Sulfuric acid-based leaching is a promising cleaner method to produce chromium salts, but its feasibility for treating low Fe(II)-chromite still remains to be proven. A Box–Behnken design (BBD)-based set of experiments for sulfuric acid leaching of low Fe(II)-chromite was utilized in this work for generating an experimental dataset for revealing the functional relationships between the processing parameters and the extraction yields of Cr and Fe. The dependent variables were found to exhibit strong intercorrelations and the models developed on the basis of statistical criteria showed excellent prediction accuracy. The optimum process conditions of leaching treatment were found to be a temperature of 176 °C, a dichromic acid/chromite mass ratio of 0.12, and a sulfuric acid concentration of 81%. Furthermore, the dissolution behavior of chromite in the leaching process and the effect of dichromic acid were experimentally investigated. It was found that the decomposition efficiency was highly dependent on the Fe(II) content of chromite, and that the dichromic acid acted both as an oxidant and a catalyst in the leaching process. On the basis of the results of this study, a novel process for treating low-Fe(II) chromite was proposed.

中文翻译：

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低铁（II）-铬铁矿清洁生产氧化铬

基于硫酸的浸出是一种生产铬盐的有前途的清洁方法，但其处理低铁（II）-亚铬酸盐的可行性仍有待证明。在这项工作中，使用了基于Box-Behnken设计（BBD）的低铁亚铬酸铬硫酸浸出实验组，以生成实验数据集，以揭示工艺参数与Cr的提取率之间的功能关系。和铁。发现因变量表现出很强的相互关系，并且基于统计标准开发的模型显示出极好的预测准确性。发现浸出处理的最佳工艺条件是温度为176℃，重铬酸/亚铬酸盐的质量比为0.12，硫酸浓度为81％。此外，实验研究了铬铁矿在浸出过程中的溶解行为和重铬酸的影响。发现分解效率高度依赖于铬铁矿中Fe（II）的含量，重铬酸在浸出过程中既起氧化剂的作用，又起催化剂的作用。根据这项研究的结果，提出了一种处理低铁亚铬酸盐的新工艺。