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By B. J. Dotson, P. N. McCreery, R. L. Slobod, James W. Spurlock

A core sample porosity-check program is described. A number of laboratories participated in the investigation. which comprised measuring the porosities of ten selected natural and synthetic core samples. Each laboratory employed its own method (or methods) of measurement. These included Boyle's Law, water-saturation. and organic liquid-saturation methods. Brief descriptions of each method employed are given. In general, the measured values of porosity were in reasonably good agreement. The average deviation of porosity from the mean or average values for the group of samples was ±0.5 porosity per cent. The results of these measurements are compiled and presented in graphical form. INTRODUCTION The total hulk volume of a porous sample is derived from the sum of two volumes, the void or pore volume and the solid* or grain volume. The porosity fraction of the sample ia defined as the ratio of the void volume to the bulk volume. Multiplication of this ratio by 100 converts it to per cent porosity. Distinction is made here between total porosity and effective porosity. The former includes all void space, both interconnected and isolated, while the latter includes only those voids which are interconnected. This investigation deals only with the effective porosity.* Numerous cases had been noticed in which there appeared to be appreciable discrepancies in the results of porosity determinations on core samples. Differences of as much as 10 to 15 porosity per cent had been reported from different sources

Jan 1, 1951

By Robert L. Grayson, Y. J. Wang, R. Mike Mishra

Prediction of ventilation needs in long range mining projections requires serious consideration when formulating those projections. Predicting the behavior of the ventilation system of an old, complex mine poses an especially provocative problem. Air-flow around and through mined-out areas via bleeder systems, leakage flows through stoppings or other air control devices, and the use of multiple fans all add to the basic complexity of a ventilation system and make predictions of ventilation changes very difficult. Fortunately, the task of making ventilation decisions can be greatly assisted by ventilation surveying and computer simulation. The Nemacolin Mine of Jones and Laughlin Steel Corporation, located in Southwestern Pennsylvania, is one such old mine which used the computerized approach successfully. A mine-wide pressure-quantity survey was used to obtain realistic values for airway resistance factors. These values, together with network topology, formed the basic input for computer simulation. Results from this simulation indicated that air quantities generated at critical airways by the model were generally within a couple of percent of those measured in the actual survey. It was then concluded that the model was acceptable for practical application, and it was used immediately for studying the effects on the ventilation system of changing the blade settings of fans. Additionally, the model was modified to incorporate projected mine development and used to predict future ventilation.

Jan 1, 1982

By D. C. Seidel, E. F. Fitzhugh

Nickel sulfide ores lend themselves readily to concentration before smelting or pressure leaching, but neither of the major oxidized ore types-the iron-rich laterites and magnesium-rich, soft silicates-has been directly concentrated. Upgrading of crude ore in current practice is limited to cobbing lumps of the harder, lower grade rock (protore) from the softer, enriched silicate ore, because only a small percentage of the nickel in these ores occurs in discrete, contrasting mineral particles. There is no apparent mineralogical contrast in the superficial, iron-rich lateritic ores and, in fact, there is no firm assurance that the nickel atoms are within the lattices of the limonite minerals, or else irregularly adsorbed on the limonite. Within underlying, "rotten rock" silicates, occasional veinlets of garnierite and related nickeliferous silicates are found.1 The garnierite veinlets are only incidental, and the majority of the nickel atoms occur as erratic replacements of magnesium atoms in the micaceous chlorites of the ore mass.

Jan 4, 1968

By R. Van A. Norris

The following tests were made, during 1889, for the Susquehanna Coal Company, to determine the relative efficiency of several styles of mine-car wheels in use at their collieries at Nanticoke, Pa. The wheels experimented upon may be divided into two classes: The "old style" (Figs. 1 and 2), which are oiled at every trip; and the "new style" (Figs. 3, 4, and 5), which require oiling about once in two to four months. Fig. 1 shows a section of a plain cast wheel, with patent annular oil-chamber. This is held in position on the axle by a square, split cotter-pin. Fig. 2 is a similar wheel, with a patent cast bushing, which is readily replaced when worn. The lubrication is effected by a simple oil-hole, but the oil is delivered a little inside of the gaugeline of the wheel, where it is most needed. Figs. 3, 4, and 5 are sections of a " new style " patented, self-oiling wheel. In this, the outer end is cast closed, and the wheel is fastened to the axle by a spring cotter-pin passed through one of the plugged holes. Dirt is prevented from entering the open end by a cap, with faced end and packing-ring, fitting over the end of the hub. The lubricant is introduced into the oil-chamber through one of the plugged holes in the hub. When the wheel is in motion, the lubricant is thrown by centrifugal force away from the axle, enters the two ports shown, and is

Jan 1, 1890

By H. R. Thresh, A. F. Crawley, D. W. G. White

The densities of liquid tin, lead, and Sn-Pb alloys have been measured over a range of temperature above the liquidus. In all cases, data can be adequately represented by an equation of the type p = a + bT. For pure tin, the values of a and b are, respectively, 7.139 and 7.125 x 10-4, and for pure lead, 11.060 and 12.220 x 10-4. At constant temperature, molar volumes in the Sn-Pb system vary linearly with composition. DURING the course of a long-term program at the Department of Energy, Mines and Resources, Ottawa, Canada, the densities of liquid tin, lead, and Pb-Sn alloys were studied. The work reported herein draws on two sets of results independently achieved by Thresh, on the one hand, and by Crawley and White, on the other. EXPERIMENT The method and apparatus were originated by Thresh and have been described in detail in Mines Branch reports.172 In operation, the 14 cu cm graphite pycnometer is put in the furnace as shown in Fig. 1 after a machined charge has been placed inside the pycnometer and the lid screwed down. The dimensions of the charge are such that, upon melting, a small excess of liquid metal is discharged through the capillary hole to displace the weighted float above. When the pycnometer has been equilibrated at the experimental temperature, the

Jan 1, 1969

By Richard Moldenke

In crowding the recent mass of work on the physics of cast-iron into the compass of a short review, I cannot do better than to follow the lines of Mr. W. R. Webster's suggestion, made at the Florida meeting of the Institute, March, 1895.' The classification of the properties of the metal, and the influences to which it is subjected during the various processes it undergoes, is quite complete; and as Mr. Webster gives it again in full in another paper at the present meeting, a simple reference to it now will be sufficient. I. Correspondence Between Chemical Composition, and Melting-Point, Fluidity, Shrinkage, Fracture,Chill, Micro-Structure, and Other Physical Properties. Melting-Point.—The melting-point of cast-iron had long been a subject of controversy among foundrymen. They knew that a hard iron melted faster than a soft one, but this effect was occasionally disputed, and the reasons given were unsatisfactory; but could not be well controverted. It was my good fortune to take the actual melting-temperatures of some 70 pig-irons and castings; the Le Chatelier pyrometer, suitably protected, being introduced into the interior, and the iron melted off in a specially-constructed cupola. The irons had been previously analyzed by taking the borings at the point of the intro-

Jan 1, 1905

By Henry D. Hibbard

Henry D. HibbaRd, Pittsburgh, Pa,: This is a most interesting and instructive paper, some of whose lessons should find immediate application. It points out how fuel-consumption is to be decreased in open-hearth practice, by changes in the plan of the furnace. To look first at the greatest item of loss, radiation, it is seen that thicker brick-work is advisable to lessen this. Especially is this true of the roof, made at present, almost universally, only 9 inches thick to prevent cutting. Now that high roofs, well above the course of the flame, are becoming general, and the average melter is better able to judge the temperature of his furnace, that reason has less force; and we may build roofs 18 inches thick, or perhaps better cover the usual 9 inches with an equivalent layer of sand, which has the advantage of following the arch as it rises and falls with the different degrees of heat. The side-walls of the hearth, usually 131/2 inches thick, may also he thickened up to 18 inches, and the door-linings to 7 inches; and the heat thereby saved will be valuable, while its absence from the working-platform will be much appreciated by the workmen.

Jan 1, 1892

By M. J. Shulman

With the spiraling cost of exploration, all stages of exploration must be optimized. Search theory calculates the optimal distribution of effort by maximizing the probability of discovery under the constraint that the total exploration budget is not exceeded. It may help formulate strategies during the reconnaissance phase of exploration. An incremental optimization analogous to the exact solution of the search problem is introduced. In conjunction with the optimization, various stopping criteria can be defined. The stopping criteria terminate exploration in an area during a particular stage. It does not refer to abandoning exploration. The following stopping criteria were considered: the exploration effort in an area should not exceed a maximum value; the posterior target location probabilities should not be less than a percentage of the initial probabilities; the change in the posterior target location probabilities should not be less than a given value; and the change in the marginal rate of return should not be less than a given value. The incremental optimization and the stopping criteria are used to allocate reconnaissance mapping and sampling effort for phosphorite in the Sinai Peninsula, Egypt.

Jan 1, 1986

By R. P. Steijn

IT has been observed by a number of investigators that under certain conditions metals freeze into an aggregate of small hexagonal strands, parallel to one another and with their axes approximately in the direction of growth.'" This structure has been termed "cellular structure" and is explained in various ways by different workers, notably by Rutter and Chalmers." These investigators attribute the phenomenon to the presence of minute quantities of solute atoms which induce constitutional supercooling. However, if this is true, observations of the cellular structure in extremely pure substances, like frozen distilled water' and germanium of less than 0.0001 atomic pct metallic solute,' are difficult to comprehend. The purpose of this communication is to describe several observations made of the prismatic structure in zinc of 99.99 pct purity. Zinc single and bicrystals grown in a constant gradient electrical resistance furnace exhibit the cellular structure after etching in 15 pct HC1. (See Figs. 1 and 2.) It is noticed that the hexagonal substructure sometimes continues unbroken across the bicrystalline grain boundary.

Jan 1, 1956

By P. N. McCreery, R. L. Slobod, B. J. Dotson, James W. Spurlock

A core sample porosity-check program is described. A number of laboratories participated in the investigation. which comprised measuring the porosities of ten selected natural and synthetic core samples. Each laboratory employed its own method (or methods) of measurement. These included Boyle's Law, water-saturation. and organic liquid-saturation methods. Brief descriptions of each method employed are given. In general, the measured values of porosity were in reasonably good agreement. The average deviation of porosity from the mean or average values for the group of samples was ±0.5 porosity per cent. The results of these measurements are compiled and presented in graphical form. INTRODUCTION The total hulk volume of a porous sample is derived from the sum of two volumes, the void or pore volume and the solid* or grain volume. The porosity fraction of the sample ia defined as the ratio of the void volume to the bulk volume. Multiplication of this ratio by 100 converts it to per cent porosity. Distinction is made here between total porosity and effective porosity. The former includes all void space, both interconnected and isolated, while the latter includes only those voids which are interconnected. This investigation deals only with the effective porosity.* Numerous cases had been noticed in which there appeared to be appreciable discrepancies in the results of porosity determinations on core samples. Differences of as much as 10 to 15 porosity per cent had been reported from different sources

Jan 1, 1951

By C. D. Broadbent

Open pit blasting can be a low cost routine or a high cost bottleneck depending on geology, environment and the operator's ability to master site conditions. Because blasting is a repetitive operation, there should be ample opportunity to optimize the process; but ordinarily this optimization is rarely achieved and then only if conditions remain consistent and predictable. Often, however, and particularly with porphyry coppers, hidden differences in rock characteristics nullify the operator's best efforts. At a porphyry copper deposit being mined by Kennecott Copper Corporation, all of the following rock types occur; oxidized and fresh porphyry, altered and silicified limestone, explosion breccia, rhyolite, sandstone, shale and several others. The units can cover large areas or be limited to a few tens of feet in maximum dimension. They are rarely visible on the bench surface and often do not show up in the bench slope. Even though the blastability of these rocks varies substantially, a generally-uniform blasting pattern was formerly used with disappointing results. Secondary blasting was often required and high bottoms occurred frequently, overblasting wasted drilling time, and explosives caused excessive throw.

Jan 4, 1974

By A. L. Field

Previous Publications THE first report on the slag viscosity work of the Bureau of Mines was made by one of the authors 1 in 1916. It was concerned chiefly with, the method of measurement. A paper 2 on this phase of the work was presented to the Institute in February, 1917, and a similar paper 3 was communicated to the Faraday Society. Purpose and Scope of the Slag Viscosity Tables Following the development of a suitable method, the next step in the investigation was the measurement of slag viscosity over a wide range of temperature and composition, and the arrangement of this experimental data in the form of tables for the use of the blast-furnace operator. It is believed that this information, if used intelligently, should help the operator to reduce losses in production caused by off-grade pig iron, to improve fuel economy, to promote operating efficiency, and to extend present-day practice to meet the increasing need of smelting lean and complex ores. In the experimental part of the work it was early observed that the temperature-viscosity relations of a slag were determined, for practical purposes, by the relative proportions of the three major constituents, lime (CaO), alumina (Al203), and silica (Si02), provided the percentage

Jan 12, 1917

By Axel Sahlin

The day is long past when linen and cotton rags were the exclusive raw material of the paper-trade. Wood-fiber, chemically or mechanically prepared, straw, hemp and Esparto grass have largely supplied the demand, which the old materials did not suffice to fill. But even these newer fibers have been of late supplanted, to some extent, by mineral pulp. Weighting and filling materials have also been resorted to, partly to give body to the fabric, partly to increase its weight and reduce the cost per pound. China clay, sulphate of lime and soapstone have generally been employed as loading materials. Even though these materials lack fiber, their addition must by no means be viewed, as it too generally is, entirely as an adulteration. No doubt, to a certain extent, they weaken the paper ; but for ordinary grades the addition of these non-fibrous substances is a positive advantage, as they close the pores between the fibers and lend to the paper a great degree of opaqueness and a superior finish. Fibrous talc, as a form of pulp, has the same effect, without appreciably weakening the paper. When, therefore, some fifteen years ago, fibrous talc in large quantities, and of marvellous purity and whiteness, was discovered in the neighborhood of the town of Gouverneur, it was not long before the

Jan 1, 1893

By F. T. Davis

The annual review of mineral dressing was the subject of considerable discussion at the MBD meeting in New York last February. Because the amount of material now being published is so imposing, it was generally agreed that reviewers should try only to cite the items of importance. In order to conserve even more space, it was agreed to omit bibliographies. In reading these reviews, and those of the past two or three years, one is impressed by the advances in materials handling, the enlargement and the advances in automation of unit process equipment. Although there has been development of a variety of new concentration principles in flotation, magnetic separation, et al., the design of these principles into new plants has not been widespread. The probable reason is that the plants being built today are so large and costly that few are able to face the risk of any significant degree of experimentation. There are exceptions to this; for example, some of the chemical processes, but these are usually because there was no conventional process available. This situation should change in time as the ores amenable to our conventional methods become depleted.

Jan 2, 1967

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 Charles E. Johnston

By substituting photoelectric automatic car loading for mechanically induced hydraulic automatic loading and by protecting the process against operational failures, the engineering staff at International Minerals & Chemical Corp.'s Carlsbad potash mine has developed a reliable loading process that operates without an attendant. The photoelectric control, developed primarily because of frequent failures in the hydraulic control system, has not changed the basic loading operation and physical layout. Mine-run ore ranging in size from minus 200 mesh to 30-in. lumps is dumped onto a conveyor belt which discharges into a so-called "flop gate chute" which in turn, feeds the ore into six-ton capacity mine cars. Each car is filled progressively by moving the entire trip forward. When a car is filled 12 in. above its rim, the direction of flow into the car is reversed 180º and filling of the next car back is begun while the entire trip is moved forward again. Once the next car is properly spotted under the front chute, the flow is again directed to the forward position.

Jan 9, 1962

By G. A. Koenig, Moritz Stockder

Locality and Geological Occurrence. The Alpine region of Southwest Colorado, comprising the San Juan and Uncompaghre Mountains, is composed of a deeply eroded sheet of acid eruptive rocks, overlying in part gneissic sehists, and in part limestones and sandstones, including portions of the Silurian, Devonian, and Carboniferous systems. The section is clearly and beautifully exposed along the Uncompaghre River from its headwaters to its exit from the mountains. The river's course from the town of Ouray towards the Los Pinos agency is due north, and four miles from Ouray, in this direction, the Uncompaghre receives from the east the Red Cafion Creek. Following up the narrow caftan we find the section through white.. sandstone in strata dipping to the north and west, and belonging either to the lower or middle Devonian system. Presently the steep cafion-liko character of the ravine gives place to more gentle slopes, and we have entered crystalline rock-porphyry. The contact is well marked, for the sandstone, to a depth of from six to ten feet, resembles quartzite, i. e., is semifused. Ascending still higher, a small

Jan 1, 1881

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 J. S. Bowles

DISCUSSION, M. Cohen presiding J. W. Christian (The Inorganic Chemistry Laboratory, oxford, Englandl)—I was very interested in Dr. Bowles' results on the suppression of the transformation by solid films of alcohol or propane. The transformation in cobalt, which is also martensitic, can be explained by a mechanism involving the reflection of "half dislocations" down a series of atomic planes.* This reflection process is similar to that considered by Frank13 for plastic deformation on a single slip plane and, as he pointed out, reflection would be impossible if the metal were immersed in a liquid of higher density. It seems possible that solid films of alcohol have a similar effect on the lithium transformation. Reflection should also be possible at a grain boundary, though a higher kinetic energy of the dislocation, and hence a lower temperature would be required. As Dr. Bowles used coarse grained polycrystalline speci- mens, transformation on cooling should still have occurred in grains which did not form part of the outside (free surface) of the metal. This may account for the X-ray lines of the low temperature phase which were found. There is thus the interesting possibility that in a polycrystalline specimen a liquid, or in some cases a solid, film of material of or or higher density will lower M,, while in a single crystal it should suppress the transformation completely. In the case of cobalt it is necessary to find a dense liquid which will not react with the metal at the transformation temperature. The most promising liquid appears to be pure lead, but it is very difficult to devise a method of investigating whether or not this does suppress the transformation.

Jan 1, 1952

By David Burgess, Hershiel H. Hayden

Experiments at the Somerset mine, Colo., under an agreement between US. Steel Corp. and the US. Bureau of Mines are described. A test was made of the tube bundle method of mine air sampling which was developed for European longwall mines; some 300,000 running feet of tubing provided continuous monitoring at 38 locations. Carbon monoxide concentrations were obtained with standard deviations of less than 1 ppm and oxygen concentrations with standard deviations of less than 0.2%. A base level of CO index (ppm CO evolved per percent 0, removed) was determined to be zero to 20 through most of the passageways of the mine. However, in one working section where the coal was initially hot (about 180°F within a pillar) the CO index was demonstrably higher, 120 trending upward to about 60 when smoke appeared and the section was sealed. The data are discussed in terms of laboratory experiments on CO evolution from coals.

Jan 1, 1977