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By Luigi P. Gonano, John C. Sharp

The Drakensberg Pumped Storage Scheme in South Africa with an operating head of 500m is located in sedimentary rocks containing relatively weak argillaceous strata. The paper describes design and construction aspects of the high pressure concrete-lined tunnels, and the associated investigation techniques and construction controls.

Jan 1, 1983

By M. S. Vernon, J. J. Kellar, W. M. Cross, R. M. Winter, F. J. Johnson, A. G. Pommer

Three substrates (MgO crystal, CaF2 crystal and Mg plate) were used to construct thin layers of Mg(OH)2. Various routes were used to modify these substrates, including surface hydration and sol-gel coating. In each case, it was found (by using Fourier transform infrared spectroscopy) that thin layers of Mg(OH)2 could be produced. In the case of hydrated layers, the surface morphology of the Mg(OH)2 resembles the bulk platelet shape of precipitated Mg(OH)2.

Jan 1, 2000

By A. C. T. Bigg, A. F. Colombo, A. R. MacPherson

The step-by-step study of the Stronsay ores follows the testwork through the initial determination of Bond Rod and Ball mill work indices, the MacPherson Autogenous work indices and the production of a preliminary flowsheet. These results are then used to design a pilot plant program to test the effectiveness of fully autogenous primary and secondary grinding and to determine the feasibility of controlling feed rate by the use of variable speed mill drive and/or varying the mill load. A final flowsheet is recommended with mill sizes and power requirements.

Jan 1, 1992

By J. Shibata

Separation of rare earth, especially Nd and Sm, was investigated by batch and column methods with a solvent impregnated resin. The solvent impregnated resin was prepared by impregnation of organo- phosphorous extractant whose trade name was PC-88A into a macro porous resin. The adsorption behavior of rare earth with a solvent impregnated resin in a batch method is the same as that with solvent extraction. In a column method to separate Nd and Sm, the effective separation in both adsorption and elution processes can be attained by setting suitable conditions, such as bed height, flow rate and concentration of eluent. Neodymium which is a lighter rare earth is separated from Sm an adsorption step, while Sm in which is a heavier rare earth is recovered in an elution step. From the integration of breakthrough and elution curves, yield of Nd and Sm is calculated in the condition of 100% purity. It was found from the results of life test of the resin that the solvent impregnated resin can be repeatedly utilized at least 20 times.

Jan 1, 1995

By L. J. Prosser, A. T. Iannacchione

From 1991 through 1995, 44 miners out of a total workforce of less than 2,000 were fatally injured in the stone industry. Of these, 12 occurred at underground mining operations with nine deaths resulting from roof or rib falls. A safer environment can be achieved by evaluating the nature of the hazardous ground and by developing more efficient and effective ground-control strategies. Roof and rib conditions were observed and assessed in 33 underground stone mines in Illinois, Indiana, Kentucky, Maryland, Missouri, Pennsylvania and West Virginia (Fig. 1). Hazard assessment indicated that the ground failures that occurred under moderate to substantial overburden, i.e., >30 m (100 ft), were caused by stress concentrations and geologic structures. Ground failures near the surface are caused by solution (water) processes. Selection of the mining horizon and mine-layout decisions

Jan 1, 1999

By Robert A. Jankowski, Natesa I. Jayaraman, Jay F. Colinet

The U.S. Bureau of Mines evaluated the dust control effectiveness of two-phase flow systems in a full-scale model mine using a mockup of a Joy 14CM continuous mining machine. In a two-phase flow system, air and water flow simultaneously through the nozzle. Air pressure varies from 10 to 60 psi, and water at 30 to 50 psi. Coal dust was introduced at the face, and dust concentrations were monitored at the operator locations and in the return. When compared with a conventional spray system, a symmetrical two-phase flow system reduced dust levels during the box cut by 43 pct at the operator location, and 30 pct in the face return. Dust levels, however, increased at the off-operator position during the slab cut. A directional two-phase flow system reduced dust levels at both operator locations by more than 90 pct in the box cut mode. While the use of two-phase flow systems will reduce respirable dust levels and water usage, it requires an air supply to the miner. Moreover, the ability of the two-phase flow system to redirect the dust cloud makes nozzle orientation a critical factor.

Jan 1, 1991

By David J. Kruse

Accurate field measurements are essential when validating a conveyor design. They are fundamental in determining a conveyor's behavior, its long-term maintenance requirements, and the life expectancy/ condition of the installed equipment. Field measurements are also invaluable in forensic engineering, particularly when vital equipment has failed This paper will discuss a wide variety of data acquisition equipment, field measurement techniques and accuracies achieved State-of-the-art, custom designed monitoring equipment, as well as, ''08-the-shely instruments and sensors, will be discussed.

Jan 1, 2004

By D. L. McCain

In considering slurry transportation for Consolidation Coal Company's Loveridge Mine in Northern West Virginia, many things were taken into account. The advantages of slurry transportation in comparison to shuttle car, belt and rail transport have been given in previous publications." These include increased safety and the potential for increased productivity. In addition to these considerations, the slurry transport system installed in an existing mine provides an alternate or additional transportation mode to the one already existing. In the Loveridge Mine, this is rail haulage. Since the rail system is a single track system and the distances involved are several kilometers, it is not always possible to provide for haulage of loaded cars, return of empties, supplies and maintenance in an efficient manner. Slurry transport of the coal from the production faces to the preparation plant allows the rail system to fulfill the remaining transportation needs in an efficient manner. Consol initiated development work in slurry transportation in the early fifties leading to the construction and operation of the 174-km (108-mile) Cadiz-to-Cleveland pipeline which carried 1,200,000 metric t/y (1,300,000 t/y) from 1957 to 1963. Development work on coarse coal slurry transportation for underground mines started in 1970 with feasibility tests on coarse coal at Conoco's Ponca City, Oklahoma, slurry test facility. A series of tests were conducted in several locations as development work proceeded on the various subsystems, mechanical equipment and controls required to produce a working system to follow a continuous miner in a room-and-pillar type mine, then to combine the coal production from several mine faces for mainline transportation to the preparation plant. The face system, including the crusher-pump vehicle, hose hauler vehicle, slurry booster pump units, return water unit and 900 to 1,200 m (3,000 to 4,000 feet) of pipeline was brought together for the first time and tested as a system at Consol's Robinson Run Mine in northern West Virginia in 1975. A pipeline wear test at the Loveridge Mine where 300,000 tonnes (330,000 tons) of minus 127-mm (5-inch) run-of-mine coal were pumped from the raw coal bin into the preparation plant and a large scale test in Ponca City on a multiple feed sump where several slurry flows could be combined to provide surge capacity and a constant reclaim rate for mainline transportation completed the preliminary testing for a complete system. A decision was made to commit the system to a mine, and the south half of the Loveridge Mine was chosen. This site required the transporting of coal from one longwall and two continuous miner development faces. To prevent startup and unexpected problems in the slurry system from shutting down production of coal from the longwall face, the rail car loading point from the main section belt was chosen as the feed point for the slurry system and the design would allow for rapidly switching from one transport mode to the other. Scheduling of required development entry work and the developmental nature of the system led to a decision to install only one continuous miner face slurry transport system rather than two for this first system. The type of continuous miner in use at the mine for the foreseeable future was the Joy 2BT6 twin boring machine. This machine cuts a stable, arch-shaped entry and was therefore allowed to mine about 26 m (85 feet) of entry before roof bolting was re¬quired. Since peak production from this type of machine was not high, a smaller transport system could be used with it.

Jan 1, 1981

By Robert W. Bruhn

The prediction of damage to a structure that is to be undermined is generally a two step process. First, the expected ground movements (the displacements, slopes, curvatures, and strains) are estimated using available (often empirical) predictive methods or survey data from a site of comparable geology, topography, and mining geometry. Second, the prospects for damage to the structure are assessed by comparing the expected ground movements to tolerable limits, some of which appear in the technical literature as damage criteria. The inverse problem of relating observed building damage to causative ground movements involves essentially the same elements. In either case, the usefulness of published damage criteria to subsidence problems may be limited in all but the most elementary cases. This paper considers several cases where structural behavior and site specific details had to be taken into account in assessing the relationship between damage and ground movements.

Jan 1, 1986

By Donald Towse

The Permanente plant of Kaiser Cement & Gypsum Corporation is located at a unique thick deposit of Calera Limestone (Figure 1) on the southwest side of San Francisco Bay. Limestone is rare in the eugeosynclinal Franciscan assemblage, constituting less than 0.1 percent of the total volume. On the northwest part of the San Francisco peninsula Calera Limestone is present as isolated masses from the type sect ion near Rockaway Beach southeastward for ten miles, where the belt is truncated by the San Andreas fault. The large Permanente deposit is sixteen miles south of the truncated belt, on the northeast side of the San Andreas fault. Scattered small exposures are known for about twenty miles southeasterly from Permanente. (1,2) Most deposits of Calera are thin; the type section is about two hundred feet thick. At Permanente, however, the normal limestone section contains at least four hundred feet of limestone; and, due to folding and extensive faulting, the total vertical thickness of the limestone section is over 1400 feet. The unusual thickness of limestone is due to low angle thrust faulting. This fortuitous structure formed a deposit of limestone that supplies an 8,500,000 barrel cement plant in a major metropolitan market.

Jan 1, 1966

By R. L. Grayson

Focusing on relationships between severity measure versus productivity and other factors, this paper presents a comprehensive study of injuries for U.S. underground coal mines in 1996 by mine size. Based on analyses of data, generally the larger the mine, the more productive it is (in tons per employee-hour), but the more severe is its injury experience (r = 0.65). Within very large, large, and medium mine sizes, however, the more productive the mine, the less severe is its injury experience (r =-0.43, -0.36, and -0.26, respectively). For small and very small mines, a more deeply nested analysis is required to understand relationships. Other interesting relationships and comparisons are presented.

Jan 1, 2000

By Aldo Bellone, Francesca Rossano, Massimiliano Bringiotti

"In 2004 works started for the now completed seven-level automated car park accommodating 480 parking spaces inside the pre-existent “Morelli cave”, located in a strategic area in Naples. Since 470 BC Greeks initiated the growth of the fascinating world of the underground Naples, of which this cave belongs. It seems that once here the god Mithras was worshiped. It’s also became a quarry for tuff extraction and in 1600s it became an aqueduct serving the area. In 1853 the Bourbon Tunnel, a project commissioned by King Ferdinand II of Bourbon to allow easy escape from the Royal Palace in case of riots, was connected to this network of tunnels. The cavern became an air raid shelter during the Second World War, then a deposit of cars and motorcycles in the '50s and' 60s, a disposal area and it has been abandoned in the last 40 years before it’s new utilization. INTRODUCTION Over time, the overcrowding and congestion of major cities’ historic centres has led to seeking spaces underground that can accommodate activities and car parks, as in the case of the Morelli cavity, site of the future car park by that name. Before describing its characteristics, design solutions, and executive problems, it is necessary to introduce the site historically into the broader landscape of the cavities present below ground in the municipality of Naples. The province of Naples, which includes the area of the Municipality of Naples, has a large number of cavities. The existence of “Naples underground” is connected with the morphological and geological conformation of its territory, consisting of tuff stone which has entirely special features of lightness, brittleness, and stability. The first transformations in the territory’s morphology, taking place thanks to the Greeks starting from 470 BC, initiated the growth of the fascinating world of Naples underground. These transformations were dictated by water provision requirements, which led to the creation of underground cisterns to collect rainwater, and by the need to recover construction material to erect the buildings of Neapolis. In subsequent centuries, the city’s expansion led to the construction of a proper aqueduct, which allowed drinking water to be collected and distributed thanks to a series of cisterns linked to a dense network of tunnels. During Roman rule, the existing aqueduct was expanded and perfected, but with the rise of the Angevins in 1266, the city saw great urban expansion, which obviously corresponded with increased extraction of tuff from the subsoil to construct new buildings. This confirmed a particular feature of Naples: that of having been generated from its own innards, with buildings rising directly above the quarry that provided their building material."

Jan 1, 2016

By W. Ghyoot, J. Boonstra, H. Dijkman, C. Buisman, M. Picavet

Paques and Umicore have demonstrated the feasibility of biological treatment of the highly complex Hoboken wastewaters in a1 m3/h pilot plant at Umicore Precious Metals, Hoboken, Belgium. In the first step arsenic was precipitated from copper smelter effluent as As2S3using biogenic produced H2S. Other metals such as copper, lead and cadmium were also removed as MeS to concentrations well below the discharge levels. Subsequently, sulfate and nitrate were removed to low concentrations (<300 mg/l and < 5 mg/l respectively) in high rate engineered bioreactors. Sulfide produced in the sulfate reduction process was recycled to step 1 for metals precipitation. Selenite/selenate was partly removed in the sulfide precipitation step, whereas the excess was biologically reduced and removed as selenium to concentrations <0.2 mg/l.

Jan 1, 2003

By J. R. Pennington

The town of Green River, Wyoming, is located along the Green River on an arid plateau at a elevation of 6,300 feet. Green River has become the center of a booming soda ash industry. The rapid development of coal, oil, and gas resources, coupled with the soda ash boom, have created growth pains for the area. Green River and Rock Springs have experienced a 20-25% population increase in 1973 alone. However, public officials, business leaders, and local citizens are taking positive steps to ease the problems relating to housing, schools, medical services, and recreational facilities. What Is Soda Ash? Soda ash is one of the most widely used chemicals in the world. It is an important raw material in the manufacture of glass, paper, soap, petroleum products, metals, chemicals, pharmaceuticals, plastics, and a host of other items essential to every day living. In ancient times, soda ash was obtained from water solutions of various desert earths. Later, it was produced by leaching the ashes of wood and seaweed. For the past 100 years, it has been manufactured by the ammonia-soda process, which employs large quantities of salt, limestone, and coal as raw materials.

Jan 1, 1974

By M. J. Wilhelm

Bromine is the intermediate member of the halogen family of elements between iodine, a solid, and chlorine, a gas. The name is derived from the Greek bromos, meaning stench. Bromine is the only nonmetallic element that is liquid at room temperatures, with a melting point of -7.2°C and a boiling point of 58.78°C. Reddish brown in color, it dissolves easily in water to yield a red solution. Bromine volatilizes at ordinary temperatures to a red vapor that is very irritating to the eyes, nose, and throat. Density of the liquid is 3.12, and gas weighs 7.59 gpl in standard conditions. Because the element is highly active, it exists in nature only as bromide compounds. Bromine was discovered by Antoine Jerome Balard in seawater bitterns in 1825 and began to find commercial applications shortly thereafter in photography, medicine, and dyes. The first commercial production of bromine was in 1846 in Freeport, PA, followed by production in Germany in 1865. OCCURRENCE Bromine is widely distributed in nature, and compounds occur in solution in natural brines, in seawater, saline lakes, oil and gas well brines, and in evaporite chloride minerals. The concentration of bromine salts ranges from 60 to 65 ppm in seawater to several thousand ppm in oil well brines and saline lakes. The distribution of bromine in marine evaporite minerals and in the solutions from which they crystallized was determined many years ago by H.E. Boeke (1908). Theoretical aspects regarding the geochemistry of bromine have been published in numerous papers (Raup and Mite, 1969). Bromine occurs in solid solution in carnallite and sylvite associated in potash deposits, in halite in salt beds, salt in oil shales, and in trona deposits. Its presence is useful as a guide in geochemical exploration. The analysis of small amounts of bromides in the presence of large amounts of chlorides is discussed by W. Schwerdtner (1963). Manganese, iron, and iodine may interfere with the determination. Other analytical methods are discussed at length in literature (Stenger and Atchison, 1964).

Jan 1, 1994

By R. K. Sinha, B. S. Choudhary, Desh Deepak, A. K. Mishra, Hemant Agrawal, Shankar Kumar

Despite several methods (empirical, statistical and machine-learning tools) to calculate blast-induced ground vibration, it is not easy to predict and simulate blast vibration precisely under varying blasting loads and strata conditions due to complications in the blasting procedure. In this study, field blast data were simulated in Ansys software using explicit dynamics, and ground vibrations for 20 single-hole blasts were monitored. The densities of emulsion explosives were in the range of 0.9 to 1.15 g/cm3. In the laboratory, rock properties were determined from rock samples collected from the mine site before blasting. The in-hole velocity of detonation (VoD) and density of the emulsion explosive were also determined and used in numerical analysis to know the ground vibrations at specific points. The results of ground vibrations predicted by the model were validated using field data.

By N. L. Wesis

General History The first jaw crusher in the US was patented about 1830, but the Blake crusher that has maintained a substantial advantage over other types was invented in 1858 by Eli Whitney Blake. For going on 150 years the jaw crusher has been an invaluable machine; even today, when gyratory crushers have assumed most of the burden of crushing large tonnages of large rock and ore, the jaw crusher has a firm place in the mining industry. It is interesting that soon after the invention of the Philetius Gates gyratory crusher in 1881, a contest between the first No. 2 Gates and Blake jaw crushers of equal gape showed the gyratory to be 3.2 times as fast. This foretold a day not far in the future when the jaw crusher would not be adequate on the largest jobs. In his Textbook of Ore Dressing (1909) R. H. Richards recom¬mended that the word breaker be used for all machines breaking to relatively large sizes (say to 5 in. or greater), and crusher be used for finer work. Even in the 1968 US Bureau of Mines dictionary of mining terms the work breaker is defined by Richards in this context. However, in modern US usage it is nearly limited to coal breaking. Over the years the jaw crusher has been developed in a variety of forms but it appears today in these three general forms: (I) Blake type, (2) Dodge type, and (3) single toggle (or overhead eccentric) type. All of these crushers have a fixed jaw and a moving jaw, between which the coarse rock fragments are intermittently caught and crushed. The three types are differentiated by the manner in which the movable jaw is moved in relation to the fixed. Types The Blake-type crusher is shown in cross section in Fig. 1. The simplicity and strength that have made it first among jaw crushers are evident. The movable jaw is suspended from a cross-shaft at its upper end, this shaft being carried in bearings on the sides of the frame. The actuating mechanism consists of an eccentric shaft, also supported in frame-mounted bearings, which imparts through a pit¬ man and a pair of toggles a reciprocating motion to the bottom of the swing jaw, the return movement being effected by several spring¬loaded rods. The whole is built into a box frame with the crushing chamber at one end. As in all jaw crushers, the eccentric shaft is equipped with a heavy flywheel that maintains an even speed through¬out each stroke. The Dodge-type crusher illustrated in Fig. 2 is simple, mechani¬cally. Its movable jaw, being pivoted below the discharge opening, has minimum movement at crusher discharge and maximum at crusher feed. Because the choke point coincides with the point of least motion, these crushers are of relatively low capacity, and the rapid action in the feed area gives the machine the advantages of large reduction ratio and closely sized product. Thus, it fits well into low-capacity operations like sample reduction. Besides low capacity, its principal disadvantages are tendency to pack and make fines. The single-toggle or overhead-eccentric type of jaw crusher (see Fig. 3) has gained in usage, starting as a modification of the Dodge idea in that the greatest movement of the movable jaw occurs at the top, and being gradually improved and strengthened to its position today where it covers just as wide a field of application as the Blake type from the standpoint of feed opening. The motion of the movable jaw is the result of the circular motion of the eccentric shaft at the top of the swing jaw combined with the rocking action imparted to the bottom by the inclined toggle plate. Because of light weight and mechanical simplicity, it is economical in small mills and portable plants where the rock is not as tough and abrasive as to punish the machine with excessive impact from shocks, or excessive wear result¬ing from the pronounced vertical component of motion.

Jan 1, 1985

By R. F. Winkle

Shortly after World War II, considerable impetus was given to use of truck haulage in open pit mines by the manufacture of large off-highway trucks. Mine management was quick to utilize this more flexible approach to open pit operation and in the ensuing years much time and energy has been spent to improve the basic concept. Dramatic progress has been made in drilling, blasting, loading and hauling with much emphasis placed on equipment improvement. In general, haul roads in open pit mines and quarries have received rather perfunctory treatment in studies of surface mining operations. Their importance to the successful pit operation requires more than a brief sentence saying, "Good haul roads must be maintained." Haulage costs account for approximately one-third of total mining costs including general costs and about 90 percent of the total loading-haulage cycle time is consumed in travel, hence, good haul road planning, construction and maintenance are mandatory for a viable operation.

Jan 1, 1976

By G. P. Dvoichenkova, E. A. Trofimova, M. V. Zaskevich, V. A. Chanturiya

The paper presents theoretical and practical aspects of directed adjustment of physicochemical properties (pH,Eh) and ion composition of recycle and mine water by electrochemical treatment. Treatment is run in the conditioners of diaphragm-type with production of alkaline catholyte of pH value up to 12 and acidic anolyte of pH up to 2. In process of water electrolysis the directed motion of Mg2+ and Ca2+ ions is observed from anode volume to cathode one, were they precipitate as hydroxides and carbonates; it leads to decrease of salt content in anolyte and catholyte. The anolyte has been concentrating anions, it is being saturated with oxygen, which reaches 20-35 mg/L. The results of experimental and industrial testing of electrochemical technique for mine and recycle water in flotation of diamond-containing and sulphide-scheelite, hematite, phosporite, apatite-nephelite, bauxite ores indicated the increase of recovery up to 2-1 5% and grade up to 0,5-2%, concurrent with decrease of reagent consumption from 15 to 50 %. Modules of industrial conditioners of different type capacity have been developed.

Jan 1, 1995

By R. Fedors, T. Ghezzehei, D. Or

The phenomena of dripping into cavities (e.g., tunnels and drifts) within an unsaturated fractured porous medium under ventilated conditions was studied to improve estimates of dripping rates, drop sizes and the chemical composition of droplets that could affect the integrity of high-level nuclear waste packages placed in drifts. The sensitivity of dripping rates and water chemistry to ventilation was analyzed at various flow rates using analytical expressions linking flow on fracture surfaces to drop formation and evaporation. The model was tested using laboratory experiments involving machined aluminum slabs designed to represent a simplified morphology of a fracture face intersecting a cavity and using natural fracture surfaces from a welded tuff Comparison with ten years of data on dripping in natural caves showed good agreement with model predictions. In particular, for low dripping rates, evaporation due to ventilation leads to larger drop sizes and alters drop chemistry by increasing the concentration of solutes in the drop relative to that in the water flowing on the fracture face.

Jan 1, 2002