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By R. J. Matetic

The objective of this U.S. Bureau of Mines hydrologic-subsidence investigation was to evaluate the effects of longwall mining on the local ground water regime through field monitoring and numerical modeling. Field data were obtained from multiple-position borehole extensometers (MPBX's) that were used to measure subsurface displacements. Survey monuments were installed to measure mining-induced surface deformations. Numerous drawdown and recovery tests were performed to characterize hydrologic properties of the overburden strata. Coreholes were drilled above the study area to determine lithologic and strength characteristics of the overburden strata using the rock samples collected. Electronic recorders were installed on all monitoring wells to continuously monitor ground water levels in coordination with mining of the longwall panels. A combined finite element model of the deformation of overlying strata, and it's influence on ground water flow was used to define the change in local and regional water budgets. The predicted effects of the postmining ground water system determined by the model correlated well with field data collected from the fieldsite. Without an infiltration rate added to the model, a static decrease of 3.0 m (10 ft) in water level would occur due to mining of both longwall panels and if an infiltration rate was inputted in the model, no predicted long-term effects would occur to the ground water system.

Jan 1, 2010

By J. T. Nel

The establishment of a pilot plant for the continuous production of titania pigment and nano-titania is discussed. The plant was designed, constructed and operated on the Necsa site. The TiO2 production capacity is 7?10 kg.h-1 by the reaction of TiCl4 and O2at>1000°C. Liquid TiCl4 is sprayed under pressure into a plasma reactor where it evaporates and reacts with O2 to form TiO2. Process optimization has allowed for continuous production without any clogging or blockages. The primary advantage of the plasma-assisted process is the possibility to recover and recycle the chlorine values in high yield as Cl2 for use in the manufacture of TiCl4. The HCl formed in most conventional fossil-fuelled processes makes Cl2 recovery and recycling much more difficult. Particle size distribution analysis of the fine, white product revealed a d50= 125 nm. The raw product consisted of 60% rutile that could be increased to 80?100% rutile by post-annealing. The specific surface area (SSA) of the pigment was 8?20 m2?g-1(BET). According to the CIE colour index the ?whiteness? (L*>95) of the plasma-produced pigment was better than that of several commercially available pigments. The particle size could be manipulated by controlling the TiCl4 feed rate, gas flowrates, and the particle quench rate and residence time. Nano-sized TiO2 powders with a particles size (d50) as small as 50 nm were also successfully produced in this way.

Jan 1, 2010

By P. Burmeister, R. A. Errath, A. Sapin

Sag Mills are becoming bigger in size almost every year. Concentrator plants are also becoming larger with more SAG and Ball Mills units with Gearless Mill drives installed in one plant. In contradiction to this development, concentrator plants are being built in increasingly remote areas, where the power supply and network conditions are not necessarily covering the needs for the operation of such plants. This paper describes sources of harmonic distortions and possible approaches to solve this problem. It also illustrates the permissible tolerances in terms of commutation of power electronics, based on already realized installations. Furthermore it explains how, and with which measures, harmonic currents created by non-linear loads with SAG and Ball Mill drives can be handled, and how harmonic standards can be fulfilled accordingly. Finally, this paper gives an overview about the technical impact of a strong versus weak network, and the economic relationship between them.

Jan 1, 2001

By H. Kazemi, G. W. Thomas, M. S. Seth

The double-porosity model of Warren and Root7 for examining pressure drawdown and buildup phenomena in naturally fractured reservoirs has been extended to intetpret interference test results. Both analytical and numerical solutions are presented. The practicality of some of the assumptions in the Warren-Root model was also investigated. The standard procedure for interpreting interference tests in naturally fractured reservoirs beretofore employed an equivalent homogeneous reservoir model. A comparison of our results with the equivalent homogeneous model indicates the latter is inadequate for early time responses. For late time responses, however, the simpler equivalent homogeneous model yields favorable results. Finally, the effects of well spacing and the magnitude of the interporosity flow parameter are briefly cited. INTRODUCTION Interference tests can be used to provide reservoir information not obtainable from conventional pressure drawdown and buildup tests. The technique involves measuring the response in one or more wells arising from a pressure perturbation introduced into another well. It has been. successfully applied to single-layer, homogeneous, unfractured, isotropic and anisotropic formations to arrive at values of well storage capacity and a measure of directional permeability.l The techniques of interference testing usually can be extended to heterogeneous systems, provided the permeability contrast between any existing rock layers is not excessive.9 In such cases, the practical interference effects in an observation well of an interconnecting heterogeneous reservoir can be predicted using an equivalent homogeneous model. The calculated properties are then average values. Russell and Prats2 have demonstrated the utility of this approach for a single-phase, two-layer system. For naturally fractured reservoirs, some different approaches usually are necessary. The major departure from homogeneous or nearly homogeneous reservoir treatment is to characterize the fractured system as an entity having "double-porosity"; namely, we suppose the existence of both primary and secondary porosity, where the former is contained within a systematic array of identical rectangular matrix blocks and the latter is contained within an orthogonal system of continuous, uniform fractures (see Fig. 1). It is sufficient to assume that the permeability of the rock matrix is so small that movement of reservoir fluids to the producing wells is entirely through the fracture network. This assumption has been validated by Barenblatt3 and .employed by others?-7 Warren and Root7 used the double-porosity model to develop an interpretation of pressure drawdown and pressure buildup tests in naturally fractured

Jan 1, 1970

By Felix E. Mutschler

Alkaline rock-related precious metal deposits include: • orthomagmatic platinum group elements (PGE) ± gold (Au); • porphyry copper-silver-gold (Cu-Ag-Au, ±PGE); • epithermal Au-only, and Au-Ag-base metals; • submarine exhalative Kuroko-, Cyprus-, seamount- and Yellowjacket-type deposits; and • enigmatic deposits akin to Olympic Dam. Coeval epithermal deposits related to porphyry deposits suggest the two types represent separate immiscible fluids evolved in oxidized, CO2-rich alkaline magma chambers. Alkaline rock provinces develop above mantle hot-spots, but crustal structures control the final distribution of magmas and ore fluids. Prospecting guides for alkaline rock-related precious metal deposits include the presence of evolved alkaline rocks, pervasive K-metasomatic, redox and carbonatic alteration and low level Au (±Te, etc.) anomalies. Although alkaline igneous rocks crop out in less than 1 % of the area of the North American Cordillera and craton, alkaline rock-related ore deposits have produced nearly 13% of the total United States and Canadian lode gold production. Large (31-t or 1 million-oz) deposits are common (Fig. 1), and additional deposits and reserves are being discovered. New genetic models are evolving, making alkaline rock-related precious metal prospects attractive exploration targets.

Jan 1, 1991

Python Underground Processing Plant Critical Design The use of continuous gravity recovery in combination with a controlled breakage fine crushing and screening system followed by flash flotation has been incorporated into the Python processing plant. This provides miners with a flexible, robust, low cost, low energy pre-concentration process for the recovery of gold and/or heavy minerals. The Python plant incorporates fine crushing utilizing either High Pressure Grinding Rolls or Vertical Shaft Impactors in combination with the InLine Pressure Jig and Flash Flotation to continuously liberate and recover the valuable minerals. The use of these technologies has enabled a narrow, transportable pre-concentration plant to be produced which can easily be installed and operated in underground drifts and tunnels.

Sep 13, 2010

By Suresh K. Bhatt

This U.S. Bureau of Mines report reviews major developments in continuous haulage technology for underground coal mines. Haulage systems, both in use and under development, were investigated through a comprehensive literature search and visits to mines and manufacturers. The systems include flexible conveyor train, mobile conveyor, monorail bridge conveyor, multiple-unit continuous haulage, extensible, and belt turning systems. Strengths and weaknesses of the systems are assessed in light of their operating under remote control and their application to the computer-assisted continuous mining machine research being conducted by the Bureau. Through mining scenarios, candidate haulage systems are conceptualized to be consistent with the capabilities of the mining machine.

Jan 1, 1991

By C. Cunningham

The process of initiating opencast blasts through long cables is onerous. An obvious alternative is to replace these with radio controlled firing apparatus. Such devices appear from time to time and with the advance of telecommunications, more are likely to appear. However, there are two crucial and seemingly intractable obstacles to overcome: firstly, the problem of malfunction of the system, which can either fire prematurely or go into a state of suspense in which it is unknown whether firing might unexpectedly occur, and secondly, the problem of terrorism, as such a system could provide the capability for an off the shelf remote bomb. The issues of accessibility and electronic reliability when linked to explosives in a mining environment have to be demonstrated to be adequately covered before serious consideration should be given to these systems, up to now largely confined to military applications.

Jan 1, 2003

By T. P. Williams, M. B. Rydzewski, B. Corner

Konkola Copper Mines (KCM) plc is an integrated copper producer operating on the Copperbelt in Zambia. KCM has numerous mining operations located in the towns of Chililabombwe (Konkola Mine), Chingola (Nchanga Open Pit and Underground operations), Lusaka (Nampundwe Mine), with a smelter located in Kitwe (Nkana Smelter) and an SX-EW plant in Chingola (Nchanga Tailings Leach Plant). [ ]

Jan 1, 2005

By K. Lundholm, A. E. Mäkinen

"Ore grades are declining and getting more complex around the world which not only complicate the ore processing but also produce new type of requirements to manage the produce waste streams. One specifically problematic and increasingly identified element in waste streams produced in mining and metallurgy is arsenic.Arsenic is a compound that has no significant market value, but that needs to be removed from ores, concentrates and other process streams because of environmental or process technical reasons. One example of a removal process is partial roasting of high-As sulfide concentrates, originally developed by Outotec. In this process the arsenic is volatilized in the gas phase and thus separated from the solid material, i.e. the calcine. If the arsenic is recovered by wet methods the process gas is quenched and all arsenic needs to be stabilized in the effluent treatment plant.Outotec has developed ferric arsenate precipitation as a method to produce stabile arsenic residues from wet gas cleaning effluents. Iron based precipitates, when correctly produced, can meet typical landfill criteria measured with different types of leaching methods meant for characterizing the arsenic dissolution behavior from the precipitates.In this paper partial roasting of sulfide concentrates with arsenic volatilization in combination with ferric arsenate precipitation is discussed from the perspective of producing wastes that can meet the stability requirements set by common leaching tests methods, TCLP and CEN. These leaching test methods set the normative landfill requirements for most operations generating arsenic containing wastes. A typical flow sheet of Outotec® Ferric arsenate process is discussed with results showing the importance of correct process control and sequence on producing arsenic containing waste that can meet the landfill disposal requirements."

Jan 1, 2014

By Bradley Stoughton

It is very easy to reduce iron ore at a temperature well below its melting point and produce a more-or-less-pure metal which can be used directly for implements, tools, or machines. This simplicity has been the cause of much money loss by persons who were so satisfied with the successful operation of a process that they paid all too little attention to the commercial aspects of it. How easy a direct process is may be gleaned from the fact that it was practised with some -success by primitive man, and has been in almost continuous operation in one form or another for a period of probably 4,000 years. The production of steel in ton lots, beginning about 1860, brought a new phase into the economic situation, which, however, had been already greatly modified in 1784 by Henry Cort's invention of purifying pig iron. Direct processes survived both of these revolutions, under special geographical conditions, even up to the last few years of the nineteenth century, but ceased to have any general use as the basis of supply for structural, machine, or tool industries even in countries which could have manufactured iron by a direct process, but, instead, imported the product of established iron and steel processes. And this is still the situation today, notwithstanding the invention of an incredible number of 'new' processes since 1900, most of which are abandoned, and only survived as along as their financial backers were willing and able to Jose money. Probably none of these processes failed to work pretty well, and all seemed to show a handsome profit on paper.

Jan 1, 1930

By R. D. Brown

"Concerns over possible additional involvement of governments in Canada's mining industry and its adverse effects on the industry 's growth were a frequent topic of conversation at the recent Annual General Meeting of the CIM.Still painfully fresh in the minds of industry leaders are the disastrous results of the federal/provincial scramble over resource revenues which followed the relatively high metal prices witnessed in 1973/1974. At current metal prices, it is not surprising, then, that a nagging fear persists that these governments may once again restructure tax and other rules to the detriment of the industry and the country.This month, Tax Notes recalls some of the progress which the industry and governments have made in 1979 in the taxation of the resource sector, and urges that higher metal prices be viewed in light of the costly exploration, development and production efforts which will be required for the industry to continue to play its important role in our economy.IntroductionAt the Annual General Meeting of The Canadian Institute of Mining and Metallurgy, held in April, 1980, it was abundantly clear that there is widespread concern in Canada's mining industry that this country's tax regime may once again be blasted by ill winds of change.A stable and more favourable tax climate, as well as higher metal prices and profits, made 1979 almost a golden year for Canadian mining. However, from the tax viewpoint at least, there are some spots on the silver lining as apprehensions grow that the well-heralded battle between federal and provincial governments over oil and gas may spread to the mining sector, with serious damage to the industry and its newfound federal-provincial cooperation."

Jan 1, 1980

By Robert Giglio

Looking back over the last 150 years or so, it is not hard to see that electricity has been a primary force in shaping human development. It has been a basic ingredient in our industrial revolutions that simultaneously improved the productivity, working and living conditions within our farms, factories, hospitals, offices and homes. Today, it has become an essential part of our daily life and our future. Amazingly, we keep finding new ways to use electricity to make our lives more safe, comfortable and productive. It is a great success story of human ingenuity, achievement and development. Demand for electricity The convenience and value of electricity has not gone unnoticed by consumers. According to the U.S. Department of Energy (DOE) (Energy Information Administration, 2009), electricity is the fastest growing form of energy in the world and during the next 20 years the world will likely consume twice as much of it as it does today. In 2008, almost 20,000 terawatt hours of electricity globally were consumed (Energy Information Administration, 2009). That is enough electricity to light up more than two million baseball stadiums or power more than 11 billion computers continuously for an entire year. The United States has the dubious distinction of be-ing the largest consumer of electricity in the world with enough power to provide each American with more than 3 kW of electricity ? that is about twice the power currently available to Europeans, eight times the power available to the Chinese and more than 25 times the power available to the citizens of India (American Coal Foundation, 2009).

Jan 1, 2009

By Meng Li, Hao Nie, Weitian Ding, Mamdouh Omran, Ying Li, Yao Ge, Yaowei Yu, Abourehab Hammam, Lei Zan

This study examines the isothermal and non-isothermal reduction behaviors of iron ore compacts in a pure hydrogen atmosphere and compares the results obtained during the reduction process by CO. The different phases accompanying the reduction reactions were identified using X-ray diffraction (XRD) and its morphology was microscopically examined. In isothermal experiments, temperature plays a significant role in the reduction process. At any given temperature, the reduction rate during the initial stages is higher than that during the final stages. The reduction rate in H2 atmosphere was faster than in CO gas. The comparison of activation energy values suggested that reduction with H2 is more efficient thanwith CO. At the same temperature, the time required to achieve a certain degree of reduction was lower when using H2 gas than CO atmosphere. In non-isothermal tests, the heating rate has a significant effect on the reduction rate and reduction extent. At the same heating rate, the degree of reduction was higher in H2 atmosphere than in CO gas. Based on experimental data, the parameters of reaction kinetics were deduced by application of model-free and model-fitting methods. The reduction in H2 atmosphere was controlled by nucleation model (Avrami-Erofeev model), while the CO reduction reaction was controlled by gas diffusion.

Sep 29, 2020

By Damian Connelly

The metallurgical heart of the majority of copper oxide processes is the heap leaching operation. Fresh low grade sulfide ores is a far greater challenge.The success of this unit operation is so important that operators need to understand the ramifications of their decisions or non-decisions and how they could affect the downstream processing. Heap leaching is an operation that can be described as a scientific art whereby principles of science can be used to guide experienced personnel in attaining their goals. Recent advances have been made based on better understanding the ore characteristics. The success of a heap leach operation, or otherwise, is dependent upon a number of factors, notably: The type of ore to be treated The extent of testwork completed to define the process The interpretation of the testwork results Ore preparation prior to stacking Agglomeration and curing requirements Other issues are: Compliance with the ’smaller’ requirements of environmental authorities Adequate and timely drainage of solution from the base of a leaching lift The degree of saturation in the pads Heap porosity – coarser or finer ore, which is better? Higher or lower irrigation rates – which would produce a better result? Laying out irrigation pipework for ease of operation and maintenance The addition of water, raffinate during agglomeration where needed The heap leaching of sulfide ores, including chalcopyrite, via enhanced bacterial leaching is discussed. INTRODUCTION Over the last twenty years, production of extremely pure copper from solvent extraction and electrowinning (SX/EW) has become more common in a market of real declining prices for copper metal. This paper touches on a number of heap leach operations and experiences. These projects were subjected to extensive engineering design and resulted in low capital cost, efficient operations with a number of lessons learned. The key to these operations was the performance of the heaps and associated fluid collection systems rather than the plants themselves.

Jan 1, 2019

By S G. Li

Mine intelligent ventilation is an important guarantee to realise intelligent mining. It is the integration of the Internet of Things, big data, artificial intelligence, internet, cloud computing with ventilation technology, forming a complete ventilation system with intelligent perception, intelligent decisionmaking, intelligent emergency response and airflow control. In order to fully grasp the progress and trends of mine intelligent ventilation research in western China. The paper based on literature analysis and field application research, comprehensively expounds the main research and practical results of mine intelligent ventilation in western China, mainly analyses the development status of key technologies such as accurate and rapid determination of mine ventilation parameters, intelligent analysis and decision-making of ventilation and intelligent regulation of ventilation equipment, and introduces the field test or application of mine intelligent ventilation technology in western China. It lays the foundation reference for related research and improving the intelligent level of mine ventilation.

Oct 12, 2022

By Jack Kadlecik

This final technical report describes the concept feasibility study, testing, design and development effort which went into. The quick opening enclosure access cover and flame path tolerance checking system. A detailed definition of the explosion-proof multiple start threads is shown for two (2) sized electrical enclosures.

Jan 1, 1972

By W. G. Phillips

This report presents results from a study whose objective was to evaluate noise control options for existing equipment used in metal and non-metal processing plants. This equipment performs 3 basic functions, crushing, grinding to a point where the product can be liberated from the waste, and agglomeration A the product. Specifically, the study was directed towards taconite processing since the extreme hardness of taconite results in high noise levels and in considerable maintenance of the processing equipment. Both of these factors make this process a very challenging noise control task. Plants processing other ores use similar equipment, consequently the results of these studies should he applicable to a wide variety of plants. The report presents the source diagnosis and potential retrofit noise control treatments for fine screens, mills, crusher sizing screens, and vacuum disc filters. Estimates are make of the noise reduction from each treatment. The report concludes with recommendations for future research on each piece of equipment.

Jan 1, 1978

By P. Kerr

Iron segregation is pre-dated by copper and nickel segregation processes for which the experimental methodology and reaction chemistry were established. The accepted reaction sequence for segregation involves the generation of hydrogen chloride, the chloridization and volatilization of the metal chloride, and precipitation of the metal from the metal chloride in the vicinity of carbon. Iron segregation roasting offers a potential extraction solution for processing oxide deposits with complex mineralogy or waste streams such as Minette-type iron deposits, nickel laterites, ilmenite, red mud, electric arc furnace (EAF) dust, mill scale and slag. After subsequent magnetic separation, one is left with a high grade metallic iron powder which can be marketed for powder metallurgy or briquetted to serve as a direct reduced iron (DRI) product. The non-magnetic product is typically concentrated oxides including rutile, alumina, or oxides of V, P, and rare earths, etc. that may be economically recoverable with subsequent processing. While operating conditions vary for different metals, they share the requirements of an elevated operating temperature and a mixture of oxide ore, carbonaceous additive and a chloride additive in varying amounts all in a closed reactor to allow for reducing conditions and contain the volatile chlorides. This process is then followed by some form of physical separation. Testwork performed by the authors shows promising results that may aid in future development of the process. Segregation roasting of iron will likely never displace traditional beneficiation and ironmaking technologies; however, it has great potential in niche markets where traditional technologies have failed or current technologies generate substantial waste.

By K. A. Lewandowski

Leach heaps are plagued with problems due to fine material migrating downwards, clogging the spaces between the coarser ore particles, resulting in decreased metal recovery rates. The use of a binder in agglomeration would allow the fine material to be immobilized, increasing the availability for the solution to come in contact with all the ore. As much as 1.64*1012 BTU per year would be able to be saved if a 25% increase in copper recovery was experienced, assuming that 70% of heap leaching units converted to using agglomeration technology. This is equivalent to approximately 18% of the energy currently being used in leaching heaps.

Jan 1, 2008