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By Dietrich F. C. Hudewentz, Alfred H. F. Lücker

For centuries tunnellers have made use of the experience of miners. In West German coalmining tunnellers have returned the impulses in recent years by giving the miners valuable stimuli with the result that a technology has evolved which benefits drill and blast heading, opens the door to TBM heading and has developed special measures for difficult strata conditions in deep coal mines. WHAT DO THESE ROCK HEADINGS LOOK LIKE? The main roadways dealt with in this paper have crosssections of 20 to 40 m2, big enough to allow the massive airflows needed to aircondition the mines. Because of the difficult strata conditions they have to be supported: in shotfired headings mainly with multi-element arches, in TBM headings with rings of 6 to 6.5 m diameter. In West German coalmining the majority of rock headings are blasted. The proportion of rock headings driven by TBM was 11 % in 1980 and 16 % in 1981, a rising trend expected to continue. Drill and blast headings Drill and blast headings are normally equipped with two or three-boom electro-hydraulic jumbos, electro-hydraulic crawler-mounted loaders with 1.2 m3 shovel capacity, a movable working platform and both chain and belt conveyors for dirt clearance to the minecar loading point. Fans and air-condition plant complete the equipment. Spacing between arches is usually 0.8 m. Investment for this type of mechanisation works out at around 1.3 m DM.

Jan 1, 1983

By Byron N. Cooper

The Revenue Act of 1926 provided for five simple categories of natural resources to have the benefit of depletion allowances. In the 1947 Revenue Act, the number was increased to twenty-five, and in the 1951 Revenue Act to fifty-four. Of this number, fourteen were allowed 5 per cent; nine, 10 per cent; twenty-nine, 15 per cent; one, 23 per cent; and one (oil and gas), 27.5 per cent. The 1951 Revenue Act created a host of difficulties, including application of the "end- use criterion" and determination of the commonly accepted meaning of such terms as limestone, dolomite, chemical- and metallurgical-grade limestone, marble, calcium carbonates, and magnesium carbonates. Dolomite, for example, was listed at 10 per cent depletion allowance, but without definition. In the great amount of litigation growing out of the 1951 Revenue Act and its administration, it became essential to understand the derivation and subsequent usage of these common geologic terms. One thing that became clear was that our definitions changed significantly between the time that the 1951 Revenue Act became law and the time that later cases were tried. Some geologists neglected to learn about first usages of such terms as metallurgical limestone, and about meanings that were applicable when the 1951 Revenue Act was written and passed. Legal meanings in this paper are discussed in the light of certain famous cases that have been tried and settled.

Jan 1, 1966

By Dewey W. Geary

Nast Tunnel is the first granitic rock tunnel to be excavated by a machine for the U. S. Bureau of Reclamation. The machine has excavated 7500 ft of the tunnel at this writing. There have been a few good performances; 31 ft in 1, 8 hr shift, and 75 ft in a 24 hr period, but generally, progress has been slower than that accomplished in the area with reasonable comparable conditions using conventional excavation techniques. Button cutters, now employed using compression as the means of fracturing the rock, gives an average cutting rate of 3 ft per hr. Disc cutters manufactured by the machine builders were tried briefly but the snap rings holding the discs to the hub failed. However, disc cutting rates of 6 ft per hr were recorded for short periods of time in a competent coarse grained porphyritic granite. The snuck was also considerably larger and more easily handled than that produced by the button cutters. Hughes Tool Co. is working on a disc type cutter and expects to have them on the cutterhead by mid June. LOCATION, DESCRIPTION AND BID OPENING Nast Tunnel is located 2 miles west of the Continental Divide and 39 miles east of the town of Basalt in Pitkin County, Colorado. The outlet portal is in the Fryingpan River Valley at an elevation of 10,000 ft. The tunnel is a 3 mile long, 10 ft diameter gravity flow water conveyance structure and a part of the west slope water collection for the Bureau of Reclamation, Fryingpan-Arkansas Project. The bids were opened July 9, 1970, with 8 contractors submitting proposals. The contractors were given the opportunity to bid

Jan 1, 1997

By G. Reed Marchant

In 1967 the US Congress passed the "Clean Air Act." This act was amended in 1970. As a result it soon became obvious that American industries were going to have to make significant changes in their methods of operation to be able to comply with quickly developing federal regulations. One of the first regulations developed was on sulfur dioxide. For this reason, the nonferrous smelting industry was immediately affected by these new regulations. This is true because the smelting process produces sulfur dioxide as a natural product of combustion when the sulfur-bearing ore is oxidized to purify the metal. The federal government's approach for setting standards included public hearings at which government, industry, and private citizens were allowed to make comments. For this reason, it was apparent to Kennecott's Metal Mining Div. that it was desirable to make a maximum effort in working with the agency to see that correct input was provided at the hearings to assist the government in setting fair and realistic standards. It was also obvious that more complete monitoring would be required. It soon became apparent that the efforts required input from many levels of the corporation from the chief executive to the plant operators. In order to accomplish both the administrative and the technical needs, an organization was needed that could respond quickly to these needs, obtain information from diverse sources, and bring it to focus in an organized approach to the problem.

Jan 1, 1979

By W. G. Pariseau

Recent advances in rock-mass mechanics and computational technology now allow for the stability analysis of excavations in "wet" mines where mining-induced changes in rock mass deformation and fluid flow are coupled and time dependent. In addition to water pressure and flow in jointed, possibly porous, rock masses, all of the usual dry-mine parameters, including the premining stress state and rock-mass properties, are taken into account. Finite-element analyses of shafts and tunnels, as circular, elliptical, rectangular and arched-rectangular hole shapes excavated in an initially stressed and pressurized rock mass, indicate that the usual guidelines for optimum shape and orientation of single openings apply. Here, optimum means maximizing the minimum wall safety factor or, equivalently, minimizing the peak stress concentration. The results also show that failure originates in elements at the wall and the minimum safety factor at the wall in the wet case is always less than the dry case, regardless of drainage time allowed.

Jan 1, 1997

By Zhang Youdi

A two-step approach has been developed for surface mine short term planning by the authors. The first step is mid term control and planning by the use of Goal Programming. This step gives optimal results for mid term planning (i. e. yearly or quarterly mine plan) as well as a macro control for short term planning (i. e. monthly or weekly plan.) The second step of the approach deals with short term production scheduling by the application of CAD technique and Systems Simulation. An interactive color character graphic design system has been developed with a software package. The menu-driven and module- structured package provides sufficient functions for surface mine short term planning and makes the model very flexible and user-friendly. This model has been applied to a large surface coal mine for short term planning optimization. Satisfactory results have been obtained. It is concluded that for complicated mining conditions this two-step combined approach gives an optimal control of mid term planning, makes the short term planning easier to avoid blindness; it has been proven that the Goal Programming is a powerful tool for solving multi-objective decision-making problems; guided by GP mid term planning, the CAD technique and simulation software package for short term planning are able to be concentrated on their practicality and flexibility.

Jan 1, 1992

By Takashi Sakaguchi, Akira Nakajima

Some attempts were made to recover and remove heavy metal elements, such as uranium, copper and chromium, from aqueous systems by using several phosphate compounds. The phosphorylated derivatives of polysaccharides, chitin phosphate, chitosan phosphate and cellulose phosphate, have high abilities to accumulate heavy metals, such as uranium, copper, manganese, cobalt, cadmium, zinc, nickel and chromium, compared with non-phosphorylated polysaccharides. In order to obtain basic information on the recovery and removal of uranium that may be present in industrial effluents, mine waste water and seawater, the adsorption of uranium by chitin phosphate and chitosan phosphate was investigated in details. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid and was affected by pH of the solution, temperature. granule radius and co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate. Along with these fundamental research, some attempts were made to recover uranium from seawater.

Jan 1, 1993

By Philip U. Santacroce, James H. Meinholz

INTRODUCTION The Milwaukee Metropolitan Sewerage District (MMSD), is a special purpose sub-regional agency that provides collection and treatment services for sanitary wastewater for an area of 420 square miles (1088 km2) in 27 municipalities in the Milwaukee, Wisconsin metropolitan area. During its almost 75 years of existence, it has constructed 464 km of intercepting sewers, the majority in tunnel, and two sub-regional secondary wastewater treatment plants. The present program, the $1.7 billion Milwaukee Water Pollution Abatement Program, was started in 1977 and developed from ongoing internal planning, the Federal Clean Water Act and court judgments. Elements of the Program include improvement and expansion of the two treatment plants; rehabilitation of older in-place sewers; building new interceptors and relief sewers and providing capacity for high volume storage in approximately 32 km of deep, large diameter rock tunnels; reducing combined sewer overflow; and disposal/utilization of the solids that remain after the treatment process. The construction phase of the Program accounts for $1,105,900,000 within 335 separate construction contracts, 211 let to date, and covers a span of 15 years, starting in 1979 and running through 1994. Conveyance System construction cost is estimated to be $650,000,000 or about 60 percent of the total. Through December 1986, in terms of dollars, the total construction program is about 38 percent complete with Conveyance at 34 percent complete.

Jan 1, 1987

By B. K. Mishra, R. K. Rajamani, R. Venugopal, P. Songfack

Millsoft is a computer-simulation software that predicts the performance of large industrial grinding mills. This software surpasses all other tumbling-mill analysis techniques available today because it is based on fundamental laws of physics instead of empirical correlations. Graphical user interface (GUI) forms simplify the specification of the following design and operating parameters: mill diameter, length, speed, charge density and size distribution, lifter material and geometry. All of these parameters are taken into account in the discrete element numerical technique that constitutes the essence of the simulation software. In turn, the software produces a visual animation of grinding-charge motion, predicts mill power and gives the distribution of impact energy. In this paper, a case study of an 8.5-m-(28 ft-) diam SAG mill is used to illustrate the application of Millsoft for mill design and trouble shooting.

Jan 1, 2000

Although mineral commodities used to play and still play a very crucial role in the development of civilization over the centuries, their extraction, transportation, transformation and use are at present sources of great concern in terms of sustainability. Some of the most discussed environmental problems are in fact closely related to the utilization of minerals as materials and fossil fuels. The paper analyses the origins of sustain-ability weakness of mineral supply through Environmental Economics models, which have interpreted the phenomena of pollution and non-renewable resource depletion as a market failure. Conventional market tools have proved to be unable to perform an optimal allocation of those resources that are priceless or have open access. An external intervention is needed in order to reduce the excessive exploitation of environmental and natural resources. Some of the solutions proposed by policymakers and subsequently implemented by governments are briefly considered and the achieved results are discussed. In several cases the public intervention, where the attempt was to restore the sustainability conditions, has failed. Restrictive environmental protection regulations have resulted in severe limitations to the mining activity, without, on the other hand, achieving the expected results in terms of sustainability. Some of these regulations instigate unfair international competition practices among those producers who do care about the environment, but who have high production costs, and those who supply cheap raw material but whose low costs hide heavy environmental impacts. Nowadays, most of the world?s supply of minerals is being produced in developing countries, with severe global environmental impacts. As effective tools for monitoring the problem, sustainable development indicators could be used by policymakers to duly associate the comprehensive environmental impacts for each mining product, depending on its origin and extraction history.

Jan 1, 2003

By Harrison R. Cooper

Composition data is needed as input for executing process control and management of particulate separation for flotation control. While requirements for composition data can be satisfied in many cases by manual sampling and analysis, automatic sampling and assay systems are now viewed as justified for all but the simplest or smallest processes. On-stream X-ray fluorescence analysis (XRFA) has satisfied requirements for the main portion of metalliferous sulfide ore flotation processes as XRFA technology evolved in reliability and sophistication from its beginnings in the late 1950's. In recent years, advanced on-stream analysis technologies have reached levels of development suitable for use in process control to increase efficiencies of important processes in mining and minerals industries such as coal fines flotation and industrial minerals beneficiation (particularly phosphate beneficiation) where XRFA methods have been inapplicable. Recent technical developments pertinent to use of advanced technologies as well as improvements to established on-stream composition analysis methods are discussed.

Jan 1, 1989

By John E. Urosek, Jack E. Tisdale

The Mine Safety and Health Administration (MSHA) has developed a Mine Ventilation Bleeder and Gob Training Course. This three day course is designed to increase the knowledge and understanding of bleeder ventilation systems. It discusses concepts, designs, plan approval, inspection and evaluation of bleeder systems. This paper will introduce some of the material contained in that course, focusing on the inspection, examination, and evaluation of bleeder systems. The regulations addressing the use of bleeder systems are found in Title 30 Code of Federal Regulations (30 CFR) Section 75.334. The examination requirements are found in 30 CFR Section 75.364. Section 75.364 de- scribes specific locations where examinations are to be made and specific information to be gathered at those locations. The required locations and information will be discussed in some detail with examples and illustrations. These weekly examinations for bleeder systems are designed to monitor the parameters of the bleeder system and to evaluate its effectiveness. Over time, conditions can develop in the bleeder system that affect the ventilation and lead to hazards such as methane accumulations. The hazards of methane accumulations need to be understood as such accumulations can contribute to mine explosions. The importance of additional information gathered by the mine examiner that can assist in evaluating the performance of the system will also be discussed.

Jan 1, 1997

By John A. Dearinger, Fred D. Wright, Robert C. Howell

INTRODUCTION The rock mechanics study of the shortwall mining system at Beth-Elkhorn corporation's Hendrix No. 22 Mine is being conducted under contract with the U.S. Bureau of Mines. The objective of the study is to obtain data on surface subsidence over a portion of the mined area, strata subsidence in the mined area, and underground stress changes and displacements in and near natural support elements of the mining system. This study is currently in progress, and only a portion of the results are being presented at this time. The Hendrix No. 22 Mine is located in the moderately rough mountainous terrain of Letcher County in eastern Kentucky. The nearest mine workings to the shortwall area are approximately 1,900 feet distant. The depth of cover over the mined shortwall area varies from 770 feet at Panel 1 to 170 feet at Panel 5 (Figure 1). The strata in the shortwall area is summarized in the three core logs shown in Figure 2. Hole no. 2 is located in approximately the center of the mined shortwall area (Panel 3, Line C, Figure 1). The coal seam in the shortwall area is approximately 4 feet thick and horizontal, although one major ‘roll’ intersects all panels.

Jan 1, 1977

By G. D. Criswell, F. Palkovits, J. M. Johnson

A paste technology investigation was completed for non-pozzolanic fly ash from Units 3 & 4 of PPL Montana’s Colstrip Steam Electric Station. The purpose was to assess the feasibility of converting from dilute slurry deposition of ash products to a system using thickened or paste ash to reduce excess water storage in the impoundment, reduce seepage losses, and increase storage efficiency. The investigation included laboratory and field testing to characterize the rheological, geotechnical and dewatering properties of the ash products, an assessment of potential seepage reductions and an evaluation of potential for increased ash storage capacity by modifying impoundment operating procedures. The studies concluded that the conversion project was feasible, cost effective, and permittable. Critical facilities for the conversion project are currently under construction.

Jan 1, 2004

By John A. Herbst, Per-Olaf Samskog, Jan Bjorkman, Yi Chang Lo

The study described here is concerned with the development of a model for the simulation and optimization of a rod milllpebble mill circuit. A series of laboratory tests was conducted to investigate the effect of critical operating variables. The pebble mill model structure used was a population balance type which accounta for impact breakage and fines production from pebble wear. Model parameterization and verification were performed using data obtained in batch tests and in a plant test campaign. The model developed was found to provide accurate predictions of plant-scale grinding. The prediction errors are less than 21 for the product size and 31 for the mill power required to achieve that product with a mill volume scale-up of 14,000 to 1. These results indicate that accurate extrapolations from laboratory batch data to plant scale performance are poaaible using the population balance model and scale-up prediction procedures for pebble mill circuits as well as ball mills. Preliminary indications are that the new model developed here will provide vital input for pebble mill optimization and process control as well as pebble mill design.

Jan 1, 1990

By Krzysztof Filek, Anindya Sinha, Bernard Nowak

Taking into account the possibilities of condensation of water vapour contained in air during its flow through a series of spot coolers as well as formation of eventual fog, a mathematical model of dynamic temperature, specific humidity and degree of fogging of cooled air in underground mining galleries with direct ventilation is developed. In the gallery, there situated various heat and moisture sources both of distributive and of concentrated types. The model is represented by three partial differential equations of first order. The cases of cooling with full as well as with partial air stream flowing through the gallery are distinguished. Owing to the fact that in practical designing, more important is the knowledge of the variation process of temperature, specific humidity and fogging of cooled mine air at steady state conditions, the model is modified to a set of three nonlinear ordinary differential equations. Based on the presented algorithm, the obtained set of ordinary differential equations is numerically solved which enables to: • specify the distribution of temperature, specific humidity, relative humidity and degree of fogging of cooled air in mining galleries; • determine the cooling powers of air coolers for their known locations; • indicate the locations of the coolers of known cooling powers. Exemplary calculations of temperature and relative humidity of cooled air are presented graphically in a number of diagrams.

Jan 1, 1997

By Gunnar Sparrman, Börje Ahlgren, Sten Rosenström

Starting in 1967 two major hydroelectric power projects have been implemented in East Africa viz. Kafue Gorge in Zambia and Great Ruaha in Tanzania. The two projects have similar characteristics and each consists of an underground power plant, a dam in connection with the power plant and a reservoir dam. The power plants are both designed and constructed according to principles applied in Scandinavia for a long time. Each consists of a headrace of a horizontal unlined rock tunnel with a length of about 10 km, vertical penstock shafts, machinery and transformer halls in large rock caverns and a tailrace of an unlined rock tunnel with a length of about 1 km. The head of the power plant of Kafue Gorge is 400 m, Great Ruaha 175 m, the capacity is 900 MW and 200 MW respectively. Both plants were executed in one stage, but building and erection works were made in two stages. However, the power plants show some interesting differences in design. The power plants are briefly described in the following, special regard being paid to the excavation works. GEOLOGY General The foundation of Eastern and Central Africa is made up of ancient crystalline rocks, consisting of sediments, lavas and intrusives, mostly intensively altered by repeated metamorphism. This repeated metamorphism - dynamic, ther-

Jan 1, 1979

By H. Lind

The consumption rate of Estonian oil shale increases due to the growing rate of exported oil-shale oil. Estonian oil shale active resources in working mines are predicted until the year of 2025 when the consumption rate stays at the level of 12 tons per year. If the consumption rate stays at that level, new mines should be opened after 20 years, if the rate increases new mines should be opened even earlier. The predicted active resources in Estonian oil shale deposits are calculated for 60 years, based on the parameters of the power station technicoeconomics. As a result, there is a need to open new mines. One of the potential areas for surface mine is the Tammiku-Kose prospect area (Rheinbaun Engineering, 1996).

Jan 1, 2006

By Gordon R. Luster

Mineral-processing plants commonly rely on homogenization and proportioning facilities to reduce the variability of incoming raw materials and to blend different materials together to satisfy quality specifications. To determine appropriate designs for these facilities, plant designers need information about the variability of the mined materials, measured as the materials enter the plant. But if the materials to be mined in the future differ greatly from those used in the past, only information extracted from exploratory drilling of the materials in the around may be available. Fortunately, useful information for plant design may still be obtained by combining simulated mineral deposits with simulations of likely mining procedures. The output of a mining simulation is a time series of simulated raw-material characteristics that should mimic the behavior of the real materials to be delivered to the plant in the future. This paper shows how conditional simulations of coregionalized ore grades can furnish information useful in the design of homogenization and proportioning systems.

Jan 1, 1986

By Maurice Rey

The copper segregation process is designed to concentrate oxidized copper ores or mixed sulfide-oxide copper ores which are refractory to normal and cheaper mineral dressing or leaching processes. Such ores contain copper silicates or highly disseminated copper minerals in a gangue not entirely free from limestone or dolomite. Concentra¬tion by flotation is, under these circumstances, not possible and the acid-consuming constituents do not permit acid leaching. A high temperature treatment at 700-800°C, in the presence of a small amount of sodium chloride and of finely divided carbon, concentrates the copper into easily floated metal by a kind of reducing chloridizing roast. The sulfides, if present, are either oxidized in the heating stage and react like oxides or float with the metallic copper in the flotation step. The ores which have the aforementioned characteristics and which are high grade enough to pay for the treatment are scarce, so that the process has only a limited application. Theory of Copper Segregation Sodium chloride, reacting with water vapor and the acid gangue constituents, produces hydrogen chloride which reacts with the copper minerals. The copper is volatilized as cuprous chloride and immedi¬ately reduced on the coal particles by hydrogen emanating from the volatile matter of the coal and from the water-gas reaction. Hydrogen chloride is

Jan 1, 1985