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By Wayne Anderson

Regarding the technical paper by Thomas E. Finch and Edward L. Fidler, "Recovery of Stray (Thin) Seams in Western Coal Mining." I would like to comment on this subject. In western Canada, most strip mines encounter thin seam coal or rider seams. Although the paper addresses the problems and costs associated with the recovery of this coal, it does not take into account what the savings are. Without looking at the savings, the "Total Objective" is of course not clear. I feel that in a stripping operation the mine can spend per ton (of the thin seam) up to their dragline stripping costs per ton to recover a rider seam or thin seam. The reasoning behind this is simply that this is the price the mine will have to pay to expose an equivalent amount of coal without the recovery of these thin seams. If the mine can recover a rider seam or thin seam for less than the dragline operating costs per ton, a savings will be realized. By recovering a thin seam or rider seam, the life of an ore body is extended by that amount of coal not thrown away. In addition, the cost of land acquisition, associated permits, capital, and reclamation will be reduced as more coal is delivered for a given area. When the above points are considered, the recovery of these thin seams can be very profitable and indeed worth recovering.

Jan 1, 1983

Professor Somasundaran has given an excellent presentation of the numerous problems which remain to be solved before the selective aggregation of fine particulates is likely to see broad commercial application in the beneficiation of mineral fines. However it is useful, I think, to reiterate some of the major problem areas. The over-riding factor which has limited the development of selective aggregation techniques is that processes such as coagulation and flocculation tend to be inherently non-selective. Conditions which favor the aggregation of one kind of fine particles usually favor the aggregation of all kinds of particles. As Professor Somasundaran has pointed out, the state of aggregation of a fine-particle dispersion is primarily determined by the forces of interaction between the individual particles. In most systems, the dominant forces are: 1. van der Waals - London Dispersion forces between the particles themselves 2. electrical double layer forces 3. steric forces between adsorbed layers on the surfaces of the particles. The London Dispersion forces between like particles are always attractive, but for dissimilar particles dispersed in a fluid medium can, in some cases, lead to a net repulsion. Electrical double layer forces always lead to repulsion between like particles but can, again, cause either attraction or repulsion for dissimilar materials. The steric forces, which are by far the least understood of the three types, can also lead to attraction or repulsion depending on condi-

Jan 1, 1979

By E. L. Corp, J. C. Johnson, W. G. Pariseau, M. Poad, M. E. Fowler

This paper describes a comprehensive geomechanics case study of a full¬scale test stope at the Carr Fork Mine. The mine is owned by Anaconda Miner¬als Company and is located near Tooele, Utah. Large diameter blast holes were used in a new method known as blast hole post-fill (BHPF). The new design proved highly successful in contrast with earlier experience with vertical crater retreat (VCR) stopes. The main geomechanics objective was the estab¬lishment of a design procedure for optimizing stope and pillar dimensions with respect to productivity and recovery. An integrated three-part approach consisting of mine measurements, laboratory testing and finite element calcu¬lations was taken. Independent correlations of 0.88 and 0.89 between calculated and measured displacements and between estimated and observed yield :ones substantiate the finite element design approach using UTAH-II. Subse¬quent stope and pillar design analyses indicate that doubling of the original stope width at 50% extraction is quite possible without sacrifice of safety or stability.

Jan 1, 1984

ALFRED C. LANE, Tufts College, Mass. (written discussion*).-The attention of members may well be called by Allen to his discoveries, which affect not only correlations in Michigan but, as I have pointed out,1 the use of names like "Animikie" which are widely applied. It shows that one disadvantage of the wide use of locality names is that local discoveries may show that they are inappropriate. The Wewe hills were found not to contain the Wewe slate! So we note that Allen, in his correlation, drops the term Animikie, which his researches indicate covers both middle and upper Huronian: It would seem well, then, in dividing the Huronian or Proterozoic, to use, as Allen does, terms like upper, middle, and lower Huronian, or newer, middle, and early, which may be shortened into eo-, mio-, and neo-Huronian rather than to carry local terms far away; or we shall soon be

Jan 12, 1919

By John H. Ratcliffe, Hans T. Lundberg

In airborne gravity surveys effects of acceleration and irregular movements of the aircraft must be balanced out or overcome. The gradient of vertical gravity is recorded, therefore, by using two masses instead of one. As the amplitude variations are infinitesimal and difficult to measure accurately, at of gradient during flight is positive or negative. The positive portions of the pattern can then be indicated and contoured. Even with these simplifications, the source of energy must be exceptionally stable. General Principles: In the conventional gravimeter the weight of a standard mass is determined at a number of selected points within the survey area. In most systems weight is determined by comparing the gravity pull with extension or torque produced in a wire spring. The instruments employed are sensitive to the slightest movement; they cannot be used on a moving platform unless velocity is kept strictly uniform.

Jan 8, 1959

By Warren Weaver

SOME of the advantages of the inductive method of electrical prospecting were emphasized in a paper by Dr. Max Mason.1 Since this emphasis was misunderstood by some to indicate a too exclusive interest in inductive methods, we are especially happy to help correct this impression by reporting on some of our work on surface potential methods. EARTH CURRENTS AND SURFACE POTENTIALS When two electrodes, A and B, are placed on the surface of the ground a distance d apart, and a 100-volt battery is connected across the elec- FIG. 1.-LINES OF CURRENT FLOW AND SURFACE POTENTIAL IN MILLIVOLTS IN THE CASE OF A HOMOGENEOUS EARTH. trodes, current flows from the positive electrode A to the negative electrode B. The current does not pass directly from A to B along the straight line joining these two points. In fact, a negligible amount of the

Jan 1, 1928

By Bunting S. Crocker

In the summer of 1961, the Anaconda Research staff and Kilborn Engineering Ltd. began a study to investigate the possibilities of using some form of autogenous grinding in the new concentrator which Anaconda was planning to erect at Butte, adjacent to their Berkeley pit. The following criteria applied to the project: 1) The Butte mill was to be able to handle 36,000 to 42,000 tpd of copper ore, taken from the Berkeley pit and adjacent underground mines. 2) The plant was to be built in six units. 3) It would be started up two units at a time. 4) Equipment from the Anaconda mill was available for use in the new location. 5) Tonnage would be maintained at Butte and Anaconda, with equipment being moved down as required. 6) The ore from the Berkeley pit was known to vary widely from place to place in the pit and to be generally soft and friable.

Jan 5, 1964

By Lane Mitchell

A ceramic product or processed material is a solid composed of materials which have been subjected to heat above 468.3°C (875°F). The raw materials, which are blended together (or in some cases used singly), are selected and utilized for various reasons such as ease of fabrication, aid to processing, to yield desired properties after processing, lack or controllable degree of toxicity or hazard, availability, cost, and perhaps other considerations. Almost all solid inorganic, some organic, and some liquid and gaseous materials have the potential to be used individually in some ceramic product. There are several fundamental functions to be fulfilled in every ceramic product and a number of secondary functions are desirable in specified products. These functions are generally met by the most widely occurring minerals and rocks of the earth and their debris. This fact characterizes ceramics as a field utilizing the raw materials most available to man. Of course, specified products utilize synthetics, organics, and rare inorganics to produce desired results. Any solid nonmetallic product processed by subjection to temperature above a red heat may be called a ceramic product. Widely used construction materials and units, domestic utensils and units, industrial parts to facilitate manufacture, technical components, and aesthetic creations are very often of a ceramic nature because of their durability, inertness, hardness, ease of fabrication, cost, and availability of the ingredients. Often, organics or metals cannot meet desired specifications for some of these products. The rocks and minerals and mineral debris of the earth are largely siliceous. Oxygen and silicon comprise roughly 75% of the earth's crust with aluminum, iron, calcium, and the alkalies following in abundance. Silica (SiO2) and silicates can be melted to form glasses. Alumina (A1203), present in a mineral compound, gives greater durability, hardness, and strength, but lessens the glass-forming property. Iron, calcium, and the other alkalies flux silica and reduce melting points. Thus sand, which is generally almost pure SiO2, and clay, which is generally hydrated alumina silicate, are the most widely used of all ceramic raw materials-principally because of the glass-forming propensities of silicates. In ceramic formulations, clay is generally a refractory filler or skeletal material, having in the raw state a plasticity derived from its colloidal grain size and its water-loving nature. On the other hand, silica sand is a glass former or nonplastic filler. Clay and silica sand in pure forms are quite refractory, i.e., not easily melted. Clay, although siliceous, is less of a glass former than pure silica and is more refractory. Natural contaminants, such as iron oxide or limestone, adulterate many clays and some sands. These contaminants act as fluxes and reduce the fusion points of the mineral or blends. Glass is made from silica sand by fluxing the sand with strong bases, usually soda ash and limestone. Red building bricks are hard and durable because the sand and clay have been partially fused with help of natural iron oxide serving as a flux. The iron oxide performs a dual function, serving as a pigment as well as a flux. In a blend of clay and sand and iron oxide, the sand is more susceptible to fusion than is the clay. Although silica sand and clay are the most widely used raw materials in most ceramic products, many other minerals, and some nonminerals are utilized in products where these materials can produce or aid in achieving desired results. Limestone and dolomite, feldspars, pigmentary minerals, refractory oxides or carbides, and special property producers can

Jan 1, 1983

By Paul A. Schafer

BALATOC mine, the principal gold-producing mine in the Philippines, is 10 miles southeast of Baguio, in the Cordillera Central of northern Luzon.1 The region is a deeply dissected plateau, ranging in altitude from 3000 t0 5000 ft. above sea level. The rocks consist chiefly of granodiorite, diorite, and remnants of metamorphosed sediments, cut by dikes of andesite porphyry and quartz-diorite porphyry. All are intruded by a volcanic breccia plug, oval in horizontal section, about 3200 ft. long and 2300 ft. wide, which is the north central part of the mineralized area. Three main vein systems have been developed (Fig. 1): q6, 231 and 364, which strike about N.70°E. and dip 5o to 90°S. Each system is a braided zone consisting of many individual components. They are disturbed by a series of premineral faults or shear zones striking about N.45°E. Twelve of these produce important effects on the persistence, character, and quality of veins. From west to east the faults are named (after claims): Hog, Big Gun, Bull, Pine, Lolita, Bar No. I, Bar No. 2, Curt, Sun, Helen, Itoe, and Frog. They are early breaks formed prior to the N.70°E. vein fractures. Mineralization occurs on them but, with several prominent exceptions, they are too low grade to mine. A number of northwesterly striking faults complete the structural pattern. Although they are relatively abundant, the effect on the veins is so small that they do not present any problems in mining or development. All of these faults that have been observed are later than the N.70°E. veins and offset them to the left. NORTHEAST FAULTS The early northeast faults* are notably continuous in spite of their small displacements, 20 to 100 ft. Frequently they appear so weak that their importance is masked and their identity clouded. The gouge along any of these faults may vary from exceedingly weak at one point to very strong at another point only a short distance away. In other words, the amount of gouge depends on the changes of attitude of the fault plane, and is no indication of the extent of the movement. Places where walls are spread apart are filled with gouge squeezed from tight places. Also, mineralization sometimes obscures fault gouges by replacement. The mineralization of northeast faults has produced several important ore bodies; namely, 231 west on Pine fault and q6 vein on the same fault. To a smaller extent, Lolita, Curt, Bull, Bar No. I, and Sun

Jan 1, 1942

By T. M. Anderson

Open pit mining at Inspiration began in 1947 after 32 years of underground mining. Two separate pits are included in the operations: the Thornton pit, which measures approximately 2500 x 2000 ft, and the Live Oak pit, which is 1500 x 3000 ft. The geographic centers of the two pits are approximately 4000 ft apart, and at the closest point, the two slopes are only 500 ft apart. Today, much of the open pit mining is being carried out in areas which were broken by earlier underground block caving operations; less than 50% of the total material moved has required drilling and blasting. In the solid or virgin areas, the, material ranges only from soft to medium hardness, thus simplifying drilling, blasting and loading operations. As a result, most mining costs and problems have been centered around truck haulage, truck maintenance and the ever-increasing length of the grade haul.

Jan 3, 1963

By R. Neilson Clark

THE coal-beds of Canyon City are situated six miles below the town, upon the Arkansas River. At this point the Rocky Mountains have thrown out from their main ridge two spurs. The one to the north, containing Pike's Peak and Cheyenne Mountain, is known as part of the "Rim Range;" the one to the west and south is known as the "Greenhorn Range." Against these syenitic mountains, the later rocks are piled and uplifted ; at right angles to the direction of this main uplift is the axis of a lesser plication. On the north, west, and south, the pitch is steep, gradually flattening as it approaches the centre of the basin and rising again to the east at a pitch of about 5", thus forming a perfect basin, the centre of which is only three miles east of the base of the Greenhorn Range.

The following are excerpts from the report of the Treasurer of the United Engineering Society, for the year ending Dec. 31, 1915. Finances Due to the growth of the activities of the United Engineering Society, it was found desirable early in the year to consolidate the various accounts and financial records of the Society and of the Library, heretofore kept separately, and to have all the data pertaining to the building and its operation in the charge of one individual. An assistant secretary especially assigned to this work has been appointed, and a separate office has been established. The Finance Committee has had all of the records brought fully to date and has prepared a new set of account books to meet the new conditions. The Real Estate Account now includes the following items: Land $ 540,000.00 Building 1,050,000.00 Equipment 33,171.16 Founder Societies, Preliminary expenses 24,000.00 Total $1,647,171.16

Jan 4, 1916

By Boris J. Kochanowsky

In a mobile crushing unit system trucks are replaced by a conveyor, which results in a continuous, almost fully automated operation with all its attendant advantages. Because of new designs for large mobile crushing units that have been placed on the market, the use of these plants has increased significantly during the last three years. Gains in productivity and reductions in costs are vital to every mine operator, and the shovel-crusher-conveyor system is a powerful tool with which to achieve this goal. New Designs Increase Throughput While Reducing Size The basic concept of the shovel-crusher-conveyor scheme of operations is simple and sound, with the result that domestic operators are showing a growing interest in its application. A number of operators have been using small mobile crushing plants for several years, but large operators, in spite of considerable interest, have not been able to use this system because no mobile crusher capable of crushing 1000-2000 tph of rock loaded by a large shovel (6-12 cu yd) has been available. A suitable crusher must accept rock of the size handled by these large shovels, be simple in design, easily maneuverable, remotely controllable, and have price and maintenance costs not much higher than those for stationary crusher installations.

Jan 9, 1968

DISCUSSION, A. Y. Bethune presiding M. E. Wadsworth and W. M. Fassell (University of Utah, Salt Lake City)—The authors of this paper should be complimented on the experimental techniques they have employed to investigate the rate of solution of galena in sodium hydroxide solution. Studies of this type are important not only as a practical means of leaching normally non-leachable substances, but also to determine the mechanism of solution at the solid-aqueous solution interface. There is some question, however, as to the conclusions which have been drawn by these authors concerning their proposed mechanism. Unfortunately, the contribution of OH- was not definitely established in their work, and concentrations less than 0.5 N NaOH evidently were not investigated. The pressure data at 123°C and 0.5 N NaOH were used to determine pressure dependency and the subsequent model proposed was taken as correct on the basis of the three points presented in Fig. 5 of the paper. In developing the

Jan 1, 1954

By Philip McKenna

WHEN a new material becomes available to industry, it is useful to describe its properties as a guide to its most effective application; and when the new material may be produced in compositions having a series of graded properties, tests to select the combination of properties best adapted for various uses are helpful. The class of materials to be con-sidered in this paper are hard tool materials produced by processes of powder metallurgy from hard carbide constituents and various matrices of iron, nickel or cobalt, or alloys of them with tungsten, or tungsten and carbon. The customary use of carbide hard alloys is for metal-cutting tools; although wire-drawing dies, lathe centers, follow rests, grinding rests, burnishers, rolls, extrusion dies, measuring gauges and micrometers, and a number of other tools are also made with these hard alloys as the essen-tial wear-resisting parts. The properties and tests to be considered are those affecting these uses. In the development of tool, materials since the industrial revolution we have had carbon tool steels, Mushet steel, high-speed steels, stellites, and now cemented carbide compositions. For an understanding of the latter category of materials their properties and uses relative to the older and more familiar tool materials will be considered.

Jan 1, 1938

By T. L. Joseph

IN connection with its investigations of the blast'-furnace process, the Bureau of Mines, in coöperation with the Minnesota School of Mines Experiment Station, developed a 6-ton experimental furnace. Such a furnace was needed to determine the feasibility of producing ferromanganese from Minnesota manganiferous iron ores, a problem of national importance because of the present need for manganese in the steel industry and our small reserves of ferro-grade ores. Furnace operators are reluctant to use new or untried raw materials or to make decided innovations in practice on account of the financial hazard of experimenting with full-scale equipment. A small furnace which can be operated at a relatively low cost is particularly adapted for testing new, raw materials and for determining the feasibility of decided innovations in practice. Laboratory experiments, plus whatever information may be available, are valuable but often do not indicate the net result of changes in an operation involving a large number of interrelated variables. From time to time the coöperation of the Bureau of Mines is solicited in connection with problems involving departures from normal procedure. Under these circumstances some sort of a practical demonstration is a desirable forerunner to full-scale operations which appear feasible after small-scale tests.

Jan 1, 1928

By T. A. Read, S. W. Kitchen, H. I. Fusfeld

At the present time most artillery cartridge cases are used only a single time. Since the process of reshaping a fired cartridge case so that it may be used again is much simpler and cheaper than the original manufacture of the case, it is clear that important savings could be effected if such re-formed cases were used in place of new cases. Extensive use of reconditioned cases has been hindered in the past, however, by the deterioration of the brass which may occur in the period of time between the first firing and the reconditioning of the cartridge cases. This deterioration sometimes results in a dangerously high incidence of firing splits in groups of reconditioned cartridge cases. It appears that the mechanism of the deterioration is the season cracking of the brass, for season cracks, of varying degrees of severity, may frequently be found in the cartridge cases after their return from the field. There are, of course, severe practical limitations to the extent to which fired cartridge cases can be protected from corrosion under battle conditions, particularly since the powder residue in the case is itself corrosive. The present paper describes a rapid method of testing the sidewalls of artillery cartridge cases for the presence of season cracks. This method has been developed specifically for use in connection with the reconditioning of fired cases, and makes it possible to carry out 100 per cent inspection. This new method of inspecting cartridge

Jan 1, 1945

T. R. HARRISON, Washington, D. C. (written discussion *).-Ad-vantage will be taken of this occasion to mention briefly a form of double potentiometer which has been used at the Bureau of Standards for about 2 1/2 yr. in calibrating thermocouples. The calibrations referred to are those made by comparison to standard couples. In order to insure equality of temperature between the couples, the junctions are fused together; consideration of fundamental principles will show that this introduces no error. Two separate potentiometers are used, one connected to each thermocouple, and each potentiometer is provided with a reflecting galvanometer. The two spots of light are reflected on to a single scale, the galvanometers being set in such a position that the spots coincide on the scale at a point marked zero when the circuits are open or when the potentiometers are balanced. By setting one potentiometer to a desired value and adjusting the other so that both spots pass across the scale together as the temperature rises or falls, simultaneous readings are obtained. By making observations first with a rising temperature and then with a falling temperature, the rates of rise and fall being approximately equal, and taking the means of the results found, several minor errors such as those clue to differences in the time lags of the two systems, etc., are eliminated or greatly reduced. The differences between the values

Jan 12, 1919

By Charles Baskerville

Shales containing "kerogen," or bituminous matter, which on destructive distillation yield oily and tarry matters resembling petroleum are here designated as oil-shales. They differ from oil-bearing shales from which petroleum may be obtained by so-called mechanical means. The educts obtained by the destructive distillation resemble some or all the varieties of petroleum, depending on the character of the shale and the mode of treatment. Some shale oils have a paraffin base, some an asphaltic base, or a combination; some run high in sulfur compounds. The methods of refining and cracking, therefore, are essentially the same as are used in refining petroleums. In 1860, in this country, over fifty companies were successfully distilling various natural bituminous materials for the production of " coal oil," used for illuminating purposes. The discovery of petroleum and the failure of these companies to save and utilize the valuable byproduct, ammonia, brought about their inevitable doom. Prior to that time, more or less successful efforts were made to produce from the shales of Scotland oils for illuminating and heating purposes. Competition of native petroleum from the United States early eliminated some of these companies and with the entrance of oil from the Russian and other fields into the world's markets, the Scottish oil-shale industry underwent serious and trying experiences until, in 1916, only four (Scottish) were paying concerns. These survived only through energy and the application of skill in saving valuable byproducts. A few companies have successfully operated in France and New Zealand. The Canadian Government showed active interest in the New Brunswick shales, which exist in quantity and are more valuable than the Scottish shales. The retarded development of that valuable asset of the Province of New Brunswick was most unfortunate, especially when the product was so much needed in the prosecution of the war. The economic success of a shale-oil industry depends on the following factors:

Jan 1, 1921

By Georges Fleming

The new burden preparation plant of ARBED Luxembourg, Belval- Works, which comprises 2 large sinter strands, is equipped with a process computer connected to a comprehensive process control system. The main jobs done by the computer are the control of the raw mix composition, and thus the monitoring of the stacking of the piles at the bed-blending plant, and the optimization of the sintering process. Among the optimization criteria, quality is considered as the most important. The sinter quality, characterized by the mechanical strength and the state of oxidation, is controlled automatically. The control system which we have dev loped is highly reliable; as a result, the standard deviation of Fe++, for the control of bivalent iron, has been narrowed to 0,5 % and the standard deviation of the IS0 + 6, 3 mm index, for the control of the mechanical strength, has been kept within 1 %. Thanks to these results, the combined savings in fuel consumption at the sinter plant and at the blast furnaces have covered the total costs of the optimization project in 2 years. By applying automatic control, the optimum driving range of the sinter plant has been defined and these new guidelines are used for monitoring the sinter production.

Jan 1, 1977