Search Documents

By M. C. Ruiz

In the present study, the size distribution, Fo(v), of organic drops produced in a continuous-mixing vessel has been determined experimentally for various conditions. The organic phase used was a 1: 1 mixture of a salicylaldoxime (LIX 860N-IC) and a ketoxime (LIX 64-IC) in an aliphatic diluent (Escaid 103). The aqueous phase was a copper sulfate solution. The results indicated that an increase in stirring speed, extractant concentration, and pH produced smaller drops. The effect of the stirring speed was the most significant, decreasing the average volume of drops by 57 % for a change from 300 to 400 rpm. On the contrary, an increase in the dispersed phase fraction, copper sulfate concentration, and retention time produced larger drops. Changes in temperature from 23 to 30°C did not affect significantly the drop sizes. In all cases, the experimental drop size distributions could be accurately represented by a lognormal distribution.

Jan 1, 2001

Dynamic permeability is a significant hydrologic condition associated with in-situ leaching at the Cyprus Casa Grande operations. Several factors contribute to changes in the permeability conditions. They are: 1) hydraulically induced fracture development, 2) geochemical changes during leaching in the rock matrix, and 3) changes in the relative degree of saturation of the deposit. Dynamic permeability conditions were evaluated using available pressure and flow rates from the 58 injection and recovery wells obtained over one year period. A finite element, 2-D hydrologic model called INVERT which is designed to estimate aquifer parameters under transient and steady state flow conditions was used for the investigation. The permeability conditions during 7 different steady state intervals throughout the one year time frame were determined. The results confirm that big changes in permeability occur as a function of time as well as a function of injection pressure condition.

Jan 1, 1991

By Hong Yong Sohn, Miguel Olivas-Martinez

"Different approaches are used for calculating the ‘energy requirement’ of a process. The determination of energy requirement becomes confusing for a process in which a fuel is also a reactant. The key issue is which heat of chemical reaction should be included in the ‘energy requirement’ value. We will use the example of ironmaking processes to illustrate the problem. The different approaches essentially boil down to the question: does one include the combustion heat of the reductant used in the reduction reaction or just the heat of the reduction reaction? Depending on the viewpoint, either approach can be accepted; it is a matter of convention. There is a need, however, to select a standard approach because the absolute value of ‘energy requirement’ of a process depends on the choice. The energy requirement of a novel flash ironmaking process will be compared with that of an average blast furnace operation.IntroductionDifferent approaches are used for performing energy balance calculations and perhaps more significantly in presenting the ‘energy requirement’ of a process. The question becomes more involved for a process in which one or more reactants are also used to generate the process heat by combustion. Often the key issue is which heat of chemical reaction to include in presenting the ‘energy requirement’ of the process.It is worthwhile to note at the outset that the difference in energy requirements between different processes for converting similar raw materials to the same desired product is largely unaffected by the choice of chemical reactions to be included. However, the absolute value presented as the ‘energy requirement’ of a process can be different by a large amount depending on the approach. We use the example of ironmaking processes to illustrate the problem. In these processes, as currently practiced or under development, carbon and/or hydrocarbons (including hydrogen) are used as the fuel as well as the reactant for reducing the iron oxide mineral.The different approaches in this case essentially boil down to the following question: does one include the combustion heat of the reductant used in the reduction reaction or treat the reductant portion as just a reactant? Depending on the viewpoint, either approach can be considered acceptable. It is a matter of convention. There is a need, however, to select a standard approach because the absolute value of ‘energy requirement’ of an ironmaking process (e.g., the currently dominant blast furnace process) depends on such a choice. It is particularly important to clearly state the specific approach used when the energy requirement of ironmaking is compared with those of other industrial processes such as petrochemicals production."

Jan 1, 2014

By J. J. Sense

The Mission Unit of American Smelting and 'Refining Company is located in Pima County, Arizona, approximately twenty miles southwest of the City of Tucson. The Unit consists of an open pit copper mine and concentrator. The concentrate is shipped by rail to Company Smelters at Hayden, Arizona, or El Paso, Texas Mine stripping began at Mission in the fall of 1959, and construction of the 15,000 tons per day concentrator gas started in the spring of 1960, The first ore was treated in mid summer of 1961 and full ore production was reached in August of 1961. At that time over 46,000,000 tons of material had been moved from the pit. Current production (ore and waste) averages over 100,000 tons per day. Total production to date (ore and waste) over 120,000,000 tons.

Jan 1, 1964

By Clemens Schmetterer, Patrick J. Masset

"The surface tension represents an important property for the modelling of high temperature processes. In this study the surface tension of two Al2O3 – CaO – SiO2 model slags and the influence of the admixture of 5 up to 30 wt.% FeO were studied. The surface tension measurements were carried out using the sessile drop technique on BN substrates under Ar atmosphere (10-6 atm O2) up to 1500 °C.IntroductionThe aim of VIRTUHCON1 is the virtualization of high temperature conversion processes, a task that requires thorough understanding of these processes. In many of these conversion processes slag plays an important role to control the properties of the product, to protect the reactor lining or simply as waste. Slag surface tension is one of the materials properties that is needed for the description of such processes, since it influences the interactions between the components in the reactor, e.g. at the slag – Fe interface in the blast furnace.Surface and interfacial tensions have thus received considerable attention in research, but the number of investigations in this particular pseudo-quaternary system is surprisingly low. Furthermore, the literature data are subject to different measurement conditions and techniques which complicates the data analysis and comparison.The slag atlas [1] offers a compilation of the available literature until 1986 (shown in Table I), but literature search has not revealed more recent studies of this system until now. For example, Elliott and Mounier [2] determined the surface tension of ACSF slags using the double tube maximum bubble pressure technique at 1200 °C. They kept their slags in contact with Cu-S-F mattes, and the slag therefore contained a certain amount of sulphur which acts as a surfactant and lowers the surface tension. The compositions of their slags were scattered over a wide composition range and they did not use a common ACS base mixture for their tests, either. The surface tension values vary between 417 and 446 mN/m, but due to the reasons just mentioned no trend in the measurements can be observed and the influence of FeO admixture on the surface tension cannot be deduced. Further information including the temperature dependence is available from Pavlov et al. [3], Ishchanov and Shushkov [4] and Murav’eva and Kaplun [5]; the diagram on page 446 in Ref. [1] has been drawn from these sources. Both positive and negative temperature coefficients are reported in these works. SiO2 is the only pure constituent that has a positive temperature coefficient [6], but a correlation of the temperature coefficient with the SiO2 content was not found to be conclusive."

Jan 1, 2011

THIS excellent volumetric method commends itself as a means of estimating the fineness of silver firstly, owing to the large number of possible impurities which do not affect its accuracy (these impurities include Cu-up to 70 % Au, Ph, Zn, Bi, Cd, Fe, Mn, Sb, and As); secondly, the method combines accuracy with speed. The above impurities are the only ones likely to be present in the B. H. A. S. Pty. Ltd. refined silver, and, with the exception of Cu and Au, the others, if present at all, would be well under 0.1 parts per 1000.Briefly stated, the method consists in the solution of the refined silver in HN03 , addition of ferric alum (indicator), and titration with an alkaline (either ammonium or potassium) thiocyanate solution until the brown ferric thiocyanate is formed, and gives a definite tint to the solution. The method is used at the Port Pirie smelters, and the outstanding feature in the method as there applied is the type of burette employed. This burette enables the operator to read 0.01 of a cc. with ease, whereas, with the ordinary burette fitted with a float, 0.05 of a cc., when a number of readings have to be taken, becomes very straining to the eyes. Moreover, waiting for the float to rise, and dislodging air bubbles from it, hinders rapid working.A description of the burette and fittings is appended with fig. 2. DETAILS OF THE METHODSolutions required are:a) Stock Solutions:(1) Ammonium thiocyanate, 40 grm. per litre of water; 30 litres are prepared and placed in a carboy with glass syphon attached.(2) Ferric alum, 250 grnl. per litre; two litres are prepared.

Jan 1, 1922

By James P. Connell

The Berkeley Pit of The Anaconda Company is located on the southeast slope of the Butte Hill, the legendary "Richest Hill on Earth," and is one of the largest pit operations in the world completely dependent on truck haulage. Through October 31, 1968, the Berkeley stripping and mining operations have moved more than 442,589,000 tons of material. Present scheduled production is at the rate of 260,000 tons per day, with a record quantity of 306,900 tons having been hauled on September 23, 1968. Although the Berkeley Pit has been in production only a little more than ten years, it has been the proving ground for many of the presently used large trucks. Beginning with the original R. G. LeTourneau 75-ton electric truck in 1960, Unit Rig 85- and 100-ton electric drives, Haulpak 65- and 105-ton electric drives, and Caterpillar 100-ton electric drives have all been tested under production conditions. In addition, engine development has kept pace with both 1000-hp diesel and 1100-hp gas turbine engines now under test. As the size of the Berkeley operation has grown, the truck fleet has changed in size and appearance in order to maintain economic mining costs. The original fleet consisted of forty-three 36-ton trucks with conventional mechanical drives. The present fleet is made up of eighty-nine trucks: nineteen 85-ton Unit Rig electrics with 700-hp diesel engines; sixty-nine 100-ton Unit Rig electrics with either 700- or 1000-hp diesel engines; and one 100-ton Unit Rig electric with an 1100-hp gas turbine engine.

Jan 1, 1969

By A. K. Bakshi

Mineral suspensions show Newtonian flow properties at lower solid concentration, but change into non-Newtonian regime as the solids content is increased. For Newtonian fluids viscosity is independent of shear rate, but for non-Newtonian fluids it varies with rate of shear. Therefore, measurement of viscosity at a shear rate, different from the process will be futile unless the slurry is Newtonian. This is especially true for hydrocyclone operation, where the rate of shear is different at different points within the hydrocyclone. In this case, it is very important to determine the flow type of the suspension before attempting to establish any correlation between viscosity and process efficiency. A new technique to distinguish such changes in flow type has been developed. This involved a co-axial cylinder type viscometer which measured apparent viscosity at a low shear rate, and a vibrating sphere type viscometer which measured the apparent viscosity at a high shear rate. Special precautions were taken to allow measurements of viscosity of rapidly settling mineral suspensions. Because the vibrating sphere viscometer operated at a much higher shear rate than the rotating viscometer, the two instruments together could determine the shear-rate dependency of the viscosity. Ground silica of 80% passing 65~m size in water was used to prepare slurries at concentrations ranging from 1O-70wt% solids. Viscosity of each slurry sample was measured simultaneously by both the viscometers and the results were compared with each other. With this technique, it was found that all the silica slurry samples were in the Newtonian flow regime.

Jan 1, 1995

Failure of rock materials is a process of crack propagation. Crack initiation takes place when the crack tip stress intensity K reaches a critical value called fracture toughness, K1C. The rock fracture toughness is known to be affected by the surrounding environment such as temperature, confining pressure and humidity. In order to examine the effect of humidity, a series of semi-circular bend tests were performed under various water vapour pressures in a rock material that is known to be anisotropic. Water vapour promotes stress corrosion of rock and therefore the fracture toughness was found to have a decreasing trend with increasing water vapour pressure. The rate of decreasing the fracture toughness depends on the microcrack density that promotes the migration of water vapour into the rock. Also in an anisotropic rock, the fracture toughness depends on the direction of crack in relation to the anisotropy of the rock material.

Dec 6, 2010

By Thomas A. Palmer

Free cyanide has been successfully determined in ground and surface water by isolation using a microdiffusion technique followed by a pyridine-barbituric acid photometric finish. The determinable free cyanide includes hydrocyanic acid, ionic cyanide, and the cyanide of weak complexes such as cadmium, lead, manganese, and zinc cyanide. Complexes of copper, iron, nickel, and silver are sufficiently strong so the dissociation into free cyanide does not occur at the microdiffusion pH 7. Cyanate, sulfide, and thiocyanate do not interfere. Samples containing as little as 0.005 mg/L are successfully analyzed. The relative standard deviation is <10%. Samples stored at pH >I2 in the dark are stable at least three weeks.

Jan 1, 1981

A knowledge of airway friction factor (K-factor) is necessary to designing mine ventilation systems for least cost and optimum effectiveness. The friction factor used must be accurate and reliable to estimate correctly roadway resistances and pressure sources for required flows. Though the resistance to flow offered by mine airways has been an object of study over the last half century, no accurate relation has yet been established from which the prediction of the resistance of a projected airway can be made. In Kentucky, only limited and incomplete data on local K-factors are available. Therefore, there is a need for field investigations to determine these values in-situ for existing mining conditions. The author describes a study concerning K-factor that was carried out in ten coal mines, located in eastern and western Kentucky. The results of these investigations are presented in both tabular and graphical form.

Jan 1, 1991

By S. Shimaya, T. Maejima, M. Shimo

"The authors conducted the in-situ gas-tightness tests in a fractured rock at the Namikata underground LPG storage site in Ehime prefecture, Japan. The test consisted of two independent setups, a gas-tightness test that used boreholes, and a chamber-scale test that used a horizontal drift sealed with a concrete plug. In each test, the gas pressure was increased up to the onset of the measurable gas flow to obtain the maximum containment pressure. This paper discusses the hydraulic conditions for gas leakage initiation and the importance of the pore pressure measurement for monitoring the gas-tightness of the LPG storage cavern based on the test results.INTRODUCTIONJapanese first underground LPG storage plant was constructed by JOGMEC, the Japan Oil, Gas and Metals National Corporation, at Namikata in Ehime prefecture in granitic rocks (Kato et al., 2007). The “hydraulic sealing principle” (Åberg, 1977) that utilizes groundwater flow into an unlined cavern to prevent the leakage of gas through fractures in the surrounding rock mass was employed for storage of LPG. This paper describes the results of the in-situ tests performed at the Namikata Site to obtain information on fundamental gas-tightness characteristics of fractured rock. Two types of in-situ tests, a borehole gas-tightness test and a chamber gas-tightness test, were carried out near the storage caverns. Figure 1 shows the cavern layout of the Namikata underground storage plant and the test locations. The storage facilities consist of three caverns (W26m×H30m×L485m). The cavern crown lies at a depth of 150m below the sea level in Cretaceous granitic rock (Figure 1). Water curtain boreholes excavated from the water gallery tunnel at EL-125m level are located above and side of the caverns to prevent water drainage from fractures during the construction stage as well as during operation. The borehole tests were performed from a drilling adit excavated from the eastern end water gallery tunnel, while the chamber test was conducted at the southern edge of an exploratory drift extending from the central water gallery tunnel."

Jan 1, 2015

By Edgar Dunn

PART I.-DETERMINATION OF GASES IN SMELTER FLUES. IN 1907, upon arriving in Anaconda to take up work in the testing department of the Washoe Reduction Works, the. following problem was met at the car step, so to speak: complete and. exact analysis of gases, not only at the stack, but also in all departmental flues. Taken up to employ time not otherwise needed for regular testing department work, instructions were extremely liberal for a commercial plant, to the effect that accuracy should not be sacrificed to speed. In December, 1907, the work was temporarily transferred to the Great Falls Smelter, and some of the methods here given were there worked out. Differences in smelting operations at Great Falls and Anaconda, however, necessitated further investigations and the development of a new method for S03 determinations at the latter plant, where work was resumed in July, 1908, and completed about a year later. At the time of inception of the work, data (not only on percentages, but even on methods) were found to be meager in the extreme, for one or the other of two reasons: either entire lack of experiment at a large proportion of smelters, or disinclination on the part of the managements to divulge data of any description pertaining to either results or methods. In making determinations of gaseous constituents of flues, two methods are open to consideration: 1, the drawing out of a sample, and collection of the same as a whole, to be removed to the laboratory for later analysis; and 2, the absorption in situ on the flue of one certain constituent, disregarding others for the time being, or perhaps combining two or three in one determination. The first is generally the more rapid, but it is also the more inaccurate, method of analysis, even with special type absorption apparatus, being the more largely subject to error, both of reading, and also because of leakage during complicated manipulation in the laboratory. The amount used for analysis must also, because of limit of container, be small for the first method, and an average gas is very seldom obtained, necessitating for a fair average result a large number of determinations. Consequently, when we balance the time spent in a dozen determinations of short-time samples as against the time employed in making two or three long-time determinations of various constituents in situ, we are not so certain in our statement as to the relative speed of the two methods. Moreover, the method of analysis in the laboratory of 100 cc. of flue gas is satisfactory only when constituents thus determined are present in considerable quantity, results being simply approximate when determining such compounds as sulphur dioxide, sulphur trioxide, carbon monoxide and dioxide, and arsenic trioxide and water vapor, none of which are carried in all smelter flues in amounts in excess of (or even approaching) 1 per cent by volume. Special condi-

Jan 8, 1913

By S. E. Phillipson

Underground mine mapping is a critical component of understanding the controls on ground instability. Many relatively localized examples of ground failure are associated with geologic features, such as faults, joints, compaction zones, or sedimentological transition zones. In contrast, long-running, directional roof falls are associated with regionally directed horizontal stress fields, which are induced by tectonic plate interactions in the earth?s crust. When stress-related features are distinguished from geological features, underground mapping can be an effective method for inferring the direction of horizontal stress at individual mines. Comparisons with data compiled in the World Stress Map confirm that underground mapping can be a valid method for determining the orientation of maximum principal horizontal stress at a variety of scales, ranging from individual mines to an entire mining district or coal basin. Comparisons are presented between the maximum horizontal stress directions inferred by MSHA?s Roof Control Division through underground mapping and the azimuths of maximum horizontal stress in the World Stress Map database for North America?s Pennsylvanian-aged Appalachian, Illinois, Black Warrior, and Arkoma Basin coal fields. The comparison indicates that azimuths are similar for both data sets, even where variations in the direction of horizontal stress are present. It is interpreted that inconsistencies in direction are attributable to near-surface affects such as deeply incised stream valleys, or to fault zones that represent heterogeneities in the crust.

Jan 1, 2009

By S. E. Phillipson

Underground mine mapping is a critical component of understanding the controls on ground instability. Many relatively localized examples of ground failure are associated with geologic features, such as faults, joints, compaction zones, or sedimentological transition zones. In contrast, long-running, directional roof falls are associated with regionally directed horizontal stress fields, which are induced by tectonic plate interactions in the earth?s crust. When stress-related features are distinguished from geological features, underground mapping can be an effective method for inferring the direction of horizontal stress at individual mines. Comparisons with data compiled in the World Stress Map confirm that underground mapping can be a valid method for determining the orientation of maximum principal horizontal stress at a variety of scales, ranging from individual mines to an entire mining district or coal basin. Comparisons are presented between the maximum horizontal stress directions inferred by MSHA?s Roof Control Division through underground mapping and the azimuths of maximum horizontal stress in the World Stress Map database for North America?s Pennsylvanian-aged Appalachian, Illinois, Black Warrior, and Arkoma Basin coal fields. The comparison indicates that azimuths are similar for both data sets, even where variations in the direction of horizontal stress are present. It is interpreted that inconsistencies in direction are attributable to near-surface affects such as deeply incised stream valleys, or to fault zones that represent heterogeneities in the crust.

Jan 1, 2009

By Mohamed A. Eliwah

This paper deals with the determination of hydraulic conductivity of the coastal coralline limestone aquifer of Jeddah, Saudi Arabia. This coastal area has witnessed urban development and establishment of towers which requires deep foundations, excavation and dewatering of huge quantities of unconfined groundwater. It is occupied with successive layers of soft detrital and consolidated massive cavernous coralline limestone of the Quaternary age. These layers are encountered at a depth of 1.5m and extend for more than 100m. Hydraulic conductivity values were obtained by analyzing the pumping tests data under steady and transient state conditions. Hydraulic conductivity values help in selecting the proper and safe dewatering system, as well as determination of discharge rates and quantities of groundwater to be withdrawn. Test results obtained from two surveyed sites showed that the values of hydraulic conductivity are greatly variable. It ranges between 118.1 and 1559.6 m/day at the first site, whereas at the second one it ranges between 94.6 and 350 m/day. These high values are attributed to the cavernous nature of the water-bearing formation. Jeddah city could be divided into three different dewatering zones extending from north to south parallel to the coast line. Well point dewatering system could be applied in the first zone while ditches and sumps are the most suitable dewatering method in the second and third zones. Dewatering using deep wells in such highly permeable formation will require withdrawal of huge quantities of water which will be accompanied by washing out fine sediment filling the cavities in the surrounding areas. This will badly affect the nearby buildings through settlement, crakes and other structural damages. Therefore, construction of grouting plug/blanket with thickness of 3.0 m at a depth of 20.0 m is recommended. This depth will be enough to support the plug against the hydrostatic pressure. Moreover, it is highly recommended to transfer the site into closed box, by using diaphragm walls or secant bored piles.

By H. Ankara

Determining the identicalness levels of the same model trucks working in open pit mine transportation system by means of statistical analysis methods is very significant in terms of availability analysis. In this study, the identicalness levels of two trucks picked randomly from the 170-short-tonne truck fleet working in open pit coal mine over one-year period were examined through a non-parametric test, Mann-Whitney U test for two samples. Time to failures (TTFs) and Time to Repairs (TTRs) of the trucks were analyzed with this test technique and then whether they were identical or not was determined. In order to determine whether the trucks identified to be identical at the end of this test displayed the same mining performances within the same open pit transportation system, the availability analysis of the identical trucks was carried out. As a result of the availability analysis, it was observed that the trucks had availability values that were very close to each other. It was also determined that Mann-Whitney U test could be employed together with availability analysis. Finally, it was observed that Mann-Whitney U test for two samples could yield rapid results in the performance analysis of complex systems like open pit mines.

Jan 1, 2010

By Michael J. Beus, Jan G. Patricio

INTRODUCTION The U.S. Bureau of Mines, Spokane Mining Research Center, has been conducting and documenting rock mechanics research in the Coeur d’Alene mining district for the past ten years (1, 2, 3, 4, 14, 15). A current project combines the information gathered from rock mechanics instrumentation, geologic structure, and analytic techniques to improve shaft and support design for the deep mines of the district (3). This project required knowledge of the anticipated loads and the physical properties of the rock mass to provide accurate input data for computer design models. Several techniques have been utilized to determine the physical parameters including the USGS (U.S. Geological Survey) solid inclusion probe, the CSIR (Council for Scientific and Industrial Research) biaxial and triaxial strain cells, and the CSM (Colorado School of Mines) dilatometer. This paper describes the determination of the in situ modulus of deformation in three mines over a period of three years and the evaluation of these results as they applied to this project. The need for in-situ rock mass properties such as the modulus of deformation has stimulated research and development of a large number of instrumentation techniques. One area of continuing interest involves various methods of radial borehole dilation. This concept was pursued by Menard (9) with an apparatus known as the pressure meter, which is used frequently in soil mechanics. Other developments in rock mechanics include the CPC (cylindrical pressure cell) by Panek (11) and the dilatometer by Rocha et.al. (13) in Portugal. The CSM dilatometer, which also utilizes this technique, was chosen for this project because it required a small amount of background study, was inexpensive, and could easily be combined with other experiments being planned for the test locations. Although no previous field applications to hard rock (compressive strengths greater than 20,000 psi) has been documented, the instrument was selected since good results have been achieved in granite, oil shale, and several coal measure rocks (11, 12).

Jan 1, 1977

By Amoussou Coffi Adoko, Shevaune Zeng, Sebastian D’Hyon, Gareth Kennedy, Eleonora Widzyk-Capehart

Inertization of coal dust with stone dust is a common control implemented within underground coal mines to mitigate the hazard of a coal dust explosion. To achieve adequate inertization, the total incombustible content (TIC) of the coal/stone dust mixture is required to meet certain percentages depending on the risk and relevant legislation. Current methods for determining the TIC of a mixture involves laboratory analysis, colorimetric comparison, or the use of portable instruments. This paper provides preliminary analysis of determination of a sample’s TIC in real-time with chemometric modelling, using portable instruments employing near-infrared (NIR).

Feb 1, 2024

By S. K. Sadrnezhaad, B. Hashemi, Z. A. Nemati, Z. Moghimi

Based on the kinetics relationships of a solid - gas model, a software was developed for the prediction of oxidation. Preliminary prediction of oxidation by the software and experimental results of MgO-C refractories were studied and compared. By using the obtained data from this approach, the effective diffusion coefficient, intermolecular diffusion coefficient and diffusion activation energy in the MgO-C refractories, containing various amount of graphite were obtained at different temperatures. First of all, the prediction by the software was very compatible with experimental results, for different oxidation mechanisms in the MgO-C refractories. The results showed that pore diffusion is the predominant oxidation mechanism in this system. The results indicated that when graphite content was above 10wt%, the intermolecular diffusion coefficient was independent from graphite content, and it was closed to a constant value at each temperature.

Jan 1, 2004