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By Jianmin Qin, Raja V. Ramani

In this paper, the results of a research study on airborne dust transport in a full scale simulated longwall face are presented. The simulated longwall face was set up in the Lake Lynn Laboratory mine of the U.S. Bureau of Mines to conduct experiments under controlled conditions. The controlled parameters in the experiments were the dust dispersion rate, dust size distribution, density of the dust, air velocity, and the rate of travel of the dust generating source. The analyses of the experimental results on mass concentrations, particle size distributions, and real-time respirable dust concentrations are discussed. There are definite spatio-temporal trends between the location of the shearer, the concentration at any location in the face, and the dust generation rates. The size-consist and density characteristics of the source dust, the air velocity in the face, and the air leakage into the gobs all affect the concentration.

Jan 1, 1995

By P. Somasundaran, Bruno Lartiges

Two different groups of mechanisms have been considered in the past to explain the effects of chemical additives on grinding. While one group of explanations is based upon alterations of surface and mechanical properties of the individual particles, the other group depends mainly on the arrangement of particles and their flow in suspensions. In this paper some of the past work on grinding aids is reviewed and attrition grinding of a commercially important ceramic material, zirconia (stabilized with yttria) with polyaaylic acid as grinding aid, is studied in order to determine the effect of the aid on the ground product itself. It was observed that even though polyaaylic acid did cause a drastic decrease in the viscosity of the pulp, it did not have any major effect on the grinding of zirconia at least up to 2000 ppm and only minor detrimental effect above it. Importantly, complexation by the polymer was found to cause extraction of yttrium into solution with possibly significant changes in the surface chemical composition of the product.

Jan 1, 1992

By Joseph Renk, David Akers, Glenn Shirey

Each year, US coal cleaning plants landfill or impound millions of tons of high-quality, fine-sized coal. This coal is not only difficult and expensive to capture during cleaning, but, if captured, can pose serious materials handling problems. The GranuFlow. Technology was developed and patented by the U.S. Department of Energy (DOE) to address these problems. GranuFlow involves the addition of a coal binding agent such as an asphalt or heavy oil emulsion to coal to reduce moisture, dusting, and freezing and to improve the flow properties of the coal in bins and chutes (1, 2, and 3). When the emulsion is added before mechanical dewatering, the binding agent causes the formation of fine-sized coal agglomerates that dewater better than untreated coal. In addition, the binding agent increases the capture of ultra-fine coal in screen-bowl centrifuges. Previous work by DOE has also demonstrated that such treatment results in a significant reduction in dustiness and a reduced potential to freeze. To address concerns about the handling and combustion characteristics of GranuFlow treated coal, DOE performed a pilot-scale pulverization and combustion test (4). No problems were encountered during pulverization or combustion, and use of this fuel in a p.c. boiler was found to be feasible from a technical perspective. CQ Inc. has an exclusive license from DOE to market this technology and is currently performing a series of commercial demonstrations to determine if GranuFlow is both technically and economically viable.

Jan 1, 2005

By J. Felipe Costa, Andrew H. White, Marcot T. M. B. Vilhena

Ordinary kriiing (OK) is an interpolation algorithm mostly used in earth sciences applications where it provides satisfactory results. Robust kriging (RK) is an alternative algorithm which at- tempts to minimise the problems caused by the existence of outlier values within a given data set. Robust kriging essentially consists of an editing step prior to running the traditional OK method. This study compares the interpolation results obtained by OK and RK. Two data sets were used. The first data set consists of 140 samples mimicking a drilling survey named cluster.dat. An additional feature of this sample data is that its parent population, the reference data set, is available, thus permitting direct quantitative assessment of the effectiveness of a given estimation technique. The second data set consists of a grid sampled at 1x1 m. The estimates obtained by OK and RK using cluster.dat were compared to the reference data set. RK provided better results in terms of quality of the estimates than OK

Jan 1, 1996

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 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

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 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 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 John C. LaScola, Gerald L. Finfinger, Michael A. Trevits

Methane gas is an ever-present problem facing the underground coal mining industry. Mine operators are mandated by law to maintain safe concentrations of methane gas within the mine environment. Ventilation is the method of choice used by all mine operators to reduce gas concentrations. When gas emissions are such that ventilation alone cannot control the gas, methane drainage methods must be applied. In the 1970’s, there was a concern that unprecedented gas emissions would be experienced as mine operators began new developments in the deep and gassy Blue Creek and Pocahontas No. 3 Coalbeds. Such concern was well founded as significant gas volumes are being emitted as these mining operations mature. In 1971, the U.S. Bureau of Mines began to tabulate and track the change in mine emissions. These data were extracted from the underground coal mine quarterly air quality-quantity inspections performed by the Mine Safety and Health Administration. At that time, approximately 6560 Mm3/d (231.7 MMcfd) of gas were emitted from 430 underground coal mines. It was determined however, that the mines emitting less than 2832 m3/d (100 Mcfd) contributed only 2.1 percent of the total daily gas flow. In 1988, underground coal mines emitted 8350 Mm3/d (294.9 MMcfd) from 487 mines. This report evaluates the changing nature of U.S. mine gas emissions over the last 18 years.

Jan 1, 1991

By Charles H. Jacoby

Introduction Although, in general, the openings created in domes or diapiric type salt deposits during mining operations are larger than those created in bedded deposits, the openings in bedded salts are of significant lateral extent. Thus, this paper will deal primarily with the dome deposits of the Gulf Coast and more specifically with the Avery Island dome operated by the International Salt Company where recent development activities have materially increased the sizes of previously standard openings. Geology The geology of salt deposits is the governing factor in the rock mechanics associated with the opening which is being created in the salt. Bedded salts are customarily characterized by having experienced solution along the interface between the top of the salt and the overlying bed. Thus, as the salt slowly dissolves there has been left behind a layer of laminated insolubles which is often incompetent. In most cases, this incompetent rock must be supported by a thickness of bedded salt which is left in the roof as support. Where this salt is of secondary deposition (recrystallized halite) with included moisture, additional thicknesses of roof salt are necessary to achieve stability. The salt which forms the domes of the Gulf Coast regions is from the Louann formation of the Jurassic period. These formations are dipping toward the Gulf of Mexico so that the upper tier of domes which have formed across northern Louisiana in an east-west direction into Mississippi and Texas have a salt source some 10 to 15,000 feet

Jan 1, 1976

By J. K. Whyatt

A microcomputer controlled data acquisition system has been developed for automatic monitoring of underground instrumentation from a remote location. The system has been used extensively by Spokane Research Center personnel for monitoring rock instrumentation in shafts, drifts, and stopes in hardrock and coal mines, especially where instrument access is limited. Ruggedness was a major consideration in designing the underground portion of the system and it has performed satisfactorily under extreme environmental conditions, including temperatures to 1100 F, 100% humidity, and falling water. The major advantage of the system is that it multiplexes the data from 16 channels through a single twisted pair cable to the receiver, significantly reducing cabling requirements. This receiving station can be as far as 8,000 ft from the instruments without the addition of line drivers. The receiver maintains a data buffer with the latest scans, which is periodical 1 y accessed by a micro- computer, either locally or through a modem, that automatically records and reduces the data. Utilities allow on-site plotting of data and uploading of data to mainframe computers.

Jan 1, 1986

By Jörg Weidemann, Peter W. Kuchar, Paul Burgwinkel

The West German Ruhrkohle AG and the engineering company BEDIA have developed an emission control system for diesel engines that is suitable for use in underground coal mining, consisting of a granular catalytic converter and a dry cooling system. Its first ever application was to a diesel mining locomotive. In the catalytic converter the exhaust gases pass over porous, platinum-covered ceramic balls in a double tube, oxidizing CO to CO2. Simultaneously, soot particles in the gases are subjected to afterburning. Laboratory tests carried out by BEDIA and at Aachen University of Technology showed that there was a reduction of over 80% in the CO content of the exhaust gases and over 30% in soot emission. The dry cooling system fulfills all the requirements demanded of exhaust cooling underground and does not have the disadvantages of conventional systems. It needs little maintenance, and it is light and compact. The most important components are a waterjacketed exhaust manifold, a tube and shell heat exchanger, a new type of flame arrestor in a stacked crimped ribbon design and a Venturi diluter. The system has its own thermostatically-controlled cooling circuit to keep the exhaust temperature between 120° C and 150° C, thus effectively preventing the tubes becoming blocked up.

Jan 1, 1989

By S. Mathur

Oxide particles are commonly used as fillers in plastics, paper, rubber, etc. (particulate composites). The successful fabrication of such composites is dependent upon the adhesive strength of the filler particles to the matrix. The compatibility of the matrix and the filler particles is generally enhanced by the adsorption of surface modifiers such as surfactants and polymers at the particle-matrix interface. To develop a scientific basis for the selection of the appropriate modifiers it is necessary to understand their adsorption mechanisms. specifically, the adsorption of polymeric additives is attributed to a combination of chemical and electrostatic interactions, hydrogen bonding and van der Waals forces. Hydrogen bonding has been suggested to be the primary adsorption mechanism for nonionic polymers. However, a literature survey of the Poly(ethylene oxide) (PEO)-oxide system suggested that PEO, a nonionic polymer, was substrate specific. A systematic study was undertaken to investigate the adsorption mechanisms of PEO on oxide particles. It was determined that strong Bronsted acid sites on the surface interact with the ether oxygen, a Lewis base, of PEO to induce adsorption. In this work, characterization of PEO binding sites on oxides is reported and the mechanisms of PEO adsorption are discussed.

Jan 1, 1999

By G. Adel, J. M. Richardson

Mine-to-mill optimization is a holistic approach to the optimization of mining and processing operations. Developed at the Julius Kruttschnitt Mineral Research Centre, it attempts to minimize energy consumption through the optimization of the particle size reduction process. The approach involves sampling and modeling of blasting and processing, computer simulation to optimize the operation and develop alternatives, implementation of the most promising alternatives, and sampling to quantify energy savings. The primary objective of the present effort is to adapt mine-to-mill technology to the aggregates industry. This paper presents an update of work being conducted at quarries operated by the Luck Stone Corporation of Richmond, Virginia.

Jan 1, 2006

By M. A. Marticorena, R. Stratton-Crawley, C. I. Basilio

Diethylenetriamine (DETA) is a selective depressant for nickeliferous pyrrhotite during pentlandite flotation. Laboratory flotation tests conducted on ore and process samples showed that pyrrhotite rejection is greatly improved by small additions of DETA; however, the effectiveness of this depressant is most noticeable when the mineral sample is oxidized. LIMS and XPS analyses conducted on flotation products and pyrrhotite specimens showed that the difficulty in pyrrhotite rejection arises from inadvertent activation of the mineral by heavy metal ions, such as Ni2+, cu2+ and Ag+, that are present in the process water. In the presence of DETA, however, the mineral is deactivated under oxidizing conditions. The deactivation mechanism may involve oxidation of the activation products, which are likely in the form of heavy metal sulfides, followed by solubilization by DETA. FTIR spectra of pyrrhotite electrodes contacted with DETA showed no trace of the reagent on the surface, substantiating the view that its role is one of complexing agent that enhances the dissolution of activation products under oxidizing conditions. FTIR spectra of pyrrhotite contacted with amyl xanthate solutions showed that both dixanthogen and iron xanthate are formed on the surface, the latter becoming more predominant at higher potentials. In the presence of DETA, however, only a small amount of xanthate is adsorbed on the mineral at potentials (Eh) approximately 200 mV higher than the case without DETA.

Jan 1, 1995

By J. Sulaiman Lubis

Indonesia is a developing country in Southeast Asia with a population of some 180 million people. It has a stable political environment and currently enjoys high rates of economic growth. Indonesia has abundant reserves of natural resources, ample for its own needs and for export. Energy resources include oil, gas and coal. The oil and gas industries are well established domestically and for export. In the last few years, though, coal industry development has been rapid. Coal resources from bituminous to lignite amount to more than 30 Gt (33 billion st). That is more than enough to meet domestic needs and provide significant amounts for export. Figure 1 shows coal basins in Indonesia. Coals in Indonesia are generally young steaming coals. They are very low ash and sulfur, high volatile, bituminous B and C. The Indonesian government's state coal company is called Perum Tambang Batubara. The company has actively promoted the development of its coal for domestic and export markets. In particular, the government has placed priority on non-oil exports of which coal is a major element. The government strives to honor all contractural commitments for the export of Indonesian coal from contractor, private and government mines. From 1987 through 1989, coal production has increased from about 3 Mt (3.3 million st) to 9 Mt (9.9 million st). Exports have grown from I Mt (1.1 million st) to 3 Mt (3.3 million st). These are significant increases for a small industry with limited infrastructure. But with growing investment and development, these production and export levels will increase substantially, and Indonesia will be a significant world supplier of coal in the 1990s.

Jan 1, 1990

By V. Rastogi

Surfactant-based bactericides are able to control acid formation in sulfidic materials such as pyrite and sulfidic ores, thereby helping to abate acid rock drainage. Bactericides are used in the following two ways: as periodic or continuous spray treatments for the prevention of acidification of material actively handled and moved and in controlled-release form for reclamation. Site-specific bactericide treatments are designed for active sites and reclamation. Results from two active coal refuse sites show that acid production can be reduced by 88% or more. Results from reclaimed sites show that bactericide treatment can be more effective than the addition of alkaline materials such as limestone and can reduce acid production from 3,500 to <30 ppm. The controlled-release-pellets treatment outlasts the life of the pellets, as shown by a study of a site now 10 years old A single treatment sets up a change in site microbiology to replace acid-producing Thiobacillus ferrooxidans bacteria with heterotrophic bacteria and creates a stable site without the need for further treatments. A secondary beneficial effect of bactericides is on revegetation, and biomass from treated areas is almost 10 times that from areas not treated with bactericide. Depending on the application, bactericide treatment can be cost effective upfront and certainly long-term, compared to the perpetual water treatment that could be required, even after productive use of the site is completed

Jan 1, 1997

By John C. Galloway, Heinz G. Leistner

ACKNOWLEDGEMENTS The investigations described in this paper were supported by contracts with the Defense Nuclear Agency (DNA) under direction of Lt. Col. John Galloway, and by Boeing Company research funds under supervision of James Wooster. Other engineers of The Boeing Company who contributed to the work of this investigation were Don Armitstead, John McAvoy, and Tom Day. INTRODUCTION In this paper, we are describing a current concept for placing intercontinental ballistic missiles (ICBMs) in sites deep underground to be used as a strategic Future Secure Reserve Force (FSRF). The objective of such concepts is to utilize soil and rock cover to protect high value strategic weapons from destruction by nuclear attack. The burial deep underground achieves two purposes. First, it imposes a miss distance upon the attacking weapon equal to the depth of burial minus any penetration capability the weapon might have. This tends to offset increasing accuracy of weapon delivery. The other purpose is to absorb as much of the weapon&apos;s energy as possible, thus reducing the effects of powerful weapons. This use of soil or rock cover over military facilities began with the development of man&apos;s capability to loft projectiles. Until recently, underground military installations, by their nature, performed defensive functions. Since they are not mobile and their weapons in the past had very limited range, an enemy would have to approach them before an engagement could take place. Thus, they were often used to control "choke points" on sea lanes as in the case of Gibraltar or

Jan 1, 1979