Abstract: (1) In the previous article "Graphical Investigation of Coal Classification Methods, Coal Composition and Properties" published in "Acta Geologica Sinica" Vol. 36 No.1, the author proposed an entirely new method of coal classification with volatile matter on combustible basis V as abscissa and the coal characteristic coefficient β as ordinate: β=2.35( Hp-0.126 Op +0.04Np)/(Cp+ 0.375Spn). (2) In this pager, as the percentage of Np is usually around 1.5% and the percentage of Spn is usually from 0.4% up to 3 %, in the Chinese coal the .effect of neglecting Np and Spn in the calculation upon the coefficient β is negligible. So a new simplified coal characteristic coefficient βˊ=2.35 (H r-Or/8)/O r is proposed to substitute β in the classification method. The percentage of error of βˊ with comparation with β is within 5 %. Chart 1 is drawn with Vr as versus βˊ for coal classification.(3) As the physical meaning of the new simplified coal characteristic coefficient βˊ is a function of the ratio of free hydrogen (H r-Or/8) to carbon Cr on combustible basis, so another new graphical coal classification method with Cr as abscissa arid (H r-Or/8) as ordinate is tried out and is plotted in Chart 2. (4) A third new graphical coal classification method with Vr as abscissa and (Or+ Nr) /Hr as ordinate is proposed and plotted in Chart 3. The ratio (Or+ Nr) /Hr was originally used as one item in the Gruner coal classification method as described in the book "Coal" by E. S. Moore. (5) Comparison of the three new graphical coal classification methods of Russian coal and Chinese coal are made and the first method with Vr as versus βˊis the most logical one to be adopted and the other two can be used as supplementary methods. (6) As only the proximate analyses are available for the Chinese coals in the different districts of whole country, so a new graphical method of coal classification is proposed with the volatile matter on combustible basis Vr as abscissa and with the fixed carbon on ash free basis as ordinate. Fig. 4 is plotted for Russian coals and fig. 5 is for Chinese coals. (7) A new coefficient of coking ability for different coals (Hr/Or) is proposed and is plotted against Vr ?in fig. 6 as a supplementary chart in graphical coal classification. Another heating value chart for the Chinese coals can also be used as supplementary chart in coal classification (fig. 7). (8) For simplification of coal classification work, four graphical charts are precalculated and plotted in fig. 8, fig. 9, fig. 10 and fig. 11: Fig. 8 is for finding the simplified coal characteristic coefficient βˊ. Fig. 9 is for finding the ratio (Or+ Nr )/Hr Fig. 10 is for finding Vr from Va. Fig. 11 is for finding the fixed carbon on ash free basis F.Cw. From the fixed carbon on analytical basis F.Ca. (9) With the use of the graphical methods of coal classification, the different kinds of Chinese coal in the different districts are found and tabulated in the table 4.

Key words: Al -Mg dissimilar materials, Ultrasonic vibration, Friction stir welding