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When I wrote the Railroad portion of "Mining Engineering" magazines 94 Powder River Basin (PRB) Coal Article I described to you some definite destinations the Railroads had in mind. As with many destinations, the ones I wrote of turned out to be merely stops on the way to places that we have yet to reach. Somewhere along the way we discovered that making it better is a continuous process not just something that you can do in phases I, II, III, & IV. We always knew this I suspect, but perhaps not at the awareness level that exists in RR environments in 1997. The purpose of this article is to update the 94 article, which I could do very quickly. Everything I told you we were going to do in 94 is done, end of story! But in addition to making it a very short article it would not be telling you the things RR has done beyond what we were planning in 94 and for the future.

Jan 1, 1998

By V. Roze, M. E. A. Robertson, C. J. Sharland

Current Techniques - Fire Assay Fire assay of gold has been used for several thousand years and is a well known technique to the traditional assayer. Very few assayers wish to use the method but to date there has been no viable alternative. Fire assay is expensive in labour, time, capital and running costs. Workers can be exposed to hazards and uncomfortable working conditions such as lead fumes, heat stress, dust and eye strain. The high capital cost of putting up the building and equipping it, together with running costs which increase annually at a prohibitive rate makes the technique less attractive each year. The main requirement in most assay laboratories is to maximise throughput economically. This is difficult with fire assay as it is impossible to automate. Each sample for analysis is handled by at least 12 people and each person represents a potential source of error. Record keeping and report generation has to be done manually which is both slow and prone to errors. Replacement of staff requires a considerable training period and with a large turnover of personnel this presents yet another problem. The presence of silver and dross in the gold sample affects the accuracy at low gold values. X-ray fluorescent analysis Two methods of XRF instrumentation have been used with limited success. The first type is a laboratory instrument employing L X-rays. Small samples of a few grams, which are not representative,

Jan 1, 1988

By Hang Yang, Linneas W. Laage

Mine fire emergency planning requires simulation of the interaction of the fire and ventilation system and the subsequent distribution of products of combustion (POC). Several computer models were developed by the Bureau of Mines to perform this simulation. The most recent and advanced program, MFIRE performs normal ventilation network planning calculations, and dynamic transient state simulation of ventilation networks under a variety of conditions. MFIRE simulates a mine's ventilation system and its response to altered ventilation parameters such as the development of new mine workings or changes in ventilation control structures, external influences such as varying outside temperatures, and internal influences such as fires. A major concern of mine fires is the heat- generated ventilation disturbances which can move POC through unexpected passageways. This Bureau paper describes recent in-mine experiments conducted at the Waldo Mine near Magdalena, NM to validate the temperature distribution and heat exchange with rock functions of MFIRE.

Jan 1, 1991

By Thomas G. Johnston, Garston H. Blackwell

The development of a block model for a copper molybdenum ore deposit is described. The early use of the inverse distance power estimator, and later transition to geostatistics and kr iging, produced block models suitable for global reserve estimates. Because the global reserve was inadequate for routine mine planning, the production blast hole assays were incorporated into the block model, resulting in excellent local grade prediction. The on site use of small mini, and more powerful personal computers for estimating grades is described. The development of a computer aided, interactive graphic, mine planning system utilizing the grade block model is detailed.

Jan 1, 1987

By Walter E. Cook

BOB FALCONER: Without further ado I'm going to introduce our first speaker, Walt Cook. Walt is president of Strata Resources and is here with his business partner Joe Nenni. Joe would you stand up here. You'll be on the tag-team with Walt. Walt and Joe are in a consulting business associated with coal as well as metal and nonmetal industries. Their presentation will be on gainsharing. WALTER COOK: How many of you have gainsharing plans in place currently at your location? [show of hands] A considerable number-more than about half the room. Of those plans, how many of them do you consider as meeting your needs and being successful? [show of hands, far fewer, general audience laughter] You have all at least heard the word "gainsharing." Some of you undoubtedly aren't quite sure what gainsharing is, while others obviously have gainsharing plans in place and are looking for ways to improve them. In the short time I have now I'll be able to give you a precursory look at gainsharing and some brief ideas on where to look to improve your current plans. Over the years, I've found that it is often best to explain gainsharing by comparing it to other forms of employee compensation

Jan 1, 1998

By Y. T. John Kwong

Modified after procedures for assessing acid-generating potential of coal spoils, most acid-base-accounting (ABA) analyses inadequately characterize highly varied metal deposits. Although mineralogy critically controls acid generation and metal leaching, acquisition of appropriate data and their interpretation are poorly developed. Metal loading rates are commonly determined by kinetic testing, which rarely duplicate actual field samples and conditions. Accurate predictions and reduced assessment costs can conceivably be achieved by (i) use of geochemical analyses to define surrogate indicators; (ii) intelligent acquisition and use of mineralogical data; and, (iii) compilation of geo-environmental ore-deposit models to validate inference based on detailed geology.

Jan 1, 2000

By K. Hiroto, H. Tamamoto, G. J. Kusuma

"Acid mine drainage (AMD) has become a serious environmental problem in the mining industry in the last decade. Many efforts have been made in an attempt to find a better method to manage this problem in a proper manner, both through prevention and mitigation. One of the methods to prevent AMD generation is a dry dump cover system that has been proposed to minimize oxidation of sulphide waste rock in dumping sites. The performance of this system depends on the physical and geochemical stability of a barrier layer to minimize water and oxygen influx. In the mining industry, this barrier layer is formed by using Inert/Non Acid Forming (NAF) waste rocks to cover Potentially Acid Forming (PAF) underneath. However, the availability of NAF waste rocks, due to the geological condition, mining sequence and capability of equipment, is limited in some mines. This paper will discuss the acid generation mechanism, application of a cover system and its problem being faced in an Indonesian coal mine, and describe a preliminary laboratory result of a multi layer cover system in an attempt to overcome this problem."

Jan 1, 2011

By Craig Ammar

JAMIE DAVIS: Our next speaker is Craig Ammar. He's director of equipment management for Cyprus Climax Metals Company. He has, prior to this assignment, been responsible for maintenance at Bagdad Copper, Cyprus' Miami smelter, and Thompson Creek. Like Jerry, he's very shy and retiring, and doesn't have any strong opinions about maintenance. INTRODUCTION CRAIG AMMAR: The ultimate goal behind implementing a proactive equipment management process is to provide capacity assurance and ultimately increase an organization's ability to generate revenue while reducing operating costs. Targeting such lofty objectives has brought many an organization to its knees, utilizing new maintenance techniques, concepts, and technology aimed at making our lives better and more organized. The root cause of such frustration generally stems from a lack of understanding or support for the fundamentals of implementing a proactive equipment management process. There are just two types of maintenance programs, reactive and proactive. It's an established fact that you need a little of both to run an effective equipment management process, obviously more of one (proactive) than the other. Here are some telltale signs that your equipment management process is in trouble: -Maintenance is performed as a knee jerk reaction when equipment fails. -Repeated and frequent equipment failures occur, with no focus on eliminating the root cause. -Sketchy, inconsistent, unclear preventive maintenance is performed or there is no support for the preventive maintenance process. -No predictive maintenance technology process is in place, or little support for predictive maintenance exists. -Less than 50 percent of your work is generated by the maintenance group resulting from inspections.

Jan 1, 1998

By Fred N. Kissell, Robert J. Timko

Safe escape from coal mine fires continues to be a concern of the mining industry. The most life-threatening fires occur outby the working sections. Because stoppings always leak some air, an outby fire may in time cause intake escapeways to become contaminated with smoke and toxic gases. Smoke and gas infiltration into intake escapeways can be minimized by raising their air pressure over that of adjacent airways. This can be done by checking off the intake escapeway near the working face. The Bureau of Mines has investigated the use of a parachute stopping as a quick-erect check curtain during mine fires, and the concept has been tested in several mines. In every instance, when a parachute stopping was erected on the section, the intake pressure went up substantially. The pressure-raising effect of the parachute persisted for up to 1200 m (4000 ft) outby. Results indicate that checking off the intake escapeway may serve as a viable way to improve safety during mine fires.

Jan 1, 1991

By J. P. Golightly

The nickeliferous laterites of Soroako are described in their setting in the huge Cretaceous ultramafic complexes of central Sulawesi, Indonesia. The ore bodies occur on spurs, ridges and hill flanks beneath remnants of extensive erosional surfaces. Weathering pro- files that have developed on unserpentinized harzburgite and on strongly serpentinized lherzolites show distinctive laterite structures, mineralogy and chemistry. The former are unique to the Soroako area and permit an unusual degree of upgrading by rejection of unserpentinized peridotite boulders. A mass balance calculated for a selection of profiles indicates that in situ leaching of a column of peridotite 20-50 meters thick has taken place with only minor lateral migration of nickel in solution.

Jan 1, 1979

By P. Coleman, J. C. Kerkering, S. Iverson

A fatal accident may result when a dozer is driven over a hidden void in a coal surge pile and the dozer falls into the void, burying and suffocating the dozer operator. This type of accident was analyzed by researchers from the Spokane Research Laboratory of the National Institute for Occupational Safely and Health using inexpensive fault-tree programs that had been developed, for use on a personal computer. Fault-tree analysis is a systematic safety-analysis tool that proceeds deductively from the occurrence of an accident event to the identification of the root causes of that event. The analysis identified basic and intermediate events that led to the burial of the dozer and graphically depicted the interrelationship between the basic events as well as the intermediate events leading up to the accident. A sensitivity analysis on assigned probabilities showed which events had the greatest influence on dozer burial in a coal surge pile. Operational guidelines and engineering controls are suggested to decrease the probability of a burial event.

Jan 1, 2002

By R. P. Killmeyer, R. E. Hucko, P. S. Jacobsen

Cleaning of three coals from the eastern US was tested by five selective agglomeration processes and one selective flocculation process. The coals and processes are described, and the results are reported and compared. Two of the processes, which ground the coal to the finest volume mean diameter, met the stringent test program quality specifications.

Jan 1, 1991

By S. S. Peng

Horizontal stress is an important factor that contributes to roof failure during longwall entry development, especially when the immediate roof is weak. In this paper, the effects of stress angle between the maximum horizontal stress and entry development and stress ratio of the maximum to minimum horizontal stresses on the stress distributions in the weak immediate roof of a three-entry system are analyzed using the finite element method. The results have confirmed that stress angle has a significant influence on the stress distributions. Generally, the three-entry system is in the worst stress condition when the stress angle is about 60° to 75° . The stress ratio has also some effects on the roof stresses.

Jan 1, 2000

By D. W. Park

The Longwall Strata-Control and Maintenance System (LoSCo-MS) is a software and data-communication system developed at the University of Alabama. This system integrates real-time shield monitoring, data presentation, analysis and the forecasting of forthcoming events. The main objective of this system is to provide stability information on longwall panels, including excessive shield load, low setting pressure, leg leakage, poor shield performance and imminent maintenance problems. Analyses of various mining and geological parameters were also performed to determine past and present roof characteristics and to forecast roof loading patterns for the following mining cycles, the next periodic weighting, etc. A local coal mine in the Warrior Coal Basin has adopted this system to provide daily evaluation of ground stability and maintenance problems in their longwall panels. Two years of experience with this system is covered in this paper.

Jan 1, 2000

By Tamás Megyeri, Dániel Borbély, Vera Szánto, László Kovács

"Upon completion, the Bátaapáti deep underground radioactive waste repository complex (National Radioactive Waste Repository - NRWR) will provide safe final disposal for low and medium-level radioactive waste from the Paks Nuclear Power Plant in Hungary. The waste emplacement is in progress and one of the main concerns related to the development is ensuring a feasible plan is in place for permanent repository closure. Detailed hydrogeological observations and safety assessments revealed that the clay filled fault zones penetrated with the access tunnels play determinant role in the long-term confinement performance of NRWR, so they need to be plugged. Detailed mechanical analysis and numerical modelling of the tunnel constructed through a fault zone is presented here to gain a better understanding of the rock mass and rock support behavior. The effect of stress reflection is demonstrated and its consequences are described in detail. A recommendation is given for tunnel support design in such conditions. INTRODUCTION Crossing fault zones is a challenging task during tunnel construction and can lead to failure if not properly accounted for during design and construction. These failures are can be caused by high water inflow or stability loss of the rock mass surrounding of the tunnel (examples can be found in CEDD, 2015). The prediction of the magnitude and development of displacement has a considerable impact on issues during tunnel construction. Changes of rock mass stiffness or structure ahead of the face, to a great extent influencing stresses in the vicinity of the tunnel and thus deformations (Steindorfer, 1998). Further research with numerical simulations was carried out, and the qualitative and quantitative evaluation of displacement vector is presented in (Grossauer et al, 2005). The concern associated with crossing fault zones was considered during the design of the Bátaapáti deep underground radioactive waste repository complex (NRWR) in Hungary. In the case of NRWR project, the fault zones have an impact on maintaining the stability of the surrounding rock mass as well as the final sealing of the repository. As part of the final closure design, a complex numerical modelling program was completed to gain a better understanding of the mechanical behavior of the rock mass and the monitoring observations during construction. Even though the need for the presented study is closely related to the NRWR project, the results can be used in any project related to fault zone crossing. The methodology used to better understand the impact of crossing fault zones for the NRWR project is presented in this paper. First the project background is introduced including an overview of the underground facilities, the aim of the repository, and the construction experience gained from the first crossings of the fault zones. After that the in-situ and laboratory testing is summarized. The numerical modelling methodology is detailed in the next section. Not only the outcome of the model is presented, but the results are compared with the experience and observations made on site. Since a good agreement is found between the actual and the modelled behavior, the conclusions are based on the validated result. To fulfill the aim of the paper, the stress reflection concept is introduced to explain the mechanical behavior of the fault zone and the rock support; furthermore straightforward suggestions are made for rock support design."

Jan 1, 2016

By G. D. Criswell, F. Palkovits, J. M. Johnson

A paste technology investigation was completed for non-pozzolanic fly ash from Units 3 & 4 of PPL Montana’s Colstrip Steam Electric Station. The purpose was to assess the feasibility of converting from dilute slurry deposition of ash products to a system using thickened or paste ash to reduce excess water storage in the impoundment, reduce seepage losses, and increase storage efficiency. The investigation included laboratory and field testing to characterize the rheological, geotechnical and dewatering properties of the ash products, an assessment of potential seepage reductions and an evaluation of potential for increased ash storage capacity by modifying impoundment operating procedures. The studies concluded that the conversion project was feasible, cost effective, and permittable. Critical facilities for the conversion project are currently under construction.

Jan 1, 2004

By A. Maréchal

It has been shown since a few years that the problem of estimating recoverable reserves should be solved by using specialized statistical techniques : whenever the selected blocks are chosen without any other constraint than a cut-off grade criterion, the problem of estimating the corresponding tonnage-grade curve is resolved by estimating the local histogram of block grades. Two major statistical techniques are currently used by geostatisticians to estimate local histograms : the "average conditional distribution" technique (Parker, Journel, Dixon 1979) and the disjunctive kriging technique. (Matheron, 1976, Jackson, Maréchal, 1979). Both have proved to be applicable in practice, with their pros and conconcerning their practibility and versatility.

Jan 1, 1982

By Adrian Smith

14.1 INTRODUCTION From the time the last recoverable gold is extracted from ore on a heap leach, the ore - now spent ore - changes from being the resource, indeed the raison d'etre of the operator, to a potential liability. The spent ore contains process chemicals and constituents leached from the ore both in the interstitial pore water in the heap and on the surfaces of spent ore. If these chemical species were released to the environment, it could have a potential impact on the quality of both surface water and groundwater resources. Accordingly, the spent ore must be left in a condition where it does not present a potential environmental liability. This can be accomplished either on a decommissioned pad or, if the heap leach is operated as a load/unload scheme, in a waste facility. In general, the residual cyanide level in the spent ore is the perceived controlling factor when determining whether the leached material is suitable for abandonment. Regulatory authorities set permit conditions for heap leach abandonment in terms of residual cyanide levels, for example, Smith and Struhsacker (1987). This chapter discusses cyanide degradation and methods for detoxifying a heap leach in order to meet regulatory limits/permit conditions for abandonment. Cyanide degradation and detoxification by "natural" processes are described initially, based on the chemistry and geochemistry discussed in Chapter 13. This leads to a review of chemical treatment processes for detoxification of spent ore. The advantages and apparent disadvantages are then appraised. 14.2 NATURAL DEGRADATION AND DETOXIFICATION For the purposes of discussion, "natural" detoxification processes can be divided into two alternatives: • Passive abandonment (the so-called "do nothing" option); and • Water In the first alternative, the spent ore is merely left on the leach pad to age; the second alternative involves the flushing of the spent ore with water.

Jan 1, 1988

By A. B. Holland-Batt

In the 1960s and 1970s, incremental development rather than innovation was the norm for gravity separation. However, the last 15 years have seen a number of new developments in this area. The article reviews the traditional gravity-separation techniques and then examines the newer developments such as centrifugal separators. Emphasis is placed on novel devices or improvements that offer better control or improved performance.

Jan 1, 1998

By Ivor Hawkes

INTRODUCTION High energy breaking is an alternative to using ex¬plosives in underground secondary breaking operations. It also is a means of upgrading conventional hand-held breakers, manual sledge-hammer breaking, and scaling bar operations. Major areas of application are in sec¬ondary breaking over grizzlies and at drawpoints. Other applications include breaking down ripping lips in longwall seam mining, scaling in stopes and rooms, general demolition work, and roadway maintenance. There is considerable interest in high-energy impact breakers for use in primary ore breaking, but, as of 1977, all such applications have been only experimental (duToit, 1973; Joughin, 1976; Wayment and Grantmyre, 1976). EQUIPMENT Essentially, a high-energy impact hammer is a boom¬mounted pneumatically or hydraulically actuated breaker. The machine basically consists of a piston that oscillates in a housing and impacts the end of a tool or moil thrust against the rock. The force applied to the rock primarily depends upon the impact energy of the piston-the higher the impact or blow energy, the greater the force and, thus, the greater the rock break¬age. Among drill and breaker designers, a common expression for blow energy is "force of blow." Hand-held breakers are limited to blow energies of about 140 J (100 ft-lb), because the operator is unable to handle heavier machines efficiently or to absorb the recoil energy resulting from higher blow energies. How¬ever, these restrictions do not apply to boom mounted breakers; machines with blow energies on the order of 4000 J (3000 ft-lb) and higher are available commer¬cially for underground use. There is considerable evi¬dence to show that increasing the blow energy also in¬creases the efficiency of the breaking operation; i.e., more rock is broken per unit of energy expended (Grantmyre and Hawkes, 1975). Thus, there is a trend to higher blow-energy machines, particularly where high¬strength rocks are to be broken. In relation to rock breaking, the blow rate of boom¬mounted impact breakers is not as important as it is for rock drills. This is because the breaker must be moved over the work surface between blows. The blow rate is governed eventually by the power supply, and typical blow rates range between 200 and 600 blows per minute. As a general rule, light blow-energy machines have higher blow rates than heavier machines. Table 1 lists most of the boom-mounted impact breakers that were available commercially during 1977, and it gives details of the blow energies and machine weights. Restrictions are placed on the blow energy by the machine weight and size, and by the strength of the boom. Typically, boom-mounted impact hammers have a blow-energy to mass ratio of about 1.5, with lower values for lighter machines and higher values for heavier machines. In addition to supporting the hammer weight, the boom also has to absorb the recoil energy of the blow, which can be on the order of 1400 J (1000 ft-lb) for large hammers operating in a horizontal mode. Interesting exceptions to the general run of impactors are the Joy HEFTI hydraulic hammers. In these machines, the piston impacts onto a fluid cushion that is positioned between the piston and the impact tool. This approach allows very high piston velocities, over 30 m/s (100 fps), to be used without the risk of break¬ing the piston or impact tool. Steel on steel impacts must be limited to impact velocities of about 10 m/s (35 fps) due to the high impact stresses generated; thus, increased blow energies can be achieved only by increas¬ing the piston size. The Joy 514 HEFTI®, listed in Table 1, has a blow energy of 27 100 J (20,000 ft-lb), but, as of 1977, the machine has been used underground only on an experimental basis. Using a fluid cushion between the piston and the impact tool allows the use of light pistons, reducing the overall machine weight. The recoil energy, which must be absorbed by the boom for a given blow energy, is directly proportional to the piston to machine mass ratio, and operating with light pistons provides an addi¬tional benefit in reducing the requisite boom size. Both pneumatic and hydraulic hammers are avail¬able commercially. Although hydraulic hammers are a relatively recent development, they already outnumber the pneumatic machines in use. There are many reasons

Jan 1, 1982