Table 2. Results of Contact Angle of Coal Sample after Surfactant Titration under High Mineralization.

	contact angle for different concentrations of mineralized water (°)
concentrations of OP-10 (%)	0	2	5	8	10	15	20
0.0	42.22	43.96	44.89	45.33	45.42	47.47	48.15
0.2	40.49	43.02	43.40	43.73	43.54	45.65	46.50
0.5	36.99	40.07	41.14	42.80	43.20	44.15	44.30
1.0	30.57	33.49	37.20	38.21	38.94	38.96	39.15
2.0	22.13	28.68	32.79	34.55	35.08	36.36	36.63