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By Lester M. Adams

In 1980, the Bureau of Mines surveyed a group of mine seals in Randolph County, WV, to evaluate their effectiveness for reducing toxic pollutants in mine water discharges. The survey focused on 11 block wet mine seals, but mine seals of several other types were also examined. The seals were installed in 1966 and 1967 in abandoned drift portals by the Federal Water Quality Administration (FWQA), a predecessor of the Environmental Protection Agency (EPA), in cooperation with the Bureau of Mines and other Federal and State agencies, in a project known as Elkins Mine Drainage Pollution Control Demonstration Project. The seals were designed to prevent air from entering the mine portals while allowing mine water to flow out. It was believed that by preventing air from entering inactive or abandoned mines, the formation of toxic pollutants and acid mine drainage (AMD) could be reduced. Evaluation of the seals was based on water flow measurements, water analyses, and visual observations. The Bureau's 1980 data were compared with past data collected by the EPA. Several leaks and failures were observed in the clay seals, as evidenced by apparent blowouts and the absence of vegetation where the mine water surfaced. Analyses of the 1980 data indicated some improvement in the quality of water discharged from many of the wet air seals.

Jan 1, 1984

By Shosei Serata, Bruce Gardner

A system of three new field instruments has been developed to measure, in situ, the three basic classes of geomechanical parameters: material properties, stress state, and creep deformation. The significance of this development is that it represents a successful adaptation of recent computer technology to underground rock mechanics work, opening up new possibilities in underground mining methods. The system was developed to meet the application requirements of the stress control method of mining, a method which is based on the actual geomechanical conditions of the underground, rather than upon conventional linear-elastic, idealizations of ground conditions. These instruments enable in situ measurement not only of elastic, but also post-elastic, yielding, and failure conditions of geological materials, establishing the stress control method on a truly scientific foundation. In order to evaluate the present status of this field instrumentation system, case examples of underground mine openings designed with the stress control method are reviewed and analyzed, in terms of the effectiveness of the three instruments for informing and guiding the site-specific application of stress control design.

Jan 1, 1984

By D. M. Wyslouzil

"This paper was prepared for presentation at the 16th Canadian Mineral Processor's Annual Meeting, Ottawa, Ontario, Jan. 17 to Jan. 19, 1984.This paper gives an account of the development of treatment procedures for the differential flotation of refractory copper-zinc ores. Special references are made to the effectiveness of various zinc depressants and their combinations.Studies carried out on refractory copper-zinc ores demonstrated that conventional zinc depressants such as cyanide and zinc sulphate were not particularly effective when secondary copper minerals were present in the ore; the flotation activity of sphalerite was enhanced in the presence of cyanide.Among the various zinc depressants evaluated, the following depressant combinations were found most effective: Zn(OH) 2-S02 , 802-CaO, Na2S-Na2S03-S02, Na 2 S-S02 and Na 2S-S0rDS22.The practical application of any of these systems depends on the type of ore treated and other conditions such as pH, levels and points of collector and depressant additions.In this paper the effect of each depressant combination on different ores is described with reference to the selection of collectors."

Jan 1, 1984

By Mark W. Springett

The sampling of precious metal deposits entails inherent problems due to the low mineral abundances, high mineral specific gravities, skewed grade distributions and wide ranges of mineral particle sizes. Sampling practices and precautions are discussed with particular attention to each of the tripartite stages of sampling - sample acquisition, sample preparation and sample assaying. Practical examples of approaches to the sampling problem are given and some examples of significant sources of error are provided from gold and silver deposits in North America.

Jan 1, 1984

By F. C. Loughnan, Shane B. Sadleir

Bauxite is currently produced at three centres in Australia: - Weipa in northern Queensland; Gove on the northeastern tip of Northern Territory; and in the Darling Range near Perth, Western Australia. At each of these centres the bauxite is of Tertiary age and occurs as blanket-like, lateritic crusts in which gibbsite is the predominant mineral. Development was essentially in situ although possibly the deposits, particularly at Gove, are in part of transported origin. All of the deposits formed from quartz-rich parent rocks with those at Weipa and Gove being derived from kaolinitic sands while in the Darling Range, granite and other crystalline rocks of Precambrian age immediately underline the lateritic bauxite.

Jan 1, 1984

By Frank S. Shuri

INTRODUCTION The Calumet Pumping Station, located on the south side of the Greater Chicago area, is part of the Tunnel and Reservoir Plan to accomodate the city's wastewater. The Station consists of two parallel rock caverns, each 18 m high, 20 m wide, and 62 m long, located in Silurian dolomite approximately 91 m below the ground surface. The caverns are oriented N-S with a 24-m-wide pillar between them. Prior to construction, rock mechanics studies were conducted in an L-shaped test adit at the location of the west cavern. The purpo3e of the rock mechanic studies was to characterize the site, particularly the in situ stress field and deformation characteristics of the rock. This information, together with other physical properties of the rock and geologic data, was used to evaluate the stability of the preliminary cavern design, with particular emphasis on cavern orientation, rock reinforcement, and pillar stability. GEOLOGY OF THE SITE Stratigraphy The Chicago area is located on the Kankakee Arch, a broad, gently sloping arch of Paleozoic sediments. Rocks in the project area consist of Silurian dolomites unconformably overlain by Pleistocene glacial deposits. The formations of interest to this study are: - Racine Formation, inter-reef facies. This dolomite is gray- brown, silty, and compact. It contains occasional prominent bedding surfaces. The Racine Formation in the project area varies from 73 to 74 m in thickness.

Jan 1, 1984

By Dr. O’Neil Thomas J., Donald W. Gentry

"We should be concerned about the future be- cause we will have to spend the rest of our lives there. " -Charles Kettering INTRODUCTION Since the early 1970s, there has been no economic phenomenon that has been more widely discussed or experienced in the United States than inflation. Al- though its precise definition and measurement are elusive, inflation has had pro- found and extensive impacts on the manner in which nearly everyone lives. It is painfully obvious to consumers that inflation is characterized by a continuing up- ward spiral of prices. In a capital-intensive industry like mining, those increases can be positively breathtaking. An interesting example is shown in Table 1. Table I shows that on a unit basis, the equivalent 1980 capital cost of Cuajone was over six times the cost of the adjacent and quite similar Toquepala operation completed in 1959. Such sobering statistics weigh heavily on the minds of executives who are contemplating major investments in new mining facilities. In spite of its monumental presence, inflation has usually been either inadequately covered or totally ignored in textbooks on engineering economy. The reasons for this are not entirely clear, but a contributing factor is the inherent difficulty in accurately predicting inflation. However, under certain conditions, inflation may become the most important factor in a mining investment, and it can rarely be safely ignored in capital investment analyses. DEFINING AND MEASURING INFLATION Defining inflation and related terms is relatively easy. Its measurement, how- ever, is the source of almost endless debate in economic and political circles. How- ever, much of that debate is not relevant to the scope of this book, so that only those issues which impact directly on the capital investment decision are covered in this section. Inflation is the general decline in the value of money as measured by what it will buy. It is clear, then, that the rate of inflation varies with the particular currency under consideration as well as the type of goods and services being purchased. One would find, for example, that the general rate of inflation relative to German marks

Jan 1, 1984

By A. M. Strauss

This contribution illustrates the application of the theory of period doubling to the description of the formation of microcracks in rocks. The fundamental mathematics is described and a method of prediction is proposed. The invariance (universal constants) of a generic microfracturing (damage) process is described. Finally, the method is presented as a deterministic method of predicting the failure of an engineering material while keeping track of the amount of damage that has occured at any point.

Jan 1, 1984

By R. K. Bowden

In an effort to gain a better understanding of shale joint behaviour, normal-only and shear creep tests were performed on artificially prepared shale joints. Pre- and post-test surfaces were examined for changes in morphology. This paper discusses both of these programs and the results derived from them.

Jan 1, 1984

By James R. McVey

Tests during pillar robbing, longwall operations, and other mining activities indicate that roof-floor convergence rates can be used as an indicator of imminent roof failure. A large number of electrical-mechanical devices have been built to measure convergence as well as convergence rates, but most obstruct mine traffic and are costly and time consuming to install. The Bureau of Mines has designed and is evaluating three types of small ultrasonic units to make these measurements. The new instruments provide nonobstructing measurements up to 35 ft away. The ultrasonic transducers can be attached to a roof bolt, placed in an unsupported area (by means of a toss basket), or handheld. Total distance to the target and rate of closure are displayed digitally to 0.001 ft and 0.01 ft/min, respectively.

Jan 1, 1984

By William A. Hustrulid

INTRODUCTION Prior to the mid-1970's, the U.S. Radioactive Waste Disposal Program was focused on salt deposits as the geologic medium of choice, almost to the exclusion of other rock types. These efforts are illustrated by the Project Salt Vault experiment in a salt mine at Lyons, Kansas, in 1965-1967 followed by attempts to locate a repository site in central Kansas. Preliminary evaluation of other geologic media led, in 1978, to the GAIN (Geotechnical Assessment and Instrumentation Needs for Nuclear Waste Isolation in Crystalline and Argillaceous Rocks) Symposium held at the University of California (Berkeley), for the purpose of preparing a state-of-the-art document together with research needs for some of the other possible rock types. Because possible sites had not been selected, nor would they be for some time, the primary emphasis was for research and development focused on generic rocks and generic sites. A basic ground rule at that time was that the host rock formation should provide the primary containment for the waste. Also, the U.S. Nuclear Regulatory Commission (NRC) was just drafting the proposed rules regarding site suitability so that this input was not available. The collection of baseline data, conduction of some critical experiments both in the laboratory and field, and the performance of scoping studies were deemed needed. Such work was indeed undertaken; and to date, a great deal of information has been compiled and much has been learned regarding the characteristics of rock masses, rock behavior

Jan 1, 1984

By C. Michael Dickinson

In support of the DNA Deep Basing Program, SRI International has been performing scale model experiments on protective structures since 1973. The SRI program includes field and laboratory tests of mini- structure models with surrounding natural or simulated geology. This paper contains a synopsis of some of the results of this research.

Jan 1, 1984

By I. Stapf

Systematic investigations on silver-rare earth metal systems have been extended on the Ag-Ce system in order to clarify the discrepancies reported in literature. The phase diagram has been reinvestigated on the base of thermal analyses and of microstructure examination on cast and annealed specimen. All intermetallic phases Ag4Ce, Ag3Ce, Ag2Ce and AgCe show no extended range of homogeneity, they melt congruently fm), or decompose peritectically (d) at 815 °C (d), 1030 °C (m), 855 °C (d) and 855 °C (m), respectively. The system shows eutectics at 793 °C/10 at.%, 780 °C/42 at.%, and about 505 °C/81 at.% Ce. d-Ce dissolves up to 2 at .% Ag and decomposes metatectically at 710 °C. Furthermore, the phase transformation of the intermetallics would be clarified. The phases Ag5Ce and Ag51Ce14 reported in literature could not be verified.

Jan 1, 1984

By Roberts T, Firth B. A

A series of flotation experiments was carried out to study the interaction between the parameters of pulp density (mass per cent of solids in feed slurry) and frother addition (on the basis of solid mass feed rate). It was found that certain combinations of pulp density and frother additions caused large losses in yield. The interactive effect of these parameters can be primarily attributed to the total amount of frother added per unit of water. Consequently it is suggested that frother additions be made on the basis of water flow rate. As frother addition increased, in terms of the amount of frother per unit of water, yield increased rapidly but above an addition rate of about 10 g/tone it reached a plateau. Such results correlated well with qualitative visual observations of changes in bubble size and dispersion, with increasing levels of frother addition.

Jan 1, 1984

By R. G. Sandberg

Many gold-bearing ores throughout the Western United States contain small quantities of mercury. The presence of mercury not only decreases the gold-loading capacity of the activated carbon, but complicates the fire refining of cathodes and creates a potential health hazard. The Bureau of Mines investigated methods to limit mercury extraction during gold ore leaching and to remove mercury from cyanide leach solu-tions. Mercury dissolution was reduced from 40 to 10 pct by decreasing NaCN concentration from 20 lb to 0.34 lb per ton of solution at a pH of <11. When 0.1 lb CaS per ton of ore was added to a leach slurry, mer-cury extraction was reduced from 27 to 0.4 pct. Less than 0.5 pct of the mercury was solubilized when <0.1 lb CaS per ton of are, along with lime and NaCN, was added to a simulated grinding circuit.

Jan 1, 1984

By David E. Van Dillen

INTRODUCTION Current design practices for deep tunnels make extensive use of plasticity solutions by Newmark (1970) and Hendron and Aiyer (1971). These solutions are applicable to a circular tunnel subjected to a hydrostatic stress state in a Mohr-Coulomb plastic medium. The role of rockbolts is introduced into these solutions as a uniform internal pressure equivalent to the yield stress of the rockbolt pattern. The application of these solutions is hampered by their inability to consider the biaxial nature of the in-situ stress field or any surcharged stress, such as due to blast loading. As a means of considering the biaxial stress field, designers have turned to relatively costly alternatives, such as the finite element method. The recent work of Detournay (1983) simultaneously provided two generalizations to the state of the art of the analysis of circular tunnels. Whereas the solution of Newmark applies to nondilatant Mohr-Coulomb materials, and that of Hendron and Aiyer applies to materials having associated flow rules, the solution of Detournay covers materials of arbitrary dilatancy. Secondly, Detournay&apos;s solution is valid for biaxial stress states, as long as the problem remains statically determinate (St. John, Detournay, and Fairhurst, 1984). The topic of this paper is an investigation of various alternatives for introducing the effects of rockbolts into simple tunnel design charts developed using Detournay&apos;s solution. The study was conducted using the BMINES finite element code, into which rockbolt elements have been added (St. John and Van Dillen, 1983). These rockbolt elements allow for plastic deformation of the bolt, bolt

Jan 1, 1984

By C. R. Edwards

"Equity Silver Mines Limited owns and operates an open pit silver 111ine located 37 km southeast of Houston in the Omineca District of British Columbia, Figure l. The property is approximately 300 km west of Prince George and 417 km east of the Port of Prince Rupert. This is the largest silver mine in Canada and one of the five largest silver producers in the western world.Equity is a subsidiary of Placer Development Limited, which owns 70 of Equity's issued and outstanding Common Shares. Placer was responsible for financing and developing the property and now provides general management and administrative services.All mining is by open pit methods, using three 1600 P&H shovels, eight 45 t Caterpillar and three 77 t Wabco trucks, three 40R rotary drills, two D8 dozers, one 9888 front-end loader and other ancillary equipment. We are now phasing out the Southern Tail pit and bringing the Main Zone into productior; see Figure 2.Comminution in the concentrator is achieved via primary, secondary, and tertiary crushers followed by rod and ball mills. The flotation circuit, with Southern Tail ore, produces a concentrate containing between 3 000 and 6 500 g of silver per tonne, 201 copper, and 25 g of gold per tonne. Running Main Zone ore, concentrate grades will decrease to about 4 500 g of silver per tonne, 17% copper, and 18 g of gold per tonne. Design milling capacity is 5 300 tpd, which is often exceeded.The flotation concentrate contains relatively high levels of antimony and arsenic. Because of these impurities Equity was unable to obtain economically acceptable long-term sales contracts for flotation concentrate. For this reason a leaching process was developed, and a plant designed, built and placed in operation. Due to the complex and unique technology involved, many start-up problems were encountered but by March 1983 the leach plant was considered ""fully operational."" This paper describes some of our progress and problems in bringing the Equity leach plant through its start-up period."

Jan 1, 1984

By D. R. Tesarik

To ensure the stability ofa tailings pond embankment, the height of the phreatic surface must be kept at or below a safe level. In this investigation, the Bureau of Mines analyzed various horizontal drain designs for tailings embankments to determine their effects on location of the phreatic surface. This report describes the investigation, and it includes 21 dimensionless graphs that can be used to estimate the drain spacing and length dimensions necessary to ensure the stability of embankments of various configurations. Analyses were based on the use of two computer codes, a three-dimensional finite-element code and a two-dimensional finite-difference code. The computer-generated results were compared with results obtained from a laboratory embankment model, other laboratory test results, and piezomet-ric data from two actual tailings embankments. Nearly the same phreatic surface locations were predicted using either of the computer codes. For one of the actual embankments studied, the predicted phreatic surface location was slightly higher than the measured location; for the other, the predicted location closely followed the actual surface trend. Phreatic surfaces of the laboratory model were slightly higher than the code-gener-ated locations, and the differences grew larger as drain length increased or drain spacing decreased.

Jan 1, 1984

By R. G. Robins

The processing of gold bearing sulphide minerals which contain arsenopyrite and various complex arsenic sulphides results in arsenic containing emissions and effluents which are suspect in relation to clean air and clean water standards. Removal of arsenic from gaseous emissions is briefly reviewed. The use of lime to stabilise aqueous residues as either calcium arsenate or calcium arsenite is shown to be inadequate for long term disposal since both compounds are converted into calcium carbonate due to the influence of carbon dioxide in the atmosphere. Mixed calcium arsenate-phosphate residues are similarly unstable, but present better stability than the straight calcium compounds. Alternative disposal methods are reviewed whereby the arsenic is converted to more stable compounds, such as barium arsenate, titanium (IV) arsenate, and arsenic sulphide.

Jan 1, 1984

By C. J. Newman, D. J. Kemp, R. M. Sweetin

"The smelter is described by area; feed preparation, continuous furnace line, gas handling and auxiliary systems, blister refining, Hazelett casting of thin anodes, and scrap remelting. Early smelter campaign data is presented and compared to design. Some modifications to the basic design of the furnaces and gas trains are indicated, with their respective impacts on improving smelter performance.Plant compactness, the use of jumbo tanks, and a highly automated electrode handling system are featured in the refinery description, with brief coverage of the liberator and slimes leaching sections. Early experience in refining thin regular Hazelett anodes, and submersible pump recovery of raw slimes are relayed, together with automatic stripping from titanium blanks.Refinery tonnages and operating parameters are given showing the relatively trouble-free attainment of refinery design performance.IntroductionPrevious papers and articles ( 1), (2) ,(3 ) have described the metallurgical facilities serving the copper-zinc-silver Kidd Creek orebody located near Timmins, Ontario. For convenience a brief review of their mid-1983 operating status is presented.The concentrator, originally designed for 9,000 short tons, was commissioned in late 1966. It can now comfortably process over 13,000 metric tonnes per day largely as a result of the addition of a fourth circuit in 1978."

Jan 1, 1984