014 19.624 47.432 辉砷镍矿 5 富含镍、硫和少量铁元素的条带 43.865 1.096 3.601 49.342 0.677 方硫镍矿 6 同心圆状矿物内部圆粒状矿物 0.404 1.008 44.420 51.572 1.798 粒状黄铁矿 7 胶状形态圆粒状矿物 6.507 0.590 26.312 61.815 0.432 胶状黄铁矿 8 富含钼、硫元素的灰色隐晶质条带 2.326 30.625 2.948 24.928 1.400 碳硫钼矿 9 磁黄铁矿边缘花边状矿物 34.646 0.503 32.087 33.294 0.315 镍黄铁矿
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