镁渣填充材料的制备及其性能研究

发布时间：2018-07-27 17:32

【摘要】：连续数年的煤炭开采使得留下了数量惊人的采空区,为防止地表沉陷,确保人民生命财产安全,需要对煤矿采空区进行充填。冶炼金属镁需消耗大量的能源,所以金属镁工厂大都建在煤炭基地附近,而镁渣是金属镁冶炼过程中产生的废渣,一般都是将其做堆放或填埋处理,这样不仅占用土地,还引起环境污染,本文提出利用镁渣制备低成本的填充材料来填充煤矿采空区。以镁渣为主要原料,针对不同区域的采空区,制备了不同性能的两种充填体,用于不同的采空区。并通过物理性能检测,膨胀量测量,XRD,SEM等方法对充填体的物化性能进行研究后,得出了充填体的最佳配比。同时,试制了一种发泡剂来制备能满足一般回填区要求的泡沫混凝土充填材料。通过对以上实验数据分析得出以下结论:(1)制备的高强度镁渣充填体的抗压、抗折强度均随着镁渣掺量的增加而降低。通过对充填体的SEM图像分析其水化产物C-S-H和Ca(OH)2含量随镁渣的掺量增多而减少。镁渣充填体的配比为镁渣含量50%,粉煤灰含量10%,水泥含量40%,3d抗压强度为21MPa,28d抗压强度为42MPa。该配比镁渣填充体养护至200d后,其膨胀率为0.44%,具有微膨胀性。(2)低强度镁渣充填体的水胶比较小,配制的浆体流动度较差,掺入适量的粉煤灰可以提高浆体的流动度,但随着粉煤灰掺量的加大,充填体的抗压强度逐渐降低。水胶比影响填充体的凝结时间。综合比较各因素对填充体性能指标的影响,得出最优方案为水泥掺量10%,灰渣比为1:1.4,水胶比为0.32。在该配比下,浆体流动度为19.8cm,凝结时间为17.5h,充填体28d抗压强度为16.19MPa。(3)采用十二烷基硫酸钠(K12)和硬脂酸钙,制备了一种复合型发泡剂,发泡性能为发泡倍数28,1h沉陷距为1mm,1h泌水量为8ml。利用该复合型发泡剂制备泡沫混凝土,在水泥掺量10%,灰渣比为1:1.4,水胶比为0.32,泡沫掺量为0.5m~3/m~3时,制备的不同湿密度泡沫混凝土的干密度约为湿密度的一半,且28d抗压强度与干密度的增长规律符合幂函数关系。在泡沫混凝土试块SEM图像中可以看出湿密度较大时孔径细小且粗细均匀,均为独立封闭的小孔,当湿密度减小时,孔径明显增大,泡孔不均匀,存在连通孔。从泡沫混凝土试块孔径微分分布曲线上可以看出湿密度为1700kg/m~3的试块孔隙分布主要集中在100~550nm,而湿密度为1400~1600kg/m~3的试块孔隙分布主要集中在200~3000nm。泡沫混凝土试块的抗压强度总体上随着孔隙率和平均孔径的增大而降低,大孔孔隙率对抗压强度的影响更为重要。
[Abstract]:In order to prevent the surface subsidence and ensure the safety of people's life and property, the goaf of coal mine needs to be filled in order to prevent the surface subsidence and ensure the safety of people's life and property. Smelting metal magnesium needs a lot of energy, so most of the metal magnesium factories are built near coal bases, and magnesium slag is the waste slag produced in the process of smelting magnesium metal, which is usually stacked or landfill, so it not only occupies the land. It also causes environmental pollution. In this paper, using magnesium slag to prepare low cost filling material is proposed to fill the goaf of coal mine. Two kinds of filling bodies with different properties were prepared for different goaf with magnesium slag as main raw material. The physical and chemical properties of the backfill were studied by means of physical property test, expansion measurement and XRDX SEM, and the optimum proportion of the backfill was obtained. At the same time, a foaming agent was developed to prepare foam concrete filling material which can meet the general backfill requirements. The conclusions are as follows: (1) the compressive strength and flexural strength of the high strength magnesium slag fillers are decreased with the increase of the content of magnesium slag. The content of C-S-H and Ca (OH) _ 2 decreased with the increase of mg _ (2) slag content in the SEM images of the filling body. The proportion of magnesium slag filling body is 50 mg slag content, the content of fly ash is 10%, the compressive strength of cement content 40 days is 21 MPA / 28 d, the compressive strength is 42 MPA / a. After curing for 200 days, the swelling ratio of the mixture is 0.44, which has the property of micro-expansion. (2) the water glue of the low strength magnesium slag filling body is smaller, the fluidity of the prepared slurry is poor, and the fluidity of the slurry can be improved by adding proper amount of fly ash. However, with the increase of fly ash content, the compressive strength of the filling body decreases gradually. The water / binder ratio affects the setting time of the filler. By comparing the effects of various factors on the performance of the filler, it is concluded that the optimum scheme is the cement content of 10%, the ratio of ash to slag of 1: 1.4, and the ratio of water to binder of 0.32. Under this ratio, the fluidity of the slurry was 19.8cm, the setting time was 17.5 h, the compressive strength of the filling body was 16.19MPa. (3) A compound foaming agent was prepared by using sodium dodecyl sulfate (K12) and calcium stearate. The foamed concrete was prepared by using the compound foaming agent. The dry density of the foamed concrete with different wet density was about half of the wet density when the cement content was 10%, the ratio of ash to slag was 1: 1.4, the ratio of water to binder was 0.32, and the content of foam was 0.5 mg / m ~ 3. The growth law of 28d compressive strength and dry density is in accordance with the power function. It can be seen from SEM images of foam concrete samples that the pore diameter is fine and even with high wet density, and they are all independent closed pores. When the wet density decreases, the pore diameter increases obviously, the bubble pore is not uniform, and there are connected pores. From the pore size differential distribution curve of foamed concrete, it can be seen that the pore distribution of the sample with wet density of 1700kg/m~3 is mainly concentrated at 100 ~ 550nm, while the pore distribution of sample with wet density of 1400~1600kg/m~3 is mainly concentrated at 200 ~ 3000nm. The compressive strength of foam concrete samples decreases with the increase of porosity and average pore size, and the influence of macropore porosity on compressive strength is more important.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD823.7;X758

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