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By J. D. Noll, J. A. Organiscak, A. B. Cecala

Significant strides have been made in optimizing the design of filtration and pressurization systems used on the enclosed cabs of mobile mining equipment to reduce respirable dust and provide the best air quality to the equipment operators. Considering all of the advances made in this area, one aspect that still needed to be evaluated was a comparison of the efficiencies of the different filters used in these systems. As high-efficiency particulate arrestance (HEPA) filters provide the highest filtering efficiency, the general assumption would be that they would also provide the greatest level of protection to workers. Researchers for the U.S. National Institute for Occupational Safety and Health (NIOSH) speculated, based upon a previous laboratory study, that filters with minimum efficiency reporting value, or MERV rating, of 16 may be a more appropriate choice than HEPA filters in most cases for the mining industry. A study was therefore performed comparing HEPA and MERV 16 filters on two kinds of underground limestone mining equipment, a roof bolter and a face drill, to evaluate this theory. Testing showed that, at the 95-percent confidence level, there was no statistical difference between the efficiencies of the two types of filters on the two kinds of mining equipment. As the MERV 16 filters were less restrictive, provided greater airflow and cab pressurization, cost less and required less-frequent replacement than the HEPA filters, the MERV 16 filters were concluded to be the optimal choice for both the roof bolter and the face drill in this comparative analysis case study. Another key finding of this study is the substantial improvement in the effectiveness of filtration and pressurization systems when using a final filter design.

Aug 1, 2016

By L. A. Rapoport

This paper outlines the methodology and results pertaining to the simulation of the U.S. coal industry in the context of an integrated, time-dynamic model of Long-Range Energy Developments and Supplies (LORENDAS). By way of background we will present first an overview of the overall LORENDAS model structure. We will, then, outline the characteristics of the formulation and data used for the representation of the U.S. coal industry. Finally, a series of model results will be reviewed, with particular emphasis on the long term projections of coal production and distribution under different basic economic and/or political scenarios.

Jan 1, 1977

By K. K. Bhattacharyya

Vast deposits of lignite occur in the Gulf Coast states and northern plain states. Lignite resources are cited to be over 43 billion tons in the Gulf Coast states. An additional resource of 16 billion tons are reported in North Dakota (Jackson, Smith, 1981). All lignite in the U.S. is mined at present by the open pit method. Draglines and scrapers are primarily used to remove the overburden. Bucket-wheel excavators are also being considered for new mines in the planning stages. Lignite seams are mined using front-end loaders, shovels and trucks, or Easi-miners. The depositional environment of lignite is weak sedimentary soils and rock. Ground water is often encountered within the mining depth. Surface water resulting from heavy rainfall or snow melt contributes to the problems of mining. Mining depths of up to 60 m (200 ft) are under consideration. Draglines exert additional loads on the highwalls and spoil piles. The combination of any number of these factors may cause instability of the slopes. Bearing pressure, trafficability, and settlement can also be a problem for excavation and loading equipment.

Jan 1, 1982

By Armando Correa de Araujo

Cationic flotation of quartz is currently utilized for the concentration of iron ores and for the cleaning of phosphate concentrates. The present work deals with depression of quartz in the presence of aluminum ions during cationic flotation. It was established-that aluminum ions depress the flotation of quartz with an amine, especially under neutral and very slightly alkaline conditions. Studies of adsorption of Al ions on the quartz surface as a function of pH correlated with depression of this mineral with an amine as collector. The presence of Al ions also enhanced the depressant action of corn starch on quartz The sodium salt of ethylenediaminotetra-acetic(EDTA) was found to be an effective complexing agent to supress the depression caused by aluminum ions.

Jan 1, 1984

By Carl E. Williams

During the past two years a computer program called "COPOR," Computerized Open Pit Optimization Routine, has been developed and used for mine planning of several base metal deposits. This routine utilizes a three dimensional computerized block model of an orebody, some economic parameters and operating constraints to locate the mineable or economic limits of the deposit schedule the yearly production from the mine and produce bench by bench ore reserve summaries and maps of the yearly and ultimate pit configurations. The moving cone method is used to perform these functions with a conventional block model. This model is conventional in the sense that each block is assumed to be homogenous; i.e., either ore or waste but not a mixture of the two. Due to the nature of a seam type deposit this approach is not realistic; therefore, revisions have been made to form a new version of the COPOR program. This version has been named "COALOR," Coal Optimization Routine. COALOR contains all of the power of the COPOR program but is equipped to handle the intricacies of coal seam type deposits. The deposit can be composed of a single seam or multiple seams which are horizontal or dipping at any angle. The numerous coal quality values can be incorporated to aid the optimization of the economic pit limits and yearly scheduling.

Jan 1, 1978

By Frank H. Madison

The percentage depletion deduction on Federal Income Tax Returns under the provisions of the 1939 Internal Revenue Code and of Sections 611 to Section 615, inclusive, of the revenue act of 1954, have created innumerable administrative difficulties, and a new interpretation of "gross income from the property" in that the Courts have expanded the ideas of what constitutes "gross income from the property" to a degree unheard of and unthought of prior to the enactment of these two codes. Originally, under the Revenue Acts of 1917, 1918, and 1920 depletion was allowable, based upon mine valuations as of March 1, 1913; if the mine was owned prior to March 1, 1913; upon cost, as of the date of acquisition if purchased subsequent to March 1, 1913; and upon a "discovery" basis if the mine was discovered after March 1, 1913, The "jab" for mine valuations as of March 1, 1913 and for discovery valuations and depletion was not as bad as it has been made out to be. Thousands of valuations and estimates of reserves were made and agreed upon between taxpayers and Internal Revenue Service engineers and as the years went on the answers have been found to be "reasonable." However, human nature being what it is each case was a battle of wits - of a sort - and many resulted in severe differences of opinion and litigation. As tax rates increased the situation was not bettered. I could talk for several hours on this phase of depletion but it is all past now andwould not give any real service or better understanding of the matter.

Jan 1, 1958

Computer programs commonly used to simulate mining operations generally require a fair amount of data. The common data input methods have been by either creating an ASCII data file or answering numerous questions during the data input phase. Both methods of data entry are tedious, time consuming, and inflexible. A screen handling system has been developed to drive FORTRAN-77 application software for the MS-DOS environment. The system utilizes keyboard functions with an aid of extended ANSI codes. It also allows a multi-view input data entries.

Jan 1, 1990

By V. R. Degner

The minerals industry trend toward very flotation machines, exceeding 10 m3, began in the late 1960's and responds to the continuing desire to achieve better plant economics through improved plant floor-space utilization, power requirements, and operational /maintenance manpower heeds. In general, as process design tonnage increases, the benefits of the larger flotation machine becomes more evident. The development of the larger flotation machine can be distingushed from earlier, smaller, machines in demanding a rational "scale-up" procedure to guide the basic design, thereby producing a machine prototype capable of satisfactory-operational evaluation at minimum cost. Proven flotation machine "hydrodynamic" scale-up consideration, successfully applied in the development of both the WEMCO No. 164 (28.3 m3) and No. 190 (42.5 m3) machine will be reviewed, and the resulting economic benefits of large flotation machines in high tonnage applications will be summarized.

Jan 1, 1985

By W. Stark

Many developing countries with little or no previous environmental regulation are now promulgating air quality regulations which require facilities to demonstrate compliance with both process parameter based emission limits and ambient air quality standards. For many companies with operations in developing countries, an air quality compliance program at the facility level is lacking and these companies have very little background information to work with in developing a program for assessing and maintaining compliance. This paper will present a methodology for development of a comprehensive air quality compliance program for operations located in developing countries with new environmental regulations. The experiences of the authors in developing an air quality compliance program for a mining operation located in South America will be used as a basis. A program for meeting new air quality requirements can be developed in seven steps. The seven steps are: (1) regulatory review and project scope; (2) design and implementation of a baseline air quality monitoring program; (3) site visit, (4) development of a complete air emission inventory; (5) dispersion modeling; (6) compliance analysis and compliance plan; and (7) project completion.

Jan 1, 1998

By Ashish Ranjan Kumar, Barbara Arnold, Luis Sanchez Gonzalez

Mining operations adopt a variety of measures to combat dust underground. These include ventilation systems, water sprays, physical barriers, and personal protective equipment (PPE). Respirators are a class of PPE that can provide clean particulate- free air to the users. Powered Air-Purifying Respirators (PAPRs), used commonly in medical and other sectors, are not prevalent in the mining industry. PAPRs use P100 filters that have 99.97% dust capture efficiency. We present our results from computational fluid dynamics (CFD) simulations performed to understand the impact of a PAPR on airflow and dust particle concentration in the vicinity of a miner. These results show that donning PAPRs can lower the miners’ exposure to respirable coal dust in their workplace.

Feb 1, 2025

By Moussa Wone, Jeff Peterson, Filippo Azzarà, Daniele Nebbia

The DC Water and Sewer Authority's Long Term Control Plan includes tunnels, sewer separation, pumping station rehabilitation and green infrastructure to reduce combined sewer overflow (CSO) discharges to the District waterways. The Northeast Boundary Tunnel is a deep, large sewer tunnel that will reduce CSO discharges; signifi- cantly mitigate known chronic flooding in the Northeast Boundary drainage area and improve the water quality of the Anacostia River. This paper presents the unique combination of Owner and Contractor perspectives of the entire Project from conception through procurement, execution, and contract management, providing lesson learned, chal- lenges encountered, and solutions implemented to deliver the Project successfully.

Jun 23, 2024

By J. J. Pavlica

Grinding in steel mills adversely affects the flotation removal of pyrrhotite from magnetite ores. To elucidate the effect of grinding media on the floatability of pyrrhotite, rest potential and short-circuit current measurements were made on electrode combinations of pyrrhotite-mild steel and pyrrhotite-stainless steel. Galvanic contact of pyrrhotite with mild steel increased the rate of surface reactions on pyrrhotite in air-exposed and oxygenated solutions. It was postulated that the formation of ' an iron hydroxide coating on the pyrrhotite adversely affected its floatability. Its formation was minimal when pyrrhotite was contacted with stainless steel. Fine magnetite particles caused slime coating on pyrrhotite surfaces by magnetic interaction and impaired the flotation of pyrrhotite.

Jan 1, 1982

By R. E. Hamilton

Automation is a word whose meaning has been broadened by popular usage to include any labor saving device. We with restrict our usage to the replacement of human judgement by instrumental measurement and mathematical analysis in the control of industrial processes. Mineral concentration is an area which has resisted automation because of the great difficulty in developing measuring instruments which can exist in the rugged environment and can measure useful properties with acceptable accuracy. This is not the only factor limiting progress, but until recently it has been of over-whelming importance. The development of on-stream X-ray analysers, magnetic flowmeters and nuclear density meters for mineral slurries has eliminated this obvious barrier and is enabling us to locate and attack the less obvious problems which still limit our ability to automate concentrators. If we examine the history of automation in industries which are highly automated we find that it has usually gone through three distinct phases. The first phase has been regulation. This is the simplest form of control and involves manipulating some variable whose value is of no importance in order to maintain the value of some other variable which is important at a constant specified value in spite of disturbances which may occur in other variables which affect it. A simple example is the use of a control valve to maintain a constant flow of fluid in a line in spite of changes in pressure in the vessels at the ends of the line. The position of the valve stem is of no consequence, as long as it is within its operating range. Unfortunately we soon run out of variables which can be

Jan 1, 1971

This paper presents the results of column flotation of a fine feed sample of Florida phosphate. A central composite design is used to study the main and interaction effects of parameters affecting column efficiency. The statistical design is also used to determine the optimum conditions. The results indicate that, depending on the experimental conditions, it is possible to achieve a concentrate of high grade and recovery. A concentration of 15 ppm of non-ionic frother is found to be enough to maximize the recovery at the pH of 9.5.

Jan 1, 1999

By R. Asamoah, P. Forson, W. Skinner, M. Zanin

Despite the seeming benefits decoupling pyrite and arsenopyrite minerals present in practice, little success has been achieved. The present study presents possible process routes for attaining selective flotation broadly capitalizing on differential oxidation between these minerals, and the use of a chelating collectors. The best performance was achieved with dithionocarbamate application following copper activation, yielding 81.4% arsenopyrite and 37% pyrite recovery. Preaeration followed by staged addition of xanthate produced 76% arsenopyrite and 31% pyrite recovery while reverse flotation of pyrite after H2O2 addition gave rise to rejection of 66% pyrite accompanied with 24% arsenopyrite.

Mar 2, 2022

By D. G. Krige

I read the paper “The jackknife approach” with interest. There appears to be a widespread misunderstanding of the kriging variance as a measure of the error variance of the kriged grade estimate of an ore block. Virtually all mineral deposits display skew frequency distributions and are subject to the well-known proportional effect. Thus, it is usual to find in an ore body, when subdivided a really into subpopulations, that the variances of the grades (or the total sills of the variograms) for the subpopulations will be correlated with the corresponding mean grades (usually linearly with the squares of the mean grades). Thus, the variogram will be stationary.

Jan 1, 1996

By M. F. Goodrich

The concept of using water-only cyclones as a clean coal scalping device preceding a heavy media cyclone circuit shows considerable promise, as it can considerably reduce the feed to the heavy media cyclone circuit. The system will not perform as well as a heavy media cyclone circuit alone, but the resultant loss in yield is small and may be negligible under some conditions. The concept of water-only cyclone scalping has previously been suggested by others. By reducing the amount of raw coal to be processed in the more expensive circuits overall capital and operating costs may be reduced. There are a few commercial plants with circuits operating on this concept. In the Warwick and Rowland plants water-only cyclones are used to scalp the feed to a heavy media vessel and Deister tables respectively while Amherst Coal Company's McGregor plant uses them to scalp the feed to a heavy media cyclone circuit. The system was evaluated on a technical basis, both from a theoretical viewpoint and by analysis of a computer simulation, in order to gain a fuller understanding of its usefulness and limitations.

Jan 1, 1977

By Anna Gustafson, Sohail Manzoor, Håkan Schunnesson

Sublevel caving operation relies on the estimation of ore grade at drawpoints, as the mine management uses grade to decide whether the material at a certain ring should be loaded or abandoned. Grade is estimated in various ways, including visual estimation, density-based calculation, and sampling and assay methods. The grade estimation at the world’s two largest underground iron ore mines owned by LKAB in northern Sweden is based on the density difference between ore and waste. The calculations assume a constant swell factor, a theoretical fill of 100%, and a linear relationship between bucket weight and material grade. This study evaluated these assumptions in detail based on the loading data for 12,237 buckets and concluded that the method has some shortcomings which render the assumptions invalid. Further research is required to deal with these shortcomings to improve estimation of the material grade.

Oct 17, 2022

By Alen Shibu Joseph, Arvind Rajnarayan Singh, Mudila Dhanunjaya Rao, Kamalesh K. Singh

In this article, the cementation of major impurities from zinc sulphate leach solution by the addition of zinc dust was studied by considering different parameters including time, mesh size, and percentage of excess zinc dust. The output obtained from various experiments was utilized for the design of experiments. A multi-level categorical factorial design with a quadratic model was employed during this study. Results were predicted to minimize the concentration of impurity metals in the solution by altering the parameters. Furthermore, these predicted results were validated by performing another experiment. Successfully, it showed that the predicted and experimental data values were close to each other. The predicted optimized values were 40 min, 100% excess zinc dust, and 300 mesh size for copper; 42 min, 100% excess zinc dust, and 300 mesh size for cobalt; 37 min, 100% excess zinc dust, and 300 mesh size for cadmium; and 34 min, 100% excess zinc dust, and 300 mesh size zinc dust for nickel. At these optimized values, the experimental results showed 99.99%, 55.7%, 99.6%, and 76.6% cementation efficiencies for copper, cobalt, cadmium, and nickel respectively. The statistical design of experiments for the effective cementation of impurities corroborates the economic feasibility of optimizing parameters for the proposed process.

Jul 18, 2022

By E. Baliktsis

PPC (Public Power Corporation) operates a new power plant at the South-West part of Crete. Recently the extension of the Power Plant started. ATHENA SA the main contractor of the project assigned to EXORIXI SA the implementation of a blast vibration monitoring program and prevention-evaluation of risks caused by construction blastings inside or very close to the operating part of the power station. The blasting parameters and characteristic elements that had been evaluated, the measures that had been taken and materialized, the overall risk management and the results of the whole program are presented in this paper.

Jan 1, 2006