Evaluating the impact of auxiliary fan practices on localised subsurface ventilation

Mines are continually expanding in size and depth, leading to an increased reliance on localised subsurface ventilation systems. The use of underground auxiliary fans is a favoured method to increase and control airflow in working areas. However, the effectiveness of auxiliary fans in this regard is not clear. This paper evaluated the performance of these underground fan systems in four different South African deep-level gold mines. A total auxiliary fan system efficiency of 5% was found across six systems, with the average fan efficiency of 33 fans at 38%. The results showed that these fans deviate significantly from their design operating points. Therefore, there are significant shortcomings in current underground fan practices. Our detailed investigations led to the conclusion that the assemblage of underground auxiliary fan systems results in significant energy inefficiencies. Therefore, maintaining good underground fan practice such as optimal fan selection, ducting design and maintenance is crucial for the efficacy of a mine ventilation network.     

Application of ventilation management programs for improved mine safety

The purpose of ventilation management systems is to ensure the health and safety of underground workers by creating and incorporating structured plans, procedures and processes on the day-to-day operations of the mine ventilation system. The application of ventilation management programs consists of audit, verification, and corrective action procedures to:(1) ensure adherence to regulatory standards,or to(2) return to compliance and safety standards when an upset condition arises. This paper describes how a ventilation management program can be developed and implemented to ensure regulation compliance, to increase safety, to improve operational efficiency and to reduce the operating costs of an operating mine. Two case applications are presented in this paper. The first case is presented to demonstrate use of a ventilation management program in response to a site inspection and audit, with follow-up application of corrective actions. The second case application describes how air quality conditions has been substantially improved with the development and implementation of a ventilation management program for an operating underground hard rock mine.     

Stability of multiple fans in mine ventilation networks

In large mines, single fan is usually not enough to ventilate all the working areas. Single mine-fan approach cannot be directly applied to multiple-fan networks because the present of multiple pressures and air quantities associated with each fan in the network. Accordingly, each fan in a multiple-fan system has its own mine characteristic curve, or a subsystem curve. Under some consideration, the conventional concept of a mine characteristic curve of a single-fan system can be directly extended to that of a particular fan within a multiple-fan system. In this paper the mutual effect of the fans on each other and their effect on the stability of the ventilation network were investigated by Hardy Cross algorithm combined with a switching-parameters technique. To show the validity and reliability of this algorithm, the stability of the ventilation system of Abu-Tartur Mine (one of the largest underground mine in Egypt) has been studied.     

Partition airflow varying features of chaos-theory-based coalmine ventilation system and related safety forecasting and forewarning system

To realize real-time monitoring and short-term forecasting and forewarning of coalmine ventilation systems(CVS), in this paper, we first established a joint surface and underground CVS safety management system consisting of main ventilation fan, safety-partition linked passageways, and air-required locations. We then applied chaos theory to identify the air quantity and gas concentration of underground partition boundaries, and adopted a fixed data quantity, multi-step progressive, weighted first-order local-domain method to setup a chaos prediction model and a CVS safety forecasting and forewarning system formed by the normal change level, orange forewarning level, and red alarm level. We next conduct the on-field application of the system in a coalmine in Jining, Shandong, China. The results showed that (1) in the statistical scale of 5 min, the changes in both air quantity and gas concentration along CVS partition airflow boundaries were characteristic of chaos and could be used for short-term chaos prediction, and the latter was more chaotic than the former;(2) the setup chaos prediction model had a higher prediction precision and the established safety prediction system could not only predict the variation in CVS stability but also reflect the rationality of underground mining intensity. Thus, this CVS safety forecasting and forewarning system is of better application value.     

矿井通风系统的二级模糊综合评判

采用二级模糊综合评判法对矿井通风系统的质量进行综合评价，确定了矿井通风系统的质量级别，从而使不同的矿井通风系统具有可比性．     

喷流诱导通风在地下复式汽车库中的应用

地下复式汽车库与普通地下汽车库的区别在于车库层高大、存车数量多。车库层高的增加会增大排烟量,存车数量的增多会增加车库通风换气量,进而加大通风、排烟管道的高度。而减小通风、排烟管道高度成为降低车库层高、减少工程造价最简捷的方法。为解决好这两者之间的矛盾,笔者将喷流诱导通风引入地下复式汽车库的机械通风系统设计中,并从工程造价、施工方法、节省能源、空气品质等几方面对喷流诱导机械通风系统与传统通风、排烟合用系统进行比较。     

大冶铁矿尖林山车问井下通风系统改造

为了解决大冶铁矿尖林山车问井下通风系统中存在的主扇能力不足、矿井总风量不足、采区通风困难、系统外部漏风等问题,通过现场调研,提出了对通风系统风网结构和主扇设置等进行技术改造的方案．首先采用斯科特·辛斯利（Scott-Hinsley）回路解算方法进行分网分析,开发了矿井通风系统软件（MvnetVersionl．4）,并根据井下各中段作业面需风量,应用该软件进行了通风网络解算．然后通过软件解算和风机特性曲线拟合,获得了一组风机效率75％以上,满足各中段作业需求的井下通风系统的解算结果,并确定了额定功率、叶片角度、风量和风压等风机运行基本参数．最后根据解算结果,提出对矿井通风系统关键部位采用增阻和辅扇等技术进行风量风压调节,以满足井下各中段作业需风量要求．通过技术改造,提高了矿井安全性,节约了通风费用,产生了较大的经济和社会效益．     

Applications and verification of a computational energy dynamics model for mine climate simulations

A complete thermodynamic model is described for temperature and heat flow distribution simulation for ventilation networks in underground mines. The method is called the Computational Energy Dynamics(CED) model of the heat, mass, and energy transport. The Thermal and Humidity(TH) transport elements of the full model are described for advection, convection, and accumulation, encompassing heat capacity,radiation, latent heat for evaporation, and condensation in the airways, as well as variable heat conduction and accumulation in the rock strata. The thermal flywheel effect for time-dependent temperature field applications is included in the model solution. A CED model validation exercise is described, directly evaluating the iterated, minimized energy balance errors for the mechanical and thermal energy components for each network branch after a converged solution is determined. A simulation example relevant to mine safety and health is shown with the CED-TH model, demonstrating its capabilities in efficiency and accuracy in comparison with measurement results.     

Optimal use of mobile cooling units in a deep-level gold mine

The South African gold mining sector remains a significant contributor to the country's economy. Facing several challenges that hinder the realisation of South Africa's full mineral potential, the sector's sustainability and profitability can be enhanced through implementing operational improvement measures.Mobile cooling units(MCUs) were identified as a potential focus area for operational improvement.MCUs are used as tertiary or in-stope cooling in hot underground workings. In this paper, a method was presented to characterise the performance of existing MCUs based on three key performance indicators(KPIs), namely, the wet-bulb temperature ratio(WTR), efficiency and position. Optimisation strategies were then elected and implemented based on these KPIs. The implementation of this method in a South African gold mine attained a reduction in pumped water volumes, reduced operating costs through electricity cost savings and improvements in underground ventilation air temperatures.     

Wind-Thermal Environmental Characteristic of Multi-Variable Passive Enhanced Natural Ventilation System for High and Large Space Building

Natural ventilation effects in high and large space buildings of tropical areas greatly affect the air conditioning energy consumption. Aiming at nearly zero energy building design, this paper mainly contributes to provide theoretical basis and reference for thermal comfortable air conditioning system design of high and large space buildings. Taking a theatre in Hainan as study object, a newly composite enhanced natural ventilation system is proposed by integrating the underground tunnel-based earth to air heat exchange system and the solar chimney. Ventilation quantity, air velocity and air temperature field, human vertical temperature gradient difference under 24 simulation working conditions are considered and analyzed by using ANSYS Fluent. For the underground tunnel, results show that Group Two with double underground tunnels and side air supply location shows its advantages in cooling effects and air supply uniformity. Then for the solar chimney, results show that the solar radiation intensity contributes to larger difference in transmission power and leads to different cooling effects. On the whole, the system under working condition No. 7 with 120 m long, side air supply, double underground tunnel and 20 m high, 1 m wide, 0.6° absorber plate angle solar chimney shows its priority in better comprehensive performance.     

地下停车场无风道透导通风系统性能及经济性分析

分析了无风道诱导风机射流通风的基本原理,对地下停车场采用无风道诱导通风系统与采用传统通风系统的方式进行比较,结合工程实例对两种通风系统进行经济性分析.结果表明无风道诱导通风系统用于地下停车场通风具有较大的优势,结论为地下停车场通风系统设计提供参考依据.     

高层建筑地下汽车库机械通风与排烟系统选用方案探讨

根据最新的汽车库设计规范，对地下汽车库通风排烟的几种可行方式进行了比较，考虑节能和通风排烟的需求，提出用双速风机方案满足高峰和非高峰时的排风要求，并采用适当的控制转换兼用于机械排烟，使两者联合使用达到最优。     

Prediction of air flow,methane, and coal dust dispersion in a room and pillar mining face

In underground coal mines, uncontrolled accumulation of methane and fine coal dust often leads to serious incidents such as explosion. Therefore, methane and dust dispersion in underground mines is closely monitored and strictly regulated. Accordingly, significant efforts have been devoted to study methane and dust dispersion in underground mines. In this study, methane emission and dust concentration are numerically investigated using a computational fluid dynamics(CFD) approach. Various possible scenarios of underground mine configurations are evaluated. The results indicate that the presence of continuous miner adversely affects the air flow and leads to increased methane and dust concentrations.Nevertheless, it is found that such negative effect can be minimized or even neutralized by operating the scrubber fan in suction mode. In addition, it was found that the combination of scrubber fan in suction mode and brattice results in the best performance in terms of methane and dust removal from the mining face.     

Closed-loop bulk air conditioning:A renewable energy-based system for deep mines in arctic regions

With depletion of shallow deposits, the number of underground mines expected to reach more than 3 km depth during their lifetime is growing. Although surface cooling plants are mostly effective in mine airconditioning, usually secondary cooling units are needed below 2 km depth. This need emerges due to the elevated thermal impacts caused by auto-compression of mine air as well as heat emissions from strata and mine machinery. As a result, in cold climates, like Canada, ultra-deep mines need their secondary underground cooling plants running year-round while the intake air must be heated to protect the sensitive machinery and liners from freezing during the winter season. To cool mine air, horizontal bulk-airconditioners with direct spray cooling systems are commonly used due to their high performance.Conventionally, sprayed water in bulk-air-coolers are mechanically circulated and refrigerated in coupled refrigeration plants. This set up can be transformed to a natural cooling/heating process by resurfacing the warm underground bulk-air-cooler spray water for mine air heating on the surface and re-sinking the chilled water for cooling in the underground bulk air coolers. This could significantly cut-down the fossil-fuel consumption in burners for mine air pre-conditioning and refrigeration cost when applicable.This paper presents an anonymous real-life example to study the feasibility of the proposed idea for an ultra-deep Canadian mine.     

多级模糊模式识别模型在铀矿井通风系统中的应用

模糊模式识别，是对指标在模糊标准下的类别进行判定的方法。铀矿井通风系统评判标准是一个多级模糊范围，应采用多级模糊模式识别模型。应用该模型对抚州铀矿某矿井通风系统在调整前后的级别进行了评判。     

Numerical study on DPM dispersion and distribution in an underground development face based on dynamic mesh

In 2012, the International Agency for Research on Cancer(IARC) classified diesel particulate matter(DPM)as a carcinogen to human. With the increased usage of diesel equipment in underground mines, miners have a high risk of over-exposure to DPM, which has drawn many concerns from the public. This study used computational fluid dynamics(CFD) to analyse the DPM dispersion and concentration distribution characteristics in an underground development face based on an onsite experiment. The DPM emitted from a moving loader under a forcing auxiliary ventilation system was simulated. The motion of the load-haul-dump(LHD) in the tunnel was represented by a dynamic mesh method. The species transport approach was applied to study the DPM behaviours. High DPM concentration zones were then identified based on the simulation results. The results could provide guidelines for work practices and be helpful to an optimum auxiliary ventilation design to reduce underground miner exposure.     

衡量生产矿井通风系统质量指标的探讨

从衡量生产矿井通风系统质量的基本内容出发，按照选取质量指标的四个原则，确定了全面评价生产矿井通风系统的质量指标，并提出了相对通风成本比等概念。     

住宅小区地下汽车库通风设计

地下汽车库已成为住宅小区的一个重要组成部分。本文介绍了自然通风 机械排风兼排烟系统相结合的地下汽车库通风设计,探讨了通风兼排烟系统在转换过程中各部件的控制方式。     

自动喷水作用下地下车库火灾诱导通风模拟

随着城市地下车库的不断修建,地下车库的火灾安全显得尤为重要.目前越来越多的地下车库采用诱导通风系统来控制火灾烟气,为了研究自动喷水作用下诱导通风系统的烟气控制效果,采用火灾模拟软件FDS对地下车库发生火灾时的温度场和开启的喷头个数进行了研究.模拟结果表明采用诱导通风系统,可以使着火车辆上游的烟气大大减少,有利于消防队员从上游进入灭火.同时在诱导通风作用下,喷头启动的个数也大大减少,从而使自动喷水系统能够保持正常工作.     

矿山进风井风温变化规律探析

矿井井下气温高低是影响矿井通风方案选择的重要因素之一。通过对矿山通风系统进风井井筒中气温预测模型和预测数值的分析，得出了在一定的围岩热物理条件下，进风井井筒气温随井口气温、风量、井深等因素变化的基本规律。