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By Harlan A. Walker

Rock-drill steel has an important bearing on costs in many mining operations, both directly and indirectly. Direct factors include such items as shop expense, steel consumed per ton of ore produced, cost of distribution and the dust hazard. The latter, although no specific amount may be assigned to it, is an ever-present problem, and is receiving increased attention as the science of mining progresses. Indirectly drill-steel performance affects consumption of compressed air, maintenance of drills and drilling speed. The latter, in turn, increases or retards the tempo of mining and development. These factors, while not all inclusive, are preponderant in their importance. Thus it is evident that in an extensive operation drill-steel expense may run to many thousands of dollars and that thoughtful research leading toward more efficient practice is warranted. Experimental Work During the late spring of 1939, experiments were undertaken at Homestake in reducing changes in drill-steel gauge from ? in. to 1/16 in. In drifts and crosscut headings mounted machines were set up and holes were drilled with ?-in. bit-gauge changes and other holes a few inches

Jan 1, 1940

By I. N. Zavarine

THE present paper is a continuation of the work on the relationship between the magnetic and the phase transformations in carbon steels during quenching. An account was given by the author in a previous paper It of an investigation of this relationship during a continuous quench. The experimental difficulties then encountered prevented a conclusive proof of the existence or absence of such a relationship. The conclusions of the previous paper were derived indirectly. The present paper deals with the same problem, but the method of attack is modified. The technique developed by Davenport and Bain2 in their well-known study of austenite transformation at subcritical temperature was adopted in the present investigation. They have shown that the austenite to martensite transformation can be caused to proceed at a relatively slow rate by quenching steels into a hot metal bath. Slowing down of the rate of transformation, together with an observation by Lewis3 that a eutectoid steel can be preserved in the nonmagnetic state by such quench-ing, pointed out a possibility of a study of both transformations under more favorable conditions than previously described. The preliminary steps were connected with the technique of the hot bath quench. To study this phase of the present work a modification of the apparatus previously describe1 was used. The modification con-sisted in the use of a hot quenching bath instead of brine, and in fixing the secondary and the primary coils of the apparatus in a stationary position in and around the bath. Tubular specimens, as in the previous investiga-tion, were heated in a suitable furnace to a temperature in the austenitic.

Jan 1, 1935

By R. E. Crockett

MAGNETITE mining and milling in the Eastern States was at capacity during 1940, owing to the heavy industrial, defense, and war demand, coupled temporarily with the almost total stoppage of imports of foreign ores other than those under American ownership. In New York State the active mines were those operated by the Republic Steel Corp. at Mineville and Lyon Mountain. Republic's new concentrating mill at Port Henry, handling the Mineville ores, went into production about the first of April. Other large magnetite deposits in New York are currently being prospected and studied and may be under development in the near future. In New Jersey the Mt. Hope and

Jan 1, 1941

By A. J. Langhammer

A. J. Langhammer.—That is rather asking a question of the wrong man. However, I will reply to the question from our point of view. There is a considerable amount of iron powder available but the properties vary over a wide range. Powder metallurgy has progressed to the stage where we recognize certain requirements in powdered iron, and what may be a good powdered iron for one application will not necessarily fit the picture for the next one. Further, I believe that there is room for great improvement in the properties of powdered iron. Also, that there is only a limited quantity of powdered iron available having certain specific properties in which we are at the moment interested. F. P. Peters.—May I have a word? With all possible respect to the contributions of the Chrysler Corporation (and they have been tremendous) to the war effort, I think it is easy to get from part of Mr. Langhammer's discussion a false impression of vaster possibilities than really exist. It would be well if in addition to Mr. Langhammer some other manufacturers of machine parts' might tell us in the next few minutes some of the limitations they have found. For example, what is the maximum tensile strength that is being produced in a commercial part in production today? And what is the actual size limitation on bearings that are in operation and are standing up well? We should always bear in mind the fact—and I think Mr. Langhammer will agree with me— that quoting on a particular part does not necessarily mean placing it in production. In many cases it may be several months before the quotation is resolved and we know whether the part can be made. Let us open up this thing for a little free-for-all discussion of some of the ceilings that do exist in the design of machine parts made by powder metallurgy. The ceiling is not unlimited, and Mr. Langhsmmer will agree with that, 3 am sure. H. Hendriks.*—I do not think that there is so much limitation in the making of powder metallurgic manufactured parts as mentioned. Last year we had the problem of making dies for a special machine used in the manufacturing of slide fasteners. This part was wearing out very fast. It was very hard to make, it had to be hobbed out of a special steel and it was a difficult thing to manufacture in general. The tolerances were one half of one thousandth of one inch on all dimensions. We submitted this die to a manufacturer of powder-metal parts. He thought that it was impossible, but we were not as skeptical as he was and decided to try it anyway. The Canadian General Electric Carboloy Division, in Toronto, gave us then the design for the dies, which we made to their specifications. When the first part was delivered, we submitted it to our Inspection Department and its check showed that all the tolerances were right on the dot. They delivered I9 parts of exact specification, then they went off the beam; they could not keep to the tolerances. It took them a long time to get back again. We do not know what happened, but the main point I want to' make is that if a problem is attacked in the right may, the dies are made right and corrected as to dimensions found out by experiment, I do not think that there is so much diffculty in making powder-metal parts to close tolerances.

Jan 1, 1945

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Jan 1, 1907

By William P. Blake

THE magnetic iron ores of the Rees & Wilder tract, Unaka Mountains, East Tennessee, and North Carolina, so far as examined by me, are peculiar in containing considerable quantities of the mineral zircon in dark red-brown crystals, ranging in size from one-tenth of an inch, or less, to five-tenths of an inch in length. As zircons are decomposed by fusion with alkalies, the constituents may exert some favorable influence upon the iron product, which is generally acknowledged to be of superior quality. NEW HAVEN, April 20th, 1878.

Jan 1, 1879

By Frank S. Hurley

To comply with the California Mine Safety Orders pertaining to transportation of mine workers over mine railroads, the management of the New Idria mine in San Benito County, Calif., designed special man-cars. The new regulations, dated October 1958, make it mandatory for mine man-cars to be designed for carrying five or more men to and from the mine workings. At the New Idria mine, largest single producer of mercury in the U.S., each shift normally employs about 70 men. However, with the possibility of a future increase in the work force, seven man-cars were constructed with a total carrying capacity of 84 men. The general design of the mine man-cars was dictated by safety regulations plus the physical characteristics of the mine-low headroom, limited side clearance in haulageways, and track irregularities due to ground swells. The cars measure 10 ft long, 44 in. wide, and 50 in. high and were built at an average cost of $450 per car. All assembly work was done at the mine site.

Jan 7, 1960

By James R. Cost

The increasing emphasis upon the use of refractory metals has resulted in a closer look at some of the properties of these materials. In the course of a study of the Nb-N system it became necessary to re-examine one such property, the spectral emissivity, e. Experiments were performed in order to determine e for solid niobium as a function of both temperature and nitrogen content. The results of these experiments, which indicate a small but significant correction to the spectral emissivity of pure niobium, are reported herein. In addition, data on the total emissivity, et, of niobium and the spectral emissivity of the nitride Nb2N are given. To this author's knowledge, neither of these emissivities are as yet reported in the literature. Previous studies of the spectral emissivity of niobium have been few. In 1915, Burgess and Waltenburgl obtained a value of 0.49. Whitney? in 1935, used a Mendenhall V to obtain the commonly accepted value of 0.374. A recent investigation of sintering of niobium graphically reported a value of about 0.36= using a solid block of the metal with a blackbody hole drilled into it. In the present experiment a method similar to that of Worthing4 was used. An 8-in. long and 3/16 in. diam hollow tube was formed from smooth surfaced 0.0013-

Jan 1, 1962

By W. Joseph Schlitt

The types of copper leaching and recovery operations in the United States are reviewed, along with characteristics and trends in the industry. The contribution of the various leach operations to total mine output is discussed in order to provide a perspective on the relative importance of copper leaching as a method of production.

Jan 1, 1980

By Eldon N. Dunlap

Recently the producing branch of the petroleum industry has shown a considerable and growing interest in the quantitative determination of the water, oil, and gas content of cores as it relates to estimation of reserves, to providing a basis for judging as to the feasibility of applying various secondary-recovery and pressure-maintenance processes, and in general to the operation of producing properties. For years it has been known that oil, gas and water coexisted in the pores of many semidepleted oil measures. It is now generally believed that oil-bearing beds contain connate water in amounts varying up to 50 per cent of the pore space. However, only lately has reliable direct evidence of the extensive occurrence of connate water in oil sands been published. Very little work has been done to ascertain the effect of this water on the productivity and ultimate recovery of oil from wells. It was the intent of this research to study the influence of interstitial water on the flow of oil through unconsolidated sands, with the hope that the results could be applied qualitatively to the flow of oil in underground reservoirs partly saturated with water. Obviously, ultimate recovery estimates based on the void volume of the reservoir will be in error unless a correction is made for the volume of water that occupies a portion of the effective pore volume of the reservoir. Evaluation engineers in the past have applied arbitrary saturation and recovery factors that may inadverently have compensated for the failure to consider specifically the water content. Nevertheless, the evidence available indicates that these factors need revising if each is to be independently correct and truly representative. Although the fact that the connate water renders part of the pore volume of the reservoir incapable of containing oil is of primary importance to the operator, it is also to his interest to know to what extent the presence of varying amounts of interstitial water influences the permeability of the sand to oil.

Jan 1, 1938

By A. F. Daily

Free World consumption of diamonds of all types closely follows the fluctuations of the business cycles in the large industrialized countries, particularly the U.S. Sustained purchasing by this country for stockpiling purposes has been a major factor in Free World demand for crushing bort and industrial diamonds, and it has been for this reason that investments in larger plants have been made by all major diamond mining companies during the past few years. For the purposes of this study, the diamonds produced in the Congo and elsewhere in the Free World are divided into three types:

Jan 5, 1961

By T. S. Lovering

Jan 1, 1965

By Luther W. Bahney

Jan 1, 1912

By M. A. Torcaso, P. Raimondi

The distribution of the oil phase in Berea sandstone resulting from increasing and decreasing the water saturation by imbibition was investigated Three types of distribution were recognized: trapped, normal and lagging. The amount of oil in each of these distributions was determined as a function of saturation by carrying out a miscible displacement in the oil phase under steady-state conditions of saturation. These conditions were maintained by flowing water and oil simultaneously in given ratios and by using a displacing solvent having essentially the same density and viscosity as the oil. A correlation shows the amount of trapped oil at any saturation to be directly proportional to the conventional residual oil saturation Sor The factor of proportionality is related to the fractional permeability to the water phase. Part of the oil which was not trapped was displaced in a piston-like manner (normal part) and part was eluted gradually (lagging part). The observed phenomena are more than of mere academic importance. Oil which is trapped may well provide the fuel essential for forward combustion and thus be beneficial. On the contrary, in tertiary recovery operations, it is this trapped oil which seems to make current techniques uneconomic. INTRODUCTION A typical oilfield may initially contain connate water and oil. After a period of primary production water often enters the field either from surrounding aquifers or from surface injection. During primary production evolution and establishment of a free gas saturation usually occurs. The effect and importance of this third phase is fully recognized. However, this investigation is limited to a two-phase system, one wetting phase (water) and one non-wetting phase (oil). The increase in water content of a water-wet system is termed imbibition. In a relative permeability-saturation diagram such as the one shown in Fig. 1, the initial conditions of the field would be represented by a point below a water saturation of about 35 per cent, i.e., where the imbibition and the drainage curves to the non-wetting phase nearly coincide. When water enters the field the relative permeability to oil decreases along the imbibition curve. At watered-out conditions the relative permeability to the oil becomes zero. At this point a considerable amount of oil. called residual oil, (about 35 per cent in Fig. 1) remains unrecovered. Any attempt to produce this oil will require that its saturation be increased. In Fig. 1 this would mean retracing the imbibition curve upwards. In addition, processes like alcohol and fire flooding, which can be employed at any stage of production, involve the complete displacement of connate water and an increase, or imbibition. of water saturation ahead of the displacing front. Thus, in several types of oil production it is the imbibition-relative permeability curve which rules the flow behavior. For this reason a knowledge of the distribution of the non-wetting phase, as obtained through imbibition, whether "coming down" or "going up" on the imbibition curve, is important.

Jan 1, 1965

Doctor David Yang has presented an important new flotation development in the area of fine particle flotation technology; at the same time Dr. Yang presents an explanation for the effectiveness of this improved new fine flotation system in terms of an optimum dispersion state. The same statement is made for the case of carrier flotation (ultraflotation), in the removal of anatase from kaolinite by addition of calcite (selective flocculation of the anatase - calcite system and dispersion of kaolinite). Dr. Yang's data and statements raise some important questions, and I will adress myself to the more fundamental aspects of this new flotation system. The addition of sodium silicate, well known as a good depressant-dispersant agent for siliceous gangue minerals, is proved to be greatly enhanced by the incorporation of polyvalent metal salts into sodium silicate prior to flotation, producing in this manner a condition, as described by Dr. Yang, of optimum dispersion, which in the case of fine-grained oxidized taconite can be described as selective flocculation (coagulation) of hematite and almost complete dispersion of siliceous gangue components. Dr. Yang recognizes that the main mechanism, while not completely understood at this time, seems to operate by modifying the surface characteristics of the gangue slime particles so as to prevent collector from bonding there to, and making the particles strongly hydrophilic so they will become fully dispersed and consequently will not float during froth flotation. At the same time it appears that the conditioning reagent also modified the surface characteristics of the floated minerals (hematite and spodumene in this case) so that they will aggregate and tend to more readily adsorb the collector, resulting in an improved flotation kinetics and selectivity.

Jan 1, 1979

By M. K. Barnett

[ ] ENGINEERING research consists, broadly speaking, in the investigation of the effect of the variations in a number of factors on some property of a product or characteristic of a process. The unambiguous description of the product or process requires that the property or characteristic be expressible in quantitative terms. For the purpose of practical control, it is likewise desirable that the independently variable factors governing the product or process be quantities, although this ideal goal is not always attained. Maximum efficiency-i.e., the attainment of the maximum amount of reliable, useful information relating to the influence of the factors on the property of the product or characteristic of the process, for the least expense-is an important requirement for the satisfactory operation of a research organization. Obviously, a necessary condition for the attainment of maximum efficiency is an adequate knowledge of the specialized field in which the experimental research lies. While necessary, this condition is not sufficient. Proper attention must also be given to the general principles of experimental design together with the modem methods for the analysis and evaluation of experimental data. The present discussion is confined to a single design, the so-called "factorial" design. This design is of special interest in that it attains its goal, maximum efficiency, by directly departing from the

Jan 1, 1947

By R. R. Odman, O. N. Lofgren

At the planning stage for this plant it was scheduled that the plant operate at a low energy consumption. After start up in 1973 it was established that outcome was even better than the forecast. In view of the 1977 ore market it was decided to operate the plant at half capacity. This initiated efforts to reoptimize the process in order to hold back expected increase in energy consumption. The result from this work proves that a detailed study and tuning of the process can not only avoid expected increase, but also reduce specific energy consumption.

Jan 1, 1983

By R. L. Watts

Successful mining of taconite has required the solution of a series of difficult problems, including more efficient magnetic separation. Progress in this field is evidenced by reductions in operating and capital costs made possible by the advances in permanent magnetic materials and in new circuits for better utilization of these materials. The advent of the flux control circuit appears to be one of the more important breakthroughs in permanent magnet drum design circuitry and has contributed greatly to the economics and metallurgical requirements of the modern day taconite concentrators. High strength permanent magnetic separators are now replacing electro types in many applications requiring field strengths of 900 - 1000 gauss measured at 2 in. This is made possible by the new circuits having gauss readings at 2 in. previously attained only by electromagnets.

Jan 12, 1967

By H. J. Wasson, L. W. Mayer

The existing large stocks of raw materials have induced misgivings in the minds of many as to near-view prospects for a return to higher commodity price levels. Until stocks are materially reduced—and this operation will probably extend over a protracted period—a buyers' market will continue. Meanwhile the matter of production cost becomes more and more a factor of consequence to industrial management, finance and the investing public. With many commodities a general level of costs exists with which the public has been made familiar. Certain conditions surround these industries which, at the outset, determine whether there is a basis for sound commercial results. In other words, it can generally be determined in advance whether or not the cost of production is sufficiently below the normal average price to return a reasonable profit over the years. With all domestic agricultural products there are available exhaustive Government studies in the field of production costs. Such figures as the average cost of wheat, cotton, sugar, etc., are reiterated constantly. There are many products of foreign origin such as coffee, rubber, raw silk, etc., the production costs of which are to most of us matters of deep mystery. Forest products also are so diversified that few but specialists know what a thousand feet of lumber really cost at the mill, especially where remotely located. However, with respect to products of mines, production cost information has been widely disseminated. The literature is replete with such data. Here we find that without any special help from outside agencies the industry itself has given publicity to a large variety of cost figures. For example, we know, or know where we can ascertain, the cost of producing a pound of copper from Chile, Arizona or the Lake Superior district. In many cases we can secure from the company reports a vast amount of detail leading up to the cost per ton of ore and the cost per unit of the metal yield. These records are of great assistance to the mining industry as a means of estimating on new exploitations. This industry has been production-cost-minded almost from the beginning.

Jan 1, 1931

By Walter Weeks

LITTLE study has been made of the pressure changes and energy losses that take place when an air current is divided into splits which subse-quently unite. The discussion and the experiments that are described in this paper deal with the division of an air current into square splits of equal size, the area of each of the splits at the downstream junction being one-half the area of the main duct. APPARATUS AND SYMBOLS The duct system shown in Fig. 1 was built of Y4-in. redwood and made as smooth as possible.The section of the top over the splits and the zone of mixing was of plate glass to permit observation of the stream lines. FIG. 1-DUCT SYSTEM. Static pressures were measured by means of pinhole tubes and a precise inclined manometer. Measurements of rates of flow were .made by determining the drop in pressure through concentric square orifices in the splits. The air was supplied by a fan operated by a direct-current motor that received its current from a motor generator set. Delicate rheostats in the armature. of the motor. made possible the perfect control of the fan speed, which was indicated on an electrical tachometer. Vanes to straighten the. flow were placed at the head of the main duct.

Jan 1, 1933