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By J. Gonzales

For this paper, blending is conceived as a linear process that takes a proportion from one stockpile or location and mixes it with another proportion from another stockpile or location, with the aim of obtaining a set of attributes in the final combination that satisfies a given quality standard. A blending class is the combination of ore attributes and grade limits that should be stockpiled in order to achieve the target quality for the process Plant. Current literature considers the number of blending classes in the Open Pit Scheduling Problem as fixed; however, this paper shows how to define specific blending classes for a given deposit so that the schedule can be solved with Sequential Linear Programming. Finally, a practical application in a Peruvian copper mine is shown, involving four ore attributes: alteration code, arsenic, oxide content and copper grade. INTRODUCTION In copper ore deposits, blending for quality has not been a typical issue as it was for coal and iron ore; however, current copper deposits in the world are becoming geologically and chemically more complex than in the past and is not uncommon to have quality standards involving up to four attributes, introducing an additional complexity to the mine scheduling process [1]. In order to solve the Open Pit Scheduling Problem with multiple ore quality constraints, two assumptions are necessary [2]: - Grade constraints are defined only by specifying an upper and lower limit; - Ore attributes in stockpiles are pre-determined, i.e., the upper and/or lower grade limits defining each stockpile are already known at the time of setting the schedule. Assuming each ore attribute is classified as high, medium or low, and there are four attributes to be controlled in the target ore quality, the number of possible blending classes would be 3^4 = 81. This number is impractical to manage in Operations, and increases the complexity at the time of running the schedule; therefore, a more efficient way of classifying ore is required. Note that in practice, one blending class can be split into more than one stockpile location due to physical capacity constraints. Therefore, the number of stockpiles could even be more than 81. BLENDING CLASSES DETERMINATION For a given set of ore grades with lower and upper limits to be achieved, one has to find all feasible ore classes such that when blended, their grades will lie within those limits.

Jan 1, 2019

By E. H. Christiansen

Gem-quality red beryl in the Wah Wah Mountains of southwestern Utah formed as a post-magmatic mineral in a topaz rhyolite flow. Unlike topaz, this beryl occurs along fractures in devitrified rhyolite, rather than in lithophysal vugs. The flow occupies a graben and perhaps a significant paleo-drainage. Beryl occurs at medial depths within the eroded flow, about 170 m below overlying mafic lava flows. Both beryl-bearing fractures and the host rhyolite show an unusual amount of argillic alteration compared with other topaz rhyolite flows. Alteration may be related to the incursion of surface water along shrinkage fractures within the flow. Whole-rock concentrations of CaO within the host rhyolite are very low (<0.01 % to 0.18%) compared with other topaz rhyolites and Be concentrations (about 20 ppm) are about average. Low Ca activities prevented fluorite precipitation and allowed Be transport as fluoride complexes. Beryl probably grew at subsolidus temperatures (-300-650°C), but above the temperature of kaolin development (200-300°C) as fluoride-rich vapors, released by devitrification, encountered fractures and mixed with vapors derived from surface water flowing through the fractures. Beryllium fluoride complexes reacted with water vapor, silica minerals, alkali feldspar, water, and Fe-Mn oxides along fractures to produce red beryl. Continued reaction of the cooling flow with surface water at lower temperatures probably produced a boiling, more acidic fluid that produced the argillic alteration. Consequently, eruption of low-Ca topaz rhyolite followed by entrance of surface water into medial portions of a devitrifying and still hot lava flow appear to be critical factors that led to red beryl formation.

Jan 1, 1996

By P. P. Gregory

Natural petroleum gas occurring in the oil-bearing reservoirs is found to exist either as free gas associated with the oil and/or in solution in the oil. In some virgin fields practically no free gas is encountered under the reservoir conditions of pressure and temperature, although in other fields a considerable section of the "pay" horizon is occupied by free gas. In other words, a given oil field may or may not have a gas cap before the exploitation takes place. However, when the reservoir pressure is reduced to a point below the critical saturation pressure by withdrawals of fluids from the producing formation, the gas dissolved in the oil inevitably begins to come out of solution and becomes free gas. Under the controlled methods of production and drilling, a portion of this gas is produced with the oil to the surface and a portion of it remains within the reservoir to accumulate at higher structural levels toward which it migrates by virtue of its low specific gravity. The rate of growth of a gas cap in a given structure depends primarily upon the rate of decline in the reservoir pressure. If the rate of pressure decline is rapid, the gas cap likewise will grow rapidly. On the other hand, shrinkage in the gas-cap area was noted in some fields in which reservoir pressures wereincreasing. Determination of Gas-oil Contact and Thickness of Gas Cap The gas-oil contact can be conveniently located in the process of drilling a well and by electrical logging. However, very little can be found in the petroleum literature concerning methods of predetermining gas-oil contacts in producing reservoirs. Therefore, the writer feels justified in describing briefly a simple, workable, and inexpensive method of determining gas-oil contacts and outlining the limits of gas-cap areas in a field where such knowledge may be essential for efficient production and development operations. The method involves the determination of the following data: (I) Structural data, such as the depth or elevation of the top&apos; of "pay" horizon; (2) reservoir pressures; (3) tubing and casing pressures at the well head; (4) static oil-pressure gradient; (5) static gas-pressure gradient. These data can be secured with a minimum of expense, inasmuch as the

Jan 1, 1938

By Bob Drew, Alfred Spanring, Kirschen. Marcus

"Increasing material conversion and energy efficiency, and decreasing carbon dioxide emission levels are crucial for sustainable production processes in the aluminum, cooper, and steel industries. RHI supports these targets by providing a diverse range of solutions including high quality refractory linings, optimum lining maintenance, and process improvements. In this paper examples are provided of process improvements and increased energy efficiency in copper refining, potential energy savings during electric arc furnace and ladle operations in the steel industry, and increased energy efficiency by improved heat transfer in anode baking furnaces in the aluminum industry. In all cases, RHI’s expertise in close collaboration with the customer resulted in an improved performance of the reactor lining and the actual high temperature process with a positive impact on the material conversion and energy efficiency and as a result a decrease in specific carbon dioxide emission levels.IntroductionRefractory linings play an important role in heat transfer during high temperature processes in for example the aluminum, copper, and steel production industries. Due to constantly increasing energy prices worldwide and the increasing demands for environmental and climate protection, improving the energy efficiency and decreasing emission levels of these energy intensive production processes is of significant importance. In this paper, the contribution of modern RHI lining technologies to energy saving measures and the corresponding reduction of specific carbon dioxide emission are described. The type of current refractory solutions for energy intense processes are illustrated with four examples: Optimization and increase of material conversion and energy efficiency in copper refining, energy saving potentials in both electric arc furnace and transport ladle operations in the steel industry, and heat transfer improvements during the carbon anode annealing process in the aluminum industry. These examples focus on particular production processes operating with a high proportion of recycled copper, steel, and carbon anodes. Increased energy efficiency directly decreases the specific energy related carbon emission levels whereas improvements to the metallurgical processes aim to increase material conversion efficiency and, therefore, decrease specific process related carbon emission levels. Significant energy savings can be achieved by maximizing the refractory campaign length through a combination of appropriate refractory material selection, grade zoning, correct installation, careful preheating, and effective maintenance strategies. Besides the efforts to improve the performance and energy efficiency of customer high temperature processes, RHI continuously promotes the development of new low emission carbon-containing refractory bricks and unshaped products."

Jan 1, 2008

By A. E. WALKER

SOME eighty years have elapsed since the discovery of the Clifton magnetite deposit. For a few years about the time of the Civil War it was mined for iron ore. most of which was smelted on the property. Since risen the small exposures of ore in the old cut. test pits, and on the dumps have been examined by various prospectors. The M. A. Hanna Co. first became interested in the possibilities of the deposit when we discovered the large area of strong magnetic anomalies caused by the margnetite bed, indicating a size that would support a commercial operation. In 1940 we made a detailed magnetometer survey of the area. and the deposit was diamond-drilled. The main ore lied was found to be 1500 ft. long, to average 60 ft. thick, and to dip southeast at an angle of about 40 deg. The thickness of the bed is irregular in wavy folds both along the strike. and down the dip. Faults occur at both raids of the main deposit.

Jan 1, 1943

By R. C. Emmett

Gravity sedimentation is one of the most widely used unit operations in mineral processing and hydrometallurgy. Properly selected and operated sedimentation equipment can provide probably the most economical means of concentrating solids or clarifying solutions. Because of the variety of different approaches possible, including the use of modern flocculants, it is easy to overlook the optimum approach in selecting equipment. The different types of sedimentation systems that can be used in the minerals field and the sizing methods that are currently employed will be discussed here. Sedimentation applications usually fall into two areas, clarification or thickening. While the two operations are basically similar, the difference in emphasis (a well-clarified overflow as opposed to a highly concentrated underflow) results in significant differences in testing, equipment design, and operation. Clarifiers may be merely simple settling vessels with no special features, other than ample volume to provide the detention time needed for suspended solids to settle out of the feed slurry. Or, they can be designed to employ elaborate solids-contact techniques utilizing coagulants or flocculants to achieve more rapid clarification through the growth of particle agglomerates. Thickeners also are available in a wide variety of designs, with the main differences concentrated in the design of the raking mechanism. Thickeners operating in series (continuous countercurrent decantation or CCD) are used to recover valuable solution or purify the insoluble solids. Tray thickeners are used for recovering fine particulate solids such as alumina seed, but in other applications have been supplanted largely by unit thickeners or inclined plate units. Thickeners and clarifiers sometimes are used for storage of either solids or overflow liquor, or employed as precipitating reactors, such as in desilication applications. The use of flocculants and coagulants is much more common in modern processing plants, primarily due to the reduction in capital costs rendered possible through the use of these reagents. The terms flocculant and coagulant are often used interchangeably; generally, it is understood that flocculants refer to organic, high molecular weight synthetic or natural polymers which are useful in flocculating most suspended solids, but generally are ineffective on colloidal suspensions. Coagulants refer to chemicals such as those commonly used in water treatment, alum, ferric salts, lime, etc., which are usually far more effective on colloidal solids but cannot achieve the degree of agglomeration that is possible with the polymers. In some cases, both coagulants and flocculants are used in order to achieve optimum results.

Jan 1, 1986

By James Humphrey

There is a natural resistance to change in any form. When it comes to implementing a game-changing technology like autonomous haulage on an operating mine site, the resistance can at times appear insurmountable. Whether based on real information or misguided preconceptions, it?s essential that we don?t underestimate the effort it will take to overcome this resistance, while clearly recognizing when it?s worth the effort. These realizations did not happen overnight for sites where autonomous haulage has been implemented. Nor did they happen overnight for manufacturers of autonomous mining equipment. Caterpillar, for example, began building toward autonomy more than 30 years ago and had a truck operating in the mid-1990s. Lessons learned during those early years led to the realization that there was much more to be learned ? not just about the machines themselves, but about the systems and knowledge that must be in place for a successful implementation. Working closely with customers, initiating real-life demonstrations on mine sites, having discussions with regulatory agencies and other stakeholders ? these and many other activities were necessary before autonomy could be fully and successfully launched. After decades of effort, Caterpillar?s first official commercial autonomous mine site went to work in 2011 in Farmington, NM.

By Chr. Kersch

This project further develops supercritlcal fluid extraction as an industrial soil remediation process. Heavy metals are removed from sand using CO2, The effect of the type of complexing ligands, pressure and water content on the extraction efficiency is investigated.

Jan 1, 1999

By Chapman RL

A new process has been developed to remove the impurities copper, cadmium, cobalt and nickel from a zinc plant electrolyte by cementation on zinc dust. The process has been tested in the laboratory and in a continuously operated pilot plant. It has been found that cadmium, in the presence of small amounts of antimony in solution, assists the removal of cobalt. Cementation is conducted in two stages: the first stage for removal of copper with a small excess of zinc dust to produce a relatively high grade product, the second stage for removal of cadmium, cobalt and nickel by addition of zinc dust in the presence of anti- mony. The excess zinc and the cadmium present in the second stage cementate can be selective- ly recovered by slow leaching in spent electrolyte. Zinc dust processes in use elsewhere are described and compared with the present system for use in the Risdon circuit.

Jan 1, 1984

By Veerendra Singh, NILAMADHABA SAHU, ARIJIT BISWAS

Manganese (Mn) ferroalloys are chiefly consumed in the steelmaking process as a deoxidizing agent or as an alloying element to produce high-quality steels. These alloys are typically produced in a submerged arc furnace using coke, fluxes and manganese ores of a specific manganese/Fe (Mn/Fe) ratio. Preferred-grade manganese ores should have Mn content greater than 46 percent and Mn/Fe content greater than 5 to produce commercial-grade, high-carbon ferromanganese [1]. Selective mining of high-grade Mn resources has created a scarcity of these resources, which is emerging as a major challenge for the manganese and steel industry. Manganese ore resources are mainly distributed in South Africa, with about 32 percent; Ukraine, with about 17 percent; Australia, with about 17 percent; and Brazil, India, China, Gabon and Mexico, with lesser amounts.

By Swades Kumar Chaulya, Vikash Kumar, Sushma Kumari, Naresh Kumar, Girendra Mohan Prasad, Monika Choudhary

Opencast mines are vulnerable to inclement weather conditions as it disrupts the day-to-day activities at these mines. To address the problem, a perceptive driving assistant system (PDAS) has been developed to increase the visibility of real-time video of the road in front of the vehicle for operators of heavy earth-moving machinery (HEMM) at opencast mines in harsh weather conditions.

Apr 1, 2023

Equipment-washing facilities at Freeport-McMo-Ran?s Sierrita Mine in Arizona produce a mixture of oil and water that was difficult to dispose of easily or cheaply. However, after some changes in the facility, waste oil is now used as part of the mining process. Freeport-McMoRan Copper & Gold Inc., head-quartered in Phoenix, AZ, operates copper, gold and molybdenum mines. It is the world?s largest producer of molybdenum. Heavy equipment used at the mine is hosed off periodically in the wash bay. The dirty water and oil mixture drains into the sump next to the bay. Oil was manually collected for disposal. This was a tedious and dirty process Mine managers sought a more efficient method of removing the oil. Instead of spending the time and effort skimming the tank with vacuums or sorbents, they enlisted the help of Abanaki Corp., manufacturer of the Model 4 Oil Grabber. Engineers designed the sump to utilize prevailing winds to blow the oil to one corner. This was the ideal place for the Abanaki skimmer. The skimmer removes the oil and discharges it into a plastic storage container. ?This reduces the time needed to keep the area clean, and the staff can focus on cleaning the equipment rather than worrying about the oil,? according to Jay Salerno, construction manager at the Sierrita Mine. Salerno is considering adding an optional oil concentrator to the skimmer to make the process even more efficient. The concentrator would remove any water picked up by the belt and return it to the sump, leaving nearly pure oil for disposal. Because the mine is located in the Sonoran desert, most of the water evaporates in the hot, dry air and is not reused.

Jan 1, 2009

By B. K. Choi, S. H. Kang, G. E. Kim, K. B. Kim, S. Noh, T. K. Kim, H. J. Jin

Oxide dispersion strengthened (ODS) steel is being considered as an in-core structural material of future nuclear reactor systems because of its excellent creep and irradiation resistance on the basis of uniformly distributed nano-oxide particles with a high density, which is extremely stable at high temperature in a ferritic/martensitic matrix. Up to now, ODS steels have been intensively studied and developed to apply these materials to the in-core structural component of future nuclear systems. The primary activity is to develop high strength advanced ODS steel, fabrication technology for the structural components and key joining technology for the component fabrication. As a result, a Fe-10Cr-1Mo alloy with a superior creep resistance at high temperatures has been developed. An optimized fabrication process of this alloy system has been established through various process conditions in mechanical alloying, hot/cold working, and heat treatment processes. Joining technology for the ODS steel components is also being developed using solid-state welding such as magnetic pulse welding, friction stir welding and diffusion boding. These R&D activities will contribute to the realization of ODS materials for future nuclear reactor system applications.

Jan 1, 2015

This paper summarises the development t,) date for the Hidden Valley Gold (HVG) Project. It starts with the original exploration work, covers the detailed feasibility study activities and concludes with the current phase of extra exploration drilling. A brief technical summary has been made from the various mining, process and environmental studies that were undertaken as part of the project approval process. A discussion of the influential non-technical factors is included, as well as a view of the future prospects for an operating mine. The project was always seen as marginal, given the low grades, small resource and short mine life. However the capital and operating costs were lowered with aggressive design and it was regarded an acceptable development by CRA. The opportunity was taken to review the project when delays in start-up were encountered. An updated financial evaluation showed a subeconomic resource in 1990 terms and this resulted in a new exploration phase to identify a larger deposit.

Jan 1, 1991

By O. A. Ojo, R. G. Ding, M. C. Chaturvedi

In this study, the fusion zone microstructure of tungsten inert gas weld of a directionally solidified NhAl-base alloy was examined by the standard metallographic techniques involving the use of optical, analytical scanning and transmission electron microscopes equipped with energy dispersive spectrometer. Fusion zone cracking was observed to be closely associated with interdendritic secondary solidification microconstituents identified as consisting of y, y&apos; and NiMo (Y) phases. Depression of solidification temperature to the terminal ternary eutectic reaction temperature of the system during cooling is suggested as an important factor contributing to the fusion zone cracking.

Jan 1, 2006

By M Manefield, G Bournival, S Ata

Asteroids contain an abundance of valuable resources such as: nickel, cobalt, gold, platinum and rhodium. Whilst the consumption of mineral resources on Earth continues to deplete, meteoroids have the potential to become a significant source of minerals. Even though the minerals content of asteroids may be relatively high, the valuable minerals are more likely to be only a small portion of the total ore present in the main body. The ores must, therefore, be processed to extract the metals of interest from the waste. Existing terrestrial technologies rely on manipulating the physical and chemical properties of minerals. The application of these techniques to asteroids processing, however, is not straightforward due to the presence of different conditions such as zero gravity and lack of water in space. This paper discusses potential separation and extraction techniques that can be used for processing of asteroids.CITATION:Ata, S, Bournival, G and Manefield, M, 2015. Resource recovery in space, in Proceedings Third International Future Mining Conference, pp 275–280 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By Z. Xingrong, L. Jiongtian, Z. Yangge, C. Yijun, L. Liang, H. Yangjia, H. Long

In this present research, a polymer poly (acrylamide-allyl thiourea) (PAM-ATU) with an average molecular weight 1.66 × 104 g/mol was used as a depressant in the flotation separation of molybdenite from chalcopyrite and galena. The micro-flotation experimental results showed that PAM-ATU exhibited a strong influence on the flotation performances of chalcopyrite and galena, but had little effect on that of molybdenite within a pH range of 9.0~11.0 at a dosage of lower than 6.0 mg/L. The flotation results of bulk flotation tests illustrated that PAM-ATU showed a stronger depression power than sodium thioglycollate (TGA) and sodium sulfide. The comparison results demonstrated that PAM-ATU and TGA had an advantage in reducing galena and chalcopyrite impurities in the molybdenum concentrate, respectively. With the combination of PAM-ATU and TGA, a good flotation separation result was achieved through one roughing operation where the recovery of molybdenum in the froth product was over 75.0%, while the recovery of copper and lead were less than 22.0% and 15.0%, individually. It was also found that a molybdenum concentrate with Mo grade of 46.32%, Cu grade of 0.16%, Pb grade of 0.06%, was obtained by a closed circuit flotation flowsheet of one roughing-three scavenging-five cleaning with a Mo recovery of 77.67%. Keywords: PAM-ATU, molybdenite, depressant, chalcopyrite, galena

Jan 1, 2020

By K. Narayan Prabhu, W. D. Griffiths

"Heat transfer during the unidirectional solidification of a cast iron alloy against cast iron chills was investigated using an inverse modelling approach. Chills of thickness 100 mm and 10 mm were used, to simulate gravity die cruiting conditions and the use of chills in sand moulds. In both cases transient heat transfer, measured by the interfacial heat flux and heat transfer coeffieient; declined from initially high values in the first few seconds of solidification, to values about an order of magnitude lower which persisted for the remainder of the experiments. In the case of the thin chill it became saturated with heat until it was no longer in a position to extract further heat from ·the casting. These results were interpreted by studying the resistance to heat transfer from the casting offered by the ·casting-chill interface and the chill itself for example, the thermal resistance of the casting-chill interface can be influenced by the deformation of their respective surfaces and their subsequent relationship.IntroductionDie casting cast iron offers several advantages such as energy savings, higher mould yield, and better surface quality over the sand casting process1 • The process is· environmentally' friendly because of the elimination of the sand. However the design and construction of metallic moulds is expensive and a faulty die design may result in a defective casting: A simulation based process design of die castings would enable die designers and solidification modellings to try better designs of dies on the computer and arrive at a cost effective solution more quickly. This has numerous benefits for the die caster, as he would be able to produce sound castings with very short lead times.The success of a solidification model to predict accurately the thermal history and the location of hot, spots inside a solidifying casting depends to a large extent on the heat transfer data prescribed at the metal/mould interface. Many measurements of the heat transfer coeffident (or the heat flux) between a solidifying aluminum alloy and a chill have shown that the heat transfer coefficient is a function of most of the variables of the casting process2 - 8. However heat transfer studies during the solidification of ferrous alloys are rather limited. The high temperatures involved suggest that the contribution due to radiation heat transfer cannot be neglected."

Jan 1, 2000

By Loic Galisson

"Urban tunneling projects are usually extensively monitored. Most of the instruments used rely on benchmarks providing a sustainable datum throughout the life of the project. The monitoring program also is based on a predicted model of deformation induced by specific construction methods. Events can interfere with those assumptions and eventually alter the stability of these datum. In addition, the anticipated ground conditions and hence the theoretical deformation model often differ from reality. Satellite Radar Interferometry provides useful information to overcome the weakness of the hypothesis made before construction. It is also a powerful tool to ensure the continuity of the monitoring program throughout the life of the project, accurately describing the true effect of the project on the surrounding environment. This paper emphasizes the benefits and limitations of this technique for urban tunneling applications, illustrated by examples of major tunneling projects around the world. MONITORING URBAN TUNNEL PROJECTS Why Monitoring? Retrofitting existing tunnels or constructing new tunnels – including access and retrieval shafts, portals and cross passages – implies an alteration of the neighboring soil structure. Excavating, dewatering, grouting, loading tie backs, etc. artificially modifies the natural equilibrium of the pore-water pressure, of the water table level and of soil stability. In many cases, the effects are immediate: ground loss, deformation of utilities, settlements of buildings, and distortion of infrastructure are a few examples resulting from construction activity.Instrumentation and Monitoring Scope To control and mitigate the risks of damage associated with the above effects, tunnel projects usually include an instrumentation and monitoring program. Depending on the level of geotechnical, structural and environmental risk, the magnitude of this program varies. Projects with a low exposure to risk may restrain the program to conventional methods such as limited topographical surveys and intermittent manual readings of geotechnical instruments. On the other hand, iconic projects with high risk or with controversial history may implement complex and extensive instrumentation plans, involving highly technical solutions such as Automated Motorized Total Stations (AMTS – see opposite Picture 1), Multi-Point Borehole Extensometers (MPBX), In-Place Inclinometers (IPI) and a wide series of fully automated geotechnical, structural and environmental sensors. In this case, all the devices are usually connected to field data loggers collecting raw data around the clock at frequencies ranging from days to seconds, depending on the sensors."

Jan 1, 2016

By Charles E. Mauk

In 1970, recognizing the great need for an economical, high capacity chemical oxidation process for wastewater treatment, Houston Research began a fundamental study of the available technology, Included was waste characterization; oxidation chemistry for molecular oxygen, ozone and catalyst initiators; kinetics of reaction; gas-liquid contacting methods; and optimization of staged reactors for mixed wastes. Although ozone is the most powerful oxidizer available, the literature contains contradictory reports of its speed and effectiveness. It is now felt to be most likely that many of these early investigations were limited by the ineffectual transfer of ozone from the gas phase into the liquid, and so the investigators were really observing the effects of mass transfer and erroneously trying to interpret the results as if they were chemical reaction data. HR&apos;s work considered the cost and effectiveness of gas-liquid contacting in a packed tower, gas sparged contactor, ejector with hold-up tank, and a completely mixed, sparged contactor. The sparged, mixed contactor was found to be most effective and least expensive, and a later investigation settled on the reactor configuration shown in Figure 1 because of its effectiveness of mass transfer and because it lends itself to direct scale-up techniques using laboratory data to design larger reactors.

Jan 1, 1975