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By David A. Benjamin

The USBM (U.S. Bureau of Mines) studied mines, prospects, and mineralized sites in the Roberts WSA (Wilderness Study Area) in 1984. The 15,090-acre WSA, located 35 miles northwest of Eureka, NV, is underlain by alluvial deposits of Quaternary age, extrusive and intrusive volcanic rocks of Oligocene through Miocene age, and metasedimentary rocks of Cambrian through Permian age. The Roberts Mountain Thrust fault cuts through the WSA, dividing the metasedimentary rocks into upper and lower plate rock units. One mine, the Kelley, which produced 397 tons of lead-zinc ore prior to 1940, and two prospects are within the WSA; no resources were identified. Exploration for precious metal deposits is presently being conducted in and adjacent to the WSA on large claim blocks. The study area contains six sites in and near these claim blocks that have anomalous gold and silver. Detailed exploration is needed to delineate resources. High purity silica rocks are present in the WSA. Barite, phosphate, oil shale, and vanadium occurrences just outside the WSA may extend into it, but no such occurrences were observed during the USBM study.

Jan 1, 1986

By J. W. Smith, J. G. Eacott, D. H. Napier

"Three hydrometallurgicat processes (Noranda chloride leach, B. C. Research biological leach and Sherritt-Cominco activated oxygen leach) and the Noranda pyrometallurgical process have served as the basis for design projects in the final year of the chemical engineering program at the University of Toronto. Each member of a team of five or six students devotes about 200 hours to the project and the final report is expected to include an economic analysis.None of the processes has been developed to full- scale plant, nor, in the case of the B.C. Research and Noranda processes, were pilot plant data available. Nevertheless, the designs developed provide a useful basis for a preliminary estimate of capital and operating costs and for a preliminary assessment of project feasibility.This paper discusses the approach used in the design projects with respect to engineering and economic aspects, and outlines the educational features and benefits of such a program as well as some of the problem areas that arise.IntroductionAs part of the undergraduate degree course in chemical engineering at the University of Toronto, students devote some 200 hours to a design project in their final year. Hydrometallurgical processes, not yet proven at the commercial scale, have been selected for study. The students are required to develop laboratory and / or pilot scale results into a conceptual plant design, using sound engineering principles. Capital and operating costs are then determined and a preliminary feasibility study and economic analysis are carried out."

Jan 1, 1986

By D. Z. Mraz, R. S. Jones

Unlike in coal mines where caving methods are used, the subsidence over potash mines in Saskatchewan, Canada, is a function of gradual mining convergence. Because of the presence of high pressure water aquifers over the evaporite salt formations, the mines have to be designed as regionally stable and no caving is allowed. The extracted area converges gradually and the convergence is mainly a function of the extraction and the mining method employed. Consequently, the subsidence rate is very slow and the bridging of the over-lying strata is a considerably more important phenomenon than elsewhere. The paper evaluates a case history of convergence and subsidence in a deep potash mine in Saskatchewan.

Jan 1, 1986

Recent research publications in extractive metallurgy were analysed for their stated and self-evident objectives. Over 100 different objectives (not specific to a metal or unit operation) were identified. These were divided into groups of economic, environmental, professional and fundamental significance. Comparisons were made of the objectives adopted in universities, industry and national research organisations. The most common primary and secondary objectives (by a large margin) were "to develop a new process (different chemistry)" and "to determine the effects of variables on a process" respectively. It was concluded that, overall, recent research has been dominated by commercial objectives. Objectives related to thermodynamics and kinetics have been the most common of the fundamental sort. Those related to professional methods in general, sensors and process dynamics, among others, have been largely neglected.

Jan 1, 1986

By Christopher J. Bise

INTRODUCTION The control of nuisance water in a mine is extremely important; left uncontrolled, nuisance water can have a severe effect on haulage, ventilation, production, and the health and safety of miners. To control water in mines, a four-step process is followed: (1) prevention, (2) collection, (3) transportation, and (4) treatment. This chapter will be devoted to the collection and transportation of mine water because prevention is usually dictated by pre-mining conditions and initial planning, while treatment is variable and highly site specific. A mine drainage system is nothing more than a collection of gathering points (sumps), machines that impart energy to the fluid (pumps), transportation ducts (pipes), and control devices (fittings, valves, etc.). A pump does not pull the fluid up the suction pipe; atmospheric or external pressure pushes the liquid up the suction pipe to the pump. All references in this chapter will be to centrifugal pumps, due to their popularity for mine drainage. PUMP CHARACTERISTIC CURVES The performance of a pump is plotted on a graph as an indication of its characteristic. To develop the data points, a test facility similar to that shown in Fig. 1 is established. The calibrated Venturi meter is used to measure quantity, the Bourdon gage measures pressure, and the wattmeter measures power input. Various discharge pressures are obtained by throttling with a gate valve in the discharge pipe. Quantity and power are measured at each of these pressure levels, giving the necessary data for plotting the characteristic curves. Fig. 2 shows a typical characteristic curve for a centrifugal pump. Notice that pressure is measured as so many feet of vertical water column above the outlet level, or head. Knowing the quantity (in gallons per minute), head (in feet), and power input (brake horsepower), the pump's efficiency can be plotted based upon the following relationship:

Jan 1, 1986

Australia is a significant exporter of uranium for use as fuel in nuclear generating plants around the world. Although Australia does not have any nuclear power plants the Australian Atomic Energy Commission has a research program on methods for the safe disposal of wastes produced by such plants.

Jan 1, 1986

In 1980 Pancontinental Mining Limited decided that while the Jabiluka uranium project was still a major focus of the company's efforts some diversification was necessary. At this time it was decided to include precious metals in Pancon's exploration and acquisition objectives. As a result the now Paddington Gold tenements were acquired, explored and developed. Today, it rates as the 6th largest gold mine in Australia and at an expanded throughput of 1.2 million tonnes per year of ore it will produce about 110,000 ozs of gold per year. Following extensive exploration activities by Pancon's Exploration Division the Operations Division continued with development drilling finally proving up a reserve of about 8.4 million tonnes at an average grade of 3.2 g/t. An in- house preliminary feasibility study was followed by a two phase feasibility study by Davy McKee. This resulted in a recommendation to the Pancon Board of Directors to develop Paddington with an annual throughput capacity of 875,000 tonnes. This paper describes the acquisition, exploration and development of the Paddington project. It goes on to

Jan 1, 1986

By Scott G. Giltner, Paul N. Worsey

During the short duration of an explosive blast, many events occur which are too quick to be detected or observed in detail with the naked eye or by normal photographic techniques. Through the use of "hightech", high speed video, many of these events can be observed, instantly played back and recorded for later use. The use of a Spin Physics SP 2000 Motion Analysis System at a blast casting operation is presented. The variable range of recording speeds offered by the SP 2000 allowed it to be used for examination of different areas of blasts. At its maximum full frame rate of 2000 frames per second the SP 2000 can easily pick up the flame front as it travels down a nonel tube and the flash from the surface delays as they fire. The system was used for a variety of tasks including, but not limited to,the determination of delay accuracy to within 0.5 ms, the velocity and trajectory of the faces during blasts, and pinpointing geological problem areas. The effectiveness of the system as used on site is discussed along with detailed method of set up, recording, playback and data processing. Other details including site specific environmental and lighting problems are also covered.

Jan 1, 1986

By Koichi Kurokawa, Takeo Ueda, Yoji Tasaki, Masashi Nakano

We have developed a new firing system which simplifies the handling and extensively increases the safety in electric blasting operations. Based on the principle of the transformer, this system is operated as follows: When a high frequency alternating current pulse (70-110 kHz) is applied to the lead wire and connecting wire (primary circuit), magnetic flux is generated in the transcore, and an induced current flows through the looped leg wire of the detonator (secondary circuit). Then the detonators are ignited by the induced current.

Jan 1, 1986

By E. Lefeuvre

Precambien in age, the phospate deposit under study which outcrops to the south forms a synclinal consisting of only one mineralized horizon. The synclinal strikes SSW/NNE, dips from 30 to 60 NNE and is about 5 km wide. The deposit has been explored by : - trenches and pits about 50 m apart in the outcropping area ; - core drill holes forming lines perpendicular to the outcrop. These lines are about 100 m apart. On each line, the drill holes are about 50 m apart The phosphate layer is clearly visible and has then been defined from the geologicia1 description of drill hole logs. The layer has been divided into two parts : a very rich, altered part at the hanging wall and a poor part displaying opposite physical characteristics, i.e. a fresh and hard rock. With open pit mining in view, the deposit has been divided into a 3-dimension network of blocks, each block measuring 50 X 50 X 100 m. The tonnages of rich and poor ore, PO25, MgO, Si02, CaO and R2O3 grades and the tonnages of barren waste at the hanging wall and the footwall have been calculated for each block. Given the dip of the phosphate layer ranging from 30 to 60° and its relative thickness (between 10 and 15 m), it was impossible or inappropriate to carry out direct calculation by 3-dimension kriging : too many neighboring blocks to obtain sufficient date and impossibility to draw up the morphology of the layer.

Jan 1, 1986

By Christopher Mark

Current longwall pillar design methods are based on many assumptions about pillar and entry response to longwall abutment loads. Knowledge of the magnitude and time-of-arrival of abutment loads is essential for Improving design procedures. The abutment loads are in turn related to the development of yield zones and horizontal confining stresses in pillars. Entry stability, which is the goal of any longwall pillar design, is affected by in situ stresses as well as the interaction between the roof, pillars, and floor. The paper describes a study performed in a longwall panel at a West Virginia coal mine. The behavior of two headgate pillars and the adjacent entries was- monitored as the longwall face approached and moved past. The results provided a detailed picture of the response of long- wall pillars and entries to abutment loadings.

Jan 1, 1986

By Donald L. King, Frank A. Baczek

Sedimentation-based equipment is used in applications where separation of solids from liquid by gravity settling is desired. If a concentrated solids slurry is desired, the equipment is designed to "thicken"; if a clear liquid is desired the equipment is designed to "clarify." Thickeners normally handle higher solids loading rates than clarifiers, which usually process feed slurries containing low concentrations of suspended solids. Thickeners are therefore designed for heavier-duty requirements, and clarifiers have extra features to ensure more complete suspended solids removal. Major components (Figure 1) that are common to all sedimentation-based equipment are: tank, drive-support structure, drive unit and lifting device, rake structure, feed well, and a means of overflow and underflow withdrawal. Specific features are designed interdependently after the overall separation approach is defined conceptually. This conceptual approach is usually based on past experience or evolves from sedimentation studies conducted on samples of the slurry to be handled. Because many variations and combinations of components are possible, the overall conceptual approach has a number of possible designs that will accomplish the desired results. The final choice is based on practicality, potential for minimizing upsets, and cost.

Jan 1, 1986

By K. E. Soroka

More than 500 fires are now burning in abandoned coal waste banks and coal deposits in the United States. Once established, such fires can burn for decades, and extinguishing them by conventional methods such as surface sealing to exclude air, excavation to remove fuel, or flushing to cool the fire zone is usually difficult and always expensive. Burnout Control, a technique developed by the Bureau of Mines for the control of abandoned coal fires, involves the accelerated combustion of coal in place with total management of the heat and fumes produced. A burning waste bank or mine is placed under negative pressure relative to the atmosphere, and heat and combustion products are drawn from the combustion zone through an exhaust ventilation system. Heat produced appears as sensible heat in the exhaust, at temperatures as high as 1,0000 C (1,832° F), and could be recovered for the production of steam, hot water, process heat, or electricity. The Bureau's first held field demonstration of Burnout Control was at Calamity Hollow in Allegheny County, PA (near Pittsburgh). Calamity Hollow was the site of an underground mine in the 1900's and was surface mined in the 1940's. In the winter of 1961-62, a fire of undetermined origin was discovered in the exposed coal. In 1963, the Bureau constructed a trench barrier around the fire and a surface seal over the affected area. The fire was isolated but not completely extinguished. In 1979, when the Bureau began work on the Calamity Hollow Mine Fire Project to demonstrate controlled burnout, the fire was still smoldering on the hot side of the trench barrier. The project, which was begun in December 1979 and ended in July 1982, consisted of the design, construction, operation, and subsequent dismantling of a Burnout Control ventilation system. This report is the fifth in a five-part series that describes the Calamity Hollow Mine Fire Project. The first report, part 1, describes the design and construction of the field installation. Part 2 will present the results of a continuous 4-month burnout operation. (Because part 2 involves the analysis of a substantial body of data, it will not be published until after publication of parts 1, 3, 4, and 5.) Part 3 describes the instrumentation used to control and monitor the progress of the burnout operation. Parts 4 and 5 deal with the closeout phase of the field demonstration. Part 4 describes the procedure used to quench the fire, and this part (part 5) describes the final excavation and backfilling of the heated zones. The reports in this series document the Calamity Hollow controlled burnout demonstration which showed that (1) controlled in situ combustion is a feasible method for controlling underground fires in abandoned mines, (2) the resultant thermal exhaust output is sufficient for energy utilization, and (3) water injection-fume exhaustion is a potentially effective method for cooling large underground fire zones. Further investigations of both Burnout Control and the water-injection-fume exhaustion quenching procedure are planned.

Jan 1, 1986

By Carlos G. Levi

"The principles involved in the rapid solidification of supercooled metal droplets and existing numerical models are reviewed. The limitations of these models for studying alloy solidification are discussed in terms of the effects of alloying elements on the relevant heat transfer, thermodynamic and kinetic parameters. Analysis of the enthalpy-temperature diagram reveals how the extent of rapid solidification is hindered by the addition of solute. A solidification model incorporating thermodynamic and kinetic relationships into a Newtonian heat transfer formulation is used to analyze the thermal history and concurrent solute redistribution during recalescence. IntroductionIt is well acknowledged that microstructural evolution during solidification is intimately associated with the thermal history of the liquid-solid interface. Structural parameters like chemical homogeneity, morphology and size scale of the phases can be related to the interfacial temperature and velocity. These in turn change by the interaction of the interface with the thermal and solutal fields in its neighboring environment.The thermal history of powder solidification can be conveniently described on the enthalpy-temperature diagram for a pure metal shown in Figure 1 and discussed in detail elsewhere [1). A system can conceivably follow any path of decreasing enthalpy in the supercooled region of Figure 1 (~ < 1), starting at the nucleation temperature (oN < 0) on the liquid line, and ending at some point on the solid line. A vertical path represents an isothermal transformation, of which a limiting case is solidification without significant barriers to nucleation and growth, with the interface at the equilibrium temperature TM (path one in Figure 1). A horizontal path represents isenthalpic (or adiabatic) solidification whereby the system could form an amount of solid proportional to the initial supercooling of the liquid without further heat loss to the environment. A liquid that can completely transform to solid under adiabatic conditions is said to be ""hypercooled""."

Jan 1, 1986

By Donald O. Capstick

A mineral survey of a 5,700-acre portion of the 11,510-acre Upper Deep Creek Wilderness Study Area (ID-111-44B) in southwestern Idaho was conducted by the U.S. Bureau of Mines in 1985. No mining claims have been located, no minerals have been produced, and no resources have been identified in the study area. Three reconnaissance samples of alluvium from the Deep Creek drainage contained $0.21, $0.22, and $2.72 per cubic yard in placer gold, higher than usual for the Owyhee River canyonland area. The samples of near-surface material contained very fine gold in values too low to support large-volume commercial placer operations, but the quantity and size of the particles of gold in the alluvium is expected to increase near bedrock. Consequently, the area may be a target for recreational as well as small commercial suction dredge operations. The physical characteristics of the individual pieces of gold (bright and angular) indicate that it may have recently come from an unidentified nearby source.

Jan 1, 1986

By J. L. Kohler

The knowledge-based expert systems (KBES) is a potentially powerful technique to the mining engineer in traditional areas of mine design and operations, as well as in the emerging areas of mining automation and robotics. Since KBES is still experimental in many respects, caution must be exercised as this "high tech" tool is developed and applied to mining. The objective of this paper is to demystify expert systems by introducing the elements of KBES, discussing the strengths and weaknesses, and identifying some areas of application in mining, based on the authors&apos; experiences.

Jan 1, 1986

By D James

Fletcher Challenge Limited through its subsidiary Grampian Mining Co Limited has carried out an ore evaluation of one of New Zealand&apos;s largest known deposits of ilmenite located at Barrytown on the West Coast of the South Island, New Zealand. The ilmenite is located in a beach sand environment which has previously been mined for gold. Two analytical techniques were developed to quantify the resource. Considerable difficulty was experienced in this phase of the evaluation due to the presence of major inclusions within the ilmenite grains. Wet and dry concentration circuits, utilising spiral, wet magnet, high tension and plate electrostatic separators have been designed to produce ilmenite from the ore. Studies to utilise the titanium content of the Barrytown ilmenite have been made. Recent work has been directed towards a titanium dioxide pigment process.

Jan 1, 1986

By J. J. Gusek, J. T. Gormley, V. Scovazzo

Glenrock, WY is underlain by two abondoned coal mines. Subsidence events have been recorded over the years, with the frequency increasing in recent years. As part of Wyoming&apos;s Abondoned Wins Lands Program, investigations including mining history/methods/mappings, subsurface drilling and material site searches were performed. Portions of the mines less than eighty feet from the surface, were identified as probable for subsidence. Subsidence control by hydraulic backfill was selected. Design included search and injection boreholes, water supply from the mines and the slurry mixing, transport and injection system. Injection system performance and backfill success is king monitored during construction.

Jan 1, 1986

By D. M. Milne, H. H. Kanduth

INTRODUCTION The past few years has seen an increased interest in the determination of statistically valid properties of a rock mass. The increased use of computer modelling for the study of rock excavation behaviour has created a need for upper and lower statistical bounds for the properties of a rock mass being modelled. Obviously, to determine the statistical properties of a large volume of rock, many samples must be tested - an expensive proposition when using conventional testing facilities and procedures. As a result of high costs per sample, sufficient tests for statistically valid results are rarely done. In an effort to reduce both sample preparation and test facility costs, an instrument called the Bemek Advanced Rock Tester (BRT) was developed in Sweden. With a total weight of approx. 35 kg, the BRT is portable and sells at a small fraction of the cost of a conventional testing machine. It is comprised of a small 65 KN loading frame with attachments for a variety of tests (see Table 1) , a hand operated hydraulic pump, an electronic balancing unit and a programmable microprocessor. The microprocessor is capable of storing data, performing arithmetic operation on, and printing signals from, a transducer and two strain gauges. A detailed description of the apparatus is given by G. Swan et al. (1). The proposed test strategy involves first a 3-point flexure test on a notched core specimen, followed by a 4-point flexure test on the separated specimen halves. Finally, point load and Brazilian tests can be carried out on the quarter parts of the original specimen. Thus specimen preparation is kept to a minimum. These and other perceived advantages have prompted the purchase of this machine and an evaluation of its suitability to provide data on mechanical properties of intact rock for numerical modelling and rock mechanics design at Noranda&apos;s underground mines. Details of its performance evaluation and experiences with the unit are discussed in the following sections. [ ] INITIAL OPERATING EXPERIENCE During the commissioning stage the BRT had, or developed, a series of problems, some of which seriously affected its operation. Below are some examples. Poor documentation was the most serious problem encountered. Confusing instructions for the 4-point bend test installation and its microprocessor programing, as well as poor and ambiguous information on the calculation of gauge factors, are some of the difficulties which had to be overcome. Meehan~cal problems occurred, including failure of the hydraulic pump, as well as electronic difficulties with the microprocessor. Other problems with the printer, requiring its replaceqent, were fortunately covered under warranty.

Jan 1, 1986

By D. R. Brooks

The Bureau of Mines has tested a dewatering technique for phosphatic clay waste. The technique utilizes a flocculant, polyethylene oxide (PEO), that forms strong, stable flocs that can be dewatered on a static screen followed by further dewatering on a rotary screen or trommel. In field tests conducted in central Florida, clay wastes containing approximately 4 pct solids have been consolidated to greater than 20 pct solids. The rate at which PEO-treated material continues to dewater in a mine cut also was monitored. Preliminary results indicate that PEO-treated material will dewater to 30 pct solids in 80 days. Pretreatment of phosphatic clay waste with lime lowers the PEO dosage required for dewatering.

Jan 1, 1986