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By Donald F. Kennedy

During the past several years Climax Molybdenum Co. has been engaged in testing various types and sizes of hollow drill steel. The majority of tests have been on 7/8-in. hexagon st.ee1, inasmuch as it represents approximately 70% of total drill steel consumption at the Climax operation. Prior to December 1960, tests on 7/8-in. hexagon drill steel were conducted on steel with a forged collar and, in most cases, with a threaded bit connection. Through these tests and research, some improvement in steel life was achieved by making changes in heat treatment, design and alloying constituents. However, during that month, research and testing commenced on a rubber collar which was designed to replace the forged collar on 7/8-in. hexagon drill steel. Manufactured by the LeRoi Div. of Westinghouse Air Brake Co.. the collar. is very simple in design, consisting of a 1 ½ -in. diam steel cylindrical sleeve 2 in. long, containing a bonded rubber insert and attached to the steel with an epoxy cement

Jan 8, 1962

By John A. Fagnant

At Elkol, Wyo., about 80 miles northeast of Ogden, Utah, the Kemmerer Coal Co. and the Utah Power and Light Co. are involved in a joint venture that will soon see 1 million tons of coal going "out by wire" to Ogden. Kemmerer, owner of a multi-seam strip mine, and the utility, now building a steam power plant adjacent to the mine site, expect to begin initial power generation by February 1963. Although capable of producing only 150,000 kw at that time, this plant is expected to be ultimately enlarged to 500,000-kw capacity which will require about 2 million tons of coal annually. The deposit consists of more than 30 seams of coal, usually varying in thickness from 2 to 40 ft, and separated by beds of sandstones and shales. In certain areas the aggregate thickness of all the coal seams measures 300 ft. The thickest and most spectacular of these seams is the lowest one, referred to as the No. 1 seam, which is 118 ft thick in some places.

Jan 8, 1962

By Leonard Obert

The structural stability of any mine or under- ground opening in rock is dependent on the stress field, that is, the state of stress in rock before mining, the stress distribution in the rock created by the opening, and the in situ strength of the rock. In the past mine design problems have been considered by assuming that the stress field is due only to the weight of the overlying rock, the stress around the opening can be calculated from elastic theory using laboratory-determined elastic constants, and the in situ strength of the rock can be determined from laboratory tests on small specimens. Solutions to hypothetical problems using this procedure are given in a report by Obert, Duvall, and Merrill.' Because of the uncertainties of these assumptions, this method can give only a rough approximation to the solution of actual structural problems. Obviously, this approach to determining the stability of underground openings would be greatly improved if the rock stress could be measured in situ, and it is undoubtedly for this reason that in recent years many investigators have spent considerable effort on the development of procedures for measuring rock stress. In this report a method is described for determining in situ the absolute stress in rock. The method requires the measurement of the deformation of a borehole before and after the rock is stress-relieved. The magnitude and direction of the applied stresses are calculated from the borehole deformation and modulus of elasticity of the rock. Also, the results of absolute stress determination made in the walls and pillars of underground openings in five rock types are presented. From these results a number of conclusions are drawn regarding the accuracy and limitations of this method and the problem of stress measurements in general.

Jan 8, 1962

By Nathaniel Arbiter, Edward L. Vickers

Complete automation of concentrator operations through computer control has been under increasing consideration by American engineers for several years. Although justification for full-scale automation of a mill must ultimately be economic- added profits exceeding instrumentation and development costs-the technical feasibility of automation will be determined by the availability of requisite, detailed knowledge of the various unit operations in the plant. This poses problems. BASIC PROBLEMS WHICH MUST BE CONSIDERED A hypothetical porphyry copper mill will be used here to illustrate these problems. Its flowsheet will involve: mining, crushing, storage, grinding and classification, flotation, product de-watering, and disposal.

Jan 8, 1962

By Z. E. Arlin, R. D. Lynn

The problem of disposing of excess waste water coming from The Anaconda Co.'s two uranium mills in Grants, N. M., first confronted the company's engineers in 1956. The increased discharge of mill waste water was due to the start-up of a second mill, recently completed to supplement production from a smaller plant which the company had operated since 1953. The waste water is mildly acidic and has a low level of radioactivity due to small amounts of uranium-natural, thorium-230 and radium-226. In addition, it contains large amounts of manganese, iron and the sulfate and chloride salts of sodium, calcium and magnesium.

Jan 7, 1962

By John G. Roscoe

Continental Materials Corp. operates two under- ground uranium mines in the Crooks Gap district of central Wyoming. Both mines are developed as slusher mining operations through vertical shafts with single level haulage to slusher pocket loading stations. In general, operations at both mines are similar except for depth and some minor details. The shafts are identical in cross-section, each with a 4 ½ x 5-ft hoisting compartment and a 4 ½ x 5-ft manway. Kimberley-type skips are loaded from measuring pockets through air-operated guillotine gates. The Seismic shaft is 245 ft deep and the Reserve shaft depth is 585 ft. The Seismic shaft was sunk in 1957 and the mine has been producing 200 tpd since 1958. The Reserve shaft was sunk in 1960 and the mine is still in the development stage. The hoists of both mines are equipped for semi-automatic operation; that is, they are mechanically controlled to perform a certain cycle of duty and then stop until another cycle is manually initiated. The Seismic hoist, however, was originally a conventional, manually controlled unit; the reserve hoist was installed as an automated system.

Jan 7, 1962

By E. P. Chapman

In May 1957 a diamond drill hole intersected 40 ft of magnetite and chalcopyrite assaying 2.55% copper and 51.6% iron on the claims of Craigmont Mines Ltd. near Merritt, southern British Columbia. The subsequent drilling indicated the presence of a multi-million ton orebody averaging over 2% copper and 18% iron, the latter present for the most part as magnetite and specular hematite in approximately equal proportions. This orebody, although under shallow cover at its eastern extremity, did not come to the surface and the early drilling was done on the basis of strong coinciding magnetic and geochemical anomalies. After 4 ½ years of intensive exploration and development the property was put into production in September 1961. The new ultramodern concentrator has a design capacity of 4000 tpd but is consistently treating well over this amount. Production is currently coming from that portion of the deposit which is amenable to open-pit mining methods. By mid-1958 information regarding the importance of the Craigmont find became fairly wide- spread, and exploration in the Merritt area was greatly intensified. Numerous magnetic and geochemical anomalies have been tested by drilling with notable lack of success. Detailed geological studies of the deposit and of the area have been made by Government agencies and by private companies and such studies are continuing. Many types of geophysical methods have been employed over the Craigmont deposit in an effort to develop knowledge which would assist in the search for similar mineral concentrations in the environment in which it occurs. This paper will discuss the results of the various geophysical surveys in relation to geological conditions and ore outlines insofar as they are now known.

Jan 7, 1962

By Harry V. Warren

There are two topics which may be considered as opening gambits in any conversation in any part of the world, weather and health. Nothing much can be done about the former, and it would appear that no great changes can be anticipated in the immediate future. With respect to health, a great deal has been achieved in the past 150 years, curiously enough not all of it by medical men. It would appear that the time is now appropriate for geologists to come to the assistance of medical men. During the past few decades, medical science has mastered many of the diseases commonly associated with childhood. As a man tends to live longer, those diseases usually associated with middle and old age become more prominent. Thus we must realize when we say that today more people are dying of cancer and coronary disease, absolutely and relatively to other diseases, this should not suggest that these diseases did not exist a hundred years ago; it does suggest that more people are living to an age where death from these diseases is apt to become more common.

Jan 7, 1962

By W. C. Spence, Burt C. Mariacher

Methods employed to beneficiate ores utilize relatively few fundamental principles to effect size reduction and concentration. In crushing and grinding only impact and compressive forces with a minor amount of shear are employed. In concentration, gravity, magnetic, electrostatic and flotation constitute the major methods of concentration with minor use of sizing, hand picking and adhesion. This industry, as all others, can expect in the near future to see the development of new techniques for improved efficiency, cost reduction, and exploitation of raw materials hitherto considered unmanageable. NATURAL AND INDUCED RADIOACTIVITY At the Canadian Department of Mines in Ottawa in 1946, C. M. Lapointe developed a picker belt system whereby radioactive ores could be concentrated by electromechanical means. This invention ultimately led to development of what is now refer- red to as the Lapointe Picker and which has been used commercially at Port Radium and Port Hope for the upgrading of jig concentrates. Basically, the system consisted of conveying sized uranium ore on a belt under a radioactivity detection device which in turn electronically operated a kicker or plunger that separated the ore from the gangue constituents. Thus, a new principle for mineral concentration, radioactivity, was introduced commercially.

Jan 7, 1962

By Mack H. Shumate

1 Raw coal from Truax-Traer Coal Co.'s Burning Star Slope mine, Jackson County, Ill., is brought to the surface by the new 42-in. slope belt haulage conveyor at the rate of 850 tph. The loading system shown above employs four storage tracks, two tail tracks for loading, and four 25-hp hoists, operating in pairs, and coupled to two dolly cars to move the trains of cars through the tipple. The system has a capacity for loading 1800 tph. One operator is needed to load on each of two shifts. A third man working for a few hours on night shift sets up for the morning cycle. Railroad crews bring in empties placing them in the storage yard, twenty cars to the track. Trains of empties are pulled through to the tail track and loaded on the return; hoists at opposite ends pull the trains in each direction. [ ] 2 Pairs of hoist drums are interconnected electric- ally by a Trench lay cable buried between the tracks. When one hoist operates moving the cars, the tail hoist idles with brake released. The operator, situated in the tipple over the cars, views the storage yard at the end of the first shift (left). When returning loaded cars to yard, four or five cars are held on the dolly to couple the next string of empties. Empties are ready for loading on the tail track (right). Differing from a gravity system in which empty and load tracks are on a slight grade, this system is designed for 80 railroad cars for a two-shift operation and one rail service per day.

Jan 6, 1962

By E. S. Porter

The techniques of particle-size measurement are of particular importance in the manufacture of portland cement. A range of sizes, from a close approximation to Fred C. Bond's "theoretical infinite" (represented by raw material in the quarry) to particles smaller than one micron is represented in the process. Moreover, similar size-reduction operations are performed on both natural and synthetic materials, the former relatively inactive in water and the latter quite reactive. This means that aqueous sedimentation systems for particle-size analysis are applicable only to some of the materials involved in the process. A brief review of the process should be useful to place the measurement techniques described here in perspective. (Fig.l) Raw materials are quarried, crushed and transported to storage at a maximum size usually of a few inches. Typical materials are limestone and clay or shale, with small amounts of other materials used to adjust the plant mix to the concentration of lime, silica, alumina and iron oxide required.

Jan 6, 1962

By A. A. Dor

Of the numerous methods that have been tested or considered for the beneficiation of low-grade iron ores, this article deals only with proven flowsheets that are adopted in plants in operation or which have been reliably pilot-plant tested. Several recommended layouts are described and discussed. They illustrate recent trends and embody improvements and new features that have resulted from the experience acquired in the operation of the plants already in service. They have been developed, in the last few years, in the course of designing several iron ore beneficiation plants of various types and sizes. Some of the design features in the layouts which are submitted represent, in some respects, personal views and may not meet the full approval of others in this field. It is hoped that this presentation will provide an opportunity for constructive discussion of the problems involved and of suitable solutions.

Jan 6, 1962

By James E. Lawver

Efficiency of industrial research and development depends on the ability of engineers and scientists to collect and present data to top management for decisions. In many cases, the data presented are so deceptive that management makes costly wrong decisions. Since management personnel often are selected on the basis of higher administrative quality than technical ability, it is the responsibility of the industrial scientist or research engineer to make certain that the data presented tell a completely ac- curate story of each industrial problem. It is rare that misleading data are deliberately presented, but when this is done, it is? of course, dishonest. The rise of deceptive data usually stems from the lack of knowledge of experimental design and statistical methods of analysis. Most of the better chemical engineering schools have recognized the need for courses in industrial experimentation and many of them offer complete courses at both graduate and un- dergrarluate levels. By contrast, many of the mining and metallurgical schools have not recognized the importance of industrial experimentation courses and some of them, in fact, do not allow credit toward a mining or metallurgical engineering degree for statistical courses even when taken as an elective. The sole purpose of this paper is to make a plea for mining and metallurgical schools to present required industrial. statistical courses for their graduates. It is true that fine industrial research has been accomplished in the past without the assistance of any statistical techniques. Industrial problems have also been solved without the use of digital or analog computers, electron microscopes or other modern conveniences. The fact remains, however, that the correct use of these modern tools tends to reduce the cost of research and to eliminate costly errors. A working knowledge of experimental design and statistical data analysis must simply be viewed as a valuable tool whose proper use will greatly reduce the cost of experimentation and minimize the cost of false conclusions. These statistical methods, however, simply cannot replace fundamental knowledge or, for that matter, "good horse sense". Nevertheless. an experimenter armed with fundamental knowledge and good horse sense but completely ignorant of elementary statistical techniques, may easily present his data in such a deceptive form to cause management to make incorrect decisions.

Jan 6, 1962

By Earl R. McMillan

Though much has been written during the past several years about the Russian success in using hydraulic jets for coal mining, little or none of the published information, in so far as this writer has observed, has been of any use or practical application in this country. It is true, according to their published reports, that the Russians were pioneers in the use of high-pressure water jets in the mining of coal. They report the use of water jets for this purpose as early as 1936. However, according to a survey of foreign literature on the subject made by the U.S. Bureau of Mines1 a few years ago, water jets in the USSR, as well as in other nations including New Zealand, Poland and West Germany, were used principally to sluice the loosened coal after it had been previously drilled and blasted, rather than to cut or break it from the solid face. The interest of the Northern Pacific in the potential application of a high-pressure water jet to the actual extraction of coal, particularly in steeply dipping beds, originated in a visit by this author to the operations of the American Gilsonite Co. at Bonanza, Utah, in March 1958. After seeing the extraction, on a commercial basis, of gilsonite from a 22-ft wide vertical vein of this solid material with a 3/8-in. diam stream of water under approximately 2200 psi, it was felt that, with some modifications, water jets were the solution to the problem of economically mining the steeply dipping (i.e., steeper than 20º) coal beds in the State of Washington.

Jan 6, 1962

By Robert L. Haffner

When mining operations of The Eagle-Picher Co. began in the Illinois-Wisconsin zinc mining field in 1949, all underground loading of broken ore and waste was by caterpillar-tracked machines. Beginning in 1956 rubber-tired end-loaders were brought in; ultimately they completely supplanted the tracked units. End-loaders proved to have the mobility needed for the mining conditions and additional merit in auxiliary capacities. Eagle-Picher operates five mines in this area; two are entered by shafts and three by inclined adits. Several ore zones, some of which are attenuated over a considerable distance, are worked from the same entry. Consequently underground haulage roads connecting or following these orebodies have attained great length. In addition, working places are often widely separated because of the character of the mining operations which include pillar recovery and extending haulage connections into old workings. At one mine, the haulage distance is 5000 ft on either side of the shaft, at another the maximum one-way distance is 8400 ft, and at another the present road system of 6800 ft is expected to reach 10,000 to 12,000 ft.

Jan 6, 1962

By George W. Sheary

Situated 45 miles west of Philadelphia and 50 miles southwest of Bethlehem Steel Company's Bethlehem plant, the integrated Grace mine facilities produce 4000 tpd of high-quality iron ore pellets. Startup of the Grace mill was in November 1958, and iron concentrates were shipped until March 1960, when the pellet plant went into operation. The underground mine, when fully developed, will hoist about 9000 tpd, including development rock. The crude ore, which has an iron content of approximately 42%, is magnetically cobbed and crushed in closed circuit with 3/4-in. slotted vibrating screens. The ore is washed and screened in the mill and the plus 1/4 in. screen product is again cobbed prior to feeding to the rod mills. Grinding is done in rod mills, and in ball mills that are in closed circuit with 30 in, cyclones, to 1% on 100 mesh and 65% minus 325 mesh. The ground ore is magnetically concentrated by three-drum permanent type finisher magnets to 67% Fe. The magnetite concentrate is pumped from the mill to a 50 ft thickener in the pellet plant. The thickened magnetite concentrate is relayed to the filters through a two-stage pump arrangement. The filter cake is fed by belt from filter concentrate bins to mixer-muller belts where it is intimately mixed with bentonite and a slight amount of water for moisture control. The fluffed concentrate then drops into balling cones. The green pellets from the balling cones are fed in a prescribed feed pattern to shaft furnaces through the use of shuttle car mechanisms. The green pellets are dried, heated to 2500°F and cooled to 1200°F as they descend through the furnace and into pellet coolers where the pellets are further reduced in temperature to 250°F. Heat is recovered in the cooling process through the use of air-to-air heat exchangers. The cooled pellets discharge on a rubber conveyor belt and are transferred to 6000-ton pellet railroad loading bin. The final pellet product consists of 90% plus 1/4 in. material (after tumble testing1) and contains 66% Fe plus 3% silica.

Jan 5, 1962

By Gloyd M. Wiles

Since D. C. Jackling was famous for his adeptness at organizing and training teams of operating personnel, the subject of mine management is particularly appropriate for a Jackling Lecture. In fact, it is doubly appropriate because in very basic ways Jackling's career changed the nature of the tasks and challenges facing a mine manager. Management of mines, of course, is the art of finding and winning minerals economically from the earth's crust, and it involves the use of all the engineering sciences. But also of prime importance is a skill which is not yet a science-the area of management often referred to as human engineering. Since expenditures on staff and labor may well involve more than 50% of the direct costs of operating a mine, ability at human engineering is just as important as the ability to plan and put into effect the most efficient operating procedures.

Jan 5, 1962

By Earl L. H. Sackett

Barite, although not a glamour mineral and probably little known to many of those in the mining business, is produced in the US. in very respectable quantities and is an important factor in the mineral economy of this country. The scope of the various uses of this mineral is perhaps one of the most misunderstood things about it, for it is surprising how many of those with a casual knowledge of the subject speak of its primary utilization in terms of paint pigments and barium chemicals. The life blood of barite utilization, however, is the petroleum industry by virtue of its dependence on this high specific gravity, inert mineral as the weighting material in its drilling fluids. From 80 to 85% of barite usage in the U. S. is accounted for in this manner-in fact, its role in oil well drilling is the only excuse for some of the large-scale barite production facilities which have been developed. Other uses are important and widely varied, but comparatively they are of small scale. They include fine crushed barite of low iron content as a component in glass manufacture, barite as a source material for manufacture of barium chemicals, finely divided barite as a component of some rubbers and ground, bleached barite in pigments. The formerly substantial use of barite in lithopone, however, has declined markedly because of replacement of lithopone by titanium pigments

Jan 5, 1962

By William M. Huang, T. Carl Shelton

There are undoubtedly many factors that affect the emission of gas from coal but the permeability of coal to gas flow would seem to be fundamental. However, there is very little information on coal permeability to gas flow available in the U.S. at the present time, despite the fact that such knowledge would appear to be significant in any degasification effort. Studies made recently in the mining engineering laboratories at Virginia Polytechnic Institute have determined values of permeability on one-inch cubes of selected coals. COAL PERMEABILITY The permeability values given in this paper are based on adaptations of Darcy's Law formulated by Henry Darcy in 1856 from experiments with fluid flow in porous media.' Using air as the gaseous fiuid, they were obtained by employing similar methods as are used to determine the permeability of petroleum and gas reservoir rock specimens.

Jan 5, 1962

By Robert Stefanko

Roof bolting in coal mines has progressed very rapidly in the last decade, and today this method of support is in general use. There are many theories concerning the functions of roof bolts, but the importance of beam building is indisputable. Proper tension in the bolts minimizes shearing along bedding planes and creates a thick, competent beam from individually weak layers. Bolting must be accomplished immediately upon exposure of the roof, and bolt tension must be maintained if roof failure is to be prevented. Seams are being mined today with roof bolt support where conventional timbering was not effective1. The widespread use of continuous mining equipment was made possible by roof bolts which permit long supported spans free of obstructions.2 Since adequate anchorage is the key to successful bolting, better methods for determining the efficiency of anchorage are continually being sought. Attempts have been made to measure bolt loads, thus assessing anchorage efficiency by employing sensing devices between the bolt head and roof. 3,4,5 None of the techniques appears to be very accurate, and all have at least one serious deficiency.

Jan 5, 1962