Establishment of Recycling System of Incinerated Ashes produced from Paper Garbage and Paper

为了建立纸污泥中无机化合物的回收利用体系，对纸污泥焚烧灰的焚烧条件和磨粉条件进行了详细的研究，因为这些无机化合物大多来自纸张填料，它们被添加到纸的原纸中，以增加纸的不透明度和亮度。结果表明，经800℃焚烧1 h后，在水中球磨得到的纸污泥灰可作为再生纸填料。采用扫描电子显微镜和x射线色散分析仪对焚烧灰颗粒中元素的分布进行了分析。造纸污泥中的碳酸钙、碳酸镁和高岭土在600℃以下的温度下焚烧，通过熔融转化为胶凝岩。对东京市区垃圾焚烧中心的垃圾焚烧灰进行元素分析，发现其主要成分为钙、硅酸盐和铝，表明这些元素可能来源于纸质填充物。然而，这些垃圾焚烧后的灰烬样本中，水溶性成分在5-20%之间。用沸水萃取法从垃圾焚烧灰分样品中获得了具有相似x射线衍射图谱的低晶化合物。迄今为止，即使经过各种试验，也无法将纸污泥焚烧灰的亮度提高到70%以上。将造纸污泥焚烧后的灰添加到造纸原纸中，添加量达到40%，以评价含灰填料手纸的性能。使用阴离子PAM等干强添加剂可限制拉伸指数的降低。虽然手纸的亮度随着灰分的加入而下降，但不透明度得到了显著的改善。

Incineration conditions as well as milling conditions of the incinerated ash prepared from paper sludge were investigated in detail in order to establish recycling system of inorganic compounds in paper sludge, because most of these inorganic compounds originate from paper fillers, which are added to paper stock to increase opacity and brightness of paper produced. The results show that paper sludge ash obtained by incineration at 800℃ for 1 h followed by ball-milling in water can be used as recycled paper fillers. Distribution of elements in the incinerated ash particles was analyzed by using a scanning electron microscope attached with an X-ray dispersive analyzer. Calcium carbonate, magnesium carbonate and kaolin clay present in the paper sludge are converted to gellenite by fusion during incineration at the temperature below 600℃. Elementary analysis of garbage-incinerated ash sampled in garbage-incineration centers in Tokyo metropolitan areas showed that calcium, silicate and aluminum are the predominant components, which suggested that these elements originated from paper fillers. These garbage-incinerated ash samples, however, contained water-soluble fraction in the range of 5-20%. Low-crystalline compounds having similar X-ray diffraction patterns were obtained from the garbage-incinerated ash samples by boiling-water extraction. It was impossible so far to improve brightness of paper sludge incinerated ash to more than 70% even by various trials.The paper sludge incinerated ash was added to paper stock up to 40% to evaluate properties of handsheets containing the ash as fillers. Reduction of tensile index could be restricted by using a dry-strength additive such as anionic PAM. Although brightness of the handsheets decreased with the ash addition, remarkable improvement of opacity was achieved by the ash addition.