The vanadium uranium mine in Colorado, USA is the main source of vanadium in the United States. In the early days, vanadium was mainly produced, and uranium was a by-product. After 1943, it was adjusted to produce uranium. In addition to vanadium and potassium uranium ore (K 2 O·2UO 3 ·V 2 O 5 ·3H 2 O), vanadium in the ore is also vanadium mica [3(AIV) 2 O 3 ·K 2 O·18SiO 2 ·2H 2 O] and calcium vanadate. It contains about 0.24% to 1.23% of U 3 O 8 and about 0.07% to 1.16% of V 2 O 5 . The ore can be directly leached with an alkali solution (Na 2 CO 3 , NaHCO 3 ) without calcination, but the leaching rate is low because the vanadium in the vanadium mica is insoluble in the alkali solution. To this end, it is necessary to add alkali baking at 850 ° C in an oxidizing atmosphere, and then immersing in an autoclave at 120 ° C under a pressure of 0.21 MPa for 4 to 6 hours. The leaching rates of vanadium and uranium can reach 70%-80% and 90%-95%, respectively.
The Atlas Mineral Company of the United States uses a new process to treat the Mivida uranium mine. The process flow is shown in Figure 1.
Figure 1 Atlas Minerals Moabi uranium plant process
The ore is broken to 19mm, and it is treated by acid leaching and alkali leaching according to different raw materials.
I. Alkali dip
Add Na 2 CO 3 50 ~ 60g / L, the solution into the wet ball mill, hydrocyclone classification, and then into the thickener. The overflow is returned, the alkali is added, and the Na 2 CO 3 is adjusted to 50 to 60 g/L, which is used for ball milling. The bottom stream was divided into two groups, each group was immersed in 7 autoclaves in series, 120 ° C, 0.35 MPa, 6 h. The effluent slurry is heat exchanged with the feed, and the first two autoclaves are heated with indirect steam. The leached pulp is filtered with a drum filter and the residue is sent to the tailings pond. The filtrate enters four stirred tanks connected in series, heated by steam, and added with NaOH to form a Na 2 U 2 O 7 precipitate, which is concentrated and filtered to obtain a uranium product. After the filtrate passes through the CO 2 gas, it is sent to the vanadium extraction plant as a leach solution.
Second, acid leaching
Ore with water in a wet ball mill and finely classifier, liquid to solid ratio of 5/1, to obtain the recovery of copper into the flotation concentrate. After the flotation, enter a section of the leaching tank. After leaching, enter the hydrocyclone classification. The overflow is clarified and the supernatant is filtered. The bottom stream was passed to a 2-stage leaching tank, heated with steam, and H 2 SO 4 was added for 21 h. The discharge is passed through a rake classifier, and the overflow is used as a first-stage leaching liquid; after the underflow filtration and washing, the residue is sent to the tailings pond. The supernatants of grades 1 and 2 are combined and sent to the extraction process.
Third, extraction
The extract is acidified and adjusted to a pH of 1.0 to 1.2. The 4-stage mixing clarification tank is sent to extract uranium with a tertiary amine. The organic phase is extracted as follows:
Ingredients No. 1 diesel, tertiary amine, isodecyl alcohol
% 92.5 5 2.5
After extraction, the organic phase is back-extracted with sodium carbonate lye to obtain a uranium product. Remaining aqueous phase after extraction of uranium, iron metal powder was added, the solution so that the electromotive force of 150mV or less reduced, the iron is reduced to divalent ions of all, is also part of the vanadium is reduced to tetravalent, in order to increase the rate of extraction of vanadium. Ammonia was added to adjust pH = 2, and countercurrent extraction was carried out in 5 mixing clarification tanks. Organic phase
No. 1 diesel fuel composition di-2-ethyl - ethyl phosphate isodecanol
% 91 6 3
The raffinate after the vanadium extraction is discharged into the tailings pond. The vanadium-containing organic phase was back extracted with 15% H 2 O 4 . The stripping solution is sent to the precipitation tank, heated by steam, and vanadium vanadate is obtained by adding NH 4 Cl and NH 4 OH to vanadium. Finally, ammonium vanadate is dried and melted into flakes for sale.
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