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By M. Karmis

Surface subsidence has been recognized as an inevitable consequence of underground coal mining for several centuries. The damage resulting from this phenomenon has been witnessed in rural as well as in urban areas and ranges from simple land settlement to severe structural damage to buildings. Subsidence prevention is not feasible, at least under the existing technological and economic constraints of underground coal mining. Using a rational method of subsidence prediction, it has been demonstrated in many coalfields that subsidence control can be successfully practiced in order to reduce and accommodate subsidence within environmentally acceptable levels. This paper presents the development and testing of a subsidence model, based on the zone area method. This technique is a refined development of the influence functions and it is capable of investigating a mining plan of any shape, thus facilitating both longwall and room-and-pillar mining systems. More specifically, this study can be divided into two major efforts: (a) The development of the zone area model. This formulation was designed to accommodate the analysis of an optimum number of zones, over the area of interest, both accurately and efficiently. (b) The testing of the computer techniques with appropriate field measurements. In order to accomplish this, published as well as unpublished information was collected and analyzed according to a regionalized scheme. This procedure minimized differences in subsidence characteristics between the various coalfields and allowed a regional validation of the predictive capabilities of the model.

Jan 1, 1982

By Pedro Lilienfeld

The objective of this program was the development, design, and fabrication of six personal-sized completely self-contained dust monitors capable of real-time as well as time-averaged monitoring of the concentration of respirable particles in coal mines, in the range of 0.1 to 100 mg/m3. The operation of these monitors is based on light scattering and passive air sampling. The design stressed overall miniaturization, ruggedness, simplicity and versatility. These instruments incorporate a single-chip CMOS microprocessor to perform all signal processing, data display and storage, and timing functions. The overall dimensions of these devices are, approximately, 10 by 10 by 5 cm.

Jan 1, 1982

By Jorge Lema Patino

"The purpose of this paper is to determine the best techno-economic alternative for the treatment of tin ores, when comparing the various mining and metallurgical methods of preconcentration, concentration, volatilization (fuming) and up to the final stage of selling to the smelter. The study of the influence of the different parameters of cost, recovery and quoted prices has motivated the paper, which aims at determining the best process of ore treatment in terms of its techno-economic feasibility.Method of WorkOn the basis of head grades of 0.5, 0.75 and 1.0% tin, the following alternative methods of treatment are possible:1. Mining-Concentration-Smelting.2. Mining-Preconcentration-Fuming-Smelting.3. Mining-Concentration-Separation, with direct smelting and fuming/smelting of the two fractions produced.The calculations were carried out on the basis of existing information and publications concerning the various experimental recoveries in the operating mills of COMIBOL. In the case of concentrates containing less than 10% or more than 40% tin, extrapolation was required.The final grade of the tin concentrates and the gross weight of the concentrate were calculated on the basis of the estimated recovery curves. The costs of the preconcentration and the concentration stage s were determined per gross metric ton of material treated.The calculation of the cost of the smelting stage is similar for all the alternatives, the royalties and smelting charge varying with the grade of the final concentrate. In the fuming stage, a uniform recovery of 90% was taken in all cases so as to obtain a final concentrate grade of 65% tin, regardless of the head grade of the feed material.For the separation stage, the following considerations apply:a) Separation can be carried out by gravity separation or flotation methods.b) The cost of separation varies depending on the system used.c) The distribution of tin in the two fractions is 100% at this stage. In other words, there is no loss of tin during separation."

Jan 1, 1982

DR. BANOWSKY: Thank you very much. That was the shortest introduction that I have had lately, and I didn't have time to get my coat on. But I appreciated it, and I'm delighted to be here with an industry with which 1 feel strong affinity. At the University of Oklahoma we have an energy history. We are a little more currently involved in oil and gas, and those of you who know the history of our state would be aware we have an early coal development back really before the turn of the century in the southeast part of our state what we call Little Dixie. How many of you have spent anytime in Oklahoma or are from the state of Oklahoma? I'm not going to ask how many are from OSU or the University of Colorado. We did send you a football coach here from Oklahoma, and 1 see you have exchanged him. Several of you were only interested in the lobby in asking about our football team this year. 1 would like to go somewhere where we can talk about something besides football. I'm just trying to build a University that our football team can be proud of. We're going to be strong again. 1 can assure you. We've got the best football team money can buy. It's not quite as bad as the college president who called the coach in and said, "Coach we're in trouble, you're losing games and the alumni is very unhappy." "What can we do?" the president asked. The coach said, "Well the football team is flunking the admissions test. We can't get them in with the standard achievement and SAT tests." The president said, "What can we do?" The coach said, "Well the coaching staff has substituted for the American College Test the simple fill in the blank questionnaire." The president said, "Let's use it. We have got to get the team in." The first question was, Old MacDonald had a (-). And a couple of the big tackles were taking it and one of them said, "Hey, what did Old MacDonald have?" His friend said, "Stupid, Old MacDonald had a farm." "Well how do you spell farm?" He said, "Stupid, e i e i 0." Now the gentleman who met me at the registration line from Lakewood, Colorado, was asking me about one of our great big tackles; and he is doing well. We call him Doctor Death; he is also a wrestler and that gentleman said, "1 don't know how bright he is." 1 said, "He is bright enough for our academic tutoring that he is going to get through all right." So I'm delighted to see you and be here with my very dear friend, Carl Terzian. Carl and 1 were in Los Angeles together for 10 or 12 years when I was president of Pepperdine University. He and I are exactly the same age. Born in 1935 and 1 a month or two later in 1936. Fewer children were born in that period than in any other period of time in this century. For those of you who remember anything about that period, you will know why no one was having babies during that period. But Carl called and said, "Bill do you know where Vail, Colorado is?" Well when you live in Oklahoma, you learn where Colorado is in a hurry. 1 not only know this beautiful area, but have made too much of an investment here at a place called Beaver Creek. The real estate is cheap over there. 1 play regularly in the Gerald Ford Invitational Golf Tournament here. Hope you will visit Beaver Creek. It's just 10- 12 miles to the west. The sight of the 1976 winter olympics until the people of Colorado voted them out. And now Vail Associates and I are good Oklahoma families. Bass family, Harry Bass of course, many of you know this story, who is chairman of the Board of Vail Associates, is making quite an investment in that year-round resort area. Beautiful golf course now. You can come out and afford the green's fee and beautiful, beauti-

Jan 1, 1982

By Denis Yeung

In an effort to find better ways to dispose of potentially toxic material, the effect of longitudinal and lateral dispersion on the dilution of toxic fluids was investigated numerically and experimentally. Homogeneous and non- homogeneous tests were conducted to model this effect for surface mine backfills. These tests used a high-density zone [package] to bury undesirable material. The studies, utilizing inert tracers, showed that an increase in density in a soil will decrease the maximum level of tracer in the discharge. Within the range of experiments performed and using only natural materials, a 65 percent reduction in peak concentration was obtained.

Jan 1, 1982

By K. Y. Lo, R. S. C. Wai, R. K. Rowe, L. Tham

Laboratory tests for the determination of thermo-mechanical proper- ties of three rock types were performed at temperatures up to 400°C. Results showed that for the medium and coarse Granitic Gneisses, the coefficient of thermal expansion and Young's modulus are strongly temperature and temperature history dependent. A threshold temperature exists for each rock type above which material nonlinearity becomes important, and is associated with the progress of thermal cracking. Finite element computations were performed to illustrate the influence of material nonlinearity and boundary constraint on thermal stresses. Finally, a case history of thermal spalling was analyzed and it is shown that the results of analysis are consistent with field observations.

Jan 1, 1982

By Victor R. Spironello

The Bureau of Mines has conducted studies of the slags related to ferrous technology to evaluate experimentally acceptable substitutes for the auxiliary flux, mineral fluorspar, in steelmaking operations. Comparative heats were made in a 1/4-ton, pilot-scale, basic oxygen furnace (BOF) to evaluate a waste material known as "used potlining." Used pot lining is recovered from alumina reduction cells after its useful life and contains significant levels of fluorine and sodium in various compounds. This material in both lump and pelletized form provided adequately fluid slags, based on observations made during BOF operation. No adverse effects were found on furnace performance, metal and slag chemsitry, the strength of the steel produced, or the environment. Fluorine recovery in the slag was about the same as that obtained when using fluorspar, as were the losses to the scrubber water and solids. No difference was observed in furnace-refractory attack, as determined by the level of magnesia in the slag. The sodium recovered in the slag apparently also contributed to fluidity, since the fluorine input was at about two-thirds that of the fluorspar. Used potlining was determined experimentally to be a satisfactory substitute for fluorspar in basic oxygen steelmaking.

Jan 1, 1982

A new engine family has been developed by Caterpillar Tractor Co. for application in off-highway trucks. This family, the 3500 Series is available in three configurations, covering a 600-1200 kilowatt range. This engine series incorporates the latest in design technology, stringent functional specifications for servicing ease, fuel economy, reliability, optimum performance and parts interchangeability. TECHNICAL INTRODUCTION The 3500 Series Engine has been under development by Caterpillar for over eight years and has undergone extensive testing in the laboratory and in field prototype units. - The engine configuration is a 600 Vee in 8, 12, and 16 cylinder versions. - The intermittent power output per cylinder is 75 kilowatt (100 HP). Net power for off-highway trucks is 600-1200 kilowatt (800-1600 Hp) depending on engine configurations. The 3512 (3500 Series Engine 12 cylinder Vee configuration) was the first model of the 3500 Series released. These engines offer optimum user value in terms of product durability, reliability, fuel consumption, performance and installation flexibility. Additional features of 3500

Jan 1, 1982

By Parker GJ

The financing of smaller resource projects has proven to be a difficult problem for promoters and financiers alike as very often such projects have not met the requirements of available financing methods and promoters have equally found it difficult to establish credibility, management and technical ability with potential financing sources. Solutions to the dilemma in which many of these projects find themselves are not readily apparent but will need to be found if the full potential of Australia's resources is to be realised. INTRODUCTION The growth of so called project financing in its present form is normally considered to be a phenomenon of very recent times, however, paradoxically there are references to what could be called financing in the old testament. To confuse the issue further financing small resource projects may not, and very often are not undertaken on a project financing basis. It is therefore quite apparent that one should be completely clear on:

Jan 1, 1982

By Michael J. Sapko, Ellsworth R. Spencer, Frank J. Perzak

"The fire resistance of several mine conveyor belts is evaluated using a new belt-flammability apparatus developed by the U.S. Bureau of Mines. The test apparatus, experimental details and a calculated flammability index (FI) are described.The FI values are useful for ranking the fir e resistance of mine conveyor belts. Values are determined using parameters readily measured with thermocouples, high-temperature flow probes and a methane-oxygen torch, all of which are components of the Bureau's new test apparatus. The FI varies directly with the flame-spread rate and the rate of heat release during burning and varies inversely with the critical (minimum) ignitor energy output.The fire-resistance ranking of nine different belt types using this moderately scaled apparatus is compared with available full-scale data on belt fires. This comparison shows that the ranking based on the FI is consistent with the full-scale data.IntroductionFull-scale fire hazard evaluations of mine conveyor belts are not easily related to the properties usually measured in small-scale flammability tests. The inadequacy of small-scale belt fire tests has been demonstrated in works by Mitchell, Warner and Reinke.Mitchell and Warner showed that certain neoprene (NP) and polyvinyl chloride (PVC) belts, which had been approved by the Code of Federal Regulations 30 CFR 18.65, were nevertheless capable of propagating flame over their entire length when full-scale fire conditions were simulated. Comparable results were also observed by Reinke at the Tremonia experimental mine in Dortmund, West Germany, where all belts burned in full-scale tests even though they passed the small-scale tests. Only by reducing the severity of the full-scale test could these fire-resistant belts be grouped on a pass-fail basis."

Jan 1, 1982

By Bruce Bryant

Silver ore was discovered at Aspen in 1879, but the district did not reach full production until 1888 after lawsuits were settled and railroads furnished less expensive transportation to the outside world. The boom years were 1888-92; production declined thereafter. From the middle 1920's until 1950, the Midnight mine in the Richmond Hill district furnished most of the output in the Aspen quadrangle. Since 1950, little mining has been done at Aspen. The metals produced were silver, lead and zinc. Native silver dissolved from the sulfide ores was redeposited by waters circulating as deep as 300 m below the land surface, resulting in great secondary enrichment of many of the deposits. Over 100 million ounces of silver were produced in the Aspen quadrangle. Low-grade lead-zinc deposits remain between the old workings locally, and data available suggest that primary ore below levels mined is also of low grade. The ore occurs in the Mississippian Leadville Limestone and the lower part of the Pennsylvanian Belden Formation in sites that were made favorable for deposition by a number of stratigraphic and structural factors.

Jan 1, 1982

By Francis S. Kendorski

INTRODUCTION Caving offers the lowest cost per ton of any large-scale mining method, but its successful application demands an ore body that conforms to several rigid requirements. The deposit must be of wide areal extent, massive and not spotty in ore values, and insensitive to ore dilution. It must also be a rock mass that breaks up readily. There are only three active caving operations in the US-Climax, Henderson, and San Manuel-but caving methods have recently taken on new importance as deeper lower grade mineral occurrences and ore bodies are found. These deposits are too deep for surface min¬ing methods, and too low grade to support any type of underground mining except a bulk method such as caving. Announced discoveries or indications that may be amenable to caving include: Climax's Mt. Emmons molybdenum discovery in Colorado; Molycorp's Goat Hill molybdenum prospect in New Mexico; the Phelps Dodge molybdenum deposit in Beaver County, UT; Arizona copper occurrences such as Asarco's Sacaton, Hanna's Casa Grande, Noranda's Lakeshore, and Ken¬necott's Safford; Anaconda's suspected deep copper de¬posit in Butte, MT; Anaconda's Carr Fork, UT, deposit; and perhaps others. CAVABILITY'S ROLE IN FEASIBILITY STUDIES Caving is a system of underground mining which removes support from underneath an ore body. As a result, the rock mass fractures, fails, and flows vertically downward by gravity to be collected in previously ex¬cavated funnels. Types of ore that have been mined by caving include molybdenum, copper, iron, nickel, as¬bestos, and diamonds (Julin and Tobie, 1973). It is primarily a large-scale method, with production rates of more than 45 300 t/d (50,000 stpd) having been achieved. However, the initial capital investment before return is very high, often in the hundreds of millions of dollars. The cavability of an ore body or mineral occurrence is a critical item in the feasibility study of a proposed mine, not only from the point of overall minability, but from the point of impact on other costs such as blasting, loading, hauling, crushing, and grade recovered. Aside from the often-asked question of, "Will it or will it not cave?" the real questions are, "Can we afford to make it cave, carry the rock away, and extract the mineral?" The last is not a topic of this chapter, but the first two are. The cavability of an ore deposit or mineral occur¬rence is based on many things, but clearly, if a large enough area is undermined, any rock mass will cave. The result could be a violent collapse as occurred at Urad, CO (Kendrick, 1970), or perhaps the rock mass will cave beyond the ore boundary. Another unfavor¬able result could be ore blocks that are too large for the equipment and orepasses to handle without considerable secondary blasting. Weak rock with numerous fractures may produce a very fine ore when it caves, resulting in dilution and ground control problems. DETERMINING STRUCTURAL DOMAINS It has long been recognized that the geologic nature of an ore body is important to cavability (King, 1946). Such items as weak rock material, intensity of fractur¬ing, and severity of faulting all contribute to the success of a caving operation, and information regarding these is required as a minimum for the cavability determination. In practice, the rock mass-defined as the blocks of intact rock together with the intervening fractures, joints, faults, bedding planes, and other discontinuities-that contains the ore body, as well as the surrounding and overlying rock, must be examined in a systematic and detailed fashion. Surficial geology maps must be pre¬pared, exploration holes drilled, and core logged for en¬gineering information. The fracturing of the rock mass must be studied to ascertain the three-dimensional dis¬tribution of fractures and their characteristics, and faults must be located and described. The strength and other mechanical properties of the rock material, the fracture surfaces, and the fault filling materials must be tested and reported for later use by designers and planners. With this basic information and an understanding of the geologic setting, the rock mass can be divided into one or more structural domains which tend to behave similarly in response to engineering activities (Robertson and Piteau, 1970). One must keep in mind that the determination of the structural domains goes beyond the geologic units present. Several lithologic units may be lumped together, while a single lithologic unit can be divided into multiple domains. Major faults often form their own domain, and the direction of engineering ac¬tivity-for example, cave advance to the north rather than the south-may alter rock mass behavior, resulting in different domains. As an example of the detailed rock fracture map¬ping required for such studies, the structural domain determinations at the Climax mine (Kendorski, 1973) are shown in Fig. 1. The circles are Schmidt equal area projections of the three-dimensional attitudes of frac¬tures (Ramsay, 1967) mapped in detail at various rock exposures. The attitude of fractures is important to the cavability determination since it dictates the directional behavior of the rock mass as it fails, and determines the effectiveness of arching, keying, and rock block inter¬locking. Low-angle fractures must be present to allow movement of the rock in the vertical direction during undermining (Mahtab and Dixon, 1976); if low-angle planes of weakness are absent, the rock mass may arch with a keystone effect, rather than moving vertically downward.

Jan 1, 1982

By R. H. Lien

The Bureau of Mines developed a flue gas desulfurization process as part of its goal of minimizing the undesirable environmental impacts associated with energy and mineral-processing plants. The modified citrate process involves absorption of sulfur dioxide (S02) in a buffered citric acid solution. The S02-loaded solution is regenerated by countercurrent contact with steam in a packed tower. The wet S02 product is then dried and can be liquefied or further processed to make sulfuric acid. Test data from process investigation unit studies are presented. Material balances, flowsheets, and cost estimates are given for recovering S02 from copper smelter reverberatory gas, lead smelter sintering machine tail gas, and power-plant stack gas. Operating cost estimates show the process will add $0.04 per pound of copper, $0.01 per pound of lead, and $0.015 per kwhr to the cost of the respective operations. These costs could be substantially reduced if a source of waste heat was avail-able to provide the process steam requirements.

Jan 1, 1982

By John R. Burger

Industrial mineral mines that have recently been opened, or soon will be opened in the northern circumpacific will produce potash in Canada, Mexico, and Thailand; phosphate in the US, Mexico, and Colombia; soda ash in the US; and chromite in the US and the Philippines.

Jan 1, 1982

By Dean S. Rogers

"In February 1980, Dome Mines Limited announced a $50 million expansion program which would result in a 50% increase in mill capacity from the present 1,815 tonnes per day to an eventual production rate of 2, 720 tonnes per day in the year 1984. As an integral and necessary part of this planned expansion, a new vertical production shaft, No. 8 Shaft, would be sunk from surface to a depth of 1,645 metres.Throughout the seventy-year history of mining at the Dome, gold has been found in a number of different rock types and in association with a number of different structural settings. However, the key to successfully locating ore deposits lies in the recognition of the favourable environments in which they generally occur. First and foremost, the exercise of locating the No. 8 shaft became an exercise in geological deduction based on the projection of these favourable lithologic environments.In November 1980, after detailed engineering work was completed, the total cost of the project was estimated at $75.5 million 1980 dollars or $91 million dollars allowing for inflation over a four-year construction period. These estimates include the shaft, significant replacement and alterations to the milling process, and an upgrading of the plant."

Jan 1, 1982

By Irving Hauser

The determination of new ways to cut costs in then times of economic uncertainty is essential in running a successful business. Arco Petroleum Products Company a Division of Atlantic Richfield Company recognized an opportunity for a substantial cast savings in transporting calcined petroleum coke to market by simply building an economical port facility at a location that would enable them to drastically cut their normal rail haulage distance.

Jan 1, 1982

By M. Churchill, V. R. Degner

"Over the past two decades, declining ore body grades, increased operating costs and increased construction costs have provided an incentive for the development of progressively larger flotation machines. As a consequence, the 60 to 100 cubic foot flotation machine of the l950's and l960's is being rapidly replaced by large volume machines, with a resulting improvement in the flotation machine specific capacity (TPH processed per square foot floor space), specific power (HP per TPH processed) and process control simplicity. The recent development, and satisfactory plant evaluation, of the WEMCO 1000 cubic foot flotation machine provides the means by which further economic and operating advantages may be incorporated in high tonnage mill applications.The systematic development of the large 1000 cubic foot flotation machine, and its subsequent performance evaluation in beneficiating metalliferous ores (copper, zinc and iron) will be reviewed in this paper and recently completed plant results will also be provided."

Jan 1, 1982

By Van Heuzen JA

The extensive deposits of brown coal in the Latrobe Valley form the major solid fuel resource in Victoria and are the energy source for most of the State's power generation. This paper describes the coalfield resources allocated for electricity generation and a potential sequential develop- ment of these areas in future years to supply future power stations.

Jan 1, 1982

Large Off Highway Trucks operated in this country are generally of Diesel Electric Drive, this system tends to employ the familiar Electric Wheel. A number of fleets now employ the Traction Motor System as an alternative. An investigation is made of the operation of two such fleets. A brief description is given defining the components and their basic functions in each system. Available life history is presented and system reliability, maintainability and operator reaction is examined. Trlmnnnr rpm rn~r In the past large Off Highway Trucks operated in this country, that is those greater than say 120 tons, have tended to be driven by a Diesel Electric traction system. Although manufacturers are now offering mechanical or mechanical/hydraulic drives in the larger machines comments will be restricted to examining the Diesel Electric System. Since commencing operations in the mid 1960 period Hamersley Iron has made use of the diesel electric drive system using the familiar Electric Wheel. A departure was made at Tom Price with the purchase of the Wabco 3200 Series Trucks. These 235 ton capacity units employed a dual rear axle system with externally mounted motors. In 1976 a

Jan 1, 1982

The subject of heat sources in deep hard rock mines, the limitation of forced ventilation to cope with these heat loads and the sizing of refrigeration plants to boost the cooling effect of the ventilation air are discussed. The development of plant selection criteria and operating experience at North Broken Hill Limited is outlined. Future options for North Broken Hill Limited and like deep mines are summarised.

Jan 1, 1982