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By W. D. Eddy

Topaz is a fluorine-bearing aluminosilicate mineral of the kyanite-sillimanite group. The formula has been given as Al2SiO4(F,OH)2, [Al(F, OH)]2SiO4, or 2Al2O3?2Al(F, OH)3SiO2. Topaz is generally considered a semiprecious-to-precious gem mineral, but it is a fairly common minor constituent of granites. In 1937 the U.s. Geological Survey reported an occurrence of massive topaz in the 3 Brewer gold mine, Chesterfield County, S.C. Over the next 8 years considerable research was done on topaz to establish its properties and to determine possible end uses The first reported shipment of ore was in 1939 Peak production was reached in 194412, and output then began declining until the mine closed in 194913? During World War II topaz was used in refractories, as a flux in steel mills, and in the manufacture of borosilicate glass 14. The main advantage of using topaz over kyanite and sillimanite in refractory use was that calcined topaz converted to over 95 percent mullite (3A1203 .2Si02) while calcined kyanite or sillimanite contained only 88 percent mullite15. However, a major draw-back to utilization of topaz is the evolution of fluorides during calcination. In 1973 the Geological Survey reported that topaz occurred in probable commercial quantities in at least two domestic locationsl6: the Brewer area of South Carolina and a location in Colorado. The literature also indicated that progress had been made in controlling fluorine-bearing fumes. This research has progressed to the state where valuable fluorine compounds are being recovered on a commercial scale 17. Thus, a major obstacle to utilization of topaz appears to have been resolved. The Bureau of Mines under its program of advancing minerals technology initiated a project to study techniques for the concentration of topaz from disseminated materials. The objective of the study was to determine those techniques that would be used to produce topaz concentrates that could be utilized as a source of fluorine and mullite.

Jan 1, 1977

By Ernest M. Spokes

Maximum fan efficiency can only be obtained when the fan has the correct combination of size, speed, and blade setting to provide the required flow of air against the mine resistance. As the mine grows older, resistance decreases unless old workings flow is restricted, and new combinations of speed and blade setting or different fan sizes may provide greater economy.

Jan 1, 1977

By Edmund H. Warner

Any city dweller who has walked alone along a remote mine passageway has to be impressed by the eerie silence - the total absence of noise except for ones own breathing and scuffing of boots on the bottom. An underground mine can have tremendous contrasts, from complete silence to the ear piercing clatter of percussion drills working on the mine roof. Noise in underground mining machines is both useful and detrimental. Without characteristic noises that are recognizable to miners, operators would have a more difficult job operating their machines. Noise serves as a warning of approaching machinery, and changes in noise give indication that breakdowns may occur. But excessive noise is a health hazard. In recognition of this fact, our Congress included noise exposure as a part of the "Coal Mine Health and Safety Act of 1969". As Fig. 1 indicates, allowable noise exposure is established by specifying a time duration permitted at different noise levels. This is the well known "Walsh-Healey" criteria which governs noise exposure in many industries.

Jan 1, 1977

By Y. S. Kim, A. Bailey

A feasibility seismic refraction and reflection field survey was conducted at the U. S. Borax Company open-pit mine, Boron, California by the writers during the weekend of March 13 and 14, 1976. This field survey was carried out as a preliminary investigation primarily for the purpose of evaluating and establishing the ability of such geophysical techniques to locate and outline the subsurface openings of the old room-and-pillar mining under the present open-pit. The value of such knowledge about the old underground workings is directly related to the safe and economical operation of the open-pit mine for the company. Although mine maps of the old underground workings are available at the mine, the extent of roof and wall cavings and the present condition of the old underground openings are unknown. Owen and Suhler (2) are the first investigators who used electromagnetic methods, Pulse-Echo System, and electric resistivity measurement to solve the problem without success. A few years later, Herzig and Owen (1) attempted to solve the problem with application of earth resistivity measurement method with unfavorable results. The U. S. Borax Company carried out an extensive study for slope failure problems of the open-pit with application of dipmeter measurements. However, the slope stability study was not correlated to the old underground openings lying under the present open-pit (3).

Jan 1, 1977

By W. Joseph Schlitt

The use of plate and frame filter presses for dewatering cement copper at Kennecott' s Bingham Canyon precipitation plant is described. The dewatering process begins by periodically flushing a dilute copper slurry from cone precipitators to a rake thickener. The thickener underflows intermittently to an agitated surge tank which feeds the filter presses with a relatively constant slurry containing 10 to 20% solids. The presses operate with a three-stage cycle; loading, air blowing and discharging. Exothermic reactions occur during the air blow which cause actual drying as well as promoting dewatering via simple filtration. At the completion of the air blow, the presses are discharged onto a conveyor belt which transfers material to the load-out building for shipment to the smelter. An extended investigation was undertaken to relate moisture content in the filter cake to maximum press temperature, acidification of press feed, percent solids in the feed, and percent insol in the copper. Of these, press tempera¬ture and feed pH (3. 5 to 1. 0) have the greatest impact on drying. Because the discharged filter cake is hot and continues to undergo exothermic oxidation, significant drying occurs during subsequent handling so that a product containing 8 to 14% moisture is delivered to the smelter.

Jan 1, 1977

By Ben L. Seegmiller

INTRODUCTION Site characterization using oriented borehole core is the subject of this paper. Borehole core is a standard source of data for rock mechanics investigations. Oriented borehole core provides data whereby the geometric orientation of various geologic discontinuities (faults, joints, bedding, etc.) may be determined. The orientation and strength characteristics of discontinuities are important in many engineering investigations and in particular, in slope stability analyses. In heavily vegetated or soil covered situations, oriented borehole core may provide the only means of assessing the subsurface planes of weakness which characterize the site. The purpose of this paper is to briefly describe various methods or orienting core, core characteristics which may be logged and the methods of processing and using the data for site characterization.

Jan 1, 1977

By Corale L. Brierley

The effect of hydrogen peroxide (H2O2) on growth and respiration of Thiobacillus, thiooxidans, and Thiobacillus ferrooxidans, organisms involved in acid leaching of copper sulfide minerals and uranium oxides, was examined. Oxygen uptake and growth by T. thiooxidans were inhibited after contact with 0.82 mM H2O2. Inhibition of oxygen uptake by T. ferrooxidans occurred at 8.24 mM H2O2, and growth was inhibited after 6 hours exposure to 2.06 mM H2O2. Higher concentrations of H2O2 can be used without detriment to thiobacilli if it is dissipated prior to reaching the oxidation pond or dump surface. INTRODUCTION In recent years, hydrometallurgical processes for recovery of metal values from low-grade ore minerals have played an increasingly important role. Dump leaching of low-grade copper waste materials in the western United States now yields 11.5% of the total U. S. copper production. Although scavenger operations in uranium leaching have been successful, the state-of-the-art of in-situ

Jan 1, 1977

By D. G. Ball

Other than being used to convey fill material for the gob stowage or building of ribside packs on advancing longwell faces, pneumatic conveying has not been used for the transport of materials on a large scale in mining operations. The technique is extensively used in the wood products industry for conveying wood chips, limestone and other ingredients for the manufacture of paper, for the transfer from railcars, barges or ships to silos or stockpiles and further transfer into the pulp mills. This method of material transfer has the distinct advantage of transporting suitable material over horizontal and vertical distances within the same system. In considering material associated with mining, this includes, ore, coal and rock up to 4 inch cubed size, throughputs of 200 tons per hour over horizontal distances of 3000 feet or vertical lifts of 2000 feet. In recent years tests have been carried out to determine the physical and economic limitations of pneumatic hoisting, the results of which have led to the installation of two fully productive coal hoisting systems at mines of the National Coal Board in Great Britain. The equipment used for the pneumatic hoisting of coal or waste rock is described in this paper, together with a brief history of the tests which led up to the installation of the two hoisting systems in Great Britain.

Jan 1, 1977

By Charles H. Greene

This paper will describe briefly the steps taken in the development of a Central Florida phosphate ore deposit from acquisition to mining. Further, the design and early operation of the mining and beneficiation facilities will be depicted. During the 1950's, with confidence in the continually increasing requirement for phosphate fertilizer materials essential for producing food, I'. R. Grace & Cc acquired the Hookers Prairie tract containing approximately 45 million metric tons o. (50 million short ton~ of potential phosphate rock product. In 1973, at a point when the Grace captive need for rock was being greatly enlarged by a planned doubling of its Bartow phosphate chemicals plant capacity, the decision was made to expand existing phosphate rock production by building a new mine and plant. The initial annual capacity was to be 2.3 million tons (2.5 million st); however, subsequent investigation pointed to a higher than estimated dragline operating factor 'and the forecast of annual capacity was set at 2.5 million tons (2.8 million st).

Jan 1, 1977

By Kenneth L. Maloney

Ten small and intermediate-sized [11 GJ/hr to 264 GJ/hr (10,000 lb/hr steam to 250,000 lb/hr steam)] coal-fired boilers in the upper Midwest have each been tested on both a bituminous eastern coal and a subbituminous western coal. The purpose of this study was to determine the feasibility of substituting western subbituminous coal for eastern bituminous coal as a means of reducing the SO x emissions from this class of boiler and to demonstrate the feasibility of greatly expanded western coal utilization as a means of reducing the use of oil and gas. The scope of this study was such that the representative boiler types were tested on both eastern and western coal for a period of time sufficient to completely characterize their individual emission and operational characteristics.

Jan 1, 1977

By Haydn H. Murray

Kaolin is defined and described as an industrial mineral. In addition the types of deposits -primary and secondary are defined and the genesis of kaolin from feldspars and other minerals discussed. The major deposits of the world found in the United States, Great Britain, Brazil, and Czechoslovakia are described along with many of the minor kaolin deposits. Four areas which have very large deposits of kaolin could, with technological breakthroughs to reduce viscosity significantly, become important factors in supplying the world markets which are increasing year by year.

Jan 1, 1977

By D. D. Potter

ABSTRACT OF ORAL PRESENTATION Extraordinary conditions are often encountered when designing large blasts for in situ mining methods and spatial or innovation techniques are sometimes required. Some of the considerations in designing these large blasts will be discussed with emphasis on those factors that concern powder factor, rock movement and fragmentation. Sources of basic data will be described, along with some of the methods for obtaining these data.

Jan 1, 1977

By John B. Gustavson

This paper describes a case history of geochemical prospecting. An area of known mineralization was available for an orientation survey which led to the selection of elements and criteria for a reconnaissance survey in the area offsetting the known mineralization. Certain anomalies were found which were then made subject of confirmation sampling and of rock geochemical investigations. Inasmuch as the geochemical prospecting technique specifically led to a detailed area which now serves as a target for drilling and other exploration efforts, the geochemical prospecting part of the program is considered successfully concluded and, therefore, reported on here. Whether the target area will turn out to host the deposit or not is, of course, of utmost importance to the Company, but is of less importance to this paper. We will describe the concepts, the planning, the execution, the analysis and the interpretation of this typical geochemical prospecting case. A number of people on the staff of International Oil & Gas, Inc. have participated in this prospect, as have students from Southeast Missouri State University and their professor, Gary M. Lowell. In addition, the Missouri Geological Survey has been most helpful with records and letters on the century-old prospecting and mining in the general area. Many valuable discussions have also been held with geologists from the industry who, from time to time, have visited the area, examined the property and reviewed the status of the project. The support and interest from all these parties has made it possible to pursue and expand this exploration concept from one of being just "more of the same kind" to the most chal-1enging and exciting with which this author has ever been involved, namely the prospect for tin porphyry deposits in the mid-continent United States.

Jan 1, 1977

By William D. Mayercheck

The introduction of continuous mining machines in the late 1940's prompted the mining industry to reassess shuttle car batch-type haulage. Between place changes, the continuous miner could cut and load coal on a nearly continuous basis, but after loading a shuttle car, the high-capacity machine had to wait until the second shuttle car came inby and spotted itself under the miner tail boom. Thus, the wait-for-shuttle-car delay periods became the new bottleneck for increased coal production from the mine section. Recent studies have shown that nearly 25 pct of the continuous miner cycle time is consumed by delays in the haulage system, usually waiting for shuttle cars. Computer simulations of a face operation indicate that up to a 45 pct increase in coal production may be realized through the use of a continuous haulage system, assuming of course that the outby haulage system can handle this increased capacity. Coincidently, there are recent claims by some mines using continuous face haulage of a production increase of 45 pct compared with shuttle car haulage. These documented production records, computer simulations, and common sense indicate the potential of continuous face haulage in underground coal. The late 1960's and early 1970's saw several mining machinery manufacturers market mobile bridge carrier and piggyback bridge conveyor continuous haulage systems for use in underground coal mines. These systems have shown limited potential in some mines and outstanding success in others. It appears that no one system can be universally applicable to all underground mining conditions; thus, the Bureau of Mines has conducted extensive research over the last few years to investigate different types of continuous haulage systems for use in high and low coal seams that will advance the state of the art.

Jan 1, 1977

There are presently in use many grinding mill control schemes and concepts. This paper presents one operating method of controlling the particle size of the cyclone overflows for proper metallurgical results and controlling the level of the cyclone feed sump and new feed rate to obtain lowest unit cost of finished (ground) material which is usually at the maximum grinding mill throughput. This system stresses simplicity of field instrumentation and control strategy. Both of these factors lead to better operator understanding and acceptance. The low capital investment of this system also makes it more attractive at the Buick Concentrator when compared to other more complicated systems utilizing mass flow measurement and a computer to calculate circulating load and infer particle size. Furthermore, it has the advantage of utilizing an actual measurement for control, rather than a difficult-to-maintain inferred value. There are several reasons for maximizing mill throughput at Buick. The milling rate before automatic control was too low when compared to mill throughput increases planned for the future. Through this new operating system, it appears Buick will not have to make major changes of mill motors and speeds to meet the increased? production rate. Also, since power costs continue to escalate, it is desirable to maximize the throughput to the grinding circuit and reduce overgrinding to achieve a reduction in power cost per ton of ore milled. Presently, 45% of the concentrators' total power is consumed in this grinding circuit.

Jan 1, 1977

By J. E. Carr

A bewildering number of continuous thickeners and clarifiers are used in mineral industries and other heavy industries. General types are: 1. Conventional Thickeners (Fig. 1). 2. Thickeners with Flocculating Feedwells (Fig. 2). 3. Solids Contactors (Fig. 2). 4. Tray Thickeners (Fig. 3). 5. Lamellas (Fig. 4). 6. Conventional Thickeners with Lamellas 7. High Flow, Fluid Bed Thickeners (Fig. 5). These units must be adapted to varied applications. They must provide operating flexibility to meet process needs. Such factors multiply the decisions which must be made prior to the selection of a thickener. The seven types of thickeners listed above, with their variations, share design concepts which limit their application and which can be used to evaluate their performance. Some of these are listed: 1. Feed velocities must be limited and/or controlled. 2. Natural or reagent flocculation is necessary. 3. Horizontal settling area is the basis for capacity. 4. Overflow velocities must be limited and/or controlled. 5. A controlled underflow is necessary. Applying these needs to the basic process concepts is thickener selection. The basic function of a thickener in the minerals industry is the separation of a thickened sludge containing fine solids from water. To this primary separation function are frequently added others to give a list as follows:

Jan 1, 1977

By George J. Conroy

Results of a long-term program of electrical parameter measurement in under-ground coal mine working sections, performed by The Pennsylvania State University under U. S. Bureau of Mines sponsorship, are utilized as the basis for an analysis of the electrical energy requirements during operation. A model section is hypothesized, developed from the average or most representative characteristics as determined from tabulations of the measurements. Performance factors of the model section's machine complement are then analyzed, particularly with regard to the energy required per ton of raw coal cut and delivered from the section. Results are given in kilowatt-hours per ton.

Jan 1, 1977

By Sam H. Patterson

This paper is concerned primarily with the kaolin deposits extending northwestward from Macon, Ga., which is in the western part of the Irwinton district (fig. 1). These deposits are in a belt of kaolin districts extending along the inner edge of the Coastal Plain from the Aiken district, S. C., southwestward to the vicinity of Macon, a distance of 150 miles (250 km). Large kaolin deposits associated with bauxite also occur in an extension of this belt southwestward from Macon as far as the Eufaula district, Ala., a distance of about 130 miles (208 km). The belt splits away from the inner edge of the Coastal Plain in a southwesterly direction from Macon; the Eufaula district is approximately 50 miles (80 km) south of the contact of Coastal Plain sedimentary rocks with much older crystalline rocks. Structure The strata of Cretaceous and Tertiary age containing the kaolin deposits all dip gently seaward irom the landward edge of the sedimentary rocks. The dip of the Cretaceous strata is about 25 feet per mile (4.9 m per km). The dip of Tertiary strata is about 15 feet per mile (2.1 m per km). In places, the Tertiary strata overlap the older sedimentary beds and rest directly on the crystalline rocks. Faults having a few feet of displacement have been observed in several mines, but no major faulting is known in the area.

Jan 1, 1977

By LeRoy D. Loy

Would you believe me if I told you the constant battle between Government regulatory agencies and industry could be won by both sides? No, I'm not crazy, nor have I been soaking up any of that fine Kentucky whitelightning. But I have recently been a participant in a battle where both sides won. Actually, I'm using the term "battle" loosely because, in reality, it wasn't a battle at all - despite the fact that all the ingredients were there for a monumental struggle; i.e.. government, industry, special interest groups and a controversial issue - the development of effluent limitations. I'd like to tell you about it. Historically, on one side of the battle, government has always been ac¬cused of adopting regulations with limited evaluation of existing technologies; and then with seemingly no regard for the economic consequences. On the other side, industry gets punished by government's harsh actions because of their past "do-nothing" attitude toward pollution control. Recently, this battle seems to be losing steam, because both government and industry are beginning to realize that, ultimately, they both will lose. Even more important is the fact that both sides are, or should be, working for industrial expansion compatible with environmental protection.

Jan 1, 1977

By John W. Wilson

Every operation connected with the working of a deep-level mine has, to a greater or lesser extent, a direct bearing on the costs of production, and hence, profitability of the mine. If adequate mine planning is not done in the early stages in the life of a mine, considerable expenditure can result from the cost of maintaining mine service tunnels, production delays in stopes caused by poor strata control, distortion of fittings in hoisting shafts, rockbursts and so on. In fact, the optimum profitability of a deep-level, hard-rock mine can only be achieved if the layout of the shaft systems, ore passes, tunnels, stoping areas and other underground excavations are designed to withstand or accommodate the rock stress conditions that will be created by mining operations. In South Africa where the deepest mines in the world are located, access to the underground workings of most deep-level gold mines is via vertical shaft systems and a network of tunnels connecting the shaft systems to the stoping areas. In current practice, there are two basic methods of extracting the gold-bearing reef,* namely, the scattered stoping method and the longwall stoping method. The choice of the stoping method is governed largely by the anticipated gold distribution and payability of the reef in the area, the geological conditions, the degree and complexity of faulting and dyke intrusions, the depth at which the gold-bearing reef is to be mined and the inclination and width of the reef. The longwall system was first introduced at the East 717 Rand Proprietary Mines Limited in 1942 in an effort to combat the rockburst hazard which appeared to increase with increase in depth. This mining method became standard practice on that mine for stoping operations 700 ft. below the surface. Since that date, several deep mines on the Central Rand, East Rand and West Wits gold mining areas have adopted this method.

Jan 1, 1977