【作者】 罗惠莉；

【导师】 黄圣生；

【作者基本信息】 中南大学 ， 矿业工程， 2012， 博士

【摘要】 利用氧化铝工业废渣——赤泥的潜在胶凝性,通过改性和添加造粒辅料和表面活性剂等,常温下转鼓造粒制备赤泥基颗粒和赤泥-磷复合颗粒,并应用于铅锌污染土壤的原位稳定化修复。这是针对赤泥资源化利用的一种有益创新。通过在实验室开展模拟污染土修复试验、矿区重金属污染土壤盆栽试验、土柱淋溶实验和土壤中磷扩散试验；采用X射线衍射微区分析、扫描电子显微镜分析、原子吸收分光光度计分析等相结合的检测方法,对制备颗粒的组成和结构、土壤理化性质、重金属的含量和形态变化、有效磷的溶释扩散进行了研究。本论文的主要研究内容和创新点如下：1.改善赤泥胶凝性能赤泥原料(RM)凝结性差,水灰比0.5时,赤泥初凝时间为]5.75h,终凝超过48h,不能满足造粒成型要求。通过外加胶凝材料,粉磨、煅烧赤泥原料,调节水灰比等手段对其胶凝性能进行改性研究。采用赤泥粉料过0.150mmm筛,添加5%水泥,5-10%石膏,水灰比0.5时,常温下可控制凝结时间2h内。2.赤泥颗粒的制备与改良比较了不同造粒设备和工艺条件下制备的赤泥颗粒的性质。通过调节外加胶凝剂用量,添加造粒辅料和表面活性剂,确定常温下转鼓造粒制备赤泥基颗粒(PL)：赤泥原料粉(<0.15mm)通过转鼓造粒机在水灰比0.5条件下进行颗粒化造粒,胶凝材料水泥和石膏分别采用5%,秸秆粉末(<0.15mm)1%,表面活性剂OP为0.1%。该转鼓造粒方式区别于混合料注水搅拌一成型硬化的胶凝过程,造粒颗粒细小分散,内部多孔,水分易散失,因此是弱化胶凝下的造粒。3.赤泥颗粒对铅锌污染土壤的修复将制备的赤泥颗粒用于模拟铅污染土壤和铅锌矿区污染土的修复试验,确定用量和施用方式。结合韭菜、水稻盆栽实验,比较在水旱两种栽种条件下的原位稳定化修复效果,并分析对土壤环境和植物生长的影响。施用赤泥原料(粉)和赤泥颗粒(PL)均能在修复初期有效减少离子交换态铅(Pb-Ⅰ)。但施用赤泥原料(粉)在修复15d后Pb-Ⅰ反而持续增多,而施用赤泥颗粒修复15d后,对Pb-Ⅰ持续钝化效果明显,其最大降幅(模拟污土中)为94.50%。施用赤泥颗粒对土壤pH的影响小：施用1%和5%,相比施用赤泥原料(粉)的土壤pH分别下降9.76%和13.63%。土壤含水率在20%～25%,施加5%PL对500mg/kg模拟铅污染土进行修复,离子交换态铅(Pb-Ⅰ)和碳酸盐态铅(Pb-Ⅱ)含量最大降幅分别为94.50%和45.95%。残渣态铅(Pb-V)含量增加48.46%。施用赤泥颗粒对矿区污染土壤修复,离子交换态铅、锌降幅最大为44.79%,100%(即未检出)。残渣态铅、锌含量最大增幅72.26%,45.54%。赤泥原料通过添加辅助剂改性成赤泥颗粒后,能使碱性物质包覆在水化产物的晶格或晶格间隙中,从而缓释OH-。这一新的赤泥修复材料不仅保留了赤泥原料较强的吸附性能,也能有效促进污染土壤中各形态重金属持续向稳定的残渣态转化。4.赤泥-磷复合颗粒的制备和修复应用在赤泥基颗粒对铅锌污土稳定化修复应用基础上,进一步添加可溶和难溶磷酸盐,制成改良赤泥-磷复合颗粒(PK和PCA)。赤泥-磷复合颗粒缓解了因赤泥而引起的土壤pH值增加,同时促进了对矿区土壤中铅锌的稳定化。施加5%含磷6.80%赤泥颗粒PK4,对铅的化学转化促进最显著,其中残渣态铅(Pb-V)增加达81.26%,有机结合态(Pb-VI),铁锰氧化态(Pb-Ⅲ),碳酸盐态(Pb-Ⅱ)分别减少78.74%,85.62%,73.46%。控制赤泥-磷复合颗粒中可溶性磷含量1.70%,可保证植株正常生长并能有效抑制韭菜对铅的吸收,抑制率高达86.88%。土柱淋溶实验中,添加可溶磷在早期磷淋出量最高,为25.89mg/L。而添加颗粒PK4的试验组中5-20d内水溶磷持续释放优势明显,高出添加可溶磷处理下23.34%。实验结果表明赤泥-磷复合颗粒不仅能修复重金属污染土壤,又能缓释磷,持续提供有效磷素。本研究为赤泥在土壤修复和农业生产应用方而进行了积极有益的探索,提供新的资源化利用思路。更多还原

【Abstract】 Red mud is the waste from aluminium industries. Based on its potential hydration, a modified red mud granule and red mud-phosphate compound particle were made through rotary drum granulation under normal temperature with adding admixtures and surfactants. These granules were applied in the remediation of Pb-Zn polluted soil. It is an innovative approach to utilization of red mud for remediation.Remediation of artificial polluted soil and mine soil, experiments of leaving and expansion of phosphoric in soil column were conducted. The compositions and microstructures of particles, chemical-physical prosperities of soils, content and changes of phases of metals, leaving and expansion of phosphoric were determined and characterized by XRD, SEM-EDS,ABS.Main conclusions in this study are obtained as follows:1. Modification of the gelling property of red mudThe gelling property of raw red mud (RM) is poor as the initial set time was15.75h and the final set time exceeded48h under water/powder ratio of0.5. So, modification was processed by adding cements, milling and calcination, adjust water/powder ratio. The conditions and compositions of the final set time within2h were red mud powder below0.150mm,5%cement,5-10%gypsum, water/powder ratio of0.5.2. Preparation and modification of red mud granulesProperties of red mud granules manufactured by different granular under different conditions were compared. Rotary drum granulation was distinct from moisture measuring, mixing and molding. Because of the water was easy to dismiss from the small and separate granules, it was a weak gelling through rotary drum granulation. The optimum technological condition of red mud based granule PL was determined as RM (<0.150mm),5%cement,5%gypsum,1%rice straw (<0.150mm), surfactant OP of0.1%through rotary drum granulator.3. Remediation of Pb-Zn polluted soil using red mud granulePL was applied in the rremediation of artificial polluted soil and mine soil to determine the optimum amount and application mode. The effect of using red mud granules were studied in the in situ remediation with leeks and rice used in the pot experiments. And the influence on soil and growth of plants were analysis.Both of RM and PL could decrease the ion exchangeable Pb (Pb-Ⅰ). Comparing to increase of Pb-I after15d, continue notable stabilization was occurred. On soil pH, the increase by using PL was less influential. Compare to RM, the decrease rate was9.76%(adding1%) and13.63%(adding5%).When the soil moisture was maintained20%-25%, the largest decrease rate of Pb-I and Pb-Ⅱ was94.50%and45.95%with5%PL adding into the artificial polluted soil, while the increase of residual Pb was48.46%. The decrease of ionic Pb and Zn was44.79%and100%in the remediation of mine soil. And the increase of residual Pb and Zn was72.26%and45.54%.The advantage of this modified red mud granule was that alkali could be coated in the structure of hydration crystal to dilate the release of OH". So it not only persist the absorption prosperity of re mud but also purse the transformation of phases.4. Preparation of red mud-phosphate composite granule and its applicationOn the base of the application of PL, red mud-phosphate composite granule (signed as PK and PCA) was manufactured by adding soluble and dissoluble phosphate. A further relief of the increase of soil pH was obtained by using these granules to substitute red mud powder.When adding5%composite granule PK4(containing6.80%phosphoric), the transformation of phases was significant that the largest increase rate of residual Pb was81.26%and the decrease of carbonate, iron-manganese oxide and organic phase were78.74%,85.62%,73.46%. With1.70%phosphoric in PK2, the absorption of lead was effectively restrained by68.05%in the case of plants vegetated well.In the leaching experiment, the content of soluble-phosphoric after passing through soil column was the largest as25.89mg/L by adding soluble phosphate in the initial stage. But during5-20d, the release of water soluble phosphoric was in a higher level with adding PK4than adding soluble phosphate, ranging23.34%. Experiment results showed that red mud-phosphate composite granule can stabilize the metals and at the same time relieve the release of phosphoric. This study has tentatively probed in the usage of red mud in remediation of soil and agricultural production. It may provide an idea for future utilization of red mud.更多还原