Study on the influence of grinding time to the quality characteristics of different coals
Coal general analysis test coal sample is a detection matrix that serves the coal industry policy formulation,technological innovation,standard formulation and revision,trade settlement,and other necessary coal quality indicators.Coal sample grinding is a necessary process for preparing general analysis test coal samples.Un-derstanding the impact of grinding time on coal quality characteristics can provide technical support to ensure the ac-curacy of coal quality testing results.Regarding to coal types with different degrees of metamorphism,the influence of different grinding times on the particle size distribution of general analytical test coal samples were analyzed,the trend of changes in detection results of analysis water,volatile matter,calorific value,bonding index,crucible expansion index and other items of coal samples with grinding time were studied.The results show that when the grinding time of lignite and anthracite samples is less than 90 s,the yield on the 0.2 mm sieve is higher,especially when the grinding time is 45 s,the yield on the 0.2 mm sieve of lignite and anthracite samples is 14.6%and 7.3%,respectively;after grinding for more than 90 seconds,the yield of the material on the 0.2 mm sieve is close to zero.As the grinding time increases,the yield of materials on the 0.2 mm sieve of bituminous coal samples shows an increasing trend,and the cohesive bituminous coal samples contain a small amount of materials on the 0.2 mm sieve within the grinding time range of 45-240 seconds.The grinding time has a significant impact on the analysis of water content in lignite and anthracite,but has a relatively small impact on the volatile matter and calorific value of different coal types.It has a significant impact on the bonding index and crucible expan-sion number of low cohesive bituminous coal;with the increase of grinding time,both the bonding index and crucible expansion number decrease,and the bonding index decreases particularly significantly.
grinding timecoal quality characteristicsgeneral analysis of test coal samplesbond indexsieve yieldcalorific valuecrucible expansionnumberparticle size distribution
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