Microwave pretreatment for enhanced selective nitric acid pressure leaching of limonitic laterite
Microwave pretreatment for enhanced selective nitric acid pressure leaching of limonitic laterite
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DOI：
10.1007/s11771-021-4838-z
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发表时间：
2021-10-01
影响因子：
4.4
通讯作者：
Zhao Jian
中科院分区：
文献类型：
--
作者：
He Fei;Ma Bao-zhong;Zhao Jian
微波作为一种清洁能源，常用于各种矿石的预处理。本文采用谐振腔微扰法测量了褐铁矿红土的微波介电特性，系统研究了微波对褐铁矿红土微波介电特性的影响。结果表明，褐铁矿红土具有较高的微波吸收率。微波预处理后，红土矿的微观结构由针铁矿向赤铁矿转变，团聚程度降低，孔隙增多，有利于硝酸浸出（1.2公斤硝酸/公斤矿石）;在200 ℃、500 r/min条件下浸提60 min，Ni、Co、Fe、Mg的浸出率分别为95.2%、98.1%、1.8%、15%。微波预处理针铁矿转化为赤铁矿过程中，含镍矿物被活化，使镍易于浸出。结果表明，该工艺的镍浸出率高于微波预处理（82%）和常规预处理（90.4%）。因此，在硝酸加压浸出前对褐铁矿进行微波预处理是提高浸出选择性和萃取性的有效途径。
As clean energy, the microwave is commonly used to pretreat various ores. In this work, the microwave dielectric properties of limonitic laterite ore were measured by resonant cavity perturbation technique and the effects from microwave were systematically investigated. Results indicated that limonitic laterite had high microwave absorbance. After microwave pretreatment, the microstructure of the laterite became less aggregated and more porous and the main phase transformed from goethite to hematite that improved leaching in nitric acid (1.2 kg HNO3/kg ore); Ni, Co, Fe, and Mg extraction ratios were 95.2%, 98.1%, 1.8% and 15%, respectively, after leaching for 60 min at 200 degrees C and 500 r/min. Furthermore, in the process of goethite to hematite by microwave pretreatment, the nickel-containing mineral is activated, which makes nickel be leached easily. The leaching process has high Ni extraction ratio compared to that without microwave (82%) and conventional pretreatment (90.4%). Therefore, microwave pretreatment of limonitic laterite before nitric acid pressure leaching is an effective way to improve the selectivity and extraction of the leach.