| Coal freezing adhesion on the surface of bend roller and belt of belt conveyor,roller,sweeper,mine car and loader during winter in Inner Mongolia,Heilongjiang,Liaoning and other northern cold areas seriously affects the safety and efficiency of coal transportation.At present,there is little theoretical analysis about coal freezing adhesion,and the prevention and cure technology are usually about the freezing adhesion on mine car and belt.There is not effective prevention and cure technology about the freezing adhesion on bend roller.Based on The National Natural Science Fund "The study on strip mne belt conveying freezing adhesion mechanism in cold area" and the enterprise project "Analysis and prevention about common breakdown of the belt conveyor with large transportation distance in low temperature environment",the properties of coal freezing adhesion on transportation equipment is analyzed systematically,and the prevention and cure technology about coal freezing adhesion on bend roller of belt conveyor.The main research contents and conclusions are as follows:1.Study on coal freezing adhesive properties(1)The test system of coal freezing adhesion is builded.The boundary structure,separation mode and strength properties on different freezing adhesion matrix are analyzed by the test of freezing adhesion properties and other tests,and the mechanism is also analyzed.Compared to the metal and rubber freezing adhesion matrix materials,UHMWPE matrix material has a good anti-freezing adhesive effect.(2)According to three typical freezing adhesion matrix materials of coal transportation equipments,the influence on properties of coal freezing adhesion of single factor is analyzed from three aspects,which include the external conditions such as temperature,time,pressure),the properties of coal such as external water content,particle size,component clay and the properties of matrix such as matrix roughness,waviness.(3)The comprehensive influence of factors on freezing adhesive properties is analyzed.The freezing adhesive properties of coal samples from different coal mines which have different external water content,particle size,coal type and pore volume distribution is analyzed,and the comprehensive influence and correlation of factors are analyzed.The influence of the interrelation between the waviness of the matrix surface,external water content and particle size of coal on freezing adhesive properties is analyzed.(4)The regression analysis of coal freezing adhesive strength on three typical freezing adhesive matrix materials was carried out by the general rotary combination regression design method.The mathematical regression prediction model between the coal freezing adhesive strength and the main influence factors and the influence degree of each factor on freezing adhesive strength are obtained,which build the foundation for the prediction of the freezing adhesive strength.2.Prevention of freezing adhesion of belt conveyer bend pulley(1)Research on anti-freezing adhesive heating bend drum and screw sweeperBased on the study of the freezing adhesive properties,The temperature factor has a significant effect on freezing adhesive strength.The prevention and cure technology for coal freezing adhesion on bend roller of belt conveyor of the anti-freezing adhesive heating bend drum and screw cleaner is put forward to improve freezing adhesion by carbon fiber cable heating and mechanical cleaning of screw cleaner.The anti-freezing adhesive heating bend drum and screw cleaner for M101-2 belt conveyor from Xilinhaote Mineral Company need 8.2 kN friction driving force and 8.7%raise driving power of belt conveyor for heating cleaning.The similar experimental prototype is manufactured and relevant experiments are carried out.The screw sweeper has good mechanical cleaning ability and the surface temperature of the drum and screw sweeper raise by 5.5?9.5?.According to the experimental results of temperature rise and power of the prototype,theoretical analysis of convection heat transfer for heating drum and screw sweeper heating system is carried out,and the forecast of power and temperature rise parameters of the prototype is obtained.The surface temperature raise by 5.5?9.5? of the practical drum and screw sweeper prototype needs 850 W?1300 W.Test of heating drum and screw sweeper cleaning freezing adhesion by heating show that the surface temperature rise and the freezing adhesive strength reduce,and the clearance of freezing adhesion is easier and more thorough.The surface temperature rise of the screw sweeper improve the freezing adhesion between the blades.The anti-freezing adhesive heating bend drum and screw sweeper has a good prevention and cure effect.(2)Research on anti-freezing adhesive mechanism and application of UHMWPE material bend drumAiming at coal freezing adhesion on bend roller of belt conveyor,based on the analysis of freezing adhesive properties of different matrix materials,the mechanism of lower freezing adhesive strength of UHMWPE material was further analyzed from the material molecular chemical composition aspect.UHMWPE is a non-polar polymer with highly symmetrical molecular structure compared to rubber and metal matrix materials.Water molecules can not form hydrogen bonds with UHMWPE,so its solid surface energy is very low and surface wettability is very poor,which makes the coal slurry ice formed by water coagulation in coal has a bad contact with matrix material surface.So the freezing adhesive strength is very small.So the UHMWPE material anti-freezing adhesive bend drum gets a good field application effect.Aiming at the defect of the original simple steel plate cleaning device for UHMWPE material anti-freezing adhesion drum.The programme of using flexible catenulate slicker which has a good fitting is also presented.The programme needs 0.30 kN friction driving force and 0.32%raise driving power of belt conveyor for cleaning.The driving power of belt conveyor raise is little and extra driving power of belt conveyor is not needed. |
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