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By Colin MacDonald

The choices of an uranium mill flowsheet are pri- marily determined by economic feasibility with plant location and regulatory bodies playing a lesser but still important role in this determination. The host ore bodies will determine the leach pro- cess to be used for basic uranium extraction. Im- mediately following this decision, the method of leaching has to be determined. These can be: - Atmospheric leaching - Pressure leaching - In-situ leaching - Heap leaching The three previously stated criteria lay important parts in this decision. In the case of atmospheric or pressure leach and once the soluabilized uranium has been liberated from the host gang material, liquid solids separation becomes the major criteria. Three process flowsheets are available; they being: -Countercurrent decantation - Countercurrent or co-current filtration - Resin in pulp Following liquid solids separation, concentration and precipitation become the next variable choice. They being: -Solvent extraction - Fixed bed ion exchange - Fluid bed ion exchange Lastly, washing and drying of the precipitated product to remove impurities can be carried out by either filtration or centrifugation. With the exclusion of milling circuits, grinding circuits, flotation circuits, and calcining processes, we have 240 variations of the flowsheet between leaching and a dry washed precipitate. Of this total, filtration in one form or another and in single or multiple applied forms has application in 144 streams. This paper intends to discuss four (4) facets of the total flowsheet in which filtration is applied, following grinding and prior to calcining. They are: - Leached pulp liquid solid separation - Tailings dewatering - Pregnant solution clarification - Yellow cake washing and dewatering

Jan 1, 1980

By G. Reinberg, C. D. Clarke

MOST underground mining operations are dependent on pumping installations to keep the mine unwatered. The reliability of such installations is obviously of paramount importance. The volume of water to be handled is often considerable, and the total head is relatively high. In these cases, both capital cost and operating expense of the pumping installations will become significant factors in overall mining costs. To insure reliability and to keep efficiencies, and hence operating cosl;s, within acceptable limits it goes without saying that mechanical maintenance of a mine pumping installation must receive scrupulous attention at all times. Large mine pumping installations today almost invariably use multistage centrifugal pumps, since positive-displacement units would not be economically competitive except under very unusual conditions of small volume combined with extremely high heads. Centrifugal pump maintenance, under ideal circumstances, would be confined to parts subject to normal running water, i.e., bearing surfaces, stuffing box packing, and shaft sleeves. Under adverse conditions, however, metal may be lost from the wetted surfaces of a pump by erosive or corrosive action of the pumped fluid, and maintenance costs can easily attain enormous proportions. The following definitions are those most generally used for the phenomena encountered. Erosion is a general term meaning mechanical removal of material from a surface. As applied to pumps, it may be the result of simple abrasion, such as that produced by suspended solid matter in the liquid being pumped. In common with other hy-

Jan 1, 1957

By A. W. Fahrenwald

THE absolute efficiency of crushing and grinding in a ball mill is not known. A number of investigators have made calculations to this end and have presented efficiency figures. Two factors have prompted further investigation of this subject: (1) the unbelievably low magnitude of the values offered, and (2) a desire to obtain, if possible, true relationships between the relative efficiencies of a ball mill operating under varying conditions. A useful forward step in the study of mill efficiency was made when Martin1 and Gross and Zimmerley2 proved the correctness of Rittinger's law, and incidentally the incorrectness of the so-called Kick law, and when Gross and Zimmerley3 determined and gave surface values for Tyler sieve-sized quartz. These data are probably accurate throughout the range of the sieve scale, but on -400 mesh (which is the finest sieve available), the surface data, as obtained by the hydrofluoric acid disso-lution method, are of doubtful reliability. Any inaccuracy existing in surface determinations of -400-mesh material, especially when comparing runs in which varying quantities of this product are formed, will cause the resulting relative mill efficiency values to be distorted. Moreover, knowing surface accurately, the efficiency calculations require a surface energy figure. Two such figures are to be found in literature, one by Edser4 and one by Martin.5 Edser's surface energy

Jan 1, 1931

By A. W. Ashbrook

There are many methods of analysis available for compounds similar to those used in solvent extraction processes. However, the majority of these methods are not directly applicable to the determination of solvent extraction reagents, especially in raffinates. The number which are applicable is further reduced if limited to the more simple methods suitable for process control purposes. Commercial extractants are complex mixtures. The complexity is increased by the addition of diluents and modifiers in two-phase systems containing metals. Raffinates from solvent extraction processes contain the more polar components of the extractants and the products of decomposition. Only a limited amount of information is provided by total organic carbon or spectrophotometric analysis. The complexities of the systems require a combination of methods.

Jan 1, 1978

As a service to its readers, MINING ENGINEERING is publishing the mineral industry portion of the 1957 list of Accredited Undergraduate Engineering Curricula in the United States. This list, revised annually, is issued by the Education Committee of the Engineers Council for Professional Development, and covers all phases of engineering education. The AIME is actively represented on ECPD, which was jointly organized by the Founder Societies and various other groups interested in the professional recognition of engineers. ECPD is merely authorized by its constituent organizations to publish a list of accredited engineering curricula for use as desired by those agencies which require such a list. It has no authority to impose any restrictions or standardizations on schools. (Date following school refers to year of initial accrediting.)

Jan 7, 1958

No. 349.-A Canadian university wishes to engage a man to teach non-ferrous metallurgy and ore-dressing as well as to direct research work. The instruction work covers 7 months but the research work is continued throughout the year. To a suitable man the rank of professor will be granted. Applicants are requested to state education, experience, salary desired and any other particulars that might assist in selecting a man for this position. No. 354.-Wanted, for Northern Nigeria, one chief and two assistant mining engineers, competent surveyors, with good knowledge of alluvial tin mining and dressing of tin concentrate. Preferably with previous Nigerian experience, and exempted or able to. secure passport. Apply in writing, stating qualifications, experience and salary required.

Jan 12, 1918

By Kenneth L. Ancell

This paper traces the history and performance of a coal degasification project in the Black Warrior Basin of Central Alabama. The primary coal beds being degasified are the Mary Lee and Blue Creek. The area being developed for gas production is also scheduled for underground mining in two to seven years. The paper discusses the early data collection and evaluation. The coals are extremely gassy with some measurements in excess of 500 SCF/ton. Five experimental wells were drilled and produced. Geologic heterogeneities were encountered which affect the performance of the project. Drilling and completion practices together with well design considerations compatible with under- ground mining are discussed. Finally, the gas gathering and sales system together with the early production history is illustrated.

Jan 1, 1982

THE Institute of Metals Division of the American Institute of Mining and Metallurgical Engineers appointed a Research Committee in 1925 to de-termine what could be done by the Division to promote research work in the United States on non-ferrous metals. It was recognized that a considerable volume of use-ful research work in this field was being carried on by individual industrial companies as well as by the uni-versities and other research institutions, such as the Bureau of Standards. One need only refer to the recent research literature on non-ferrous metals in the TRANS-ACTIONS of the A.I.M.E., and elsewhere, to be con-vinced of healthful research activity in this field. The appointment of the Committee, however, voiced the impression that what was being done was, however excellent, inadequate for the needs of the industry. It was felt that the Division could usefully devote some of its time and effort in stimulating activity in this field. The deliberations of the Research Committee have not failed to develop wide differences of opinion even on the simple questions: (1) whether the Division can aid in any practical manner in this cause and (2) what the features of such aid might be. However, it was clear that there was only one type of research activity with which it could be very usefully concerned, viz., that on subjects of fundamental interest and general application. It was obvious that research work having special objects and more immediate commercial appli-cation should best be left to the industry itself.

Jan 1, 1927

By R. J. Wysor

CHARLES H. RICH, Conshohocken, Pa. (communication to the Secretary*).-Mr. Wysor has certainly covered his subject in the most thorough and able manner and his paper will no doubt result in enlarged effort toward the conservation of this important byproduct. Not all furnace burdens are as rich in alkalies as those noted by Mr. Wysor. In our own experience we have never gone into any extended examination of the materials entering the furnace burdens, but have made a number of determinations of the water-soluble alkalies of our flue and boiler dust and found maximum of about 4 1/2 per cent. K20-too small for profitable reclamation. We have, however, frequently encountered the smoky gas described by Mr. Wysor. Such gas carries heavy fume, and buds with a fitful flame difficult to maintain. So pronounced was the inhibitory effect of the fume that, in extreme cases, the flame of a lighted match was extinguished by the current of gas and it was found impossible to conduct calorimeter tests without preliminary washing of the gas. When the gas was led through a washer filled with distilled water and pieces of coke, the fume was absorbed and the gas burned without difficulty. Careful analyses conducted on the water solution from the washer showed cyanides in increasing amounts in proportion to the difficulty experienced in burning the gas. We, note Mr. Wysor's statement that he has never found evidence of cyanides in their gas, ascribing the difficulty of burning such gas to the presence of chlorides. Our determinations were conducted in such manner as to preclude possibility of interference by chlorine.

Jan 3, 1917

By Charles W. Schwartz, Subash Kolluru

INTRODUCTION Creep of rock in situ, like most rock mass behavior, will be largely governed by the behavior of the natural discontinuities -- bedding planes, faults, and joints, in particular, Several past studies have investigated various aspects of the time-dependent deformation of rock discontinuities; examples include Amadei and Curran (1980), Engelder and Scholz (1976), Johnson (1975), Kaiser and Morgenstern (1979), Solberg et al. (1978), and Wawersik (1974). These studies have provided much insight into the general phenomenon, but they have also produced some inconsistent conclusions and left many unanswered questions. This paper will attempt to shed some light on one of these questions: What is the influence of stress level on the creep of unfilled rock joints? The discussion will follow a two-part approach to the problem: (1) laboratory creep experiments on small scale jointed specimens, (2) a simple theoretical mechanism to explain, at least in qualitative terms, some of the results from the experimental program. EXPERIMENTAL PROGRAM Uniaxial creep tests were conducted on intact and jointed samples of a specially formulated gypsum plaster "synthetic rock." Synthetic rock materials have several advantages over natural rock for long-term creep testing: (a) higher creep rates, (b) lower strength and therefore lower loading requirements, (c) simpler specimen preparation, and (d) more controlled and consistent properties. Gypsum based plasters have been used previously in studies of short-term strength and deformability of jointed samples (Patton, 1966; Einstein and Hirschfeld, 1973). Furthermore, Williams and Elizzi (1977) demonstrated that natural gypsum, at least, creeps in a manner similar to that of most other creep-susceptible natural rocks.

Jan 1, 1982

By E. Topuz, G. Faulkner, M. Karmis, C. Haycocks

The Appalachian coal region of Virginia, southern West Virginia and Kentucky and the extreme eastern portion of Tennessee constitutes a unique area of surface coal mining activities. The area contains a number of contiguously placed coal seams, up to a total of fourteen in some places, which vary in thickness from a few centimeters to 2,5 meters. Much of this coal is of high quality, some being the highest grade metallurgical coal found anywhere in the world. The region may be broadly characterized physiologically as a dissected plateau with a relief above the valley floors of up to 500 meters and a dendritic drainage pattern. Up to six seams may outcrop in the hillsides above drainage, many of which have been subjected to contour stripping operations. Prior to the passage of the surface mining reclamation act, little effort was made to reclaim stripped areas. The passage of the strip mining act, including the controversial requirement for returning the land to its approximate original contour, has forced intensive recla¬mation efforts from the mining industry. The wisdom of this original contour requirement has been the subject of considerable debate and litigation, mainly because of its cost, inconvenience, and value of the land after it has been reclaimed. Regardless of whether recla¬mation is carried out, under current practices slope failures do occur. This in effect circumvents the intent of the law and can expose large unvegetated spoil areas, and contribute to hillside erosion and stream silting. Such failures must be eliminated if further costly reclamation efforts are to be avoided.

Jan 1, 1983

By W. E. C. Coxe

At the meeting of the Institute in Philadelphia, in June, 1876, it was my pleasure to read a paper on the "Manufacture and Endurance of Iron Rails." I then spoke of some trial rails which had been placed in the down track of the Philadelphia and Reading Railroad, over which passed, in addition to merchandise and passengers, most of the heavy coal traffic of that company. One of these rails, made at the Philadelphia and Reading Rolling Mill in 1870, and then placed in the track, was removed in 1876, after having carried about 55,000,000 gross tons, and was on exhibition at the Centennial Exhibition. A piece of this worn rail, twisted cold, was also shown there. One of the same series of rails was allowed to remain in the track until 1878, and short sections of this rail, as well as one not worn, to show its original shape, are presented for your inspection. A comparison of the two will show that the top of the head or tread has morn down 3/16ths of an inch during its nine years of service. It carried in that time 67,000,000 gross tons of freight, passengers, cars, and engines. This rail was made in the usual way of manufacturing iron rails at the Philadelphia and Reading Rolling Mill. The head was made from puddled iron bars, piled, heated, and rolled into bars, 41/2 and 3 inches wide by 1 inch thick, these bars, breaking joints, were made into a pile in section 9 inches square, heated and rolled into slabs 9 inches wide and 2 inches thick; the balance of the rail-pile was made of 41/2 and 3-inch bars, rolled from two-thirds old rails and one-third puddled iron, the

Jan 1, 1880

By Charles C. Hall

The following procedure in estimating mineral oil when mixed with vegetable or animal oils, is the result of a long series of cxperiments based on the method suggested by Sir William Thompson and Mr. A. H. Allen, in a paper read before the Royal Society.* Four to five grams of the oil under examination are weighed out into a porcelain capsule of 75 C.C. capacity. Thirty C.C. of a 10 per cent. solution of potassium-hydrate in alcohol are added, and the capsule covered with a watch-glass is placed in a water-bath heated to about 93' C. The mixture of oil and alkali should be stirred frequently, and after three-quarters of an hour it is boiled with stirring. This will secure the complete saponification of all the vegetable or animal oil. After the boiling has been continued some time, and most of the alcohol is expelled and a thick scum of soap forms on the surface, a little bicarbonate of soda is added to convert the excess of caustic alkali into carbonate. When the contents of the capsule have become pasty an equal bulk of fine, clean sand is stirred in. This makes the soap granular, and facilitates the removal of the last traces of alcohol. The capsule is now heated for two hours more on the water-bath. After cooling, the contents of the capsule are transferred to a short-necked funnel, having a thin plug of asbestos, and washed with petroleum-ether, or some other light petroleum spirit. The ether dissolves out the mineral oil from the soap, and is best collected in a quarter-liter flask having a short neck. The ether can be applied conveniently and effectively by a small washbottle. Care must be taken to effect a complete removal of the oil

Jan 1, 1883

The housing of labor and sanitation at mines in India are difficult problems to solve because-no more than two or three castes will accept the same conditions, and conditions suitable to one coal-field are not applicable to other fields. It is also necessary to consider the financial standing of the different companies. The European companies, which pay 30 per cent. and more dividends, can erect more suitable houses than the Indian companies, which are just able to keep their heads above water. The Santhal will not live in a bucca-roofed house as a permanent dwelling, and both the Santhal and Koras have an aversion to living in a line of attached huts. They have forsaken a whole, line of houses in one of which a case of sickness or death has occurred, and those houses were afterward considered unfit by all other classes of natives. The Santhals, Koras, and Douri castes will not take drinking water from a stand pipe; wells must be furnished. When well water is not available, these people will take water from the nearest pool or tank regardless of whether or not the water is stagnant. The well tops should not he completely enclosed, nor should there be a drain around the top. The ground should slope away from the well. In the Girieih coal fields, the miners have a great objection to pucca floors; they prefer earth which is lapped, easily cleaned, and renewed. As it is customary for the miner to build his own house, the company supplying the roofing material, he takes a special interest in it, keeps it in order, and hesitates to leave it. Each house is surrounded by its own bit of land, which the inmate cultivates.

Jan 12, 1918

By Howard W. Dubois, Charles T. Mixer

Only within the past few years have chemists recognized the importance of the fact, that comparatively large amounts of phosphorus may occur in the siliceous residue left from the acid treatment of iron-ores. We know of one case in which an ore contained about three times as much phosphorus in the insoluble, as in the soluble, form. It was disposed of at a premium, as an exceptionally high-grade Bessemer ore containing 0.010 per cent. of soluble phosphorus, while the insoluble phosphorus brought the total amount up to 0.040 per cent. The magnetite and specular hematite of the Lake Superior districts and the fine ores of the Mesabi range, as a rule, contain very small amounts of insoluble phosphorus. But the mining of the soft hematites and the progressive lowering of the phosphorus-limit in a strictly Bessemer ore, have combined to make the determination of insoluble phosphorus one of the routine-requirements in all analyses of Bessemer ores. The insoluble phosphorus is understood to be that pbosphorus which cannot be extracted by boiling hydrochloric acid of 1.1 specific gravity. The time given for the extraction of the soluble phosphorus will vary, of course, according to the nature of the ore. In ordinary practice the boiling is continued until the residue is white or only very slightly tinged with ferric oxide. This ordinarily takes from half an hour to an hour. The prolonged boiling of ores known to contain considerable quantities of insoluble phosphorus has failed to extract any appreciable amount of additional phosphorus. Very fine grinding and subseqnent sifting through bolting-cloth has not increased the extraction. These statements represent the re-

Jan 1, 1898

R. S. Shoemaker: Our first question is, is there a need for a grizzly before a primary crusher? What is its effect on crusher capacity and crusher maintenance? Is it worth the extra capital cost in a crusher installation? Vincent: ASARCO has a grizzly at Mission. Utah Copper uses grizzlies ahead of their gyratories. There is some quite abrasive ore at Mission, an argillite type of rock, which has a work index of 16.5 to 20, which is getting up toward the taconite classification. We get a life of 12- 16 million tons per set of concaves or per mantle with the grizzly ahead of the crusher. At Duval Corp., some 6 miles to the south of Mission, their crusher installation on a good, hard rock does not have a grizzly, and the last information I had is they get a life of about 2 ½ -3 million tons on their mantle and concave. At Silver Bell, our other copper unit in Arizona, they do not have a grizzly ahead of the gyratory and there they get a life of about 5-6 million tons. At Utah Copper, which we all know is a fairly soft ore, relatively speaking, they get a life of 24-27 million tons with grizzlies ahead of the crushers. I think a grizzly has a very definite effect on the life of the mantle and the concaves. As far as a jaw crusher is concerned, I think that usually it is desirable to have a grizzly if it is properly designed, which means it is self- cleaning. Otherwise I would not like to see one in the circuit.

Jan 9, 1967

By John Cobb

THE attempts of British investigators to arrive at definite knowledge concerning the nature of the nitrogenous constituents of coal have been mainly made through studies of the behavior of coal on carbonization and gasification. There have been carried out numerous determinations of ,the distribution of nitrogen in the products of carbonization under laboratory and large-scale conditions; and by a careful consideration of the extent to which nitrogen is liberated, say as ammonia, at different temperatures and under different conditions of operation as regards atmosphere, it has been possible to form some general notions as to the nature of the nitrogenous compounds present in the coal, and at the same time to arrive at clearer ideas as to what are the important operative factors in determining the ammonia yield under working conditions. This work has been spread over many years and is summarized below. The difficulties of connecting the results in such a way as to allow of the nitrogenous constituents of the coal being described in terms of specific organic structure are great. They arise, for example, in the carbonization process, because the phenomena of decomposition observed at any one temperature can only refer to compounds decomposing at that temperature, each of them with a previous history of chemical transformations occurring at lower temperatures. To put it in another way, the compounds occurring in the coke at any stage are not in the least likely to be those present in the original coal. The same difficulty, in a milder form, occurs when the method of differential solution is attempted. There is always the preliminary question, almost impossible to answer, as to how far the separation by the use of the solvent has involved some form of decomposition of the original compounds. In the following summary, an attempt has been made to bring together results obtained by British workers.

Jan 3, 1925

By S. L. Sass

DURING an electron microscope study of the w phase in zirconium-base alloys,1 a stereographic technique was devised which allows the synthesis of high energy electron diffraction patterns from a single crystal containing several variants of a second phase. The technique will be described using as an example the w phase which forms in a bcc matrix. The w phase was suggested by Silcock et al.2 and Bagaryatskii et al.3 to have a hexagonal structure with (0001)111(111)^, [001]B//[110]B* *The subscripts B and 1 are used to refer to the bcc phase and one particular orientation of the w phase, respectively. and with cell parameters aw = v2aB, where a^ is the lattice parameter of the bcc struc-ture. Since there are four <lll>B directions there should be four orientations of the w phase. In approaching this problem the question to be answered is, "What reciprocal lattice vectors from the B phase and the four w variants lie in the particular reciprocal lattice plane of interest?" One may restate the question in the form, "What plane normals from the B phase and the four w variants lie in the particular reciprocal lattice plane of interest?" The question is answered and the desired diffraction patterns are plotted using the following stereographic technique. Knowing the cw/aw ratio (=0.613 for the as-quenched form of the w phase), a stereographic projection of plane normals from one w variant can be constructed relative to a cubic projection using the above orientation relations, with the direction of the projection along the [001]B direction, Fig. 1. Let us now synthesize the diffraction pattern observed by looking along

Jan 1, 1970

By Fred Beasley

METALLURGISTS have, in the past ten years, overcome many difficulties of high zinc in lead blast-furnace slags. This problem was brought to the front at the close of the late war, by the price obtained for lead and the high cost of labor, fuel, and flux. The Port Pirie plant of the Broken Hill Associated Smelters, Australia, early in 1919 had increased the zinc oxide in its blast-furnace slags from 13.5 to 20 per cent., at the same time reducing the iron oxide in the slag from 33.5 to 25.6 per cent. These results were obtained by the following proceduret the addition of granulated slag to the roaster charge, 10 to 12 per cent., improved conditions of the crushing and mixing and roasting of the constituents of the sinter. By experiments and improve-ments the practice at this plant has developed a normal slag that carries 22 per cent. zinc oxide, and at times runs as high as 33 per cent. zinc oxide, with only slight furnace trouble. The granulated slag is used not, only as a diluent to the sulfur in the roaster charge, but also on account of its value as a slag-forming material and on account of the physical properties it imparts to the finished sinter. The ore is mixed with flux and given a double roast. All the first roasting is by sintering with the Dwight & Lloyd machines. The final roasting is performed partly by Dwight & Lloyd machines and partly by H. & H. pots. The charge to the blast furnaces consists chiefly of the final sinter, slag shells, siliceous and non-bearing sulfur, lead ores. High blast and ore columns are the practice. The greatest care is taken to obtain in the final sinter as low a sulfur content as possible.

Jan 2, 1925

By M. G. Magnuson, H. O. Hofman

When dry chlorine gas is made to act in the cold upon fiuely-divided gold,&apos; it converts the latter with evolution of heat into auro-auric chloride, Au4 Cl4, a hard, dark-red, hygroscopic salt. Moisture splits this salt into aurous and auric chloride, Au²C14 = AuCl + AuCl³; treatment with water converts it into auric chloride and gold, 3 Au²CI4 = 4 AuC1³ + Au². Aurous chloride, when stirred with water, undergoes a similar decomposition, 3 AuCl = AuCI, + Au,. These decompositions of auro-auric chloride and of aurons chloride furnish the explanation for the practice of moistening an ore before it is treated by the Plattner chlorination-process; practical experience having shown that gaseous chlorine gave an unsatisfactory extraction with dry ore. According to Rose12 fine gold is acted upon more slowly by chlorine than gold containing some base metal, e.g., copper. He also says that small quantities of silver increase the rate of solution, but adds that the coating of silver chloride formed, checks, and finally stops, further action, if the percentage of Silver be increased beyond a certain undetermined amount. Bromine3 acts upon finely-divided gold in a manuer similar to chlorine; the auro-auric bromide, Au²,Br4,, however, is not hygroscopic. Upon treatment with water it is decomposed as is the corresponding chlorine salt. It is generally believed that bromine does not act as energetically upon gold as does chlorine. This seems to be borne out by the results in the leach- +1MASSACHUSETTS INSTITUTE OF TECHNOLOGY, BOSTON, MASS.

Jan 1, 1905