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

Abstract

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 pre-calcination 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%.

Keywords

• acid-leaching residue of laterite nickel
• ammonium sulfate
• roasting
• whitening
• phases