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By J. R. Ross, J. B. Rosenbaum

Bureau of Mines research has resulted in the development of fluid- bed ion-exchange columns for recovering uranium from slime pulps. In pilot plant tests, slime slurries containing up to 6 percent solids were processed at flow rates of 10 gallons per square foot per minute with high uranium recoveries and efficient resin loadings. Uranium was effectively eluted in a laboratory fluid-bed elution column at eluate-to-resin ratios of less than 5:1 and eluate flow rates of 3 gallons per square foot per minute. Construction costs of mills using these improved ion exchange techniques are estimated to be 25 percent less than for mills using solvent extraction of clear solutions. For mills having a capacity of 2,000 to 2,500 tons of ore per day, the saving would be in the range of $2.5 million. In addition, a saving of about $0.80 per ton of ore in total operating costs is indicated.

Jan 1, 1973

By Robert G. Van Nostrand, John H. Henkel

TRANSIENT potentials obtained in resistivity prospecting can be separated into two classes. The first is electromagnetic, has a comparatively short time constant, and increases in relative amplitude as the electrode separation is increased. These electromagnetic transient potentials, of which an excellent theoretical treatment is given by Yost,1 are the result of changes in the current and can be classed as differentiated signals. The second class is electrochemical, has a comparatively long time constant, and decreases in relative amplitude as the electrode separation is increased. The electrochemical signals are generated by the current flow itself and can be classed as integrated signals. The transient potentials due to electrochemical factors are the subject of this article. The phenomenon is referred to as induced polarization. Schlumberger2 was the first worker to observe induced polarization, but he was unsuccessful in attempts to apply the principles of induced polarization in electrochemical prospecting. Other workers, notably Bleil3 have studied polarization and in some cases pointed out its possibilities, but no theory has been presented that describes polarization and its time dependence adequately. It is the purpose of this discussion to present the essence of a theory to geo- physicists and to show that it leads to results consistent with experimental evidence. The theory on which this analysis is based has existed in electro- chemical circles since 1910.4

Jan 3, 1957

By O. B. Bennett

WHEN diamond drilling was introduced in the Rhokana mines in 1939 it was used principally for pillar removal and for completion of the upper portions of shrinkage stopes which were being affected by increasing pressure. This method of drilling long blastholes proved so successful that it was extended gradually to cover stoping, pillar recovery, and hanging cave work. By 1949 virtually all the production of Mindola and Nkana was being obtained by this method. At the present time 87,500 ft are drilled each month by the 80 diamond drills in daily operation. Responsibility for control and issue of diamond drilling equipment and crowns, as well as tabulation of all performance figures, was taken over by a specially formed Roto drill department, which also investigated the problems encountered with this new method. To assist this department a fully equipped test chamber, Fig. 1, was established underground where performances of various types of machines and equipment could be studied under conditions as nearly uniform as possible.

Jan 12, 1954

Jan 1, 1954

HAVING told you about steel in the previous chapter, it seems to me necessary to speak here of brass for the same reason, for it bears the same relation to copper that steel does to iron. It is the opinion of some concerning both of these that they are true minerals because Pliny in his Natural History calls it aurichalcum and says that it has its own ore; he does not say, however, where it is found, and I have not heard from anyone else that it has been found anywhere, and, surely, if it had been found when he wrote, it would also be found today. Since I have no knowledge other than that gained through my own eyes, I tell you as a certainty that just as steel is iron converted by art into almost another kind of metal, so also brass is copper given a yellow color by art. Surely it was a splendid discovery, for which we must praise the alchemists,* although perhaps whoever discovered it was deceived, thinking that he had made gold from copper. Now, in short, this work requires infinite labor, and is carried out in various places, for instance, in Flanders, Cologne, Paris, and in many other countries, and also in the city of Milan in Italy, where I have seen a

Jan 1, 1942

By James Chapman

THE observations here presented are those, not of an expert accountant, but of one who, while he has seen considerable service in the accounting departments of large companies, has spent more time in engineering and operating. This paper is intended to cover, in a measure, mine accounting for small mines, as distinguished from the elaborate systems, requiring many persons ;n the accounting department. I shall attempt to outline a system embracing the essentials of accounting, and simple enough in form to permit one or two persons to carry it on from month to month, in sufficient detail to be able to tell quickly the grade of ore, the prices received for metals, costs per ton for mining and milling, costs per foot for development, upward or downward tendencies in costs, ore settled or in transit, cash on hand, stocks of supplies on hand, efficiency of' labor, etc. As in all accounting, there are two main divisions: that of revenue received for what is sold, and that of disbursements made for what is bought, so in mine accounting we have to consider chiefly the income derived from sales of ore or concentrates, and the expenses incurred in producing the said ore or concentrates in a marketable condition.

Jan 3, 1916

By E. Nelson Fell

As this plant is the first ever erected in British Columbia for the treatment of tailings by the cyanide process, and as the ores of this, mine are of a character not unusual among gold-ores of this Province, it is probable that a description of the principal features of the plant, and of the methods employcd in its operation, may be interesting. These works were designed after a careful study of the process, in a small experimental plant, for a period of six months. During this period ten percolation-tests on charges of tailings of 1100 lbs. each, eight percolation-tests on similar charges of concentrates, and twenty-six tests 011 concentrates in a revolving barrel, were made, besides laboratory-experiments. The ore consists of a quartz gangue, containing a little lime and variable quantities of the sulphidcs of iron, lead and zinc. The following figures, giving the analyses of the ore before milling, and of the tailings after milling, which constituted the material to be cyanided, are based on the daily samples taken during February and March, 1901.

Jan 1, 1902

By Donald M. Hausen

Microscopic evaluation of trace quantities of metalliferous phases in flotation products requires counting large numbers of particles. Particle counts of many thousands may be required for precision, but cannot be obtained practically by conventional microscopic techniques. A less tedious microscopic method for evaluating trace sulfides in mill tailings was developed for the O'okiep Mining Co. in South Africa. Hundreds of thousands of particles were evaluated by this method called "gross-counting." Gross-counting consists of counting microscopic fields rather than point-counting individual particles. Total counts are calculated by multiplying the average number of particles per field by the total number of fields examined over the entire mount. Total gross-counts range from about 20,000 particles for +200 to 100,000 or more for -400 mesh size material in lucite mounts. Sulfides and metallic particles in each field are identified and tallied along with field counts. Totals for each type of metallic particle are divided by the total gross-count to give volume percent which is corrected to weight percent by specific gravity factors.

Jan 1, 1973

By A. Bauer, P. Calder, N. H. Carr, G. R. Harris

Smallwood mine is part of the Iron Ore Company of Canada's Carol Lake operation and is situated in Labrador, 240 miles north of Sept-Iles, Quebec. Last year, 15 million tons of crude ore were crushed to yield 6.3 million tons of concentrate and pellets. This year the figures will be 17 million of crude and 7 ¼ million tons of concentrate and pellets, which is the full plant capacity. Carol Lake ores consist primarily of specularite and magnetite mixed with quartz. Since both rotary and jet piercing drills are used, it is often desirable in planning to know in which regions of the orebody, or new orebodies, a particular drill will be most economic. This makes it necessary to establish a correlation between drillability and pierceability and some physical rock property. For the rotary drills a good correlation was found with penetration rate and grinding factor index. The jet piercers were found to have a reciprocal relationship in the sense that the best rotary ground was the worst jet ground and vice versa. It is also indicated how an economic comparison could be made using these penetration rate versus grinding factor index curves, the hole size distribution curves for single pass and chambered holes, and the mine distribution curve for grinding factor index.

Jan 9, 1965

By Jack L. Lytton, Oleg D. Sherby

RESULTS of recent investigations1 on the creep of metals at high temperatures have revealed that the activation energies for creep of pure metals, AH,., about equals the respective activation energies for self-diffusion, hHD. This fact strongly suggests that the rate-controlling process in creep at high temperatures might be that of dislocation climb, as first postulated by Mott.' It would be desirable, however, to relate the creep rate of a metal at a given temperature and stress with actual diffusivity data, rather than with a comparison of the tempera-

Jan 1, 1957

PRACTICAL PROBLEMS AND BASIC PRINCIPLES ranging from ore testing to cost estimation get a working over from top men in the minerals beneficiation field. The Minerals Beneficiation Division developed this symposium for presentation at the 1953 Los Angeles General Meeting to assist the many people who think that having a new plant necessitates a lot of trouble and dismay. The papers and free discussion from the floor give ways and means of approaching a new plant that will relieve the strain on the organization, if adequate attention is put on the program before work begins - that is if thought is given to the program itself, before tackling the actual mill design.

Jan 9, 1953

By Robert H. Merrill, Raymond M. Stateham

Recently, the Denver Mining Research Center of the U.S. Bureau of Mines began tests to detect hazardous or potentially hazardous conditions in or around mines with infrared measurement devices. Among the many potential uses of infrared detection techniques are the location of misfires, underground mine fires, combustion in waste dumps, underground water courses and loose rock. However, the primary emphasis has been placed upon the detection of loose rock in roofs, pillars and faces in underground mines. The rock along the edge of an underground opening is subject to two temperature environments: the temperature of the air in the opening, and the temperature of the rock surrounding the opening. Assuming that the rock on the edge of the opening is solid, the rock will reach an equilibrium temperature that depends upon the temperature and flow of the air, the thermal conductivity of the rock and its ambient temperature. Presume that a loose rock exists among this solid rock; because there is a temperature barrier, to some extent, between the loose and the solid, the loose rock will be affected more than the solid rock by the temperature of the air. Therefore, depending upon the temperature differences between the rock and the air, the loose will be warmer or cooler than the solid.

Jan 1, 1970

By H. R. Payne, A. F. Gorton, H. A. Schwartz

In a previous paper1 we published what we believed to be a correct stable equilibrium diagram for an iron-carbon alloy containing + 1.20 per cent. silicon. The purpose of the present paper is to record the results of studies concerning the effect of silicon on the location of the eutectoid points of both systems, including also certain incidental observations of general interest. We prepared white cast irons containing roughly 21/2 per cent. carbon, 0.05 per cent. manganese, and 0.03 per cent. each of phosphorus and sulfur, but of accurately known silicon contents which varied from 0.40 to 3.32 per cent. These were completely graphitized, and both A1 points determined, as in our previous work, the specimens being converted from the stable to the metastable condition and vice versa by appropriate heat treatments. Each stable alloy was heated to a few degrees above Arl for 3 to 7 hr., quenched and analyzed for total and graphitic carbon, the difference being the "combined" or, better, agraphitic2 carbon content of the saturated solid solution just above the eutectoid transformation. One specimen was lost through accident, and the 0.40-per cent. silicon material gave an anomalous result ascribed to difficulty in maintaining the stable system in the presence of but little silicon.

Jan 1, 1923

By Henry S. Brown, Jean E. Tilden

Pyrite, pyrrhotite, chalcopyrite, and sphalerite from deposits distributed within the Piedmont and Blue Ridge provinces of North Carolina and adjacent areas were examined by atomic absorption spectrophotometry for cobalt, nickel, manganese, lead, tin, chromium, molybdenum, and gold. The ore samples were also examined petrographically. Cobalt and nickel, in general, enter pyrite and pyrrhotite rather than chalcopyrite and sphalerite. Manganese generally enters sphalerite rather than the other phases where an alternative is possible. The presence of tin in sulfide minerals was noted in a group of deposits east of the known occurrences of tin oxide (cassiterite) in the Kings Mountain belt, which may indicate the presence of a more extensive tin belt in the southeastern Piedmont than was previously recognized. Pyrrhotite from a group of four deposits in Jackson and Clay Counties, North Carolina, differs from pyrrhotite from other Ducktown-type deposits in having cobalt/ nickel ratios less than one, finer grain sizes, and colloform texture. These differences suggest that that this group of deposits has had a history different from that of the other Ducktown-type deposits studied. No significant conclusions could be made based on the distribution of lead, chromium, molybdenum, or gold.

Jan 1, 1975

By H. M. Chance

Asst. Geologist, Pennsylvania Geological Survey THE following tables have been compiled from the annual reports of the Inspectors of Mines, to determine the percentages of fatal and non-fatal casualties from roof-falls and explosions of fire-damp. As we cannot assume that every accident has been recorded by the inspectors; as many casualties terminating fatally after the lapse of a considerable period, are inevitably recorded as "non-fatal;" and as clerical errors may have crept into the compilation,* the figures of these tables cannot be considered absolutely correct, but the summary is sufficiently reliable to show the features I wish to differentiate. Under the heading a Miscellaneous" are included all accidents not directly attributable to explosions of fire-damp, roof-falls or falls of coal. Prominent among the numerous causes included under this head are premature or delayed explosion of blasts, accidental explosion of powder or cartridges, accidents from mine cars, falls in shafts, machine accidents, sliding of loose coal in pitching breasts, sltffouration by choke-damp, etc., comprising in all 48 per cent of the total number of casualties. * Compiled by Mr. Maxwell Chapman

Jan 1, 1882

By Earle E. Schumacher

THE elements silicon and germanium are not metals within the usual, intuitive association of the word, nor are they so within a stricter definition based on the electronic binding. Two properties associated with metals are plasticity and high electrical conductivity. These elements crystallize in the diamond cubic structure, an arrangement apparently not very favorable to slip, and are therefore brittle rather than ductile. Their electrical conductivity is not like that of metals the atoms are locked together by the covalent bond, which in pure and perfectly arranged material leaves but few electrons free to act as electrical carriers.† In further contrast to metals, their electrical conductivity can be greatly increased by raising the temperature. Yet silicon and germanium are not ideally nonmetallic. They are hard, solid, and possess a metallic luster. They exhibit that peculiar brand of electrical conductivity conveniently termed "semi- conduction," wherein, as shall be seen, lies much of their importance. Both, but silicon in particular, are important components in real metallic alloys and the methods of their reduction and preparation lie clearly in the province of the metallurgist. From their duality of physical and chemical properties, silicon and germanium, along with such elements as boron, diamond, gray tin, selenium, antimony, and arsenic, are considered semimetals or metalloids. Because of their importance to metallurgy and the im-

Jan 1, 1953

By R. S. Sandhu, L. E. Baker, W. Y. Shieh

The finite element method of analysis was introduced by Clough.1 Within a short period, it has developed into a powerful solution technique in structural and continuum mechanics. It has been used to solve boundary value problems in two and three-dimensional elasticity.2-5 Anisotropy and heterogeneity of materials were allowed for at the earliest stages. 1,4 Its application has been extended to allow for cracks,5 creep and viscoelasticity, 6,7 incremental construction,6-8 nonlinear elasticity3,9 effect of joints in rock,10 and to materials with different behavior in tension and compression.7 Because of its versatility, the finite element method has found increasing application in the field of rock mechanics. In fact, several of the more significant developments have been motivated by problems in this field. Elasto-plastic material behavior based on the incremental or rate-type theory of plasticity rather than the deformation theory was considered by Reyes and Deere11 A material law based on a generalization 12 of the Mohr-Coulomb criterion was used. In this chapter, the formulation of material laws developed by Reyes and Deere 11 is used. An efficient analysis procedure, incorporating recent developments in finite element analysis, is developed for plane-strain conditions. To demonstrate its effectiveness, the procedure is applied to three cases, one for which an exact solution is available, another for which field observations had been made, and a third one for which a parallel study was made, using an accepted limit-equilibrium method.

Jan 1, 1970

By William G. Pariseau

A design procedure for the quantitative estimation of support load requirements in underground mines is presented. The central problem in the design of mine support is one of es¬timating a maximum load that the ground will exert on the support in the coarse of mining. The distribution of stress around mine openings changes as mining progresses. At the time of support installation, the support load is essentially zero. With the passage of time and advance of the face, ground motion loads the support. The finite element method of analysis provides a simple quantitative technique for simulating the effects of mining and face advance on support load requirements. In particular, the maximum support load can be estimated by the proposed design procedure.

Jan 1, 1978

By H. l. Burghoff

DURING the course of preparation of crystals of alpha brass for an investigation of their creep characteristics, a number of critically oriented crystals were produced. In each of these specimens, P0, the specimen axis, lay near some important crystallographic direction or on or near the border of two possible slip systems. Because of the unusual nature of their orientations, it was considered of interest to deform these speci-mens in simple tension and to study orientation changes and any unusual occurrences, different from what would be expected for specimens in which only one slip system had distinctly the highest maximum resolved shear stress. Choice of actual operating slip system in a crystal offering an immedi-ate possibility of two slip systems would be expected to be due to chance, defect, or some inhomogeneity. Even in an ideally perfect crystal so oriented, the natural oscillations of the atoms about their lattice positions would give rise to a condition wherein one slip system would be favored over the other at the critical shear stress. In the large, nonperfect crystals of the present investigation, slip on both systems, but in different portions of the specimen, might occasionally be expected.

Jan 1, 1940

By F. P. Agterberg

It can be useful to model the mean grade values for a metal in mineral deposits containing that metal as representing the extreme value tail of a lognormal frequency distribution for the concentration values of the metal in common rocks of all types. Results for copper and zinc in the Abitibi area of the Canadian Shield are compared to results previously obtained for the Canadian Appalachian region. The lognormal model is also applied to a set of 162 large gold deposits in the Abitibi area. In the second part of the paper, 1311 large and small gold deposits in the Abitibi area are modeled as discrete events. By means of a newly developed spatial clustering model it is possible to predict the variances of random variables for frequencies of deposits in cells of different sizes.

Jan 1, 1981