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By D. Wallace Fields

Increasing public pressure and demands from various tiers of government have generated a legislative maze of statutory and administrative requirements facing industries involved in mineral extraction and processing. Each tier, of government has asserted concurrent jurisdiction and threats of harsh measures if industry does not satisfy all requirements. In the field of water pollution control, federal requirements have increased, carrying with them increasing techniques of enforcement - ranging from injunctions through criminal penalties. Federal laws have required that states formulate water quality standards as an adjunct to federal regulation. Florida has reacted with the Water Pollution Control Act of 1967. This act incorporates state water quality standards and permit requirements for any installation constituting a potential source of pollution, and provides for civil sanctions as well as injunctive relief. The federal government has utilized an 1899 law to require a permit for discharges into navigable waterbodies - a term which has been judicially defined to include any watercourse capable, after reasonable improvement, for use in the transportation of waterborne traffic. Failure to secure these permits can result in the issuance of an injunction or civil or criminal penalties. The Corps of Engineers will not issue these permits without the approval of the discharge by state, local and other federal agencies. Air pollution similarly is regulated by a multi-tiered network of laws and administrative standards. Federal regulation has increased from early research support in the 1950's through the development of Air Quality Standards and their enforcement by large fines, injunctions, administrative conferences and public hearings. Florida regulation, under the Florida Air Pollution Control Act of 1967, parallels federal law but grants concurrent regulations, requirements and enforcement tools to local and state agencies. Although previous state regulation was minimal, consisting only of three acts passed in 189 1, 1899, and 1911, in the future the mining industry will have to contend with this increasing network of ecological requirements. It is recommended that the industry take the initiative by involving Florida in the Interstate Mining Compact, as well as seeking the passage of a state reclamation law funded by a severance tax.

Jan 1, 1972

By Nora M. Hutt, Kevin A. Morin

There is currently some pessimism over mixing of net-acid-neutralizing (NAN) and net-acid-generating (NAG) rock to obtain indefinite near-neutral seepage from mined-rock piles. This is due in large part to the lack of well- documented, successful cases of blending and layering, and to the knowledge of unsuccessful attempts. Past work often defined a potentially successful mix in terms of the ratio of net-acid-neutralizing rock to net-acid-generating rock. For example, one case study indicated the bulk pile-wide ratio was approximately 3: 1. Since this exceeded a common ratio used in acid-base accounting, no acidic drainage was predicted. However, acidic drainage appeared within two years. A large part of the ambiguity in mixing arises from attempts to predict success based on a ratio. This paper looks in detail at simple discrete-zone mixing, where at least one truckload of NAG rock is placed in a particular location with no further rehandling or dozing. The lack of acidic drainage in this scenario is dependent on the intervening distance between the discrete NAG zones, along flowpaths occupied by NAN rock. Calculations show that the bulk mixing ratio of a mined-rock pile is not an accurate indication of whether near-neutral drainage can be maintained. For example, a pile with a bulk ratio around 300: 1 could still release some acidic drainage. Calculations also show that the minimum separation distance of the NAG zones (L) can be so great, even with typical NAG and NAN rock, that the mixed pile could safely contain only a few percent of NAG rock, which would not be sufficient for many minesites with NAG rock. The comparison to a more elaborate, computer-based statistical model shows that the simple discrete-zone approach will provide a reliable yes-no indication of whether any acidic drainage will leave a pile. However, predictions of whether combined downstream drainages will be acidic depend on numerous site-specific physical and geochemical factors within and below a pile that cannot be modelled in a general way, like the number of flowpaths and the nature of their intersections.

Jan 1, 2000

By Omar A. Muhtadi

8.1 INTRODUCTION Several methods currently exist by which gold may be recovered from a pregnant leach liquor. Two of these methods are discussed in this chapter, the Merrill-Crowe (zinc cementation) process and the carbon adsorption process. These two methods represent the most frequently used techniques for gold extraction and are, -in fact, used almost exclusively in U.S. heap leaching operations. Because of the efficiency and ease of use of these two methods, it is extremely likely they will continue to be quite prevalent within the gold mining industry in years to come. The remainder of this chapter includes information on the history of the two processes, descriptions of the actual processes, criteria to consider in selecting a recovery process, and commercial design and construction considerations for both of the gold recovery methods. As with other chapters in this book, some fairly technical information is presented for the benefit of those readers needing a greater level of detail. However, the overall intent of the chapter is to provide an overview of the processes likely to be used in gold extraction, thus giving the reader a firm basis for more technical research into the topic, should this be needed. 8.1.1 History of Zinc Cementation During the late 18901s, zinc cementation was introduced for the precipitation of gold and silver from cyanide solutions. This occurred at about the same time as the introduction of the cyanidation process, the history of which is recapped in Chapter 1. The initial cementation process involved introduction of a gold-bearing cyanide solution onto a bed of zinc shavings. It proved to be quite inefficient because the reaction rate was very slow. The zinc quickly became "passive", inhibiting further gold deposition. Shortly after this first introduction, zinc precipitation was improved by adding a lead salt (usually lead nitrate) to the zinc. This allowed a zinc-lead couple to form on the surface of the shavings, eliminating passivation of zinc surfaces and thereby allowing continued deposition of gold. Further improvements were shortly forthcoming. The first of these involved the use of zinc dust rather than zinc shavings. This provided a much

Jan 1, 1988

By David B. McWhorter, John D. Nelson

INTRODUCTION The quantity of seepage that will be released from a tailings impoundment depends not only on the characteristics of the seepage control system, but also on the properties of the foundation soil or rock beneath the impoundment and the nature of the groundwater in the area. The interaction between various elements of the seepage control system and the influence the various characteristics of the site and impoundment have on seepage are the subject of this paper. The results of analyses are presented herein to indicate the nature and magnitude of the effect that the various factors will have on seep¬age losses. Analyses were conducted for a uranium mill tailings impoundment located in an area characteristic of many found in the western United States or Canada. A typical seepage control system consists of placement of either a clay or synthetic liner beneath the impoundment. In some cases an underdrain system may be placed on top of the liner to collect drainage from the tailings. The parameters that were varied in the analyses included those pertaining to the liner, underdrains and foundation strata. In general, it is shown that the seepage losses will vary in a complex manner depending on the interaction of the elements of the site and the seepage control system. As may be expected, the liner and underdrain systems have the most pronounced effect on controlling seepage. This paper deals with the quantity of seepage released from an impoundment However, the impact that seepage losses from an impoundment will have on the surrounding environment will depend on the rate at which contaminants will enter the groundwater and the nature of the groundwater flow itself. Consequently, when considering these results with regard to environmental impact they must be interpreted along with considerations of geochemical factors. MECHANICS OF SEEPAGE The mechanics of seepage and methods of analysis that were used will be discussed briefly herein. For a more detailed discussion the reader is referred elsewhere (McWhorter and Nelson, 1978, 1979, 1980). A general column through the impoundment was considered to be as shown in Fig. 1.

Jan 1, 1980

By William H. Langer

Nearly every community in the United States is dependent on aggregate (sand, gravel, and crushed stone) resources to build and maintain its infrastructure. Unfortunately, developing aggregate resources to meet societal needs causes environmental impacts. Most environmental impacts associated with aggregate mining are benign. Extracting aggregate seldom produces acid mine drainage or other toxic effects commonly associated with mining of metallic or energy resources. The most obvious environmental impact of aggregate mining is the conversion of land use, most likely from undeveloped or agricultural land use, to a hole in the ground. This major impact is accompanied by loss of habitat, noise, dust, blasting effects, erosion, sedimentation, and changes to the visual scene. Some of the impacts are short-lived, and most are easy to predict and easy to observe. Most impacts can be controlled, mitigated, or kept at tolerable levels and can be restricted to the immediate vicinity of the aggregate operation by employing responsible operating practices and available technology. The intensity of environmental impacts generated as a result of mining are determined in large part by the geologic characteristics of aggregate deposits (geomorphology, geometry, and physical and chemical properties). Mining deposits that are too thin, or contain too much unsuitable material, results in the generation of excessively large mined areas and large amounts of waste material. Mining aggregate can lead to serious environmental impacts in some situations. Some geologic environments such as active stream channels, slide-prone areas, and karst terrain are dynamic and respond rapidly to outside stimuli including aggregate mining. Some geomorphic areas and (or) ecosystems underlain with aggregate serve as habitat for rare or endangered species. Similarly, some geomorphic features are themselves rare examples of geologic phenomena or processes. Mining aggregate might be acceptable in some of these areas, but should be conducted only after careful consideration, and then only with extreme prudence. Failure to do so can lead to serious, long-lasting, and irreversible environmental consequences, either in the vicinity of the site or at locations distant from the site. Environmental impacts caused by irresponsible aggregate mining can compromise mining in an entire region.

Jan 1, 2001

By R. T. Webber, D. Moffett, D. W. Averill, G. H. Kassakhian

INTRODUCTION In Canada, radium-226 is removed from uranium mining and milling effluents by the addition of barium chloride to precipitate barium-radium sulphate. Large settling ponds are provided to effect solid-liquid separation. However, the barium-radium sulphate precipitate [(Ba,Ra)S04] is a fine, slow-settling crystalline solid which is not easily removed by simple sedimentation systems. Consequently, settling pond effluents may contain appreciable quantities of particulate or suspended radium-226, depending upon the specific pond system and/or the time of year considered. Also, current technology is expected to be incompatible with ultimate disposal goals since safe recovery of the barium-radium sulphate sludge from the settling ponds may be difficult to achieve (IAEA, 1976). Under the auspices of Environment Canada, a Government-Industry Mining Task Force established a Radioactivity Sub-Group in 1974 to assist in the development of effluent regulations and guidelines for the uranium mining industry. Among the recommendations of the Sub-Group was the need to seek more effective methods of radium removal, including development of physical--chemical treatment systems as an alternative to settling ponds. In response to the Sub-Group recommendations, a bench scale feasibility study began in March 1976 at the Wastewater Technology Centre (WTC) of Environment Canada. The bench scale work was expanded and accelerated in 1977 with financial assistance provided by the Atomic Energy Control Board. The results of this study indicated that coagulation and flocculation of the (Ba,Ra)S04 precipitate greatly increased settling rates (Wilkinson and Cohen, 1977). Subsequently, a research program with a larger scope was initiated in January 1978; this program is jointly managed and funded by government and industry as indicated in Table 1. The principal goal of the Joint Government-Industry Program is the development of a physical-chemical process to reduce the radium-226 content of uranium mining and milling effluents. The following effluent radium-226 activities were established as targets for the program: 0.37 Bq/L (10 pCi/L) as total radium-226; 0.11 Bq/L (3 pCi/L) as dissolved radium-226. Process development work was undertaken at bench scale at the WTC and at

Jan 1, 1980

By Richard H. De Voto

The Pb-Zn-Ag deposits within the Lower and Middle Paleozoic strata of central Colorado (Leadville, Gilman, Aspen, and others) occur principally in Late Mississippian karst-solution features within dolomites and, to a lesser extent, limestones. Several un- conformities within the Devonian and Mississippian carbonate rocks and the subregional dolomitization of the Leadville (Mississippian) Formation that occurred during the Late Mississippian resulted from recurrent uplift of elements of the Ancestral Sawatch, Gore, and Front Range areas within central Colorado. Uplift of these areas also strongly influenced the details of the extensive karst topography that developed during the Late Mississippian. In particular, uplift of the Sawatch Range area caused paleovalleys from 300-600 ft deep to form on the karst landscape. The pattern of karst-solution caverns, sinkholes, cutters, channelways, and breccia-rubble zones was strongly controlled by incision of surface drainages and the strong northeast-trending Mississippian joint system. These subterranean karst-solution features and breccia-rubble soil [ ] zones are the primary controls of the location of the Pb-Zn-Ag ore deposits in these rocks. In the Leadville and Aspen districts, the deeply incised paleovalleys occur immediately adjacent to the principal areas of mineralization. Pennsylvanian deposition of a thick terrigenous and evaporite sequence occurred within central Colorado in response to actively subsiding extensional basins and adjacent high-relief uplift areas. Hot brines developed within the Pennsylvanian strata, migrated laterally to, and moved upward vertically along, basin- margin faults during continued Pennsylvanian subsidence and deposition. These metal-rich brines migrated into karst-solution features within the Lower and Middle Paleozoic dolomites and limestones, principally within the Leadville Formation, in basin- edge uplifted locales where the Pb-Zn-Ag minerals were precipitated. Field relationships, mineral assemblages and paragenesis, fluid-inclusion data, and isotope studies suggest that the metals and brines were derived within the Pennsylvanian sedimentary sequence and that the ore minerals were deposited under different temperatures and at different depths from deposit to deposit. Chemical reaction with the carbonate cave sediment and wallrock, cooling of fluid temperatures, and mixing with meteoric ground waters were the probable combined causes of mineral deposition in the karst-solution features. Late Cretaceous-Tertiary intrusive activity has subsequently modified some of the primary Pb-Zn-Ag deposits in local areas.

Jan 1, 2013

By M. A. Cornachione

The west central upper Peninsula of Michigan contains a large resource of graphitic slate. The slate has potential industrial use as a substitute for shale currently used in the production of portland cement. Some of the unweathered slate, however, has a high concentration of pyritic sulfur which can create emission problems when processed in a kiln. A low cost method to reduce the sulfur content of the slate through the optimization of pyrite oxidation in a bio-heap leaching operation was investigated.

Jan 1, 1992

The amount of hydrophobic materials constituting the mineral froth strongly influences the froth viscosity. Higher froth viscosity on the other hand can retard the drainage of physically carried over hydrophobic particles. In phosphate flotation tests a direct correlation was observed between froth viscosity and recovery and an inverse correlation between froth viscosity and grade. Phosphate flotation tests in the presence of a silica depressant indicated that higher froth viscosity is an effect rather than a cause of silica particles reporting in the froth.

Jan 1, 1992

By John A. Riddle

Some of the pitfalls and problems in selecting and applying corrosion-resistant materials in uranium plants are discussed, together with some suggested solutions. Includes some cost data.

Jan 1, 1979

By Y. C. Kim

Although the first published optimum pit limit design algorithm by Lerchs-Grossmann dates back to 1965, the majority of the open-pit mines in the U.S. has not as yet adopted such a rigorous optimization algorithm. Instead, the floating cone approach initially developed by Kennecott Copper in 1961 is still used today for various reasons. However, shortcomings with the floating cone algorithm, particularly for precious metal deposits with erratic mineral distributions, have provided a renewed interest in optimizing algorithms.

Jan 1, 1988

By D. A. Rice

In pelletizing magnetic iron ore concentrates, about 6 to 18 lb of bentonite binder are added per ton of concentrate during balling to give green and dry strengths to the unfired pellets. The dry bentonite is mixed into the filtercake following the magnetic concentration circuit of the plant. The filtercake contains about 10% moisture, and the water may be of highly variable composition, depending on the particular concentration circuit, its source, and the ore being treated. A knowledge of the parameters that influence the balling operation is essential for optimal efficiency in producing balls strong enough to survive the treatment during transportation from the balling device to the furnace and during the firing operation. Furthermore, very weak unfired pellets probably contribute to high dust losses and poor furnace control. The factors that determine the strength of unfired pellets have received considerable study (1,2,3,4). Tigerschiold and Ilmoni(l) pointed out the significance of the surface area of the particles being pelletized. Merklin and Childs(2) reported on the effect of material size consist, chemical additives such as soda ash, lime, balling time, ball size, and the moisture content of green balls. Iwasaki and Zetterstrom(3) examined the detrimental effects of fatty acids on the pelletizing process. Stone(4) correlated the zeta potential of bentonites with the strength of unfired pellets. He found that, in general, a high negative charge on the bentonite is conducive to good balling. Although studies of pelletizing in the iron ore industry deal with a complex multicomponent system consisting mainly of the iron mineral, bentonite, and water, the last of these has received little attention, particularly with regard to the possible effects of mill water chemistry on the pelletizing process and the strength of unfired pellets. It is widely known that the composition of mill process water is an important variable in unit operations such as flotation, thickening, and filtering and that impure water can lead to poor metallurgical results. The results of the present study indicate that the chemistry of the mill water may be an important variable in the balling operation as well. Knowledge about this variable should contribute to lowering bentonite and oil consumption and to improving furnace performance. Such knowledge can also assist those who use balling in evaluating commercial bentonites for plant use as well as those investigating balling from a more fundamental point of view In this study we have examined 1) the effects of replacing mill process water in the magnetic concentrate filtercake with pure water, and 2) the effects of several chemical impurities that are commonly found in mill process waters upon the strength of unfired pellets. The results are interpreted in terms of the zeta potential of the bentonite and magnetite particles. The data lend support to a suggested mechanism whereby the electrostatic attraction of oppositely charged particle surfaces causes bentonite-bentonite and magnetite-bentonite bonding. This mechanism would also explain why several chemical additives e.g., sodium carbonates and phosphates, have such marked effects on increasing the strength of unfired pellets.

Jan 1, 1971

By J. Bartrum

Kidston Gold Mines is a 14 000 tonnes per day rated operation located 280 kilometers west of Townsville in Queensland. The principle shareholder is Placer Development Limited. Kidston's orebody consists of 44.2 million tonnes graded at 1.79 g/t gold and 2.22 g/t silver. Production commenced in January, 1985, and despite a number of control, mechanical and electrical problems, each month has seen a steady improvement in plant performance to a current level of over ninety percent rated capacity.

Jan 1, 1985

By T. B. Jarboe, H. Wen

Introduction The 150 MW circulating fluidized bed (CFB) power plant described in this article is the product of recent Bechtel experience in the industrial power and steam market, where the economic feasibility of fluidized bed projects has been proven. The ability of CFB boilers to burn low grade fuels makes it possible to burn low ranking coals or coal wastes. These include anthracite culm, coal mine rejects, and coal wash-plant-waste slurries. This article also addresses the impact of fuel characteristics on plant design. This includes solids handling, steam generation, sulfur capture, and auxiliary load requirements. The uncertain economic environment in which utilities must now operate has shifted the industry's interest away from large, base-loaded generating units to small, more versatile installations. Utilities now consider purchasing new generating capacity in smaller increments and staging its deployment to correspond with demand increases. In this way, they lower their risk in the increasingly hazardous art of long-range load forecasting. This strategy has many advantages. Multiple, smaller units have inherently greater turndown capability and better availability than a single larger unit of the same size. In addition, the smaller units will each have better cycling capability. And, with CFB combustion, the smaller units will have greater fuel flexibility. General plant description The 150 MW powerplant described here is a grassroots CFB unit. Fluidized bed technology differs from conventional combustion techniques. With CFB, solid fuel, together with inert material such as sand, gypsum, limestone, or ash from the fuel, is kept suspended in the combustion chamber. This is done by using the action of the fluidizing air distributed below the bed. Fluidization promotes the turbulent mixing conditions required for good combustion. The turbulence causes the entire mass of solids to behave like a liquid. The result is improved mixing. This allows heat to be generated at a lower and more uniformly distributed temperature that is below the ash fusion temperature of most coals. The fluidizing mechanism offers several other advantages over conventional combustion. There is less volatilization of alkali compounds, which cause deposits on boiler tube surfaces. And there is less sensitivity to the quantity and nature of the ash in the fuel. The low combustion temperatures prevent vitrification of the ash particles and minimize problems associated with furnace slagging. The ability to select from many fuels is one of the major advantages of CFB combustor technology. Fuels that can be burned in CFB plants to produce steam and electricity include: low grade coals with high ash or sulfur, lignite, peat, wood and pulp products, biomass, refuse, anthracite culm, petroleum coke, and oil shales. The plant's turbine cycle uses superheated steam at 12.4 MPa (1800 psi) and 538°C (1000°F), with single reheat to 538°C (1000°F). Two high pressure and three low pressure, closed, feedwater heaters are furnished. So is a deaerator, which is an open, direct-contact heater. The CFB plant exceeds EPA's New Source Performance Standards (NSPS) for air emissions. The design limits sulfur dioxide (SO,) emissions to 0.25 kg/GJ (0.6 lb per million Btu). SO2 reduction occurs in the combustor by reac-

Jan 11, 1988

By B. Mather

I was very glad to see an article on alkali-silica reactivity of concrete aggregate in Mining Engineering. It is a topic that should be reexamined every 45 or 50 years. The last paper (that I am aware of) that examined this topic in Mining Engineering was Rexford (1950), who, at the time, was chief of the Petrography Section, South Pacific Division Laboratory, Corps of Engineers, Los Angeles, CA. The paper was presented at the AIME meeting in Los Angeles in October 1948. Professor Leming's discussion generally reflects the current state-of-the-art; but it provides no references for more detailed information. I wrote a paper titled "How to avoid excessive expansion of concrete due to alkali-aggregate reaction," which was included in the Proceedings of the Second International Conference on Alkali-Aggregate Reactions in Hydroelectric Plants and Dams (Mather, 1995). In it, I emphasized that it was the hydroxide ion (not the alkali ion) that caused the pore fluid in the concrete to dissolve reactive silica, producing alkali-silica gel capable of taking up water, thereby, causing swelling and rupturing of the concrete. Excessive expansion will not occur unless there is a sufficient amount of potentially expansive alkali-silica reaction product and water. However, this will not occur unless there is a sufficient quantity of reactive aggregate and unless there is a mechanism by which the pH of the pore fluid can get well above the normal value of about 12.6. In many cases it is sufficient that the cementitious medium not only contains portland cement but also contains ground granulated blast-furnace slag (GGBFS) or a pozzolan such as fly ash, silica fume, metakaolin, volcanic glass or calcined shale - any of which may have been included for economic reasons. If, however, the person selecting the ingredients for concrete knows that the aggregate is reactive (with no alternate nonreactive aggregate available) and if the person knows that the only available portland cement has a high alkali content (i.e., more than 0.6% Na2O.; Na2e = % Na20 + 0.658 x % K20), then it becomes irresponsible not to establish what reasonable precaution one should take. Professor Leming suggests using one of the following: 30% Class F fly ash, 50% GGBFS or 7% to 10% silica fume. My view is that one should prepare test specimens with the cement and aggregate to be used and then expose these both with and without at least two dosages of each of the various alternative materials (slag, pozzolan and lithium salts), so that the required dosage. to control the expansion is established. Then, economic considerations can dictate the final selection. I would point out to the author that GGBFS is not a pozzolan and is not an admixture, but, rather, it is a latent hydraulic cement. An admixture is, by definition, a material other than hydraulic cement. I commend him for suggesting that aggregate producers should become more active in knowing about the reactivity of their products and the precautions needed to permit those products to be safely used in concrete.

Jan 1, 1997

By Y. C. Kim

M.S. Azun The article unfortunately has some serious flaws negating the usefulness of the paper. The authors claim that kriging (linear kriging) is superior to other methods such as polygon. This is not the case. The deterministic methods (referring to polygon, ID, IDS, etc.) should not be compared with the statistical methods (linear kriging, disjunctive kriging, etc.) because they differ not only in their assumptions, but also their tools used in estimation. Thus, they give different results. By comparing the results of deterministic methods and linear kriging, the authors conclude that polygon, IDS, and linear kriging give an average thickness close to the value obtained from realizations. Besides, they argue that linear kriging gives less variance than the others (Fig. 2). The first conclusion is expected, due to the well-known central limit theorem. The second is the result of the statistical properties of different estimators. Thus, the comparison presented in the paper is rather meaningless because the authors have failed to follow basic statistical procedures. The numerical results of different approaches to an estimation problem cannot be generalized. In conclusion, the paper is not a meaningful contribution, and sadly, quite erroneous. Reply by E.Y. Baafi and Y.C. Kim The two key contentions made by M.S. Azun regarding the paper are: deterministic methods should not be compared with statistical methods and, hence, the results are erroneous; and the paper does not make a meaningful contribution. The first contention is an academic one. Most practitioners in ore reserve estimation could care less whether the tool they are using falls under a deterministic or a probabilistic method, so long as it gives the desired answers. It is probably for this reason that, whenever any new tool such as linear kriging is introduced to practioners in the mining industry, they would like to see a comparison test performed between the existing and the more familiar tools with a new and "strange" tool. Only when a new tool passes such a test, the generally conservative mining community would begin to utilize the new tool to its advantage. The second contention, is a subjective one. The final judgment should be left up to the readers within the mining community. If kriging is accepted more among practitioners, partly due to the paper, then the paper makes a practical contribution to the state-of-the art in ore reserve estimation. Finally, M.S. Azun entirely missed two main points in the paper. The first is that any comparative study of kriging vs. Polygonal or IDS should be performed for local estimation and not for global estimation. In the past, kriging was frequently compared with other existing tools in its performance on global estimation. Such results were nearly identical due to the central limit theorem effect, which further prevented the acceptance of kriging by practitioners. The second point is that a single case study using an existing property, as it was frequently performed in the past, is not sufficient because results depend not only on the tool itself, but also on the nature of the mineralization.

Jan 3, 1984

By Charles L. Kimbell

Introduction Despite the focus on the so-called "high-tech" and service components of the economy, the minerals industry in 1987 continued to provide the world the overwhelmingly dominant share of the total raw material supply for all manufacturing operations. And, in the form of fertilizers and other soil treatment materials, minerals also supplied indispensable raw materials to ensure continued high production of the agricultural and forestry sectors of the world's economy. Moreover, the role of minerals as a source of construction raw materials was essential to that sector. On the basis of preliminary and partial statistics on world output of crude mineral commodities, 1987 appears to have been a year of further recovery from the recessional years of 1981-1983. The value of world crude mineral industry production (all mineral commodities including fuels) apparently advanced about 5% to nearly $1.1 trillion in terms of constant 1983 dollars.' That is significantly above the recently revised 1986 level of nearly $1.05 trillion, but still considerably below the record-to-date high of $1.27 trillion set in 1980, as shown in Table 1. That growth in value took place despite relatively flat world oil prices - oil being the most important component of the aggregate, as it has been for decades. There is insufficient information available to assess the total value of processed mineral commodities (refined metals, refined oil, manufactured fertilizers and the like). But a figure of $2.6 trillion (constant 1983 dollars) would be a quite conservative estimate for those materials derived only from primary or newly mined materials. And an additional, as-yet-unestimated increment should be added for processed materials derived from secondary raw materials - scrap and other reclaimed substances. From a world trade viewpoint, minerals and mineral products dominate in terms of tonnage. For example, in 1985, on a weight basis, mineral commodities including fuels constituted more than 58% of all goods moving through the Suez Canal and 53% of all goods passing through the Panama Canal. These waterways cannot accommodate giant tankers and ore carriers. So an even larger share of total oceanic trade is composed of minerals and mineral products. Yet, in terms of value, the share of the total accounted for by these industrial essentials is much lower than that accounted for by other commodities, most notably sophisticated high-tech equipment and other goods with a relatively high per-pound value. Worldwide data on the value of mineral export trade for 1987 is so incomplete at this writing that it is impossible to assess that actual level. Indeed, the compilation of similar available data for 1986 covers only the exports of nations with developed market economies. In 1985, these countries accounted for only 67% of total world exports of all goods. They accounted for only 41% of world exports of major mineral commodities: crude nonmetals; metal ores, concentrates, and scrap; mineral fuels; nonferrous metals excluding gold; and iron and steel. For these developed-market-economy countries, the value of exports of these major mineral commodities declined by more than 10% between 1985 and 1986. Most of the shortfall came as a result of a 26% drop in the value of fuels exports. If these patterns of

Jan 7, 1988

By B. Hornsby

At the Mount Isa mine, Mount Isa, Qld., Australia, sublevel open-stope mining is used for copper ore while both sublevel open-stope and cut-and-fill methods are used for the silver-lead-zinc ores. Production in 1979¬80 was 4 730 000 t (5,200,000 st) copper ore and 2 590 000 t (2,850,000 st) of lead ore. The deepest mine level currently is 960 m below the surface. GENERAL ORE BODY REQUIREMENTS AND LIMITATIONS Size, Shape, and Dip The mine is located in the valley of the Leichhardt River in Lower Proterozoic sediments of the Mount Isa group. The regional strike of the sediments is north¬south and they have a persistent westerly dip of about 1.1 rad (65°). In the mine area, the Mount Isa group comprises a sequence of alternating bands of dolomitic shales and siltstones some 3.2 km (2 miles) in width. It is bounded on the east by greenstones and quartzose sediments of the Eastern Creek volcanics, and on the west by the Mount Isa fault, west of which occur schists and other metamorphic rocks. The ore bodies as currently known at Mount Isa are restricted to the Urquhart shale, a formation of thinly bedded pyritic, dolomitic, and volcanic shales some 1070 m (3500 ft) thick. Towards the top of the Mount Isa group sediments, copper and silver-lead-zinc ore bod¬ies occur as contiguous but discrete entities and are mined and treated separately (see Figs. I and 2). Argentiferous galena, sphalerite, pyrite, and minor associated sulfides occur in distinct concordant bands throughout the Urquhart shales. Wherever these bands are grouped together in sufficient density they constitute silver-lead-zinc ore bodies with widths varying up to 36.6 m (120 ft). Other mineralized bands are common in intervening beds. Individual ore bodies persist for many hundreds of meters concordant with the strike and dip of the enclosing shales. Intersections of these beds with fold axes provide local zones of enrichment but otherwise the mineral content of the ore bodies varies only slightly throughout the extent of the dip and strike. Chalcopyrite is the only important primary copper mineral. It occurs in association with pyrite and pyrrhotite as disseminated flocks and as vein fillings throughout irregularly shaped zones of folded, brecciated, and re¬crystallized Urquhart shale. These zones, which are lo¬cally termed "silica-dolomite" bodies, are broadly transgressive to the shale bedding and confine all significant copper mineralization to the virtual exclusion of silver¬lead-zinc mineralization. In some areas, the downward percolation of acidic water through faults and shears has caused extensive leaching of the coarse-grained carbon¬ates to depths in excess of 610 m (2000 ft), but most of the silica-dolomite remains unleached and the ground is competent. The majority of lead ore being mined is north of the main shaft pillar (R62, U62) area. The major lead¬producing areas for many years have been the Black Star ore bodies (2 and 5 ore bodies) and the Racecourse ore

Jan 1, 1982

By Robert E. Blackett

To help local governments plan for long-term supplies of sand and gravel for buildings and infrastructure, the Utah Geological Survey is assessing natural aggregate resources (mainly sand and gravel) in the St. George, Utah area. Whereas much of the aggregate in the study area is adequate for road-base construction, high-quality aggregate for Port- land cement concrete is limited due to geology, and also due to land administration and environmental issues. Virgin River alluvial gravels southwest of St. George are generally poor sources of aggregate because they contain clasts of soft sediments and soluble minerals derived from Mesozoic rocks. Elsewhere, widespread secondary calcium carbonate (caliche), as rinds and matrix in gravel, lower the quality of material. Young river-terrace deposits in Fort Pearce Wash, and along the Virgin River above St. George are the primary sources of sand and gravel for the area. Alluvial fans on the east side of the Beaver Dam Mountains, and on the west side of the Hurricane Cliffs are also sources of aggregate. Stream-channel deposits associated with "inverted valleys" north of the towns of St. George and Hurricane, Utah, and older pediment gravels on the west flank of the Beaver Dam Mountains may be future sources of high-quality aggregate. Accelerated urban development during the 1980s and early 1990s has caused St. George and other communities in Washington County to encroach upon sand and gravel pits originally located in rural, undeveloped areas. Urban residents often view nearby sand and gravel operations as undesirable neighbors and pressure elected officials to close the pits. Pit closures effectively eliminate the remaining reserve from the sand and gravel resource base of the area. More- over, resources may also be lost as new homes are built upon undeveloped sand and gravel deposits. The St. George area is particularly susceptible to loss of aggregate resources because high-quality natural aggregate for construction is already in short supply. Moreover, most of the land in the study area is administered by the U.S. Bureau of Land Management and subject to various land-use restrictions. Much of this public land cannot be developed for mineral materials, such as sand and gravel, because of federal regulations protecting rare plants and animals, archaeological sites, and important watershed areas. Of particular concern to resource development are areas designated as Areas of Critical Environmental Concern, Wilderness Areas, and Wilderness Study Areas. Protection for Endangered Species is a critical element in all planning efforts. Those species present in the St. George area or in areas near- by include: the desert tortoise, southwestern willow flycatcher, Virgin River chub, and dwarf bearclaw poppy. As the St. George area is depleted and/or deprived of sand and gravel resources through extraction and urbanization respectively, construction costs will rise unless conservation measures are instituted. To avoid the loss of aggregate resources, the UGS is pursuing a program of data gathering and field surveying of surficial deposits to determine tonnage and quality of the remaining sand and gravel resources. The resource information from this program will help land planners, developers, and government officials make informed decisions concerning urban development throughout the region.

Jan 1, 2001

By P. Soros

To accommodate the immediate and long term growth of the Hunter Valley, one of Australia's major coal producing regions, a third coal terminal was required in the Port of Newcastle, N.S.W. The initial capacity required was 15 million tons per annum, made up of 40 different blends, to be expanded to 50 million tons of 100 different blends, made up from 70 grades. Coal arrives in 3,200 ton unit trains, a total of 16,000 trains in a year.

Jan 1, 1986