变频调速在恒压供水控制系统中的应用

介绍了变频技术、变频调速的原理,变频恒压供水系统的硬件、软件设计,变频恒压供水系统控制流程,以及变频调速在恒压供水控制系统的应用.     

绕线式异步电机转子变频磁链观测研究

为改善煤矿高压变频调速的现状,分析了采用转子变频调速的优势,探讨了转子变频调速系统的实现。重点介绍转子变频调速的原理,得到了绕线式异步电机转子变频调速时的磁链方程。通过Simulink建立转子变频磁链观测模型。仿真结果表明,采用转子变频时供电电压低,输出电压谐波含量少,有利于改善传统调速系统的性能,该绕线式异步电机转子变频的数学模型是正确的。     

基于变频器BOP面板调速系统的设计与实验

以西门子MM440变频器变频调速实验为例,介绍了变频调速的原理,阐述了变频调速的技术的优点。设计了一种基于西门子MM440变频器的变频调速系统,研究了BOP面板控制下的变频调速,通过protel绘制了线路原理图。利用MM440变频器BOP面板设置变频系统参数来控制电动机,并通过实验验证了该系统可以可靠稳定性的运行。     

变频调速的原理及应用

介绍了变频调速的原理,总结了变频调速的功能、性能及可靠性,以及变频调速装置在煤矿井下防爆绞车的实际应用。结果表明变频调速系统具有很好的应用发展前景和可观的经济效益。     

变频技术在主井提升电控系统中的应用

随着变频技术的发展,传统的TKD控制方式将被全数字变频控制技术所替代。介绍了全数字变频电控系统及其控制单元,对应用前后的提升能力及安全控制能力进行了对比,阐述了全数字变频技术的6大优点,为变频技术在提升机电控上的应用提供了依据。     

一种大功率防爆变频装置研究

针对矿用变频领域的研究及使用现状,分析了大功率变频装置的设计重点、关键技术及遇到的问题,提出矿用大功率变频装置采用多机并联技术,设计了基于双机(多机)并联拖动技术的大功率防爆变频装置。变频装置通过了严格的性能试验和上海电科所对变频调速装置进行的EMC检测,各项指标均符合国家标准要求。     

浅谈空气压缩机的变频拖动

目前矿山企业在用空气压缩机的电能损耗居高不下,这种电能损耗问题可采用变频技术改善.介绍了传统压缩机压力控制方式的弊端,阐述了空压机使用变频技术的必要性,介绍了变频拖动系统的构成及其能够实现的性能,总结了空压机使用变频拖动的优点,并提出了在使用变频拖动时的注意事项.     

大型带式输送机机电耦合系统的计算机仿真研究

文章以带式输送机变频调速控制系统为研究对象,应用Matlab-Simulink仿真工具,研究了输送机在采用多滚筒变频驱动时各电动机的电流、驱动力矩特性,给出了多滚筒变频驱动的最佳控制原则,为多滚筒变频驱动的应用奠定了理论基础。     

连续采煤机行走变频系统设计及优化

介绍了连续采煤机电控系统和行走变频系统设计方案,并对行走变频系统提出了优化,以及行走变频系统方案优化时需注意的关键问题。现场应用表明:优化后的变频系统提高了生产效率,降低了故障率。     

变频控制在主煤流运输中的应用

该文介绍了变频控制系统的工作原理,以及变频控制系统在陈四楼煤矿北翼主煤流运输系统中的应用情况,并对生产过程中遇到的问题进行分析解决。通过对变频控制系统的应用效果进行分析,体现了实施变频控制改造的必要性。     

Flotation of PGM-containing minerals: Plant-wide regression and prediction of circuit performance

A crucial step in the processing of PGM-bearing reefs in South Africa is the flotation of the sulfidic minerals from the host rock. Flotation plays a crucial role in reducing the mass of material to be processed further downstream by smelting, converting and hydrometallurgical refining. However, flotation has the lowest recovery of valuable metals along the processing chain. As a result, small improvements in efficiency in flotation have an enormous benefit to the company’s performance. Modelling and simulation play an important role in circuit optimisation, due to the ability to test and examine multiple options in a small amount of time without affecting the operational circuit. Unfortunately flotation is extremely difficult to model and simulate due to the complexity of the mechanism and the large number of variables involved. Whole circuit modelling is even more difficult, for the reasons already mentioned as well as maintaining a consistent mass balance in the face of multiple recycle streams. The purpose of this work is to construct a whole-circuit model of a flotation circuit, and use the model to predict the effect of changes to the flotation circuit. A goal in the construction of the model was to use as few parameters as possible. The work presented in this paper is focused on the regression of the parameters of a first-order kinetic flotation model to actual pilot plant data. The performance of the model was then validated by predicting the behaviour of a modified flotation circuit.The regression showed excellent correlation with actual plant data on a bank by bank basis. Using the regressed parameters directly on a modified circuit configuration, the model was able to predict the circuit behaviour when compared to plant data.     

基于STIRPAT模型的山西省耕地变化研究

经济快速发展对耕地面积减少的影响,是当前土地利用变化研究领域的热点之一。本文以山西省为例,应用STIRPAT模型,分析总人口、城市化率、产业结构对耕地面积变化的影响及富裕度与耕地变化之间的相关性。结果表明：总人口对耕地减少产生线性正效应,但各城市影响强度差异明显,最大者是最小者的23倍;城市化率、产业结构对耕地面积的弹性系数均大于-1且小于0,说明这两个因素每发生1%的变化,耕地面积发生反向但小于1%的变化;在观测数据范围内,富裕度和耕地面积之间形成类似环境Kuznets曲线。据此研究认为,缓解山西省耕地面积减少的压力可从控制人口、调整产业结构等方面入手。     

铁矿石资源对我国经济增长约束的分析

21世纪以来,随着我国工业化、城镇化步伐加快,钢铁产量大幅度增长,铁矿石需求强劲。特别是2004-2009年,我国铁矿石进口快速增长,价格不断攀升。根据矿产资源约束经济增长的短期模型,通过2001-2009年我国铁矿石进出口和GDP数据,测算铁矿石资源对我国经济增长的约束,表明同期铁矿石影响我国经济增长的绝对值也不断增长。其中2004年影响GDP 0.42%,2009年达到2.92%。铁矿石资源对我国当前经济增长特别是工业增长短期约束是显著的,今后一段时期内仍将维持较强的态势。     

Bubble–particle detachment in a turbulent vortex I: Experimental

The mechanics of the detachment of particles from bubbles in the flotation process in a turbulent environment are unclear. The traditional hypothesis assumes a bubble–particle aggregate is trapped inside an eddy of equivalent size, and the attached particles rotate at the same speed as the eddy. The rotational movement subjects the attached particles to a centrifugal force. It is theorised that particles detach when the centrifugal force is greater than the capillary force, but this hypothesis has not yet been experimentally proven.This work is an experimental study of bubble–particle detachment in a rotating eddy. A special experiment was designed to obtain a strong confined vortex, and bubble–particle aggregates were introduced into the cavity without destroying the vortex structure. This newly developed method, which provides a realistic analogue of the turbulent conditions in a flotation cell, is well suited to the study of an important sub-process of flotation in a turbulent field, namely, the stability of single bubble–particle aggregates.Particles can detach from bubbles by a number of ways, including inertial actions induced by rapid changes in direction, and disruption due to coalescence of colliding bubbles. In this paper, we focus on a particular mechanism, in which bubbles are observed to rotate in a turbulent vortex. Particles can be held on the surface of the bubble by surface tension, and the radial centripetal force induced by the rotation is sufficiently high, particles may detach. Experiments are described in which the process of particle detachment due to centrifugal movement, was captured by a high-speed video camera, and the necessary physical parameters, especially the rotational velocity of the particles, were extracted. For the first time, centrifugal movement of the particle on the bubble surface inside a vortex was observed, and the theory of detachment due to centrifugal forces in the turbulent field was experimentally proven.     

The Limnology of Summer Camp Pit Lake: A Case Study

Abstract.  Surface water bodies are expected to form in several pits at the Getchell Open Pit Mine after mining has ceased due to inflowing surface and ground water. Predicting the long-term geochemical behavior of the pit water is important in assessing potential environmental effects. One of the pits, the Summer Camp Pit, began to develop a pit lake in 1991 when dewatering ceased and the pit was used to store water pumped from underground operations. This provided a field-scale opportunity to identify the controls on lake water chemistry and determine the effects of seasonal mixing events on long-term chemical behavior. During a five-year period (1996-2001), a number of physical, chemical and mineralogical characteristics of the lake were monitored with the intent of using this information as a basis for predicting long-term geochemical behavior of future lakes in the other pits. Seasonal and multiyear cycles were identified within the water column. These cycles were influenced by climatic changes and element and sediment loadings of inflow to the lake. Stratification occurred, with the metalimnion or active layer of the lake evolving from a low total dissolved solids (TDS), alkaline water to a high TDS, neutral to mildly acidic water, until turnover occurred due to density variations between the metalimnion and epilimnion, completely mixing the layers. A hypolimnion that formed has the potential to stabilize metals in the basal sediments as sulfide minerals below a chemolimnion in the lake. Longer-term events also appear to involve the hypolimnion.The monitoring program demonstrated the dynamic nature of a pit lake and how the complex limnology can affect seasonal water quality. Such considerations are important in interpreting water quality from pit lakes and in selecting monitoring data to use when constructing mathematical models for predicting changes in water quality.     

西北内流盆地地下水资源开发利用的问题及其对策研究

本文在简要介绍了西北内流盆地的地理、地质概况和水资源特点的基础上,较系统地总结了西北内流盆地水资源开发利用中存在的问题及其对生态环境的影响,其核心症结在于中游农业区大量水资源的不合理开发与低效利用,深入地分析了产生这些问题的4方面原因,并从基本理念、政策和技术方面,提出了内流盆地水资源合理开发利用与生态环境保护的战略对策：1）尊重客观规律,树立科学的水资源开发利用与生态环境保护理念;2）完善农业水利工程投资政策,促进和引导水资源的合理开发;3）充分利用山前地下水库,合理开发中游地区地下水,严格限制开发下游地区深层承压水,实现水资源的合理调控与优化利用;4）加强土地整理是有效降低农业灌溉定额的重要举措。     

Service Delivery Strategy: Trends in Mining Industries

Mine operators are increasingly outsourcing non-core business processes. Often, the maintenance issue is treated as a non-core business by the mining industry. In today's business environment, many industrial operators/users are interested in buying performance rather than physical products. It is a common practice for an original equipment manufacturer (OEM)/supplier of a product to own, operate, maintain, and support his product. Product performance in general is defined in a negotiated agreement. Even in a conventional product scenario a user/mine operator often prefers to outsource maintenance to OEMs or contractors in order to focus on core business goals. This paper reviews the recent trends in delivery of product support within segments of the mining industry. In this paper, we advocate the adoption of 'solution-selling' and 'total care solutions' into the mining industry. There appears to be a strong likelihood that these concepts can benefit the mining industry. Solution selling and total care solutions are seen as applicable to the mining industry because the product/equipment utilised in this industry are specialised and often expensive. The strategies addressed in this paper support a mine operator's option to buy processes instead of physical products, and the increasing demand for a total solution.     

Grinding operation optimization of the CODELCO-Andina concentrator plant

This paper presents results following the application of a sub-optimal control scheme, both through simulation and in situ, from the operation of Section C of the CODELCO-Andina copper concentrator plant. The algorithm permits the determination of the necessary control action at each instant of time in order to maximize a defined plant performance index. The main objective of the algorithm is to maximize the mineral tonnage processed by the section, subject to it not exceeding a predetermined value establishes! for the operation conditions of the mills, while at the same time maintaining constant the mass fraction over 65 mesh (212 [microns]) in the overflow of the hydrocyclones, at a value within the operational requirements of the flotation stage. The performance index is defined in terms of; the percentage of pulp solids fed to the hydrocyclones of each line of ball mills, penalty functions to prevent electric power to the ball mills ,falling below the lower limit (so as not to enter the overload region), the tonnage processed in the section, and, since water is a scarce resource, a term considering the water added to each sump is also included. The scheme is first studied and adjusted in a simulator of a concentrator plant similar to that used in the industrial application. For plant implementation, a PC software program, denoted CONMOL, is developed in TurboPascal for Windows. This software allows plant applications to be carried out through a communications interface. Finally, the results of two tests performed on Section C of the CODELCO-Andina copper concentrator plant are shown where the control is applied over 3 and 5.5 hours respectively.     

An evaluation of the role of particle size in the flotation of coal using different cell technologies

A large variety of new flotation cells has been introduced in the last few years, probably as a result of the successful introduction of column flotation in the minerals processing industry. In common with the column cell, a number of these new cells employ an essentially quiescent separation zone. However, a number of novel cell designs have been introduced that use agitation mechanisms similar to those employed on conventional flotation cells. The aim of this investigation was to evaluate flotation behaviour in both an agitated and non-agitated environment, particularly with respect to particle size. A hybrid ‘agitated’ column cell was designed for the investigation, and the operation of this unit was compared to that of a column cell, and to a batch flotation cell, on a laboratory scale. The testwork was conducted on coal fines, as problems with the flotation of coarse coal particles in a column cell had previously been identified. It was demonstrated that the addition of an agitated stage to a column cell can significantly improve the coarse particle recovery in comparison to the conventional column cell, while maintaining good selectivity in the fine sizes.     

煤炭资源型城市生态风险评价及预测:以鄂尔多斯市为例

 以鄂尔多斯市为研究对象,采用资料分析法、GIS空间数据处理技术,对研究区自然、社会、经济等各项指标进行分析和深入了解。在此基础上应用PSR模型,选取24个指标构建研究区生态风险评价指标体系,采用模糊综合评价法对研究区2005—2015年生态风险程度进行评价。运用BP神经网络方法构建滚动预测模型,对研究区未来5年的生态风险进行预测评价。研究结果表明：1）2005—2015年鄂尔多斯市生态风险程度经历较高（2005—2008年）、一般（2009—2011年）、较低（2012—2015年）3个水平,生态风险级别特征值随时间发展呈现波动上升的良性变化趋势;2）未来鄂尔多斯市生态风险级别特征值会有波动性下降,但整体仍将维持在较低生态风险水平,2017年鄂尔多斯市风险级别特征预测值为5894 5,处于一般风险状态,2020年鄂尔多斯市风险级别特征预测值为6026 6,处于较低风险状态;3）导致鄂尔多斯市生态风险程度恶化的压力因素主要为环境压力,具体包括工业污染物排放量等指标,状态因素主要为经济状态和环境状态,具体包括第三产业在GDP中所占比重和降水量等指标,响应因素主要为人文响应,具体包括万人在学校大学生数和万人拥有医疗机构床位数等指标。为预防生态风险程度由2017年起进一步恶化,未来应当着重控制人口发展、工业污染物排放、草原退化与沙漠化,增加医疗、教育发展的投入。