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By T. Wang

A new generated NaNO3 ? NaNO2 ? KNO3 ternary thermal energy storage system which has low melting point as 124°C and high specific heat capacity was studied for the short and long?term thermal stability by using the Thermogravimetric Analyzer (TGA). Based on the actual working condition of molten salt in solar two, the simulated cyclic thermal stability measurement was also conducted. The ternary system demonstrates excellent short ? term thermal stability and thermal reliability after cyclic heating and cooling processes. However, in the long ? term as well as the simulated cyclic stability measurement, large amount of weight loss was observed. Moreover, the stepwise long ? term isothermal study reveals that below 440°C the weight change is minimal and this temperature is viewed as the upper limit temperature of thermal stability for this ternary system. To determine the lost phases at high temperature above the upper thermal stability limit, techniques such as XRD and SEM are used to compare the condition of the salt mixture before and after the long ? term thermal stability study. On the basis of the comparison, it can be concluded that the major weight loss was due to the decomposition of sodium nitrite.

Jan 1, 2012

By Guillermo V. Borquez

The economics of open pit mine design are dictated by three basic elements: cut-off grade, stripping ratio and slope angle. Although these elements are functions of a number of independent parameters, they are interrelated through their influence on the overall economics. The optimum slope angle is the most uncertain element to determine, because rock mass properties are difficult to obtain. However, for preliminary estimation, the slope angle can be determined from the relationship between the probability of failure and the safety factor. The economics of the slope selected will depend on a profit versus risk judgment. In this paper, the author will present an actual case of application of this postulate.

Jan 1, 1977

By K. Oraee

Mining Ventures are considered as high risk projects and therefore managing the risks is inevitable. Risk assessment is an important part of the complex process of risk management, hence applying appropriated and practical methods for ranking the risks associated with projects, can help to perform a better risk management. In this research the applicability of using Techniques for Order Preference by Similarity to Ideal Solution (TOPSIS) method for risk ranking in an underground mine, extracting by block caving method, was studied. Via this method, the risk associated with reserve estimation ranked as the first while in conventional method (P-I Matrix method) located in the sixteenth. Also there were significant differences in ranks of the other risks. Considering the more criteria, with different weights, in comparison with conventional methods, the results comprised from TOPSIS method are more reliable. By implementing this method risks are ranked better and more realistic and consequently then will be managed more efficient.

Jan 1, 2011

By P. Somasundaran, S. E. El-Mofty

A comparison of the IMC Anionic Process and the CLDRI Process, based on pilot plant testing of waste pebble by Jacobs Engineering is presented. Estimated costs for constructing and operating a beneficiation plant utilizing dolomite flotation are given. Research to develop practical flotation processes for removing dolomite from low-grade phosphate rock has been a high priority for the Florida Institute of Phosphate Research. The Institute funded the above pilot plant programs in 1998 and 2000. The Florida Phosphate industry currently deals with the increasing dolomite content of ore reserves by practicing selective mining. Heavy media separation plants installed at two mines to remove dolomite from pebble are not being operated. The flotation separation of dolomite from waste pebble requires that the flotation feed be ground. Grinding liberates the mineral species and produces particle sizes small enough to be floated. Only two dolomite flotation processes, the IMC Anionic Process and the CLDRI Process, have been successfully demonstrated on flotation feed that has not been deslimed after grinding. Deslimed flotation feed, relative to undeslimed feed, has improved flotation performance and reduced reagent consumption. However, for the above mention processes, undeslimed ground feed increases the yield of concentrate because the phosphate desliming losses are avoided.

Jan 1, 2002

By T. Matthews

"One critical factor in mineral reserves reporting, as well as mine-reserves reconciliation, is the impact of dilution and ore loss in the mining process. This paper considers the implications of various factors on dilution and ore loss projections, by orebody geometry, mining method, and ore control systems. We also discuss the implications of resource estimation methodology on dilution for reserves. DEFINITIONS Dilution and ore loss are two critical concepts in mining, which address the differences encountered between modeled grade and tonnages and actual production. Dilution is volume increase and grade reduction caused by multiple factors, chief among which are mining of waste material along ore-waste contacts, mining of internal waste as ore, and misclassification of waste as ore in the ore control process. There are also geostatistical and estimation aspects sometimes lumped with dilution, including the volume-variance effect (the tendency for small volumes of material to include a less regular distribution of grade than large volumes of material). Ore loss is described as reductions of ore volumes in the mining process due to misclassification of ore as waste in the ore control process, exclusion of discontinuous mineralization from mining due to geometry or continuity, and mechanical losses in the mining process. Dilution is typically taken as an increase in tonnes of ore with no change in contained metal (and thus results in a reduction in grade.) (Some workers consider the likely grade of the diluting material as well, particularly in deposits with gradational grade boundaries—this will be addressed later in the text.) Ore loss is typically taken as a reduction in tonnes at average grade of the ore, and thus results in a reduction in both tonnes and contained metal. If model (resource) tonnes are Mt, grade is Mg, and contained metal is Mm, the resource with ore loss (L) and dilution (D) included (Rt, Rg, and Rm) will be:"

Jan 1, 2015

By M. Stefanakis, M. Errington, A. Kontopoulos, J. M. Prevosteau, K. Adam

The Olympias arsenical pyrite concentrate assaying 25 g/t Au, 40% S, 40% Fe and 12% As is highly refractory in nature; an oxidation pretreatment step is required to liberate gold and render it amenable to cyanidation. In the present study mineralogical analysis techniques including Image Analysis, SEM, EPMA, SIMS, Mossbauer, ICP/MS, etc., have been employed in order to investigate the mode of gold occurrence within the Olympias pyrites. Bacterial oxidation was used as a case pretreatment route and bacterially leached products were examined under SEM. The mineralogical observations and the relevant metallurgical and cyanidation test data were combined to establish a correlation between the mineralogical characteristics of the raw and oxidised products and conditions prevailing over the oxidative pretreatment step and the gold liberation achieved.

Jan 1, 1990

By Thomas P. Meloy

As the importance of particle shape in mineral processing is increasingly recognized as an major variable in predicting the behavior of both individual particles and particle systems, whether it be in dense media, froth flotation, comminution or the flow of particles, new method of shape characterization are being developed, particularly for use on image analyzers. These shape characterization methods may be broadly classified into the analytical, empirical and physical formation methods. Discussed are approaches and the strengths and weakness of each of these methods. Moreover old and new shape measuring techniques are reviewed, particularly the new image analysis methods techniques such as Fourier, Haar, Fractal, Walsh and Delta as well as a variety of other techniques such as tabling, the Cascadograph, settling and L/D ratios. Also discussed are the problems of doing shape research, current progress and the future of the field.

Jan 1, 1990

By Z. Henderson, J. R. Saylor, L. Rojas-Mendoza

"Diesel particulate matter (DPM) is a major occupational health hazard in underground mine environments, even with available abatement technologies. Prior work has demonstrated that micrometer-scale water droplets, or “fog,” may be effective in removing significant number fractions of DPM from a conditioned exhaust stream. Here, a series of laboratory experiments are described which demonstrate that such a treatment can remove significant DPM mass from an unconditioned stream. The removal mechanism involved coagulation of the DPM and drops. The fog treatment removed about 45 percent more DPM mass on average than no treatment. Varying engine load, flow rate and fog droplet number density did not significantly affect the results under the range of conditions tested. IntroductionDiesel engines have seen widespread use for well over a century due to their relatively high thermal efficiency and fuel economy (Heywood, 1988). Recently, however, the adverse health risks of diesel exhaust have become increasingly clear. The term diesel particulate matter (DPM) is used to refer to the solid components of diesel exhaust, which are an ultrafine mixture of elemental and organic carbon (EC and OC) and minor constituents including sulfates and metal ash (Kittelson, 1997). DPM is generally considered to occur almost entirely in the submicrometer range. It is classified as a carcinogen (Occupational Safety and Health Administration, 2013), and epidemiological studies have demonstrated a positive correlation between long-term exposure to DPM and other combustionrelated fine particulates and increased cardiovascular and pulmonary diseases (Pope et al., 2002; McDonald et al., 2011). Many of the risks of diesel exhaust are associated with the physical and chemical properties of exhaust components (Heywood, 1988; El-Shobokshy, 1994; Kittelson, 1997). Exposures are generally measured and regulated on the basis of mass concentration. However, DPM number density and particle size are increasingly recognized as critical factors in terms of health outcomes (Bugarski et al., 2012; Kittelson, 1997; Occupational Safety and Health Administration, 2013; Pope et al., 2002)."

Jan 11, 2017

By Gary PE Beerkircher

A brief history of banana screen development and evolution will be presented along with the operational advantages of the large banana screens available in the industry today. Applications of the large banana screens will be presented as well as the economic advantages that the use of large banana screens can offer to the Mining lndustry today. Banana screen installations in metal, non- metal and coal mining applications will be presented.

Jan 1, 1997

By Odd G. Askilsrud, Steinar Johannessen

New powerplants, tunnels and dams are currently under construction at Meraaker to triple the annual power production of a nearly 100 year old power scheme. A total of 44 km tunnels with cross sections varying from 7 m2 to 32 m2 have been excavated in hard rock formations. Ten kilometers were excavated by a High Performance Tunnel Boring Machine (HP TBM). The remaining tunnels have been completed by the drill and blast method, using modem proven equipment and procedures. This paper gives special attention to the TBM drive and equipment selection, including, planning, site organization and performance.

Jan 1, 1993

By John C. Harkey

The paper shares programs that presently use the CDC PLATO System to train individuals in industry. A short history of PLATO development; as a training system is presented with reflection on the major training trends being used to improve training effectiveness. A discussion is offered to describe the benefits of using a system for individualizing instruction. An introduction; is offered showing how one can recognize' individual differences, with an explanation of how the strengths of a computer are used to deliver and manage the training. Simulations of hazardous processes are shown to be one of the most effective uses of the computer for training.

Jan 1, 1979

By R. H. King, D. R. Schricker, R. E. Cameron

Mine managers rely on their experience, section foreman's daily reports and occasional time studies to make important production, maintenance and forecasting decisions. This information is often subjective and imprecise, consumes expensive engineers time, is often biased and is restricted to short time periods. Managers need better information. Furthermore, if a recently purchased machine is being evaluated, a large increase (>10%) in productivity may be obvious, but small increases are usually masked by other variables. In today's highly competitive markets, cumulative small changes are important, especially since managers have already exhausted most available, obvious avenues of improvement. A technique to separate these charges from effects of other variables and to quantify the target effect is necessary. CSM researchers are addressing this need by developing an intelligent decision support system (IDSS). It provides key production and maintenance information to support management decisions by recognizing patterns in mining machine sensor data and representing knowledge about mine management, operations, layout and equipment. A continuous miner section at Western Fuels-Utah Inc.'s Deserado Mine in Rangely, CO is the test facility for the research. Power transducers located in the sections load center provide kilowatt versus time data from continuous section equipment. The IDSS pattern recognition algorithms classify the kilowatt versus time patterns into individual machine operating modes. It produces an output similar to a typical industrial engineering time study but continuously, automatically and without an engineer in the section. It is relatively easy for a time-study engineer to identify the stop and end points of a cycle element and classify it by looking at the machine and glancing at a stop watch. The problem is that monitoring system hardware and software do not have these unique capabilities. Consequently, IDSS algorithms must automatically define the begin and end points of machine tasks and identify the task by recognizing patterns in kilowatt versus time data. However, many mines have file drawers of time-study type data that are not very useful. So, IDSS contains the knowledge representation subsystem (IDSS/KRS) to produce short reports containing only key information. This is difficult because mine environments continually change and information requirements differ for each management level. Consequently, IDSS/KRS must learn and adapt to new conditions in a dynamic mining environment. Western Fuels-Utah owns and operates the Deserado Mine, located about 19 km (12 miles) northeast of Rangely, CO (Upadhyay, 1988; King and Eros, 1988). One longwall and two continuous miner sections produce about 900 kt (1 million st) of coal annually for the Deseret Generation and Transmission Cooperative's 4000 MW power plant located near Bonanza, UT. Three mine monitoring systems control the underground mine, the preparation plant and the unit train load out. Pattern recognition IDSS/PRS produces a listing of begin and end times for each machine operating event as shown is Table 1.

Jan 1, 1991

"During his presentation at the 2016 George A. Fox Conference about the history of public-private-partnerships (PPP) in the tunneling and underground construction industries in New York, Vincent Tirolo, Jr., told a story about how, as a young engineer in the late 1960s, he and others pooled money to purchase a calculator for $75 that had the ability to perform sine and cosine functions. That was a big deal in those days and would make their job much easier. Oh how far things have come. Tunnel and underground construction engineers can now virtually map out and plan entire projects before the first shovel ever breaks ground. And the machines that are used to build the tunnels have advanced in ways that could not have been imagined 50 years ago.The calculator is just one example of innovation in the industry and on Jan. 26, more than 400 industry professionals attended the George A. Fox Conference at the Graduate Center of New York (CUNY) to learn more about the next innovations, new tunneling technologies and what the future might hold for the industry. The conference included sessions on contracting models, rescue and fire life safety and new technological developments as well as an international project spotlight presentation from Nasri Munfah about the Eurasia Tunnel, connecting the European and Asian sides of Istanbul, Turkey.The project, also known as the Istanbul Strait Road Tube Crossing project, was named the 2015 Major Tunneling Project of the Year by the International Tunneling and Underground Space Association.The tunnel boring work for the 3,344-m (11,000 ft) long tunnel under the Istanbul Bosphorus Strait was completed in August, heralding a new era in tunneling.Tunnel boring work was launched in April 2014 with a ceremony with then Prime Minister Recep Tayyip Erdogan in attendance. The work was completed on Aug. 22, 2015 with Prime Minister Ahmet Davutoglu participating in the ceremony."

Apr 1, 2016

The only good news in the exploration sector in 1982-a year plagued by low metal prices and weak demand-was precious metals. Gold in particular remained in the forefront, as it has for at least the past three years. The reason for this is partially due to gold's seeming resilience to conventional supply side factors-such as new production-that normally influence many other metals. Also, with projected production costs of about $6.40-$9.65/g ($200¬$300/oz), modest deposits with average grades can offer an early return on capital investment and good profit potential. Keeping escalating capital costs for new mining ventures within reason has shifted gold exploration efforts in recent years. Many mining companies are seeking relatively low grade, modest tonnage, near-surface gold mineralization. This, of course, leads to lower development costs using open-pit mining methods. Recent refinements in the carbon-in-pulp recovery process also has enhanced the economics of such deposits. Slumping economic conditions certainly played a key role in shaping exploration activity last year. Nearly every major mineral-producing state recorded exploration slowdowns. In Alaska, for example, development expenditures approached the level of exploration spending for the first time in the state's history. This not only reflects major companies' decisions to move toward production but also the economic slowdown. The worldwide recession stopped Nevada's exploration and mining boom "dead in its tracks," said John Schilling, state geologist. The year was one of layoffs and closings for the state's mines and exploration offices, he reported. Similar trends were noted in most other states, especially in the West and Southwest. In the Pacific Northwest, however, exploration appeared to continue at a relatively good pace considering the metals market. In the mining geophysical community, recent advances in telecommunications and microprocessor technology are continuing to provide a positive impact. Many geophysicists have begun using satellite digital communication links to access computer systems from remote sites where using a microcomputer would be difficult. There were also major contributions made in exploration geochemistry last year. Highlights include progress in formulating mineral deposit models, geochemical exploration in glaciated and arid environments, and publication of many informative books. The following state-by-state summary and articles on geophysics and geochemistry provides a detailed view of exploration events throughout the US in 1982.

Jan 5, 1983

By Ian S. Ross

The emphasis in this paper is focussed on dry bulk car go or the same cargo converted to slurry form for ease of handling. It is this type of cargo which is of primary interest to the mining industry whose products it represents to a large extent. The design problems associated with the handling of liquid bulk and of unitized cargo are sufficiently different to be treated separately. This paper then will consider the port handling facilities of dry bulk commodities as part of a system consisting of (1) the movement of products to the port area, (2) the movement of products out of the port area and (3) the handling of products within the port area itself. Expanding within these three components of the total transportation system, the paper will discuss the various difficulties encountered concerning the mode of transport into the port area and the method of handling product from transport to stockpile. Secondly, and before discussing the port area itself and in order to complete the conditions under which the port must operate, the movement of products out of the port area will be covered dealing with such items as the accommodation of the ship, problem associated with the very large ships, optimum berthing arrangements and the need to consider the various costs associated with the vessel. Finally the paper will review within the port or interface area such items as stockpiles, method of recovery, inventory control and an outline of the common design difficulties encountered. In all cases the relative influence on the total transportation costs of each of these dry bulk transportation system components will be considered.

Jan 1, 1972

One of the most challenging and ambitious dump rehabilitation projects in South Africa’s mining industry is being carried out at Greenside Colliery’s smoldering coal dump, which lies adjacent to the N 12 Johannesburg-Witbank highway. Greenside Colliery is the largest coal mine in the Gold Fields Group. It began operation in 1946, the year in which the burning dump had its origins. Today, Gold Fields plans to spend R16 million (about $USS8 million) to encapsulate the dump, bringing it into compliance with South Africa’s Mining Environmental Management Programme, according to Martin Hamer, engineering manager of the Greenside Colliery. The improved environmental management approach will result in reduced sulfur dioxide gas, smoke and dust emisson into the air and an enhanced aesthetic appearance of the dump from the N 12 highway. The objectives of the project are to place and compact coal discard to within the National Institute of Coal Research specifications in order to prevent spontaneous combustion, and to preserve as an asset the coal portion of the discard.

Jan 1, 1994

By F. H. Buttner

Commodity currency intrigues most of us because of the problems it offers to solve for the Third and the First Worlds. What problems might be solved, if commodity currency were to be adopted in the Third World? That is really the question we are probing here right now. It would take a while to think through all their subtle consequences of this question, but, off the top, it might well have at least three important impacts. Most important of these to this audience is relief from unfair Third World competition. Second, it might well liberate Third World economies from financial indebtedness to the First World and give them freedom from the liquidity limitations. The third benefit is that it might help relieve World trade tensions. All three benefits are interrelated. We could start our speculations on the application of commodity currency from anyone of these starting points. But let us use the starting point most important to you, unfair competition to the U.S. mining industry. From there we might wind up with some thoughts on things you, yourselves, can do to improve things.

Jan 1, 1978

By Albert Ruiz

The 2,250-MW, coal-fired Navajo Generating Station located in Page, AZ draws water from Lake Powell using submersible pumps installed in five inclined shafts. Drought threatens to lower the reservoir to below the existing intakes. A system of new steel-lined intake shafts located on the same site was required for uninterrupted plant operation. The small size of the site, and the need to keep the existing system in operation, required detailed designs and placed significant limitations on construction equipment and activities. The Navajo Sandstone that forms the near vertical shoreline of the reservoir is 98 percent very fine grained quartz, highly abrasive and contains highly fractured intervals that presented numerous challenges to drilling the new 152-m (500-ft) deep, 109-cm (43-in.) diameter intake shafts inclined 23° to 26° from vertical. Spatial constraints, submersible pump design and operational criteria required that each shaft have a unique inclination and orientation and hit a small breakout target located 76 m (250 ft) under water. Sophisticated drilling equipment and techniques as well as state of the practice downhole survey technology and methods were used to make adjustments and maintain drilling accuracy with less than 1 percent deviation. Environmental requirements mandated water as the drilling fluid and grout was not allowed in to the lake under any circumstances. The shafts were videotaped and the breakout locations were examined using an underwater remotely operated vehicle (ROV) to verify shaft locations and rock conditions, and to guide placement of pneumatic packers to ensure grout did not transmit to the lake during the steel liner installation. In anticipation of the invasion of quagga mussels, the shaft design included an allowance for a chemical dosing system and a copper-rich alloy at the exposed portions of the steel liner.

Jan 1, 2011

By N. Champigny

The geostatistical estimation of the reserves of an ore deposit is highly dependent on the quality and stability of the variograms of the sample grades. Gold deposits commonly show a skewed grade distribution. The few high grades at the tail end of the distribution produce unstable variograms that are difficult to model. If these grades are cut to a lower grade value or removed, more stable variograms are obtained. However, outlier grades may make a deposit economically viable, and their cutting or removal should be treated with caution. To reduce (but not to eliminate) the effect of high grades, a transformation of the raw data can be performed. Most commonly used transformations are: logarithm, gaussian anamorphosis, rank and indicator. Variograms of the transformed grades are resistant to high grades and present a clear structure. The weak point of data transformation appears when grades are estimated by kriging; the estimates are very sensitive to slight variations in the parameters of the back-transformation. More robust variogram estimation procedures can also be used, but often these procedures are not suitable for skewed grade distributions as they are based on an assumption of a contaminated normal distribution. The Porgera gold deposit in Papua New Guinea has a highly skewed grade distribution, with grades ranging from 0.01 to 3500 g/t and a coefficient of variation greater than 5. For the geostatistical estimation of the high grade zone of the deposit, the influence of the high grades was quantified by calculating and comparing the following variograms: raw grades, raw grades with the highest grades removed and transformed grades. The study confirmed that there is no general method for handling high grades in a geostatistical reserve study. Several methods should be tried to quantify the influence of high grades.

Jan 1, 1991

By K. K. Bhattacharyya

Vast deposits of lignite occur in the Gulf Coast states and northern plain states. Lignite resources are cited to be over 43 billion tons in the Gulf Coast states. An additional resource of 16 billion tons are reported in North Dakota (Jackson, Smith, 1981). All lignite in the U.S. is mined at present by the open pit method. Draglines and scrapers are primarily used to remove the overburden. Bucket-wheel excavators are also being considered for new mines in the planning stages. Lignite seams are mined using front-end loaders, shovels and trucks, or Easi-miners. The depositional environment of lignite is weak sedimentary soils and rock. Ground water is often encountered within the mining depth. Surface water resulting from heavy rainfall or snow melt contributes to the problems of mining. Mining depths of up to 60 m (200 ft) are under consideration. Draglines exert additional loads on the highwalls and spoil piles. The combination of any number of these factors may cause instability of the slopes. Bearing pressure, trafficability, and settlement can also be a problem for excavation and loading equipment.

Jan 1, 1982