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By M. Selamat, J. Nirdosh, S. V. Muthuswami

High-grade uranium ores of Cluff Lake and Key Lake mines from the province of Saskatchewan in Canada are treated with nitric and hydrochloric acids with the objective of leaching 230 Th and 226Ra simultaneously with uranium to produce environmentally safe mill tailings, h is found that optimum conditions for uranium leaching are 50°C, 4 h, 30% solids in leach slurry and an acid concentration of 1 mol/L for HNO, for both the ores. In the case of HCl, a 3 mol/L acid concentration is needed and addition of an oxidant is required because otherwise 230Th and 226Ra extractions remain poor.

Jan 1, 1990

By H. Suharyono, M. Lutsky, R. Hogg

Sediment consolidation in highly flocculated suspensions occurs only if the self-weight of the material exceeds its compressive yield stress. A simple model for sediment densification is presented and applied to the simulation of thickener operations. Measured relationships between sediment self-weight and the extent of consolidation are used to establish underflow densities. Supernatant turbidity data provide the information necessary to predict overflow clarity. It is shown that thickener depth can play a role in determining solids-handling capacity as well as dewatering performance. The application of the model to the design and operation of full-scale thickeners is described.

Jan 1, 1995

By M. S. Celik

Unlike most other minerals, electrokinetic measurements of calcium montmodonite (a clay mineral) and u1exite (a boron mineral) exhibit an unusual behavior. While the addition of monovalent salts such as NaCI and KCI is expected to compress the electrical double layer with a resultant less absolute charge, an opposite trend is observed. A set of systematic experiments with monovalent and multivalent ions has been carried out to understand the mechanism of this phenomenon Examination of the results reveals that the behavior of montmorillonite is dictated by the exchangeable divalent cations at the edges which undergo an exchange process with monovalent cations resulting in the reduction of positive charges. The solubility of ulexite, on the other hand, is found to decrease with increasing monovalent cation concentration leading to again an increase in the absolute negative charge.

Jan 1, 1996

By Sidney L. Hansen

This report was written because of concerns of the possible error involved when stopping leakage is incorrectly assumed to be turbulent. It is common practice to use turbulent flow to characterize each airway branch for computer models of mine ventilation circuits. This report addresses computer methods to accurately model air-leakage paths. A graphical method is described for deriving the equations of leakage through stoppings. The significance of modeling leakage according to the proper flow regime (turbulent or laminar) is demonstrated by the following method. A hypothetical mine was developed to represent present-day conditions. The stoppings of the mine were chosen to leak according to laminar flow properties. The mine was represented by constructing two base models. One base model used turbulent leakage equations for each stopping, while allowing the corresponding resistances to vary. The other base model used the correct laminar leakage equations and held corresponding resistances constant. The mine circuit was then expanded to demonstrate future development. The expanded portion was designed with stoppings that were identical to those in the base mine. The mine in the future state was represented by two projection models. Each projection model was an extended version of its associated base model; one used turbulent leakage equations and one used laminar leakage equations for stoppings. The laminar projection was theoretically correct and is used as a basis for comparison of differences in airflow quantities. Rather than modeling every leakage path for stoppings, a more practical approach is also discussed. A good level of accuracy is maintained by combining leakage paths if the proper flow equations are used. This method was used on the hypothetical mine projection and the flows were very similar to the theoretical values.

Jan 1, 1989

By Sandeep Upadhya, Marc Morgan, Baljinder Bassi, James Fletcher, Mike Deevy, Nishant Nayan

"In order to protect public safety in the event of a deliberate fire attack, underground rail authorities are increasingly considering the need to design for arson-initiated fire scenarios. Where typical design fires for modern rolling stock mean a peak fire size is reached after 12 minutes, an arson-initiated fire reaches its peak within 2-3 minutes. We present the innovations required to successfully incorporate this requirement on a recent design-build project. In stations 3D modelling is used to optimise smoke reservoir designs, smoke chimneys, station boxes and tunnel geometry to allow coordination with structural requirements. In tunnels, novel coupling of one dimensional network modelling and 3D Computational Fluid Dynamics (CFD) is used to improve assessment of complex fire scenarios. Finally, the impact on tunnel structures is assessed through comparison with standard time-temperature curves and risk of explosive spalling. INTRODUCTION An increasing regulatory environment and the appreciable influence that terrorist incidents have had on public safety policy have motivated the need to protect against large arson fires, especially in civil structures and public transport systems. With a greater reliance of a growing urban population on underground subway systems, design of such infrastructure is continually being reassessed and developed worldwide. Underground rail authorities are paying increased consideration to the design of fires - with properties beyond the upper regions of growth and intensity - amongst arson fire studies. Use of fire hardened materials on modern rolling stock means fires caused accidentally can be expected to develop relative slowly. However, recent experiments involving large initiating fires (as would result from an arson attack) have shown rapid fire growth rates and flashover leading to greater maximum heat release rates, Hadjisophocleous (2012), White (2010), and Lönnermark, et al. (2015). This paper describes the challenges and innovations required to complete a detailed design to control smoke from such aggressive super-fast growing fires. Computational modelling is used to demonstrate the required smoke control design by configuring the mechanical exhaust system combined with careful coordination with the architectural and structural design. The design objectives are to provide tenable egress paths in accordance with NFPA 130 (2014) and fire-fighting access. Finally, analysis of the design fire is used to inform the tunnel lining design, reducing the risk of explosive spalling, protecting the asset in the event of a severe fire."

Jan 1, 2016

By Kerry Spickelmier

A traveler driving across desolate central Nevada to the Round Mountain property can easily identify with turn- of-the-century prospectors seeking a fortune, or at least an existence, from the high desert. But now a shadow passing overhead is as likely a sophisticated fighter aircraft from Stillwater Naval Air Station as a circling bird, and the famous trails west show only as historical markers along the highway. Even the approximately 400- km (250-mile) trip southeast from Reno or northwest from Las Vegas takes hours now, not days. And the camps of Round Mountain’s early prospectors have been replaced by one of the world’s largest gold heap-leaching operations. While Round Mountain’s uniqueness begins with its scale, it doesn’t end there. Consider the mine’s low cutoff grade of 0.2 g/t (0.006 oz/st) gold, made possible by a new dedicated (not reusable) leach pad. Also, the operation’s degree of automation means that ore dropped in the south crusher system is not manually handled until it is stripped from the pads. There is the bonus of a geothermal field that is tapped to heat the leach solutions in the winter. And, of course, there was that “unexpected” hitch expected in all mining operations. For Round Mountain, it meant buying a gravity plant to process the gold nuggets discovered last summer in a fault gouge.

Jan 1, 1993

By V. Karra, G. Beerkircher

Application of the innovative WaterFlush® crushing technology to the processing of gold, copper, and iron ores is presented for retrofit circuits and productivity gain in each case is stated. New operations containing WaterFlush are described in brief.

Jan 1, 1995

By Jacob D. Baker

Sulphur dioxide is a versatile gas which has many uses throughout Pulp & Paper, Chemical, specialty Chemical, Mining and other industries. During recent years, S0 2 consumption and distribution patterns have resulted in renewed interests for liquid S0 2 and on site gaseous S02 manufacturing facilities. one relatively new use for S0 2 in the Mining Industry is its use for cyanide detoxification. Our purpose in this paper is to describe the process steps, economics and general technical features of so 2 gas generation using a Jet Type sulphur Burning System.

Jan 1, 1991

By Roger Holmberg

INTRODUCTION The driving of drifts is a very important aspect of underground mining. It is not unusual for the percent¬age of rock broken during development in a mine using sublevel caving, for example, to be as much as 25% of the total. If one also considers the amount broken for transport, ventilation, and exploration drifts, one can easily understand that the planning and excavation of drifts play a major part in the total economics of the mine (Fig. 1). Increasing mechanization in mining demands larger tunnel areas for transport and mining equipment. With modern machines the hard work involved in using hand¬held pushers is gone, and a better environment is achieved. More rational methods could be used, but much of the experience the working man acquired by working close to the rock face (such as utilizing the natural weak planes in the rock when he placed the drill¬ing holes) has unfortunately been lost. By having sepa¬rate shifts for drilling, loading, and hauling, more atten¬tion has to be placed upon a well-designed drilling pattern. Some reduction in the number of holes required can be achieved with mechanized drilling because of the larger holes that can be produced. On the other hand, it is probably not possible to achieve the same precision as with pneumatic pushers, and it is difficult to utilize the larger holes because these cause more damage to the re¬maining rock. Recently, however, the precision has be¬come very good with the parallel booms and automatic devices for setting the lookout angle (Fig. 2). A larger arch of the drift roof requires a more carefully executed blasting procedure than before in order to prevent rock fall and to insure a sufficiently long stand-up time. In this chapter, empirical relationships that can be used to design an economic and optimal drift blasting design will be presented. The principles of the calcula¬tion method are based upon the earlier work of Langefors and Kihlström (1963) and Gustafsson (1973). COMPARISON OF EXPLOSIVES To provide for the use of various explosives it is necessary to have a basis of comparison. Several meth¬ods have been developed to characterize the strength of an explosive. Some examples are comparison of values given by (1) calculated explosion energies; (2) the ballistic mortar test; (3) the Trauzl lead block test; (4) the brisance test; (5) the weight strength concept; and (6) the underwater test. However, most of these meth¬ods should be used carefully when stating the breaking

Jan 1, 1982

By J. Stephen Slottee, Jerold Johnson

The use of a thickener, without filtration, to produce a non-settling paste (also called thickened tailings) with non-Newtonian rheology has been practiced in Australia for many years for the disposal of red mud. The application of paste thickening technology outside of alumina is relatively new. Interest and installations in paste thickening are rapidly growing. Water shortages and environmental pressures make consideration of thickening tailings to solids concentrations within the paste range necessary in most new tailings projects. The paste thickeners at the DeBeers CTP plant in Kimberley, South Africa are the latest example of paste tailings disposal on the surface, also called “stacking”. Houman (2003) The use of a paste thickener as an alternative to filtration for mine paste backfill is a more recently developed application. This paper describes the principles of design and general operating characteristics of a paste thickener compared to the conventional and high-rate thickener. The application and operating performance of paste thickeners in mine backfill is discussed as an example. An integrated approach to process design is described that matches the performance of the thickener, pumping system, and application on a common rheological basis to ensure that none of these steps prevents achieving process performance targets.

Jan 1, 2005

By N. Rajmohan, K. T. Jacob

Presented is a thermodynamic feasibility analysis of extracting base metal chlorides from low-grade, multi-metallic oxide ores using CaC[1]2 as a chlorinating agent in the presence of SO2 and O2. The oxides react to form corresponding chlorides, while CaC[1]2 is converted to CaSO4. The Ellingham diagram is used for comparing the standard Gibbs' free energy change for the sulfation-chlorination reaction of a large number of oxides. Except for alumina, silica and chromia, most of the other metal oxides will be converted to their respective chlorides. The volatile chlorides can be condensed, and the chlorides present in the condensed state can be leached. A process is proposed that uses a nontoxic chlorinating agent and gives an efficient separation of the metallic values from the gangue.

Jan 1, 1993

By M. H. Pelkki, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

Research has shown that excessive soil compaction is detrimental to the establishment of trees in reclaimed soils. Dry bulk density and penetration resistance are two soil parameters that can be used to indicate the level of compaction in reclaimed soils. It is believed that reclamation practices which minimize soil compaction will produce better results when forestland is the intended post-mining use. The University of Kentucky has developed reforestation test cells on reclaimed soils at a surface mine in eastern Kentucky to test this hypothesis. Each test cell has been planted with various species of trees, and since 1997, data have been collected at these test cells for soil average dry bulk density, average penetration resistance, average depth to refusal, and average survival rate of trees. These data have been correlated to determine the relationship between soil compaction and tree survival rate. It is believed that the two soil compaction parameters may ultimately be used to predict tree survival rates on reclaimed surface mined lands.

Jan 1, 2001

By S. Atak, G. Bulut

The xanthate adsorption mechanism on pyrite was investigated with an emphasis on solubility studies. Additionally, adsorption studies, Eh and infrared spectrophotometer measurements were performed. Pyrite floats at pH levels between 3 and 6 using ethyl and amyl xanthates with a maximum at pH 4. The solubility of pyrite in the absence and presence of xanthate was investigated in detail with respect to pH and conditioning time. Experimental results showed that the solubility of pyrite increases from 60 to 120 ppm (10-3 to 2x10-3 mol/ L) in the presence of xanthate at pH 3. Fourier transform infrared (FTIR) spectra of ferric xanthate, dixanthogen and pyrite conditioned with xanthate indicated that dixanthogen is the only species that can be determined on the pyrite surface. Adsorption tests showed that the highest level of xanthate adsorption was in the acidic range; yet higher adsorption densities were detected in neutral solutions compared to alkaline conditions. Electrochemical data suggest that the doubling of the iron concentration is due to the reduction of ferric ion to ferrous by xanthate while xanthate is oxidized to dixanthogen. Dixanthogen formation together with the hydrophobic iron hydroxy-xanthate complex on the surface is proposed to be responsible for pyrite flotation. Key words: Flotation, Pyrite, Adsorption, Xanthate, Dixanthogen

Jan 1, 2003

By W. R. Hibbard

Emerging from discussions of U.S. energy policy: from the Project Independence Blueprint; from President Ford's statements to Congress; and from several independent appraisals of the situation; there is a clear objective to achieve an appropriate balance of supply and demand in the near term future (1) by developing more efficient ways of using energy and (2) by extending domestic sources of energy. More specifically, the strategy for achieving this goal has three parts (1) Conservation of energy through greater efficiencies in automobiles, appliances, lighting, heating, and industrial processes. (2) Increased domestic production of oil and gas through new sources such as the outer continental shelf and new efficiencies such as tertiary recovery. (3) Substitution of coal and uranium for oil and gas in utility power plants and industrial heating. The goal of energy research and development is to help achieve these goals and to help minimize the economic, environmental and social impact of our shift from imported energy to domestic sources. The focus of this paper is the implications of the expanded use of coal, and the research and development which may help achieve the above goals in so far as coal is concerned.

Jan 1, 1975

By E Marambio, R Brändle, G Fischer, G von Rickenbach, M Fuentealba, L Burgos, R Luis Fonseca

In underground excavations, under high stress conditions, ground support systems must provide safe and effective response to dynamic events. These systems must be capable to resist dynamic impacts and yielding during the loading process. In this context dynamic testing of the reinforcement and retaining elements that compose the ground support system are required to study and improve the behaviour of these elements under dynamic load events. During the last years, Geobrugg has been working on the improvement of retaining products by testing them in a large-scale impact test facility located at Walenstadt, Switzerland. The test facility is composed of a double level platform with a square-shaped pyramidal trunk geometry, in the upper level housing a loading mass that drop from a height up to 5m. The loading mass is guided by one central steel pipe, and the impact occurs in the sample to be tested located at the lower level in a slab with an area of 3.6m × 3.6m where the ground support system is installed. During the last years, this innovative facility has been used to test several configurations of ground support systems. The results of these tests have enabled to improve the understating of the behaviour of ground support systems under dynamic loads. In this manuscript, the back analysis through numerical methods (central difference and Newmark’s method) of a ground support system tested with a double dynamic impact in 2019 is presented.

Apr 26, 2022

By Dana A. Echter

The Paso Diablo coal project is located in the Guasare Basin in the northwestern region of Venezuela near the border with Colombia. In 1987, Carbones del Guasare SA, a joint venture comprised of Carbozulia and A.A. Antilles Coal (an Arco and AgipCoal joint venture) was formed to develop the Paso Diablo coal reserves for world markets. Regional drilling has indicated a coal resource of more than 6 Gt (6.6 billion st). Further exploration has delineated the Paso Diablo deposit as an area particularly suited for cost-effective surface mining. The calculated economically minable reserves of this area (200 Mt or 220 million st) and the coal quality characteristics are based on extensive core drilling programs. Initial coal mining operations began in August of 1987 and the mine is presently producing at a rate of 1.5 Mt/a (1.65 million stpy). The coal is hauled about 85 km (53 miles) to a barge loading terminal at Santa Cruz de Mara using highway-type haul trucks. When the coal reaches the terminal, it is loaded into barges and then transloaded onto ocean-going vessels with barge mounted

Jan 1, 1990

By Leonard Harris

Mining is a business and, therefore, is expected to make profit for its investors, like any other business. It is a risky business which requires the expertise of professionals from several disciplines to make it successful in the finding, evaluation and development of a new mining venture. Many of the same disciplines, as well as experts in some other fields are required to operate the facilities once they are built. To manage all this, wide-ranging, versatile and sharp managerial skills are required. On the U.S. domestic front, the most important management issues requiring attention today and tomorrow are the increasing unwarranted attacks by anti-mining groups and legislators on the industry and aided by an unchallenged, but widespread, public view that mining is not necessary and damages the environment. Higher costs to mine and process deeper and more refractory ores are also of great concern. More and more attention is being focused, therefore, on overseas projects under the belief that undeveloped countries will recognize the economic value of mineral production and that lower costs can be achieved.

Jan 1, 1993

By J. Snowberger III

Rhenium is a valuable and extremely rare chemical element with unique chemical properties. It is extracted commercially as a byproduct from the processing of molybdenite associated with porphyry copper ores. There is a present interest in recovering rhenium from copper pregnant leach solutions (PLS) produced by copper heap and stockpile leaching. These solutions contain rhenium at very dilute concentrations, typically in the 1 mg/L concentration range. This paper describes laboratory column ion exchange experiments to extract rhenium from these solutions using weakly basic anion exchange resins and actual plant PLS from two operating mines. The dynamic loading and elution behavior of Re on Purolite® A170 and A172 is discussed.

Feb 23, 2014

By D. B. Spears

The sillimanite group includes the aluminosilicate minerals sillimanite, kyanite and and alusite, all of which have the same chemical composition (Al2SiO5). This discussion also includes the closely related mineral, mullite(about Al6Si3O15), which, although rare in nature, is produced artificially for industrial use. All of the minerals in this group have a low coefficient of thermal expansion and high corrosion resistance. This makes them desirable for refractory applications, especially in the steel and foundry industries. Other uses include electrical insulators, abrasives and household ceramic products. The minerals in the sillimanite group decompose with an irreversible expansion at temperatures between 1,300° C and 1,600° C (2,372° F and 2,912° F). Sillimanite and and alusite have relatively small expansion on decomposition (4 percent to 6 percent) and, therefore, can be used as aggregates in refractory products. Kyanite’s expansion on decomposition is large (18 percent). So it is sometimes used to balance shrinkage of other materials such as clays in refractory mixtures. For applications requiring high-temperature volume stability, mullite is more desirable. As an additive, mullite improves resistance to creep and corrosion, and imparts thermal and electrical insulating properties.

Jan 1, 2005

By X. P. Zheng

Barium fluorphlogopites were synthesized in the laboratory in order to investigate the effects of composition and crystal parameters on surface properties and floatability. The negative surface charge of mica is determined by the barium content, the crystal cell volume, the distance between layer structure and the Ba-O bond length. The higher barium content, the larger the cell volume and distance between the layer structure and the longer the Ba-O bond, the more negatively charged the surface is and hence the more easily adsorbed to cationic collectors. When an anionic collector (sodium oleate) is used, barium oleate forms on the mica surface and hence chemical adsorption occurs.

Jan 1, 1993