Search Documents

By M. D. Monroe

Getting the best match between truck and haul road requires examination of many factors and their effect on the bottom line. Most mines use a bottom line measure based in some way on cost per ton of material moved. This measure focuses on the two components of truck haulage cost per ton: productivity (or performance) and operating cost. Productivity can be measured or predicted for specific tasks using either field measurement or modelling. Individual tasks can be combined to provide a larger scale, longer term net figure for total mine output. True cost is more difficult to capture as they are time and task oriented and can be influenced by a summation of factors over a truck lifetime. For example, "allocated" costs, such as owning (depreciation) and some repair costs, are spread over long periods of time. Other cost, such as fuel and tires can be tied more directly to certain tasks such as fuel and tire cost. This paper focuses on the more direct, task-oriented factors that affect truck productivity and cost.

Jan 1, 1992

By Joseph Kuti

Longwall mining is the term used for the underground extraction of a wide and deep panel of coal. Such a panel may be blocked out by one or more entries on either side ("head" and "tail") of a longwall face. If all the entries are pre-driven, the panel extraction is termed longwall retreat mining. With one exception, all the longwall faces in the United States are of this type. (1) prior to the general decline in the rates of production with Continuous Miners, the development of the multiple entries generally kept ahead of the longwall extraction rate. This is no longer the case: longwall extraction rates far exceed the rate of development. In addition to this problem, in newly established mines, the development of a haulage and bleeder system based on multiple entries results in a lead-time of three years or more before longwall mining can be applied. This is one reason why earlier projections and much of the optimism attached to longwall mining as a principal "savior" in the energy crisis should be viewed with some caution.

Jan 1, 1978

By Sandeep Pattnaik

Spring stiffness of soil and rock at different depth is often required for a pile structural model. If the pile is rested in multiple layers of soil, then it is rather more complex to simulate the soil in a structural model. The spring stiffness will vary based on density of soil strata over the depth. When a pile is socketed in weathered rock followed by a soil layer, a sudden change in subgrade modulus can influence the pile deflection drastically. Determination of soil spring and simulation of the pile in this condition required correct interpretation of subgrade modulus. The conventional approach of pile spring calculation underestimates the spring stiffness by ignoring underlaying stiffer layers. A finite difference method (FDM) of analysis can reasonably estimate the p-y of soil / rock based on subgrade modulus of each layer. However, the transition between the layers can be better simulated as per the deflection pattern of the pile. The lateral deflection of the pile is mainly dependent on the stiffness of soil layer surrounded by the pile. Generally, the lateral influence of a pile varies from 4D to 6D depending on the soil type. Therefore, soil spring stiffness around the pile would require special attention of a Geotechnical engineer to avoid uncertainty in the prediction of pile behaviour. In this paper, emphasis has been given to develop an approach for pile spring stiffness design. A standard software program LPile has been used to develop p-y curves of soil and rock layers at different depths and then converted to soil/ rock springs over the depth. Modulus of Subgrade Reaction as given in IS 2911 (Part2) was also used to correlate the spring value for different type of soil. Obtained analytical results were compared with full scale field trial for lateral deflection of pile. A good agreement between these two approaches has been established. The effect of soil structure interaction in the structural model shall be simulated by assigning an equivalent vertical and horizontal soil spring, which is developed by Winkler’s soil spring approach. A simplified design principle for calculating the pile spring is discussed in this paper. This approach has been extensively used in Mumbai metro elevated line pile design.

Nov 1, 2022

By William A. Beck

Bauxite was discovered in the Springvale district in 1916. About 16, 000 tons was mined in the period 1916 to 1922, but no bauxite mining has been done since that time. The Bureau of Mines explored for bauxite in the district from September 5 to November 18, 1943. During the life of the project, the Bureau of Mines obtained mineral exploration agreements covering a total of 11,330 acres from 50 property owners. A total of 388 holes were drilled on five of these properties and 164 samples were taken and analyzed. The Springvale bauxite district includes an area of about 30 square miles in the northwestern part of Randolph County, Ga. The village of Springvale is in the west central part of the district, and Cuthbert is 8 miles southeast of it (fig. 1).

Jan 1, 1949

By E. B. Kester

In the commercial evaluation of coal tars, a distillation analysis properly carried out is of considerable importance. Close attention must be given to this operation in order to obtain consistent results and to secure the minimum decomposition of the tar compounds, Which in Many cases are sensitive to undue heat effects. Low-temperature tars in particular contain compounds of this nature, while in the case of tars produced at high temperatures the large proportion of pitch present has an adverse influence during a distillation. If excessive cracking takes place, the composition of the distillate will naturally vary from the normal, with the result that all the analytical criteria subsequently obtained are affected. Where tars, produced over wide ranges of carbonization temperatures are investigated as in the survey of gas, coke, and by-product making properties of American coals now being conducted at the United States Bureau of Mines Pittsburgh Experiment Station, the method of distillation must necessarily be the same for all of the tars studied. Also, it mast function equally well for both low and high temperature tar permit accurate fractionation, and reduce adventitious decomposition to a minimum. The authors are aware that certain types of distillation analysis which do not meet the above requirements may give results comparable with those of the large stills of a by-product coke-plant where one type of tar is produced. These may be simpler and shorter and entirely suitable for control work, but at the same time have little value in a fundamental investigation.

Jan 1, 1932

By Walford S. Wright, NORMAN EBBLEY

During the past decade (1937 to 1947), including the war years of heavy demand for metals, the United States realized about one-eighth of its antimony requirements from domestic production, chiefly in Alaska. In World War II, our foreign supply sources became endangered; and uncertainty in our Far Eastern supply made this nation focus on Alaska’s mineral resources with a Production Gear that centered in the Bureau of Mines experimental station at College (Alaska). The development work known as District or central deposits. The strategic mining districts included that of central Alaska was reorganized at Ketchikan Mining Districts. Mines were located here had produced considerable quantities since 1901; but methods for exploration had come from 1936 to spring 1942, some $4 million produced in gold alone. Statistics relating to available ores are those selected by type and exploitation periods with wide variety applied. During the summer of 1941, as part of an extensive Geological Survey program continuing through funds provided by U.S., geological surveys spent six weeks mapping an area approximately two square miles surrounding mines. The mines working both surface & underground work employed these men in mapping exercises.

Jan 1, 1948

By J. Perlacia

Introduction The Bulk Handling Technology has already started its transformation to the Industry 4.0. Having some of the harshest working and environmental conditions of the industry, the possibility of remote analysis and maintenance of the components seems a perfect target to focus on. The most important and expensive tools have been adapted to the digital era during last years, from remotely controlled haul trucks to monitored conveyor belts. However, these big parts of the installations rely in smaller parts that have been left aside for a while, mainly due to the difficulty to adapt them to IoT (Internet of Things). The paradigmatic example is the lack of monitored rollers whereas all the other components of the conveyor belt installations (the belt itself, motors, drums etc.) were monitored some time ago. The main problem is that a failure of a single roller can cause the stop of the whole conveyor, due to the possible damages to the belt, thus the implementation of an integral monitoring system of all the components of the conveyor is a must. The R&D Department of ULMA Conveyor Components, has been working since early 2012 on the development of Monitored Rollers, facing all the problems until its final installation in very different demanding conveyors, from the Australian extreme heat to the freezing cold Norway. All the tests done under actual working conditions, in real installations, have given a valuable knowledge in the identification of problems, their solution and the final advantages of a roller monitoring system. Background and Current State The malfunction of a single roller in certain conveyor belts can suppose the standstill of the whole installation until its replacement, due to the risk of greater and more expensive failures like the rip of the belt. In the case of a bulk handling installation where a continuous supply of material is necessary, an unexpected stop of one hour could entail huge economical losses. What’s more, many conveyor belts are several kilometers long or the access to some parts of them is very complicated. Due to these difficulties the inspection and maintenance operations can become expensive and hard going, with staff going over the whole area checking the correct condition of the conveyor and rollers, which means a dangerous activity. As in many other industry products, the condition of rollers can be recognized measuring key parameters like the temperature of the bearings, the vibration level etc. The traditional way is to use the characteristic noise of a failing bearing, but this method usually implies to change several rollers because the maintenance team is not able to identify a single source of the noise. In recent years different attempts to measure the temperature of the bearings have been made, but the result is not accurate enough due to the proximity of the rollers in the idlers

Jan 1, 2019

By R. P. Vinson

The Bureau of Mines examined the effects of high humidity and water droplets on the GCA Corp. real-time aerosol monitor (RAM--l). which uses a lO4mm cyclone preseparator. Tests were conducted both in a laboratory and in a full-scale model mine entry. The laboratory tests were conducted in a test chamber saturated with moisture and water droplets. Under these extreme conditions. the RAM-I responded by indicating dust concentrations of 1-1/2 to 2 mg/m3? although the air was dust free. Within the first 2 h of each test. water accumulated in the cyclone and affected the cyclone particle separation characteristics. resulting in readings of 3 to 4 mg/m3. In addition. condensation formed inside the RAM-I case and affected the liquid crystal display (LCD). However. the full-scale mine entry tests revealed that the RAM-I can function ac-ceptably in an atmosphere of water vapor and water droplets similar to the most severe conditions found in an underground mine.

Jan 1, 1984

By Gerald W. Elger

To determine the feasibility of removing nonferrous metal impurities from automobile scrap by thermal treatment in a rotary kiln, the Bureau of Mines conducted four series of tests with synthetic scrap mixtures heated at various temperatures under oxidizing and reducing conditions. The treated scrap mixtures were melted in an electric-arc furnace and cast into small ingots for impurity evaluation. Analyses showed that the ingots were essentially free of residual metal impurities except for copper. Test data indicated that in an oxidizing atmosphere the percentage of copper removed increased with treatment temperature. Percent of copper removed in a reducing atmosphere was found not to be temperature dependent. A significant finding was that copper was embrittled under some of the operating conditions and was mechanically removed by fragmentation.

Jan 1, 1968

This paper firstly reviews the requirements for container and hopper design for reliable discharge. Discussion is then directed to the evaluation of the consolidation stresses acting in both in both the cylinder and hopper sections during both initial and flow conditions. Here the vast difference, especially in vicinity of the bin outlet, between the initial or filling and flow conditions is highlighted. This vast difference has major design and operation implications. A further major implication is that all bulk solids must dilate to flow. The opportunity to simultaneously attain reliable discharge and partial moisture removal is also examined.The selection of design parameters to maximise the consolidation stresses in both the cylindrical and hopper sections is detailed. In regard to the latter, it is recommended fine coal bins be discharged using low friction lined transition hoppers with large outlet spans. Such outlets will discharge fine coal in a relatively compacted state. This compaction state should exhibit minimum water retention and short term moisture uptake.

Jan 1, 1998

By Melvin E. Poad

This Bureau of Mines report presents two phases of a research program to evaluate a single-entry system for longwall development. Organizations participating in the program; which began in July 1971, include the Bureau of Mines, the Mining Enforcement and Safety Administration, and the University of Utah, working under a cooperative agreement with Kaiser Steel Corp. at its Sunnyside mine in Utah. Part 1 of this report describes the present longwall mining practice, including a brief history, and discusses the advantages and disadvantages of a single-entry development system and its introduction in the United States. Part 2 of the report presents the research program; test design, instrumentation for ground and support evaluation, and the test results from the No. 2 mine. Subsequent reports will describe the research conducted in the No. 1 mine.

Jan 1, 1977

By Duclerc Fernandes Parra, Vijaya Kumar Rangari, Washington Luiz Oliani, Ademar Benevolo Lugao, Nilton Lincopan

Due to its versatility and low cost, polypropylene (PP) is one of the most widely used polymers in the world, consequently in research and development of new products. The polypropylene modified was prepared by gamma irradiation in acetylene at 12.5 kGy dose, technical polymer also known as high-melt-strength-polypropylene (HMSPP). It was mixed with montmorillonite (MMT) clay and silver nanoparticles (AgNPs) for bactericide activity. HMS-Polypropylene-clay-silver nanocomposites were manufactured using twin-screw extruders. Those materials were prepared by a melt mixing process via twin screw extrusion with a wide range of processing conditions. The polypropylene nanocomposites (PPNC) surfaces were exposed to gamma-radiation (60Co) source in presence of nitrogen as inert atmosphere at 1; 3; 5; 10; 20 and 50 kGy doses for modified the surfaces in order to enhance biocide activity. The samples surfaces were characterized by Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and evaluated by determination of bactericide effects. The results indicate the formation of structures predominantly intercalated of HMSPP nanocomposite. Contact tests for antibacterial activity of the hybrid polymer were applied against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. The irradiations on the samples surfaces were insufficient to promote activity on contact biocide tests.

Mar 1, 2018

By C Katonga

Mindola mine is currently the deepest mine in the Zambian copper belt. Stoping is currently active to 1330 m below surface with long range plans indicating future production from 1590 m level. The orebody is tabular and dips between 55o to vertical. The thickness varies from 8 to 14 m. The vertical crater retreat method of mining was first introduced at Mindola mine in the late-1980s following several trials that helped define the design criteria for its application. Over the last ten years the method has been continually modified to improve safety and maximise ore production. For example, due to the weakness of some rock units within the orebody formation and the instability of the hanging wall, the last VCR slices are usually between 8 - 10 m thick, and efforts are being made to strictly apply shrinkage method in order to reduce dilution. Recent advances in mining technology in the areas of equipment, blasting techniques, rock mechanics and materials handling have been employed to increase the overall productivity of the mine. Large down-the-hole machines capable of drilling 165 mm diameter blast holes, up to 80 m long are used in stoping. Each stope produces up to 20 000 tonnes of ore per month and can last for three months. Heavy systematic ground support of VCR development has significantly enhanced safety for mining crews and equipment. Crater mining has not only improved productivity and enhanced safety, but also overcome various problems associated with conventional sublevel open stoping previously employed at the mine. This paper discusses the technical and operational aspects of vertical crater retreat mining at Mindola mine during the last ten years. The changes in mining method are often accompanied by changes in mine design, blast design, mining equipment, ground support and operating practices.

Jan 1, 2000

By Y Zhang, Z Zhao

The green production of the steelmaking process has urgent requirements for fluorine-free fluxes. In this article, a new solid waste-based slagging flux was applied in the external dephosphorisation test of low silicon hot metal to replace the traditional fluorite-lime dephosphorisation slag. The results showed that under laboratory conditions, the new flux was utilised for smelting low-silicon molten iron with a phosphorus content of 0.10~0.13 wt per cent, the temperature of the molten iron was 1350°C and the slag amount was controlled at 2 per cent. Within ten minutes of smelting, the dephosphorisation rate of the molten iron reached more than 50 per cent. When making slag with new flux, the slag melting time was about 40 seconds and the P2O5 content in the final slag was higher than 8 wt per cent. In the industrial test of a 150 t molten iron ladle, under the same molten iron conditions, an out-of-furnace dephosphorisation test was conducted in the Kambara Reactor (KR) process. The flux material consumption per ton of steel was 8~10 kg. Within 15 minutes of smelting, the dephosphorisation rate of the molten iron was about 30 per cent. During flux slag making, the slag melting time was about three minutes and the P2O5 content in the final slag was higher than 6 wt per cent. This new solid waste-based flux has significant cost advantages and outof- furnace dephosphorisation effects and is expected to become the benchmark for a new generation of fluorine-free steelmaking fluxes.

Aug 21, 2024

By Granville S. Borden

TAXES in general are onerous and are not a pleas- ant subject for discourse. There are, however, some very cogent reasons why we should dedicate a part of our thoughts and services to the solution of our taxation problems: The happiness of every individual in the United States depends on the maintenance of a stable government. The collection of taxes is an indispensable function of a stable government, and the power to collect taxes depends in part on the question whether taxes are fair and equitable. As representatives of the mining industry it is our duty to .protect it from tax burdens that are discriminatory or- unjust, As citizens we find that taxation is incessantly endeavouring to unravel the knots in our purse-strings. Many members of the Institute may be consulted .by clients on taxation problems, especially the phases which re- late to depletion and valuation. It is the hope of the writer that the discussion of some of the current depletion and valuation problems will stimulate interest in the problems, and as a consequence of this new interest facts will be ventilated, opinions rendered and services performed, which will be a means of solving the problems to the satisfaction of all parties interested.

Jan 1, 1929

By Emily Johnson, Catherine Johnson, Ben Sonpon, Kelly Williams

The effect of length to diameter of the detonator is compared using Ansys/Autodyn 2-D simulations, the results of which are validated experimentally. It was found that higher pressure comes with a larger diameter, because it will result in more explosive energy being allocated out the end of the detonator.

Feb 1, 2020

By Steve T. Laflin

Since the beginning of the nuclear era, there has never been a commercial solution for the large quantities of depleted uranium hexafluoride generated from uranium enrichment. In the United States alone, there is already in excess of 1.6 billion pounds of DUF6 currently stored. INIS is constructing a commercial uranium processing and fluorine extraction facility. The INIS facility will convert depleted uranium hexafluoride and use it as feed material for the patented Fluorine Extraction Process to produce high purity fluoride gases and anhydrous hydrofluoric acid. The project will provide an environmentally friendly and commercially viable solution for DUF6 tails management.

Aug 1, 2010

By G. M. L. Robinson

Mineral Processing Wastes, as defined by the Environmental Protection Agency (EPA), has determined that most of the mine wastes will be regulated pursuant to subtitle D (Solid Waste Regulations) of the Solid Waste Disposal Act while specific mine waste categories will be regulated within the framework of the Toxic Substance Control Act. Though EPA's determination currently relieves the industry of the regulatory constraints mandated by the Resource Conservation and Recovery Act (Hazardous Waste Regulations) Subtitle C regulatory framework; the industry is not granted immunity from historical or current environmental regulations related to listed or characteristically hazardous or solid wastes. Because of the current regulatory trends and the need to implement cost effective remediation alternatives; advanced currently available on-site remediation technologies are available to minimize, reduce, contain or prevent environmental impacts related to mining and processing activities. In light of industry technical needs, an overview of the research and commercially available remediation technologies will be discussed and a brief discussion of the strengths and weakness of each technology will be presented. Technologies to be discussed includes stabilization, solidification, soil wash, soil flush, thermal distillation, pump and treat, metal extraction, centrifuges, filter presses, bioremediation, and incineration.

Jan 1, 1992

By S. Klein, M. McLeod, S. Gambino, K. Johnson, E. O’Hara

The Mokelumne Aqueducts Resiliency Project (MARP) involves construction of a 16.5-mile tunnel across the Sacramento-San Joaquin Delta (Delta) to replace the existing surface aqueduct pipelines with more resilient conveyance. The tunnel will be bored in Pleistocene-age alluvium at elevations between 100 to 10 feet below mean sea level. At this depth ground conditions are signicantly stiffer and denser than surcial soils and will mitigate potential seismic harards related to liquefaction ground shaking and cooding that could arise from potentially damaged levees. The heterogeneous soil deposits at tunnel depth consist of interbedded layers of stiff to very stiff clay and silt, and dense to very dense clean sand and silty sand.

Jun 23, 2024

By Richard A. Leiby

The recycling of lead-acid batteries in the United States has become a challenge as to how to balance ever increasing environmental regulation and cost with efficient operations. East Penn's captive secondary lead smelter has developed into a recycling facility producing lead, polypropylene, sulfuric acid, ammonium bisulfite, and non-hazardous discard slag. The emphasis has been to design a facility to comply with environmental regulations, to eliminate wastes, and to produce products, while at the same time, continuing to supply the company's battery manufacturing raw material needs.

Jan 1, 1993