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By John Addison

Experimental animal studies comparing asbestos and non-asbestos varieties of tremolite indicate tremolite asbestos is markedly more carcinogenic. By direct analogy, the differences in carcinogenicity between tremolite asbestos and non-asbestos prismatic tremolite should be the same for the other types of amphibole that also crystallize in the asbestos and non-asbestos habits. The earliest of the experiment animal studies, done more than 25 years ago, have design limitations by modern standards including the use of injection or surgical implantation as the route of administration rather than the more relevant route of inhalation. However, the differences in the carcinogenicity of amphibole asbestos and non-asbestos amphiboles are sufficiently large to be clearly discernable even with the study limitations. Together with later studies on these and related minerals, there is strong evidence of a much lower hazard associated with the shorter, thicker fibers of the non-asbestos amphiboles, than is found for the asbestos analogues of the same mineral. It is possible that the non-asbestos amphiboles are no more hazardous than other silicate minerals widely considered nuisance dusts. © 2007 Elsevier Inc. All rights reserved. Keywords: Amphibole; Asbestos; Tremolite; Carcinogenic

Jan 1, 2007

By Monica Prezzi

"Auger cast-in-place (ACIP} piles and drilled displacement piles are being increasingly used as foundation elements for structures, particularly in projects requiring accelerated construction or involving the rehabilitation of foundations of existing, overstressed structures. Auger cast-in-place piles (also referred to as continuous-flight-auger piles) are widely used to construct the foundations of all types of structures. There are many different types of drilled displacement piles, with the installation methods varying according to the equipment used. Depending on the specific rotary piling technology used, responses ranging from those associated with non-displacement to those associated with full-displacement piles are obtained. Conventional pile design methods do not account for how the various construction techniques involved in auger piling change the soil state around the pile during installation and, hence, cannot accurately estimate the pile resistance in a consistent way. Research on this subject, identifying the different variables that must be accounted for in design and linking these variables to installation methods, is lacking. This paper describes the different piling methods available for auger cast-in-place and drilled displacement piles, the equipment used to install them and the quality control processes typically used. It also reviews some of the design methods currently used.IntroductionDeep foundations are extensively used in geotechnical engineering practice. The wide spectrum of piling methods results in a variety of pile types. Each type behaves differently, depending on the installation or construction methods. On one end of the spectrum are non-displacement piles, the classicql examples of which are bored piles or drilled · shafts. These piles are constructed by removing a cylinder of soil from the ground and replacing it with concrete and reinforcement. On the other end are full-displacement piles, such as closed-ended pipe piles or precast reinforced concrete piles, which are typically driven into the ground. Driven piles preload the materials below the toe of the pile and displace the soil surrounding the pile shaft laterally during the installation process. Therefore, displacement piles are, in general, more likely to have a stiffer response than non-displacement piles. This is true particularly in the case of sandy soils where displacement causes densification."

Jan 1, 2005

By N. J. Contini, R. W. Knopp

"In March 1988, old Denver flotation cells were removed from Dickenson's Arthur w. White Mill, and a new flotation circuit, consisting of four Prochem rougher cells and a Hydrochem agitated cleaner column, was commissioned. The refractory portion of the gold in the ore is associated with arsenopyrite, therefore the flotation circuit is set up to produce a saleable sulphide concentrate. Tailings from the leach circuit are conditioned prior to being pumped as feed to the flotation circuit. The prototype Hydrochem agitated column has been in operation as a single cleaner stage for rougher concentrate. The effect of flotation circuit changes on gold recovery data, as well as cleaner concentrate production, and development work to achieve the target results, have been investigated. Flowsheet modifications and the resulting circuit performance data, along with test results to date, will be presented.INTRODUCTIONThe mill is capable of treating 1000 stpd of ore averaging approximately 0.30 oz/ton Au. The ore is crushed and ground to 75% - 200 mesh. Gravity concentration, cyanidation, and Merrill - Crowe precipitation yields 84% gold recovery. Detailed descriptions of the comminution, gravity separation, and leaching circuits, as well as background information have been presented elsewhere (Suttill, Van Weert et al). The target cleaner concentrate grade is 1.0 oz/ton Au for custom smelting and refining. Historical gold recovery values of the old circuit was approximately 20% of the gold present in the float feed at the target grade. The recovery value objective set for the new circuit during the planning stages was 50% of the gold present in the flotation feed at 1.0 oz/ton Au in cleaner concentrate."

Jan 1, 1989

By D. Kosior

Influence of frothers (a-terpineol and n-octanol) concentration on kinetics of a three phase contact (TPC) formation by a bubble colliding with a hydrophobic surface (Teflon) of different roughness was studied using a high-speed camera (1040 frames per second). It was found that the Teflon surface roughness and the frother concentration strongly affected time of the TPC formation (tTPC) and time of drainage (tD) of the liquid film separating the colliding bubble from the solid surfaces. With increasing Teflon surface roughness, from ca 1 to 80 µm, the time of the TPC formation was shortened by over the order of magnitude, from ca 100 to a few milliseconds only. At low a-terpineol and n-octanol concentrations, thetTPC values were shorter than in distilled water due to lowering the bubble velocity in the frother presence and diminished bouncing of the colliding bubble. However, at high frothers concentrations the tTPC values were prolonged, despite that the bubble velocity was similar. The prolongation of the tTPC at high frother concentrations indicates that air (micro- and/or nano-bubbles) was present at the Teflon surfaces of different roughness. The mechanism of the tTPCprolongation at high frother dosage is described.

Sep 1, 2012

By Chee Theng

"Mineral processors know you can put in the best technology in the world but it won’t work optimally without the support of the operators. Conversely, you may have complete operator support but won’t get top results without the right technology. When the two come together, the returns can be phenomenal.The first day of talks at the 68th Annual Colorado MPD Conference, held April 26-28 at The Broadmoor in Colorado Springs, covered the ground on these industry wisdoms.Coming together as a team“Think of the people, not just the lab and the numbers. That makes all the difference,” said Dee Kippers, of FMI Henderson Mine, in her talk on “Process optimization during a market downturn (A Moly MacGyver story).” Kippers told an entertaining story of the journey she and her team took in tackling the issue of an annual spike in iron content in the product at Freeport- McMoRan’s Henderson primary molybdenum mine near Empire, CO.As the metallurgists tried one thing after another — cranking up the iron depressant, adjusting pH with sodium hydroxide and hydrated lime, modifying reagent levels — Kippers found that when she shared her results with the operators, communicated with them on what she was doing and got their input, they were more willing to work with her, and more understanding and supportive of her efforts.The results make the case for getting people on board and coming together as a team. The cost savings from their optimization efforts, with little capital investment, have been “enough to cover the annual salaries of our metallurgy department and then some,” Kippers said.Considering the environmentDavid Lemieux, of Dundee Sustainable Technologies (DST), talked next on “Cyanidefree process for gold extraction,” presenting the results obtained from a demonstration campaign of the company’s novel chlorination process for gold extraction and associated arsenic stabilization process. Developed at an investment cost of C$35 million, they are ready for commercialization, having been demonstrated on the laboratory, pilot and demonstration scales.The DST process is differentiated from the Plattner chlorination process, which was in use from 1851 to 1916, by moderate process conditions of atmospheric pressure and ambient temperature — the result of using sodium hypochlorite solution, or bleach, instead of direct injection of chlorine gas — and new, cheaper materials of construction, such as polymers, plastics, fiberreinforced plastics and Teflon, resulting in lower capital and operating expenditures."

Jan 7, 2018

By Jong Hyeon Lee, Go-Gi Lee, Chang-Kyu Lee, Hong Youl Ryu, Sung-Koo Jo

This study deals with research on the reduction process of neodymium oxide by molten salt electrowinning. Neodymium fluoride and lithium fluoride electrolyte were used for feed stock of electrolyte and neodymium oxide was added as precursor. Cell current was confirmed that cell potential was applied as constant potential of 4.5V. Argon gas injection into the electrolyte was carried out to confirm convection effect on current efficiency. Applied current was gradually decreased without argon flow, but applied current was kept within a certain range with argon flow in electrolyte.

Jan 1, 2015

By Charles K. Presley

This paper deals with drilling large diameter shafts for the mining and construction industry with diameters in excess of 3 feet to more than 20 feet in diameter. It discusses appropriate applications of the rotary drill method, linings for large diameter shafts, circulation systems,, and the limitations of the method. Each specific rotary drill method is determined by the geology of the area, the depth to be drilled and the formation fluids encountered. Shaft lining or casing must be improved to result in lighter weight, higher strength and lower cost. All phases of rotary drilling equipment must be improved to drill shafts in excess of 10 feet in diameter. As these goals are reached, more shafts of large diameter will be drilled by the rotary method for the mining and construction industry.

Jan 1, 1967

By David J. Brown

Extensive deposits of bituminous, subbituminous, and lignite coals occur in the western United States (Figure 1). Over one trillion tons of identified resources have been located and inferred by geologists and more than 200 million tons of western coal are mined annually (1). In the future, production of western coals will increase significantly and approach national production levels of higher-rank eastern coals. Western coals will be utilized in new power plants as a replacement fuel for oil and gas and may be used in advanced technologies such as diesel engines or in direct-fired turbines. Since these applications require low-ash, low-sulfur coals, crushing to fine sizes and significant cleaning to remove minerals and sulfur will be required. Coal cleaning traditionally has been associated with reducing pyrite and other mineral matter from high-rank eastern coals. To date, insignificant quantities of western coals have been cleaned before utilization and limited data on their washability characteristics exist. Because of this lack of data, it is difficult to predict how these coals will react to standard washing techniques.

Jan 1, 1985

By Andre Zingano

The variation in pillar behavior at underground coal mines working in the Bonito coal seam is observed in both research and mining company case studies. There is no consistency in pillar behavior, as it varies from mine to mine. In some cases, it is possible to find rib yields for both excavation modes and pillar sizes. This paper?s objective is to investigate pillar behavior for different load conditions and pillar sizes. Three-dimensional numerical simulation models considering these factors were built. A matrix was then assembled to compare pillar behavior between loading conditions, as well as between different pillar sizes with the same loading condition. The results showed some pillar rib plasticity due to vertical loading and stress relief independent of the pillar size and load. For the same load conditions, the yielding thickness is the same for different pillar sizes.

Jan 1, 2012

By Robert L. (Original by) Llewellyn

Many of the problems that occur in the preparation plant originate from practices in the mine. Impurities in raw coal can be in the seam itself or from extraneous material taken in mining from the roof or bottom. In the case of underground mines, the choice of mining equipment will affect the size consist and the amount of extraneous material included with the coal. Also, governmental regulations concerning the degree of rock dusting, gobbing underground, and cleanup have increased the dirt in raw coal. Sulfur dioxide emission standards, on the other hand, are pressuring the coal industry to clean coal more thoroughly. Coal supplied for coking purposes is nearly all upgraded by washing, while for the largest market, electric power generation, a high proportion is shipped as a raw product with processing, in whole or in part, only necessary when excess impurities are mined with the coal. This chapter will deal primarily with plants that process or wash coal to some extent (Fig. 1) and only incidentally with mines shipping raw run-of-mine coal crushed to a top size of, usually, 51 to 102 mm (2 to 4 in.), with little, if any, other treatment.

Jan 1, 1981

By W. S. Gillam

A need for new supplies of fresh water exists today and in many specific areas that need is urgent. One solution lies in saline water conversion, a problem complicated by cost factors. The principles involved in saline water conversion, the status of development, and the estimated costs (present and future) of several processes are presented. Among the methods discussed are distillation, electrodialysis, and freezing. In general, the costs presented are based on a standardized procedure for estimating conversion costs, permitting a valid comparison among the various processes. The need for new supplies of fresh water and the potential benefits to be derived from an abundant supply of converted water are recognized by practically everyone concerned with water problems. The water supply problem exists today; it is urgent in many specific areas in this country and also in the world, and it will become more acute in the future. One answer to the growing problem of adequate water supplies is the development of new sources. Very significant quantities of brackish underground and surface waters exist in certain areas and an inexhaustible supply of ocean water is available. Thus in many areas water resources can be extended through saline water conversion. Congress recognized the need for new sources of fresh water in 1952 and passed the Saline Water Act, Public Law 448, amended it in 1955, and in September 1958, enacted Public Law 85-883, calling for the construction of at least five demonstration plants. The program is administered by the Dept. of Interior through the Office of Saline Water, and its primary objective is to reduce the cost of converted water produced, whether it be by development of new processes or improvement of known processes. This is a most difficult problem and one that will require several years of prodigious effort. It is difficult—not because of any intricate or new chemistry, engineering, or physics involved—but because of the difficulty in converting water at low cost. Whatever the sources of the saline water, the salts which are held tenaciously in solution must be removed before the water becomes suitable for industrial or domestic uses. Saline water is a relatively simple system of salts dissolved in water. It has certain chemical and physical properties that determine the various methods by which the salts may be separated from the water. The system, although not complex, in most instances, has had countless years in which to reach equilibrium and is, therefore, comparatively stable. Because of its stability, separation of saline solutions requires relatively large quantities of energy. The unique properties of water depend on the fact that its molecules are chemically active. The chemical and physical properties of water are associated with the type of bonding involved in the water molecule. Chemical changes such as hydrolysis, or rusting of iron, involve the breaking of chemical bonds between the hydrogen and oxygen atoms. Physical changes, such as evaporation in a boiler, the melting of ice, or the viscous resistance to flow in a pipe, involve breaking of the hydrogen bonds. (The hydrogen nucleus is so small that it can attract two negative atoms.) Thus water molecules not only combine with molecules of other compounds but even with one another; e.g., each molecule may be bounded to four other molecules. Water molecules cling to the ions of dissolved salt to form water-encumbered hydrated ions and they cling to one another to form entangling networks through which hydrated ions can be propelled only by tearing the networks apart. That is one reason why considerable energy still needs to be expended in our simplest procedures for purifying water. If water molecules did not have this habit of clinging so tenaciously to other molecules, and to one another, it would be easy to push salt ions past the water molecule and get a separation. But the water would not then dissolve salt, so the problem would not exist.' Water when heated evaporates very slowly, relative to other liquids having simple molecules. Vaporization involves the separation of molecules from the liquid, and this means overcoming the attraction between molecules which is due to the hydrogen bonding. The heat of vaporization for water is high; consequently, the boiling point of water is also high. Water boils at 100" C; hydrogen sulfide (H2S) at -60" C; oxygen (02) at -183" C; nitrogen (N2) at -196" C; and methane (CH4) at-161°C, even though the latter has about the same molecular weight as water. Because of these peculiar properties of water, it exists as a liquid on earth instead of a gas such as hydrogen sulfide or nitrogen and oxygen.

Jan 1, 1961

By A. R. Laplante

Gold recovery early in the flowsheet, typically from the primary grinding circuit, has seen significant advances in the past three years. Some of the advances achieved under the auspices of the AMIRA P420B Gold Processing Technology project are reviewed. The areas covered are gravity-recoverable gold (GRG) characterization, GRG behaviour in classification, gravity recovery simulation and the link between gravity recovery and cyanidation.

Jan 1, 2005

By P. Sanchez-Mejorada

GEOLOGISTS who are acquainted with the mines of northeastern Mexico realize that the most important lead-silver replacement deposits of the province are confined to a single formation. But since the formation is several hundred meters thick, the author has determined the relative position of the lead mantos in the belief that this information will prove useful in the search for new mines. This article describes the stratigraphic location of lead-silver replacement deposits known in several mines situated in a region comprising part of the states of Coahuila and Nuevo Leon. The area studied extends for 200 km* (125 miles) from east to west and 70 km (45 miles) north to south. Metallogenic Province: The most important metallic deposits of the region have the following common characteristics: 1) The orebodies occur as manto replacements of calcareous sediments. 2) The horizons that have contributed large tonnages of ore are in similar positions in the corresponding stratigraphic columns (as it will be shown later on). 3) Lead is the most important metal in the ores. Silver is commonly present in small amounts. Occurrence of zinc is dependent on the degree of oxidation of the primary sulfides. 4) A large proportion of the total production has been in the form of oxidized ores. 5) The deposits are located on anticlines. Rocks of Cretaceous age crop out over large areas of the states of Nuevo Leon and Coahuila. forming part of a belt that extends to the south along the eastern Sierra Madre. The sediments are cut by a small number of intrusive stocks ranging in characteristics from rhyolite to diorite. The most prominent structural feature of the region is a series of folds trending northwest-southeast. Faulting is not conspicuous in the region, although a major fault zone is found farther East.' The physiography closely reflects structural features, with mountains formed by anticlines and valleys conforming with intermediate synclines. Narrow valleys have also been developed along the axes of many anticlines, where solution of limy sedi- ments and erosion have proceeded along axial tension fractures. Stratigraphy: Rocks of the Upper Cretaceous are exposed in only a small percentage of the total area. Generally they have been eroded away from the mountains and are covered by recent talus and alluvium in the valleys. Humphrey' has published an excellent paper describing the Cretaceous formations of the Sierra de los Muertos, a short distance west of Monterrey. A brief summary of these formations is given below to convey an overall picture of the stratigraphic sequence that prevails just south of the area under consideration. Upper Cretaceous Indidura: Essentially thin shaly sediments. Cuesta del Cura: Limestone in thin wavy beds

Jan 1, 1959

By V. A. Preto

The Rexspar uranium deposit is located approximately 5 kilometres south of Birch Island, B.C. Three separate zones of commercial-grade uranium mineralization mineable by open pit have been outlined. Uranium and fluorite-celestite mineralization occur in a trachytic member of alkali-feldspar porphyry, lithic tuff, tuff breccias and pyritic schist conformably interlayered with a succession of strongly deformed greenschists and fragmental rocks that are, in large part at least, of volcanic origin. The age of these strata is not precisely known, but they are considered as part of the possibly Mississippian Eagle Bay Formation. Commercial-grade uranium mineralization is always associated with fluorphlogopite-pyrite replacement of the trachytic unit and is contiguous to, but separate from , a zone of ore-grade fluorite mineralization. In all zones, ore occurs in lenses of variable thickness and lateral extent, which lie parallel to the schistosity of the trachytic rocks and surrounding greenschists. The principal radioactive minerals at Rexspar have been identified by other workers as uraninite, uranothorite, bastnaesite, torbernite and metatorbernite. Considerable amounts of thorium oxide and widespread rare earths have been reported from all three radioactive zones. The geology of the deposit suggests that the trachytic rocks represent a highly differentiated intrusive-extrusive system in which fluorphlogopite, pyrite, fluorite and uranium-bearing minerals were deposited late in the evolution of the system by deuteric, volatile-rich fluids. The considerable amounts of thorium and widespread rare earths associated with the uranium tend to support the thesis that this element is of primary origin rather than secondary.

Jan 1, 1978

By S. Afrouz, C. Keles, E. Sarver, A. Greth

While respirable dust monitoring has long been done on the basis of mass concentration, it is increasingly recognized that specific dust characteristics may play an important role in health outcomes. Scanning electron microscopy with energydispersive X-ray (SEM-EDX) can be used for detailed particle analysis, but the quality of results can be dependent on the sample substrate; ideally, particles should be deposited on a smooth, uniform substrate like polycarbonate (PC). While direct air sampling onto PC filters is possible, this is not the standard approach in many situations. For example, in coal mines, polyvinyl chloride (PVC) filters are often used. They enable conventional mass-based analysis — of the total respirable dust, and the content of crystalline silica in this fraction — but are fibrous and thus not ideal for SEM-EDX or other microscopy. To address this issue, the current work tested a simple method to recover respirable dust particles from PVC filters and redeposit them to PC. Results generally indicated that recovered particles are representative of the original dust sample in terms of mineralogy distributions. Where this was not the case, the issue appeared to be with high particle loading density during SEM-EDX work rather than related to the recovery/redeposition method itself. This bodes well for applications where a single PVC filter sample could be used for nondestructive analysis to determine respirable dust mass and/or respirable silica mass, followed by preparation for SEM-EDX analysis to evaluate particle characteristics. The recovery and redeposition method might also be adapted for other applications, such as to enable the analysis of respirable dust samples collected by the continuous personal dust monitor (CPDM).

Oct 1, 2024

By C. W. Fitzgerald

INTRODUCTION Continuous mining machines are used in regular flat ore beds having uniform thickness. Since coal is the most common type of material occurring in such beds, most continuous miners are used for the extraction of coal from underground mines. The first continuous mining machine for under¬ground coal mining was introduced in 1948. In one machine, the continuous miner combines the functions performed by a conventional face drill, a cutting ma¬chine, and a loading machine. It breaks or digs the material out of the surrounding solid and transfers the material back through the machine chassis by means of a chain conveyor. The conveyor carries the material to a haulage system, usually a rubber-tired vehicle known as a shuttle car. Generally, continuous miners are used in seam heights from 890 to 3660 mm (35 to 144 in.). For seam heights of 1070 mm (42 in.) or less, the haulage system may be a multiple-bridge conveyor or battery-powered tractors that haul low-bed trailers. Proj¬ects are being undertaken by private industry and through government contracts to develop a continuous haulage system for all seam heights. As of 1976, the majority of continuous miners were of two types. The first type is the drum miner, which mounts the cutting elements on a series of drums across the cutting head of the machine, sometimes using a cutting chain to cut clearance for the gear drive. In the drum-type machines, the cutting head rotates parallel to the material face. The second type is the auger miner, which utilizes cutting elements mounted on two auger-type cutting heads. One head is located on each side of the machine, with the heads mounted per¬pendicular to the material face. Chain-head ripper-type miners/miners having rotary cutting elements with oscillating motion and twin-head boring-type miners have all been popular within the last 15 years. Although these are considered obsolete, some machines are still being supplied for specialized applications. GENERAL DESCRIPTION This chapter describes only continuous mining ma¬chines available as manufacturers' production models as of September 1976. Figs. 1 through 11 illustrate some typical machines currently in use. Cutting Elements The cutting elements are the interface between the machine and the material being mined. In describing the cutting elements, consideration must be given to the differences between the drum- and auger-type machines, the bit-tip speeds, and the bit types. Drum-Type Continuous Mining Machines: Three of the four principal manufacturers of drum-type miners use multi-motor designs that provide separate a-c motors for driving the cutting elements. Gear trains are used to reduce the speeds of the motors to the rotational speeds of the cutting elements. One of the three suppliers drives the cutting elements of its low-seam models with a heavy-duty drive chain that is equipped with cutting bits; all other functions of this machine have separate motor drives that are either electrical or hydraulic. The fourth principal manufacturer generally provides two a-c electric motors, utilizing gear reducers, drive shafts, and hydraulically operated engaging clutches to power all of the operating functions, including the cut¬ting elements. Some drum-type miners use trim chains, equipped with cutting bits, to cut clearance for the gear drives. These trim chains vary from two 305-mm (12-in.) chains to one 760-mm (30-in.) chain per machine, de¬pending upon the manufacturer's design concept. In all machines other than the low-seam models that use chains to drive the heads, the trim chains are driven by sprockets on the drive shaft of the final cutterhead drum; therefore, the trim chains are not used for power trans¬mission to the cutting elements. In addition to cutting clearance for the gear drives, the trim chains provide uniform bit spacing all the way across the head and assist in moving the cut material to an area where it is either loaded directly into the miner's conveyor or is easier to load into the conveyor. On a drum-type mining machine, the cutting ele¬ments all rotate from the top to the bottom. Therefore, the recommended procedure is to raise the cutterhead to the maximum seam height, sump the entire machine forward to maximum depth by means of a crawler drive, and then shear downward until the cutter elements reach the floor level. The maximum sump depth varies ac¬cording to the drum diameter, the type of material, the floor conditions, and the operator's abilities. It normally varies an average of 460 to 760 mm (18 to 30 in.). Cutter drums are supplied with two types of cutting bit holders. Weld-on holders are attached permanently. Pin-on holders are replaceable at the face. Cutter-drum diameters over the bit tips vary from 660 to 965 mm (26 to 38 in.), depending upon the chassis height of the machine and the range of cutting heights. Auger-Type Continuous Mining Machines: As cut-

Jan 1, 1982

By J Dwyer, M Hill

Downer’s mining division has made an operational and financial commitment to developing engineered solutions that mitigate the risks associated with operator proximity to uncontrolled development drill boom movements, and unguarded rotating drill steels.With the potential for serious injury or fatality, these identified risks are categorised as critical. Previous attempts by the industry to engineer them out have produced limited success, with numerous incidents still occurring year on year. Ultimately, the industry (as a whole) remains reliant on procedural prevention for operator safety.Downer understood the success of such an initiative would largely depend on the effective collaboration between operational experience, technology experts and automation. With so many variables requiring consideration; such as physical operator movement, machine boom movements, variable machine positions, and underground environmental impacts – challenging traditional technologies was necessary to deliver an optimal solution.For that reason, discrete detection (similar to laser curtains or beams) was considered not fit for purpose. The use of situational mapping, using rotating lasers, however, provided the optimal solution. The lasers collect data that is then processed using a custom software application.The software application is specifically programmed for tracking and classifying objects within detection zones, using advanced algorithms and filtering. Recognition and removal of non-positive disturbances are possible without losing personnel detection capability. The detection of relevant classified objects (humans) is determined by analysis of object size, age, movement, and speed etc. When the relevant object is detected, an alarm and inhibit function is applied preventing drilling functions.Any breach of the safety zone (forward of the front jacks) will automatically disable the hydraulic boom function. This can only be reset in the cabin once the person or persons have returned past the front jacks of the development drill into the safety zone.Downer, in collaboration with partner YUMARR Automation, has successfully developed this reliable boom isolation system, and is called JumboGuard. The system has now been commissioned and installed across all Downer Mining development drill fleets, operating in Australia.CITATION:Hill, M and Dwyer, J, 2017. JumboGuard – automatic boom isolation system, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 287–294 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By Victor O. Homerberg, Dexter N. Shaw

A study of the correlation of the mechanical properties and of the microstructure with the heat treatment of 60-40 brass has been confined, heretofore, to the rolled or extruded material as received from the mannfacturer. The results obtained by Babson and Buhler,' Bengough and Hudson12 Stead and Stedman,3 and Brayton4 have been confined to the treatment of the material as received. No attempt was made to get the material into a given condition and then to work from this basis. To start with a given structure would have the decided advantage of making the work independent of the original condition, hence, to make the results reproduceable. In a previous paper, it was shown, in connection with the study of the transformation that occurs at about 470" C., that if specimens were quenched to produce the beta structure and then reheated, the beta would begin to break down, at approximately 200" C., into a very finely divided alpha. It was predicted that important results might be obtained if test pieces were to be given a similar double heat treatment and then tested for the mechanical properties as well as a study of the microstructure. The material used in the present investigation was a 3/4-in. round bar of extruded muntz metal of the following composition: Copper, 61.05 per cent.; zinc (by difference), 38.90 per cent.; lead, 0.05 per cent.; iron, trace; tin, nil.

Jan 1, 1924

By Luis Valentim, Terry Cousins

The goal of a mine is to produce ore at the lowest possible cost with due regard to safety of pemonnel and equipment. The mining process consists of a number of discrete operations such as planning, drilling, blasting,excavation, transportation and crushing. These processes are interrelated and cannot be considered as separate activities when optimising output and minimising cost. In order to optimise the global costs it may therefore be necessary to increase cost in one area such as blasting design and management beyond the norm.

Jan 1, 1998

By Michael Hamilton

Mineral resources have been identified at seven properties in the, Middle Fork Judith study area (fig. 1, and table 1). Commodities consist of silver, gold, copper, lead, zinc, and marble. Eleven properties (fig. 1 and table 2) have potential for discovery of silver, copper, lead, zinc, or sapphire resources. Of principle interest are the mineral deposits within contact zones between the Yogo intrusive complex and the surrounding Paleozoic sedimentary rocks. Contact alteration zones along the southern slopes of Yogo Peak have been prospected in a 2- to 3-mi (3.2-to 4.8 -km) long belt within the study area.

Jan 1, 1982