寒冷地区露天矿胶带运输冻粘机理研究

The winter time in our country's northern strip mine can last more than five months, the minimum air temperature can reach -40℃.The frozen stick of belt conveyor drums and idlers is serious and it affects the normal work performance, efficiency and production cost of equipments directly. The method which combines field investigation, theoretical analysis, experimental measurement with field application will be adopted. The frozen stick forming process, the structure which frozen stick coal rock particle formed and the change of tensile strength, shear strength and compression strength of Frozen Stick coal rock mass will be studied. The quantitative relation between frozen stick strength and the size of coal rock particle, water content, temperature and time will be studied and then the mathematical model of coal rock frozen stick` problem will be got. The influnce which different running speed, different coal stacking thickness ,different idler spacing have on drum frozen stick strength will be studied. Then the optimum parameter which prevents Frozen Stick will be determined. The adhesive force of metallic material, non-metallic material and coal rock mass will be studied, the influence which material performance has on adhesive strength will be analysed, and then the material whose adhesive force is the smallest will be determined. In cold area strip mine belt conveyer, the material whose adhesive force is small will be adopted as the encapsulation material of drums and idlers to reduce the influence of frozen stick, and then the feasibility of the scheme will be verified. The scheme which solves the frozen stick problem in cold area strip mine belt conveying will be presented.

我国北方的露天矿冬季时间长达5个月以上，最低温度达-40℃。胶带输送机滚筒和托辊冻粘非常严重，直接影响设备正常工作性能、效率和生产成本。项目采用现场调研、理论分析、实验测试与现场应用相结合的方法，研究冻粘形成过程、冻粘煤岩颗粒形成的结构、冻粘煤岩体抗拉、抗剪及抗压强度变化，建立冻粘强度与煤岩颗粒尺寸、含水量、温度、时间的定量关系，得到煤岩冻粘问题的数学模型；研究不同运行速度、不同煤体堆放厚度、不同托辊间距等对滚筒冻粘强度的影响，确定防治冻粘的最佳参数；研究金属、非金属材料与煤岩冻粘体的粘附力，分析材料性能对粘附强度的影响，确定粘附力最小的材料；在寒冷地区露天矿胶带运输机中，采用粘附力小的材料做为滚筒和托辊的包胶材料，减小冻粘影响，并验证方案的可行性。提出解决寒冷地区露天矿胶带运输冻粘问题的方案。

在我国北方寒冷地区冬季，各大露天矿的胶带输送机改向滚筒、胶带及运煤矿车等煤炭运输设备存在煤冻粘现象，严重影响着煤炭运输的安全与效率，目前对于煤冻粘问题缺少系统理论分析，对于改向滚筒表面冻粘防治缺少有效措施。. 在冻粘机理研究方面，搭建了煤冻粘特性测试试验台，通过试验分析得到不同冻粘基体上煤冻粘界面结构形式、分离破坏形式和冻粘强度等冻粘特性；从冻粘外界条件（冻结温度、时间、压力）、煤自身特性（粒度、外在水含量、黏土成分）以及基体特性（表面粗糙度、波纹度）三个方面，分析得到各单一因素对煤冻粘特性的影响规律及原因；以国内典型煤矿煤样为样品，进行试验和理论分析，分析得到多因素综合影响下煤的冻粘特性及规律，建立了不同冻粘基体上煤冻粘强度关于主要影响因素的数学模型，煤在Q235基体材料上的冻粘强度cτ/MPa关于温度T/℃、时间t/h、压力P/MPa、粒度d/mm、外在水含量δ外/%、表面粗糙度Ra（Q235）/um的回归方程为：cτ=-8.040+0.584δ外-0.052d-0.008δ外2+0.002Ra(Q235)2-0.022d•δ外-0.012T•δ外+0.032 P•Ra（Q235）+0.001t；在UHMWPE基体材料上冻粘强度的回归方程为：cτ=0.165+0.027δ外-0.028d•δ外+0.408δ外2+0.004t-0.006P-2.059e-5T•t-0.001Ra（UHMWPE）. 在冻粘防治方面，基于机理研究，首次分析了UHMWPE材料减粘机理，研制了UHMWPE材料防冻粘滚筒，在煤矿现场应用取得了良好防粘效果，同时设计了UHMWPE材料防冻粘滚筒配套使用的柔性链刮刀式冻粘清扫装置；针对原包胶滚筒冻粘，又设计了防冻粘可加热式改向滚筒及螺旋清扫器，并制作样机，为进一步试验奠定基础。. 本项目为寒冷地区煤在运输设备上冻粘的防治奠定了理论基础，同时提出相应的可行性防治方案，对节约煤炭资源、提高生产效益具有重要意义，具有较好应用前景。