螯合处理对钢渣体积安定性的改善

摘要：钢渣中存在的游离氧化钙(f-CaO)会与水反应生成氢氧化钙（Ca2(OH)2），造成体积膨胀，使得钢渣的利用变得困难。通过配制草酸与柠檬酸钠螯合剂消除游离氧化钙。探讨钢渣水化规律和吸水率，确定最佳螯合时间和螯合浓度。利用XRD、TG、SEM分析钢渣矿物成分、游离氧化钙含量及微观形貌变化；对比处理前后钢渣膨胀率、黏附性和压碎值等物理指标。结果表明：草酸和柠檬酸钠螯合剂最佳螯合时间分别为84、108h，最佳螯合浓度分别为0.4、0.2mol/L，均对钢渣膨胀性有所抑制，尤其是草酸螯合剂，游离氧化钙消除率达到52%，钢渣膨胀率下降51%。螯合处理后钢渣断面部分物质发生水化反应，表面分别形成大量草酸钙(CaC2O4)和柠檬酸钙(C12H10Ca3O14)络合物，发生沉淀转化，改善了钢渣集料的物理特性。

Improvement of volume stability of steel slag by chelating treatment

Abstract：The free calcium oxide (f-CaO) in steel slag will react with water to form calcium hydroxide (Ca(OH)2), which will cause volume expansion, making the utilization of steel slag difficult. The f-CaO was eliminated by preparing oxalic acid and sodium citrate chelating agent. The hydration law and water absorption rate of steel slag were discussed, and the best chelating time and concentration were determined. XRD, TG and SEM were used to analyze the mineral composition, f-CaO content and micro-morphology of steel slag. Physical indexes such as expansion rate, adhesion and crushing value of steel slag before and after treatment were compared. The results show that the best chelating time of oxalic acid and sodium citrate chelating agent is 84 and 108h, and the best chelating concentration is 0.4 and 0.2mol/L, respectively. Both of them can inhibit the expansively of steel slag, especially oxalic acid chelating agent. The elimination rate of f-CaO is 52%, and the expansion rate of steel slag decreases by 51%. After chelation treatment, some substances in the steel slag section undergo hydration reaction, and large amounts of calcium oxalate (CaC2O4) and calcium citrate (C12H10Ca3O14) complexes are formed on the surface, respectively, which precipitate and transform, thus improving the physical properties of steel slag aggregate.