INFLUENCES OF CASTING SPEED AND SEN DEPTH ON FLUID FLOW IN THE FUNNEL TYPE MOLD OF A THIN SLAB CASTER

In recent years, thin slab continuous casting technology has been widely used to improve the quality of the product and to reduce the cost. One of the challenges faced by this technology is to design reasonable flow patterns, which strongly affect the surface and inner properties of the final slab in the mold. With the fixed scales and complex geometrical structures of nozzle and funnel type mold, a series of numerical simulations are made to analyze the flow patterns in melt steel using finite volume method based on structured body fitted coordinate grids. The CFD （computational fluid dynamics） package is validated first using one typical case described in previously published studies, and then it is developed to study the effect of operational parameters on fluid flow in thin slab caster. Two operational parameters, casting speed and SEN （submerged entry nozzle） depth, are mainly considered for numerical analysis. On the basis of present simulations, the reasonable SEN submergence depths corresponding to different casting speeds are suggested according to fluid flow characteristics like, flow jet impingement on the narrow side of the mold, flow speed of the melt steel beneath the meniscus and the recirculation region. This is the first stage of study on the numerical analysis of the whole thin slab casting process with electromagnetic brake.

滇西芒市盆地芒棒组软岩的水文、工程地质特征及其对工程的影响——以芒究煤矿为例

滇西芒市盆地是在喜马拉雅构造运动第Ⅱ幕基础上形成的陆相沉积盆地,该盆地中的上新世芒棒组为河湖相沉积体系。根据矿区钻孔资料,芒棒组在工程地质岩组划分上属半固结软岩,可分为砂岩-砂砾岩软弱岩组、粉砂岩软弱岩组和炭质泥岩-煤层软弱岩组3类。

群矿采煤条件下水资源与水环境的变化与预测

以往针对单个煤矿采煤对水资源或水环境研究较多。利用煤田区5个井田和6个生产矿井资料,从水循环、水量、水质角度综合分析群矿采煤对区域水资源与水环境的变化并在此基础上进行预测。结果表明,不同标高同时开采,开采面积逐渐扩大、开采深度逐渐加深和开采强度不断增大,不同埋深的含水层逐渐被疏干,形成以矿井为中心的地下水降落漏斗群,最终形成200 km^(2)的巨大地下水漏斗,十个煤矿排地下水共3.67×107m3/n。天然水循环在群矿采煤活动中被破坏或打乱,补给、径流和排泄均发生变异。群矿采煤活动中地表径流和老窑水通过采煤形成的裂缝与塌陷带渗漏入矿井中,致使地表径流量减少,地下水系统和地表水系统也随之改变,地表水资源和地下水资源受到不同程度的影响和破坏。尤其是矿井抽排水、老窑积水与渗漏、煤矸石淋漓、酸性水及固体废弃物随着地下水和地表水迁移和扩散,使地下水环境和地表水环境受到不同程度的破坏与污染,且随着采深加深而逐年恶化,加大治理修复难度。