Abstract:

MgO-containing calcium aluminate clinkers doped with Na₂SO₄ were synthesized using analytical grade reagents of MgO, CaCO₃, SiO₂, Al₂O₃, and Na₂SO₄ at 1350℃ for 1 h.The clinkers were studied for leaching performance in sodium carbonate solution, and for crystal structure and self-disintegrating performance by XRD and SEM.Doping Na₂SO₄ improved leaching performance of clinkers.When Na₂SO₄ content was raised from 0% to 4%, Al₂O₃ leaching ratio of clinkers increased from 61.89% to 92.01%.The leaching tended to be stabilized with further increase of Na₂SO₄ dopant.XRD results showed that doping Na₂SO₄ caused phase transformation from 20CaO·13Al₂O₃·3MgO·3SiO₂(Q-phase) to 12CaO·7Al₂O₃(C₁₂A₇).Na⁺ intrusion into C₁₂A₇ lattice forced lattice distortion, which probably promoted Al₂O₃ leaching.Na₂SO₄ dopant also deteriorated self-disintegration of clinkers.When Na₂SO₄ content increased from 0% to 6%, self-disintegrating ratio decreased from 97.46% to 85.34%, respectively.It further decreased to 36.3% for clinker with 10% Na₂SO₄ dopant.

Key words: calcium aluminate, sintering, alumina leaching, Q-phase, Na₂SO₄ doping

摘要：

使用分析纯MgO、CaCO₃、SiO₂、Al₂O₃与Na₂SO₄在1350℃保温1 h合成了掺杂Na₂SO₄的含MgO铝酸钙熟料，在Na₂CO₃溶液体系下研究了其氧化铝浸出性能，通过XRD等分析手段对其晶体结构和自粉化性能进行了研究。结果表明，Na₂SO₄可以显著提升铝酸钙熟料的浸出性能，Na₂SO₄掺杂量由0%提高到4%，熟料的氧化铝浸出率由61.89%提高到92.01%，继续添加Na₂SO₄，浸出性能趋于稳定。由XRD结果可知，Na₂SO₄促使20CaO·13Al₂O₃·3MgO·3SiO₂（Q相）发生分解并使其转变为12CaO·7Al₂O₃（C₁₂A₇）。Na⁺进入C₁₂A₇晶格引起晶格畸变，从而提高C₁₂A₇的氧化铝浸出性能。Na₂SO₄的加入降低了熟料的自粉化性能，Na₂SO₄掺杂量由0%提高到6%，熟料的自粉率由97.46%下降到85.34%，当Na₂SO₄掺杂量达到10%后，熟料自粉率仅为36.3%。

关键词: 铝酸钙, 烧结, 氧化铝浸出, Q相, Na₂SO₄掺杂