Ca(OH)_2对污泥焚烧灰渣中Pb含量的影响

Influence on Pb in the ash by Ca(OH)_2 in the process of industrial sludge incineration

将添加有Ca(OH)_2的污泥在管式炉中焚烧,通过原子吸收分光光度计(AAS)测定灰渣中Pb的含量,分析Ca(OH)_2对灰渣中Pb含量的影响。结果表明:在污泥焚烧过程中,Pb的挥发率随焚烧温度呈先上升后下降再上升趋势,结合X射线衍射(XRD)分析发现,这主要是由于硅铝酸盐对Pb的固留作用和挥发动力学的相互影响。添加Ca(OH)_2后,污泥灰渣中Pb的含量有明显的降低,而且随着Ca(OH)_2添加量的增加,污泥灰渣中Pb的含量持续降低,表明Ca(OH)_2的添加,促进Pb的挥发,减少Pb在灰渣中的含量。将灰渣中Pb的形态分为浸出态和残渣态,通过分析X射线衍射(XRD)和灰渣中两种形态Pb的变化规律,得到Ca(OH)_2促进Pb挥发的机理主要是:添加的钙元素与硅铝酸盐反应,降低了硅铝酸盐与Pb反应的概率,从而使Pb转变为挥发形态的可能性增大,因此提高了挥发率。

The influence on Pb in the ash by Ca(OH)2 added was studied during sludge incineration in tubular furnace. Atomic absorption spectrometer(AAS) was used to detect the distribution of Pb in the ash. The experiment showed that the volatilization rate of Pb increased initially, then decreased and then increased with the working temperature increasing. The X-ray diffraction(XRD) results of sludge showed that the retention effect of aluminosilicate on Pb and volatilization kinetics lead to the trend. After Ca(OH)2 added, the retention of Pb in sludge ash decreased obviously, which indicated that the addition of Ca(OH)2 could promote the volatilization of Pb. Moreover, the more Ca(OH)2 added, the less retention of Pb was. The morphology of Pb in ash was divided into leaching state and residual state. The main mechanism is that the reaction between calcium and aluminosilicate reduces the probability of aluminosilicate reaction with Pb by analyzing the results of X ray diffraction (XRD) of sludge added Ca(OH)2 and the content of two forms of Pb.