Optimization Methods and Activation Mechanisms for Enhancing Activity of Coal Gangue Powder

doi:10.16552/j.cnki.issn1001-1625.2025.0851

Abstract

Abstract:

The activity of coal gangue determines its potential and application scenarios for resource utilization in the building materials sector. To investigate methods for enhancing coal gangue activity， coal gangue powder from the Shijiazhuang metropolitan area was selected as the subject. Compressive strength， flexural strength， and reactivity index were adopted as evaluation metrics. The study compared the activity of coal gangue powder after single and combined treatments of mechanical activation， thermal activation， and chemical activation， along with the corresponding changes in the mechanical properties of mortar. Additionally， laser particle size analysis， XRD， and SEM were employed to analyze the mechanism of enhancing gangue powder activity at the microscopic level. Results indicate that mechanical activation-thermal activation-chemical activation synergistic treatment yields the most significant enhancement in both reactivity of coal gangue powder and mechanical properties of mortar， followed by thermal activation. The effectiveness of chemical activation depends on the type of activator， with CaO demonstrating the best activation effect. The recommended composite activation parameters are 60 min mechanical grinding， calcination at 650 ℃， and 4% （mass fraction） CaO. The corresponding coal gangue powder reactivity index， 28 d mortar compressive strength， and 28 d flexural strength are 108.20%， 46.2 MPa， and 8.1 MPa， respectively. Mechanical grinding and high-temperature calcination enhance the hydration reactivity of coal gangue powder by regulating its particle size distribution and phase composition ratio. Chemical activation primarily promotes the formation of hydration products like calcium silicate hydrate （C-S-H） gel through alkaline environment adjustment， achieving simultaneous improvement in both the reactivity of coal gangue powder and the mechanical properties of mortar.

Key words: coal gangue powder, activation method, activity index, mechanical strength, microscopic testing, activation mechanism

CLC Number:

TD849.5

CUI Yingbin, LIAN Haikun, LIU Fangfang, WANG Zhen, FAN Taotao, SI Chundi, LI Zixuan. Optimization Methods and Activation Mechanisms for Enhancing Activity of Coal Gangue Powder[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(2): 528-539.

Figures/Tables 14

References 32

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Factor level	A： Grinding time/min	B： Calcination temperature/℃	C： CaO content/%
1	40	650	2
2	60	750	4
3	80	850	6

Factor level	A： Grinding time/min	B： Calcination temperature/℃	C： CaO content/%
1	40	650	2
2	60	750	4
3	80	850	6

Number	Horizontal Combination	Influencing factor			Compressive strength/MPa			Flexural strength/MPa			Activity index/%
Number	Horizontal Combination	A	B	C	3 d	7 d	28 d	3 d	7 d	28 d	Activity index/%
1	A1B1C1	40	650	2	19.2	29.1	41.8	3.8	5.8	7.5	97.89
2	A1B2C2	40	750	4	18.4	28.3	45.6	3.5	4.8	8.0	106.79
3	A1B3C3	40	850	6	19.2	27.1	45.4	3.6	4.8	8.0	106.32
4	A2B1C2	60	650	4	21.6	33.6	46.2	3.9	6.1	8.1	108.20
5	A2B2C3	60	750	6	20.8	32.2	45.2	3.6	5.9	8.0	105.85
6	A2B3C1	60	850	2	18.2	25.3	42.5	3.5	4.6	7.6	99.53
7	A3B1C3	80	650	6	20.4	28.7	44.7	3.8	5.2	7.9	104.68
8	A3B2C1	80	750	2	19.1	29.0	43.8	4.0	4.7	7.8	102.58
9	A3B3C2	80	850	4	17.8	24.9	43.6	3.2	4.4	7.8	102.11

Number	Horizontal Combination	Influencing factor			Compressive strength/MPa			Flexural strength/MPa			Activity index/%
Number	Horizontal Combination	A	B	C	3 d	7 d	28 d	3 d	7 d	28 d	Activity index/%
1	A1B1C1	40	650	2	19.2	29.1	41.8	3.8	5.8	7.5	97.89
2	A1B2C2	40	750	4	18.4	28.3	45.6	3.5	4.8	8.0	106.79
3	A1B3C3	40	850	6	19.2	27.1	45.4	3.6	4.8	8.0	106.32
4	A2B1C2	60	650	4	21.6	33.6	46.2	3.9	6.1	8.1	108.20
5	A2B2C3	60	750	6	20.8	32.2	45.2	3.6	5.9	8.0	105.85
6	A2B3C1	60	850	2	18.2	25.3	42.5	3.5	4.6	7.6	99.53
7	A3B1C3	80	650	6	20.4	28.7	44.7	3.8	5.2	7.9	104.68
8	A3B2C1	80	750	2	19.1	29.0	43.8	4.0	4.7	7.8	102.58
9	A3B3C2	80	850	4	17.8	24.9	43.6	3.2	4.4	7.8	102.11

Indicator	3 d compressive strength			7 d compressive strength			28 d compressive strength			Activity index
Indicator	A	B	C	A	B	C	A	B	C	A	B	C
Extreme difference	1.27	2.00	1.30	3.30	5.17	1.60	0.60	1.03	2.43	1.40	2.42	5.70
Primary and secondary factor	B>C>A			B>A>C			C>B>A			C>B>A
Indicator	3 d flexural strength			7 d flexural strength			28 d flexural strength			—
Indicator	A	B	C	A	B	C	A	B	C	—
Extreme difference	1.27	2.00	1.30	0.77	1.10	0.27	0.07	0.13	0.33	—
Primary and secondary factor	B>C>A			B>A>C			C>B>A			—