电化学活化赤泥对过硫磷石膏矿渣水泥性能的提升研究

doi:10.16552/j.cnki.issn1001-1625.2026.0130

摘要/Abstract

摘要：

过硫磷石膏矿渣水泥作为一种低碳环保的新型胶凝材料，在工业固废资源化利用方面展现出广阔的应用前景。本研究采用电化学方法对拜耳法赤泥进行活化处理，并将处理后的赤泥应用于过硫磷石膏矿渣水泥体系中，系统考察了电化学活化赤泥对过硫磷石膏矿渣水泥力学性能、水化产物和微观结构的影响规律，揭示了其作用机理。结果表明，电化学处理实现了赤泥的活化，这种处理方式提高了赤泥中活性铝的溶出能力。经电化学处理后赤泥中部分结晶矿物向非晶态发生转变，赤泥滤液中铝元素浓度提升了18.6倍，而铁元素浓度降低了95.4%，这种组分变化提高了赤泥的火山灰活性。同时，电化学活化赤泥的掺入显著改善了过硫磷石膏矿渣水泥的力学性能，有效解决了该类水泥早期强度偏低的难题。掺入20%（质量分数）电化学活化赤泥的浆体3 d抗压强度达到24.1 MPa，相比未掺电化学赤泥的过硫磷石膏矿渣水泥组提升了6.3倍；28 d抗压强度达到45.8 MPa，相比未掺电化学赤泥的过硫磷石膏矿渣水泥组提高了40.5%，实现了早期和后期强度的同步提升。电化学活化赤泥通过提供活性铝和增强碱激发作用两个途径显著促进了早期水化反应的进行，掺入电化学活化赤泥后试样的水化诱导期从约40 h缩短至3 h，水化放热峰出现时间大幅提前。本研究为赤泥高值化利用及过硫磷石膏矿渣水泥性能提升提供了有效的技术途径。

关键词: 赤泥, 过硫磷石膏矿渣水泥, 电化学活化, 性能提升, 水化机理

Abstract:

Excess-sulfate phosphogypsum-slag cement （ESPSC） represents a low-carbon cementitious material that simultaneously valorizes phosphogypsum and granulated blast furnace slag （GGBS）， with carbon emissions only 20% to 30% of ordinary Portland cement. However， residual soluble phosphorus and fluorine impurities in phosphogypsum severely retard hydration， resulting in critically low early-age strength that limits practical application. Red mud， a strongly alkaline byproduct of Bayer-process alumina refining with global stockpiles exceeding 4 billion tonnes， theoretically provides reactive aluminum to promote hydration， yet its active components are predominantly locked within stable crystalline minerals including cancrinite， muscovite， and kaolinite. Traditional activation routes such as thermal calcination and mechanical grinding are energy-intensive and incompatible with low-temperature ESPSC system， necessitating a greener activation approach.

This study employed an electrochemical method to activate red mud at a constant potential of 1.15 V versus Hg/HgO in 4 mol/L NaOH solution at 60 ℃ for 3 h， exploiting cathodic reduction of iron oxides to disrupt the mineral lattice and liberate reactive aluminum species. The electrochemically activated red mud was incorporated into ESPSC at replacement levels of 10%， 15%， and 20% by mass， and its effects on mechanical properties， hydration products， microstructure， and hydration kinetics were systematically characterized using XRD， TG-DTG， SEM-EDS， ICP-MS， and isothermal calorimetry. Electrochemical treatment induces partial transformation of crystalline minerals to amorphous phases， evidenced by the weakening or disappearance of cancrinite and muscovite diffraction peaks. Ion dissolution analysis shows that aluminum concentration in the filtrate increases 18.6-fold to 259.521 mg/L， iron concentration decreases by 95.4% to 0.030 mg/L， and solution pH rises from 10.64 to 12.48， confirming substantially enhanced pozzolanic reactivity.

Incorporation of 20% electrochemically activated red mud achieves a 3 d compressive strength of 24.1 MPa， a 6.3-fold improvement over the reference group， and a 28 d strength of 45.8 MPa， a 40.5% increase. TG-DTG analysis shows that the mass loss ratio in 60 to 120 ℃ range rises from 3.32% to 7.61% at 3 d， confirming markedly greater ettringite and C-（A）-S-H gel formation. Isothermal calorimetry reveals that the hydration induction period is shortened from approximately 40 h to as little as 3 h. SEM-EDS observations confirm a denser microstructure with uniformly distributed ettringite and abundant C-（A）-S-H gel filling the pore space， while high Al and Si atomic fraction of 9.25% and 7.84% （paste with 20% electrochemically activated red mud） in partially reacted red mud particles， which verifies that reactive aluminum participates in hydration. The enhancement is attributed to two synergistic mechanisms： the greatly increased reactive aluminum supply accelerates early ettringite formation， and the retained alkalinity further activates slag by promoting Si—O and Al—O bond breakage to sustain C-（A）-S-H gel growth at later ages. This work provides an effective technical pathway for red mud valorization and addresses the inherent early-strength deficiency of ESPSC systems.

Key words: red mud, excess-sulfate phosphogypsum-slag cement, electrochemical activation, performance enhancement, hydration mechanism

中图分类号:

TQ172.1

唐佩, 朱美怡, 肜鹏杰, 陈伟. 电化学活化赤泥对过硫磷石膏矿渣水泥性能的提升研究[J]. 硅酸盐通报, 2026, 45(8): 2806-2816.

TANG Pei, ZHU Meiyi, RONG Pengjie, CHEN Wei. Performance Enhancement of Excess-Sulfate Phosphogypsum-Slag Cement Through Electrochemically Activated Red Mud[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(8): 2806-2816.

图/表 13

图1 原材料的XRD谱和粒径分布

Fig.1 XRD patterns and particle size distribution of raw materials

表1 原材料的化学组成

Table 1 Chemical composition of raw materials

Material	Mass fraction/%
Material	Fe₂O₃	Al₂O₃	SiO₂	Na₂O	TiO₂	CaO	MgO	SO₃	Other	L.O.I.
Red mud	32.42	21.24	17.37	11.76	5.96	1.02	0.13	0.31	0.83	8.96
PG	0.50	0.73	7.49	0.11	0.14	33.38	0.24	44.87	2.44	10.10
GGBS	0.30	14.02	31.77	0.60	1.03	41.42	7.32	2.52	2.02	-1.00
Cement	4.73	3.41	13.23	—	0.32	71.30	1.09	2.84	0.65	2.43

表2 胶凝材料配比设计

Table 2 Mix proportion design of cementitious materials

Sample	Mass fraction/%					W/B
Sample	Untreated red mud	Treated red mud	Phosphogypsum	GGBS	Cement	W/B
REF	0	0	45	49	6	0.4
RM-2	20	0	40	34
TRM-1	0	15	40	39
TRM-2	0	20	40	34
TRM-3	0	10	45	39

图2 赤泥悬浮液的循环伏安曲线和计时电流曲线

Fig.2 Cyclic voltammetry curves and chronoamperometry curves of red mud suspension

图3 赤泥的电化学活化机理图

Fig.3 Mechanism diagram of red mud electrochemical activation

图4 电化学处理前后赤泥及分离铁组分的XRD谱

Fig. 4 XRD patterns of red mud before and after electrochemical treatment and separated iron composition

表3 矿粉和电化学处理前后赤泥滤液元素含量和pH值

Table 3 Elemental content and pH value in filtrate of GGBS and red mud before and after electrochemical treatment

Sample	Content/（mg·L^-1）				pH value
Sample	Ca	Al	Si	Fe	pH value
GGBS	92.503	2.524	14.157	0.002	11.24
RM	0.232	13.918	1.472	0.648	10.64
TRM	0.259	259.521	4.963	0.030	12.48

图5 不同龄期下试样的抗压强度

Fig.5 Compressive strength of samples at different ages

图6 不同配比试样在3和28 d龄期的XRD谱

Fig.6 XRD patterns of samples with different mix proportion at 3 and 28 d

表4 硬化浆体在不同温度段下的失重率

Table 4 Mass loss rate of hardened paste at different temperature ranges

Age/d	Sample	Mass fraction/%
Age/d	Sample	Dehydration of ettringite， C-（A）-S-H （60~120 ℃）	Dehydration of calcium sulfate dihydrate（120~180 ℃）	Dehydration of CaCO₃（650~850 ℃）
3	REF	3.32	7.84	1.29
	RM-2	6.21	6.68	2.01
	TRM-1	7.46	6.00	5.07
	TRM-2	7.61	5.89	3.45
	TRM-3	7.44	7.04	6.41
28	REF	6.76	7.74	3.89
	RM-2	7.67	6.63	3.02
	TRM-1	7.90	6.47	3.45
	TRM-2	8.52	6.44	2.58
	TRM-3	8.00	7.33	5.18

图7 不同配比试样3和28 d的TG-DTG曲线

Fig.7 TG-DTG curves of samples with different mix proportion at 3 and 28 d

图8 不同配比试样的水化放热速率和累积放热量曲线

Fig.8 Hydration exothermic rate curves and cumulative heat release curves of samples with different mix proportion

图9 不同配比试样水化28 d的SEM照片及EDS分析

Fig.9 SEM images and EDS analysis of samples with different mix proportion hydration at 28 d

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