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By Tiziana Apuani

The study refers to an area of about 70 km2, extended in the Italian Central Alps along the the San Giacomo Valley where different civil and mining works are present The regional geological setting is related to the Pennidic Nappe arrangement, characterized by the emplacement of sub-horizontal gneissic bodies resulting from the Mesoalpine isoclinalic folding of crystalline basements, emplaced throw East, and separated by matasedimentary cover units. The investigated geological rocks, belong to the ?Tambò?Unit, overlapped by its meta-sedimentary cover and by the ?Suretta? Unit. The tectonic contact gently dips to the E?NE. The valley, furrowed by the Liro Torrent, follows a N?S striking tectonic lineament, almost parallel to the nappe contact. A number of more then 70 sites, distributed in the studied area, were chosen and detailed structural and geomechanical field surveys were performed to characterize the rock masses, its intact rock and discontinuities. The procedure identifies the number of joint sets, their representative orientation, the set spacing, the type of movement, the amount of dilatation, the degree of alteration, the roughness coefficient, the presence and nature of infill. Rock mass quality indexes, such as the Rock Mass Rating (Bieniawski, 1989) or the Geological Strength Index (Hoek et al. 2002) have been evaluated in each surveyed site. The work is a contribute in assessing how the geometrical and geomechanical properties of the rock masses can be regarded as regionalized variables. The spatial distribution of these properties is a function of the geological and structural phenomena at which the rock masses have been subjected. The presented geostatistical analysis regards the spatial variation of the orientation of the most representative joint set.

May 1, 2009

By H. R. Thresh

An oscillational vis cometer has been constructed to measure the viscosity of liquid metals and alloys to 800°C. An enclosed cylindrical interface surrounds the molten sample avoiding the free surface condition found in many previous measurements. Standardization of the apparatus with mercury has verified the use of Roscoe's formula in the calculation of the viscosity. Operation of the apparatus at higher temperatures was also checked using molten lead. Extensive measurements on five different samples of zinc, of not less than 99.99 pct purity, indicate i) impurities at this level do not influence the viscosity and ii) the apparatus is capable of giving reproducible data. The variation of the viscosity ? with absolute temperature T is adequately expressed by Andrade's exponential relationship ?V1/3 = AeC/VT , where A and C are constants and V is the specific volume of the liquid. The values of A and C are given as 2.485 x 10-3 and 20.78, 2.444 x 10-3 and 88.79, and 2.169 x 10-3 and 239.8, respectively, for mercury, lead, and zinc. The error of measurement is assessed to be about 1 pct. Prefreezing phenomena in the vicinity of the freezing point of the zinc samples were found to be absent. AS part of an over-all program of research on various phases of melting and casting nonferrous alloys, a systematic study of some physical properties of liquid metals and their alloys was undertaken in the laboratories of the Physical Metallurgy Division.1,2,3 The most recent phase of this work, on zinc and some zinc-base alloys, was carried out in cooperation with the Canadian Zinc and Lead Research Committee and the International Lead-Zinc Research Organization. One of the properties investigated was viscosity and the present paper gives results on pure zinc; the second part, on the viscosity of some zinc alloys, will be reported separately. Experimental interest in the viscosity of liquid metals has virtually been confined to the past 40 years. The capillary technique was already established as the primary method for the viscosity of fluids in the vicinity of room temperature; all relevant experimental corrections were known and an absolute accuracy of 1 to 2 pct was possible. Ap- plication of the capillary method to liquid metals creates a number of exacting requirements to manipulate a smooth flow of highly reactive liquid through a fine-bore tube. Consequently, the degree of precision usually achieved in the high-temperature field rarely compares with measurements on aqueous fluids near room temperature. However, the full potential of the capillary method has yet to be explored using modern experimental techniques. As an alternative, many investigators in this field have preferred to select the oscillational method. Unfortunately, the practical advantages are somewhat offset by the inability of the hydrodynamic theory to realize a rational working formula for the calculation of the viscosity. In attempting to overcome this restriction many investigators have employed calibrational procedures, even to the extent of selecting an arbitrary formula for use with a given shaped interface. However, where calibration cannot be founded on well-established techniques, the contribution of such experiments to the general field of viscometry is questionable. A critical appraisal of the viscosity data existing for pure liquid metals reveals a somewhat discordant situation where considerable effort is still required to establish reproducible and reliable values for the low-melting point metals. The means of rectifying this situation have gradually evolved in recent years. Here, the theory of the oscillational method has undergone major advances for both the spherical and cylindrical interfaces. The basic concepts of verschaffelt4 governing the oscillation of a solid sphere in an infinite liquid have been adequately expressed by Andrade and his coworkers.5,6 Employing a hollow spherical container and a formula, which had been extensively verified by experiments on water, absolute measurements on the liquid alkali metals were obtained. The extension of this approach to the more common liquid metals has been demonstrated by culpin7 and Rothwel18 where much ingenuity was used to surmount the problem of loading the sample into the delicate sphere. Because of the elegant technique required to construct a hollow sphere, the cylindrical interface holds recognition as virtually the ideal shape. On the other hand, loss of symmetry in one plane increases the complexity of deriving a calculation of the viscosity. The contributions of Hopkins and Toye9 and Roscoe10 have markedly improved the potential use of the cylindrical interface in liquid-metal viscometry. The relatively simple experi-

Jan 1, 1965

By Z. D’Amico

"IntroductionWE HAVE HEARD quite a lot recently on newer methods -of supporting roof, such as roof bolting or the use of metal props and •booms, but, with the exception of roof bolting, these methods are confined mostly to comparatively low, regular seams and even .bolting cannot be used to hold soft sides. Thus, where a seam of coal has great variations in thickness, or where it is faulty, or where the coal sides must be supported, nothing can wholly take the place of timbering with wood. This paper will deal mainly with the method of timbering such a seam, namely, the No. 3 seam mined by Brazeau Collieries, Limited, at Nordegg, Alberta, where the full height of a thick seam is mined in development. However, a few words on one or two other systems practised in Alberta when, in development work, a thick seam is only partially mined, should be of interest.Examples of Timbering in High SeamsThere .are several methods in use today for dealing with high seams of coal. The most popular is to develop the seam by driving road-ways in the coal by some conventional method, usually recovering the full thickness of the seam on the retreat. The following examples illustrate two variations of this method.In Figure I we have a thick •seam of friable coal, with a good roof, pitching about 30 degrees, which is being mined by taking the upper part of the seam in the development work, leaving the •bench coal in place. Figure 1A shows a section through a room."

Jan 1, 1954

By H. Lawrence

In 1977, the Bureau of Mines awarded a grant to the State of South Carolina to explore the possibility of using Landsat multispectral scanner (MSS) data as an aid in monitoring surface mining activities in selected counties of the State. Work had been done in Aiken County prior to the grant by Bureau of Mines and State personnel at the EROS Data Center using both the GE Image 100 and ESL IDIMS systems. The initial work on the 1-100 consisted of locating and measuring the areas of various kaolin mines. The results were excellent on location, identification, and accurate area measurements of several mines as compared with aerial photos of each mine. The effort also included locating and measuring the size of all mines (including sand and gravel) within two U.S. Geological Survey (USGS) 7 ½ min quadrangle maps. Line printer overlays using the IDIMS equipment and software resulted in the location of all known mines within an estimated error less than ±91.4m (5300 feet). Mine acreage was calculated by counting each symbol (which represented one pixel) and multiplying by 1.1 (the number of acres per pixel). Figure 1 shows a portion of one quadrangle overlay. Table I gives a comparison of acreage measured for sever- al mines from the 1-100 and IDIMS systems vs. aerial photo measurements.

Jan 1, 1979

By Basil B. Zavoico

ALTHOUGH the American petroleum industry was affected by the Second World War from its early beginning it was not until Dec. 7, 1941- that the industry was placed on full war footing. Even throughout most of 1942 the American overseas operations were limited and not until late in the year did expansion of military activities, more particularly the offensive in North Africa, affect the domestic supplies to such an extent that critical deficiencies developed locally in this country, particularly along the East Coast. The definite outlook for greatly expanded offensive operations by the United States on both Atlantic and Pacific fronts makes certain that during 1943 the domestic situation will. not be alleviated; rather it may become even more critical even though additional transportation facilities, now being built and planned. will be completed from the southwestern producing states to the East Coast.

Jan 1, 1943

By De-wen He

The distribution of persistent organic pollutants in the environment is studied using the multimedia environmental fugacity model, and environmental health risk assessment of POPs nearby a copper smelt enterprise is carried out. The result indicates that all are in an agreeable risk level without exception. The annual individual chronic risk index of HCB is 7.50×10-11. The annual individual risk index of 3,3',4,4'-TCB is 1.57×10-9, and the annual individual risk index of 2,3,7,8-TCDD is 6.57×10-9.

Jan 1, 2009

By Gerrit V. R. Goodman, Charles D. Taylor

A technique was developed to determine the fraction of air recirculated from the scrubber exhaust toward the face and the fraction of gas captured by the scrubber. To determine these two values, a series of tests was required. In the first test, gas was released at the face area and concentrations measured at the scrubber exhaust. In the second test, gas was released directly into the scrubber with concentrations again measured in the scrubber exhaust. The simultaneous solution of two independent flow expressions gave values of recirculation and scrubber capture. A series of tests was conducted with various combinations of scrubber flow, curtain flow, setback distance, and machine location. Statistical analyses then were conducted to determine those factors which influenced the levels of scrubber recirculation and scrubber capture in a deep cut. INTRODUCTION As cutting depths increase, the trend is toward the use of blowing face ventilation systems. With these ventilation systems, the potential exists for recirculation between the scrubber exhaust and the intake air stream. One concern is that methane gas, having been removed from the face area, is subsequently recirculated back into the intake airflow. Under these conditions, methane-laden air could be substituted for fresh intake air, leading to increased methane concentrations at the face. There is currently no standard for recirculation between the scrubber and intake airflows. The implied understanding of the Mine Safety and Health Administration (MSHA) is, and has always been, that any recirculation of ventilation air is unacceptable. To minimize recirculation potential, MSHA suggests that operators maintain scrubber and curtain flows within 0.47 m3/sec (1000 cfm) of each other. Given that recirculation may occur in some circumstances, the question arises as to how much recirculation constitutes a hazard for the face workers. Unfortunately, there is currently insufficient information to answer this. Emphasis must instead be placed on means to quantify the amount of recirculation between the scrubber and face area. Methods must also be examined to control this phenomenon. This paper presents a technique for quantifying recirculation and scrubber capture levels in a blowing face ventilation system. Several ventilation parameters are investigated to determine their effects on these levels. DEVELOPMENT OF RECIRCULATION EXPRESSIONS One way to measure airflow quantities at a point near the face would be to measure the gas flow rate Qgas, and gas concentration c at that location. The airflow Qair, would be simply the ratio of these two values, Qair, = Qgas/c. Although gas concentration values, c, can be obtained easily with existing gas monitoring equipment, it is more difficult to obtain gas flow readings, Qgas, at specific locations. To obtain these values of Qgas, another method was needed. Previous work in this area was conducted by Kissell and Bielicki (1975). However, the calculations in their model assumed a constant gas concentration in the region around the continuous miner. In a deep cut, it is questionable that gas concentrations would remain constant or uniform around the mining machine. The technique presented here does not rely on this assumption. It instead assumes that the gas concentration in the scrubber exhaust remains constant. A quantity of gas released at the cutting face either flows into the scrubber inlets or bypasses the inlets and flows around the off-curtain side (in this example, the right side) of the continuous miner (Figure 1). The fraction of the face gas that flows

Jan 1, 1993

By W. C. Holliman

This report on the characteristics of commercial aviation gasolines is one of a series of such reports. It presents compilations of' inspection data furnished on their products by 15 manufacturers of commercial grades of aviation gasoline and special data obtained in Bureau of Mines laboratories on 68 samples of these gasolines. Data are presented for 18 samples of grade 80, 20 of grade 91/98, 21 of grade100/130, and 9 of grade 115/145 aviation fuels. The gasolines are designated January 1948 production, although some of the samples actually were produced at a later date.

Jan 1, 1948

By B. Orgilbayar, B. Unursaikhan, S. Sukhbat, Ts. Zagarzusem, D. Baasanjav, L. Jargalsaikhan, E. Otgonjargal, N. Sugir-Erdene, Ts. Soyolmaa

This study has investigated the efficacy of the gravity beneficiation method based on gravitation and centrifugal forces for manganese ore. Powdered samples of manganese ores from the Unagad deposit in Mongolia were analysed for their element and mineralogical composition using ICP-MS and X-ray powder diffraction (XRD). The analysis presented the mineralogical compositions of the ores as hydro goethite, manganese minerals and magnetite, gangue minerals as quartz, albite, orthoclase and microcline of manganese ore. Manganese minerals are white in colour and have micro-veinlet, fine grained-aggregates associated with gangue minerals. The most important manganese minerals are hausmannite, pyrolusite, rhodochrosite, and manganosite. The composite of feed containing 17.31 % Mn and 36.3 % SiO2 was processed in a shaking table. In the experiment, a concentrate assaying 41.37% Mn was obtained from this composite with 65% recovery. In another experiment, f80=0.074 mm particle size ore was used in the MGS concentration test. A concentrate containing 38.34 % Mn with 75.2% recovery was produced in this experiment. The results showed that it is possible to obtain concentrate through gravity processing of manganese ore, which is an economically beneficial process for producing a product of a standard requirement. Keywords: Manganese ore, gravity separator, centrifuge, shaking table 1. Introduction

Jan 1, 2020

By J. C. Bradley

THE relation of annealing temperature to conductivity of copper wire has been determined.1 Conductivity hard was 98.26 per cent. After a 10-min. heating at 200° C. it was 98.69. By annealing 10 min. at 300° C. a large increase, to 100.93, occurred. Maximum conductivity, 101.15, was attained after a 500° C. anneal; thereafter it decreased to 100.53 after a 950° C. anneal. If copper is gassed the decrease is much more than this. MATERIAL AND METHOD The work was done on high grade electrolytic copper, 99.942 per cent. copper-plus silver, silver 0.0008 per cent. It was hot-rolled to 3 in., then cold drawn to 0.080 in. The wire was cut into 25 5-ft. lengths and numbered 1 to 25 as cut. Four samples were tested hard. The others were wound into 5-in. diameter coils. For the 100° C. heating a coil was put into water, the water brought to boiling, and the wire kept at this temperature for 10 min. For the higher temperatures the coils were placed in envelopes of sheet copper, a little water added, and the envelopes sealed by folding over the edges twice, and hammering them together. This kept the air out very well. The envelope and wire were brought to the desired temperature; this was maintained for 10 min., then the whole was water-quenched.

Jan 1, 1927

By R. G. Jones

Chris Hinde talks us through his career from BSc in Mining Engineering to roles with Golder Associates, Schroder Securities, Mining Journal and SNL. He discusses the issues facing the mining industry.

May 1, 2015

By Pramila Misra, Jibardhan Meher, Debadutta Das

The concentrated coal-water slurry has been receiving considerable attention recently due its ability to replace fossil fuels. Attainment of stable and concentrated slurry has been succeeded so far through several physical and chemical techniques. The present article reports the formulation and stabilization of a highly concentrated coal-water slurry formed from five varieties of non-coking coals with variable ash contents obtained from Eastern part of India, employing three varieties of starch esters, such as starch benzoate, starch formate, and starch carbamate as dispersant. The apparent viscosity of the modified coal-water slurry has been measured by varying coal loading, dispersant percentage, pH, temperature, etc. The apparent viscosity of the slurry has been found to be decreased substantially on addition of 0.8% of adsorbate in the slurry. The particle-particle interaction has been considerably decreased and stable concentrated coal-water slurry containing high weight fraction of coal (61.5-63.5%) has been achieved in each case. The slurries stay in a non-settling form for about a month with viscosity in a permissible low range. The coal-water slurry has been found to behave as a non-Newtonian liquid. Comparison of the zeta potentials of the naked and modified coals evidences that adsorption of the dispersants at coal-water interface results in inhibition of the agglomeration of coal particles through mostly steric repulsions.

Jan 1, 2014

By Charles C. Boley

High-volatile A bituminous coal from the Allen mine, Las Animas County, Colo., blended with char produced from the same coal yielded accept-able metallurgical coke in a 500-lb movable-wall test oven. Nineteen experimental runs were carried out using several concentration levels of two different chars, 5.6 and 19.6 percent volatile matter, produced by entrainment carbonization of the base coal. With the higher-volatile char, an acceptable coke was produced at a 22.5-percent concentration; the lower-volatile char did not produce an acceptable coke at the concentrations investigated.

Jan 1, 1972

By Joseph W. Town

The Bureau of Mines conducted studies related to SO2 air pollution to determine attritioning rates, SO2 sorption rates, and sulfur loads that could be obtained on commercial alkalized alumina sorbent pellets. Fluidized-bed attritioning rates ranged from 0.025 pct/hr for alkalized alumina with a crushing strength of 4 kg to 0.075 pct/hr for 0.5 kg crushing strength mate¬rial. Airlift attritioning rates ranged from 0.50 pct/hr for 3 kg crushing strength alkalized alumina to about 3 pct/hr for 0.5 kg material. Attritioning rates for the commercial alkalized alumina were comparable to those obtained for sorbent pellets prepared in the Bureau of Mines laboratory. Sorption rates were related to S02 concentration in flue gas, temperature, and presence of nitrogen oxides in the gas stream. Sorption rates at 300° C were 0.35 X 10-6 gS/gp/sec (grams sulfur per gram pellet per second) in 0.045 pct so, gas, 5.1 x 10-5 gS/gp/sec in 0.34 pct SO2 gas, and 65 X 10-5 gS/gp/sec in 10 pct SO2 gas. For the 0.34 pct S02 gas, sulfur loads of 0.10 gS/gp (the projected load for regeneration) were obtained in 47 min at 130° C and in 116 min at 300° C. The presence of either NO or NO2 in the 0.34 pet S02 gas increased the SO2 sorption rates 2 to 3 times at 300° C, but had no effect at 130° C.

Jan 1, 1969

By C. Cristoffanini

A real-time transient pipeline simulation was used to model the operational pressure response in the concentrate and tailings pipelines of the Minera Los Pelambres copper mine in Chile. A high-fidelity simulator was needed to train the operators on safe operation of the pipeline for different scenarios. A simulator that solves the transient equations was used to dynamically predict the pressure and flow throughout the pipeline to provide real-time responses to operational changes such as opening or closing a choke valve, or sending a water batch. Slurry rheological properties were incorporated into the model. This paper presents the technical background of the pipeline simulation model and the study of slurry properties. The paper shows the results of the transient simulation for different operating scenarios such as start-up, shutdown and leakage, by presenting the hydraulic gradient curves for each case. Finally, the paper briefly presents how the simulator was connected to an emulated control system and used to train the operator, it demonstrates the most effective tool available to learn to resolve undesirable conditions.

Feb 23, 2014

By John C. Kleiber, George M. Meisel

From time to time since the initial installation of an experimental flotation section in 1940, Permanente Cement Co. has made efforts to beneficiate the low-grade limestone fraction which occurs in its deposits at Permanente, Calif. The encouraging results outlined in this article are the result of Permanente's latest effort. THE PERMANENTE LIMESTONE AND THE REASON FOR ITS BENEFICIATION The Permanente deposit is a sheet of Calera limestone over 700 ft thick lying within the Franciscan sediments of the San Francisco peninsula. Limestone suitable for cement manufacture underlies, overlies, and is interbedded with low-grade limestone and chert. Andesite intrusions are found as a secondary gangue. The limestone is identified as follows:

Jan 3, 1964

By William D. Meakins

INTRODUCTION Today, auxiliary fans, or boosters as they are sometimes called, are commonly used underground to provide ventilation for safe working conditions for personnel. Fans are installed in many ways and for many purposes; however, their use falls into three main categories depending upon the application. Auxiliary Face Ventilation For Coal Mines Usually the application of auxiliary fans underground in coal mines presents problems not normally encountered in other types of mining. Two of the major problems deal with liberation of methane at the coal face and the production of coal dust in the mining process. For these conditions it is necessary to use permissible (explosion-proof) type of equipment. As a result, these fans are discussed in a category by themselves. Auxiliary Fans For Tunnel and Drift Ventilation Tunnels and drifts present unique ventilation requirements. For instance, tunnels and drifts can be developed for considerable distances into virgin territory. Since they are generally dead-ended, the only way to obtain ventilation at the face is to use ventilation pipe to establish one leg of a ventilation circuit. The ventilation of tunnels and drifts therefore falls into another natural category. Other Uses of Auxiliary Fans For Mining Purposes Fans can be applied to mining applications in many ways other than those discussed under the other two categories. For example, many times auxiliary fans can do a much more practical job of proper air control and distribution that can be achieved with any other mechanical means; therefore, these other uses are discussed as a special category. AUXILIARY FACE VENTILATION FOR COAL MINES After 1936, federal and state coal mining laws prohibited the use of auxiliary underground fans in coal mines since such equipment had been widely misused. In certain cases, recirculation of face air had been allowed to occur thereby creating a serious potential explosive hazard by the possible buildup of excessive methane concentrations. By the late 1950s, mining machines with rapid face penetration were commonly being used in coal seams which liberated higher quantities of methane than in earlier years. As a consequence, in the late 1950s and early 1960s, the use of auxiliary face fans was again allowed under strict experimental conditions because conventional methods of face ventilation control without fans were becoming inadequate. Today, auxiliary face fans are widely used under strict federal and state control. Such auxiliary ventilation does not reduce the need for the amount of primary air from the main mine fans; however, it does help to distribute primary air more efficiently at the face. The present trend is toward an exhaust system of ventilation utilizing 406- to 610-mm (16- to 24-in.) diam tubing extending from the face to an outby auxiliary fan. Since the tubing is normally applied with negative pressure, spiral wire reinforced tubing has been replaced largely with metal and, more commonly, fiberglass tub¬ing. Additional auxiliary blower units are often used at the mouth of the room being developed, or installed on the miner or loader near the face, depending upon the amount of gas liberation present. Often one (or more) of the fan units is equipped with an integrally mounted hopper and feeder which automatically adds a continuously metered amount of rock dust to the exhaust air. The combination unit tends to make the mixture of discharge particles noncombustible and reduces to some extent the need for additional rock dusting of return airways. In this part of the chapter, typical auxiliary ventilation systems are described including curves and photograph of typical/applicable equipment. Reference will be made to "blowers" and "ex¬hausters." Both are fans and are basically the same units. They take on their name through the manner in which they are used. A blower usually has an inlet bell on the inlet side to help to obtain good air flow into the blades. An exhauster often has a discharge cone added to reduce the discharge loss. Any basic fan unit can be used either as a blower or an exhauster. Description of Auxiliary Ventilation Systems Several auxiliary ventilation systems and modifications of basic systems have evolved over recent years. Some of these systems are described and illustrated. System No. 1, an exhaust system for faces with comparatively low gas liberation, is shown in Fig. 1. Here

Jan 1, 1982

By Shin-ya Kitamura

Kinetic modeling is very important to understand steelmaking reactions. The coupled reaction model proposed by Prof. D.G.C Robertson is the best suited program, and therefore, the author has applied it to the various steelmaking reactions, a few examples of which are discussed. Hot metal dephosphorization occurs under non-equilibrium conditions as it takes place between the slag, which has a high oxygen potential, and the hot metal, which has a low oxygen potential. A process simulation model based on the coupled reaction model was constructed. This model considers the solid and liquid slag, liquid metal phases, and the reaction between the solid and liquid slag, besides the reaction between the liquid slag and liquid metal. Using this model, the ruling factor to increase the reaction efficiency of dephosphorization has been verified. In the secondary refining process, the values of inclusion composition calculated by the thermodynamic model, under the assumption of equilibrium with the metal composition, were found to be different from those observed in practice. A kinetic model, incorporating the reactions between slag, metal, inclusion, and refractory has been postulated, and the composition change of inclusion during treatment has been analyzed.

Jan 1, 2014

By D. N. Madge

A survey is given of production scheduling systems currently in use or contemplated for future use in Cominco operations. Emphasis in this presentation is made on the chain of decisions that are made with the help of mathematical programming models. Some attention is devoted to the structural properties of the models.

Jan 1, 1966

The Metallurgical Development of an Enargite-Bearing Deposit

Sep 13, 2010