黄钾铵铁矾的热分解过程及其产物

Products and Kinetics of Potassium Ammonium Jarosite Thermal Decomposition

考察黄钾铵铁矾对硫酸盐体系中锌、铟的吸附性能。在铁、锌、铟共存的硫酸盐体系中采用黄钾铵铁矾法除铁,得到了含锌、铟的黄钾铵铁矾,通过TG/DTA和XRD对黄钾铵铁矾及其热分解产物进行表征。结果表明,黄钾铵铁矾对锌铟有一定吸附作用,当98.5%的铁形成黄钾铵铁矾沉淀时,锌铟的共沉淀率分别为0.53%和98.9%。黄钾铵铁矾在217～900℃间有二个明显的分解发生,不同温度下所得产物具有不同的晶型及组成。第一步和第二步的热分解活化能、频率因子(lnA)和热分解机理函数[g(α)]分别为175.0kJ/mol,26.0,α2和224.0kJ/mol,23.3和[1-(1-α)1/3]2。

The performance of potassium ammonium jarosite for zinc and indium ions adsorption in the sulfate system is investigated. The potassium ammonium jarosite with zinc and indium is obtained by Fe^3＋ ion removal from the iron, zinc and indium coexisted sulphate system by potassium ammonium jarosite process, The potassium ammonium jarosite and its thermal decomposition products are characterized by TG/DTA and XRD. The results show that the potassium ammonium jarosite can adsorb zinc and indium to some extent. Co-precipitation percentages are 0.53% for zinc and 98.9% for indium, respectively, when 98.5% iron are converted into potassium ammonium jarosite. The thermal decomposition of potassium ammonium jarosite between 217℃ and 900℃ occurs in two well-defined, and products from different temperature calcining have different crystal types and compositions. The Activation energy （E）, frequency factor （lnA） and mechanism function [ g （α） ] for thermal decomposition reaction of first and second step are 175.0 kJ/mol, 26. 0, α^2 and 224.0 kJ/mol, 23.3, [ 1 - （ 1 - α） ^1/3 ] ^2, respectively.