Thermal characterization of hydrated eco-friendly clinkers produced from pulp and paper mill waste

Simão, L.; Lóh, N. J.; Hotza, D.; Raupp-Pereira, F.; Labrincha, J. A.; Montedo, O. R. K.

doi:10.1590/0366-69132018643712339

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Articles • Cerâmica 64 (371) • Jul-Sep 2018 • https://doi.org/10.1590/0366-69132018643712339 copy

Thermal characterization of hydrated eco-friendly clinkers produced from pulp and paper mill waste

Caracterização térmica de ecoclínqueres hidratados produzidos a partir de resíduos da indústria de papel e celulose

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Industrial wastes from pulp and paper mills are potentially useful materials to use as alternative materials in clinker production. In this study, eco-friendly clinkers were obtained using only waste as feedstock. Eco-friendly clinker with different C₃S and C₂S contents were produced and hydrated for 7 days at 40 °C, or for 28 and 90 days at room temperature. The potentialities of these waste and the products obtained were revealed through chemical (XRF), thermal (DTA/TG) and surface area (BET) analysis. For comparison, a common ordinary Portland cement (OPC) was tested. As expected, the hydration rate of formulations presenting higher C₃S content was higher, generating higher amounts of Ca(OH)₂. Furthermore, the amount of Portlandite formed was lower when compared to OPC.

Keywords:
pulp and paper mill waste; clinker; hydration; portlandite

Table I - Investigated formulations (wt%).

Formulation	Lime mud	Biomass ashes	WWTP sludge
F1	66	34	0
F2	66	31	3
F3	68	30	2
F4	69	29	2
F5	70	30	0

Table II - Chemical composition (wt%) of the wastes.

Component	Biomass ashes	WWTP sludge	Lime mud
Al₂O₃	9.94	13.24	0.22
SiO₂	49.65	5.24	1.06
Na₂O	0.33	0.67	1.06
K₂O	3.14	0.30	<0.05
CaO	2.10	2.14	53.55
MgO	1.25	0.32	0.91
Fe₂O₃	4.07	0.75	0.16
MnO	0.24	0.29	0.10
P₂O₅	0.65	1.83	0.65
TiO₂	0.95	0.07	<0.05
^aLOI	26.97	74.84	42.25

Table III - Estimated chemical compositions (wt%) of the formulations.

Component	F1	F2	F3	F4	F5	^aHBR
Al₂O₃	4.88	6.02	5.38	5.24	4.35	3.46
SiO₂	24.33	22.91	22.06	21.40	21.69	19.65
Na₂O	1.36	1.43	1.43	1.45	1.42	0.13
K₂O	1.52	1.43	1.37	1.33	1.35	0.84
CaO	62.11	62.28	64.02	64.92	65.70	66.30
MgO	1.62	1.61	1.61	1.61	1.62	4.74
Fe₂O₃	2.08	2.00	1.92	1.87	1.87	3.65
MnO	0.23	0.25	0.24	0.24	0.22	0.10
P₂O₅	1.04	1.23	1.17	1.18	1.05	0.12
TiO₂	0.50	0.47	0.45	0.44	0.45	0.31
Na₂O+K₂O	2.88	2.85	2.81	2.78	2.77	0.97
^bNa₂O eq	2.36	2.37	2.34	2.32	2.31	-

Table IV - Crystalline phases (wt%) determined by Rietveld method.

Sample		C₃S	C₂S	C₃A	C₄AF	χ²
HBR	-	59	26	4	11	4.264
F1	1350	10	69	9	11	4.746
	1400	31	49	3	17	4.692
	1455	4	63	7	26	4.708
F2	1350	10	71	4	15	3.840
	1400	22	46	16	16	6.529
	1455	19	44	20	17	7.791
F3	1350	12	59	14	15	5.935
	1400	49	31	6	14	7.102
	1455	34	33	13	20	6.489
F4	1350	29	44	13	14	6.052
	1400	39	37	8	16	5.772
	1455	46	32	11	11	4.704
F5	1350	23	52	13	12	6.538
	1400	36	35	6	23	5.502
	1455	49	22	8	21	5.164

Table V - Specific surface area (m2.kg-1) of the materials, after milling and sieving (<45 µm).

Formulation	1350 °C	1400 °C	1455 °C
F1	1352	2499	2341
F2	1578	1575	2033
F3	2332	-	2391
F4	1668	1911	1196
F5	936	1964	1926
HBR		1107

Table VI - Dehydration temperatures (°C) of C-S-H identified in the thermograms of formulations F1, F2, F3 and F4.

Formulation		7 days	28 days	90 days
F1	1350 °C	224.34	214.08	220.20
	1400 °C	219.57	218.11	225.38
	1455 °C	211.61	222.68	227.98
F2	1350 °C	209.73	217.18	219.70
	1400 °C	210.42	222.16	225.84
	1455 °C	214.20	217.67	223.34
F3	1350 °C	217.58	222.85	222.24
	1400 °C	212.67	-	-
	1455 °C	219.52	218.86	237.38
F4	1350 °C	216.21	216.98	220.82
F4	1400 °C	212.10	-	-

Table VII - Quantification of portlandite (CH) from DTA-TG curves.

Formulation		Day	Wi (mg)	Peak (°C)	TG (mg)	CH (mg)	CH (wt%)
HBR		7^a	15.9670	421.49	0.4290	1.7637	11.05
F4	1455		19.7990	413.68	0.1511	0.6212	3.14
F5	1350		16.6930	412.59	0.2478	1.0187	6.10
	1400		16.9530	410.95	0.1300	0.5344	3.15
	1455		15.0000	409.53	0.1141	0.4691	3.13
HBR		28	16.6540	431.31	0.5072	2.0852	12.52
F4	1455		16.8490	415.30	0.1096	0.4506	2.67
F5	1350		17.2550	410.11	0.0652	0.2680	1.55
F5	1455		17.7140	413.51	0.0510	0.2095	1.18
HBR		90	15.4430	431.75	0.3710	1.5252	9.88
F4	1455		18.7680	422.29	0.2011	0.8267	4.41
F5	1350		16.4310	418.15	0.1153	0.4740	2.88
F5	1455		15.9870	424.32	0.1623	0.6672	4.17

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