Characteristics Of Coal Slime And Improvement Effect On Sandy Soil

The clean and efficient use of coal action plan(2005-2020)calls for a 70%washing rate of raw coal,which means more slime will be produced.According to statistics,nearly 300 million tons of coal slime were produced in 2017,of which nearly 140 million tons were piled in an open and extensive way,causing serious environmental problems.In addition,both desertification and aeolian sandy soil use processes need to improve their bad characters.The characteristics of high clay powder content and strong water-holding capacity of coal slime are complementary to the disadvantages of poor grain composition of sand and easy loss of water.Therefore,with the utilization of coal slime and the improvement of sandy soil as the goal,the characteristics of coal slime and the improvement effect of sandy soil were studied.The effects of coal slime on the physical,chemical and biological properties of sandy soil were studied by the no-plant culture experiment with different coal slime contents.The main test results are as follows:1.Coal slime has a neutral pH value,with clay and powder particles as high as 73.43%,high content of organic carbon and nutrients,and almost all medium and trace elements necessary for plants,meeting the basic characteristics of improved alkaline sandy soil;The content of heavy metal in coal slime is low,which meets the improved national standard and is safe.2.Coal slime has an impact on the physical properties of sandy soil.The grain composition of sandy soil was optimized and the contents of clay(d<2 ? m)and silt(2?50?m)were increased by 0.21%?5.88%and 2.30%?47.22%,respectively.The range of soil available water content was 2.29%?10.48%.3.Coal slime has an impact on the chemical properties of sandy soil,reducing the soil pH by 0.07?0.57 units;The increase of soil organic carbon,electrical conductivity and alkaline nitrogen were 123%?927%,13%?182%and 10.6%?49.1%,respectively.In addition,the changes of pH,conductivity and organic carbon were correlated with the addition of coal slime.4.Coal slime has an effect on the biological properties of sandy soil.In the early stage of culture,it has a significant inhibitory effect on catalase;in the middle and late stage,the inhibitory effect gradually weakens.The microbial diversity was promoted and then inhibited.In conclusion,coal slime has the basic characteristics of improving sandy soil and is safe.Adding coal slime can improve the physical,chemical and biological properties of sandy soil.