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By Pancho J. Garza, Keith H. Dahlen, Chris A. Labye

"Design for reconstruction of the East Flagstaff traffic interchange project located in Flagstaff, Arizona posed particular challenges. The proposed design included construction of a nearly 50-foot tall mechanically stabilized earth (MSE) wall given rightof- way constraints and soft subgrade soils. The tight right-of-way, approximately 15 feet in certain locations, adjacent to existing structures limited the number of viable remedial alternatives to provide grade separation at the proposed bridge abutment without significant settlement. Preliminary analyses indicated the existing subgrade soils - consisting primarily of relatively soft silts and clays with decomposed pumice - would settle approximately 12 to 14 inches resulting in unacceptable wall deformation. Stone columns placed via vibratory methods (vibro-replacement) consisting of circular excavations which penetrate to firm bearing soils and which are filled with crushed stone were selected to densify the existing subgrade soils. The implemented mitigation measures helped limit settlement to less than one inch and allow for successful construction of the project. The project history - including site constraints, subsurface conditions, evaluation of remedial alternatives, stone columns methodology, and effectiveness of ground improvements - will be discussed.IntroductionThis paper describes the subsurface investigation performed for the reconstruction of the Business Route 40 (B-40) (Country Club Drive) and United States (US) 89 Traffic Interchange (TI) located within the city limits of Flagstaff, Arizona. This project is currently referred to as the East Flagstaff TI. The Project Site Vicinity Map is shown below.The former B-40/US 89 TI was considered ineffective in handling the current and projected volumes of traffic which transition from northbound (NB) B-40 to US 89 (both directions), as well as from southbound (SB) US 89 to SB B-40. The intent of the project was to reconstruct the TI to better accommodate projected traffic volumes. The project eliminated the existing ramps from both NB B-40 to SB and NB US 89. The new interchange includes a Tee intersection from B-40 to US 89. In order to accommodate this alignment, the profile of US 89 was raised several feet (on nearly the same as existing horizontal alignment) to match the elevated profile of B-40. B-40 was shifted just west of its current alignment to accommodate construction of a new, wider bridge structure which spans over Industrial Drive, the Burlington Northern Santa Fe (BNSF) railway, and old Route 66. South of the new bridge, B-40 transitioned back to the existing alignment just north of the I-40/B-40 TI. Within the project limits, both US 89 and B-40 were widened to three travel lanes in each direction."

Jan 1, 2015

By John F. Wiggert

DURING the early years of Homestake operations, shaft signaling from the cage tenders to the hoisting engineers was done by mechanical means. Small steel cables or jointed steel rods were suspended in the shaft compartments and counterbalanced with weights or springs. These cables or rod strings were connected to the mechanically operated gongs at the engineers' stations by means of bell cranks and steel wires. The system was simple and economical and served the purpose well until the mine reached a depth of 1000 ft., then the system became slow and cumbersome and required a considerable amount of muscular effort to operate it with much speed, because of the inertia of the heavy moving parts. The mechanical signaling was superseded by a simple electrical system consisting of a single pair of wires in steel conduit for each shaft compartment. In the shaft at each station a pull switch was connected to the wires. The switches were operated by means of bell cords, which extended from station to station. This electrical system was a great improvement over the mechanical one, but it had one serious drawback, which also applied to the older system; namely, the engineer did not know where a signal originated. Later on this signaling was improved to overcome this drawback, and to give the engineer a positive indication of a signal's origin. In this system a separate return wire from each pull switch is carried to an annunciator at the engineer's station, where it indicates the signal's origin. While the annunciator system used by Homestake is very safe and reliable, it has the inherent drawback of all wire-connected systems in that it is impossible to send a signal from a moving cage. A number of years ago Homestake became interested in the possibility of using some sort of radio transmission for shaft signaling. The company did much experimental work with purely radio signal transmission, but no practical way was discovered to use radio transmission in a mine shaft for signaling to or from a cage. Therefore, all efforts were directed to devising a practical way of using the hoisting rope as part of the circuit. It was realized that the return circuit from the rope would need to be through electrostatic coupling between the cage and the earth or ground sides of the shaft, because the guides would not always be wet enough to make possible good electrical contact between the cage and earth, therefore relatively high-frequency alternating current was chosen as the medium of transmission. Soon a practical system was developed for transmitting an electric current from a moving cage over an electric circuit of which the hoisting rope was a part. A high-frequency electric current is used as a carrier to transmit the signals or mes-

Jan 1, 1941

By John R. McWilliams

The technological and economic pattern of the U. S. mining industry has undergone a rapid and continuing change since World War II. To provide realistic up-to-date cost data and to disseminate knowledge of technical developments, the Federal Bureau of Mines, with the cooperation of individual mining companies, is presenting a series of mining methods and costs reports similar to those it issued before 1939. Shaft sinking has always played an important part in mine development and [ration] and is an appropriate subject for this series of reports. Shafts [are] especially important in areas such as the Coeur d'Alene district of Idaho, where every major mine is served by one or more shafts and shaft sinking is in progress at one mine or and her almost continuously.

Jan 1, 1960

By H. W. Gillett

MAINTENANCE of membership by the technical so¬cieties and the activity of these societies in spite of the adverse business situation have been noteworthy. This forcibly brings home the fact that industry recognizes that sound technical guidance is well worth its cost. The numerous difficulties and losses due to defects of various kinds arising from gas-metal reactions are now generally recognized and interest in these problems is widespread. The forthcoming A. I. M. E. round-table discussion of gas-metal problems will do much to clarify the situation and will permit us to assay our present knowledge and to suggest the proper direction for profitable future research. "The Age Hardening of Metal" was the title of the annual I. M. D. lecture delivered by Dr. Paul D. Merica. A critical review of the known facts relating to age-hardening phenomena was first given, followed by the presentation of a theory correlating the detailed observations which have been made regarding the mechanism of the hardening.

Jan 1, 1933

By Malcolm Ross

Asbestos crystallizes within rock formations undergoing intense deformation characterized by folding, faulting, shearing, and dilation. Some of these conditions have prevailed during formation of the taconite iron ore deposits in the eastern Mesabi Iron Range of Minnesota. This range includes the Peter Mitchell Taconite Mine at Babbitt, Minnesota. The mine pit is over 8 miles long, up to 1 mile wide. Fifty three samples were collected from 30 sites within areas of the pit where faulting, shearing and folding occur and where fibrous minerals might occur. Eight samples from seven collecting sites contain significant amounts of ferroactinolite amphibole that is partially to completely altered to fibrous ferroactinolite. Two samples from two other sites contain ferroactinolite degraded to ropy masses of fibers consisting mostly of ferrian sepiolite as defined by X-ray diffraction and TEM and SEM X-ray spectral analysis. Samples from five other sites contain unaltered amphiboles, however some of these samples also contain a very small number of fiber bundles composed of mixtures of grunerite, ferroactinolite, and ferrian sepiolite. It is proposed that the alteration of the amphiboles was caused by reaction with water-rich acidic fluids that moved through the mine faults and shear zones. The fibrous amphiboles and ferrian sepiolite collected at the Peter Mitchell Mine composes a tiny fraction of one percent of the total rock mass of this taconite deposit; an even a smaller amount of these mineral fragments enter the ambient air during mining and milling. These fibrous minerals thus do not present a significant health hazard to the miners nor to those non-occupationally exposed. No asbestos of any type was found in the mine pit. © 2007 Elsevier Inc. All rights reserved. Keywords: Taconite; Asbestos; Amphibole; Reserve mining; Tailings; Mesabi iron range; Mineral fibers

Jan 1, 2007

By G. L. Oldright

The first Report of Investigations of the present series (No. 4562) was on the fundamental properties of lead compounds, and the manner in which they set limits to the richness of lead products treated in the usual sintering-blast furnace units. These properties of the compounds were emphasized, as' it was desired, also, to learn the limitations of smelting the same compounds in present ore hearth practice; the hearth has a competitor in these "usual" units, even with the rich lead feeds best adapted for the hearths. Operating conditions that were followed in older metallurgical processes, when rich products, were treated, were outlined. The second report of the series (R. I. 4563) was on the development of the ore hearths of the types now used in the Tri-State from the viewpoint of the features, functions, and dimensions of the earlier hearths that had been most changed. Experimental data, for both well and poorly desulfurized charges being considered, were given to show the relative changes in the sizes and compositions of the charges after they were added to the ore (Scotch) hearths. A general picture was given of the charge column and of the conditions prevailing there when the operation was satisfactory. In this third paper, the composition of the gases prevailing in the charge column at various elevations will be correlated with what has been learned of the nature of the charge column in order to trace the steps of operation by which lead sulfide is converted into metallic lead. The metallurgical factors that govern operation and the lines along which improvements may be made will be noted.

Jan 1, 1949

By L. A. Jordan, D. van Vuuren

A two-dimensional finite difference model has been developed to describe the reduction of kilogram quantities of dehydrated phosphogypsum. The model’s scope has been limited to focus on the heat transfer and reactions that occur within a mass of material contained in a vessel inside a furnace rather than also including the effects of heat transfer to the vessel. Changes in the heat transfer properties (k, ρ, and Cp) are incorporated as the composition of the mass changes as the chemical reactions progress. The model is validated against experimental data, with samples heated to 1000°C at 3°C min−1 while purging with nitrogen gas. A sensitivity analysis of model predictions to the pre-exponential factor of the reaction rate constant of the main chemical reaction and the thermal conductivity of the powder bed indicated that, at the envisaged process conditions, the behaviour of the system depends much more on the rate of heat transfer than on the rate of the chemical reaction. The model demonstrated a significant increase in accuracy when the thermal conductivity was modelled to increase linearly with temperature compared to assuming a constant value.

Oct 1, 2022

By H Arvidson, V Chamberlain, J Joughin, N Pollock, F Cessford, T Flitton, T Rowl

Environmental, social and governance issues (ESG) have become a defining feature in the marketplace to differentiate preferred investments. With the sustainability commitment and reporting landscape anticipated to evolve exponentially, it is now imperative to rapidly develop the approach taken by mineral companies to adequately identify and address ESG risks and opportunities in the reporting of Mineral Resource and Mineral Reserve (MRMR). MRMR cannot be effectively reported as technically and financially assured and realistically executable, if ESG is not integrated into the strategy, business model, input assumptions and process that defines and drives robust MRMR public reporting. Regulatory reporting codes across the globe are presently in various stages of being updated and modified to ensure ESG factors are appropriately covered as a key part of diligent and transparent disclosure. Security exchanges are making it clear that companies must not omit ESG risks from reports to investors. This paper discusses associated challenges for MRMR reporting and suggests avenues for improvement. Key themes include: the importance of procedure rather than prescription and checklists; how ESG criteria impact Modifying Factors and determination of Reasonable Prospects for Economic Extraction (RPEE); the need for financial models to account for material ESG commitments; the uniqueness of each mineral asset; the need for education, upskilling and accreditation of both ESG experts about MRMR reporting and equally Competent Persons in ESG matters; and the need for clear and balanced reports that meet the needs of end users. (RPEE is adopted here for simplicity and consistency, recognising that some reporting codes still include ‘Eventual’ in the term (ie RPEEE). Whilst RPEE and RPEEE are subtly different the intent is to point to the process of assessing ESG factors in determining reasonable prospects.) The principles of transparency, materiality and competence remain paramount when considering the impact of ESG matters on MRMR reporting, and this necessitates an inclusive, cohesive, and integrated approach to assessing ESG issues to ensure the necessary expertise and diligence is applied.

May 24, 2023

By T. V. Simpkinson

Abstract A brief history of the electric arc furnace process of steel-making is given. The greater relative importance of this method of steel manufacture to the Canadian steel industry, as compared with its importance in the steel industry of the United States, is shown. The scope of the process is outlined and brief mention is made of the difficulty of obtaining melting stock low in alloy content. The physical chemistry of steel-making is discussed at length in simple terms, with emphasis on oxidation, de-oxidation, and the role of hydrogen. Carbide-type and silicon-type slags are described and the particular usefulness of each is outlined. The importance of various factors in the melting practice is evaluated on the basis of practical experience. Introduction Although electric furnace steels constitute only a small portion of the total weight of steel used in industrial operations, their importance is relatively much greater than is indicated by comparative tonnage figures. Tool steels, which are vital to all industry, are made almost exclusively by the basic electric arc furnace process, as are stainless steels, valve steels, and the higher alloy types of the class usually referred to as "alloy steels'. For many applications where steel other than electric furnace quality is often used, and when first cost is secondary to performance in service, the extra steel cost of electric furnace quality material is usually returned with interest by consistently longer service life. The electric furnace is pre-eminent in the quality alloy steel field because of the control that may be exercised over conditions of oxidation, de-oxidation, and temperature, the fundamental operations in steel making.

Jan 1, 1948

By P. W. J. Delport, E. Du Toit

Investing in a mining venture can be risky and stakeholders need transparent, unbiased reports to understand the Mineral Resources and Mineral Reserves a mining company holds. Readability and textual choice can be used consciously to manipulate perceptions, or it can be done unconsciously. This exploratory study investigates the readability and textual choice of supplementary Mineral Resources and Mineral Reserves Reports of companies listed on the Johannesburg Stock Exchange. The results indicate that narrative manipulation occurs in these reports through word choices that make the reports difficult to read, as well as specific narrative selections. This reduces the informational value of the reports. The results of the study will be useful to various stakeholders, such as mining company management, investors, investment specialists, financial analysts, and even employees and the general community, who all use these reports to make important decisions. It is also useful for the preparers of the Mineral Resources and Mineral Reserves Reports, Competent Persons, and other technical specialists to be aware of readability and that certain textual choices can affect the interpretation of these reports. It is recommended that bodies such as the JSE and the SAMREC and SAMVAL Code committees consider adding a plain language requirement to regulations, guidelines, and codes to ensure transparent, unbiased, and objective reports.

Mar 1, 2021

By J. A. Finch

In this paper, the author offers a personal view of what the next 30 years holds for mineral processing. Restating that mineral processing will remain a vibrant industry in raw material production, growth opportunities in waste management are identified. The processing sequence familiar now (mining ?mineral processing ?extraction) will become more interwoven. In situ processing (i.e., milling underground) will evolve from concept to demonstration. Opportunities to exploit physical properties altered in chemical (pyro- and hydro-) processing will present themselves. In primary grinding, the path to AG/SAG milling will progress with little deviation but opportunities in regrinding are wide open. Flotation will see the trend to designing bubble/particle reactors accelerate simultaneously with a vigorous response from mechanical cell suppliers. Gravity separation remains a bastion of the lone inventor but this author anticipates that the new lines will come from the waste management business. The paper concludes with the examination of the “research cycle” and identification of growth in small “high tech” companies and university research centres

Jan 1, 1998

By III Scotland

Genstar's underground mine at Texas, MD experienced a failure of the mine roof and subsequent damage to an underground backfill caused by surface floodwaters. A hydraulic backfilling program was developed in house to stabilize temporary repairs to the mine roof, replace 2300 yards of pneumatically stowed backfill, and complete a permanent repair to the mine roof. A flowable backfill material was developed, tested, and later marketed as the result of experience gained during this project. In addition, Genstar personnel developed backfilling techniques to meet the requirements of the repairs and completed work without the additional expense of non company services or contractors.

Jan 1, 1992

By Charles A. Lindberg

Mobile cranes on tires are perhaps the most important accessory in truck-haulage pits. They usually are of 20-ton capacity at short radius and with outriggers but have considerable overload capacity. Standard booms are 30 ft but have 10-ft extensions with which they are usually operated. Cranes have two engines, both originally gasoline, but 150-hp Diesel engines have been found more reliable for the propulsion motor, the 100-hp gasoline motors being retained for hoisting. Pro- visions are made for dropping the ballast counter- weight to reduce axle weights to legal limits for highway travel. The weights are carried on a regular truck or are transported on an extra trailer axle behind the crane. Tractors-Probably equalling the cranes in usefulness are the track-laying tractors which are used to prepare roads and other surfaces, to clean up at the shovel, and for dozing on stripping dumps. A new type of tractor mounted on rubber tires has been tried out on the Mesabi Range for the past year and a half. The advantage of this design is its mobility which makes it capable of taking care of the spill at the shovel and then running to the dump to clean up. Alternating between these two jobs, it relieves heavy tractors that can be used to better advantage on heavier work that does not require so much traveling. This tractor can travel at speeds of 12 to 13 mph and is designed to facilitate repair of the expendable parts. Weaknesses have developed in the internal construction which have seriously marred the performance record of this unit, but when used within its capacity it is quite successful.

Jan 1, 1949

By J. A. Russell

MR. M. W. Boom: I would like to congratulate Mr. Russell on his fine paper. One very good point which has always appealed to me is the smooth working of a steam hoist as compared with electrical. He does not mention the steam hoist at Springhill which has been working there for a good many years. MR. S. R. NEWTON: I have read with a great deal of interest the paper presented by Mr. Russell on the development of haulage engines in the mines of the Dominion Steel & Coal Corporation. He is to be congratulated on having produced a comprehensive article showing, step by step, the various improvements that have been made over the years in the design of such engines. I am quite in accord with Mr. Russell's statement that the positive tooth clutch can have too many teeth, and also that the method of driving a sliding clutch hub of any design should be by means of a hexagon or octagon on the shaft. Where the clutch hub does not of necessity slide on the shaft it can be pressed on and keyed to the shaft in the normal manner. With regard to the 'Cramp' internal-expanding jaw-type clutch, while it is true there are more moving parts than with the clutch consisting of a ring with internal cut teeth and a driver having a fewer number of teeth as .described by Mr. Russell; there are compensating advantages to the internal expanding jaw-type of clutch. The V shaped profile of the teeth permits of engagement of the clutch with very much less 'jockeying' of the drum. This is particularly the case in vertical-lift mine hoists, where it may be necessary to engage and disengage the clutching mechanism at frequent intervals.

Jan 1, 1944

By J. M. Benson

Metal powder compaction offers unique advantages in the manufacture of net-shape components using techniques such as laser sintering, conventional press and sintering, metal injection moulding, direct rolling, direct forging, and hot isostatic pressing. If the output from the primary metal production process is in powder form, then considerable cost and energy savings can be realized by direct conversion to semi-finished or final shapes. This possibility exists for titanium and possibly also for Ta, Zr, Hf, and Nb metals. However, these attractive benefits are associated with some significant risks. The high surface-to-volume ratio of powder particles coupled with the reactive nature of these metals means that special care must be taken when handling them. Powder explosions are unfortunately still a regular occurrence internationally and these often result in serious injury and loss of life. Even seemingly 'safe' compounds such as sugar, flour, and grain can be extremely hazardous when handled or milled and dust clouds are produced. In addition, exposure to airborne particles can have adverse effects on the human body, especially when particles are inhaled on a regular basis. Furthermore, the medical consequences of these are not fully understood, especially in the case of nanoparticles. The impact is often not observed immediately and debilitating illnesses may emerge only years or decades later. As far as is known, there are no South African guidelines for handling of metal powders. This paper attempts to provide an awareness of the risks associated with metal powders (including those produced indirectly by other metalworking/finishing operations) as well as some guidelines for their safe handling, based on international best practices.

Jan 1, 2012

By E. H. Skinner

An abandoned mine shaft near Omar, in Logan County, W, was permanently sealed through a cooperative agreement between the West Virginia Department of Commerce, Labor, and Environmental Resources, Division of Environmental Protection, and the US. Bureau of Mines (USBM), Abandoned Mine Lands (AML) Program. An engineered shaft seal design was developed and demonstrated that featured lightweight concrete as a key material component at a wet density of about 45 lb/ft3. A reinforced concrete cap designed for 5 psi live load was placed over the shaft seal. Applicable new concrete technologies relating to a 100-yr design life were utilized to assure future integrity of the shaft seal. Waterproofing methods were included in the shaft seal design to provide protection from ambient moisture and corrosive mine waters and to increase the long-term durability of the shaft seal. All construction methods used in the field trial are fully adaptable for the mine-reclamation contractor, The USBM research objectives were to develop a broad generic design that will be widely applicable to other adit-sealing and shaft-sealing problems throughout the mining industry.

Jan 1, 2010

By J. M. Singer

Thermal, mechanical, and physical properties of virgin and heat-treated Pittsburgh seam coal were determined as part of a comprehensive study of combustion of monolithic coal block. The information was sought to help characterize pyrolysis and combustion processes in underground coal mine fires but should also prove useful in the study of in situ and surface coal gasifiers. Measured properties include thermal conductivity, specific heat, thermal expansion, density, compressive and tensile strength, porosity, and permeability. The transport property data were obtained (when feasible) in two mutually perpendicular directions of the anisotropic virgin coal material, and coal samples carbonized for 5 hours at temperatures of 350° C, 475° C, 500° C, 650° C, and 850° C. Other coals (Pocahontas No. 3, Sewell, and Illinois No. 6 seams) were investigated for porosity and relative permeability. Interdependence among all properties was evident from the results; however, only a few correlations could be developed owing to inhomogeneity of coal material and specimen variation, which had the effect of reducing the accuracy of measurement and increasing data scatter.

Jan 1, 1979

By W. A. Dunkley, W. W. Odell

About two-thirds of the manufactured gas supplied to the public by the gas plants in the Illinois district is cnrbureted water gas. The leading generator fuel is coke, ma.de in by-product c.oke ovens or in retorts, chiefly from eastern gas coals. During the fall and winter of 1917-18, when the demand for coke by war industries and the restrictions of the Fuel Administration in connection with the transportation of coke from eastern States made it almost impossible for many gas companies to obtain their coke requireml'nts, several water-gas plants had to use bituminous coal as generator fud. Many operating difficulties were encountered, some of which were solved more or less satisfactorily in different plants. A number of plants attacked the problem rather blindly because facilities for making tests were lacking and because technical men were too busy with labor and supply problems to study thoroughly the conditions involved or to ascertain what other plants had done with this fuel. It was therefore with the hope of assisting the gas industry during this critical period, and of promoting the use of Central District coals for gas making, that the Illinois Mining Investigations, a joint agency of the U. S. Bureau of Mines, the University of Illinois, and the Illinois Geological Survey Division undertook the, tests discussed in this paper. • This report was compiled under the auspices of a technical committee appointed by Gov. Frank 0. Lowden to promote the use of Central District coals in gas manufacture as a war measure. This committee included the following representatives of the various agencies concerned: U. S. Bureau of Mines, E. A. Holbrook and W. W. Odell; Illinois Gas Association, C. W. Bradley and R. B. Harper; University of Illinois, Dean C. R. Richards, Prof. S. W. Parr, and Prof. H. H. Stoek; State Geological Survey Division, F. W. De Wolf, G. H. Cady, a.nd W. A. Dunkley. F. W. De Wolf was chairxnan of the committee and E. A. Holbrook was secretary.

Jan 1, 1924

By Ben C. McLellan, Philip J. Bangerter, Andrew Murphy, Glen D. Corder, Damien Giurco

Sustainability now forms a critical part of metallurgical plant design. In addition to compliance with requirements and corporate principles, design engineers must also consider how community and societal responses to the metallurgical industry affect the way they design and build plants. Three broad areas to consider are: the design engineer’s contribution to sustainability through the design process and the relationship to the social license to operate (SLO)—the unwritten license communities give companies to safely and responsibly operate the plant and equitably share benefits; the realization of sustainability goals through methodologies emerging in the design activities; and the integration of design frameworks into a contemporary project design context and its investment objectives. This chapter explores sustainability in metallurgical plant design in the context of SLO, design tools and frameworks, and community and societal influences.

Jan 1, 2015

By J. D. Miller, C. L. Lin

From mine to mill, the 3D characterization of particles ranging in size from meters to micrometers is now possible. A brief review of X-ray tomography for mineral processing is given with recent advances considered, such as high-speed scanning and image analysis procedures to describe important particle properties, including size, shape and composition. Considering these new 3D characterization tools, applications in mineral processing are discussed for high-resolution X-ray microtomography (HRXMT) laboratory analysis of particles ranging from 20 mm to 5 μm, with a voxel resolution of about 1 μm, including (1) multiphase particle characterization by HRXMT and comparison with scanning electron microscopy (SEM), (2) particle damage state as a result of blasting/comminution, (3) liberation characterization to describe expected separation efficiency, (4) exposed grain surface area analysis to explain the flotation of locked particles, and (5) floc size, shape and water content for polymer-induced flocculation. Finally, applications in mineral processing for plant-site analysis using high-speed X-ray computed tomography (HSXCT) are examined, including, for example, coal washability analysis, the analysis of crusher plant products, and the analysis of pebble phosphate products from central Florida. Scanning rates on the order of 1 kg/min for particle sizes ranging from 150 mm to 1 mm are possible, with a voxel resolution of about 100 μm. For coarse particles smaller than 5 to 10 mm, high scanning rates of more than 300 t/h may be possible at a voxel resolution of about 1 mm.