Comprehensive evaluation of rock and soil quality of different geological stratum groups in Pingshuo opencast coal mine reclamation area

In order to make scientific and rational use of waste rock and soil in mining areas, guide its classification and discard and reconstruct high quality reclaimed soil, the loess parent material in the Pingshuo opencast mining area is used as a control to analyze the differences in physical and chemical properties of different types of rock and soil layers, and the source control of land reclamation is conducted from the source of the reclaimed soil parent material. It may provide a basis for land reclamation and ecological restoration in opencast coal mines. Combining the analysis results of the single nutrient content and beneficial trace element content, with the help of the modified Nemero comprehensive index method, the fertility quality of each rock and soil layer is comprehensively evaluated. With the single factor quality index method, the environmental quality of each rock and soil layer is also evaluated. The comprehensive fertility coefficient of each rock and soil layer is in the range of 0.40 to 1.26, which is barren or general. The organic matter or total nitrogen content of the two gangue layers in the Anjialing Mine, the total potassium content of the upper shale layer in the Anjialing Mine, and the total phosphorus content of the carbonaceous mudstone layer in the East Opencast Mine are rich, which are significantly higher than those of the loess parent material layer. The fine sandstone layer at the bottom of the East Opencast Mine and the marl layer in the Anjialing Mine have excessively high sulfur content, and the former cadmium element environmental quality index is 1.05, which is a slight pollution level. The pH value of the fine sandstone layer at the bottom of the Anjialing Mine is as low as 4.25 and the acidity is too high. Most of the rock and soil layers in the Pingshuo opencast mine are of good environmental quality but poor comprehensive fertility quality. The rock and soil layers with safe environmental quality, which have rich individual nutrient contents and are easily weathered, can be used as the alternative material for rebuilding the reclaimed soil. It is conducive to improving the quality of the reclaimed soil and improving the productivity of reclaimed soil in a short time.