Table 1.

Chemical composition of CG from different producing areas.

Sources		SiO2	Al2O3	Fe2O3	MgO	CaO	Na2O	K2O	TiO2	L.O.I	Refs.
North China	Shandong	59.54	16.31	6.55	1.82	1.52	-	-	-	12.27	[43]
	Huaibei	54.12	22.38	3.56	0.71	0.98	0.64	1.13	-	-	[15]
	Fuxin	48.78	21.86	5.38	0.82	3.87	-	-	-	12.14	[44]
	Heilongjiang	58.82	27.87	8.31	-	0.78	-	1.23	1.04	1.43	[45]
	Shanxi	56.56	36.78	1.95	0.22	0.62	0.42	-	2.10	-	[46]
	Ordos	45.9	16.0	4.71	1.37	0.74	0.99	3.36	0.78	8.03	[47]
	Hebei	52.4	42.26	0.14	0.08	0.76	0.03	0.02	-	2.52	[48]
	Beijing	49.90	24.41	6.42	1.59	0.82	1.46	2.06	0.88	11.76	[49]
South China	Chongqing	58.10	24.50	5.31	1.05	5.73	1.14	1.54	-	-	[50]
	Liuzhi	46.50	16.40	13.85	3.57	10.67	1.48	1.83		-	[42]
	Yichang	49.03	34.18	0.73	-	0.20	-	0.12	1.72	13.50	[51]
	Pingxiang	52.56	16.57	3.35	2.01	1.24	0.21	2.39	-	20.71	[42]
	Xuzhou	57.95	19.02	5.32	0.82	3.16	-	-	-	-	[52]
	Xuzhou	60.24	18.50	2.58	0.52	1.48	0.14	1.53	-	-	[53]
Iran		37.8	13.14	2.85	0.73	0.76	0.28	2.02	1.17	40.96	[54]
Spain		56.4	26.34	6.42	1.07	1.06	0.17	4.02	1.21	2.38	[55]
America		34.4	14.4	3.4	0.93	1.3	0.34	3.5	1.2	38.7	[56]
Jerada		62.41	7.95	4.14	0.97	20.38	0.14	1.02	-	-	[57]