Effects Of Aluminum Colliods And Humic Acid On Uranium Transport In Saturated Quartz Sand

In the CO₂+O₂ in-situ leaching uranium mining process,the deposition and blockage of mineral colloids seriously affect the extraction efficiency of uranium.Therefore,it is urgent to study the influence of colloid on uranium transport behavior,and to provide scientific basis for improving the permeability and uranium leaching effect of CO₂+O₂in-situ leaching uranium deposits.The aluminum hydroxide colloid was prepared,and colloid was characterized by modern detection technology.Al(OH)₃ colloid,humic acid(HA),uranyl carbonate(UC(?))were used as research objects.The effects of flow velocity,ionic strength,initial UC(?)concentration,and humic acid concentration were investigated under the condition of p H=7.6.The transport of single system[Al(OH)₃ colloid or UC(?)],binary system[Al(OH)₃-UC(?)]and ternary system[Al(OH)₃-UC(?)-HA]in saturated quartz sand were investigated.The research contents are as follows:(1)The transport and co-transport behaviors of Al(OH)₃ colloid and UC(?)in the column were studied through column experiments with saturated quartz sand as the medium.The results showed that the increase of flow velocity and the decrease of ionic strength could promote the transport of Al(OH)₃ colloid;the increase of the flow velocity and the concentration of UC(?)would promote the transport of the UC(?);the influence of Al(OH)₃ colloid on the transport of UC(?)were related to the concentration of UC(?).Al(OH)₃ colloid would inhibit the transport of low or high concentration UC(?);at high concentration UC(?)conditions,the inhibitory effect of Al(OH)₃ colloid on the transport of UC(?)first decreased and then increased with the increased of ionic strength.The presence of UC(?)would also inhibit have the transport of Al(OH)₃ colloid;(2)The influence of humic acid on the transport of UC(?)in saturated quartz sand column were studied.The results showd that humic acid would significantly accelerate the transport of UC(?),and the promotion effect would increase slightly with the increase of humic acid concentration;(3)The influence of humic acid and Al(OH)₃ colloid on the transport of UC(?)in saturated quartz sand column were studied.At low concentration of UC(?),low concentration of humic acid could not change the inhibitory effect of Al(OH)₃ colloid on UC(?),while at high concentration of UC(?),humic acid would significantly promote the transport of Al(OH)₃ colloid and UC(?);(4)The Tufenkji-Elimelech equation sorption model and two-site non-equilibrium were used to fit the transport results of Al(OH)₃ colloids,UC(?)in saturated quartz sand columns.DLVO theory was used to calculate the interaction energy between aluminum hydroxide colloids and quartz sand and between humic acid,UC(?)and Al(OH)₃ colloid and quartz sand.As a result,the model could well fit the transport results of Al(OH)₃ colloid and UC(?),respectively.DLVO theoretical calculation results were also consistent with experimental results.