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By G Anders

The effectiveness of two types of powder used in long-wall slashing was compared. The evaluation of the results can serve as a good example of how the application of statistical methods to underground test data can help to minimize the number of tests to be carried out. The conclusions are stated concisely, including a definite assessment of the reliability of the tests. Introduction AN assignment at the Algom Nordic mine called for a performance comparison between 70 per cent Cilgel B and 75 per cent Dygel in longwall stope slashing, particularly taking into account, in both cases, the build-up of bootlegs as dependent on hole deviation. Stopes were usually 8 to 10 ft. high and inclined at about 17 degrees. Starting from a raise, they were widened by consecutive longwall slashes to 60 ft., and, al-lowing for drift pillars, were approximately 300 ft. in length along the incline.

Jan 1, 1964

By Benjamin N. Webber

The peninsula of Nicoya contains virtually all of the known manganese deposits of Costa Rica. These are south and west of the Tempisque River, which flows across the peninsula near its juncture with the mainland. This peninsula forms the westernmost part of the province of Guana-caste, which is the northern. of the two Pacific Coast provinces of Costa Rica. The larger villages are connected by ox-cart roads and trails. The area may be covered on horseback without difficulty except during the rainy season, when rivers are in flood and difficult to ford. This is particularly true of the Rio Seco-Guay-jiniquil area, where there are no inhabitants and few open trails through the tropical jungle. Santa Cruz and Sardinal are served by the Taca Airlines, two planes a week from San Jose and Puntarenas. The port of Puntarenas has excellent loading facilities but none are available nearer the manganese districts; there ore must be lightered to vessels standing offshore. Physiography In Costa Rica there are three physiographic divisions: (I) the central plateau (Mesa Central), a somewhat dissected lava platform upon which are superimposed volcanic peaks, some of which are still active; (2) the Atlantic lowlands and (3) the Pacific lowlands. The peninsula of Nicoya and the larger part of the province of Guanacaste lie within the Pacific low- lands. The term "lowland" indicates relation to the central plateau, as the peninsula of Nicoya is largely mountainous. The mountains of Nicoya form the southern extremity of a range of low hills, which are almost continuous along the Costa Rican coast to the Nicaraguan border. The coast line shows evidence of subsidence. The Gulf of Nicoya obviously is the drowned valley of the Tempisque River. The west coast of Nicoya shows many rocks, shoals, bays, inlets and small islands as evidence of a sea encroachment. The altitude of the manganese deposits ranges from 0 to 800 ft. Topography is of the mature type of wide valleys and low hills, often with abrupt slopes. The climate is tropical and humid; rainfall of 125 in. falls largely between Sept. I and Jan. I. Vegetation often is very dense, the Rio Seco-Guayjiniquil area being truly tropical jungle, containing many hardwoods. History and Production The production of manganese ore in Costa Rica apparently dates from the first World War. It reached a peak of about 10,000 tons in the year 1919, then declined rapidly. Evidence of this period of prospecting has rotted away or been swallowed by the jungle. The war now in progress apparently revived the interest in Costa Rican manganese and has encouraged further prospecting. Deposits long known have been redenounced and trails have been cut through the jungle to them. Many new deposits have been discovered in the last

Jan 1, 1949

By F. W. Wood

Ingots of zirconium and other highly reactive metals such as titanium and hafnium produced by the consumable-electrode arc-melting process require conditioning before forging or rolling. A nondestructive, arc-conditioning technique has been developed as a substitute for lathe conditioning. The technique employs en electric arc under an inert atmosphere to fuse surface metal on the sidewalls of ingots without seriously affecting the general quality of the ingots. Advantages of the practice are Increased yields, lower accumulation of inferior scrap, and actual cost savings. The work cited in this report was done on zirconium. INTRODUCTION The consumable-electrode arc-melting process as practiced at the Bureau of Mines3 4/ has proved to be a technique for producing sound, homogeneous, commercial-size ingots of zirconium and its alloys. Ingots produced by this process, however, have as a characteristic a layer of partly fused metal on the sidewall to a depth of 3/16 to 3/8 inch. To prevent extension of surface imperfections during forging, the ingots are ordinarily conditioned by removing defective material in a lathe. If the metal were less reactive or the requirements less severe, the machine chips could be recycled and remelted. However, zirconium, being so oxygen sensitive, is contaminated by merely being machined despite extensive cooling of the tool bit. Further, being contaminated with oxygen, the chip metal upon remelting is 10 to 25 Brinell-hardnese numbers harder than the ingot from which it was machined. For this reason, the ingot specifications for naval reactor use have prohibited remelting machine chips, except as required for starting pads. Again, were zirconium less costly or less in demand this ever-increasing pile could be burned to oxide and recycled through the Kroll sponge process. Economics do not favor this, as melting feed stock has an estimated increase In value over oxide of about $8.80 per pound of contained zirconium. The efforts of the Bureau to solve the problem have been directed along two lines: To reduce the contamination of the machine chips produced and to reduce the quantity of the chips produced. This paper presents the technique developed to reduce the quantity of chips produced by arc-conditioning the remelted ingot.

Jan 1, 1955

Polyacrylamide flocculating agent has been used in the Leaching Division 'of the Risdon Works of the Electrolytic Zinc Company of Australasia Limited since October, 1960. The number of thickeners in the continuous thickening stage was thereby reduced from eight to three. There has been an increase of 25 per cent in throughput and a reduction of solids in thickener over-flow from 3-4 g/l. solids to 0·5 g Ir. solids. Reagent addition has been at the rate of 0·25 lb Separan NP10 per ton solids.Additionally there has been a gain of 3 per cent in current efficiency as the direct result of the addition of Separan NP10 to purified cadmium sulphate solution priOl; to electrolysis for cadmium metal. A smoother deposit has resulted and it has been possible to increase deposition time between strippings from 47 to 71 hr. However, there has been a slight increase in the lead content of the cadmium metal produced.The use of Separan NP10 to settle copper bearing residue in a batch process stage has resulted in a five-fold increase in settlement rate and a reduction in purification cycle time.INTRODUCTIONThe Electrolytic Zinc Company of Australasia Limited, Risdon, Tasmania, produces zinc by electrolysis of purified zinc sulphate solution, the raw material being zinc sulphide concentrate. In the Risdon process (Van Arsdale, 1953; J ohnstone, 1953; Ross, 1949) the compound zinc ferrite (ZnO.Fe203) is formed during the concentrate roasting stage. When the roasted material is leached in dilute sulphuric acid the zinc ferrite is not attacked, and it remains as part of the insoluble leach residue, of which it may form as much as two-thirds of the whole. The remainder is mainly unroasted zinc sulphide, unleached zinc oxide, lead sulphate, gypsum, silver compounds etc. The zinc in the residue may be 10 per cent of that in the original concentrate.Continuous thickeners are used to recover the valuable residue from the impure zinc sulphate solution and the...

Jan 1, 1963

By Margaret N. Maxey

For the past quarter century, it is fair to say that the political agenda of Western industrialized societies has been driven by those opposed to forms of economic growth providing sustenance to a growing population. They regard growth as the major threat to their social philosophy which champions a wholly "new ethic of biocentric equality" or "living as if Nature mattered." This ethic demands that "a violent, plundering humankind" must abandon its alleged rape of Planet Earth and derive its ethical norms from pre-existing harmonies and fragile, precarious balance present in Nature. A Green political agenda appeals strongly to deep longings shared among many people whose temperament seeks tranquillity in a world of wild natural beauty uncluttered by dependency on tools and experts and specialists. According to proponents of the Green philosophy, our world is pregnant with enormous problems. Armed with expanded political powers, regulatory guardians at state and local levels have mustered their forces with shotguns cocked, poised to prod an ignorant and lazy citizenry to the altar for an exchange of vows with Environmental Ethics. Social engineers have skillfully discredited the traditional role of professionals in scientific engineering who are summarily dismissed as the failed architects of an industrial system pillaging the earth. They stand accused of producing unmanageable offspring - from mining minerals and energy resources to disposing of toxic wastes - whose disputed parentage and expectant crimes against humanity must be prevented by removing them from normal custody. Green critics claim that markets cannot be given custody of industrial offspring - pollutants, wastes, land-use abuses. Markets appear to have failed to provide equity to present and future generations. The only custodian with sufficient coercive power seems to be the regulatory bureaucracy. The upshot is a stark Hobson's choice - Shotgun Wedding vs. Custody Dispute. It derives its fateful predestination from an uncritical acceptance of several preconceptions which currently undergird the altar of Sustainability characterized by its acolytes as "a new and exciting doctrine." It is significant that Limits to Growth slogans of the 1970s have been displaced in the 1990s by the more palatable language of Sustainability. As a policy recommended to forestall an impending doom, Sustainability derives its credibility from dire predictions of global warming, ozone depletion, acid rain and the like. The Rio Declaration announced to the world in June 1992 that, although energy is essential to human well-being, its production and consumption in wealthy industrialized nations is unsustainable. It called for a complete overhaul of energy systems with nothing short of a total replacement of fossil fuels, uranium fission reactors, and large hydroelectric projects by means of so-called renewable energy sources, augmented by coercive regulations to force conservation and limit consumption demands. The social and political consequences of such a sweeping

Jan 1, 1995

By N. Haghdadi, D. M. Maijer, A. B. Phillion

B206 is a recently-developed high-strength Al-Cu casting alloy with reduced Ti and Fe, as compared to the well-known AA 206 alloy, for improved hot tearing resistance. In the current study, the solidification kinetics of this alloy as a function of cooling rate from 1 to 15 K/min were studied using differential scanning calorimetry (DSC) and microscopy. Specifically, the evolution in fraction solid, grain size, and secondary dendrite arm spacing have been characterized. The DSC results show the occurrence of three peaks during cooling from the liquid state, which are related to the formation of primary aluminum, a pre-eutectic intermetallic, and the eutectic phases. Thermal analysis also indicates that while the liquidus temperature is not sensitive to the cooling rate, the temperatures at which the pre-eutectic and eutectic phases form are strongly coupled to the rate of heat extraction. A decrease in the latter temperatures was observed when the rate of solidification was increased, leading to a lengthening of the freezing range of the primary phase. The results will be useful for improving B206 casting processes, specifically through modification of mould cooling conditions.

Jan 1, 2014

By G. Ozbayoglu, Z. Ozdemir

Turkey is the main boron minerals producing country in the world. The most important boron minerals are tincal, colemanite and ulexite. All mining, beneficiation and handling operations generate fines which cause ecological and economical problems. Utilization of this accumulated material requires both upgrading and agglomeration. The aim of this research was to exploit the ulexite fines by improving their grade and size. Attrition-scrubbing followed by washing and screening was employed for upgrading the fines. It was found that the grade can be increased from 23-25% B2O3 to 29% B2O3 with 73% recovery. Briquetting was applied as the size enlargement process. During the briquetting, the effect of moisture content, pressure, amount and type of binder, and drying on the quality of briquettes were investigated. The tests showed the possibility of production of strong briquettes by adding water alone, but the briquettes had no resistance to abrasion and water. Binders, namely boric acid and borax have been added to improve the properties of briquettes. The results showed that the compressive strengths and abrasive resistances of briquettes obtained with both binders were acceptable. However, the briquettes have no water resistance properties.

Jan 1, 2004

By Jim Baumann

Deposited millions of years ago in irregular paleokarstic channels, Jamaica’s extensive bauxite deposits provide good quality ore for alumina production and subsequent aluminum smelting. Bauxite mining operations are critical to the Jamaican economy. It accounts for a large percentage of Jamaica’s export earnings. Bauxite production in Jamaica accounts for about 10% of the world’s output each year. Bauxite deposits in Jamaica lie close to the surface. They can be extracted using standard surface mining techniques. The deposits occur in scattered pockets across the country’s rugged landscape. So it was necessary for two of the country’s major mining and refining operations to implement cost effective methods for the acquisition and management of bauxite reserves and surface ownership distribution rights.

Jan 1, 2002

By Charles L. Karr

Researchers at the University of Alabama in cooperation with the U.S. Bureau of Mines have developed adaptive process control systems in which genetic algorithms (GAS) are used to augment fuzzy logic controllers (FLCs). GAS are search algorithms that rapidly locate near-optimum solutions to a wide spectrum of problems by mimicking the search procedures of natural genetics. FLCs are rule based systems that efficiently manipulate a problem environment by modeling the "rule-of-thumb" strategy used in human decision making. GAS and FLCs can be combined to produce powerful, efficient, and robust adaptive control systems. To perform efficiently, such control systems require a control element to manipulate the problem environment, an analysis element to recognize changes in the problem environment, and a learning element to adjust to the changes in the problem environment. I" this paper, the details of an ongoing research effort to develop and implement an adaptive process control system for a column flotation unit are discussed.

Jan 1, 1996

By Bidjan Ghahreman

A total of 120 micropiles were constructed for foundations of a new selective catalytic reduction (SCR) unit in a coal-fired power plant east of Kansas City, Missouri. Construction was performed under restricted overhead conditions because of the existing facilities. The subsurface profile included about 70 feet of overburden composed of granular fill, stiff to very stiff cohesive material, medium dense sand, and very dense gravel. The bedrock was composed of alternating layers of shale and claystone (weak rock) and limestone (strong rock). It was decided that the bond zone would be entirely in the bedrock. The design rock profile along the bond zone was composed of 10 feet of shale and claystone underlain by 10 feet of limestone, which in turn was underlain by shale and claystone. To achieve the design compression and uplift capacities of 100 tons and 60 tons, respectively, a length of 23 feet was determined for the bond zone. Compression and uplift load tests were performed to verify the design. IBC-2000 elastic line, Decourt (1999) extrapolation, and Chin-Kondner extrapolation were used to interpret the load test results. The interpretation of load test data indicated that both compression and uplift capacities far exceeded the respective design loads. Spring constants of 397 tons per inch (T/in.) (in compression) and 290 T/in. (in uplift) were estimated from load tests at respective design loads. During the compression load test, no sign of creep was observed after the applied load was maintained at the design load (100 tons) for two hours.

Jan 1, 2009

By Mitsuru Tanahashi

In order to develop an effective process for the production of from metallurgical-grade one (MG-Si), the oxidation removal of boron from molten MG-Si was investigated at a solar-grade silicon (SOG-Si) 1773K by the following two CaO-saturated CaO-CaF2 flux treatment processes. I) Boron removal by flux addition onto the molten M6-8 followed by oxygen gas injection into the melt (Two-stage connecting process). II) Boron removal by simultaneous injection of flux powders and oxygen gas into the molten MG-Si (Simultaneous injection process). These processes can establish the special condition of both high basicity of the flux and the high oxygen partial pressure at the boron removal reaction sites. Through these processes, especially by the simultaneous injection Process using a flux powder injection equipment, the boron content in MG-Si can be efficiently reduced. The obtained results clarified that both processes should be conducted for a time period as short as possible by using as much flux as possible. By repeating the simultaneous injection process for 60 s three times under the optimum operating conditions determined in the present study, the boron content in MG-Si can be reduced from 14 to 4.7 mass ppm.

Jan 1, 2003

By Catherine Aimone-Martin, Mary-Alena Martell

Whole-structure and mid-wall responses of 33 non-traditional structures to surface coal mine blasting were characterized. Eighty-nine blasts were conducted at 11 mine sites throughout the U.S. to measure blastgenerated dynamic response of structures typically found in the proximity of surface coal mining. Structures selected for this study include log-type, manufactured (single- and double-wide trailers), “mine camp”-type, adobe, and stone. Traditional acoustic microphones, t&axial (ground) and single component (structure) velocity transducers were used to record airblast, ground motions, and structures response time histories with a common time base. Wall crack displacement gages were used to record static and dynamic movement of existing drywall cracks. The relative responses of selected “atypical” structures to blast vibrations and nonblasting causes of structural stress, including natural forces, environmental effects, and human habitation, are compared. The purpose of this study is to document and compare vibration characteristics of structures that were not included in previous studies conducted by the U.S. Bureau of Mines and others in establishing the widely adopted safe level blast vibration criteria in the U.S. An important objective of this study is to outline an evaluation process including structure uniqueness relative to cracking susceptibility.

Jan 1, 2002

By Eva B. Kisvarsanyi

An Early Proterozoic orogenic terrane of metasedimentary and metaigneous rocks underlies Nebraska, Kansas, and Missouri. Middle Proterozoic epizonal terranes of anorogenic granite and rhyolite, a known metallogenic province partly exposed in southeastern Missouri, overlap the orogenic terrane on the south. These Proterozoic terranes, covered by less than 1,000 meters of Phanerozoic strata, contain a virtually untapped source of mineral wealth and are one of the last frontiers for geologic exploration in the continen-tal United States. Petrographic study of subsurface samples is a powerful tool in the identification of favorable host rocks for a variety of ore deposits.

Jan 1, 1987

By A. E. J. Engel

INDUSTRIAL talcs and ground soapstones both include earth materials of different chemical and mineral compositions. In general, the industrial talcs are composed of silicates that contain appreciable amounts of magnesia. Generally talc, the mineral, is a predominant or at least common constituent. Talc, the mineral, is a hydrous magnesium silicate, with a suggested theoretical formula H2Mg3 (SiO3)4 or H2O.3MgO.4SiO2, which postulates 63.5 pct SiO2, 31.7 pct MgO, and 4.8 pct H20.11 Actually different single grains or leaves of pure talc have variations in water content ranging from 3.5 pct to more than 7 pct, as well as slight differences in the proportions of MgO and Si02.16 Only a very small percentage of the ground industrial talcs produced in the United States approaches the composition given above (see Table 1). The purer talcs invariably occur as alteration products of magnesium carbonate rocks. Some of these relatively pure talcs include compact, massive types largely mined in California, which are designated as steatite.38,58 In general, steatites cannot contain in excess of 1.5 pct CaO, 1.5 pct combined FeO and Fe203, and 4 pct A1203. The less pure varieties of massive talc and mixtures of magnesian silicates are commonly called soapstones, or merely talc. Many industrial earth products classified as talc or as soapstone contain a variety of minerals, especially serpentine (H4Mg,Si2O9), chlorites (hydrous magnesium, iron, aluminum silicates), tremolite (Ca2Mg5H2[SiO3]8), anthophyllite ([MgCa]SiO3), diopside (CaMg[SiO3]2), and quartz (SiO2). The carbonates calcite (CaC03), dolomite (CaMg[CO3]2), and magnesite (MgCO3) are also present in some industrial talcs and soapstones. Some of these minerals, as well as sulphides, sulphates, and iron and manganese oxides, if present at all or in excess of minute amounts, may alter the composition of the industrial talc sufficiently to restrict materially its use or to lower or destroy its value. These factors are discussed in a subsequent section of this chapter.

Jan 1, 1949

By C Menzies

Hydraulic Monitor mining at Solid EnergyÆs Spring Creek Mine has proven to be a safe and effective method of extracting steeply dipping thick seams at production capabilities approaching one million tonnes per annum.   This paper traces the development of Hydraulic Monitor mining from its initial introduction into old workings at Strongman Mine, its refinement at Strongman 2 in shallow, thick and steep workings, through to its introduction into the deep, very thick seams at Spring Creek Mine. This last step of the progression came with all the added complications that come with depth, particularly flammable gas.   This paper will describe the various changes in mining conditions that dictated the performance of the monitor, how the mine layouts were changed to adapt, and the various operational systems that were put in place, to allow a safe and productive operation.

Jan 1, 2007

By C. Slotta, F. Charlier, P. Blomen

"Within the energy concept of the German government, the operating time of nuclear power plants was initially extended from about 8 to 14 years. It is planned, however, that every power plant will gradually be decommissioned until 2025 and that simultaneously the amount of renewable energies will successively be expanded. According to the political state, nuclear energy is a discontinued model. Looking at the global energy market, though, an obviously opposed development can be observed. At the moment, 443 nuclear power plants are running worldwide and further 62 facilities are being built. These about 500 nuclear power stations have to be supplied with nuclear fuel right now and in the future. The present paper will describe the worldwide use of nuclear energy, the extraction of the nuclear fuel uranium and in detail the available and predicted resources of uranium. The conclusion of the paper is the statement that uranium as nuclear fuel is no scarce resource but sufficiently available."

Jan 1, 2011

By Ralph D. Gift

This report describes a program of research to evaluate methanometry in coal mines. The program commenced by conducting an extensive state-of-the-art survey. Details of the survey are presented which includes a rating of various types of instruments that can be used to detect and record methane gas. Laboratory test data, on mine instruments tested are presented together with results from a computerized statistical analysts.

Jan 1, 1972

By S. F. Ravitz

IN his excellent book on the Principles of Flotation, Wark1 makes the following sig-nificant statement concerning the theory of flotation: Two questions of first-rate importance must be considered . . . First, it must be decided whether the sulfide minerals require a collector in order that they may float, or whether as has been claimed, they possess an inherent float-ability and need no collector. Second, it must be decided whether the xanthate type of col-lector can react with or be adsorbed by the unchanged sulfide minerals themselves, or whether, as many claim, reaction with the collector is dependent upon initial oxidation of the mineral surface. In the theory of flotation there are no two questions of greater impor-tance than these. Ravitz and Porter2 presented evidence that galena can be floated without a col-lector, and even without any reagent, pro-vided oxidation products are thoroughly removed from its surface. They found also that thoroughly cleaned galena floated faster when xanthate was used than when a frother alone or no reagent was used, and that, without a collector, the recovery decreased gradually upon exposure of the mineral to air. Their work, however, has met with considerable criticism. 1(127),3-6 This paper is presented to answer the objections that have been raised, and to present additional data that confirm their results.

Jan 1, 1940

UNIVERSITY OF ALABAMA University, Ala. MINING AND METALLURGICAL SOCIETY James W Stewart UNIVERSITY OF ALASKA College, Alaska MINING SOCIETY OF THE UNIVERSITY OF ALASKA Guinn Metzger UNIVERSITY OF ARIZONA Tucson, Ariz. MINERS, SOCIETY H. Krumlauf

Jan 1, 1951

By R. Vasant Kumar

Measurement and control of trace elements in molten metal are often critical in order to achieve optimum production, refining, alloying or recycling. Solid electrolyte sensors for monitoring oxygen and very recently for hydrogen have made major impact in the metal industry. It has not proved straightforward to develop solid electrolyte sensors for many other elements that can be industrially applied in metal production. Novel self-tuning chemical sensors have been developed by the authors that may open up new technological opportunities. Three such examples will be presented in this paper: (i) a self-selecting oxygen-sulfur dual sensor using a composite beta-alumina/zirconia solid electrolyte; (ii) a copper sensor for liquid matte based upon cusicon solid electrolyte operating in a current reversal mode; and (iii) an aluminium sensor on solid NaCl containing channels of molten NaAlCl4 electrolyte formed by electrochemical charging in molten zinc.

Jan 1, 2006