Study Of Liquid Holdup Behavior And Leaching Process Enhancement Mechanism In Agglomerated Heaps

Agglomeration heap leaching is an efficacious method to realize the efficient leaching of complex low-grade copper resources.However,liquid holdup behavior in the heaps has the unique features including hard-definition,hard-prediction,complex and changeable,which heavily restrict mass transfer and mineral leaching efficiency.This thesis takes the liquid holdup behavior and leaching process enhancement mechanism in agglomeration heaps as the research object,and aiming at improving the liquid holdup behavior of heaps and enhancing mineral leaching efficiency.The main research work includes:1)Independently researched and developed rolling speed and inclined angle adjustable agglomeration experimental drum,systematically revealed the influence of physical factors(ore particle size distribution,rolling speed and inclined angle of agglomeration drum),chemical factors(curing time,binder type and added concentration)and biological factors(concentration of bacteria solution)on the ore agglomeration efficiency.Based on the CCD method and response surface,the response among multiple factors was explored and optimal agglomeration condition were obtained effectively;2)Independently researched and developed the in-situ monitoring device of liquid behavior in unsaturated heaps;investigated the steady liquid holdup,residual steady liquid holdup,immobile-mobile liquid ratio and the other liquid holdup behavior parameters;revealed the effects of stacked feed particle type,particle size,irrigation rate(superficial flow rate),irrigation pattern,initial moisture content on the static liquid holdup of agglomeration heaps;inferred the fluid hysteresis behavior of the agglomeration heap;3)Explored ore leaching regulation under the initial difference of liquid holding behavior;researched the variation of copper leaching rate,pH/Eh value,and bacterial concentration;proved the dynamic liquid holdup behavior features in the leaching process of agglomeration heaps;obtained the solute residence time distribution(RTD)curve based on the tracer and conductivity test;proved the solute diffusion and retention characteristics in agglomeration heaps;discussed the internal relationship between dynamic liquid holdup and mass transfer;4)Determined the size parameters m and n that are suitable for agglomeration heaps based on the van Genuchten-Mualem(VGM)empirical model and the moisture characteristic curve;referred by the liquid film flow theory,the maximum height of the liquid film axis h and the contact angle a,the Lima immobile-mobile liquid model was corrected to obtain a defined model suitable for the fluid flow in agglomeration heap;5)Simulated and predicted the liquid holdup in agglomeration under the different heap porosity,irrigation rate,dripper spacing,initial moisture content and the other condition based on HeapSim platform;Discussed the uneven distribution of liquid holdup behavior at different depths of the agglomeration heap,and different distances to dripper;revealed the features of formation,development and expansion of infiltration tips under the different irrigation condition of agglomeration heap;6)Analyzed the enhanced leaching methods based on the controlling of liquid holdup behavior,proposed grading and classification process of agglomeration particle,pressure-free,thin-layer stacking of agglomeration particles,spray-drip compound multi-layer spraying operation and other engineering advices,by combining the features,mechanisms of ore agglomeration,static liquid holdup,dynamic liquid holdup,and mass transfer,which provided a reference to realize the enhanced leaching of industrial agglomeration heaps.