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By John R. Freeman

This paper relates entirely to the casting of brass under fluid pressure in steel dies. Die castings of metals and alloys of low melting point have been available for many years but the development of brass die castings has been relatively recent, occurring within the past five years. The successful developnlent of brass die castings has resulted from the availability of alloy steels that would give satisfactory life as dies and the development of suitablc die-casting machines. The melting point of copper is 1084" C. (1983" F.) and of a high brass about 900" C. (1652" F.), as compared to 327.5" C. (621.5" F.) for lead, 419.4' C. (786.7" F.) for zinc and 658.7" C. (1217.7" F.) for aluminum, temperatures that are indicative of the casting temperatures required for the various types of alloys, of which the melting points are somewhat lower than those of the pure metals. Type of Die-casting Machine In the well-known plunger and gooseneck types of die-casting machines used for casting the alloys of relatively lower melting point, much of the working mechanism is immersed in the molten alloy. For alloys having the relatively high melting point of brass, this obviously is impossible. Machines with a separate melting chamber are essential. Two rather distinct types are in extensive use at the present time, the Pack and Polak machines, the former designed by Charles Pack and developed at the American Brass Co., the latter developed by Joseph Polak, of Prague, Czeclioslovakia. The principles of operation of these machines have been described in articles by Pack1,2,3 and by Sieg.4

Jan 1, 1935

By John R. Freeman

This paper relates entirely to the casting of brass under fluid pressure in steel dies. Die castings of metals and alloys of low melting point have been available for many years but the development of brass die castings has been relatively recent, occurring within the past five years. The successful developnlent of brass die castings has resulted from the availability of alloy steels that would give satisfactory life as dies and the development of suitablc die-casting machines. The melting point of copper is 1084" C. (1983" F.) and of a high brass about 900" C. (1652" F.), as compared to 327.5" C. (621.5" F.) for lead, 419.4' C. (786.7" F.) for zinc and 658.7" C. (1217.7" F.) for aluminum, temperatures that are indicative of the casting temperatures required for the various types of alloys, of which the melting points are somewhat lower than those of the pure metals. Type of Die-casting Machine In the well-known plunger and gooseneck types of die-casting machines used for casting the alloys of relatively lower melting point, much of the working mechanism is immersed in the molten alloy. For alloys having the relatively high melting point of brass, this obviously is impossible. Machines with a separate melting chamber are essential. Two rather distinct types are in extensive use at the present time, the Pack and Polak machines, the former designed by Charles Pack and developed at the American Brass Co., the latter developed by Joseph Polak, of Prague, Czeclioslovakia. The principles of operation of these machines have been described in articles by Pack1,2,3 and by Sieg.4

Jan 1, 1935

By Gerald C. Dohm

INTRODUCTION After a mining company has discovered a mineral deposit, the problem is then how to mine and process that deposit the best way. The principal problem facing managers or engineers who must decide on mine plant size, equipment selection, and long-range scheduling is how one can optimize a property not only in terms of efficiency but also as to project duration. Mine opti¬mization is dependent upon the interaction of con¬tributing parameters which leads to maximizing the net present value (NPV) Realistic mine planning is the key, to the analysis. The process is to be used when evaluating undeveloped properties or when a complete revamping of existing facilities is scheduled The proc¬ess is not intended for detailed mine design but rather for property evaluation and feasibility studies. The derivation of the various input parameters will only be discussed to the point where a meaningful correlation can be made with the overall analysis. The interrelationship of the parameters will be the central point because most company guidelines and financial analysts have their own standards when deriving the various inputs. Assume that the data is totally acceptable and pro¬vides at least the following categories of information and guidelines- (1) mineral and waste inventory; (2) geologic, hydrologic, and geotechnical criteria; (3) topographic layout including property boundaries; (4) metallurgical flowsheet, recovery and design criteria; (5) access, water, power, and environmental base-line study; and (6) financial constraints (minimum rate of return, payback period, etc).

Jan 1, 1979

By David B. Burrows, Francis R. Conley

INTRODUCTION A prerequisite to the evaluation and management of oil properties is accurate information derived from the analysis of core samples; but reliable data, such as porosity and permeability, can result only if all oil and water have been removed from the core samples analyzed. The most common method of core cleaning used to date has been Soxhlet extraction—a somewhat static technique, which depends upon the slow diffusion of hot solvent through the core sample. Soxhlet extraction performs satisfactorily only with highly permeable samples and at best requires long cleaning periods. The centrifuge method was developed in 1951 by Continental Oil Co. to overcome the inefficiencies inherent in the Soxhlet method. The new method is basically an operation in which hot solvents are caused to flow through the samples under the influence of centrifugal force. The centrifuge unit has proved so successful that samples which formerly required days for partial extraction can now be completely cleaned in approximately one hour. The original idea was conceived in 1950 by Elmer S. Messer, whose early experiments consisted of flowing solvent over sandstone samples suspended in a revolving basket and driven by a vertically mounted vacuum cleaner motor. Results were so outstanding that more permanent units were constructed. A modified model using this basic design was recently built by Core Laboratories, Inc., and is now used regularly in their operations. DESIGN Fig. 1 shows a photograph of the two extractors routinely used to clean small core plugs in the Production Research Div. of Continental Oil Co.'s Ponca City laboratories. For illustrative purposes, the basket from one of the units has been removed, and because both extrac- tors are of identical design only one is described in the following discussion. Each extractor unit consists of a centrifuge and a solvent still. The core basket of the centrifuge is made of mild cold rolled steel 7 1/2 in. in diameter and 1 1/8 in. deep. The basket holds 18 1-in. samples (cubical or cylindrical) and is attached directly to a cone fitted to the shaft of the motor. Both the outer rim and the hollow hub of the basket contain perforations for the passage of solvent and extract. The solvent is delivered to the perforations by means of a copper tube inserted into the hollow hub. The motor is a vertical tool post grinder motor; (115 v, 5.6 amp, 0-60 cycles, AC-DC, rated at 1/3 hp). It has a rated speed of 10,000 rpm under full load and 15,000 rpm with no load. Variation of speed is obtained by the use of a variable transformer. The solvent still was constructed from one end of a stainless steel oxygen bottle by inserting a heating element, sight glass, and piping as shown on the schematic diagram, Fig. 2. The heater used was a three-position, 1,000 w, 115-v, immersion type. Intermittent flow of solvent to the centrifuge is obtained by means of a siphon bottle inserted between the condenser and the centrifuge.

Jan 1, 1957

By Herty, C. H.

The effect of temperature on the physical properties of structural materials has been the subject of many investigations during the past decade. The literature on the effect of elevated temperatures. is voluminous, and during the last four years a great deal of experimental work has been carried out on the effect of low temperatures on the impact properties of steel. For many engineering purposes it is important to know the shock resistance of steels at low atmospheric temperatures, and with the ever-developing field of refrigeration and separation of materials at low temperatures, the normal limits of atmospheric temperature have been exceeded in practice. Iron and its alloys in the unnotched condition have a high impact strength at low temperatures, but in practice variations in type of notches result either from design or accidentally through scratches and surface or internal defects. A study of notched bar impact tests is, therefore, highly important to the engineer. A survey of the literature on low temperature impact testing indicates that chemical composition, heat treatment and method of testing have been the variables which have been considered in most previous work. In only a few instances has any mention of the steel- making method been mentioned and in these the comparison was between steel-making processes and not between steel-making methods on the same process. In view of the wide variations in impact properties at room temperature, in quench and strain ageing and in grain growth of steels of identical chemical composition, (by this is meant the usual five element analysis reported), it was felt

Jan 1, 1957

CONTENTS PAGE Rae, Colin C.-A Possible Origin of Oil. Discussed by S. Linker, Colin C. Rae... 2 Cottingham, Kenneth.-Subsurface Conditions on Portion of Arches Fork Anticline. Discussed by David B. Reger 6 Moyer, W. Irwin.-Time to Pay Out as a Basis for Valuation of Oil Properties. Discussed by H. J. Smith 9 Pogue, Joseph E.-Future Demands on Oil Industry of United States. Discussed by James O. Lewis 11 J. J. Walsh.-Coa-lmine Ventilation. Discussed by W. B. Daly, J. J. Walsh, R. R. Sayers, H. H. Stock, George S. Rice, James W. Paul, D. Harrington, T. D. Thomas 15 Longyear, Robert Davis.-Diamond-drill Sampling Methods. Discussed by Ira B. Joralemon, J. J. Rutledge, E. C. Harder 19 Joralemon, Ira B.-Sampling and Estimating Disseminated Copper Deposits. Discussed by J. Parke Channing, John E. Hodge, E.E. Hunner, B. B. Gottsberger, W. Y. Westervelt, W. O. Hotchkiss 20 Boericke, W. F.-Sampling and Estimating Zinc and Lead Orebodies in Mississippi Valley. Discussed by J. Parke Channing, Arthur Thacher 24 Daly, W. B. and Linforth, F. A.-Organization of Mine Sampling at Anaconda. Discussed by George A. Packard, W. B. Daly, B. B. Gottsberger 25 Norris, E. M. and Rahilly, H. J.-Mine Fires. Discussed by R. Dawson Hall, W. B. Daly, Frank Haas, D. Harrington, Robert E. Tally 26 Raymond, R. M.-Safety Practice for Hoisting Ropes. Discussed by B. F. Tillson, Graham Bright, Rudolph Kudlich, J. F. Howe, Robert Peele, H. G. Davis. 30 Howe, J. F.-Use of Wire Rope in Mining Operations. Discussed by Horace F. Lunt, J. F. Howe, B. F. Tillson 36 Tanner, W. N., and Jaccard, F. C.-Wire Rope and Safety in Hoisting at Butte Mines. Discussed by Horace F. Lunt, W. B. Daly, C. L. Colburn, William Kelly, Robert Peele, B. F. Tillson, Graham Bright, Charles E. Locke 38 Richardson, A. S.-Ventilation of Butte Mines of Anaconda Copper Mining Co. Discussed by D. Harrington, Chas. A. Mitke 42 Stuart, Charles E.-Storage-battery Locomotive as Applied to Mine Haulage. Discussed by Howard N. Eavenson, Charles E. Stuart, William Kelly, Arthur Thacher, W. H. Patton, Graham Bright 45 Woodward, C. D.-Electric Haulage Systems in Butte Mines. Discussed by William Kelly, Graham Bright, Howard N. Eavenson, C. E. Arnold, Gerard B. Rosenblatt, K. A. Pauly 47 Harrington, D.-Efficient Ventilation of Metal Mines. Discussed by R. E. Simpson 52 Otagawa, Masayuki.-Mining Methods at the Ashio Copper Mine. Discussed by Horace V. Winchell, D. W. Brunton 52 Stoek, H. H. and Clagett, Thomas H.-Coal Mining Methods. Discussed by P. D. Browning, G. L. Cox, Erskine Ramsay, Frank Haas, George S. Rice.

Jan 6, 1922

By H. W. Gillett

MAINTENANCE of membership by the technical so¬cieties and the activity of these societies in spite of the adverse business situation have been noteworthy. This forcibly brings home the fact that industry recognizes that sound technical guidance is well worth its cost. The numerous difficulties and losses due to defects of various kinds arising from gas-metal reactions are now generally recognized and interest in these problems is widespread. The forthcoming A. I. M. E. round-table discussion of gas-metal problems will do much to clarify the situation and will permit us to assay our present knowledge and to suggest the proper direction for profitable future research. "The Age Hardening of Metal" was the title of the annual I. M. D. lecture delivered by Dr. Paul D. Merica. A critical review of the known facts relating to age-hardening phenomena was first given, followed by the presentation of a theory correlating the detailed observations which have been made regarding the mechanism of the hardening.

Jan 1, 1933

By K. S. Seljesater

SINCE the development of dispersion-hardenable lead-antimony alloys1 in the laboratories of the Western Electric Co., Inc., studies have been made of the effect of various third constituents on these alloys.2 This paper covers a study of the effect of small amounts of arsenic. This element is important since it occurs as an impurity in many commercial antimonial leads and the results obtained are particularly interesting as indicating a class of addition agents which exert a stabilizing effect on dispersion-hardened alloys. EXPERIMENTAL In order to-study the effect ,of increasing amounts of arsenic, a series of alloys were made up containing 1 per cent. antimony, and arsenic varying from 0. to 0.10 per cent., the balance Doe Run lead (99.997 per FIG. 1..-CHANGE OF MICRO-BRINELL HARDNESS WITH TIME OF 1 PER CENT. LEAD-ANTIMONY ALLOY. cent. lead). The alloys were cast into bars 1 ½ in. wide by ¾ in. thick and cold-rolled to about 1/8 in. thickness. Three samples of each composition were annealed 1 hr. at 225° C. and quenched in water. One set was aged at room temperature, one at 50° C., and the third at 100° C., the

Jan 1, 1929

By F. C. Wagner, E. P. Klier, D. E. Nulk

The presence or absence of plastic strain at a cleavarage surface is a question of much importance, and upon its answer depends future possible theoretical work. To investigate this question back-reflectinn X ray patterns were obained on the cleavage facets of ferrite grains. The test set-up consisting of FeK colli- mated radiation, single grain material and stationary cassette and specimen will not lead to a diffraction pattern, in general, but is an ideal arrangement for the exami-nation of surface effects. A pattern taken on hydrogen purified

Jan 1, 1949

R. F. MCELVENNY.- Over 20 years ago I went back East on a little tour of copper companies to see how copper was handled and fabricated, and I met a Mr. Bassett who took me through the Waterbury branche of the American Brass Co. I have not seen this gentleman for 20 years, but I have a letter from him that I would like to read to you. 'The American Brass Co. Waterbury, Conn. May 19, 1930. To the-Salt Lake City Conference on Reverberatory Smelting Practice: Through the courtesy of Mr. Scott Turner, Director of the U. S. Bureau of Mines, Mr. G. L. Oldright has been temporarily released from his regular duties to act as your secretary. We have asked him and Mr. McElvenny to make the necessary preliminary arrangements and to present to you at the opening session the greetings of the officers and' directors of the Institute. I am very glad that it has been possible for you to come together under the auspices of the Institute and that the acceptance of our invitation has been so very unanimous. Such an acceptance of the invitation to this meeting indicates your interest in getting together for an exchange of technical data and ideas. We anticipate that this meeting will be of real service to the smelting industry through your open discussion and exchange of ideas, and we sincerely hope that you will form an organization which will arrange for future meetings of a similar nature. While it probably may not be desirable to. distribute the minutes of this conference except to the members who take part in it, we hope that later the Institute publications may be enriched by such matter as you think it desirable to have published; and also, that some of you may be able to offer technical papers for the Institute publications. I hope that you will find a permanent organization desirable and trust that it will be possible for you to form such an organization so that conferences may be regularly called. We hope that you can make use of the Institute organization and that we can be of real service to your industry. With best wishes for your success in this undertaking, I am Most cordially yours, W. H. Bassett, President.

Jan 1, 1930

Jan 1, 1967

By W. E. Stiles

A method is presented for predicting the performance of water flooding operations in depleted, or nearly depleted, petroleum reservoirs. The method makes use of permeability variations and the vertical distribution of productive capacity. From these two parameters can be calculated the produced water cut versus the oil recovery. Derivations of the mathematical analogy is shown and sample calculations and curves of prediction are presented. Comparison is made of the predicted and actual performance of a typical 5-spot in an Illinois water flood. INTRODUCTION The use of water as a flooding medium in both depleted and "flush" oil reservoirs is gaining greater recognition and acceptance. Many of the shallower fields, depleted by primary production, have been and are being subjected to water injection in order to obtain some part of the large volume of oil remaining after primary production. Some of the earlier water flood installation proved highly discouraging and the value of water flooding was often questioned. Many of these earlier floods were haphazardly selected and developed as little was known of the physical characteristics and contents of the producing formations. The prior evaluation of the flood performance was impossible. During the past decade the development of the required reservoir engineering tools-—core analysis, reservoir fluid analysis, electric logs, fluid flow formulae, etc.—has allowed the engineer to construct and apply the methods which are presently being used to evaluate the economic and mechanical susceptibility of a reservoir to flooding. This discussion will present a method for taking into account the effect of permeability variations in predicting the performance of water floods in depleted reservoirs. PERMEABILITY AND CAPACITY DISTRIBUTION It is generally agreed by most investigators that in a single phase system fluid will flow in a porous and permeable medium in proportion to the permeability of the medium. Producing formations are usually highly irregular in permeability, both vertically and horizontally. However, zones of higher or lower permeability are often found to exhibit lateral continuity. Thus, while structurally comparable stringers in adjacent wells may differ several fold in permeability values, they usually bear resemblance as being part of a general continuous higher or lower permeability section. It is generally agreed that where such stratification of permeability exists, injected water sweeps first the zones of higher permeability, and it is in these zones that "break-through" first occurs in the producing well. It is a basic assurnption of the presently described method that penetration of a water front follows the individual permeability variations as if such variations were continuous from input to producing well. This is admittedly not rigorously true, but can be justified as making possible a simplifying mathematical approach to an otherwise extremely complicated three dimensional flow problem. As a basis for study of the lateral flow of fluids in formations of irregular permeability, the irregularities may be conveniently represented by a permeability distribution curve and a capacity distribution curve. In obtaining these curves, the permeability values, regardless of their structural position in the formation, are rearranged in order of decreasing permeability. If these permeability values so arranged are plotted against the cumulative thickness, a permeability distribu- tion curve is obtained. This curve may then be likened to a "smoothed" permeability profile of the formation. In making comparison between different distribution curves it is convenient to state the permeabilities in terms of the ratio of the actual permeability values to the average permeability of the formation. These ratios termed "dimensionless permeabilities", are used in this paper rather than the permeabilities in terms of millidarcys. The capacity distribution curve is a lot of the cumulative capacity (starting with the highest permeabilities) versus the cumulative thickness. The capacity and thickness are given as fractions of the total capacity and thickness. Mathematically, the capacity distribution is the intergration of the permeability distribution curve. In practice it is convenient to first obtain the capacity distribution curve and derive from it a smoothed dimen-sionaless permeability curve. The method of obtaining the capacity distribution curve is illustrated in the successive column of Table 1, in which capacity and thickness are derived as fractions of their respective totals. If only a small number of permeability values are available, it is generally desirable to smooth the resultant curve. This has been done to give the capacity distribution curve shown in Figure 1. The differentiation of the capacity distribution curve to obtain the permeability distribution curve is shown in Table 2. Here, the capacity values are read from the smoothed curve at intervals of cumulative thickness, and the increments of capacity are divided by the increments of thickness to obtain the dimensionless permeability, K. Due to this stepwise procedure of calculation these premeability values must be plotted at the midpoints of the successive increments of thickness. The curve so obtained from these data is shown in Figure 1. The total area under the K' curve is equal to unity.

Jan 1, 1949

By W. E. Stiles

A method is presented for predicting the performance of water flooding operations in depleted, or nearly depleted, petroleum reservoirs. The method makes use of permeability variations and the vertical distribution of productive capacity. From these two parameters can be calculated the produced water cut versus the oil recovery. Derivations of the mathematical analogy is shown and sample calculations and curves of prediction are presented. Comparison is made of the predicted and actual performance of a typical 5-spot in an Illinois water flood. INTRODUCTION The use of water as a flooding medium in both depleted and "flush" oil reservoirs is gaining greater recognition and acceptance. Many of the shallower fields, depleted by primary production, have been and are being subjected to water injection in order to obtain some part of the large volume of oil remaining after primary production. Some of the earlier water flood installation proved highly discouraging and the value of water flooding was often questioned. Many of these earlier floods were haphazardly selected and developed as little was known of the physical characteristics and contents of the producing formations. The prior evaluation of the flood performance was impossible. During the past decade the development of the required reservoir engineering tools-—core analysis, reservoir fluid analysis, electric logs, fluid flow formulae, etc.—has allowed the engineer to construct and apply the methods which are presently being used to evaluate the economic and mechanical susceptibility of a reservoir to flooding. This discussion will present a method for taking into account the effect of permeability variations in predicting the performance of water floods in depleted reservoirs. PERMEABILITY AND CAPACITY DISTRIBUTION It is generally agreed by most investigators that in a single phase system fluid will flow in a porous and permeable medium in proportion to the permeability of the medium. Producing formations are usually highly irregular in permeability, both vertically and horizontally. However, zones of higher or lower permeability are often found to exhibit lateral continuity. Thus, while structurally comparable stringers in adjacent wells may differ several fold in permeability values, they usually bear resemblance as being part of a general continuous higher or lower permeability section. It is generally agreed that where such stratification of permeability exists, injected water sweeps first the zones of higher permeability, and it is in these zones that "break-through" first occurs in the producing well. It is a basic assurnption of the presently described method that penetration of a water front follows the individual permeability variations as if such variations were continuous from input to producing well. This is admittedly not rigorously true, but can be justified as making possible a simplifying mathematical approach to an otherwise extremely complicated three dimensional flow problem. As a basis for study of the lateral flow of fluids in formations of irregular permeability, the irregularities may be conveniently represented by a permeability distribution curve and a capacity distribution curve. In obtaining these curves, the permeability values, regardless of their structural position in the formation, are rearranged in order of decreasing permeability. If these permeability values so arranged are plotted against the cumulative thickness, a permeability distribu- tion curve is obtained. This curve may then be likened to a "smoothed" permeability profile of the formation. In making comparison between different distribution curves it is convenient to state the permeabilities in terms of the ratio of the actual permeability values to the average permeability of the formation. These ratios termed "dimensionless permeabilities", are used in this paper rather than the permeabilities in terms of millidarcys. The capacity distribution curve is a lot of the cumulative capacity (starting with the highest permeabilities) versus the cumulative thickness. The capacity and thickness are given as fractions of the total capacity and thickness. Mathematically, the capacity distribution is the intergration of the permeability distribution curve. In practice it is convenient to first obtain the capacity distribution curve and derive from it a smoothed dimen-sionaless permeability curve. The method of obtaining the capacity distribution curve is illustrated in the successive column of Table 1, in which capacity and thickness are derived as fractions of their respective totals. If only a small number of permeability values are available, it is generally desirable to smooth the resultant curve. This has been done to give the capacity distribution curve shown in Figure 1. The differentiation of the capacity distribution curve to obtain the permeability distribution curve is shown in Table 2. Here, the capacity values are read from the smoothed curve at intervals of cumulative thickness, and the increments of capacity are divided by the increments of thickness to obtain the dimensionless permeability, K. Due to this stepwise procedure of calculation these premeability values must be plotted at the midpoints of the successive increments of thickness. The curve so obtained from these data is shown in Figure 1. The total area under the K' curve is equal to unity.

Jan 1, 1949

Nominating Committee.-On the recommendation of the President, the Board of Directors, at their meeting on Apr. 25,1913, appointed the following Nominating, Committee to nominate officers and directors for next year: John Hays Hammond (Ex-President), Chairman. Robert H. Richards Chairman of Boston Local Section. Richard S. McCaffery, . . . . Chairman of Spokane Local Section. Chester F. Lee Chairman of Puget Sound Local Section. Frederick G. Cottrell, . . . . San Francisco, Cal. Charles W. Goodale Butte, Mont. James W. Maleolmson, . . . . Kansas City, Mo.

Jan 5, 1913

By Louis D. Huntoon

SHORTLY after publication of the article in the July, 1924, issue Of MINING AND METALLURGY, entitled "Canada as a Gold Producer," requests were received to determine the ownership of production. Advices have also been received that considerable discussion has taken place on the same questions both in Canada and Great Britain. The author is indebted to R. H. Coates, Dominion Statistician, and George C. Bateman, Secretary, Ontario Mining Association, for the following figures and takes this opportunity of expressing his appreciation. There have been no statistics compiled as to ownership of production. Statistics were compiled as of Dec. 31, 1921 relative to the distribution of stocks, bonds and "other securi¬ties" in industrials, agriculture excepted, throughout the Dominion, and "distribution of ownership of securities issued by mining companies incorporated and operating in Ontario" for the same year. Stock registration does not necessarily represent actual ownership' as large blocks may be endorsed and not transferred; neither does registration actually represent production. When the charts are studied individually and collectively one cannot help but be impressed with the fact .that in the mineral industry of Ontario and the Dominion at large, Canadian registration predominates, the United States registration is about half that of Canada, and Great Britain is about half that of the United States. When the nickel-copper industry is excepted the British registration falls to a very low percentage. Since Dec. 31, 1921, British capital has commenced to flow into mining enterprises in Ontario and it has been already rewarded by the discovery of valuable ore deposits.

Jan 1, 1925

By Rudolph G. Wuerker

THE Krupp-Renn Process,[1] has been successfully used to treat low-grade iron ores, laterites, titaniferous sands, and other minerals, and before World War I1 25 units were built by the Krupp-Grusonwerk, Magdeburg, Germany. J. J. Howard[2] has shown theoretical advantages of the pyro-metallurgical treatment over conventional approaches; and the process was described by R. Durrer[3].

Jan 1, 1951

By John Griffen

HYDRAULIC classification as explained by Rittinger and others was largely restricted to conditions wherein the free-falling velocities of the particles were conceived as governing the separations effected (see chapter 9). The laws governing classification under free-falling conditions have been summarized by Chapman and Mott as follows:

Jan 1, 1943

Discussion of the paper of Frederick Laist, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 79, July, 1913, pp. 1147 to 1162. J. C. DICK, Salt Lake City, Utah :-I would like to ask Mr. Laist why a 10 per cent. salt solution was used. MR. LAIST :-The reason for using salt in the solution is to get .the sulphur. The solution of dilute sulphuric acid has no solvent action on the sulphur even after roasting, and the addition of the salt is made primarily to dissolve the sulphur chlorides. MR. DICK:-I would like to ask also if you made any experiments as to grinding fine your calcines, rather than leaving the coarse material. MR. LAIST :-We have not made any experiments along those lines except in the laboratory, but the objections which we have to grinding are that the difficulties of roasting are very much greater when roasting finely ground material than when roasting coarse material, and the difficulties of leaching are somewhat increased; the percolating system is simpler and easier to manipulate, particularly when acid solutions are used, so that we prefer from our experience not to grind. STUART CROASDALE,* Denver, Colo. (communication to -the Secretary +) :-In order to meet the conditions involved in his ore-treatment problem, Mr. Laist has developed a very interesting and apparently successful metallurgical hybrid which he calls the oxychloridizing roast. The lower floors of the MacDougall furnaces are made to accomplish what used to be done on the " cooling floor" in the old days of salt roasting and " hypo " or brine leaching of silver ores.

Jan 11, 1913

By Paul E. Melancon, Vincent C. Kelley, Dale F. Kittel

Uranium of the Grants region occurs predominantly in continental sandstones of the upper part of the Jurassic Morrison Formation, but significant lesser deposits are found in limestone of the Jurassic Todilto Formation and in black shale of the Cretaceous Dakota Formation. The deposits are disseminations that form runs ranging from a few hundred tons to several million tons. The ore consists mainly of uraninite, uraniferous carbonaceous material, coffinite, and such secondary oxidized minerals at tyuyamunite, carnotite, and uranophane. In sandstone, the ore runs were locallized by mudstone, interstitial carbonaceous material, and primary sand channel trends. In limestone, ore deposition was related to folds and fracture zones. The great bulk of production has come from the Ambrosia Lake mines in the Grants district and the Jackpile and Paguate mines in the Laguna district. The ores, which generally have been 0.20 to 0.30 per cent U3O8, are treated at mills operated by Kerr-McGee Corporation, Homestake-Sapin Partners, and The Anaconda Company, all in the Grants district. In 14·years after discovery in 1950, the deposits had yielded concentrates valued in excess of $800,000,000. Since deposition of the Jurassic host rocks, a geologic history involving tilting, faulting, erosion, changing ground-water environments, and oxidation has considerably influenced the existence and character of the deposits. It is evident that their ongm is not simple. However, a degree of agreement appears probable for a pre-Dakota age for the original ore runs, and, at Ambrosia Lake, two principal stages of ore formation, separated by Laramide faulting, are recognized. All earlier ores have been modified by Quaternary oxidation, solution, and enrichment during which time much secondary tyuyamunite, metatyuyamunite, carnotite were formed.

Jan 1, 1968