Search Documents

By Victor E. Archer

INTRODUCTION Man is exposed to many agents which induce mutations in germ cells and/or cancer at work, at play, and at home. In this total mix of mutagenic and carcinogenic agents, how important are radon and its daughters? Before man moved into caves and other permanent dwellings, the principal mutagenic and carcinogenic agent to which he was exposed was natural background radiation--cosmic rays, radium and potassium-40 in his food, plus gamma rays and radon from the soil and rocks. When man moved into caves, captured fire, and began to preserve and store foods, his exposure to carcinogens and mutagens took a quantum leap. Carcinogens and mutagens appear to act in the same way, that is, by altering the DNA or nuclear proteins of cells. Most mutagens are carcinogens, and vice versa, so when I say mutagens from here on, I will be referring to both. The relationship of the two is emphasized by the fact that administration of a carcinogen to a group of animals not only increases cancer rates among the exposed animals, but also among their progeny (Tomatis 1979). Environmental Mutagens Smoke from man's fires, overheated foods, and foods preserved by smoking, resulted in ingestion and inhalation of many polycyclic aromatic hydrocarbons--many of which are mutagens. Caves and houses with tight windows and doors tend to collect the radon which is constantly emanating out of soil, rocks and concrete, so man's exposure to the radon daughter component of background radiation increased several fold. Preserving food by salting or pickling with material that contained nitrites and nitrates led to increased ingestion of nitrosamines, which are potent mutagens. When his grains and other foods were stored in slightly damp rooms, fungi or mold would grow on them. Several of these fungi are now known to produce very potent mutagens. The best known of these is aflatoxin B (Ramachandra 1979). It may seem strange that a living organism would produce a mutagen. One might think that it would scramble its own genetic heritage. The reason it does not is that it produces the mutagen in an inactive form. It can be activated only by an animal's enzyme systems after being eaten. When man moved into cities, the collective smoke from wood and coal fires further increased his exposure. That particular smoke has now mostly disappeared, but has been replaced by smoke from automobiles and industry. When man moved into the age of technology, his exposure to mutagens again increased dramatically. Many mutagenic chemicals, from benzene and beta naphthylamine to a long array of pesticides and tobacco products have been added to our environment. Excess deaths from cancer are now being observed among chemists in most industrialized nations. Mutagens are even found in much of our wine, beer, and whiskey (Keller 1980). Some of the chemical mutagens were widely used in food or in other commercial products before their potential was discovered. Striking examples of this is the original butter coloring agent and the polychlorinated biphenyls that have been widely used in brake fluids and electrical transformers. Large quantities of them have been discarded or disposed of in a careless manner--in such a way that many of them have contaminated our food, our ground water and air (Landrigan 1981). In this nation, with the help of several recent laws, we were just beginning to get control of the industrial chemical mutagens. With the relaxing of these laws that is currently going on, it appears that it will be many more years before we really bring chemical mutagens under control. Many nations have yet to come to grips with this problem. On top of this massive array of chemical mutagens we have now added radiation from many artificial sources. For most of us this means medical X-ray and fallout from nuclear weapons testing. Ionizing radiation is one of the most potent mutagens, so it has caught the public eye, and its contribution cannot be ignored. Fortunately, by the time we started using radioactive materials in quantity with the Manhattan Project, we had experience with radium and X-ray (some of it bad); we knew enough radiobiology and enough about methods of radiation protection so that most nuclear laboratories have had a phenomenal record of radiation safety. Radiation is one new technology with great potential for harm that has not exhibited that potential except for a few isolated situations like that of radium dial painters, uranium miners and atomic bomb victims. Uranium miners slipped into this list almost by accident. We could have protected our uranium miners just as well as we did the workers in nuclear laboratories; but we failed to do so. Why didn't we? The reason is simple. The Atomic Energy Commission was charged with protecting the health of their workers. They did not wait for a pile of bodies before they introduced controls. Congress appropriated the money, and taxpayers were willing to pay for the protection against radiation. Miners unfortunately did not work for the Atomic Energy Commission. Although mine operators were ignorant about radiation, the key item was that in the 1950s nobody was willing to pay the extra costs of adequate ventilation to control the high levels of radon and radon daughters in uranium mines. Control was not achieved until new laws and regulations were passed which made it compulsory. BIRTH DEFECTS AND CANCER

Jan 1, 1981

By L. Alan Weakly

Page one is missing from book

Jan 1, 1982

By Richard Klimpel

1. Introduction Laboratory and industrial grinding tests have shown that the process of size reduction can be significantly influenced by chemicals added to the powder or slurry being ground. The terms grinding aid or grinding additive refers to a substance which when mixed into the mill contents causes an increase in the rate of size reduction. The increased rate can be used to grind a higher feed rate to the desired product size or it can be used to produce a finer product size at a fixed feed rate. Whether the use of a grinding aid is justified in any given situation depends on the cost of the substance versus the improvement of output or product quality obtained with its use. Obviously, an expensive chemical must be effective in very small concentrations if it is to be economically justifiable; the cost criteria is calculated on the basis of the cost of the grinding additive per ton of material ground. Although there is direct experimental verification of the advantageous effect of grinding additives, no sound scientific explanation has yet been offered which explains or predicts the general behavior of additives. Rose and Sullivan have summarized most of the work undertaken prior to 1950 and Hartley, Prisbrey, and Wick have recently prepared an updated synopsis of the grinding additive literature. Many of the studies reported consist of subjecting materials with simple geometric shapes to some type of hardness or controlled single fracture test. On the other hand, a number of the studies were carried out on operating industrial scale mills, with little control or precise monitoring of the effect of the additives.

Jan 1, 1977

By Charles Bruce

Although much has been said about the high cost of exploration, both at home and overseas, little of a specific nature has been published on actual finding costs, if indeed such data has been developed. This contrasts sharply with our sister industry, petroleum, where finding costs for oil and gas are available for virtually any country In the world. The reason is largely attributable to the genetic complexity of the hard minerals, as opposed to petroleum, and the increasing difficulties we are facing in the search for new orebodies. We have available to us data on the annual exploration budgets of most of the major mining companies which show them to run into the tens of millions of dollars. My co-panelist, Dr. Walthier, Director - Corporation Exploration, St. Joe Minerals Corporation, New York, NY, summed up the feelings of many explorationists in a recent keynote address when he stated, "I would not recommend a mineral exploration program of a general nature in North America budgeted at less than three to four million dollars annually, spread over four to five years -- or smaller amounts for more years". We have the fact that many of the major companies now prefer to "buy into" a new mineral discovery, particularly overseas, because of the high-risk and high-cost of exploration. Is there, then, a place for the small investor, let us say with a budget of under $200,000 per year and, if so, where and how? This paper is directed toward the above question and is based on experience gained while managing a limited international exploration program, on a shoestring, over the past three years.

Jan 1, 1976

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"The Vermilion range extends from the vicinity of Tower to and beyond the ""international boundary, crossing into Canada at the eastern end of Hunter's Island. Merchantable bodies of ore have been discovered at but two localities along this extent, at Tower and at Ely, twenty-one miles east.The iron bearing formation of this range occupies the lowest position geologically of any of the Lake Superior iron formations, being placed by Van Rise and Clements in the Archean, as shown from the following succession:Lower Huronian Intrusive granites, granite porphyries, dolerites, and lamprophyresKnife Lake slatesAgawa formation (iron-bearing) Ogishke conglomerate(Unconformity.)ArcheanIntrusive granites, granite porphyries, and some greenstonesSoudan formation (the iron-bearing formation). (Minor unconformity.)Ely greenstone, an ellipsoidally parted basic igneous and largely volcanic rock The ores of the Vermilion series occur in the Soudan formation (the Agawa iron bearing rocks are not of commercial importance).At the Minnesota mine at Soudan the ore is a dense, hard hematite, occurring in irregular connected and disconnected lense shaped bodies in the jasper, which is intricately infolded in the ellipsoidal greenstone or green schists, so called on account of a characteristic ellipsoidal parting. The strike is about east and west and the dip approximately vertical, with a westerly pitch. The underground workings at this mine are some 4,500 feet in extent east and west, and over 1,500 feet in depth. The structure here is probably the most complex in the Lake Superior iron districts. Above the iron bearing formation, geologically, comes the basal conglomerate of the Lower Huronian, carrying large boulders and Masses of the iron bearing rocks."

Jan 1, 1920

By Alexandru Corneliu Stematiu, Catalin Popescu, Radu Sarghiuta

"The tunnel sector is excavated into a rock mass heavily affected by tectonics, defined as a regional fault. The rock around the tunnel support undertakes the non – elastic deformation and gradually detaches from the rest of the non affected rock mass, moving inside of the excavated area and tending to fill up the whole space. The initial solution of using stiff support consisting in double steel ribs I12 with circular shape in the upper part and straight vertical pillars in the lower part has proved to be inadequate. Based on the calculations of the subsidence phenomena and a mathematical model, the proposed alternative support was provided by special circular steel ribs – SG-23 –that allows a limited rib deformation (by relative slip between the arch segments) in order to mobilize the contact between the rock contour and the inner face of the rib - not only for the deformed rib but also for the neighboring ribs. 1. INTRODUCTION Hydropower development of Jiu river in Romania, in the narrow gorge sector includes two diversion HPP and a small hydro plant that provides the minimum required flow downstream: CHE Dumitra , CHE Bumbesti and MHC Livezeni (Table 1. Hydropower parameters).The Livezeni intake reservoir is provided by a gated dam located 1250 m downstream of merging point between Jiul de Vest river and Jiul de Est river. The dam is equipped with three radial gates with flap gates with a span of 12 m each and the height of (6 + 3) m. The longitudinal profile of Dumitra head and the location of the gallery zone that is the subject of the paper are presented in Figure 2. Longitudinal Profile – Dumitra Head."

Jan 1, 2016

By H. S. Soto

The exact reasons that explain the low recoveries of coarse particles in conventional flotation machines are not clear. Being a concern for only a couple of mineral industries comparatively very few studies have been devoted to the problem of coarse particle flotation. Coarse particles flotation is particularly important in potash and phosphate beneficiation. Potash concentrates with particles larger than 1-2 mm do not require additional compaction or recrystallization and receive a premium price. However, recovery of this size particle in conventional flotation cells is very low, and therefore, the coarse floation tailings have to be reground and refloated to produce, at a higher cost, a less desirable concentrate. In phosphate beneficiation deslimed coarse ore (nominally l4x35 or l6x35 mesh) is normally treated separatedly from the finer (35x150 mesh) ore. Concentration by conventional froth flotation alone yields very low recoveries, and therefore, additional processes such as agglomerate flotation in tables spirals and belt conveyors have to be used ( Moudgil and Barnett 1979). Fatty acids and fuel oil used in phosphate flotation have a moderate level of selectivity but considerable amounts of sand report to the froth product, thus concentrates have to be further upgraded by a double flotation process. Concentrates from the anionic circuit are scrubbed in an acidic media to desorb the collectors and then refloated in a cationic circuit to eliminate the fine silica (Lawver et.al. 1978). In this paper the reasons that explain the low recovery of coarse particles in conventional flotation are discussed. A flotation column modified according to the main conclusions of this discussion is tested with two coarse phosphate samples.

Jan 1, 1989

By B. N. Everett

The growing role of Colombia as a major supplier of internationally traded steam coal has been widely discussed in the industry. Although Colombian coal has been produced and exported in small quantities for a number of years, Colombia's position as a major coal exporter began in earnest in 1985 with the first commercial exports from the Cerrejon North Block Project. By way of background: ? The mine is located on the Guajira peninsula in Northeast Colombia, about 90 miles from the coast, as shown in Figure 1. ? In addition to the mine itself, the project involves construction of a dedicated railroad and port, which form a modern, efficient and integrated system. ? The Project is embodied in a 50/50 Association Contract between International Colombia Resources (Intercor), a wholly owned subsidiary of Exxon, and Carbocol, the Colombian state coal company. Intercor and Carbocol share investment and operating expenses equally and Intercor has the additional responsibility of managing operations on behalf of both partners. Each partner is entitled to 50% of the coal produced, and each markets its share separately. ? The project is a multi-seam, truck and shovel operation, based on large reserves (2-3 billion tonnes') of high quality bituminous coal. ? Exports began in the first quarter of 1985 at modest levels through what we call Early Coal Facilities, designed and constructed apart from the permanent coal handling system. ? Production will increase rapidly in each of the next few years, reaching the design capacity of 15 Mt per year in 1939. Based on available resources, however, the resource will support expansion, and continued growth n production into the 1990s appears feasible.

Jan 1, 1986

By Alexander Sutulov

It is calculated that since the beginning of last century, which practically coincides with the beginning of the Industrial Revolution, our civilization has consumed around 239.5 million tons of copper (see: Table 1). According to the most pessimistic projections of today, with only a 2.5% annual growth rate in demand, we are bound until the end of this century to consume another 200 million tons of copper in remaining 17 years. A recent study made by US Bureau of Mines (1) indicates that the proven ore reserves of 150 major operating mines and about 120 deposits sufficiently explored for development and feasibility studies accumulate a total mass of 49.3 billion tons of ore, assaying an average of 0.82% Cu and containing around 324 million tons of recoverable copper. Consequently, there is a high grade of probability that the bulk of our future ore supplies, for our demand of, say, next 25 years will cane precisely from these mines. The interesting point in USBM study is that it indicates the recoverable byproduct content of these ores and which is: 118.2 million troy ounces of gold 2277.4 million troy ounces of silver 7.1 million tons of lead 24.7 million tons of zinc 1.3 million tons of nickel 3.1 million tons of molybdenum 765 thousand tons of cobalt, and 720 thousand troy ounces of platinum. This information gives us a relatively reliable profile of our future ores for next 25 years, and thus makes possible evaluation of byproduct credits in our future copper mining and producing activities.

Jan 1, 1983

By L. G. Wilson

In order to comply with time limitations imposed by this symposium, a very narrow but nonetheless interesting segment of the market has been chosen for discussion of the preparation of a tailor-made product to meet a specific need, and in view of the fact that the barite market is one of the oldest and one of the broadest non-metallic mineral markets in the world, it is necessary that we place this in perspective. Of a recent world annual production; (i.e., 1966 figures released last year in MINERALS YEARBOOK), of some four million tons, the United States consumed over 1/2 million tons, of which approximately 950,000 tons were produced domestically and approximately 700,000 tons were imported. Of this total, something approaching 90% was used for drilling-mud weighting, and of the balance, all but about 60,000 tone is consumed in the production of glass, barium chemicals, aggregates, and other minor uses; thus we are really taking a look at a very minute, however important, and very selective, portion of the total barite-market. The real meat of this paper, after eliminating all irrelevant uses of barite, and delineating the area of discussion, resolves itself into the approach to a favorable marketing area and a specific attack on that area. Cost, to the user, has been, patently, a function of distance, as the basic price of barite has varied very little over the years until recently, and freight rates have been the governing factor. Conversely, the seller of barytes must make concession in the plant price to compensate for distance, if he is to successfully compete.

Jan 1, 1969

By William C. Baldwin

Unitization and containerization continue to grow with great rapidity throughout the world today. Every industrial nation outside of the Iron Curtain is devoting more and more time toward research of these developing sciences. Unitization and containerization are proving to be the solution to many of modern industry's most pressing handling and shipping problems. Manufacturers make large savings, carriers receive many benefits, and customers take an increasing interest in demanding that their shipments either be unitized or containerized. Unit-loads consist of items, packages or bulk materials pre-assembled into a convenient mass for handling by mechanized equipment and to fit the internal dimensions of carriers. It has been found that unitized handling and shipping offers cost savings too great to be ignored by anyone interested in the distribution of goods. At present, the benefits from unitized shipping and handling are being enjoyed only to a small extent due to the failure of many persons concerned with handling practices in recognizing only some of the advantages of unitization. Before the full benefits of unitized handling and shipping can be realized, some major changes in packaging and distribution practices will be necessary on the part of industry. Numerous investigations in the last two years show conclusively that there are more advantages and more inherent savings for shipping goods on pallets in unit loads than by any other method. There is no question that unit-load handling can offer significant advantages to the user over piece-by-piece package handling. Reduction in handling costs is the primary objective of such activities, but it is by far not the sole objective. Some of the other benefits that can be realized are:

Jan 1, 1973

By R. H. Smith

The total energy demand in the United States increased about 4 per cent annually during the 1960's 1 and is expected to increase at the same rate during this decade. Z Fuel oil growth in the 1960's was only Z per cent per year until 1968, but it increased to 8 per cent in 1969 and 11 per cent in 1970. Fuel oil demand is expected to grow at a 6 per cent rate through the 1970's. Part of this rapid increase in demand has been caused by restrictions placed on the sulfur content of fuels. High sulfur coal can no longer be burned in many parts of the country and has been replaced by low sulfur fuel oil. An insufficient supply of natural gas has also contributed to fuel oil demand. Air pollution regulations have not only caused an increase in fuel oil consumption, but they have also caused a reduction of sulfur content in residual fuel oils. Current regulations call for 1 per cent maximum sulfur content fuels over much of the country. Sulfur contents of fuels are limited to 0. 3 per cent in certain areas on the east and west coasts. Sulfur in residual fuel oils from high sulfur imported crude oil is reduced to 1 per cent currently. However, sulfur reduction to 0. 3 per cent is difficult and expensive.4 As a result, refiners may be hard pressed to supply the market for low sulfur fuel oil. The oil shale deposits in Colorado and Wyoming potentially are a huge source of low sulfur fuel oil. It will be shown that the low sulfur content and more importantly the sulfur

Jan 1, 1972

By Joseph E. Schiller

As part of the Bureau of Mines research on identification of asbestos fibers, a method was discovered for removing asbestos fibers from water. This report describes this process and its theory of operation. The surface charge of amphibole minerals in potable water was found to be negative, and in common with most other silicate minerals, the isoelectric point of amphibole asbestos fibers lies in the pH range 4 to 6. Magnesia is one of the rare oxides with a high isoelectric point of about 11. The surface of magnesium oxide will, therefore, be positively charged in water at pH 6 to 6, while the electric charge an. amphibole asbestos fibers is negative. Because of the electrical attraction of these oppositely charged solids, it was possible to remove negatively charged asbestos fibers from water by percolating water that contained suspended-asbestos through a porous bed of magnesium oxide particles. A bed of 100/200-mesh MgO was added to a glass tube with a cotton plug. Aqusous suspensions of 1 to 10 ppm cummingtonite asbestos (amosite), crocidolite, and chrysotile were percolated through this porous plug of MgO. Even though chrysotile is positively charged below pH 11, MgO is an effective filter medium for removing it. The highly basic MgO appears to cause the chrysotile to flocculate and attach to particles within the bed. Scanning electron photomicrographs indicated that essentially complete removal of the fibers from water was accomplished. Other materials tested as contact filter media and found to be ineffective or only partially effective were sand, calcite, carbon, diatomaceous earth, and cellulose. Acidic alumina collected amphibole fibers but not chrysotile fibers.

Jan 1, 1980

By J. D. Miller

X-ray computed tomography (CT) techniques have been developed for the medical services field in order to provide accurate internal images of the human body.(l-7) Now, a decade later, CT techniques are starting to be used in non-medical applications such as, non-destructive testing(8), flow pattern analysis(9), drill core examination (10,11), and coal characterization(12,13). In these fields of application, CT techniques offer the potential to extend our knowledge and understanding beyond that provided by more traditional methods of analysis. Although, CT systems involve very specialized and expensive equipment, the advantage of x-ray CT in revealing the detailed internal structure of an opaque material non-destructively should make it an important tool to provide a more complete analysis of mineral processing phenomena. X-ray CT systems generally consist of an x-ray source/collimation unit and a detector/data acquisition unit. The object to be examined is placed between the two functional units as shown in Figure 1. With this system the density array of selected cross sections of a chosen opaque object can be obtained in two dimensions. There are numerous areas in mineral processing to which x-ray CT technology can be applied and it is the aim of this article to identify these potential areas noting the advantages and limitations of the technology. Particular emphasis is placed on particle composition distribution and multiphase fluid flow measurements. In the case of particle composition distribution, liberation analysis and coal washability are considered. While in the case of multiphase fluid flow, swirl flow in the air-sparged hydrocyclone is given by way of example.

Jan 1, 1989

By Steve R. La Brooy

Techniques for dealing with copper-gold ores are reviewed. Cyanide has little selectivity of gold over copper, and depending on the reactivity of the copper minerals cut-off grades for gold recovery by direct cyanidation are generally below 0.5% copper for oxide ores and 1 % for sulfide ores. Non-cyanide gold leachants also tend to be reactive to copper. The cheapest option for sulfidic ores is to produce a flotation concentrate for smelting, while transition ores generally need a sulfidisation pre-treatment. The requirement for the concentrate to have a high enough copper grade to be acceptable to a smelter may compromise copper and gold recovery. This can lead to significant gold grades in the flotation tailing, and copper levels in the tailing that are too high for direct cyanidation to be able to recover the gold. Oxidised ores, flotation tailing or other material not amenable to flotation represent the greatest grey area for gold recovery. Copper removal by acid, alkaline or ferric pre-treatment is possible though not generally used. Cyanide pre-leaching to remove copper, followed by copper and cyanide recovery represents a potential option that has been installed at one Australian gold plant, where copper is recovered onto carbon, ahead of the slower leaching gold. Actual cyanide recovery depends on ore mineralogy, allowing for losses as cyanate, thiocyanate, carbonate and ferrocyanide. Alternative options for gold recovery following cyanide leaching include precipitation, ion exchange and solvent extraction of the gold. Ammonia-cyanide leaching may offer another option for more selective gold dissolution from flotation tailing and oxidised materials. A plant is currently under construction in Mauritania.

Jan 1, 1992

By K. R. Weller

In recent years, a variety of new or substantially modified grinding machines have been offered to the mining industry with claims of improved performance relative to standard grinding machines especially rod and ball mills. The incentive for developing such new machines is high, because costs associated with grinding are a very substantial part of the total costs of processing run-of-mine ore, and gold ores are no exception in this regard. The incentive is also high because of the very low conversion of input energy to comminution energy in most tumbling mills. If the most energy-efficient means of mechanical size reduction is slow compression of single particles, then this energy amounts to only about 3% of that used in tumbling mills. It would seem, therefore, that there is a huge potential to do better. This paper examines three types of grinding machine for which claims of higher energy utilisation ( amongst other beneficial claims) have been made, namely the high pressure grinding rolls, the vibrating drum mill and various styles of stirred mill. It presents evidence concerning the claims, examines the range of particle size and particle size reduction over which benefits might reasonably be expected to accrue, discusses the major issues in contention and briefly describes the research the CSIRO Division of Minerals has in progress, both independently and collaboratively, the latter mainly with the Julius Kruttschnitt Mineral Research Centre (JKMRC) via the Cooperative Research Centre for Mining Technology and Equipment (CMTE) and the Australian Mineral Industries Research Association (AMIRA). There are many criteria which may be chosen to assess relative performance of grinding machines. Those used below are:

Jan 1, 1995

By Julian Malnic

The nascent marine mining sector appears to be now at a point of critical mass with the prospect of mining seafloor massive sulphide deposits at some time in the coming few years an inevitability. Julian Malnic makes comments from his experience base as an entrepreneur and founder of Nautilus Minerals Inc. in 1995 and will speak from an independent viewpoint of the commercial setting of the status quo of the proto-industry and the major factors likely to have major influence over its future. The presentation questions these factors and the role they will play. Do we need metals from the oceans? Understanding the competing and established terrestrial sources of each commodity is essential in comprehending how a marine competitor can profit. What are the rates of discovery for marine minerals? At what point will marine explorers start to impact the terrestrial copper and zinc exploration sector? The advance of technology is important in finding, imaging and mining SMS deposits, but which new technologies offer the advantage to mining in the ocean and which to mining on the land? Several competitors have now joined Nautilus as competitors to this global pioneer of SMS exploration/production. The membership of the major miners in the marine sector is growing steadily with important relationships developing but many have not put a toe in the water yet. A path of increasing width is opening to commercialization of SMS miners but crusts and nodules, as bearers of copper ? also found in SMS, and nickel ? also found in widespread nickel laterite deposits on land, are unlikely, in this perspective, to be winners this century unless highly valued minor metals are targeted.

Jan 1, 2008

By J. J. Bartels

The phosphate rock review did not arrive in time for publication in the. June issue. The world phosphate industry continued its slide in 1992 from the already depressed levels in 1991. The industry is locked into a 30-year fertilizer price low due to the worldwide fertilizer glut. Domestic production and imported, marketable phosphate rock decreased 1%, while domestic consumption increased by 1 % last year. The US Bureau of Mines reported a decrease in the domestic phosphate rock value from $25.42/t in 1991 to $23/t in 1992 ($23.06/st to $20.80/st). The diammonion phosphate (DAP) product price also dropped in value from $138/ t in January 1992 to $11 0/t in December ($125/st to $99.70/st). Continued declines in DAP prices is forcing the US fertilizer industry to develop cost-saving programs and reorganizations. Layoffs in 1992 resulted in a 7.6% decrease in the Florida phosphate workforce. Since 1980, the Florida workforce has declined by 35%. Small phosphate companies were forced to close operations or were sold to larger phosphate companies. Federal and state environmental regulations for byproduct waste disposal methods are being studied. The Environmental Protection Agency (EPA) approved phosphogypsum use in agri¬cultural and research applications as long as the radium 226 concentration is lower than 10 pci/g. The EPA is also reviewing regulations concerning air emissions at fertilizer plants. Industry publications reported the possibility of continued company sales and mergers in 1993. Industry expectations are optimistic while waiting for an upturn in the market. The US phosphate industry consolidation into three or four major companies should evolve into a stronger world market force.

Jan 1, 1993

By Raphael G. Kazmann

The predicted warming of the earth's surface, presently the subject of much debate, controversy and legislation, is based on what is termed "the greenhouse effect." This is the result of the property of certain atmospheric gases. These gases allow the passage of radiant energy to the earth's surface and reflect back, to the earth, the infrared radiation given out by the heated surface. Physicists have computed that if there were no greenhouse effect the average temperature of the earth, now about 15° C (60T), would be close to -18° C (OT). Just what gases have produced this salubrious effect? Water vapor is the most important. Then come carbon dioxide, methane and a number of minor constituents of the atmosphere, both natural and man-made. Climate change, its cause and its impact on human activities have been the subject of scientific and historical study for more than a century. Recently, some scientists have concluded that if the man-made increase in the carbon dioxide and other greenhouse gases continues, by the late 21st century the earth's global average temperature will rise between 2° to 8° F. This temperature rise would cause the water in the oceans to expand and the massive polar glaciers to melt. In 1980, it was predicted that the sea level would rise 7.6 m (25 ft) by the late 21st century. By 1985, the predicted rise was 1 m (3 ft); and by 1989, it was 0.3 m (1 ft) (Jastrow, Nierenberg and Seitz, 1990). Agricultural scientists have pointed out that an increase in atmospheric carbon dioxide would enhance biological growth including the production of foodstuffs.

Jan 1, 1992

By Thomas D. Kaufmann

Whether pursuing hedging or speculative strategies, gold miners can increase sales revenues 1 % to 6% by constantly pricing production forward. Unlike other commodities, gold futures prices are consistently higher than spot prices. A Colorado School of Mines study showed theoretically and empirically that in the 15 years since the price of gold was released from government control, the forward price for gold has been higher than the current price almost 100% of the time. The reason why Metal traders know that holders of metal earn a bonus selling forward when the metal is in "contango." "Contango" is a mysterious word that crept into the trading vocabulary a century ago. It designates a situation when the price of a metal on the futures markets is higher than the price in the immediate or spot market. If the spectrum of spot and futures prices remains static over time, the forward seller who has contracted at a higher than spot price can make a profit equal to the contango by redeeming his commitment at the lower spot price when the contract matures. Consequently, when a seller in a contango market hedges, he makes a profit on the transaction in addition to avoiding a price change risk. On the other hand, buyers of the metal who hedge in a contango situation will sustain a loss equal to the contango. Producers of gold, however, are sellers of gold. For most metals and oil, there is no inherent reason why futures prices should be higher than present prices. Buyers and sellers decide that the price of the commodity will be lower or higher than present values for a variety of reasons.

Jan 1, 1991