金属液滴穿越精炼渣层真空浇注高洁净大型钢锭新工艺应用基础研究

Considering the demands on the high cleanness heavy forging ingots as well as the current limitation of vacuum casting process, a new vacuum casting process with liquid metal drops passing through the refining slag for high cleanness heavy steel ingots will be investigated. Some important theoretical and key technical issues of this new technology will be studied to lay an important theoretical and applied foundation for the industrialization of it. With the theoretical and hot experimental study in laboratory, the refining slag system of a typical steel grade for the new process will be presented, and the process mechanisms of liquid steel drops passing through the liquid slag layer as well as the refining behaviour during this passing process will be revealed. The efficiency of dehydrogenation during the fall process of drops will also be revealed and the suitable device for drops formation will be developed. Mathematical models will be established to describe the melt-gas two-phase flow during the fall of drops as well as the melt-gas-slag multi-phase flow during the drops passing through the liquid slag layer in the new process and the effects of operation parameters on desulfurization, deoxidation and dehydrogenation will be investigated. By the field application test, the application feasibility of the new vacuum casting process with liquid metal drops passing through the refining slag for high cleanness heavy steel ingots will be presented. So the present study will have important theoretical and practical significance in the stable production of high cleanness heavy steel ingots and it will improve the surface and internal quality of the vacuum casting process with top pouring. And it will also provide some theoretical guidance and reference for the cleanness investigation during the refining processes in other metallurgical reactors.

针对高洁净度大型锻件用钢锭的需求和当前真空浇注工艺存在的问题，进行金属液滴穿越精炼渣层真空浇注高洁净大型钢锭新工艺研究，对涉及此新工艺的若干重要理论与关键技术问题开展深入研究，为此新工艺技术的工业化奠定重要的理论和应用基础。通过实验室的理论与热态实验研究，提出适合该新工艺的典型钢种精炼渣系，揭示液滴穿越液渣层的过程机理及该过程的精炼(脱硫、脱氧)行为机理，揭示液滴下落过程的脱氢效率，研制出合理的液滴生成元件；建立描述该新工艺液滴下落过程钢液-气两相流及液滴穿越渣层过程钢液-气-渣多相流行为的理论模型，揭示过程和操作参数对脱硫、脱氧及脱氢的影响规律；通过企业现场应用试验，提出金属液滴穿越精炼渣层真空浇注高洁净大型钢锭新工艺应用可行性。本项目研究对高洁净大型钢锭的稳定生产具有重要的理论和现实指导意义，能提高真空上注法铸锭的表面及内部质量，本研究还会对其它冶金反应器精炼过程洁净度研究有借鉴作用。

基于高洁净度大型锻件用钢锭的需求和当前真空浇注工艺存在的问题，开展了金属液滴穿越精炼渣层真空浇注高洁净大型钢锭新工艺研究。提出了适合本新工艺的典型钢种精炼渣系；建立了钢液液滴在液渣层中运动的理论模型，并通过理论解析提出了钢液液滴穿越液渣层的过程机理模型；利用热态实验探究了钢液滴穿越精炼渣层的可行性，并研究了液滴直径、渣层厚度、渣系组成等工艺参数对钢液滴穿越渣层的影响规律；通过研究发现，熔渣黏度、液滴直径均为钢液滴穿越渣层的重要影响因素；当熔渣的黏度为0.15 Pa∙s时，钢液滴能够穿越精炼渣层的最小直径为2.1 mm；当液滴直径为6 mm时，钢液滴能够穿越的精炼渣最大黏度为2.13 Pa∙s；提出了适用于高温钢水液滴下落过程的修正脱氢理论模型，并揭示了钢液滴直径、熔池高度、真空度、钢液初始氢浓度对脱氢行为的影响规律；揭示了新工艺过程的脱硫行为规律；研究了新工艺的去夹杂行为，并揭示了不同工艺参数对去夹杂的影响规律。通过热态实验，提出了金属液滴穿越精炼渣层真空浇注高洁净大型钢锭新工艺的可行性。本项目研究对高洁净大型钢锭的稳定生产具有重要的理论和现实指导意义，能提高真空上注法铸锭的表面及内部质量，本研究还会对其它冶金反应器（中间包、VD炉）精炼过程洁净度研究有借鉴和理论指导意义。