Water-physical Properties Of Foamed Fly Ash Filling Materials And Their Effects On Water Quality

Fly ash is one of the largest single industrial solid wastes in China.In recent years,fly ash has been widely used in underground mining projects,such as fil ing of mined-out areas,grouting away from layers,and blocking of abandoned roadways(docks).After the fly ash material enters the underground rock layer,its own properties will be affected by the mine water,as well as the groundwater quality.This paper takes the end fil ing project of Dananhu No.1 Mine as the engineering background,and uses theoretical analysis and experimental testing methods to study the hydraulic characteristics of foamed fly ash and its impact on mine water quality.The main research results are as follows:(1)The hydraulic characteristics of foamed fly ash are analyzed.Experimentally determined,the dry apparent density of the foamed fly ash is 298.54 kg/m~3,the porosity is 80.7%,the saturated water absorption rate is 45.1%,and the uniaxial compressive strength level is C0.3.The uniaxial compression test found that when the moisture content is greater than 0.3,the stress-strain curve of the foamed fly ash has no obvious elastic stage and yield stage,and the specimen exhibits strong ductility,which is mainly due to the presence of fissure water,which delays The penetration time of microcracks delays the destruction rate of the material macroscopically;at the same time,it is found that with the increase of water content,the elastic modulus of foamed fly ash gradually decreases due to the existence of cohesive force and pore water bearing capacity The elastic modulus of the specimen with high water content will maintain a small value and will not continue to decline.(2)Analyzed the leaching situation of the foamed fly ash tip fil ing body.Based on the analysis of the geological structure and hydrological characteristics of the 1305working face,starting from the prediction of the water inflow and the development of the water conduction cracks in the rock layer above the fil ing body,the leaching of the fil ing body is analyzed,and it is concluded that the foamed fly ash is significantly leached Conclusion.From a statistical point of view,the potential toxicity characteristics and content characteristics of the main heavy metal elements in the mine water were qualitatively and quantitatively analyzed,and the SPSS software verified that there was a strong negative correlation between the p H of the mine water and the content of Cu and Zn elements.(3)Revealed the precipitation rule of heavy metal elements in foamed fly ash under leaching.Dynamic leaching and static leaching tests found that Cu and Zn elements were wrapped in foamed fly ash base material and chemical y combined.Only in a strong acid environment,when the enriched space was destroyed,was a large amount Leaching;the influencing factors of Pb,Cu,Zn three heavy metal elements have the same primary and secondary order:particle size>p H>liquid-solid ratio.The experiment confirmed that the Pb,Cu and Zn in the foamed fly ash shower solution did not exceed the standard,indicating that the foamed fly ash as the end fil ing material will not cause pollution to the underground water environment of the mine.The paper has 31 pictures,26 tables,and 69 references.