电解锰渣煅烧时Mn、N元素形态分布与微观结构变化

Morphological distribution of Mn and N elements and changes in microstructure in electrolytic manganese residue during the calcination

电解锰行业的发展会产生大量的电解锰渣,易导致严重的环境污染,高温煅烧已成为当前无害化处理电解锰渣的高效方法之一。为探究高温煅烧时电解锰渣中特征污染物的化学形态及物相组成,选取广西某电解锰企业经不同工艺产生的电解碳酸锰渣(EMCR)与电解二氧化锰渣(EMDR),通过其理化特性及Mn、N元素形态分布与微观结构变化分析,研究了不同温度煅烧处理对电解锰渣污染物的影响。结果表明,电解二氧化锰渣中Mn元素的可氧化态与可还原态分布均大于电解碳酸锰渣。当煅烧温度在1 000℃以上时,2种电解锰渣中Mn元素基本上以残渣态的形式存在,通过风险评估代码(RAC)结果可知样品处于低风险甚至无风险状态,可进行后续的处理处置。2种电解锰渣中N元素的形态随着温度的升高主要以NO形式为主。通过对煅烧过程中微观结构的变化分析可知,在800℃时电解碳酸锰渣中石英相(SiO_(2))的衍射峰强度最佳,有利于活性发展,此时的能谱分析结果显示Fe元素占比达到了52.40%,有利于Fe的回收利用,而电解二氧化锰渣的最佳煅烧处理温度显示为1 000℃。该研究结果可为2种电解锰渣经煅烧处置后的资源化再利用工作提供有效的数据支撑。

The development of the electrolytic manganese industry will generate a large amount of electrolytic manganese residue,which is prone to serious environmental pollution.High temperature calcination has become one of the efficient methods for harmless treatment of electrolytic manganese residue.To explore the chemical forms and phase composition of characteristic pollutants in electrolytic manganese residue during hightemperature calcination,electrolytic manganese carbonate residue(EMCR) and electrolytic manganese dioxide residue(EMDR) produced by a household appliance manganese removal enterprise in Guangxi through different processes were selected.The influence of calcination at different temperatures on the pollutants in electrolytic manganese residue was studied by analyzing its physicochemical propertie,including the morphological distribution of Mn and N elements,and the changes in microstructure.The results showed that the distribution of oxidizable and reducible states of Mn element in electrolytic manganese dioxide residue was greater than that in electrolytic manganese carbonate residue.When the calcination temperature was above 1 000 ℃,the Mn element in the two types of electrolytic manganese slag basically existed in the form of residue.The risk assessment code(RAC) results indicated that the sample was in a low-risk or even risk-free state,and can be subjected to subsequent treatment and disposal.The form of N element in the two types of electrolytic manganese residue was mainly in the form of NO with the increase of temperature.Through the analysis of the microstructure changes during the calcination process,it can be concluded that the diffraction peak intensity of quartz phase(SiO_2) in electrolytic manganese carbonate residue was the best at 800 ℃,which was conducive to the development of activity.At this time,the energy spectrum analysis results showed that the proportion of Fe element reaches 52.40%,which was conducive to the recovery and utilization of Fe.The optimal calcination temperature for electrolytic manganese dioxide residue was shown to be 1 000 ℃.The research results will provide effective data support for the resource reuse of two types of electrolytic manganese slag after calcination treatment.