Study On Oxygen Diffusion Kinetics Model In Biological Oxidation Pretreatment

Biological oxidation gold extraction technology is the most promising gold extraction technology in recent years.Because the oxidation tank involves solid,liquid and gas,the flow of the fluid is very complex,and the oxidation tank involves biological reaction and chemical reaction,making the mechanism of biological oxidation tank more difficult to study.At present,the design and operation of biological oxidation tank in engineering practice have great experience and lack of reliable theoretical support.High energy consumption is a common problem in the process of biological oxidation tank.In this paper,numerical simulation method is used to study the characteristics of gas-phase fluid model in biological oxidation tank,so as to obtain relatively optimal working condition parameters in practical engineering and reduce energy consumption.Firstly,this paper introduces the theoretical basis of numerical simulation and computational fluid dynamics,analyzes and simplifies the biological oxidation pretreatment process based on practical engineering,and establishes the mathematical model of fluid diffusion in the tank and the mathematical model of gas phase diffusion.Secondly,CFD modeling was used to study the fluid characteristics in the oxidation tank at different times,at different mixing speeds and at different air intakes.Conclusions were drawn as follows: When the stirring speed was between 40-50 rpm,the flow field was complex,there were many small eddies,and the gas phase was evenly distributed.When the stirring speed was 60 rpm,the flow field was complex,the gas phase was evenly distributed,but the liquid level was unstable,and a large vortex appeared.(2)when the stirring speed is constant and the air volume increases,the gas phase distribution does not change with the change of air volume;When the stirring speed was 30 rpm,the gas content in the tank increased faster than that when the air volume was increased to 50 rpm.Finally,the relationship between the diameter of the air disperser and the gas distribution in the oxidation tank was studied,and theconclusions were drawn :(1)in the biological oxidation tank,when the rotor speed was constant and the air intake was constant,the closer the oxidation tank was to the diffuser,the higher the gas concentration was,and the farther it was,the lower the gas concentration in the oxidation tank was.(2)when the diameter of the air disperser is between 2m and 5m,the gas concentration increases with the increase of the diameter;When the gas concentration increased to 1.2258 kg/m3,the diameter of the air disperser continued to increase,but the gas concentration no longer increased.The conclusions of the study can provide the following Suggestions for the field :(1)the stirring speed should be set at 50 rpm,when the flow field in the oxidation tank is complex,the gas phase distribution is uniform,and the liquid level is stable.(2)the amount of oxygen needed in the oxidation tank shall be provided on demand according to the line chart of air filling amount and gas content in the oxidation tank.(3)setting the diameter of the air disperser to 5m can maximize the inflation efficiency.