基于工业CT的青海察尔汗盐湖固体钾矿孔隙度与给水度研究

Study on Porosity and Specific Yield of Qarhan Salt Lake Solid Potassium Mine in Qinghai Province Based on Industrial CT

钾盐是我国战略性关键矿产资源,察尔汗盐湖是我国最大钾盐生产基地,钾盐原料主要来自固体钾矿的固液转化,而孔隙度、给水度是固体钾矿固液转化评价的关键指标。本研究首次利用工业CT技术获得察尔汗盐湖固体钾矿准确的孔隙度和给水度,并结合前人资料,对其动态变化及原因进行了初步研究。主要结论如下:(1)工业CT可高效、直观、非破坏性地测量固体钾矿的孔隙度和给水度。(2)察尔汗盐湖固体钾矿孔隙度均值为16.49%,给水度均值为10.21%。孔隙度由第一层向第三层逐渐减小,第四层稍有回升但仍呈减小趋势;给水度的平均值也由第一层向第四层逐渐减小。在特定采区,孔隙度和给水度的最大值和最小值位于不同孔深处,主要是岩性的不均一性引起。(3)别勒滩矿区的孔隙度(17.12%)较2007年的孔隙度(20.64%)减小,而给水度(10.58%)较2007年的给水度(9.56%)增大,表明地层持水度降低,储藏卤水能力减弱,这可能与干旱气候及固液转化有关。本研究可为察尔汗固体钾矿资源承载力评价提供科学依据,更为地质条件类似的盐类矿床评价提供可借鉴的方法和思路。

Potash is a strategic key mineral resource in China,and the Qarhan Salt Lake is the largest potash production base in the country.Potash raw materials are mainly from the solid-liquid transformation of solid potash ore.Porosity and specific yield are the key indicators for evaluating of the solid-liquid transformation of potash in Qarhan Salt Lake.In this study,accurate porosity and specific yield values of Qarhan Salt Lake solid potassium deposit were obtained for the first time by using by industrial CT technology,and the dynamic characteristics and causes of the results were preliminarily studied.The main conclusions of the study are as follows:(1)Industrial CT can efficiently,intuitively,and nondestructively measure the porosity and specific yield of solid potassium ore.(2)The average porosity of the Qarhan Salt Lake solid potassium deposit is 16.49%,and the average specific yield is 10.21%.The porosity decreases gradually from the first layer to the third layer.It rises slightly in the fourth layer but still shows a decreasing trend.The average value of specific yield also decreases gradually from the first layer to the fourth layer.In a specific mining area,the maximum and minimum values of porosity and specific yield are located at different hole depths,which are mainly caused by the heterogeneity of lithology.(3)The porosity(17.12%)in the Bieletan area is lower than it was in 2007(20.64%),whereas the specific yield(10.58%)is higher than it was in 2007(9.56%),indicating that the formation specific holding capacity was reduced and the brine storage capacity weakened,which may be related to the arid climate conditions and solid-liquid transformation.This study provides a scientific basis for evaluating the carrying capacity of the Qarhan solid potassium mine resources and a reference method and idea for the evaluation of salt deposits with similar geological conditions.