The Calcination Process in a System for Washing, Calcinating, and Converting Treated Municipal Solid Waste Incinerator Fly Ash into Raw Material for the Cement Industry

Figures & data

Table 1. Element content of RFA, CaFA, and NaFA (wt %)

Element	RFA	CaFA	NaFA
O	37.3	24.6	13.2
Si	4.97	2.68	1.28
C	3.24	7.55	8.17
Cl	6.81	16.2	33.9
S	3.31	1.81	1.31
Ca	24.7	28.2	10.2
K	2.99	3.38	5.84
Na	2.97	3.46	18.5
Ti	1.51	0.82	0.54
Mg	1.12	0.72	0.34
P	0.67	0.24	0.18
Ba	0.27	0.12	–
Al	3.99	4.30	5.92
Fe	2.32	1.56	0.71
Zn	0.22	0.39	0.89
Cu	0.24	0.06	0.15
Pb	0.39	0.21	1.23
Br	0.11	0.27	0.91

Table 2. Element content of RFA-II#, CaFA-II#, and NaFA-II# (wt %)

Element	RFA-II#	CaFA-II#	NaFA-II#
O	45.0	41.3	34.8
Si	5.42	4.23	4.52
Br	0.02	0.04	0.14
Cl	0.96	2.67	3.98
S	3.72	2.33	1.22
Ca	23.5	26.0	15.1
Fe	5.27	1.97	2.33
Zn	2.11	2.63	8.13
K	0.99	0.87	0.96
Na	0.66	0.69	1.29
Ti	1.48	1.15	1.44
Mg	1.35	1.34	1.39
P	0.74	0.40	0.60
Al	3.59	2.17	2.55
Cu	0.55	0.15	0.69
Pb	0.95	0.37	6.38
Cr	0.20	0.06	0.10

Table 3. Experiment design of the formal experiments I

Code	Temperature (°C)	Heating Time (hr)	Dwell Time (hr)
1#	400
2#	500
3#	600
4#	700
		1	1
5#	800
6#	900
7#	1000
8#	1100
Notes: Atmosphere, 100% N2; flux = 25 mL/min.

Table 4. Experiment design of the formal experiments II

Code	Temperature (°C)	Heating Time (hr)	Dwell Time (hr)	Atmosphere	Flux (mL/min)
9#	1000	1	1	10% O2	25
10#	1000	1	1	10% O2	50
11#	1000	1	1	10% O2	75

Figure 1. Experimental results of calcinating formal experiment I: (a) LOR weight and (b) chlorine concentration in the residue.

Figure 2. Data processing from Figure 1: (a) left derivative of LOR curve, (b) chlorine amount left in the residue, and (c) left derivative of chlorine left curve.

Table 5. Contribution of some elements to the LOR of calcinated RFA-II#, CaFA-II#, and NaFA-II# at 1000 and 1100 °C

	RFA-II#				CaFA-II#				NaFA-II#
	1100°C		1000°C		1100°C		1000°C		1100°C		1000°C
	LOR = 10.4%		LOR = 7.54%		LOR = 24.6%		LOR = 23.2%		LOR = 31.4%		LOR = 27.7%
Element	Con. (%)	LOW (%)	Con. (%)	LOW (%)	Con. (%)	LOW (%)	Con. (%)	LOW (%)	Con. (%)	LOW (%)	Con. (%)	LOW (%)
Ca	26.0	0.18	25.4	0.04	33.8	0.52	34.6	–	26.7	–	25.8	–
S	2.92	1.10	3.58	0.41	0.45	1.99	0.70	1.79	0.41	0.94	0.60	0.79
Pb	–	0.95	0.08	0.88	–	0.37	–	0.37	–	6.38	1.74	5.12
K	0.53	0.51	0.82	0.22	0.14	0.76	0.27	0.66	0.09	0.90	0.46	0.63
Cu	0.15	0.41	0.22	0.35	0.21	–	0.21	–	0.83	0.12	0.81	0.11
Zn	2.16	0.18	2.26	0.02	2.33	0.87	3.05	0.29	8.16	2.54	9.89	0.98
Al	4.11	–	4.13	–	4.22	–	4.05	–	4.54	–	4.77	–
Mg	1.60	–	1.56	–	2.16	–	2.12	–	2.41	–	2.66	–
Na	0.83	–	0.85	–	0.18	0.56	0.27	0.49	0.82	0.73	0.74	0.76
Notes: Con. = concentration; LOW = Concentration FA-II# − (1 − LOR) × Concentration calcinated-FA-II#.

Table 6. TC and inorganic carbon value of RFA-II#, CaFA-II#, and NaFA-II#

	RFA-II#	CaFA-II#	NaFA-II#
TC (%)	0.43	5.02	6.09
Inorganic carbon (%)	0.37	2.18	0.79

Figure 3. Experimental results of formal experiment II: (a) LOR weight and (b) chlorine concentration in the residue.

Figure 4. XRD results of samples in formal experiment II: (a) RFA-II#, (b) CaFA-II#, and (c) NaFA-II#.