Hydrochemical And Hydroregime Study Of Trata S₄ Inter-Crystal Brine In Bieletan Section, Qarhan Salt Lake

The Qarhan Salt Lake in Qinghai Province is a large-scale comprehensive salt evaporite deposits, which is also the largest potash production enterprise in China. After the Salt Lake Group Company has invested in the developing of the lake, especially the start of the "Megaton Project", large quantities of inter-crystal brine (Strta S4) are pumped out as raw material annually. Accordingly, it is extremely to monitor the hydrochemical and hydroregime variations during the drawing brines.Ever since the research in 1980's on the hydrochemistry and hydroregime in Qarhan 's first mining area, systematical research in Bieletan section is insufficient than in the Qarhan Section.The effect of drawing brines in a large scale becomes obvious as the production continues. content change of various ions in the inter-crystal brine takes place and the ground water level descends continuously. It is significant to investigate the variation laws of hydrochemistry and hydroregime during the pumping brine from the Qarhan Salt Lake.Based on the drilling holes, observations, sampling,and analysis of the samples in lab during 3 year, the research results on the hydrochemistry and hydroregime in the Bieletan show as the following:1. There are certain areas that are rich in boron and lithium in Bieletan Setion. Areas rich in boron are close to b-1 hole, areas rich in lithium are located close to b-02 and b-03. There is a fine positive correlation between born and lithium. The contents of both ions will increase as the mineralization of the brine increases. The central area that rich in boron and lithium vary as seasons and the ground water level change.2. There is a positive correlation relationship between concentration of Mg2+ and salinity, Li+, Boron, this is because Mg2+ enrichment by the vaporization of brines. The central area that rich in Mg2+ are close to b-8,b-9,b-13, which are near to area rich in Cl-. The ground water level influences the location of area rich in Mg2+ and the area disappear almost due to influence by dilution during the high level period in September.3. There is a negative correlation relationship between concentration of SO42- and Cl-. Area rich in Cl- is close to b-03,b-13, which is also the area that has a low content of SO42-. The brines in this area supplied by the deep ground brines in northern part of Qarhan are the chloride type. Area rich in SO42- is near to the northern part of Senie salt lake, which is also the area that has a low content of Cl- and may be supplied by brines from the lake. The concentration of Ca2+ and Cl- correlates positively, and their horizontal distribution is almost the same .4. Content of K+ decreases as the brine pump keeps on, the speed of brine supplying can not catch up with the pump speed of the brine. A huge ground waterfunnel in Bieletan Section forms along with the descending of the ground water level.5 The ground brine level descend periodically in certain way. The level remains the same during high level period from June to September, and the level in certain area may rise. In general, the groundwater level of brine falls though in an undulating ground. The average annual descending value calculated from observation is in a well match with the actual result. The descending speed may speed up as the starting of the second Megaton Project of the Salt Lake Group Company.6 The brine collecting trench has very important factor on the brine flowing direction only in certain area , while it will have no influence beyond its range.