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By J. E. Sepulveda, R. Morrow

"In full scale mineral grinding operations, the steel balls normally utilized as auxiliary grinding media get to be consumed at different specific rates, as determined by 3 basic mechanisms: abrasion/corrosion (wear), impact ball breakage and impact surface spalling, the latter relating to the removal of rather small pieces of steel coming off the exposed surface of the balls due to repetitive impact with other balls in the charge or the surrounding mill liners. In conventional ball milling applications, the clearly predominant mechanism is gradual wear by abrasion/corrosion. In the case of SAG mills, where the make-up balls may be as large as 6”f diameter, breakage and spalling mechanisms are significant contributors to total ball consumption, although not to the extent of overriding wear mechanisms.Ball wear has been well characterized by the Linear Wear Theory, as presented at the last CMP 2014. Impact breakage has been customarily monitored, at the ball manufacturing site, via Drop Ball Tests (DBT) consisting of repeatedly dropping balls from a standard height and accounting for the number of broken balls and the weight loss (spalling) of the remaining unbroken balls. When properly conducted, DBT’s should provide meaningful indications of the breakage and spalling resistance of large diameter balls. The current publication is focused on the interpretation and projection of DBT results to full industrial scale, taking into account all 3 mechanisms of grinding media consumption in SAG mills.INTRODUCTIONA thorough, quantitative understanding of the independent contribution of all active grinding media consumption mechanisms is of the highest practical relevance, particularly in semiautogenous (SAG) milling operations where ball breakage and spalling can not be ignored or neglected, as it has been normally acceptable for conventional ball milling processes. The high severity impact conditions currently imposed in typical SAG mill environments create serious challenges to the manufacturers and suppliers of large diameter (5”–6”) SAG balls, whose products must be capable of surviving such harsh operational conditions with minimum breakage or spalling."

Jan 1, 2015

By C. J. Johnson, C. J. Bise

Abstract - As the US coal industry moves into the next century, it is becoming more apparent that the effective application of new technology is the only way it can remain competitive in the energy marketplace. Examples of this emphasis are with us today in such diverse areas as face- ventilation and excavation-equipment applications. The focus of this new technology is directed toward improvements in health and safety, cost control, and productivity. Room-and-pillar mining accounts for approximately 68% of the nation's underground coal production; this percentage is not expected to decrease markedly in the near future. As such, this paper analyzes the impacts of the changing techno- logical climate on future room-and-pillar operations by comparing a base-case section (current) to three scenarios incorporating new or emerging technology. A microcomputer-based comparative analysis will reflect the changes in section production and costs.

Jan 1, 1990

By Peter F. Steidl

As part of the Bureau of Mines methane control program, the Upper Free-port coalbed was studied in Fayette County, Pa., where this coalbed lies about 650 feet below the Pittsburgh coalbed and contains the largest remaining reserves of any coalbed in the county. Its estimated recoverable reserves in Fayette County are between 670 and 800 million tons. Coal and overburden isopachs, structure and joint pattern maps, and a fence diagram were prepared using data from gas and oil exploration logs and coal outcrops. These maps will aid in determining the need and/or feasibility of degasifying the Upper Freeport coalbed in the study area. Much of the coalbed in this area is under 600 to 1,400 feet of overburden. By correlation with data from the Pittsburgh coalbed, the gas content at depths of this order is estimated to be between 140 to 300 cf/ton of coal.

Jan 1, 1977

By Niels Verbaan, Ron Molnar, David Dreisinger

"An acidic chloride leach solution was generated from the treatment of an ore containing the following value elements: silver, gold, indium, gallium, copper, zinc and lead. Iron was also co-extracted into solution as a ferric chloride species. Iron extraction was a significant component of the overall acid consumption of the leaching process. The recovery of iron by solvent extraction and water stripping was investigated. Tri-butyl-phosphate (TBP) was very effective at recovering iron from the leachate. The water strip solution could be decomposed to produce ferric oxide (hematite) and hydrochloric acid for recycle via hydrothermal hydrolysis or pyrohydrolysis.INTRODUCTION The Malku Khota deposit is situated in the eastern part of the Bolivian Altiplano at elevations between approximately 3,800 and 4,580 meters above sea level (Figure 1). The project is located 98 km east-southeast of Oruro, and 85 km south of Cochabamba in a relatively remote area."

Jan 1, 2016

By Kristine L. Pankow, Keith D. Koper, Michael K. McCarter, Jared R. Stein

"The Wasatch Plateau region of central Utah contains a number of active underground coal mines in an area of well-documented natural seismicity. As a result, there are several hundred seismic events recorded in this region every year that may or may not be attributed directly to mining activity. Previous studies have linked the majority of this seismicity to mining activity through various means, but have not attempted to develop a method for categorizing individual events within a seismicity catalog. This study uses both relative relocation and waveform cross-correlation to separate events based on hypocentral depth and waveform similarity, respectively, in the area surrounding a single longwall coal mine within the Wasatch Plateau. We conclude that relative relocation can help with depth discrimination, but there are some unavoidable limitations caused by sparse seismic network coverage. The cross-correlation technique is more promising, with the ability to group events by waveform similarity and track mining progress over both space and time. With cross-correlation based clustering, we confirm that the vast majority (97.6%) of events in the study area are directly related to mining activity, but that a small population of natural seismicity is present as well. Eliminating this natural seismicity from the catalog of seismic events, leaving only those events related to mining, can give operators valuable information about the changing conditions as mining progresses and eliminate concern over events unrelated to mining activity.INTRODUCTIONA number of underground coal mines are located in the Wasatch Plateau region of central Utah, and have been in operation since the late 1800s. This activity has resulted in a well-known history of mining induced seismicity (MIS) (Wong, 1985). Additionally, this area is situated near the border of the Basin and Range and Colorado Plateau physiographic provinces, where naturally occurring tectonic earthquakes also occur (Arabasz et al, 1980). Seismicity separating these physiographic provinces is part of a larger band of seismic activity known as the Intermountain Seismic Belt (ISB) that runs from Montana to Arizona and cuts through the western boundary of the central Utah coalfields (Smith and Arabasz, 1991) (Figure 1)."

Jan 1, 2015

By Robert B. Hopler

"The story of packaged explosives begins with the use of black powder (also called gunpowder) in mining. Although discovered in the 13th century, it was not until 1627 that the first records of use in mining is recorded. It took until the early 1800's before its use began in underground coal. Althougha free-running, granular material, its recommended (and safest) manner of use was for the miner to pour it into ready-made or onsite formed paper bags prior to insertion into the borehole. This was absolutely necessary in horizontal or upward-slanting holes."

Jan 1, 1991

The process of resource estimation of large precious metal deposits is illustrated by reference to major deposits now being mined or developed by Placer.The estimation procedure commences with building an appropriate model of the mineralization and proceeds through steps of data validation and geostatistical studies. It is important that the geologists most familiar with a deposit be involved with all stages of the estimate, and also prepare a manual estimate used to validate the kriged resource.Resource estimates are major exercises taking many man-months of work. The most time consuming part of this is usually construction of an appropriate three dimensional geological model. The data base for the resource calculations must be complete and checked for accuracy. The most appropriate estimation method must be selected.

Jan 1, 1990

By Charles O. Thomson

When a wire rod of iron or of steel is immersed in a hot solution of common salt, allowed to remain long enough to bring the metal to the temperature of the brine, and withdrawn, the surface of the rod is irregularly covered with a deposit of crystals of salt. These crystals adhere to the cod with great firmnes, in consequence, doubtless, of a thin film of ferric hydrate, which is formed between them and the rod as the water dries off. The rod can now be reduced, by successive passes through a dic or draw-plate, without any

Jan 1, 1881

In 1975 the US Bureau of Mines (BOM) under contract with the Bureau of Indian Affairs (BIA), began a systematic mineral resource evaluation of Indian reservations in the United States. The purpose of the BIA/BOM program was to stimulate economic development on Indian lands through exploration and mining ventures with the mining industry. Since that time, 109 phase I reports (literature studies) and nearly 45 phase II and phase III (field studies) reports have been written by the BOM. The various tribes in conjunction with the BIA have access to these reports for decision making regarding mineral resource development.

Jan 1, 1990

By Thomas J. Peters

In 1988, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 5,640-acre Soda Mountain Wilderness Study Area (OR-011-017), in order to evaluate its identified mineral resources. The study area is located in Jackson County, OR, about 30 miles south-east of Medford. The study area covers most of the south-facing slope of 6,071-ft Soda Mountain. Geologically, the area is underlain by Oligocene to Pliocene basaltic andesite flows and less extensive intrusive rocks of the western Cascade Mountains. In addition, there is a 3/4-mile-diameter area of kaolinized and silicified rhyolite tuff, which appears to have intruded the andesite, and is host to epithermal gold mineralization.

Jan 1, 1989

By Blake M. Caldwell, Thomas C. Poulter

A new approach to an old problem has made it possible to do in a a tively short period what has not been accomplished in the past three quarters of a century using strictly experimental methods. A theoretical study was made of the underlying principles whereby a jet is formed by a shaped charge and of the mechanism of the penetration of the target by that jet. It was found that there are more than 10, and perhaps as many as 15 variables affectin!? the performance of the shaped charge. Only a few calculations are necessary to show that it is physically impossible to investigate all of these variables experimentally. The shaped charge theory has been extended to include a previously little-understood mechanism in high explosive phenomena; namely, low order detonation. By superimposing a high order detonation on a zone already undergoing low order detonation, all appreciable improvement in performance is accomplished. The development of a design wherehy these phenomena are coordinated in such a way as to develop a jet which is tailored to meet the specific target requirement will be described in detail. The shortcomings or even impossibility of strictly experimental techniques will be illustrated by a discussion of the development of a special-purpose explosive charge. INTRODUCTION In an article appearing in the May, 1888 issue of Scribner's Magazine, Charles E. Monroe described his early experiments with gun cotton (Fig. 1) which led to his name being most fre-quently connected with our present-day shaped charge. Although the sunken letters or "cavities" in Mon- roe's gun cotton were not lined, they produced some penetration of an iron plate. The credit for the lined shaped charge, however, should rightfully go to Dr. R. W. Wood of the Physics Dept. of Johns Hopkins University, who was responsible for first discovering the fact that a metal liner in a cavity of explosive gave high velocity fragments and/or jets of metal. This discovery was made by Dr. Wood inadvertently while investigating an accidental death resulting from an electric blasting cap. He discovered that a jet of high velocity copper particles was ejected from the dimple

Jan 1, 1958

Cobar Mines Pty. Limited (CMPL) uses sodium sulphite as the principal depressant to attain selectivity in copper flotation prior to sequential recovery of lead and zinc. The usage of sodium sulphite is examined both from a theorectical viewpoint ana from the manner in which the copper circuit at (MPL has developed. The results of relatively recent investigations, both in the laboratory ana the plant, are discussed aria shown to support the present operating Techniques.

Jan 1, 1983

By Sam S. Taylor

"INTRODUCTION This report deals with a comparatively simple application of some of the engineering principles involved in the evaluation, installation, and operation of air- or gas-injection projects and well-clean-out and repair methods to increase the producing rates of oil wells in partly depleted pools during the war. The methods suggested for developing gas-injection projects take into consideration that in general no new wells will be drilled because of wartime restrictions of equipment and manpower and that only existing wells and second-hand machinery will be used. Because air will be employed as the injection medium in secondary-recovery operations where natural gas is scarce and expensive, the disadvantages and hazards accompanying, its use are discussed. Engineering techniques recognized as best modern practice are discussed in relation to the effect of simple air-injection development of properties on postwar operations and Probable ultimate recovery of oil. The report is an introduction to where, when, why, and how an air-injection project should be installed and operated; it is not intended to be an engineering manual for technical guidance in the selection, development, and operation of simulative methods of oil recovery.The report is intended mainly for these thousands of operators in the Appalachian region owning a few wells prodding small quantities or oil daily. Many such operators are anxious to increase their production rates by simulative means and to rehabilitate their wells so that they will produce more oil to help win the war but, in general, are unfamiliar with secondary-recovery operations and cannot afford to hire technical assistance."

Sep 1, 1944

By L. C. IlsLey

Coal mining is more widely distributed throughout the United States than is generally known, as 30 States are credited with having coal mines. In 1919 twenty-three of these States each produced at least a million tons of bituminous coal, and all the States produced about 560,000,000 tons. In addition, Pennsylvania produced about 85,000,000 tons of anthracite. Twenty-eight States have regulations prepared by commissions or have enacted laws governing the operation of coal mines. Pennsyl¬vania has separate codes for the anthracite and bituminous fields. The codes may be classified as follows: Twelve distinctly coal¬mining codes; eight codes that are essentially coal mining, but also apply to other mines; five codes that are subdivided, referring partly to coal mines and partly to other mines; and four codes that are essentially metal mining, but apply in part or in whole to coal mining. The first State to have a coal-mining law was Pennsylvania, which enacted a law, for Schuylkill County only, in 1869. The first State to enact a coal-mining law governing all the coal mines in the State was Illinois in 1872, followed by Ohio in 1873. Pennsylvania in 1879 enacted a law for anthracite mines only, but did not enact similar laws for bituminous mines until 1577. At least 10 other States enacted coal-mining laws between the years 1870 and 1890. Before 1890 electricity was little used in coal-ruining operations and therefore practically no provisions governing the installation, inspection, or maintenance of electrical equipment were made in any of the laws enacted up to 1890. In the law of Colorado, approved April 8, 1885, there is a reference to the use of telephones, probably the first reference to electrical equipment of any kind in a State-mining code. Most of the mining codes have been changed from their original form by amendment or by complete revision. In some of the early changes a casual reference is made to the use of electricity or to the handling of electrical equipment. In 1911 Pennsylvania added

Jan 1, 1920

By Xia Hong-ying, Peng Jin-hui, Zheng Zhao-qiang, Zhang Li-bo

"Preparation of activated carbon from the walnut shell by microwave assisted steam activation was studied. Influences of the three parameters, activation temperature, activation duration and steam flow rate on the adsorption capacity and yield of walnut shell activated carbon(WSAC) were investigated,optimization process was obtained by the Response Surface Methodology (RSM). The optimum preparation conditions were as follows: activation temperature of 980°C, activation duration of 41 min and steam flow rate of 1.66 ml/min. The optimum conditions resulted in an activation carbon with an iodine number of 1025 mg/g and a yield of 52.17%, while the BET surface area, total pore volume and average pore diameter of WSAC were 1328m2/g, 0.72ml/g and 2.2nm respectively. The study supported the potentiality of comprehensive utilization ofWalnut shell and the benefits of the microwave heating.IntroductionActivated carbons are one of the most important adsorbent materials in modern society because of its abundantly developed pore structure, strong adsorption ability, high surface area and thermo stability. They have extensive application in many industries fields which include gas purification [1], catalyst supports [2] and other pollutants [3]. However, in recent years, the industrial production of activated carbon is facing the problem of raw material scarcity and high cost, which limit to be widely used. Therefore, the selection of an appropriate precursor plays an important role and it has become hot sport to seek cheap raw material to lower preparation cost. As a kind of reproducible resource, the waste from agriculture and forestry is a high-grade raw material for preparing activated carbon due to is high carbon content, such as palm shell [4], rice hull [5], and coconut shell [6]. At present Walnut shell is widely accepted to be a renewable source of biomass. According to statistics, there is more than 1000,000 tonnes of walnut shells are produced in China annually [7]. As a good precursor for activated carbon production, Walnut shell is a major agricultural waste, to make better use of the cheap and abundant agricultural waste, it is proposed for activated carbon production."

Jan 1, 2014

By S. G. Hardcastle, C. K. Kocsis

In Canada’s metal mines, ventilation, which requires electricity to operate the fans and fossil fuel for heating, accounts for a significant portion of the overall mine’s underground power consumption. Mine ventilation systems are usually designed near the end of the mine design process and often designed for the ‘worst-case-scenario’ with respect to ventilation demand. In Canada’s metal mines this is commonly dictated by either diesel equipment usage or heat management considerations. Once designed, mine ventilation systems tend to operate at this peak level throughout the operating life of the mine. This is despite there being significant periods when this quantity is not required this is done mainly due to lack of appropriate ventilation controls. Consequently, such systems are inefficient and wasteful and this must be changed if mining operations are to remain competitive while meeting increasingly more stringent regulations of underground environmental conditions. The advances in computing power and modelling software now make it possible to design, model and schedule a mine from opening to closure. The tools used for this include several disparate types of software. A developing trend is to design and plan the mine using orebody modelling software, followed by using discrete event simulation to predict production and evaluate various operating scenarios. It seems that again ventilation design is not being integrated into this process. Although, several modelling packages exist for ventilation design, little work has been done on integrating ventilation modelling into the overall life cycle plan of the mine. This paper will present a discussion of the work where the authors are attempting to integrate discrete event simulation for mine planning with ventilation modelling to predict the ventilation requirements for the operating life of the mine.

Jan 1, 2003

By H. L. Talbot, A. J. Hall, R. S. Young

A method for the chemical differentiation of oxidized cobalt from sulphide cobalt in complex mine and concentrator products is of considerable interest to a number of mining companies throughout the world. At Rhokana Corporation, in Northern Rhodesia, for instance, cobalt is found chiefly in the sulphide form, as carrollite, but a cobalt oxide mineral also occurs irregularly underground, and relatively small quantities in the mill feed from time to time are difficult to detect visually at the concentrator. The oxide cobalt is not amenable to the sulphide flotation process used at Rhokana and nearly all of it passes into the tailing. The occasional period when high tailing losses occur with no appreciable change in the cobalt content of the mill feed has naturally been disturbing to the concentrator staff, who had no means of determining whether an influx of cobalt oxide ore or laxity on the part of the mill flotation operators as responsible for these results. A procedure for determining oxidized copper minerals, based on their solubility in dilute sulphuric acid saturated with SO2, has been used for many years in the copper industry. In the presence of cuprite the procedure fails, but otherwise it gives results quite satisfactory for control pur- poses. Empirical methods for determining oxidized forms of zinc and lead have been proposed, but they are generally unsatisfactory except in isolated cases of a very simple ore. No published procedure for determining oxidized forms of cobalt or siinilar elements has come to the authors'notice. Experimental Procedure There are obviously two alternatives in attacking a problem of this nature. One is to employ a solvent for oxide cobalt that will not dissolve cobalt sulphide. The other is to find a substance capable of oxidizing the cobalt sulphide to sulphate, which of course is water-soluble and can then be leached from the water-insoluble oxide cobalt. A representative sample of Rhokana cobalt oxide ore was secured, ground to minus 200-mesh, and carefully rolled to furnish a standard sample for this work. The analysis of this material gave the following percentages: Co, 0.55; Cu, 1.64; Fe, 2.98; S, 0.08; SiO2, 41.42; Al2o3, 11.20; CaO, 13.82; MgO, 3.80. As a source of cobalt sulphide a similar large sample of carrollite was prepared, analyzing Co, 23.36 per cent; Cu, 27.32; and S, 31.13. This sample of course was not pure carrollite, but was the best obtainable in quantities sufficient for a standard intended for considerable work. It was a pure sulphide sample, microscopic examination showing only carrollite, a little bornite, and gangue, with no visible sign of oxidized ore present. A wide variety of reagents as used in an effort to selectively dissolve oxide cobalt or to oxidize sulphide cobalt to

Jan 1, 1949

By A. ALLANORE, OLIVEIRA M. DE, D. CICERI, D. P. CHEN

The alkaline hydrothermal processing of K-feldspar rocks in an autoclave can be a pathway to synthesize a potassium fertilizer for tropical soils that is potentially cheaper and more efficient than traditional potash (KCl). When K-feldspar undergoes hydrothermal alteration in the presence of calcium oxide (CaO), it generates a complex mixture of calcium-aluminum-silicate-hydrate (CASH) minerals that incorporate K atoms stochastically in their structure. These atoms are subsequently released, as shown in a test-tube leaching test, indicating a possible uptake by crops. The relationship between the processing temperature and time in the autoclave for the hydrothermal reaction and the resulting mineralogy and elemental release are only partially understood and are investigated in this study. Elucidating that relationship is the key requisite for subsequent techno-economic analysis, and ultimately for the development of a fertilizer that can be considered as a feasible alternative to KCl.

By Anil K. Ray

This paper discusses in situ studies conducted at an Illinois Basin room-and-pillar coal mine to evaluate the performances of three different types of bolts under similar geologic conditions. The bolt types considered were the fully grouted passive rebar (FGPR), the resin-assisted mechanical anchor (RMAB), and the fully grouted tension rebar (FGTR). During the evaluations, the three types of bolts were installed in a single entry covering a span of three contiguous pillars with almost identical geologic conditions. The performances of the three types of bolts were investigated by instrumentting the bolts prior to installation as primary supports on cycle. Additional data on roof behavior was collected with extensometers and shear meters placed near the instrumented bolts. Excluding some time lapse right after installation, the performance evaluation of the three bolt systems was based on the data collected for over a year. Based on this study, it was found that the axial loads measured in the different bolt types did not show any identifiable patterns under the prevailing geological conditions at the mine. Therefore, the assumption that active bolts must be superior to passive ones is not always valid. Even though the studied mine did not have any thinly laminated, weak rocks in the immediate roof, the passive bolts performed as well as the active systems.

Jan 1, 2012

By G. R. Purdy, J. A. Malcolm

The isothermal dendritic precipitation of y in p CuZnSn is compared with the isothermal formation of Widmanstatten a plates in p CuZn. Although both precipitates are evidently bounded by semicoherent interfaces, the dendritic shape of y evolves through smooth "sinuoidal" shape perturbations, while a-p interfaces tend to be strictly planar, or rnicroscopically faceted. An estimate of the average inter-facial free energy of cube-oriented y in p through the Mullins-Sekerka analysis indicates that it is low (of the order of 50 ergs per sq cm). Interface mication is apparently controlled by volunle dij'usion, and the observed anisotropy in growth probably results from anisotropy of inter facial free energy. Studies of the grain boundary precipitation of y in p indicate that the precipitate can grow in both $ grains, but becomes unstable with respect to the grain with which it shares a mobile semicoherent interface. Facets observed at the tips of Kurdjumov-Sacks-oriented Wid-manstatten a plates correspond to variants of an irrational hahit, near (231)0. Comparison with Hu and Smith's determination of relative interfacial free energies of a-(3 boundaries suggests that this system possesses an extremely deep o cup, which results in an ej'ective low-o zone. The possible effects of such a cup on the stability of a-p interfaces are discussed, a needles, grown during rapid continuous cooling, possess microscopically smooth interfaces, and are characterized by a high degree of' damage in the region of the boundaries. These boundaries, induced to move on tempering at 200"C, become faceted as equilibrium is approached, which seems to indicate that boundary structure and mobility in this system are dependent on the local degvee of departure from equilibrium MULLINS and sekerkal have elucidated the phase boundary stabilizing effect of surface tension. a factor not taken into account in previous treatments of morphological development. Their analysis applies to the isothermal growth of a pure spherical precipitate (planar in the limit of infinite radius) in a slightly supersaturated solution, under conditions of inter-facial local equilibrium and isotropy of interfacial free energy. More recently, several other factors which might tend to stabilize planar interfaces have received attention. These are: i) interface diffusion;4"8 and ii) slow interfacial reaction. cahn7 included a slight anisotropy in interfacial free energy, and showed that it has no stabilizing effect, but forces shape perturbations to reflect the anisotropy. shewmon4 noted that dendritic morphologies are rarely observed in solid-solid systems, and, in particular, postulated that slow interfacial reaction occurs at all boundaries between proeutectoid ferrite and austenite, except those which propagate parallel to {11 l)y planes (for Kurdjumov-Sachs [K-S] related phases). Previously, Aaronson~ had proposed interfacial reaction at the broad faces of Widmanstatten plates, and expected that the lateral motion of high-mobility incoherent ledge edges would produce planar precipitates bounded by law-mobility semi-coherent interfaces. The problem of interfacial reaction during the dif-fusional formation of precipitates has often been ignored, although it is apparent that a small component of chemical reaction must exist at any moving interface." Further, all solutions of the diffusion equations for boundary conditions corresponding to isothermal growth predict infinite growth rate at time zero, so that elements of interfacial reaction would be most easily detected at early times. However, reported deviations from diffusion control are comparatively rare," and the local-equilibrium diffusion-control model appears adequate for the description of many isothermal growth systems.'2"9 Cahn14 has treated the problem of migration of an interface which is able to reach positional energy minima, and concluded that such an interface, if subjected to a high local ther-modynamic "driving force", may migrate normal to itself without the benefit of ledges. As local equi-

Jan 1, 1968