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By Xia Zhao, Yong Zhao, Wen Pan, Ze-jun Ma, Yan-juan Yang

Characteristics of the gas-solid reduction reaction between iron ore sinter and carbon monoxide (CO) gas at 1273 K were studied with thermogravimetric analyzer. The microstructure, mineral compositions and porosity of sample were investigated prior to reduction, in the 30% reduced sample, in the 70% reduced sample, and in the fully reduced sample. At the reduction degree of 30%, the hematite and calcium ferrite was reduced to 44.4 and 60.4% respectively. At the reduction degree of 70%, all the hematite, calcium ferrite and magnetite were reduced to metal iron, only 36% wustite was left in the core area. The reduction reaction began with the loose structures and spread to the nearby area. In the area of micropores, the reducing gas can easily diffuse to the reaction interface to proceed the reduction reaction effectively. So increasing the content of micro-pores is an effective way to improve the reducibility of the sinter.

Mar 1, 2018

By P. A. Meyer

The Tenmile Range is a north trending zone of high relief within the central Colorado porphyry-mineral belt, located between Leadville and Breckenridge. (Figure 1, the Index Map of the area surveyed.) The Climax mineralized zone is located at the southern end of the range on the northwest side of the Continental Divide. This portion of the total area surveyed will be discussed in detail today. A fixed wing aeromagnetic survey was flown over this range and mineralized zone in the fall of 1957. The survey was run as an experiment to see if a useful geophysical tool could be applied in the exploration for similar type deposits. The purpose of this paper is to describe the results of this survey and the approaches used to aid in the interpretation of the total intensity data.

Jan 1, 1968

By John H. Hollomon

The interpretation of notched-bar impact results has been a matter of controversy since the introduction of more or less standard tests by Fremont,' Charpy2 and others at the turn of the century. Many investigators3-l1 have contributed to the understanding of the significance of such tests. Several symposiums12,13 have been held with the express purpose of discussing the significance and interpretation of the impact tests. It is not the purpose of this paper to review all these contributions to the development of the knowledge on this subject, but rather to present an interpretation of notched-bar impact tests that appears to be in agreement with the available published data. Fundamentally, the interpretation discussed in this paper of the brittle failure of some steels in notched-bar impact test is similar to the qualitative analysis presented by Ludwik3 in the I92o's. Essentially, Ludwik stated that the function of the notch was to increase the tensile stress necessary for yielding, and that brittle failure occurred when the stress necessary for yielding exceeded the normal stress required for fracture (with no plastic deformation). Ludwik, however, had no means of measuring this normal stress necessary for failure of a plastically* undeformed metal, therefore he could not extend his interpretation beyond the qualitative stage. Kuntze14 and recently Mc-Adam15 attempted to determine the effect of deformation on the stress necessary for fracture by testing, in tension, specimens notched to various depths and angles. Because of the uncertainties in Kuntze's (and McAdam's) analysis of the stresses (which have been pointed out by Sachs16) and the inherent nonuniformity in the stress distribution in notched bars, the results of such investigations are difficult to interpret. A more direct method of measuring the effect of deformation on the fracture stress was suggested in previous papers"-18 and has been utilized in the present investigation. The present paper concerns itself primarily with the behavior of notched impact specimens. The effects of strain rate, temperature, and stress distribution, which are discussed with reference to the impact specimen, apply just as well to the behavior of metal at the bases of notches in any engineering structure. All that is necessary is to determine the stress distribution in the structure at the base of the notches.

Jan 1, 1944

By E. R. Johnson

The copper concentrator of the Braden Copper Co. is at Sewell, Chile, on the westem flank of the main Cordillera of the Andes, at an air distance of approximately 50 miles southeast of Santiago, the capital of Chile. The region is mountainous and space is at a premium because of the rough terrain and the danger of snowslides. The ore, a porphyry copper, is mined by a block-caving method in the El Teniente mine. It is hauled to the crushing plant, a distance of 2.6 miles, through a tunnel because of the severe climatic conditions. The usual large, coarsely set, primary reduction machines found in many ore-treating plants are not required because of the mining method employed and the limiting 12-in. spacing of the grizzlies at the head of each ore pass in the mine. It is the purpose of this paper to describe the numerous improvements made in the crushing section of this large flotation concentrator during the past I5 years to increase the efficiency of the plant and to raise the daily output from around 20,000 to 30,000 tons. The reader should keep in mind that all changes were made within the existing building because of the limited space and the high cost of the heavy mill construction required to withstand the snow loads. The present plant, as well as the former, operates on a 24-hr, 7 days a week basis. The crushing plant commenced operations at its present site in 1921, the main equipment being No. 7½ gyratories, followed by 48-in. horizontal Symons disk crushers. Fines were removed by I-in. stationary grizzlies ahead of each unit. In 1924 a third stage of crushing was provided by the addition of 55½-in. rolls in open circuit. During 1925, the Symons disks were replaced by 73½-in. rolls. All the rolls were changed to closed circuit, with elevators and screens to give a final product of 9 pct plus 3-mesh. The flowsheet of a typical crushing section of this period is shown in Fig I. The ore was withdrawn from a common bill serving the five crushing sections in the plant by means of any number up to six 36-in. wide-apron feeders, which discharged onto a common conveyor belt. This conveyor was equipped with a magnetic head pulley and the crusher attendant was stationed near the discharge end to pick out pieces of mine timber that might be in the ore. The ore was discharged over a 13/4-in. spaced bar grizzly and the oversize of this grizzly was crushed by a No. 7½ McCully gyratory crusher set at 13/4-in. opening on the closed side. The grizzly undersize joined the gyratory discharge and was conveyed to a set of 73½ by 20-in. Garfield rolls set at I in. These rolls operated in closed circuit with a bucket elevator and two vibrating screens placed in parallel.

Jan 1, 1949

By John H. Hollomon

The interpretation of notched-bar impact results has been a matter of controversy since the introduction of more or less standard tests by Fremont,' Charpy2 and others at the turn of the century. Many investigators3-l1 have contributed to the understanding of the significance of such tests. Several symposiums12,13 have been held with the express purpose of discussing the significance and interpretation of the impact tests. It is not the purpose of this paper to review all these contributions to the development of the knowledge on this subject, but rather to present an interpretation of notched-bar impact tests that appears to be in agreement with the available published data. Fundamentally, the interpretation discussed in this paper of the brittle failure of some steels in notched-bar impact test is similar to the qualitative analysis presented by Ludwik3 in the I92o's. Essentially, Ludwik stated that the function of the notch was to increase the tensile stress necessary for yielding, and that brittle failure occurred when the stress necessary for yielding exceeded the normal stress required for fracture (with no plastic deformation). Ludwik, however, had no means of measuring this normal stress necessary for failure of a plastically* undeformed metal, therefore he could not extend his interpretation beyond the qualitative stage. Kuntze14 and recently Mc-Adam15 attempted to determine the effect of deformation on the stress necessary for fracture by testing, in tension, specimens notched to various depths and angles. Because of the uncertainties in Kuntze's (and McAdam's) analysis of the stresses (which have been pointed out by Sachs16) and the inherent nonuniformity in the stress distribution in notched bars, the results of such investigations are difficult to interpret. A more direct method of measuring the effect of deformation on the fracture stress was suggested in previous papers"-18 and has been utilized in the present investigation. The present paper concerns itself primarily with the behavior of notched impact specimens. The effects of strain rate, temperature, and stress distribution, which are discussed with reference to the impact specimen, apply just as well to the behavior of metal at the bases of notches in any engineering structure. All that is necessary is to determine the stress distribution in the structure at the base of the notches.

Jan 1, 1944

By E. C. Barfield, D. G. McCarty

Two-dimensional analyses offer considerable promise in providing the basic information required to effect more precise control of petroleum reservoir performance. This paper describes a method for conducting some engineering analyses of this type using a high-qreed digital computer. The general approach is to (I) develop a representative numerical model of the reservoir and (2) employ a suitable numerical technique to solve the basic equation of flow and to develop the required engineering information for the particular case represented by the model. This technique has been used to calculate pattern performance in connection with several field projects involving water injection into oil reservoirs. This type of analysis involves sequentially (I) calculating the pres-' sure distribution in the reservoir and (2) tracking the progress of the interface between the displaced and displacing fluids in a step-wise manner to provide a depletion history of the operation. The particular analysis presented in this discussion is subject to the restriction that the mobility of the displaced and displacing fluids be equal and assumes that the fluids are incompressible and that gravity and capillary pressure do not affect the shape of the flood pattern. Complete two-dimensional .flexibility is maintained with regard to definition of reservoir rock and fluid characteristics, placement of physical restrains and boundary conditions, investigation of flow characteristics in the reservoir, and movement of the displaced and displacing fluid interface. The results of these studies indicate that the highspeed digital computer is well suited for conducting reservoir performance studies in two-space dimensions and that dependable numerical techniques are available for making such analyses. INTRODUCTION One of the problems facing petroleum engineers is that of providing more precise engineering control over reservoir operations at all stages during the depletion cycle. The most direct approach to this problem is to simulate the reservoir with some type of physical or mathematical model and use the information developed from the behavior of the prototype to predict the performance of the actual reservoir. This principle is, of course, not new, and a variety of simulation techniques have been developed to provide information on the behavior of oil and gas reservoirs. One straightforward refinement of present reservoir analysis techniques is the progress from one-dimensional reservoir models to those where the reservoir can be represented in two- and three-space dimensions. Multidimensional reservoir analyses are desired in order to show not only what is happening in the reservoir but in addition to show where in the reservoir the various phenomena of interest are occurring. Thus far, two-dimensional analyses have been confined predominantly to potentiometric and electrolytic model studies. However, when large numbers of wells are involved and where large-scale models are required, such problems become very tedious and instrumentation problems become acute." It is possible through use of numerical methods and general purpose digital computers to avoid many of the instrumentation difficulties and to relax some of the restrictions of previous techniques. The purpose of this paper is to discuss some recent experiences with the use of high-speed digital computers for predicting pattern performance in fluid injection operations and to describe the numerical procedures which have been used for making such analyses. THE NUMERICAL MODEL The problem of representing the reservoir with an appropriate numerical model is composed of at least two important considerations. The first requires that an adequate description of the reservoir mechanism be formulated in the form of the basic differential equation describing the process. The second consideration is definition of the physical characteristics of the reservoir. The latter requires that representative basic data be obtained, examined, and interpreted to provide sufficient detailed definition of the pertinent physical properties throughout the system. The Differential Equation One of the basic assumptions made for the purpose of performing the two-dimensional studies being dis-

By B. H. Caudle, M. D. Witte

In predicting the performance of a pattern injection operation, the engineer needs to know both the amount of oil to be recovered and the rate at which the recovcry will take place. This paper- describes fluid flow model studies on the effect of mobility ratio on the rate of oil recovery in a five-spot. The results show the change in fluid conductivity (total flow rate/pressure drop) as the sweep-ont pattern increases for mobility ratios between 0.1 (and 10. There data, when cornbitted with a knowledge of reservoir permeabilities and sweep-orit pattern efficiencies, cata he used to predict the cLrmulntivr oil production as a function of time for homogeneous five-spot injection systems. INTRODUCTION The flow potential in a pattern flood element is a function of the mobility ratio and how far the injected flood front has gone.1,2 For a waterflood project having a mobility ratio of one, the conductance—which is the flow rate per unit pressure drop (q/Ap)—-will remain the same throughout the life of the flood. If the mobility ratio is favorable ( < I), the conductance of the project will drop continuously throughout the operation. If, on the other hand, the mobility ratio is unfavorahlc. the conductance ratio will increase continuously. Therefore, if the reservoir engineer wishes to predict either the rate at a specified pressure or the pressure at some rate for a secondary recovery project, he must know how the conductance will vary during the flood. Other investigators have studied this problem using potentiometric models&apos; or analytical solution&apos;. The

By M. Leahy

"Very little is known about the large scale fluid dynamics and associated distribution of copper in an operating electrowinning cell, yet they will have a major influence on mass transfer and plating quality. The CFD model in this work is used to simulate an entire EW cell with 60 cathodes and 61 anodes, or 121 anode–cathode pairs, elucidating for the first time the three-dimensional (3D) flow and copper distribution in an industrial cell. Two methods for the distribution of electrolyte are modelled:1. Downcomer method: electrolyte is fed by a downcomer at one end of the cell, overflowing at the opposite end.2. Manifold method: a horizontal manifold pipe runs the whole length of the cell and feeds electrolyte via small holes in the top of the manifold pipe.The recirculation that develops within each anode-cathode pair, driven by oxygen bubble generation on the anode, is similar to that seen previously in two-dimensional models of single anode–cathode gaps. However a more complex 3D flow recirculation is established, which involves flow of electrolyte down the side gaps (being a path of low resistance for return flow) as well as the usual return flow down the cathode side of each pair gap. The bubble-driven flow is not influenced by the mode of electrolyte distribution.The electrolyte flow due to the manifold and downcomer is somewhat secondary to the bubble driven flow. In the case of the downcomer distribution mode, the high injection velocity causes a very turbulent flow in the first 1–2 m down the cell from the downcomer, with several large vortices developing. This may lead to some sludge particles being entrained into the bulk of the cell.In the manifold pipe case, the jet from each hole is dissipated very quickly, within the first 10–20 cm. The jets are directed into the downward flowing zone of the bubble-driven recirculation, which leads to unstable and periodic behaviour on a large spatial scale.In both the manifold and downcomer cases, there is a marked two-zone vertical stratification in copper concentration."

Jan 1, 2016

By J. S. Pascover, J. K. Abraham

The influence of the early stages of precipitation on the kinetics and structure of martensite formation in Fe-27Ni and Fe-29.5Ni alloys containing from 0 to 10 pct Ti was examined with X-ray and electron microscopy techniques. The formation of a coherent, ordered preprecipitate had a profound stabilizing effect on the austenite. The Ms was decreased by increased titanium content and aging time up to a critical time. When the critical aging time was exceeded, the Ms was observed to increase markedly. The formation of the clusters was insuppressible and the volume fraction of clusters formed during the quench was a function of the titanium content. Martensite resulting from transformation of the clustered austenite is tetragonal with the c/a ratio increasing with titanium content. A model for the tetragonality is suggested. The morphology and substructure of the m artensite is inter-preted in terms of the above information and the cur-rent models of twinned martensite. ThE ramifications of precipitation in austenite to the properties of austenite have been the subject of numerous investigations. The current research is concerned with the influence of precipitation in austenite on the kinetics and structure of subsequent marten-site formation. In a previous investigation, Abraham et al.1 followed the aging reaction in an Fe-29.5Ni-4.2Ti* (at. pct) alloy using an X-ray diffraction technique. This technique, employing a Guinier camera, provided kinetic measurements through observation of the side band position as a function of aging time. The salient results of this work were: 1) The initiation of precipitation was not suppressed by quenching, i.e., there was a finite cluster zone size at zero aging time; and 2) The hardness of the aged austenite correlated extremely well with the zone size. During the previous work it was noted that the mar-tensite formed after aging was tetragonal, substanti-ating an earlier observation.2 Systematic investiga-tion revealed that the martensite was tetragonal in both the solution-treated then quenched, and the solu-tion-treated, aged, and quenched condition, and, furthermore, that a marked stabilization of the austenite occurred as a function of aging time. The present work is concerned with documenting the tetragonality and the stabilization phenomena as well as the ob- served microstruction with a suggested rationale for the behavior noted. EXPERIMENTAL PROCEDURE The compositions of the alloys are listed in Table I. The analyses were performed after the solution treatment of the strip material. Nickel was determined using the standard dimethy1-glyoxime procedure whereas titanium was determined colorimetrically with hydrogen peroxide and volumetrically by titrating with ferric iron. The materials were melted in a 5-lb vacuum induction furnace, cast into 2-in.-diam ingots, and forged in a temperature range of 950. to 1200°C to 1/2-in. slabs. The three higher titanium containing materials cracked during forging; therefore, to get the alloys into strip form, slices 1/8 in. thick were cut from the slab, homogenized 4 hr at 1150°C, then cold-rolled to a 0.04-in. thickness. The remaining slabs were hot-rolled, homogenized 4 hr at 1065"C, then cold-rolled to a final thickness of 0.03 in. All of the heat treatments were performed under a protective atmosphere of argon. The Ms temperature for most of the alloys is below room temperature; therefore, it was possible to solution treat, quench to room temperature, polish, and then observe the transformation optically on a cold-stage microscope. To determine the effect of aus-tenitizing temperature on Ms, eight of the alloys were treated at two temperatures, 1025" and 1120°C. No measurable variations in Ms were noticed. The remaining alloys were treated at 1025°C. The specimens, : by 5/16 by 0.03 in., were austeni-tized in a vertical tube furnace under a dynamic argon atmosphere. The bottom of the tube was submerged in water for quenching purposes. The question of stabilization that may be operating at room temperature was investigated and found to be negligible. Many of the specimens were held at room

Jan 1, 1970

By A. Rahmati

Geological and geo-statistical modeling of the ore deposits play a prominent role in resource and reserve estimation for geo-statistical evaluations. Sheytoor iron deposit is located in the Bafq iron ore district (Central Iran) and in the south-east of the Esfordi 1:100000 sheet. According to the geological data, limestones and dolomitic limestones are situated in the north and central parts of the area, on the other hand, iron ore outcrops are observable in the center, south-west and south-east of the studied area. Meanwhile this ore deposit represents a sulfide one. Based on the boreholes data, geological and geostatistical models of the high and low grade iron mineralization zones were generated by Rockworks v.15 software. The IDW method was selected and employed for processing the collected data and a good adaptation between the results was revealed. The distribution model of Fe concentration displayed a relatively high grade Fe in the center, south and south-east parts of the area. Furthermore, this model illustrated a relatively high grade S and P in some parts of the center, north and south-east of the area. The Fe concentration, in the high grade mineralization zone, was between 45 and 61.5%. In addition, in the low grade mineralization zone, it was between 3.64 and 57.64%. Moreover, in the intrusive granites, the Fe concentration was between 30 and 48.73%. Due to the significant amount of the sulfur in the deposit model, most of Fe-bearing minerals are pyrite, so it is recommended an evaluation on Cu-bearing minerals and their related elements in the area to get done. Additionally, there are too much Fe values in granitic zones which could be caused by possible measurement errors and the geological classification of the area. Therefore, it should be done more carefully.

Aug 1, 2013

By H. Groeneveld, C. A. Connally, P. J. Hoenmans, J. J. Justen, W. L. Mason

A miscible displacement pilot using a slug of LPG driven by separator gas was conducted in the Cardiurn reservoir of the Pembina field. The injection pattern was a 10-acre, inverted, isolated five-spot. Upon completion of the LPG-gar phase, an experiment was conducted using a slug of water followed by gas. Calculated performance of the pilot is compared with actual performance. Equations are developed to calculate the distribution of LPG into zones of varying permeability, to estimate the progress of the flood at different times in the various zones and to estimate gas rates after breakthrough. The analysis indicates that permeability stratification was a dominant factor in controlling oil recovery and that oil was completely displaced from the swept pore volume. The results of the pilot indicated that miscible flooding is a practical means of pressure maintenance in this reservoir. The total recovery from the pilot area was good in spite of the early breakthrough of LPG. The effects of stratification were reduced by injecting a slug of water into the partially swept reservoir. INTRODUCTION The Pembina field,&apos; located in Alberta, is the largest oil field in Canada and one of the largest in the North American continent. The reservoir is a stratigraphic trap producing from the Cardium sand. Neither bottom water nor free gas has been found. The recovery of oil by the natural depletion mechanism has been estimated at 12.5 per cent. Pressure maintenance studies of various areas have indicated that the recovery can be increased 21/2 times by water flooding, and a large area of the field is presently under water flood. However, reservoir studies of the North Pembina area indicated that miscible flooding might be competitive with water flooding. A pilot test was conducted to evaluate the performance of a miscible flood. A 10-acre, inverted, isolated, five-spot pattern was selected for the pilot. The pattern area was large enough to minimize wellbore fracturing effects and contained sufficient oil to provide significant working numbers. The performance of each of the four producers could be evaluated individually and compared. In the event of breakthrough in one direction, the effect would be isolated from the other producers. The use of a single injector minimized the volume of LPG required, and, because of the high mobility of gas, one well was sufficient to inject the necessary daily volume to replace the high rate of production. With four producers, the test could be completed in time for results to be evaluated, additional engineering studies to be made and a unit to be formed before the reservoir pressure in the North Pembina area declined below the bubble point. The pilot was located in an area developed on staggered, 80-acre spacing. The injection well was drilled at a regular location, while the four producers were drilled 467-ft north, east, south and west of the injector. Each quadrant and its associated producer were identified according to their direction from the injector— that is, north, east, south or west. The eight surrounding producers on 80-acre spacing were shut in to isolate the pilot area and provide for reservoir pressure observation. The pilot wells were completed using permanent-type completion techniques. After coring, casing was run through the pay section and cemented. Inside 51/2-in. casing, 2 1/2-in. tubing was hung. The wells were perforated opposite the Upper Cardium sand and lightly fractured. Fracturing volumes, rates and pressures were low to minimize the extent of the fractures. The fracturing treatments average 1,000 lb of 20-40 mesh sand in 700 gal of a low fluid-loss sand-carrying agent. Feed rates and wellhead fracturing pressures averaged 5.5 bbl/min at 2,535 psig, respectively. After fracturing, the productivity index was measured in each of the five pilot wells. The average PI of the four producers was 0.41 BOPD/psig drawdown. The measured PI&apos;S were approximately the same as PI&apos;S calculated from core analysis data, indicating that the fracturing treatments were just sufficient to overcome

By WILLIAM WATERS

L HISTORY. THE Pierrefitte mines, situated in the South of France, in the district of the Hautes-Pyrenees, owe their name to the fact that the first mining operations of any extent, and of comparatively recent date, were carried out in the neighborhood of the vil¬lage of Pierrefitte, which is a branch terminus of the Midi railway. The Pierrefitte mines, however, embrace a wide extent of country and several different concessions, on most of which comparatively little exploration-work has been done. The portion of the property presently to be described is a zone running roughly E-W., over a distance of about 5 miles from the valley of Cauterets to the valley of Estaing, the ridge dividing these valleys being a spur of the main chain of the Pyrenees, and running more or less at right angles to it. According to local tradition, which various indications tend to confirm, these mines are of ancient date, the first workings being attributed to the Romans, who are supposed to have sought not only the lead but also the silver which is contained in the ore. Old slags have been found in the neighborhood which might well have been produced from the cupellation of lead-ores. These old workings, while of considerable extent at times, do not seem to have extended beyond a depth of 100 ft., even this depth being somewhat exceptional. The old notarial records of the district show that mines were known to exist, and that they were even worked, in the sixteenth century, but since the mines were abandoned (by the Romans or others) considerably prior to this period, very little

Nov 1, 1908

By Danu Putra, Budi Sulistianto, Tri Karian, Mohammad Nur Heriawan

Stope layout optimization is an important feature of underground mining that maximizes the economic value of the project while taking mining limits into account. The large number of parameters and constraints makes it difficult to obtain the optimum condition. Several algorithms have been created to address these problems using a variety of methods. However, the circulating method has not explicitly included stope dimension stability analysis, resulting in a solution that is not stability-proven, which can result in a suboptimal solution. This study integrates the Mathews stability graph into the stope optimization algorithm so that the optimized stope layout considers stability conditions directly through an assessment of the available geomechanical data within the block model. The proposed algorithm is validated through a case study of a synthetic block model created by considering variations in grade and the geomechanical conditions of the rock. Furthermore, several scenarios are created to compare the performance of the algorithm that applies variations in stope sizes with the common case study of stope sizes that remain fixed. A more detailed assessment is also conducted on each final stope layout wall to ensure the successful application of stability analysis in the proposed algorithm through back analysis on the Mathews stability graph. The optimization results show that all walls in the final stope layout fall into the stable condition. Also, the proposed algorithm is also capable of maintaining the project’s economic value. Ultimately, the proposed algorithm can be deemed applicable and suitable for use in the initial stages of mining as a comprehensive assessment of the optimal stope layout, taking into account the stability conditions of the stope.

May 22, 2024

By Kewal K. Kohli, Stefanie Self

"Three cases of surface subsidence investigated over abandoned coal mines after flooding in one case and dcwatering in two cases are presented in this paper. Mining was conducted by the room and- pillar method at all the mines leaving stable pillars. This paper will discuss the background chain of events and the likely causes of the pillar failure resulting in surface subsidence.CASE NO.1BackgroundThe Pittsburgh scam was mined in 1960 by the room-and- pillar method, leaving pillars (Figure I) through Mine A. located in Monongalia County. West Virginia.The mining height in U1is area was 1.83 m (6 ft) with an average mining depth of 140 m (460 ft). The mining recovery was 62% and the safety factor of the pillars was calculated at 1.15 using the Bieniawski ( 1984) fom1ula. For stable pillar design. a 1.5 safety factor is recommended. A 1.15 safety factor is considered marginal. Pumping continued after the mine was shut down in 1960 to prevent water seeping into an adjoining mine owned by the same company. The pumping ceased on December 12. 2003, and the mine was allowed to flood. The water level rose about 17 m (55 ft) by August 3 1, 2004, based on observations in a nearby borehole. On September 3, 2004 surface subsidence occurred above this area causing damage 10 a residence (Figure 2).Summary of InvestigationThe floor of the Pittsburgh coal scam played a strong role in the pillar failure. In this area, the immediate floor of the Pittsburgh seam consists of about two feet of fireclay. Extensive damage to the surface house was an indication that a major collapse below the surface had occurred. The pillars supporting the overlying strata were evaluated to find the cause of their failure. The pillars in the Pittsburgh seam (sec Figure I) had a marginal safety factor of 1.15 before flooding and were stable for 26 years. Once the mine was flooded the water level in the Pittsburgh seam rose by 17 m (55 ft). Shortly thereafter the fireclay in the floor weakened, resulting in several pillars punching into the floor unevenly making the immediate roof unstable. The overburden strata supported by these pillars also subsided do"" n into the mine, causing damage to several house on the surface."

Jan 1, 2010

By Helmut Antrekowitsch

Nowadays nearly the half of the world zinc production is used for galvanizing. After their life span most of the galvanized products return as scrap to the steel mill. During the steel process the zinc is collected in the flue dust It is astonishing to notice that between 40 and 50 % of the zinc produced is brought into the steel processing cycle by the coated scrap while only 3 to 5 % of the zinc production can be covered by the recycling of the zinc-bearing steel mill dusts. Responsible for this worse ratio is the fact that the established recycling technologies suffer from high energy consumption, low zinc yields, halogen problems and hardly any iron recovery. A development of new or an optimization of current recycling procedures for the dusts is unalterable because of increasing zinc amounts in these residues and the rising costs for the disposal. Different pyrometallurgical recycling technologies are tested in rotary kilns and vertical retorts at the Department of Nonferrous Metallurgy, University of Leoben, Austria. Various reducing agents from carbon monoxide to hydrogen and combinations are used. The results should make it possible to draw conclusions that allow an economical and ecological judgement of the different varieties. The goal is to support the affected industry to increase the low recycling rate and prevent a loss of high zinc values in the steel industry filter dusts.

Jan 1, 2003

By V. R. Garfias

INTRODUCTION FOR a number of years the senior author has been interested in the various geologic and engineering problems involved in the development of the petroliferous districts of northeastern Mexico, having in a previous paper 1 endeavored to present a summarized statement of the information relating to the geology and soil resources of this region. Of the many interesting geologic phenomena, perhaps those which have been the object of more speculation relate to the igneous intrusions which, in places, have a controlling influence on the accumulation of oil in commercial quantities, a relationship which has been tentatively explained by various observers with as many interestingly different views. The authors of the present paper aim to record, in the course of a general discussion of the various viewpoints, some additional data, and present further tentative conclusions with a view to rounding out an up-to-date summary of the subject. The greater part of the area in question lies in the State of Vera Cruz, only a northwest fraction being in the State of San Luis Potosi. Vera Cruz is bounded on the north by the State of Tamaulipas, the northernmost of the Mexican States along the Gulf. The topography of the States of Tamaulipas and Vera Cruz and of Texas and Louisiana to the north, is controlled by the Gulf coastal plain which in northern Vera Cruz has an average width of about 60 miles, the transitional topography between that of the rugged flanks of the Sierra and the lowlands of the coast being made up of a series of terraces and irregular hills and valleys.

Jan 8, 1917

By M. S. Seehra, R. S. Pandurangi

"Investigations of the infrared spectra of crystalline and amorphous silica particles of different sizes (0.05, 5, 10, 15, 30, 45, and 260 um) in the range of 400-4000 cm-1 using Fourier transform infrared/photoacoustic spectroscopy we reported. The change in the intensity I of the signal with porosity e of powders follows the e/(1 - e) dependence for strong bands and e dependence for weaker bands as pre¬dicted by the theory of McGovern of al. For strong bands, I also follows the empirical relation I ~ D-n, where D Is the particle diameter in cm and n = 0.34-0.42. The anomalous positive frequency dependence of I on the modulation fre¬quency f observed for the stronger bands in the 45-pm and 260-pm particles Is believed to result from saturation. Some observations on the effect of changing the background from (carbon black) powder to pellet are also made.INTRODUCTIONSince the publication of the Rosencwaig—Gersho (RG) theory on the photoacoustic effect in solids (1, 2), Fourier transform infrared/photoacoustic spectroscopy (FTIR/PAS) has become an important technique for obtaining the IR spectra of surfaces and materials in their natural state (1-12). In the one-dimensional RG theory, the incident radiation, modulated at frequency f, is absorbed by the material to a depth pp = 1/B (B = absorption coefficient), thus setting up temperature variations in the material. These variations heat the adjacent gas/solid interface leading to the pressure fluctuations of the gas above the sample, which in turn is detected by microphone as a PA signal. The thermal wave originating from no deeper than the thermal diffusion length(2k/npcf) 1/2 in the material contributes to the PA signal (here k, p, and c are respectively the thermal conductivity, density, and specific heat of the material). Since u2, can be varied by varying the experimental parameter f, depth pro¬filing by PAS is possible and a number of papers on this subject have appeared in recent years (2-10). Another im¬portant phenomenon is saturation which occurs when the material thickness 1> u> us (1-12).The original promise of PAS for use with powder samples, without the need to ""prepare"" samples as in FTIR spectros-copy, has not yet been fully realized because of several com¬plications. Theoretical works by Monchalin et al. (13) and McGovern et al (14) showed that the interstial gas in the voids of the powders can act as amplifier and that, for the same mass, a finer powder is expected to yield higher PA signal than a coarser powder. Although in a number of earlier studies (15-21) an increase of PA signal with decreasing particle size has been observed, a quantitative check on the equations developed by McGovern et al. (14) has not yet been made. It is necessary to understand the particle size effects in PAS if the promise of PAS for IR spectroscopy of powders is to be realized. In this paper, we report results of a detailed study on the PAS of silica powders for the particle size range of 0.05-260 um and compare the results with theory (14). We have also investigated the frequency dependence of the variousIR modes in these powders and show that the saturation phenomenon affects at least some of the observations. Some observations on the effects of pellet vs powder background are also reported (22-24). Details of these findings are presented and discussed in this paper."

Jan 1, 1990

By J. L. W. Birkinbine

INTRODUCTION. This paper is a discussion of a part of the mineral wealth of the States of Oaxaca and Puebla, Mexico. It does not refer to the precious metals, some miles of which, in these States, are said to have been worked before the advent of the Spanish conquistadores in the sixteenth century, as my purpose is to invite attention to the exploration of deposits of coal and iron-ores in the Mixteca region. The prominence given to coal is warranted by the great effect of the scarcity of fuel upon the industrial development of Mexico. Under the progressive administration of President Porfirio Diaz, the Republic has made wonderful advances in the past three decades; and this progress would have been greater but for the limitations imposed by expensive fuel. In the spring of 1906 I was detailed by the Birkinbine Engineering Offices, of Philadelphia, to accompany A. B. Adams, of New York, in a reconnoissance of reported deposits of iron-ores in the State of Oaxaca. The result of this expedition was the formation, in 1907, of the Oaxaca Iron & Coal Co., of which Mr. Adams became, and has remained, President and General Manager, and I have spent the past three years as Chief Engineer of this company in Mexico, principally in western Oaxaca, where field-headquarters were established. GEOGRAPHY AND POPULATION. Although the geographical anti topographical, features of the Republic of Mexico are well known, few realize that the majority. of its population is domiciled in the States which immediately surround the capital city of Mexico, including the Federal District, Mexico, Tlaxcala, Morelos, Puebla,

Sep 1, 1910

By Anton Sizo, Alexey Klyashtorin

The Gunnar uranium mine operated from 1953 to 1961 on the shore of Lake Athabasca, in 1964 the site was abandoned, and the mine pit flooded. In 1981, the pit was found to be stratified with a chemocline at ~70 m by a sharp change in conductivity and TDS. The uranium concentration was ~700 μg/l on the surface, 320 μg/l at 50 m, and 2,900 μg/l at 110 m. The Ra-226 concentrations were 0.1, 0.06, 0.12, and 0.4 Bq/l. By 2017, the chemocline was ~60 m deep. The highest uranium concentration was 1150 μg/l and the lowest concentration (220 μg/l) was attributed to the chemocline. In the deeper column, the uranium content varied around 750 μg/l. The uranium distribution down the pit profile was aligned with DO, ORP, and TDS. Ra-226 averaged to ~0.4 Bq/l, Ra-226 and uranium profiles were inversely related with the respective maximum and minimum attributed to the chemocline. The uranium and radium amount accumulated in the pit by 2017 was 3,420 kg and 2,163 GBq, respectively. The uranium and radium apparent accumulation trend estimates to 64 kg/y and 41 MBq/y, respectively. A stable chemocline and no concentration gradients in the other parts of the pit suggest that the contaminants are unlikely to inflow from the bottom opening or outside the pit, but rather are mobilized from the pit walls. The contaminants are not in a steady state, and concentrations of both uranium and radium are likely to increase slowly in the future if no remediation occurs.

Jan 1, 2020

By Geoff W. Seward, Charles J. Maes

INTRODUCTION The work of the metallurgical engineer engaged in developing a leach, solvent extraction electro- winning process usually begins in the laboratory and generally proceeds via pilot plant testing before finally resulting in a commercial operation. The path leading to the development of the eventual process will involve a test program on leaching in order to derive information on the amenability of the copper-bearing material to acid dissolution, under various conditions. Commonly in North America the leach process of choice is either dump or heap leaching but it may also be in-situ leaching or the treatment of mine waste- waters and bleed streams. In the past, agitation and vat leaching have also been included in the list of options. Currently the economics of copper production dictate that only material of mineralogy and grade, capable of being leached without prior milling, will lead to a viable process. This is not necessarily true in other parts of the world where grades are higher and milling costs lower and therefore this paper con- fronts all the techniques available to the metallurgical engineer in terms of the evaluation of the solvent extraction process. Understanding the objectives of a laboratory and pilot plant evaluation of a solvent extraction route is important and these are described in some detail in this paper. Of at least equal importance is understanding limitations of such a test program and this aspect of process development is also discussed with reference to the kind of equipment and experimental practices that have been shown to produce results consistent with the objectives. WHERE TO BEGIN? At the inception of a project much information is developed on the variables of the leach process and indeed in some instances the type of leach that best suits the ore to be treated is the subject of intense investigation (Wadsworth 1983). The decision to treat the leach solution by solvent extraction focuses attention on the selection of the extractant most suited to the nature of the chemical composition of the solution. A laboratory screening program will probably need to be arranged in order to assist in narrowing the options and the following is suggested for this initial screening. Selection of a Representative Leach Solution This is preferably obtained from leaching a representative sample of the ore under conditions likely to pertain in the commercial leach circuit. As the conceptualized circuit flow sheet will undoubtedly involve the recycle of aqueous solutions via the leach, then it is desirable to know the nature of and the likely level of the impurity ions in the solution as well as the concentration of copper. The other most important parameter that is required is the free acid (Anon, Acorga Analytical Method) content of the solution. As a rule of thumb, it is always true that recovery across SX is maximized as the pH of the leach solution rises. Whilst a high pH may be desirable for SX recovery, it is not always desirable for the pH (or more correctly, the free acid) of the leach to rise too high. The working range, therefore, tends to be between 1.5-2.5 pH. At an early stage in process development it is likely that a number of ill-defined conditions will exist, making it difficult to decide on typical leach conditions in which case the screening tests should be carried out using a synthetic leach solution prepared from laboratory chemicals. In doing this the copper and free content should be carefully controlled along with the appropriate addition of major impurity ions as their sulphate salts. Preparation of Suitable Organic Solutions Manufacturers information sheets on the reagents to be tested are required at this stage The information necessary to make an informed judgment on reagent performance is: Copper Uptake Value. This will indicate the amount of copper that can be extracted by a reagent as a function of its operating concentration in a

Jan 1, 1986