Ammonia leaching pretreatment process of molybdenum concentrate or molybdenic acid filter cake
A molybdenum calcination and pretreatment technology, which is applied in the pretreatment process before ammonia leaching, and in the field of molybdenum recovery, can solve the problems of difficult industrial application and difficult cleaning and regeneration of charged film.
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Embodiment 1
[0021] The ammonia leaching pretreatment process of molybdenum calcined sand, its main process is as follows figure 1 As shown, firstly, the molybdenum calcine is pretreated with a mixed solution of hydrochloric acid and ammonium nitrate, the pH value of the pretreated wastewater is 1.5, and the molybdenum content in the wastewater is 4.53g / L; then lime is used as a precipitant to pretreat the Afterwards, the wastewater undergoes chemical precipitation treatment, thereby adjusting the pH value of the wastewater to 8; and then uses a cross-flow filter with a TiAl membrane with a filtration accuracy of 1 μm as the filter element to perform cross-flow membrane filtration on the wastewater treated by the above chemical precipitation. When filtering, a negative voltage of 8V is continuously applied on the TiAl membrane relative to the shell of the cross-flow filter, and the filtered concentrated solution is returned to the pretreatment step. The content of molybdenum in the filtered...
Embodiment 2
[0023] The same molybdenum calcine raw material as in Example 1 was used, and the whole ammonia leaching pretreatment process conditions were basically the same as in Example 1, the only difference being that the pH value of the wastewater was adjusted to 6 during the chemical precipitation treatment. After testing, the content of molybdenum in the filtered clear liquid is 38.2 mg / L, so the process makes the recovery rate of molybdenum in the pretreated wastewater reach 99.15%. Embodiment 2 shows with the result contrast of embodiment 1, when the pH value of waste water is 6, because the part molybdenum in the waste water is with the polymolybdate anion of higher price (MoO 20 4- 、Mo 7 o 24 6- ) forms exist, and these higher-valence polymolybdate anions can generate stronger electrostatic repulsion with the TiAl film, thereby improving the rejection rate of the TiAl film for molybdenum.
Embodiment 3
[0025] Use exactly the same molybdenum calcined raw material as in Example 1, and the whole ammonia leaching pretreatment process condition is also basically the same as Example 1, the only difference is that 15V is continuously applied on the TiAl membrane when filtering relative to the cross-flow filter housing negative voltage. After testing, the content of molybdenum in the filtered clear liquid is 31.3 mg / L, so the process makes the recovery rate of molybdenum in the pretreated wastewater reach 99.31%. The comparison between the results of Example 3 and Example 1 shows that increasing the voltage on the TiAl film causes a stronger electrostatic repulsion between the molybdate anion and the TiAl film, thereby improving the rejection rate of molybdenum by the TiAl film. The results of Example 3 further support the correlation between the pH value of wastewater in Example 2 and the strength of electrostatic repulsion during filtration.
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