Recovery Molybdenum From The Residue Is Produced In The Ammonia Leaching Process Of Molybdenum Calcined

The production of ammonium molybdate by roasting-ammonia leaching process is the mainstream process of molybdenum extraction.In the process of molybdenum extraction,a large number of ammonia leach residues will be produced.On the one hand,there are unstable elements in the ammonia leach residues,and the stacking of ammonia leach residues will bring potential harm to the environment.With the improvement of environmental protection requirements,the resource and reduction of ammonia leach residues is an urgent problem for enterprises to solve.In addition,there is a certain amount of molybdenum in the ammonia leach residues.With the decrease of molybdenum resources,how to effectively use the existing resources is the key to energy conservation and efficiency.In this paper,the extraction of molybdenum from ammoniacal leaching residue produced in the production of ammonium molybdate was studied.Based on the study of the existing forms of molybdenum in ammonia leaching residue and the theoretical analysis of Mo-H₂O system and Mo-S-H2 O system involved in the process of molybdenum leaching,the technical scheme of recovery of molybdenum in ammonia leaching residue by alkali leaching is proposed.The process and theory of atmospheric alkali leaching and high-pressure alkali leaching of molybdenum from ammonia leaching residue were studied in this paper and have the ammonium molybdate product was prepared from the leaching solution obtained by high pressure alkali leaching.The results show that the elements in the two ammonia leaching processes are basically the same,but the molybdenum content is quite different.In the first process,the molybdenum content of ammonia leaching residue is 7.64%?low-grade ammonia leaching residue?and that of high-grade ammonia leaching residue is 21.74%?high-grade ammonia leaching residue?.The low-grade ammonia leach residue contains2.0% soluble molybdenum and 5.0% insoluble molybdenum;the high-grade ammonia leach residue contains 21% soluble molybdenum and 2.5% insoluble molybdenum.When the low-grade ammonia leach residue is leached by atmospheric multi-stage alkali,the molybdenum leaching rate can reach 87.23%,and the molybdenum content in the leached residue can be reduced to less than 1.33%;the high-grade ammonia leached residue is often leached by multi-stage alkali,the molybdenum leaching rate can reach82.23%,and the molybdenum content in the leached residue can be reduced to 4.2%.The leaching rate of low-grade ammonia leach residue is 96.6% and the content of molybdenum in the residue is less than 0.3% after sodium carbonate thermal leaching;the leaching rate of high-grade ammonia leach residue is more than 82.7% after sodium carbonate thermal leaching,and the content of molybdenum in the residue can be reduced to 3.2%.Under the condition of 1:3 solid-liquid ratio and 1:1.2 alkali content,the molybdenum content of high-grade ammonia leach residue can be reduced to 2.7%after being leached at 150 ?,high-pressure alkali for 2h.After the pretreatment of high-grade ammonia leaching slag by spraying ammonia water with concentration of20% at 60 ? for 1.5h and then high-pressure alkali leaching,the content of molybdenum in the slag can be reduced to less than 1%.The alkaline leaching solution is purified by ion exchange method,and the standard ammonium molybdate and sodium molybdate products can be made by traditional technology.