Calcium phosphate stabilization of fly ash with chloride extraction.
Calcium phosphate stabilization of fly ash with chloride extraction.
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DOI：
10.1016/s0956-053x(01)00074-5
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发表时间：
2002
期刊：
影响因子：
8.1
通讯作者：
A. Nzihou;P. Sharrock
中科院分区：
文献类型：
--
作者：
A. Nzihou;P. Sharrock
城市固体废物焚烧炉的副产品包括飞灰和空气污染控制残留物。为了将这些焚烧炉废物转化为可重复使用的矿物物种，必须分离可溶性碱金属氯化物，并且必须将有毒微量元素稳定在不溶性形式。我们表明，碱金属氯化物可以有效地提取在水提取步骤结合磷酸钙凝胶沉淀。在这种方法中，获得不含钙盐的氯化钠和氯化钾，并且痕量金属离子固定在磷酸钙基质中。经化学处理后的粉煤灰经适当煅烧后可生成结晶状羟基磷灰石。掺有铜离子并通过该方法处理的飞灰显示出改善的金属离子稳定性。用水或EDTA进行的浸出试验表明，金属离子溶解度显著下降。羟基磷灰石可以捕获有毒金属，也可以防止它们在热处理过程中蒸发。焚烧飞灰与空气污染控制残留物一起，通过氯化物提取和羟基磷灰石形成工艺的组合处理，可以被认为是安全的，可以用作诸如道路基层或水泥块的增值产品中的矿物填料。
Municipal solid waste incinerator by products include fly ash and air pollution control residues. In order to transform these incinerator wastes into reusable mineral species, soluble alkali chlorides must be separated and toxic trace elements must be stabilized in insoluble form. We show that alkali chlorides can be extracted efficiently in an aqueous extraction step combining a calcium phosphate gel precipitation. In such a process, sodium and potassium chlorides are obtained free from calcium salts, and the trace metal ions are immobilized in the calcium phosphate matrix. Moderate calcination of the chemically treated fly ash leads to the formation of cristalline hydroxylapatite. Fly ash spiked with copper ions and treated by this process shows improved stability of metal ions. Leaching tests with water or EDTA reveal a significant drop in metal ion dissolution. Hydroxylapatite may trap toxic metals and also prevent their evaporation during thermal treatments. Incinerator fly ash together with air pollution control residues, treated by the combined chloride extraction and hydroxylapatite formation process may be considered safe to use as a mineral filler in value added products such as road base or cement blocks.