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By Hill McDonald

Sand and gravel deposits may be explored by many different methods. The methods used by The Standard Slag Company are primarily two in nature. One is using an auger which is limited in depth by various soil conditions. The other is a heavy wall dry sampler and a heavy wall wet sampler. The heavy wall dry sampler takes continuous uncontaminated samples up to seven inches in diameter. The heavy wall wet sampler takes continuous uncontaminated samples up to six inches in diameter. For us, the maximum depth of the heavy wall samplers has been two hundred fifty feet of which one hundred feet was above the water table and one hundred fifty feet was below the water table.

Jan 1, 1972

By Jeong-Heum Kim, Jan M. Mutmansky

A number of solution methods for solving the nonlinear equations derived from mine ventilation networks use meshes selected from the network as the basis of the solution techniques. Mathematicians working in network theory have outlined several methods for speeding up the computations through mesh selection and ordering procedures. In the mine ventilation area, a fair amount of attention has been paid by ventilation specialists to procedures for choosing the meshes so that the computational effort is eased. However, little attention has been paid to mesh ordering methods. This paper outlines research into random mesh ordering procedures plus two non-random mesh ordering procedures and compares some results using these procedures within four solution algorithms.

Jan 1, 1993

By Andrew J. Neale, Mark Franklin, Mike Cooper

Although recent advances have significantly improved our understanding of flotation fundamentals, disturbance variables combine to make it difficult to maintain steady state operating conditions over either the short or long term. One of the major concerns relates to knowing how much reagent to add to the flotation system, how to monitor the addition rate, and how to determine when to adjust the reagent addition rate in the presence of these disturbances. This paper will look at the development and installation of process control systems that address these issues. The economic benefits that accrued from the implementation of these strategies is described.

Jan 1, 1994

By Stanislaw Wasolewski

Computerized systems for ventilation parameters monitoring which are used in Polish coal mines provide the ventilation staff with a great number of measuring data. These data can be used to get knowledge about dynamic properties of ventilation process and disturbances affecting its state. This is necessary to create a reasonable concept of mine ventilation control system and make a practical application of such system. In the paper a method of ventilation process identification with the use of measuring data from monitoring system is described. Computer analysis of time series including statistical, correlation and frequency methods are applied to estimate dynamic properties of ventilation process and its disturbances. Using the Fast Fourier Transformation (FFT) algorithm the parameters of the process have been obtained which can be efectively used in a system for mine ventilation control.

Jan 1, 1991

By Ronald S. Conti, Harry Dobroski

Re1iabl e monitoring a1ong an underground mine belt line is of great concern because of combustibles, electrical apparatus, and friction. Belt entries are strategically located where a fire can have rapid and disastrous consequences. This paper reviews conventional distributed temperature sensing systems based on resistive, thermistor, and thermocouple effects. These are shown to provide limited benefits. A new system tested by the U.S. Bureau of Mines based on fiber optics and time domain reflectrometry, promises much better temperature and spatial resolution, faster response, inexpensive cable, longer distance, and comprehensive data analysis. Test results in a small, controlled, in-mine fire are given.

Jan 1, 1992

By D. Lenartowicz, K. R. Alexander, M Collings

Cosmo Howley is a gold deposit in the Northern Territory of Australia. The geology is complex and the input of geological data is an important part of the grade control process. As the geology of the deposit has become better understood, grade control and mining techniques have evolved to meet the changing circumstances. Present grade control depends on the use of angled blast holes, 21/2 benches and selective mining. Data is processed on site using 2 386 PC's running Surpac software. An environmental protection programme is employed, including soil stripping and stockpiling, sulphide waste containment and water quality monitoring.

Jan 1, 1989

By S. B. Gaidhani, V. A. Mandlekar, R. L. Sonolikar

Column flotation technique is applied for the depression of the magnetic material by the application of an axial magnetic field from chalcopyrite ore. It is observed that an increase in the intensity of magnetic field from 0 to 316.8 oersteds decreased the magnetic content in the froth from 25 to 2 %. . This might be due to retention of magnetic material in the magnetizable zone and the diffusion of nonmagnetics through it. The effect of air velocity increased the magnetic content in the froth and total froth content also. At low gas velocity the tiny bubbles are formed whereas at high gas velocity these coalesce into big bubbles and slugs formed breaks the magnetizable zone. This study opens a new field called 'Magneto-flotation'.

Jan 1, 1988

By J. Pang, S. Chander, A. Briceno

The mechanism of sulfur oxidation in pyrite is a function of the rate and driving force for oxidation. New evidence is presented to show that, at moderate potentials, a sulfur-rich hydrophobic layer is formed. Under ordinary conditions, the sulfur layer is covered with a layer of iron oxides, hydroxides, sulfate or oxy-sulfide ions. Pyrite is hydrophilic under these conditions. In the presence of iron-chelating agents or iron sequestering ions, an iron layer might not form. Under these conditions, the sulfur layer is exposed, and the pyrite might become hydrophobic. Stronger oxidizing conditions decompose the sulfur layer, thereby making the surface hydrophilic.

Jan 1, 1994

By H. J. Handewith, W. D. Coski

This paper describes the development and testing of the RAMEX excavation system. Incorporating a synergy of low velocity, high energy impact and kerf cutting, this machine offers a competitive alternative to drilling and blasting in hard rock. It is a boom mining machine that incorporates the features of a lightweight roadheader and it can mine nearly any shape opening in hard rock. The RAMEX Tunneler has been developed to satisfy industry demands for a non-explosive, flexible, continuous and rapid underground rock excavation system. It will produce minimum ground vibration in the urban environment and allow the flexibility necessary for thin seam mining conditions. It will also reduce initial ground support costs and has a minimum impact on rock integrity. Developed by RAMEX Systems with cooperative research provided by the U.S. Bureau of Mines, this system, could produce the next step in the continuing evolution of mechanical mining systems.

Jan 1, 1989

Traditional finance theory recommends discounted cash flow (DCF) analysis as the tool to value mineral properties. Yet, the calculated values by this method are usually lower than the market value. Finance theory also advises us to develop an undeveloped project immediately if its net present value is positive. Most projects are, however, only developed when the economics are highly favorable. This paper uses insights from option-pricing theory to explain these divergences between market behavior and finance theory and presents simple modifications to discounted cash flow analyses that will lead them to produce correct valuation and development timing advice.

Jan 1, 1999

By L. J. E. Hofer, L. F. Zeiler, D. A. Giardino

The Jones Trickett Ratio (JTR) is generally used in investigations of fires and explosions for the determination of the composition of the fuel. This paper takes a close look at the JTR and finds it unreliable and ambiguous for the determination of fuel composition. A new index is presented, termed the (H/C) Index which uniquely determines the fuel composition. The (H/C) Index is simple to use requiring only the results of a single gas analysis of the combustion products. Experimental data testing the (H/C) Index for methane, propane, ethylene and coal dust are given, showing that the Index unambiguously determines the composition of the fuel. The (H/C) Index is also applied to the gas analysis data of several mine fires, illustrating how the Index changes with the progression of the mine fire.

Jan 1, 1993

By P. Somasundaran, A. Sivakumar

Surfactants and polymers are used in a number of processes such as flotation and flocculation. The structure of the adsorbed surfactant and polymer layers control the interfacial properties of the solid and hence an understanding of the structure of the adsorbed layers at the molecular level is essential. In this paper, a review of different spectroscopic techniques (fluorescence, electron spin resonance and Raman) used to characterize the adsorbed layers [in-situ] is presented. Information on the micropolarity, microfluidity and size of the surfactant aggregates was obtained and the growth of the adsorbed layer was followed. [In-situ] conformational states of polymers at the solid/liquid interface were determined for different pH values.

Jan 1, 1989

By Archie M. Richardson, Carl E. Brechtel, Tom R. Kelly, Frank Feero

Recent work to upgrade the ventilation system for the el Mochito lead/zinc mine in central Honduras is discussed. Network modeling and underground measurements were used to evaluate cost-effective alternatives for achieving satisfactory ventilation in a complex and expanding underground operation. Both interim and long-term solutions were implemented to make mining possible under difficult conditions. INTRODUCTION Mining operations at the el Mochito Mine, located in the central highlands of Honduras, Central America, have been virtually continuous since the opening of the mine in 1948. Initially a high-grade silver mine, the mine has expanded along a westward trend of pipe-like orebodies to a distance of roughly one mile from two centrally located shafts. Production of the relatively large San Juan orebody at the western most extension of the mine (Paddock, 1981) led to the introduction of diesel-powered equipment; however, the ventilation infrastructure was insufficient to meet the needs of mechanized mining. A succession of owners/operators in the 1980s allowed the existing ventilation infrastructure to decay to the point that ventilation in the production areas of the mine was very poor. Environmental conditions in some working areas were not conducive to efficient ore extraction because of high dry bulb temperature, high humidity, and diesel emissions. Upon acquiring the mine in 1990, Breakwater Resources of Tucson, Arizona began an aggressive program to refurbish the mine infrastructure to complete extraction of the San Juan orebody and to allow the extension of the mine another 2500 ft to the west for extraction of the Nacional orebody. The program included increasing the capacity of the main ventilation system. This article presents a case history of the process of upgrading the ventilation system in a mine where extensive old workings cause large air leakage. This process has been one of selecting solutions to difficult technical problems that are compatible with the existing mine infrastructure and economic constraints. The initial ventilation system is described in the background section, along with ventilation projections for the mine expansion. Field characterization of the ventilation system for design verification and fan specification is then discussed. The paper describes a series of interim changes to the system to improve ventilation pending completion of new ventilation boreholes. In addition, the temperature/ heat problems in the mine are described. BACKGROUND Initial Condition of Ventilation System The ventilation system is illustrated in Figure 1, which shows the extent of mining with the main ventilation paths superimposed. Early mining around the two shafts opened up vertical connections (stopes and raises) over the entire 2420 ft (737.6 m) of vertical extent, and mining progressed to the west primarily using compressed air and electric-powered equipment. Since ventilation was not a complex problem in the original mining system, the stopes and interconnecting raises were not sealed. The San Juan orebody was much larger than the silver ore zones mined previously, being primarily zinc and other base metals. Its geometry, size, and grade allowed the use of vertical crater retreat (VCR) stoping with diesel mucking and haulage equipment. Its depth, along with the existence of warm groundwater, resulted in a mine climate problem on the lower levels. To establish a complete ventilation circuit, two vertical boreholes (Bonanza Nos. 1 and 2) had been drilled by previous owners from the surface in the vicinity of the San Juan orebody. The system design called for air to be drawn down the intake shafts, across the lower mine levels to the San Juan workings, then up through the San Juan ramps and ore passes to these two exhaust boreholes (see Figure 1). In practice, however, only the Bonanza No. 1 borehole was drawing air through the desired path. Leakage across the old upper levels from the intake shafts, the Caliche tunnel, and from intervening abandoned stopes and raises supplied most of the air flowing to the base of the Bonanza No. 2 borehole. In effect, there were two ventilation circuits in semi-parallel through the mine, of which only one was delivering appreciable air to the San Juan workings.

Jan 1, 1993

By J. G. Wargo

Disseminated gold deposits are the object of major search and development efforts by many mining companies throughout the world. The invention of more advanced equipment for open pit mining and and use of heap leaching methods, taken together with favorable gold prices has led to rising profits in the gold mining industry.

Jan 1, 1988

By Richard R. Klimpel

This paper will summarize the trends resulting from the data generated in a large number of laboratory and industrial studies con- ducted by this author where various slurry rheology factors have been carefully changed and controlled. Factors such as percent sol- ids, addition and/or removal of fines, slurry mill filling level, specific material oriented breakage properties, chemical additions, etc. are discussed with a number of illustrating examples. This paper is specifically aimed at developing rheologically related operating guide- lines for plant engineers so that improved operating conditions can be selected.

Jan 1, 1997

By David M. Spatz

Team, as defined by Katzenbach and Smith (1993), is a small number of people with complementary skills who are committed to a common purpose, performance goals and approach for which they hold themselves mutually accountable. As the mining industry searches for new ore discoveries increasingly under post-mineral cover, the process of mineral exploration has taken us from prospector to geologist to multidisciplined explorer to multi-disciplinary team. Multidisciplinary exploration techniques have improved in terms of sensitivities and penetration and more than ever before each technique requires specialists with appropriate training and skills to process data and interpret results. To produce a quality product, specialists must collaborate openly and honestly in an atmosphere where the collective result takes into account the knowledge and expertise of each individual and the relationships between all pertinent data sets.

Jan 1, 1998

By R. S. Das, A. K. Sinha

Modern mine ventilation systems have grown rapidly in recent years both in terms of complexity and value for human health and safety. Although computer models are now available to help the design and operation of mine ventilation systems, considerable differences often exist between the computer-based predictions and practical results. Research conducted to compare computer results with practical measurements made in ventilation circuits simulated in a physical model seems to confirm such differences. It is concluded that although a mine ventilation computer model is a very powerful tool, it can be utilized to its full potential only if reliable input data are provided.

Jan 1, 1987

By D. W. Horsfall

The washability of South African coals is described and the problems encountered in washing at low densities, to make premium products, are enumerated. The measures taken to overcome those problems, when low density separations became a commercial necessity, are described in detail. The descriptions of processes are with specific reference to the three sizes commonly treated separately in coal preparation namely coarse coal, small coal, and fine coal. Some information is given on the performance characteristics of the plants erected to meet market requirements.

Jan 1, 1995

By J. F. T. Agapito, C. E. Brechtel, M. E. Adam

Full-scale stopping and simulated over- cast structures were constructed in large opening (30 ft high by 55 ft wide) room and pillar excavations in an oil shale mine. The program was undertaken to develop construction techniques and to generate data on structure costs and leakage rates. Leakage rates were measured using both sulfur hexafluoride tracer gas and "brattice window" methods at varying differential pressures. The measurements were conducted before and after a full-scale face blast to characterize the effects of blasting on leakage, and blast air pressures were measured across the stoppings. The operating performance of different combinations of permanent and temporary stoppings was evaluated by developing an operating model for a two-panel oil shale mine. The operating performance for the different stopping combinations was then compared to the system cost to evaluate the overall performance.

Jan 1, 1987

By Victor F. Hollister

This report summarizes data available on the Fort Knox gold deposit to the end of 1989. It is presented courtesy of Fairbanks Gold, operator of the Fort Knox mine. The ore body and the data base are being expanded in 1990, but this summary is pertinent for inclusion in a case history volume that, in part, stresses porphyry-type deposits. Fort Knox is a pluton-hosted gold deposit 22.5 km (14 miles) northeast of Fairbanks, AK. It is easily accessible from Fairbanks, and ultimately it will be the largest open pit gold mine in Alaska. The Fort Knox pluton has an interesting historical record, and it has been discovered at least twice. Fig. 1 shows the geology and location of major plutons in the Fairbanks mining district.

Jan 1, 1991