氧气底吹冰铜熔炼过程中多相流传输行为及反应动力学研究

Oxygen bottom-blown smelting method is a world advanced new copper smelting technology, which is independently developed by our country. In view of the ambiguous law of bubble behavior in the bottom-blown smelting process and the vacancy of research on the smelting reaction kinetics, in this subject, based on the behavior mechanisms of bubble break and coalescence and the compressibility of gas jet, the transport behaviors of multiphase flow and the reaction kinetics are simulated. The influence laws of gas compressibility on the bubble growth and liquid turbulence are firstly revealed. The influence of turbulent vortex, flow sheer stress and trailing vortex mechanisms on the bubble behaviors of break and coalescence is explained. The quantitative relations between flow characteristics of melt motion, gas holdup and bubble size and the operation parameters of bottom-blown smelting and oxygen lance are obtained. Furthermore, based on the theories of thermodynamics and kinetics, behavior mechanisms and control steps of heterogeneous phase chemical reaction such as gas-liquid reaction and liquid-liquid reaction in the smelting process are clarified. The quantitative relations between concentration distribution of the components in copper matte and slag, and the parameters of time, space, bottom-blown smelting and oxygen lance are established. Finally, transport behaviors of multiphase flow and the reaction kinetics are described comprehensively and the mutual influence laws are revealed, which provides theoretical basis of increasing smelting efficiency and improving process.

氧气底吹熔炼法是我国自主研发的一种世界先进的铜冶炼新工艺。针对目前对底吹炼铜射流过程中气泡尺寸行为规律尚不明确，对非均相反应动力学规律尚未揭示与掌握的现状，本项目基于气泡破裂、聚合行为机理，在考虑射流气体的可压缩性基础上，对氧气底吹熔炼过程中多相流传输行为及反应动力学展开研究。首次揭示气体可压缩性对熔池内气泡膨胀及液体湍流的影响规律；探明液体湍流漩涡、流动剪切、气泡尾涡等机制对气泡聚合、破碎行为的影响规律；阐释底吹熔炼炉内熔体运动、气含率、气泡尺寸等与底吹参数、氧枪参数间的定量关系。在此基础上，基于热力学和动力学理论，阐明熔炼过程中气-液、液-液等各非均相化学反应行为机理和控制环节，建立熔池内冰铜、渣相中各组分浓度分布与时间、空间、底吹参数、氧枪参数间的定量关系。最终全面描述多相流传输与反应动力学，揭示其相互影响规律，为提高熔炼效率，改进工艺提供了理论依据。

针对目前底吹炼铜法存在的氧枪结构和布局不合理，部分入炉矿料难以被迅速卷入熔体，熔池喷溅导致加料口堵塞等问题，开展了氧气底吹冰铜熔炼过程中多相流传输行为及反应动力学研究。探索了底吹转炉射流行为和熔池内气泡微细化形成机制，考察了不同熔池深度、喷嘴直径、喷吹角度、喷吹气流量及喷嘴排布对气泡的尺寸、停留时间和混合效率的影响。利用CO2-NaOH溶液体系模拟底吹炉内的气液传质现象，探明了不同CO2体积分数、气体喷吹速度和熔池深度对容积传质系数和气体利用率的影响规律。揭示了底吹气体流量、底吹氧枪喷嘴直径和氧枪安装角度对底吹炉物料卷吸效果的影响，建立CFD-PBM耦合数学模型描述底吹炉射流气泡破碎聚合机制。研究发现：使用1.6mm喷嘴、喷吹角度为14°时，气泡尺寸小、气泡停留时间长。对于小尺寸喷嘴，物料卷吸效果随着喷枪角度和喷气量的增大而增加，大尺寸喷嘴的规律则与之相反。熔池喷溅主要出现在液面上方的泉涌区；增加熔池深度有利于提高熔池搅拌效果并减少喷溅。当喷嘴布置在炉底中心，熔池混合效率较低，过高布置不利于气体利用率，7deg-14deg的喷嘴布置为最优方案。随着喷嘴数量和喷吹流量的增加，熔池内气泡分散性变好，但过多喷嘴数量会造成熔池混合效率的降低，且吹气流量超过18.8Nm3/h时，气泡总体和传质速率增长趋势变缓，因此推荐炉底喷嘴数量为13个，喷吹气流量为18.8Nm3/h。本项目的研究及成果为深入认识底吹炼铜过程的流动传输和反应动力学行为，优化底吹设计，降低喷溅，提高冶炼效果提供理论基础和指导。