| Vertical centrifugal separation is a beneficiation method for separating target minerals by applying several times or even a hundredfold acceleration of gravity to the mineral.This separation method has the characteristics of low energy consumption,strong adaptability,small particle size at the lower limit of recovery and friendly separation environment,etc.However,the complexity of the matching relationship among the parameters of vertical centrifugal separation,operation parameters and mineral characteristics is different from that of other gravity separation.Therefore,this field has rich theory,technical connotation and broad application prospects.The following works have been finished by combining theoretical research,experimental analysis and numerical simulation method based on experimental platform established by Knelson concentrator.On the basis of mechanical analysis of mineral particles,a centrifugal sorting model associated with material characteristics and operation parameters is constructed and solved;The correlation of centrifugal separation efficiency under different operating parameters was analyzed by CFD-DEM coupling method,the prediction model of the separation effect of centrifugal concentrator is established by response surface method and the correctness of the prediction model and the feasibility of applying CFD-DEM coupling method in centrifugal separation process are verified by simulation and experimental analysis.After the research,some primary results can be obtained:(1)Based on the mechanical analysis of mineral particles under complex physical field,the relationship between parameters such as recoil water pressure,separation cone speed,ore feed flow rate and ore feed concentration on particle movement characteristics and separation efficiency is analyzed;The separation model based on density separation is established,and the influence of particle size matching with other operating parameters on the separation effect is analyzed theoretically,which lays a theoretical foundation for the numerical simulation of centrifugal separation process.(2)A finite element model of separation cone for centrifuge concentrator,the distribution of pressure,tangential velocity and axial velocity in the separation cone flow field is studied on the basis of CFD-DEM coupling;and the movement,stratification,concentration distribution and dynamic separation law of light and heavy mineral particles in centrifugalforce field is analyzed in microcosmic scale.(3)Through the numerical simulation experiments of different operating parameters,it is found that with recoil water pressure,separation cone rotation frequency,feed flow rate and feed concentration increase,tungsten grade and recovery increase first and then decrease.therefore,the optimum centrifugal separation effect can be obtained by reasonable matching of each parameter.(4)A centrifugal separation experiment with operation parameters matching is carried out by using the centrifugal separation experimental platform.The response surface optimization method is applied to establish the prediction model which using separation parameters as variables and the ore dressing evaluation indexes as the response values.By conducting multi-factor related experiments,it is found that the interaction between backwash pressure and feed volume is the most significant response to concentrate grade.The interaction between rotational frequency and feed concentration is the most significant response to concentrate recovery;The experimental results show that the prediction model of grade and recovery based on response surface method is correct.The above results show that research of this subject has a practical significance for the study of centrifugal separation mechanism and numerical simulation,and provide a new idea for the development of centrifugal processing technology and the design of high efficiency centrifuge concentrator. |
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