Comparative Analysis of Ash Content Determination Methods of Imported Low-Ash Lignite
In this paper,two methods for the determination of ash content in low-ash lignite are established:one is to reduce the burning time at high temperature,and the other is to increase the surface area of the ash dish.The reduction of the high-temperature burning time is due to the low ash content and flammability of imported low-ash lignite,and the burning time is changed to 10 min at 500℃ and 20 min at 815℃,which can make the coal sample burn to a constant weight.The purpose of increasing the surface area of the ash dish is to increase the contact area between the coal sample and the air,which can increase the reaction rate between the coal sample and oxygen per unit time,and promote the rapid burning of the coal sample to a constant mass at a specific temperature.The F-value of the method of reducing the high-temperature burning time and the slow-ashing method was between 1.15-2.38,and the F-value of the method of increasing the surface area of the ash dish and the slow-ashing method was between 1.02-3.92.When the confidence level is P = 95%,F＜F0.05,6 = 4.28,so there is no significant difference in the precision between the method of increasing the surface area of the ash dish or reducing the high-temperature burning time method and the slow-ashing method.These two methods are simple,convenient and fast to operate,and have the advantages of strong operability,which can solve the problem of rapid determination of ash content of imported low-ash lignite and better meet the daily detection work.
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