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By Alvin Kaufman

At the turn of the century the U.S. had a gross ALVIN KAUFMAN Mineral Economist U.S. Bureau of Mines area slightly in excess of three million square miles, a population of 76 million, a gross national product of $37 billion (constant 1929 dollars) and a mineral production valued at $2 billion (1929 dollars). Some 60 years later its area had increased by 600 thousand square miles, population had risen 140%, gross national product was seven times greater and mineral production had grown to a value five times that of 1900. Of perhaps greater significance, however, were the changes wrought by technology. It was during this period that the "American Way of Life" was revolutionized by the introduction of the airplane and the automobile; man also took his first probing steps in the utilization of nuclear energy and pre- pared to unlock the secrets of space. It was during these six decades, also, that he learned to create additional new materials, some of which were from old sources such as plastics from petroleum and coal. These new materials have created competition and attendant problems for the traditional materials such as iron, copper, lead and zinc. Additional problems undoubtedly will be created by technologic advances in the future.

Jan 2, 1963

By O. Bergmann, R. E. Lueders, R. R. Ellefson, H. M. Brennecke, D. S. Davies

A new hydrometallurgical process has been developed to recover copper from sulfide ores. Copper is leached in a staged reactor system utilizing nitric and sulfuric acids at 105OC. Iron is removed from the pregnant liquor as a jarosite, and cathode copper is electrowon directly from the purified pregnant liquor. The spent electrolyte is recycled. Nitrogen oxides evolved from the leach are reconverted to nitric acid and are also recycled. Sulfur is rejected as So, jarosite, and gypsum. The process is highly versatile and can recover precious metals, molybdenum, and zinc when these elements are present. Continuous, integrated, semi-pilot plant operations using chalcopyrite ores demonstrated 99% copper leaching and production of cathode grade copper. Economic evaluation shows that the process is competitive with pyrometallurgical and other hydrometallurgical processes.

Jan 1, 1982

By K. V. S. Sastry

First attempts to apply computers for the modeling, simulation and analysis of mineral processing unit operations date back to almost twenty years. Since then substantial efforts have been directed to the development of computer software for mineral processing. Current literature indicates considerable activities in the development of computer packages for interactive and batch simulation of individual unit operations and integrated plant operations. This paper presents a comprehensive review of various simulation systems that have been described in the literature along with a discussion of present trends in the development of mineral processing simulation software. Finally, the paper includes a detailed discussion of the desirable features in future simulation packages.

Jan 1, 1984

By Peter L. Swanson

A microcrack process zone is frequently suggested to accompany macrofractures in rock and play an important role in the resistance to fracture propagation. Attenuation of surface waves propagating through mode I fractures in wedge-loaded double-cantilever beam specimens of Westerly granite has been recorded in an attempt to characterize the structure of the fracture process zone. The ultrasonic measurements do not support the generally accepted model of a macroscopic fracture that incrementally propagates with the accompaniment of a cloud of microcracks. Instead, fractures in Westerly granite appear to form as gradually separating surfaces within a zone having a width of a few millimeters and a length of several tens of millimeters. A fracture process zone of this size would necessitate the use of meter-sized specimens in order for linear elastic fracture mechanics to be applicable.

Jan 1, 1984

By W. H. Chang

The phase identification results on several Mg-base alloys are presented. These results have been correlated with strength data and microstructural studies to indicate that carbide dispersion may contribute significantly to raising the recrystallization temperature and strength of Mo alloys. Evidence is presented to show that the degree of carbide dispersion, and hence the extent of strengthening, is governed by the "metal/carbon" ratio which, in turn, depends on both the carbon content and the presence of stable -carbide-forming alloying elements. IN recent years, Mo-base alloys containing small additions of C, Ti, and/or Zr have been developed, which exhibit much higher recrystallization temperature and strength than those of unalloyed Mo. The superiority of these alloys undoubtedly results from simultaneous operation of more than one strengthening mechanism. In the present paper, the strengthening effect of carbide dispersion will be discussed. Although the role of carbide dispersion is being increasingly recognized, the nature of the carbides has, to the author's knowledge, not been well es- tablished. In Table I are presented some of the phase identification results on representative Mo alloys. These results have been obtained by X-ray diffraction of residues electrolytically extracted from an ethyl alcohol solution containing 7 pct HC1.

Jan 1, 1961

By Klaus Schonert

The elements of a mill matrix and the classifier matrix de- scribing the grinding process depend on operating conditions, especially on the feed rate. Relationships between the matrix elements and the feed rate have a great influence on the stability of a closed circuit and its optimum point. These problems have been studied by means of computer simulation and different kinds of classifier characteristics have been considered. A circuit with a cross stream classifier has only a limited range where stable operation condition can be attained. Beyond the stable limit, the recirculation ratio increases rapidly and there is no correlation between feed rate of the circuit and feed rate of the mill. In comparison, a spiral stream classifier gives a wide range of stable operation. The recirculation ratio can be greater than in the case of the cross stream classifier if the feed rate is small. The results of the simulation provide a better understanding of the real behavior of closed circuit grinding.

Jan 1, 1969

By J. B. Newsorn

VERTICAL SHAFTS in the United States have heretofore been sunk by blasting and mucking. The blasting leaves uneven, shattered walls which usually must be supported. Even though the walls will stand, shaft lining is needed to furnish supports for the cage guides, pipes, and power conduits. The lining is generally timber, and as timber can be most easily framed into rectangles, rectangular shaft openings are the rule. The timber reduces the size of the cage floor. For example, if the Idaho Maryland company had put down No. 2 shaft by blasting and mucking, the cage area would have been about thirty per cent of the total shaft area. Besides a low percentage of useful area, an ordinary shaft is subject to fire hazard and to timber maintenance charges. It is also poor for ventilation because the timber ribs cause eddies which greatly reduce the speed of the air currents. A bored shaft does not have these disadvantages. The walls are smooth, circular, and not shattered by blasting, so lining is not required in most

Jan 1, 1936

By Raymond B. Ladoo

Abrasives include the substances, natural or artificial, that are used to grind, polish, abrade, scour, clean or otherwise remove solid material, usually by rubbing action but also by impact (sandblasting, for example). They do not include abrasive tools-for instance, lathe tools and files-or polishing agents such as waxes, which act by filling pores. Detergents and cleaners whose action is chemical rather than physical are omitted although some chemical-action polishes and cleaners may also contain solid abrasives; for example, many automobile and metal polishes. General Considerations The most important physical properties of materials that qualify them for use as abrasives are hardness, toughness (or brittleness), grain shape and size, character of fracture or cleavage, purity or uniformity. For making bonded grain abrasives such as grinding wheels, additional important factors are stability under high heat and bonding characteristics of grain surfaces. The economic factors of cost and availability are always important. No one single property is paramount for any use. For some uses extreme hardness and toughness are needed, as in diamonds for drill bits; for others, the factors of greatest importance are hardness and ability to break down slowly under use, to develop fresh cutting edges when grains become worn-for example, in garnet for sandpaper, neither highly cleavable or friable grains nor extremely tough grains are wanted. For still other uses, great hardness is objectionable; for example, abrasives for dentifrices and for glass-cleaning soaps. For the most efficient use in the more critical applications, the different types of abrasives are rarely completely interchangeable; thus, while crushed quartz and garnet are both used in sandpaper, the papers are not at all interchangeable in their use applications. In the last analysis, the choice of a high-grade abrasive depends upon the quality and quantity of work done by the abrasive per unit of cost. Initial cost of an artificial abrasive. may be much greater than that of a natural abrasive but the artificial abrasive may do so much better work than the natural one, and do it so much faster, that the ultimate cost will be less. It is on this basis that artificial abrasives have largely replaced natural abrasives for grinding metal. Classification Abrasives may be divided into two general classes, natural and manufactured. The former includes all rocks and minerals used for abrasive purposes without chemical or physical change other than crushing, shaping or bonding into suitable forms. Manufactured or artificial abrasives are made either by heat or chemical action from metals or mineral raw materials. On page 2 is a list of the most important abrasives, classified as to inherent types and as to forms in which they are used industrially. For most types of use there are manufactured products that can be substituted for the natural products, usually at higher initial

Jan 1, 1960

Jan 1, 1970

Wabush Mines is the largest single supplier of iron ore to the Canadian steel industry, with 42% of its 6 million tpy of iron ore production going to the company's two Canadian owners-The Steel Co. of Canada and Dominion Foundries and Steel Ltd. Six other companies hold interests in Wabush Iron Co. Ltd. These are Lykes-Youngstown, Inland Steel Co., Intrerlake Steel Corp., Wheeling-Pittsburgh Steel Co., Finsider of Italy and Pickands Mather & Co. Field work on Wabush began in mid-1957 when a long-range program of economic, geologic, and metallurgical investigations started. This work was followed in 1959 by the construction of a temporary camp and a 700-tpd pilot plant. At the same time, work was also started on a 38-mi railway connection to Ross Bay, Newfoundland.

Jan 1, 1970

By H. D. Dahl, Roger C. Parsons

In order to improve roof stability, Continental Oil Co.'s research program, initiated in 1969, was directed toward defining the geological parameters that affect the severity of roof conditions in any particular area of the mine. In addition, the program was seeking to define why roof falls in the Humphrey No. 7 mine (and in northern West Virginia-southwestern Pennsylvania coal mining areas) are oriented so that they occur primarily in north-south rooms or entries. Conclusions and recommendations from this study of roof fall orientation are given.

Jan 1, 1973

By Craig R. Smith, Warren Pfefferle

Tests were conducted utilizing large flat jack devices placed in a vertical slot for high pressure loading of rock to measure in-situ properties of a rock mass. The high pressure flat jack devices were used as a site investigation tool to obtain rock mass properties. Tests were conducted before and after a 100 ton surface high explosive detonation test to assess explosive effects on the rock. It was conclusively demonstrated by these tests that meaningful flat jack tests could be successfully accomplished; also, a significantly different response of the rock medium was measured as larger areas of rock were loaded. Surface jointing was severely disturbed by the explosion.

Jan 1, 1971

By M. J. Langley

The American Zinc Company’s mining operations in East Tennessee are located in Knox and Jefferson Counties. Mineralization occurs, intermittently, through a strike length of more than 30 miles, from near the eastern edge of Knoxville northeastward to a few miles beyond Jefferson City. The presence of zinc in these Counties has been known for well over 100 years. In 1910 it was brought to the attention of American Zinc Company that zinc sulphide deposits in the Mascot area might be attractive. Following an examination and some surface prospect drilling, the American Zinc Company of Tennessee was organized and acquired the Mascot properties in 1911. Operations began in 1913 on the basis of 1,000 tons per day mill capacity. With the successful operation of the Mascot mines, the Company undertook explorations in the area from Jefferson City southwest through Friends Station to Mascot. The efforts resulted in development of substantial tonnages of zinc ore and enabled the Company to expand the Mascot and New Market milling operations to their present capacity of 11,100 tons per day. Folded and faulted Paleozoic sedimentary rocks under- lie the mining district. The principal zinc mineralization occurs in a group of strata known as the Knox

Jan 1, 1970

By F. C. Schora, H. P. Meissner

COUNTERCURRENT staged processes involving chemical reactions between solid and gas streams are becoming more common. Such operations are generally carried out in a series of fluidized beds with each bed acting as a stage. Fig. 1 is a schematic illustration of a series of stages located in a single column, with a solid stream moving down through this column from stage to stage counter to a rising gas stream. The reduction of iron oxides with hydrogen and carbon monoxide is one of the reactions which can be advantageously carried out in such a countercurrent system. Calculation of the performance of a countercur-

Jan 1, 1961

By A. W. Edelen

THE Teziutlan copper-zinc deposit is supposed to be of late Cambrian or early Paleozoic age. The country rocks are a series of schists or phyllites, flat lying and in the form of a plunging anticline. The ore deposit occupies a single horizon in the schist for a known horizontal extent of 1200 meters. Along its strike occur four large lenses or ore bodies. These ore bodies occupy positions along the flank and extend to the crest of the anticline. The primary mineralization is in the form of quartz, pyrite, sphalerite, chalcopyrite and galena, with a few scattered silver anti-monides. Quartz and pyrite form the mineralization between the ore lenses. In the ore lenses the sulphides appear as a massive, very fine-grained intergrowth of minerals. The intergrowth suggests a contemporaneous deposition of the heavy sulphides. The grain size, usually under 0.09 mm., makes the separation difficult and fine grinding important. The ore bodies were formed at great depth by solutions probably originating in the same basic magma that gave rise to the dolerite sills that are so common in their vicinity.

Jan 1, 1937

By Charles R. Isaacs

In 1972 Kennecott Explorations, Inc. conducted a three month cruise to the central Pacific as part of a study of deep-ocean manganese nodules. One of the objectives of the voyage was to collect at least 200 tons of nodules for use in extractive metallurgy research and various engineering tests. It was determined to cut off production at a maximum of 200 tons, should we reach that amount before the end of the 38 on-station days. We were able to reach that goal; 200 tons of nodules were collected, representing an average return of 2340 lb from 171 dredge runs. Once equipment and techniques were refined, normal returns consistently exceeded 2 tons per haul. Up to this time, Kennecott had sampled extensively with the use of small free-fall devices using wire rope and winch equipment. These devices have never offered a viable method for collecting nodules in bulk, and we sought to develop a dredging capability which would give some assurance of meeting future requirements with efficiency and economy. After testing a series of increasingly complex dredge designs at sea, it was decided to utilize two of the simpler configurations, which after modification provided the basic design for the dredge used.

Jan 4, 1974

By Sharon Brady, Catherine O’Donoghue, John V. Beall, Paul C. Merritt

Between 1950 and 1965, more than 80% of all phosphate rock produced in the world each year was used as fertilizer, either directly applied to the soil or processed into mixed chemical fertilizers. Of the potassium salts produced, 95% followed suit. A variety of uses in industrial chemicals and consumer products absorbed the remaining percentage of each. Future trends in these two commodities will be dominated by what happens to the fertilizer market. Farming is much the same as mining the soil. Plants remove the minerals little by little. Phosphate and potash comprise two of the three primary nutrients removed in this way, the third being nitrogen. Phosphate stimulates early root formation and growth, whereas potash is a salt necessary to root strength.

Jan 10, 1966

By Milton Ohring, Stephen M. Edelglass

THE recently determined coefficients for diffusion of very dilute impurities in aluminum are shown in Table I. Of these data the activation energies for Ag110, cu54, Mn54 and zn85 are clustered about the value of self-diffusion in aluminum; for the remaining

Jan 1, 1970

By Benjamin B. Lawrence

The lease-system is the gradual result of the development of our larger producing mines throughout the State of Colorado. The operation of a mine, or group of mines, by corporations has been attended, in many cases, by disaster, owing to the difficulty of securing a fair day's work from the men employed in the mine, and the loss entailed by careless mining and sorting of high-grade ores, or by lax or inefficient management on the part of superintendents and foremen. Given, therefore, a mine that has been practically abandoned by its owner, for the reasons given, but still possessing merit, the lessee appears on the ground and secures a lease for a year, or term of years, from the owner, upon the payment of a royalty upon the gross smelter- or mill-returns of the ore which he mines. In this way many of our abandoned mines have been re-opened by the miner, who, with two or more associates, has been enabled, by careful attention, to obtain profitable results.

Jan 1, 1893

By A. M. Gaudin, D. W. Fuerstenau

By streaming potential techniques, the zeta potential of quartz has been measured as a function of the concentration of dodecylammonium salts at different pH values. These experiments indicate that adsorption of dodecylammonium ions takes place as individual aminium ions until a certain critical concentration is reached in the double layer, at which point the adsorbed collector ions begin to associate into patches of ions, called hemimicelles. Because of its effect on the surface potential of quartz, pH controls the adsorption of dodecylummonium ions. The value of cooperating agents and nonionized constituents of flotation systems is discussed. Previous investigation of the role of pH in the flotation of quartz with anionic collectors is here extended to an inquiry of how the cationic collector, dodecylammonium acetate, is adsorbed at the quartz-solution interface. The equilibrium amount of this collector adsorbed by quartz has already been measured as a function of concentration and pH. The weight of prior evidence has suggested that two mechanisms are involved in the adsorption of this collector by quartz, but with existing adsorption measurements alone it is not

Oct 1, 1955