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By John C. Nigro

Bench scale and pilot plant research was conducted using dolomites (CaO,MgO) lime as the basic additive in the preparation of self-fluxed pellets from a typical magnetic taconite concentrate (5.57 S_2). The specific objective of this investigation was to ascertain the viability of the magnesia lime pellets in high temperature oxidizing and reducing atmospheres. Pellet basicity and induration temperature were major parameters affecting fired pellet quality; temperatures ranging from 1,200° to 1,250" C appeared to be the most favorable for production of self-fluxed pellets with basesities (B) above 1.0. Comparison of the mechani¬cal and metallurgical properties of regular (acid) and self-fluxed pellets (B 1.55) produced under similar conditions in a modified grate pelletizing machine showed that the self-fluxed pellets were more resistant to abrasion and to high and low temperature reduction disintegration, an important consideration in commercial application. The Plus 3 mesh Linder index increased from 68 percent (regular pellets) to over 90 percent (self-fluxed pellets). The reducibility and swelling indices of the self-fluxed pellets were found to be comparable to the regular pellets.

Jan 1, 1972

By D. L. Paulson

The Bureau of Mines is investigating pyrometallurgical and chemical methods for extracting copper from sulfide ores under conditions that provide for control of gaseous and solid emissions. Under this program, a new electrothermic reduction process was developed to produce blister copper after collecting essentially all of the sulfur by a single-unit operation. The process feasibility was indicated by a laboratory-scale investigation that demonstrated chalcopyrite concentrate can be roasted to less than 1 percent sulfur and that the resulting calcine can be reduced with carbon to blister copper by a cyclic process in a single arc-smelting furnace. Pilot-scale tests in an 800-kV-A electric-arc furnace demonstrated that 98.4 pct of the contained copper can be continuously recovered as metal by operating at bath temperatures between 1,350° and 1,375° C. Smelting rates of approximately 225 lb of blend ft2 of bath surface/hr resulted in power consumptions of approximately 520 kW-hr/ton of blend. The blister copper that was produced contained less than 0.1 pct iron while the precious metals reporting to the copper product and gangue material elimination were similar to those in a conventional smelting operation.

Jan 1, 1976

By Y. M. Zhao

The separating performance of a pilot dry beneficiation system using a gas-solid fluidized bed was investigated with coal from South Africa. The coal used for the study has a low inherent moisture content, a moderate ash content, a moderate volatile content, a low sulphur content and a high calorific value. Its washability is moderate. Experimental results show that the separating quality of the fluidized bed drops gradually as the feed-coal particle size decreases. The probable error, E, values for 50?25mm, 25?13 mm and 13?6 mm coals were 0.04 g/cm3, 0.06 g/cm3 and 0.09 g/cm3, respectively. The cause of the differences in separating characteristics was analysed by particle dynamics and numerical modelling. Furthermore, the pilot fluidized bed was employed to separate 50-6mm coal. In this experiment the coal ash content was reduced from 23.74% to 11.79%, with a probable error, E, value of 0.07 g/cm3and a recovery efficiency of 98.26%. This indicates that the fluidized bed is applicable to the separation of coal from South Africa and has good separating performance and wide applicability. Keywords: feed-coal particle size; gas-solid fluidized bed; dry coal beneficiation; numerical simulation.

Jan 1, 2010

By William N. Patterson

Drive systems for mining machines are usually sized to accommodate anticipated peak loads. Usually, the average power requirements are considerably less. Energy storage and power averaging are attractive concepts for mining machinery and could have far-reaching implications. The purpose of this program was to: ? Identify truly feasible concepts, ? Identify advantages/disadvantages, limitations, and constraints, ? Evaluate feasibility based on today?s technology, ? Identify anticipated safety problems, and ? Provide the designer with a comprehensive literature base. Concepts evaluated include flywheels, high energy batteries, gas charged accumulators, inductive storage, capacitive storage, springs and counterweights, thermal, closed cycles, internal combustion engines, trolley systems, and hybrid systems. A comprehensive reference index is provided. Included is an appendix containing abstracts of the pertinent literature.

Jan 1, 1980

By Jack Kadlecik

This final technical report describes the concept feasibility study, testing, design and development effort which went into. The quick opening enclosure access cover and flame path tolerance checking system. A detailed definition of the explosion-proof multiple start threads is shown for two (2) sized electrical enclosures.

Jan 1, 1972

By Galen H. Clevenger, MARTINUS H. CARON

Although there are exceptions, oxidized silver ores containing the higher oxides of manganese are generally refractory to hydrometallurgical methods of treatment. When these ores are of high enough grade they can be smelted; indeed, some rather low-grade ores of this type have been smelted at a profit because of their fluxing value. In the past, when these ores could not be smelted, they either were not treated or were treated at low efficiency, generally by cyanidation. The need for thorough investigation of the problem was therefore evident for some time before the writers began their research. The problem of treating manganese-silver ores seems to have been recognized first about 35 years ago by C. W. Goodale in applying pan amalgamation at Tombstone, Ariz. He attributed the low extraction of silver to the fouling of the mercury by manganese rather than to the presence of a refractory compound of manganese and·silver. Although definite knowledge as to the cause of the poor extraction of silver was lacking, a more or less effective preliminary treatment, that is, a chloridizing roast, was applied. E. M. Hamilton, in 1909, was perhaps the first to define clearly the problem as it affects the cyanidation of silver ores and to suggest possible methods of preliminary treatment. Most of the work done in the interval between the appearance of Hamilton's paper and the assumption of the investigation by the authors was in the nature of routine tests covering suggestions already made rather than of research directed to a fundamental study of the problem. No practical application has so far been made of any of these proposed processes. The investigation described in this bulletin has proved that there s a refractory compound of manganese and silver-probably a manganite- insoluble in cyanide solution and other common solvents for silver. Although this compound has not been isolated from natural ores, it has been made synthetically, and shows all the characteristics of the natural product. Furthermore the authors have shown definitely that heating in air a relatively small amount of a silver compound with a large excess of silica (in the proportions ordinarily occurring in a commercial silver ore) renders

Jan 1, 1925

By C. H. Herty

As the problem of inclusions in steel has become increasingly important, more and more attention has been paid to the source of the oxide inclusions in steel. In killed steels the oxide inclusions are traceable to the reaction of deoxidizers with the iron oxide dissolved in the steel during the refining period of the open-hearth heat. In a large class of steel known as "rimming steel" the action of the steel during solidification depends entirely on the gas evolved, and this evolution in turn is controlled by the amount of iron oxide in the liquid steel in the mold. It is therefore of great importance to be able to determine the amount of iron oxide dissolved in steel and to devise methods for the control of iron oxide in any class of steel. The object of the present investigation was to obtain a true value of the oxygen content of liquid steel. If the steel has not been deoxidized, the greater percentage of the oxygen is present as iron oxide in solution.

Jan 1, 1932

By S J. Brace

About 180 000 tons of explosives are used annually underground in South Africa. Most is loaded into holes less than 50mm in diameter. 75% is consumed in the gold and platinum mines where holes are between 25 and 4omm in diameter and no more than 3.0m in length. The small amount of explosives per hole with extreme conditions of heat, humidity and seismic activity, make the choice of explosive on safety and technical grounds very important to the success of a blasting operation. Taken together with the fact that many underground precious metal operations are now marginal then the choice of an explosive, when its price is also considered, becomes critical to the very viability of some mines.

Jan 1, 1994

By O&apos, M. W. Neill

Mini-piles have been found to be a practical, technically correct remedial underpinning method. They can be constructed in limited access areas with very little disruption. Experience indicated that mini-piles installed using a down-the-hole soil displacement hammer would be particularly effective in the "bottomless" Beaumont Clay formations in the Houston, Texas, U.S.A. area. The University of Houston Foundation Testing Facility was ideally suited to perform tests on mini-piles. The availability of extensive geotechnical data and previous pile test results was invaluable in evaluating the mini-pile test data. As expected, the mini-pile test results were consistant with test results from large sized driven piles in the same soil formation.

Jan 1, 1989

By F. V. Antonio, R. S. Pizarro

Masbate Gold Mines, dormant since WWI I, are now back in operation. The ore treatment plant incorporates carbon-in-pulp processing, utilized because of the ready availability of coconut shell charcoal in the Philippines and the high clay content of the ore. A detailed description of the plant, including the surprisingly fast and efficient alcohol stripping facility is presented. Operating data for the plant is provided together with an interesting performance evaluation of mechanical versus air- lift agitated leach tanks.

Jan 1, 1981

By Jonathan E. Ludlow

A field test was conducted to demonstrate and quantify the relationship between deep cutting and the creation of airborne respirable dust for longwall mining With a double-ended ranging drum shearer. The testing program was carried out on the 3 North longwall of North American Coal Company's Quarto No. y mine in Claringten, Ohio. Continuous recordings of the dust levels were made at both the midface and tail ate areas. Data were collected during 27 shifts during which time 81 complete mining, cycles took place. Both drum speed and the number of picks per line were varied systematically during the testing program to alter the depth of cut while the production rate was held constant by maintaining a constant haulage speed. The test results indicated that at the midface position, airborne respirable dust was strongly dependent upon the depth of cut as influenced by both the drum speed and number of picks. Drum speed had a much stronger effect than number of picks over the experimental range, since a halving of drum speed reduced dust levels by approximately 60 percent while removal of every other vane pick resulted in only a 2.1 percent reduction at constant production. At the tailgate position, however, neither effect was strongly apparent. A tendency for the slower drum speeds to he associated with reduced power consumption and higher haulage speeds (and therefore production rates) was also noted. It is recommended that longwall operators oper¬ate at the lowest available drum speed wherever possible.

Jan 1, 1981

By Carl Lubbe, Ron Frye

Numerous articles have been written regarding the effects of blast control plugs in an attempt to quantify stemming ejection rates, air overpressures, fragmentation’and other parameters measured using these devices. In an effort to further attempt to understand the function of these devices, field and laboratory research conducted with various stemming devices was performed to enhance existing data sets and analyze otherphenomena that occur when these products are used.

Jan 1, 1998

By Paul M. Tyler

The technology of clay and the manufacture of ceramic products therefrom, and also the clay resources of most of the individual States, are already covered by a voluminous literature. The present resume touches these matters only briefly; its purpose is essentially to bring together in small compass certain of the elementary factors affecting the potential commercial value of a clay deposit. In its preparation the author made extensive use of the annual chapters on Clay in Mineral Resources of the United States and in the two annual issues of the Minerals. Yearbook that succeeded them. For careful review and constructive criticism of the manuscript, the author is indebted to Hewitt Wilson. GENERAL DESCRIPTION The term ?clay? includes a great variety of substances that may differ widely in chemical mineralogical and physical properties. No two clays are exactly alike. All of them however, have the prominent characteristic of becoming more or less plastic when wet. Nearly all of the useful clays can be molded into articles, will hold their shape while being dried, and can be converted into a hard, rocklike substance by heat. Clay may, and in fact usually does, consist of a number of minerals among the commonest of which are kaolinite, quartz, feldspar, iron oxides, mica, bauxite, calcite, and manganese oxides. Organic matter is often present. Pure kaolinite, which has the formula A1203. 2 SiO2. 2H2O, is ordinarily, considered to be the parent "clay substance," butt most clays contain other hydrated mixtures of alumina and silica (aluminosilicic acids) along with indefinite amounts of sand and other nonessential minerals3/ Even, this so-called inert matter affects the plasticity, drying shrinkage, ease of drying, and final density, and at high temperatures may react chemically with the clay substance.

Jan 1, 1929

By Terry R. Neumann

In 1989, the Bureau of Mines conducted a mineral resource investigation of the 52,350-acre Jersey Jack study area, located in the Clearwater Mountains of north-central Idaho. Twenty-eight mines and prospects were examined, and 483 rock, placer, and petrographic samples were collected during the field study. Two properties contain gold resources; mining company data show the Robinson Dike mine contains an estimated 940,000 tons of "drill proven and probable reserves" averaging 0.041 oz/ton gold, and the Bureau of Mines investigation showed the Blacksand placer mine contains an estimated 64,000 cubic yards of identified placer resources averaging $8.13 in gold per cubic yard. Sample analyses from other properties indicate that gold resources are likely to exist; however the low tonnage, narrow, fissure-vein type deposits would require mining by relatively high-cost underground methods and would be subeconomic at a gold price of $400/oz.

Jan 1, 1991

By P. T. Brooks

Mineral nodules from the ocean floor represent a vast potential source of manganese, nickel, cobalt, and copper. Process development studies to devise methods for recovering these metals were conducted by the Bureau of Mines using two types of nodules--relatively low-grade calcareous nodules from the Atlantic Ocean and higher grade siliceous nodules from the Pacific Ocean. Ammoniacal carbonate leaching of reduced nodules appeared to have the best potential for processing the calcareous nodules, but the method proved to be impractical for recovering manganese. Extraction of 90 percent or better of the nickel, cobalt, and copper showed the technique to be attractive for recovery of these metals. The siliceous nodules appeared amenable to a process that starts with either a sulfur dioxide leach or a sulfation roast followed by a water leach to dissolve the soluble sulfates.

Jan 1, 1971

By Robert W. Waytulonis

This publication contains 1,000 citations of technical and semi-technical literature treating diesel-powered equipment usage underground both generally and specifically. These citations were gathered by U.S. Bureau of Mines personnel over the period of 1978-1983. The citations concern diesel engines as powerplants for underground mining use; their design, emission characteristics and control, maintenance, usage; and health and safety aspects. All citations have been abstracted and arranged 1n a subject classification system with extensive cross-referencing.

Jan 1, 1983

By Roderick Eggert, Dipesh Dipu

We look at the empirical evidence of coal block auctions in India to understand how competitive intensity affects the bid amounts in common value auctions. The results suggest that competitive intensity measured through the number of bidders for a coal block is instrumental in determining the bidding outcomes. The presence of higher numbers of bidders in the auction leads to higher bids - every additional bidder causes the bid amount to rise by INR 142.67 per tonne of coal for auctions studied for 127 coal blocks from 2014 to 2023. The paper also examines the moderating and mediating effect of competition on bids and on excess of bids from the comparative market price of coal from alternative source of Coal India Limited. The results indicate that competitive intensity does not have statistically significant impact on the relationship between common value of coal blocks and bids, neither as a moderator nor as a mediator. The strategic behavior of the bidders has also been observed as bidders have been seen to bid in a higher than market price in order to outbid the competitors.

Feb 1, 2025

By Gary B. Glass

Seventeen percent of US coal production now comes from the 19 surface coal mines in the Powder River Basin of northeastern Wyoming. The Powder River Coalfield, which coincides with this topographic and structural basin, is unique to the conterminous US, in that it contains an estimated 934.4 Gt (1.03 trillion st) of in-place coal resources. At least 13.2 Gt (14.6 billion st) is a compliant, strippable reserve base. In 1993, an estimated 162 Mt (179 million st), or 98% of the coal mined in this Wyoming coalfield, came from the thick - average 30.5 m (100 ft) - subbituminous, Wyodak coalbed, or from the Anderson and Canyon coals in the one mine where the Wyodak is split into two separate coalbeds. The other 2.7 Mt (3 million st) of coal mined in the Powder River Basin in 1993 came from the School, Badger, Monarch and Deitz No. 3 coalbeds. In this "world class" coalfield, there are at least 13 other persistent, 3 to 15 m (10 to 50 ft) thick, coalbeds as well as the Big George and Lake De Smet coalbeds, which are each 61 m (200 ft) or more thick in places. None of these latter 13 coals are mined at this time.

Jan 1, 1994

By D. Gendzwill, N. Martin

"In early 1987, the Patience Lake potash mine near Saskatoon, Saskatchewan, was closed due to uncontrollable floodingWater inflows were first encountered during routine mining in 1975 at the south boundary of the mine lease. Underground grouting and construction of bulkheads limited the flo but did not completely stop it. Subsequent seismic surveys showed that the mine had approached the edge of a large collapse structure in which the salt and potash had been partly dissolved and removed by groundwater.In 1986, the small flow into the mine started to grow. Despite renewed grouting, the flood increased and outstripped pump capacity. The grouting program temporarily slowed the inflow but was unable to stop it. Eventually, from seismic and drilling evidence, it became clear that the water source was an extensive system of vertical fractures which would be impossible to seal by drilling and grouting from underground. A new plan to install 14 bulkheads underground would have sealed the water source from the rest of the mine but the construction program could not be completed before rapidly increasing inflow threatened to fill the mine. The underground mine was closed and a new solution mine started in 1988."

Jan 1, 1996

By Terry J. Close

U.S. Bureau of Mines personnel studied the 33,900-acre Silver Peak Range North Wilderness Study Area (NV-060-338), in order to evaluate its identified mineral resources. The area studied lies between the towns of Silver Peak and Dyer, about 40 miles southwest of Tonopah, in Esmeralda County, Nevada. There are no producing mines in the area studied. However, development of Sunshine Mining Company?s Sixteen-to-One silver-gold mine, located in the Silver Peak mining district near the eastern edge of the study area in the early 19801s, has stimulated recent interest. The Sunshine Mining Company claimed two sites within the study area in 1985. Also, Intermountain Resources, Incorporated, located a group of claims at a prospect along the west side of the study area in the Dyer mining district, and in 1986, began drilling. Other claimants are holding two other claim groups by assessment. At the five currently (1987) held sites, precious metals occurrences are being investigated. There are no patented mining claims or mineral leases in the study area.

Jan 1, 1987