红土镍矿酸浸渣硫酸铵焙烧-超声分散-离心分离提纯增白效果与机理

Study on the process and mechanism of acid-leaching residue of laterite nickel roasting whitening and ultrasonic-assisted centrifugal purification

红土镍矿酸浸渣作为提镍废渣,存量大、白度低、重金属含量高。为实现它在相关领域的回收应用及高值开发,本文通过研究红土镍矿酸浸渣原矿、提纯增白样品和尾渣的化学成分、物相、微观形貌、孔结构以及焙烧过程中的气相,并通过同步热分析与红外-质谱(TG-FTIR-MS)联用系统,以及XRD、SEM、EDS等手段对提纯增白机理进行了分析。提纯增白机理为:预先煅烧去除有机杂质并将铁、铝、铬等离子氧化,二段焙烧将金属氧化物通过一系列反应转化为NH4(Al、Fe、Cr)(SO4)2,并在超声波作用下溶于水中经洗涤去除,未参与反应的六方硫镍矿和砷化锗镉还有部分石英经离心沉淀去除。试验结果:红土镍矿酸浸渣白度由56%提升到84%、含铁量由0. 92%下降到0. 2%、比表面积由84 m2/g提升到96 m2/g、回收率达到47%以上。

As nickel extraction residue,the acid-leaching residue of laterite nickel has a large stock,low whiteness and high heavy metal content.In order to realize its recycling application and high value development in related fields,in this paper,the chemical constituents,phase,microscopic morphology,pore structure and gas phase in the roasting process of the raw acid-leaching residue of laterite nickel,purified and whitened samples and tailings were studied.The mechanism of purification and whitening was analyzed by means of simultaneous thermogravimetry analyzer and infrared spectroscopy-mass spectrometer(TG-FTIR-MS),as well as XRD,SEM and EDS.The mechanism of purifying and whitening is precalcination to remove organic impurities and oxidation of iron,aluminum and chromium ions.The second-stage roasting converts metal oxides into NH4(Al、Fe、Cr)(SO4)2 through a series of reactions,then leaching dissolved in water under the action of ultrasound and removed by washing.The heazlewoodite and cadmium germanium arsenide and some quartz which had not participated in reactions were removed by centrifugal precipitation.The whiteness of acid-leaching residue of laterite nickel was increased from 56%to 84%,the iron content decreased from 0.92%to 0.2%,the specific surface area is raised from 84 m2/g to 96 m2/g,and the recovery rate reaches more than 47%.