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By John O. Marsden

The project development metallurgist is faced with an interesting dilemma: The use of overly conservative metallurgical projections and cost estimates can kill a project that has the potential to provide needed jobs and growth to a company's bottom line. On the other hand if the metallurgist uses a highly aggressive approach by trimming capital and operating cost estimates to the bone and by applying highly optimistic metallurgical projections, there is a risk of creating a project that can never live up to expectations. The metallurgist must walk a tightrope between "sandbagging" and "overoptimism," and this tightrope is fraught with political intrigue and difficulty. This paper takes a some- what lighthearted look at some of the political aspects associated with this issue, and other issues, and offers a few guidelines for walking the "political metallurgical" tightrope.

Jan 1, 2001

By H. L. Ehrlich

Modes of microbial attack of metal carbonates, metal silicates, metal oxides and metal sulfides are summarized. The current status of microbial redox mechanisms, whereby metals in metal oxides and sulfides are mobilized, is discussed. Opposing theories of a single mode of attack involving interaction with a microbially produced reductant or oxidant in the bulk phase and of dual modes of attack involving a reaction requiring physical contact between microbe and mineral surface on the one hand and microbial production of a reductant or oxidant in the bulk phase that reacts with the mineral on the other hand are considered. No one mode when finally completely unraveled should be expected to fit all cases. Some biochemical, electronmicroscopic and spectrophotometric approaches for elucidation of missing details of different modes are suggested. Key words: Bioleaching, Biobeneficiation, Metal mobilization

Jan 1, 2003

By Syd S. Peng

The key design parameters of roof bolting using expansion - shell type support for underground coal mine roof support are bolt length, bolt spacing, installed load and anchorage capacity. Depending on the utilization of suspension effect or friction effect, the bolt length is dictated either by the distance between the roof surface and the first overlying strong strata encountered or the desired magnitude of reduction in bending stress at the roof surface, The current prevailing practices about the bolt spacing and installed load are that an initial torque of 125 - 170 ft-lbs is applied and the bolts are spaced at 4- or 5- ft. square grid pattern. This seems to be a rather broad generalization in view of the great geological variances which are expected in underground coal mines. A modest evaluation program to measure the effectiveness of current roof bolting practices is to monitor the load history of roof bolts during a complete mining cycle including the phases of room development and pillar robbing. The load history, when compared with the anchorage capacity of roof bolts determined by in-situ pull tests, will provide information for evaluating the installed load, the bolt spacing as well as the specifications for structural and anchorage characteristics of the bolt assemblies. This paper presents a case history of monitoring the complete load histories of roof bolts in an underground coal mine of Pittsburgh seam.

Jan 1, 1976

By C. L. Jiang

The selective depression of pyrite obtained from Kentucky No.9 seam in coal flotation with various kinds of inorganic and organic chemicals was systematically examined. Most of the organic chemicals tested showed little selectivity in pyrite depression. It was found that both orthophosphate and pyrophosphate were effective for the selective depression of coal pyrite in coal flotation using fuel oil as a collector. At substantially low concentrations of pyrophosphate, the flotation of coal pyrite was completely depressed over a wide pH range, while the coal flotation remained unaffected. The mechanism of the selective depression of pyrite by phosphates has been explained with the help of thermodynamic calculations of iron-phosphate-water systems and zeta potential measurements. It was shown that pyrophosphate reacts strongly with iron ions of pyrite to form stable hydrophilic iron pyrophosphate complexes on pyrite surfaces.

Jan 1, 1998

By Roger B. Jr. Herbert

Surface water samples were collected from water accumulations at the surface of a neutral pH mine tailings deposit in Kristineberg (Sweden) where algal growth and iron hydroxide precipitates were observed. Ferric iron in the aqueous samples was determined by (adsorptive) differential pulse - cathodic stripping voltammetry. The analyses indicated that labile Fe3+ concentrations were in the range <20 to 337 nM, while total Fe3+ levels were much higher at 0.9 to 8.3 uM. The labile Fe3+ levels are more than two orders of magnitude greater than would be expected based on equilibrium with ferrihydrite. These results suggest that iron complexation with strong ligands in the surface water competes with iron hydrolysis, and that these ligands may be of algal and/or bacterial origin.

Jan 1, 2000

In the estimation of recoverable resources, geostatistical techniques such as Multiple Indicator Kriging require a change of support correction to derive theoretical recoveries based on an assumed level of mining selectivity. The change of support models most widely used in practice entail model based generalized corrections either on a global or local basis. Examples include the affine and indirect lognormal methods. Change of support corrections derived empirically through short-scale conditional simulation realizations often show notable differences compared with theoretical corrections determined using model variogram parameters. The existing changes of support models are reviewed and an alternative method is proposed.

Jan 1, 1999

By J. A. Siekmeier

The thickness of the laminated beam modeled in this study is based on bridging potential and TDR measurements. The laminated beam stiffness is based on the effective stiffness of an equivalent transformed section. The maximum deflection of this near-surface laminated beam is compared with the maximum measured surface subsidence. The spreadsheet provides a rational technique to graphically display the character of the overburden and potentially allows prediction of a subsidence factor based on boring logs and the proposed mine plan. The U.S. Department of the Interior, Bureau of Mines (Bureau), utilizes a commercially available computer spreadsheet program in combination with a modified version of Bieniawski&apos;s Rock Mass Rating (RMR) system to characterize the geology overlying high extraction coal mines. The spreadsheet program calculates a RMR for each bed based on the lithology, thickness, and engineering properties, which are determined from boring logs and laboratory tests. Once the RMR is calculated the spreadsheet has two major functions. First, the spreadsheet calculates values used to graphically represent the character of each individual bed in the overburden. It calculates an in situ deformation modulus using an empirical rela¬tionship between the modulus and the RMR and then uses this effective modulus along with additional parameters that are based on mine geometry to calculate the bending stiffness and bridging potential for each bed. Second, the spreadsheet creates a transformed section that allows groups of beds to be modeled as an elastic beam. It then calculates a bridging potential for the entire rock mass. The bridging potential of the rock mass is a single value that takes into account both the geology of the overburden and the geometry of the mine. It seems reasonable that there would be a strong correlation between the bridging potential, the overburden response to high extraction mining, and the subsidence ratio. The results presented in this paper focus on the relationship between the bridging potential of individual beds and the deformation measured using Time Domain Reflectometry (TOR). Subsurface displacements measured over seven high extraction coal mines in southern Illinois were correlated with the bed stiffness and bridging potential profiles. Based on these correlations it was evident that the process of caving and subsidence over these high extraction mines involved momentary bridging by individual beds or groups of beds and the ultimate development of a laminated beam near the surface.

Jan 1, 1986

By James E. Kolesar

An essential prerequisite to expanding the application of longwall mining techniques in the United States is the development of a better understanding of the mechanics of rock mass deformation near the mined seam, in the inter- burden and at the surface. The results of studies of this type will provide a basis for the development of empirical and/or numerical modeling techniques to predict the rock mass response to mining both near and far from the mined seam. This will lead to improved gate and panel design, resulting in maximum recovery, increased productivity, as well as provide a mechanism for assessing likely surface effects induced by long- wall mining. Presented here is the instrument plan to be used at Kitt Mine No. 1 in the study of rock mass response to two adjacent longwall panels.

Jan 1, 1982

By W. E. Heinrichs, R. W. Davis

Introduction Cross borehole seismic tomography (CBST) is a geophysical technique that allows definition of the distribution of some physical rock property between two boreholes. The method is similar to the computer-assisted tomography (CAT) scans used by the medical industry. This paper describes the method, its applications and the developing trends in its use that interest the mining industry. The idea of using tomography in connection with geophysical methods for measuring rock properties between boreholes has been around for three or four decades. Until the advent of high-speed, large-capacity computers, the necessary calculations were too formidable for production use. Another factor in the development of the technique has been the refinement of a mathematical base to meet the needs of the medical industry. The geophysical applications have benefited from this refinement. An extensive discussion of the basic theory is given in Kak and Slaney (1988). CBST, although widely researched and written about, is still not extensively put to use in mining and engineering projects. Most real world examples in the literature have come from research carried out by government laboratories or by large companies. An exception is the regular use by Prospection Geophysique Francaise (Cottin et al., 1986) in damsite investigations. The Japanese appear to be doing extensive research and testing of CBST&apos;s uses in civil engineering projects (Saito et al., 1988). Canada is researching the use of the method in connection with nuclear waste site investigations (Wong et al., 1987). Finland has tested the method in connection with a foundation investigation for a nuclear power plant (Cosma et al., 1984). In the US, the US Bureau of Mines has taken an interest in using CBST as a means to enhance in situ mining operations (Tweeton, 1988). Major oil companies are examining the method as a tool in oil field development (Justice et al., 1989). Description of the method CBST involves placing a series of receivers down one borehole and recording transmissions from an energy source placed successively at a series of positions in another hole. The objective is to generate a dense network of seismic raypaths between the holes. The denser the network of raypaths, the better the features between the boreholes are resolved. Either seismic travel times or sine wave amplitudes are measured by the receivers. Analysis of travel times between boreholes develops a picture of rock velocities between the holes. Analysis of seismic wave amplitudes develops a picture of the distribution of energy transmission characteristics between the holes. These seismic properties can be used to define occurrences of fracture zones, lenticular sequences or other important geologic data not apparent from examination of the borehole logs. When longitudinal (compressional) and transverse (shear) waves are analyzed, the physical properties, such as elastic moduli, can also be mapped. When wave amplitudes are measured, rather extensive corrections to the data are necessary. There is some disagreement among researchers as to the feasibility of making some of the corrections. For this reason, this paper will concentrate primarily on travel time analysis. Wave amplitude analysis will be mentioned occasionally only in passing. This does not mean that amplitude analysis does not provide important data on rock parameters, only that for the present there are limitations on its uses. Vertical seismic profiling (VSP), extensively used in recent years in oil exploration, is similar to CBST. Instead of using two boreholes, however, the VSP method uses an array of seismic sources or detectors down one hole and an array of detectors or sources along the surface radiating outward from the hole. While adequate for determining vertical velocity distributions, the VSP method is not, by itself, suitable for most engineering or mining projects. Computer programs used to analyze the field data make use of the fact that the total travel time or change in signal amplitude between boreholes is described by Dines and Lytle (1979) as: [9k = f Rk f( x,Y) ds (1)] where gk = the total time or attenuation along the kth ray path,

Jan 1, 1992

By K. W. Vincent

This paper, deals with the beneficiation of a low grade Western phosphate to ore. More specifically it summarizes the results of a study made to optimize a scrubbing step in the process, and to provide firmer data for use in plant design. The deposit is situated about 30 miles northeast of Pocatello, Idaho, in the Fort Hall Indian Reservation. It is a bedded deposit and throughout most o the orebody includes three contiguous layers of phosphatic material which differ in P205 content. The J. R. Simplot Company, as operator for a Simplot-FMC joint venture, mines the ore selectively by open pit methods The lower bed containing a nominal 30% P205 is shipped to the Simplot Company fertilizer complex near Pocatello; the middle layer averaging about 24% P205 supplies the FMC elemental phosphorus plant also near Pocatello, The top layer averaging around 16% P205 and designated as mill grade shale is stockpiled for future beneficiation. This paper is concerned with some aspects of the processing of this low grade shale.

Jan 1, 1965

By William M. Greenslade

As the search for minerals leads to deeper mines the need to control water inflow into mine shafts and mine workings will grow. As shal¬lower more readily available minerals are exploited, ore bodies which were previously uneconomic be cause of their depth will now become attractive targets. In known mining districts new ore bodies are being discovered down dip of existing ones. In the west many metal deposits are being developed in rocks of the mountain front pediments, frequently covered by several hundred feet of saturated alluvium. Greater depth often means that workings are developed well below existing water tables, creating high hydrostatic heads adjacent to mine workings. The purpose of this paper is to review some of the methods available for determining if water control will be necessary and to present some of the techniques for locating water bearing zones and the amount of water to be expected. The paper will concentrate on problems associated with water control in mine shaft development, although many of the exploratory techniques are similar to those needed for assessing overall mine water inflow problems. A brief case history on water control problems in mine shafts in the Grants mineral belt of northwestern New Mexico is presented. Water control during shaft sinking presents some unique features. First, the problem is a relatively short term one, since water control is often necessary only while the shaft is being sunk. Control measures may be necessary only while the shaft is open into the water bearing zone and the lining installed and cemented. Secondly, limited working space within the shaft area presents difficulties in handling large amounts of water inflow. The presence of water in the shaft working area increases sinking time and the potential hazard to miners. Finally, there is the economics of shaft sinking. While the shaft is being sunk no ore is being produced and there is every incentive to minimize costs.

Jan 1, 1979

By M. Z. Rashad

The purpose of this work is to determine the influence of sample length or size on the value of variance (Semi-variogram) to select the suitable length that is required to the geostatistical computations of ore evaluation. Three cases in Ghorabi Iron Ore were studied. The first one was on the iron fraction (Fe\) at which the semi-variogram gave an evidence to good continuity of the fraction in the ore. In this case, the length of sample has not important influence. The second case was for the Mn\ component of the same area where the semi-variogram has a nugget effect. The selected length for this case was 4 meters. The Cl fraction of the ore was the third case where the anisotropic phenomena was appeared and the suitable length is 3 meters.

Jan 1, 1992

By Lauren W. Choate

Wollastonite, a calcium metasilicate, derives its name from the man who discovered the mineral, Doctor William H. Wollaston, an English scientist. OCCURENCE Occurences of the mineral have been noted in Finland, Switzerland, Russia, Japan, Mexico and in the United States in Texas, California, Arizona, and New York. The only commercial deposit now being exploited is at Willsboro, New York. It is mined and processed by the Cabot Corporation whose home offices are in Boston, Massachusetts.

Jan 1, 1964

By F. Milton Lewis

In 1977 a paper was presented which reviewed the cost trends in producing copper by conventional processes for five years, 1972 through 1976. In this paper these costs have been updated to include the years 1977 and 1978.

Jan 1, 1979

By Edward F. Nagle

Instrumentation engineers have recently devised practical methods of metering the net solids flowing in a hydraulic mixture. The solids flow rate is determined by measuring the specific gravity and the flow rate of the mixture. T e specific gravity is measured by a variation of the bubbler system. The flow measurement is made by a somewhat unorthodox orifice requiring field calibrations. The linear mixture flow signal is then multiplied by the specific gravity signal, which is directly proportional to the percentage of solids in the mixture, to produce a linear solids Slow rate signal. The computations in this system are performed by Sorteberg pneumatic relays. Having obtained this measurement, integration and automatic control of hydraulic solids flow are available. This system is useful in mining, drilling and dredging industries. It provides maintenance of the net solids flow rate and reduces power consumption. Automatic control will provide rapid stabilization of net solids flow rate and release operators from making menual adjustments. The advantages of this application are economy of operation and increased pump efficiency, This paper describes a hydraulic solids flowmeter system installed aboard a dredge. Its purpose is twofolds:- 1. 20 provide a summation of the net solids flowing 2. To make available a practical guide for the drag tender operator. (Dwg. GSD-2219)

Jan 1, 1958

By G. R. Burman

Gilsonite is a brittle, natural solid bituminous resin, classified as an asphaltite. It is found in near-vertical veins in the Uintah Basin of Eastern Utah. Discovered well over 100 years ago by Samuel Gilson, this unique material has, since its finding, enjoyed a variety of commercial and industrial applications. Early uses for the product included black automotive paint and beer vat linings. Among its many important uses today are additives for oil well drilling fluids and cements, additives for sand castings for the foundry industry, reinforcing agent for asphalt pavements, and dispersing agent for black inks. Gilsonite is mined and processed in Bonanza, Utah, by two companies, American Gilsonite Company (AGC), an operating division of Chevron Resources, and Ziegler Chemical, a privately held company headquartered in New York.

Jan 1, 1990

By C. B. Manula

The application of computers to materials handling problems has recently been investigated by various mining groups. This approach has been found, especially useful where a large amount of alternatives must be investigated prior to arriving at a final decision. These alternatives may be expressed in terms of man hours, units and types of equipment such as trucks or conveyors, or the allocation and operation of proposed or existing haulage facilities. The decision problem becomes especially evident when we consider the mechanical revolution which has flooded the mining industry in recent years. The industry has become highly competitive, with the need to keep low profit materials away from high cost production faces ever increasing. The capital investment required for the highly sophisticated equipment that is necessary to perform this function is generally great, and management is faced with decisions which must all too often be made without sufficient data.

Jan 1, 1967

By Roger Bell

Most modern mines can profit from improvements in information handling. Recording systems in many cases were designed to satisfy certain necessary legal requirements, but not specifically to provide management information. As a consequence, the top managements of these properties work with cost data and production information that is dated, lacking in detail and clouded with supposition. It is the intent of this paper to describe an information system for a mine-plant complex in terms of the type of data, application areas and the existing equipment technology that may be applied to improve this situation. The economics of information processing and data handling will not be discussed in detail. This paper is based on the premise that information is something of value and that information processing like a manufacturing operation works for and is subject to management control. Information, the product, must be of quality, and the cost must be favorable in terms of its use.

Jan 1, 1965

By John B. Patton

No academic program of reasonable duration can provide a geologist with all the skills that may be needed for applied work in industrial minerals, but any curriculum that does not provide background in such basic subdisciplines as mineralogy-petrology, stratigraphy, sedimentology, structure, and geomorphology will leave the practitioner handicapped. Enough geochemistry to understand materials requirements, and sufficient geophysics to utilize geophysical data, are essential. In addition to purely scientific considerations, the industrial minerals geologist must be able to evaluate economic factors and may be faced with legal, social, and political problems in land use, zoning, environmental protection, and reclamation.

Jan 1, 1981

By Robert M. Becker

The evaluation of in situ rock stresses from measurements of the change in diameter of a borehole that is stress-relieved by overcoring has become a common practice. Generally the stress evaluation has been based on isotropic relations whereas rock in varying degrees is anisotropic. A plane elasticity solution for a circular hole along one axis of an orthotropic medium has been adapted to evaluation of in situ stress. The necessary elastic parameters for this evaluation may conveniently be obtained from static tests on the overcore in conjunction with a consistent orthotropic thick-wall cylinder solution. The method and equations for the laboratory and field evaluations are summarized and illustrated.

Jan 1, 1968