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By F. R. Lee

[WHEN the Bureau of Mines was established in July 1910, one of the problems immediately attacked by the new organization was the development of standard, for the design and testing of electrical equipment that could be used without fear of initiating fires and explosions in underground coal mules. Research and investigation by Bureau personnel, supplemented by the published results of similar work by European mining authorities, led to the establishment of standards or "schedules." which guide manufacturers in the design of many types of electrically operated machines and devices used in. underground coal Mining. By issuing these standards, Bureau personnel establish the requirements to be met by such equipment before it tan be approved by the Bureau of Mines as permissible for use in gassy coal mines. Every 2 years the Bureau of Mines publishes a list of equipment that leas been accepted as approved or permissible during the preceding 2 calendar years. This is done to inform the mining industry of the availability of the latest equipment for safe use underground.]

Jan 1, 1964

By Chester O. Ensign

The White Pine Mine is situated in the southwestern portion of the Keweenaw Peninsula of Upper Michigan approximately 6 miles south of Lake Superior (Fig. 1). It is east of the Porcupine Mountains in Ontonagon County. The ore deposit is about 70 miles southwest of the famous native copper deposits of the "Copper Country" lying northeast of Houghton. Geological conditions are different at every mine and create a special set of problems in dilution control. This paper is largely intended to describe the techniques applied in mine dilution control (grade control) at White Pine, and present results of the program. For necessary background information major geologic characteristics of the deposit, particularly those that exert control over the distribution of ore, are briefly discussed. Mining methods are described in considerable detail since applied grade control techniques are adapted to these.

Jan 1, 1964

In 1961, West Australian Petroleum's Eneabba No. 1 bore encountered 22 seams of coal totalling 40 ft in thickness between the depths of 6373 ft and 6441 ft. On analysis, this coal had a similar calorific value (8000-HOOO B.T.U./lb, assuming 20 per cent water) to the coal from the Collie Coalfield, Western Australia's only known area of commercially exploitable coal. Being buried to depths in excess of 6000 ft, the coal at Eneabba had developed weakly-coking properties, and thus, although much younger than the Permian coals of Collie, gave promise of being a major potential source of power for Western Australia.West Australian Petroleum undertook a programme of stratigraphic drilling and shallow test drilling to determine whether this coalhorizon persisted into the outcrop of the Lower Jurassic sediments in the Hill River district, 140 miles NNW. of Perth, and, if it was present, if the quality and quantity of the coal would warrant development of the deposits by open cutting. The coal horizon was identified in the near surface, but the poor quality of the coal and the complexity of the structure made development (in the area examined) uneconomic at the time.A strong seismic reflection in the Eneabba area occurs at the same depth as the Jurassic coals. This event originates within the upper beds of the Lower Jurassic and it is probable that the velocity contrast between the higher velocity siltstones and the very low velocity coals enhances this very strong, distinctive seismic reflection.This event can be followed on continuous seismic data over a large area of the northern Perth Basin, from 13 miles SE. of Dongara to 20 miles SW. of Coorow. It can be followed from a depth of 4000 ftnear Dongara to over 17,000 ft to the SE., so development of thisvast potential source of power will depend on the economics ofprocesses being developed for the production of power from theburning of coal seams in situ.INTRODUCTIONThe discovery of 22 seams of economically useable coaltotalling 40 ft in thickness in the Lower J urassic sedimentsof the Eneabba No. 1 bore (Fig. 1) led to the search forthese seams at economically workable depths. The Ministerfor Mines in Western Australia granted to West Australian1. Supervising Geologist, West Australian Petroleum Pty. Ltd.Manuscript received at The Institute, 25th May, 1964. and presented to the 1964Annual Conference.

Jan 1, 1964

By H. I. Aaronson, H. A. Domian

The self-diffusivity of Ag10 has been measured as a function of temperature and composition in AgMg. a CsCl-type intermetallic compound with a substitutional defect structure on both sides of the stoichiometric (50 at. pct Mg) composition. These measurements show that In D increases linearly, and both In Do and Q decrease linearly with deviation from stoichiometry. The slopes of these lines are significantly steeper in magnesium-rich alloys. Equations for the variation of Q with composition have been derived by application of the theory of random walk processes on the assumption that diffusion in compounds of this type takes place by the six-jump cycle mechanism of Huntington, Elcock, and McCombie. The favorable agreement obtained with experiment furnishes fresh support for the correctness of this assumption. A principal result of this treatment is that. although the concentration of vacancies is considerably higher in the silver sublattice than in the magnesium sublattice, the acfivation energies for movement of the magnesium sublattice vacancies are so much lower that these vacancies are responsible for effectively all diffusion of silver in this compound. A tendency for vacancies of both types to be kinetically bound to wrong atoms is also noted. THIS study was undertaken to examine the influence of substitutional defects upon self-diffusion in an intermetallic compound, AgMg, with a CsCl-type crystal structure. The CsCl structure is exception- ally simple. At the equiatomic or stoichiometric composition in a binary alloy, it consists of two interpenetrating simple cubic sublattices, each of which is exclusively populated by the atoms of one species. When atomic size and other factors are favorable, deviations from stoichiometry can be entirely accommodated by the substitution of atoms of the species present in excess of 50 at. pct on the sublattice of the other species on a one-for-one basis. Under this condition, the only vacancies present are those formed by thermal activation. The excess atoms thus incorporated into the sublattice of the minority species may be considered as substitutional defects in this sublattice. Several X-ray studies have shown that the defect structure of AgMg is entirely of the substitutional type on both sides of the stoichiometric composition.1"3 The thermodynamic investigation of Kachi indicates that, aside from a low level of thermal disorder and these constitutional defects, order is maintained to the solidus temperature. This compound is therefore a particularly useful vehicle for a study of the influence of substitutional defects upon diffusion kinetics. Other advantages of AgMg for this purpose include: the broad composition region, as much as approximately 10 at. pct on either side of the stoichiometric (50 at. pct Mg), in which the compound is stable; the comparatively low temperature range of the solidus (820°C and below),5 making diffusion anneals near this range experimentally convenient; the reasonably good machinability of the compound, permitting utilization of the standard sectioning method of radiotracer analysis; and the availability of a good tracer, A for one of the constituent species. While this investigation was in progress, Hagel and westbrooks reported data on the self-diffusion

Jan 1, 1964

By R. B. Anderson

As a part of a Bureau of Mines program on the conversion of coal to liquid and gaseous fuels, the kinetics of the Fischer-Tropsch synthesis on iron catalysts was investigated. Nitrided catalysts were studied at 21.4 atmospheres using feed gases ranging from 2H2+1CO to 0.25H2+1CO, and at 7.8 to 21.4 atmospheres using 1H2+1CO gas. The overall apparent activation energy increased with increasing carbon monoxide content of the feed gas from 19.5 kcal/mole for 2H2+1CO to 23.7 for 0.7H2+1CO. The rate of synthesis with 1H2+1CO feed increased linearly with operating pressure from 7.8 to 21.4 atmospheres. A semifundamental rate equation of the form [r=a'PH2 0.6pco 0.4- ?r0.5PH200.5] was shown to fit the data satisfactorily. The relative usage of hydrogen to carbon monoxide decreased with increasing conversion, passed a minimum, and then increased. Apparently water is the principal primary product and carbon dioxide is produced by subsequent water-gas shift reaction. In another group of experiments water, carbon dioxide, argon, and methane were added to 1H2+1CO feed to a nitrided iron catalyst. Argon and methane were only diluents. Carbon dioxide was a slight inhibitor and water vapor was a strong inhibitor to the rate of synthesis. Water accelerated the water-gas shift and usually increased methane production. Important factors of catalyst geometry in determining rate were found to be particle size and extent of reduction. Apparently the active portion of the catalyst is confined to a layer of 0.01 to 0.02 cm from the external surface of particles. A special solution was made of differential equations relating re¬action at the catalyst surface to diffusion in pores of the catalyst for spherical particles with an active layer surrounding an inert core. The equation derived expressed the experimental data reasonably well. Diffusivities determined by this equation varied from 3 to 24X10-6 cm2/sec; these values are of the same magnitude as observed for the diffusion of gases in liquid. The appendix presents a group of synthesis experiments at pressures of 21.4 to 103 atmospheres. In this range the rate of synthesis on nitrided iron catalysts increased with pressure to the 0.74 to 0.84 power.

Jan 1, 1964

By A. Lawley S. Schuster

The tensile behavior of copper foils prepared from rolled bulk material has been studied over the thickness range 2 to 53 , and for a range of pain sizes. For foils of comparable grain size, having the cube texture and tested along (100), yield strength increases with decreasing foil thickness t below -26p, with a corresponding decrease in ductility. Deformation occurs in the form of localized slip clusters distributed throughout the gage section. To the extent that the tensile strength (10 to 18 kg mm-) is unaffected by foil thickness, and that the foils possess fair ductility, the stress-strain behavior resembles that of bulk material rather than that of whiskers or evaporated films of comparable dimensions. The dependence of yield strength o on foil thickness t below -26p is of the form: oy = oo + kt-1/2. Possible explanations for the stress increase are considered based on 1) the dependence of active dislocation source length on foil dimensions, 2) the locking of surface sources, or the blocking of mobile sources at the surface due to surface film. It is now well-established that filamentary whiskers of many materials show exceptionally high strength compared with bulk crystals.'-11 As the diameter of the whiskers decreases to -1, the observed fracture strength approaches, and in certain cases exceeds, the calculated shear stress for the nucleation of slip in a perfect crystal.' In general, the stress-strain curve is entirely elastic, with strains at fracture approaching 1 pct. Similarly, thin films12-24 of evaporated or electrodeposi-ted material have been shown to possess tensile strengths three to seven times that of bulk material, with total strains at fracture -1 to 2 pct. In the present study, attention has been directed to the room-temperature tensile behavior of thin foils of copper over the thickness range 2 to 53, prepared from rolled bulk material. Yield stress, ultimate tensile strength, elongation to fracture, and work-hardening behavior are measured as a function of grain size and foil thickness. Structurally such foils are superior to either evaporated or electrodeposited films, and in the recrystallized condition exhibit considerable ductility. Apart from preliminary work by Sumino and Yamamoto25 on the work-hardening behavior of rolled and recrystallized copper foils, no systematic tensile studies have been carried out on material of this form. EXPERIMENTAL PROCEDURE Tensile specimens were prepared from 99.995 pct purity rolled copper foils of thickness 2, 6, 12, 26, and 53, obtained from the Hamilton Watch Co., Lancaster, Pa. Irrespective of specimen shape, it is necessary to use tensile foils with edges free from notches or tears. To this end, any form of cutting operation was excluded, and the tensile foils prepared using a photoengraving process, the details of which are described elsewhere.26 Since tensile data are required under conditions of uni-axial stress, the specimen shape is extremely important. Ideally, the foil should be infinitely long, allowing a gradual taper from the grip area to the gage section; however, from a practical standpoint, long foils are easily damaged during testing. A modified tensile specimen was therefore selected having a parallel gage section 1.25 by 0.20 in. with a tapered shoulder section increasing to 0.5 in. at the grips, and an over-all length between grips of 4 in., Fig. 1. In practically all tests, these foils fractured within the parallel gage section. By approximating the foil contour (Fig. 1) to a hyperbola it is possible to analyze the stress distribution in the tensile foil using two-dimensional elasticity

Jan 1, 1964

By F. R. Lee

When the Bureau of Mines was established in July 1910, one of the problems immediately attacked by the new organization was the development of standard, for the design and testing of electrical equipment that could be used without fear of initiating fires and explosions in underground coal mines. Research and investigation by Bureau personnel, supplemented by the published results of similar work by European mining authorities, led to the establishment of standards or "schedules." which guide manufacturers ill the design of many types of electrically operated machines and devices used in underground coal Mining. By issuing these standards, Bureau personnel establish the requirements to be met by such equipment before it tan be approved by the Bureau of Mines as permissible for use in gassy coal mines. Every 2 years the Bureau of Mines publishes a list of equipment that leas been accepted as approved or permissible during the preceding 2 calendar years. This is done to inform the mining industry of the availability y of the latest equip¬ment for safe use underground.

Jan 1, 1964

By P. L. Russell

The use of nuclear explosives for excavation has been demonstrated to be feasible and practical. Application of nuclear explosives for overburden removal from large ore deposits appears to offer economic advantages over present methods, but under the present pricing schedule, high-yield devices must be used to obtain an economic advantage. The use of nuclear explosives presents problems not inherent in the use of conventional explosives, and thus they can be used only in areas where large explosions and associated phenomena can be tolerated. Stripping of coal with nuclear explosives does not appear practical at this time, but stripping overburden from copper or iron ore deposits may be a potential use. Even here, however, the use of nuclear explosives would require isolation, favorable topography, favorable ground-water conditions, and a low population density. If these basic requirements can be met, the use of nuclear explosives for overburden removal would offer both economic and time advantages. The possibility of using nuclear explosives for peaceful purposes was a subject for speculation as early as 1945. The PLOWSHARE Program was formally established by the AEC in June 1957 for the purpose of developing and demonstrating peaceful applications for nuclear explosives. The technical direction of the program is the responsibility of the Lawrence Radiation Laboratory, Livermore, Calif. Mining and excavation were two fields that received early consideration as areas in which nuclear explosives might be used. Knowledge gained from underground weapons testing increased this possibility, and the development of the thermonuclear device which has a small fission-to-fission ratio, reduced the hazard of radiation, and spurred interest. Nuclear explosives appear to have the greatest potential in the following mining operations: 1.— Surface Mining a) Stripping of waste for open-pit excavation b) Breaking of ore in open-pit mining c) Quarrying d) Blasting for production of aggregate, riprap, etc. 2. — Underground Mining a) Block caving application b) Crushing of ore for in-situ leaching, etc. c) Preparation of underground waste disposal areas Of the potential applications, excavation is perhaps the most obvious and the best understood, and probably the most practical for use in the near future. Large quantities of rock and earth can be moved by proper emplacement of nuclear explosives, but economic and practical relationship must be determined between the known capabilities of nuclear explosives and the required excavating to remove overburden. REMOVING OVERBURDEN IN OPEN-PIT MINING Removing the overburden is one of the largest jobs in open-pit mining. In 1960 open-pit mines produced approximately 130 million tons of coal, 108 million tons of copper ore, and 135 million tons of iron ore. To obtain this much production, an estimated 3-billion tons of overburden were removed from the coal, 216 million tons from the copper ore, and 135 million tons from the iron ore. These figures do not include the initial stripping required before ore production. For example, the ASARCO Mission mine started stripping operations in August 1959 and by mid-November 1961 had removed 46.3 million tons of material including 1.2 million tons of ore.* Initial excavation of this type offers the most favorable conditions for utilizing the earth-moving ability of nuclear explosives. EXPLOSIVE CASTING FOR REMOVING OVERBURDEN The use of explosives to remove overburden is not a new idea. Conventional explosives have been used for this purpose for many years with varying degrees of success. Several small coal strip operators have used this idea to increase production. At these mines about one-third or more of the overburden is thrown by explosives across the pit and onto spoil piles. The additional costs of drilling more blast holes and more explosives are more than compensated for by a reduction in the time required to uncover the coal, and by an increase in coal production.

Jan 1, 1964

By Melvin P. Silverman

The literature on methane-oxidizing bacteria is reviewed in regard to (1) the growth and isolation of cultures by special techniques; (2) the distribution of these organisms in nature and descriptions of individual species; (3) the physiology of methane-oxidizing bacteria as influenced by temperature, light, pH, aerobiosis versus anaerobiosis, and carbon and nitrogen sources; and (4) the biochemistry of methane oxidation revealed by studies with intact cells and subcellular systems. Present practical applications of methane-oxidizing bacteria are limited to prospecting for natural gas and petroleum deposits. Desirable areas for future research are discussed as well as some possible applications such as (1) the removal and/or early detection of methane gas in coal mines by intact cells or enzyme preparations; (2) the generation of electrical energy by microbial fuel cells using methane as fuel; (3) the growth of methane-oxidizing bacteria on methane for their food value; (4) the purification of hydrocarbon gas mixtures using methane-oxidizing or other alkane-oxidizing bacteria; and (5) the synthesis of methane from mixtures of H2 and CO or H2 and CO2 by me thane-forming bacteria.

Jan 1, 1964

By A. W. Fletcher

A nickel-copper sulphide concentrate was treated in a pilot plant at Warren Spring Laboratory during 1961, by a hydrometallurgical roast-leach- solvent extraction process devised to cleanly separate the metal values, and produce acid sulphate liquors containing the metals. It is shown that 86 percent of the nickel and 95 percent of the copper could be leached from the calcine, after a sulphatizing roast on finely ground flotation concentrate. Iron was removed from the leach liquor by limestone neutralization with a small loss of values. Copper and nickel were separated by solvent extraction with naphthenic acid in kerosene after partial neutralization of the iron-free liquors with ammonium hydroxide. Hydrogen sulphide and chlorine were used to remove zinc (and residual copper) and cobalt impurities respectively. The recovery of pure copper and pure nickel, by electrowinning, from the acidic solvent extract strip liquors finally produced, appears technically feasible.

Jan 1, 1964

By John C. Draper

Little precise information is available on the effect of mining on the surface topography. It is often assumed that after mining the surface will simply sink. This is not an infallible conclusion as is well illustrated in two of the three examples herein. This paper describes the results of an attempt to precisely measure the surface movement in the area around coal pillars left in place for three oil wells in a completely mined and caved area at the Harwick Mine of the Duquesne Light Company. The dates when the various measurements were made are shown on the data sheets and indicate the rate of surface movement. These oil wells are identified as wells Nos. 2, 3, and 6. This mine property is located on the north side of the Allegheny River at Cheswick, Pennsylvania, and extends in a northerly and westerly direction about five miles. The three well pillars are situated on the westerly side of the Bessemer and Lake Erie Railroad some 2,000 feet from Rural Ridge, Pennsylvania (Fig, 1).

Jan 1, 1964

By Kenneth H. Johnston

This report describes an in situ combustion project and three waterflood projects in Allen, Anderson, and Wilson Counties, Kansas, that will be visited during the 1964 annual tour of the Kansas-Oklahoma Waterflood Association. Among the unique features of the projects are the movement of heavy crude oil through the reservoir and into the wellbore with energy furnished by burning s portion of the crude oil therein. Another feature is the simultaneous injection of C02 and water, through separate tubing into input wells during early development, to increase injectivity at moderate pressures, Discussion of individual projects includes information on their early history, source and treatment of injection fluids, oil production-decline curves, and the results of water injection on oil production.

Jan 1, 1964

The iron ore deposits of the Port Hedland district of North Western Australia are associated with band'ed sedimentary iron formations that form part of the local succession of folded and faulted Archaean volcanic and sedimentary rocks. The iron formations are regarded as the protore beds or sources of the iron which became concentrated by supergene processes to form commercial grade iron ore deposits.Iron oxide deposits occurring in situ within the protore beds are considered to be of residual-replacement origin, due to supergene leaching of gangue minerals and' deposition of secondary iron oxides in their place, Two types of deposit have been recognized. Lode deposits are deep lenses of massive hematite located adjacent to major faults. These deposits are thought to be very old and to have originated by supergene processes during the long period of erosion represented by the major unconformity between the Archaean rocks and the overlying Proterozoic beds. The other type, known as crust ore deposits, are shallow cappings of hematite and goethite on hills formed by the outcrops of steeply dipping protore beds. These deposits could have originated as far back as the early Mesozoic and it is possible that the ore-forming process is continuing at a slow rate at the present day.Deposits formed by erosion and re-deposition of material derived from pre-existing residual-type deposits are known as derived deposits. These include conglomerates and scree accumulations of various types and ages and pisolitic deposits formed by supergene leaching of transported detritus. Derived deposits range in age from early Proterozoic to Recent. The presence of pebble accumulatio,ns of lode-type hematite in the Proterozoic basal conglomerate provides good evidence that lode hematite deposits existed in pre-Proterozoic times.INTRODUCTIONThe existence of iron ore deposits in the Port Hedland district of Western Australia has been known since the beginning of the century, but little attention was paid to them untIl the 1930's, when the Commonwealth Aerial, Geological and Geophysical Survey of Northern Australia carried out investigations of most of the then known mining fields of the Northwest Division. The only iron...

Jan 1, 1964

By Robert D. Saltsman

The inadequacy of our knowledge of the coal combustion process has long been recognized. This was expressed very well by Spicer and Finney (1). "The control of combustion processes in industry and the design of the equipment necessary for efficient burning to take place have always been very much branches of an industrial art rather than of an exact science. This has been especially true of the utilization of coal, a substance so hetrogeneous and complex in character that all too little is known about its chemical and physical composition.' During the past several years one branch of coal utilization, that of high temperature carbonization; has made significant advances from being an art into being an exact science. This has been accomplished by the development of petrographic techniques for identifying, measuring, and determining the thermal properties of the organic materials which affect the carbonization of coal and the correlation of this information with a pre-existing standard of coke quality, the stability index.

Jan 1, 1964

By Frank G. Schwartz

VARIABLES OF composition and environment affecting storage stability of gasoline-type fuels were studied, utilizing radioactive tracers and other analytical techniques. Changes in gasoline composition brought about by aging were determined and correlated with gum formation. The amounts of reaction of selected gasoline components, measured by radioactive tracers, were determined in a gasoline-type blend and in a mixture of 17 selected pure gasoline components. The data show that sulfur compounds, nitrogen compounds, polycyclics, and olefins enter into gum-forming reactions. Certain sulfur and nitrogen compounds were found to be most reactive in the gum-forming process. Results of this study indicate that the aromatic constituents of gasolines may contribute substantially and directly to gum formation. A mixture of tetralin and indan-type compounds is reactive, and this mixture appears to be the main aromatic portion entering into gum formation. A secondary but significant amount of naphthalenes also appears to have reacted in the gum-forming process. Analyses of the sulfm compounds in a fresh and an aged fuel indicated that elemental sulfur, hydrogen sulfide, thiols, sulfides, and disulfides were depleted during aging, but thiophenes and residual sulfur compounds were not depleted by fuel deterioration.

Jan 1, 1964

The principle activities of the Explosives Research Laboratory from July 1, 1961 to June 30, 1962, are described briefly in part 1. Part 2 gives short abstracts of publications that appeared during fiscal year 1962; in general, the research reported in these publications antedates the report period. Part 3 gives the results of an investigation which, although too limited to warrant separate publication, merits presentation in some detail because of current interest in ammonium nitrate-fuel oil compositions.

Jan 1, 1964

By Forrest T. Moyer

The National Safety Competition was inaugurated in 1925 by the Bureau o1 Mines, U.S. Department of the Interior, in cooperation With the Explosives Engineer. In the first nationwide contest, 210 mines and quarries were enrolled. In 1962, the thirty-eighth anniversary of the competition, 910 mines and quarries were enrolled. These participating plants were worked a total of 133,292,989 man-hours. Of the enrolled plants, 415 achieved injury-free operations tar the year, the largest number of perfect safety records in the history of the contest. In 1961 and 1962, the National Safety Competition was conducted and sponsored by the Bureau of Mines. In January 1963, the American Mining Congress became a cosponsor and participated with the Bureau in the award activities related to the 1962 contest. The basic purpose of the competition is to stimulate employees to work safely and too give impetus to the building of better accident-prevention programs. A well-designed and efficient safety program helps a company economically by cutting costs, preventing damage to equipment and materials, and reducing nonproductive delays. An effective safety program benefits the employee more directly because his injuries cause personal suffering, lost time, and lower living standards for his family. Since both have much to gain, management and workers should cooperate closely to eliminate disabling work injuries. The greater contest participation and the larger number of perfect safety records indicate increasing safety consciousness on the part of management and employees.

Jan 1, 1964

By Bernadette C. Michalski

THE RAPID GROWTH of the small Albanian mineral industry in the 1950's began to taper off by 1961 and slackened sharply in 1963. The abandonment of Soviet and East European technical assistance programs in mid-1961 greatly affected Albania's mineral development, since four-fifths of all technical aid personnel were engaged in mineral activities. Chinese assistance apparently has not been able to fill the void. Overall mineral production increases during 1961-63 averaged 1 percent per year in value, as compared with 3 percent in 1959 and 5 percent in 1960. Although by world standards Albanian mineral output, except for chromite, is insignificant, it is vital to the country's domestic economy. The mineral industry generated about 14 percent of the gross industrial product in 1962 and employed a notable share of the industrial labor force. In recent years, mineral products have provided about three-fifths of the country's exports by value. Chromite and iron-nickel ores together constituted from one-fourth to one-third of the total export value. In 1963, total trade turnover increased 12 percent over 1962.

Jan 1, 1964

By Lauren W. Choate

Wollastonite, a calcium metasilicate, derives its name from the man who discovered the mineral, Doctor William H. Wollaston, an English scientist. OCCURENCE Occurences of the mineral have been noted in Finland, Switzerland, Russia, Japan, Mexico and in the United States in Texas, California, Arizona, and New York. The only commercial deposit now being exploited is at Willsboro, New York. It is mined and processed by the Cabot Corporation whose home offices are in Boston, Massachusetts.

Jan 1, 1964

A semi-automatic device has been constructed that can be used to check the solution strength of cyanide solutions. It consists of a wheel on which a gold-foil-bearing glass slide is mounted. The wheel moves the gold foil through the solution under test and intercepts a light beam. As the gold foil is attacked by the cyanide solution its light absorption diminishes. The successive in-crease in transmitted light intensity is recorded and gives a measure of the gold dissolution rate. Curves have been obtained to show the effect of cyanide concentration and oxygen content on dissolution rates. Details are presented of the construction of the unit, and some practical operating procedures are outlined. 0 NE of the important, although often neglected, factors in the extraction of gold by cyanidation is the actual dissolving strength of the cyanide solution. This depends in a

Jan 1, 1964