Speaker
Dr
Aleksandr Morozov
(Russia)
Description
The treatment of low-grade commercial uranium ores by heap leaching has been carried out at the enterprise since 1996.
During the initial stage of development, the ore piles were formed of the raw ore having the run-of-mine coarseness with uranium content around 0.08%. Under such conditions, recovery of the metal to the solution is 60-65% in case of a pile treatment during 2 years.
To intensify the process and to provide a stable concentration of uranium in the productive solutions transferred to sorption, the developed at the enterprise method of percolation leaching of low-grade ores with re-circulation of productive solutions through the re-treated ore bulk was implemented RF patent No. 2226564. The main peculiarity of such leaching is simultaneous moistening of the ore by productive solutions and by barren solutions that are sharpened with sulphuric acid; that gives the possibility to wet far bigger areas of piles under constant volume of productive solutions outputting to the sorption treatment. Such scheme enables to treat successively first the piles at the “re-treatment” (where the metal is mainly extracted), and then the piles at the “active leaching” stage (where the metal is mainly inside the ore bulk).
The technical-and-economic indexes of the heap leaching of low-grade uranium ores were significantly increased in 2006, when the roentgen-radiometric treatment plant was commissioned. The technological scheme of ore treatment at the processing plant includes mould and grating of the raw material with delivery of undersized products enriched with uranium: -5 mm are transferred to the pulp process; fractions (-200+40) mm do to the roentgen-radiometric separation; the material of size (-40+5) mm washed-out from clayey and slunding particles do to the uranium heap leaching in piles.
Delivery of the ore material having size (-40+5) mm to the treatment by the acid leaching method excluded colmatage and creation of zones impermeable for water, and in combination with re-circulation of productive leaching solutions it enables to intensify the process and to increase the recovery of Uranium to the solution up to 75%, with the time of an ore pile treatment equal to 1.2 to 1.5 years.
The next stage of the uranium heap leaching process intensification shall be implementation of the scheme of fractioning of the ore at the roentgen-radiometric treatment plant before creation of piles from the material having size below 15 mm. Use of such method will give the possibility to increase the recovery of uranium of to 85% in case of the ore with the initial uranium content ~ 0.06-0.07% and the leaching period having duration less than one year.
Primary author
Dr
Aleksandr Morozov
(Russia)
Co-author
Dr
Valery Litvinenko
(Russia)
