Supercritical CO2 fluid cooperative biological in-situ leaching uranium mining method

Abstract

The invention discloses a Supercritical CO2 fluid cooperative biological in-situ leaching uranium mining method. First, a uranium ore is pre-acid-leached by injecting organic weak acid citric acid into an ore layer, metal uranium is dissolved from mineral by using a method that a functional group of the citric acid forms a compound and chelate with metal uranium ions, then acclimated thiobacillusferrooxidans is injected into an acidified ore body as an oxidizing agent, Fe2+ in ore is oxidized to Fe3+, then Fe3+ is used to oxidize U4+ insoluble to acid soluble U6+, and finally a highly solubleuranyl carbonate complex is formed with an injected supercritical CO2 fluid. Therefore the concentration of the metal uranium in a leaching solution and the leaching efficiency of the metal uranium are improved, the leaching time is shortened, no side effect exerts on the environment, meanwhile, the use of citric acid can further reduce the precipitation of calcium, magnesium, iron and the like in the leaching solution, and the contact area between a leaching agent and the uranium ore in the subsequent leaching process is increased, so that continuous carrying out of a leaching reaction is facilitated.

Description

technical field [0001] The invention relates to the technical field of uranium mining by in-situ leaching, in particular to a supercritical CO 2 Fluid synergistic bio-in-situ leaching method for uranium recovery. Background technique [0002] In-situ leaching uranium mining is to inject a leaching agent prepared in a certain proportion into the ore layer through a liquid injection well drilled from the surface to the ore-bearing layer, and the injected leaching agent and oxidant will chemically react with the useful components in the ore to form soluble The compound leaves the chemical reaction zone under the action of diffusion and convection and enters the leachate flow that permeates and migrates along the ore seam to form leachate. [0003] In recent years, a number of in-situ leaching sandstone uranium deposits with large reserves have been proven in many parts of Inner Mongolia. Although the resources of one type of uranium deposits are large, they are characterized b...

AI Technical Summary

Problems solved by technology

[0004] For this type of sandstone uranium deposit, if the traditional acid method (generally using sulfuric acid as the leaching agent) is used for mining, on the one hand, due to the high content of carbonate, the acid consumption is relatively high, which is not suitable for the economical development of uranium deposits. At the same time, a large amount of carbon dioxide gas and calcium sulfate precipitation will be produced during acid leaching, which will cause serious blockage of the ore-bearing layer, resulting in the failure of normal mining of the entire uranium deposit

[0005] while using CO 2 +O 2 When the leaching process is mined, although the CO 2 The addition of can partially improve the formation permeability, but it is still difficult to greatly increase the production of process holes

On the one hand, this makes the leaching efficiency low. On the other hand, due to the low production volume and insufficient oxygen injection, the concentration of uranium in the leach solution is low.