| Bottom-blowing oxygen-enriched copper smelting is a production process closely related to multiphase fluid flow and heat and mass transfer.The study for fluid flow characteristics and furnace structure and operating parameters of bottom-blowing furnaces is conducive to oxygen-enriched bottom-blowing copper smelting toward lower energy consumption and more efficient and environmentally friendly.In this paper,numerical simulation and mathematical statistics are combined to establish a mathematical model of multi-phase flow heat and mass transfer with enhanced mixing based on a multi-channel bottom-blowing oxygen lance,and the mathematical model is verified by hydrodynamic modeling experiments.This paper is main study as follow:(1)The study is conducted to investigate the mechanism of enhanced stirring during the gas injection of multi-channel oxygen lance.Through numerical simulation to monitor the flow field and velocity at the outlet of the straight-tube oxygen lance and the multi-channel oxygen lance,it is found that there is an obvious Laval tube effect during the gas injection of the multi-channel oxygen lance.For the model calculation results,the bubble rise time,gas holdup variance,average turbulence intensity and image entropy are used as evaluation criteria to compare the mixing uniformity of straight pipe and multi-channel bottom-blowing oxygen lance gas blowing and mixing.The results show that:multi-channel oxygen lance spraying can not only improve the melt stirring energy can also make the melt in the middle-upper part of the melt pool more fully mixed,the multi-channel oxygen lance applied in production practice,found that its operating rate and load rate increased by 5.58%and 1.28%respectively.The elucidation of the mechanism of gas injection intensified stirring by the multi-channel oxygen lance and its successful application in production practice proves the superiority of the multi-channel oxygen lance in the bottom-blowing melt pool melting.(2)The flow characteristics of the stratified fluid in horizontal bottom-blowing furnace based on the multi-channel oxygen lance is studied,and the bottom-blowing furnace is optimized according to the weight matrix method of orthogonal test design.Using the gas content holdup and the average turbulence energy as the indexes,the optimization interval of each factor is obtained from the single-factor analysis of the exit area,inclination and spacing of the multi-channel oxygen lance and the slag-copper thickness ratio in the bottom-blowing furnace.i.e.,the gas holdup variance and the average turbulence energy are in the good level when the outlet area of multi-channel oxygen lance is about 10 mm2,inclination of multi-channel oxygen lance is about 21°,spacing of multi-channel oxygen lance is about 45 mm and the slag-to-copper thickness ratio is about 0.3.Further,the weight matrix analysis method based on orthogonal test design is used to obtain the index value weight of each factor level,and the optimal optimization plan and the priority influence order of each factor on the index value of the orthogonal test are determined according to the weight.i.e.,the best optimized combination is A2B3C3D2,and the priority influence order of each factor on the index values of the orthogonal test is B(0.339)>A(0.255)>D(0.2095)>C(0.1965).The study of the multiphase flow characteristics of the stratified fluid in the bottom-blowing furnace and the structure and operating parameters of the bottom-blowing furnace provides a scientific and accurate theoretical basis for the optimization of the technology related to the bottom-blowing process. |
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