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By Benjamin Miller

FROM earliest recorded times, limestone has been employed in the industrial life of peoples of all sections of the world where it exists. It is widely distributed and therefore has been available in almost every country and has been employed for a variety of purposes. Its earliest use was for buildings, since it is more easily quarried and dressed than most other kinds of rocks and so could be utilized by early inhabitants, poorly equipped with tools. The next use was in the manufacture of lime, which was employed by the ancients in mortar. These two uses of limestone are still all important, but they have been overshadowed in scores of regions by literally hundreds of new applications for raw lime-stone or products made from it. Anyone familiar with modern manufacturing processes can quickly call to mind many industries in which limestones are essential, and new uses are continually coming to notice. Any enumeration would probably be incomplete and soon out of date.

Jan 1, 1935

By R. E. Ford, P. Tarassoff, P. H. Jennings

Copper oxide ore may be leached at all sizes from run-of-mine down to pulp, and consideration must be given to all available methods in determining the most economical one. Heap leaching was evaluated in a pilot plant at Gaspe Copper Mines, Ltd. which was designed to simultaneously leach two 1200-ton dumps of ore. The plant was operated for two years, in part under severe winter conditions. Two modes of leaching were investigated: acid leaching in which sulfuric acid was added externally to the leach solution, and pyritic leaching in which pyrite concentrate was added to the dump and acid was generated in situ by bacterial action. The pilot plant operation is described, and the results are compared with laboratory data obtained in 6-in.-diam columns. It is concluded that pyritic leaching offers certain operating advantages over acid leaching when copper is recovered by cementation in that iron buildup in the solution is prevented.

Jan 1, 1974

By Vernon Read

Among the technical problems in AEC's Project Plowshare is the necessity of determining the precise effects of nuclear blasts in all kinds of ground formations. This calls for extensive in-situ sampling with full core recovery. In the exploration drilling that often precedes a new test detonation, the AEC and its contractors have applied both novel and established sampling techniques in many new ways, giving improved core recovery and reduced costs in all subsurface sampling and testing. Unique among these new techniques is one that achieved full recovery and virtually undisturbed samples from near-surface layers of unconsolidated boulder-strewn alluvium. This approach involves a combination of oilfield and mining core drilling equipment. Oilfield heavy drill collars, rotary stabilizers and thick, vibration-reducing oil emulsion drilling mud were used in combination with the precise hydraulic feed control, fast (over 300 rpm) bit rotation, light drilling weight, hard rock core barrels and multi-step diamond bits that are common in mining industry diamond drilling.

Jan 8, 1963

By C. R. Johnson, R. A. Greenkorn, G. W. Widner

This paper describes a short, simple well-testing procedure evolved from unsteady-state concepts to appraise wellbore damage in water-input wells. Input rates are changed at specific intervals over a 30-minute period and the wellhead pressure recorded at the end of each interval. From these data, the pressure drop due to the "skin" can be computed. This pressure drop in terms of psi/B/D of input rate is referred to as the "skin factor". Two of these variable-rate tests are required to determine change of wellbore damage and to evaluate well-treatment techniques. There are several advantages to the variable-rate procedure. The necessary data can be obtained with wellhead gauges and meters. There is little interference with normal operations. The short testing period eliminates many interpretative difficulties that come from interference from adjacent wells. The shut-in period required for standard tests before the plot of pressure vs log of time attains a straight line is often 12 hours or more. Such a time period is incronvenient, especially when a well must be tested repeatedly to evaluate change in wellbore characteristics. This variable-rate procedure has been successfully npplied to water-input wells in three fields. For some of the wells, skin factors were calculated from both the standard and the variable-rate tests. These results show good agreement. THEORY OF THE VARIABLE-RATE PROCEDURE In many waterflood input wells, the pressure in the wellbore differs from the pressure in the reservoir immediately adjacent to the well because of the restriction of flow through the skin of the well. If the true pressure of the reservoir at the well, p,, is that pressure which would exist in the well if no skin were present, and p,' is the actual pressure as measured in the well, this difference, is the skin effect. Fig. 1 shows the change in skin effect with change in flow rate. As the flow is reduced, the skin effect is reduced by an amount equal to the change in wellbore pressure minus the change in reservoir pressure. The equation of pressure change without skin using the point-source solution of the diffusivity equation is (after van Everdingen')

By J. W. Richards

There are two essentially different 'types of case-hardening processes; that using a dry mixture in which the object to be case-hardened is packed and kept for the necessary time at the necessary temperature, and the "liquid" proccss, employing a bath of fused salts into which the object is immersed and which by immediate contact case-hardens the surface of the article. The Shimer process belongs to the second class, and was a war emergency invention. Of the liquid melts used as baths, the most effective and most frequently used are melted potassium cyanide and melted sodium cyanide. These may be used either pure or mixed with salts that reduce the melting point and the percentage of .cyanide present. The use of these baths since 1914 has met many commercial difficulties because of the high price and frequent commercial scarcity of the cyanide salts; at present sodium cyanide has practically entirely displaced potassium cyanide. Another trouble is the danger to the workmen handling the cyanide salts, which are extremely poisonous, and the annoying and poisonous vapors or gases given off in the workshop, unless an effective system of hoods and ventilation is provided, so as to prevent the gases from the baths mixing with the air of the room. Porter W. Shimer, of Easton, Pa., has invented a substitute1 for the bath of melted cyanides which case-hardens with equal or greater facility and effectiveness, gives off no poisonous vapors, and costs for chemicals materially less than the cyanide costs in the previously used baths. The process has been in use over a year in a large American works and the following statement embodies the results of practical experience in the use and operation of the process. The Shimer liquid or melted bath consists of a mixture of easily fusible salts that do not possess case-hardening properties, into which is immersed fresh calcium eyanamid, which imparts to the bath case-hardening properties. The composition of the non-case-hardening salts appears rather immaterial. Good results have been obtained by using a mixture of sodium chloride, calcium chloride, and barium chloride in equal proportions by weight; also a mixture of one part sodium chloride

Jan 1, 1920

By Dr. Egleston

While I thoroughly appreciate the United States testing-machine at the Watertown Arsenal, and regard it as the most accurate testing-machine that has yet been built, I wish that I could say that it is complete in all respects. I not only fully appreciate it, but I have given up advising thesending of material to be tested anywhere else. It is five or six times more expensive to use this machine than any of the others, but the results which are obtained from it are, I think, perfectly reliable, and of such a character that the tests are all comparable with each other. It has proved, beyond a doubt, that the system of testing specimens of' diminished area, and then calculating that the metal examined will be as many times stronger as its area is greater, is an absolutely vicious one. I am quite prepared to say, that, either from their limited size or faulty construction, most of

Jan 1, 1882

By P. E. Cavanagh

SINCE the 1930's' the production of iron ore in Canada has increased from zero to about 15 million tons per year. In the same short period of about 25 years, the steel industry has doubled in output, while the consumption of steel has also doubled. In the 1930's all Canadian steel was made from imported iron ore, whereas today, Canada is exporting considerably more iron ore than she imports. It appears certain that the production of iron ore in Canada will at least double in the near future, and should be over 45 million tons per year at the end of the next 25 years, in 1980. It also appears certain that most of this iron ore will be exported to the United States, with some proportion going to Europe. In this situation, it is logical and proper at the present time for Canadians to consider means of converting some of all of this Canadian iron ore into semi-finished or finished products in Canada.

Jan 6, 1958

By Frederick Prime

AT the last meeting of the Institute, Mr. A. L. Holley read a paper on "Steel," in which he proposes for it a definition so opposed to the one generally received, as to call for some remarks. Until within the last five or six years there has been no dispute on the subject, and it seems worth while to investigate the matter. For not only does a proper tax on all importations depend on a proper appreciation of the term steel, but it is necessary to know whether steel, or wrought-iron, or homogeneous iron are requisite in all processes of manufacture in which malleable iron is employed, on account of cost, strength, etc. Karsteu* says : " Iron may be obtained, either as an unforgeable, unweldable metal, which melts at a high heat, termed cast-iron; or as a ductile, weldable, soft metal, which can only be melted at the * Karsten, Handbuch der Eisenhüttenkunde, 3d ed., vol. i, p. 6. Berlin, 1841.

Jan 1, 1876

A mine that staggers the imagination is Chuquicamata, the granddaddy of them all. In 1968 production exceeded 300,000 tons of copper. Production began in 1915 and mining proceeded solely on oxide ores until 1953 when the first treatment of sulfides began. Today the company has mined about 1.2 billion tons of all types of material since inception. The accelerating rate of output can be gauged by the comparable 1946 figure of production-to-date which was 350 million tons. No single mine comes close to touching Chuqui for productivity at its high annual metal yield mining only 90,000 tpd of ore at the luxurious waste-to-ore ratio of 0.6 to 1. However, the complexity of the operation is enormous and the experience required to synchronize the various processes is masked by normal operations and only becomes apparent in times of emergency such as when the slide took place in the pit in February.

Jan 11, 1969

By Samuel G. Lasky

The writer has been interested in determining the mineralogic dis-t,ribut.ion of silver in the base-metal ore of thc Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.' This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many districts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the proportionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impracticable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathematical method used, and to point out the value of using this method even when assays of pure specimens are available. Value of the Mathematical Method The obvious way of attacking the problem would be to separate cleanly large quantities of ore into its component minerals and then to determine the average silver content of each mineral by assay of representative samples. Since an absolutely clean separation is not feasible, it has been the practice, as mentioned above, to assay pure specimens of the different minerals. No one will contend seriously that the silver content of a base-metal mineral is constant throughout any particular deposit, and it will

Jan 1, 1935

By Samuel G. Lasky

The writer has been interested in determining the mineralogic dis-t,ribut.ion of silver in the base-metal ore of thc Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.' This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many districts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the proportionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impracticable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathematical method used, and to point out the value of using this method even when assays of pure specimens are available. Value of the Mathematical Method The obvious way of attacking the problem would be to separate cleanly large quantities of ore into its component minerals and then to determine the average silver content of each mineral by assay of representative samples. Since an absolutely clean separation is not feasible, it has been the practice, as mentioned above, to assay pure specimens of the different minerals. No one will contend seriously that the silver content of a base-metal mineral is constant throughout any particular deposit, and it will

Jan 1, 1935

The writer has been interested in determining the mineralogic dis-t,ribut.ion of silver in the base-metal ore of thc Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.' This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many districts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the proportionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impracticable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathematical method used, and to point out the value of using this method even when assays of pure specimens are available. Value of the Mathematical Method The obvious way of attacking the problem would be to separate cleanly large quantities of ore into its component minerals and then to determine the average silver content of each mineral by assay of representative samples. Since an absolutely clean separation is not feasible, it has been the practice, as mentioned above, to assay pure specimens of the different minerals. No one will contend seriously that the silver content of a base-metal mineral is constant throughout any particular deposit, and it will

Jan 1, 1935

By Samuel G. Lasky

The writer has been interested in determining the mineralogic dis-t,ribut.ion of silver in the base-metal ore of thc Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.' This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many districts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the proportionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impracticable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathematical method used, and to point out the value of using this method even when assays of pure specimens are available. Value of the Mathematical Method The obvious way of attacking the problem would be to separate cleanly large quantities of ore into its component minerals and then to determine the average silver content of each mineral by assay of representative samples. Since an absolutely clean separation is not feasible, it has been the practice, as mentioned above, to assay pure specimens of the different minerals. No one will contend seriously that the silver content of a base-metal mineral is constant throughout any particular deposit, and it will

Jan 1, 1935

We did install one 100% brick bottom in our #33 furnace which is basically the same design as Inland's furnace. We had previously embarked on a program of replacing all bottoms in our 300 ton furnaces every 2nd campaign which would be about every 2000 - 2300 heats. This had been necessitated by the effect of our rather high oxygen blowing rates and our desire to maintain a minimum bottom interval level. This meant that we were able to compare bottom performance of various types of materials on a realistic bas is. Since furnace availability is critical to our operation, we are organized to employ every piece of equipment and all the necessary man power to complete a rebuild in the shortest possible time. A 300 ton furnace requires 7.5 days to rebuild. If a new bottom is to be installed an additional 2.5 days is added - 24 hours for tear out and 36 hours for bricklaying - making a total of 10 days.

Jan 1, 1972

This Association is made up of Alabama members of the following technical societies: The American Society of Civil Engineers, American Institute of Mining Engineers, American Society of Mechanical Engineers, American Institute of Electrical. Engineers, American Chemical Society and the American Institute of Architects. The association organized last winter for the purpose of maintaining an organization among the technical men of the State of Alabama, to stimulate the development of the natural resources of the State, to foster public interest in all things beneficial to the State, to advance the interest of the technical profession in the State and to encourage social intercourse among its members. On June 30, 1917, an excursion was made to the power house of the Alabama Power Co. at Lock 12 on the Coosa River. This is the first meeting held outside of Birmingham and is also the first meeting to which ladies were invited. About 85 members and guests attended and the excursion was voted a great success by all present.

Jan 8, 1917

The following are excerpts from the report of the Treasurer of the United Engineering Society, for the year ending Dec. 31, 1915. Finances Due to the growth of the activities of the United Engineering Society, it was found desirable early in the year to consolidate the various accounts and financial records of the Society and of the Library, heretofore kept separately, and to have all the data pertaining to the building and its operation in the charge of one individual. An assistant secretary especially assigned to this work has been appointed, and a separate office has been established. The Finance Committee has had all of the records brought fully to date and has prepared a new set of account books to meet the new conditions. The Real Estate Account now includes the following items: Land $ 540,000.00 Building 1,050,000.00 Equipment 33,171.16 Founder Societies, Preliminary expenses 24,000.00 Total $1,647,171.16

Jan 4, 1916

By C. W. Haworth, M. G. Hall

THE diffusion of copper in silver has been studied by Sawatzky and Jaumot1 and Cahoon and Youdelis.2 Sawatzky and Jaumot measured tracer diffusion in single crystal specimens but the 12.9 h half-life of CU64 limited the time of the diffusion anneal to about 50 hr, and in consequence the minimum temperature of the investigation was 716°C. Cahoon and Youdelis employed polycrystalline diffusion couples, and measured the interdiffusion coefficient over the range 0 to 2 at. pct Cu. These experiments were performed at temperatures down to 630°C and a discontinuity in the Arrhenius plot was observed at -700°C. The high D-values at lower temperatures were attributed to the effect of grain boundary diffusion. The present experiments were undertaken to investigate this anomaly and study the low temperature region of the diffusion of copper in silver. The method employed single crystal samples and a plated source of copper. Silver single crystals 2½ by 4 in. sq were grown from zone-refined silver bar (>99.99 pct Ag) by the Bridgeman technique, and $ in. thick slices were cut by spark machining. The specimens were electro-polished, and a 2 µm layer of copper was electroplated on to the planar surface at one end of each specimen using a potentiostatic voltage source. The following solution was used for plating: CuSO4 . 5H2O 125 gm H2SO4 (S.G. 1.8) 53 ml H2O 1000 ml The diffusion couples were sealed in capsules, in an argon atmosphere, and were annealed at either 701, 597, or 498°C. The temperature measurements were made to an accuracy of *l°C After the anneal, the penetration of copper into the silver was determined using an electron probe micro-analyzer. 100 sec scaler measurements of the intensity of Cu Ka! X-radiation were performed at 2 to 5 µm intervals along a line normal to the source, with a beam potential of 25 kv. Allowances were made for the background radiation, and the dead-time of the counting system in the normal way, and the intensity ratios were corrected to weight concentration by the method of Duncumb & de-Casa.3 For the analysis of the diffusion profiles, it was first observed that the copper layer did not completely dissolve in the host crystal for the specimens annealed at 498 and 591 whereas for the specimen annealed at 701°C, a single phase solid solution was formed. For the 498" and 597°C specimens, the concentration of copper in the silver at the interface was therefore constant throughout the anneal and the analysis for a

Jan 1, 1970

By Carl F. Floe, John Chipman

A YEAR ago the authors published a paper on the solubility of sulphur dioxide in molten copper.1 The data in that paper agreed closely with that obtained by previous investigators, which, however, did not agree with the theoretical predictions for solubility of triatomic gases of this type. It has generally been assumed that the reaction of solution is: [ ] Neglecting the slight change in copper concentration and considering that the concentrations of sulphur and oxygen are both proportional to the volume of gas absorbed, it follows that this volume should be proportional to the cube root of the pressure. It was found that a plot of the volume absorbed versus the cube root of the pressure gave a straight line, but that this line did not pass through the origin. Calculations of the equilibrium constant for the reaction showed that it was fairly constant for pressures above l00 mm. but that actually it approached zero at lower pressures. The conclusion was made therefore that the solubility as determined could not be expressed by Eq. I or by any other simple equation, particularly at low pressures. Other investigators have concluded that the solubility of sulphur dioxide in copper as well as in several copper alloys is more nearly proportional to the square root of the pressure.* Such a conclusion, however, does not satisfactorily account for the results, even when rather complicated mechanisms for the solution are assumed. The highly improbable speculations of Lepp2 and of Schneider and Esch3 based upon hypothetical dissociation pressures of Cu20 and (a; 2S dissolved in copper illustrate the type of reasoning that has been used to account for the discrepancy. In the discussion of the previous paper, the authors pointed out that the discrepancy might possibly be due to impurities in the copper, although the purest form available was used. Further consideration of the problem suggested that the impurities likely to have the greatest effect on the solubility of SO2 in copper were oxygen, sulphur and carbon. Accordingly, further experiments have been made to show the effects of these elements. EXPERIMENTAL METHODS The apparatus used for measuring solubility was essentially the same as that shown in the previous paper. However, since it was desired to make measurements at low pressures, a McLeod gauge was added and 6-mm. glass tubing was substituted for the capillary. This increased the "hot volume" considerably but was necessary in order to obtain good vacuums in a reasonable length of time. A mercury diffusion pump was also installed.

Jan 1, 1942

By H. D. Kiddle

IN mining in Malaya has been a courageous ad- venture in private enterprise, attended by all the hazards of prospecting in unexplored areas of tropical jungles-jungles that still cover four-fifths of the country. To assess the contribution of an industry to a country's revenue, it is necessary to consider not only duties levied on the products, but also the revenue from all businesses and individuals directly and indirectly deriving income from the industry. Exact figures are not obtainable, but from 1850 until shortly before the first World War, tin mining in Malaya was a dominant factor in the Federation's development. Even at the turn of the century, tin export duty alone represented 45 pct of total Government revenue, while in the 40-year period up to the end of 1937, tin ore duties collected by the Federated Malay States Government amounted to 383,- 81 0,284 Malayan dollars,* approximately one-fifth of the total revenue for the same period.

Jan 11, 1957

By O. B. Bennett

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

Jan 12, 1954