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By Liu Wenyong, Huang Yucheng, Yang Ba

High-water rapid-solidifying material, called æhigh-water materialÆ, is a new material developed by the authors over many years. The material can solidify nine times its volume of water into solid. The material is a fine kind of binder with special properties. The solidifying body of high-water material with water has quite a high early strength. The compressive strength of the material within three days can reach the same strength as conventional Portland in 28 days. One ton of the material can replace three tons of conventional Portland cement as binder. Some important achievements have been made in application of high-water material. In metal mines, based on the material, a new full-tailing cemented backfill technology has been developed. The characteristic of the new technology is that high-water material is used as binder and full tailing or alluvial sand is used as backfill aggregate. Because of the application of the new technology, major technical problems in backfill technology such as classifying of tailing, dewatering, transportation of pulp, low strength of backfill body, environmental contamination and so on, have been solved.

Jan 1, 1998

By Michael S. Wieland

The work-principle method was developed for theoretically resolving toxic fumes from non-ideal charge formulations. The whole description of a wanted process refers to macroscopic changes resulting from removing and imposing constraints that work one at a time to chronologically render trajectory terminal (key) states. The trajectory resolution utilizes a thermodynamic quasi-potential or negative work function, and numeric results require some appropriate standard thermodynamic (equilibrium) reaction code TDRC. The underlying method is unable to restrict reactions, tailor the work output or resolve states within the trajectory transitions, so the trajectory terminology is used somewhat figuratively. The work-principle model has the working fluid (reaction material) interacting with a tremendous reservoir (chamber air and walls), while forecasting the work performed upon a mechanical agent.

Jan 1, 1998

By D. G. Brophey, J. A. O’Neill

"High costs, both in terms of human resources and financial costs, have long been the end result of accidents involving vehicles which continue to occur too often throughout our industry.For example, radio remote control LHDs too often seriously injure their operators in underground operations. Costly efforts are required by mine owners to provide safety bays and platforms from which their operators can work safely. In open pit operations, large heavy haulers have too frequently backed over vehicles or turned into vehicles unfortunate enough to be situated in their large blind spots. These are just two examples of situations that have occurred again and again under similar circumstances.Meanwhile, electronic methods of detecting proximity to vehicles have continued to develop. The time has come for the industry to think “outside the box” to evaluate whether many of these new methods can solve these recurring problems.This note takes a look at various types of proximity detection technologies that are in use today in other industries, and discusses the various potential applications within our industry."

Jan 1, 1998

By Tim Ross

Slurry injection into mined-out panels is an attractive alternative for disposal of coal preparation plant fines. however, in areas where surface subsidence cannot be tolerated, either by law or necessity to protect surface structures or aquifers, special consideration trust he given to the effect of slurry injection on panel stability. Slurry injection can lead to panel failure and unplanned subsidence by degrading roof, pillar, and floor strength. Water degradation is of particular concern where clay is present in the floor. Recently. unplanned subsidence related to slurry injection occurred at an Indiana room-and-pillar coal mine subject to weak floor conditions. This paper discusses the efforts of the mine operator to determine the causes of the panel failure and to design panels and injection procedures to allow for future economic slurry injection without subsidence. The numerical and empirical/analytical techniques applied give the operator a rational approach to pillar panel design for future injection panels under various cover depths and weak floor conditions.

Jan 1, 1998

By George Weinman

GEORGE WEINMAN: Our first group leader for the discussion, "Ups and Downs of Downsizing," wishes to remain anonymous. ANONYMOUS PRESENTER: When George and Jamie asked me to do this, I thought a while about what to say and went through several variations of what I’ll present today. I came up with the title "Ups and Downs of Downsizing." A lot of downsizing has occurred in all of our industries-mining in particular. While this downsizing has gone on there's no doubt that all of us produced more and more, probably with less and less people and less and less resources. But I contend that there's also a big downside associated with this. I disagree with a point made in the keynote presentation yesterday, the point being that vendors are bringing new technology to us. I can agree that the major changes associated with equipment and similar items are being brought to us by vendors. But I do contend that there's an awful lot that's getting away from us-especially if you factor in the integrated supply or the strategic alliance or the various and sundry related purchasing techniques. I contend that we are missing a lot of, let's call it, lesser technology; not major equipment changes, but different tools, different techniques for doing things, different left-handed widgets. The integrated suppliers, to some degree, are bringing this to us; but I am concerned about the small guy who comes up with a good idea but deals through integrated suppliers rather than having direct contact with plant people. They're probably going to go somewhere else and market their wares. That's what I'm hearing from a lot of smaller vendors. I also think that we are losing a lot of our knowledge base. Every time you shrink an organization somebody leaves. The bottom line: less people. When a person leaves-and I don't care who he or she is, be it the janitor who's cleaning the bathroom, the operator, the engineer-when that person leaves there's some knowledge that goes with that per- son. And sometimes that knowledge is quite valuable. I've worked more or less at the plant "low." I can't tell you how many excellent, viable projects have come from people who said, "Look here. There's a better way of doing this." And, you know, they were right. Now, maybe they didn't have the resources or the expertise to develop these ideas into full projects, but they had that basic idea. Someone may say, "Well, if we put a no. 6 skyhook here, so we can lift this particular pump without bringing a crane from 30 miles away ...." No. 6 skyhooks are a bit expensive, but what if we put together a little structural steel here or whatnot?

Jan 1, 1998

How often does one hear that a recent feasibility study was not a success? Alternatively, when scope of the feasibility study was sent out to tender there was a large discrepancy in tendered prices. If the tendered prices were to be compared to the consumer market, for instance the purchase of a car, where the concept is transport in a controlled and safe manner, prices vary by large factors, but then so do the specifications. In the case of a feasibility study, prices should be within a tighter margin as the tenderers are all quoting against the same concept and specification. Why do these discrepancies occur? Price discrepancies will in every likelihood be attributed to two main factors; one, the perceived amount of work and two, the ability of the bidder to carry the risk associated with the feasibility study. It is, therefore, important that the scoping of the feasibility study covers the detailed requirements as clearly as possible stating what level of accuracy is required. The feasibility study is one of the first activities in the life of a project. The study, like the project it is investigating, is subject to the constraints of time, cost and quality. Its primary objectives are to demonstrate the viability of a project within the outlined scope and constraints.

Jan 1, 1998

By Graeme Exelby

The 4" Wassara water hammer was originally developed by G-Drill AB together with Swedish Mining Company LKAB for their underground long hole production drilling. Sandvik Rock Tools AB is responsible for the introduction of Wassara worldwide.

Jan 1, 1998

By J. A. Finch

In this paper, the author offers a personal view of what the next 30 years holds for mineral processing. Restating that mineral processing will remain a vibrant industry in raw material production, growth opportunities in waste management are identified. The processing sequence familiar now (mining ?mineral processing ?extraction) will become more interwoven. In situ processing (i.e., milling underground) will evolve from concept to demonstration. Opportunities to exploit physical properties altered in chemical (pyro- and hydro-) processing will present themselves. In primary grinding, the path to AG/SAG milling will progress with little deviation but opportunities in regrinding are wide open. Flotation will see the trend to designing bubble/particle reactors accelerate simultaneously with a vigorous response from mechanical cell suppliers. Gravity separation remains a bastion of the lone inventor but this author anticipates that the new lines will come from the waste management business. The paper concludes with the examination of the “research cycle” and identification of growth in small “high tech” companies and university research centres

Jan 1, 1998

By S. A. Matthews, M. L. Nave

AC variable frequency motor drives are emerging technology for belt conveyors. The success of the application in mining depends on adequate and timely consideration of drive, motor, and conveyor features. The purpose of this paper is to familiarize and inform possible mining users of AC variable frequency drive attributes.

Jan 1, 1998

By Adeloju S, McQuade CV, Riley SJ

Metal contamination of sediments can be an issue for minesites discharging water. Water sampling of receiving waters is frequently undertaken. Sampling and analysis of sediment is less common. The variability of receiving environments makes the formulation of a generic sediment sampling strategy virtually impossible. Each situation needs to be carefully assessed before sampling is undertaken. This paper outlines the approach taken for one such survey.The main factors that need to be considered in a survey of surficial sediments are sample representativeness and sample variability. A simple data set from one site within a regional survey is used to illustrate the importance of these factors. The metal content of sediment is shown to vary significantly over small spatial scales.The variability associated with the spatial distribution of samples within a site is shown to be the most significant source of variability in the study. This variability could bias the results of a study if not planned for in the sampling methodology. Taking multiple samples from within each site (sub-site samples) and combining the data gives a more representative indicator of overall conditions than a single sample. The optimum number of sub-site samples to be taken from each sampling site was found to be 15.It is shown that a composite of sub-site samples can give a good indication of the average site metal content, while considerably reducing the sample preparation and analysis effort.

Jan 1, 1998

By Dharmappa HB, Sivakumar M

This paper is concerned with two case histories of wastewater quality management in underground coal mines in the Illawarra region. The first investigation briefly presents an analysis of mine water discharge having an extremely high concentration of suspended solids and consistently high barium concentrations, averaging, 14.4 mg/I Barium, over the sampling period. A laboratory study of chemical precipitation processes has indicated that about 91% of barium could be removed by using ferric sulphate and lime. On the basis of the information obtained from the environmental audit process an alternative water treatment and reuse system incorporating 51% reduction in the water consumption with 32% less off-site discharge has been suggested (Thomas, 1995).The second case history is concerned with the storm water management at a mine situated in the Illawarra escarpment where only 20% of the wastewater generated in the colliery is discharged off-site. Computer modelling of the storm water system showed that 75% of the clean runoff becomes contaminated through poor management practices and causes the process wastewater treatment system to fail in wet weather. Suggested improvements include relatively simple alteration to the coal wash filtration dams which are expected to reduce the periods of inefficient operation of these dams by 95%. The use of storm water diversion channels and detention basins can reduce the overflow volumes by 70 - 100 % for a ten year ARI (Average Recurrence Interval) storm event (Wingrove 1996).

Jan 1, 1998

By Yajie Wang

Traditionally, roof falls are usually attributed to bad roof strata and high vertical stress related to the overburden depth. However, roof falls under shallow overburden depth are oflen caused by a high horizontal stress field. Recent studies have proven that the high horizontal stress field, if existing, plays a major role in roof stability. Also the roof conditions are related to the entry diredions under a horizontal stress field. Questions are: How to orient the entry to a favorable direction to prevent the roof falls? If the entry cannot be oriented, how to support it? Through a case study in mine A, this paper analyzes the horizontal stress effect on roof stability. The guideline for the entry orientation is given based on the results of analysis. Additionally, suggestions are made for those entries that cannot be oriented to a favorable direction.

Jan 1, 1998

By Siddall B

A brief review of the capabilities and practical limitations of blast simulation packages has been carried out. It is concluded that the simulators accurately reflect size distributions in the mid-ranges of 0.1 to 1.0 in, but are less reliable

Jan 1, 1998

By P Andersson, P Marklund

Evaluation of different techniques for bottom fill stabilisation showed that frozen fill was the most economical method. In order to test the method a full-scale field test was performed in the Rehnstr÷m mine. The test was instrumented with temperature gauges and extensometers. Before the field test, frozen fill was tested at the laboratory. The mechanical properties of the frozen fill were determined by uniaxial compression and creep tests. A deformation model for the frozen fill was set up. Calculation procedure for design of spacing between the freezing tubes, time for freezing and calculation of the necessary capacity of the refrigeration plant was developed. These procedures were calibrated against the field test. The results of these investigations allow the following conclusions: From a mechanical point of view, frozen fill has excellent properties as a structural member and it also has excellent properties to support itself and the fill above. Methods for the thermal and mechanical design of freeze stabilisation have been developed and found adequate. The need to place the freezing tubes several years in advance of the future sill pillar mining, requires careful long-term planning and accurate documentation.

Jan 1, 1998

By I Cameron

Simulation is increasingly being used to analyse mineral processing operations and explore efficiency options. Engineers that use simulation are rightly concerned with the quality and applicability of the underlying models. However, many of these models have a significant empirical component, and the best structure for this component may not be apparent. There is an opportunity to improve the quality and application range of these models by exploring potential structures for this empirical element. One approach to this problem is the use of structural optimisation, which is a formalisation of the model development process. This method searches through a family or hyper-structure of candidate models for a model that is optimal with respect to some measure of model quality. This method has been applied to the modelling of an industrial flotation circuit. The result was a model that was a significant improvement over a number of standard models reported in the literature. Structural optimisation provides a method to compare potential models in a systematic and efficient way, and hence to improve the structure of process models.

Jan 1, 1998

By Roger G. Sprague

With the passing of time, changing marketplaces and years of hard service, coupled with new machines, increased productivity, rapidly improving technology, equipment which used to be the latest in modern mining have now slipped into obsolence. Mining companies need reliable, productive equipment in order to compete in today's market. In Western coal mining, as coal seams become deeper, older equipment must be replaced with that which can do the job more efficiently.

Jan 1, 1998

By A. Coulombe

"RésuméL’analyse des séquences d’exploitation, actuellement en usage pour les gisements très inclinés, a démontré qu’elles ne sont pas toujours optimales du point de vue du contrôle des terrains et de la concentration des travaux d’abattage (nombre de chantiers simultanément en opération). Effectivement plusieurs séquences sont très propices à la création des nombreuses zones de hautes contraintes, qui sont à l’origine des effets de pilier. L’étude de cas de la mine Lac Shortt a démontré que certaines séquences d’exploitation, actuellement en usage, ne sont surtout pas adéquates dans le cas d’un état élevé des contraintes naturelles. En effet la mine a eu de sérieuses problèmes avec le contrôle des terrains (coups de terrains et les effondrements des épontes). Ces effondrements étaient responsables de la dilution excessive et des pertes importantes des réserves minières. Les deux nouvelles séquences proposées, visent la meilleure redistribution des contraintes d’exploitation en vue d’éliminer la création des effets de pilier. En plus elles permettent une concentration plus élevée des travaux d’abattage.À notre avis les séquences proposées pourraient améliorer substantiellement la stabilité des chantiers d’abattage et par la suite les performances technique et économique des opérations souterraines. ABSTRACTThe planning of underground mining sequences represents an important aspect of the mining operation. The analysis of mining sequences actually in use for very steep orebodies has demonstrated that they are not always optimal, considering ground control and the number of stopes simultaneously in extraction. These sequences are conducive to the creation in the rockmass of several stressed zones caused by pillar effects. The case study of Lac Shortt mine showed that the sequences of exploitation currently in use are not adequate especially in the case of a high state of the natural constraints. Indeed, the mine had serious problems with ground control (rock bursts and collapse of walls). These collapses were responsible for excessive dilution and significant losses of mining reserves. The two new sequences suggested aim for the best redistribution of exploitation constraints in order to eliminate creation of pillar effects. Moreover, they allow a higher number of stopes to be extracted simultaneously. In the opinion of the authors, the sequences suggested could substantially improve the stability of working areas and, thereafter, technical and economical performances of the underground operations."

Jan 1, 1998

By Greg Barfoot, Kurt Keskimaki

The Henderson Mine is located approximately 50 miles west of Denver, Colorado. A project is underway to replace the existing rail system which transports molybdenum ore 15 miles from the mine to the mill using three flight conveyor system. The first conveyor is a 1 mile, high lift conveyor which transports the ore from an underground crushing station to the end of the existing rail tunnel. The second conveyor is 10 miles in length and utilizes the existing rail tunnel to transport the ore from the mine, which is on the east side of the Continental Divide, to the mill located on the west side. The third conveyor takes ore from the tunnel portal to the mill through a series of 7 horizontal curves and inclines up to 15 degrees. The project applies advanced conveyor design to tackle the installation of the system in an operating mine and achieve the highest possible level of reliability. This paper outlines the design process for this system, discusses the options which were evaluated and how the current design evolved.

Jan 1, 1998

By A. P. Cook

Methane Rating has been developed from a need, in South Africa, for quick and simple measurement of coal face methane characteristics. It employs proven existing direct measurement methods, adapted specifically for rapidly advancing coal face conditions, to deal with the short term high release rates encountered during continuous miner coal cutting. The Rating is a comparative value, relative to the normal or average conditions encountered within a maintained data base. The seam gas content and the initial emission rate are plotted against each other on a graph, where they are compared with the average conditions to obtain the rating. The higher the seam gas content, and the higher the initial methane release rate, then the higher the Methane Rating, on a scale of 1 to 4. Methane being released from a newly mined coal sample is measured once underground, from a sealed gas-tight canister. The sample is returned, still sealed, to surface and milled to rapidly release the remaining methane. It is later intended that the milling process is also completed underground. Applications include the identification of changing methane conditions, outburst prone conditions, methane emission against advance, and mining in devolatilised coal.

Jan 1, 1998

By C. Sui, J. E. Nesset, M. Li, J. Y. Kim, S. L. Chryssoulis

"A plant study of zinc rougher flotation at Brunswick Mining was conducted using lime, soda ash and a combination of both as the pH modifiers in order to establish the effects on sphalerite and pyrite kinetics and mineral selectivity. The plant sampling and analysis was augmented by surface analysis using TOF-LIMS, SEM and XPS as well as fundamental precipitation and surface-charge studies in the sphalerite Ca/C03/S04 system.The results revealed the important role of carbonate ions in cleaning the sphalerite surface for effective activation by CuS04 to occur, and the beneficial role of combined soda ash and lime in increasing pyrite and galena depression.1.0 IntroductionThe studies reported in this paper were initiated as part of an investigation into the causes of a particularly pronounced seasonal deterioration in metallurgical performance at the Brunswick Mining concentrator during the summer of 1995. The concentrator treats a complex base metal ore having a typical feed composition of 9.0% Zn, 3.5% Pb, 0.4% Cu and 100g/t Ag at a current throughput of 9,000 TPD, although at the time of the problem in 1995, the average production rate was closer to 10,500 TPD. Zinc, lead, copper and bulk (zinc-lead) concentrates are produced with overall metal recoveries of 86% zinc, 63% lead, 60% copper and 60% silver; results which are typical of the lower recoveries associated with fine-grained, highly complex VMS and SEDEX type deposits. The main economic minerals of interest are an iron-containing (7% Fe) sphalerite, galena and chalcopyrite with the main diluent (about 60% wt) being pyrite.Figure 1 shows a simplified flowsheet of the Brunswick milling circuit while the seasonal decrease in summer metallurgy in 1995 is illustrated in Figure 2. Of significance is the rapid drop in copper and lead recovery in June while there is an apparent delay until late August-September before the zinc deterioration reaches its lowest point. A more typical seasonal effect within the experience of the authors is the reverse of the Brunswick situation, namely an improvement in summer performance thought to be associated with improved differential flotation kinetics during warmer weather leading to better mineral selectivity. The historical Brunswick experience was particularly severe during the summer of 1995 with estimated incremental losses of $10 Million for this period. The potential of the very significant economic benefits to be gained from understanding and hopefully improving the annual drop in performance led to an investigation involving the minesite metallurgical group, the Noranda Technology Centre (NTC) as well as researchers in Professor Jim Finch's group at McGill and the surface analytical services and interpretive skills of AMTEL."

Jan 1, 1998