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By C. B. Manula

The application of computers to materials handling problems has recently been investigated by various mining groups. This approach has been found, especially useful where a large amount of alternatives must be investigated prior to arriving at a final decision. These alternatives may be expressed in terms of man hours, units and types of equipment such as trucks or conveyors, or the allocation and operation of proposed or existing haulage facilities. The decision problem becomes especially evident when we consider the mechanical revolution which has flooded the mining industry in recent years. The industry has become highly competitive, with the need to keep low profit materials away from high cost production faces ever increasing. The capital investment required for the highly sophisticated equipment that is necessary to perform this function is generally great, and management is faced with decisions which must all too often be made without sufficient data.

Jan 1, 1967

By Saul Escalara

Data on sulfonate adsorption by silicate minerals are very scarce in the literatures. Perhaps the only comprehensive paper written on the topic was done by Fuerstenau and Bhappu (1); this work dealt exclusively with quartz but included many important suggestions as to the form and nature of the hydroxy-sulfonate species of some cations formed during the conditioning step and their effect on the flotation response of quartz. Another paper by the same authors (2) contains additional data on the role of hydrolysis in sulfonate flotation of beryl. As postulated by Fuerstenau and Bhappu, a solid form of cationic sulfonate functions as the collecting species to produce flotation of quartz and beryl. According to the authors, the solid compound is a hydroxy-sulfonate of a given cation, where the hydrogen of the hydroxyl part provides a means for bonding of the species to the mineral surface; thus, the presence of hydroxyl in the neutral precipitated compound is of primary importance to produce flotation. Although the preceding examples illustrate the effect of a sulfonate collector in silicate systems other than plagioclases, they are important as examples of processes of hydroxy-sulfonate complex formation. Since the plagioclase minerals con¬tain Ca(II) and Al(III) cations, which are very reactive in sulfonate media (1), the formation of hydroxy-sulfonate compounds with these cations released from the solid phase may well prove to be the cause for their flotation.

Jan 1, 1973

By Karel Rössler, Petr Vítek

"The Ejpovice tunnels in Czech Republic were built by EPBM in soft Clyashale, and in weathered profile with low soil overburden. The segmented liner at the cross-passage openings required support, which would not interfere with the EPBM clearance envelope during the scheduled pull back of the EPBM through both tunnel tubes. For that reason support frames or radial bolting could not be used. Steel rods inserted into the neighboring segments during the ring assembly, and later grouted were tested and realized as an innovative solution. The paper presents practical experience gained with the segmented liner support during cross-passages construction. INTRODUCTION An innovative solution using the grouted dowels was developed and realized for sixteen cross-passage openings of the twin Ejpovice Tunnels, whose construction was part of the railway track Rokycany – Plzen modernization. The following paper described practical experience gained with the innovative support of cross-passage openings, which was realized by short steel dowels grouted within the segments of the EPBM segmented liner. The paper is a continuation of the paper published in WTC 2015, which described the design aspects of the grouted dowels support, while the following paper concentrated on the production, and the performance of the dowel support observed during the breakout for the cross-passages openings. The connection by grouted dowels was patented by Metrostav, a.s. Company THE EJPOVICE TUNNELS CONSTRUCTION The Ejpovice tunnels construction started in 2013. The start of the high speed train operation through the tunnels was planned for 2018. The project was funded by the state government with the support of European Union funds of up to 70%.The tunnels were excavated with one EPBM (Earth Pressure Balanced Machine) with the external diameter of 9.89 m. The segmental liner inner diameter was 8.7 m, and thickness of 0.4 m. First, the South tunnel tube was excavated from the East portal, then the EPBM was pulled back through the South tunnel, and the excavation was started from the same portal for the North tube. After the South tube was freed from the EPBM excavation operations the cross-passage construction started. Due to the short time schedule, in the North tube the cross-passage construction started while the tunnel was still under construction. Therefore, the cross-passage construction was performed concurrently with the segments transportation, and with the EPBM pull-back through the tunnel. There were 8 cross-passages along the tunnels with a maximum distance of about 500 m, Fig.1."

Jan 1, 2016

Surface contamination of minerals during fine grinding may occur due to coating of one material on the other. This can alter the surface chemical properties and adversely affect the separation of minerals by physico-chemical processes. In dolomite-silica system, selectivity was completely lost (compared to a synthetic mixture) after wet grinding of the minerals in spite of using a dispersant. Adsorption and surface characterization studies were conducted on silica particles separated after grinding with dolomite. SEM-EDAX analysis indicated the presence of dolomite on silica particles, which could cause the loss of selectivity.

Jan 1, 1993

By Bradley V. Nelson

A number of improvements in the ventilation system at the Henderson Mine have been made during the past several years. A key to these improvements was the installation of a computerized monitoring and control system. Employees can determine the status of any of hundreds of devices in seconds through the use of this monitoring system. Mine dewatering pumps, the water treatment system, the ore haulage system, electric power usage as well as other devices are controlled and/or monitored. Ventilation parameters which are monitored include air flow volumes and carbon monoxide as well as the status of main surface fans, mine doors, and ventilation raise doors. Main underground fans are also constantly monitored and can be controlled remotely. These underground fans can be programmed to automatically start and stop to follow work schedules, optimizing air quality while reducing power cost. Mine air heating costs have been reduced by replacing an electrical resistance heating system with a direct fired natural gas heating system at the portal of the ore haulage tunnel.

Jan 1, 1995

By David D. Rabb

Leaching or solution mining, a relatively simple and economical process for beneficiating metallic ores, is likely to find increasing application in the treatment of low-grade ores that are impractical to mine by any other means. This process may be carried out in two different ways: 1. Dump leaching, where the ore is moved from its original location to be leached at another site. 2. In situ leaching, where the ore is leached in place by introducing the leach solution at the top, letting it flow down through the ore under gravity, and then recovering it plus the dissolved metals it contains.

Jan 1, 1969

By Eugene C. Robertson

The exchange of heat from wall rock to ventilating air was studied in a cross-cut driven through fresh rock on the 4600 level of the Kelley Mine, Six- teen thermocouple probes, 10 inches long, twenty-three probes, 7 feet long, and five probes, 50 feet long, were emplaced in the walls soon after blasting and wall -rock temperatures were monitored intermittently over a two-year period to determine heat loss from the wall rock. Temperatures, humidity, and velocity measurements were made of the air at the same times to determine heat gain. An important but less well-defined variable was the heat transfer by water entering the crosscut from fractures and leaving in the ditch. The balance of heat in and heat out at each probe station is within an acceptable range. Theoretical and empirical models for heat flux into a cylindrical opening fit the data reasonably well, also.

Jan 1, 1970

By B. J. Scheiner

The Bureau of Mines has developed a system for dewatering waste slurries by flocculating mineral particles with polyethylene oxide (PEO) and dewatering the resulting flocs on static and/or rotary screens. This paper discusses data obtained from dewatering, rheology, and ion-exchange experiments. A possible mechanism is postulated for the attachment of PEO to claylike particles through a water bridge with the intershell waters of the exchanged ion and the polymer.

Jan 1, 1986

By Edward J. Sterne

Several shale-hosted Pb-Zn-Ag deposits have been discovered in the northwestern Brooks Range, Alaska. Best known among these are the Red Dog, Drenchwater Creek, Lik, Ferric Creek, Hot Dog Creek, and Competition Creek deposits. They occur in a tectonically disturbed sequence of of Mississippian to Triassic shales, argillites, and cherts, and most are spatially associated with volcanic rocks. The sulfides are hosted in shales as disseminations, banded layers, massive lenses, and crosscutting veins. Detailed geologic descriptions of sulfide prospects in the Brooks Range were given by Tailleur (1970), Nokleberg and Winkler (1978), and Plahuta and Robinson (1979). Lange et al. (1980) discussed the formation of the deposits, the nature of the mineralizing solutions, and the temperature of formation on the basis of sulfur isotope studies. More recently, Harrover et al. (1982) detected a correlation between sulfide mineralization and high-temperature formation of charts associated with the sulfides by oxygen Isotope and chert crystallite size determinations.

Jan 1, 2013

By M. G. Ayat

Although other methods of mineral concentration have been developed over the years, gravity separation remains one of the most efficient and economical for cleaning coal. The concentrating table and the spiral separator are popular devices used for the separation of minerals by exploiting the differences in specific gravities of the product material and the gangue. While the former device has been servicing the coal industry for over 75 years, the latter seems to have not been employed extensively for coal cleaning purposes in this country. As far as coal preparation is concerned, both separatory devices seem to be most efficient for intermediate to fine size fractions. As it stands there exists a great deal of confusion amongst preparation engineers and plant managers as to whether spirals can have a place in the coal industry. If so, whether their come back is the beginning of the end for concentrating tables, or can they be employed along with concentrating tables to contribute toward more efficient cleaning processes resulting in an improvement in the overall economics of the coal preparation industry. This paper examines the efficiency of both systems for coal processing operations as well as the basic principles, operational variables, economics, advantages and disadvantages associated with each unit operation. Attempts have been made to draw conclusions and make recommendations as to which system would be more beneficial for coals of known characteristics.

Jan 1, 1986

By B. Pesic

Northwest Alloys, a wholly owned subsidiary of Alcoa, produces magnesium from dolomite by reduction with ferro silicon and aluminum. This process produces alkaline by-products in quantities that allow their consideration for use as commercial by-products. Two such products are dicalcium silicate slag, Di-Cal, and magnesium oxide condensate, MgO. The alkaline properties of these materials offer acid neutralizing capability comparable to the traditionally used lime, therefore, warranting a study for their use in applications where the neutralization of acidic waters or process solutions is required, such as treatment of mine waters. In this ongoing study, three mine waters (Bunker Hill Mine, Berkeley Pit, and Blackbird Mine) were selected for treatment with Di-Cal and MgO. Lime was used as the background control. The solid precipitates were subsequently contacted with pure water at four different pH conditions for stability testing of prepared metal precipitates (expanded TCLP). It was found that neutralization with Di-Cal results in precipitates which are of equivalent to superior stability than those from lime treatment.

Jan 1, 1999

By Ted C. Mathews

Pre-concentration by sorting is as old as the mining industry. Inevitably waste rock is broken with ore. Separation may take place in the stopes by selective mucking and transport, or selective loading and transport of ore and waste by 12-cu, yd. shovels and 100-ton trucks in large open pit operations. Hand sorting of 1" to 16" pieces, formerly widely practiced at underground chutes and prior to or following first stage crushing, has greatly diminished in the United States with its high per hour labor cost, although still widely practiced in other countries and, surprisingly, in some of the most modern mills where inexpensive labor is available. The economics of pre-concentration by sorting is attractive since elimination of waste at any cost less than the total milling cost will show a profit. The size at which sorting should be under- taken is determined by the size at which liberation is secured to yield a product of ore and waste, and greatly influences cost and the point in the flowsheet where sorting can be undertaken. In some instances mining costs can be reduced where an inexpensive sorting system to eliminate waste is combined with a less selective and less costly mining method. This is particularly true in deep mines where hoisting capacity determines the rate of extraction and sorting is performed underground, with waste utilized for fill. Hand sorting, while efficient, is expensive because of low sorting rates. Peale (1) quotes man hour capacity at 1/3 ton per hour on sizes 3/4" to 3" copper ore, and up to 5 tons per hour on rich iron ore sized from 4" to 16".

Jan 1, 1974

By A. D. Davis

A ground-water flow model was developed to simulate the post-mining recharge rate at the Belle Ayr surface coal mine in the Powder River Basin near Gillette, Wyoming. State regulations of Wyoming require that reclaimed lands should provide a rate of recharge that approximates the pre-mining rate. Steady-state calibration and transient simulations showed that the post-mining recharge rate in backfill is at least five centimeters per year, exceeding the original infiltration rate of 0.4 centimeters per year to shallow, overburden aquifers. Major reasons for the increase include the flat topography of reclaimed areas and decreased spoil density. It is expected that the backfill will disaggregate and settle over time, eventually resulting in a nearly constant recharge rate less than five centimeters per year but somewhat greater than the pre-mining rate.

Jan 1, 1995

By E. J. Rorem

Rockfall and unstable rock slopes can be effectively controlled by utilizing steel wire rope net systems, either as barriers or as slope draping. The chief advantage of such systems over rigid type barriers is the flexibility of wire rope netting, permitting kinetic energy dissipation, yet providing high strength and consequently low maintenance. A review of the design considerations involved with these systems, as well as a review of several mine and non-mine installations is presented with the hope that the information may contribute to the safety against the dangers of rockfall and other mine hazards in active and abandoned mines.

Jan 1, 1996

The Newmont Boddington Orebody (NBO) is a large, diffuse Au/Cu orebody in Western Australias South-West corner with approximately 20Moz Au in current Reserves. The current sulphide Resource is reported after calculation with the non-linear estimation technique Uniform Conditioning to account for the mining selectivity being smaller than the average drillhole spacing. Simulation of Au grade is also run over the entire orebody reviewing risk and uncertainty. There are differences in results from the two methods. These have been investigated and the lessons learned of the influencing parameters and effect of technique alone, are helpful for applications to other orebodies.

Jan 1, 2010

"With up to 2,300 m (7,545 ft) of rock on top of it, the Gotthard Base Tunnel, which is scheduled to go into regular operation in December 2016 in the Swiss Alps, is not only the world’s longest, but also the deepest railway tunnel ever built. Accordingly, the temperatures in the tunnel are very high, with the surrounding rock expected to reach 45° C (113° F) once the tunnel is fully operational. Since unrestricted rail operations are only permitted in temperatures of 40° C (104° F) or less, the heat has to be controlled with suitable equipment. Large fans developed and built especially for this application by TLT-Turbo GmbH provide fresh air for regular operations as well as during maintenance and repair work. Separate fans ensure that the emergency exits are properly ventilated in case of fire. In addition to coming up with a technical solution that could handle the special challenges of this project, the engineers and planners had to develop detailed preliminary plans as well as a sophisticated logistics and installation concept.The Gotthard Base Tunnel consists of two 57-km (35-mile) long tubes, one in each direction. Including all connecting and access tunnels, the entire underground system measures 152 km (95 miles). At Faido and Sedrun, at approximately 16 and 36 km (9 and 23 miles) respectively, two multifunction stations were built that cut each of the two tubes into three sections of roughly equal length. Here, trains can make emergency stops and change tracks, if necessary. This is also where eight large axial fans made by TLT were installed that exchange the air, i.e. they extract a certain amount of heated air and inject the same amount of cool fresh air a few hundred meters further down the train tracks. In addition to the four exhaust and four supply fans, 24 so-called jet fans were installed along with associated components like silencers, shut-off dampers, drives and lubrication systems from TLT.In addition to exchanging the air, these fans are used to enable maintenance and repair operations in the tunnel. Current plans call for blocking each tunnel tube for one night per week in order to perform preventive maintenance work, thus enhancing the tunnel’s overall functionality and availability. During these hours, many people will be in the tunnel who require fresh air. “One of the major criteria for winning this bid was the fans’ ability to quickly switch between a wide-range of modes. TLT fans are among the best in the world in this regard,” said Andreas Kuhn, TLT’s project manager for the Gotthard Base Tunnel, about the selection of his company’s fans for this project."

Dec 1, 2016

By Alexandru Corneliu Stematiu, Catalin Popescu, Radu Sarghiuta

"The tunnel sector is excavated into a rock mass heavily affected by tectonics, defined as a regional fault. The rock around the tunnel support undertakes the non – elastic deformation and gradually detaches from the rest of the non affected rock mass, moving inside of the excavated area and tending to fill up the whole space. The initial solution of using stiff support consisting in double steel ribs I12 with circular shape in the upper part and straight vertical pillars in the lower part has proved to be inadequate. Based on the calculations of the subsidence phenomena and a mathematical model, the proposed alternative support was provided by special circular steel ribs – SG-23 –that allows a limited rib deformation (by relative slip between the arch segments) in order to mobilize the contact between the rock contour and the inner face of the rib - not only for the deformed rib but also for the neighboring ribs. 1. INTRODUCTION Hydropower development of Jiu river in Romania, in the narrow gorge sector includes two diversion HPP and a small hydro plant that provides the minimum required flow downstream: CHE Dumitra , CHE Bumbesti and MHC Livezeni (Table 1. Hydropower parameters).The Livezeni intake reservoir is provided by a gated dam located 1250 m downstream of merging point between Jiul de Vest river and Jiul de Est river. The dam is equipped with three radial gates with flap gates with a span of 12 m each and the height of (6 + 3) m. The longitudinal profile of Dumitra head and the location of the gallery zone that is the subject of the paper are presented in Figure 2. Longitudinal Profile – Dumitra Head."

Jan 1, 2016

By D. W. Park

Longwall mining is considered the most efficient underground coal mining technique in terms of coal extraction ratio, production rate, and safety standards. Due to the increasing demand for higher coal production, wider panel and faster face movement have become the recent trends. Thus, longwall mining can create unexpected threats such as roof falls, excessive face convergence, shield damage and numerous maintenance problems causing sudden interruption of coal production and serious safety hazards. A recent study at the University of Alabama is dedicated to develop LoSCoMS (Longwall Strata Control and Maintenance System) which integrates real-time shield monitoring, data presentation, analysis, forecasting, and warning modules. The main objectives of this system is to provide the stability and maintenance information, at every minute, such as high load, low setting pressure, leg leakage, etc., analysis of various mining and geological parameters to determine past and present roof characteristics and forecasting of loading patterns for the following mining cycles, next periodic weighting, etc. Using this unique system, mine operating personnel are well aware of past, present and future roof loading patterns at the longwall face, and thus, proper safety measures can be taken ahead of time.

Jan 1, 1997

"INTRODUCTION While the United States coal mining uses prescriptive regulation under the Title 30 Code of Federal Regulation enforced by the Mine Safety and Health Administration (MSHA), Australia uses a risk based approach. Australian regulation is individual to each state. In Queensland, Australia this risk based approach to address principal hazards is underwritten by the Queensland Coal Mining Safety and Health Act of 1999 and the Coal Mining Safety and Health Regulation of 2001. Each Queensland Mine is required to have an overarching Health Safety and Environment Management System, of which Safety Management Plans are an element. “Safety Management plans (SMP’s) are intended to formalise the process by which mines address principal hazards and other related matters to ensure the safety of mine personnel.”7 THE QUEENSLAND CONTEXT In Queensland, the basic elements of a coal mine’s safety and health management system must provide for risk identification and assessment, hazard analysis, hazard management and control, and the reporting and recording of relevant safety and health information and data.5 (Part 2 Division 1 Section 6(a-d)) The initial guidance for writing Safety Management Plans comes from the Approved Standard for Mine Safety Management Plans and Guidance Note QGN09- Reviewing the Effectiveness of Safety and Health Management Systems. The Guidance Note and Approved Standard are supplemental to the Act and Regulation, and put in place to provide more clarity around the topic. The definitions in this section come from the Approved Standard and are included to provide context for those who may not be familiar with Australian or Queensland law and regulation. A hazard is defined as a source of potential harm or a situation with a potential to cause loss, while a principal hazard is a hazard with a potential to cause multiple fatalities. A risk is the chance of something happening that will have an impact upon objectives which is measured in terms of consequences and likelihoods. It is important to be able to make the distinction between a hazard and a risk. For instance, a lion is a hazard, while the risk associated with a lion is getting eaten. As defined by the Queensland Approved Standard for Mine Safety Management Plans, a Safety Management Plan (SMP) requires a systematic definition of all the actions necessary to ensure that mining operations are carried out safely. A SMP includes, but is not limited to organisational structures, planning, activities, responsibilities, practices, risk identification, audits and reviews.7 The goal of a SMP management plans is to mitigate the risks to bring them to an As Low As Reasonably Achievable (ALARA) level."

Jan 1, 2016

By Michael Fellows

Epidote is a common hydrothermal alteration product in many copper deposits of the southwestern United States. In many of these deposits epidote, along with calcite and chlorite, generally characterize a distal or halo propylitic alteration assemblage, but the mineral can occur within the central potassic alteration zone as well. Epidote is also a common alteration mineral in deposits formed in calcareous host rocks -- the skarn or pyrometasomatic ore bodies. Within the past 15 years, studies of the major and trace element composition of other alteration phases, principally biotite, associated with base metal ore deposits have demonstrated that some hydrothermal alteration minerals are compositional distinct from their igneous or metamorphic counterparts: However, the use of major and minor element content to identify and zero in on mineral¬ized areas does not appear to be very promising. Little work has been published upon the geochemistry of epidote from this standpoint and the results of my work suggest that a similar conclusion can be applied to epidote. My work (Fellows, 1976) suggests that epidote minerals in hydrothermal alteration suites from porphyry copper deposits in the southwestern United States are generally iron-rich rather than aluminum-rich. As a group, these alteration minerals differ compositionally from epidotes of regional metamorphic terrains. I ascribe these differences to the variations in the oxidation character of the respective environments. However, it appears as though the use of major element compositional variations of epidotes as an exploration tool is severely limited. Epidote is a complex calcium-aluminum silicate. Replacement of aluminum by ferric iron establishes a solid solution series between

Jan 1, 1977