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By James J. Fallon

I'm glad this meeting is being held in New York. First, because the city is close to my home in New Jersey, only 35 minutes from Times Square ..... if I were to come to Times Square between two and three in the morning. Otherwise it takes two hours. But even more important is the fact that all of you good people from around the country and around the world will enjoy the unique experience of that warm friendly atmosphere in the greater metropolitan area, something that you won't see any place else on the face of the earth. Seriously, the greater metropolitan area has been a large part of my industrial, cultural and spiritual experience. There are many aspects of it which I find disagreeable but on net I would rather live in this area, at least for the time being, than any other area of the United States. As a consultant I find contact with financial institutions, corporate headquarters, information sources and a great many production and research facilities a valuable asset to my activity.

Jan 1, 1985

By C. K. Jankousky

The midwestern area referred to is the Illinois basin. The coals presently worked are mainly the No. 5 and No. 6 coal seams which vary in thickness from five to eleven feet. Present average of the more important No. 6 id about nine feet. The coal can vary considerably in toughness within the same mine with some coal perhaps rashing very easily and other coal being extremely difficult to cut. Top is generally well laminated shales with some fortunate areas having limestone roof. There are local areas with troublesome top of poorly laminated shales, shale with slickensides and shale intermingled with small partings and traces of coal. The bottoms are generally one to three feet of clay which softens readily on exposure to moisture. The mines are dry although some water is released and collects from rapid penetration of the seam by continuous miners. However, there are locally wet areas. Most of this material refers to mines of the Freeman Coal Mining Corporation. The mining operations written about are underground mines in southern and central Illinois.

Jan 1, 1962

By J. W. Leonard

Comments The venerable straight-line equation Y = Bx + A is again being rediscovered, but this time by economists, mining engineers and geologists. Two economists, William Sharpe and Harry Markowitz, from the University of Chicago and Stanford University, respectively, won the 1990 Noble Prize in economics by showing that the price of individual stocks can be related to the Dow Jones industrial average (DJIA) using the straight-line equation. According to Bill Chidester, Investment Analyst, Scientific Investment, Sharpe and Markowitz strongly emphasized the role of the beta (B) value while considering the alpha (A) value to be "pretty unimportant." Chidester claims that alpha is the "mystery" value that causes individual stocks to behave independently of popular stock-market indices, such as the DJIA. For many years, mining engineers and geologists have routinely called alpha the "nugget" or surprise element in geostatistical analyses in which a designated distance (x-axis) is related to the variance of the grade (y-axis). Because the influence of the independent variable (distance) over the dependent variable (grade variance) is ideal when alpha is equal to zero, any increase in alpha represents a loosening of influence or control within the relationship. This can be good news or bad news - good news if you are an economist sorting out off-trend stocks and bad news if you are a mining engineer trying to predict sulfur in a coal seam. With many mining trends, such as those involving the relationship of distance to the variance of grade, a mathematical relationship can be formed. In geostatistical analysis, the point where a mathematical trend ends is known as the sill. If the difference between the variance of grade at the sill and at alpha can be determined, then an estimate of the relative control for a given distance can be obtained by comparing the sill value to alpha. The extent to which alpha approaches the value of the sill provides an indication of independence or loss of trend. The alpha concept may find application with distance, time or fluid problems. The point of change can be either a change in trend or the trend limit. However, even without a clearly defined point of change or trend limit, increasing alpha values always infer loss of trend. Alpha analysis should be regarded as a valuable tool when sorting out many sets of mining data. The application of this user-friendly concept to reserves, material transport, fluid flow and other areas has been, and will continue to be, the basis of many important past and future developments in mining and geology.

Jan 1, 1996

By Gary L. Simmons

Over the past several years, Newmont Gold Company (previously Santa Fe Pacific Gold Corporation) developed a new technology for the flotation of refractory auriferous sulfide minerals which is referred to as the N2TEC flotation process. Starting in April 1997, the first commercial flotation plant utilizing N2TEC technology was successfully commissioned at the Lone Tree Mine near Valmy, Nevada. The Lone Tree flotation plant was designed to process 4,085 mt/d of ore producing 494 mt/d of sulfide concentrate. A flotation tails leach CIP circuit was added to recover cyanide-soluble gold from the flotation tails. A portion of the flotation concentrate is blended with whole ore feed to the Lone Tree autoclave, up to the limit imposed by the current oxygen plant capacity. The remainder of the concentrate is shipped to either the Twin Creeks autoclaves or the Carlin roaster for subsequent oxidation and gold extraction. This paper discusses the results achieved in the commercial flotation plant compared to pilot plant testing and engineering design flotation modeling. Capital and operating cost information are also presented.

Jan 1, 1999

By D. Harris, M. Osterberg

This paper examines the economics of acquiring mineral exploration rights by royalty-rate bidding when the royalty basis does not provide for full cost recovery. Bidding takes place prior to exploration and the documentation of actual tonnage and grade. Consequently, it increases considerably the risk to exploration capital when the fraction of cost recovered is small and the product price exhibits large fluctuations. Price and grade risk are demonstrated on a 360-Mt (400-million-st) porphyry copper deposit by Monte Carlo simulation of discounted-cash-flow analysis. Copper price is modeled as a stochastic price process, and costs are based on US Bureau of Mines cost models. When both grade and price risk are considered, the probability for a negative NPV is 0.54, given a royalty rate of 5% applied to a basis that allows the recovery of costs up to 50% of product price. Investment risk could be considerably reduced by defining the royalty basis to allow greater cost recovery. Although such a basis would require society to share in the risk, society would benefit from greater resource development.

Jan 1, 2000

By T. Reed Scollon

Major interrelated factors to be considered in assessing the impact of air pollution control regulations on coal are: (I) the fuel and fuel-related limitations of such regulations; (2) the rate of adoption and areal scope of the regulations; and (3) the availability of fuels and fuel-burning equipment to meet the requirements. A growing number of regulations contain provisions limiting the emissions of sulfur oxides or the sulfur content of fuels or both. With few exceptions, these limitations have not yet become fully effective in those areas which have already adopted regulations, and pertinent details of future regulations or legislation for most other areas are unknown at this time. Sufficient information is not avail- able to determine the availability of low-sulfur fuels at various demand and price levels, and large-scale commercial feasibility of sulfur-oxides removal processes and equipment is believed to be some years away. Accordingly, with the many uncertainties and unknowns, it is possible at best to make only a rough assessment of the impact of such regulations or legislation on coal.

Jan 1, 1969

By J. N. Carras, N. W. Bainbridge

In order to further the understanding of spontaneous heating of longwall goafs a numerical model was developed, based on conservation principles applied to the transport of heat, water vapour and oxygen across the god Advective air flow into the goaf is caused by the differential air pressures across the god The air velocity field within the goaf area was computed using Darcy's law. The boundary and initial conditions concern air pressure, temperature and relative humidity. The oxidation rates and heat generation rates of the goaf materials required for the simulation were obtained from laboratory measurements. The main outputs of the model are temperature, oxygen and water contour maps, the rate of air leakage into the go4 velocity field and pressure distribution across the god. The model while still in its development stage, is able to simulate a heterogenous goafs constructed from different materials with different thermal and mass flow properties. Validation of the model by comparing its output with measurements from within goafs is required before the model can be used with confidence in a predictive sense.

Jan 1, 1995

By G. F. Revey

Most commercial explosives contain from 70% to 94% (by weight) ammonium nitrate. When some of the explosives end up in shot rock and ore, through either spillage or incomplete detonation, ammonia and nitrates can leach into the ground water. In recent years, state and federal regulators have applied more stringent water-quality standards, particularly at new mines and development projects. When mining conditions permit, bulk ANFO, a mixture of ammonium nitrate and fuel oil, is the explosive of choice. ANFO is less costly than other explosives but it dissolves readily in water. Several case histories in the United States and Canada show a clear connection between uncontrolled losses of bulk explosives and high nitrate levels in mine effluents. Mining companies have tried several approaches to reduce ammonia and nitrate levels in groundwater. These approaches range from controlling explosive losses to treating the mine effluents. In this paper, controlling explosive losses is addressed For both packaged and bulk explosives, guidelines to limit losses during storage, handling and use are described in detail.

Jan 1, 1997

By Richard C. Smith, Steven H. Brown

Commercial scale in-situ leach uranium facilities (i.e., solution mining) have operated since late 1975, and have begun to appear in increasing numbers in the last few years. Solution mining involves the pumping of ground water, fortified with oxidizing and complexing agents, into an ore body, leaching and solubilizing the uranium in-situ, and then pumping the solutions to the surface where they are fed to a mill. Milling is by conventional means, involving ion exchange, precipitation, calcining and packaging processes. This paper presents an overview of the solution mining process, and discusses an empirical method that has been used to determine the radon gas release rate in Bq (curies) per year for the overall operation of the facility including wellfields, milling processes and waste storage reservoirs. In addition to radon generation on the surface from radium decay, it has been determined that the major component of radon release is associated with the dynamic generation of radon from solutions returning from underground. Process parameters impacting this evaluation and the mathematical expressions developed are discussed. The preliminary data accrued is presented.

Jan 1, 1981

In underground coal mining, one of the biggest challenges is spontaneous combustion, which will not only present safety hazards but result in reserve losses as a result of burnt coal. The released heat coupled with other combustible gases commonly encountered underground will significantly increase the risk of explosion. In this paper, three-phase foam as an environment-friendly fire fighting agent composed of nitrogen, water and fly ash is introduced. The nitrogen facilitates inertization of the fire zone; the water helps cool down the fire and the fly ash can closely cover the coal to isolate the oxygen. What's more, the fly ash and the foaming agent are good free radical absorption. The comprehensive merits mentioned above make three-phase foam quite effective in quenching spontaneous combustion. Experiments indicate that three-phase foam can significantly slow down the temperature rise of coal during oxidation. The comparison between slurry and three-phase foam shows that the latter one is capable of flowing upward in the porous media so as to extinguish the high-point fire and concealed fire.

Jan 1, 2011

By George A. Lawrence

A new super-large 100 m3 (3500 ft3) pneumatic mechanical flotation cell is now available to meet today's mineral processing challenges. Several innovative design concepts represent a marked departure from conventional flotation cell designs. The radial discharge from the pump action rotor and the overhung vane type stator is contained in a conical bottom round tank with no dead comers. Peripheral launders collect froth overflowing the entire circumference of the tank and these launders are of a hexagonal design permitting cells to be nested together in a honeycomb fashion. The mechanism drive is either a customized right angle gear reducer or a conventional Vee belt drive. Both drive systems are available with an optional variable frequency control system that permits infinite speed adjustment of the rotor in each flotation cell or group of cells. Results of side-by-side comparative testing between three major manufacturers of super-large pneumatic mechanical flotation cells are discussed. These results were obtained at a large copper concentrator in Chile during several weeks of commercial scale testing.

Jan 1, 1995

By D. Krzyszton, P. Czaja

Mining explosions in rocks originate stress waves of great intensity, which crush the surrounding rocks and are then propagated as a seismic wave. Seismic waves are the cause of dynamic loading of pillars and their subsequent destruction. In calculating safe dimensions for inter-room pillars, not only the stresses conditioned by overburden pressures should be taken into consideration, but also the dynamic stresses caused by explosion. This is of particular importance for pillars with great specific acoustic impedance which have been destroyed mainly by the reflected seismic wave. It is possible to take dynamic loading into consideration in the calculation of pillars when the parameters of the propagation wave, the dynamic elastic constants of rocks, the strength properties of rocks, the strength properties of rocks subjected to dynamic loads and the parameters of the blasting charge are known. An example of the calculation for the safe width of an inter-room pillar subjected to the seismic effect of an explosion is given and the possibilities of reducing the dynamic loading of pillars are discussed.

Jan 1, 1982

By Bobby J. Timmons

A few years ago during a Southeastern Geological Society field trip, a professor from a Florida university and a trip leader commented at one of the stops, "... and for those of you interested in the geology ...." More recently, in the spring of 1992, a geology faculty member at another southeastern university remarked, "Field geology is obsolete." An interviewee for a potential assistant position stated that he had never had a field class. This would-be assistant was to receive his Master's Degree in-Geology within a few days from yet another southeastern university. A regional illness? Certainly not, but symptomatic of the general health of Geology. Capitulation to Environmental Sciences seems to be in vogue with Geology becoming a four-letter word and the mention of mining is verboten regardless of the company. These trends permeate our profession while the demands for earth materials increase, often exponentially. Efficiency, a word lost on government, is routinely expected of business--our business--the industrial minerals geologist and producer. Our stage shrinks but the responsibilities expand. Are we meeting the challenge? Stay tuned!

Jan 1, 1995

By M. J. McPherson, P. Mousset-Jones, G. Danko, I. M. Konduri, F. Calizaya

The flow of air through a bare rock, underground airway is affected by the size and frequency of the micro- and macro-asperities of the rough surface. The focus of this study is to characterize this roughness using the coefficient of friction, the friction factor and the fractal dimension. The rough surfaces were identified by two sets of 177 and 78 transverse profiles measured by a laser profiler along the length of an underground airway at the Sunshine Mine, Idaho. Based on the measurements, the friction factor was estimated from Atkinson's equation and the coefficient of friction from the Moody diagram, and power series and variography were used for computing a fractal dimension for the airway surface. Significant conclusions are reached relating the effect of error in the measurement of cross-sectional and rubbing surface areas of a drift, on the estimated friction factor for the airway. The potential role of the fractal dimension as an alternative to the friction factor for characterizing the roughness of a mine airway is discussed.

Jan 1, 1993

By Abdullah Arik

The resource classification methodologies have always been a topic of research and debate. There are both traditional and Geostatistical methods used in practice. Because of the uniqueness of each ore deposit, it seems almost impossible to have a single industry-accepted norm for resource classification. Therefore, some practitioners have adapted the methodologies to suit the deposits they are working on, but many simply use the methods they are comfortable with. Another reason for the existence of varying classification methodologies is the lack of an easy and established way to measure the confidence in the estimates. Therefore, their classification becomes a subject of debate. In this paper, a new approach is offered to classify the resources using a "Resource Classification Index." The approach using this index takes into account the local variation, the spatial data configuration around the block being estimated, as well as the traditional distance measures. A case study for a gold deposit is presented to demonstrate how this new index can be used to classify the resources. The results from this approach are compared to those from two popular classification methodologies.

Jan 1, 2002

By X. Zhu

Establishment and monitoring of revegetation in areas affected by mining activities is quite often a difficult task. The efficiency of the scheme applied can be substantially improved by using simple adequate indicators so that progress and trends can be plotted, elucidated and assessed over time. Sustainable revegetation management indicators should take into account soil quality and area characteristics, as well as social, economic and political aspects. In the present paper an interactive prototype Spatial Decision Support System (SDSS) is presented. The system, based on methodological studies, has been designed to identify and interpret indicators that can be used for the evaluation of revegetation efficiency. It provides a platform for formulating indicators describing biophysical, socio-cultural and economic processes during the entire revegetation period. It integrates modular assessment, database management sub-systems and Geographical Information System (GIS). It is structured in a way that takes into account the project environment, soil quality, land characteristics, data acquisition control, output engines and spatial analysis. The output generates visual quality diagrams and interactive attribute quality maps that elucidate revegetation issues.

Jan 1, 2007

By A. Bascetin, A. Nieto

One of the most difficult problems in mining operation is how to determine optimum cutoff grades of ores at different periods over the lifespan of the mine that will maximize the net present value (NPV) of the mine. Cutoff grade optimization maximizes the NPV of a project subject to capacity constraints in the mine, mill and the market.. This paper describes the determination of a cutoff grade strategy based on K. Lane’s algorithm adding an iterative optimization factor calculated for every year during the live of the mine to maximize the project’s NPV. The introduced algorithm is a windows based program developed at Virginia Tech which coded in visual-basic within a spreadsheet environment (Excel). The resulting cut-off windows based program is a user-friendly tool which calculates interactively different mining cutoff grade scenarios. The benefits of the methodology are demonstrated using a hypothetical case study. The authors have observed an improvement of the total NPV using this iterative approach using a year by year optimization factor.

Jan 1, 2007

By G. S. Dobby, N. J. Contini, S. W. Wilson

Scale-up and simulation of flotation columns requires construction of mathematical models which employ, as a minimum, rate constants for quantifying particle recovery in the collection zone as well as split factors for quantifying froth zone performance. To date, measurement of these rate parameters has proven to be difficult, due to the interdependent nature of the collection and froth zones. This paper describes a technique for making these measurements. The method requires recovery data from two modes of operation: countercurrent and cocurrent. In cocurrent flow slurry is fed at the bottom of the column and tailings are withdrawn a short distance below the froth interface. Countercurrent mode is conventional operation. The critical difference is that particles which are dropped out of the froth in cocurrent mode are immediately lost to tailings, while in countercurrent mode the particles are subjected to recollection. Fitting of the measured recoveries to the equations that describe flotation in the two modes yields rate constant or recovery values for both the collection and the froth zones.

Jan 1, 1988

By J. Finch, J. Yianatos, N. W. Johnson, R. Espinosa-Gomez

A method of determining the maximum concentrate solids rate or carrying capacity is described for given column operating conditions. The method requires alteration of the feed rate of solids to the column at a fixed residence time by manipulation of the % solid of the column feed pulp or the bias rate. The carrying capacity was measured for five streams at the Mt. Isa Mines Pb/Zn and Cu concentrators. As a potential scale up parameter, the mass of solids per unit time per unit column cross section (Ca, g/min.cm2) is explored. Ca is tentatively related linearly to the 80% passing size (d80) of the concentrate. For d80 < 15 pm Ca was less than 4 g/min.cm2 (8 lb/min.ft2) which makes it a critical consideration in scale-up for such fine feeds. An alternative carrying capacity parameter, mass of solids per unit volume of gas Cg was not as useful as Ca since Cg varied inversely with gas rate.

Jan 1, 1988

By R. R. Jozefowicz, T. X. Ren, J. S. Edwards

The control of methane emission into underground mine workings is important both for the safety and productivity of the mine. As deeper and gasser coal seams are mined, ventilation methods involving increasing air pressures and quantities across mine workings may not be able to cope consistently with methane emission rates during the production cycle. An accurate prediction of methane emission into mine workings is of great significance in the design of ventilation systems and additional methane control methods if required. Research has been conducted to develop a numerical method for simulating methane flow through strata in which permeability is strongly influenced by mining-induced stress. To achieve this objective, both numerical modelling using Computational Fluid Dynamics (CFD) and laboratory tests on rock samples and granular materials under triaxial stress condition were carried out. Correlation has been established between stress and permeability characteristics of rock-measure rocks and laboratory results are being incorporated into the CFD models. This paper introduces the use of CFD techniques to model methane flow through permeable strata around longwall coal faces currently undertaken at the University of Nottingham.

Jan 1, 1997