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By W. S. Stahmann, F. W. Bowdish

Previously published experimental data showing that both collectable and non-collectable sulfide films may be formed on chrysocolla were analysed, and chemical mechanisms were proposed for the formation of the films. A special technique was developed by which the quantity of sulfur adsorbed was determined for samples sulfidized under different conditions of pH and soluble sulfide concentration. The data on sulfur adsorption were used together with the expression for the equilibrium constant for the proposed reaction to indicate the validity of the chemical mechanism theory. A recent paper 1 about contact angle studies on chrysocolla reported the effects of pH value and sodium sulfide concentration during sulfidization upon the character of the surfaces produced. In each experiment the surface of a specimen of chrysocolla was prepared by grinding it with fine abrasive and washing it in tap water. The specimen was then placed in the sulfidizing solution for 10 min, rinsed in tap water, treated for 15 min in a solution containing 30 mg of potassium amyl xanthate per liter, rinsed in distilled water, and tested for air adhesion in a contact angle apparatus. The results, when plotted as in Fig. 1, showed an island representing conditions giving air adherent or collectable surfaces surrounded by conditions giving non-collectable surfaces. Particular interest may be attached to the region of non-collectability to the right of and above the island in Fig. 1, and to the boundry curve separating these two regions. It is apparent that at any pH from 4.0 to 6.0, where a collectable surface may be produced, a sufficient increase in the sulfide concentration results in a non-collectable surface. Thus it appears that too much soluble sulfide has a depressing effect upon the mineral, just as it has in sulfide flotation. This paper presents some speculations regarding the chemical mechanisms by which the collectable and non-collectable sulfide films may be formed and reports on a physical-chemical study intended to support these speculations. THEORETICAL CONSIDERATIONS The experimental results presented in the previous paper were analysed in several ways in an attempt to understand better the chemical mechanisms involved. For several points on the boundary to the right of the region of contact in Fig. 1, molar concentrations of H+, OH-, HS-, and S= ions, as well as various ion concentration products, were calculated. Following the reasoning of Wark and Cox, 2,3 no single kind of ions may be credited with causing depression of the surface because none of them have a constant con-

Jan 1, 1968

By Rizzi Homestake Mining Co.

Geophysical methods of discovering new mineral deposits have long been routine with both the petroleum and mining industries. Experience has shown that most subsurface structures and mineral deposits can be located, provided that detectable differences in physical properties exist. The main properties exhibited by the more common rocks and formations are: density, magnetism, electricity, electrical conductivity, and radioactivity. This entails five major geophysical methods: gravitational, magnetic, seismic, electrical, and radiation. Applications of radioactivity measurements in geophysical exploration are concerned with location of concentrations of radioactive rocks and materials, such as uranium. The search for uranium ores and minerals has been carried on for more than 50 years, ever since the first atomic breakdown from uranium to radium was discovered. However, the comprehensive search now being made throughout the world for radioactive materials is a direct result of the first atomic explosion and the subsequent development of new and more sensitive portable equipment to detect radiation.

Mar 1, 1956

By Stanley L. Arnot

The Mother Lode district in California is probably better known as the land of Bret Harte and Mark Twain than as a gold-producing district, although in this respect it holds an important place. The history of quartz mining on the Mother Lode dates back to the '50s, when, after the first fever of the gold rush, men began to look for something more permanent, if not more lucrative, than the placers. Since that time, the discoveries, shutdowns, and reopenings of the many mines, together with the varying fortunes of their numerous operators, constitute an interesting chapter in California history, but one too long to include in a description of mining methods. The district is well situated, so far as physical conditions are concerned. The Mother Lode extends along the western slope of the Sierra Nevada Mountains, about half way between the crest and the Sacramento and San Joaquin Valleys, the country traversed consisting of low rolling hills—typical foot-hills. The elevation varies from 1000 to 1800 ft. and the climate is most desirable. There is an abundance of water, timber is easily obtained from the higher foot-hills a few miles east, and cheap hydro-electric power is generated practically on the Lode. These natural conditions are conducive to low costs in mining and have been the deciding factor in allowing profitable exploitation of the comparatively low-grade orebodies. Transportation facilities are not bad. Five branch railroads, from the main trunk lines in the valley, tap the district at intervals of from 10 to 30 miles, and the roads connecting these are fairly good for trucking purposes. Labor is made up of several nationalities, the principal ones being American, Spanish, Jugo-Slav, Italian, and Mexican. There were few Mexicans on the Lode prior to 1919, but the shortage of labor, experienced generally by the mining camps of the country in the years following the war, made necessary the hiring of some. The percentage of Mexican labor rapidly increased in 1920 and for a year or so thereafter, but it has now diminished until at most of the mines only a few Mexicans are working. Of the different nationalities, Americans are the most efficient and Mexicans the least.

Jan 1, 1925

By Samuel L. Hoyt

This paper gives a brief description of an investigation made several years ago on the diffusion of zinc into copper. The material for that study was furnished in the form of thin copper strips coated with zinc. The result was required rather quickly and at not too great an expense, and especially information was desired as to the rate at which zinc would diffuse from the zinc coating into the copper and the temperature at which the operation should be carried out. A study of the requirements of this problem indicated that the solution might be secured by means of six determinations. This is the smallest number that will give the information desired and, at the same time, furnish checks on the accuracy of the determinations which justify an abbreviated experimental program. This does not count a preliminary test which was designed to give some idea of the correct temperature to use. The minimum number of temperatures that can be used is two. Knowing the rates of diffusion of zinc into copper at two properly chosen temperatures, it is possible to calculate the rate for any other temperature, and also to check the accuracy of the determination by means of the heat of diffusion, which is calculated from the effect of temperature on the rate of diffusion. The minimum number of determinations at any one temperature is three. The amount of diffusion which occurs at a fixed temperature is definitely related to the time of diffusion, so that by determining the amount of diffusion for three different time intervals, this relationship may be established and possibly a check on the accuracy may be secured. This accounts for the six determinations or experiments, and suggests the logical plan of the work. The check used here is not generally applicable to diffusion phenomena, but it seems to hold closely enough for the limited amount of diffusion in this investigation to justify its use. The samples used were 5 to 6 mils thick and about 1 in. square. They were placed between iron blocks and set in the hot zone of a nichrome furnace which had been brought to the desired temperature Time was taken from the moment the samples reached the furnace

Jan 1, 1929

By Samuel L. Hoyt

This paper gives a brief description of an investigation made several years ago on the diffusion of zinc into copper. The material for that study was furnished in the form of thin copper strips coated with zinc. The result was required rather quickly and at not too great an expense, and especially information was desired as to the rate at which zinc would diffuse from the zinc coating into the copper and the temperature at which the operation should be carried out. A study of the requirements of this problem indicated that the solution might be secured by means of six determinations. This is the smallest number that will give the information desired and, at the same time, furnish checks on the accuracy of the determinations which justify an abbreviated experimental program. This does not count a preliminary test which was designed to give some idea of the correct temperature to use. The minimum number of temperatures that can be used is two. Knowing the rates of diffusion of zinc into copper at two properly chosen temperatures, it is possible to calculate the rate for any other temperature, and also to check the accuracy of the determination by means of the heat of diffusion, which is calculated from the effect of temperature on the rate of diffusion. The minimum number of determinations at any one temperature is three. The amount of diffusion which occurs at a fixed temperature is definitely related to the time of diffusion, so that by determining the amount of diffusion for three different time intervals, this relationship may be established and possibly a check on the accuracy may be secured. This accounts for the six determinations or experiments, and suggests the logical plan of the work. The check used here is not generally applicable to diffusion phenomena, but it seems to hold closely enough for the limited amount of diffusion in this investigation to justify its use. The samples used were 5 to 6 mils thick and about 1 in. square. They were placed between iron blocks and set in the hot zone of a nichrome furnace which had been brought to the desired temperature Time was taken from the moment the samples reached the furnace

Jan 1, 1929

Jan 1, 1916

By Lawrence A. Garfield

From the bottom of a shallow fissure the near-naked man-animal hacked out a hand-sized chunk of the red rock-like material which, when beaten between other rocks, could be drawn out to the thinness of a flint edge. Unlike flint, however, it did not shatter when, as the point for a spear or arrow, it went wide of its mark and fell amongst the rocks or tree branches. For this reason and others, the red rock- like material was specially sought and much time was spent in trying to break it from the real-rock in which it grew. Only infrequently was a chunk broken free and in this area many hours had been spent to win but a few fragments. What luck then, to remove so large a piece where before nothing but real-rock dust formed whenever the stone hammer hit. Why did this happen? Did yesterday's food-fire, burning on top the red rock, loosen its hold on the real-rock and cause it to break free when struck with the stone hammer? It is not a matter of recorded history that the first heat assisted extraction of native copper from country rock occurred under the circumstances or in the manner related but it is known that crude mining operations using these techniques were conducted by primitive man. In this way the first mineral production may have been achieved and the original example of rapid excavation unknowingly given to the world. Rapid excavation is not a method of removing rock or ore from an insitu condition nor does the term refer to a type of equipment which is specifically employed in mining and underground construction. It is, rather, the nomenclature currently popular in industry-primarily in underground construction- relating to a comparative rate of performance.

Jan 1, 1971

By Stanley W. Ivosevic

The commercial success of this low-grade property by Houston Oil and Minerals Corp. (succeeded in interest by Houston International Minerals, Inc.) resulted from credibility of analytical data furnished by the property vendor upon initial examination and from other favorable geologic criteria in evidence; from negotiation of lease terms not detrimental to project economics; from entrepreneurial exploration management; from an encouraging attitude by the US Forest Service; and from the favorable mining and metallurgical characteristics of the ore body. The potential of the property, but not its location, was brought to the attention of the project manager (the author) by the vendor some time before accepting employment with HO&M. In December, 1977, the vendor granted an examination to the project manager, by then an employee; and a lease to the 15 mining claims embracing the property was executed in April, 1978. (See Fig. 1.) Field work and extensive claim staking in this virgin district commenced in May, with drilling beginning in August. At the point that an apparent discovery was recognized in October, only $98,000-including property payments-had been expended on the project. By April, 1979, the deposit was drilled out on 60-m (200-ft) centers and a preliminary re- serve estimate, discounted cash-flow analysis, and recommendations for mine development and additional exploration submitted to management-all at a cost well below budget. The property was recommended for acquisition after matching favorable geologic criteria developed by the project manager. Favorable lithology, structure, and geochemical zonation converged on a subdued low-temperature hydrothermal alteration zone subtly expressed on a pediment surrounding the heart of the property, from which approx [ ]

Jan 1, 1985

By H. A. Wentworth

THE Huff electrostatic plant of the United States Smelting Company operated in conjunction with its wet concentrator at Midvale, Utah, was the second plant of substantial size installed using the Huff process, and the first plant to be put in operation on the so-called Western complex ores. In spite of the machinery being of early design and consequently embracing many of the mechanical weaknesses incident to a pioneer plant the mill has operated steadily and uniformly since the summer of 1909, about five years now, without any material change other than some re-arrangement of the machinery for better handling of the sizes. The ore, at present coming almost entirely. from the company's mines in Bingham, is of practically the same composition as that upon which the plant was first put in operation. The crude ore, consisting of the sulphides of copper, lead, zinc, and iron, and containing small amounts of gold and silver, is brought by train and delivered to the hoppers of the wet concentrator, where by jig and table treatment, there are produced a shipping lead concentrate, a tailing and a middling product, the latter being conveyed in push cars to the adjoining electrostatic mill. The crude ore delivered to the wet concentrator contains from 6 to 9.5 per cent. zinc. At times the plant is used also for the treatment of custom ores from the Bingham district and elsewhere, and at such times the results of the plant vary according to the material in use, but as by far the larger portion of the product is that from the company's own mines, the results given below are fairly indicative of the general work obtained. The accompanying diagram illustrates graphically the flow of the ore through the electrostatic mill. The middling coming from the wet mill containing from 15 to 18 per cent. moisture is hoisted while on the cars by an elevator, and delivered from the top of the elevator to a hopper over the drier. The drier first installed was of too low capacity to take care of the moisture present in the tonnage to which the mill was later

Jan 8, 1914

By D. Hugh Trollope, L. A. Fekete

L.A. Fekete (Project Engineer, Johnson B & Assoc. Engineers, Houston.) - The author tries to classify rock slopes in: a) homogeneous monolith, b) random, c) block-jointed systems. This may be practical at a specific mine, but it does not describe the mechanical behavior of the slopes in general. The difficulty with the problems of earth mechanics is the same, as with other structural problems: To

Jan 1, 1963

By U. Runolinna, R. T. Hukki

Preliminary separation of precious metals by flotation can offer a simplification of the conventional method of treatment of anode slimes. Laboratory flotation experiments show that rich gold and silver concentrate can be obtained with excellent recoveries.

Jan 11, 1950

By George A. Johnson, Leon H. Banks

The Missouri-Kansas Zinc Corpn., operating in the Waco district, 15 miles northwest of .Joplin, Mo., owns large tailing piles made during milling operations of the years 1918-28 by the Butte-Kansas, Acme, and Barnsdall mining companies, whose holdings have been purchased and consolidated under the ownership of the Missouri-Kansas Zinc Corpn. These tailings had been considered too low in value to be worth retreating by the ordinary methods. C. Erb Wuensch, consulting engineer of the Missouri-Kansas Zinc Corpn., noted the difference in the type of tailing from upper-level and lower-level ore. The latter contained hard lime chats. He also found that mill losses had been due to particles of blende on the corners or sides of the chats and to the existence of soft, porous, cellular, lime chats containing varying amounts of blende. He conceived the idea that a quick grind in rolls or hall rnills might change the type of the rnaterial so that jigging could rnake a clean tailing for discard and a partly concentrated product sufficient in blende content to justify the expense of fine grinding in hall mills to free the mineral entirely. A laboratory was equipped with the necessary machines and the writers were assigned the problem of developing a method of retreating the tailings. Laboratory Testing From preliminary drill sampling of each pile was obtained the blende content, the soluble sulfate content, and the general characteristics of the material to he treated. The tailings were a mixture of lime and flint with some shale. Visual examination showed most of the blende to be in the dolomite and very little in the flint, although there were some flint particles with blende on the cleavages. The blende was found as particles on the corners or cleavage faces in one type of chat and in another disseminated in a soft, porous, cellular lime. Because of the porosity of the latter type of chat, the apparent specific gravity, under hindered-settling conditions, is less than that of a solid piece of lime or flint. That it,

Jan 1, 1930

By Shiou-Chuan Sun, R. F. Wesner, J. D. Morgan

A new apparatus termed a "distribution analyzer" is introduced to ascertain the optimum conditions of electrostatic separation of minerals. It was found that with similar surface condition, testing environment and a constant feed rate of not higher than one layer of particles fed on the grounded roll of the separator, the behavior of each component mineral in a synthetic mixture or ore is roughly similar to that of the same mineral when tested alone.

Jan 3, 1950

By Frank Firmstone

In the Kaernthner Zeitschrift, No. 2, 1881, p. 53, et seq., Prof. Ledebur details some experiments on the power of various silicates of lime and alumina, magnesia and alumina, and lime, magnesia and alumina, to remove sulphur from pig-iron, from which it appears (as has long been recognized in practice) that the more basic the silicate the greater the quantity of sulphur it will take up; but also that for the same grade of silicate, this quantity is greatest for the lime-alumina silicate and least for the magnesia-alumina silicate, the lime-magnesia-alumina silicate occupying an intermediate position, and he concluded therefrom (p. 59) that, for the production of pig-iron low in sulphur, pure limestones are to be preferred to those containing magnesia. Much the same opinion has been published elsewhere on high authority, and lately (not to multiply references) by Sir Lowthian

Jan 1, 1895

ALTHOUGH everybody is familiar with coal, few persons have an exact idea of, the great impor-tance of this precious fuel. Coal is the black bread of industry. Without it, industrial activity is much restrained; and so the great industrial countries of Europe and the United States of America are the great producers of coal. The 1913 production of coal in Belgium was 22,842,-000 tons, valued at 418,700,000 fr., nearly a half billion. In 1919, it was 18,483,000 tons, about 81 per cent. of the production before the war; in 1920, it had reached 22,414,000 tons, approximately the production before the war. To show the importance of coal production of Belgium, let us say that the coal industry employed 168,000 workers in the year of 1920, the metallurgical industry only 129,000 and the textile industry 103,000. The coal industry, then, employs the greatest number of workers. The value of the coal production in 1919 is estimated at 1,121,000,000 fr. On the basis of the production before the war, the value of the production of iron in 1919 would have been 701,000,000, of finished steel 1,086,000,000, and of zinc 415,000,000; therefore, in 1919 the value of the coal industry was greater than that of the metallurgical production.

Jan 8, 1922

By Fred C. Bond

SIZE of grinding media is one of the principal factors affecting efficiency and capacity of tumbling-type grinding mills. It is best determined for any particular installation by lengthy plant tests with carefully kept records. However, a method of calculating the proper sizes, based on correct theoretical principles and tested by experience, can be very helpful, both for new installations and for guiding existing operations. As a general principle, the proper size of the make-up grinding balls added to an operating mill is the size that will just break the largest feed particles. If the balls are too large the number of breaking contacts will be reduced and grinding capacity will suffer. Moreover, the amount of extreme fines produced by each contact will be increased, and size distribution of the ground product may be adversely affected.

Jan 5, 1958

By Strathmore R. B. Cooke, Robert E. Brandt

EARLIER work1,2 has shown that the strength developed by fired magnetite pellets containing silica or silicates is due to three separate effects. Two of these are associated with the formation of slag in the interior of each pellet at temperatures above 1000°C, where the atmosphere is substantially though temporarily neutral. The third is independent of the silica content and is responsible for the development of a hard shell around the pellet during the initial stages of firing, a condition which permits the pellet to assume the increasing load of the overlying burden and prevents extrusion of the slagged and semi-liquid interior. Pellets made from hematite concentrates do not show these effects unless specific additives are incorporated, and it is these differences in behavior which in large part account for the difficulty in producing satisfactory pellets from such concentrates. Elsewhere it has been stated that "the most important factor responsible for the development of strength in fired magnetite pellets containing no additive is the oxidation of magnetite to hematite and the subsequent recrystallization and grain growth of this constituent."1 The object of the investigation reported in the present paper was to study in detail the mechanism described above and to evaluate its contribution to the strength of the fired pellet compared with other possible mechanisms, excluding slag bonding. This was effected by placing together polished faces of two cubes prepared from specific minerals and then heating them under constant pressure at different temperatures both in air and in nitrogen.

Jan 4, 1954

By Richard Franchot

IN the inevitable conquest of the blast furnace by metallurgical science in the solution of the problem of how to make more and better iron or to burn less coke, or both, it is highly desirable first to find out why the efficiency of the furnace generally is no better than it is. The immediate need would seem to be a theory to account for the existing facts. Explanation for the quantitative results obtained in current practice has been strangely lacking. One reason for this may be found perhaps in the custom of think-ing of efficiency in terms of coke consumption. Before efficiency can be explained there should be a fairly exact knowledge of what it is. A statement of the pounds of coke used per ton of iron made may have value in indicating comparative results in smelting similar ores with similar cokes, but it tells very little of the efficiency of the operation. When the materials are different, one practice burning 1800 lb. may be less efficient than another using 2000 lb. A better measure is the pig and slag per unit of coke. What is needed is a specific description of efficiency as a' definite quantity having an exact meaning. Such description is afforded by expressing efficiencies in terms of the respective proportions of the fuel energy absorbed in and chargeable to the various actions known to be -taking place in the furnace. Concretely, the energy value of a pound of coke having 85 per cent carbon blown with air heated to 1200° F. is about 7650 lb.-cal. (13,770 B.t.u.). And the work done in smelting a pound of average iron from hematite, comprising reduction and melting with production of a half pound of free running slag from an equal weight of limestone,

Jan 9, 1926

By F. W. Schremp, J. W. Chittum, T. S. Arczynski

This paper describes a laboratory study of causes of external casing corrosion and the test work that led to the use of oxygen scavengers to prevent this attack. External casing failures are classified as water-line, casing-casing, collar and body failures. A corrosion mechanism based on principles of differential oxygen availability is developed that is consistent with facts known about each kind of failure. The field use of oxygen scavengers is depicted as a direct result of the laboratory study. A part of the paper is devoted to reporting on the field use of hydra-zine to control external casing corrosion. Results of field measurements made over a period of several years are presented as evidence of the efectiveness of the hydrazine treatment. The first conclusion reached is that the use of hydrazine materially reduces the cathodic protection requirements for treated wells. This result is interpreted to mean that a reduction is taking place in the amount of corrosion on the casing. Results indicate also that hydrazine shows its greatest usefulness within the first 12 to 18 months after a well is completed when pitting corrosion is likely to be most active. INTRODUCTION According to surveys sponsored by the National Association of Corrosion Engineers,' the cost of repairing casing leaks caused by external corrosion may exceed $4 million per year. In addition, well damage and lost production resulting from casing leaks probably costs the petroleum industry an additional $5 to $6 million per year. Concern about the cost of external casing corrosion led to an extensive laboratory study of factors causing this external corrosion and to the development of a new approach to its prevention. This paper presents a discussion of various causes of external casing corrosion, details of laboratory studies and the results of the field use of an oxygen scavenger in well cementing fluids to prevent the external corrosion of oil-string casing. Measurements on test wells over a period of several years show that cathodic-protection current requirements are greatly reduced when hydrazine is used in cementing mud. Reduction of current requirements can be interpreted to mean that removal of oxygen by hydrazine has greatly suppressed corrosion cells on the external surface of the casing and thereby, has reduced corrosion. To date, hydrazine has been used by the Standard Oil Co. of California in more than 200 well completions. KINDS OF CASING FAILURES A survey of a large number of casing leaks disclosed four types of external casing failures — water-line, casing-casing, collar and body failures. These types are identified largely by their location on the casing. Water-line failures are found just below the surface of water or mud in the casing annulus. Casing-casing failures occur on the oil string just below the shoe of the surface string. Collar failures are found in the threaded ends of casing joints where they are screwed into casing collars. Body failures may occur at any point on the body of a casing joint. Ex- amples of each kind of failure have some of the general characteristics that are shown in Fig. 1. Water-line failures usually result in the circumferential severance of an oil-string casing. The corrosive action causing a water-line failure usually is sharply defined and is limited to a short length of the casing. Casing-casing failures usually are accompanied by pitting corrosion distributed around the oil-string casing for distances up to 100-ft below the shoe of the surface string. Casing-casing failures may also sever the casing. Collar failures seem to start on the first thread at the bottom of recesses between collar and casing joint. Corrosion proceeds across the threads by what appears to be a normal pitting mechanism. Both casing and collar are severely attacked. Body failures are the result of highly localized pitting at any point on a casing wall. Besides the pit that perforates a casing, a large number of other pits usually are found along one side of the casing joint. The pits occasionally are filled with corrosion products consisting largely of oxides and sulfides.' Frequently, the mill scale is largely intact on the rest of the casing. Examination of a casing failure does not always reveal the cause of the failure. Frequently, the necessary details are destroyed when the failure occurs. For example, formation water flowing through a perforation at high velocity may enlarge the hole and destroy any remaining evidence of the cause of the failure. One way to obtain undistorted information about a failure is to study the nature of other pits on the casing in the vicinity of the failure. A study of such pits frequently suggests that they are characteristic of an attack resulting from the differential availability of molecular oxygen.

By G. D. Monk, W. C. Krumbein

THE relation between permeability and the size parameters of unconsolidated sand is approached by considering sands as logarithmic frequency distributions having the basic parameters mean size and standard deviation. Sieve separates were mixed in accordance with the normal logarithmic probability law, so that the mean and standard deviation could be varied at will. Experiments were conducted in which one parameter was kept fixed and the other varied; in this manner the dependence of permeability on the individual parameters was evaluated. It was found that permeability can be expressed as the product of a power function of the mean size and an exponential function of the standard deviation.

Jan 1, 1942