【作者】 张海军；

【导师】 刘炯天；

【作者基本信息】 中国矿业大学 ， 矿物加工工程， 2009， 博士

【摘要】 矿物浮选泡沫是一种气—液—固三相泡沫体系,对于那些气含率高、流动性差、稳定性高的泡沫而言,普遍存在后续处理难的问题。目前柱分选工艺流程中过稳定性浮选泡沫主要依靠渣浆泵输送,由于泵受汽蚀和气缚的影响,极易导致泡沫输送困难,影响流程稳定和分选指标。此外,用泵输送泡沫还存在系统配置复杂、投资与运行成本高、占地空间大的不足。论文研究所依托的专题“柱式分选设备泡沫自吸输送装置开发”就是在这种背景下诞生的。作为“柱式短流程分选的共性与关键技术研究”课题中的一个专题,论文以自吸封闭式无扰动浮选泡沫输配技术开展研究工作,对于高效柱式短流程分选工艺的开发具有十分重要的意义。在参阅相关文献的基础上,论文首先对泡沫的流变特性进行了总结和分析。通过对泡沫稳定性的研究,提出了柱浮选泡沫同平台自吸输送的研究思路,构建了泡沫输送吸浆器的结构雏形。结合叶片式流体输送机械的研究成果,分析了离心吸浆轮的内流理论,并进行了实验室型泡沫输送吸浆器性能试验,分析了相关参数对性能曲线的影响,在此基础上建立了实验室型泡沫输送吸浆器的能量方程。利用流体力学计算软件对泡沫输送吸浆器叶轮内部流动进行了数值模拟计算,分析了吸浆器内部气液两相流动的相对速度、压力及浓度分布规律,揭示了气含率和气泡直径对叶轮内部流动的影响,掌握了带有螺旋推进轮和离心吸浆轮的组合叶轮内的流场特性。基于对泡沫输送吸浆器过流件磨损形态的分析,对其内部液固两相流动进行了数值模拟计算,得出了吸浆器内部液固两相流场的相对速度、浓度及压力变化规律,分析了流场特性对吸浆器过流件磨损的影响,揭示了颗粒直径和固相浓度对吸浆器过流件的磨损机理。根据泡沫输送吸浆器的工作原理、结构特点和输送方式等,确定了浮选柱泡沫输送吸浆器的结构。借鉴叶片泵的设计方法,结合吸浆器内部流动特性的研究结果,形成了浮选柱泡沫输送吸浆器的水力设计方法和优化措施。在试验研究、数值模拟及结构优化设计的基础上,研制开发了规格为φ400 mm和φ450 mm的吸浆器,并建立了柱浮选泡沫同平台自吸输送试验系统,实现了柱浮选泡沫的顺利输送,简化了柱分选系统配置,改善了柱分选环境,提高了分选指标。更多还原

【Abstract】 Mineral flotation froth is a gas-liquid-solid three-phase system, and the type of froth featuring high gas holdup, poor fluidity and too high stability usually causes processing problems. By now, the steady flotation froth is mainly generated and transported using slurry pump during the column separation process. However, it is still very difficult to transport three-phase froth using slurry pump because the pump efficiency can be greatly reduced by cavitation and aerial binding, resulting in lower processing stability and lower column separation efficiency. In addition, this froth-pump-transporting manner has other drawbacks, such as complicated configuration system, high investment cost and large area occupation. To solve this froth-transporting problem, the research subject of the development of froth transporting and self-sucking device for the flotation column was proposed and received research funding. And this thesis originates from it. As one of the projects of the study on common problems and key technology of shortened process for column separation, this thesis focuses on the study of the technology of flotation froth transmission and distribution under the condition of closed type and undisturbed, which could develop the high efficient shortened process for column separation.After reviewing literature, this paper summarized and analyzed the rheological properties of foam. Based on the reserach of flotation froth stability, a new research idea of self-sucking and transporting manner for column flotation froth was presented. The preliminary structure of froth transporting and self-sucking device was constructed.Applying the research results of fluid transporting machinery with blades, the theory of flow for froth transporting and self-sucking device was analyzed. And the new device was tested under lab-scale to study the influence of relevant parameters on its performance curve. And the energy equation for self-sucking device was established under lab-scale.By using the computational fluid dynamics software, the numerical simulation was carried out for the gas-liquid two-phase flow in impeller of froth transporting and self-sucking device. The influence mechanism of the gas holdup and bubble diameter on the flow in impeller was disclosed. Meanwhile, the flow characteristics of compund impeller with propulsive impeller and centrifugal impeller were explained.Based on the pattern form analysis of flow passage components of self-sucking device, the numerical simulation of the liquid-solid two-phase flow in self-sucking device was carried out. It simulated the relative velocity, pressure and concentration distribution in self-sucking device. The influence of the flow field characteristics on wearing for the flow passage components of self-sucking device was discussed. And the wear effect of particle diameter and solid concentration on the flow passage components of self-sucking device was explained.Based on the working principle, structural characteristics and transporting manner of self-sucking device, the structure of self-sucking device were determined. By referring to the design methods of vane pump and the studies on two-phase flow characteristics in self-sucking device, the hydraulic design method and optimization measures for self-sucking device were preliminarily confirmed.Two self-sucking devices with diameters of 400 mm and 450 mm had been developed on the basis of laboratory tests, numerical simulation and structure design of self-sucking device. The industrial application of this system for froth transporation in column separation process was established, and the column separation froth transported in the same operating platform was realized. The system configuration for this column separation had been simplified, and the separation condition and the separation indexes for column were improved.更多还原