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By James C. Church

The Bureau of Mines devised and demonstrated a portable linear cutting tester that directly measures and records the in situ cutting forces required of continuous-mining machine picks to it coal in underground mines. It requires only two operators to transport and operate the tester, which can be assembled and operated through a complete test cycle within a single mine work shift. This report reviews the factors considered in the design and development of the tester and the results of its system verification testing at coal mine sites.

Jan 1, 1985

By W Russell

The Hercudet Non-Electric Delay Blasting Cap System provides a means of achieving greater flexibility in the use of delays, using totally enclosed gas detonation circuits which eliminate the concussive effects of detonating cord trunklines in the confinement of access tunnels beneath pillars of ore. This is an account of one such pillar blast.

Jan 1, 1985

By Paul Soros

The rationale for innovations in two directions is identified: raising capital and annual throughput, in order to avoid the cost of constructing and operating an additional system and to reduce the capital cost of pits and tunnels, applicable to installations of any capacity. Cast histories cover railroad unloading of bottom dump cars, rotary dumping of random cars, with and without indexer, and unit trains as well as truck unloading of multiple grades of coal.

Jan 1, 1985

By Robert M. Valentine, Randall L. Lentell

Interpretive geotechnical investigations were performed for the construction of approximately 15,250 m (50,000 ft) of wastewater interceptor tunnels in Austin, Texas. Subsurface materials consist of claystone (or clay shale), siltstone, altered volcanic tuffs, chalk and limestone. Special conditions include multiple crossings of Onion Creek with cover ranging from about 1/2 to 3 m (2 to 10 ft.), and the potential for mixed-face conditions consisting of water-bearing gravels overlying clay shale or siltstone. The methods and results of the geotechnical investigations are discussed and the inferred construction conditions are compared to those encountered during tunneling. A suggested format is presented for interpretive geotechnical reports for underground construction projects.

Jan 1, 1985

By Jack Mantel

The goal of this 42-month contract was to increase safety in low-seam underground coal mines through development and in-mine evaluation of a temporary roof support system for roof drills and floor-riding operator compartments for a loader and shuttle car. The program was performed in three phases. During Phase I, state-of-the-art canopy technology was investigated, and preliminary design and mock-up evaluations were performed for temporary roof supports for single-and dual-boom bolters and for transverse-mounted floor-riding canopies for a shuttle car and coal loading machine. The shuttle car and loader canopies were approved for further development, and the design, fabrication, testing, and certification were completed in Phase II. In Phase III, the Bureau of Mines furnished an FMC 6L shuttle car fur use in the evaluation of the canopy for 45 shifts. The shuttle car canopy was evaluated at Virginia Crews Coal Company in West Virginia. Efforts to secure an evaluation site for the loader canopy were unsuccessful. The loader canopy was shipped to Bruceton for possible future evaluation.

Jan 1, 1985

The objectives of this research were to examine and to laboratory performance of several brands of rigid urethane een brands, produced by 13 manufacturers, were examined. was performed in a laboratory under controlled conditions. document the foam. Eight-All testing Preliminary laboratory tests included flame spread evaluations, flame penetration, ignition temperatures, air permeability, and adhesion. Having established arbitrary cutoff values, the original 18 candidates were narrowed to 8. More specialized tests followed. The effects of water immersion and dry aging on flame spread performance and other physical properties were then examined. This Bureau of Mines report was written to provide information for those concerned with using rigid urethane foam as a sealant. Its intent is to describe the various laboratory evaluations performed and to delineate the performance of each candidate. This report neither promotes nor discourages the use of rigid urethane foams. It presents results that will enable those responsible for using or enforcing the use of rigid urethane foams in underground mines to make informed decisions.

Jan 1, 1985

By Edward S. Plotkin, Thames F. Peyton, Gary A. Almeraris

This paper describes high speed tunneling by drilling and blasting in a heavily populated urban area. The project consists primarily of mining 2500 m (8237 ft.) of tunnel through mica schist, excavating three shafts approximately 200 m (650 ft.) each and concreting lining 5300 m (17,400 ft.) of 7.34 m (24 ft.) inside diameter tunnel. The techniques developed and equipment utilized to ensure a high rate of tunneling advance are described. Extensive planning and good communications were especially essential in maintaining production on this project since tunnel mining, tunnel concreting, and shaft excavation all proceeded simultaneously from one common work shaft and a single heading.

Jan 1, 1985

By Noel N. Moebs

The Bureau of Mines studied the feasibility of water diversion and overburden dewatering for underground coal mines in the Appalachian region. All relevant published literature pertaining to the occurrence and control of surface and ground water in underground coal mines was reviewed, and the impacts of mine water with respect to health and safety, production, environment, and costs were assessed and are described in this report. The report also identifies the sources of water inflow into underground coal mines, and gives a summary description and evaluation of techniques that can be used to reduce the amount of water entering these mines. Engineering practices currently used by operating coal mines in the Appalachian region to prevent the movement of ground and surface water into active coal workings were reviewed and are summarized. Major emphasis has been placed on the identification of geologic and hydrologic conditions of the site, the water control methods used, and an evaluation of their technical and cost effectiveness.

Jan 1, 1985

By Steinbrucker G

Improvements in mining by the application of electronics necessitates analy-sis of the objectives and problems. A detailed analysis has shown that increased tunel-ling performance is one of the most important objectives. In mining, the environmental conditions for machines, their handling and servicing are very hard. Therefore a health monitoring system for tunnelling machines in hazardous areas has been developed. This system measures operational parameters, such as-flow, pressure, temperature, etc., de-rives forecasts of possible failures from these values, and assists maintenance person-nel. Important data are transmitted to a surface computer via telephone cables. Health monitoring is based on the cognition that slow deterioration of characteristic parame-ters, e.g. fluid loss, are symptoms of wear. Sudden changes of machine parameters indi-cate sudden destruction. Computer technology is very advanced, but transducer technolo-gy has not,been able to keep pace. Filling the yawning gap in the mining industry is a challenge to technology and requires special techniques. Machine monitoring and automa-tion in underground mining is still in its infancy. A lqt of development and research work is still necessary. The risks are great-The expected benefit due to increased min-ing performance (up to 5 %) justifies the risks in development.

Jan 1, 1985

By K. C. Dean

Discarded automobiles represent the greatest single resource of reusable metals, plastics, and rubber in the United States. This report presents results of Bureau of Mines research, conducted from 1965 to 1983, on separating and recovering useful materials from the scrapped hulks, using old and new metallurgical techniques combined with standard scrapyard methods. The Bureau determined the materials composition of three composite cars designated as circa 1960, mid-1970's, and early 1980's, and used these cars to study smokeless incineration and hand-sorting techniques. In studies on treating rejects from automobile shredders, the Bureau designed a process that included air classification, water elutriation, magnetic separation, handpicking, and heavy-medium separation, and also investigated cryogenics and liquation. Complete recovery of cop-per and other metals was economically made by hand and tool dismantling, leaching, or selective melting of starters and generators. Techniques are also discussed for plastic recovery and waste tire treatment.

Jan 1, 1985

By Fred A. Breu, Jerome C. Neyer, James F. Peters, John W. Critchfield

This paper describes experiences with methane and hydrogen sulfide gas encountered during design and construction of a sewer tunnel in rock, in Rochester, N.Y. Design explorations are summarized, including geologic setting, measurements of gasses in test borings, laboratory analyses of gas samples, and measurements of gas pressure and flow rates from a sealed borehole. Contract specifications regarding gas are outlined. Results of the Contractor's additional explorations and testing are presented, along with a description of selected equipment and provisions for ventilation and degassification.

Jan 1, 1985

By G. L. Dollinger, J. P. Kindsvater, J. A. Gibson

DESIGN AND DEVELOPMENT OF A MOBILE MINING MACHINE INTRODUCTION Until recently, developing tunnels in hard rock has been accomplished either by the drill and blast method or by using large tunnel boring machines. Combining the flexibility of drill and blast with the safety, efficiency and productivity of a TBM has been the objective of mining machinery producers for many years. In 1979 The Robbins Company began developing a new type of tunnel boring machine called the Mobile Miner to meet these objectives. The development and testing of the Mobile Miner is the subject of this paper. CURRENT MINE DEVELOPMENT METHODS Both the drill and blast method and the use of a TBM have notable advantages and disadvantages. The drill and blast method, for example, allows much more flexibility, requires less setup time and has a lower initial cost than a TBM; however it requires the use of high explosives and blasting has a disrupting effect on the rock surrounding the development. A TBM, on the other hand, is safer to operate, more efficient, more productive and produces smooth tunnel walls without disturbing the surrounding rock. In longer straight drifts it will easily out distance the drill and blast method. The TBM, however, is limited to boring a circular cross section tunnel which must then be modified if a flat floor is required. It also has a higher initial cost and an extended setup period.

Jan 1, 1985

By Jon C. Volkwein

The Bureau of Mines and many member companies of the Industrial Sand Association have been working in several areas to reduce personal exposure to respirable dust. Areas investigated include ventilation, modification of hardware, moisture addition to the product, and improved housekeeping practices. Ventilation systems have been devised and shown to contain 100 pct of a tracer gas released within the hood. An industrial clean air island has been developed and shown to reduce dust levels 90 pct at the opera- tor's position, Modification of hardware on a bag filling machine has been demonstrated to reduce dust 83 pct at the machine operator's lapel. This particular development has been termed a significant advancement in the state-of-the-art of bag filling by industry representatives. Addition of moisture to dried product materials has been tested with results showing dust reductions of 90 pct are possible!, Control of the moisture addition method still needs refinement and costs may be prohibitive. Dust sampling results clearly show the benefits of housekeeping practices such as building cleaning and vacuum sweeping. Rotation of work schedules is also effective for reducing personal exposure.

Jan 1, 1985

By T. Patching

"THE FOLLOWING notes on coal mining in the Edmonton city area are based, in the main, on scattered reports and accounts as little coal mining has been done in this area for about 20 years and few people are left who were involved in what was at one time an important industry of northern Alberta. Although coal mining is not likely to be permitted in the city area itself in the future, a record of this work is warranted to indicate the ·conditions and problems that may be encountered if underground mining again is proposed in the district in the same geological formations and in similar strata. Coal mining in the Edmonton area developed with the influx of settlers in the latter part of the nineteenth century and the first part of the present century. Probably local coal was used by the Fort's blacksmith as early as 1841, and the early settlers probably were 'gopherholing' into the outcrops along the river banks by the 1870s. The first report of commercial coal mining was in 1880 when a contract was let by the Hudson's Bay Company for the provision of 300 tons. As the population in the city and northern parts of the province grew, many new mines were opened along the river and in the district, and coal was even shipped by barge to points in Saskatchewan(1 ,2) By 1909 the Department of Public Works reported that 'Edmonton stands as the second largest domestic coal producing centre in the province'. It continued to hold this position until 1942. From about 1912 to 1951 annual production from mines in the city and surrounding district ranged between 0.38 and 0.65 million tons, depending on weather, wars and strikes. Production began to decline in 1951 because of the increasing availability and consumption of natural gas which was piped into the city and then provided to other towns and rural areas in the northern part of the province. Taylor noted that between 1880 and March 1970, when the last mine within the city area closed, the total of mines and prospects within the Edmonton city area rose to 153. Most of them were small; not more than 20 produced more than a quarter of a million tonnes during their entire life, and only three produced a million tonnes or more. As described by Taylor ""within the city district workings extend discontinuously from the apex of a narrow triangle near Groat Bridge to the base of the triangle in the Clover Bar area"". The larger mines were in this latter area. Approximate locations of the old mine workings in the city are shown in Taylor's atlas. A number of other coal mines were worked in the Rabbit Hill, Big Island, St. Albert, Namao, Cardiff and Morinville districts around the city."

Jan 1, 1985

By Stephen J. Navin, Francis P. D. Navin

Long-distance movement of various materials by conveyor is becoming common; therefore, it is no surprise that conveyors are frequently found in very long tunnels. In such long tunnels, there is a continual controversy between the tunnel operator's requirement for a maximum of clear space for the conveyor and vehicles and the investor's wish to make the minimum capital investment for excavation. This analysis shows that the question becomes more pressing as the tunnel becomes longer. The result given in this paper is a straightforward method by which an economic and operational optimal tunnel width may be selected for any specified tunnel length. Detailed computational formulas are developed relating costs of construction, vehicle operation, vehicle accidents, and conveyor downtime to both tunnel width and length.

Jan 1, 1985

By Törbjorn Naarttijärvi, Bengt Ludvig, Agne Rustan

"Falling rock is one of the major causes of serious injuries and deaths in Swedish mines. The research at the Division of Mining and Underground Construction was therefore directed toward controlled blasting in hard intense jointed rock.The project was started with an extensive literature review. Model tests with a new equivalent model material have been initiated to find ways of improving blasting techniques. The result showed that long cracks arise at the perimeter holes when there is a long time delay between adjacent holes. This led to the theoretical development of a new initiation method with ultra short delays (1,5 ms) f or controlled blasting, called ""Cutblasting"".Full-scale tests have been done at LKAB in Malmberget in hard intense jointed magnetite ore. Four different types of perimeter charges have been tested, namely: tube charges, ANFO mixed with plastic beads, detonating cord and linear shaped charges. Three types of initiation of the perimeter holes have been used, conventional (half-second delay detonators), instantaneous and ultra short ""cutblasting initiation"" (1,5 ms delay). The change in rock strength before and after blasting has been studied with bore hole periscope, vibration measurement and ocular observation of the rock surfaces.Thefull-scale tests showed that ""cutblasting"" with detonating cord in the perimeter holes gave the smallest damage to the surrounding rock. A combination of cutblasting initiation and tube charges are anticipated to give an even better result. A new method of controlled blasting using linear-shaped charges has also been tested, however, this charge type needs further development.The full- scale test also showed that the damage which can be seen on the rock surf ace is about the same for different controlled blasting methods but the not-visual-damage zone varies as much as from 0,1 to 0,7 m.A new classification system for controlled blasting regarding the damage to the surrounding rock has been devised."

Jan 1, 1985

By William C. Beebe, Russell E. Martin

An account of driving and concreting two 900 m railroad tunnels for the Denver and Rio Grande Western Railroad under emergency conditions. Details the importance of on-site decision making by the Owner in completing the project successfully in record time. A general description of the geology and construction methods. The Thistle Drainage Tunnel drained water impounded behind the Thistle slide and serves as permanent diversion of the Spanish Fork River and Thistle Creek around the slide area. The project involved 684 meters of 5 m horseshoe tunnel, a 5 m diameter raised shaft and 23,000 cm of cut excavation.

Jan 1, 1985

By Jerome C. Neyer

Within most of Canada and the northern third of the United States, the soils overlying bedrock are of glacial origin. Tunnelling in glacial soils presents numerous challenges to the contractor, including abrupt changes in soil type, boulders and glacial erratics, water bearing fine sands and silts, toxic or explosive gases, and glacial till. This paper examines the available techniques for geotechnical exploration in glacial soils; the relationship between subsurface conditions predicted by various techniques and conditions actually encountered during tunnel construction; and potential improvements in the planning and implementation of geotechnical explorations. Case histories of geotechnical exploration and tunnel construction in glacial soils are also reviewed.

Jan 1, 1985

By Dennis J. McCarthy

TAX TREATMENT OF EXPLORATION AND DEVELOPMENT EXPENSES Exploration Expenditures General Principles. Exploration expenditures are expenses incurred within the United States or the Outer Continental Shelf for the purpose of ascertaining the existence, location, extent or quality of any deposit of ore or other mineral. Section 617 of the Internal Revenue Code permits a taxpayer to elect to deduct these expenditures currently. In default of election, exploration expenditures must be capitalized and included in the basis of the mineral property for purposes of determining cost depletion. Entitlement to Deduction. In order to qualify for current deduction, exploration expenditures must be incurred prior to the commencement of the development stage, i.e., when mineral deposits are shown to exist in sufficient quantity and quality to reasonably justify commercial exploitation. Generally, expenditures for geological and geophysical investigations, reconnaissance, surveying, testpitting, trenching, drilling, driving of exploration tunnels and adits and similar types of work constitute exploration expenditures if incurred prior to the commencement of development. However, expenditures to further delineate the extent and location of an existing commercially marketable deposit are not exploration expenditures. Exploration expenditures may be incurred from within a producing mine to ascertain the existence of what appears to be a different ore deposit. Expenditures for property which is subject to an allowance for depreciation are not deductible under §617. However, depreciation properly allowable on assets used in exploration is an exploration expenditure. Election to Deduct Exploration Expenditures. The election to deduct exploration expenditures is made by deducting these expenditures in the return for the first taxable year for which such treatment is desired. The election applies to all properties of the taxpayer. Once the election is made all exploration expenditures, in the year of election and thereafter, must be deducted, unless the election is revoked with the prior consent of the Commissioner. The Tax Equity and Fiscal Responsibility Act of 1982 (TEFRA) made substantial changes in the treatment of exploration expenditures. For exploration expenses incurred after 1982 and before 1984 by a corporation, the amount currently deductible is limited to 85% of the expenditure. The remaining 15% must be capitalized and recovered over a five-year period. Although exploration costs capitalized under this provision are not part of the basis of the property for cost depletion purposes, investment credit may be claimed with respect to these expenditures. Further changes have been added by the Tax Reform Act of 1984 with respect to expenditures made after 1984. The Act reduces the amount of otherwise currently deductible costs from 85% to 80%. Additionally, it limits the availability of the investment credit for capitalized mineral exploration costs to deposits located in the United States. TEFRA also allows individuals a special method of recovery under which exploration expenditures may, at the election of the taxpayer, be amortized ratably over a 10-year period beginning with the year in which the costs are paid or incurred. If taxpayer does not use this method, the excess of the exploration expenditures actually deducted over the amount that would have been deducted if 10 year amortization had been elected is an item of tax preference subject to the alternative minimum tax.

Jan 1, 1985

By J. Patrick Powers, Arthur B. Corwin

Modern improvements in hydrogeology make it possible to predict with good reliability the performance and cost of ground water pumping systems in many tunneling situations. The testing and analysis techniques are presented. Data from the Buffalo NY LRRTS (1978-1980) illustrate the successful application of the technique for tunneling in rock. Data from the Red Hook Interceptor Tunnel in Brooklyn NY (1978) illustrate the application in soft ground. The Red Hook project also illustrates concerns for the side effects from dewatering, such as ground settlement and damage to timber structures. At Red Hook protective measures included compressed air, artificial recharge and controlled dewatering. Given the uncertainties of the underground, the possibility of unexpected situations must be considered. A hard rock sewer tunnel in Atlanta, Georgia (1982) illustrates an unexpected problem, and the emergency measures used to solve it.

Jan 1, 1985