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By H. EI-shall

In this paper, the results of a fundamental study involving zeta potential and turbidity determinations of solid suspensions are discussed. Illustrations of how these results are utilized to design field applications of solid grade polymers to clarify mine drainage water are presented. Other applications in different industries are also reported. The operational and economical advantages are examined.

Jan 1, 1994

By Alexandru Corneliu Stematiu, Catalin Popescu, Radu Sarghiuta

"The tunnel sector is excavated into a rock mass heavily affected by tectonics, defined as a regional fault. The rock around the tunnel support undertakes the non – elastic deformation and gradually detaches from the rest of the non affected rock mass, moving inside of the excavated area and tending to fill up the whole space. The initial solution of using stiff support consisting in double steel ribs I12 with circular shape in the upper part and straight vertical pillars in the lower part has proved to be inadequate. Based on the calculations of the subsidence phenomena and a mathematical model, the proposed alternative support was provided by special circular steel ribs – SG-23 –that allows a limited rib deformation (by relative slip between the arch segments) in order to mobilize the contact between the rock contour and the inner face of the rib - not only for the deformed rib but also for the neighboring ribs. 1. INTRODUCTION Hydropower development of Jiu river in Romania, in the narrow gorge sector includes two diversion HPP and a small hydro plant that provides the minimum required flow downstream: CHE Dumitra , CHE Bumbesti and MHC Livezeni (Table 1. Hydropower parameters).The Livezeni intake reservoir is provided by a gated dam located 1250 m downstream of merging point between Jiul de Vest river and Jiul de Est river. The dam is equipped with three radial gates with flap gates with a span of 12 m each and the height of (6 + 3) m. The longitudinal profile of Dumitra head and the location of the gallery zone that is the subject of the paper are presented in Figure 2. Longitudinal Profile – Dumitra Head."

Jan 1, 2016

By H. J. Bogert

Shallow, gently dipping quartz veins at the Mineral Hill Mine are mined in room and pillar stopes. Ore zones are severely folded and fractured, thus actual pillar strength and physical properties of the rock mass deviate significantly from conventional laboratory tests and pillar theory. Laboratory specimens large enough to include pre-existing fractures proved to be representative of actual pillar strength. Further adjustment for specific pillars was based on RQD. Deformation and stress were measured in several pillars during pillar recovery. Stress data and finite element modeling were used to estimate absolute pillar stress at failure. The stress/strain relation provided an excellent indicator of pillar behavior. Good agreement between lab data and underground data was found.

Jan 1, 1995

By Simon D. Strauss

This paper discusses the ways in which the metals industries dealt with surplus capacity in the past, primarily the twenty years, 1950 - 1970. During this period, the bulk of metals production in the market-economy countries was controlled by private sector companies. Since then, public sector companies have played an increasingly important role in the metals industries of the market-economy countries. Of course, the change was not overnight. It occurred gradually over a period of many years. Indeed, by 1965, several developing nations had adopted policies of government control of metal operations previously in private hands. The metals industries are so many, so large and so diverse that the constraints of time make it impossible to deal with all segments. To illustrate the problems of surplus capacity in the metals industries during the period, this paper focusses primarily on three metals. One experienced rapid market expansion between 1950 and 1970; one had a growth more or less in line with the expansion of the world economy; and one lagged well behind the pace of industrial expansion. No one will be surprised if aluminum is identified as the metal with rapid growth; copper is identified as the metal that kept pace with the world economy; and tin is identified as the laggard. Individual computations of the rate of growth for these metals show some variations, but most estimates place the increase in aluminum consumption in the market economy countries between 1950 and 1970 at a compound annual rate of about 8%. The corresponding figure for copper is a compound rate of 4%. Tin consumption showed no growth. A widely accepted point of view is that sharply rising demand will force the price of a commodity to increase substantially in order to attract a necessary expansion of supply. The corollary to this is that stagnant demand will hold prices down, as there is no need to stimulate new supply and it may be necessary to force marginal producers out of the market. The experience with aluminum, copper and tin in the years 1950-1970 does not support this theory. In 1950, the average prices in the United States market as reported by the American Bureau of Metal Statistics were 17.74 a pound for aluminum, 21.24 a pound for copper, and 95.54 a pound for tin. The corresponding figures in 1970 were 28.74 a pound for aluminum, 57.74 a pound for copper and 174.24 a pound for tin. Aluminum, with the greatest market growth, rose by 60%, whereas tin rose 82% and copper by 172%. Clearly, other factors were a more important influence on price than was the trend of demand To revert now to the capacity issue, during the period under review aluminum demand was rising so sharply that that industry had no sustained problem with surplus capacity. Instead, if anything, capacity may at times have been a constraint on demand. The industry succeeded in attaining explosive market growth through imaginative research and promotion programs. Some of this growth was the result of substitution of aluminum for other commodities – steel, copper, wood and glass as examples. But much of the growth was the consequence of developing entirely new products through technological innovation. Prior to World War 11, the number of aluminum producers was extremely limited. Alcoa and Alcan in North American and Pechiney and Alusuisse in Europe were the dominant firms. The developing countries had virtually no production and in Japan and Germany production was only a small fraction of the North American output. During the War years the United States had financed the construction of many new facilities. After the war these plants were sold by the government to Reynolds and Kaiser in order to foster more competition in the market. Subsequently many other concerns became aluminum producers, both in the United States and elsewhere and competition for markets intensified.

Jan 1, 1989

By John W. Welty

Volcanic activity occurred during six periods of Arizona's geologic history. Precambrian volcanism occurred in two pulses at 1.8-1.6 billion years (b.y.) ago and at 1.2-1.1 b.y. ago. Volcanism occurred again in mid-Jurassic and Laramide (Late Cretaceousearly Tertiary) time. Volcanic rocks from these times are not used commercially in any significant quantity. Middle and late Cenozoic magmatic activity covered large areas of Arizona with voluminous volcanic rocks. During the mid-Tertiary magmatic pulse, explosive silicic magmatism, with eruption of areally extensive ash-flow tufts, covered large areas in the Basin and Range Province, while the Colorado Plateau remained largely unaffected. Basalt eruption also occurred during and immediately after silicic volcanism, leading to compositionally diverse suites of volcanic rocks. Late Cenozoic volcanism occurred throughout Arizona and was dominated by wide-spread eruption of basalt flows with local cinder-cone clusters and siliceous volcanic deposits. Perlite deposits near Picketpost Mountain in northeastern Pinal County account for the bulk of the industrial uses of mid-Cenozoic volcanic rocks. Other perlites of presumed middle Tertiary age are present in central, southeastern, and western Arizona, but to date remain unexploited. Arizona Fire Agate is a valuable gem material and is associated with volcanic rocks of middle Tertiary age. Basaltic rock of this age also is utilized in the manufacture of rock wool for insulation. Late Cenozoic volcanism produced most of the industrial-quality volcanic rocks. Basalt, cinder cones, and materials of rhyolitic composition are commercially exploited by municipal and Federal agencies and private industry for aggregates, road conditioners and maintenance materials, asphaltic concretes, cinder block construction, pozzolans, and landscaping. These deposits are generally confined to the Flagstaff and Springerville areas. A famous peridot gem locality is associated with late Tertiary basalts at Peridot Mesa on the San Carlos Indian Reservation. Important products derived from altered volcanic materials of late Cenozoic age include clay and zeolite. Arizona's volcanic-rock sequences are still incompletely known, particularly in central and western Arizona. The potential for recognition and exploitation of important new deposits of useful volcanic materials is high.

Jan 1, 1987

By James D. Hervol, Josepph W. III Leonard, Barbara J. Arnold

INTRODUCTION Dry concentration or pneumatic cleaning uses air currents as the separating medium. Pneumatic cleaning in the United States today is limited to three or four operations. In fact, the quantity of bituminous coal cleaned pneumatically has declined from its peak in 1965 of about 25.4 million tons (23.1 Mt) to its current level (1988) of less than 4 million tons (3.64 Mt) annually, as shown in Fig. 7-9 1. In 1940, pneumatic methods accounted for 15% of the bituminous coal and lignite cleaned in the United States as given in Table 7-32. Currently, pneumatic methods account for less than 2%. The largest air plant was built in Pennsylvania about 1968 with 14 units processing 1400 tph (1280 t/h) of 3/, in. X 0 (19 mm X 0) raw feed and two additional units retreating middlings. This same plant is one of only three or four plants still operating air-cleaning devices in the US. A wet plant was added in 1985 to increase the efficiency of cleaning the fines. The air plant is still used as a scalping operation for the coarse material. Five additional operations are either no longer in production or have discontinued the use of air tables within the last year. Wet cleaning methods are now being employed at the facilities that have discontinued air table operation. he advantage of dry cleaning techniques is the low moisture content of the clean coal product. However, to decrease respirable dust, mining operations must use water sprays on modem mining equipment. This water adds to the moisture content of the run-of-mine coal and decreases the effectiveness of dry cleaning processes that rely on low surface moistures in the feed to allow for good separations. Wet cleaning methods are preferred, especially since they also allow for much sharper separations. The advantage of dry cleaning techniques is the low moisture content of the clean coal product. However, to decrease respirable dust, mining operations must use water sprays on modem mining equipment. This water adds to the moisture content of the run-of-mine coal and decreases the effectiveness of dry cleaning processes that rely on low surface moistures in the feed to allow for good separations. Wet cleaning methods are preferred, especially since they also allow for much sharper separations. Despite dry concentration's drawbacks, research has continued into dry concentrating methods, including both electrostatic and magnetic separation techniques. The real application for future dry cleaning processes is probably at the power plant between the pulverizer and the boiler feed where particles are already dry and ground to fine sizes (- 200 mesh [ -0.075 mm]), increasing the effectiveness of the separation and also, possibly, increasing the liberation of clean coal from finely disseminated impurities. From a utility's viewpoint, pneumatic cleaning offers the best delivered Btu cost, based on the premise that a percent of moisture is just as detrimental as a percent of ash. Additionally, several other advantages are inherent in dry concentration techniques. The main advantage is that dry concentration re-

Jan 1, 1991

By J. M. Mutmansky

Introduction Since the Hardy Cross numerical algorithm was applied to the solution of mine ventilation networks, numerous developments have taken place in ventilation network analysis procedures. The Newton-Raphson method, the linear theory method and the second-order approximation method are three of the additional approaches that have been applied. The efficiency of a ventilation network analysis procedure depends not only on the method of solving the system of equations derived from ventilation networks but also on the method of deriving the equations through selection of the meshes. This paper investigates the impacts of three mesh selection methods on the efficiencies of four ventilation network procedures. The minimum-resistance spanning tree method is the most popular procedure for selecting meshes. The shortest-path method was suggested by Epp and Fowler (1970) for improvement of the Newton-Raphson method. The minimum-resistance-path method is suggested here as the third method of selecting meshes. The effects of these three methods on the Hardy Cross method, the Newton-Raphson method, the linear theory method and the second-order approximation method are analyzed in this paper. These network analysis methods have been summarized in the paper by Kim and Mutmansky (1991). Mesh selection methods A procedure for mine ventilation network solution based on mesh equations typically consists of two steps: • the mesh selection step and • the network solution step. The mesh selection step establishes a set of independent equations to solve the network. The resulting equations are nonlinear. One method of solving nonlinear equations is to linearize the equations and iteratively solve these linear equations. The four analysis methods previously discussed in this paper use this approach. The linear equations required for solution can be written in matrix form as: P•dQ = dF (1) where P is the pseudo-resistance matrix, Q is the quantity matrix, and F is the Jacobian matrix (Kim and Mutmansky, 1991). The efficiency of the solution method depends on the characteristics of the P matrix, which in turn depend on the method of selecting meshes. To understand the impacts of the mesh selection methods on the efficiency of the ventilation network analysis procedures, the characteristics of the P matrix must be understood first. The diagonal elements of the P matrix, m in number, are the sums of the pseudo-resistances of the branches contained in the m meshes necessary for solution. The off-diagonal elements are the sums of the pseudo-resistances of the branches shared by two meshes. For example, P12 (first row, second column element of the P matrix) is the sum of the pseudo-resistances of the branches common to mesh 1 and mesh 2. When solving the system of equations expressed in Eq. (1), three of the iterative procedures (the Newton-Raphson, the linear theory and the second-order approximation methods) use the direct factorization method (Burden and Faires, 1985) on the P matrix. When the direct factorization method is used, the computational efficiency is enhanced by larger diagonal elements and a sparser P matrix. Generally, the sparsity of the P matrix is more important than the size of the diagonal elements. There is no known mathematical method of predicting the efficiency of these procedures, but heuristic methods can be used to study the efficiency. The Hardy Cross algorithm applies the Gauss-Seidel method of splitting the P matrix and applies the Newton-Raphson procedure. The efficiency of the Hardy Cross method depends on the spectral radius of the matrix[[D-L]-1U], where D is the diagonal, L is the lower triangle and U is the upper triangle of the P matrix for the Newton-Raphson method (Ortega, 1972). The smaller the value of the spectral radius, the faster the convergence. As with the other three methods, larger diagonal elements and a sparser matrix aid in faster convergence. With the Hardy Cross method, however, the size of the diagonal elements is more important than the sparsity of the matrix. Remembering that each of the diagonal elements of the P matrix is the sum of the pseudo-resistances of the branches in a mesh and that each off-diagonal element is the sum of the pseudo-resistances of the branches shared by two different meshes, the following strategies can be used: • Avoid having branches with larger resistance values shared by multiple meshes. This increases the size of the diagonal elements and reduces the chance of off-diagonal elements being large.

Jan 1, 1993

By Kang-Hyun Lee, In-Mo Lee, Byung-Kyu Kim, Parkm Jinho, Seoung-Won Lee

"In this study, the TBM Resistivity Prediction (TRP) system is developed for predicting the location, thickness, permittivity ratio and electrical conductivity of anomalous zones ahead of tunnel face using the measured resistivity of the ground. The applicability of the developed system was verified by performing field tests at a construction site in which an EPB-shield TBM is used for tunnelling work. In the first field test, it was found that the rock around the tunnel face had the same resistivity and permittivity with the rock ahead of the tunnel face indicating no anomaly ahead of the tunnel face. In the second test, a stronger zone 5-m thick was predicted ahead of the tunnel face based on lower permittivity than that of the rock around the tunnel face. The ground condition assessed by the newly developed TRP system matched well with that either predicted from geophysical exploration or directly obtained from drilling boreholes or from daily observed muck conditions. INTRODUCTION During tunneling work, the emergence of unpredicted zones of relatively weaker or stronger ground can lead to delays in construction work or an increase of construction cost. Predicting anomalous zones ahead of tunnel face in advance can thus prevent time and economic loss. For these reasons, various methods to predict the ground condition ahead of the tunnel face have been studied and developed. Prediction methods using various kinds of equipment include tunnel seismic prediction, ground penetrating radar, electromagnetic surveys based on electronic antennas, and electrical resistivity surveys conducted by analyzing electric currents in the ground ahead of the tunnel face (Ryu et al. 2008). However, most of the prediction methods are only applicable to conventional tunneling job sites, which feature free access to the tunnel face. In mechanized tunneling projects, accessibility to the tunnel face is very limited because the tunnel face is occupied by the TBM."

Jan 1, 2016

By R. Musu, J. A. E. Bell

P.T. Inco has constructed a smelter to produce 45 000 tonnes (49 500 tons) of nickel per year as a nickel matte from the lateritic ores of Sulawesi, Indonesia. The facilities include mines, five screening stations, two dryers, three novel reduction kilns, three electric furnaces, three top blown rotary converters, and associated infrastructure of port, towns and a hydroelectric generating station. The screening stations and converters are unique in the industry. The problems encountered in the construction and operation of this complex facility in remote Indonesia are described.

Jan 1, 1979

By J. J. Whittaker

Zaldivar is an open pit copper mine operation located in the Atacama Desert, in northern Chile. The plant produces Cu cathodes using 4 solvent extraction trains. The plant was started up May 1995. Since 1996 the plant has been using on-stream analyzers based on X-ray fluorescence and titration for process monitoring and control. Elemental analyzer alone is not able to provide the critical information for plant operation, it has to be complemented by on-stream titrators integrated to one sampling system. The analyzers are located in a prefabricated shelter. The analyzer system project, operation and performance issues are the main topic of this paper.

Jan 1, 1999

By B. C. Litzinger

Minerações Brasileiras Reunidas S.A. - MBR is a brazilian iron ore mining company geared for the export market. It is controlled by Companhia Auxiliar de Empresas de Minerações - CAEMI through its subsidiary Empreendimentos Brasi leiros de Minerações - EBM which holds 51% in MBR and is formed by CAEMI, the six major japanese steelmills and five japanese trading companies, Universe Tankships, Inc., and Indústria e Comércio de Minérios S.A. - ICOMI. The remaining 49% of MBR's capital are held by St. John del Rey Mining Company, a subsidiary of The Hanna Mining Company. MBR iron ore reserves exceed 1.5 billion tons of high grade ore distributed in 36 deposits located in the so-called IRON QUADRANGLE in the State of Minas Gerais. The Aguas Claras Mine is the largest presently known and highest grade deposit owned by MBR. Other mines such as Pico, Mutuca and Jangada are in operation at a combined rate of production of about 2 to 2. 5 million tons per year. The project consists of mine, railroad and marine terminal (slide). The Aguas Claras deposit, which is located about six kilometers southeast of Belo Horizonte the Capital of Minas Gerais, was selected for initial development. The Sistema Regional Centro of the Rede Ferroviária Federal, through its 6th Division known as the "Central " is responsible for the transportation of MBR ore, and provided the necessary railway construction to connect Mine and Terminal. The Terminal is located on Guaiba Island near the entrance to Sepetiba Bay, at about 120 kilometers west of Rio de Janeiro.

Jan 1, 1974

By L. Mao

A first-order flotation rate equation was derived by incorporating both hydrodynamic and surface forces involved in bubble-particle interactions. The hydrodynamic forces were calculated using an appropriate stream function, while the surface forces calculated using the extended DL VO theory. The equation was used to predict flotation results as functions of several important parameters such as contact angle, Zeta potentials of air bubbles and particles, and bubble size. The predictions are consistent with experience, and can be explained in view of the various sub-processes considered in the model.

Jan 1, 1997

By C. L. Lin

Linear grade distribution measurements determined from polished sections of randomly oriented particles can be used to estimate the extent of liberation for multiphase particles of specified size. Two techniques, optical image analysis and microprobe analysis, have been used to establish linear grade distributions. Both techniques were evaluated and compared using variable grade samples of products from a copper porphyry flotation circuit. The statistical significance of the linear grade distribution data obtained by optical image analysis was assessed. The average chalcopyrite content of these samples, as determined by chemical assay was used to estimate the variance of the experimental procedure. For a given accuracy, the number of particles required to obtain an unbiased representation of the sample was determined.

Jan 1, 1985

By R. D. Irvine

Enhanced concern for protection of the environment and attendant actions by environmental regulatory authorities in support of this concern are influencing to varying degrees the demand and supply of a range of industrial minerals in a number of jurisdictions. These influences take a variety of forms. In this paper, the author seeks to delineate certain broad trends which are occurring relative to industrial minerals and the environment and then, through a series of examples, outline opportunities, developments, and impacts respecting a number of industrial minerals produced and consumed in Canada and the United States.

Jan 1, 1995

By Oluwafemi Salami

Conducting full-scale fire experiments in underground mines is difficult and expensive. Sometimes, it is impossible to carry out fire tests in mines due to the danger they pose to mine workers and the underground facilities. However, understanding the potential occurrence of fires in a mine and their dynamics is critical to developing an appropriate emergency evacuation plan, fire suppression, and firefighting techniques. In this study, a numerical fire model using computational fluid dynamics (CFD) with fire dynamics simulator (FDS) 6.7.6 was developed to examine the influence of tunnel bifurcation on maximum temperature beneath a tunnel ceiling. The model was validated using full-scale experimental data. The maximum ceiling gas temperature predicted using FDS and measured maximum smoke temperature during the experiment shows good agreement. The study shows that bifurcation could lower the maximum ceiling temperature of fire-induced smoke in a subsurface environment. The findings from this study apply to the broader field of ventilation and fire life safety in tunnels and other underground environments.

Jun 23, 2024

By J. Peterson, R. Michael, D. Yantek, E. Ferro

Among underground coal miners, hearing loss remains one of the most common occupational illnesses. To address this problem, the U.S. National Institute for Occupational Safety and Health Office of Mine Safety and Health Research (NIOSH OMSHR) conducts research to reduce the noise emission of underground coal mining equipment, an example of which is the roof bolting machine. Field studies show that, on average, drilling noise is the loudest noise that roof bolting machine operators would be exposed to, and it contributes significantly to the operators’ noise exposure. OMSHR has determined that the drill steel and chuck radiate a significant amount of noise during drilling. OMSHR and the Corry Rubber Corporation (CRC) have developed a bit isolator that breaks the steel-to-steel link between the drill bit and drill steel and a chuck isolator that breaks the mechanical connection between the drill steel and the chuck. This effectively reduces the noise radiated by the drill steel and chuck and in turn reduces the noise exposure of roof bolter operators. This paper documents the evolution of the bit isolator and chuck isolator. Laboratory testing confirms that production bit and chuck isolators reduce the A-weighted sound level generated during drilling by 3.7 to 6.6 dB.

Jan 1, 2011

By E. Allen Wendt

It is both a great pleasure and something of a challenge for me to have this opportunity to address a gathering encompassing such a wealth of expertise in the minerals field, It is particularly challenging because I have been asked to turn your attention from the relatively glamorous subjects of gold and money to the more mundane questions of our International commodity policy and the place of buffer stocks in that policy. However, these questions may be of more immediate importance for our economic interests at home and Abroad. I can testify that the problems affecting international commodity markets and the possibility of international action To resolve those problems are matters of real concern to Washington as well as to your industries,

Jan 1, 1978

By Raymond E. Krauss

The McLaughlin Mine is based on a world class epithermal gold deposit located in the coastal thrust fault of northern California, about 1 12 air km (70 air miles) north of San Francisco. Owned and operated by Homestake Mining Co., the McLaughlin deposit contains about 18 Mt (20 million st) of gold ore at an average grade of 5.2 g/t (0.152 oz per st), or about 93 t (3 million oz). The area was identified as a gold target by Homestake in early 1978. Drilling confirmed it to be a commercial deposit by 1980. The mine was then planned, engineered, built and brought into production by March of 1985. The deposit was historically a part of the Knoxville District. It was mined for cinnabar, which was used to produce mercury for use in recovering gold and silver in the Mother Lode and Comstock districts. At that time, the mine was called the Manhatten and later the One Shot Mine. It was worked for more than 100 years, producing about 76,000 flasks of mercury without any awareness of the presence of economic concentrations of gold. By 1978, the site was largely disturbed and entirely unreclaimed.

Jan 1, 1990

By Robert W. Roscoe

For over a century, St. Joe Minerals Corporation in Southeast Missouri has been sinking shafts for their lead mining operations. Upon discovery of the Viburnum Trend, or "New Lead Belt", St. Joe brought its experience and expertise in shaft sinking to the area. Eleven shafts were then sunk in an 18 year period, ending in 1972. In 1981, St. Joe began sinking a new shaft in the Trend with hand-picked employees from the four operating lead mines and service facilities. The paper describes the general history of St. Joe shaft sinking methods and equipment, focusing on the current development of the Viburnum No. 35 Shaft.

Jan 1, 1983

By J. E. Gray

Before specifications are discussed it may be well to define the term "Mineral Aggregates." Professor K. B. Woods (1) defined "Mineral Aggregate--An aggregation of sand, gravel, crushed stone, slag, or other material of mineral composition used in combination with a binding medium to form bituminous and portland cement concrete, macadam, mastic, mortar, plaster, etc., or alone as in railroad ballast, filter beds, and various manufacturing processes, such as fluxing, etc. " This definition is too all inclusive for the purposes of this paper; therefore, this discussion will be confined to specifications for natural aggregates which means sand and gravel and crushed stone, and limited primarily to coarse aggregate which is aggregate larger than one-quarter inch in size. To the uninitiated, this may seem to be a very limited subject on an unimportant material. However, aggregates are essential in all types of construction. The tonnage and value of these two aggregates produced in the United States during 1959 as reported by the Bureau of Mines were as follows: Sand and Gravel 729,895,000 tons valued at $728,527,000 Crushed stone 581,721,000 tons valued at $824,411,000

Jan 1, 1961