In the ore beneficiation process of Baiyun Obo, the process of reduction roasting-magnetic separation (recovery of iron )-flotation (recovering rare earth, fluorite and other minerals) plays an important role. It is of practical significance to study the effect of reduction roasting on the floatability of minerals.
1. Effect of reduction roasting on the floatability of mixed rare earth minerals and fluorite
As shown in Fig. 1, after the rare earth mineral and fluorite were calcined at 600 ° C, the floatability was significantly improved.
Figure 1: Before and after calcination -0.043+0.01mm Rare earth and fluorite floatation I, I'- and after 600 °C reduction roasting rare earth ore; II, II'- without 600 ° C reduction roasting fluorite
2. Effect of reduction roasting on water glass and alum flotation rare earth minerals and fluorite As shown in the results of Fig. 2 and Fig. 3, the flotation of rare earth minerals and fluorite before and after reduction of roasting glass and alum is basically the same. Only because of the increase in floatability of the mineral after reduction roasting, the amount of inhibitor required is correspondingly increased.
Fig. 2 Effect of reduction roasting on the flotation of rare earth and fluorite by water glass as inhibitors I, I'-reduction and roasting of rare earth ore at 600 °C; II, II'-reduction of calcined fluorite by reduction at 600 °C [ Next]
Fig. 3 Effect of calcination on alum flotation -0.043+0.01mm rare earth and fluorite I, I'- the same as Fig. 1; II, II'- the same figure 1
1.8.3 Reasons for floatability change before and after rare earth mineral reduction roasting In order to investigate the reasons for the increase of floatability of rare earth minerals after 600 °C reduction roasting, Yang Naigeng and Xu Yiwei used a radioisotope (14C) adsorption measurement method for comparative study. It is proved that the ability of the mixed rare earth minerals after calcination to adsorb lauric acid (14C) is remarkably improved, which is presumed to be due to the increase in surface angle and porosity after roasting of rare earth minerals.
We conducted research by X-ray analysis, microscopic observation, differential thermal analysis, and measurement of decomposition rate. X-ray analysis and microscopic observation shows structural and optical properties bastnaesite has changed, generates a crystalline rare earth oxide, but the change has not occurred monazite. Differential thermal analysis showed a strong decomposition endothermic reaction at 600 °C. The decomposition rate experiment (see Fig. 4, the decomposition rate is expressed by the number of bubbles in the calcium hydride solution decomposed by the oxygen per minute) indicates that the decomposition process of the bastnasite is divided into two stages, which are mostly decomposed at 470 °C. When the temperature is raised to 530 ° C, the decomposition rate is decreased. It is possible that the residual CO 2 and the crystal lattice are tightly bound at this time, and it is difficult to decompose. When the temperature is further raised to 600 ° C, the bubbles are precipitated in a large amount, and then, the temperature is further increased. Very few bubbles were precipitated, indicating that the bastnasite was substantially decomposed at 600 °C.
Fig. 4 Relationship between reduction calcination temperature and CO 2 escape rate in rare earth minerals (-0.043+0.01mm)
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