深部蓄冷充填体释冷相变行为与协同降温机理研究

The problem of the heat hazard has become increasingly prominent with the increase of mining depth. Seeking an economical and environmental cooling method for stopes which is suitable with mining characteristic, and exploring the synergetic cooling mechanism under the conditions of high geotemperature and high geostress are major problems in exploiting deep mineral resources. An academic thought of ‘cold storage-phase change and cooling’ on the basis of the characteristics of filling-mining method was proposed in this application. By adding the phase change materials (PCMs) with the function of cold-storage to the filling slurry, the PCMs change phase and absorb heat in the goaf to cool the adjacent stope. The project plans to carry out the following research: a) By the multi-objective decision target of flow, heat transfer and strength characteristics, design and optimize the cold storage backfill material with the function of cooling by phase changing based on the solid waste of mining; b) Starting with the physical properties of PCMs, develop two different scale researches by crystallization kinetics and heat transfer, build the population balance model for revealing the phase change behavior of the PCMs in the composite backfill, and build the heat transfer model for exploring the evolution law of cold capacity of backfill in time and space in the phase change process; c) Using the thermal-mechanical coupling method to establish the synergistic cooling mathematic model of backfill region- surrounding rock region- stope region, in order to reveal the synergistic cooling mechanism and evaluate the stope cooling effect and energy utilization efficiency. This project is significant in exploring the cold release phase change mechanism of cold storage backfill, solving the synergistic cooling problem in deep mine, and realizing sustainable exploitation of deep mineral resources.

矿井采深的增加导致热害问题日益突出，寻求与开采特点相适应的经济环保的采场降温方法，探究高地温、高应力条件下的协同降温机理是深部矿床开采亟待解决的问题。本申请结合充填采矿方法特点，提出“蓄冷-相变降温”思想，将具有蓄冷功能的相变材料添加到充填料浆中，在深井内相变吸热以实现对临近采场的降温。项目拟开展以下研究：①以流动、传热、强度特性为决策目标，设计并优选基于矿山固废基质的蓄冷相变降温充填材料；②从相变材料的物理特性着手，采用结晶动力学与传热学从两种尺度开展研究，建立群体平衡模型以揭示相变材料在复合充填体中的释冷相变行为，建立传热模型以探寻相变过程中充填体冷量衰变时空演化规律；③采用热-力耦合方法建立充填体区-围岩区-采场区的协同降温数学模型，揭示协同降温机理，评价采场降温效果与能源利用效率。本项目对探索蓄冷充填体释冷相变机理，解决深部矿井协同降温问题，实现深部矿产资源可持续开采具有重要意义。

项目紧密围绕蓄冷充填体在深部矿井热害治理中的传热特性与降温能力开展研究，完成了基于矿山固废基质的蓄冷相变降温充填材料设计与优选，探明了蓄冷相变充填材料释冷相变行为与冷量衰变规律，揭示了蓄冷相变充填体协同降温机理与温控效能。（1）结合深井降温需求与充填采矿特点，提出了蓄冷功能性充填降温方法，研究了该方法的总体实施方案，分析了该方法较之传统矿井降温方法的优势。通过分析常用相变材料特征，综合考虑其导热特性、相变温度、潜热量，并结合经济、环保等方面因素，选取了冰粒作为蓄冷充填料浆中的相变材料；综合考虑流动、传热、强度特性，设计并优选了基于矿山固废基质的蓄冷相变降温充填材料。（2）通过实验和数值传热研究了相变材料在充填体中的释冷相变行为，建立了多孔介质-焓法-水化放热的蓄冷相变充填体传热复合计算模型，研究了相变过程中充填体冷量衰变时空演化规律。为优化模型计算效率，探索了基于RC模型的蓄冷充填体相变传热计算方法，在保证计算准确性的条件下，大幅提高了计算效率。（3）针对井下多区域传热耦合问题，建立了充填体区-围岩区-采场区的协同降温数学模型，分析了初始液相率、充填体料浆浓度和充填策略对冷却性能的影响，研究了不同充填方式下蓄冷功能性充填体的降温性能，揭示了蓄冷相变充填体协同降温机理，采用无量纲温度和表面传热系数进行了采场降温效果与能源利用效率的评价。项目研究通过对蓄冷充填体释冷相变机理的探索，为高效解决深部矿井协同降温问题，实现深部矿产资源可持续开采奠定了理论基础。