Search Documents

By S. E. Piper, E. M. Buchalter, R. P. King, E. T. Woodburn

The problems involved in an optimum decision making model for flotation circuit are, first of all, to characterize the feed material in terms of parameters which can quantitatively describe the network flotation action in terms of a feasible set of control actions. Once the characterization has been postulated, it is then necessary to devise tests relating to parameter sensitivity, in order that credibility of the model predictions can be assessed. Once a credible model is available, the optimum control set is determined by a hill climbing technique. Details will be reported as to the credibility of model predictions using the stochastic flotation model on a network and further, computational problems associated with hill climbing for a complex objective function are reviewed. Discussion is presented on use of the Rosenbrock technique with constraints and use of a modified objective function with constrained derivatives when employing Fletcher and Powell technique.

Jan 1, 1969

Jan 1, 1920

Some years ago it was my good fortune to inspect some coal properties in Germany, and the most striking impression I received on my trip was that in that country every one in the coal industry, miners and operators, was proud of the fact-not apologetic about it-and that industrially coal was looked upon as a King. The explanation, of course, was that at least 90 per cent of the entire mineral value produced in Germany was from coal, and that it was the very foundation of the nation's industrial life. The feeling was so different from that existing in the United States among those engaged in producing coal that it made a profound impression on me, and many times since then I have speculated about the reasons for the difference in opinion in the two countries. Here, of course, our units are much smaller and more numerous, there is not so large a proportion of technically trained men, and we have the American trait of depreciating the things we do at home; but among those not actively

Jan 1, 1935

By S. B. Christy

Jan 1, 1902

By W. Mostowitsch, H. O. Hofman

In a previous paper,' The Behavior of Calcium Sulphate at Elevated Temperatures with Some Fluxes, we published the results of our investigation into the behavior of calcium sulphate in air; that is, under oxidizing conditions. The results as a whole hold good for a neutral atmosphere, or one which has no chemical effect upon calcium sulphate. The present paper deals with the behavior of calcium sulphate under reducing conditions, the reducing-agents employed being carbon monoxide and carbon, and the changes the calcium sulphide formed undergoes when it is subjected to an oxidizing-roast. Technical literature deals very sparingly with the subject. The information furnished by the recent leading chemical manuals is general. Thus Dammer,2 Missan,3 and Abegg4 quote Berthier as having reduced, in 1823, calcium sulphate with carbon, and Stammer as having done the same in 1851

Jan 1, 1911

By Frederick J. McGarry, Parviz F. Rad

Although tunneling machines have attained very high advance rates in medium-hard rocks, the need for frequent repairs has slowed their use in very hard rocks. Laser- assisted tunneling is expected to improve tunneling machine performance by improving either specific energy or amount and quality of muck. The beneficial effects of lasing are the initiation and growth of microcracks from differential thermal expansion of grains, and overall spalling in the vicinity of the lased area. Using a constant thrust rock cutting device with disk cutters, the effects of cutter geometry, cutter diameter, thrust, and speed variations on specific energy and muck were explored and the improvement in performance of disk cutters caused by lasing was evaluated. It was found that the improvement depends on beam power and density, beam speed, pattern of heating, and cutting pattern and procedure. A focused beam slightly offset from the cutter path gives the most improvement both when cutting on a smooth surface and when cutting in previously cut grooves.

Jan 1, 1971

ALABAMA Anniston. Carrington, F. G. Ashland.-Herr, I. Auburn.-Brown, R. L. Bessemer.-Abbott, C. E. Dobbs, G. G. Ferguson, V. Salmon, H. S. Schaber, C. F. Birmingham.-Adams, J. H. Aldrich, T. H. Aldrich, T. H., Jr. Allen, A. W. Ball, E. M. Bonnyman, J. Bowron, J. Bush, M. W. Crawford, G. G. Crockard, F. H.

Jan 1, 1917

By S. Usui, I. Matsuoka, H. Sasaki, J. Shimoiizaka

Depression of galena by sulfite or chromate ion in xanthate flotation was investigated by means of adsorption measurements, electron diffraction and flotation tests. Flotation of galena was depressed by sulfite ion only when galena had been oxidized; no depression took place with unoxidized clean galena. A similar behavior was found when chromate ion was used as a depressant, with the exception that the chromate ion depressed unoxidized clean galena around neutral pH. Depression was attained with galena on which xanthate still remained in appreciable amounts, indicating that the depression is not due to a decrease in xanthate adsorption. The galena surface produced sparingly soluble films under conditions in which depression of galena took place. These films were identified by electron diffraction as lead sulfite and lead chromate on oxidized galena and as chromic oxide on unoxidized clean galena. These observations in conjunction with contact angle measurements, indicate that the depressing action of sulfite or chromate ion arises primarily from film deposition resulting from the reaction between depressants and the galena surface. The thickness of the film was analyzed by means of electrochemical polarization.

Jan 1, 1976

By A. D. Hodges

The process to be described, whatever other merits (or demerits) it may have possessed, certainly proved a financial success under the conditions of the locality where it was introduced and where a refining process had been sought previously in vain. I have ventured to bring it to the notice of the Institute in the hope that it may prove of some interest as a solution of a practical problem, such as is often presented to the metallurgist in the remote mining regions of the West. The method was used first at the Lyon Mill at Dayton, Nevada, and has been adopted at other tailings-mills on the Cornstock. These mills treat two classes of tailings: "sand," or; material which has passed previously through the pans of the ore-mills; and " slimes," or the fine clayey material which, coming from the battery, is too light to settle in the tanks inside of the mills but is

Jan 1, 1886

HAVING produced one ton of concentrate that contains the copper that can profitably be saved or recovered from anywhere between 3 and 60 tons of mine ore, the ore-dressing engineer passes the result of his handiwork over to the metallurgist for smelting. Essentially, the concentrate is a damp mass of finely ground material consisting of copper sulphide minerals; pyrite, the sulphide of iron; and gangue, usually silica and silicates of aluminum. The purpose of smelting is to produce metallic copper and a slag containing the iron and siliceous constituents by pyrometallurgy-the kind of metallurgy that employs fire and heat to produce the chemical reactions through which it attains its object. Though blast furnaces have been used to smelt Porphyry-mine concentrates, notably at Braden, more than 90 per cent of [ ]

Jan 1, 1933

By Ripu Daman Lama

The size of coal pillars in mines until recently has been determined by experience without being based upon scientific investigations. As a consequence, the size of pillars had invariably been larger than could be accounted for because of the number of unknown factors involved which influence the strength, dictating the use of large safety factors. With the mining going deeper, the size of the pillars greatly increases and sometimes a considerable portion of the mineral property are blocked in the mine pillars required to support the superincumbent strata. With the advances in the field of Rock Mechanics, attention of mine planning engineers has been focused upon the design of mine pillars for safe and efficient working as well as decrease losses of coal. The problem involves the study of three factors: (1) Presence of stresses in the area and their distribution on pillars in the course of extraction. (2) The influence of external factors on the strength of coal. (3) The inherent mechanical properties of coal. These aspects have been studied by a large number of investigators, the first by in-situ stress measurements and photoelastic studies and the second and third aspect by studies conducted in the laboratory on small size specimens (Bunting, 1911; Evens & Pomeroy, 1961; Gaddy, 1956; Greenland et al, 1941; Steart 1954). The size of the specimens tested in the laboratory has been limited to a few inches and the results obtained have been extrapolated by large factors, sometimes several hundred times the largest specimen tested. In these tests much consideration has not been given to

Jan 1, 1971

By D. F. Hewett

[In an increasing degree in recent years, especially since the war, men in many parts of the world are turning their attention to the problems of the future, attempting to appraise the basis and extent of man's progress and interpret the problem that he faces in the near future. The war made clear to ma persons the degree to which modern industry depends upon t continuous flow of enormous quantities of raw materials, a especially of the minerals. In many circles throughout t world, the question of adequate supplies of the mine especially the fuels and metals, for near as well as more remo needs is receiving serious consideration. As a result, persons representing the state as well as industry are looking to geologists and engineers for all the data that throw light on the distribution, extent and availability of the minerals that must serve coming generations.] Obviously, in a brief research I have been able to consider only a few sources of the metals in Europe, perhaps fifty out of a total of many hundreds. In order that the conclusions may have value, however, I have chosen districts which have been important sources during some epoch of the last three hundred years or more.

Jan 1, 1932

1. List of Manuscripts Seen in America 2. List of Manuscripts Seen in England 3. List of Maps Examined 4. List of Newspapers Examined 5. General Bibliography - Numbered Reference List

Jan 1, 1942

UP TO and including 1931, the twelve mines that were treated in THE PORPHYRY COPPERS had produced 17.4 billion pounds of copper worth $2,820,000,000. With a little help from six others (three of them did not start output until 1954) that record had been increased at the end of 1955 to 60.5 billion pounds worth $10,440,000,000. Today, ten billion dollars is not as impressive as it once was; but it still represents a lot of value. It must be remembered that this is newly-created wealth, produced entirely from material considered worthless when the Porphyry era started about fifty years ago. At that time "rock" that contained less than forty pounds of copper per ton was regarded by competent mining engineers as value- less. It was not "ore" in the economic sense. Today, ore is being successfully exploited that contains less than twelve pounds of copper per ton. Also, in Peru, a typical Porphyry operation is being launched by a partnership of four United States mining companies that will involve an initial capital investment of $200,000,000 for mine development, plant construction, and the provision of related facilities. Of this project more will be said at the end of the chapter. The point I want to make now is twofold: (1) that phenomenal progress has been made in Porphyry engineering and technology; and (2) that exploitation of an important Porphyry copper deposit has become an industrial enterprise of truly great magnitude. Much had been accomplished by 1931; but that progress has been dwarfed by the achievements of the past 25 years- a fact that, in the nature of things, is as it should be.

Jan 1, 1957

[United States PAGE Alabama 226 Alaska 226 Arizona 226 Arkansas 227 California 227 Colorado 230 Connecticut 231 Delaware 282 District of Columbia 232 Florida 232 Georgia 232 Idaho 232 Illinois 233 Indiana 234 Iowa 234 Kansas 234 Kentucky 234 Louisiana 235]

Jan 1, 1928

By J. L. Sepulveda, R. F. Yap, R. Jauregui

INTRODUCTION The Third Theory of Comminution, oftentimes called the Bond Theory, was first published by Fred C. Bond in 1952. Since then, it has been widely used in the milling industry to size crushing and grinding equipment as well as to predict and evaluate their performance. Although two other comminution theories were advanced almost a century earlier, one by Rittinger, 1867, and the other by Kick, 1885, their use was limited because they did not agree with actual commercial comminution systems (Bond, 1961). According to Bond's Third Theory, the work input is proportional to the new crack tip length produced in particle breakage, and equals the work represented by the product minus that represented by the feed. For particles of similar shape, the crack tip length is equivalent to the square root of one-half the surface area, and the new crack length is proportional to [(1/vT - vF)]; where P and F are particles diameter of product and feed, respectively. For practical calculations, the particle diameter can be expressed in terms of the 80% passing sizes, P and F, respectively. Therefore, the work input is given by, [10 _ 10', W = Wi [7P_7F(1)] Where W = the energy input to the mill, (kwh/t) Wi = Work Index, (kwh/t) P = square sieve opening which 80% of the product passes, (microns) F = square sieve opening which 80% of the feed passes, (microns) Equation (1) is the mathematical statement of the Third Theory, or the Bond equation. Numerically, the work index is the energy required in kwh/t to reduce a given material from theoretically infinite feed size to 80% passing 100 microns. The work index of a particular material is determined in the laboratory by conducting the standard Bond grindability test. Bond developed separate tests for the rod mill and the ball mill. The simplified test method described in this paper, which is used at Anaconda Research Center to approximate the work index, is an alternative procedure to the ball mill

Jan 1, 1982

By Pope Yeatman

In my experience, perhaps the most interesting problems came up during the testing, prospecting, developing and equipping of the Chuquicamata and Braden Copper Mines in Chile, and it is proposed in this article to give as briefly as possible what some of those problems were, their solutions, and the decisions made as to the different methods to be employed. The romance of mining is still a great lure to the young man who is making a choice of a profession to follow. The thought of travel to strange and out-of-the-way places, the glamor of pioneer life, the excitement of discovery, the constructive work of building something, entirely "from the grass roots up," or of reconstructing a played-out property and making a success of it-all of these phases have a strong appeal and often influence the young man in the choice of mining as a profession. That great engineer, Col. Seeley Wintersmith Mudd, whom we are endeavoring to honor, while having too much common sense to have been materially influenced by the romance of mining, certainly experienced all of the

Jan 1, 1932

By George Rice

A PROBLEM of possible subsidence of the surface from mining opera-tions, which might have had disastrous results, arose in 1913 at the Brier Hill mine, of the Penn Iron Mining Co., near Norway, Mich., now managed by Pickands, Mather & Co. for the Bethlehem Steel Co. A double track and sidings of the Chicago & North Western Railroad passed over part of the mine, and if subsidence had reached the surface it might have affected the stability of the tracks. The chief purpose of this paper is to record the facts disclosed by investigations of underground movement from 1913 to 1919, when the tracks were moved, and subsequently at intervals, as engineering data of value from mining carried on below the tracks in the steeply pitch-ing lenses. A secondary purpose of this paper is to describe a novel method for determining the rate of speed of upward breaking above the mine excava-tions. This method was found effective and might be used elsewhere under similar conditions. The mine workings under consideration were developed from the Brier Hill shaft, which was circular, concrete-lined, 14 ft. in diameter, and about 900 ft. deep. They extended about 800 ft. westward from the shaft, and nearly parallel to a corresponding length of the railroad tracks. The highest part of these workings was at a depth of 400 ft. below the tracks (Figs. 1-12). The mining company had the right to remove the ore, the railroad assuming that the surface would be sup-ported. Finally, without legal controversy, an amicable adjustment was reached as to what should be done to lessen or obviate the hazard of subsidence.

Jan 1, 1934

By Henry M. Bates, Roscoe Pound

Mr. Chairman and Gentlemen: I accepted your Chairman's invitation to speak to a group of experts in this field with the greatest hesitation, because I know little or nothing about it. Certainly I can make no detailed suggestions, or suggest planning along very definite lines. You cannot do that sort of thing in a vacuum, and as I have suggested, my knowledge of the whole oil problem is next to nothing. It is possible that as a student of our public law, constitutional law particularly, for a number of years, I have acquired a perspective that may enable me to offer, for what they are worth, some general thoughts on these problems. I think that nothing in the whole field of law requires more definitely and clearly the functional approach than does the problem of a sound legal solution of the difficulties of the oil and gas industry. The industry is dealing with substances that are peculiar, and one must know how those substances act and what has been the history of the industry, to undertake to make anything like specific suggestions. I certainly am not qualified.

Jan 1, 1935

By T. A. Rickard

Among the gold-deposits discovered in recent vears none is more extraordinary in richness or interesting in structure than that of the famous mine at Mount Morgan. At a time when but few Australian mines were known to the world outside the colonies, Mount Morgan was quoted as an occurrence, unusual not only in its origin (for it was said to be dye to geyser-action) but also in the purity of its gold. The mine is situated just within the tropics, twenty-six miles southwest of Rockhampton, in central Queensland. Queensland attained in 1889 the first place among the gold-producing colonies of Australasia, a position previously always held by Victoria. In that year Queensland produced 737,822 ounces, while Victoria cape second with 614,838 ounces. Of the four chief mining districts Rockhampton stood first, as the following figures show: Quartz crushed, Yield,. Average per ton, Tons. Ounces. Oz. Dwt. Rockhampton ,....81,138 340,669 4 4 Charters Towers,.. .. 109,328 165,551 1 10 Gympie,.....106,625 112,847 1 1 Croydon,.....29,423 51,156 1 15 It should be added that Queensland has but little alluvial mining, the total output from this source in 1889 being only 5044 ounces, none of which came from the four principal gold-fields. Leaving out Rockhampton, the output of which is practically that of the Mount Morgan mine, it will be noted that the more northerly goldfields show the highest average (Gympie being furthest from and Croydon nearest to the equator). This is largely explained, however, by the increased cost of milling, due chiefly to the want of water for batteries and the consequent economical necessity of selecting high-grade material only for crushing. During the year ending November 30, 1889, the Mount Morgaq

Jan 1, 1892