Selective Liberation of High-Phosphorous Oolitic Hematite Assisted by Microwave Processing and Acid Leaching

Abstract

The release of valuable minerals from the associated gangues is called liberation. Good liberation is essential to the subsequent separation stage. Selective liberation is advantageous to improve the degree of liberation. Oolitic hematite is one of the typical refractory iron ores in China, and its resources are abundant. However, owing to its fine dissemination and complex mineralogical texture, the conventional grinding processes are inefficient in improving the selective liberation of oolitic hematite. In this study, microwave processing and acid leaching were used to assist the liberation of oolitic hematite. The assisted liberation of the oolitic hematite mechanisms of microwave processing and acid leaching were studied by using scanning electron microscope (SEM), X-ray diffraction (XRD), BET specific surface area detection method (BET) and the transflective microscope method. The results indicated that microwave processing can reduce the mechanical strength of oolitic hematite and improve the liberation of hematite, and acid leaching can improve the microwave-assisted liberation efficiency and reduce the content of phosphorus in the grinding product. Compared to direct grinding, the liberation of hematite increased by 54.80% in the grinding product, and especially, the fractions of −0.038-mm and 0.05-0.074 mm increased significantly; however, there was no obvious change in other grain sizes, and the dephosphorization ratio reached 47.20% after microwave processing and acid leaching. After the two stages, the iron grade and recovery of the magnetic separation product increased by 14.26% and 34.62%, respectively, and the dephosphorization ratio reached 88.59%. It is demonstrated that microwave processing and acid leaching comprise an efficient method to improve the liberation of hematite and the dephosphorization ratio of oolitic hematite. The two-stage treatment can achieve selective liberation of oolitic hematite, which is beneficial to the following magnetic separation.

Characterization studies on Agbaja iron ore: a high-phosphorus content ore

“…As a consequence, a lot of research efforts have been focused on phosphorus removal from high-phosphorus iron ore [20,24,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] in a bid to reduce the P content to acceptable levels. Processes that had been employed for phosphorus removal from iron ores include thermal treatment [7,21,24,[38][39][40][41][49][50][51][52][53], microwave treatment [38,[54][55][56], ultrasonic treatment [54], acid leaching [12,17,20,49,[56][57][58][59][60], alkaline leaching [5,59], bioleaching [30,[61]…”

Methods of Ore Pretreatment for Comminution Energy Reduction

“…The results showed that the microwave treatment (f = 2Hz, pulse time = 100 µs, power = 5.6 kW, time = 30 s) of the samples (+9.2 −12.5 mm, 6 kg) prior to heap leaching (800 mL solution; 14 g/L sulphuric acid +3.75 g/L ferric sulphate, at 25 • C) improved the yield in the range of 7% to 12% [69]. Cai et al (2018) studied the combined effects of the microwave pretreatment, acid leaching, and magnetic separation of high phosphorus oolitic hematite (HPOH) [71]. The first phase of the study indicated that the microwave pretreatment (2.5 kW, 45 s, water quenched after treatment) of the representative HPOH samples reduced their work index from 15.25 kWh/t to 10.11 kWh/t.…”

Avaliação do potencial de solubilização de fósforo pelo Aspergillus terreus

“…Diversos são os processos empregados na remoção de fósforo de minérios de ferro, incluindo a separação por magnetização de torrefação (Cao et al 2018;, redução direta à base de carvão , tratamento térmico (Zhang et al 2018;, tratamento por micro-ondas (Cai et al 2018;Kim et al 2018), tratamento ultra-sônico (He et al 2018), lixiviação ácida (Xiang et al 2018;Cai et al 2018), lixiviação alcalina (Guo et al 2015;, aglomeração seletiva (Yang et al 2018), e flotação (Tudu et al 2018;.…”