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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

To gather additional field data from the western United States, researchers from the National Institute for Occupational Safety and Health (NIOSH) installed an array of field instrumentation at a longwall coal mine in Central Utah. The purpose of this field site was to monitor ground movement and changes in pressure during mining where conditions include massive, stiff overburden and relatively deep cover. To accomplish this, field instrumentation was installed in the two-entry gate road between the fifth and sixth longwall panel in the current mining district.

Jan 7, 2020

By Terry A. Kirk

"This paper describes Derrick High Frequency Vibrating Screens and their process performance in grinding circuit applications. The benefits of screen sizing in closed circuit grinding are illustrated by case histories from a wide spectrum of mineral industries.INTRODUCTIONHigh capacity, reliable wet screening equipment is increasingly in demand by the mining and allied industries for separations finer than 1/.7 5mm (I/ mesh). The continuing search for improved energy efficiency and reduced steel consumption in comminution has Jed to greater scrutiny of every aspect of circuit design and operation, including the classifier efficiency (selectivity) function.Derrick Manufacturing Corporation has been developing high frequency screening machines designed specifically for grinding circuit applications since 1973. Successful installations are currently operating in iron ore, copper, coal, uranium, phosphate and other extractive industries."

Jan 1, 1984

By K. H. Coats, M. H. Terhune

Analysis and example applications have been performed to compare the accuracy and computing speed of alternating-direction explicit and implicit procedures (ADEP and ADIP) in numerical solution of reservoir fluid flow problems. ADIP yields significantly greater accuracy and requires about 60 per cent more computing time than ADEP, not 300 or 500 per cent more as reported elsewhere. l,2 INTRODUCTION Several recent papers 1-3 discuss an alternating-direction explicit difference approximation (ADEP) to the diffusion equation. Example applications of ADEP and ADIP4 were reported to support conclusions that ADEP is comparable in accuracy to ADIP and requires one-fifth to one-third the computing time of ADIP. Applications of ADEP in calculation of two-phase flow in reservoirs was also proposed. 3 This study was performed to compare further the relative merits of ADEP and ADIP in simulation of two-dimensional flow of one and two fluid phases in reservoirs. Since two-phase flow equations are often essentially elliptic rather than parabolic, the efficiency of ADEP in solving the elliptic equation was also examined.

Jan 1, 1967

This paper provides an overview of possible approaches for structuring the ventilation systems for mines that will become operational within the next decade. Features addressed in the paper include: aspects of airway design and layout in the absence of centralized vertical return shafts, the impact of using diesel-powered trackless equipment in conjunction with conveyor belts in the development and production phases of the project, and the need to balance increasing electrical power costs against the requirement for reduced capital expenditure. The paper provides brief descriptions of the strategies employed in real-life situations and presents an overview of various operational parameters affecting the design of ventilation systems that will be used as ?platforms? for much deeper mines in the future.

Jan 1, 2007

By D. P. Roberts

The stoping of platinum orebodies in the Bushveld has in the past been accomplished by using in-stope pillars to ensure stability of the workings. In the future, the use of continuous mining machines to mine the platinum orebodies is probable. It is not envisaged that such machines will cut in-stope pillars. This paper describes the alternative support systems that will replace the pillars and the stope geometries that will be required for this type of mining. The paper describes how the support resistance provided by in-stope pillars in current mining was determined and then evaluates support systems that can substitute for these pillars. Conceptual layouts based on existing breast mining layouts are presented. The layouts consist of panels of up to 100 m face length between rigid strike stabilizing pillars. A number of design charts are then proposed that allow for the design of appropriate support systems.

Jan 1, 2005

By Robert M. Valentine, Randall L. Lentell

Interpretive geotechnical investigations were performed for the construction of approximately 15,250 m (50,000 ft) of wastewater interceptor tunnels in Austin, Texas. Subsurface materials consist of claystone (or clay shale), siltstone, altered volcanic tuffs, chalk and limestone. Special conditions include multiple crossings of Onion Creek with cover ranging from about 1/2 to 3 m (2 to 10 ft.), and the potential for mixed-face conditions consisting of water-bearing gravels overlying clay shale or siltstone. The methods and results of the geotechnical investigations are discussed and the inferred construction conditions are compared to those encountered during tunneling. A suggested format is presented for interpretive geotechnical reports for underground construction projects.

Jan 1, 1985

By Virgil Miller

Bureau of Mines Reports of Investigations 3244, 3245, 3246 and 3264 give data of detailed studies on smelting in the lead blast furnace handling zinciferous charges at Trail, B. C. The present paper gives more on analyses of the gases leaving the top of the charge and on accretions formed on the walls of the blast furnace. New data are presented to show the effect of the temperatures at the tuyere zone on the lead content of the slags made. The greater part of this paper, however, deals with a much debated subject, namely air used in lead blast furnaces. Original data are presented to show the effects on smelting lead 'products when air is supplied to a lead blast furnace under volume versus under pressure control.

Jan 1, 1940

By Virgil Miller

Bureau of Mines Reports of Investigations 3244, 3245, 3246 and 3264 give data of detailed studies on smelting in the lead "blast furnace handling zinciferous charges at Trail, B. C. The present paper gives more on analyses of the gases leaving the top of the charge and on accretions formed on the walls of the blast furnace. New data are presented to show the effect of the temperatures at the tuyere zone on the lead content of the slags made. The greater part of this paper, however, deals with a much debated subject, namely air used in lead blast furnaces. Original data are presented to show the effects on smelting lead 'products when air is supplied to a lead blast furnace under volume versus under pressure control.

Jan 1, 1940

The observation of lower-than-predicted Fe/Cu ratios in the cementation of copper on iron in tests at elevated temperatures indicated that some other reaction was contributing to the reduction of cupric sulphate in addition to the reduction by elemental iron. Experiments showed that the copper sponge, which initially formed on the iron, subsequently reduced the cupric sulphate giving the products cuprous oxide and sulphuric acid.Tests were undertaken to determine the rate and equilibrium conditions of the reduction reaction with variations in the types of the reducing agent and solution parameters. The reaction first became apparent at temperatures above 50°C and as it ceased at pH 1·8 it was possible to induce further reaction by alkali addition.

Jan 1, 1974

By Richard Peaker, Jens Lichter, Alexander V. Potapov

"The recent combination of Computational Fluid Dynamics (CFD) and Discrete Element Modeling (DEM) can provide considerable insight into the performance of flotation cells. One area of interest from a fundamental equipment design perspective has been the influence of flotation cell size and the inflow rate on the metallurgical performance of the cell. One of the specific design objectives when increasing the size of flotation cells, or increasing the feed flow to the flotation cell, is to ensure that the feed stream flowing into the cell does not have an opportunity to bypass the mechanism.This paper describes the initial modeling efforts to quantify the inter-relationship of cell size, inflow rates, and feed and discharge box placement, on the retention time distribution of solids in the flotation cell, and the fraction of particles that bypass the mechanism on a size by size basis.INTRODUCTIONThe great majority of newly installed cells in mineral processing plants world-wide are of the cylindrical tank design and this tank shape offers a number of hydraulic advantages over the older style of square cells. Cylindrical cells give symmetrical flow patterns and by careful design of the mechanism and tank internals, the flow patterns generated can concentrate the more intense mixing in the lower portion of the cell to promote good solids suspension and particlebubble contact. Simultaneously, cylindrical tank design gives a more quiescent upper zone for particle-bubble transport into the froth zone. These symmetrical flow patterns are naturally disturbed in normal operation by the slurry inflow and outflow from the individual cells. The challenge for flotation cell designers is to determine the magnitude of these flow disturbances, and to assess whether or when the inflow and outflow rates have a sufficient impact on the hydraulic flow patterns so as to potentially affect the metallurgical performance of the flotation cell."

Jan 1, 2007

By M. Hagfors

When establishing an underwater testing site for the energy measurements of the explosives, the dimensions of the measuring pool have to be measured to find out what is the maximum weight for the test charge. Secondly one has to decide the distance between the pressure gauge and the shooting point. Thirdly the pool has to be calibrated because of the reflections of the explosions by measuring the bubble periods of the calibration charges. The calibration shots can also be used to estimate the minimum weight of the explosive charge for the reliable energy measurements by calculating the shock, gas heave and total energy values and their standard deviations.

Jan 1, 2007

By P Landeros, D Benado, J Cornejo, A Pinochet, C Caviedes

In 2005, El Teniente mine began preconditioning the primary rock mass by hydraulic fracturing (HF). The major perceived benefits of this process are a decrease in the magnitude of the expected maximum seismic event and improved cave propagation. In addition, HF has resulted in new information on the propagation pressures of each fracture. Previous studies have attempted to relate propagation pressure to minor principal stress or confining stress.Considering the spatial continuity of propagation pressure and the significant quantity of collected data since the incorporation of the HF technique, minimum requirements for geostatistical modelling have been reached, permitting robust estimates inside the representative volume with acceptable errors (Cornejo, Muñoz and Rojas, 2012; Cornejo and Landeros, 2013). These results are then used to identify zones with higher magnitudes, which are mostly related to more complex geotechnical zones (intrusive and major faults) and caving singularities, making it possible to estimate the spatial extension of these zones.Finally, these results are integrated with other geomechanics aspects to support risk analysis of the mining plan.CITATION:Cornejo, J, Landeros, P, Benado, D, Caviedes, C and Pinochet, A, 2016. Geostatistical modelling of hydraulic fracturing pressures at El Teniente Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 183–190 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By S. Lin

A new hydrogen production process, named the HyPr-RING, has been proposed. Fundamental concept of the HyPr-RING is integration of water carbon reaction, water-gas shift reaction and CO2 absorbing reaction in a single reactor. Firstly, thermodynamic analysis was done to judge the possibility to realize the process. It was found that high pressure and temperature condition, such as 20 MPa and 1000 K, is required to promote this integrated reaction. Next, experimental verification of the new process was done under the high pressure and temperature reaction conditions. As the results, integration of above three reactions in a single reactor can be done successfully and produced a large amount of hydrogen as estimated by thermodynamic analysis. Experiments showed that organic materials including coal, heavy oil, biomass, plastics can be used in this process. In the gaseous phase, no pollutants such asH2S, SO2, COS are detected so that gas cleanup system is not required for power generation when this process is used. Finally, a process design was made to estimate process efficiency. Theoretically, 1 mole of carbon can generate 2 moles of hydrogen and cold gas efficiency of this process estimated as more than 80 per cent. The process potentially reduces hydrogen production cost compared with the conventional hydrogen production methods. Keywords: Hydrogen, Fossil fuel, Energy, Process, Supercritical water

Jan 1, 2001

By K. E. Brown, J. P. Brill, A. R. Hagedorn, T. C. Doerr

A recent correlation for multiphase vertical flow by Hagedorn and Brown1,7 has been used to examine the effect of numerous variables such as pipe size, gas-liquid ratio, liquid flow rate, liquid viscosity, liquid surface tension, oil API gravity, water cut, etc., on flowing pressure gradients. Most previous correlations were derived by using a form of the general energy equation which assumed negligible changes in kinetic energy. Under certain flow conditions this can lead to serious errors in predicting pressure traverses. Examples of traverses calculated both with and without the kinetic energy term are included here. The Chew and Connully correlation for calculating changes in viscosity with changing pressure and temperature has been extended so that the effect of a changing viscosity with depth on pressure gradients can also be predicted. Examples illustrating the effect of tubing size show the importance of this correlation in determining pipe sizes for initial well completions. Limitations on production rates in small pipe sizes from excessive friction losses can be predicted with greater accuracy. The combined use of a vertical-flow correlation with a horizontal-flow correlation provides a method for determining the maximum flow rate possible from both flowing and gas-lift wells. Examples are included to illustrate application of the combined use of vertical and horizontal-flow correlations in optimizing production rates and minimizing excessive costs from over injection of gas in gas-lift wells. INTRODUCTION The problems of multiphase vertical and horizontal flow are immediately encountered in any producing well. Fig. 1' shows three stages of production: flow in porous medium, vertical flow and horizontal flow. All three stages affect the production rate from a well. If we are confronted with a particular well and consider only the variables involved in the vertical and horizontal stages of Fig. 1, we should be capable of calculating the flowing bottom-hole pressure necessary to produce a particular flow rate. A change in any of the variables results in a new solution to the problem. Recent approaches in developing horizontal and vertical-flow correlations have improved to the extent that the solution can now be obtained with more confidence than previously. VERTICAL AND HORIZONTAL FLOW CORRELATIONS Since Poettmann and Carpenter's' original work in multiphase vertical flow, there have been many additional vertical-flow correlations developed which have greatly improved the accuracy of pressure-loss calculations. These

Jan 1, 1967

By Eugene H. Skinner

This Bureau of Mines report describes the fieldwork and subsequent analysis to determine physical properties, stress distribution, and several aspects of rock behavior as a necessary evaluation for a typical mine opening. All work was done at a test site on the 3300 level, Crescent mine, Coeur d'Alene mining district, Idaho. Free field stress beyond the influence of the opening was also determined. Conventional overcore technique with the three-component borehole deformation gage developed by the Bureau of Mines was used in three drill holes. Three field verification tests were performed using a gage newly developed by the Spokane Mining Research Center in an approach herein termed "initial deformation method." Use of this method validated that aspect of overcore theory which predicts that similar deformation effect occurs in the wall rock around the perimeter of an opening in rock under stress. Also described are all drilling procedures and performances. Physical property determinations were made on rock samples obtained from the three overcore drill holes. Twelve physical properties with a total of [532] values were obtained at various drill hole orientations and depths. Exhaustive statistical tests were utilized in the analysis of these physical properties. Further elaborated are statistical inferences based on these analyses. Extensive analysis and interpretation of Crescent mine geology are also described.

Jan 1, 1974

By Grant Goddard

Cameco?s ?Double U? Strategy ? Double existing production ? To 40 million lbs U3O8 annually ? By 2018 ? Existing operations ? Saskatchewan ? United States ? Kazakhstan ? Projects under evaluation ? McArthur River expansion ? Kintyre (Australia) ? Inkai Block 3 (Kazakhstan) ? Development properties ? Cigar Lake project Measures of Success ? Safe, healthy and rewarding workplace ? Supportive communities ? Clean environment ? Outstanding financial performance

Nov 1, 2011

By B. J. Barfield

Standard erosion plots (4.6 m by 22.1 m on 9 percent slope) were constructed on the Alston Surface Mine of Peabody Coal Company in Western Kentucky to evaluate the effects of placement technique and density on the erodibility and eroded size distribution from mine spoil and reconstructed topsoil. PLots were constructed with a dozer and scraper pan from shale spoil material, topsoil (A horizon) and subsoil (B and C horizon mixture) using soils stockpiled at the Alston Surface Mine. Plots were evaluated under fallow conditions with a tilled plot surface and two compacted conditions. One compacted condition was generated by tracking the surface with a dozer and rolling with a loaded scraper pan. The second was generated by rolling the surface with a solid wheel compactor. Rainfall was supplied with the Kentucky Rainfall Simulator at a rate of 63.5 mm h-l with the plots in three different soil moisture conditions; dry, field capacity, and very wet. Runoff was evaluated for flow rates, sediment concentrations, and aggregate and primary particle size distributions. Sediment yields and the Universal Soil Loss Equation E130 indexes were calculated from the data for each plot. The erodibility was calculated from the tilled plot data using a weighted soil loss and E130 value from the dry, field capacity and wet runs, and a cover management factor calculated for every other condition. For the topsoil and subsoil plots, sediment yield was greatest for the dozer scraper pan plots and lowest for the tilled plots. For the shale plots, erosion rates from the wheeled compacter plots were the highest and tilled plots the lowest. Average erodibilities were 0.14, 0.38, and 0.41 tons ac h ft-1 tonf-1 in-1 hundred ac-1 for the shale, subsoil, and top-soil plots. Cover management factors for each plot were 1.29, 1.42, and 1.17 for shale, topsoil and subsoil plots compacted with the solid wheeled compacter and 1.29, 3.79, and 2.51 for shale, subsoil, and topsoil plots compacted with the dozer scraper pan conbination. The accuracy of the Wischmeier erodibility nomograph was evaluated on the data collected. Erodibilities were accurately predicted for the topsoil plot and poorly predicted for the sub-soil plot. The accuracy of the CREAMS procedures for predicting the composition (size distribution) of eroded particles was also evaluated. The composition was well predicted for the topsoil plots, moderately well predicted for the shale plots and poorly predicted for the subsoil plots.

Jan 1, 1983

By Eldon L. Abbott, Rebecca K. Bolan

The Florida Department of Transportation, Florida’s Turnpike Enterprise is studying the feasibility of a 1128 meter (3,700 foot) vehicular tunnel to provide direct access for Port of Miami traffic to/from I-395, I-95, SR-836 (Dolphin Expressway) and Miami International Airport. Both Bored and Immersed Tube tunnels were evaluated and re-evaluated for constructing two, two-lane, 11.9 meter (39-foot) diameter tunnels beneath the Main Shipping Channel lying between Watson Island and the Port of Miami on Dodge Island in Biscayne Bay, Miami, Florida, USA. Bedrock Geology of South Florida is predominately very permeable, vuggy limestone with sand seams and occasional voids. Groundwater inflows in deep cut-and-cover excavations, tunnel buoyancy, grouting, maintenance of Port operations and potential/possible environmental impacts to Biscayne Bay were significant issues.

Jan 1, 2005

By Charolett Hayes, A. L. Russell, Anthony J. Bednar, Jared Smith, Valentine A. Nzengung, Stephen L. Pilcher

The manufacture of Energetics Materials (EM), including maintenance and demilitarization of munitions causes dangerously high levels of explosives residues to be harbored in building features. The two commonly approved methods of decontaminating energetics contaminated equipment and building features are thermal treatment and steam washing. The current regulatory environment is generally becoming more stringent and unfavorable to thermal and steam decontamination because of their adverse impact on air, soil, and water and their ineffectiveness to completely remove accumulated energetics from foundation cracks, internal and external piping, voids in walls and ventilation systems, and internal cavities of fixed equipment. However, chemical destruction of energetics, especially high explosives, is gaining acceptance as a safer, cost-effective and environmental friendly alternative to thermal and steam decontamination. Organic explosives, including nitramines and nitrate esters are oxidized organic compounds that are susceptible to chemical oxidation and reduction reactions. Under suitable conditions, a chemical reagent consisting of sulfur-based bulk reductants (neutralent) commercialized as MuniRem generates highly reactive free radicals that very rapidly degrade many energetic compounds to innocuous end products while stabilizing metals as the insoluble metal sulfides.

Jan 1, 2016