| Paste filling mining is an important part of green mining in coal mine,and it is an important method for coal mining enterprises to improve coal recovery rate.At the same time,An important reason that restricts the development of filling mining in coal mine is that the production cost increases greatly and the production efficiency is low.In paste filling,the cost of filling materials accounts for more than half of the total cost.The cementitious material mainly composed of slag can make use of a large amount of industrial waste slag to reduce the filling cost.Slag cementitious material can make use of a large amount of industrial waste to reduce the filling cost..In this paper,the raw materials of paste filling are investigated.Coal gangue,fly ash,cementitious material,admixture and mine water are selected as the filling raw materials whose physical and chemical properties are analyzed to determine the relevant performance indicators.XRD and SEM tests were carried out to study the hydration and hardening mechanism of the binder.The results show that gelatin binder is a kind of slag cementitious material,and its hydration products are mainly hydrated calcium silicate,ettringite,etc.The alkali and sulfate composite activators in the binder system play a synergistic role in the hydration process,and the ettringite produced is helpful to improve the compactness of hydration products.The alkali and sulfate composite activators in the binder system play a synergistic role in the hydration process,and the ettringite produced is helpful to improve the compactness of hydration products.The amount of binder has a great influence on the performance of paste.Increasing the amount of binder can significantly improve the strength of paste and reduce the bleeding rate.Considering the strength and pumpability index,the amount of binder should not be less than 120kg/m~3.If the final strength is not less than 5MPa,the amount of binder should not be less than 160kg/m~3.The amount of fly ash has a great influence on the pumpability of paste.When the content of fly ash is lower than120kg/m~3,the prepared paste is easy to separate and has potential safety hazard.From the perspective of cost control and material performance improvement,the dosage of fly ash should be 180?210 kg/m~3.The initial concentration of the paste is82%-83%.PA and HA admixtures are added separately,that is,PA admixture is added in the ground filling station and ha admixtures are added in the underground filling face.PA admixture can effectively improve the flowability of paste,reduce the water consumption by more than 10%;without increasing the amount of binder,the strength can be increased by 10%-30%.The results show that the way of adding ha additive is injection type;the paste loses its fluidity within 30 min after adding ha;at the same time,the best amount of HA is determined in the test.When the amount of HA is 5 kg/m~3,the time of removing the mold can be shortened to 4 h.Gaohe Energy paste filling project has been applied with cementitious materials and admixtures.The annual recovery of coal resources is up to 800000 T,which can effectively solve the problem that coal under village,railway line and river.The annual treatment of gangue is up to 1 Mt and fly ash of 100000 t.It greatly solves the problems of land occupation and waste disposal.It can increase the profit of 122.32million yuan per year,which greatly solves the employment problem of local people.The cost of cementitious materials can be saved by 20 yuan/m~3by using cementitious materials by comparing cement and binder.The dissertation has 30 figures,28 tables and 90 references. |
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