Morphology characteristics and mode of CaO encapsulation during treatment of electrolytic manganese solid waste
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- 作者：Bing Du ; Zhigang Dan ; Changbo Zhou…
- 关键词：Electrolytic manganese solid waste ; Calcium oxide ; Encapsulation ; Secondary hydration heat ; Microstructure
- 刊名：Environmental Science and Pollution Research
- 出版年：2016
- 出版时间：November 2016
- 年：2016
- 卷：23
- 期：21
- 页码：21861-21871
- 全文大小：4,843 KB
- 刊物类别：Earth and Environmental Science
- 刊物主题：Environment
Environment
Atmospheric Protection, Air Quality Control and Air Pollution
Waste Water Technology, Water Pollution Control, Water Management and Aquatic Pollution
Industrial Pollution Prevention - 出版者：Springer Berlin / Heidelberg
- ISSN：1614-7499
- 卷排序：23
文摘
Electrolytic manganese solid waste (EMSW) is composed of manganese, calcium, and other sulfates. Common practice in China is to treat EMSW with quicklime (CaO); however, the per unit mass treatment efficiency of CaO is low. Studies of the interface between the CaO and EMSW particle and their microstructural characteristics are limited; these interactions may explain the low treatment efficiency. We conducted leaching experiments and measurements of the secondary heat generated by hydration of CaO to assess the extent of excess CaO in EMSW. The microstructure of CaO was also analyzed. It was determined that excess CaO particles in the EMSW were encapsulated, which influenced CaO hydration and morphology. The outer layer of the encapsulated CaO contained high levels of calcium and sulfur, which postulated to be caused by CaSO4 precipitates formed from the reaction of CaO hydration products with soluble sulfate. Three types of CaO encapsulation were identified: fully encapsulated CaO (55 % of the total CaO), partly encapsulated CaO (32 %), and self-encapsulated CaO (13 %). High concentrations of soluble sulfates in EMSW cause CaO encapsulation. These react to form CaSO4, which could negatively influence mass transfer and result in low treatment efficiency of EMSW by CaO.