The effect of copper on the precipitation of scorodite (FeAsO4·2H2O) under hydrothermal conditions: evidence for a hydrated copper containing ferric arsenate sulfate-short lived intermediate.
The effect of copper on the precipitation of scorodite (FeAsO4·2H2O) under hydrothermal conditions: evidence for a hydrated copper containing ferric arsenate sulfate-short lived intermediate.
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DOI：
10.1016/j.jcis.2011.05.010
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发表时间：
2011-08
影响因子：
9.9
通讯作者：
M. Gómez;L. Becze;M. Celikin;G. Demopoulos
中科院分区：
文献类型：
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作者：
M. Gómez;L. Becze;M. Celikin;G. Demopoulos
研究了硫酸铜对臭葱石沉淀的影响及其在150 °C下的形成机理。确定臭葱石是在所有探索的条件下形成的主要相（0.61 < Fe（III）/As（V）< 1.87，0.27-0.30 M Fe（SO 4）1.5，0- 0.3 M CuSO 4，0- 0.3 M MgSO 4，在2.5小时和150 ℃下）。发现所产生的臭葱石在其结构中含有高达5%的SO 4和约1%的Cu或Mg。臭葱石的沉淀是化学计量的，即固体中的Fe/As摩尔比等于1，与溶液中的起始Fe/As比无关。在初始溶液中存在过量的硫酸铁（Fe/As > 1），发现减缓了臭葱石中氢键结构的有序化。等摩尔浓度下的沉淀（As = Fe = Cu = 0.3 M），时间短，温度低（30-70分钟和90-130 °C）揭示了Cu-Fe-AsO 4-SO 4-H2O短寿命凝胶状中间体的形成，其非常类似于碱性砷酸硫酸铁（BFAS）类型的相，然后最终完全转化为最稳定的臭葱石相（96分钟和138 °C）。通过元素分析（ICP-AES、XPS）、结构分析（PXRD、TEM）和分子分析（ATR-IR、拉曼），在整个反应过程中追踪该相变。在铜精矿的加压浸提（1小时和150 °C）期间产生的含砷工业残余物的ATR-IR研究发现形成类似于中间碱性砷酸铁硫酸盐相的砷酸盐矿物形式的证据。
The effect of copper sulfate on scorodite precipitation and its mechanism of formation at 150 °C was investigated. Scorodite was determined to be the dominant phase formed under all conditions explored (0.61 < Fe(III)/As(V) < 1.87, 0.27–0.30 M Fe(SO4)1.5, 0–0.3 M CuSO4, 0–0.3 M MgSO4, at 2.5 h and 150 °C). The produced scorodite was found to incorporate up to 5% SO4and ⩽1% Cu or Mg in its structure. The precipitation of scorodite was stoichiometric, i.e. the Fe/As molar ratio in the solids was equal to one independent of the starting Fe/As ratio in the solution. The presence of excess ferric sulfate in the initial solution (Fe/As > 1) was found to slow down the ordering of the H-bond structure in scorodite. Precipitation under equimolar concentrations (As = Fe = Cu = 0.3 M), short times and lower temperatures (30–70 min and 90–130 °C) revealed the formation of a Cu–Fe–AsO4–SO4–H2O short lived gelatinous intermediate that closely resembled the basic ferric arsenate sulfate (BFAS) type of phase, before ultimately converting fully to the most stable scorodite phase (96 min and 138 °C). This phase transition has been traced throughout the reaction via elemental (ICP-AES, XPS), structural (PXRD, TEM) and molecular (ATR-IR, Raman) analysis. ATR-IR investigation of an arsenic containing industrial residue produced during pressure leaching of a copper concentrate (1 h and 150 °C) found evidence of the formation of an arsenate mineral form resembling the intermediate basic ferric arsenate sulfate phase.