Rule Of Hydration Heat Generation And Prediction Model Of Ventilation Cooling For Cemented Tailings Backfill

The backfill mining method has been widely used in the deep mining processes due to its advantages in low loss and dilution,high utilization of solid wastes,such as tailings,and effective control of stope ground pressure.This also meets the goal of domestic green mine construction.For deep mines that adopt backfill mining,the problem of thermal damage is prominent.At present,there are few studies on the hydration heat of cemented tailings backfill and its impact on deep thermal damage.Therefore,studying the hydration heat change of cemented tailings backfill and the change law of ventilation cooling in excavation roadway containing the heat source of cemented tailings backfill is crucial to the calculation of deep cold demand and the improvement of thermal environment.In this thesis,a combination of similar material experiment,theoretical analysis,field test and numerical simulation is used to study the hydration heat change of cemented tailings backfill and the change law of ventilation cooling in excavation roadway containing the heat source of cemented tailings backfill.The laboratory similar material experiment method was used to analyze the temperature evolution of the cemented tailings backfill samples under different slurry concentrations,cement-sand ratios,dosages of cemented powder and volume variables.The results show that the hydration of cement and cemented powders are the main sources of hydration heat of the samples in the early and middle-late stage of the reaction,respectively.The sample temperature is positively correlated with slurry concentration,cement-sand ratio,dosage of cemented powder and volume.Compared with the change of sample temperature,an evaluation method for the heat generation of cemented backfill was proposed based on the characteristic point temperature and duration,and the ratio of the most and least hydration heat generated by cemented tailings backfill and the optimal evaluation index were obtained by analysis.According to the ? theorem and matrix theory,a cemented tailings backfill hydration heat generation temperature model was established based on the similar materials experimental results for hydration heat generation of cemented tailings backfill.The average absolute percentage error between the theoretical calculation value of the model and the experimental value in the laboratory is 0.49%,which verifies the accuracy of the cemented tailings backfill hydration heat generation temperature model.Using EDS energy spectrum analysis and Smileview software,the Ca/Si and particle size of the hydration products in the samples S6,S9 and S13 are analyzed,revealing the change law of Ca/Si and particle size of cemented tailings backfill hydration products under different similar material ratios and ages.According to the previous related researches and their combination with the actual situation of the site,the surrounding rock temperature,inlet wind speed,inlet wind temperature and surrounding rock thermal conductivity are selected as the main variables.COMSOL Multiphysics software was used to establish a physical model of the excavation roadway containing the heat source of cemented tailings backfill.The results show that the hydration heat of cemented tailings backfill has an important influence on the distribution of wind temperature in the excavation roadway,and it is effective to use ventilation cooling to improve the thermal environment in the deep excavation roadway.The impact and change trend of different variables on the wind temperature of the roadway section are obtained by simulating the distribution of the temperature field in the excavation roadway during ventilation cooling in excavation roadway containing the heat source of cemented tailings backfill.Based on the temperature distribution of ventilation cooling in excavation roadway containing the heat source of cemented tailings backfill,a wind temperature prediction model in the excavation roadway containing the heat source of cemented tailings backfill was established combined with the properties of the surrounding rock.The total average absolute percentage error between the theoretical calculation value of the model and the simulated experimental value is 0.08%,which verifies the accuracy of the model.The results proposed in this thesis provide a theoretical basis for the hydration heat generation estimation of cemented tailings backfill,the determination of the deep heat source structure,the heat contribution rate calculation of the heat source and the calculation of cold demand,which supplies and enriches the basic theory of the hydration heat generation of cemented tailings backfill.By calculating the impact of hydration heat generation on the surrounding environment,this thesis provides experimental data for the formulation of deep ventilation cooling programs.