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By Edwin G. Johnsen

Underground mining is relatively safe today, but no technique or equipment is completely fool proof and 100% reliable. The only sure way to prevent accidental death or injury to underground workers is to remove them completely from the hazardous environment. This alternate approach to underground work is now feasible. Tunnelling and mining systems can be built that could be remotely controlled by men operating consoles in a surface control room. This concept, called a teleminer, would use recently developed remote control technology to remove man from underground work but still give him the capability to remotely operate mining and excavating equipment as if he were actually in the working area. It is appropriate to present this concept in the session "Environmental Controls" because the rationale for environmental control in underground areas can be significantly modified if man is excluded from the underground operation. The development of teleminers cannot only reduce or eliminate most of the requirements for conventional environmental control, but it can also create new and powerful techniques for rapid tunnelling and excavation. TELEMINER CONCEPT The concept of remotely controlled mining machines is neither new nor untried.(1)(2) Conventional remotely controlled mining equipment employs the standard techniques of extending the controls of the equipment to a remote console. For example, the rotary cutters on a remotely controlled tunnelling machine are started or stopped by a human operator turning a switch on the remote control console.

Jan 1, 1997

By Ivor Hawkes, Malcolm Mellor

INTRODUCTION There are currently around fifteen companies in the United States and Europe manufacturing hard rock tunneling machines. In recent years upwards of 200 hard rock tunnels of lengths up to 12 miles and diameters to the order of 30 ft have and are being successfully driven by over 100 different machines. It has been predicted that within the next decade over 2,000 miles of tunnels will be driven for transportation purposes in the United States alone (OECD Advisory Conference on Tunneling, Washington, 1970) and it is expected that eventually most tunnels including mine drivages will be excavated by machines. All tunneling machines have certain common basic functions; thrust is applied to drive or hold the rock cutting tools into the face, and torque is applied to rotate the cutting tools over the face so that they can continuously break out rock. The speed of head rotation, together with the torque requirement, determines the cutter head power. (The power required to push the head forward is usually negligible.) There are many factors which determine how successfully a given tunneling machine will perform in a given rock but one of the most important is effective utilization of cutter head power. This paper is a review of the specifications and performance of hard rock tunneling machines, obtained from manufacturers' catalogs, published literature, talks with manufacturers and visits to operating machines throughout the United States and Europe.

Jan 1, 1997

By I. Dumitrescu

Since 1990, the entire Romanian mining industry has suffered a major restructuring, i.e. technical and economic. The large majority of the remaining active mines are these with a chance for economic comeback. This is also the case for the mines that belong to MINVEST Deva Company; most of the mines are closed, and are waiting to be reclaimed. The authors present the closing procedures of the former copper mining perimeters managed by MINVEST. It is well known that pollutants of concern for the environment must be monitored to obtain reliable information on the quality of ambient conditions and to minimize their impact on the environment. Consequently, the monitoring problems during the closing procedures will be presented.

Jan 1, 2008

By F. W. Petersen

In the precious metal industry, activated carbon is used extensively for the recovery of gold and silver from cyanide solutions, particularly from slimy pulps and unclarified solutions. However, carbon can easily become fouled by inert particles in the pulp, thus decreasing the activity or gold loading of the carbon. This paper attempts to quantify the distribution of fine inert particles in activated carbon. Furthermore, a possible mechanism for the intrusion of fines will be postulated. Precipitated silica and ground silica sand were used to simulate pulp conditions and their loadings on activated carbon were determined by ashing. The kinetics of intrusion of fines into the pores of carbon were relatively fast, and were dependent on the concentration in the pulp. Results indicated that particle size of the solids and zeta potential of the fines influenced the loading of inert species on carbon. Scanning electron microscopy and secondary ion mass spectrometry showed a decrease in solids concentration to the centre of the carbon particle.

Jan 1, 1995

By Thomas D. Kaufmann

Whether pursuing hedging or speculative strategies, gold miners can increase sales revenues 1 % to 6% by constantly pricing production forward. Unlike other commodities, gold futures prices are consistently higher than spot prices. A Colorado School of Mines study showed theoretically and empirically that in the 15 years since the price of gold was released from government control, the forward price for gold has been higher than the current price almost 100% of the time. The reason why Metal traders know that holders of metal earn a bonus selling forward when the metal is in "contango." "Contango" is a mysterious word that crept into the trading vocabulary a century ago. It designates a situation when the price of a metal on the futures markets is higher than the price in the immediate or spot market. If the spectrum of spot and futures prices remains static over time, the forward seller who has contracted at a higher than spot price can make a profit equal to the contango by redeeming his commitment at the lower spot price when the contract matures. Consequently, when a seller in a contango market hedges, he makes a profit on the transaction in addition to avoiding a price change risk. On the other hand, buyers of the metal who hedge in a contango situation will sustain a loss equal to the contango. Producers of gold, however, are sellers of gold. For most metals and oil, there is no inherent reason why futures prices should be higher than present prices. Buyers and sellers decide that the price of the commodity will be lower or higher than present values for a variety of reasons.

Jan 1, 1991

By J. F. Kvitfkovich, R. L. Bate

Coal production in the Central Appalachian region has a long history, and it remains a major US coal-producing region. The coal industry consensus is that the region is in a state of decline as evidenced by the recent lower regional output. Are Central Appalachian coal reserves adequate for the region to continue as a major supplier of low sulfur coal? To answer that question, this paper focuses on the Central Appalachian coal reserve base estimates and production trends. Central Appalachian (CAPP) reserve evaluations face the difficulty that there are no publicly available databases that provide a thorough analysis of remaining CAPP reserves. Based on best available Energy Information Administration (EIA) data, a coal reserve estimate of 17.6 billion tons is developed. This estimate appears high according to industry perception. Recent United States Geological Survey (USGS), and other state agency coal reserve estimation projects are evaluated as alternative approaches to the re-serve estimation problem. Using the conclusions from these studies, the CAPP reserve base is estimated at 7.1 billion tons. Another perspective on the CAPP reserve base is provided by reserve holdings of major CAPP operating companies reported at 5.2 billion tons. A conceptual mining cost analysis indicates substantial price increases will be necessary to offset this deterioration in the economic viability of the reserve base.

Jan 1, 2004

The ever-increasing power (and decreasing cost) of computers has opened up substantial oppor¬tunities for 'Vision'-based systems in both on-line and off-line control. This paper reviews image analysis applications in use at the Julius Kruttschnitt Mineral Research Centre (JKMRC) for: •blast and mill feed size monitoring; •AG/SAG mill model-based control; •mineral liberation; and •froth flotation control. The SPLIT™ image analysis system is being used to estimate muck pile and ROM feed sizings. AG/SAG mill feed sizing is being used in a dynamic model for mill control. A new generation mineral liberation analyzer has been developed with Philips Electron Optics. The Philips-JKMRC mineral liberation analyzer offers a substantial improvement in resolution and speed over previous developments. While on-line liberation control continues to be something of a pipe dream, measuring liberation "one shift behind" is now feasible. A robust instrument has been developed to measure flotation froth bubble size and velocity. The instrument also derives a parameter that allows different froth textures to be distinguished. The instrument has been used for on-line control in coal and sulfide flotation. For coal froth, an online ash estimate has been achieved at one site and is being tested at other sites. Overall, image analysis is finding many applications in mineral processing and control.

Jan 1, 2000

By Lothar Anheuser

Theoretical research, laboratory tests and practical experience confirm the possibility to stabilise the excavated tunnel front by suitably composed slurries even in coarse ground with extremely high permeability. The fluid assures dependable repartition of the pressure, low torque of the cutting wheel and small perturbances of the original ground structure. Very easy access to the front, for tool repair or removal of obstacles, are other features of the WF-Hydroshield concept. For soft ground, the Hydrojet (excavation by immersed slurry jets) permits still further improvements. Field experiences in very mixed face conditions are related. Measured soil subsidences in homogeneous, loose sands above Hydroshield-driven tunnels are compared to calculated values. Dependable shield tail seals, which are a necessary condition for work without compressed air in the tunnel, and an original repair kit are presented. The aim to liberate shield driving from hazards of narrowly defined soil conditions and to broaden the range of applications led to a series of bentonite shield machines, derivated from the initial slurry type, such as Dense Mud Shield, Earth Pressure Balance Shield or shields with hard rock cutterheads. Similar to these constructions, overall stability of the front was the major concern in developing the Hydroshield. Initially, this type was designed for use in cohesionless medium to coarse sands and gravels only. The mechanism of front collapse, initiated by a local slide uncovering a limited area, which triggers a

Jan 1, 1983

By H. Dr. Boldt, J. Dr. Henneke

PREFACE In German coal mines the application of tunnel boring machines has become a very effective and economic technique for major development works. After initial trials around 1970 the breakthrough was reached by driving 13 km of road ways on Rheinland and Friedrich Heinrich collieries, using a DEMAG tunnel boring machine of 6 m diameter. INTRODUCTION The coal mines of Rheinland and Friedrich Heinrich are to be found in the West of the Ruhr Area, the largest coal mining area in the Federal Republic of Germany (Table 1). They form part of the Ruhrkohle company. Rheinland coal mines produces 41000 to 43000 t of run-of-mine coal every day, of which 20500 t are usable coal. Friedrich Heinrich has a daily production of 17000 t of run-of-mine coal, 9000 t of which are usable. The coal is worked at depths of 600 to 1100 m in seams 0.6 to 3.0 m thick. The method of mining is longwall, and the machines used are ploughs and shearer loaders. From 1973 to 1980 a programme was put into operation in these two mines to develop and open up the coal field on the 885 m level. A total tunnel length of 20 km was to be driven. After thorough investigations it was decided to employ a full-face tunnel boring machine for

Jan 1, 1981

By R. M. Bowen

To help solve problems associated with the optimization of complex coal preparation systems, a mathematical model has been assembled which can simplify calculations pertaining to the core of the plant, i.e. the coal cleaning section. It uses algebraic expressions, derived by fitting hyperbolic equations to Mayer curves, to calculate optimum settings for a specified array of coal cleaning units and feeds. This is done without search procedures, and with usually only minor iteration of a simple calculation to specify optima within 0.02% of specified product ash contents. The key to the calculation is a relationship derived via the analytical geometry of conic sections facilitating easy application of the incremental ash theory of separations. The model has been assembled in a generalised form to cater for N processes in parallel, each giving M separations to produce P final products. Examples are given involving assessment of some complex circuit options.

Jan 1, 1986

By Heinrich H. Becker, Vladimir L. Konyukh, Sergey P. Koltsov, Valery A. Davidenkol

Ramifide conveyor transport of the biggest russian coal mine "Raspadskaya" is simulated by Petri nets. There are 6 longwalls with accidental output. 12 belts, and 5 transfer bunkers at this mine. It is necessary to coordinate transport links for recon- structed conveyor system. Many tasks were solved by dynamic simulation, such as estimation of transport lateness, influence of transfer bunkers on an unevenness of total coal flow, maximum filling of each bunker, maximum time of main conveyor refusal, co-ordination of unloading for dependent bunkers, choice of main conveyor. The problem of mine-wide conveyor transport animation for dispatcher is formulated in reference to mine "Komsomolets". OBJECT OF SIMULATION The biggest russian coal mine "Raspadskaya" is situated on a south part of Kusnetski coal basin (West Siberia). One mines about 20.000 tons of coal out of flat seams by 2.2-4.5 m thickness in a day. There are 6 fully- mechanized longwalls by output 720- 3600 tons in a shift in mine. Coal haulage to surface is carried out by 12 belts having 1.6 - 4.3 km length. For a smoothing over un- evenness of coal flows 5 transfer bunkers to 300 tons were intro- duced. The designed conveyor system is divided into two parts (Figure 1). In the upper part some coal from Face 1 comes through belt road C, into transfer bunker 8,. From the opposite side that bun-

Jan 1, 1996

By Jan W. Oberholzer, Jan J. L. Du Plessis, Gerard Appelman, Andrzej M. Wala

The use of on-board scrubbers on continuous miners is an important aspect in efforts to reduce the amount of dust that heading workers are exposed to. As part of the CSIR:Mining Technology's research programme to combat dust, a collaborative project with the University of Pretoria was conducted to evaluate scrubbers. Based on fundamental parameters that were identified to play a role in determining the efficiency of scrubbers, a protocol for testing scrubbers in the laboratory environment, as well as the working section, was established. Tests on various prototype scrubbers were conducted in the laboratory environment. These tests proved some of the fundamental premises according to which scrubbers were designed. By testing some of the newer scrubber types underground, insight into the effect of alternative design aspects on scrubber efficiencies was obtained. The importance of the factors which play a role in reducing the amount of dust in the air is illustrated, as well as the role which other non-design factors play in the reduction of dust levels.

Jan 1, 1995

By H. R. Weischedel

The art of wire rope inspection has advanced rapidly over the past decade. Present electromagnetic (EM) wire rope inspection instruments provide an important and often vital element of wire rope inspection. Some instruments are easy to operate and offer simple and clear data interpretation. Simultaneously, wire rope inspection and retirement standards are becoming simpler and more lucid. Future guidelines will he easy for inspectors to apply and for rope operators to fulfill. The thrust of evolving regulations is clearly toward periodic EM inspections supported by visual inspections. These development sallow even moderately skilled personnel to perform EM inspections of wire ropes. Therefore, it is now possible and cost effective for wire rope users to have EM and visual inspections performed by in-house personnel. In-house EM inspections have many advantages and offer an excellent return on the initial investment. Since EM inspections can detect rope deterioration in its beginning stage, wire rope users recognize that they are an effective preventive maintenance tool. For instance, the early detection of wear or corrosion allows immediate corrective action. This can easily double, or even triple or quadruple, the service life of a rope.

Jan 1, 1991

By Thomas R. Kuesel

In traditional construction contracting practice, the owner allocated almost all risks to the contractor, saying in effect, "you deal with all construction problems and all third parties, and don't bother me." In this same tradition, the architect or engineer designed a structure in its finished condition, and if he thought about the construction problems that might be involved in building it, he was careful not to express any opinions on these matters in the contract documents. This feudal attitude fostered two results: 1. Contractors added high contingencies to their bids to cover the costs of risks. 2. Litigation of construction contract claims blossomed. Broadly, the owners lost--the courts reallocated many risks the owners thought they had laid on the contractor. Thoughtful owners and engineers recognized that owners were paying for risks twice --once in bid contingencies and a second time in court. Meanwhile, contractors were not getting rich; they were losing money on delays and disputes, and just about getting even (if they were lucky) in court. And construction law was becoming an increasingly lucrative field--for lawyers. Furthermore, with the growing influx of lawyers onto the construction scene, the owner-contractor-engineer relationship became increasingly an adversary one. The emphasis came to be on culpability rather than capability--who could be held responsible for breaching some contract clause, not who might find a solution to some common problem. This game was played with equal vigor by owners and contractors.

Jan 1, 1979

By Erich U. Petersen

Discussion by Erich U. Petersen Harbuck et al. (1990) present results of research on sulfuric acid leaching of a germanium-gallium ore and shed considerable insight on possible extraction methods for gallium and germanium. However, the presentation does not give sufficient details to evaluate the research, so some of the conclusions may not be as applicable as stated. The objective of this communication is to indicate that relevant and easily obtainable geological and technical information was omitted. Consequently, on this basis, alternative explanations for some of the data are possible. Discussed below are the omission of: • pertinent geological, mineralogical and geochemical literature; • details regarding the determination of germanium concentration in quartz by electron microprobe; and • details on the calculation of the amount of germanium locked in quartz. "These topics are important since the determination of the amount and locus of "unrecoverable, locked germanium" may have an important impact on the economics and methods of germanium extraction and the directions of future research. Harbuck et al. state that "A key to increasing germanium extraction is understanding the mineralogy of the ore." However, only two studies are cited that in some manner describe the mineralogy of the ores. In addition, both of these studies were very preliminary, of limited scope and examined very few

Jan 1, 1993

By Roland Heersink, Charles H. Wells

This paper discusses how a mill uses off-site data hosting approach to effectively utilize an entire suite of advanced applications to optimize daily operations, without incurring the overhead of on-site systems, staff and support. Details of the solution are provided, together with a live view of actual plant operations. Security and authentication mechanisms are also outlined so that users may gain an appreciation of the actual security of the remotely hosted data. A number of Web-hosted software applications provide direct connectivity to the database offering rapid and deterministic response times to clients. A 24x7 help-desk is available to authorized users from any Internet connected device. The paper shows how mill management advantageously use wireless PDA's to view what is going on at anytime and from anywhere. It concludes with a summary of how the approach is being used to speed decision-making and capture spot market opportunities.

Jan 1, 2002

By Merrill P. Allen

The Vernal phosphate rock concentrator is located in the Uinta Mountains near Vernal, Utah. Ore is sedimentary rock from the Phosphoria Formation. Truck and shovel mining is done at a rate of 11,500 TPD. Run of mine ore is crushed and then milled through a SAG mill and ball mill to minus 16 mesh. Milled ore is deslimed using cyclones and hydrosizers. Sands are conditioned with fatty acid, petroleum sulfonate, diesel fuel and frother prior to primary rougher and cleaner flotation. Primary flotation tailing is milled to 95% minus 48 mesh, deslimed in cyclones, conditioned using reagents previously described, and then processed through rougher and cleaner scavenger flotation. Product of scavenger cleaner concentrate is upgraded by reverse flotation of dolomite. Flotation concentrates are combined and dewatered, pulp being milled to 99.5% minus 65 mesh and then thickened to 65% solids. Product is pumped from storage through a 10 inch, 94 mile pipeline to a conversion plant at Rock Springs, Wyoming. Mill tailing is stored behind an earthen dam, water from the settled tailing being reclaimed for mill use.

Jan 1, 1993

By William Petruk

Volcanogenic base metal ores contain about 0.5 to 7 g/T Au, commonly as an intermetallic compound with Ag and/or Hg, and to a small extent • "invisible gold" in pyrite and arsenopyrite. The Au-bearing phase (electrum, Au-Ag-Hg alloy, etc.) generally occurs as fracture fillings in pyrite, arsenopyrite and chalcopyrite, and rarely • minute inclusions in pyrite and arsenopyrite. The Au-bearing phase in fractures generally occurs • small grains, and is frequently associated with galena, tetrahedrite and other late minerals. The gold is readily liberated from fractures and recovered by flotation in Ca concentrates. Copper concentrates usually recover around 60% of the gold when the ore grade is around 3 g/t. Higher recoveries are obtained for higher ore grades, and lower recoveries for lower grade ores. Lead and zinc circuits act as scavengers for gold, and recover all the exposed gold attached to small particles. Only unliberated gold, "invisible gold" and very minute gold grains attached to large particles are lost to tailings.

Jan 1, 1990

By W. J. Adamson

Strategic Data Planning (SDP) is an emerging technique for the analysis and design of information systems. This paper describes the use of strategic data planning in the formulation of a complete integrated set of mining technical systems for the Koolan Island iron ore mine. Applications covered include hydrogeology, geology, mine planning, surveying, quality control, laboratory and mine production recording. Koolan Island is 13 kilometres long and 5.5 kilometres wide at its widest point. Its sole industry is an open pit iron ore mine of 3 million tonnes annual capacity, owned and operated by BHP Minerals. Some of the production is used by BHP Steel International, but most is exported. The orebody is steeply dipping and is mined bench by bench. Outturn grades for run-of-mine product are iron 66.5%, silica 3.0%, alumina 1.0%. Computer systems are run on Data General equipment, currently an MV10000. Computer applications, which are shared across mine sites, are developed and maintained by BHP Information Systems in BHP's Melbourne Office.

Jan 1, 1986

By Richard V. Good, John B. Harvey, Lloyd S. Jones

INTRODUCTION The term "Rapid Underground Excavation" is generally associated with high speed tunnel advance with large volumes of excavation, and indeed this is the type of work for which most of the recent innovations in methods and new machinery have been developed. However, the term applies as well to any underground excavation process that results in an earlier project completion than would be expected with conventional methods, and hopefully with a decrease in total unit excavation cost. Often significant progress has been made during the primary stages of an underground construction project and then an inordinate amount of time and effort has been expended on small units of "miscellaneous" excavation which has delayed the overall project completion and escallated overall unit costs. Construction at the Nevada Test Site of the Atomic Energy Commission for underground testing frequently requires significant amounts of so called "miscellaneous mining" such as short access drifts, cross cuts, alcoves, niches and concrete keyways. Many of the keyways must be excavated without disturbing the rock beyond the excavation lines and construction scheduling often dictates that much of the work must be accomplished without disturbing sensitive electronic equipment already installed. In order to cut down on lengthy and costly delays required for the tedious manual excavation of much of this miscellaneous mining, a market search was made for suitable mechanical excavation equip-

Jan 1, 1997