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By E. C. Tveter, R. B. Tippin

The separation of minerals by heavy liquids is a standard laboratory technique which goes back at least 50 years, but commercially economic application of this principal to ore concenfration has been prevented by problems of liquid recovery. Recent investigations which demonstrate the different types of liquid-solid systems on various ores using the two major heavy liquids - methylene bromide and tetra-bromoelhane — are discussed in this article. As a result of these studies, over-all liquid recovery, and especially desorption of heavy liquid from the mineral surface, was improved by the use of surfactants as well as both thermal and mechanical energy. The examples given in the article indicate that heavy liquids which should find major commercial use in ore concentration are now available. The sink-float process using a heavy liquid medium has long been recognized as a nearly perfect method of mineral separation based on the differences in density of the minerals. The use of heavy liquid separation (HLS) offers the potential of an ore dressing method that provides the maximum possible natural concentrate grade and high recovery. In addi- tion the process requires no water, causes no waste disposal problems, and is extremely simple — the crushed ore is merely introduced into a liquid whose density is between that of the minerals to be separated. The minerals lighter than the liquid float while those heavier than the liquid sink. As such, HLS has become a standard laboratory tool but major commercial application has been prevented by the requirement for complete recovery of the heavy liquid, imposed by economics and materials handling hazards. Investigations, both in the United States and abroad, have shown that improved liquid stability as well as improved chemical engineering techniques brighten the future for HLS in ore dressing. The available commercial heavy liquids suitable for mineral separation cost from $2.00 to $20.00 per gallon1 and on this basis alone their complete recovery is economically desirable. Possibly of even greater importance is the fact that any residual heavy liquid remaining on the products could create a serious toxicity hazard. Consequently, to make the process commercially attractive requires (1) essentially complete removal of the liquid from the ore products and (2) optimum recovery of the liquid for reuse. Until recently these two stipulations have remained as obstacles but laboratory and pilot plant research now in progress suggests that these may soon be overcome. Various heavy liquid recovery systems have been proposed to meet these requirements and might be classified into one or more of the following three general classes: Solvent Wash (Fig. 1): The dissolution of the heavy liquid from the ore with a less expensive solvent,

Jan 1, 1969

By David L. Holt

It is well-established that hydrostatic pressure distribution is hardly achieved during uniaxial compaction of powders. All the previous investigations1-4 give consistent results and this variation is attributed to the die-wall friction. The conclusions are based on measurements of the density of very small portions of the compact. Although the analysis of the density or the strain distribution in the compact is very helpful in obtaining information about the stress distribution within a powder compact, it does not describe the problem from a more fundamental point of view. The densification in metal powder compacts takes place chiefly by plastic deformation (ignoring particle rearrangement) at the points of contact of the powder particles. The onset of yielding and subsequent growth of the contact areas (for spherical powders) take place fixed by a constant stress equal to three times the yield stress in tension or compression,5-7 assuming little or no work hardening. Therefore, by deforming spherical powders in the die and measuring the contact areas on each particle, the load at each contact point can be determined. In the present investigation, this was done by hot-pressing uniform spheres of lead, K-Monel, and sapphire. The details of the experiment have been described elsewhere.' The spheres were studied for the size and the number of contact points on each particle using a specially designed goniometer. It was found that the deformed faces that were approximately normal to the direction of pressing were about 2.2 times larger than those parallel to the direction of pressing. Fig. 1 shows the typical deformed sphere. A detailed study showed that the mean value of the contact areas on each sphere was within 5 pct for all the spheres in the die (ignoring those touching the die walls and the top and bottom of the die).' The spheres touching the die walls and the top and bottom of the die were found to have larger contact areas (8 to 10 pct) which indicates higher pressures in these regions of the compact and thus higher compact densities in these regions. These results show that density distribution calculated from such an experiment will give results consistent with the previous investigators. It is concluded, therefore, that the pressure distribution in the die is better understood by studying contact areas on each particle. 'R. Kamm, M. A. Steinberg, and J. Wulff: Trans. TMS-AIME, 1947, vol. 171, p. 439. 'Pol Duwez and Leo Zwell: I. Metals, 1949, vol. 1, p. 137. 'G. C. Kucynski and I. Zaplatynskyj: Trans. TMS-AIIME, 1956, vol. 206, p. 215. 'R. P. Seelig and J. Wulff: Trans. TMS-AIME, 1946, vol. 166, p. 492. 'H. Hencky: Z. Angew. Math. Mech., 1923, vol. 3, p. 241. "J. Ishlinsky: I. Appl. Math. Mech. USSR, 1944, vol. 8, p. 233. 'D. Tabor: Proc. Roy. Soc. (London), Ser. A, 1948, vol. 192, p. 247. 'Ashok K. Kakar and A. C. D. Chaklader: 1. Appl. Phys., 1967, vol. 38, p. 3223. Superplasticity in 60Zn-40Al David L. Holt THE occurrence of superplasticity in Al-Zn alloys is of interest because of its possible industrial exploitation.' The eutectoid composition (78Zn-22A1) has been the most extensively studied;'-= neck resistant flow and high strain rate sensitivity of flow stress (characteristic of superplasticity) are associated with a micron-size grain conferred on the alloy by an homo-genization and quench.5'6 Compositions away from the eutectoid have received comparatively little attention, especially from the viewpoint of relating the structural

Jan 1, 1969

By O. Jay Myers

THE war effort has furnished the necessary impetus for better magnesium foundry practice. Four or five years ago, there were but a few formulas in general use for cores and mixtures for magnesium castings. Certain sands, binders, and inhibitors were specified and the proportions of these materials in each mixture were maintained between very narrow limits. As more and more war industries entered the field, much research was carried out and methods and practices were improved. Magnesium founding is still in a state of flux; therefore it is not uncommon to find one foundry spraying inhibitors on its cores, and another foundry using sand mixtures with incorporated protective agents. The basic core or dry-sand mold mixture for magnesium in use today is compounded with sand, core oil or resin binder, cereal, and moisture. Core oil or resin binder are added for baked strength while the cereal binder and moisture are for green strength. The normal mixtures (based on the weight of the sand) contain from 0.5 to 1.5 per cent of both cereal binder and core oil, and the moisture content varies between 1.5 and 5 per cent. The ratio of core oil to cereal binder varies from 60:40 to 40:60, while the correct amount of moisture depends upon the method of coremaking. PROTECTIVE AGENTS In all magnesium practice, protective agents are used in conjunction with the core and molding sands to prevent oxidation of the metal. The use of these inhibitors is not novel, but publications covering this field are not entirely adequate. Beck1 says Magnesium alloys decompose water to form magnesium oxide, hydrogen being liberated in the process (Mg + H20 -+ H21 + MgO). This reaction results in the blackening of the skin and the appearance of areas of porosity on the casting surface, the cavities of which are filled with a grey oxide powder (these are termed `burns'). Although sand cores for magnesium castings are thoroughly dried during the baking cycle, burning will take place on the castings unless the metal is protected properly. This type of burning is more difficult to define than the "water-magnesium" reaction cited by Beck. A possible explanation may lie in the following equation: 2Mg + 02 -s 2MgO Here, the source of the oxygen is not water, but the air in the mold cavity, together with the chemically combined oxygen in the core-binding media. Generally, two methods are used to prevent this reaction from taking place.

Jan 1, 1945

By Robert E. Tally

THE membership of the American Institute of Mining and Metallurgical Engineers is composed largely of technicians, operating engineers, and executives in the mining, metallurgical and petroleum industries. The Institute also has its student, junior and associate membership and its Woman's Auxiliary. Primarily, it is a technical society, devoting itself largely to the encouragement of progress within the industries it represents, and to the discussion and dissemination of facts regarding this progress to its membership. The wisdom of this policy is reflected by the prestige and position which the society has gained, not only .among its members but throughout the entire mining world.

Jan 1, 1932

By W. W. Whitaker, C. W. Manry, R. H. McLean

In an eccentric annulus, cement may favor the widest side and bypass slower-moving mud in the narrowest side. Tendency of the cement to bypass mud is a function of the geometry of the annulus, the density and flow properties of the mud and cement and the rate of flow. Bypassing can be prevented if the pressure gradient protluced from circulation of the cement and buoyant forces exceeds the pressure gradient necessary to drive the mud through the narrowest side of the annulus at the same velocity as the cement. In the absence of buoyant forces, one requirement for this balance is maintenance of the yield strength of the cement greater than the yield strength of the mud multiplied by the maximum distance from the casing to the wall of the borehole and divided by the minimum distance. If the yield strength of the cement is below this value, bypassing of mud cannot be prevented unless buoyant forces or motion of the casing significantly aid the displacement. INTRODUCTION Successful primary cementing leaves no continuous channels of mud capable of flow during well treatment and production. Prevention of channels requires care. Tep-litz and Hassebroek provide evidence of channels of mud after primary cementing in the field.' Channeling of cement through mud in laboratory experiments has also been reported.'-' Recommendations for improving the displacement of mud include (1) centralizing the casing in the borehole,'-" 2) attaching centralizers and scratchers to the casing and moving it during displacement,18 "3) thinning the isolating the cement by plugs while it is circulated down the casing,%( (5 establishing turbulence in the cement," and (6) holding the cement slurry at least 2 lb/gal heavier than the mud and circulating the cement slurry at a very low rate of flow.' Although much has been written about the above parameters, the relative importance of each has not been well defined. In this investigation, the mechanics of mud displacement are described through results from analytical models and experiments. The model chosen — a single string of casing eccentric in a round, smooth-walled, impermeable borehole — is analagous to casing centralized in a borehole which is not round and to placing more than one string of casing in a borehole. In each, some paths for flow are more restricted than others. A fluid flowing in the borehole may seek the least restricted, or most open, path. This tendency for uneven flow can lead to channeling of cement through mud unless preventive measures are taken. The analytical models describe channeling and give means of balancing the flow. Experimental data test the analytical models and illustrate effects of motion of the casing, differences in density and mud's tendency to gel. Results are encouraging. Piston-like displacement of mud by an equal density cement slurry is possible through proper balance of the flow properties of the mud and cement slurries to the eccentricity of the annulus. The more eccentric the annulus, the thicker must be the cement relative to the mud. If proper balance is not achieved. bypassing of mud by cement cannot be prevented without assistance from motion of the casing or buoyant forces. Increasing the rate of flow can help to start all mud flowing but cannot prevent channeling of cement through slower moving mud in an eccentric annulus. Thinning the cement slurry tends to increase channeling although the extent of turbulence in the annulus may be increased. Description of flow in an eccentric annulus begins in the next section. It is assumed that (1) the casing is eccentric and is stationary, (2) the mud and cement slurries have the same density and (3) the gel structure of the mud has been broken and the mud and cement follow the Bingham flow model. Effects related to these restrictions will be discussed. FLOW PATTERNS SlNGLE FLUID IN ANNULUS Flow of a single fluid through an eccentric annulus is illustrated in Fig. 1. Part A shows laminar flow of a Newtonian fluid. This distribution of flow was calculated by Piercy, Hooper and Winney.' In fully developed turbulent flow, the velocity distribution around the annulus is less distorted, but the flow still favors the widest part of the annulus Parts B, C and D of Fig. 1 are a qualitative representation of the flow of a Bingham fluid. The yield strength of the fluid increases the severity of bypassing compared to Newtonian flow. At a very low rate of flow, all flow is confined to that portion of the annulus which has the minimum perimeter-to-area ratio. The fluid shears on the perimeter of that area when the pressure gradient multiplied by the area just exceeds the yield stress of the fluid multiplied by the perimeter. Whether or not the minimum perimeter-to-area region encompasses all of the annulus or only a part (as shown in Part B) depends on the geometry of the annulus. If only a part begins to flow, increasing the rate of flow increases the area flowing until finally there is flow throughout the annulus.

Jan 1, 1933

By Oliver Bowles

Two striking events marked the year 1871-the establishment of the A.I.M.E. and the beginning of the portland cement industry, the most spectacular of all the nonmetallics in its development. Just as David Saylor's first portland cement, made in a little mill at Allentown, Pa., in that year was the forerunner of a mighty industry, the products of which in 1942 were made in 155 plants scattered throughout the country (having attained a value of nearly $300,000,000), so the Institute from its small beginning has attained a membership of many thousands, likewise decentralized into a series of individual sections of wide geographical distribution. Concurrent with the establishment of the Institute was also the invention of the steam drill, followed by the compressed-air drill about 1904. These mechanical drills were so immeasurably in advance of the hand drill and hammer used previously that quarrying and mining of present-day magnitude could never have been attained without them. Some outstanding occurrences have marked this eventful three quarters of a century. The concrete age, with its enormous demands for cement, aggregates and steel, is of primary importance. Of interest also is the shift of fertilizers from the organic to the mineral field. Nitrates, primarily obtained

Jan 1, 1947

By H. J. Wasson

DEVELOPMENTS in Venezuela during the past few months have been obscured by the hap-penings in Seminole and, more recently, those in southwest Texas. The question has been asked whether or not the opening of these vast new, prolific areas in the United States may not have depressed prices to a point so low as to give the developments in the Caribbean countries a serious setback. Nothing of the kind, however, has taken place, and on the contrary, there has been demonstrated the fact that Venezuela can profitably produce great quantities of oil under existing market conditions, and at the same time finance the foundation for further large expan-sion in the future. The three big factors which contribute to place Venezuela in a unique position and tend to insure the steady expansion of its oil industry are, in the order of their importance: I. Reasonable oil laws backed by a sound govern-ment, which comprehends the all-important fact that the country's prosperity depends on the prosperity of its industries, in a word, perceiving that the goose which lays the golden egg merits considerate treatment. II. The low cost of placing Venezuela oil on our At-lantic seaboard; not over $0.60 per barrel. III. The uniformly high average production per well and the large area of some of the individual pools. Under these conditions Venezuelan producers may be expected to continue steady and profitable ex-pansion even in the face of further market slumps. Their position is analogous to that of the low-cost copper producers, and unless artificial barriers, such as tariffs, come into play, Venezuela will steadily grow in importance. Within less than five years it should be second only to the United States among the oil-producing countries of the world.

Jan 10, 1927

Jan 1, 1926

By B. P. Canning

In recent years much attention has been given to comminution theory and the design of crushing and grinding installations in large plants. The day of the small plant is not over, however, and we will attempt to analyze some cost aspects of conventional plant design, particular to their smallness. Small plants generally have the same design requirements as large plants, however, certain additional restraints are imposed which generally reduce efficiency and availability. The engineer must take particular note of these restraints in order to properly design crushing and grinding installations for these plants. Whatever equipment is selected for small plant crushing and grinding circuits, it is more costly on a per-ton capacity basis than for a large plant. Circuit Design Small crushing and grinding circuits of recent design usually are of one-line concept utilizing simplified flowsheets. This is the logical outcome of a cost evaluation excluding special considerations and is the basis of the circuit design discussion and cost evaluation which follows. Objections to the one-line concept have been voiced with arguments claiming little flexibility, low availability, higher disaster risk, etc., however, experience has proven these arguments not to be convincing. Equipment of sufficient capacity is available on the market for all normal applications up to the 4000 mtpd plant size here considered and the engineer has complete freedom of choice. Where separate treatment of ores is required, the single-line plant concept requires adequate ore storage be provided with facilities for clean-out between campaigns on one or the other ores. It is very difficult to justify parallel crushing and grinding sections for small plants as material handling is more difficult with small flows involved, and equipment costs become significantly higher. Cost Evaluation Criteria In order to evaluate the small plant comminution circuit on a cost-effectiveness basis, a test model is here established for a comparison basis. Although it is recognized that the parameters chosen will fit only certain metal mining applications, the cost trends should provide useful information for other applications. The test model used is a one-line comminution circuit which considers maximum space utilization in an all-enclosed plant. Plant feed is assumed to be 90 percent passing 12 in. with nominal maximum rock size

Jan 1, 1982

By Edward Keller

THE ASSAY FOR COPPER. SOMEONE some time ago remarked that some chemists still insist on telling us how to determine copper by the electrolytic method. The. writer must confess that he believes that everything is not known definitely as yet as to how the exact amount of copper is determined in such material as purest commercial electrolytic copper. Some of us are not yet convinced that the pure copper atom is at all times deposited from an acid solution and that no oxygen or hydrogen will, under certain conditions, accompany it. Difficulties with impurer material are frequent, but erroneous results are not always apparent, since these do not speak so readily for themselves as those in the first case. By this is meant that if a chemist finds 100 per cent. of copper in electrolytic copper it is pretty certain that he perceives the result to be wrong, while if he finds 0.1 per cent. of copper too much in a very impure material he is far more likely to be unconscious of his error. These, in a wide experience, are frequent happenings and the writer has always looked with interest to publications on this subject. In turn, he :feels justified in giving to others a few of his own observations. Up to a few years ago there were two methods of electrolytic copper assay in technical use, which had in common, that the amount of copper deposited on the cathode did not exceed 2 g., and they differed in that, for the one a large sample 1 (20 to 80 g.) was taken from the general sample by a splitting device, dissolved, and from the solution a small portion (to contain 1 or 2, g. of copper) measured out for the electrolytic deposition; in the other Method the copper was determined, generally in 1-g. portions of the separated coarse and fine portions of the sample, all of which passed -a 16 or 20-mesh screen, being accomplished by a 40-mesh screen,

Jan 8, 1913

By W. M. Parris, P. D. Frost, H. A. Robinson

The effects of hydrogen content and strain rate on the static tensile and notch-rupture properties of the Ti-3Mn-complex alloy heat-treated to differed strength levels were investigated. The extent of embriulement was found to be proportional to the amount of hydrogen present and the strength to which the specimens were heat-treated. The research suggests the possible necessity of specifying lower hydrogen limits than are now allowed when titanium alloys are heat-treated to higher strengths than are presently used. The research also supports a hypothesis advanced earlier for a mechanism of hydrogen embrittlement. MUCH attention has been focused on the effects of hydrogen in in Most of the published in- formation has dealt with the effects of hydrogen on alloys in the annealed or lowest-strength condition. The work of Kotfila and Erbin3 is one of the few exceptions. In view of the fact that heat-treatments are now being used to produce high strength in titanium alloys,' it is necessary that more attention be given to the effects of hydrogen on these alloys in the heat-treated condition. Research was initiated to establish the effects of hydrogen on the properties of the Ti-3Mn-complex alloy at various strength levels. This research, which supplemented that of Kotfila and Erbin, was started because it was found that high-strength tensile specimens of this alloy were strain-rate sensitive. The essential results of the research are summarized in this paper. MATERIALS AND EXPERIMENTAL PROCEDURES Material for this investigation was a 41/2-in.-diam bar forged from a single commercial heat of the Ti-3Mn-complex alloy having the composition given in Table I. The as-received forging was reduced further by forging at 1750°F to 3/4-in. square bars. About one fourth of this material was vacuum annealed at 1400°F for 24 hr to obtain a base hydrogen content of 25 ppm. The remaining bars were hydrogenated to levels of 90, 140, and 260 ppm in a large Sievert's apparatus in the following manner: Four 3/4-in. square bars, 5 in. long, were placed in the reaction chambzr. The chamber was evacuated, heated to 1400°F, and a measured amount of hydrogen was introduced. When absorbtion was complete, as indicated by the drop in pressure, the reaction tube was cooled and the bars removed. Each batch of bars was then sealed in individual evacuated Vycor containers and heated for 24 hr at 1400°F in order to distribute the hydrogen homogeneously. After vacuum-annealing or hydroge nation, the bars were rolled at a temperature (1400°F) below the ß-transus to 1/2 - in. - diam rounds. Groups of the rolled specimens representing each of the hydrogen levels were given the following heat-treatments: 1) One hr at 1300°F, water-quenched. 2) One hr at 1300°F, water-quenched, and aged 8 hr at 1100°F. 3) One hr at 1300°F, water-quenched, and aged 4 hr at 1000°F. 4) One hr at 1300°F, water-quenched, and aged 48hr at 800°F. Heat-treated bars were machined into standard 0.250-in.-diam tensile specimens having 1-in. gage lengths. Throughout the processing and testing of this material, hydrogen analyses were made by vacuum-fusion methods to check for accuracy of hydrogen additions, homogeneity, and possible losses during processing. A summary of these analyses is given in Table II It may be seen that the actual hydrogen contents were reasonably close to the desired levels. In addition, it was noted that the variation in hydrogen content within any one bar did not exceed

Jan 1, 1959

By Gordon M. Matheson, Charles V. Logie

The current state-of-the-art design of mine pillars can be grouped into empirical and numerical design techniques. Numerical design techniques are based on sophisticated computational techniques which analyze the stresses and strains through the interstices of a pillar. Empirical techniques are less exact, but have been widely used, particularly for coal mine pillar design, because of their ease of computation. Over the years numerous empirical equations have been proposed to calculate the ultimate strength of coal mine pillars. This paper presents a review of the various equations which are most frequently utilized and examines the fundamental assumptions, limitations and applicability of the design formulae. The review intends to provide the practicing mining engineer with an understanding of the assumptions and mathematical basis of each equation to aid in the selection of the criteria most applicable to his specific design problems. Recommendations are made of the empirical equations that are presently most acceptable for design.

Jan 1, 1983

By D. S. Bloom

RECENTLY a report has been published on an investigation of the MO-RU system by E. Raub.' In this report it is stated that below approximately 1200°C the system consists of two terminal solid-solution phases and the intervening two-phase field; at 1200°C and above, an intermetallic compound labeled Mo,Ru, makes an appearance. Along with some other little known systems in which it was considered possible for a u phase to form, the Mo-Ru system had been under investigation in this laboratory. Since molybdenum and ruthenium have very high melting points and also since ruthenium is expensive, the investigation was confined to X-ray diffraction by sintered powder compacts. The compositions which were studied were (in atomic percentages): 75 Mo-25 Ru, 67 Mo-33 Ru, 50 Mo-50 Ru, and 25 Mo-75 Ru. All compacts were made from the pure powders, and no chemical analyses were attempted. Each compact weighed about 5 g. All annealing was done in evacuated Vycor capsules, and even though the capsules completely collapsed at 1250°C, they still admitted no air. The results of this investigation in general corroborate the work of Raub. Up to 1150°C the two terminal solutions and the intervening two-phase field were found, and at 1200°C and above an intermetallic compound was found. However, the composition limits of the compound were estimated to lie close to 70 atomic pct Mo rather than 62.5 atomic pct Mo as Raub had reported. At least the X-ray diffraction results indicated that the 75 atomic pct Mo specimen consisted of the molybdenum solid solution plus the compound, while the 67 atomic pct Mo specimen consisted of the ruthenium solid solution plus the compound and the equiatomic composition contained only very little of the compound. The most interesting observation, however, was that the diffraction pattern of the compound was similar to that of the well known u phases, except that unusually large lattice constants were indicated. The d-values, or interplanar spacings, of the diffraction lines (as produced by filtered copper KCX radiation) of the compound are given in Table I, as determined from specimens annealed at 1250°C for 9 hr and then quenched in water. Also shown are the lines of the Mn-Mo u phase as given by Decker, Waterstrat, and Kasper,' the lines of the Fe-Mo a as given by Goldschmidt," and the lines of the Mo-Ru phase multiplied by constants in order to make comparison with the Mn-Mo and Fe-Mo patterns easier. These results indicate that the compound in the Mo-Ru system is apparently isomorphous with the other o- compounds. The rather large lattice constants of the Mo-Ru a phase are acceptable in view of the comparatively large size of the constituent atoms. The data in Table I for the Mo-Ru compound check quite well with those given by Raub, not shown here, though there are some discrepancies between the two sets of data in the estimated intensities of a few lines. Although very little is known at present about this u phase, there are some things which may be pointed out, mainly in comparison with other better known u phases. Even though molybdenum and ruthenium are in the same columns in the Table of Elements as chromium and iron, respectively, the Mo-Ru u phase contains much more molybdenum than ruthenium, while the Cr-Fe u phase centers around or very nearly around the equiatomic composition; furthermore, the Mo-Ru u is stable only above approximately 1200°C, but the Cr-Fe u is stable only below about 825 °C. With respect to its being unstable below 1200°C, the Mo-Ru u is similar to the other binary molybdenum u phases in the Co-Mo and Fe-Mo systems. Similar to the latter two systems, the Mo-Ru u apparently exists over a rather narrow composition range, whereas the Cr-Fe u at lower temperatures is stable over a much wider composition range. The Mo-Ru u thus is closer to the other molybdenum u phases than to the Cr-Fe cr phase. The most striking feature of the Mo-Ru u phase, however, is the absence of any of the transition elements of the First Long Period.

Jan 1, 1956

Jan 1, 1927

By Dennis V. D’Andrea, Larry R. Fletcher, Peter G. Chamberlain

The evaluation of potential in situ copper leaching deposits requires a thorough examination of the geologic, mineralogic, hydrologic and physiological characteristics of the ore body. The decision to develop the deposit is made with these data along with leaching properties, estimated copper recovery, and economic analysis. A test blast followed by pilot leaching can a so be used for further evaluation and to reduce uncertainty regarding the deposit's potential. This report describes a number of ground characterization techniques that can be used to evaluate potential deposits. Field methods include geologic mapping, groundwater hydrology, core drilling, geophysical logs, permeability testing, and in-situ stress measurements while laboratory tests include assaying, mineralogy, leaching, rock physical properties, size analysis, and computer simulation.

Jan 1, 1980

By B. A. Chomyn, P. Lapointe

Current work within the Magnetic Properties Task of the Canadian Nuclear Fuel Waste Management Program has indicated that a relation exists between the measured bulk magnetic susceptibility and fracture and lithological characteristics of granitic cores from the Lac du Bonnet batholith in Manitoba. Susceptibility minima correspond to fractured and associated altered rock; uniform background levels coincide with unaltered, non-fractured homogeneous rock; and susceptibility maxima denote the presence of xenoliths and intervals of core containing large and coarse-grained magnetic minerals. The observed variation in bulk susceptibility is largely controlled by the gram size and the relative abundance of iron-titanium oxide minerals of which magnetite is the most important. The magnetic minerals occur as monomineralic grains of magnetite and hematite, as aggregates of magnetite and ilmenite, hematite and ilmenite and as examples of either of these two categories but exhibiting evidence of oxidation and alteration. The degree of alteration of the oxides is commensurate with the alteration of the enclosing rocks. Susceptibility minima characteristic of fractured rock reflect decreases in oxide gram size and abundance, as a result of the oxidation of magnetite to hematite and the development of titanium-rich phases. Correlations between boreholes indicate the possibility of continuous fracture zones at 80 m and 150 m from the surface and another one at a greater depth.

Jan 1, 1984

By Leonid Bryner

For many years, geologists have inferred a connection between the evolution of the earth's crust and ore deposition, a connection coming under the heading of metallogeny. In recent years the concept of metallogeny has assumed major importance in the exploration planning of Russian geologists in their quest for new mineral sources. As defined by Radkevich, metallogeny is "the science which studies the laws governing the distribution of ore deposits in the earth's crust." However, since it can be argued that metallogeny does not contain enough certitude to be classified as a "science," it would be more appropriately defined as the study of metallogenic provinces, and metallogenic epochs.

Jan 6, 1963

By M. G. Corson

Information regarding the use of ixanganese alloys has hitherto been incomplete and available only from widely scattered sources. This paper attempts a systematic description of properties and uses of alloys other than manganese bronze, manganin and duralumin, which are probably the only non-ferrous alloys associated with manganese in the minds of most metallurgists. Properties of Manganese Manganese can react either acid or basic; it is hard to obtain in the pure state; it has two different crystalline lattice structures, both of the cubic system, one stable above 850" C. and the other below 650" C., both coexisting in the intermediate range. Although the commercial product is hard and brittle, the pure metal seems to be ductile. In fact Zhemchuzhny, in Russia, was able to obtain ductile manganese and draw it to fine wires by the simple expedient of adding about 3 per cent. copper to the alumino-thermic product. Copper most probably brings the sili-cides, aluminides, nitrides and carbides present in the commercial product into a much less harmful form of distribution. One industrial use that can be foreseen for wrought manganese articles is as anodes for electrolytic processes in sulfate and nitrate solutions, particularly with high voltages. A practically insoluble skin of manganese peroxide is likely to form in such cases and an insoluble and strong anode material will be available. Manganese as a Scavengek Because of its activity manganese might become the most efficient scavenger and refiner of copper, were it not for the fact that 0.01 per cent.

By Andrew S. McCreath

The manufacture of pig iron for conversion into steel by the Bessemer and open-hearth processes, is now one of the most important industries of the United States. It is necessary that iron intended for this purpose should be very pure, and especially must it be comparatively free from phosphorus. Great care must therefore he exercised in the selection of proper ores, flux, and fuel. Only such ores as are practically free from phosphorus can be used, and pure fuel is as much a necessity as pure ores; though hitherto iron men have paid comparatively little attention to this point. During the course of my work as chemist for the Second Geological Survey of Pennsylvania, I' had occasion to examine some of the bituminous coals of the State fix phosphorus, and the results obtained are so interesting that I venture to present them to the notice of the members of the Institute. The coals are arranged in geological order according to the different beds, and the table shows the percentage of phosphorus in the coal and also in the coke. The greatest number of specimens have been selected from the Pittsburgh bed, because it is the principal coal-bed of Southwestern Pennsylvania, and most of the mineral fuel which is mined along the Youghiogheny and Monongahela rivers, to be used in the coke ovens of the Connellsville region and in the blast furnaces and mills of Pittsburgh and its vicinity, and to be shipped to Western and Southern markets, comes from this bed. It will be noticed that many of the specimens examined contain

Jan 1, 1880