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By William G. Pariseau

The research reported here concerns ground control in multi-seam mining and relates mainly to the analysis of stress about multi-seam room and pillar mines. The two variables of most concern are distance between seams and alignment of pillars between seams. The first year results of the two year investigation apply to the development phase of mining when the extraction is typically less than 50 percent. The second year effort is concentrated on retreat mining and barrier pillar safety when the extraction is typically greater than 50%. The procedures in both cases are readily applicable to more than two seams. Although two seam mines are the most frequent type of multi-seam operations, because of the potential for three seam operations in the Western United States, a number of three seam development analyses are also presented. The results enable one to make a rapid assessment of stability of rooms and pillars during production and barrier pillar size during extraction of adjacent panels. In the event of low safety factors, more site-specific analyses can be undertaken.

Jan 1, 1983

By Arthur A. F, MacKenzie I. H

Copper in zinc/lead sinter charged to the Imperial Smelting Furnace operated by Sulphide Corporation Pty Limited at Cockle Creek, New South Wales, concentrates in a complex lead dross which forms as the bullion is cooled to around 400°C. The 0.35 mm portion of this dross, containing approximatelY 67 per cent of the total copper, is treated via a hydrometallurgical route to produce 5000 tonne/yr of CuSO4 5H2O crystal.Around 3000 tonne/yr of copper-lead dross containing 49 per cent copper is leached at 55°C in continuous leach reactors with ammoniacal ammonium carbonate leach liquors to convert copper to soluble copper amine complexes. Leach ettlciencies of 80-85 per cent are obtained. Leach residues are repulped with ammoniacal liquid diluents from the plant and heated in a four stage steam distillation unit to reduce ammonia levels to between 0.5 and 1.0 g/Iitre. The resultant slurry is directed to an effluent treatment plant for final treatment, and separation and return of solids to the sinter plant.Copper is extracted from leach liquor by solvent extraction techniques based on the use of L1X 54 diluted 3:1 with Shellsol 2046 to give a nominal copper loading of 30 g/litre. The loaded organic is contacted with a sulfuric acid solution of pH 5 to remove the bulk of ammonia and zinc, then stripped at 55°C with a 60 g/Iitre H2SO4 95 g/Iitre copper solution to yield a 15 g/Iitre H2SO4 125 g/Iitre copper solution.This liquor is fed to an adiabatic vacuum crvstalliser operating at 35°C and 5 kPa vacuum where crystals of CuSO4 5H2O are formed. Crystals are separated from mother liquor and washed in a two stage pusher centrifuge, then dried in a hot air rotary drier. The crystal product obtained is of a high chemical purity and readily conforms to both Australian and overseas standards.

Jan 1, 1983

By C. R. Carpenter

A dynamic gas-mixing system assembled by the Bureau of Mines for the generation of precise gas mixtures from sources of concentrated or pure gases and diluent gases is described. A set of electronic mass flow controllers with maximum flows ranging from 10 to 5,000 ml/min, a so-called Pure Air Generator, and gases in cylinders are used to generate differing gas concentrations. The repeatability of the delivery rate of a flow controller, measured on different days, has a precision of 0.3 pct of the setting. This dynamic gas-mixing system reduces the cylinder inventory and the demurrage charges for special gas mixtures. Gas mixtures that cannot be shipped commercially, such as flammable mixtures of methane in air, can be conveniently prepared by this system. The maximum dilution ratio is 2.5 x 104. Thus, gas mixtures can be made over a wide range of concentrations, from the percent region (by dilution of a pure single-component gas) to fractional parts per million (by dilution of a premixed standard, e.g., a 1,000-ppm mixture). This system is especially useful in determining the response of gas detection devices over the entire range of their measurement. Because the controllers are voltage controlled they lend themselves easily to automated control using computer-based systems.

Jan 1, 1983

By R. S. Olsen

Although aluminum is easily leached from calcined clay with boiling mineral acids, the presence of fines and slimes in the leached residue has hindered the application of acid leaching processes. A feed preparation method was, therefore, devised that provided a dense, smooth-surfaced, fine-grained clay. The important factors affecting feed quality were determined to be (1) crushing the raw clay to the size desired for the leaching process, (2) moistening the crushed clay with a fine mist of water while tumbling on a rotating disk, (3) drying the misted clay, and (4) calcining the dried clay at 750° C in a fluidized bed. Clay treated by this method was leached with HCI, and its residue was washed by water displacement in 4-ft-deep beds. Bed permeabilities on the order of 47 darcys or 4.6 x 10-7 cm2 were obtained with the leached residues.

Jan 1, 1983

By M. M. Wong

The Bureau of Mines, under a cooperative research program with four lead companies, has investigated a nonsmelting process for the production of lead metal. The process, which would eliminate sulfur dioxide generation and minimize particulate lead emissions, involves ferric chloride leaching of galena concentrate to produce lead chloride, followed by molten-salt electrolysis of the lead chloride to yield lead metal and chlorine. This chlorine is used to regenerate ferric chloride in the leaching solution. The process was tested in an experimental unit with a capacity of 500 lb of lead metal per day. The tests were performed in three 10-day and six 5-day campaigns, during a period spanning 28 mo. The study was carried out using a southeastern Missouri lead concentrate. Typical lead recovery was about 98 pct. Process problems related to impurity buildup and control were studied. When copper and silver impurities were removed from the leaching solution, a lead metal purity of 99.999 pct was obtained. Lead-in-air levels and lead-in-blood levels of operating personnel were monitored. The process has potential for producing lead with minimum pollution, but is not ready for commercial utilization. Operation of a prototype commercial electrolytic cell and a full-scale pilot-plant investigation by industry are needed to evaluate the commercial viability of the process.

Jan 1, 1983

By Ronald T. Mayerle

The Condrey Mountain RARE II area lies mostly within the Elliot Creek mining district, a significant producer of gold from placers, and gold, Silver, copper, and minor soapstone from lode deposits. No mineral production has occurred within the study area; no resources are known in the area. However, significant resources in lode and placer deposits are just outside the west and northwest boundary of the area. The Blue Ledge Mine (fig. 1, no. 15) adjacent to the western boundary, is reported to contain 226,000 ton; (205,000 t) of identified resources averaging 0.05 oz gold per ton (1.7 g/t), 2.16 oz silver per ton (/4.0 g/t), 3.5 percent copper, and 3.95 percent zinc. The mine has produced 11,131 tons (10,114 t) of ore that yielded 1,026 oz (31,908 g) of gold, 58,431 oz (1.8 million g) of silver, and 2.7 million lb (1.2 million kg) of copper. Exploration is currently underway at `he mine and vicinity, including part of the study area.

Jan 1, 1983

By Fritz F. Prugger, Peter R. Jones

This paper considers some of the main aspects of underground mining in the flat, rich, but deep lying deposits of Saskatchewan. It briefly describes the pertinent geological features as they relate to mining and the practical de-stressing techniques used to allow productive extraction in the high stress environment present in many of the province’s mines. Mining layouts, materials handling, and the evolution of some of the world's largest mining equipment are examined.

Jan 1, 1983

By S. J. Gerdemann

In support of its objective to improve mine safety, the Bureau of Mines has searched for better materials and systems to anchor roof bolts. TIlis report describes a study on the effects of mine waters upon accelerated gypsum, one of the materials under consideration. The accelerated gypsuw dissolved at an appreciable rate relative to an assumed 10-yr life span of a roof bolt. Surface orientation, initial ion concentration of a dissolving solution, and flow rate of the solu-tion had substantial effects on the dissolution rate. Factors such as water-cement ratio, accelerator content, wax capsule additions to the gypsum in cartridge-installed bolts, surface area, temperature, and curing duration had little effect. In an actual roof-bolt environment, dissolution will occur in static solutions to the solubility limit of gypsum (~2 giL) and cease, result-ing in minimal damage; but in flows of unsaturated solution as slow as 1 L per month, a loss of up to 10 pct will occur in 2 yr. Since miners cannot readily measure the flow or ion concentration of static-appearing water at every roof-bolt site, all such water must be assumed to be pure and flowing. It is recommended that gypsum-bonded roof bolts be confined to dry roofs only.

Jan 1, 1983

By Lyman G. J

Magnetic separator operation in the recovery of magnetite in heavy medium circuits was studied by conducting a series of tests on a full size wet drum magnetic separator.The significant operational variables were found to be feed pan clearance, squeeze pan clearance, dry magnetite feed rate and separator drum speed. With feed and squeeze pan clearances optimized for typical primary separator operation, magnetite loss and concentrate specific gravity were found to be related in a regular manner to dry magnetite feed rate at any drum speed.A two component model of magnetite loss is proposed, relating total magnetite loss to losses in the feed pan and squeeze pan zones. The experimental curves relating magnetite loss to dry magnetite feed rate at the various drum speeds are interpreted in terms of the two component model.The magnetite particle size distribution in the separator was also examined. The tailings magnetite was found to be finer than the feed magnetite only when the dry magnetite feed rate was low, or immediately following the introduction of a new charge of magnetite when the separator was fed at an intermediate dry magnetite feed rate.

Jan 1, 1983

By C. H. Bertoni

"The Superior Province of the Canadian Shield is the largest gold producing area within Archean greenstone rocks in the world, with total production of over 140 million ounces of gold. One hundred and fifty-five mines have individually produced more than 8,000 ounces, although only a relatively limited number of deposits (33) produced more than one million ounces of gold. The output from these 33 deposits accounts, however, for 85% of total gold production. The majority of grades (68%) ranges between 0.10 and 0.30 ounce per ton, and there is no linear relationship between grade and tonnage.Development of new gold mines reflects the history of gold prices. However, the response to the latest increase in gold prices was not as marked. It is concluded that gold deposits are becoming increasingly more difficult to find and new exploration techniques are urgently required.IntroductionWith most of its production coming out of the Superior Province, the Canadian Shield is the largest producer of gold from Archean greenstone rock s in the world. In total gold production, the Superior Province is surpassed only by the paleo-placers of Witwatersrand and the placers of the USSR (Anhaeusser, 1976). There has been no attempt so far to compile the historical production of the Province as a whole in a single document. The aim of this work is to fill this gap, not only for the convenience of having a complete list of gold producers, but, more importantly, as a basis on which to study the tonnage and grade characteristics of these deposits."

Jan 1, 1983

By Bill M. Stewart

Since 1974, a large amount of data has been developed concerning the physical properties and stability characteristics of waste generated by the mining and preparation of bituminous coal. However, very little information has been developed on the properties and characteristics of anthracite waste. During this Bureau of Mines research project, coarse anthracite breaker refuse from five sites in eastern Pennsylvania was sampled and the physical properties, which indicate stability characteristics, were determined in the laboratory. Coarse anthracite breaker refuse is quite similar to coarse bituminous refuse in chemical and mineralogical composition. However, the physical properties of the anthracite waste materials tested are different from those of coarse bituminous refuse. For the coarse anthracite breaker refuse tested, the average maximum laboratory density is 113.2 lb/ft3, the average angle of internal friction (direct shear) and average cohesion are 30.2° and 2.6 psi, respectively, and the average permeability (four sites) is 1.24 x 10-2 cm/sec. Stability analyses were conducted on six theoretical anthracite waste embankments. These analyses show the effects on minimum safety factors of geometry, phreatic surface level, and physical properties.

Jan 1, 1983

By Z. T. Bieniawski, E. H. Skinner, R. A. Cummings, F. S. Kendorski

INTRODUCTION Caving Mine Drift Support Design The support of production drifts remains a high-cost item facing the developer or operator of an underground caving mine. Support costs are incurred well in advance of ore production, and there is a strong need to minimize these pre-production commitments of capital. Due to the extensive rock loads that normally develop during the caving process, the support used in caving mines is typically quite heavy and therefore costly. The process of designing this support increasingly makes use of basic tunneling principles, but is hindered by the still-incomplete state of knowledge of rock behavior in caving mines, and high variability of geological conditions in caving orebodies. Caving mines differ from tunnels in that the deformations and rock loads induced are transient and dynamic in occurrence, and are normally large in magnitude, often well in excess of rock mass strength. As opposed to tunnels, caving mine layouts are more intricate, and the methods and effects of construction ordinarily are not as closely monitored. Safety factors in mining tend to be lower and rock masses tend to he weaker. These aspects prevent strict application of tunnel design technology to caving mine drift support, with the result that mine drift supports are commonly designed chiefly on the basis of experience at other mines. Mining procedures at caving mines are evolved in response to site-specific requirements, to the extent that there are really as many caving methods as there are caving mines.

Jan 1, 1983

By Yoneji Kanoh, Masahiko Ohtsuka

In Japanese tunneling history, it has commonly been accepted that the long-round driving is difficult due to the complicated geological condition. Therefore, the maximum past record has been less than 3 m per round. A new record of advance was established in the 99 m2 headrace tunnel of Imaichi Water Power Station Project with an advance of 239.5 m in a month by drilling 3.9 m deep blast holes. The geology of the headrace tunnel composed of pyroxine andesite (ie. 960-1770 kg/cm2, VP3.1-4.3 km/s) which had several clay seams and open cracks and was moderately weathered. Automatic shotcrete machine was used for shotcreting. Rock support was specified according to the N.A.T.M. with each different rock type. The contractor achieved a remarkable tunneling advance not earlier experienced in Japan.

Jan 1, 1983

By G. R. Smith

Critical and strategic metals are often present in small quantities in low-grade domestic ores. When these ores are leached, the resulting solution usually contains the metals in very dilute quantities. Selective electrowinning from dilute electrolytes was investigated by the Bureau of Mines. A metal deposit containing 84 pct nickel was electrowon from the leach solution of a complex domestic ore bulk flotation concentrate originally containing approximately 2 wt-pct nickel. Key to achieving accelerated deposition rates, in the case of dilute solutions, is the rapid movement of the electrolyte through the electrowinning cell. Pure, synthetic nickel electrolytes were used to establish deposition parameters, and to optimize electrolyte velocity or mass transfer rates. Hydrodynamic and electrodeposition parameters for both the synthetic and leach electrolytes are presented and the experimental research described. Selective electrowinning appears to offer a viable alternative to physical separation methods to obtain separate metal "concentrates" from low-grade ores.

Jan 1, 1983

By Dutton D

In the British coal mining industry, during the last decade, a great deal of environmental monitoring experience was acquired, particularly in the Doncaster Area of the Yorkshire coal- field, which had a long history of spontaneous combustion and gas emission problems. This paper summarises the experience obtained and shows how the introduction and operation of these systems has resulted in improved techniqu- es for fire detection and control. Some of these systems are described in detail with emphasis placed on the uses to which output data are put, and their impact upon management at colliery level. Reference is also made to the problems encountered in the development of such systems and how they were solved. The paper also makes reference to the recent Research and Development work of the NCB's Scientific Department and Mining Res- earch Development Establishment (MRDE), which was directed to the design and application of a range of underground sensors, and so ensured continuing progress in this field. The paper refers briefly to a new comprehensive monitoring unit and an integrated fire detection and data transmitting system which are currently being assessed in the Yorkshire coalfield.

Jan 1, 1983

By Richard S. Gaps

The Derby and Alexander Claim, located within the Tunnel Ridge Wilderness Study Area (WSA), has placer gold resources. No lode deposits are known within the area, but lode gold deposits are found within 1 1/2 mi of the WSA. In additon, rock units which contain lode gold deposits north of the WSA are found within the northern portion of the study area. INTRODUCTION The Tunnel Ridge Wilderness Study Area (WSA), CA-030-402, encompasses 4,623 acres of BLM administered public land in Trinity County, California, about 35 mi west-northwest of Redding (fig. 1). Major access to the Tunnel Ridge vicinity is by U.S. Highway 299. Ac-cess to the WSA boundary is by a secondary paved road from Junction City and several light duty dirt and gravel roads (fig. 2). The WSA is on the southwest slope of Weaver Bally Mountain. The topography is rugged with moderate to steep slopes; elevations range from about 1,600 ft to 5,900 ft.

Jan 1, 1983

By Donald O. Capstick

The U.S. Bureau of Mines conducted an inventory of the prospects and mineral resources in the Scodies RARE II area (No. 5212) in 1982. No mineral production is recorded from the area, and no mines are being developed. The Scodies RARE II area is comprised primarily of light colored granodiorite with minor inclusions of mafic granitic rocks. Late stage differentiates of magmas resulted in quartz veins and pods. Metasedimentary rocks which have been mineralized in some parts of the Sierra Nevada were not observed within the study area during this investigation but small inclusions have been reported.

Jan 1, 1983

By T. A. Rundle, K. Kim, W. M. McCabe, E. C. Gregory

Overcoring tests were conducted at the Near-Surface Test Facility(NSTF) to assess the suitability of five techniques (U.S. Bureau of Mines borehole deformation gauge (BDG), Commonwealth Scientific and Industrial Research Organization (CSIRO) hollow inclusion stress cell, Luleå triaxial gauge (LuH gauge), and Council for Scientific and Industrial Research (CSIR) doorstopper) for in situ stress determination in a closely jointed basalt. This effort is in support of the Basalt Waste Isolation Project, which is studying the feasibility of locating a nuclear waste repository in the basalts of the Hanford Site in southeastern Washington. This paper presents the results from the overcoring study that formed the basis for selection of two techniques to be used during the further exploration of the basalt formations at depth.

Jan 1, 1983

By Rixon K. L

Hargraves (1983) has reviewed the phenomenon of instantaneous outbursts of coal and gas with special attention to Australian occurrences. The purpose of this discussion is to highlight some problems and omissions in his review that reflect particularly on the authors' structural geological investigations of outburst-prone coal seams.It is surprising to find that much of the authors' reported work has either been glossed over or the results distorted by Hargraves (1983) and it is, therefore, important to clarify the contribution that structural analysis of coal seams can make.For many years it has been known that faults provided preferred loci for gas outbursts (for example, Briggs 1920-21) but the roie that faults played in outburstprone seams was unclear. The present authors reviewed the association of faults and outbursts drawing upon local investigations and the world-wide literature (Shepherd et aI., 1981), and discussed some wideranging aspects that result from the high coincidence of faults and outburst sites. Without repeating large segments of this article the authors will discuss four aspects of coal seam faulting and fracturing.

Jan 1, 1983

By C. O. Brawner

FACTORS THAT INFLUENCE STABILITY AND STABILIZATION METHOD The most effective stabilization method and design can only be developed if the cause(s) and mechanics of the slide are known. Therefore, it is important that the stability be evaluated by an engineer who has had extensive rock stability experience. The most important factors that influence stability are structural geology, ground water, blasting and the mining method or methods. Structural Geology - The majority of failures in rock slopes occur along discontinuities in the rock (joints, bedding planes, shear or fault zones, etc.). Therefore, on all surface mining projects, the development and maintenance of a comprehensive structural geologic mapping program should be a first priority program that is considered a part of the operations function. This program should include mapping all major features - faults, shear zones and through going joints. All structural features which could influence stability should be mapped and presented in a structural domain format for the entire mine (Canmet, 1977). Where planes, wedges or blocks will be undercut by the mining excavation, shear strength and strain to failure tests should be performed on the joints, fault gouge and gouge-rock contact surfaces. These tests must be performed on the samples in the direction of potential slide movement and must determine the range of peak and residual shear strength values. A preliminary assessment of friction angle can be obtained from measurements of failed surfaces in the field (Figure 1) or from core sliding tests (Barton, 1981). An assessment must be made of the past geologic history of

Jan 1, 1983