Crystallization and Strength of the Molten Slag on Sewage Sludge Melting Process

在熔化过程中，污泥在1300~1500ﾟC的高温范围内熔化，超过了污泥无机物的倾注点，渣中重金属的大体积减量和稳定化有望大于焚烧过程。另一方面，研究了将处理后的污水污泥制成的玻璃渣转化为结晶渣的方法，将其作为建筑材料进行再利用。矿渣中的无机成分对矿渣的结晶有很大的影响。研究结果如下：1.研究结果。虽然污泥中含有SiO_2、Al_2O_3、CaO和Fe_2O_3的混合物需要很高的熔融温度，但通过加钠和加钙来调节Na_2O/CaO的无机组成比(在0.2-0.4之间)，熔融温度下降了约200ﾟC。添加聚合物的污泥的最高成核温度约为700ﾟC，最高晶体生长温度约为1100ﾟC。结晶渣是将固溶体在1100ﾟC下保温1h，然后冷却熔渣制成的。此外，晶态渣很容易通过重新加热玻璃渣来制造。渣中SiO_2含量影响渣的强度。渣的强度随SiO_2含量的增加而增加，但SiO_2含量对液体粘度的影响导致熔化温度较高。建议调整碱度(CaO/SiO_2比：1.0左右)使熔化温度降低。

In the melting process, sewage sludge is melted in the high temperature range of 1300 to 1500 ﾟC which is beyond the pouring point of sludge inorganics and a large volume reduction and stabilization of heavy metals in the slag are expected to greater than incineration process.On the other hand, methods of converting glasses slag made from processed sewage sludge to crystalline slag has been investigated to reuse them as construction materials. Crystalyzation of slag is greatly affected by in-organic component parts in the sludge. The results are as follows.1. Though a mixture of SiO_2, Al_2O_3, CaO and Fe_2O_3 contained in sewage sludge in-organics require a very high temperature to be melted, the melting temperature dropped about 200 ﾟC with the adjustment of inorganic component ratio of Na_2O/CaO (between 0.2-0.4) by Na-added and Ca-added.2. The maximum nucleation temperature of polymer-added sewage sludge is about 700ﾟC, and the maximum crystal growth temperature is about 1100ﾟC. The crystalline slag is made by holding the solid solution at 1100ﾟC during 1 hr and cooling the molten slag. Also, the crystalline slag is easily made by re-heating a glasses slag.3. Strength of a slag is affected by SiO_2 contents in a slag. Strength of a slag increases with increasing of SiO_2 contents, but viscosity of liquids affected by SiO_2 contents causes a high melting temperature. It is suggested that the adjustment of basicity (CaO/SiO_2 ratio : about 1.0) makes the melting temperature lower.