大型球磨机多体冲击摩擦耦合行为研究

Aming at improving the effficiency of ball mill and reducing energy dissipation and consumption of steel ball and liner, the multi-body impact-tribology pair of steel ball-mineral- liner in a ball mill is investigated. The multi-body impact-tribology coupling behavior of a large ball mill is studied according to the theory of discrete element method, impact dynamics, tribology, heat conduction, contact mechanics, fracture mechanics and damage mechanics. Firstly, the discrete multi-body impact dynamic model and the energy evaluation model of grey relational-support vector machine are established. And the parameter of the large ball mill is optimized to reduce the energy consumption. Secondly, the friction and wear mechanism of multi-body impact is revealed and the evaluation optimization model of the tribology characteristics is set up to increase the transfer ratio of friction energy. Additionally, the discrete heat conduction model among the steel ball particle, mineral particle and liner is established. The thermal-impact fatigue fracture and fatigue damage models of steel ball, liner and mineral are established on the basis of the numerical manifold method. And the mechanism of thermal-impact failure is revealed, which is in favor of reducing the consumption of steel ball and liner. Finally, the temperature-seepage-stress-damage coupling model is established, and the integrated evaluation model of the mill efficiency and the consumption of energy and steel ball is set up. The research results will break through the key foundation issues of large ball mill with high consumption of energy and steel, which will form the theory and technology of multi-body impact tribology.

本项目以大型球磨机内钢球-矿石-衬板的多体冲击摩擦副为研究对象，以提高球磨效率、降低能耗和钢球、衬板消耗为目标，将离散元、冲击动力学、摩擦学、热传导、接触力学、断裂力学、损伤力学等理论相结合，开展大型球磨机多体冲击摩擦耦合行为研究。首先，构建多体冲击离散动力学模型，建立灰色关联支持向量机能量评价模型，优化球磨参数，降低大型球磨机能耗；其次，揭示多体冲击摩擦磨损机理，构建以摩擦磨损特性为评价指标的优化模型，提高大型球磨机摩擦能转换率；接着，构建大型球磨机内部钢球、矿石及衬板离散传热模型，基于数值流形方法建立钢球、衬板热冲击疲劳断裂模型以及矿石热冲击疲劳损伤模型，揭示多体热-冲击破坏机理，降低钢球和衬板消耗；最后，建立球磨过程温度-渗流-应力-损伤耦合模型，构建球磨效率、能耗和钢耗的综合评价模型。研究成果将突破高能耗、高钢耗大型球磨机核心基础问题，形成具有普遍意义的多体冲击摩擦理论与技术。

球磨机是物料破碎的关键设备，广泛应用于矿山、冶金、建材、制药等行业，也是上述行业耗电量最大的设备，其耗电量约占选矿厂整体用电的40%-50%，耗电总量约占全国发电总量的2%；此外，磨矿过程中存在着磨矿效率低、钢球消耗量大、衬板磨损失效等问题，造成了极大的能源消耗。为此，本项目以球磨机内磨矿介质-铁矿石-衬板多体冲击系统为研究对象，以提高球磨机效率、降低球磨机能耗为目标，结合离散元、摩擦学、破碎动力学、热传导、冲击动力学等理论，开展了多体冲击离散动力学研究、多体冲击摩擦磨损研究、多体冲击热传导行为研究、多体热-冲击破碎研究、铁矿石颗粒破碎特性研究。重要结果主要有：以离散元数值仿真和试验验证相结合的方法，标定了磨矿介质间接触参数；提出一种位置密度法，解析介质群速度区域分布特性和碰撞能量分布特性；理论分析了磨矿介质运动学规律，解析了磨矿介质运动特征参数的变化规律，并构建了介质群特征参数预测模型；掌握了球磨机内钢球与衬板多体冲击摩擦磨损特性；基于离散元软件，二次开发了离散热传导模型，创新应用于球磨机多体热传导研究；设计了检测球装置，创新应用于干湿磨工况下球磨机介质动力学试验研究；开展了铁矿石热破碎试验和冲击破碎试验，探析了铁矿石颗粒破碎规律以及能耗分布。项目资助期间，发表论文14篇：SCI收录8篇、EI刊源2篇、中文核心4篇；在审SCI论文3篇；授权澳大利亚发明专利1件、中国发明专利2件、实用新型专利1件、在审发明专利1件；2人次获孙越崎青年科技奖、全国煤炭青年科技奖，2人次获评江苏省“333高层次人才培养工程”中青年科学技术带头人；培养博士生2名、硕士生2名（指导毕业1名博士生和1名硕士生，在读1名博士生和1名硕士生），满足项目预期成果要求。本项目提出了一系列的球磨机研究方法和评价指标，提高了磨矿效率、降低了钢耗和能耗，为设计节能降耗的球磨机提供了基础理论和技术支撑。