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By M. M. Botz

Cyanidation tailings which are disposed in a surface impoundment experience a loss of cyanide due to natural degradation, frequently reducing the cyanide concentration to very low levels. Quantifying cyanide losses in terms of pond geometry, local weather conditions and feed solution chemistry has been largely empirical though in many cases mining operations rely on surface impoundments to reduce cyanide to below an internally regulated concentration or an effluent limitation. To permit a more quantitative evaluation of cyanide losses in an impoundment, a computer simulation was developed to estimate the losses of free, WAD and total cyanide due to dissociation, photolysis and volatilization. Results of the model are compared against data collected for a North American tailings impoundment during 1998.

Jan 1, 1999

By Ernest A. Draeger, James W. Collins

Water only cyclones, sometimes referred to as hydrocyclones, are one of the newest types of coal processing equipment. These devices have achieved wide acceptance as fine coal cleaners in the past decade. Many metallurgical coal plants employ water only cyclones to process 0.5 mm x 0 size coal. Some of these plants have as many as 40 to 50 305-mm-diam units with each unit receiving as much as 9 t/h of raw feed. The growth in the utilization of hydrocyclones is due partly to the energy shortage, partly to the general increase in over-all coal preparation, and also because of a need for a simplified fine coal (0.5 mm x 0 size) gravimetric separator. Large diameter water only cyclones are also available and in use to process feed sizes up to 32 mm in size. However, the size normally employed for cleaning 0.5 mm x 0 coal are 356 mm or 305-mm-diam for single-stage circuits. In two-stage circuits, the secondary units are normally the same diameter as the primary units or smaller, such as 203-mm-diam. By using the small diameter cyclones and treating a closely sized feed, 0.5 mm x 0 only, it has been found that the probable error or imperfection of the water only cyclones is comparable to that obtained on the same size fraction treated in a large 610-mm-diam heavy media cyclone washing 38 mm x 0. The water only cyclone can approach the efficiency of a heavy media cyclone when cleaning fine solids because it creates its own dense media by accumulating high specific gravity particles in the wide angle conical section of the cyclone. A cut-away cross sectional view of a water only cyclone is shown in Fig. 1. It is also true that when treating a wide range of sizes (38 mm x 0) in heavy media cyclones, the smaller size particles (0.5 mm x 0) separate in proportion to the split of the media through the cyclone rather than by particle density.

Jan 8, 1980

By Ian McFeat-Smith

Despite a present, short-term economic recession, a remarkable enthusiasm exists in Hong Kong for building infrastructure including major tunnel projects. This paper provides details of current and recent bored tunnel works together with an insight into the impressive list of future underground projects planned by the MTRC,KCRC, Highways Department and Drainage Services Department for the next decade. Risks for each of these works including pipejacking, mixed face and rock tunnelling generally in Hong Kong are also identified. From this is evident that the scale and difficulty of such works continues to increase, requiring the use of more sophisticated methods of construction, the need for better methods of assessing and managing risks and for Government to utilize improved, more equitable Conditions of Contract for such major tunnelling projects.

Jan 1, 2001

By J. P. Wilson, T. Cook, H. Kling

The Tessenderlo-Kerley Leachprocess has been shown to be effective in the removal of residual copper from molybdenite concentrates. Concentrates of varying mineralogy, including those containing relatively large amounts of chalcopyrite, have been successfully leached on laboratory and pilot plant scales. The lixiviant system is ammonia andammonium bisulfite with air / oxygen addition. An abrasive is added which greatly enhances the kinetics, and it is subsequently screened out and reused. The dissolved copper is easily recovered using existing technology. Extraction profiles, reagent consumptions, and mineralogical data are presented.

Jan 1, 1999

By D. F. Strong

Most Newfoundland. mineral deposits can be clearly classified as within rocks formed either as accreting plate margins (ophiolitic pyrite-chalcopyrite massive sulfides such as Betts Cove, Whalesback, York Harbour, chromite at Lewis Hills, and asbestos at Baie Verte), at consuming plate margins (Kuroko-type polymetallic massive sulfides such as Buchans and Pilleys Island, porphyry-type Mo-Cu at Rencontre, fluorite at St. Lawrence), or within plates (zinc deposits at Daniels Harbour, sedimentary iron ores at Wabana, manganese in Conception Bay.) As these metallogenic patterns can be convincingly extrapolated southward into the Appalachians and northward to the Caledonides, they provide an important means of eliminating and selecting areas for particular exploration targets. Sonic criteria are described for the recognition of these environments of differing economic potential.

Jan 1, 1973

By Yu. A. Polozov, V. A. Lagunov, O. Yu. Lushinkova, Yu. I. Svirskiy, Eh. Ya. Kipko, Roy A. Williams

The effectiveness of the grouting of saturated, fractured rock in the vicinity of underground workings depends to a great extent on the correct interpretation of the specific hydrogeological conditions at the site. During the planning of grouting operations, calculations of the hydrogeologic co-efficients and of the parameters of the isolating grout curtain(s) and the procedures for forming the curtain(s) must be based on valid hydrogeologic characteristics of the fracture system of the rock within each hydrostratigraphic unit (Anon., 1976). This chapter presents a discussion of the background information that must be collected for these purposes. Details of testing are presented in Chapter 3. The general design of new or the reconstruction of existing underground workings requires a broadly based organization having the expertise to develop a grouting operations plan once it acquires the necessary information. The needed information includes: 1) general information about the hydrogeologic section, 2) the engineering design of the underground workings, 3) the geology of the region, 4) the hydrochemistry of the ground water, 5) the hydraulic properties of the rock, 6) the characterization of all gases present, and 7) characterization of the rock's physical-mechanical properties which is necessary to avoid or control hydrofracturing . The geological documentation portion of the hydrogeological investigation is prepared based on the results of geologic mapping, geophysical surveys and on geo-exploratory operations at a regional and local scale. Geological data from the excavation of other underground workings in adjacent areas of the region is also included. Finally the results of site specific investigations in boreholes constructed at the site of the proposed underground activity are incorporated. A section of the preliminary report entitled "General Information about the Project Site" patterned after the parent STG guidance document on this subject must be com- piled based on the contents of geological reports and on the general construction plan for a new project or the plan for reconstruction of an existing operation. This section of the preliminary report must contain concise information about the conditions under which the planned grouting operations are to be conducted. The information must cover the geo- graphic, administrative, and economic subject areas also. Information about sources of electrical power, heat and water supplies, the presence and characteristics of local construction materials suitable for making grout (particularly clay and cement for the clay-based grout), transportation, and the status of communication lines and other services must be included in this section. Map scales for this section should be on the order of 1:25,000. The technical characterization of planned underground workings is presented in a project report chapter called "General Construction Plan for a New or the Restoration of an Old Operation. " The characterization comprises concise information about the purpose of the workings, the planned depths (for shafts) and the length (for horizontal and inclined workings), the inside and excavated diameters (for shafts), the cross-sectional area (for inclined and horizontal workings), and the face and mouth markers. If excavated underground workings exist in the region, then a concise description of them must be provided. The characterization of all excavations and all operational conditions must be specified. The location within the general structure of the proposed operation is specified. Flow charts must be included in this section that show: 1) the plan for opening the deposit, 2) the plans of the mining operations, and 3) the planned geological sections as they relate to the main workings. These graphical flow charts and appendices are drawn in scales of 1:2000 or 1:5000. 2.1 GEOLOGICAL CHARACTERIZATION The geological characterization of a site of proposed underground workings includes the following principal subject areas: stratigraphy, lithology, structural geology and a characterization of the status of fracturing. 2.1.1 STRATIGRAPHY AND LITHOLOGY A description of the geological section of the rocks to be intersected by the planned underground workings is complied on the basis of: 1) research data derived from core extracted from exploratory boreholes and monitoring boreholes, 2) the documentation and mapping of all natural out- crops in the region, 3) the data from all existing under-ground workings in the regions where operations are being canied out already, along with data from adjacent regions, 4) the data from surface and borehole geophysical investigations (standard and specially developed logging methods, and 5) regional stratigraphy. The geological description of the rock must express the maximum detail possible. The description provides the name of the rock, the granulometric composition (for fragmented rock), the composition and type of stratification, the drilling characteristics of the rock, a visual estimate of porosity and density for each stratum identified, the karstic

Jan 1, 1993

By Walter R. Jr. Hibbard, William A. Vogely

INTRODUCTION Volatile markets and pricing, increasing imports, constraining but effective laws related to the environment, health and safety and price controls lead to concerns which generated pious laws stating non-fuel policy and authorizing studies but resulting in ineffective implementation. Several commissions, reports by the Secretary of Interior and even the President have led to many recommendations but little or no action. No single comprehensive policy could solve problems which are diverse, commodity specific and not categorizable (Landsberg 1982, 1983). Thirteen laws administered by 27 agencies regulate or affect minerals and materials. Political instability created by communist regimes in Southern and Central Africa jeopardized sources of critical imported materials. This situation led to a Resource War mentality. It was feared that the U.S.S.R. was seeking to control this area and exclude the United States from resources (Vogely, 1980). The success of the Organization of Petroleum Exporting Countries with a petroleum cartel led to fears of an Organization of Minerals Exporting Countries which might create more cartels and/or make the existing ones more effective. Economic needs of developing countries required export to maintain employment and balance of payments have led to world surpluses, weak markets, low prices, and large loans from the World Bank which have under- mined U.S. industry (Landsberg, 1982a). Un- cooperative environmental laws, obsolete facilities and non-competitive costs have led to shipping U .S. ores to other countries for processing into ingot and bars which are imported back to the United States. Yet massive internal turmoil has interrupted supplies, and led to un- certain availability and higher prices. This situation could happen again. Included in this category of critical materials with uncertain sources are metals required in the manufacture of military aircraft, which has led to concern regarding the defense industry base (Morgan 1983). Remedies have been proposed which include: updated stock piles, material substitution, international cooperation and coordination, foreign policy aimed at resolving racial and national stresses in South and Central Africa, relaxing U.S. environmental and public land regulations and action under the Defense Production Act (Goth 1982). The President's report (1983) to Congress has stated a national materials policy which recognizes: that materials play a critical role in our economy, defense, and standard of living; that public lands contain a vast untapped mineral wealth; that the role of government is to identify mineral issues and act on them; and that there is a need for long term high potential pay off research (Bureau of Mines 1983). There is a serious question as to whether or not a comprehensive national mining, minerals, and materials policy is feasible let alone necessary. One solution is to abandon the attempt at comprehensiveness and to target specific is- sues with realistic policies (Comptroller General 1979). In the following sections, the major studies of the 1970s will be reviewed, major issues yet to be faced will be identified, the principles involved in these resolutions will be reviewed,

Jan 1, 1985

By C. H. Bucknam

Classical acid-base accounting using modified Sobek titration methods has resulted in interpretation of results for materials with neutralization potential (NP) less than 20 tons of CaCO3/1000 tons of material (2% CaCO3) as "uncertain" due to lack of sensitivity within that content range. Standardization of a "fizzless" acid neutralization potential (ANP) method was undertaken in the American Society for Testing and Materials (ASTM) International using two ranges of sulfuric acid additions based on reaction pH and carbonate carbon estimates rather than subjective fizz testing as well as hydrogen peroxide additions to correct for mineral acidity. The method is identified as the acid neutralization potential acidity (ANPA) titration method. During interlaboratory testing a positive bias was discovered within the "uncertain" range which was further investigated and resolved by increasing the test sample weight from one to five grams for samples needing improved accuracy in materials with ANP <2% CaCO3. Test results from the interlaboratory testing of the low range method is presented and compared with the results from the original ANPA method in the paper.

Feb 27, 2013

By James J. Scott

To the safety engineer, mine planning engineer, and mine inspector associated with an underground operation, stability of the underground structure is of the utmost importance. In the United States in 1961 rock falls killed 167 miners, crippled many more, and cost the industry a fortune in lost equipment and production. Much research has been carried on to try to find ways to eliminate this loss of life and property. Within the past few years the interest in rock mechanics as a science has been at its highest point, Private industry, government agencies, universities and foundations have launched studies to gain a better basic understanding of the stability of underground openings.

Jan 1, 1966

By M. Manrique

Various pyrometallurgical methods for treating Ilmenite and Zircon concentrates are reviewed. Laboratory experiments, using a thermal plasma reactor, have been performed to evaluate: the conversion of ilmenite to TiC or TiC-Fe and the conversion of zircon to ZrC or ZrC-SiC. Results are examined and possible processing routes are identified.

Jan 1, 1996

By P. van der Veen

The objective of this paper is to analyze the evolution of the strategic drivers of the mining sec-tor over the last half century, which has been guided by a varying and expanding list of motivations. While companies cannot survive for long unless they are making profits, the strategic drivers of the industry have gone far beyond profits since at least the mid-1970s when environmental concerns began to be taken seriously. For the most part, these forces have followed global trends and public opinion, but they have been shaped and magnified by the significant, often dominant role that the mining sector plays in many economies. While the mining sector used to be primarily motivated by the first pillar of sustainable development -i.e. the economics pillar-, in the 1970s the second environmental pillar became an important factor in decision making, and in the 1990s the third social pillar emerged as a major driver.1 The entrance of new strategic drivers has also had considerable impact on technological and organizational developments in the mining industry; however, technological changes, driven by cost reduction considerations, have in turn impacted the strategic drivers of the industry, resulting in the need for further technological and organizational developments.

Jan 1, 2007

By Robert L. Wade

The two primary goals in underground coal mining are to improve safety and to lower mining costs per ton through increased productivity. However, as evidenced by the drastic decrease in. productivity since the enactment of the 1969 Coal Mine Health and Safety Act, (the Safety Act), these goals appear to be mutually exclusive. Millions of dollars have been spent in the res, arch and development of systems to solve this problem. Before the Safety Act, "productivity had experienced a 25-year history of continued increases ...? (Douglas, 1980). But since its enactment there have been dramatic decreases in productivity accompanied by phenomenal increases in mine costs. Labor trends, depletion of the more readily minable underground coal reserves and other factors have contributed to this situation, but the dominant factor is undoubtedly the Safety Act itself. To illustrate, prior to 1969 underground coal mine production was much greater than surface mine production but since then underground mine production has been declining at a rate greater than the overall growth rate of total coal production.

Jan 1, 1985

By T. Gouri Charan, G. V. Rao

A spherical agglomeration process for the separation of scheelite fines of less than 30 µm in very low concentration of 0.04% WO3 in a binary mixture with quartz fines of less than 30 pm has been described. A concentrate containing 14% WO, with more than 90% recoveries could be achieved by means of anionic sodium sulfo succinate collector at pH 3.5 and also with commonly used anionic sodium oleate at pH 10.5 as per the conceptual flowsheet suggested. Such a process is envisaged as commercial potential for the recovery of fine-grained scheelite present in the tailings of gold plants as found in India.

Jan 1, 1991

By F. Calizaya

This study summarizes the results of various numerical and laboratory experiments per-formed to study the effect of airflow recirculation on gas concentration. The numerical exercises were carried out on a simulated mine ventilation net-work. The laboratory experiments were conducted at the Mackay School of Mines&apos; airflow monitoring system in Reno, Nevada. In both cases, the airflow was recirculated through the system by means of a main fan and a set of booster fans. The booster fans were positioned to produce two types of recirculation: In line and Cross-cut. For each type, various recirculation conditions were generated by changing the booster fan pressure. During each test, the gas emission rate at the simulated working face was kept constant. The study illustrates the conditions under which controlled airflow recirculation may be used to solve a district ventilation problem.

Jan 1, 1991

Projections of coal reserves in Central Appalachia are essential for long-term planning in the region. Annual production is declining in some states, such as Virginia, and mineable reserves for the Central Appalachian Coalfield are challenged by difficult geological, mining, and market conditions. In order to project coal mining longevity in this region, interviews with mining companies were conducted to assist in the determination and assessment of technical and economic factors that impact coal seam mineability. This information was applied to seam and coal reserve data developed by state and federal governments. The results were carefully analyzed to determine the effects of various factors on the overall mineable coal reserve base.

Jan 1, 1998

By P. C. Clark

This paper is an overview of the requirements and concerns for minerals and pigments used in papermaking. The first part of this paper deals with mineral or pigment filling in the actual papermaking process. The second part deals with the pigment or mineral properties that are important in today&apos;s coating processes.

Jan 1, 1993

By Robert L. Grayson

An application of goal programming (GP) in evaluation of proposed purchases of major mining machinery is presented. It incorporates historical operating data compiled on mechanical delays to production time. The goal programming technique, which is an extension of integer programming, is used to maximize an objective function. The objective function combines the capital budgeting evaluation methods of net present value, payback period, profitability index, and total net earnings as goals weighted according to a management preference. The GP method gives an optimal solution to a multiple-goal problem. A sensitivity analysis is performed to determine the effect of an increased production forecast or a tightened budget on proposal selection.

Jan 1, 1982

Invensys’ recently introduced Field Device Manager for Foxboro I/A Series distributed control systems provides the industry’s first solution that takes advantage of both the latest Enhanced Electronic Device Description Language (Enhanced EDDL) and FDT technologies. This combination provides comprehensive lifecycle support to configure, calibrate, commission, diagnose and optimize the performance of any vendors’ foundation fieldbus device. The I/A Series Field Device Manager enables users to take advantage of any EDDL, Enhanced EDDL and/or FDT host deliverables supplied by the device vendor.

Jan 1, 2007

By K. H. Nimerick

Laboratory data and field tests indicate that substantial losses of valuable coal can be caused by wind erosion. Wind tunnel tests show the effects of wind velocity and particle sizing on the amount of coal lost while in transit. Different coals were evaluated to determine the variables associated with wind erosion. The erosion losses can be substantially reduced by using a binder, or crusting agent, to consolidate the surfaces of the coal into a solid mass which resists erosion. This not only reduces economic loss but minimizes pollution.

Jan 1, 1977

By David Butts

Completion of a railroad to the high Tibetan Plateau in Central China has now made it economical to exploit its mineral reserves. Lead and zinc mines are now being established. A potash plant to produce 40,000 tons per year KC1 is now in operation. Plans to produce 200,000 tons per year by 1987 are being implemented. Pilot drilling for oil and natural gas have proved up reserves. Slaughter houses are being constructed to ship yak, mutton and beef from the endless grasslands on the plateau. Research Centers in Xining and Golmud have been completed for the sole purpose of increasing technology and exploitation of the Tsaidam Basin and surrounding area.

Jan 1, 1984