Experimental Study On Dust Reduction Based On Wettability Of Blasting Muckpile Dust In Haerwusu Open-pit Coal Mine

Open-pit coal mines are accompanied by serious dust pollution during all aspects of operation,and currently mainly use the inefficient traditional water sprinkling dust reduction methods.Due to the wide range of open pit coal mining and the complex manner and location of dust formation,a targeted dust suppression program should be proposed according to the characteristics of dust in different operating areas.Based on this,this thesis takes the coal dust and rock dust generated by blasting muckpile of different blast stages in Haerwusu open-pit coal mine as the research object,and collects three groups of coal dust and rock dust from different blast stages in the field.Wettability and its influencing factors,and according to which the dust suppression scheme suitable for different blasting stages is compounded.The main results achieved are as follows:The physicochemical characteristics of the blasting muckpile dust of different blasting stages were analyzed by physicochemical characterization tests,including particle size distribution,microscopic morphology,industrial composition,mineral components and other physicochemical properties,and the results showed that: the blasting muckpile dust is mainly composed of large particles of 10μm～100μm;the dust surface is rough and agglomerated,with irregular internal pore structure;the coal dust is medium-ash,high water content and low coalification lignite;kaolinite is the main mineral component of coal dust,and quartz is the main mineral component of rock dust.The wettability of dust from different stages of blasting muckpile was tested by contact angle method.The results showed that: coal dust is hydrophobic and chemical dust suppressant needs to be added to improve dust reduction efficiency;rock dust is hydrophilic dust and dust suppression is carried out by water spray.The results showed that the particle size,specific surface area,moisture,ash and volatile matter of coal dust were positively correlated with wettability,and the content of kaolinite and fixed carbon were negatively correlated with wettability;the particle size,specific surface area and quartz content of rock dust were positively correlated with wettability,and the content of kaolinite was negatively correlated with wettability.The most important factors affecting the wettability of coal dust and rock dust and the best regression equation were obtained by multiple stepwise linear regression analysis,respectively.The surfactant helps to reduce the surface tension of the liquid and,within a certain mass fraction,the contact angle with the coal dust.The physical and chemical properties of different coal dusts are different,and the wetting effect with surfactants is also different.It seems that the combination solution of fast percolation T and Na Cl has the best wetting effect on three different steps of coal dusts at low mass fraction,and finally0.05wt% fast percolation T + 0.5wt% Na Cl is determined as the best dust suppression solution for 1# and 2# coal dusts,and 0.05wt% fast percolation T + 1wt% Na Cl is the best dust suppression solution for 3# coal dust.Finally,the dust suppression effect was verified by permeability experiment and spraying experiment,and it was found that the permeability of coal dust was improved after using compound dust suppressant;the dust reduction efficiency of three groups of coal dust could reach 82.5%,83% and 81.4%respectively after using compound dust suppressant spraying to reduce dust;the dust suppression efficiency of three groups of rock dust could reach 87.3%,85.3% and 85.2%respectively after using clear water spraying.There are 41 figures,19 tables,and 88 references in this thesis.