矿渣-粉煤灰-磷石膏基骨料制备参数及性能

Preparation Parameters and Properties of Slag-Fly Ash-Phosphogypsum Based Aggregate

研究了不同制备参数、改善药剂对矿渣-粉煤灰-磷石膏基人造骨料性能的影响,分析了骨料性能增强及污染物释放规律。结果表明,相同体积下,骨料最终密度与挤压压力成正相关,挤压造粒较优参数为:挤压压力为85 MPa,水固比为0.09~0.11。相比常规圆盘造粒制备骨料工艺,挤压造粒的人造骨料粒度分布均匀,密实度高,吸水率低,长期强度稳定,适用于制备高强骨料。骨料抗硫酸盐质量损失率低于12%,冻融循环质量损失率均小于8%,经改善药剂处理后,抗盐侵蚀能力强化,冻融后针片状颗粒含量和质量损失大幅降低。骨料经过长期浸泡,氟和磷浸出均呈现初期快速浸出,后期浸出放缓的规律。浸泡至90 d,水环境中氟与磷最高质量浓度均低于GB 8978—1996《污水综合排放标准》一级标准限值,骨料经改善药剂处理后磷和氟的浸出有效减少。

In this paper,the effects of different preparation parameters and improvement agents on the properties of slag-fly ash-phosphogypsum based artificial aggregate were studied,and the law of enhancing the properties of aggregate and pollutant release was analyzed.The results showed that the final density of aggregate was positively correlated with the extrusion pressure at a given volume.The optimal parameters for extrusion granulation were extrusion pressure of 85 MPa and water-solid ratio of 0.09-0.11.Compared with that by conventional disk granulation process,the artificial aggregate by extruded granulation had distribution of uniform particle size,high compactness,low water absorption and long-term stable strength,which was suitable for the preparation of high-strength aggregate.The quality loss rate of sulfate resistance of aggregate and quality loss rate of freeze-thaw cycle was less than 12% and 8%,respectively.The salt erosion resistance was obviously intensified after treatment with improved agent,the content and quality loss of needle flake particles were greatly reduced after freeze-thaw.After long-term immersion,fluorine and phosphorus leached rapidly at the initial stage and slowed down subsequently.After soaking for 90 d,the highest concentrations of fluorine and phosphorus in the water environment were lower than the primary standard limit of GB 8978—1996"Integrated wastewater discharge standard",and the leaching of phosphorus and fluorine was effectively reduced by the treatment with improved agent.