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By E. R. Borcherdt

IT is notable that the first large-scale mine operation equipped entirely with detachable bits was the Badger State mine of the Anaconda Copper Mining Co. in Butte, Montana, just 30 years ago. This mine in 1922 was producing approximately 1200 tons of ore per day. Much of the data presented in C. L. Berrien's article' describing the development and installation of the Hawkesworth detachable drill bit were obtained from these operations. As in any pioneering effort, no precedent existed and many difficult problems required solution, so that the changeover to detachable bits at all Butte hill mines was not completed for 6 years. There was widespread disbelief as to the probable efficiency of the new installation. Some attempts were made in 1931 by the owners of the Hawkesworth patents to interest Ontario gold mine operators in the bit. These efforts were not successful, but they undoubtedly stimulated thinking which resulted in the invention and patenting of several well-known Canadian detachable bits, one of which is now a widely used throwaway bit. The success of the Butte installation also led to the development of the threaded type of bit connections by several well-known manufacturers, and in 1935 these bits were introduced to the mining industry on a national scale. The original Hawkesworth bit was not provided with a water hole but, depended upon water passing through the clearance opening between the tongue in the bit and the groove in the rod to flush cuttings from the drill hole, see Fig. 1. In December 1935 it was found that this method of introducing drilling water to the bit face resulted in high dust counts. To correct this a water hole was drilled on the central axis of the bit, passing through the tongue. Unfortunately, quenching water would rise through the small water hole, spot-hardening the tongue to cause breakage, never completely eliminated. In the fall of 1936 large-scale tests indicated that savings would be effected by use of a threaded type of bit, which was therefore adopted as standard for all Butte mines. This type of bit was used until 1947, when it was superseded by a one-use slip-on type. Since the first use of the Hawkesworth bit every detachable bit of importance has been investigated, and where advantages which might reduce costs or increase efficiency were indicated, substantial tests of the bit were carried on in the Butte mines. When tests demonstrated the advisability of changing from one kind of detachable bit to another the change was made at one level or in one area each day until the new rod and bit equipment was used throughout the mine. This involved a minimum of cost and disruption of drilling. Intelligent selection of a detachable bit to obtain optimum results requires careful consideration to achieve a balance between the three principal types of equipment used in the drilling process: 1—drill bits, 2—drill steel, and 3—drilling machines. Optimum results imply maximum output and minimum cost per unit of output. Since every rock type differs in drillability and it is generally impractical to provide equipment for more than one or two types of rock which may occur in one operation, selection of equipment must encompass average drilling conditions. However, on exceptional occasions several widely differing conditions may make it mandatory to provide equipment best suited to each condition. The choice of rock-drilling equipment is a most controversial subject and one that is further complicated by unreliable and frequently misleading performance claims. Small operators without the means for making accurate evaluations of equipment frequently suffer from these over-enthusiastic claims. It is apparent from experience in rock drilling throughout the world that rock drillability is not alike in any two places, and that selection of proper equipment can only be made after conducting thorough trials of various types of equipment. Some recent drilling tests in tactite and hornstone at the Darwin, California mine of the Anaconda Co. present some interesting clues on rock drillability. Microscopic examination of thin sections of these rocks reveals that mineral composition and rock texture are equally important in governing drillability. The Darwin hornstone is at times so abrasive that the carbide bit cutting edges become flattened to 3/32 in. in 2 to 4 ft of drilling, and some carbide bits were dulled to this point after 9 to 10 in. of drilling. This wear was determined to be the proper point for resharpening to eliminate carbide insert breakage or breakage of the steel rod when drilling with 1½ to 1?-in. bits, with a drifter of 2 3/4-in. diam and 90 to 100 psi air pressure, see Supplement A. Before considering the merits of various bit designs it may be well to review the mechanics of drilling rock with percussion drills. A sharp bit cuts by penetration and chipping. The amount of penetration governs the amount of chipping and depends upon the contact area of the cutting edge, the foot-

Jan 1, 1954

By Paul B. Barton

Unconventional mineral deposits are those that differ significantly from productive deposits in mineralogy, grade, or geologic setting. Thus, the initial representatives of each deposit type are, by definition, “unconventional” until they are exploited. The “unconventional” status changes to "conventional" because of economic shifts (e.g., bulk silver ores), because of technological innovations (e.g., froth flotation), or simply through the recognition of, and production from, novel mineral concentrations. Heretofore the discovery of new deposit types has been almost entirely accidental, but the long- established concept of the geochemical cycle provides a nearly untouched opportunity and challenge for the application of geochemistry in predicting novel, potentially economic, mineral concentrations.

Jan 1, 1983

By R. F. Slack, J. C. Draper, J. A. Younkins

In 1959, the Duquesne Light Co. was faced with the problem of moving more than 40 million tons of bituminous coal in Greene County, Pa. The coal had to travel a distance of about 4 ½ miles from a new mine portal in Rocky Run Valley to the company preparation plant and loading facilities on the Monongahela River. After careful study of this immense transport problem, Duquesne decided that the belt conveyor system described in the following pages offered the best solution. This system, now in operation, is probably one of the four or five longest permanent overland conveyor systems in existence. The general layout of the entire system is shown in Fig. I. A detailed description of the salient features of the system is presented below. THE MINE The valley of Rocky Run where the system begins is very, very narrow and very steep. It was chosen as the site of Duquesne's new mine portal because it was the only place on this particular property where the Sewickley coal seam cropped out. The valley also had two other advantages. First, it fronted on a state road and, second, it offered a site where some 4 million gallons of water could be stored for use in dust-allaying sprays needed in the mine. The company elected to construct a drift mine in the valley because this would require neither the hoisting time of a shaft mine nor the walking time of a slope mine. As part of the mine construction project, the valley was leveled by relocating its stream and filling its center with material cut from each side.

Jan 11, 1966

By Boyd Dudley

The material presented in this paper is an abstract of a thesis submitted by the writer to the faculty of the Massachusetts Institute of Technology, as part requirement for the degree of Master of Science. The investigation was undertaken at the suggestion of Prof. H. 0. Hofman, and it was conducted, under his direction, in the laboratories of the Mining Department of the Institute. The purpose of the work was, first, to study some of the reactions that have been considered as a part of the mechanism of the chloridiz-ing roast, and second, to study the conditions under which nickel oxide and copper oxide may be chloridized. While the production of chlorine gas by various reactions during the chloridizing roast may not be primarily useful in the chloridation of metal oxides and compounds, it nevertheless serves a useful purpose in preventing the dissociation and decomposition of chlorides once they have been formed; for example, the dissociation of cupric chloride into cuprous chloride and chlorine. Therefore it was thought that a study of some chlorine-producing reactions would prove of interest, and the first series of experiments dealt with this phase of the subject. he object of the latter part of the work was to show the possibility of treating heavy sulphide ores, such as those of Sudbury, Ontario, containing much iron and small amounts of copper and nickel, by chloridizing and removing the copper, leaving an iron-nickel oxide product suitable for smelting in the blast furnace for nickel-bearing pig iron. The chloridizing of the copper would, of course, be preceded by a roast for the removal of sulphur, the sulphur oxides being available for the manufacture of sulphuric acid, if under the local conditions this product would be of commercial value. Reactions of the Chloridizing Roast Reaction of Sodium Chloride, Sulphur Trioxide, and Oxygen.—The first reaction studied was that involving the production of chlorine

Jan 1, 1915

Jan 1, 1928

By R. V. Norris

The removal of mine-water by hoisting in tanks instead of pumping, while somewhat a reversion to the methods of the ancients, has come very rapidly into favor in the anthracite region of Pennsylvania during the past few years. In fact, so much so, that at the present time there are at least eight large collieries at which all the water is hoisted, and six more plants are in preparation. The particulars of the plants in operation and under construction, as far as decided on, are given in the tables on pages 107 and 108. Besides these, the Delaware, Lackawanna and Western R.R. Co. is constructing a hoist of large capacity for a depth approximating 500 feet, to be located in the Keyser Valley, near Scranton. The hoists will be driven by electric motors, geared directly to the sheaves. The Lehigh Valley Coal Company is planning a large hoist for the Packer collieries in the Shenandoah district, but no work has been done on this as yet. The earliest regular hoisting, I believe, mas done by means of semi-cylindrical tanks (Fig. 1) at the Nanticoke collieries of the Susquehanna Coal Company. These tanks were attached under the regular shaft-carriages, taking in water through six large clack-valves in the bottom, and discharging through an endgate opened by a lever which was operated by a guide-piece on the shaft head-frame. These tanks were designed July, 1880, by the late J. H. Bowden, one of the very early members of the Institute. Similar tanks are still used in emergencies at the Nos. 1, 2, 3 and 6 shafts of the company. The objections to. their use were: that water could only be hoisted during the night-shift, or when the shafts were not in use for hoisting coal, thus requiring a very large sump, and greatly limiting the water capacity of the plants; that the alternate wetting and drying

Jan 1, 1904

By R. G. Mallon, R. L. Braun

Primary copper-sulfide ore deposits that are well below the water table can be chemically mined by in-situ high-pressure leaching. The leaching is accomplished by pumping oxygen gas into the bottom of a large underground flooded column of rubblized ore. Part of the injected oxygen dissolves under the high hydrostatic pressure in the column. With a high enough injection rate, the excess oxygen gas induces a convective circulation of oxygenated solution within the rubble column, which transports dissolved oxygen throughout the system. At elevated temperatures, this results in a relatively rapid dissolution of the copper minerals. A method of calculating the leaching rates is presented. The calculation is done by means of a finite-difference computer code that couples all of the processes relating to copper leaching, convective circulation, and the injection, dissolution, and consumption of oxygen. Results of the calculation for a typical case show that over 70% of the copper can be extracted in less than six years with good efficiency in oxygen utilization.

Jan 1, 1976

Jan 1, 1944

Jan 1, 1944

Sulfuric Acid and Phosphate Industries at Anaconda Reduction Works. BY E L LARISON (Contribution 70-Preprint 4400 words) In 1915 a 135-ton chamber sulfuric acid plant was built at the Anaconda Reduction Works to supply acid for leaching sand tailing Sulfur dioxide was obtained by roasting copper table concentrate Soon after, the flotation process, using acid as a reagent, together with development of a leaching and electrolytic process for zinc recovery, necessitated building a second acid unit of 50 tons' per day capacity, completed in 1917 Within a few months the zinc process was so improved as to consume no added acid Mean¬while research work was in progress on production of phosphate fertilizers using sulfuric acid and Idaho phosphate rock In 1920 a pilot plant was put into operation which treated 50 tons per day of phosphate rock to produce treble superphosphate containing 45 per cent available P205 In 1922 the original plant and process for leaching of sand tailing were abandoned in favor of a combination leaching and flota¬tion process In 1923 the sand leaching plant was remodeled into a treble super¬phosphate plant designed to treat 160 tons per day of phosphate rock. In 1924 the copper flotation process was put on alkaline circuit and acid, has not since been used as a reagent Practically all the acid produced is now used for making phos¬phate products In 1931 the use of copper concentrate as a source of sulfur dioxide was abandoned and an iron concentrate, floated from the copper concentrator tail¬ing, substituted

Jan 1, 1935

By Charles A. Ashburner

THE appliances which have been proposed, and the modifications in the construction of boiler-furnaces which have been made for the prevention of smoke, and the utilization of what are ordinarily called the waste products of combustion, have been innumerable.

Jan 1, 1882

By Donald Jaffe, Michael B. Bever

The solidification of Al-Zn alloys (2 to 70 pct Zn was investigated at different rates of solidification. The resulting structures were studied; the amounts of nonequilibrium eutectic were measured and compared with the amounts calculated on the assumption of no diffusion in the solid. The compositions of the cored primary constituent were investigated by quantitative autoradiography after activation of the zinc by neutron irradiation. These compositions were also determined from microhardness values. IN a recent investigation of the soltdification of aluminum-rich AI-Cu alloys,' the amounts of non-equilibrium eutectic were measured and compared with the amounts calculated on the assumption of no diffusion in the solid. The compositions of the cored primary constituent were investigated by quantitative autoradiography. The work reported here extends the investigation of nonequilibrium solidification to the Al-Zn system in the range from 2 to 70 pct Zn. In addition to autoradiography, microhard-ness values were used to determine compositions on a micro scale. Solidification Experiments The alloys contained approximately 2. 6, 12, 20, 30, 50, and 70 wt pct Zn and the balance aluminum. According to published diagrams the eutectic reaction occurs at 382°C between the eutectic liquid (95 pct Zn), a (82.8 pet Zn), and $ 498.9 pct Zn). Solid-state reactions at lower temperatures (due to the miscibility gap between 350" and 275"C, the eutectoid at 275'C, and the precipitation from supcrsaturated a) did not affect this investigation. Even if they occurred to any appreciable extent, they did not alter the evidence pertaining to the solidification structures. The alloys had to be of high purity to avoid radioact~ve contamination during activation. The aluminum analyzed 0.015 pct Si, 0.009 pct Fe, less than 0.004 pct Cu, and less than 0.006 pct Mg with traces of sodium and titanium; the zinc was reported to be at least 99.99 pct pure with traces of iron and magnesium. The alloys were prepared under argon in an induction-heated, bottom-pouring furnace, and poured into a coated steel mold, which could be preheated to temperatures up to 700°C in order to control the rate of solidification. The pouring temperatures ranged from about 40" above the liquidus for 2 pct Zn alloys to about 130°C above the liquidus for 70 pct Zn alloys. As soon as the melt entered the mold, the readings of a thermocouple placed % in. above the bottom of the mold were recorded by a recording potentiometer. Cooling at the rate induced by the initial temperature of the mold was continued to a temperature 100°C below the liquidus; the mold with its contents was then quenched in icy brine. Quenching from a fixed interval below the liquidus was used to provide a standardized procedure, since the solidus and liquidus temperatures and the interval between them vary greatly over the composition range investigated. The temperatures from which the samples were quenched were below the equilibrium solidus, but under nonequilibrium conditions some liquid was still present. This residual liquid solidified during the quench. The samples measured 314 in. diam and 11, in. height. Drillings for chemical analysis were taken

Jan 1, 1957

By R. B. Sudderth, C. R. Merigold

Greater, emphasis is being placed on recovering nickel from laterite ores by ammonia leaching techniques. New methods are required for lower cost, non-polluting techniques to separate more efficiently the metals of interest. Liquid ion exchange techniques meet these requirements with the added advantage of producing salable electrowon nickel cathodes at the plantsite. A complete solvent extraction- electrowinning process is described, including preliminary engineering and cost data for a typical plant producing 50 million pounds of nickel per year.

Jan 1, 1973

By P. W. Harben

Jan 1, 1985

By Chas. A. Ashburnea

THE appliances which have been proposed, and the modifications in the construction of boiler-furnaces which have been made for the prevention of smoke, and the utilization of what are ordinarily called the waste products of combustion, have been innumerable.† †There is now open in London an exhibition "of apparatus of all kinds devised to prevent smoke."

Jan 1, 1882

By R. W. Raymond

Jan 1, 1905

By James A. Brierley, Corale L. Brierley

Microorganisms have been considered as agents which may be of importance in catalyzing hydrometallurgical processes for the extraction of metals from low-grade ore minerals. Various microorganisms and their role in bacterial leaching are described. Bacterial leaching as applied to copper, uranium, zinc, lead, and coal is discussed.

Jan 1, 1981

By Elihu Thompson

The subject of welding by electricity has been so recently and so ably treated by Sir Frederick Brsmwell before the Institution of Civil Engineers* as to render evidently superfluous there-statement on this occasion of many facts and considerations which might be appropriately advanced, had they not been so well discussed in his paper already. The electrical arts grow rapidly in these days—a fact which is strikingly illustrated in the development of electric railways. In

Jan 1, 1891

Elected Died 1895 *ABBOTT, AI ATTHUR 1908 1882 *ABBOTT, ARTHUR V 1906 1903 * ADAMS, CHARLES C. 1905 1905 * ADAMS, WILLAMS 1909 1884 *ADDY, MATTHEW 1896 1889 * AKERS, WILLIAMS 1906 1894 *ALLEN R B 1896 1905 * ALLEN, R. SCOTT 1906 1874 *AMIOT, H 1892 1886 *AMSLER, CARL 1894 1895 *ÅNGSTROM, CARL 1901 1900 * ARLETT, GEORGE H 1906 1895 *ARMSTRONG, JOHN F 1898 1882 *ARNOLDS, HUGO 1886 1875 *ASHBURNER, CHARLES A 1889 1872 *ASIIBURNER, WILLIAM 1887 1883 *ATKINS, C M , JR 1885 1905 * AUSTEN, PETER T 1907

Jan 1, 1910

Six hundred miles inland from Australia's east coast Port of Townsville in Queensland's sea of rock and spinifex lies Mount Isa. The town, as in most mining towns, is dominated by its mine and the mine in turn is dominated by its 503 ft copper smelter stack. This candy and white painted stack is a striking introduction to one of the world's greatest copper producing mines and a town where people of over 40 different nationalities live remote but well. Mount Isa Mines Limited is surging into the ranks of' the world's great mines on the momentum of a relentless push begun in 1956. It is as if the time lost in the lean years of the past should be caught up in a hurry.

Jan 10, 1964