Research On Microfluidic Technology In The Purification Of Nickel And Cobalt Sulfate Solution And The Preparation Of Nano-BaSO₄

Solvent extraction and liquid phase precipitation are representative reaction systems in liquid-liquid reaction.There are many problems in conventional extraction,such as long distance of mass transfer,serious co-extraction and emulsification,while liquid phase precipitation can not overcome the problems of uneven distribution,wide particle size and agglomeration.Micro-flow technology can cut reactant into micro-nano-scale fluid,increase the volume ratio of interface significantly,and increase the physical gradient of concentration rapidly.It can overcome the problem of conventional liquid-liquid reaction,and it is suitable for liquid-liquid reaction system.Nickel and cobalt,as two non-ferrous strategic metals,have been playing an important role in metallurgical industry.As the main source of nickel and cobalt,laterite nickel ore is often associated with and imbedded with Fe,Mn,Zn,Ca,Mg and other elements.solvent extraction is often used to separate metals in industry.The mass transfer of conventional extraction distance is long,and co-extraction is serious.In this study,the separation of Mn and Zn from nickel-cobalt sulfate solution by microreactor technique was carried out to achieve the goal of green and high efficiency extraction by microreactor.The liquid-liquid two-phase system under the condition of micro-fluid can realize the rapid mixing mass transfer process without mechanical stirring but only through structured micro-channel,not only it can be used for the extraction reaction,but also is suitable for the reaction of the rapid nucleation of the reaction crystallization.Nano-sulfuric acid is a new kind of inorganic material,which not only has the function of common sulfuric acid,but also has a wide application prospect in the fields of catalysis,magnetic materials,medicine and new materials.Nano-particles prepared by micro-reactor method can overcome the problems of uneven distribution and serious agglomeration of conventional methods.The main contents and conclusions of this paper are as follows:?1?The effects of different process parameters?organic phase concentration,saponification rate and total flow rate?on the extraction and separation of manganese and zinc were studied.In the process of extraction,the flow pattern of liquid-liquid immiscible two-phase fluid is slug flow,and mass transfer is realized by internal circulation and diffusion between interfaces,which effectively strengthens the mixed mass transfer process.When the saponification rate is 10%,the extraction rate of Mn is up to 96%,the Zn is 99%,and the separation coefficient of manganese and zinc reaches the maximum value.The extraction ratio increased almost linearly with the increase of concentration.When the concentration is up to 20%,the separation coefficient reaches the peak of?_Zn/Ni?1469?and?_Zn/Co?2174?,and the concentration is up to 20%to Mn,?Mn/Ni?166?and?Mn/Co?75?.?2?The total volume mass transfer coefficient?kla?showed a nonlinear increase with the increase of the total flow rate,and the total mass transfer coefficient?k _L?showed a similar trend.With total flow rate increasing from 0.1 to 4 mL/min,The k _La of Zn is 0.016⁰.18 s^-1,the k _La of Mn is 0.00881⁰.10757 s^-1,the k _La of Ni is0.0029⁰.026 s^-1,the k _La of Co is 0.0049⁰.041 s^-1,The total volumetric mass transfer coefficient of Zn is much larger than that of ni and Co,The k _La value of Mn/Niwas about 10 times,and Mn/Co was 6 times.?3?In the T-type micro-reactor,the influence of flow rate and reaction temperature on the prepared nano-barium sulfate particles was studied and compared with the conventional stirring precipitation reaction.The results show that the product prepared by conventional method is not uniform in distribution and wide in particle size,while the nano-particles synthesized by micro-reactor method have uniform distribution,smaller particle size and better dispersion.The larger the liquid-liquid flow rate in the microreactor,the shorter the reaction time,the higher the nucleation rate of the grains,and the smaller the nano-particles.The temperature has little effect on the growth of the particles,and the average size of the particles is about 30 nm at 20?-60?.When the flow rate of the microreactor was increased to 100-200 mL/min,the shape of the product was still irregular spherical and the particle size was between 20⁵0 nm,which indicated that the microreactor had no magnification effect,good dispersion and uniform distribution.The product synthesized by IR and XRD analysis is polycrystalline barium sulfate nanoparticles.