钾盐资源全球分布和我国找钾实践及方法探究

世界各国大型古代海相固体钾盐矿床多数是在石油、盐岩矿、盐泉卤水等资源的勘查过程中被发现的。国内几十年的找钾实践证实,我国缺乏大型海相固体钾盐矿床,近年来在新生代陆相沉积盆地中寻找大型固体钾盐矿床的努力也没有取得明显进展。我国已探明的钾盐储量主要分布在青海柴达木盆地和新疆罗布泊的11个盐湖及其晶间卤水中,约占资源总量的90%以上;以固体钾矿赋存的资源量少且品位不高,仅占己知总量的2.6%。从1958年察尔汗盐滩生产出第一批953吨钾肥填补我国钾肥生产的空白,到年产150万吨KCl的卤水钾盐开发规模的形成;从1995年在罗布泊发现大型卤水钾矿,到2008年预期生产120万吨K2SO4,显示了我国干旱区盐湖卤水钾盐资源的重要位置。有专家建议,今后的工作应在深入研究成盐盆地基底构造和岩相古地理的基础上,进一步划分可能成钾的次级盆地并进行重点勘探和研究。借鉴世界各国找钾经验,将地质观察分析、地球物理探测、地球化学与水化学等方法综合运用,我国的探盐找钾工作有可能取得突破性进展。

A Review on the Exploration of Global Potash Resources with an Emphasis on the Past and Present Status of China with a Methodological Perspective

Major potash-ore resources of the world were discovered primary in the exploration of other resources such as petroleum,ancient evaporate deposits and underground brines.They were predominantly reserved in oceanic sedimentary basins of the globe.In China,however,potash deposits extensively developed in ancient oceanic basins are essentially deficient,as suggested by the survey of potash resources in the past several decades.There has been no substantial progress either made to explore potash ores from China's large continental basins of Cenozonic Era.The sylvite reserves of China,therefore,largely relies on potash-bearing brines reserved in about 11salt lakes and/or playa lakes from Qaidam Basin,Qinghai Province,and Lop Nor,Xinjiang,which accounts for>90% of the known total reserves.The ancient potash-ore resources of China by far accounts only for 2.6% of the known total and the ore grade usually is low.The production of the first batch of 935-ton potassium fertilizer was started in 1958 from the Qarhan playa,Qaidam Basin,which filled blank on manufacturing potassium fertilizer in China.The out put of the manufacturing production there increased dramatically and in 2006 reached 1.5 million-ton KCl per year.The exploration of the potassium-bearing brine in the Lop Nor Playa Lakes has been carried out since 1995 and it is anticipated that an annual manufacturing production of 1.2 million-ton K2SO4 would be accompanied by the end of 2008.Emphasis regarding future investigations of ancient potash resources should be placed on distinguishing sub-basins favorable for potash deposition from large evaporite basins in China.Based on the results and experience derived from potash search in the world,methodological improvement for the exploration is considered to be important.Further exploration in this way may help to achieve the goal targeted several decades ago.