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By L. Trincado

Mantoverde is a heap leach-SX-EW plant that was commissioned in December 1995 at a production rate of 42,130 ton of copper per year and 5.4 million ton of ore per year. Copper production has steadily been increased to 57,290 ton in 2002. Forecast copper production for 2003 is 60,000 ton for an ore treatment rate of 8.5 million ton. Several improvements in the heap leach process have been implemented. The main process improvements are related to the optimization of heap height, particle size, irrigation rate and leach cycle, in addition to a better heap drainage design and a solution management system. A first dump leach operation was started in 1999 at a production rate of 1,922 ton of copper. A second dump leach operation was started in early 2002 at a production rate of 2,805 ton of copper. Dump leach production will be increased over time to as much as 24,000 ton of copper. The main heap leach process improvements, as compared to the original plant design, as well as the main dump leach operating parameters are discussed in this paper.

Jan 1, 2003

By Dinner Paredes

El presente trabajo técnico, denominado “Impulsando la competitividad minera en el Perú: La economía circular y los incentivos tributarios como elementos claves para el desarrollo de una minería sostenible”, tiene como propósito primordial analizar y resaltar la importancia que tienen los principios de la economía circular y los incentivos tributarios para promover un sector minero competitivo y sostenible en el Perú.

Sep 29, 2023

By Jorge D. Vier, Raúl B. Rebak, Alicia E. Ares, Natalia S. Zadorozne

Recent worldwide demand has driven nickel and molybdenum prices to record high values. Alloys containing significant amounts of nickel and molybde- num, such as the austenitic and duplex grades, have experienced significant price increases and some spot shortages have resulted in some regions. With low or no nickel content and reasonable molybdenum content, super-ferritic stainless steels are now proving to be the most cost effective corrosion resistant materials. The electrochemical behavior APMT® (Fe–21Cr–5Al–3Mo–0.04C) and 4C54® (Fe–26.5Cr–0.8Mn–0.5Si) super-ferritic stainless steel in NaCl solutions has been studied using open circuit potential measurements, potentiodynamic polarization curves, and electrochemical impedance spectroscopy. The aim is to compare the behavior of these materials with austenitic stainless steel alloy 316 (Fe–18Cr–10Ni– 2.5Mo). The results indicate that the APMT alloy presents a better performance than the AISI 316 stainless steel, while 4C54® does not, especially at anodic potentials. The good behavior of APMT® may be attributed to Al and Mo content in its composition.

Mar 1, 2017

By L. W. Helle

The investigation, which was conducted at Iscor's Newcastle works (in Natal), was aimed at the development of reliable, consistent, and cost-effective methods of sampling. In the sampling of hot metal, it was found that lollipop and spoon samples had identical sulphur analyses, and negligibly different silicon analyses. Thus, spoon sampling of the hot metal was implemented, with a resultant saving of over RIOO 000 per annum on lollipop samplers. In the sampling of steel, aluminium -killed samples were found to have lower phosphorus analyses than titanium killed samples. Spoon sampling was rejected in this application since the use of titanium wire would be too costly. It was decided that titanium would be used as the deoxidant in lollipop samples of steel, and that the Leco carbon! sulphur analyser would be used as the sole arbiter of sulphur content.

Jan 1, 1983

By B. V. Close

Surface mining regulations together with mine and reclamation planning require collection of large amounts of geologic and hydrologic data for both new and existing mines. Recently developed microcomputer software facilitates the integration of this information from computer databases into ground-water flow models. The databases are used to identify areas which require dewatering and/or depressurizing and for generating contour maps of aquifer parameters. Gridded versions of these contour maps are incorporated into finite difference ground-water flow models which are used to design dewatering and depressurizing well fields and to estimate the effects of ground-water pumping and pit progression on local ground-water levels.

Jan 1, 1988

By Anthony Iannacchione, Tim Miller, Nicole Evanek

The Subtropolis Mine is a room-and-pillar mine extracting the Vanport Limestone near Petersburg, OH. In February 2018, mine management began implementing a new mine layout to better control the negative effects of excessive levels of horizontal stress. Almost immediately, the conditions in the headings improved. Conversely, and as expected, stress-related damage was concentrated within crosscuts. Over the last 18 months, the mine operator has diligently experimented with different techniques/methods to lessen the impact of the instabilities in the outby crosscuts. The range of controls used by the mine operator include angled crosscuts, crosscut offsets, increased distance between crosscuts, arched crosscuts, cable-bolted crosscuts, altered blasting pattern, and windows. A window is used to resist roof deformation by leaving a strong brow of roof rock within the crosscuts.

By A. H. Leuschner, P. J. Kruger, J. Kruger

INTRODUCTION This paper deals with some practical aspects of the use and interpretation of dosimetric methods for assessing the exposure of workers to natural uranium. Consideration must be given not only to the scientific value of the method of dosimetry, but also to the practicality of the method in the particular working environment. It is generally accepted (IAEA, 1976) that uranium does not present a hazard during the mining and extraction processes up to the final concentration stage, that is precipitation as ADU or calcining to the oxide. Further processing (e.g. conversion to oxides, fluorides, etc.) is generally associated with the nuclear industry. It is customary for uranium processing facilities to be managed according to industrial norms rather than according to those applied for the purpose of radiation protection. This is mainly because of the large quantity of material to be processed and the fact that uranium is considered to be of a low radiotoxicity. Although ventilation is used to some extent, provision is not made for the same level of protection as would be required in a radiochemical facility. It is typical in such a plant to find that the process itself may be enclosed and ventilated, but the ventilation is inadequate to cope with an accidental release of material. The working environment is poorly ventilated, sometimes only by natural ventilation, and one frequently finds areas with high airborne dust levels, designated as mandatory respirator areas. Protection of personnel is dependent on personal protective equipment. Radiation protection is not of prime concern and personnel are not specifically trained in this subject. It is in this type of environment that acceptable monitoring procedures and personnel dosimetry must be established. The effectiveness and practical application of the dosimetry must also be judged against this working environment. DOSIMETRIC TECHNIQUES The methods available for assessing personnel exposure, whether it be in terms of chemical or radiological hazard, include urinalysis, faecal analysis and [in vivo] monitoring. Faecal analysis does not present itself easily as a method for routine use. Techniques for [in vivo] monitoring have been developed recently and as expensive instrumentation is required, it is not generally available. That leaves urinalysis as a dosimetric technique for routine use, and it is probably for this reason that urinalysis is still widely used. Guidelines for the interpretation of urinalysis results, as originally provided by Neuman (Neuman, 1950), are still used in practice, even though it has become clear that this method has severe limitations as regards the assessment of the dose as a result of the intake of class W or class Y compounds (Alexander, 1974). Typically a level of 300 µg [U/C] urine can serve as an indicator of an acute exposure (above which chemical damage to the kidneys may occur) and a level of 100 µg [U/C ] urine can serve as an indicator for an investigation. Such levels are determined and are used in conjunction with several factors, such as mode of intake (ingestion or inhalation), solubility of compound (D, W or Y), means of intake (acute or chronic), environmental monitoring results and frequency of urine sampling. Since the ICRP concept for internal radiation limitation changed from that of the critical organ, i.e. the single organ of greatest significance under the circumstances, to that of effective dose equivalent, i.e. account being taken of the total risk due to the exposure of all tissue, the maximum permissible organ burden (MPOB) was replaced as secondary dose limit by the annual limit on intake (ALI) (ICRP, 1977). The ALI values are calculated from the committed dose equivalents of the various organs, and are used to determine organ burdens, which are then used to interpret the dosimetric results. Using the ICRP model (ICRP, 1979), a comprehensive calculation was made by Johnson (Johnson, 1980), giving organ burdens and excretion data in terms of intake for acute and chronic exposures for different categories of uranium compounds. The question arises as to what extent the direct measurement of intake can be utilised as a method of dosimetry. This will require a method of personal intake measurement for each individual worker, with both ingestion and inhalation being taken into account. A measurement of

Jan 1, 1981

By Jozef Stachulak

Prof. H. Bystron: "An Application of the First Law of Thermodynamics to Winter Dry Air Flow in Mr. Stachulak's Mine Model". [ ]

Jan 1, 1980

By G. K. Manning, W. E. Few

WORK on the effect of vacuum heat treatment of 0.040 in. diam sintered and wrought molybdenum wires has been sponsored by the Office of Naval Research at Battelle for the past several years. An electrical resistance furnace' capable of maintaining a vacuum of less than 0.1 micron of mercury at temperatures as high as 4000 °F was used for heat treating the wires. Early in the work, it was found that the introduction of a few microns pressure of oxygen into the furnace resulted in a rapid increase in the oxygen content of the wire specimens and the appearance of a discrete oxide phase. Subsequent elimination of the oxygen atmosphere caused the disappearance of the oxide phase. This was used to determine the solid solubility of oxygen in molybdenum over the temperature range of 2000" to 3000°F.2 It was observed that, with the disappearance of the oxide phase, the wires regained some ductility. Single-phased wires possessed from 5 to as much as 40 pct elongation in 2 in. Later, attention became centered on determining the cause of this wide range in ductility. Wires containing less than 0.002 pct C, less than 0.0007 pct 0, less than 0.0005 pct N, and less than 0.00003 pct H exhibited the erratic ductility noted above. These percentages represent approximately the limit of accuracy of presently available methods of analysis and thus it became apparent that chemical analysis would be of little help in the study. A number of possible explanations for the wide range in ductility were suggested during the course of the work. It was first suspected that variations in the grain size of the recrystallized wire specimens might be responsible. Wire from several lots of material was available. One of these lots tended to develop very large grains when recrystallized, the others all developed an ASTM grain size of 3 to 4 when heated above 2700°F. No correlation between grain size and ductility could be found. It was thought that back diffusion of oil from the diffusion pump might cause contamination of the wire, principally with carbon, but when wires were treated without cooling the cold trap in the pumping system,

Jan 1, 1956

By W. J. Przybylowicz, V. M. Prozesky, D. de Bruin

"The common style of gold mineralization in the Basal Reef and other auriferous conglomerates of the Witwatersrand Supergroup comprises clusters of gold grains occurring interstitially to quartz and pyrite pebbles as well as gold accumulations attached to the surface of and infilling hairline cracks and fractures in round, compact, detrital pyrite. The latter textural association is generally interpreted as a result of remobilization of originally detrital gold during regional metamorphism and related hydrothermal fluid circulation. There is general agreement that, although gold solubility was low, ore modification occurred during the metahydrothermal event, but uncertainty exists about the magnitude and scale of gold remobilization.Micro-textural and chemical investigation of compact round pyrite and associated gold accumulation has established that gold is preferentially deposited on chemically heterogeneous pyrite surfaces. Combinations of alternating high- and low-As zones in pyrite result in mixed np-type conductivity accompanied by electron exchange and the reduction-driven deposition of gold at the cathode. This model does not explain gold accumulations which are not immediately linked to chemical heterogeneities and it is inferred that an additional control on the deposition of gold was exerted by physical defects which lead to zones of increased charge density and/or areas of focussed conductivity. The inferred precipitation mechanisms suggest that submicrocopic physical and chemical controls are the important factors that determined the sites of gold nucleation and that precipitation mechanisms based on physicochemical changes of the hydrothermal system were not involved. The Basal Reef contains on average close to 5OJo of round, detrital, chemically zoned pyrite which provides a large number of electrochemically active pyrite surfaces. The extremely effective electrochemical precipi- . tation mechanism together with the low solubility of gold in Witwatersrand fluids is the main reason for the spatially restricted remobilization of gold in the conglomerate reefs."

Jan 1, 1994

By Göckmann. Klau

"IntroductionCopper has been recycled ever since its discovery. Even in Graeco-Roman times recycling of this resistant, and thus valuable material was carried out as a matter of course. Just take, as an early example, the Colossus of Rhodes: after the figure collapsed during an earthquake, the bronze parts were melted down into ingots and sold.Copper is a material which can be recycled again and again because copper produced from recycling is not different from copper originating from primary materials. This is mainly due to electrolytical copper refining whereby not only the base metals but also the precious metals can be removed. In contrast, with aluminum and iron only the more electropositive elements can be removed by refining, and the resultant scrap must, therefore, be sorted mechanically into various alloys for subsequent smelting.The recycling rate for different base metals is given in Table 1. Despite this ideal prerequisite, the generally quoted recycling rate of copper of about 40070 appears rather low. However, it must not be forgotten that the recycling rate is defined as the ratio of the annually utilized quantities of copper scrap and the annual production figures (Table 2). Moreover due to the economic growth over the last 30 years the availability of copper from scrap materials is lower than its consumption because copper is principally employed in very long-life consumer durables and only returns to the recycling circuit after many years. The average time for the copper of some goods to be recycled is detailed in Figure 1."

Jan 1, 1992

By H. L. Gilbert, W. W. Stephens

Production of anhydrous zirconium tetrachloride by direct chlor- ination of a zirconium oxide carbon mixture in a silica-brick-lined chlorinator is described. Theory and thermodynamics of reactions are discussed. A pilot-model chlorinator and full-scale production equipment are described and operating data are included. ANHYDROUS zirconium tetrachloride required as a starting material in the Kroll process for production of ductile zirconium has been produced in this country principally by chlorination of the carbide or "carbonitride" made by reduction of zircon sand concentrates with carbon in the arc furnace. This process and the equipment used have been fully described.'.' It is well known that zircon or badde-leyite ores may be chlorinated directly with chlorine in the presence of carbon, and this one-step approach would seem at first glance to be preferable to the two steps involved in the carbide-chloride operation. As previously discussed1 considerations leading to adoption of the longer process were: 1—Chlorination of the carbide proceeds rapidly at temperatures below 500°C, whereas temperatures above 900°C were considered necessary for chlorination of zircon-carbon mixtures. 2—The highly exothermic nature of the carbide-chlorine reaction makes it self-sustaining, while heat must be supplied continuously in direct chlorination of the ore. 3—Silicon was thought to be chlorinated along with zirconium in the direct chlorination of zircon, leading to high chlorine consumption. In production of carbide in the arc furnace, silicon is driven off as silicon monoxide and does not enter the chlorinator. 4—For efficient direct chlorination, the ore must be finely ground and intimately mixed with carbon, and the mixture briquetted. 5—Direct chlorination requires a much larger chlorinator for a given production capacity than chlorination of carbide. Recently it has become necessary to produce large quantities of zirconium metal from a chemically purified zirconium oxide. Since the cost of the latter is high, the relatively high losses encountered in production of carbide in the arc furnace could not be tolerated, and a graphite resistor furnace5 was developed for production of carbide, which was then chlorinated in equipment previously used for chlorinating arc-furnace carbide. This method of operation was quite satisfactory, and losses in the carbid-ing step were minimized. However, operating costs were relatively high, and the process did not lend itself particularly well to large-scale operation because of the multiplicity of small units required and the hand labor needed to load, unload, and maintain the furnaces. To chlorinate the carbide, a vertical-shaft chlorinator was used in which the charge was heated with a central split graphite-rod resistor.' Operation of this chlorinator was somewhat less satisfactory with the resistor furnace carbide than it had been with the arc-furnace carbide due, principally, to the differences in physical properties of the carbide. The arc-furnace carbide is obtained as a fused metallic-appearing mass which can be crushed to -1/4 in. with production of a minimum of fines, whereas the resistor-furnace product is lightly sintered and produces a large proportion of fines in crushing and handling. These fines tend to pack in the chlorinator and promote channeling. which results in poor chlorine efficiency and low capacity. Data based on production of 22,000 lb of chloride from resistor-furnace carbide in this equipment are shown in Table I. Necessity for increasing production of chloride from about 2,000 to 15,000 lb per week led to further investigation of possible methods for direct chlorination of the oxide or oxide-carbon mixtures. Direct chlorination of the pure oxide presents much less difficulty than chlorination of zircon sand or oxide ores. The oxide is easily ground to —200 mesh, and no silica is present to cause excessive consumption of chlorine or contamination of the product. Theoretical Considerations The principal chemical reactions involved in chlorination of mixtures of zirconium oxide and carbon may be written as follows: ½ ZrO2 (c) + C(c) + Cl2(g) = ½ ZrCl,(g) + CO(g) [I] 1/2 ZrO, (c) + CO(g) + Cl2(g) = ½ ZrCl,(g) + CO2(g) 121 ½ ZrO2 (c) + ½ C(C) + Cl2(g) = 1/2 ZrCl4(g) + ½ CO2(g) [3]

Jan 1, 1953

By Ernest P. Hall

At the SME Fall Meeting held in Phoenix, Ariz. last October, Ernest P. Hall, addressing an Air and Water Pollution session, noted that water pollution caused by acid drainage from bituminous coal measures had begun long before recorded history. "Until recently," he said, "man did not begin to understand the physical phenomena which took place to cause [it] and even today he does not know what can be done to prevent it." CAUSES "It is known from the reports of early explorers that drainage from bituminous coal measures was causing water pollution before coal mines were opened on this continent. They noted the nature of the polluted water in the runs and creeks and predicted the presence of substantial deposits of coal based on the appearance and character of the water. Even today, polluted water drains from virgin coal areas which have not been touched by mining machines," Mr. Hall said.

Jan 1, 1966

GREETING Hail! Hail! the Coal Miner, Damn the operator, damn the operator, Hail! Hail to mining coal We'll tell 'em how to run the mines. Oh, we'll send out a questionnaire And we'll quiz 'em, we will razz 'em for fair, We'll ask about the profits and order them to stop it Tell the world we're going to stop right there. Hail! Hail! etc. NASH AND PRYDE Tune, "Gallagher and Shean" There are two mining men, the best I've ever spied, One is Mister Harry Nash, the other Mister Pryde. When these two fellows meet it surely is a treat, The things they do, and the things they say, And the funny way they greet. Say, Mister Harry Nash, Oh, Mister Harry Nash, Tell me what's on your mind this evening, Mr. Pryde; I have heard an awful lot of that steep coal mine you got, And I wondered if some one had up and lied. Oh, Mr. Pryde, Oh, Mister Pryde, It's so steep it seems to lie upon its side. If it were steeper than it is, it would put us out of biz, Absolutely, Mister Harry Nash, positively, Mr. Pryde. Oh, Mister Harry Nash, Oh, Mister Harry Nash, Somebody said that at this new mine you've begun 'Fore you mined a lump of coal, had to burrow like a mole, And of rock you dug out many a million ton. Oh, Mister Pryde, Oh, Mister Pryde, I hate to think of all the dough I supplied. I believe the Moffat Tunnel bore won't cost a single dollar more I don't think so Mister Harry Nash, I agree with Mister Pryde. PARTING Tune, "Leave Me With a Smile" Though a sea of strikes and low price squabbles, Follow us the while; Once a year we gather just to show them whether We still wear-a smile; Rocky music coal still packs a barrel full Of timely fun sans guile, Rocky Mountain Institute can follow such And smile its yearly smile.

Jan 1, 1924

By Naoki Hiroyoshi

It is generally accepted that ferric ions are effective for leaching chalcopyrite as an oxidant and ferrous ions contribute to the leaching only as a source of the oxidant ferric ions. However, this paper shows that ferrous ions are more useful for leaching chalcopyrite than oxidant ferric ions in sulfuric acid solutions in air at ambient temperatures. Leaching experiments and dissolved oxygen consumption measurements were carried out with a very pure chalcopyrite and 0.001 - 1 mol dm-3 sulfuric acid solutions containing 0 - 0.1 mol dm-3 ferric or ferrous ions at 303 K. Chalcopyrite oxidation with dissolved oxygen was promoted by ferrous ions but suppressed by ferric ions. As a result, the amount of extracted copper was larger with ferrous ions than with ferric ions. Effects of Thiobacillus ferrooxidans on the ferrous promoted chalcopyrite leaching were also investigated and discussed based on the experimental data.

Jan 1, 1999

Mr. Shepard's paper was unfortunately delivered extemperaneously so no record is at hand. He spoke most interestingly and at length on the oil shales of Colorado, giving his opinion as to the ultimate outcome of the oil shale industry. He explained his idea that it would be built up of comparatively small plants, each of which would make the crudes, or more exactly would roughly divide the crude into its fractions, piping or shipping the fractions to a Central Refinery, using the residue for fertilizer, as it runs very high in fertilizer salts. He recommended that this plan be taken up by Coal Producers, that they consider the possibility of breaking up coal and selling its more refined products in place of selling raw coal. He spoke at length of the various outlets for products of distillation. Mr. McDermott gave a very interesting talk later on work that is being done in the Northern Colorado field along these lines. Mr. McDermott mentioned the strange fact that coaly materials such as mother of coal appeared to give just as good or better results under distillation than did lignite coal. Messrs. Randall, Howe, Goddard, Danford, and Nash added interesting data covering the use of pulverized fuel, and this data will be collected and offered to the Institute later in the form of a paper. Mr. Young spoke of the use of powdered coal in small units for small plants, mentioning the system now being offered by an Eastern Iron Works for small heating plants.

Jan 1, 1922

By Murray D. Fredlund

The consolidation of soil material is central to many types of engineering analysis. Problems such as the building of highway structures, landfills, or buildings over saturated soft clays require application of such theory. It has been found in industry that the application of consolidation theory has lagged significantly behind the theory which has been developed some time ago. The application of small-strain saturated consolidation theory was first proposed in a 1D form by Terzaghi. Although this theory has been available for some time it?s implementation into software packages in 2D and 3D forms has been slow due to inherent complexities in the coupling equations. The flow and stress equations are also inherently somewhat unstable and this further complicates software implementation. Of particular interest in the mining industry is the consolidation of uranium tailings. One such disposal method that has been utilized is the subaqueous deposition of uranium tailings in large pit structures. When performing such deposition the calculation of consolidation rates is central to determining final pit capacity and expected life. Consolidation software can be successfully used in such cases in order to determine pit filling rates. The primary complexity, however, is that tailings are typically deposited in slurry form and therefore the potential deformations are large. Large-strain consolidation theory is therefore required in order to properly solve the deformations over time. This paper presents the use of a large-strain consolidation analysis in order to predict long-term filling rates in a uranium tailings pit.

Aug 1, 2010

By Zhanjing Yu

Longwall ground behavior in the Illinois Coal Basin was studied in the past (1, 2, 3). Most of the past studies, however, were concentrated on either surface subsidence or underground structural behavior. In this study, both surface and in-mine ground behaviors are considered, which include: 1) stress and deformation characteristics in the chain pillars; 2) roof and floor deformations; 3) surface subsidence characteristics, including time effect; 4) relationship between the surface subsidence and underground strata behavior; and 5) the ultimate hearing capacity underneath the chain pillars. Field measurements and tests were conducted and the data were analyzed using both analytical and statistical methods. The findings in this study can he used by mine operators in the Illinois Coal Basin for longwall ground control planning and design.

Jan 1, 1994

By G. C. Weatherly, D. S. Wilkinson, A. M. Limarga

In addition to the harsh environment, materials for high-temperature applications are often subjected to a significant mechanical loading. Several researchers have noted that the rate of oxidation can be affected by stress in a range of materials. We have recently studied this effect in y-TiAl, based on the preliminary work of Magnan and Weatherly which showed that nitridation rates on the tensile side of a flexural creep specimen could be 10 times higher than on the compressive side. We have since developed a four-point bending creep setup capable of controlled atmosphere testing. We present quantitative data on the effect of creep on scale growth under a range of atmospheric conditions. Finite element analysis will also be used to show how modest applied stresses can have a large effect on scale growth rates through the generation of large stresses due to the mismatch of creep rate between the metallic substrate and the scale.

Jan 1, 2004

By W. K. Utt, C. C. Woodward, W. L. Howie, G. G. Miller

The process of roof drilling and bolting is one of the most dangerous jobs in underground mining. In the United States, roof drilling and bolting results in about 1,000 accidents with injuries each year. Researchers, from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are studying the feasibility of using a drill-monitoring system to estimate the strength of successive layers of rock and assess the integrity of a mine roof. Such a system would allow roof drill operators to be warned when a weak layer is being drilled. Using measurements taken during drilling, a neural network can classify mine roof strata in terms of relative strength. The concept has been proven in principle. This research project was undertaken to increase the safety of underground miners, especially those involved in roof bolting. The system should be applicable to the mobile drills now used in underground mines, and the system would likely find wider application as well.

Jan 1, 2003