应用能谱扫描电镜与X射线衍射等分析技术研究西藏扎西康铅锌矿中伴生元素锰的赋存状态

西藏扎西康铅锌多金属矿床是我国首次发现的喷流沉积-热泉水改造型锰铁锑铅锌银矿床,已有研究表明矿床中除了铅锌矿还伴生有银、锑、铜、硫、锰、砷等多种元素。本文在化学多元素分析和光学显微镜镜下鉴定的基础上,结合能谱扫描电子显微镜和X射线衍射分析等手段对扎西康铅锌矿中伴生组分Mn的含量、矿物种类、嵌布和包裹等特性进行了研究。分析结果表明,原生矿石的主要成矿元素Pb和Zn的含量分别为6.00%和4.00%,伴生元素Mn的含量平均达到4.36%;原生矿石中的主要矿物为方铅矿、闪锌矿,其次为黄铁矿、毒砂和菱锰矿等。原生矿石中伴生元素Mn主要以独立的菱锰矿和铁菱锰矿形式存在,与闪锌矿和方铅矿密切共生,是成矿早期重要的载矿矿物,嵌布在石英、黄铁矿、闪锌矿和毒砂的粒间、边部及空隙间,其次以类质同象形式赋存于菱铁矿和菱锌矿中。进一步对扎西康铅锌矿选冶产物中的伴生元素Mn的含量和赋存状态进行研究,研究表明Mn具有较高的综合利用价值,在原生矿石、铅精矿、锌精矿和尾矿中的质量分数分别为4.36%、0.51%、0.95%和5.36%,显示Mn很少一部分进入铅精矿和锌精矿,而绝大部分进入尾矿;Mn在尾矿中仍主要以菱锰矿形式存在,存在形式与原生矿石相比未发生改变,可通过强磁选工艺从铅锌尾矿中综合回收利用Mn。

Occurrence of Manganese in the Zhaxikang Lead-Zinc Deposit from Tibet Investigated by Energy Scanning Electron Microscope and X-ray Diffraction Methods

The Zhaxikang Pb-Zn polymetallic ore deposit, the first SEDEX-modified by hot spring type Mn-Fe-Sb-Pb-Zn-Ag deposit discovered in China, is associated with Pb, Zn, Ag, Sb, Cu, S, Mn, As and other elements. The concentration, mineral species, dissemination and inclusion of Mn in the Zhaxikang Pb-Zn deposit were studied by chemical analysis and examination using Petrographic Microscope, Scanning Electron Microscope and X-ray Diffractometry. The analysis showed that the content of ore-forming elements Pb and Zn were 6% and 4%, and the content of the associated component Mn was 4.36%. The main mineral compositions of the Zhaxikang Pb-Zn polymetallic ore deposit are galena, sphalerite, pyrite, arsenopyrite and rhodochrosite. The useful composition of manganese minerals in the mine mostly occurs as rhodochrosite and iron rhodochrosite, which closely associated with sphalerite and galena, an important carrier of mineralization stage, inlay on the edge, intergranular and gap between quartz, pyrite, sphalerite and arsenopyrite. The others occur in siderite and smithsonite with isomorphism forms. The content and occurrence of Mn in Zhaxikang Pb-Zn ore metallurgical produts were analysised, which shows that the comprehensive utilization of Mn is of high value. The mass fraction of Mn in the lead ore, lead concentrate, zinc concentrate and tailings was 4.36%, 0.51%, 0.95% and 5.36%, respectively, indicating that little Mn enters into lead concentrate and zinc concentrate, but mostly in tailings. Mn is mainly in rhodochrosite form in lead-zinc tailings, which can be comprehensively recovered and utilized by a high intensity magnetic separation process.