Research And Development Of Biomass-Coal Mixed Combustion Ash Polymer Backfill And Strength Formation Mechanism

The mixed ash of biomass and coal is a solid waste rich in silicon and aluminum and has good volcanic ash activity.As a by-product of blast furnace ironmaking rich in calcium,slag is often used as cementitious material.Coal gangue has certain activity and is often used as aggregate in paste filling field.Therefore,on the basis of paste filling technology and the excellent properties of the above three solid wastes,it is of great scientific significance to develop a new type of biomass and coal mixed combustion ash polymer filling body and explore its strength formation mechanism,for green filling mining and solid waste disposal in mines.In this paper,a new paste filling material was prepared by using biomass and coal ash and slag as cementitious material,coal gangue as aggregate,sodium hydroxide and sodium silicate as alkali activator.The influence of various factors on the compressive strength of net slurry at different ages was studied from the Angle of variance,range and grey correlation degree.Single factor analysis and multi-objective algorithm were used to prepare the cementitious material and obtain its optimal mixture ratio.Response surface method and satisfaction function method were used to prepare biomass and coal mixed combustion ash backfill and obtain its optimal mix ratio.SEM-EDS,XRD and FTIR were used to explore the strength formation mechanism of biomass and coal mixed combustion ash cementable material and geopolymer backfill.The results show that:（1）Based on the test of biomass and coal mixed combustion ash,it was found that the effects of various factors on the compressive strength of the slurry at different ages were consistent:slag content>alkali content>sodium silicate modulus;（2）In the mortar test,the flexural strength and compressive strength increase with the increase of slag content,and with the increase of sodium silicate modulus and alkali content,both show a trend of rising first and then decreasing.Through single factor analysis and multi-objective algorithm,the optimal mixture ratio of biomass and coal ash cementing material was determined as follows:slag content was 40%,sodium silicate modulus was 1.22,alkali content was 10.56%;（3）On the biomass and coal burning ash in the preparation of polymer filling process,found that the uniaxial compressive strength of 28d and cost increases with the increase of mass concentration and decreases with the increase of bone glue than,slump decreases with the increase of mass concentration,the increase of the ratio of collagen increased,but fine rate relative to the mass concentration of coal and gangue,bone glue,relatively small impact on the response value results.Response surface method and satisfaction function method were used to obtain the optimal mixture ratio of backfill:mass concentration of 82%,bone glue ratio of 3.585,fine gangue rate of 40%.（4）SEM-EDS,XRD,FTIR and MIP were used to reveal the strength formation mechanism of cementing materials and backfill.SEM-EDS results showed that C-S-H gel,C-A-S-H gel and Ca CO₃were generated in both cementing materials and backfill,and the products gradually increased with the growth of age.XRD results show that the diffraction peak of the product increases with the growth of the phase.FTIR results showed that h-O-H,Si-O,Si-O-Al and C-O chemical bonds were formed in the reaction products.The growth of the age,the MIP results show that with the reaction product of the increase in the Numbers of gel filled with harmful holes exist in the process of sample preparation is bigger,more holes,at the same time,the number of internal structure bore less pollution and harmless got growth,performance gradually dense in the internal structure,porosity is reduced,and SEM,EDS,XRD,FTIR analysis results.The paper has 49 pictures,33 tables,and 99 references.