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By Michael Moran

Typical ACIP Pile Rig [ ] Hollow Stem Auger ? Continuous flight auger ? 3 inch inside diameter pipe ? Auger diameters: 12, 14, 16, 18, 20, 22, 24, 30, and 36 inches ? Auger section lengths: 4, 5, 10, and 20 ft ? Weight ranges from about 70 lbs per ft for 12 inch to 120 lbs per ft for 24 inch and 200 lbs per ft for 36 inch

Jan 1, 2005

By C. P. S. Barnard, D. G. Krige

Objective justification on economic grounds for expenditure aimed at improving the quality of the underground working environment requires a suitable measure of any improvement in productivity that would result under routine working conditions. For this purpose, a composite production criterion is suggested, as well as its correlation under actual operating conditions with various factors directly affecting productivity and the environment. Of the environmental factors, wet-bulb temperature appears to be the major factor affecting productivity. The production data given indicate that a decrease in the wet-bulb temperature of 1OC can be expected to result, on average, in some 3 to 4 per cent increase in productivity; in the higher temperature ranges, this percentage could be much higher.

Jan 1, 1981

By Mark J. Klein

The behavior of nitrogen in Cr-0.12 at. pct Y was studied in specimens of varying interstitial concentration and thermal history. It was found that soluble nitrogen can be introduced into this alloy by increasing the concentrations of either oxygen or nitrogen. For low nitrogen concentrations the nitrogen in solution is low relative to that in unalloyed chromium. However, the nitrogen in solution increases with increasing nitrogen concentration, approaching that in unalloyed chromium. When the alloy is supersaturated with nitrogen, the nitrogen precipitates readily from solution as a chromium nitride. The stress -induced relaxation of nitrogen is influenced by internal oxidation or internal nitrification of this alloy. THE addition of small concentrations of reactive elements such as yttrium have been found to enhance the low-temperature ductility of chromium.&apos; However, the mechanism by which the ductility is increased is not known. It has been suggested that this effect is caused by a drastic reduction in the concentration of nitrogen retained in solution and therefore a decrease in the number of dislocations locked by nitrogen, a factor that has been associated with an increase in ductility.1,2 However, a change in the type of interstitial precipitate induced by yttrium could also contribute to enhanced ductility of the alloy, since chromium nitride precipitates appear to be embrittling.&apos; In this regard, it has been shown that yttrium scavenges nitrogen in chromium to form YN,4 thus reducing the embrittling chromium nitride phase. However, the change in nitrogen solubility induced by yttrium and the partition of nitrogen between chromium and yttrium nitrides are not known. The object of this investigation is to study the effect of yttrium on the behavior of nitrogen in chromium to obtain information relevant to the mechanism by which scavengers enhance the ductility of chromium. EXPERIMENTAL PROCEDURES The experimental procedures used in this investigation have been described in detail elsewhere.5,6 Wires of Cr-0.12 at. pct Y, 15 cm in length and 1 mm in diam, were drawn from rods 0.6 cm in diam supplied by the General Electric Co. The grain size of the wires after recrystallization at 1150°C was somewhat nonuniform, varying from 0.006 to 0.06 mm in diam. The interstitial analysis for the wires in ppm by weight was about 160 0, 80 N, 12 C, and <2 H. Heat treatments were carried out after encapsulation of the specimens in quartz tubes containing argon. Changes in interstitial concentrations, or interstitial "loading" as it is termed in this study, were generally accomplished by annealing in oxygen, ammonia or methane at 1150°C. The internal friction was measured using a conventional torsional pendulum enclosed in an evacuated chamber. Electrical-resistivity measurements were made at liquid-nitrogen temperature.

Jan 1, 1967

By Washington Luiz Mafra

Every year the conventional direct reduction processes ? Midrex and HYL III ? increased their market share in the world steel production, even though they are only economically feasible in countries where natural gas is available at competitive prices. In this context, the new Midrex projects are based on large reactors (Megamod - 1.5 to 1.8 Mt/y of DRI), reduction temperatures of the metallic burden up to 850oC, with bustle gas temperatures between 960oC e 1050oC. Thus, the requirements of metallic burden performance, as well as the evaluating methods, usually based on ISO standards, need to be reviewed. It is well known that the standards usually applied to quality evaluation do not reflect the performance of metallic burden inside the reactors. This paper describes the different methods of evaluating the disintegration under reduction of DR pellets based on ISO 11257 standard. This is the most important method used by pellet producers and customers for evaluating DR feedstocks. The different methodologies tested to evaluate the disintegration under reduction had varying results, evidencing the relevance of the method and the quality of the pellet. Nevertheless, validating the method in an industrial reactor is still fundamental.

May 1, 2007

By Arcy, D&apos Banister

The productive potential of the Nation&apos;s principal active and inactive silver mining districts has been evaluated, using 1964 economic conditions and assumed silver prices ranging up to $3 per ounce. On this basis, the United States has an estimated 5 billion ounces of unmined silver, excluding minor byproduct silver in gold deposits. Approximately 3.5 billion ounces are contained in deposits requiring higher silver prices to be economically minable, and about 1.3 billion ounces are in currently operating mines. An analysis of silver consumption trends since 1954 indicates that the free world industrial market will climb to nearly 800 million ounces annually by 1985. U.S. industrial silver consumption has been projected to increase at an annual rate of 4 percent from 1965 to 1985. Average annual increase for the remainder of the free world has been 8.1 percent since 1953; this is expected to level off with an estimated average increase of 5 percent to 1975 and 4 percent from 1976 to 1985. Foreign silver production has, in the past, exceeded consumption, but in 1960 the supply deficit was over 100 million ounces. U.S. production, also traditionally exceeding demand, was suddenly overtaken at the start of World War II. By 1964 the annual deficit, excluding coinage, was over 84 million ounces. World coinage requirements of silver are fast declining and expected to total only 25 million ounces annually by 1985. In fact, coins are already becoming major short-term source of silver to fill the large deficit between industrial demand and current production. The larger, long-term deficit (to 1985, the limit of this study) must be balanced by silver from the hoards and new production from silver deposits. Eventually all of the deficit must be met by new production or silver prices will rise until consumption is greatly curtailed. To balance free world supply and demand, it is estimated that the free world must produce an additional 85 million ounces by 1975 and 375 million ounces by 1985. The estimated proportion expected from U.S. deposits is 17 million ounces by 1975 and 74 million ounces by 1985.

Jan 1, 1969

By Tim Edwards, Richard Triglavcanin, Ian Arbuthnot, Darren Colwell, Brad Garraway, Ken Roberts

"In the mineral processing industries, there is an increasing need to design thickeners which are able to produce high density underflows usually referred to as “paste”.The behaviour of a flocculated suspension in compression needs to be well understood in order to arrive at a reliable thickener tank configuration (i.e. diameter, cone angle and depth) for a required paste result.As a suspension approaches paste consistency, it’s fluid characteristics change markedly. It develops a high yield stress, and may have an increased tendency to form agglomerates, which lead to a phenomenon known as “rotating beds”, “donuts”, or “islands”. These characteristics present challenges to the designer of the rake mechanism.The subject paper addresses the requirements for designing a paste thickener, covering the following topics:o Testwork for thickener sizingo Design of rake mechanismso Suspension rheology and effect on designo Case studiesTESTWORK AND SIZING FOR PASTE THICKENERSThickening slurries to the maximum possible density (paste) is becoming increasingly common. Applications such as Autoclave feed thickeners, paste backfill and some counter current washing (CCD) circuits are all examples of potential paste thickening applications. The principle of paste thickeners is that the compression zone is much deeper than on either high rate (HRT) or high compression (HCT) units; generally 3 metres or more. As the compression zone gets deeper, theunderflow density for a given flux rate (tph/m2) increases, as a result of two factors:1. Longer bed settling time. Settling flocs move relative to one another and release interstitial fluid when they are in compression. Increasing bed residence time achieves higher density underflow as more fluid is removed.2. The nett weight of the bed creates a compressive force on the settling flocs. This force increases with depth, so that the flocs at the bottom of the bed experience the highest compressive force. This represents the driving force to expel interstitial fluid and hence increase bed density."

Jan 1, 2005

By U. Sachse

This paper explores a systematic approach for mining decision-makers to use when faced with choosing which method to use for a specific rockpass length. The different excavation methods available in the broad South African mining industry are compared against a number of critical parameters, as applied to rockpasses of varying length. This approach is not meant as a definitive, prescriptive planning tool, but rather as a proposed approach to enable designers and planners to choose the best system to excavate their specific rockpasses

Jan 1, 2005

By James Westfield

Drilling for roof bolting has created a new dust problem for the coal-mining industry. Drilling is inherently dusty, and control of dust produced by drilling vertical or nearly vertical holes is much more difficult than control of that produced by drilling flat or down holes.4/ Also, the dust produced by roof drilling differs in composition from that produced by drill-fur, or cutting the coal face because it contains a significantly greater amount of free silica and therefore presents a greater potential hazard of silicosis. Roof bolting has been practiced successfully in the mines of the St. Joseph Lead Co. in southeastern Missouri for over 20 years, but it was not until 1947 and 1948 that large-scale roof-bolting experiments were conducted in coal mines.5/ Although the need for dust control in conjunction with roof drilling was recognized from the beginning, the development and acceptance of roof bolting progressed so rapidly during 1949 and 1950 that solution of the dust problem lagged behind other engineering phases of the technique.

Jan 1, 1951

By Kenneth H. Johnston

This report describes in detail three waterflooding projects and a pres-sure-maintenance project in Butler and Cowley Counties, Kans., that will be visited on the 1963 annual spring tour of the Kansas-Oklahoma Waterflood Association. Among the unique features of the projects are the flooding of five oil-producing horizons separately with injection water furnished by two water treating plants. Discussion of the individual projects includes information on their early history, the source and treatment of the injection fluids, oil production decline curves, and the results of water injection on oil production.

Jan 1, 1963

By C. Matthews, A. Vo

Australia is one of the world’s leading exporters of bulk commodities and the extensive use of sampling equipment is key to the successful management of each mining operation. At the process plant, without a full understanding of the feed, product and tails, it is impossible to fully optimise the performance of the plant, such that the metallurgical balance is often open to error. At the port, a statistically correct, bias free and compliant sampling system is crucial to ensuring exported minerals are reflective of their true value and to avoid penalties. Over the last decade, as a result of the iron ore boom, there has been high demand for reliable, representative and standard compliant solids sample systems in Australia. This paper reviews several solids sampling applications at Australian mine sites, the challenges and experience gained and how the implementation of reliable representative sampling systems has provided better understanding of plant process performance, improved plant control and overall benefits to the operations. INTRODUCTION Mining is the primary contributor to the Australian economy with Australia ranking in the top 4 in economic resources for 21 primary industrial minerals in 2016 (Britt, et al., 2017). Australia is one of the world leaders in the export of the majority of its commodities including gold, copper and iron ore (Britt, et al., 2017). Therefore, a suitable and standard compliant sampling system is essential for evaluating plant performance and content verification. At the mine and at the port, the larger iron ore miners in Australia have developed stockpile models to predict the grade of their ore down to individual blocks of the stockpile. This allows the miner to create the right blend of material for sale to their customers and ensures they are not underselling their product or at risk of penalties for impurities or low grade. As an example, the average difference between the benchmark 62% Fe and low grade 58% Fe fines at the time of this report averaged US $20/tonne according to the Metal Bulletin Iron Ore Index (Fastmarkets MB, 2019). At a shipload of 180kt this would be a variation of US $3.6M. Whilst this is an extreme example, it highlights the economic importance of producing the correct grade product and a recognised representative sample of said product.

Jan 1, 2019

By Adrian J. Moore, Alan B. Richards, Rob Evans

Air and ground vibration from blasting is influenced by the delay pattern that is used. Wavefronts from blastholes fired in a blasting pattern can combine in certain circumstances to give increased blast vibration levels. A simple computer model has been developed which shows the combined effect of wavefronts from a multi-hole blast and identifies if wavefront reinforcement occurs, and permits delay patterns to be designed which will avoid or reduce wavefront reinforcement.

Jan 1, 1994

By C. M. St. John

A series of analyses of possible mining excavations associated with the development of copper nickel deposits of the MINNAMAX site in Northeastern Minnesota is presented. Specific areas such as roof and pillar stability and excavution orientations are addressed. The majority of these analyses were conducted using a boundary element method but some cases were also analyzed using the finite element method. Comparable results were obtained using the two methods but the boundary element method required less data preparation time and computer run time. Results of the analyses, as well as indicating the capabilities of geotechnical numerical models, provide some insights into behavior around multiple excavations in jointed rock.

Jan 1, 1979

By I. A. Mwamba

Titanium aluminide of composition Ti-47.5 at.% Al was prepared by melting titanium and aluminium of commercial purity with additions of precious metals of 0, 0.2, 1, 1.5 and 2 at.% content. The microstructure, hardness and oxidation properties were assessed. It was found that at 47.5 at.% Al, the microstructure of plain TiAl alloys was duplex, consisting of duplex lamellar grains and ? grains. The lamellar grains consisted of alternating lamellae of ? (TiAl) and a2 (Ti3Al), with overall aluminium content in the range of 43?47 at.%. The ? grains had a aluminium content above 50 at.%. The addition of precious metals to the TiAl alloy resulted in the formation of a new phase, with a high precious metal content, occurring mostly in the ? phase, without any major change to the microstructure. Increasing the amount of precious metals resulted in an increase of the new phase amount, at the expense of the ? phase. The hardness of the different alloys was around 300HV10. Overall, the research has shown that addition of precious metals to TiAl resulted in a slight increase in hardness and a significant improvement of the oxidation resistance. This shows that alloying TiAl with precious metals, at the addition levels investigated, does not alter the mechanical properties very much, but improves oxidation resistance.

Jan 1, 2012

By B. B. Broms

Embankment piles are common in the Scandinavian countries (Kjellman, 1940) and in Southeast Asia as support of fills, light structures, bridge abutments and deep excavations (Eide, 1968) as described in the following. Untreated timber piles are often used for light structures and shallow fills when the ground water level is high since they are inexpensive and readily available. When the applied loads are relatively high precast concrete piles and steel piles are preferred. DESIGN CONSIDERATIONS Embankment piles carry the load from a fill or a struc-ture either through skin friction along the sides of the piles (Fig. 1a) or through a precast concrete slab or through pile caps at the top of the piles (Fig. 1b). When the load is carried by skin friction it is often economical to use small diameter timber piles because of the large surface area (Asplund, 1939). For precast concrete or steel piles concrete caps are used to transfer the load to the piles due to the relatively high capacity of the piles since the skin friction resistance alone is not sufficient to transfer the load to the piles.

Jan 1, 2010

By Robert W. Bartlett

Hazardous metal contaminants in liquid and solid wastes and from ground spills are important environmental problems in many metallurgical production operations. Acid rock drainage, from mines and huge quantities of permeable mine waste, is probably the most ubiquitous example. Fixing mine waste contaminants in situ has been practiced, using sulfate reducing bacteria (SRB) and organic reagents as electron donors to create anaerobic conditions and precipitate metal sulfides. Aqueous solutions of sugar and alcohol have been percolated into mine wastes with good results. However, maintaining anaerobic conditions permanently is unlikely, as these solutions are eventually washed out of solid waste and contaminated ground by inflow of either groundwater or meteoric water, allowing re-oxidation from entering air. Emulsions of inexpensive, non-aqueous organic microdroplets dispersed in water provide earth wettablility equal to aqueous solutions and easy percolation into both the ground and mine waste. Subsequent breakdown of the O/W emulsion provides permanent retention of the organic phase, attached to earth particles, that secures lasting anaerobic conditions, precipitates metals as sulfides and prevents re-oxidation of these sulfides. This process and its optimization are described, including experiments with sand-filled columns representing a vertical section through solid waste. Results of organic and metal retention in solid waste are provided from analyses of acid mine water drainage before and after waste treatment.

Jan 1, 2006

By Barry J. Turley

With over 700 large electric-drive haulage trucks operating in Canadian mining today and over 3700 in mines worldwide, most aspects of electric drive are well known. Recently, however, extensive application of these trucks to down-hill hauling in mountain mining makes it vitally important that many of us better understand the operation and proper application of the dynamic retarding feature of these vehicles. This paper is an attempt to clear up misunderstandings on this subject, to suggest precautions that mining operators should take in comparing competitive retarding systems and to challenge equipment manufacturers to evolve improvements to the important aspect of system performance.

Jan 1, 1978

By Scaife PH, Cripps Clark J, Cameron DB

Tuyere coke samples have been taken through the tuyere openings of B.H.P. International Blast Furnaces since 1978 with Whyalla No. 2 Blast Furnace taking samples on a regular basis since 1982. The degradation of coke during it&apos;s passage through the Blast Furnace can be measured and the relationships between these data, feed coke data and blast furnace operating data demonstrated. Tuyere coke sampling has been useful in revealing misleading external coke testing results and is still the method to monitor directly the performance of coke within the Blast Furnace.

Jan 1, 1987

By Jerry G. Craig

The Bureau of Mines has developed a computerized oil and gas well data retrieval system from studies of the waterflood potential of a producing reservoir. This system stores pertinent information about each well completed in a reservoir and facilitates selection and manipulation of large volumes of data. Use of the system enables reservoir information to be supplied rapidly, accurately, and at less expense.

Jan 1, 1971

By Errol L. Montgomery

The region of metalic ore deposits in northern Chile, southern Peru, western Bolivia, and northwestern Argentina occurs in arid zones at altitudes as high as 4,600 meters. Because surface water supplies are meager, new mines require unexploited sources of water. Prolific groundwater aquifers occur in salar basins in this region of the Andean Highlands. Exploration water wells have been constructed and aquifer characteristics have been tested in eight salar basins. Results indicate groundwater quality is good. Aquifer transmissivity and storage computed from results of pumping tests indicate maximum production water well capacities in excess of 170 liters per second.

Jan 1, 1982

By T. P. Lim, A. J. Vivyurka, N. K. Davé

Chemical and radioisotope stratification studies were carried out in an abandoned uranium tailings pile at Elliot Lake, Ontario, Canada. The tailings, with an average thickness of 7 m over an area of 16 hectares, were deposited approximately 20 years ago on a layer of black peaty material which overlays deposits of permeable glaciofluvial sands. Geohydro-chemical investigations of this tailings area have been ongoing since 1978. The radioisotope profile study was conducted on three adjacent sites. Solid core samples, collected with a split spoon sampler at various depths, were analyzed for various chemical and radioisotope constituents. The results indicated by 2 distinct zones of stratification; an upper zone, where the constituents were uniformly distributed, and a lower zone, near the peat-tailing interface, which showed increasing concentration with depth. Within the peat layer, the concentration decreased rapidly with no significant levels of contaminant penetration below the peat layers observed, though the samples were limited. The pH profile showed that the top 5 m of the tailings have been oxidized, the average soil pH in this zone was 3.4 compared to 5 .8 underneath it. The groundwater hydrology of the system was observed to be complex showing downward and lateral flow in the dry season and lateral and upward flow during the spring and periods of heavy rainfall. The results are discussed in terms of a model based on the combined segregation and settling process of the tailings fine fraction, and the geohydro-chemical interaction of the solid and liquid phases.

Jan 1, 1981