钢渣不同矿物的加速碳化

钢渣不同矿物的加速碳化

房延凤，张婷婷，常  钧^*

(大连理工大学土木工程学院，辽宁 大连 116024)

摘要：钢渣中较高的氧化钙含量赋予其较好的碳化能力。本文用QXRD（quantitatively X - ray diffraction analysis）分析了钢渣的主要矿相，并合成了β-C₂S，γ-C₂S，镁蔷薇辉石(Ca₃Mg(SiO₄)₂)，尖晶石(Ca₄Si₂O₇F₂)，黑钙铁矿(Ca₂Fe₂O₅)，钙铁石(Ca₄Al₂OFe₂O₁₀)等矿物。将各矿物在8MPa下压制成型制成20mm×20mm×20mm的立方体，在99.9% CO₂，0.2MPa 压力下加速碳化2 h。通过QXRD，TGA（thermogravimetric analysis），FT-IR(Fourier transform infrared spectrometer)和SEM(scanning electron microscope)对碳酸产物进行分析。结果表明，氢氧化钙吸收二氧化碳的量最大；γ-C₂S，β-C₂S，镁黄长石，镁蔷薇辉石和尖晶石固碳量逐渐减少。抗压强度与固碳量并不呈正相关关系，因此提出了不同矿物碳化的比强度(K)来表征单位质量CO₂提供的抗压强度。 β-C₂S 的K值最大，氢氧化钙K值最小。钢渣吸收的CO₂量，抗压强度和K值都介于单矿物之间。除了γ-C₂S和镁黄长石分别存在少量的球霰石和文石，所有单矿和钢渣碳化的产物为方解石。用QXRD和TG（thermogravimetric analysis）的方法对碳酸钙进行定量分析，QXRD所得结果稍小，可能是由于碳化产物中存在少量非晶相碳酸钙。不同矿物碳化后方解石的颗粒尺寸，形貌均不同，这也对抗压强度影响。

关键词:钢渣；矿物；加速碳化；比强度；QXRD

中图分类号：TF7；TU528；TU502；TG115.21⁺5.3     文献标识码：A     doi:10.3969/j.issn.1000-6281.2015.06.003

 Accelerated carbonation of different minerals of steel slag

FANG Yan-feng, ZHANG Ting-ting, CHANG Jun^*

(School of Civil Engineering, Dalian University of Technology, Dalian Liaoning 116024, China)

Abstract: The high calcium content makes steel slag an excellent candidate industry waste for mineral carbonation. Minerals of steel slag were analyzed by QXRD. The main minerals, i.e., β-C₂S, γ-C₂S, merwinite (Ca₃Mg(SiO₄)₂), cuspidine (Ca₄Si₂O₇F₂), srebrodolskite (Ca₂Fe₂O₅), brownmillerite (Ca₄Al₂OFe₂O₁₀) were synthesized. The minerals (water/solid ratio is 0.1) were compacted at 8 MPa to 20mm×20mm×20mmand then were carbonated in a sealed chamber (CO₂ pressure is 0.2MPa) for 2h. The carbonated products were analyzed by QXRD, TGA, FT-IR and SEM. The results indicate that portlandite absorb the greatest amountof CO₂ and the carbon sequestration of γ-C₂S, β-C₂S, akermanite, merwinite and cuspidine gradually decrease. But compressive strength don’t show positive correlationwithCarbon sequestration capacity. Compressive strength to CO₂ uptake(K) values of different minerals are defined. β-C₂S presents the greatest K value and portlandite show the least K value. The CO₂ uptake, compressive strength and K value of steel slag are all between the minimum and maximum valuesof synthetic minerals. Calcite exists in all the carbonated minerals and steel slag. Small amount of vaterite and aragonite exist in carbonated γ-C₂S and akermanite, respectively. Calcium carbonate from QXRD analysis is less than that from TG analysis. Calcite with different morphologies and different crystal sizes formed, which also have influence on compressive strength.

Keywords:steel slag；synthetic minerals, accelerated carbonation；Compressive strength to CO₂ uptake value；QXRD

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