| Since the new century,China's economy has developed rapidly,and the green and new economic development model has gradually replaced the crude economic development model.However,a series of environmental pollution problems have emerged in the process of economic restructuring.The problem of site pollution is particularly serious.The management,investigation and repair of site pollution in China are still in the initial stage,and there is no relevant management system and experience in repairing technology.Therefore,it is of great significance to study the treatment and disposal of contaminated soil in the site.In this study,the heavy metal contaminated site soil was proposed and a high-temperature curing method was proposed to stabilize the heavy metals in the soil,ie to solve the problem of heavy metal pollution in the contaminated site,and then it can be reprocessed into a valuable product.Four kinds of heavy metal elements such as Cd,Pb,Cu,and Zn were selected to simulate heavy metals contaminated soils by introducing heavy metals from outside,and clay and glass powder were selected as additives to cure and reuse the contaminated soil.Through the orthogonal test method,the best sintering formula was obtained,and then its mechanical properties were measured.Then the effect of the sintering temperature and sintering time on the stability of the heavy metal was analyzed by the heavy metal solid solution rate and the heavy metal leaching concentration.The comprehensive benefits of reusing high-temperature solidified soil in a heavy metal-contaminated site were analyzed.Research indicates:The leaching concentrations of heavy metal in soils were Cd(0.4545mg·L-1),Pb(6.3817mg·L-1),Cu(0.9255mg·L-1)and Zn(24.9667mg·L-1),serious pollution.The optimum sintering formula obtained by orthogonal experiment was 62.5%of contaminated soil,25%of clay and 12.5%of glass frit.The final sintering temperature was 950?.Polluted soil,clay and glass powder are mixed into a green body at a ratio of 5:2:1.After being stored at room temperature for 24hours,the soil is dried at 105?,and the water content of the brick is reduced to3%-5%.It was then placed in a muffle furnace,sintered at 300?,550?,750?and 950?for 1 h,then cooled naturally to room temperature with the oven temperature.The leaching concentrations of heavy metals in the brick body were as follows:Cd(0.0006mg·L-1),Pb(0.0041mg·L-1),Cu(0.0.0030mg·L-1)),Zn(0.0046mg·L-1).Is a non-hazardous materials,can be used directly.The research on firing temperature and time shows that when the firing temperature is 950?and The best sintering environment can be achieved,and the stability of heavy metals in the brick body is good.The mechanical properties of sintered brick were tested.The bulk density of brick was between 1.8and 2.1g·cm-3,the average water absorption was 11.4%and the saturation coefficient was 0.53,A slight frost phenomenon,compressive strength rating of MU10,antifreeze good acid and alkali.From the aspect of the availability of brick body after firing,the high temperature solidified brick made of contaminated soil in heavy metal field has good economy and is an effective way of treatment and utilization,and has environmental and social benefits. |
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