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By Steve Dillingham

Change occurs all of the time. In fact, it’s fair to say that change is a constant. Sometimes the change is inconsequential, but sometimes the change impacts us d i rectly and severely. Take regulations, for instance. Complying with regulatory requirements is just part of the job for those involved with explosives. But in recent years, it seems as if new or revised regulations in areas such as hazardous materials training, drug and alcohol testing, security issues, or local licensing/permitting standards are changing the way we operate on a recurring basis. Simply keeping track of all of these regulations has become a full-time job.

Jan 1, 2003

By N. A. Eilertsen

This paper presents the results of intermittent study begun in 1956 by the Federal Bureau of Mines of yieldable steel arches and yieldable steel ring sets installed for support of development openings in metal mines. Observations were made of this type of support in several iron mines in the northeast and north-central states. The sets, both arches and rings fabricated in the United States, are made from a hot-rolled, cold bent, structural U-shaped steel section in two weights, 15 pounds and 21 pounds per foot. The lighter section is generally used, It is 4.41 square inches in cross section area, and the calculation is that a 6-foot length of this structural shape installed as a supporting column, will safely carry the same load as a Douglas fir post of the same length but of 22 times the cross-sectional area of the steel.

Jan 1, 1962

The ability to optimise a concentrator from mill feed to final products requires a simulator which integrates comminution, classification and separation modelling. In order to model this range of processes, such a simulator must handle a variety of information about the ore. The AMIRA P9 project has developed a whole-of-concentrator simulation capability which brings together a texture-based model of mineral liberation, quantitative X-ray micro-tomography analysis to measure the inputs required by this model, and a multi-component simulator software framework. In the context of this approach, the term ?multi-component? implies the ability of the simulation to handle many particle properties simultaneously; for example size, composition, density, floatability etc. The simulation software framework provides the means to manage the flow of data around a circuit flowsheet, allowing each process model to access the information relevant to that particular model. A case study based on plant data from a gold-bearing pyrite concentrator is used to demonstrate the capabilities of the multi-component approach in simulating circuits which contain comminution and separation processes.

Feb 27, 2013

By J. Leja, J. H. Schulman

FROTH flotation is usually effected by the addition of a collector agent and a frothing agent to an aqueous suspension of suitably comminuted mineral ores. The action of collectors is to adsorb onto the surfaces of minerals to be separated, sensitizing them to bubble adherence. The action of frothers has, in the past, been accepted as that of froth formation only, brought about by a lowering of the air/water interfacial tension. Substances capable of producing froth are classed1a,b according to their relative capacities for production of froth-volume and froth stability in the simple frother-water system. The purpose of this paper is to show that the surface active agents acting as frothers become effective only when there is a suitable degree of molecular interaction taking place between collector molecules and frother molecules at the air/water and solid/ water interfaces. Further, the discussion will demonstrate that the actual mechanism of adherence of an air bubble to a suitably collector-coated particle is due to the molecular interaction collector-frother. This leads to the formation of a continuous interfacial film of associated molecules, anchored to the mineral by polar groups of the collector, and enveloping the whole bubble. The tenacity of adhesion mineral-to-bubble results from the strength and the visco-elasticity of this mixed film.

Jan 2, 1954

By E. S. Leaver

The gold that is not recovered by a particular process is refractory to that process. A study to determine how the refractory gold is associated in the ore constituents usually indicates the needed improvement in the process or additional methods for bettering recovery. In preliminary work, segregation of the various minerals, gangue or impurities, and data showing the reactions of each in the recovery method readily confines the refractory gold to a certain part on which extensive research can be directed. In this dissecting plan, the microscope is an important aid in locating the refractory gold but should be supplemented by chemical tests.

Jan 1, 1934

Decrease dust concentra¬tions of longwall face workers by keeping them up¬wind of the headgate stage loader and crusher. Approach Direct the face airflow from tailgate-to-headgate, the direction of coal transport. How It Works Ventilation is the primary method of dust control on longwall faces, and the most effective ventilation control is to put workers upwind of dust sources. Recent ad¬vances in longwall dust sampling by the Bureau have shown that on some faces, the headgate crusher and transfer points are signifi¬cant sources of dust -some¬times making up more than half of the total dust to which the face workers are exposed. Also, when the air is coursed from head-to-tail, the relative velocity between the air and moving coal on the face conveyor can cause dust entrainment from the conveyor, particularly if the coal is dry. On the faces where these dust sources are a signifi¬cant problem, they may be eliminated by coursing the air from tailgate-to-headgate, provided that the mine roof is stable enough to permit the necessary intake of the tailgate along with an aux¬iliary intake at the headgate.

Jan 1, 1982

By Agus Setiabudi

East Pit Wira II Project in South Kalimantan, Indonesia with a radius of <500 meters (1,640 ft) from residential has about 454,168 tonnes of coal reserves, with a total remaining reserves of 3,369,383 tonnes (topography per end of June 2011). Thus, reserves may be lost as much as 13.48%. Therefore, it is needed to determine safe blasting technique which meets the Indonesian National Standards (SNI) No. 7571:2012 of vibration threshold, the maximum vibration of 3 mm/s (0.118 in/s) and air blast of 120 dB.

Jan 1, 2014

By James F. Kemp

(San Francisco Meeting, September, 1915) THE iron ores of southeastern Cuba present a subject of exceptional geological interest. Their relations to the inclosing rocks are varied and in some cases unusual. The problem of their geological origin is not a simple one and for this reason has occasioned some divergence of views among previous observers. Profiting, however, by. these earlier studies and by more detailed field and laboratory observations as well as by the experience of added years of mining, much more satisfactory descriptions and interpretations can now be prepared. PREVIOUS WORK In 1884, interest in the southeastern coast of Cuba became active among the consumers of iron ore along the Atlantic seaboard of the United States. Active development was undertaken by the Juragua Iron Co., Ltd., a corporation affiliated with the Bethlehem Steel Co., and the Pennsylvania Steel Co. The property of the Juragua company, which is situated about 15 miles east of Santiago, was studied in June and July, 1884, by Dr. James P. Kimball, at the tine Professor of Economic Geology in Lehigh University and one of the best known of American mining geologists. Dr. Kimball published on his return two papers, the first important descriptions which we have of the local geology.1 It is

Jan 9, 1915

By S. Dixon

The Peñasquito deposit in Mexico is one of the largest grassroots precious metal discoveries to be developed in recent years Minera Peñasquito, S.A. de C.V., a wholly owned subsidiary of Goldcorp Inc. has developed the Peñasquito property to produce an average annual production of 120 kilo tonnes of lead containing 0.5 million oz gold and 30 million oz silver and 250 kilo tonnes of zinc containing 20 thousand oz gold and 1.5 million oz silver.. The Peñasquito property covers a 39,000 hectare area in the western half of the Concepción del Oro district in the northeast corner of Zacatecas State, Mexico, approximately 24°45&apos;N latitude/101°30&apos;W longitude. The sulfide reserves are 1,009 million tonnes containing 3.33 million tonnes of lead, 7.26 million tonnes of zinc, 16.5 million ounces of gold and 1,000 million ounces of silver. This paper describes the work to justify the installation of HPGR to process the crushed SAG mill pebbles. The SAG mill-Ball mill and Cone crusher (SABC) grinding circuit is an accepted grinding circuit to optimize power consumption relative to throughput. The installation of a HPGR to process the Cone crusher product is the next step in optimizing the power consumption relative to throughput. The concern expressed by some on not moving on this change in grinding circuit was the capital and operating cost of a HPGR. The pebbles from the SAG mill can be the more abrasive and are the harder particles of the ore. Goldcorp investigated the wear and processing costs of installing a HPGR to treat the crushed pebbles. The conclusion was the installation would be a very positive economic factor in the operation of Peñasquito. This is the first application of the use of HPGR to process crushed pebbles. Minera Peñasquito and M3 Engineering selected Polysius to provide a Polycom 2417 with twin 3,000 kW drives. A comprehensive test program at Polysius has shown for 7% higher circuit power it is possible to get approx 23% higher tonnage. This coupled with full utilization of the SAG and Ball Mill available energies and with proper control of the transfer size from the SAG to Ball mill circuit there is the potential to achieve 65,000 mtpd per line or a 30% total capacity increase. The cost of power for this increase in grinding capacity is 4.8 kWh/tonne.

Jan 1, 2010

By B. T. Lu, J. L. Luo, J. F. Lu

The present paper investigates the chemo-mechanical effect in slurry-erosion corrosion process of carbon steel to understand the synergistic mechanism due to interaction of chemical and mechanical factors. The erosion-corrosion tests were conducted with A1045 steel in slurries comprising tap water and silica sand. Various heat treatments were adopted to achieve different hardness in the test material. The chemo-mechanical effect is evaluated in line with the correlation between the degradation of hardness in the surface layer and anodic current density. During the erosion-corrosion tests, various anodic currents were applied to find the relation between the anodic dissolution rate and erosion rate. The experimental results indicate that the hardness decreased with increasing anodic dissolution. Based on the fact that pure mechanical erosion rate increased with decreasing hardness, this result suggests that the corrosion-induced degradation of mechanical property is a mechanism of corrosion-enhanced erosion. This theoretical prediction is verified by erosion-corrosion experimental results.

Jan 1, 2004

By S. H. Ward

Since the advent of the first airborne electromagnetic system, it has been evident that such systems were inherently limited to shallow depths of exploration of the orderof 100 to 200 feet. Hence in 1948 the author and his associates commenced a study of the feasibility of applying natural audio frequency magnetic fields to investigation of the electrical properties of the subsurface in order to provide a system capable of overcoming this limitation. This research culminated, in the summer of 1958, in the development of a new airborne prospecting device — AFMAG. This device has detected surface massive sulphide bodies while flown at heights as great as 3000 feet. Hence, by inference, it is deduced that it could find similar sulphide bodies if they were buried 2500 feet below surface and the aircraft flown at 500 feet. Thus a considerable improvement over conventional airborne electro-magnetic systems is obtainable with AFMAG. Airborne exploration in mountainous terrain involving deep valley fill now becomes possible. Examples are presented of the results of actual airborne AFMAG test surveys over known deposits of massive sulphide mineralization. Interpretation of the data is discussed with particular reference to the knowledge of size, dip, depth, depth extent, and conductivity of causative bodies as deduced from the flight records. The possibility of mapping major geologic structures, for both mining and oil exploration purposes, is discussed with the aid of examples of airborne AFMAG data. INTRODUCTION Electrical prospecting with natural audio frequency electromagnetic waves as a source has, within the last three years, become a practical reality. Both airborne and ground survey instruments under the trademark "AFMAG" (for audio frequency magnetics) have been used successfully in the search for conductive mineral deposits. It is the object of this paper to discuss the principles of airborne AFMAG and to illustrate its application by means of examples obtained over known geological situations. WHY AFMAG? In view of the large number of good airborne electromagnetic systems available for purchase or contract surveying, one may well ask, "Why another new system?". Primarily the answer lies in the fact that AFMAG does not suffer from the very limited depth of exploration available with, and inherent in, any conventional airborne electromagnetic system. AFMAG is not conventional insofar as an artificial transmitter is not required. Only a receiving and detecting device is employed. The electromagnetic fields measured are those from millions of electrical discharges in the atmosphere (e.g;..- lightning strokes). Their random distribution in time and space make these fields difficult to employ and it is only with recent advances in the electronics of geophysical instrumentation that this has become possible. A second reason for AFMAG and one of its

Jan 1, 1961

By Mark Fennel

The present paper describes the operation and application of the QEMSCANTM automated applied mineralogy technology and how it is been utilized for long range planning by characterizing and optimizing the primary sulfide reserve while providing operational support of the ongoing secondary sulfide leaching operation at the Cerro Verde Mining Complex in Arequipa, Perú.

Sep 12, 2005

By G. B. Atkinson

To develop technology to help assure an ample domestic supply of zinc, the Bureau of Mines is investigating an aqueous chlorine-oxygen leaching process for treating complex sulfide concentrates. This report discusses the purification of aqueous C12-02 leaching solutions by utilizing zinc cementation to remove Cd, Co, Cu, Ni, and Pb. Additional processing of the purified solution is necessary to produce ZnC12 crystals suitable for molten-salt zinc electrowinning cells. The effects of solution temperature, reaction time, zinc dust concentration, ZnCl2 concentration, and degree of agitation on the removal of impurities were investigated for both simulated and actual leaching solutions. Zinc dust addition to a leaching solution at 30° C decreased the Cd, Cu, Ni, and Pb concentrations to acceptable levels of less than 3 mg/1 each. By increasing the solution temperature to 75° C, the cobalt content was decreased to less than 5 mg/l, an acceptable level for producing electrolytic cell-grade ZnC12. Impurity removal rates from ZnCl2 solutions are Pb>Cu=Cd>Ni>>Co. An increase in the solution temperature increases the rate of removal for these metal impurities.

Jan 1, 1982

By M. B. Mirza, F. D. Wright

Models of photoelastic material were made to simulate a mine roof that had cracked over the edge of the pillars and at the center of the span. Models were restrained from moving laterally outward so they acted as flat arches. Uniform loading was approximated by loading the models along the bottom at eight points spaced equally along the span. It was found that for models with depth to span ratios of 1:3 to 1:6, the maximum stress at the top of the center crack could be calculated directly by the following formula: Elastic stresses in mine roofs composed of sedimentary beds are usually computed by assuming that the immediate roof bed acts as a fully restrained beam uniformly loaded by its own weight and by overlying strata. Very little work has been done to analyze stresses in roof beds or beams which contain vertical (normal to the span) or nearly vertical cracks. Yet every mining engineer has walked safely under roofs that show such cracks. As far back as 1933, Bucky&apos; made model studies of the effect of vertical cracks on the behavior of horizontal strata. He did not make any analysis of the stresses but did show that a cracked beam will stand safely under certain conditions, and also showed that a beam restrained at the ends can crack over the supports and in the middle without collapsing as long as the ends of the beam are not free to move laterally outward. The beam, or rather, part of the beam, acts like a flat arch and supports itself by pushing outward at its supports. In 1941 Evans2 treated analytically the problem of a beam cracked along so many planes perpendicular to the axis of the beam that no tensile stress can operate. He named this type of beam a "voussoir-beam" by analogy to the voussoir-arch. In 1962 ~a~cocks~ modified Evans&apos;s solution by including the effect of the shear stress component of the resultant force at the abutment. This paper gives the results of a photoelastic study of the stresses in a beam containing vertical cracks in the center of the span and over the supports. A

Jan 1, 1963

By Kenneth N. Han

Ammonia has been found to be an effective leaching reagent for gold, silver and platinum group metals in the presence of appropriate oxidants. Electrochemical and kinetic aspects of the dissolution of elemental gold in ammoniacal solutions have been investigated. The cathodic reaction of aurous di-ammine on the gold cathode has been investigated first. From this investigation, the standard electro-potential of the cathodic reaction .and hence. the Gibbs free energy of formation of the aurous di-ammine were established. The solubility of gold in ammoniacal solutions was also examined in relation to ammonia concentration, temperature and concentration of various oxidants. The anodic reaction of the gold disk in ammonia? in the presence? of various oxidants including oxygen, ozon, hypochlorite, hydrogen peroxide, cupric and cobaltic ammine, and iodine was also examined and the results have been discussed. Excellent dissolution yielding of gold and many other metals, typically better than 95% recovery in 1&apos;-2 &apos;hours of leaching at a temperature ranging 80°C to 190°C has been observed. Test results of the dissolution of gold from elemental state as well as other sources including sulfidic ores and scrap are presented.

Jan 1, 1998

By K. Collett

Elandsrand started shotcreting back in 1991. This paper will share the experiences of the mine by looking into the past, the present situation and the way Elandsrand plans to approach the future. It looks at the application of drycrete and discusses the factors that led to the introduction of wet fibre reinforced shotcrete. The logistical constraints of getting shotcrete material underground will be solved by the development of an underground batch plant, using run of mine waste rock as an aggregate.

Jan 1, 1998

Jan 1, 1967

By Hamid Maleki

A geotechnical monitoring program has been implemented at Energy West Mining Company for enhancing site-specific evaluation of longwall stress conditions. This program consists of underground measurements at five locations in two neighboring mining districts located in the Hiawatha and Blind Canyon Coal Seams under moderate to deep cover. Within the last five years, additional measurements, including data on recorded seismic events and face conditions, have been incorporated into the data collection program together with detailed geologic mapping of longwall gateroads. In conjunction with the measurement program, the authors have completed detailed boundary-element stress analyses of the mine plans. Models have been calibrated using the data from in-mine instrumentations and then routinely used for evaluation of mine plans at depths approaching 2,600-ft. The work has improved our understanding of load transfer, seismicity and yield pillar performance. It has identified areas of potential increased stress levels at certain longwall face positions and provided guidance to measures that could be considered to mitigate the potential for these increased stress levels.

Jan 1, 2009

By James M. Tantalla, Dwight Metcalf, Roderic A. Ellman Jr.

"The construction of a new low head hydro-electric plant at the Cannelton Lock and Dam required the design and construction of a cofferdam to accommodate a deep excavation extending approximately 150 feet below the Ohio River levels. The new plant, which generates about 390 GWh of electricity annually, is owned by American Municipal Power (AMP). A specialist team was assembled to design and construct the cofferdam, marine dike and CB slurry wall that helped make the project successful and on time for project delivery.Because the new plant diverts water from the locks and dam through a powerhouse to generate power, it would need to be partially in the river to operate properly. To accomplish this, approximately 250,000 square feet of land was reclaimed from the river by construction of a marine dike. The dike, combined with the design and construction of a 150 foot deep cement bentonite (CB) cutoff wall enabled construction of the new plant in the dry. Extensive dewatering analyses were performed using Modflow to evaluate pumping requirements and the number of wells needed to maintain ground water at required levels within the side slopes and final subgrade. A monitoring program consisting of inclinometers, piezometers and movement monitoring points were used to monitor cofferdam stability and performance throughout construction. Detailed two and three dimensional stability analyses that included a parametric study of fluctuating river levels and slurry unit weight were performed to ensure stability and suitable low permeability of the trench during cut-off wall excavation both on land and in the marine dike. The wall was constructed with both a hydromill excavating primary panels and a clamshell following behind to construct secondary panels. Data acquisition systems onboard the excavating equipment allowed for detailed confirmation of the continuity of the wall at each interface between panels. Another challenging aspect was the CB mix design for the trench. The cofferdam required the construction of a 1,300-foot long marine dike downstream of the existing dam up to 100 feet tall founded on existing river sediment to enclose the site and cut-off the seepage into the excavation from the river. Marine dike construction utilized vibro-compaction to pre-densify granular fills placed underwater through which the CB trench extended."

Jan 1, 2016

By P. Marier, T. R. Ingraham

When anhydrous cupric sulfate is heated in a stream of nonreactive gas, cupric oxysulfate is formed. When this reaction is complete, the cupric oxysulfate then decomposes to cupric oxide, which is the normal end product of reaction. The kinetics of each of these reactions has been studied using pellets prepared from finely divided cupric sulfate and from finely divided cupric oxysulfate. In each case, the reactant-product interface within the pellet is well-defined, and by normalizing the decrease in inter facial area with the weight fraction of the pellet decomposed it has been shown that the interface migrates into the pellet at a uniform rate at constant temperature. The activation energy estirnated for the decomposition of cupric sulfate is 57 ± 7 kcal per mole and that for cupric oxysulfate is 67 ± 8 kcal per mole. The rate of interfacial reaction is flow-sensitive, increasing with increasing flow of a sweep gas in the range from 50 to 2000 cu cm per min. The rate of decomposition is retarded by sulphur trioxide in the sweep gas. The relationship between sulfur trioxide Partial pressure and rate is consistent with the Langmuir Adsorption Isotherm governing the retention of sulfur trioxide in the interfacial layer. MOST of the work reported on the thermal decomposition of cupric sulfate and of cupric oxysulfate is related to the thermodynamics of the individual decompositions.&apos;-4 No information is available on the rates of the individual reactions, on their activation energies, or on the effects of gas flow or of partial pressure of sulfur trioxide on the reaction rates. Some dubious conclusions based on relative reaction rates have been drawn from studies on the oxidation of sulfides. For example, on the basis of the products observed in a quenched system, it has been suggested5" that, when copper sulfide is roasted, the cupric oxide which is formed arises from the decomposition of either cupric sulfate or cupric oxysulfate. This is very difficult to reconcile with the thermodynamics of the C-S-O System,3 which support the probability that both cuprous oxide and cupric oxide precede cupric oxysulfate and cupric sulfate in the sequence of products formed during the oxidation of cuprous sulfide. In this paper the individual sulfate decomposition reactions will be examined and suggestions will be advanced for the mechanism of reaction. This will be based on the effects on reaction rate of changes in interfacial area, flow rate, and back-pressure of sulfur trioxide. EXPERIMENTAL Materials. The copper source material used in all experiments was Fisher Certified Reagent Grade anhydrous cupric sulfate, for which the following analysis was supplied by the manufacturer: chloride, 0.002 pct; alkalies and earths, 0.2 pct; insoluble, 0.002 pct; iron, 0.020 pct. Cupric oxysulfate was prepared by roasting cupric sulfate for 48 hr, with frequent rabbling, in an open tray in a muffle furnace maintained at 725°C. At this temperature, cupric sulfate develops about 0.16 atm pressure of combined sulfur trioxide, sulfur dioxide, and oxygen. Cupric oxysulfate develops only about 0.05 atm pressure, and is stable until

Jan 1, 1965