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By George Fumich

The Office of Coal Research has been supporting the development of processes for producing synthetic pipeline gas from coal since 1964. .Some of this work has also been jointly supported by the American Gas Association. The work has progressed through laboratory investigation, to bench scale, to pilot plant. It was far from a crash program, generally being fund-limited.. As of one year ago, we had reached the following position: 1. The Institute of Gas Technology HYGAS. process pilot plant in Chicago, Illinois, was in the process of being finally completed. This plant is designed to produce about 1,500,000 cubic feet of pipeline-quality gas per day from 75 tons of coal. 2. The Consolidation Coal Company, CO2 Acceptor Process pilot plant in Rapid City, South Dakota, was well._ on its way to completion. This plant, designed primarily for lignite and subbituminous coals, has about one-half the design capacity of the HYGAS plant. Additionally, the initial construction did not provide for cleanup and methanation; only the preliminary synthesis gas is produced. 3. The Bituminous Coal Research, Inca, BI-GAS pilot plant was in a preliminary design stage. A site had been selected near Homer City, Pennsylvania, to build this plant, planned to consume 120 tons of coal per day. Meanwhile, as you are all well aware, a natural gas shortage was developing in this country. Much has been published about it, so I will not. bother you with further details. Suffice it to say that the reserve-to-production ratio has been steadily declining, because we have been using.-as-faster than we have been find-

Jan 1, 1972

By Jorgen Elbrond

The calculation of open pit operations' capacities has been the subject of many studies using computer simulations. The common problems of simulation are that if one desires a realistic picture of an operation the programming work becomes long and expensive and that the program requires a large computer and long time to run. The method presented in this paper overcomes these problems by using a straightforward calculation procedure. It is based on the queuing theory's simple formula for waiting time in a closed circuit and uses a system of correction factors, which reflect the loading, travel, and dumping times' relative variabilities and which have been found by 1) mathematical analysis and 2) simulations of basic circuits. The method includes the main parameters of the operation: numbers, sizes and operational availabilities of trucks, shovels and dumping point, distribution of the production over shovels, trucks' loading, travel (loaded and empty) and dumping times as well as their variabilities, shift's composition. The procedure models: the average duration of a complete truck cycle during stationary and non-stationary periods during the shift as a function of the number of trucks in the circuit, the composition of the average 100% operated shift, the simultaneous probabilities of operationally available shovels and trucks and the distribution of shovels and trucks according to production and cycle times. The procedure can be programmed for a small computer and requires only short computing time, which makes extensive studies of various parameter combinations practical to carry out. The development of the method is an extension of previous work by Morgan and Peterson {1}, who by simulation established the relation between the match factor (which is the ratio between the sum of one loading time pr truck in the circuit and the complete net cycle time) and the shovel's efficiency, and by Hayes, Splaine and Whitaker {2}, who established this relation from a large number of observations in the Nchanga pit in Zambia. The present method establishes this relation by a straightforward calculation procedure. Theoretical solutions to some situations are found in the litterature on the queuing theory. The papers {3},{4} and {5} give solutions to situations, which fall outside those encountered in the shovel-trucks circuit. These solutions together with simulations of in-termediary situations have been used to establish an interpolation procedure for the correction factors to be applied to the waiting time formula in order to cover the situations encountered in practice.

Jan 1, 1977

By J. Duran

Mining at Newmont Mining?s Phoenix?s Mine is currently done by surface operation in the Fortitude and Bonanza pits at a combined rate of approximately 100 kt/d (110,000 stpd). A portion of the orebodies targeted by these pits was mined previously by underground mining methods, dating back to the mid-to late-1800s. Most of the underground workings (voids) are located in the west central area of the Bonanza pit. The surface operation requires excavation through voids, and there is a risk of pit floor subsidence that has to be addressed. This article presents a review of the risk mitigation measures that were implemented to reduce risks to people and equipment working in the area.

By Thomas Novak, Sampurna Arya

Controlling dust generation and keeping it below permissible limits to meet federal dust standards at the working face of a room-and-pillar coal mine is a challenge for a mine operator. With the recent changes in federal dust regulations requiring lower worker exposure, maintaining compliance has become increasingly difficult. The current most effective practice of dust control at a continuous miner face in an underground mine is the use of a flooded-bed scrubber. A study carried out by the U.S National Institute for Occupational Safety and Health (NIOSH) indicated that a flooded-bed scrubber could achieve cleaning efficiencies between 58 and 90 percent. But the operation of such a system is maintenance intensive. The flooded-bed scrubber screen becomes clogged with dust particles and requires frequent cleaning to maintain performance. However, the dust control issue is not solely a mining-industry problem. Other industries face similar issues. The University of Kentucky collaborated with Toyota Motor Manufacturing on the development of a novel wet scrubber, called the vortecone scrubber, for capturing over-sprayed paint particles in automotive paint booths. The vortecone scrubber achieved a cleaning efficiency of 99 percent and required minimal maintenance. This study aims to assess the ability of this vortecone scrubber to capture respirable dust in an underground coal mine. The paper presents the results of computational fluid dynamics (CFD) modeling of this vortecone scrubber. It discusses the effects of air quantity and dust particle size on the performance of the scrubber. 

By David R. Hargis

Large-scale groundwater withdrawals are necessary to depressurize a confined aquifer system allowing the dry open-pit mining of the overlying phosphate ore. The extent of the existing and planned groundwater development led to the establishment by the State of North Carolina of Capacity Use Area No. l. Groundwater use in the Capacity Use Area is regulated by a permitting system. A two-dimensional finite-difference ground- water flow model was developed for North Carolina Phosphate Corporation. The aim of the model is to aid the Corporation in matters relating to permitting by serving as a predictive tool. The model can be used to project regional water level impacts resulting from various scenarios of depressurization pumping.

Jan 1, 1983

By III Westbrook

Although calcium sulfate dihydrate, commonly referred to as gypsum, has been utilized for some time in fiberglass reinforced polyester (FRP) applications, it does not have the fire retardant filler recognition of ATH. Gypsum is more commonly known for application in cement, soil and water treatment, plaster, and wall-board. Inherent characteristics of gypsum limit its use to low temperature and, until recently, non-aqueous applications. However, as a plentiful, naturally occurring hydrated mineral, the cost effectiveness of calcium sulfate dihydrate has prompted development and yielded success in the areas of FRP spray-up and latex carpet backing.

Jan 1, 1993

By Louis W. Riggs

The primary concern in dealing with contractual arrangements for construction is getting the work completed satisfactorily, in the shortest time, and for the least expense for the owner--while assuring that all other parties associated with the contract make a reasonable profit for their effort. In our complex construction climate of today, achieving all of these is usually not possible. Somewhere between the beginning of design and the completion of the work, disagreements and delays arise which can destroy the best of intentions. Assuming that all parties associated with the contract are acting honorably and professionally, the disagreements generally arise through inappropriate contract types or through flawed contract documents. These flaws can be either sins of omission or commission, but we must find a way to lessen, if not completely eliminate, their impact. Disagreements and delays are directly related to the extra cost which the owner and the other involved parties must suffer. Usually the attorneys are the only ones who come out on the positive side. Inappropriate or defective contract documents can be the result of inadequate time for preparation and review, laziness in not searching out the proper terms and language, insufficient recognition of the proper assignment of risks, or just ignorance as to what is right and what is wrong for the particular project. They can also result from a client, particularly a public agency, providing rigid general conditions and format requirements with which the engineer is not allowed to tamper. Arguments

Jan 1, 1979

By Samuel Sigman, Martin M. Cooper

A basic ingredient for rapid tunnel excavation is material handling. In construction of tunnel projects in urban areas material handling requires additional input to maximize performance. Urban projects share the same problems experienced in all tunnel construction and they must be dealt with. Howeve.., Urban constraints add a larger dimension. APPLICATION ENGINEERING A MUST A word of caution. To achieve increasing speed of excavation in tunnels whether in Urban areas or elsewhere will require much creative thought and energy. It would be a false premise to assume that major breakthroughs will result from this conference, or shortly thereafter, or to hope that a success here or there can translate into a universal solution. The reality, as we see it is that rapid progress and great economies will accrue on any given project only if effective application engineering is carried through. By all means take advantage of past experiences but, do not at the peril of costly undertaking, blindly accept the program of a successful job elsewhere as automatically suited to your project. Tunnel construction in urban areas is at best a difficult undertaking made more difficult in this period of greater awareness of environment, of conservation and of the quality of living by sophisticated urban communities,. A construction job represents a necessary nuisance to urban communities. To minimize this nuisance many regulatory laws are adopted. These regulations can and do slow down tunnel jobs and pyramid costs.

Jan 1, 1974

By Alan J. Solomon

The function of advertising is communication. Viewing the advertisements of mineral suppliers exposes the reader to a broad spectrum of purposes: announcements of new products, availability and supply, departmental services, company image, etc. It is the advertiser's hope that the message being conveyed is the same message being perceived by the viewer. To maximize this probability, the advertiser at least must carefully construct precise copy, identify the target audience and select the appropriate advertising medium. A truly successful and efficient ad, however, also must accurately reflect a product's life cycle, i.e., the rise and fall in demand for a product. Buggy whips and radio tubes are classic examples of items formerly in high demand. Industrial minerals are similarly affected by occurrences of product life cycles.

Jan 1, 1983

Just 104 km (65 miles) from Phoenix, AZ, Rio Tinto hopes its new Resolution Copper Mine will be a showcase for the Rio Tinto management philosophy. Its goal is to have a net positive impact. In every place that Rio Tinto mines, it wants to be able to have an overall beneficial effect on the local community, environment and economy. ?We?re constantly working to understand our impacts, to understand how to minimize our impacts and understand how to mitigate those impacts,? said Resolution Copper Mining chief executive officer David Salisbury, from the global headquarters of Rio Tinto Minerals in Green-wood Village, CO.

Jan 1, 2010

By F. B. Brost

In 1976, a decision was made by Anamax Mining Company to install an unusual conveying system to transport ore 10.3 km (6.4 mi) from the new Eisenhower Mine to the Twin Buttes concentrator. The system, supplied by Cable Belt Limited of the United Kingdom, represents a radical departure from conventional belt conveyors. The driving tension is applied through two endless wire ropes driven by a single 2 240 kw (3 000 HP) drive while the belt acts only as the ore carrying medium. Full production was begun in January, 1979. Start-up problems hampered production for several months but were resolved by a joint Anamax-Cable Belt effort. The system has been operating at design capacity for 4-1/2 years, and has proven itself as a reliable, low cost ore transportation system.

Jan 1, 1984

By Timothy G. Shuttleworth

In the late1970s, mineral processing plants producing copper sulfide concentrates and oxide leaching feedstocks went online with operating tonnages that exceeded traditional installations. This created a need for larger capacity belt conveyors and apron feeders. Apron feeders are slow moving, heavily loaded conveyors that feed a deep bed of ore from a bulk holding location (a bunker) as a controlled stream, often into a large capacity crusher. Apron feeders use sprockets and caterpillars, while belt feeders use rubber belts with motorized head pulleys to convey the material. The damaging of belts and clogging of transfer points from tramp iron required larger magnetic separators and the removal of tramp metal cannot prevent these serious problems. Corrective action at this location is important for two reasons: Removing tramp iron early in the ore stream protects downstream equipment from potential costly damage. Installing apron feeder magnets before the primary large capacity crusher means that secondary and tertiary crushing steps (made up of multiple parallel units) operate more efficiently, since tramp metal is removed at the onset.

Jan 1, 2011

By R. K. Mehta

An accurate, efficient and stable computation of the mill matrix function (eAt) is needed where mill matrix (A) is a real general matrix. Two important modeling cases in comminution where such need arises are: Heterogeneous comminution behavior of multi-component ores and ultra-fine grinding involving simultaneous attrition and fragmentation breakages. This paper presents the application of a novel splitting method in conjunction With similarity transformation technique in the form of "product formula" which is found to work in all cases and uses a most aggravating, yet interesting property of the matrix exponential in a restricted sense. Results are presented showing that this method can yield solution as accurate as those obtained With an analytical technique. The utility of this computational approach is demonstrated by parameter estimation analysis using a distributed component model in the liberation area through computer simulations.

Jan 1, 1992

"Iron ore is the source of primary iron for the world’s iron and steel industries. Its production can be reported as crude ore, usable ore or iron content of ore. Historically, the U.S. Geological Survey (USGS) used reported crude ore production from China in tabulations of world iron ore production while other countries have typically reported their production in terms of usable iron ore. When China’s crude ore production was tabulated with usable ore production from other countries, world iron ore production totals have been overestimated by 10 percent to a high of content and may include products such as concentrates, direct-shipping ore, pellets, and sinter.• Iron content, also referred to as metal content or grade, denotes the amount of elemental iron in the crude or usable ore.BackgroundIron ores consumed in the steel industry typically require an iron content greater than 58 percent before being considered commercially usable. Iron ores that are not commercially usable must undergo beneficiation to raise the iron content. Approximately 98 percent of the world’s usable iron ore production is consumed in blast furnaces to make pig iron, which is further processed to make steel.High-grade iron ore mines can supply usable iron ore, known as direct-shipping ore, to blast furnaces, with minimal physical processing and no beneficiation. With direct-shipping ore, the reported production for crude ore and usable ore are the same. Ore from low-grade deposits must undergo beneficiation to increase the iron content before it can be used by the steel industry. In this instance, the mined material is called crude ore and post-beneficiation concentrates are called usable ore; the amount produced will be less than the crude ore amount. With the notable exceptions of countries such as Australia and Brazil, most of the world’s iron ore deposits are low-grade and require beneficiation."

Feb 1, 2017

By A. Ghosh

Commonly used predictors of ground vibration from blasting, being linear in log-log plot, do not model the underlying physics of wave attenuation. Amplitude of the wave decays with distance due to geometrical spreading and inelastic attenuation producing a nonlinear carve in log-log scale. The nolinear decay of seismic waves has also been observed from non-explosive sources, such as, pile driving, drop hammer, traffic, etc. The improved predictors, by explicitly taking these two mechanisms into consideration, model the data trend extremely well at all distance ranges. Actual field data from different studies have been used to validate the improved models.

Jan 1, 1991

By David B. Costain

Three dimensional surface approximations are important means of evaluating physical and environmental factors that affect surface coal mining and reclamation. Computer approximated surfaces are projected as an array of square grid cells where individual cells define each parameter value respective to locations on the grid. Grid surfaces or grid cells within a surface can be compared or modified through application of standard mathematical functions. Surface approximations can be used to define the quantity and quality of marketable coal and to evaluate thickness and quality of overburden. Surface approximations also can be used to evaluate overburden swell factors wherein changes in post-mine topographic relief are related to expansion of unconsolidated materials in the backfill. Application of computer approximated surface to analysis of approximate original contour (AOC) standards allows an assessment of the quantity and geographical displacement of overburden and the distribution and numerical level of slope.

Jan 1, 1984

By Yuting Xue, Danqing Gao, Brijes Mishra

Heterogeneity and discontinuity significantly affect rockmass strength. Past studies have largely used arbitrary scaling approaches to produce rockmass strength from laboratory rock tests. This paper proposes a stochastic approach to produce rockmass strength from laboratory rock tests. Based on the laboratory data, MATLAB with an extreme value stochastic model generated a database for each physico-mechanical property of the rock. Then finite-difference software FLAC2D simulated laboratory-sized rock specimens. Random material properties in MATLAB were generated using the grids developed in the numerical model. The random properties were then applied to the final FLAC2D model. Model runs simulated the approach performed in the laboratory. The results from the model indicate that a stochastic approach produced compressive strengths that were lower than those from the deterministic approach. Failure modes for each specimen were different from those observed in the laboratory. In addition, random density also influenced the failure mode, highlighting the importance of stochastic analysis in rocks.

It is widely accepted that particles stabilize flotation froths and that stable froths result in improved flotation performance. Predicting the effect of particle addition on froth stability is, however, challenging. Furthermore, there is currently no technique that allows the prediction of the effect of different flotation reagents on froth stability, without carrying out froth stability experiments.

By Maria S. Adusumilli, A. Bhaskara Rao

ABSTRACT The presence of gold in lateritic crusts over mafic and ultramafic volcanogenic complexes in / and greenstohe belts, has called the attention in several parts of Brazil and also in Australia. Recent studies reveal the variety of structures and mineralogy of such crusts, and their importance in correlation with host(bed) rock types, as exploration guides, specially for greenstone belt metallogeny. The expected nature of growth of plates and/or nuggets in such crusts is under detailed study, and is considered as possibly due to dissolution and reprecipitation phenomenae of disseminated-fine-low grade ore in the host rock, in this investigation, laterite geochemistry, though incipiently discussed todate, is of fundamental importance and significance. Lateritic gold can be classified texturally as: dusty and diffused, fine, thin platy, taDular, and nuggets. Such gold is pure, and is often restricted to nodular (pisoliths, ooliths, concretions) forms or the matrix, that constitute the crusts or lateritised gravel beds which have an essentially goetnitic nature. Further this gold is recovered directly by mining the crusts or the adjoining placers with the metal derived from them. The thickness and extension of laterite crust zones is extremely variable depending oh the paleoclimatic conditions, and is conditioned to the favourable lithology and its structural expression. However, the "growth" of gold in these laterites will be conductive , without doubt, to several small scale mining activities, specially in the developing countries and regions limited to latitudes 309N and 309S.

Jan 1, 1987

By Justin R. Patts, Andrew B. Cecala, A. KYLE LOUK, Emily J. Haas

The U.S. National Institute for Occupational Safety and Health (NIOSH) and the former U.S. Bureau of Mines (USBM) have put significant effort over the past four decades into researching and developing engineering controls and interventions to reduce mine workers’ dust exposures during the bagging and palletizing of industrial minerals. Workers who perform the manual bagging and palletizing of 50- to 100-lb bags typically have some of the highest dust exposures of all workers at mining and mineral processing operations. This paper provides an overview of available dust control technologies for bagging operations and presents the findings of a recent case study conducted at four industrial sand operations to identify the current types of bagging and palletizing technologies being used and to evaluate their effectiveness in reducing workers’ exposures to respirable crystalline silica dust. An evaluation is also performed to determine if further reductions in respirable dust levels can be achieved by incorporating additional modifications or improvements into the existing technology.