铅锌冶炼渣制备微晶玻璃和地质聚合物及其铅镉固化机理

发布时间：2018-06-17 01:27

本文选题：铅锌冶炼渣 + 烟化渣　；参考：《北京科技大学》2018年博士论文

【摘要】：铅冶炼烟化渣和锌冶炼挥发窑渣分别是原生铅和锌冶炼过程中的两种产量大、处理困难的重金属危固。这两种冶炼渣已被列入《国家危险废物名录》。固化后安全填埋,目前是这两种渣的唯一处置途径,但安全填埋的成本很高,填埋后还需长期监测。因此,开发新的再利用方法,解决铅锌冶炼渣的处理问题极为必要。烟化渣和挥发窑渣的成分相似,其中Ca、Si、A1和Fe等无害元素总量很高,Pb、Cd等有害重金属元素的含量很低,但有溶出风险。铅锌冶炼渣的二次利用的难点在于渣中的有害重金属元素的固定/稳定化(简称固化)和无害元素的合理利用。通过文献调研发现,微晶玻璃固化法和地质聚合物固化法具备同时解决这两个问题的潜力。铅锌冶炼渣中Ca、Si和A1的含量较高,具备制备微晶玻璃和地质聚合物的成分条件,微晶玻璃和地质聚合物都有较为广泛的应用前景。通过文献调研发现,目前还没有文献系统对比过两种固化方法的优缺点。因此,本研究开发了铅锌冶炼渣制备微晶玻璃和地质聚合物的工艺方法,较为系统的阐明了冶炼渣中的超标元素Pb和Cd在微晶玻璃及地质聚合物中的固化机理。本研究通过对微晶玻璃的成分配方和热处理制度的优化,发现铅锌冶炼渣适合制备普通辉石微晶玻璃。适宜的热处理制度为:一步法热处理,850℃条件下保温2h。烟化渣制备微晶玻璃的配方为:烟化渣46wt%,粉煤灰46wt%,不锈钢渣8wt%。优化后的烟化渣微晶玻璃的抗弯强度、耐酸度和耐碱度分别为146.26MPa,≥99%和≥99%,均高于JC/工2097-2011《工业用微晶板材》行业标准规定的抗弯强度≥70MPa,耐酸度≥96%和耐碱度≥98%的要求。该微晶玻璃的Pb和Cd的浸出浓度分别为1.342mg·L-1和0.021mg·L-1,均低于工CLP(Toxicity Characteristic Leaching Procedure)浸出毒性标准规定的 Pb≤5mg·L-1,Cd≤1mg·L-1的要求。挥发窑渣制备微晶玻璃的配方为:挥发窑渣36wt%,粉煤灰52wt%,不锈钢渣12wt%。该微晶玻璃的抗弯强度、耐酸度和耐碱度分别为128.31MPa、≥99%和≥99%,Pb和Cd的浸出浓度分别为1.087mg·L-1和0.032mg·L-1,各项指标同样能达到上述标准的要求。通过对地质聚合物的原料配比和养护制度的优化,发现烟化渣和挥发窑渣都可与粉煤灰配合制备地质聚合物。地质聚合物能有效固化两种废渣中的重金属。烟化渣和挥发窑渣制备的地质聚合物的7d抗压强度分别可达82.81MPa和60.39MPa。本研究在开发出铅锌冶炼渣制备微晶玻璃和地质聚合物工艺方法的基础上,进一步探究了浸毒性超标元素Pb和Cd的固化机理。本研究以PbO和CdO等物质模拟了冶炼渣中的重金属污染物,研究了 Pb和Cd在微晶玻璃和地质聚合物中的固化形态。微晶玻璃中Pb的可固化量约为2wt%,当微晶玻璃中的Pb含量低于该值时,Pb在微晶玻璃固化体中同时进入残余玻璃相和普通辉石微晶相。Pb通过替代价态相同半径接近的Ca,进入普通辉石微晶相中,形成置换型固溶体。Cd在残余玻璃相中的溶解度可能较低。微晶玻璃中Cd的可固化量约为1wt%,当微晶玻璃中的Cd含量低于该值时,大部分Cd同样通过替代价态相同半径接近的Ca,进入微晶相中,形成置换型固溶体。Pb在地质聚合物中的固化机理与Pb的化学形态有关。碱性可溶含Pb污染物能参与地质聚合反应,通过形成Pb-O-Si或Pb-O-Al键进入到地质聚合物胶凝相中。地质聚合物对这类含Pb污染物既能起到物理包覆的作用,又能起到化学稳定化的作用。碱性不可溶Pb不参与地质聚合反应,地质聚合物对该类污染物仅能起到物理包覆的作用。CdO在碱性溶液中不发生溶解,缺乏参与形成地质聚合物的先决条件。地质聚合物对CdO仅能起到物理包覆的作用。对比PbO与CdO在微晶玻璃和地质聚合物中的固化效果,发现:微晶玻璃对PbO的固化效果接近地质聚合物对PbO的固化效果,PbO在两种固化材料中的可固化量约为2wt%。微晶玻璃中CdO的可固化量约为1wt%,由于地质聚合物对CdO仅能起到物理包覆的作用,地质聚合物中CdO的可固化量远低于微晶玻璃。微晶玻璃更适合处理CdO含量较高的危废。
[Abstract]:Smelting slag of lead smelting and smelting slag from zinc smelting are two kinds of heavy metals in primary lead and zinc smelting process, which are difficult to deal with. These two kinds of slag have been listed in the national hazardous waste list >. After solidifying, safe landfill is the only disposal path of these two kinds of slag, but the cost of safety landfill is very high, and it is still needed after landfill. Therefore, it is very necessary to develop a new reutilization method to solve the problem of treatment of lead and zinc smelting slag. The composition of the slag and the volatile kiln slag is similar. The total amount of harmless elements, such as Ca, Si, A1 and Fe, is very high, and the content of Pb, Cd and other harmful heavy metals is very low, but it has the risk of dissolution. The difficulty of the two utilization of lead and zinc smelting slag lies in the slag. It is found that microcrystalline glass solidification and Geopolymer solidification have the potential to solve these two problems at the same time. The content of Ca, Si and A1 in lead-zinc smelting slag is higher, with the composition of the preparation of microcrystalline glass and geopolymer. Conditions, glass ceramics and geopolymers have wide application prospects. Through literature investigation, it is found that there are no advantages and disadvantages of two kinds of curing methods compared with the literature system. Therefore, this study developed the process method of making glass ceramics and geopolymers from lead-zinc smelting slag, and systematically clarified the excess of smelting slag. The curing mechanism of the standard elements Pb and Cd in microcrystalline glass and geological polymers is found. By optimizing the composition and heat treatment system of the glass ceramics, it is found that the lead and zinc smelting slag is suitable for the preparation of ordinary pyroxene glass ceramics. The suitable heat treatment system is the one-step heat treatment and the preparation of 2h. glass ceramics at 850 degrees centigrade to prepare the glass ceramics. The formula is: the flexural strength of smoke chemical slag 46wt%, fly ash 46wt%, stainless steel slag 8wt%. optimized by 8wt%., the acid resistance and alkali resistance are 146.26MPa, > 99% and > 99% respectively, which are higher than that of JC/ workers in 2097-2011< industrial microcrystal plate > industry standard, with the bending strength of more than 70MPa, acid resistance more than 96% and alkali resistance of 98%. The leaching concentration of Pb and Cd in this glass ceramics is 1.342mg. L-1 and 0.021mg. L-1 respectively, which are lower than that of industrial CLP (Toxicity Characteristic Leaching Procedure). The flexural strength of glass ceramics, acid resistance and alkali resistance are 128.31MPa, > 99% and > 99% respectively. The leaching concentration of Pb and Cd are 1.087mg. L-1 and 0.032mg L-1 respectively. Each index can meet the requirements of the above standard. Through the optimization of the raw material ratio and curing system of geopolymer, it is found that both the slag and the volatilization kiln slag can be used with powder. The geological polymer can effectively solidify the heavy metals in the two kinds of waste residue. The 7d compressive strength of the geological polymers prepared by the slag and the volatilization kiln slag can be 82.81MPa and 60.39MPa., respectively, on the basis of the development of the technology for the preparation of the microcrystalline glass and the geological polymer by the development of the lead and zinc smelting slag. The curing mechanism of Pb and Cd was investigated. The heavy metal pollutants in the slag were simulated by PbO and CdO, and the curing forms of Pb and Cd in glass ceramics and Geopolymer were studied. The curable amount of Pb in the glass ceramics was about 2wt%. When the Pb content in the glass ceramics was lower than that, the Pb was in the glass ceramics. The residual glass phase and the common pyroxene microcrystalline phase.Pb are entered into the ordinary pyroxene microcrystalline phase by replacing the Ca of the common pyroxene microcrystalline phase at the same time. The dissolubility of the permutation solid solution.Cd in the residual glass phase may be lower. The curable amount of Cd in the glass ceramics is about 1wt%, when the Cd content in the glass ceramics is lower than that of this value. Most Cd also enters the microcrystalline phase by replacing the Ca with the same radius of the same radius. The solidification mechanism of the displacement solid solution.Pb in the geological polymer is related to the chemical form of the Pb. The alkaline soluble Pb contaminants can participate in the geological polymerization and enter into the geopolymer gelation phase by forming the Pb-O-Si or Pb-O-Al bonds. The polymer has the effect of both physical coating and chemical stabilization on this kind of Pb containing pollutants. The alkaline insoluble Pb does not participate in the geological polymerization. The geological polymer can only play a physical coating on this kind of pollutants..CdO does not dissolve in the alkaline solution and lacks a prerequisite for the formation of Geopolymer. Geopolymer can only act as a physical coating on CdO. Comparing the curing effect of PbO and CdO in microcrystalline glass and geopolymer, it is found that the curing effect of glass ceramics to PbO is close to the curing effect of geopolymer on PbO. The curing amount of PbO in the two kinds of solidified materials is about the curable amount of CdO in 2wt%. glass glass. For 1wt%, because geopolymer can only act as a physical coating to CdO, the curable amount of CdO in geopolymer is much lower than that of glass ceramics. The glass ceramics are more suitable for treating the hazardous waste with higher CdO content.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2018
【分类号】：TQ171.733

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