Range of classification criteria for coal
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This post was last edited by angryant on 2018-8-19 at 14:31. When classifying coal, volatile matter content V, caking index G, and the maximum thickness of the vitrinite layer y are generally used as classification criteria. For example, the volatiles content of low-quality coal: >10~20. I don’t understand the greater-than sign “>”; what exactly is the range for the volatiles value? Who can explain it? In mathematics, it is written as: V＜10, 10＜V＜20, V＞20, etc., which makes it very easy to understand.
I once shared your confusion as well; it was only later that I realized that judging the classification of coal based on just one coal quality analysis indicator can lead to inaccuracies. A determination can be made only by considering several indicators together. Therefore, the values for these indicators are usually given as ranges rather than fixed values
My confusion isn’t about how many indicators are used for classification, but rather about the range of values for a particular indicator. For example, the volatiles content of low-quality coal is >10–20; is then a volatiles value of V=30 within this range? 30＞20 Ah.
Haha! I don’t understand it either; many of the standard descriptions in China are really bizarre!
Therefore, several indicators need to be considered together to obtain more accurate results
This post was last edited by angryant on 2018-8-20 at 19:04. Since it was already stated that the volatile matter content of low-quality coal ranges from 10 to 20, what does the › symbol before that mean? Personally, I think there are obvious errors in language expression and logic!
There are many such descriptions in the national standards; it’s probably not a logical error, it’s just that we haven’t understood the intent behind formulating these standards
Ha, it refers to the 10-20 range
Then how can the greater-than sign ahead be explained?