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By Cynthia M. Walck, S. K. Grant, R. D. Hagni

The Post Gold deposit is located in the northern part of the Carlin trend. The mineralization at Post occurs in proximity to a Jurassic-Cretaceous composite stock. Most of the gold at Post is hosted by non-metamorphosed calcareous siltstone and highly altered diorite, adjacent to the low grade skarn. Endoskarn, exoskarn, hornfels and marble are developed outward from the intrusive. The skarn is composed dominantly of diopside, tightly intergrown with gannet, k -feldspar, and sphene. The highest grade gold values are adjacent to the skarn, which acted as a permeability barrier to fluid migration. Post is the first Carlin-type deposit at which a skarn has been recognized to play a significant role in the localization of gold.

Jan 1, 1990

By Brian H. Jasperse, Nicholson Peter J.

Gravity retaining walls have been constructed using Deep and Shallow Soil Mixing (DSM and SSM) since 1991 in the United States. These walls, for both temporary and permanent uses, were constructed by mixing cement with in-situ soils over a volume containing 100% of the required gravity wall zone. Modern design techniques have reduced costs substantially by forming the required gravity wall section as a composite mass. Using ratios of 15-35% by volume, treatment f the ground forming the required gravity section has reduced the cost from about $40 to about $20 per square foot. Design, construction and actual performance of these gravity walls are presented.

Jan 1, 1999

By N. Finkelstein, D. A. Hinckfuss

The large and compact but simple Bougainville Copper Limited flotation circuit has been in operation for 3-1/2 years. Discussion of problem areas encountered since start-up and remedies that have been implemented or proposed, form the main basis of this paper. Full cur- rent operational data is also provided.

Jan 1, 1976

By L. O. Bond

High costs--and high risks--are normal in coal exploration and mine development. But risks and ultimate costs are minimized by foreknowledge of prospective coal seams and adjacent formations. Extensive drill hole programs are often used to obtain needed information. Cores and cuttings from these holes are used to determine coal location, thickness, and quality; they are also used to study physical and geological characteristics of surrounding beds. Valuable as these core and cuttings studies are, their effectiveness is often diminished by loss of recovery or by incomplete analysis. Needed is an effective and economical method for augmenting these studies. Well logs provide information of the type needed for efficient cool prospecting. Furthermore, obtaining these logs in drill holes, and evaluating the data they provide, is both fast and economical. To investigate the usefulness of well logging methods in coal explorations, the authors worked with Mr. Jon Jenkins of Truax Truer Coal Company. Logs were run in a number of drill holes in various areas of the Illinois Basin; these areas provided variety both in coal quality and geologic conditions. The data were studied extensively using computer methods similar to those now used in the evaluation of oil and gas wells. (2, 3) This study was used to produce a computer-generated analysis designed especially for mining problems.

Jan 1, 1969

Iron ores may be upgraded by flotation of iron oxides or siliceous gangue using either cationic or anionic collectors. The electrostatic mechanism of adsorption can account for the complex chemistry involved. In industrial practice, only cationic silica flotation is used at present in North America. Some of the seemingly paradoxical phenomena of cationic silica flotation behaviors in meeting the demand for low silica concentrates are reviewed.

Jan 1, 1989

By D. A. Norrgran, J. N. Orlich

Described is the application of high- intensity magnetic separation throughout the spectrum of industrial minerals. Performed either wet or dry, the separation has application in both the recovery and concentration of value minerals and in removing deleterious mineral constituents. The various types of magnetic separators along with the design and operating parameters relative to separation response are characterized. The characteristics of specific minerals to magnetic collection and the production of high-grade concentrates are described. Laboratory, pilot-scale, and plant studies carried out on a variety of industrial minerals have demonstrated the effectiveness of magnetic separation as either a primary or a secondary unit operation to achieve product quality.

Jan 1, 1987

By Ezra L. Kotzin

Foundry sands used to make molds and cores have been very important to foundrymen since metal casting began hundreds of years ago. They are now used in two basic ways, either in an uncured green state, grain-bonded with clay, or in a set cured state achieved with sand that, mixed with resins or oils, is cured by baking or by chemical reaction. The term sand, as generally used in foundry applications, may best be defined as material composed of granular particles of mineral matter, ranging in size from 0.5 to 2 mm in diameter. The particulate nature of the material may be the result of natural disaggregation or result from crushing and screening of rock or ceramic materials; crushed and screened products are sometimes referred to as "manufactured sand." Based on their origin, the raw materials for foundry sands will vary in grain shape, grain composition, relative surface, grain size, and grain distribution patterns. These properties, in addition to their chemical analyses, sintering point and expansion characteristics play an important part in the choice of sands used as the base molding or core aggregate in metal casting. Sands with different origins may be blended to produce specific compositions and grain size distributions. Early raw material requirements based on silica sand were simple, but as sand/core/mold technology became more sophisticated and binder technology continued to be developed, the physical properties of foundry sands became more critical. Silica sand is composed of quartz, along with, in most cases, small amounts of feldspar, mica, clay, and other common minerals. Although silica sand is still by far the most widely used base material in production of molds and cores used in metal casting, other natural mineral sands have their own unique characteristics and fill an important niche in special applications. As a result, the term sand, as applied to raw materials used in metal casting, has been logically extended to include granular materials composed of a group of minerals other than quartz. With increased use in advanced foundry technology, natural sands composed predominantly of zircon, chromite, staurolite, or aluminum silicate minerals and of granularized chromite or olivine, have become more than just alternate materials and are now commonly classified as sands when the grains are sand-sized. Foundry sand may therefore be considered under two categories: silica sands and non-silica sands.

Jan 1, 1994

By Guido Venturini, Giorgio Martinotti, Luca Delle Piane, Paolo Perello

This paper presents a critical review of geo-structural mapping methodologies applied to deep tunneling projects in complex mountain chains such as the Alps. Geological forecastings are often a crucial part of tunneling projects, which should allow contractees or contractors to assume their own risks. Despite this, often adequate methodological criteria are not applied in the realization of these studies, with consequent increase of costs and delays. A discussion should hopefully start in the world of tunneling in order to define a correct approach.

Jan 1, 2003

By Stephen J. Crittenden

Deep gas and oil production has been substantially increased over prolonged periods through the use of sintered bauxite propping agents. Since its inception in 1976, over 170,000,000 pounds of high strength ceramic proppants have been employed. Recent field evaluations and economic analysis demonstrate the superiority of sintered bauxite proppant over quartz sand. This paper describes the development, application, field results, and product evolution of sintered bauxite.

Jan 1, 1983

By Dick Lewis

The Misima deposit is on Misima Island in the Lousaide Archipelago, 240 km east-southeast of the Papua New Guinea mainland, and 600 km east of Port Morseby. Misima is a narrow mountainous island 40 km long and up to 10 km wide. The highest point is 1035 m above sea level. Gold mineralization is restricted to the eastern and less rugged third of the island. The Melanesian population lives in coastal villages. Subsistence agriculture is the main activity, although copra and cocoa are grown in plantations on the eastern and southern coasts. Prior to 1950, mining was important in the economy of the island. Climate is tropical, with little seasonal variation in temperature or rainfall. Tropical cyclones occur about every 10 years (Fig. 1).

Jan 1, 1990

By K. Hanumantha Rao, K. S. E. Forssberg, H. R. Manouchehri

The fundamentals of electrical separation, the electrical properties of minerals, the principal methods used for charging minerals and their mechanisms, the effective factors controlling the acquisition of charges by minerals, the general configuration of commercial electric separators and the forces operating during electrical separation of minerals are reviewed and presented.

Jan 1, 2000

By R. Allan Wallis

In the past mining engineers have tended to rely heavily on the advice of fan manufacturers in relation to fan equipment issues. A more adequate approach was advocated in a paper [ Wallis, 1965 ] submitted to the Eighth Commonwealth Mining and Metallurgical Congress held at Surfers Paradise, Australia during 1965. At that time Mount Isa Mine were in the process of installing 3 large 6096mm (20ft) diameter vertical axial flow surface fans of an advanced type [ Mathews et al, 1967 ]. The preliminary feasibility studies prior to preparing the detailed job specification for this project were extremely thorough with the result that it was possible to include detailed information and instructions in the document, ensuring the procurement of equipment that was satisfactory in all respects. Full advantage was taken of expert services provided by external organizations during the large coordinated multi-disciplinary exercise. My continuing activity and development in relation to the technology of axial flow fans is now at a stage where all known design and performance data are accessible through CAD programs [ Wallis and Kipp, 1987 ]. The extensive calculations that were necessary in 1983 can now be carried out in a mere fraction of the time, and with complete confidence. Model testing in order to validate the fan and duct design proposals is, in my view, no longer essential. The first of the computer programs enables a mine ventilation engineer to study a large number of alternative axial fan arrangements for comparison with the centrifugal alternative. By entering the volume flow rate, fan pressure and air density, he can then with ease, and rapidly, investigate the effect of various blading arrangements, downstream evasee area ratios, and hub ratios, on fan diameter and speed, with their related attainable fan efficiencies. This procedure had its origin back in the 60s when I was advising mining companies on new fan equipment. At that time such an investigation was quite lengthy and lacked the precision and completeness that is now available within the present programs. To obtain the major benefit from these outputs, it is most important not to be disconcerted by the three very important nondimensional parameters, namely, the tip flow coefficient (LAMt), the fan pressure coefficient (Kt or Kit), and the swirl coefficient (Es and/or Ep) as these are important when assessing the various design proposals. When seeking an understanding of the role and importance of each of these variables, ample help is provided in the user manual; the design recommendations are summarized in the help screens which are readily accessible within the design programs.

Jan 1, 1989

By William C. Larson

The number of uranium in situ leach operations has increased significantly since 1975. As of May, 1980, there were a total of 27 active projects, including 16 commercial scale operations (or under construction) and 11 pilot scale operations. The south Texas uranium district and Wyoming have been the most prominent areas in early field experiments as well as in commercial application of this new recovery technique, although in situ leach tests are now being conducted in Colorado and New Mexico. The growing number of commercial-scale operations is accepted as prima facie evidence that in situ mining now offers a third option along with open pit and underground mining for winning uranium from sandstone host rocks. It is estimated that in 1979 about 9 percent of the nation's total uranium production was from in situ mining. However in situ mining of uranium is not without its environmental controls. The primary emphasis of environmental controls falls into two catagories; namely, control of the leach solutions during mining and demonstration of ground water restoration. Finally this paper briefly reviews the Bureau of Mines research program in uranium in situ mining.

Jan 1, 1980

By Owen Kingman

This paper discusses grade control of ore mined at Tennessee Copper Company. Mineral zoning and the influence of mineral zoning on production grade are discussed and illustrated. In order to make this most understandable we will first briefly examine the flow sheet at Tennessee Copper to indicate the path followed by the raw material toward its various products. Then we will discuss some of the characteristics of the ore, specifically the distribution or zoning of the minerals in the ore which cause some of the grade control problems. Finally we Will discuss same of the steps that are taken to combat these problems. The flow sheet is illustrated as plate 1. The mined ore is allied to obtain 3 usable products: Copper concentrate, iron concentrate and zinc concentrate. Copper is found in the mineral chalcopyrite, CuFeS2. The Copper concentrate from the mill contains about 20% copper. These concentrates are smelter in reverberatory furnace and Pierce-Smith converter to blister copper containing 99.2% copper. Some metal is cast into 360 lb. pigs and shipped to the refinery. Some is made into shot copper and used locally to make copper sulfate. Copper sulfate is marketed from Copperhill principally in fungicides.

Jan 1, 1960

By R. Bleischwitz, R. Delzeit

"Tantalum, a heavy metal with characteristics such as superconductivity and high terminal resistance, nowadays is the most efficient material for production of capacitors, which are essential for production of small electronic applications like notebooks and cell-phones. It is one of the strategic resources for information societies. With supply extracted from Central Africa (Congo / DRC), China, Australia, and Canada, it can serve as an example for sustainability efforts in the management of non-renewable resources in Developing Countries, Newly Industrializing Countries and Industrialized Countries alike. The paper analyzes the life cycle of tantalum in its environmental, social, and economic dimensions. The first section highlights the importance of tantalum, showing a demand-driven market. The second section analyzes current and future supply. The third section tackles environmental and social impacts of tantalum mining in different legislations. The fourth section especially deals with the Case of the Democratic Republic of Congo since companies have been accused of participating in a civil ‘resource war’. Section five will draw conclusions for sustainable resource management. Written in an interdisciplinary manner, the article has a bearing on economics, especially on resource economics and new institutional economics, as well as on geography. It deals with questions such as security implications of physical scarcity in rapidly growing markets. In doing so it can, firstly, be shown that information exchange in combination with reputational risks lead to a shift in extraction activities from a Developing Country (DRC) to an Industrialized Country (Australia); i.e. a ‘race to the bottom’ does not take place. This, however, does not mean that market mechanisms work properly since information exchange (especially with China) is incomplete, moral hazard still prevails, and inadequate institutions hamper development processes in an exporting country like Congo. Any sustainable resource management for tantalum not only should foster gathering and exchanging better information on environmental and social impacts, but also incentives for upstream metal recycling in industry as well as support for governance processes in Developing Countries"

Jan 1, 2005

By Henry N. McCarl

From the earliest use of crushed and broken stone as landfill for eroded gullies in trails and roads, to the mixing of sand and gravel with cement to make concrete, men and women have found mineral aggregates to be useful materials in satisfying human wants. Crushed stone, sand and gravel, volcanic cinders, pumice, manufactured lightweight aggregates, slag, cinders, expanded perlite and vermiculite, and a great array of recycled materials such as grog (broken or crushed brick) and fly ash have served as mineral aggregates. These materials have provided bulk and strength in portland cement concrete, bituminous concrete, road base, fill, concrete block, and plaster and stucco finishes. Mineral aggregates provide many special characteristics such as compressive and tensile strength, surface textures, weight and density, thermal and acoustical insulation, abrasion resistance, and impermeability to various concrete products and mixes. While most materials used as mineral aggregates are consumed on the basis of their low unit values, the large volumes extracted in the United States each year make them one of the most valuable mineral resources in current production. In 1960, US production of construction aggregate was just over a billion tons per year (Meyer and Zelnick, 1991). Two decades of accelerated interstate highway, residential, and commercial construction brought the total annual production of mineral aggregates to roughly 1.4 Gtpy by 1970 and just over 1.6 Gtpy by the late 1970s. General economic and related construction slowdowns in the early 1980s saw annual US production of aggregates fall to below 1.1 Gt in 1982, and then rise to just over 1.7 Gtpy in 1990, a new peak in mineral aggregate production and use. Per capita annual consumption of mineral aggregates was approximately 5.68 t/capita in 1960, 6.89 t/capita in 1970, rose to a high of 7.25 t/capita in 1979, and has since settled to just under 7 tpy for every man, woman, and child counted in the United States Census of 1990. The value of these materials came to approximately $9 billion in 1990. During the period 1960-1990, roughly half of all mineral aggregates were used in the construction of residential, commercial, and industrial structures, and the remainder was consumed in highways, bridges, and other transportation facilities such as railway roadbeds, airports, and water-related projects (Meyer and Zelnick, 1991). During the period 1988-1992, public works (highways, waterway projects, road maintenance, etc.) represented closer to 60% of annual mineral aggregate demand with residential and non-residential construction approximately 40%. The growing market share of public works projects has been mostly due to the dramatic slowdown in residential, commercial, and industrial construction during the 1988-1992 period.

Jan 1, 1994

By W. K. O’Connor, J. C. White, P. C. Turner

The US Bureau of Mines is investigating the cobalt and manganese resource of the West-Central Arkansas district through field investigations, mineralogical characterization, beneficiation and hydrometallurgical tests. Located within the Ouachita Mountains, these structurally-controlled deposits occur along the axes of anticlines that form the mountain ridges. Brecciated novaculite is cemented with a mixture of manganese oxides, primarily cryptomelane and psilomelane. Cobalt is concentrated within lithiophorite, a particular Mnoxide phase. Chemical analyses of head samples reported up to 25% Mn and 0.17% Co. Magnetic separation yielded products containing up to 41 % Mn and 0.22% Co at recoveries of 95% and 93%, respectively.

Jan 1, 1993

By Gerald V. Jergensen, Edward J. Samuel

Slurry system are the principal method for storage and transportation of solids within and between concentration operations In a mineral processing plant. A slurry 1s a mixture of solid particles In water, or a chemical solution, that behaves like a liquid. The design of slurry transportation systems is generally analagous to pumping and piping water, but with a few notable exceptions: • The interaction of particle on particle affects slurry transport. • Particles often interact with the fluid, particularly when chemicals have been added to the system. • Particles have a frustrating tendency to settle from the slurry suspension, especially into locations not considered In the design. • Solids have an affinity for wetted surf aces and tend to wear them away. Slurry transportation systems Include a number of separate components, each requiring special design considerations. A systematic evaluation of each component of a slurry transfer system will help overlooking the small details that could cause operational headaches. Most slurry transport systems include: • A receiving sump or tank that provides for mixing and/or momentary storage of slurry. • A driving force.. by a pump, atmospheric pressure or gravity. • A suitable conduit for transportation.. pipes or launders. • A delivery objective.. another sump or process vessel, or distribution system to several process points. • A control strategy and design to regulate the transfer operation. The design of the slurry transportation system normally evolves through the following steps: • Finalizing the process flowsheet and establishing the weights and volumes to be handled. • Identifying and characterizing the various process fluids and slurries. • Defining critical and minimum transport velocities of fluids. • Selecting a pipe diameter (or dimensions and gradient) and

Jan 1, 1986

By Arthur B. Steiker

Digital simulation was used to model a proposed underground' train system. The trains are to haul ore from numerous loading points beneath the production area of the mine to a central underground dump location, and then return to the mine. The purpose of the simulation was to aid mine engineers in studying various alternatives and configurations regarding track layout, crusher (dump point) specifications, dispatch procedures, fleet size, and train length, among others. The simulation' model can also be used to study the same aspects of existing haulage systems. To accommodate a wide and initially unknown range of system designs, a modular model structure was developed with major components devoted to track routing, train movement, loading process, dumping process, and dispatch. Key statistics tabulated were number of trains dumped during a simulated week, queueing delays in the mine and at the crusher, crusher utilization, cycle time, and percent of time for each: activity (loading, moving, dumping, etc.). The simulation results were instrumental in identifying a train system design which would reduce queueing delays and meet production goals with a minimum of trains and track mileage.

Jan 1, 1982

By D. Papacharalampos

A combination of decision- theoretic and knowledge-based methods can be used to classify rock-types from satellite data both efficiently and accurately. An expert system utilizes knowledge-based rules, as a field geologist does, to produce results that make geological sense. Our expert system (GEMS), first processes background information from preexisting knowledge and develops a plan, then classifies individual pixels, and finally generalizes the results using geological rules and plots a map. The system is implemented on a microcomputer and is inexpensive enough to be a part of the standard equipment of any geologist who prepares reconnaissance maps.

Jan 1, 1986