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By Richard F. Link, George S. Koch

About 50,000 assays of mine samples were required in a preliminary investigation of the distribution of gold, silver, lead, copper, and zinc in two large Mexican mines, the Frisco mine at San Francisco del Oro (Chihuahua) and the Fresnillo mine at Fresnillo (Zacatecas). The feasibility of working with so many assays rests directly on the use of machine processing methods. The purpose of this article is to describe the methods used because machine (or data) processing can also be used efficiently to make the many calculations from mine assays needed in mining operations. No particular originality is claimed for these methods, which are straightforward applications of standard procedures for machine processing. Inasmuch as machine processing is essentially a routine job once it is begun, procedures must be organized more completely than is the case where human judgment can be inserted at every step. Before undertaking any work, it is necessary to decide carefully just which data must be processed as well as the exact results desired.

Jan 9, 1960

By Frank Firmstone

IT is proposed to consider here only comparisons made between results obtained when the materials employed are precisely the same, two furnaces at the same works for example, or the same furnace under different conditions as respects temperature of blast, method of charging, etc. With this limitation, the most important point in the comparison is the amount of fuel consumed per ton of iron. This, in fact, is the only item in the prime cost of the iron which can properly be said to vary in consequence of changes in the furnace process ; for of the other principal items, the ore used per ton of iron, and also the amount of fluxing material, will depend on its richness, which, under the assumed conditions, will be practically invariable when taken over any considerable period; the labor cost also, from its nature, should be very nearly constant when estimated on the ton of iron. Moreover, as it consists principally in handling and moving material, it is greatly affected by circumstances quite independent of

Jan 1, 1876

By A. R. Sims

Are from the Greater Butte Project is hoisted through the new Kelley shaft. In 1946 when plans were formulated for the Kelley mine, two test cave blocks were mined by using the facilities of the old St. Lawrence mine. These blocks, known as the Adams No. 1 and Adams No. 2, produced more than half a million tons of ore. The experiment proved beyond all doubt that cave mining was possible- and economical-in Butte. Adams No. 1 was patterned after Inspiration cave blocks. Adams No. 2 was a slusher type, with the slusher lane on the first floor above the haulage crosscut and at right angles to it. Thirty-horsepower electric hoists slushed ore from 48-in. scraper buckets directly into cars for haulage to the shaft. These cars were the 57-cu ft Granby type hauled by 6-ton battery locomotives over 40-lb, 18-in. gage track. Prior to this time the largest slushing machines used at Butte were 15-hp electric hoists pulling 36-in. scrapers.

Dec 1, 1956

By Frederic Dewey

HAVING shown1 the difficulty of assaying so-called cyanide bullion and the extreme variations often found in the results, an investigation was undertaken to discover if possible the causes of these variations by a series of tests upon the specific action of various metals during cupellation. Zinc.-In order to test the effect of zinc, 48 assays were made in sets of 6, 2 rows of 3. The charge for the middle cupels consisted of 500+ mg. Au, 1,125 mg. Ag, 10 mg. Cu. To the end cupels 50, 75, 100 and 125 mg. Zn were added, and a set of each proportion was cupelled with 4 and 8 grants Pb. The cupels were assayed and showed the following gold contents in milligrams, the figures being arranged as the cupels stood in the muffle: TABLE 1 50 Mg. Zn 75 Dig. Zn 100 Mg. Zn 125 Mg. Zn 4 grams, Pb 0.2S 0.25 0.2S 0:29 0.27 0.34 0.33 0.28 0.41 0.31 0:30 0.36 0.30 0.33 0.34 0.31 0.31 0.29 0.35 0.37 0.42 0.41' 0.34 0.38 8 grams, Pb 0.40 0.43 0.42 0.38 0.36 0.43 0.35 0.34 0.41 0.33 0.37 0.37 0.54 0.17 0.59 0.44 0.43 0.43 0.38 0.39 0.41 0.57 0.38 0.46 _ In many instances the zinc does not appear to affect the cupel gold, but various exceptions are apparent, generally in the cupels in the back row. With 100 and 125 mg. Zn, in some cases the Zn burned with its characteristic flame before it could alloy with the other metals. Also, less fusible oxidized lumps were observed during the cupellation and some cupels showed a scum. In order to lessen the premature burning out of the Zn, an alloy of 2 parts Ag to 1 part. Zn was used. A uniform charge of 500,+ mg. Au,

Jan 7, 1917

By Jack M. Jodrey, Neil D. Donnell, O&apos

Bituminous sands of the Lower Cretaceous McMurray Formation in northern Alberta constitute the ore for the surface mining operation at Syncrude Canada Ltd. These sediments represent a complex succession of fluvial, estuarine and marine depositional environments. Grade prediction is realized through a combination of geological interpretation, computer modeling, and reference to past mining experience. Accurate forecasts of feed grade permit reliable predictions of volumes for removal to meet budgeted synthetic crude oil production. This planning facilitates efficient allocation of mining equipment and resources. The feed grade to the Extraction Plant is monitored at various points along the delivery system.

Jan 1, 1985

By B. Bernstrom

A 22-ft diam, 7-ft long, wet autogenous grinding mill was installed in the new Cretaceous plant of the Jones & Laughlin Steel Corp. to prepare crude iron ore for concentration in spirals and flotation cells. The paper describes the flowsheet and gives a description of the operating and metallurgical results that have been obtained. These results include capacity, horsepower, operating problems and a comparison of pilot plant results with those obtained in commercial operation. The Cretaceous plant at the Hill Annex mine of the Jones & Laughlin Steel Corp. was designed with a wet autogenous mill for grinding low grade iron ore so that it could be concentrated by spirals and flotation cells. The plant, on the west end of the Minnesota's Mesabi Range, went into operation in June 1961, and preliminary operating and metallurgical information describing the performance of this mill can now be given. The crude is lean ore from the Cretaceous iron foundation. This formation is a beach deposit of Cretaceous age that overlies the Precambrian direct shipping and concentrating ores. This rock in nature is not extremely hard but is quite resilient, resisting blasting in mining and size reduction in milling. It contains hematite as water-rounded particles and other fragments of the underlying iron formation and adjacent rocks cemented together by a high alumina-silica ferruginous matrix. It is interspersed with hard dense hematite agglomerates and also contains granite pebbles and boulders that were not cleaned off during removal of the surface. It has a 3.48 sp gr and in the stockpile the material consists of frag-

Jan 1, 1962

Body Hoists A complete new line of hydraulic dump truck body hoists and bodies featuring many outstanding design improvements has just been announced by St Paul Hydraulic Hoist Fourteen models of this new hoist are available in a selection of capacities from 6 to 25 tons The new body hoist features low standard mounting height, advanced lifting point, new low operating oil pres [ ] sures, a new Uniflex subframe, friction-free roller bearing drive mechanism, including pump and power takeoff, to insure quiet operation and long trouble-free life A stress-eliminating design feature of the new hoists absorbs dumping shocks and permits use of a new principle in hoist design a flexible subframe which ends tendency of rigid hoists to crack or bend when flexed Circle No. 1 Combination Drill A new combination drill offering all three methods rotary, auger, and percussion drilling on the same rig is the revolutionary feature of the latest drill rig designed by Mobile Drilling Inc The B-36 drill is larger, more powerful and versatile than previous models built by this company This new drill has a hydraulic feed of approximately 8000 lb pressure The hydraulic feed cylinder is located directly over the rotary turn table The carriage of the drill is of tubular construction The drill mast, also of tubular construction, nests in the tube members of the drill carriage for cross-country travel with a maximum overall height of 10 ft The drill mast telescopes together with the feed cylinder hydraulically to an operating height of 16 ft The drill can be furnished with an auxiliary cat head, sand reel, and special high pressure water pump The B-36 maximum depth for auger drilling without water is approximately 150 ft, depth for rotary drilling with water is in excess of 300 ft Circle No 2

Jan 1, 1952

By Lane D. Schultz, John D. McLennan, Jean-Claude Roegiers

During construction of the intake tunnels for a nuclear power facility in Ohio, evidence of a potential geological discontinuity was discovered. Assuming that the discontinuity might still prevail underneath the site, it was decided to measure the stress profile across the discontinuity. This information would be used to assess future stability on the basis of predicted shear stresses acting along the fracture. Seven intervals were hydraulically fractured to determine the magnitude and orientation of the stress tensor, in order to infer the shear stresses acting along the discontinuity. The formation consists of tightly interbedded shales. This, in combination with the shallow depths, would be expected to lead to horizontal hydraulic fractures -- a situation which generally provides limited information. Careful testing procedures, and meticulous interpretation, allowed the determination of the horizontal stress components as well as the vertical component, via the initiation and/or propagation of multiple fractures. The measured stresses fall within the range of stress magnitudes and orientation determined in other areas of the northeastern and north-central United States and in southern parts of Canada. In addition, a small stress gradient anomaly was recorded at depth. On a different scale, the measured stress regime is also evaluated in light of the regional geological setting.

Jan 1, 1982

By D. W. Peaceman

In previous papers by this author on numerical calculations of multidimensional miscible displacement, some simplifying assumptions were made in writing the dispersion term of the differential equation. It was assumed that the flow vectors were essentially parallel to the x-axis. However, in most multidimensional miscible displacements, the flow vectors are not so simply oriented with respect to the coordinate axes. This paper derives the correct dispersion term /or the more general case; gives a difference approximation /or the dispersion tern; and derives the stability criterion for the corresponding explicit difference eguation.

Jan 1, 1967

By D. S. Choi, D. L. McCain

A method of estimating the chain pillar size required to support the wide working faces of longwall or shortwall coal mining is presented. The pillar size is determined through the use of coal strength, entry geometry, panel width, and overburden pressure. Design analysis is focused on a three-entry development system in the Pittsburgh Seam but can be used for other development plans and other seams by substitution of the proper geometric and strength data.

Jan 1, 1981

By C. N. Kravig

STANDARD raises at Homestake are 150 ft long. Raises of more than 150 ft, driven with the use of a cage and hoist, are considered long raises- some have been driven more than 900 ft. Long raises have eliminated the need for access drifts on each level when transfer and ventilation raises are driven. These timbered cage raises, 7x9 ft in cross section, include a rock compartment and a combination cage, pipe, and manway compartment. To prevent excessive weight on the timbers, 10x10-in. bearing beams are cemented into hitches cut in the rock at 150-ft intervals. The beams also hold back timber movement caused by daily drawing of rock through the rock compartment.

Jan 6, 1957

By Howard S. Strouth

Investors and mining companies in the U. S. have recently shown increased interest in the Union of South Africa. This has been sparked partially by the founding in the U. S. of a large investment trust which will hold substantial shares in many of the leading gold and uranium producers. The average U. S, mining man's judgment of the Union, however, may be somewhat clouded by recent headline news. We are inclined to take a strong dislike to the stern measures of the present Union government with regard to its native majority. Others possibly think of South Africa in krms of a British colony which, under pressure of rising African nationalism, must eventually be abandoned. These concepts frequently suffer for lack of precise information.

Jan 5, 1959

By D. S. Nilsson

Small-scale mines are today expected to provide much of the increased production of metals and coal this county demands. But in fact the category of larger mines tends to grow in number and size faster than the category of smaller mines. Larger mines show the highest productivity, the lowest injury frequency, and the lowest costs. Lower cutoff grades can be wed in larger mines. The paper describes how the production level affects the choice between different types of loading, haulage, and hoisting equipment; how the increased production level in a mine results in lower production costs per ton; and how this affects the profitability of mining deposits with various ore grades. The future trend is expected to favor larger and larger operations.

Jan 1, 1983

By T. W. Turk, S. A. Sass

The engineering design features of the Mercur Gold Project crushing, grinding, carbon-in-leach, bullion, reagent, and tailings disposal areas will be discussed in this paper. It presents a project overview and flowsheet along with selected design alternatives. During the engineering phase, major equipment and other features were selected to optimize design within site location and environmental constraints. The project team organization and procedures were adopted to accommodate multiple optimization studies while maintaining a tight engineering schedule.

Jan 1, 1985

By Samuel Hoyt

THIS paper gives a brief description of an investigation made several years ago on the diffusion of zinc into copper. The material for that study was furnished in the form of thin copper strips coated with zinc. The result was required rather quickly and at not too great an expense, and especially information was desired as to the rate at which zinc would diffuse from the zinc coating into the copper and the temperature at which the operation should be carried out. A study of the requirements of this problem indicated that the solution might be secured by means of six determinations. This is the smallest number that will give the information desired and, at the same time, furnish checks on the accuracy of the determinations which justify an abbreviated experimental program. This does not count a preliminary test which was designed to give some idea of the correct temperature to use. The minimum number of temperatures that can be used is two. Knowing the rates of diffusion of zinc into copper at two properly chosen temperatures, it is possible to calculate the rate for any other temperature, and also to check the accuracy of the determination by means of the heat of diffusion, which is calculated from the effect of temperature on the rate of diffusion. The minimum number of determinations at any one temperature is three. The amount of diffusion which occurs at a fixed temperature is definitely related to the time of diffusion, so that by determining the amount of diffusion for three different time intervals, this relationship may be established and possibly a check on the accuracy may be secured. This accounts for the six determinations or experiments, and suggests the logical plan of the work. The check used here is not generally applicable to diffusion phenomena, but it seems to hold closely enough for the limited amount of diffusion in this investigation to justify its use.

Jan 1, 1928

By Wolfgang Pietsch

Direct Reduced Iron is a product obtained during solid state reduction of iron oxides into metallic iron. General chemical and physical characteristics of all direct reduced iron materials result in a noticeable reoxidation tendency and a relatively low ignition temperature. As most of the chemical reactions are exothermic, normally heating occurs and if water is present hydrogen evolves. Dry direct reduced iron deactivates quickly in air but is still reactive if it comes into contact with moisture. Because of these characteristics, special requirements are necessary for safe storage, shipment, and handling. In an effort to improve this situation passivation techniques were and still are being developed. The paper discusses the properties of direct reduced iron, presents past experience with storage, shipment, and handling of MIDREX® Iron, a direct reduced iron material produced in the MIDREX® Direct Reduction Process, and evaluates benefits derived from different passivation techniques.

Jan 1, 1978

By Zay Jeffries

The object of the present paper is to enlarge somewhat on the general principles advanced in my discussion1 of Mathewson and Phillips' article on The Recrystallization of Cold-Worked Alpha Brass on Anneal-- ing.2 It will also serve as an acknowledgment of Prof. Howe's most important remarks on my contribution. In this paper the writer has adopted Prof. Howe's suggestion to substitute the term "germinative temperature'' for "critical temperature for grain growth." Instead of being an exact or certain temperature it should be considered that the germinative temperature phenomenon exists throughout a small temperature range. v Factors Influencing Fast Growth Phenomena The development of grains of macroscopic size at the germinative temperature should be considered the extreme condition of a general rule. When considered in this light it is not strange that the development of these large grains should be the exception and not the rule. The principal factors influencing the operation of the laws of fast growth temperature are as follows: . 1. Rate of heating. In the original paper,' the germinative temperature was defined as "the minimum temperature at which two adjacent grains can coalesce to form one larger grain, provided that this larger grain will have sufficiently increased its power of attack, to enable it to absorb adjacent grains which cannot coalesce with each other. Time is always to be understood as a factor governing the first stage of grain growth." If the time of heating is short, the germinative temperature is raised. The formation of large grains in metals may occur at relatively high temperatures when the rate of heating is rapid. It is to be understood that in such cases, grain growth

Jan 1, 1917

By Benjamin S. Lindsey, James Norman

BARITE (BaSO4) is the most important industrial barium mineral from the standpoint of quantity consumed. In 1938 the amount was 365,000 tons. Its uses are numerous, some of the more important being in the production of pigments, as an inert filler in a wide variety of products, as a weighting material in oil-well drilling muds, in the manufacture of some kinds of glass, and in the production of barium chemicals. The barite studied in this investigation occurs as the massive variety in a shale replacement formation near Magnet Cove, Ark. It is intimately mixed with quartz and small amounts of iron oxide and residual shale. Complete liberation of barite and quartz is not obtained when the rock is ground to 100 per cent through 325 mesh. The crude rock with which all test work was done assayed 85.1 per cent BaSO4, 11.11 per cent Si02, and 2.85 per cent R203. Its specific gravity was 4.03. It was found in the course of the investigation that the barite contained a small amount of uniformly distributed carbonaceous material, so intimately dispersed that it could not be seen with the microscope, but gave a definite gray cast to the barite concentrates. The color of the barite in polished sections of the crude rock ranged from gray to almost black, while finely ground powder ,was a reddish gray. The reddish hue was due to the iron oxide present. In 1939, under the supervision of Oliver C. Ralston,* the Bureau of Mines, in cooperation with the Milwhite Company, of Houston, Texas, undertook to study the flotation of barite from Magnet Cove, Ark. Flotation of several southern barite ores had already been investigated by the Bureau of Mines.' The Magnet Cove barite was unique, however, in that it had to be ground to such an extremely small particle size for liberation. The flotation of nonmetallic minerals in the presence of a large amount of slime is usually very difficult, and when done is an innovation calling for conditions different from those under which granular material is separated. LABORATORY FLOTATION WORK Preliminary investigation showed that the flotation reagents recommended by O'Meara and Coe1 for separating barite and siliceous material were suitable, but much larger quantities of reagents were required to separate such finely divided material. Moreover, it was found that careful control of the frothing was necessary. When oleic acid and sodium silicate were used a voluminous froth was observed at the beginning of a test, and toward the end there was not enough froth to effect complete recovery of barite. The addition of pine oil as a frother gave proper frothing for the duration of the test, and the substitution of coconut fatty acid (crude lauric acid) for oleic acid produced a more heavily burdened froth. Two different paper-mill fatty-acid products were tested

Jan 1, 1941

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 M. Van Siclen

THE outstanding fact in connection with dust disease in the United States at present is the growing recognition of its seriousness by state officials and by the more progressive operators of mining, metallurgical and allied industrial plants. The same may perhaps be said of labor in some of its better organized centers, but the average independent non-union workman continues, .as of yore, to suffer the toll of disability and even of death from dust inhalation without realization of the source of his ill-being. Progress in the betterment of the handling of sufferers from dust disease and of the conditions creating dust hazards in mining and allied industries is pursuing a course similar to that of the now widespread campaign against accidents, in which the risk is more obvious, more severe, and was naturally recognized sooner. The coming on of dust disease is generally relatively slow and its immediate effects not infre-quently masked by or attributed to other diseases. Marked exceptions to this general rule have occurred in districts where the dust is particularly pernicious, such as the Rand and Joplin; yet such exceptions, unhappy in themselves, opened the eyes of medical men, and of those in other localities charged with the responsibility for the welfare of industry, to the much more widespread if less spectacular hazard existing from the inhalation of dust in all rock-excavating operations and all industrial operations creating inorganic dust, whether it be crushing and grinding, sand-blast-ing, granite-cutting, or what not. Advancement to date in the United States in prevention and treat-ment has been slow, yet the record shows that quantitative methods for determining the degree of hazard and means for decreasing it were being developed as far back as 25 years ago; and that more rapid progress may be looked for from now on. In 1908, in this country; F. L Hoffman?(1) discussed the mortality from consumption in dusty trades, especially brass foundries; and in 1913 E. R. Hayhurst(2) described the effects of inhalation

Jan 1, 1933