Study On The Method Of Immobilized Continuous Culture Of Ore-leaching Bacteria And The Experiment Of Uranium Leaching

There were some problems in industrial application of microbial uranium leaching technology,such as insufficient supply of mature bacteria solution and weak tolerance of bacteria.In this experiment,a new immobilized continuous culture method was used to obtain bacteria with high tolerance to various unfavorable factors,and the best reaction conditions and tolerance values of immobilized bacteria were studied.On this basis,the immobilized continuous culture method of bacteria suitable for uranium leaching wasdetermined,and finally the leaching solution produced by immobilized bacteria was applied to the column leaching experiment of uranium.This paper has the research significance of providing the theoretical basis and technical support for the industrial application of microbial leaching of uranium.The specific research contents andachievements are as follows:The experiment of bacterial immobilization culture shows that the immobilization of Acidithibacillus ferrooxidans can be realized in a short time by adopting the method of circulating reflux culture with 50%inoculation rate and decreasing inoculation ratesuccessively,and the immobilization method can enrich bacteria and improve the ferrous oxidation rate of Acidithibacillus ferrooxidans.The growth curve of immobilized cells has no stagnation period.Under the same conditions,the average oxidation rate of ferrous iron by immobilized cells is 5 times as high as that of free cells with 20%inoculation rate and 4times as high as that with 40%inoculation rate.The continuous culture test of bacteria shows that the immobilized bacteria have good anti-scouring ability and acid resistance;Under normal circumstances,the medium passes through the carrier column in the down-in and up-out mode to obtain higher conversionamount of ferrous iron concentration difference,and the up-in and down-out mode passes through the column to obtain higher ferrous iron oxidation rate;The higher the carriercolumn,the lower the oxidation rate of ferrous iron by bacteria.The best aeration rate is to meet the growth demand of immobilized bacteria.Considering that bacteria only need 2?3g/L Fe³⁺for uranium leaching,a 55 cm high zeolite carrier column was used for uranium leaching experiment.Column leaching tests with different liquid feeding methods show that the total leaching time of K1,K2 and K3 columns was 77 days,77 days and 91 daysrespectively.The total leaching rates were 89.00%,95.56%and 87.55%respectively,and the leaching rates of slag were 85.11%,91.16%and 84.55%respectively.The total acid consumption rates of the three groups were 6.01%,6.75%and 7.87%respectively.For this test ore,continuous drip leaching is the most economical and the highest uranium leaching rate in column leaching.In the later stage of leaching test,the enhanced leaching method of column turning and soaking was adopted,and the leaching rate of U did not increaseobviously.The activity of immobilized Acidithibacillus ferrooxidans can be maintained at the highest Fluorine content of 1057.78 mg/L.Acidithibacillus ferrooxidans immobilized on zeolite by the immobilization method in this experiment can meet the requirements of column leaching test with spray intensity of 12.74 L/(h·m²)and uninterrupted spray for 24hours under the continuous culture conditions of flow rate of 0.1 L/h,liquid inlet mode of lower inlet and upper outlet and aeration amount of 1 L/min.