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柴达木盆地西部大浪滩梁中矿区是一个以液体钾矿为主、固液并存的大型钾镁盐矿田。通过对梁中矿区大浪滩凹地钾镁盐矿点实地考察,以兴元钾肥厂开挖的固体钾盐(软钾镁矾、钾石盐和杂卤石等矿物)剖面为研究载体,采集73件固体盐样。通过XRD矿物组成分析,发现梁中凹地盐类呈石盐+泻利盐—石盐+泻利盐+软钾镁矾—石盐+泻利盐+钾石盐—石盐+钾石盐+光卤石—石盐+水氯镁石矿物组合变化。其中,在Ⅱ阶段(5.3~2.6 m)沉积了层状的固体钾盐矿物(包含软钾镁矾、钾石盐和光卤石)。地层中沉积的软钾镁矾,结晶良好。通过对比分析认为,软钾镁矾的形成条件:1)外来水体的混入,溶滤了地表盐滩中可溶性钾;2)(全新世)相对较高的温度条件,芒硝等矿物的溶解,会使湖表卤水中硫酸盐含量明显增加,卤水组成点易落在25℃介稳相图的白钠镁矾相区,有利于软钾镁矾结晶析出;3)干旱的气候条件。
Daxiongtanliangzhong Mining Area in western Qaidam Basin is a large-scale potassium-magnesium salt orefield mainly composed of liquid potassium ore and solid-liquid coexist. Through the field investigation of the Kali Magnesium salt deposit in Dalangtan depression in Liangzhong Mining Area, the section of solid potassium salt (minerals such as soft arsine, potash salt and polyhalite) excavated in Xingyuan Potash Factory was used as the research carrier, and 73 Solid salt sample. According to the analysis of XRD mineral composition, it is found that the salt in Liangzhonglian is in the form of rock salt + diarrhea salt - stone salt + diarrhea salt + soft magaziite - stone salt + diarrhea salt + potassium stone salt - stone salt + Carnallite - rock salt + bischofite mineral combination change. Among them, the lamellar solid potassium salt minerals (including the soft alum, potassium salt and carnallite) were deposited in the stage II (5.3 ~ 2.6 m). Stratum deposition of soft magnesia, good crystallization. The comparative analysis shows that the formation conditions of soft muscovite are as follows: (1) The mixing of alien water and the leaching of soluble potassium in the surface salt beach; (2) the relatively higher temperature conditions (Holocene), the dissolution of thenardite and other minerals So that the sulfate content in the lake table brine increased obviously. The composition point of brine is easy to fall in the white sodium magnesium alum phase region of the metastable phase diagram at 25 ℃, which is favorable for the crystallization of soft magasia; 3) The arid climatic conditions.