Research On Superhigh-water Material As Coal Fire Retardant Agent

Superhigh-water material as a good backfill material for the mining goaf has been proven in many practices,and it has great potential in fire prevention and extinguishing.In order to investigate the retardancy and extinguishing characteristics of superhigh-water material,promote it's better application and promotion in mine fire prevention,the basic properties and extinguishing performance of superhigh-water material are studied in this paper.Firstly,the basic properties of superhigh-water material,including setting time,viscosity,permeability and thermal stability are analyzed and tested.The results show that the setting time is influenced greatly by the water-cement ratio and temperature;the lower the water temperature and the larger the water-cement ratio,the longer the initial setting time.The higher water cement ratio of super high water material,the better permeability in coal seam.The viscosity of the superhigh-water material remains at a low level before setting time,the viscosity will increase sharply after that,and the larger the water-cement ratio of the material is,the later the sharply increasing time will be.Superhigh-water material has good waterholding property in low air velocity environment at 60?,and the smaller the water-cement ratio,the better the water-holding property.The experimental study on the prevention of spontaneous combustion of coal by superhigh-water material was carried out through selecting four low rank coals(Zhao Tong lignite,Xiao Longtan lignite,Yi Li long flame coal and Da Tong weakly caking coal)as research objects.The change law with temperature of symbolic gas concentration,CO production rate,oxygen consumption rate and CO inhibition rate were obtained respectively.It found that the superhigh-water material under different conditions has flame retardant effect on four kinds of coal samples in a certain temperature range(< 180?).In addition,the higher the material quality and the smaller the water cement ratio,the better the flame retardant effect.In order to investigate the relationship between coal sample characteristics and flame retardant properties of superhigh-water materials,the above four coal samples were also selected as research objects.After treated with the material in different conditions,the CO concentration evolution and CO inhibition rate of these four coal samples at 160 °C were studied.It found that the remarkable flame retardant effect on any coal studied could be obtained,especially Zhaotong lignite.The best inhibitory effect on lignite and long flame coal occurred when the water cement ratio is 20:1.However,the material inhibitory effect on Da Tong weakly caking coal is decreased with the water cement ratio.Under the condition of high water cement ratio(>15:1),the lower rank of coal sample,the stronger inhibitory effect of material on it.Compared to pure water,the flame retardant effect of the material is still remarkable even if the water cement ratio is as high as 30:1.The results of orthogonal test analysis show that the mass ratio and coal rank are both the significant factors affecting the flame retardancy of materials.Thus,the superhigh-water material is an ideal fire retardant and extinguishing agent for coal mine and has a good application prospect.