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By F. Fraas

ELECTROSTATIC methods are used to separate and concentrate or purify granular particles derived from ores or various synthetic and agricultural products. Compared with other separation methods that require many technological refinements, the electrostatic attraction of fibers, grass, and seeds to charged surfaces clan be accomplished under the most primitive circumstances, and the early development of this method of beneficiation seemed very promising. Precise application of the method to provide high selectivity, however, is a complex procedure, and interest in this method declined. During this period Mr. O. C. Ralston initiated a Bureau of Mines research program oil electrostatic separation. It is the purpose of thins publication to describe the development of the electrostatic method of particle separation from the early beginning to the present resurgence of interest. Most of the information for this description bas been derived from references, a few of which were not available for thorough review. Much information has been drawn from the investitions of the Bureau. Acknowledgments Mr. O. C. Ralston, former Chief metallurgist of the Bureau of Mines, began the research program on the subject and did research on the mils literature. Both Mr. Ralston and Mr. H. B. Johnson, former president of the Huff Electrostatic Separator Co., furnished patent references. A critical review by Mr. F. D. Lamb, Research director, and Mr. M. J. Spendlove, Supervisory metallurgist, Bureau of Mines, College Park Metallurgy Research Center, lifts been of much value in preparing this report.

Jan 1, 1962

By R. E. Scheffel

Most supergene copper heap leach operations today employ forced-aeration, irrespective of ore grade. Unfortunately, there is little published quantification of its benefit. There is a natural desire to strive for the ideal chemical kinetics. The reality, however, is that physical mechanisms control the commercial extraction rate. This paper presents the performance of a number of operations, their operating conditions and physical ore characteristics, which contribute to non-ideal solution distribution and variable extraction rate. Regardless whether one uses forced-aeration, commercial experience to date suggests it is prudent to design for longer leach cycle times to ensure the production target is met.

Jan 1, 2006

By P. K. Chatterjee, G. D. Just

Sublevel open stoping is a low-cost method that has been successfully employed in many large underground mining operations. Where ore body characteristics are suitable, extensive mechanization and the use of large-scale stoping techniques can considerably reduce operating costs. However, careful long-term planning of mine layouts and large capital commitments in development are required prior to production. Implementing precise mine design procedures and carefully controlling operations can result in considerable benefits. This article describes methods to achieve these objectives based largely on mining operations at Mount Isa, where sublevel open stoping has been used since 1932. Ore won by this method accounted for a very large percentage of the total tonnage produced at Mount Isa. Major costs associated with sublevel open stoping can be classified as drilling, explosives and charging, and LHD costs. In this article, analyses of these costs are made with particular reference to stope design. Parameters such as burden, drill hole diameter, explosive density, specific charge, etc., are considered in establishing the interrelationship of unit operating costs, as well as total costs of sublevel open stoping.

Jan 10, 1981

As shown in Table 9, consumption has risen steadily for the period November through April, reaching its highest level since June of 1974. Imports remained at a relatively high level in spite of decreased imports from Zaire and Belgium-Luxembourg. Award prices for cobalt sold by the General Services Administration on June 17, 1976 ranged from $5.058 to $5.41211 per pound of contained cobalt. The high bid was about $1 per pound above the current market price set by the major sales agent in the U.S. for cobalt on April 15, 1976. COPPER: Eight domestic producers on July 1 hiked refined copper prices by 4¢ to 74¢ per pound for cathode and to 74.625¢ for electrolytic wirebar. New York Commodity Exchange (COMEX) June pricing of prompt contracted copper averaged 70.6¢, with daily quotes registering between 67¢ and 72.5¢ per pound. In June, London Metal Exchange (LME) cash wirebar prices averaged 70.3¢, trading between a low of 65.5¢ and a high of 73.6¢. End of the month copper stocks totaled 108,758 short tons for the COMEX and 539,350 metric tons for the LME.

Jan 1, 1976

By C. K. Eilerts

Knowledge of the phase relations of the fluids that exist in the porous spaces of rocks constituting natural petroleum reservoirs and of the behavior of these fluids under various field conditions of operation is essential to the conservation of petroleum and natural gas and to their efficient recovery. The problem of determining whether these fluids are in the liquid or gaseous state and of recognizing the transitions that may take place as the material in the reservoir is subjected to different conditions of pressure and temperature confronts many producers today, especially in certain fields. The subject has grown rapidly in importance since the discovery of and production from deeper reservoirs that have correspondingly higher pressures and temperatures as compared with shallower

Jan 1, 1938

By Karl J. C. Harries

Mineral Agreements and Royalties

Jan 1, 2003

By J. D. Bardill

"The Stoddard mine, Cheshire County, N. H., was explored by the Bureau of Mines in 1944 as a source of the strategic fluorite. It was reported that the vein persisted in the bottom of old workings and the geology of the immediate area indicated the possibility of finding additional lenses.In its program of exploration of mineral deposits, the Bureau of Nines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts pre¬liminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director.Special acknowledgment is expressed for the cooperation and assistance given by Robert F. Sherwood of the United Feldspar & Minerals Corp.; by McHenry Mosier, chief, College Park Division, Mining Branch, who aided in re¬vising this report; and by J. B. Zadra, chief, College Park Division, Metallurgical Branch, and others of his staff, who assisted in performing the beneficiation tests and analyzing samples. The field work was under the direction of Harry P. Hermance.The property lies on the southern boundary of the town of Westmoreland, Cheshire County, N. H., at approximately 72° 39’ west longitude, 42° 27’ north latitude, in the Keene, N. H. (G.S.) quadrangle.Good gravel roads lead from paved State Highway 63 to the property. A dirt road in fair condition suitable for truck leads to the nine.Dwight H. Smith, Putney, Vt., is the owner and has leased the property to the United Feldspar & Minerals Corp., 10 East 40th Street, New York 16, N. Y.Property titles were not investigated.The fluorite deposits of Cheshire Count', H. H., have been known for many years, being reported by Jackson, (Geology and Mineralogy of New Hampshire, by Charles T, Jackson, 1844) and by Hitchcock, in1878 (Geology of Now Hampshire, vol. 3, 1878, by Charles H. Hitchcock). A large pit on the largest or east vein was mined by Lovat Frazer from about 1908 to 1917, This operation is reported to have produced approximately 3,500 tons of fluorspar. In 1917, the American Steel & Wire Co, took over the mine end is said to have produced 3,500 tons of fluorspar before relinquishing the lease in 1923.From 1935 to 1937 the New Hampshire Fluorspar Cc. operated the Stoddard mine, working chiefly on the most westerly of the three known veins on the property, as well as doing some preliminary work on the small central vein. In 1938, the United Feldspar 6 Minerals Corp. leased the mine, and less than 100 tons of fluorspar was produced from exploration and development work, No mining has been done since that time."

Sep 1, 1946

By N. H. Emmons

In the United States the value of gold- and silver-ores is everywhere reckoned in ounces troy of the metal per " short ton " (2000 lbs. avoird.) of the ore. In the case of silver, which fluctuates in market value, the New York quotation on a given day must be known, in order to determine the gross value of an ore at that date. In Mexico the assay is reported 'in kilogrammes of silver or grammes of gold per metric ton. As everyone is aware, this is practically a percentage system, 1 kg. of silver per metric toll (1000 kg.) being 0.1 per cent., and 1 gramme of gold per metric ton, 0.0001 per cent. The notation is simple and convenient for both assayer and miner.* The Mexican government purchases at an unvarying price for silver, payable in silver, and at a fixed price for gold, payable in gold if the seller insists, but preferably in silver at about the rate of exchange between U. S. gold coin and Mesican silver coin. The value of silver is $40.915 per kilogramme in Mexican silver dollars. That of gold is $675.416 per kilogramme in gold coin. The mints do not, as a rule, issue gold dollars, as the government keeps them to pay the interest on the national debt. Almost all bullion containing a considerable percentage of gold is shipped to foreign countries (principally the United States) to be refined. The Mexican mint receives for refining and coining no bullion which is not at least .950 fine in gold and silver, separately or

Jan 1, 1902

By Tad Crowie, Victor Delgado, Nick Katsikaros, Tim Hughes

"A number of silver producers have identified a need for a system to recover silver and gold from base metal flotation concentrates on site rather than sending the concentrate to third party smelters to improve mine economics. Historically intensive cyanidation has only been used for coarse gold gravity concentrates in batch machines but Gekko have applied the InLine Leach Reactor (ILR) to these difficult to leach concentrates.The ILR’s unique ability to operate at various solid to solution ratios, high mass capacity, the ability to handle fines, the use of peroxide to aid silver leach kinetics and simple operation has resulted in significant economic benefits to Hochschild PLC’s Selene and Arcata operations. This paper describes the commissioning phase of the ILR5000BA intensive cyanidation reactors on concentrates from the Selene mine at the Ares Concentrator.INTRODUCTIONIntensive leaching of high grade concentrates in gold ore treatment is now commonplace and is considered an essential feature of most gold circuits (Lane, Fountain and LeBrooy, 2008). The devices commonly used for intensive leaching (InLine Leach Reactor, Acacia Reactor, etc) are specifically designed for the typical coarse nature of the concentrate.In some of these intensive leach applications, significant amounts of silver are co-recovered with the gold. In fact, the intensive leaching conditions of 1 to 2% NaCN in solution and high dissolved oxygen levels, overcome the issue with silver’s slow dissolution rate in traditional CIL/CIP circuits and avoids the formation of insoluble silver sulphide minerals on the surface of the gold (Marsden, 2006).There are a significant number of mine operators producing silver in the form of mixed base metal sulphides flotation concentrates. Typically the mine operators are paid for the silver after processing of the concentrate by the base metal smelter whom recovers the silver during the refining process."

Jan 1, 2010

By Jennifer A. Slatnick

Chlorofluorocarbons (CFC's), once universally accepted as ideal compounds for use in cooling and refrigeration, in foam production, and in cleaning electronic components, are being phased out and eventually banned under extensive international agreements because the chlorine in CFC's is thought to deplete the Earth's ozone layer. The industry has responded with the introduction of alternatives in the form of hydrofluorocarbons (HFC's), which contain no chlorine, and with hydrochlorofluorocarbons (HCFC's), which fill an intermediate gap in the replacement of CFC's. As a result of the elimination of chlorine in the HFC's and the reduction of it in the HCFC's, these alternatives contain more fluorine than the CFC's do. Other nonfluorocarbon substitutes, known as not-in-kind alternatives, contain no fluorine at all. As a result, the fluorspar mining industry, which is the source of fluorine in fluorocarbons through intermediate hydrofluoric acid, is being affected. Concern for this impact has led the U.S. Bureau of Mines to employ its capabilities to analyze various scenarios in the evolution of CFC replacements and substitutes to determine their effect on fluorspar mining. This report utilizes a network flow model to examine the effects of proposed replacements for CFC's, in terms of fluorine content, on fluorspar operations worldwide and on hydrofluoric acid plants in North America and Europe.

Jan 1, 1994

By III, Peter J. Rogers, J. Gordon Ogden

A study is described which attempts to identify the chemical factors of common concern to environmental and exploration geochemistry as indicated by recent work in both disciplines in Nova Scotia. Cores taken in lake sediments define geochemical baselines for the modern and pre-industrialisation periods. The investigation of lake and stream drainage indicates the presence of numerous chemical and organic factors that can be attributed to man's activities, such as construction and energy consumption. Geochemical surveys of lake and stream sediments are used to locate potentially toxic, high risk areas in Nova Scotia. Rapid change occurs in most surface drainage systems with the possibility of numerous chemical reactions taking place. It is found that spatial and temporal variations in the chemistry of modern and recent sediments are of interest to exploration and environmental surveys.

Jan 4, 1992

By Milford L. Skow

MICA is a group name for a number of complex hydrous aluminum silicate minerals that have a sheet or platy structure and extremely variable and complex compositions containing various metallic ions, particularly those from the alkali group. Muscovite and phlogopite, the two varieties of significant commercial value, are the principal consideration of this report; muscovite has major importance industrially. The mica crystal, because of its laminated structure, can be split easily and accurately into thin films that are transparent, flexible, elastic, tough, and waterproof and have outstanding dielectric and insulating characteristics. This combination of properties is not duplicated in any other known substance. The world production of mica can be divided into two main classifications: (1) Sheet mica and (2) scrap mica (including flake mica). In general, separate divisions of the industry produce these two classes of mica, which differ widely in their uses and in the forms in which they are marketed. A glossary of mica terminology is given in appendix A.

Jan 1, 1962

By Patrick M. - Langevin

THIS TALK IS ABOUT : How the DBL mining camp deposits have been found and what is done to find the next one PLAN: Overview of the geological context Historical exploration perspective Deposits geology and key features Conclusion

May 1, 2006

By Roger F. J. Adam

This report summarizes the principles of safely working steep coal seam using longwall mining methods. It presents the state-of-the-art and identifies the problems which result from seam inclination. Details are given on foreign longwall faces achieving good records of safety and productivity when mining on 30 degree and 50 degree inclined seams. Recommendations for further research are suggested.

Jan 1, 1981

By W. D. Sinclair

"Between 1934 and 1956, nearly 31 million grams of gold were produced in the Matachewan area from deposits on properties belonging to Young-Davidson Mines Limited and Matachewan Consolidated Mines Limited. In 1979, production from these properties was renewed by Pamour Porcupine Mines Limited.Most of the gold produced has come from relatively lowgrade deposits (3.4 gl t or less) that occur in an east-trending belt of dykes and irregular bodies of trachytic syenite. Although small by comparison, these deposits have some of the characteristics of porphyry copper-molybdenum deposits. The mineralized syenite contains up to 5 per cent disseminated pyrite and is highly fractured and cut by quartz and quartzcarbonate veinlets. Gold occurs as native gold along fractures, in quartz veinlets and as minute inclusions in pyrite. Minor chalcopyrite and trace amounts of scheelite, molybdenite and galena are also present. Mineralization was accompanied by potassic alteration, consisting mainly of potassium feldspar.Some gold was also produced from small, but higher-grade, deposits in volcanic rocks. These deposits occur near the syenite-hosted deposits and consist of quartz veins and stringers mineralized .with pyrite and gold. Minor gold is present in some low-grade, porphyry-type copper-molybdenum occurrences and, locally, in large, isolated quartz veins.Lead isotope analyses suggest that the gold deposits were formed at about 2700 Ma and were locally remobilized at approximately 2400 Ma, following the Kenoran orogeny. The deposits appear to be genetically related to felsic magmas emplaced in an epizonal environment and deposited from hydrothermal solutions relatively concentrated in S and K20."

Jan 1, 1982

By FREDERICW K. BRADLE

I HAVE been puzzled by two lines of thought'; one emanating from Washington, D. C., to the effect that we must all cheer up, that in a very short time, measured in terms of months, prices would begin to recover, business would become normal, and prosperity would continue on its way just as before the interruption of a year ago; and a second, coming from certain industrialists and economists, expressing fears that all commodity prices were in for a long downward trend, which would cause much unemployment, eventually drag down wages and so restrict purchasing power as to further aggravate the situation. One basis for the fear of a downward trend in commodity prices' is that ifter great wars a depression could last for something like 40 years-the downward trend to such a depression after our recent World War having been postponed for some reason or other; and the basis for another fear was that the production of gold was becoming less. I had 'also been trying for some time past to refresh my recollection as to how my ow11 particular lead interest climbed out of the depression of 1893; and as all the metals have had, and still have. relative values and prices, I can best express what I have in mind by talking principally about lead.

Jan 1, 1930

By E. V. Konopleva, H. J. McQueen, V. M. Khlestov

In addition to increasing grain boundary area during hot working of austenite, the dislocation substructures create potential sites for nucleation of ferrite both at original grain boundaries and at transition boundaries between deformation bands. This development gives rise to a marked increase in the rates of nucleation, of growth and of transformation to ferrite. The combined net effect is product grain refinement that requires less stringent cooling between finish rolling and coiling; hence determination of the above rates would advance process optimization. The important control parameters are the preheat temperature (degree of homogenization), finishing temperature, strain (accumulation near finishing) and the extent of recrystallization after finishing. These effects vary greatly with steel composition; nevertheless, some general rules have been formulated. Moreover, there is also potential for deformation of the refined ferrite. There are other thermo-mechanical processes such as warm forming of metastable alloy austenite to provide a dense substructure that is carried into the martensite on quenching. In other processes, the austenite may be deformed during cooling through the transformation to develop a dense substructure in the ferrite that is stabilized by fine carbides.

Jan 1, 2004

I N the introductory chapter to "Man and Metals," T. A. Rickard wrote "Five hundred thousand years ago the first footfalls of man's oncoming echoed down the corridors of time." This phrase has always appealed to me, not only for its resonance but because it seems to place in some perspective man's place in the cosmos. As we go about our daily occupations and as we meet here tonight, we must agree that we have come a long way slowly at first through the ages of change but with a quickening pace that has brought to man's know-ledge and use, within the last hundred years, more ideas, more material advantages, more opportunities and more comforts than were ever imagined or dreamed of in those long corridors of time. Looking back to the dawn of his-tory, a mere five thousand years ago, there is one aspect of the birth and growth of civilization that has particular significance for the miner and the metallurgist.

Jan 1, 1965

By Dave Kay, Young-Suk Song

To meet the needs of South Korea's rapidly expanding economy, a large number of infrastructure projects are under way to improve transportation efficiency within the nation. These projects include high-speed rail links between major population centres and improvements to the road network. Being densely populated and geographically mountainous, infrastructure development in Korea requires a significant amount of tunnelling. Owing to the predominantly hard granitic nature of rock, drill and blast is the preferred method of tunnel advance. The Korean tunneller, however, faces the same pressures as those of his international counterpart in that both cost and production targets need to be achieved while meeting expectations of both community and regulator.

Jan 1, 2005

By James F. Kemp

Jan 1, 1914