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By U. F. Beichmann

INTRODUCTION The City of Oslo together with the neighbor municipalities, Baerum and Asker, are presently building a jointly owned sewage treatment plant located on the west side of the inner Oslofjord. The project is scheduled for completion late 1981. Because the location of the treatment plant is at a distance of about 20 miles (30 km) from the city center, a discharge of more than 13 yds 3/sec (10 m3/sec.) of sewage and storm water will have to be transported over considerable distances. The topography of the area and the geological conditions early indicated that the only realistic transport method had to be through tunnels. As planning proceeded, full face tunnel boring emerged more and more as a favorable alternative to conventional drill and blast medhods. Today the scheme comprises nearly 25 miles (40 km) of tunnels being excavated by full face tunnel borers. In addition a number of access tunnels and cross cuts are to be excavated by conventional methods.

Jan 1, 1979

By D. A. Newman

A longwall chain pillar is comprised of two distinct zones, a solid elastic core enclosed by an exterior of failed or yielded coal. For the purpose of pillar design, the ability to delineate the extent of pillar yielding and correlate the yielding with the applied pillar load is of fundamental importance. A study was initiated on a longwall section of a West Virginia mine to: (1) delineate the location of the elastic core-yield zone boundary, (2) examine the stress distribution within the pillar, and (3) quantify pillar stability as the longwall face retreated toward an instrumented pillar. A US Bureau of Mines sonic velocity probe was used in conjunction with vibrating wire stress meters to define the elastic core-yield zone boundary and the migration of vertical stress toward the pillar core. The extent of the yield zone as determined by field results is compared with the extent of the failed zone as predicted using a series of equations developed by Wilson.

Jan 1, 1988

By K. N. Han, Q. Xu

The adsorption behavior of gold in ammoniacal solutions on activated carbon was studied. The gold adsorption capacity of the activated carbon and the recovery efficiency were examined. The parameters affecting the adsorption of gold on the activated carbon included temperature, agitation speed, the concentration of cation and anion and the concentration of ammonia. It was found that the maximum gold adsorption was about 10 kg/t of carbon. The recovery of gold by the adsorption, from ammoniacal solutions was found to be dependent upon the initial gold concentration. Under experimental conditions, a gold recovery of 98% was obtained after 120 hrs of adsorption. It was also found that the initial adsorption rate was relatively fast, when compared to the entire adsorption period. The apparent activation energy for the adsorption was determined to be 15.8 kJ/mol. It was believed that the kinetics of gold adsorption on the activated carbon was controlled by pore diffusion.

Jan 1, 1997

By Charles T. Staniek

Following a dragline relocation at Agrico's Fort Green phosphate mine in 1986, the recovery plant experienced a significant decrease in flotation performance. Through weeks of trial and error testing, we discovered we could restore recoveries by conditioning feed at pH's higher than we had used historically. The higher pH's essentially increased flotation cell kinetics, although we still do not understand the exact mechanism at work. Armed with new-found appreciation of pH modification, we initiated a program to determine the optimum modifier for us, from both a performance and environmental perspective. Environmental considerations were important because ammonia, the standard industry modifier, is a plant nutrient and higher usage rates could affect the quality, of our recycle process water. This paper describes the research and development work spanning a 3 year period that culminated in making a major change in our reagent suite when we replaced ammonia with soda ash on a permanent full-time basis.

Jan 1, 1993

Information Technology has addressed those problems unique to senior management in the mineral industry. In general, these problems are those concerned with decision-making. Peter Drucker in his discussion of making effective decisions identifies five phases: (1) define the problem, (2) analyze the problem, (3) develop alternate solutions, (4) decide the best solution, and (5) convert the decision into effective action. The scope of the chapter by Guernsey addresses the first three phases which provide input to the decision-maker. The decisions to be made relate, in most instances, to the economics related to a mineral property or process. Computer models have been designed to generate these economic and financial evaluations. No one model is appropriate to the solution of all management's problems. In this chapter several applications are identified and summarized; a model for the economic evaluation of a mineral property is described in greater detail. The implementation of such models is dependent on the unique needs of management.

Jan 1, 1979

By H. Sis, S. Chander

The beneficial effect of a series nonylphenol polyethylene glycol ether surfactants were tested in the flotation of phosphate ores in which the mixture of sodium oleate and dodecane was used as collector. The performance of nonionic surfactants was first tested in the microflotation of pure apatite mineral. Microflotation experiments showed that the recovery of apatite depends on the number of ethoxylation of the nonylphenol surfactants and decreased with higher ethoxylation. The nonionic surfactant with the smallest ethoxylation group used in this research (NP-4) was then tested in batch flotation of phosphate ores. The flotation of three different size phosphate ores was carried out in the absence and presence of NP-4 surfactant. The beneficial effect of nonionic surfactant was obtained for fine size (-35+150 mesh) and very fine size (-150+400 mesh) phosphate ores at different collector dosages studied. But, in the flotation of coarse size (-16+ 35 mesh) phosphate ore the beneficial effect of nonionic surfactant was obtained only at high collector dosages.

Jan 1, 2002

By Thomas Van Riper

Newmont Mining Corporation started as one man's investment vehicle. William Boyce Thompson, Newmont's founder, was already a millionaire many times when he incorporated his existing Newmont company in Delaware in 1921. The initial stake in the company was $8 million in capital contributed by Thompson and several close associates. In its infancy the company was truly a holding company. It did not operate or manage any properties. This situation changed drastically over time. By 1939 Newmont was actively mining 12 gold mines in North America. The following year, the first copper mine that Newmont ever managed directly, came into full production in South Africa. The period after World War I1 was a glorious one for Newmont. Plato Malozemoff took the helm of the company, and expanded its operations over the next 30 years into copper in Arizona, oil and gas in the U.S. and the North Sea, into domestic coal and thankfully, into significant gold operations.

Jan 1, 1989

By Mark J. Schultz, William J. Francart, Gary J. Wirth

Atmospheric Monitoring Systems (AMS) utilizing carbon monoxide sensors have demonstrated their superiority over thermal type fire sensors for early fire detection in underground coal mines. After proving their capability and dependability throughout the 1980's, systems are now evolving and applying new technologies to enhance their effectiveness and reliability. The use of AMS in coal mines which utilize diesel equipment presents unique obstacles. Exhaust gases from diesel equipment not only raise mine ambient CO readings, but also cause numerous nuisance alarms. Both of these conditions reduce the effectiveness of the AMS. New technologies, such as discriminating devices, smoke detectors, and time delays, as well as administrative controls, have been developed and are being utilized to help reduce nuisance alarms produced by the diesel exhaust. This paper will discuss these technologies and administrative controls which are being utilized in coal mines to enhance the effectiveness of the Atmospheric Monitoring Systems. Reference to specific products does not imply endorsement by the Mine Safety and Health Administration.

Jan 1, 1995

By J. Partyka, Trevor R. J. Kelly

This paper presents the results on noise testing of a fan only, as well as the results of a steel silencer and of flexible silencers that were connected directly to a fan. On-site facilities and free-field method set by the British Standards Institution were used to measure and then compare the fan only and different practical silencer configuration setups. In order to determine the fan-silencer combination that would give the maximum noise attenuation, total noise intensity, noise contributed to by the fan motor only, as well as aerodynamical noise created through air interacting with the fan parts were considered to obtain decibel readings for the octave bands. Subsequently, the optimal configuration found was the setup with flexible silencers on the fan inlet and the fan outlet. If only one silencer is used, it should be installed on the fan inlet. The aerodynamic noise affects the low frequencies. The flow noise is then overtaken at 1 kHz by the mechanical noise.

Jan 1, 1995

By J. Hanna, R. Kalathur

Over the years, Alabama's coal industry has generated, during mining and cleaning operations, about 150 million st of fine waste coal, with this total increasing at a rate of 2 million stpy. Reclamation of the fine-size wastes (containing 20% - 60% clean coal by weight) provides, free of charge, mined and crushed feed stocks for coal recovery. Also, the removal or recovery of pyrite from the tailings should eliminate a major source of acid-water pollution. Tests were made on the impounded wastes and current plant discharges to recover the coal fraction by sizing, gravity and flotation techniques. Gravity separation of the +100-mesh material produced commercial-grade coal averaging 7.6% ash, 0.8% sulfur and 13,471 Btu/lb. However, the coal yield, at about 31 % - 56%, was relatively low. Froth flotation, using mechanical and froth column methods, gave similar coal products at much higher coal recovery rates of 87% - 93%. This coal analyzed 10% ash and 1.1% sulfur.

Jan 1, 1993

By H. Zhu, A. G. Journel

Qualitative and interpretive information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging, and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system provides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data. A case study using a large reference database is presented; the indicator conditioned estimates have a smaller conditional bias and a smaller error variance than the ordinary kriging estimates. The results also showed that the indicator conditioned estimator is more efficient for selection in mining.

Jan 1, 1990

By Eddy J. Jacques

When the automatic control of a ventilation process is considered, and supervising expert systems need to be designed, an important problem to address is: what will be the optimal set points of the regulators that should meet a certain number of independently formulated requirements, distributed over a ventilation network? The set of these requirements, expressed in terms of air flow quantities or differential pressures in certain airways, need not be consistent. Their number is not limited by the number of available regulators, nor by their nature, i.e. passive or active. Moreover, they may be subject to upper or lower limit values. The method described here addresses this problem and tries to provide a tool that should allow to calculate the set points of all the regulators as a global and optimal solution with respect to this set of distributed requirements. The pure mathematical developments in this paper are kept as short as possible in order to allow more room for the description of a relevant example.

Jan 1, 1991

By J. A. Herbst, T. I. Martinovic, Y. C. Lo

This study was concerned with the application of a computer simulation methodology to optimize the performance of mills grinding iron ore concentrate prior to pelletizing. The methodology involves batch and plant testing, modeling and computer simulation. The analysis of grinding performance was carried out and capacity increases were predicted in the context of detailed population balance models developed for the plant ball mills. Model developnent and plant confirmation were performed using data obtained in a series of batch tests and three plant tests. From experimental data and computer simulation it was found that ball size, percent solids and classification all had a significant effect on mill throughput. Based on the findings of this study, a 12-152 increase in capacity was predicted to be available by a proper combination of ball size charge and optimum percent solids. These predictions have been confirmed by plant tests in which the recommended operating changes have been made.

Jan 1, 1990

By Alden B. Carpenter

The Dead Sea is the only relatively large body of surface water having bromide concentrations comparable to those in the brines of the Smackover Formation in Arkansas. The Dead Sea, like the Smackover brines, contains a great deal of calcium and is very low in sulfate and iodide. The relationships between potassium, divalent cations, and chloride indicate that over 20 percent of the bromide in the Dead Sea is derived from some source other than by the evaporation of sea water. A similar type of study of the Smackover brines in Arkansas indicates that approximately 60 percent of the bromide has been derived from some source other than sea water. Both the Dead Sea and Smackover brines are very low in iodide suggesting that the excess bromide has not been derived from organic matter. The origin of the excess bromide is probably the same for both of these brines, but the source of this bromide remains unknown.

Jan 1, 1978

By Bruce Johnson

This paper is not written to "break new ground" in computer applications; it is just a treatment of how an operating metal mine utilizes a mainframe computer for planning, analyzing, and reporting on the ventilation and cooling systems. The Unisys mainframe computer at the mine site is used in programs that analyze the ventilation network, keep records on various ventilation installations, calculate the results of measurements and produce reports on ventilation conditions in the working places and on the main air distribution, and plan and analyze the cooling system. All the programs are interactive to terminals. There are a series of data files that are generated by some programs which may be used by other programs. Most of these programs have been developed in-house. The computer is also used as a word processor via a vendor-supplied text editing program to produce memos, letters, and to keep up-to-date lists of equipment used.

Jan 1, 1989

By S. Shrivastava, R. G. Reddy

Spent potliner is generated in the electrolytic process of reducing alumina to make aluminum metal using molten fluoride electrolytes. Spent potliner(SPL) is obtained at the end of the pot's life. The SPL contains small amounts of cyanide and fluoride, which present environmental problems. Spent potliner could possibly be used as a fluidizer to replace calcium fluoride (CaF2) in the iron- and steelmaking industry and in the glass industry. A low viscosity and a low melting point are prime requirements for such an application. In the present study, viscosity measurements were performed. The effects of various additives, such as sand, limestone, dicalcium silicate dust and MgO baghouse dust, on the viscosity of SPL were studied. The results showed that the addition of sand and limestone can produce a very high fluidity SPL melt at significantly lower temperatures. The results suggest that spent potliner mixed with additives could potentially be used as a substitute fluidizer.

Jan 1, 2002

By W. K. Utt, C. C. Woodward, W. L. Howie, G. G. Miller

The process of roof drilling and bolting is one of the most dangerous jobs in underground mining. In the United States, roof drilling and bolting results in about 1,000 accidents with injuries each year. Researchers, from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are studying the feasibility of using a drill-monitoring system to estimate the strength of successive layers of rock and assess the integrity of a mine roof. Such a system would allow roof drill operators to be warned when a weak layer is being drilled. Using measurements taken during drilling, a neural network can classify mine roof strata in terms of relative strength. The concept has been proven in principle. This research project was undertaken to increase the safety of underground miners, especially those involved in roof bolting. The system should be applicable to the mobile drills now used in underground mines, and the system would likely find wider application as well.

Jan 1, 2003

By Eli Curiel, Ingar F. Walder, Patrizia P. Schuster, Walt Keyes

Mansfield Canyon, of the Wrightson Mining District, Santa Cruz County, Coronado National Forest, Arizona, was actively mined in the late 1800's and early 19001s, with minor activity until 1953. The main products were lead, silver, copper, zinc, and gold occurring in polymetallic quartz veins. The canyon contains numerous adits and waste dumps, some of which generate metal-loaded acid. Samples of seeps, waste dumps and bedrock have been collected for various analyses: metal concentrations, acid base accounting (ABA), and water quality to evaluate the extent of oxidation and metal release from the start of mining until present, the potential impact, and reclamation options. Although the waste-rock piles within the canyon are small (2,000-10,000 tons), they have a high sulfide content with little or no neutralizing capacity. It is planned, therefore, to move the waste piles either to a constructed repository site within the canyon or to a copper leach facility to be used as an acid generator.

Jan 1, 2000

By Robert A. Haney

Utilizing the recently developed laser velocimeter and a Pitot-static tube, the United States National Bureau of Standards (NBS), has calibrated various types of anemometers that are commonly used in the mining industry. This paper presents a summary of the performance characteristics including accuracy, precision, starting and stopping speeds of each instrument tested. The specific instruments that were calibrated by NBS have become Mine Safety and Health Administration (MSHA) primary reference instruments. These primary reference instruments are used in turn to calibrate secondary reference instruments for each Coal Mine Safety and Health District. Each District calibrates anemometers that are used by District engineers and inspectors. Calibration is accomplished through a substitution procedure in which the reading on the anemometer is compared to the true velocity determined by the reference instrument. Calibration is performed over the entire range of the instrument using an open jet wind tunnel to produce the various approximate velocities. Some specific details of the calibration procedure are presented in this paper.

Jan 1, 1980

By J. G. Henning, R. Edrissi

This paper describes a practical methodology, based on numerical modeling, for the prediction of progressive failure of underground-mine stopes having cable-bolt support. A case study of the 40-761 scope at the Kidd Creek mine, Timmins, Ontario, Canada is presented. Scope 40-761 was mined by blast hole open sloping in 1986 and was a lead scope within a mining block located between levels 36-1 and 38-2. Initially designed to peak at level 38-2, the scope back caved upwards =40 m towards level 36-1. After caving began, cable bolts were installed above the stope from level 36-1. The stope eventually stopped caving when the falling rock mass encountered a sufficiently high cable density. This paper provides details of the geomechanical data and modeling results of the case study. Numerical modeling of cable bolts around the mine stoke was carried out using a finite-element modeling software. The software, known as e-z tools, was developed by the first author.

Jan 1, 1996