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By Craig E. Burson

This paper discusses the relationship between frother types and coal flotation as a function of particle size. It has been found that each frother has a unique size fraction that it will float effectively. This fact is very important when it comes to selecting a reagent scheme that will provide maximum recovery of both coarse and fine particles. Improvements in recovery can be attained when the chemical relationships between frother type and particle size floated are understood. Data from plant evaluations using commercial and developmental frothers are presented to verify the importance of frother types versus size fraction floated.

Jan 1, 1987

By M. G. Ayat

I have been following the discussions on coal degradation started by the article "Degradation process in coal slurry pipe-lines," by M.G. Ayat and B.C. Scott. I agree with Mr. Dasher's comments in January that the title of the article was perhaps misleading as the information appeared to pertain more to processing the coal than to transportation. Specifically, the authors' conclude that the cyclone had an important impact on the degradation. Dr. Ferri's comments on degradation in other physical processes was very correct, handling of coal in a turbulent manner has an impact on the size distribution of the coal. This is one reason that when I design a coal system (mine to rail car) I try to minimize the total number of transfer and processing steps consistent with achieving the desired product specifications. Another area, mentioned in passing in the article, the impact of natural causes and the mining step, is of particular interest to me. A mine in West Virginia had a variation of 50% in the -6.35 mm (-0.25 in.) raw coal depending upon the direction of mining. Since it was a single unit mine, this significantly impacted the final product. Two articles on mining's impact on size distribution are: • Stefanko, R., Chopra, I. K., and Ramani, R. V., 1974, "Mining influence on size consistency and washability char¬acteristics of coal," SME Fall Meeting. September; and • Albrecht, M., and Olsen, D., 1980, "Mining methods impact on coal preparation plant design." 1st International Mine Planning and Development Symposium. September. Both articles presented information on variation of size distribution and cleaning plant performance on a coal depending on the mining method used. Both articles considered a single coal seam at one mining operation. Stefanko's article considered continuous and conventional mining of coal in Pennsylvania. Albrecht's article considered surface, underground continuous, and underground hydraulic mining of a coal in British Columbia. Both concluded that mining methods do impact coal characteristics. I agree with Mr. Ayat's comments in reply to Dr. Ferri's discussion, "... degradation is a multi-faceted phenomenon involving many natural and man-made factors." As efforts are being made to produce a higher quality (lower sulfur) coal, this topic becomes even more important

Jan 1, 1990

By Bo Hyun Kim, Mark K. Larson

Researchers at the National Institute for Occupational Safety and Health have tested the finite element code, UT3PC, with LaModel to evaluate their results using know case studies. The purpose of the testing was to demonstrate the usefulness and limitations of these programs in evaluating mine layout design. Both of these software packages are simple to use and free for public download. Their use by mine engineers, along with other tools, such as empirical methods, can enhance the assessment of a mine layout design. LaModel can model mining layout on a mine scale or, at least, on a multiple-panel scale. However, this software has limitations in calibrating to conditions at many coal mines in the western United States. The UT3PC software models smaller parts of a mine and is used to evaluate the design of pillars, shafts, or drifts; but the software calculates all components of the stress tensor and provides stresses, displacements, and safety factors throughout the model volume. The two codes are used to evaluate design of one known case, and UT3PC is used to evaluate another case. The results and approaches demonstrated in the testing are intended to aid mine engineers in evaluating site-specific problems and to show that these tools can provide useful information to the mine engineer in evaluating mine layout design.

Jul 1, 2023

By M. Albrecht

I have been following the discussions on coal degradation started by the article "Degradation process in coal slurry pipe-lines," by M.G. Ayat and B.C. Scott. I agree with Mr. Dasher's comments in January that the title of the article was perhaps misleading as the information appeared to pertain more to processing the coal than to transportation. Specifically, the authors' conclude that the cyclone had an important impact on the degradation. Dr. Ferri's comments on degradation in other physical processes was very correct, handling of coal in a turbulent manner has an impact on the size distribution of the coal. This is one reason that when I design a coal system (mine to rail car) I try to minimize the total number of transfer and processing steps consistent with achieving the desired product specifications. Another area, mentioned in passing in the article, the impact of natural causes and the mining step, is of particular interest to me. A mine in West Virginia had a variation of 50% in the -6.35 mm (-0.25 in.) raw coal depending upon the direction of mining. Since it was a single unit mine, this significantly impacted the final product. Two articles on mining's impact on size distribution are: • Stefanko, R., Chopra, 1K., and Ramani, R.V., 1974, "Mining influence on size consistency and washability characteristics of coal," SME Fall Meeting, September; and • Albrecht, M., and Olsen, D., 1980, "Mining methods impact on coal preparation plant design," 1st International Mine Planning and Development Symposium, September. Both articles presented information on variation of size distribution and cleaning plant performance on a coal depending on the mining method used. Both articles considered a single coal seam at one mining operation. Stefanko's article considered continuous and conventional mining of coal in Pennsylvania. Albrecht's article considered surface, underground continuous, and underground hydraulic mining of a coal in British Columbia. Both concluded that mining methods do impact coal characteristics. I agree with Mr. Ayat's comments in reply to Dr. Ferri's discussion, "... degradation is a multi-faceted phenomenon involving many natural and man-made factors." As efforts are being made to produce a higher quality (lower sulfur) coal, this topic becomes even more important

Jan 1, 1989

By Edwin R. Phelps

Good morning ladies and gentlemen - today I am in an enviable position for two basic reasons - No. 1, since I am first on the program, the audience should start out awake because those that partied too much last night are still asleep, but in their room, not here. No. 2, since copper, iron, and mining technology are not competitive, the veracity of my statements will not be questioned. Most such meetings I attend are based on the subject of energy and the coal industry does have competition from oil, gas, hydro, and nuclear. However, to counteract this advantage I am the usual engineer with a limited vocabulary by schooling, and the remaining vocabulary almost completely eliminated due to the presence of ladies. In relation to the past of the coal industry, we have not only suffered the competition of other energy sources mentioned before, but in addition have in the last 25 to 30 years been required to meet the demands of a vastly changing market. To explain this statement, I am sure many of you can remember 30 to 40 years back when most homes were heated by coal furnaces or stoves and shudder to recall the shoveling of coal into the fire and the carrying out of ashes with the attendent manual labor dust. Now this space heating portion of our sales has almost become non-existant due to an almost universal switch from coal to natural gas, oil, and electric heating. Actual figures show a decrease from 119 million to less than 28 million tons per year in less than a twenty year span. Also, most of you can remember the coal burning steam locomotives and the tremendous volume of coal they consumed and then the very rapid change to the diesel-electric locomotives, incorporating improved large diesel engines driving D C generators and electric drive motors, which resulted in cheaper motive power. This change over was so complete that the annual tonnage of coal dropped from 125 million to less than 2 million tons in 15 years. 'Actually, now it requires some considerable interrogation and traveling to find a locomotive still operating on steam.

Jan 1, 1968

By Manuel Viveros J.

This paper will deal with the type of rocks so called evaporites, which are sedimentary rocks produced by water evaporation from seas, lakes or marginal lagoons, in warm and arid climates. Salts derived from these deposits are precipitated according to their solubility; that is, the more soluble precipitates first, overlain by other sediments like silts, shales, limestones, sands, etc. The most common evaporites, according to their chemical composition, are : Chlorides Sulphates Carbonates Nitrates Borates Common salt, or halite, sulphates like anhydrite and gypsum, are the most important. Potassium chloride (silvite and carnalite) and potassium sulphate are of great commercial value.

Jan 1, 1974

By R. Bruce Sheibach

The Picher Mining District, located principally in north-eastern Oklahoma, was one of the world's largest lead-zinc mining areas during its 55 year life. The field covers an area of approximately 72 square miles (186 km.-); an estimated 1.6 x [103 yds3 of material (1.22 x 103m3)] worth in excess of one billion dollars, has been mined. Mining activities were typified by surface exploratory drilling identifying ore distribution and extension of underground workings to the lead and zinc deposits outlined. Exploration holes were either left unplugged or plugged at the surface with a section of a telephone pole. Low grade ore and waste rock were discarded in mined out portions of drifts. These waste piles containing pyrite and marquisette were left underground and oxidized during the many years of active mining. Upon cessation of mining activities in the mid-1960's, the drifts and shafts of the abandoned workings began to flood as the cone of depression filled in, leading to the dissolution of the oxidized sulfides and the formation of large volumes of acid mine water in the mined out openings. The resulting poor quality water, with high concentrations of cadmium, iron, lead and zinc, began discharging at the surface in 1979. Contamination of the underlying aquifer supplying local residents was first detected on a localized scale in 1980. The present surface water and ground water contamination have lead to the area being classified as one of the top ten hazardous waste sites in the U.S. by the EPA under the superfund program.

Jan 1, 1982

By R. A. Deju

The Basalt Waste Isolation Project of the U.S. Department of Energy is a part of the National Was re Terminal Storage Program. Its mission is to assess the feasibility of siting a nuclear waste repository in the basalt formations which underlie the Hanford Site of the U.S. Department of Energy. The progress in all program areas is summarized in this paper. Activities conducted to date have led to the identification of possible repository candidate sites within the Hanford Site.

Jan 1, 1981

By Robert L. Grayson

An application of goal programming (GP) in evaluation of proposed purchases of major mining machinery is presented. It incorporates historical operating data compiled on mechanical delays to production time. The goal programming technique, which is an extension of integer programming, is used to maximize an objective function. The objective function combines the capital budgeting evaluation methods of net present value, payback period, profitability index, and total net earnings as goals weighted according to a management preference. The GP method gives an optimal solution to a multiple-goal problem. A sensitivity analysis is performed to determine the effect of an increased production forecast or a tightened budget on proposal selection.

Jan 1, 1982

By Douglas R. Cook

Our present and future needs for base and previous metals are not satisfied by the present rate of new viable discoveries. This deficiency can be met by increasing the number of competent exploration organizations and by doing a more effective job of prospecting. My principal purpose is to show that new discoveries can be increased by improving the use of exploration techniques in a concept-oriented exploration program. Exploration techniques are defined and classified. The effectiveness of many exploration groups can be improved by better definition of objectives and thorough planning of the exploration program. The role of objectives, planning, and the use of techniques are discussed within the scope of the exploration framework. Common pitfalls in the use of exploration data are identified such as: inconsistency of geologic measurements, negative use of data, indiscriminate use of geo-surveys, collection of irrelevant information, and the unrealistic desire for exploration panaceas. Suggestions for improving the use of techniques include the use of multiple-working hypotheses, improvements in the quality of exploration data, use of geology in the selection, planning and interpretation of geochemical and geophysical surveys, and the recognition of variables and limitations affecting the interpretation of exploration data. The critical role of geologic mapping by Federal and State agencies is mentioned for satisfying the continual exploration demand for better geologic maps and filling many gaps that currently exist. The importance of imaginative and qualified exploration personnel is discussed as well as the maximum utilization of their exploration creativity. The problem of integrating field studies, research and training at universities and research institutions is identified. The need for high-quality research in economic geology is emphasized especially the importance of reducing the steadily increasing gap between basic and applied research.

Jan 1, 1968

By Wendell R. Peters

Shallow underground voids resulting from early coal mining and other resource recovery activities over the past several decades are now being recognized as a significant cause of ground subsidence problems. Uncertain knowledge of abandoned coal mines also imposes potential hazards in current mining operations since water inundation or the release of methane gas is a serious hazard when mine excavation operations break into an abandoned mine. Requirements for detecting and mapping subversive man-made tunnels in previous work has led to the development of a surface- operated automatic earth resistivity survey system and associated computer data processing system for military applications. Field demonstration tests of this system have resulted in successful detection of tunnels at depth-to- diameter ratios greater than ten to one. Under the sponsorship of the Bureau of Mines, a similar high-resolution earth resistivity system was designed and constructed for use as a potential means of detecting coal mine workings. The hardware and software aspects of the new system are described together with applications of the method to the survey and mapping of abandoned coal mine workings. Field tests are presented showing the detection of both air-filled and water-filled mine workings.

Jan 1, 1981

By J. E. Russell

The purpose of this paper is to describe an independent study which forecasts Texas coal production, specifically for electric power generation. This study, extending to the year 2000, is justified on the following basis. Texas produces and consumes considerably more electric energy than any other state, has consistently high growth rates in the population and industrial sectors, and has large lignite reserves. Also, since recent forecasts have been criticized as overly optimistic, this study is timely when considering the long lead times required in obtaining new power sources. In the study demand for electric energy was assumed to rest on two dominant factors: 1) overall state of the Texas economy as measured by the Texas Gross State Product (TGSP) and 2) Texas population. Demand models were prepared and tested following a study of several options. A final linear regression demand model with time lags for the two variables was chosen on the basis of good correlations. On the supply side, uncertainties such as impact of nuclear sources, gas-fired cogeneration, and ratio of imported to lignite coal exist. These uncertainties were studied with high and low cases for effects on lignite. Finally a simple supply model was chosen. Results of the study indicate that lignite production in Texas will rise from the current (1984) 40 million tons per year (XTPY) to the range of 77 to 124 MTPY and more probably 100 HTPY in the year 2000.

Jan 1, 1984

By K. Verghese

Neutron capture prompt gamma-ray analysis provides the best method for on-line analysis of the elemental composition of large volumes of bulk material. This paper summarizes the Monte Carlo models which simulate the radiation transport within two such analyzer systems; namely, the borehole configuration and the conveyor belt configuration. The models are useful in the design optimization of the analyzer systems, in minimizing the amount of experimental calibration data for calibrating these analyzers, and in investigating the detection sensitivity for different elements. The computational scheme in these models is made extremely efficient by the use of various powerful variance reduction methods and by efficient data management. Experimental verifications of the two models carried out in the laboratory indicate very good agreement with the Monte Carlo results.

Jan 1, 1984

By G. Rinelli, Paul R. Jr. Smith

Preparation for flotation begins with dragline mining, pumping, washing, screening, and desliming. Slimes, nominally -150 mesh material, constitute large quantities of phosphate and water which are a disposal problem. Older techniques involve sizing at about 35 mesh for separate coarse and fine treatment. The plus 14 mesh fraction does not require concentration. Coarse treatment includes agglomerate spiralling, belt flotation, thickening, scrubbing with sulfuric acid, de-oiling for reagent removal, and cationic flotation of fine quartz. A recent trend is to screen at coarser than 35 mesh size and eliminate coarse particle treatment, sacrificing some grade of this product. Techniques for flotation concentration of the fine size fraction are discussed.

Jan 1, 1976

Tables

Jan 1, 1973

By Robert R. Munro

Traditional aggregate sources, that is the riverbeds, the alluvial fans, located relatively close to the developing urban centers are being foreclosed to mining. As the sand and gravel reserves are depleted, those production plants are unable to secure additional adjacent reserves and are being forced to close down. The sand and gravel industry, in many respects, is its own worst enemy. We promote development, we promote the paving of streets, the building of houses, and industrial and commercial centers, and because of economics, we tend to favor those developments located close to our operations. Thus, we encourage development by our neighbors who soon become our detractors. In general, urban development is not compatible with sand and gravel mining. The neighbors don't like the view of the pits or the quarries, they complain about the "dust", about noise, about trucking . . . in general, the neighbors are not happy being close to an aggregate source.

Jan 1, 1984

By W. Z. Choi

A model describing size reduction and mineral liberation during grinding has been extended to include multiple classes of composite particles. The majority of the model parameters have been directly determined using computerized image processing equipment to analyze the products from batch grinding tests. A coarse-grained sphalerite ore from Tennessee, representing a nearly ideal binary mixture of sphalerite and dolomite, has been used to experimentally validate the model for the case of dry, batch grinding. In all cases, excellent agreement has been observed between the model predictions and the experimental results.

Jan 1, 1986

By C. H. Pitt

A jet slurry apparatus has been constructed to test corrosive/erosive wear properties of grinding ball metal. Plain high carbon steel heat treated to a hardness of about 60 RC was used. Slurries of quartz and chalcopyrite ore concentrate were used as the jetting media. Weight loss due to pure corrosion was determined by the linear polarization technique and weight loss due to pure erosion was determined by jetting while cathodically protecting the sample. By comparing the total weight loss with the sum of the weight losses from pure corrosion and pure errosion it was found that there was a synergistic effect between corrosion and erosive wear. Erosive wear rates are given as a function of pH and mineral type.

Jan 1, 1984

By David W. Houston

The increasing energy crisis, coupled with stringent environ- mental regulations, has created new demands for high capacity materials handling systems with unit train transporting and continuing surveillance of quality control. Effective and efficient methods of material conveyance are through high speed, high volume conveyor belts with the monitoring of quality through the utilization of automatic sampling. When we speak of high speed, high volume belt discharges we are referring to speed ranges from 600 to 750 FPM and volumes as high as 5500 TPH. To achieve the optimum operating sampling system for high capacity belt discharges, it is imperative that two major design characteristics be investigated and evaluated; namely technical analysis of operating conditions through application of ASTM design criteria and practical experience in the selection of equipment and the design of related components. The task of obtaining a sample of reasonable weight to represent an entire lot presents a number of problems and emphasizes the necessity for using standard sampling procedures.

Jan 1, 1973

By Dennis C. Parker

The Porters Creek clay is mined for its absorbent properties. The formation is part of the Upper Mississippi embayment and is recognized in Alabama, Mississippi, Tennessee, Kentucky, Illinois, and southeast Missouri. Major minerals in order of abundance are Montmorillonite, Quartz, Illite, Kaolinite, and Chlorite. Mining consists of open pit operation utilizing track loaders or scraper. The clay is dried or hardened in rotary kilns and crushed to size by roll crushers. The clay granules are sized and air classified prior to storage for shipment or packaging. Granules are sold for pet absorbents, oil absorbents, anti-skid material, fertilizer, and pesticide carriers.

Jan 1, 1979