基于酸浸焚烧污泥灰中的磷释放及蓝铁矿生成

Phosphorus release and formation of vivianite from acid leaching incineration sludge ash

酸浸焚烧污泥灰(ISSA)是一种湿化学法提取磷(P)的工艺,因其操作简单、损耗低而被广泛应用.以烘干污泥为对照,通过考察不同温度(600~900℃)下ISSA中的磷形态和矿物相转变,研究了H_(2)SO_(4)和HCl作为提取液的酸浓度、酸浸时间和液固比对ISSA样品释磷性能以及对Ca、Al、Mg、Fe等关键金属元素浸出行为的影响,最终通过酸浸、阳离子交换树脂(CER)纯化和沉淀三步反应得到磷回收产物.结果表明:ISSA样品磷的形态以非磷灰石态无机磷(NAIP)为主,且部分NAIP会随着焚烧温度的升高转变为磷灰石态无机磷(AP);同时,污泥样品经两种提取液酸浸后,金属元素Ca、Al、Mg释出量最多,其中Ca、Mg元素的浸出量随焚烧温度的升高变化不大,而Al的浸出量随焚烧温度的升高急剧降低;相比其他焚烧温度,800℃条件下ISSA释磷性能更好,且H_(2)SO_(4)酸浸释磷性能优于HCl酸浸,当H_(2)SO_(4)浓度为0.10mol/L、液固比为150mL/g、酸浸时间为150min时释磷率达到最高;分析表征结果表明,采用CER对H2SO4浸出液纯化后,反应合成的磷回收产物为纯度较高的蓝铁矿.

Acid leaching incinerated sewage sludge ash(ISSA)which is a wet chemical process to extract phosphorus(P),is widely employed due to its simple operation and low loss.In this study,the effects of acid concentration,acid leaching time and liquid-solid ratio on the phosphorus release performance and the leaching behavior of key metal elements(Ca,Al,Mg,Fe)of ISSA samples using H_(2)SO_(4) and HCl as extraction solutions were investigated by analyzing phosphorus form and mineral phase transition in ISSA at different temperatures(600~900℃)with dried sludge as control.Finally,phosphorus recovery products were separated by acid leaching,cation exchange resin(CER)purification and precipitation.The results showed that the form of phosphorus in ISSA sample was mainly dominated by non-apatite inorganic phosphorus(NAIP),and part of NAIP could change to apatite inorganic phosphorus(AP)with the increase of incineration temperature.At the same time,after acid leaching with two extraction solutions,Ca,Al and Mg were the highest released metals in sludge samples,among of which the leaching amount of Ca and Mg changed slightly while Al decreased sharply with the increase of incineration temperature.Moreover,ISSA had a better phosphorus release performance at 800℃ compared with other incineration temperatures,and the phosphorous release performance of H_(2)SO_(4) acid leaching was better than that of HCl acid leaching.As H_(2)SO_(4) concentration was 0.10mol/L,liquid-solid ratio was 150mL/g and acid leaching time was 150min,the phosphorus release rate reached the highest.Analysis and characterization revealed that,the phosphorus recovery product synthesized from H2SO4leaching solution after CER purification was highly purified vivianite.