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By Thomas F. Stinson

Energy-producing states see severance taxes as attractive sources of increased revenues for otherwise tight budgets. Consumers in energy-poor states, however, protest that current rates are excessive and have moved to obtain a reduction. The US Supreme Court heard two cases questioning such taxes during its 1981 term, and Congress, in each of its last two sessions, has seriously considered measures placing a ceiling on severance tax rates. Although discussions usually focus on coal severance taxes levied by Montana and Wyoming, ramifications of changes in national policy are much larger, potentially affecting mineral taxes in all states. Severance taxes yield substantial revenues in some states, as illustrated in the accompanying table. In fiscal 1980, Texas collected more than $1.5 billion from such taxes, while Louisiana, Alaska, and Oklahoma collected $525 million, $507 million, and $436 million, respectively. Oil and natural gas production were the major items taxed. While the table shows only the 10 states with the largest severance tax collections, a total of 17 states had severance tax receipts exceeding $10 million in 1980. The enormous increases in severance tax revenue between 1970 and 1980 can be seen from the table by comparing columns A and B. For the 10 states shown, revenues increased from $650 million to $3.8 billion during that period, due to a combination of higher prices, increased production, and new or increased taxes. In most states, increases in prices and production were more evident than higher tax rates. Although the revenue increase is impressive, it understates the extent of changes occurring during the past decade. Since tax collections are shown for fiscal 1980, the full impact of the decontrol of domestic oil prices is not evident. Also, taxes on natural gas reflect controlled prices. When full de-control of natural gas occurs, significantly higher revenues can be expected in gas-producing states, even if tax rates, production, and world prices remain constant. These increases in severance tax revenues, coupled with further increases expected to accompany natural gas decontrol, have produced fears that a substantial transfer of income is taking place from residents of energy-poor states to those living in energy-rich areas. Others worry that increased severance tax revenues will be used to substitute for a substantial portion of state taxes that would have otherwise been collected from firms and individuals. The resulting improvements in tax climate, it is thought, may encourage firms and workers to migrate to energy-producing states. While these issues are often portrayed as pitting energy have-nots against the haves, such is not entirely the case. Much of the original impetus for limits on coal taxes came from Texas residents, the state collecting the most severance tax revenue. One way of gaining perspective on these concerns is by examining severance taxes per capita and as a percent of state tax collections (see columns C and D in the table). When this is done, Alaska, where 1980 taxes on oil and gas production totaled more than $1300 per capita (and 35% of all state tax collections), stands out as a special case. There, the state was able to eliminate some individual taxes, place revenues in a permanent trust fund, and consider offering a rebate of some previous income

Jan 4, 1982

By L. T. Larson

Nothing in Turkey is simple. Its his¬tory is long and convoluted, its culture fascinating, its metallogeny diverse, and its geology very complex. This article will focus on the geology of western Anatolia and the precious metals poten¬tial of this third of Turkey. Any gold produced by mines in Tur¬key since the early 1900s has been a by-product of the mining for other met¬als, such as copper from the massive sulfide deposits of the Pontics. Archaeological records, however, prove that gold was mined from the Pactolus (present day Gediz) River and refined by Croesus at Sardis in about 550 BC. Other records and legends make it possible that gold was mined before 1200 BC for the Homeric City of Troy (Priams treasure?) about 25 km (15 miles) east of Canakkale at Mad¬endag and Kartaldag. A final legend of antiquity suggesting gold in what is now Turkey relates to King Midas. And, indeed, the city-state belonging to a king of that name has been recognized near the city of Eskise¬hir. More recently, precious metals have been mined at Madendag-Kartaldag in the late 1800s. Arapdag, near Izmir, remains the only "authenticated" epith¬ermal precious metal deposit in Turkey (Mosier et al., 1985). With this spotty record, why the sud¬den interest shown by at least five Euro¬pean-based, three or four US-based, and several other international mining firms and their Turkish subsidiaries? Like other aspects of Turkey, the complete answer is not simple but, reduced to its basics, has three parts. Turkey, relative to many developing nations, has a stable, democratic form of government (although it also has a for¬midable bureaucracy) whose currency exchange rate is premised on the US dollar. New laws promulgated since 1983 have opened the country and welcomed foreign investment. Some have even provided investment incentives. The Mining Law of August 1985 made sweeping reforms of the old land tenure system. This law made it possible for a foreign-based company to have a wholly-owned Turkish subsidiary en¬gaged in mining. Equally important is the belated recognition that western Anatolia, while geologically compli¬cated, is today basically a province Neogene extensional tectonics having many of the geologic attributes of the leading gold producing province of the US - the Basin and the Range. Geologic rationale for precious metals exploration Tectonic/lithologic framework: Alle¬gorically and simplistically, Anatolia during early Neogene (middle Miocene) can be likened to a tube of toothpaste with the cap off. It is squeezed in the vise formed by the Arabian plate mi¬grating north toward the southwest end of a stable Asian platform. The "tube" was compressed. It could not expand to the east because it was sealed by what is now southern Russia and Iran. The filling of the tube escaped to the west, in the direction in which the cap was miss¬ing (Fig. 1). So developed during the middle to late Miocene the western-most struc¬tural province of Anatolia. This was done by a process aptly termed tectonic "escape" by Sengor et al (1985). This province is dominated by exten¬sional tectonics much like the Basin and Range of the western US and has an estimated extension of between 30% and 50%. The most striking manifesta¬tion of this extension is the 10 to 11 major east-west trending grabens (Ge¬diz, Buyuk Mendares, Kocuk Mendares, etc.) and intervening horsts, although a much greater number of smaller, gener¬ally northeast-striking grabens and half

Jan 1, 1989

By G. Chi, M. C. Fuerstenau, R. C. Bradt, A. Ghosh

Technical Papers, Mining Engineering Vol. 49, No. 12, pp. 70-75, Discussion by McIvor, R. and Fink, R. P. We must challenge what we consider to be dubious statements in the above-mentioned article. Much of what is reported was published elsewhere over a year ago (i.e., in their reference: Chi, G., Fuerstenau, M.C., Brandt, R.C. and Ghosh, A., 1996, "Improved comminution efficiency through controlled blasting during mining," International Journal of Min¬eral Processing, Vol. 47, p. 93). There is nothing unusual or significant about a 10% or more difference in grindability between two materials of apparently similar origin and other attributes (such as chemical assays, hardness and specific gravity). Consider also that: • the materials came from different locations in the pit; • only two sets of four blastholes were considered per blast: • spatial orientation with respect to the face and other blastholes was also altered; • only two pairs of data were collected; • the impact of sampling error and bias, • both of which could be significant in this case; and • normal experimental error in parameter measurement and calculation. It is clearly inappropriate to draw any conclusions with regard to cause-and-effect relationships without first presenting a thorough error analysis. A substantial number of randomly selected test and control areas might provide meaningful statistical evidence of the claimed effect of the variables being studied. Even that appears doubtful, however, because Figures 3 and 4 show about as much variation in crushing energy for the two "regular" conditions vs. regular and altered conditions. On a separate, but also important issue, broad experience with autogenous/semiautogenous milling has shown that smaller or weaker feed material results in reduced tonnage. ? Reply Thank you for the opportunity to respond to the comments of Messrs. Mclvor ant Fink. The points raised are addressed in the order of presentation. As the commenters noted, there are parallels between this article and a previous manuscript. The reason for these complementary articles is that the audiences for the two publications are different, although there is obviously some overlap. We believe that the different audiences each profit from the technical aspects of the two manuscripts. We are not in agreement that a grindability difference of 10% is insignificant. The laboratory work is corroborated by data obtained at plant scale, which confirms that an increase in throughput of the same magnitude (between 5% and 10%) is achieved when the blasting pattern is modified, i.e., reduced from 9 to 8 m (29.5 to 26.2 ft). This increase in throughput translates into substantial power savings for ore grinding. No differences in appearance in the rock were noted between the two adjacent areas. Rock in both areas belonged to the same rock mass/block, which was quite homogeneous and without geological features in between that could create drastic differences in comminution characteristics. Given the resources, we would have sampled from all of the holes. Additional data would certainly have been desirable, as would have been additional funding to expand the study. Their comment, "spatial orientation with respect to the face and other blastholes was also altered," is not clear. Figure 1 does not show the initiation sequence. Without the initiation sequence, we do not understand how the commenters concluded that spatial orientation with respect to the face and other blastholes was altered. The commenters may be trying to make the point that the four-hole configurations with respect to the original bench face are not exactly the same. In fragmenting the

Jan 1, 1999

Hoses provide a variety of critical functions in nearly every mining operation. Care must be taken when selecting, installing, and maintaining hoses to insure maximum hose life. This article provides some tips on selecting, installing, and maintaining hoses, and gives some background on hose construction and safety. In the mining industry, hoses are used for everything from hydraulic systems that power drills and hammers, to suction systems that carry away dust and debris. Hoses are used on such a large scale that a detailed discussion of specific applications would require many volumes. Dayco Corp. has, however, provided these basic and brief guidelines on how to select and maintain hoses for mining applications. Hose Construction Industrial hoses are classified as much by construction as they are by application. So, it is a good idea to start any discussion of hoses with a description of their basic construction. There are four basic components to hoses: the tube, reinforcement, cover, and couplings. The tube is the inner core or lining, and is usually made of smooth rubber or plastic. Rubber or plastic composition is scientifically determined to be compatible with the materials passing through it, such as fluids, chemicals, gases, or substances. Other considerations in compounding rubber or plastic for the tube are temperature ranges and stresses. In practice, the required compound can be precisely chosen from various charts listing them according to application. There are, however, applications where the compounding of tube rubber or plastic must be customized. The reinforcement hose layer immediately surrounds the tube. As its name implies, this layer gives the hose strength and provides protection for the tube component. Reinforcement must be able to contain the inner forces-pressure and shock-transmitted through the tube, and such external forces as twisting, bending, and crushing. So it is usually made of high tensile strength cord, fabric, or wire that is wrapped, wound, or braided around the tube. The cover is the outermost layer, so it may encounter oils, acids, water, dust, abrasion, and other potentially damaging influences depending, of course, on the application. An appropriate cover material must be selected, usually a rubber compound. Couplings, even though they are a hose attachment, are as vital as any other component and should be considered part of the hose. Couplings are usually made of carbon steel or malleable iron; however, bronze or stainless steel might be used if corrosive chemicals are involved and brass or aluminum might be used for flammable fluids. A coupling is usually in two parts: an insert that fits into the hose bore and contains the threaded male, female, or other type of connection, and the ferrule or collar that fits over the hose and secures the coupling in place. There are, however, some one-part couplings that fit securely into the hose without a ferrule. These are usually limited to low pressure applications and are secured to the hose by clamps or metal bands. Some fittings can also be permanently "built-in" as the hose is made. Couplings can be classified as reusable or permanent. The reusables can be removed when the old hose expires and used again on a new hose. The permanent types are crimped or swaged on at the factory or in the field (using special equipment) and must be discarded with the hose. Although couplings are most commonly thought of as having threaded fittings, there is another type called "quick connect." These either have a crow-foot or jaw-type design that permits a fast, "snap" connection. This can

Jan 6, 1982

By D. A. Norrgran, J. A. Wernham

Introduction In view of the continuing depletion of natural resources, requirements for energy conservation, plant optimization and hazardous waste management, and environmental consciousness, recycling and secondary recovery of materials are being developed with increasing interest Many secondary recovery processes are being developed that apply mineral processing technology. Gravity separation, magnetic separation and flotation have all emerged as explicit methods for recovering residual values from various process streams and hazardous constituents from waste streams. Recently, a technique for concentrating metallics has been successfully reintroduced. The concept of the alternating magnetic field eddy-current separator was developed over a century ago using rudimentary electromagnets (Patent 400317 issued to Thomas Edison on March 26, 1889). Widespread acceptance was, however, hindered by high costs, marginal results and poor economic incentives for secondary recovery. With the recent increased interest in secondary recovery and the development of high-energy rare earth permanent magnets, the eddy-current separator has now gained prominent acceptance. The separation forces imparted by an eddy current separator are the function of the magnetic field intensity and the alternating frequency of the magnetic field. The evolution of permanent magnets has provided a cost effective alternative for the generation of high-intensity magnetic fields. High-energy rare earth permanent magnets have substantially reduced the capital and operating costs over the electromagnetic circuits employed in antecedent eddy-current separators. Specifically, in recent years, the strength of permanent magnets has increased several fold with neodymium-boron-iron rare earth magnets now providing an energy product of 35 million gauss-oersted. Figure 1 shows the evolution in the strength of permanent magnets. The development of these rare earth magnets has led to the design of circuits possessing a magnetic force an order of magnitude greater than that of conventional permanent magnetic circuits. The eddy-current separator has been successfully applied in several metal sorting and recovery operations. Most common is the sorting of metal from shredded automobile scrap and municipal waste. With the advent of high-frequency, high-intensity magnetic fields, the separator has advanced to the point where it has direct application in the beneficiation of fine sized metals. Relatively fine sized (-1/4 in.) metal bearing slags and spent foundry casting sands as well as precious metal hearing electronic scrap demonstrate excellent metallurgical response to the eddy-current separator, and applications have progressed to finer materials and more selective separations. Theory Electrical currents are induced in all conductors when exposed to an alternating magnetic field. The induced current generates a magnetic field in the conductor that opposes that of the alternating magnetic field. Figure 2, is a schematic illustration of generated eddy currents. In this particular example, the alternating magnetic field is produced by a series of permanent magnets mounted on the circumference of a rotor. The permanent magnets have alternating polarity. As the rotor revolves, an alternating magnetic field is produced, and the rate of revolution determines the frequency of the alternating magnetic field. When a conductor, such as a metallic disc in the illustration, is placed in the alternating magnetic field, a closed loop current flow occurs. The current loop in the conductor produces a magnetic field that is a mirror image of the alternating magnetic field. At any point in time, the induced magnetic field in the conductor directly opposes the alternating magnetic field. This opposition of magnetic fields produces an instantaneous repulsion in the conductor. The conductor is consequently repelled from the rotor. The alternating magnetic field has no effect on nonmetallic materials as they pass through the magnetic field and discharge the rotor in a natural trajectory. [ ]

Jan 1, 1992

By R. Kneisley, D. Conover, K. Haramy, K. Hanna

INTRODUCTION Coal mine entry intersections are high-risk areas for roof falls due to inherently wide roof spans, excessive stress, and variable intersection shapes resulting from breakthrough misalignments. Statistics from underground coal mines reveal that a high percentage of injuries occurs from roof and rib falls in entry intersections (Peng, 1980). The U.S. Department of the Interior, Bureau of Mines, is conducting a field research project to investigate failure modes surrounding underground coal mine entry intersections. The research objectives are to (1) develop a method to determine failure modes and stress-displacement relations around coal mine intersections and (2) develop engineering guidelines and empirical relationships for use in designing safer coal mine entry intersections. The basic approach to achieve the objectives is to instrument and monitor intersections before, during, and after intersection development in order to determine contributing parameters, such as in situ stresses, stress changes, strata movement, geology, physical properties, and mining sequence, that may influence the short- and long-term stability of the intersection and adjacent entries. This paper describes a rock mechanics instrumentation program, data analyses, and a comparison of two case studies conducted at two underground mines, designated as "A" and "B", in the Illinois Coal Basin. The instrumentation plans and data collected during development and long-term monitoring of four-way intersections and adjoining entries are presented. Data analyses of pre- and post-mining roof stress, pillar loading, strata movement, roof bolt loading, and geologic features are included. INTERSECTION FAILURE MECHANISM The region surrounding an entry intersection is characterized by different failure criteria than the region surrounding a single entry. Stresses induced during intersection development may result in a high incidence of roof and rib failures. Various numerical modeling techniques have been used to evaluate the failure modes surrounding intersections (Gercek, 1982; Chugh et al., 1975). Numerical modeling techniques include problems associated with the analysis of post-failure behavior, provision for different horizontal stresses (i.e., 01 f 021, and determination of inputs required for any non-elastic behavior. It seems likely that more sophisticated failure criteria, based on actual field data, are needed. The Bureau of Mines has conducted an extensive instrumentation program to investigate actual intersection failure mechanisms and to provide an improved understanding of stresses and deflections using beam and plate theories. Beam theory is not applicable to analyzing intersections (Wright et al., 1964); however, it can be used to explain roof deflection and failure (shear and flexure) of adjacent entries and to provide an improved understanding of stress changes and displacements as the entries, crosscuts, and intersection are developed (Hanna et al., 1985). Beam theory may be used for entries when the roof length is twice the width. When the length is less than twice the width (as in intersections), the roof must be analyzed as a three-dimensional problem, and stress and deflection calculations are based on flat plate theory (Adler and Sun, 1976). The confined-core theory (Wilson, 1972) hypothesizes that within a typical pillar, two regions exist: a confined-core region where the horizontal confining pressure is uniform and approximately equal to the overburden pressure, and a yield zone where the vertical pressure increases from nearly zero at the rib to a pressure peak at the boundary of the yield zone. The strength of coal in the yield zone ranges from nearly zero at the rib to nearly full strength at the confined core. The vertical stress in the confined core decreases from maximum at the yield zone boundary to the overburden pressure some distance into the pillar. Excavation of the adjoining entries

Jan 1, 1986

By M. R. Yalamanchili, C. A. Young, J. J. Kellar, W. M. Cross, J. D. Miller

Introduction Researchers have long speculated regarding the adsorption state of collectors on mineral surfaces. Only recently have analytical techniques become available that allow direct in situ analysis of adsorbed layers. With reactive internal reflection elements (IREs), Fourier transform infrared spectroscopy coupled with internal reflection spectroscopy (FT-IR/IRS) allows for unobtrusive investigation of the adsorbed layer (Harrick, 1979). This technique has been used both for the in situ identification of adsorbed species and for the direct calculation of collector adsorption density in real time from infrared spectral data (Miller and Kellar. 1988). The reactive mineral IRE serves both to internally reflect the infrared light and to act as a substrate at which collector adsorption can be monitored. Shown in Fig. I is a schematic of light being internally reflected in an IRE. As the light is totally reflected at the interface, an evanescent wave propagates a short distance (typically a few microns) away from the IRE, and sampling of the interfacial region occurs. Because of multiple internal reflections, great sensitivity can be obtained. Flotation systems for which this method has been demonstrated include CaF2/oleate, Al2O3/dodecylsulfate, CaCO3/oleate, ZnS/xanthate and KCI/octylamine (Miller and Kellar, 1988; Kellar et al., 1989, 1990; Miller et al., 1990). Of particular interest to flotation chemists is the conformational behavior of the alkyl chain of adsorbed collector molecules. In the simplest sense, conformation can bethought of as the relative flexibility of the hydrocarbon chain caused by rotations about carbon-carbon single bonds. The flexibility is described by the amount of gauche/trans conformations in the alkyl chain. Figure 2 shows examples of gauche and trans conformations (rotational isomers or rotamers) in a hydrocarbon chain. These two conformations are observed when the terminal methylene groups in any four-carbon subchain are on the same side (gauche) or opposites sides (trans) of the plane of the middle carbon-carbon bond. A gauche conformer (rotamer) is thus a state of maximum potential energy, whereas a trans conformer is a state with minimum potential energy. The difference between these states has been found to be approximately 0.5 to 0.8 kcal/mole (Mead et al., 1986). The relative number of butane molecules present as gauche conformers with respect to trans conformers can be calculated from the Boltzmann equation (Mead et al., 1986). At 25° C approximately 66% of the butane molecules are trans rotamers. [ ] However at 100° C, only 33% of butane molecules are trans rotamers. Exposing the hydrocarbon chain to a polar, rather than an a polar, medium should also cause an increase in the number of gauche butylene groups in a hydrocarbon chain, although this effect has been difficult to observe experimentally (Mead et al., 1986). Forming a crystalline hydrocarbon is equivalent to decreasing the temperature, which greatly increases the amount of trans butylene groups present in the chain. From the preceding discussion, a picture of the solution species of concern can be developed. The collector monomer should exhibit the greatest number of gauche rotamers and most likely will look crumpled or balled-up to reduce the surface area in contact with water. The micellar form is expected to be aggregated, with the hydrocarbon chain existing in a less polar environment. These characteristic conformational features have been examined by FT-IR spectroscopy for various liquid phases of alkanoic acids (Umemura et al., 1981; Cameron et al., 1982a; Yang et al., 1986; Wong, 1987; Wong and Mantsch, 1983; Cross et al., 1992), phospholipid membranes (Fringe Ii, 1980; Casal and Mantsch, 1985: Wong et al.. 1988;

Jan 1, 1994

By Barrie Butt, V. S. Znamensky

The opportunity for an exploration geologist to follow a successful exploration project through the feasibility, financing, construction, development, and exploitation phase is rare. In addition, it is not often that the exploration geologist can be present during the mining of a deposit to explain why certain actions were taken or interpretations made, and to find out how these interpretations turned out in actuality. At the Woodsreef chrysotile asbestos mine in New South Wales, Australia, mining has been- in progress for seven years and the writer of this chapter has been intimately associated with the project during the five years of exploration and seven years of exploitation. The Woodsreef mine has had major production problems, the majority of which have stemmed from the unique characteristics of the ore body and fiber. Because of the latter feature, much research has been undertaken by Woods- reef and other scientific organizations in Australia, England, and Canada regarding the Woodsreef fiber. The answers to some of the problems have negated some accepted concepts of asbestos ore milling and led to the development of new techniques. Some of these new techniques include the adoption of microscopic fiber counts as a routine procedure, the modification of accepted evaluation procedures, the development of new machines for dedusting fibers, and the recognition of a fiber with a unique milling behavior pattern and, possibly, properties. The problems experienced can be broadly divided into those associated with the geology and the physical properties of the fiber. It is possible that the same features may manifest themselves in other deposits around the world, and if they can be recognized during the exploration stages, a feasiblity evaluation may be just a little closer to the actual. The Woodsreef chrysotile asbestos deposit (latitude 30°24' S, longitude 150°44' E) is located 80 km north of Tamworth, NSW, Australia. The mine has been in production for six years and has a present scheduled mining rate of 33.11 Mt/y. An eight rock line mill treats an average of 7000 t/day, after beneficiation, and yields fiber grades in the range of group 4 to group 6 with some floats. The estimated re- serves of 30.56 Mt, with an ore to waste ratio of 1:3.0, are contained in two main zones that are designated the North and South zones. Mining started in the South Zone in 1972 and then, be- cause of the higher ore value, moved to the North Zone in 1975. Presently, there are two distinct open cuts referred to as the South and North pits that will eventually be worked together. The Woodsreef mine is owned by Woodsreef Mines Ltd. and is operated by Chrysotile Corp. of Australia Pty. Ltd., and is one of only two producing asbestos mines in Australia. The second mine is at Baryulgil, (latitude 29°13' S, longitude 152°37' E), and is operated by a subsidiary of Woodsreef Mines Ltd. This operation produces about 500 t/y for a captive market. An exploration program is being conducted in the area surrounding this small producer with a significant degree of success. The concepts developed during the exploitation of the Woodsreef deposit are being incorporated in the evaluation of the Baryulgil area, and if the Baryulgil deposit proves to be eco- nomic it is hoped that this approach will eliminate some of the major crises that have beset the production at Woodsreef during the first four years of operation. The purpose of this chapter is to describe the Woodsreef deposit, and more important, to

Jan 1, 1986

By E. Yigit

Hydrometallurgical production of zinc from concentrates is generally carried out by H2SO4 leaching. For the smooth operation of this process, some harmful components must be removed from the leach solution before the electrolysis stage; MgO is one of these compounds. Zinc concentrate samples from the Mount Isa mines were used in leaching tests. Leaching tests with an aqueous solution of H2SO4 and SO2 gas were carried out at various temperatures, pH levels and leaching durations. While duration and the pH value of the solution were effective parameters in H2SO4 leaching, temperature and pH were more effective in SO2 leaching for the removal of MgCO3 and CaCO3. Removal of MgCO3 and CaCO3 was generally achieved at low pH values. The results show that SO2 gas can be a good alternative to sulfuric acid in the leaching of MgCO3 and CaCO3

Jan 1, 2010

By K. Oraee

Excessive emissions of methane from the coal seams can have a serious adverse effect on both safety and productivity of longwall coal faces. Mechanization of coal faces has increased production possibilities to the extent that normal ventilation systems may not be able to ventilate coal face areas in order to lower methane content in the air to within legal limits. Production increases may therefore be prohibited for this reason, especially in gassy seams. Methane drainage from the coal seam by means of long holes and before production starts can act as a useful remedial action. In this paper a two dimensional mathematical model has been produced. The model that is based on finite elements, simulates a methane drainage system where the resultant risk is linked to the coefficient of diffusion, coal permeability, holes pattern and the duration for which the seam is subject to drainage. It is concluded that methane drainage of this type can assist in achieving production increases in many coals seems, especially where high gas content is a virtue of the seam.

Jan 1, 2010

By A. A. El‑Midany, O. M. Asem, S. E. El‑Mofty, M. F. Abadir

Glauconite is a clay mineral that is most probably mined with phosphate and represents a challenge for phosphate upgrading by flotation. Reverse flotation is a common method for removing silica and silicate from siliceous phosphate. Thus, a systemic study was conducted to determine the effect of clay and its interactions with siliceous phosphate ore components on its cleaning by flotation. The flotation of each mineral (phosphate, quartz, and clay) was tested in terms of product recovery using quaternary amine at pH 9. In addition, the settling behavior of each mineral was investigated with and without quaternary amine. Binary and tertiary systems were studied to investigate the interactions between the main ore-containing minerals. The results of each mineral flotation test showed that quartz has the highest floatability, with low floatability of both phosphate and glauconite by quaternary amine. The presence of glauconite does not affect the phosphate recovery, whereas glauconite reduces the quartz floatability, which deteriorates the quartz removal from phosphate. Finally, the interaction mechanisms in the different systems are illustrated.

Apr 5, 2024

By M. Yekeler

The critical surface tension of wetting values (Ye) of realgar (AsS), talc [Mg3si401o (OH) 2]' stibnite (Sb2S3), and sulfur (S) were determined by flotation in the absence of conventional flotation collectors as 38.7, 38.0, 35.5, and 30.0 dyne/cm, respectively. The surface tensions of flotation media were arranged by methanol. Separation of binary mixtures of these minerals was performed exploiting their Ye differences-which form the basis of the "ganuna flotation process". One step flotation test showed that sulfur floats preferentially from its mixtures with realgar and stibnite at recoveries of 73.6 and 70.7 % and grades of 81.7 and 91.2 %, respectively. The separation of stibnite from realgar gave a recovery of 4.1 % and a grade of 41.2 % for stibnite, indicate that a minimal Ye difference of 3.6±0.2 dyne/cm is essential for such separation when conventional flotation reagents are not used. This paper presents data and describes the approach employed in these separations.

Jan 1, 1994

By S. S. Peng

High horizontal stress has been well recognized as a significant factor in roof control. It can adversely affect roof stability if the panel is designed improperly. Mining experience has shown that it can cause a cutter roof. The effects of high horizontal stress on roof stability depend on many factors such as magnitude and direction of the maximum principal horizontal stress, ratio of the maximum to minimum principal horizontal stress, structure and mechanical properties of the immediate roof and mining sequence. However, little is known about the intrinsic mechanism of high horizontal stress effect on roof stability except some conceptual explanations. In order to design a stable entry, the redistribution and concentration of high horizontal stress around the openings must be fully understood. Using the 3-D finite element analysis technique, this paper presents the redistribution and concentration of high horizontal stress field for a three-entry system with different orientations of horizontal stress. Based on the horizontal stress redistribution, possible roof failure for different orientations of horizontal stress is analyzed.

Jan 1, 1996

By James W. White

From Modular's first truck-dispatching system for Phelps Dodge Corporation in 1979 to today's alliance between Modular and Komatsu, Ltd., innovation has been Modular's main product. This paper describes the growth of a mining products supplier and the philosophy and decisions behind that growth.

Jan 1, 1998

By Gordon P. Riddler

IMMM Reporting Code 2001 – Some Developments -General definition of a Competent Person -Rules of Conduct with Guidelines -Table of Generic Terms with Guidelines -More specific to non-metallic minerals -Word ‘ore’ is not used for reserve/resource categories -More definitive on Mineral Exploration Results

Jan 1, 2003

The paper describes the procedure of data inquiry on the structure of mineral production in Austria and selected results. Goal of the endeavor was to gain more tangible insights into the mining industry as a basis for regulation balancing economical, ecological and social aspects.

Jan 1, 2006

By Mary C. Jennings, Peter F. Marcus

This paper examines the dynamics of aluminum consumption (all products), scrap recovery and primary aluminum capacity for the Western World through 1995, with particular emphasis on the U.S. aluminum industry. The relationship between the prices of ingot, sheet and extruded products is also explored.

Jan 1, 1986

High pressure grinding rolls have found widespread acceptance for cement processing, and are now making their debut in the metalliferous minerals industry. Significant energy and wear material savings appear achievable in many applications. This paper re- views the technical literature on this important, emerging technology.

Jan 1, 1997

By D. H. H. Quon, A. Ahamd, G. Pouskouleli, T. A. Wheat

An outline of the contributions of hydro- metallurgical techniques such as sol-gel processing, direct precipitation and hydro- thermal decamposition for the development of high-quality ceramics is given and examples drawn from recent work on both structural (engineering) and functional (electrical) ceramics are discussed.

Jan 1, 1990

By AK Raina

Blasting is used in mining and civil excavations to break the rockmass for ore production or creation of space. One of the disadvantages of the method is that it causes breakage beyond the proposed excavation lines. Pre-split is used to control such breakage in rockmass. This paper introduces the use of digital image analysis technique (DIAT) to measure rock breakage and half cast factor (HCF%). A new factor, undamaged area (AUD%), is introduced to improve the prediction, owing to the shortcomings of the HCF%. A comparison of significant data of AUD% and HCF% showed that HCF% has a lacuna of overpredicting, whereas AUD% can be used effectively to address the issue. Artificial neural networks are used to solve the complexity of multiple variables involved in predictions and to ascertain the importance and sensitivity of such variables in prediction regimes. This method will help users to evolve blast-induced damage objectively. A comprehensive scheme of things for future developments is included, which can be helpful to researchers in defining their research in this area.