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By T. M. Gurr

In response to concerns voiced by local, state, and federal agencies and various environmental groups, the Central Florida Phosphate Industry and various governmental agencies have been investigating methods to accelerate the consolidation of waste clays generated during phosphate washing and beneficiation processes. The objectives of research efforts have been to reduce the storage volumes required for clay waste, accelerate reclamation and to return the land to approximate pre-mining topography. Government and industry research to accelerate waste clay consolidation has evolved two general methods: gravity thickening and chemical flocculation. Gardinier, Inc. one of the phosphate mining companies, evaluated the use of synthetic (polyacrylamide) flocculants as an alternate waste clay thickening method in response to mining conditions encountered at their Fort Meade Mine and the proposed North Hardee County extension of the Fort Meade mine (Figure 1). After considerable research and evaluation, the Alsthom-Atlantic Clariflux Super-flocculation method was chosen by Gardinier, Inc. as a method to seriously consider for use at their Fort Meade mine.

Jan 1, 1986

By M. D. Ross

Complex combinations of technical, economical, safety and environmental factors are causing mining engineers everywhere to review their operations. Naturally, some of the traditional methods still have a large role to play because they are, in certain circumstances still adequate and are well understood. But, as circumstances change, a new approach is required. The combination of technical and economical reasons for introducing Long- wall mining in some seams in the United States is associated with strata control. Other reasons include simplifications and improvement of ventilation, reduced coal dust, more output from each unit and crew, increased percentage of recovery from each area of the coal deposit, and reduction of rock dusting. The innovations which transformed Longwall mining from a cyclic to a continuous mining system were the armored conveyor and power loading machines, but the crucial breakthrough for application to high production was the development of the powered roof support, which at once gave the system the advantages of mastery of strata control, increased rate of advance, significant reduction of manpower, and increased safety.

Jan 1, 1974

By C. E. Jordan

Direct digestion of phosphate ores by the acid-alcohol method offers improved leaching selectivity for the exclusion of iron and aluminum in the product acid. The leaching kinetics of this process will have a major role in the eventual application of this technology. The Bureau of Mines investigated apatite dissolution to determine the reaction rate and mechanisms of the leaching kinetics. The dissolution kinetics were monitored on various sized fractions of pure apatite. The "shrinking-core" kinetics model was applied to the data to determine the rate controlling mechanisms. For each size fraction, the initial reaction rate was controlled by the dissolution reaction. After an hour the dissolution rate slowed indicating a diffusion controlled reaction caused by the formation of calcium sulfate hemi-hydrate coating on each particle. For complete dissolution of the apatite, the phosphate rock should be ground to near 10 µ m size.

Jan 1, 1993

By G. D. Hood

The U.S. Bureau of Mines investigated rapid froth flotation through the use of more efficient bubble-particle collisions that improved the overall flotation kinetics. An in-line static mixer efficiently mixed the air bubbles, water, and ore, rapidly attaching the hydrophobic mineral to the bubble surface. As the mixture entered the flotation chamber, the hydrophobic mineral was already attached to the bubbles and was quickly floated away from the remaining ore pulp. A rougher concentrate containing 4.5 pct copper was obtained from a western porphyry copper ore containing 0.67 pct copper. Over 99 pct copper was recovered from the ore at a rate 7 times faster than conventional flotation.

Jan 1, 1991

By Thomas S. Mackey

The industrial types, sources, and quantities of USA tin residues are identified and the methods of treatment reviewed. The effect of a lower tin price, due to a current major world surplus of tin metal, is mentioned and covered in some detail. The names and locations of over 100 USA firms recovering tin residues are listed. Current smelting and refining charges are included to convert the residues into tin metal and alloy. The impact of the suspension of the LME daily tin price since October 24, 1985 to date, and the failure of the International Tin Council to support the Buffer Stock Manager are reported with comments.

Jan 1, 1986

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 Alex Stewart

Most iron bearing ores treated by the R=N Direct Reduction Process yield products lower in phosphorus than the initial ores. The sulfur is also removed and generally is in the range of 0.02 to 0.05 percent in the final R=N product, independent of the sulfur content of both the ore and carbon fuel used. The mechanism and thermodynamic justification of the principal reactions leading to the removal of both phosphorus and sulfur and the control of sulfur in the iron concentrate produced are discussed and supported by the results of laboratory experiments. In substantially all iron ores (containing up to 4% sulfur as sulfate) and solid carbon fuels (containing sulfur from 1 to 8%) tested, the rejection of sulfur has been in the order of 90-95%, with not more than 0.02 0.05% sulfur in the final metallic iron product. With respect to phosphorus-bearing iron ores ranging up to 0.70% P205, the rejection to tailings has been in the order of 70-95%, resulting in not more than 0.03 - 0.07% phosphorus in the final product.

Jan 1, 1958

By P. Somasundaran

Flotation of oxide minerals is controlled by a number of factors, such as surface potential and solubility of the mineral, concentration and type of various inorganics, properties of the collector, pH, ionic strength and temperature. The role these factors play depends on the mechanisms of adsorption of the collector inorganics or polymer additives. The major mechanisms include electrostatic interactions, chemical adsorption, chain-chain interaction between adsorbed collector species and modifications of the surface by inorganics. In real systems, flotation is, however, markedly affected by various other processes, including aging of the minerals, surface precipitation of the collector on the mineral and associative interactions between various collector species leading to highly surface active, for example, ionomolecular complexes. These effects are reviewed here with selected examples.

Jan 1, 1999

By William J. Shampine

The Floridan aquifer, which underlies all of Florida, yields water with a hardness of less than 180 pmts per million (ppm) in the northwestern part and throughout much of the center of the Slate. In most of the rest of the Stale, the aquifer yields water having a hardness greater than 180 ppm and as much is 1,900 ppm. Hardness of ground water is caused by dissolved salts from the geologic formations through which the water passes or by direct pollution. Sometimes pollution may indirectly increase the hardness of ground water by increasing the acid content and thus increasing the solution of calcium and magnesium salts. Water from deep zones of the aquifer lend to he harder than water from more shallow zones. Only the hardness of water from the upper part of the aquifer is shown.

Jan 1, 1966

By Edward T. Koch

With the dramatic increase in world demand for basic raw materials, open pit mining is proceeding at an unprecedented rate. A viable demand is the ever tempting Siren's song for increased production or new facilities. When the Siren's lure is viewed against the panorama of today's world economic milieu the concomitant Scylla and Charybdis are seen in the form of high capital cost and high operating cost. If the economic realities of present day open pit mining are to show a proper return on investment, a clear and penetrating eye must be cast upon the area of mine planning. This paper deals with the problem of overburden removal. In almost every open pit mining operation overburden removal is a significant part of the capital cost and operating cost of the total operation. This paper deals with a new and unique method to affect economical overburden removal. Well known to all are the parameters surrounding draglines, shovels, and bucket wheel excavators. All of these machines require a reasonably stable soil to support them and the shovel and bucket wheel excavator require a reasonably stable bank in which to operate. Their reliability, portability and rate of production per dollar of invested capital are good.

Jan 1, 1975

By George M. Hamilton

The gas producer actually dates back far beyond the period from which we first find recorded data. A partial production of producer gas can take place in any type of solid fuel grate equipment, such as a boiler, or even a fireplace if a sufficiently deep fuel bed is provided. Those of us who have watched a coal fire burning in the hearth, have no doubt noticed at times, the gases liberated by the heat burning on or near the surface of the fuel bed. So far as we know, the first gas producer was built by Bischof in Germany in 1839, followed by Ebelman in France in 1840, and Ekman of Sweden in 1845. The first large industrial development in the use of gas producers was When the two Siemens brothers of Germany patented their first combined gas producer and regenerative furnace in 1861, thus opening up the field for the use of raw, crude producer gas in heavy furnace work. In the years 1879-1881 J, E, Dowson, of England developed a producer gas cooling and cleaning plant, which extended the scope of application of producer gas to make possible its use in small furnaces and gas engines.

Jan 1, 1961

By S. Usui

In a previous article1 the methyl stretching vibrations for a series of xanthates and amines were reported, and the frequency of the methyl stretching vibrations in a homologous series of the alkyl compounds were shown to decrease exponentially with chain length and approach a limiting value corresponding to that of saturated hydrocarbon beyond six or seven carbons. These observations were explained quantitatively by the theory of Goto and Takenaka2 who proposed an equation relating the frequency shifts to the inductive effect of polar groups. As a result, the alkyl groups in the shorter chain heteropolar compounds were interpreted as becoming somewhat polar, and a good correlation was observed between the CH3-stretching frequencies and such surface chemistry parameters as contact angle, surface tension lowering, solubility, and critical micelle concentration" The substitution of fluorine atoms, the most electronegative of all atoms, for the hydrogen atoms in alkyl groups was expected to reverse the direction of the inductive effect within a heteropolar molecule, and its effect on the C-F stretching frequency shifts and on some surface chemical properties became of interest. In a recent study the C-F stretching frequencies of a series of normal perfluorocarboxylic acids and a few 1,1' -dihydroperfluoro alcohols were determined as a function of chain length and the results were compared with the corresponding hydrocarbon analogs. Furthermore, the nature of the induced polarity in the hydrocarbon and fluorocarbon groups was investigated through surface potential measurements at the interfaces of air-aqueous solutions of normal butyl alcohol and of l,l'-dihydroperfluorobutyl alcohol and through differential capacity and electrocapillary measurements at the interfaces of mercury-aqueous solutions containing the above two alcohols. Experimental Normal perfluorocarboxylic acids and 1,1' -dihydroperfluoro alcohols were provided through the courtesy of the 3M Company, St. Paul, Minnesota. Normal butyl alcohol was purchased from Distillation Product Industries, Rochester, New York. A Perkin-Elmer Model 621 infrared spectrophotometer was used to investigate the spectra in the frequency region of 1200 to 1270 cm-l with frequency scale

Jan 1, 1971

By Ronald M. Tipton

Freeze and thaw deterioration is a serious problem In con¬crete pavements. The main cause of distress Is thought to be the pore structure of coarse aggregate. In an attempt to characterize deleterious pores, the Iowa Pore Index test and the Expected Durability Factor, as Calculated from the mer¬cury intrusion porosimeter, were devised. This study Included freeze-thaw and sodium and magnesium sulfate soundness testing of sixteen carbonate aggregate samples. In addition, the Iowa Pore Index and the Expected Durability factor were determined for each of the samples. All of the Above mentioned physicochemical parameters were examined using bivriate correlation analysis with the In¬tent to evaluate the effectiveness of the Iowa Pore Index and Expected Durability factor for predicting the frost dur¬ability of an aggregate. The results from the bivariate correlation analysis showed no significant correlation, between the Iowa Pore In¬dex And- Expected Durability factor with the other physico¬chemical parameters investigated. Rust interesting is that the Iowa Pore index predicted that All of the tested samples would resist freeze-thaw failure, whereas the Expected Durability factor predicted that -ash sample would he non-durable.

Jan 1, 1987

By J. C. Heter

Industrial Mineral Fillers, LLC. is in the initial stages of mining and processing Anorthosite (CASPAR TM) at its CASPAR mine located in Soledad Canyon, Los Angeles County, California The CASPAR is being mined from the Precambrian San Gabriel Anorthosite Complex of the western San Gabriel Mountains. Preliminary results suggest that CASPAR is a desirable alternative to silica sand used in construction applications, such as, stucco, grout, abrasives, and other uses including filtration and golf course recreation sands. With the use of standard ore dressing techniques, CASPAR is suitable for use as a filler in paint, plastics and rubber. Environmentally, CASPAR has advantages over silica sand, in that, there is no detectable Free Silca.

Jan 1, 1997

By L. R. Berry

The successful selection of a slurry pump depends on the accuracy and completeness of the information provided for the application. Inaccurate or incomplete information can result in incorrect pump selection and / or operational problems. Some information is more critical to the selection process than other information. A full description of the slurry (liquid -solid mixture) including the particle size distribution and maximum concentration, the flow, head and NPSH requirements are most important for successful slurry pump selection and operation. Common problems resulting from improper slurry pump selection will be discussed to illustrate the need for correct selection requirements.

Jan 1, 1996

By Ronald H. Mullennex

The growing need for development of thinner, more erratic, or less easily- mined coals in the Appalachian region requires more detailed analysis of conditions and factors controlling or influencing deposition of these seams. The value of depositional modelling in evaluation of such coals has been demonstrated in many recent studies and publications. Such modelling may be applied to allow prediction of factors varying from regional coal occurrence trends to very local areas of seam discontinuities, but requires thorough utilization of all available types of data. Mapping of general depositional energies, as derived from basic geophysical and driller's logs, can be applied to specific prediction of coal occurrence, and projection of particular facies as representative of unique depositional features or conditions often proves more applicable to coal character delineation than does mapping of the coal itself. Depositional modelling and trend projection may also serve as a guideline in reserve classification and confidence-levels in reserve estimations.

Jan 1, 1981

By Robert A. Jankowski, Charles A. Babbitt, Natesa I. Jayaraman

The U. S. Bureau of Mines, through a contract research program with Foster-Miller, Inc., has identified guidelines for the selection of the most effective water spray system and water flow rates for use on continuous mining machines. Specifically, these parameters were modified to obtain maximum dust control with regard to quartz dust exposure and more stringent respirable dust standards due to quartz. A novel water spray system, consisting of flat fan spray nozzles, mounted across the top of the mining machine, along with high flow, flat fan and higher pressure hollow cone nozzles mounted under the boom has been identified and tested. The anti-rollback/underboom spray system minimizes dust rollback while increasing dust knockdown by its unique positioning of spray manifolds and orientation of spray nozzles. Respirable dust suppression characteristics of the system acted in three ways: - by wetting the surface of the broken coal material to prevent dust from becoming airborne; - by controlling the airflow pattern at and near the face to minimize dust rollback to the operator Is control location; and - by dust knockdown, i.e., airborne capture, or scrubbing of airborne dust from the air. During underground trials, the anti-rollback/ underboom spray system reduced dust levels at the operator's position and in the immediate return by 55 and 15 pct, respectively, when compared to a conventional spray system. Quartz dust levels at the operator '8 position were essentially eliminated, while quartz dust levels in the immediate return were reduced by 57 pct. Applying the concepts of this technique throughout the mining industry should reduce the health hazard associated with excessive exposure to respirable quartz dust, as well as allow coal mine operators to comply with the associated, more stringent, respirable dust standards.

Jan 1, 1987

By Leonard H. Hoyle

The American Society of Association Executives is a professional society composed of nearly 10,000 individuals who serve as salaried executives on the staffs of more than 6,500 associations. Represented is the full range of international, national, regional, state and local associations...including trade associations, professional societies, philanthropic organizations and others. The dramatic growth of ASAE during the past 15 years is a manifestation of the growth of the association movement during the past two decades. This is not to imply that associations are a new phenomenon, because they have existed for thousands of years. Ancient civilizations show evidence of groups formed for mutual protection and advancement. In the transition from ancient to medieval time, trade associations and guilds came to serve an important function for the craftsmen and merchants they represented, encouraging the growth of new industries, improved processes and education.

Jan 1, 1981

By J. Douglas

The past year has been a strange one for the fertilizer industry of the world and the United States. Listening to news stories, you would think the sky is falling on the world's agriculture and probably conclude that we should have had an exceptionally poor fertilizer season. In some respects, we did. Prices were low, profits were low, and in some cases nonexistent, but volume was good. We heard much in the press about the farmers' credit crunch. The truth of the matter is that only 6.6 percent of the U.S. farmers have debt-equity ratios of 70 percent or more, and a large percentage of our farmers have absolutely no debt but operate entirely on their own cash assets.

Jan 1, 1985

By M. Z. Rashad

The purpose of this work is to determine the influence of sample length or size on the value of variance (Semi-variogram) to select the suitable length that is required to the geostatistical computations of ore evaluation. Three cases in Ghorabi Iron Ore were studied. The first one was on the iron fraction (Fe\) at which the semi-variogram gave an evidence to good continuity of the fraction in the ore. In this case, the length of sample has not important influence. The second case was for the Mn\ component of the same area where the semi-variogram has a nugget effect. The selected length for this case was 4 meters. The Cl fraction of the ore was the third case where the anisotropic phenomena was appeared and the suitable length is 3 meters.

Jan 1, 1992