Multivariable Regression and Adaptive Neurofuzzy Inference System Predictions of Ash Fusion Temperatures Using Ash Chemical Composition of US Coals

Table 2

The range of variables in 1040 US coal ash analyses.

Variable	Min	Max	Mean	Standard deviation	Variance
SiO2 (%)	13.00	80.00	42.63	12.25	150.07
Al2O3 (%)	1.60	46.00	23.73	6.97	48.59
CaO (%)	0.12	29.00	3.90	4.66	21.71
MgO (%)	0.12	7.90	1.08	0.81	0.66
MnO (%)	0.00	1.20	0.04	0.08	0.007
Na2O (%)	0.02	6.80	0.54	0.70	0.49
K2O (%)	0.01	6.80	1.78	0.98	0.96
Fe2O3 (%)	0.60	69.00	16.33	13.87	192.30
TiO2 (%)	0.08	5.60	1.12	0.49	0.24
P2O5 (%)	0.00	8.00	0.48	0.68	0.47
SO3 (%)	0.00	28.00	3.41	3.65	13.31
Base	2.23	70.98	23.68	14.51	210.54
Acids	23.26	98.61	71.38	15.9	252.81
Base/Acid	0.02	2.72	0.4166	0.405	0.164
Dolomite ratio	0.01	0.87	0.23	0.18	0.03
Silica ratio	0.17	0.99	0.67	0.20	0.04
SiO2/Al2O3	0.84	23.75	1.90	0.91	0.84
Fe2O3/CaO	0.13	110.00	10.40	14.15	200.24
IDT	1790	2910	2368.58	282.73	79936.25
ST	1930	2910	2455.19	266.04	70777.28
FT	2000	2910	2543.83	229.20	52532.64