A Preliminary Study On Low Temperature Pyrolysis Of Mercury Contaminated Soil By Additives

The main research area of this thesis is farmland high mercury pollution in Guizhou province Qingzhen area 。The high concentration of mercury pollution in the area,although the effect of pyrolysis technology is better,but when the temperature is too high（600⁸00 ℃）,not only the repair cost is high,the waste of energy,it will bring great harm to the physical and chemical properties of soil itself.Using low temperature pyrolysis（less than 500 ℃）of the a certain areas of mercury contaminated soil,the concentration of mercury in soil can effectively reduce the residual mercury in the soil,but is still very high,so based on low temperature pyrolysis technology,by adding additives to improve the removal rate of soil mercury in soil.In this paper,FeCl₂,FeCl₃,KI and Citric acid were used as soil additives:（1）The concentration of mercury in soil can be reduced during the low temperature pyrolysis.When the pyrolysis temperature is less than 350 ℃,the additive effect is obvious;（2）The soil with FeCl₂ and FeCl₃ are suitable for 5:1,when the pyrolysis temperature of 350℃,the pyrolysis time of one hour,the treatment effect is improved by more than 75%,the higher the temperature,the better the effect;（3）Add KI of the soil,the pyrolysis temperature ≥400℃,have stimulative effect,when the pyrolysis temperature is 450 ℃,the lowest concentration of added KI residues of mercury in soil（4）Adding Citric acid and soil 1:5 ratio for the best effect,the pyrolysis temperature ≥350℃,the real way to citric acid wet mixed reagent is soluble in water,and soil mixing way（5）With the addition of the four kinds of additives,the residual state and organic binding state of mercury in con-taminated soil were transformed to other forms,and the stability of mercury in soil was reduced.