Study On Preparation And Alkali Excitation Mechanism Of Coal Gangue-Iron Tailing Ore Non-Sintering Ceramsite

With the rapid development of domestic industrialization,a large amount of industrial solid waste is generated during the production of raw materials.This waste exhibits a low utilization rate,occupies a large amount of space,and poses safety hazards.Therefore,there is a pressing need to conduct an in-depth study on the resource utilization of industrial solid waste.Ceramsites,a new type of lightweight and high-strength aggregate,have garnered attention in the field of green building materials.To prepare non-sintering ceramsites using a large amount of mixed industrial solid waste,mechanical grinding is employed to stimulate the activity of gangue.The influence of different fineness levels on the change of gangue activity is investigated.Experimental studies were conducted to investigate the mechanical properties of non-sintering ceramsites made from coal gangue,iron tailing sand,and industrial solid waste.Microscopic techniques were utilized to analyze the mechanism of alkali exciter,which stimulates the activity of industrial solid waste instead of cement.This approach not only reduces the need for cement admixture and saves preparation costs,but also achieves the goal of resource utilization of large admixtures of industrial solid waste.The main research contents and conclusions are outlined below:(1)The mechanical grinding method was utilized to stimulate the activity of coal gangue,and the microstructure,mineral composition,and mechanical properties of coal gangue cement specimens were studied under different fineness levels.The gangue activity was quantified using the specific strength algorithm,and the activation law of mechanical force on the gangue was revealed.The results indicate that the average particle size of the gangue is 20.6μm,the specific surface area is 505 m~2/kg,and the activity index is 91.8%.The contribution of the volcanic ash effect reaches 25.1%,making it applicable in the preparation of non-sintering ceramsites granules.(2)The single-factor variable test method was used to study the effect of the admixture of inactive solid waste gangue and iron tailing sand on the cylinder compression strength,bulk density,1h water absorption rate,strength after water absorption,softening coefficient and microstructure of non-sintering ceramsites,to determine the best admixture of inactive solid waste for the preparation of ceramsites and to improve the resource utilization of inactive solid waste.The research results show that coal gangue as a binder can bond agglomerated powder,and iron tailing sand as an inert admixture can fill the pores.The comprehensive performance of ceramsites is optimal when coal gangue is mixed with 10%and iron tailing sand is mixed with35%.(3)Through a three-factor four-level orthogonal test,this study investigated the effects of fly ash,Na OH,and aluminum powder content on the mechanical properties of non-sintering ceramsite.Analysis of variance was employed to reveal the impact of various factors on the performance of ceramsite.The optimal mixing ratio of alkali-excited solid waste with a large dose was determined to prepare non-sintering ceramsite,which met the requirements of a 600-grade specification.The total solid waste content reached 73%,while the cement content was reduced to only 15%,thus achieving the goal of utilizing a large amount of industrial solid waste and reducing the amount of cement needed.(4)The mechanism of preparation and alkali-excited hydration reaction of non-sintering ceramsites was revealed by analyzing the internal structural changes using X-ray diffraction and SEM microscopic techniques.The results show that the agglomeration of coal gangue and other powders into pellets is the result of the action of interpowder attraction and liquid bridge force.The alkali exciter was found to effectively activate the activity of fly ash and coal gangue,generating calcium alumina,C-S-H gel,and other hydration products,which were intertwined to form a dense structure of gel as a whole.Moreover,fly ash was found to promote the secondary hydration reaction of coal gangue,further improve the performance of non-sintering ceramsites.