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By Robert R. Perron

The U.S. Bureau of Mines is engaged in many diverse programs for improving mine safety. Of particular interest to the Bureau are new and improved means for minimizing the hazard of fire which can be initiated by prolonged low energy electrical faults on trolley line systems. When a high energy fault occurs on a trolley line, wherein the current exceeds the magnitude normally drawn by legitimate loads, such as locomotives, then the circuit breakers at close-by power rectifier sets trip. Tripping of the breakers not only protects the equipment at the rectifier sets, but also disconnects the energy source from the fault and thereby minimizes the fire risk. However, the fault current is frequently of a level substantially below that required to trip the overload breakers. When the fault is a substantial percentage of the set level of the breakers, the energy dissipated by the fault is frequently sufficient to clear the system by rapidly burning itself clear. Such a fault is often short-lived and does not present as serious a fire risk hazard as a prolonged, much lower energy fault, wherein the energy level is too low to clear the system. The breakdown of a trolley line insulator, in which there was a 20 or 30 ampere leak, would represent such a fault or illegitimate load and a substantial fire risk.

Jan 1, 1974

By T. D. Rourke, E. J. Cording, O&apos

INTRODUCTION Detailed investigation of a 60-ft-deep excavation in a mixed profile of sands and stiff clay was performed by the University of Illinois for the Washington Metropolitan Area Transit Authority (METRO). The work was coordinated through DeLeuw, Cather and Co., the General Engineering Consultant of METRO. Instrumentation was concentrated in a portion of braced excavation for the Gallery Place Station near the intersection of 7th and G Street. The early construction date, the 60 ft depth of cut, and the proximity of large buildings formed the basis for selection of this site as the focal point of observation and measurement. A history of lateral and vertical displacement is provided wherein movements which occurred during excavation to the full depth of cut and, subsequently, during station construction and the removal of braces are described in detail. Observations of preloading and the consequent brace loads and wall displacements are described. The effect of temperature change on brace loads is discussed and the measured apparent earth pressure for the 60-ft cut is provided. The paper discusses the relationship of lateral displacements of the cut wall to the construction procedure, and compares the lateral wall displacement with both lateral and vertical movement in the surrounding soil mass. Based on observed movement, the method by which displacement was predicted for a nearby 82-ft-deep excavation is described. The performance of the 82-ft-deep excavation has been summarized elsewhere (2).

Jan 1, 1974

By Joseph W. Leonard

The purpose of this paper is to review and discuss some of the less evident and sometimes neglected opportunities for progressive developments in coal research. While a great deal of both promotional and technical information flows from some areas of coal research, output deficiencies in other areas of activity have reached a magnitude where important developments have been, and will increasingly be, unfavorably affected. These areas mainly involve coal mining and preparation. Some recommendations for the intensification of effort in these areas follow: Coal Mining While a huge tonnage of in-the-ground coal is assured, the location and distribution of these tonnages are becoming less favorable. The easy-to-mine coal which is located in or near population centers has been, or is being, mined. The vigor with which the less accessible reserves are recovered by the mining industry depends largely on the condition of the coal market at the time of mining. Hence, during a buyer's market, the commercially oriented mining industry is compelled to mine the easier and less costly reserves. Conversely, during a seller's market, the need to rapidly expand production results in more difficult mining and higher cost coal as few obstacles are encountered in finding markets. Hence, a seller's market tends to enhance the recovery of reserves while a buyer's market does not. One reason for today's fuel supply problems is that the Nation has recently emerged from a long-term coal buyer's market which lasted from about 1950 to 1968. During that period, national policy caused severe production cutbacks which regretably drove the industry to mining only the more accessible and better quality reserves. Often in order to remain in business, many hundreds of millions of tons of more difficult to mine reserves were abandoned and lost behind caved areas. Many of these reserves are close to population areas and would not have been lost in a more stable economic climate. It is difficult to fully account for all the impacts that were caused by the great buyer's market of the 1950s and 1960s. Besides the obvious loss of reserves that were once considered national wealth, the mining of better reserves tended to produce a generation of technically optimistic mining people. Mining people frequently became accustomed to looking at nothing less than outstanding mining conditions as a result of the declining market. Many are now and have long since received a re-education in the other half of mining. Going from many years of mining accessible, select and easy-to-win reserves, to the crash-driving of development entries in reserves that were considered unworthy of mining during 50s and 60s, frequently results in a much higher rate of encounter with in-seam and out-of-seam rock as well as with coal-deficient areas or "washouts." Intensive entry driving activity and compulsory non-selective mining in sometimes lean reserves were brought on by the need to rapidly open up new supplies of coal. Working under these requirements presents a continuing reminder that much more needs to be known about the relatively esoteric art of planning the best direction for driving entries in order to insure that a more consistent and greater supply of coal is available during early mine development. All of the preceding discussion tends to point to a need for a better estimate of those reserves of coal that are likely to be mined in the future. Such estimates should not be limited to the compilation of the amount of coal in the ground; but, where possible, should also include information concerning the capability for producing this coal. After all, a coal seam of ample thickness may have a degree of thickness variability, undulation, bad roof or floor, so as to make what would otherwise appear to be an attractive mining condition untenable. Underlying the problem involving the feasibility of producing known reserves is the need to develop better methods for the characterization of coal seams and associated lithotypes, based on drill core data, once at area is selected for mining. Reserves and their characterization involve aspects of exploration technology that are frequently considered mature. The resulting technological deficiencies may be the main reason why coal exploration frequently does not end with core drilling of a property, as it should, but extends into the mining operation during the driving of development entries. When exploration is extended to the driving of development entries, the near absence of integrated decision-making theory involving mining, geology, mathematics, and economics becomes, once again, all too painfully apparent and frequently results in very costly rationalizations. Hence, by the formal initiation of a concentrated program to combine the cyclical effects of economics with geology and mining, more relevant estimates of reserve distribution, tonnages, and production capability should be forthcoming. Moreover, a similar formal effort is needed to develop a combination of the most advanced concepts of mathematics, geology, and mining to better "see" coal seams as a means to favorably implement many long-range decisions involving mine safety and productivity. Much more applied research needs to be done on coal mining systems for mining in thin seams and/or under bad roof. Current difficulties in both of these areas at recently opened coal mines should provide a sobering glimpse into the future. Full-scale applied research, sponsored by appropriate federal agencies, is urgently needed on a scheme involving a new combination of established mining and preparation elements. The scheme may include: (1) a continuous mining machine remotely operated by a miner stationed at some distance behind the machine using a cord attached control box; (2) hydraulic transport of coal through pipes from the mining machine to a coarse refuse removal grid, crusher, and then on to portable concentrating equipment; (3) the hydraulic transport of clean coal out of the mine in pipes to the surface for thermal dewatering, if neces-

Jan 1, 1974

By Sidney Katell

This study estimates capital investment, operating costs, and selling prices for four underground bituminous mines producing coal with annual production ranging from 1.06 to 4.99 million tons. It is assumed that the mines have a 20-year life. Wages and union welfare payments are considered as of November 12, 1973, under the Bituminous Wage Agreement of 1971, and costs for material and equipment are based on 1973 indexes. Initial capital investment ranges from $12,540,700 for the 1.06-million-ton-per-year (MM tpy) mine to $44,720,500 for the 4.99 MM tpy mine. Total capital investment ranges from $21,850,700 to $75,693,500 for the same mines. Corresponding selling prices for the coal range from $8.76 to $7.53 per ton, assuming a 12-percent discounted cash flow rate of return after Federal income taxes.

Jan 1, 1974

Over the last few years several important developments have taken place in the Electro- lyte Purification Plant at Copper Refineries Pty. Ltd. A fully automated system for the continuous removal of arsenic has been develop- ed. A submerged combustion process for the removal of nickel has been developed to a stage where patent coverage has been obtained in most of the copper producing countries. A plant has recently been commissioned for the production of Tetra Cupric Arsenate, which it is hoped will find a ready market in the timber preservation industry.

Jan 1, 1974

By Henry R. Tiedemann, Eugene H. Skinner, George E. Wickham

Improving the state-of-the-art of tunneling is a continuing challenge to those involved in underground construction. New methods and procedures are usually evolved over a relatively long period of time as compared to advancements in other types of construction. To a large extent this is probably due to the fact that tunneling deals with a material or medium - the rock structure - whose physical properties are not only extremely varied, but in many instances virtually unknown until time of penetration. This hovering of the unknown tends to make "non believers" of many and at best leads to a general reluctancy of accepting new ideas or procedures. The situation is further complicated by: 1) discrepancies in terminology and respective meanings as used by different disciplines to describe, define or evaluate pertinent factors and their relative effect on the tunneling process and 2) the fact that no two tunneling situations are identical with respect to either geological conditions or construction and contractual requirements. In spite of the above there have been many successfully completed tunnels which make it apparent that both the technical and practical expertise needed to develop or project improvements is available within the industry. It is with this in mind that the RSR concept was developed. BACKGROUND This paper presents the findings and results obtained from contin-

Jan 1, 1974

By Albert W. Scragg

"THE ADMINISTRATION DEPARTMENT consists of six sections, all with their own supervisors, reporting to the superintendent of administration. Although each of these sections is uniquely separate, they all work together, in one department, to provide very necessary services.1. Accounting 2. Purchasing 3. Warehousing 4. Data Processing 5. Inventory Control6. Office ServicesThis department, which now numbers 108 people, had its birth in an office over a hardware store in downtown Timmins in 1964. Initially, only basic accounting and purchasing functions were performed and these, of course, were on a very small scale. The growth of the administration department is a function of the growth of the company."

Jan 1, 1974

Gunpowder Copper Limited processes 1,000 tonne/day of Mammoth ore in a conventional flot- ation concentrator. Run of mine ore is prepared for flotation by three stages of crushing and two stages of ball milling. The concentrate, in which the primary copper mineral is chalcocite, is solar dried and exported to Japan. The history of operation is summarised, and plant practice and metallurgical problems are discussed.

Jan 1, 1974

By D. G. Peterson, W. J. Guay

The extraction of gold from refractory ores containing activated carbon and various types of carbon compounds is being done commercially for the first time at Carlin, Nev., by Carlin Gold Mining Co. Oxidation of the carbonaceous materials to CO and CO,- is accomplished by the introduction of chlorine into an aqueous pulp. The chlorine reacts with the limestone in the ore to form calcium hypochlorite which in turn reacts with the carbonaceous matter to form calcium chloride, CO, and CO.. Following the oxidation treatment the ore is cyanided in the conventional manner. For the first six months of operation the plant averaged 83% extraction at a feed rate of 500 tpd and a consumption of 28.4 lb chlorine per ton of ore which showed only 33.5% extraction by conventional cyanidation without the oxidation pretreatment.

Jan 1, 1974

Commencing early in 1975, Saraji Mine in Central Queensland will product 3.56 million tonnes in the first year and then 4.57 million tonnes annually for the Japanese and European markets. The coal will be mined from a series of pits separated by corridors which will be mined at a later date. Through the corridors flow regional drainage structures and power lines. Relatively easy areas will be mined initially to assist the cash flow and to minimise start-up difficulties. For ease of scheduling it is desirable that pit lengths exceed 3 000m but this will not always be possible. Ramps were designed using 1 200m spacing and 5 per cent gradient as optimum but modified to suit specific conditions. One ramp will be in the end of each pit nearest the ROM hopper and stripping will commence from this end. The advantages so gained are shorter haul distances, immediate access to the coal after stripping and simplification of the excavation of the first ramp. Haul road location was defined by the minimum present value of construction plus operating costs. Road design utilised airfield construction charts because wheel loads were outside the range of available road design manuals. Low load resistance characteristics of

Jan 1, 1974

By Michael J. Beus

This Bureau of Mines report describes the development of load cells for measuring compressive loads in timber and lock-bolt support systems commonly used in. coal; metal, and nonmetal mines Design and evaluation is covered in detail to insure a reliable, accurate, and practical instrumentation scheme. The load cells are relatively inexpensive and adaptable to various size support systems. User-oriented procedures are emphasized, and design equations were reduced to a series of nomographs. Laboratory evaluation, destructive testing, environmental testing, and tests to determine the effect of extraneous loads were conducted. Field performance was evaluated in conjunction with ongoing Bureau projects at a metal mine in North Idaho and a coal mine in Utah. Load cells utilizing a titanium alloy as the cell body and weldable strain gages as the strain-sensing components satisfied the basic design and performance criteria, and with minor design modifications, the load cells can be adapted to many mining applications.

Jan 1, 1974

By I. Iwasaki, R. Titi-Manyaka

Chlorination and chloridization behaviors of pyrite, pyrrhotite, marcasite, chalcocite, covellite, galena, sphalerite, heazlewoodite, and elemental sulfur were investigated by thermogravimetric analysis. The possible reaction mechanisms are discussed on the basis of the theoretical weight changes and thermodynamic considerations. Chlorine is a more effective chloridizing agent than hydrogen chloride. In the light of the experimental results, a scheme for producing nonferrous metal chlorides, molten sulfur, and ferric oxide from complex sulfide flotation concentrates is discussed.

Jan 1, 1974

By F. E. Armstrong

An instrument using a gamma-ray backscatter technique for determining the weight-percent incombustibles content of coal dust and rock dust mixtures in coal mines has been built and tested. The unit gives a direct readout in per-cent incombustibles for coal mine dust mixtures containing between 50 and 100 percent incombustibles; calibration of the device requires using a sample of the rock dust employed; this is usually limestone but occasionally dolomite or gypsum. A small americium-24l source is used with a scintillation detector whose output feeds a rate meter. The source-detector geometry used was chosen to reduce the effects of variation in bulk density. Accuracy of the system is within ±3 percent for most mixtures. The instrument is portable and completely self-contained; the rechargeable batteries supply power for 300 to 400 determinations.

Jan 1, 1974

By M. L. Whisman

Three samples of waste lubricating oil were re-refined by processes developed by the Bureau of Mines and reformulated with additives to meet designated requirements for viscosity and service. Quality-defining bench-scale tests were used to compare and evaluate the quality of these three motor oils, eight commercially re-refined lubricating oils, and three new lubricating oils. Most of the re-refined oils studied could not be distinguished from new oils by the bench tests used to define quality. There was some evidence, however, that one and perhaps more of the re-refined products investigated might not meet all of the quality standards of new lubricating oil, suggesting the need for better quality controls by re-refiners.

Jan 1, 1974

By Jack L. Henry

The Bureau of Mines conducted seven pioneering experiments in a 12-inch-diameter Kroll reduction reactor to examine the feasibility of coreducing the chlorides of Ti, AI, and V to produce a homogeneous titanium alloy sponge. The coreduction studies proceeded in a normal manner, and the yields of sponge were comparable with those of pure titanium sponge made in the same reactor. Vanadium concentration was very uniform throughout the sponge cake when VC14 in solution in TiCl4 was fed into the molten magnesium. More difficulty was encountered in feeding solid VCl2 and AIC13. Vanadium and aluminum concentration in the sponge was not uniform, and mechanical difficulties were experienced with the small-scale screw feeder. Although the sponge varied in composition from region to region, the ingots prepared from it were uniform in composition.

Jan 1, 1974

By E. C. Foster

The project objective of this contract is to design, develop, and demonstrate a dust collecting system for auger head miners, used in coal seams 40 inches or less in height, which will reduce respirable dust below the limits established by the Federal Coal Mine Health and Safety Act of 1969. This system was to be incorporated into 3 Wilcox Mark 20 continuous miner. In order to accomplish this, the objective was divided in three main areas. First: To develop a dust control system which would remove by isolation, respirable dust from the face area and areas where miners work. Second: To develop a dust scrubbing system to remove and collect float dust before the air reaches the return airway. Third: To reduce the overall noise levels to which the miners are exposed.

Jan 1, 1974

By A. C. Lyons, A. J. Reed

INTRODUCTION A trend which is obvious in the United Kingdom and is thought to be evident in other parts of the Western world is the disproportionate rise in the cost of tunnel mining labour compared with other tunnel cost increases. This disproportionate increase in labour costs has been accompanied by, and may be the result of, a shortage of skilled working labour. To combat this problem there has been a steady increase in the use of machines for excavation and for the erection of tunnel linings to keep the amount of skilled labour working below ground to a minimum. The typical tunnelling cycle, where the ground needs continuous support can be excavation, temporary support, temporary lining, grouting and permanent lining. It is obviously an advantage to combine as many of these operations as possible and carry out as much as possible by machine. Machines have been developed which will, either alone or used in combination with a shield, excavate and, when necessary, temporarily support the excavation. If a segmental lining is used, it can be so designed that it will form the permanent lining and reduce the cycle time and skilled labour requirement to a minimum. In cases in which the ground can be cut accurately to a smooth profile and will stand without support for a sufficient time, the lining can be expanded against the ground and the necessity of grouting eliminated. In cases in which ground will not stand without support, the usual method is to use a bolted lining and to grout behind it preferably as the shield is shoved forward. Whichever technique is used (this is largely determined by the ground) it is an advantage to make the segments as large

Jan 1, 1974

By Gomi S

A new watersoluble binder for mineral ore pellets has been developed by the sulfonation of bituminous materials. A highly effective binder for iron ore pellet making is obtainable from bituminous materials produced in the high temperature cracking of crude oils. This paper deals with production process and basic properties of this binder as well as new applic- ations in the field of iron ore pelletizing.

Jan 1, 1974

By Robert D. Talvensaari

It is indeed an honor for White Pine, as a member of the copper mining industry, to participate in this Rapid Excavation Conference. Although our presentation, as the title indicates, is not a success story, we foresee, through our experience, future application of boring machines and rapid excavation equipment in the hard rock mining industry. One might ask what a copper mining company would be doing with boring machines and why the gamble on a high-cost, capital investment for a relatively untried application. Perhaps a little background on the White Pine mine and its geology will explain our daring and speculative motives. THE WHITE PINE MINE The White Pine Copper Company, a wholly-owned subsidiary of Copper Range Company, operates a mine, mill and smelter at White Pine, Michigan in the western Upper Peninsula approximately 6 miles due south of Lake Superior. We employ approximately 3,000 people from the surrounding area and mine approximately 25,500 tons of low grade (1%) copper ore per day. The orebody is contained within several distinct sedimentary horizons that comprise the lower 20 feet of a Precambrian formation known as the Nonesuch Shale. Numerous articles and reports have described many aspects of the White Pine operation and the geology. I will brief you only on that criteria which precipitated our interest in rapid excavation equipment and techniques, specifically, boring machines. Mineralogical and optical studies have demonstrated that the siltstones, sandstone and shale beds all contain relatively barren and discrete particles of quartz (25%), feldspar and mica, bonded with

Jan 1, 1974

By Parks T. C

A low-grade disseminated nickel sulphide serpentinite ore from W.A. had a relatively high permeability after drying. Various techniques indicated that the permeability resided within a fine network of fibrous vein- lets and especially within coarse cracks along which the sulphides lay. The ore minerals were therefore open to selective extraction by chemical leaching. A IM ammonia-7.8 wt.o "ammonium carbonate" solution, oxygenated at 1 bar oxygen pressure and about 23¦C, released nickel, copper and cobalt from the sulphides, leaving a permeable residue of goethite, while calcium, magnesium and iron concentrations remained negligible in the leachant. The nickel and copper was electrodeposited directly from the pregnant liquor in a deposit which included 16.5 wt.% sulphur. Enhanced copper/ nickel ratios early in the extraction suggested that valleriite (not amenable to flotation) was leached preferentially. Th$ controlling influence of the pore structure was demonstrated by the dependence of leaching rates on the size of the ore particles used, and on the measured porosity of different ore samples. A 2mm size was probably the optimum for exposing sulphides to the leachant. Leaching was accelerated by increasing the temperature and oxygen pressure.

Jan 1, 1974