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By J. Slivnik, A. Stergarsek

[The site] [Z]irovski vrh uranium ore deposit is located in the extreme north-western part of Yugoslavia, some fourthy kilometers from the capital of Socialist Republic of Slovenia, Ljubljana, not far from the Italian and Austrian border. The sandstone type deposit of uranium ore with medium grade is located in a foothill of Julian Alps. The site shows some typical conditions for this region, which demand special attention in respect to the incorporation of an uranium treatment facility into environment. Among these specific conditions the following site characteristics should be mentioned: - populated area of agricultural and recreational value, - unconvenient climatic conditions with excessive rainfall and long lasting temperature inversions in the winter time, - very pure surface and underground waters which supply the drinking water reservate for large area including the capital of Slovenia, - sharp relief, - unconvenient geological structure. The choise of technology The intention to produce uranium and at the same time respecting the natural characteristics and existing uses of the site made the design of the ore treatment facility relatively difficult one. In general, there were two basic alternatives available perform the task. First alternative was to adopt the usual technological flowsheet with wet tailings disposal and with discharge of used water i.e. liquid effluents into the river. In order to prevent the negative impact of such technology on the sourrounding area sophisticated water purification installation and costly measures in wet tailings disposal e.g. impermeabilisation of large areas by concrete injections, large dam constructions, uncertain capturing of the water sources should be employed. Second alternative was to modify the usual flowsheet by employing the maximal recycling of liquid effluents to the process and to dispose the solid

Jan 1, 1980

By A. L. Mular

Steady-state material balances calculated from data measured at various locations around process units are useful for many purposes, such as metallurgical accounting, on-line control, and the development of mathematical models. Often it is possible to calculate material balances by several independent procedures when excess measurement information, i.e., redundant data, is available. Clearly, if the data were collected without measurement errors, a theoretical condition never found in practice, all material balances calculated from redundant data would be in agreement. The real situation is that error exists in practical measurements, so that the results of material balances determined from available optional procedures differ. Consequently, best fit computational procedures to improve the material balances by taking measurement errors into account have been formulated. Such procedures can be used also to judge whether measurements are grossly in error due to either faulty observations or defective data sensing devices. A variety of mathematical techniques are available which serve to adjust raw data. The adjusted data permit mass balancing that does not depend on the computational method. To illustrate the need for an adjustment procedure, Table 1 shows a raw data set acquired around the Brenda Mines Ltd. No. 4 grinding circuit shown schematically in Fig. 1. At least seven optional ways to calculate a circulating load ratio may be employed. These are shown in Table 2 where, depending upon the calculation [ ]

Jan 1, 1979

By Ross W. Smith

Many studies have been made of the microflotation of quartz (1,2,3,4,5,6) and alumina (3,5,6, 7,8) using various anionic and cationic hetero- polar hydrocarbon surfactants as collectors. A few studies have been made on these minerals using amphoteric hydrocarbon collectors ( 9,10, 11,12) and only a few studies have been made on the use of fluorocarbon surfactants as flotation collectors (13,14). The present investigation compares microflotation response of the two minerals in hydocarbon and fluorocarbon collector systems of the anionic, cationic and amphoteric types. An attempt is made to relate flotation response of the minerals to their electrokinetic behavior and the pKa values of the collectors.

Jan 1, 1979

By Rong Guo, Qi He, Jinsuo Zhang

"Coal mine ranks No.1 among the 6 major high-risk industries, so it is no doubt that the senior managers in the coal mine bear more stress than other industry executives. The massive working stress results in serious influences on the physical and mental health of the senior managers of coal mine, which might also induce the safety risk in the coal mine. Therefore, to evaluate the senior managers’ working stress and put forward strategies of mitigating the stress is of great theoretical and practical significance in improving the physical and mental health of the senior managers and reducing the safety risk in the coal mine. The research on the working stress has been made in the western countries for almost 50 years, China began the research in the mid and late 1990s, the research is spread across multiple industries including education, medical treatment, computer and aviation. However, there is little research on the senior managers’ working stress of the coal mine, so the available literatures are few. In the paper, we, based on the working stress model of Robbins and through questionnaire survey, analyze the element composition of the senior managers’ working stress of the coal mine; then, we construct the evaluation indicator system of the senior managers’ working stress of the coal mine based on the individual factor, organization factor and environment factor; after that, we determine weights of each evaluation indicators by using the improved triangular fuzzy number weight method, and set up the evaluation model of the senior managers’ working stress of the coal mine on the basis of the fuzzy comprehensive assessment method. At last, in accordance with the model, we evaluate and analyze the working stress for the senior managers of some typical coal mines, and diagnoses the major sources and intensities of the senior managers’ working stress, and then propose corresponding strategies of mitigating the stress."

Jan 1, 2017

By D. W. Jahn

Road construction in the near future will require contractors to guarantee that a project will remain trouble free for years after the project has been completed. These guarantees will challenge aggregate producers to become technically proficient in judging performance of their products. Testing procedures are described that may be used to predict performance of concrete and asphalt pavements before being committed into a construction project, and may also be used as quality assurance tools during construction to monitor performance as construction proceeds.

Jan 1, 1995

By E. Steiakakis

This paper presents in detail the procedures followed and the results obtained in order to determine the stiffness parameters of the calcareous marls found in the lignite mines in Ptolemais, Northern Greece. Triaxial tests were performed on representative samples of the inner burden marl and the marl which underlies the lignite bearing series of the region. The tests were conducted under drained conditions, with controlled loading (including an unloading-reloading loop), while the axial strain was measured externally as well as with displacement transducers mounted directly on the specimen (Hall Effect sensors). The geotechnical parameters obtained (i.e., cohesion, angle of friction, stiffness modulus, stress-strain relationship), were subsequently used for simulating the triaxial testing with the Plaxis finite element software. Simulation results are in good agreement with the experimental results. The resulting material model can then be applied to modeling the mobility that is expressed during the excavation of the open pit mines.

Jan 1, 2005

By R. L. Atwood

This paper discusses the metallurgical and Manufacturing input to Merrill-Crowe plants. Topics treated are pregnant solution chemistry, clarification, degassing, zinc addition, product filtration, accounting, and costs.

Jan 1, 1985

By Ayman A. El‑Midany, Hassan E. El‑Shall, Kerri‑Ann A. Hue

Modification of clays is necessary for the zearalenone (ZEN), as long-chain mycotoxins, removal. The organic-cations were usually used to modify the clay hydrophobicity to accommodate the large mycotoxin molecules. In this study, tri capryl methylammonium (TCMA) chloride and common corn oil were used in clay modification. Several characterization techniques such as XRD, FTIR, and TGA were used to identify the d-spacing changes after modification either by TCMA or corn oil. The results of applying the TCMA-corn oil-modified clays in ZEN removal indicated a noticeable improvement where more than 90% of ZEN could be removed in vitro at acidic and neutral pH values. The success of eliminating a high percentage of ZEN molecules is due to the expansion of intergallery spacing as a result of TCMA surfactant intercalation within the clayforming layers. The removal percentage does not depend only on pH but also on the amount of clay used. In addition, the ZEN removal in the presence of corn oil is better at acidic pH and small clay amount where the ZEN can be fully removed.

Sep 27, 2021

By R. Schuerch, G. Anagnostou, R. Poggiati

"The paper presents dimensionless design diagrams for estimating the stand-up time of a tunnel face in saturated ground of medium-low permeability. The diagrams cover a wide range of ground parameters and apply to shallow tunnels (overburden less than two diameters). As the time-dependency of the face stability in water-bearing ground is associated with the consolidation process in the soil ahead of the tunnel face, the stand-up time is determined by means of hydraulic-mechanical coupled spatial stress analyses. The results presented are important for tunnel engineering practice, e.g. when estimating the feasibility of atmospheric interventions in the working chamber of a closed shield. INTRODUCTION The response of water-bearing medium-low permeability ground to tunnel excavation is time dependent. The time-dependency is due to a transient seepage flow process that is triggered by the excavation and develops slowly over the course of time. Experience shows that the short-term behavior the ground is more favorable than the long-term one: the deformations increase with time; the tunnel face may be stable initially and fail only after some time. The time over which the tunnel face remains stable is called the stand-up time. This paper investigates the time dependency of the tunnel face stability assuming that all time effects are due to consolidation rather than creep. This assumption is reasonable for shallow tunnels crossing water-bearing soils. In the problem under analysis, the unsupported tunnel face remains stable under the undrained conditions prevailing after excavation, but collapses before reaching the drained conditions prevailing at a steady state. The assessment of the stand-up time is important from an economical point of view for both mechanized and conventional tunneling through weak water-bearing ground, as a long stand-up time removes the need for face support or ground improvement works during standstills, thus saving time and money, while short stand-up times require hyperbaric interventions or the implementation of costly and time-consuming auxiliary measures."

Jan 1, 2016

By George Biro, Christoph Mueller

A number autonomous operations is in place in several, mainly in fenced areas, where safety is assured by locking off the entire area for other traffic. However autonomy can be brought much further if functional safety is assured and a real mixed traffic of autonomous and manually operated vehicles is possible. MobileTronics has created a modular software and control framework for autonomous machines. The paper covers application examples in which the deterministic object recognition in combination with probabilistic algorithms and sensors is used as a basis for functional safe certification of mixed traffic autonomy.

Jun 25, 2023

By Salvatore] [Parand

Deep well disposal is a much used and abused term which is the panacea for wastewater disposal in some minds and creates near hysteria in others. It can be the answer to a difficult waste disposal problem, or if improperly employed, can create more problems than it solves. My purpose in this presentation is to focus on the value and limitations of deep well disposal as expressed by New York State's experience and policies. To he sure, I feel a place for such practices docs exist if adequate safeguards are utilized. I shall give a broad brush approach to New York's legislative, geologic and operational concerns and speak briefly on some case histories. I shall not delve deeply into the technological details since I am not an expert in mining exploration or well drilling.

Jan 1, 1973

By Scott G. Britton

Traditionally, water removal has taken a backseat to many other coal mining functions. However, it is a vital part of the total mine support system. In many US coal mines, more tons of water are removed each year than tons of coal. An excellent discussion of general drainage characteristics can be found in Chapter 8 of Elements of Practical Coal Mining, published by SME-AIME. This chapter is organized into three major sections. These are: designing effective drainage systems; constructing the main mine pumping station (static system); and constructing a portable pumping station (dynamic system). Each topic presents a separate discussion of the elements a construction foreman or engineer should consider for effective installation and operation of the mine drainage system. In addition, a list of pumping equipment manufacturers is available to interested persons and follows these sections.

Jan 1, 1983

By William K. Brown

Are the results of an exploration program worth the cost? This is a question I suspect many of you are familiar with and, theoretically at least, it is an easy question to answer. The answer, of course, lies in comparing the future earnings stream the program is expected to generate, to the present value of the cost of carrying it out. While historical costs can be determined without much difficulty, estimating the value of a future earnings stream involves all sorts of assumptions regarding future costs, metal prices, inflation rates and an appropriate discount factor; and in the context in which the question arises, requires additional assumptions about mineral deposits which have yet to be discovered. As a practical matter, this kind of approach isn't likely to produce a very convincing answer; certainly not one convincing enough to satisfy a skeptical audience; nor one likely to temper the illusions of recent converts to mineral exploration, who are convinced that if enough money is spent, profitable discoveries will inevitably follow. Within broad limits, however, I believe it is possible to analyze the costs and results of gold exploration in the U.S.A. over the past 20 odd years in a useful manner. And while such an analysis is imperfect, it will provide some insight into this fascinating subject.

Jan 1, 1983

By J. J. Poveromo

"Iron ore for alternate iron processes concerns alternate iron products designed for use in EAF (electric arc furnace) steelmaking processes. These alternate iron products include both DRI (direct reduced iron), HBI (hot briquetted iron) and merchant pig iron. Merchant pig iron can be produced in conventional blast furnaces, mini blast furnaces (including charcoal BF's) or novel processes such as RHF/SAF (rotary hearth furnace/submerged arc furnace) such as Iron Dynamics or RHF such as Mesabi Nugget. These novel processes are coal based and can use iron ore concentrates or recycled steel plant oxides. The blast furnace processes can use conventional feed materials: pellets, sinter, lump ore and coke. However, DRI and HBI processes are predominantly pellet based but require DR grade pellets that are low enough in acidic gangue (SiO2 and Al2O3) to avoid additional expense in the EAF process This paper will focus on the quality and availability of DR grade pellets for NAFTA DRI/HBI plants but also concentrates for fines based processes and feed materials for merchant pig iron production. INTRODUCTION This paper will outline alternative (to the blast furnace) competitive ironmaking processes and process routes. Within each section the types of iron ore to be utilized will be discussed. Before discussing some of the details of these processes, it may be appropriate to review some definitions and commonly used terms within this industry. DefinitionsDirect Reduction: Reduce iron oxide to metallic iron without melting. Unreduced ore compounds remain as undesirable oxides • Direct Reduced Iron: Iron oxide feedstock exits in same form as entered (pellets in, pellets out; lumps in, lumps out) • Hot Briquetted Iron: DRI that has been hot (1200°F, 650°C) briquetted to a high density pillow shaped briquette • Hot Metal: Molten iron in liquid form, above 2500°F, 1370°C • Pig Iron: Solid product of the iron blast furnace • Residuals: Undesirable elements such as copper, nickel, chromium, tin, sulfur, molybdenum and phosphorus • Gangue: Rock minerals in the iron ore such as silica (SiO2), alumina (A2O3), calcia (CaO), magnesia (MgO). These remain in the oxide form in DR processes. • Reduction: Fe2O3 + 3 CO = 2 Fe + 3CO2 2 Fe2O3 + 3 H2 = 2 Fe + 3H2O (Fe2O3 > Fe3O4 > FeO > Fe)"

Jan 1, 2018

By Francis Martino

There are numerous techniques and predictive models used by geologists and mining engineers to define coal reserves and plan mines. The traditional reserve estimation methods commonly used include the isopach, triangular, polygonal, inverse-distance weighting, weighted-moving-average, and trend-surface methods. Geostatistically-based estimation techniques are now being examined by many geologists and mine planners as a superior alternative to these traditional methods. With today's coal mine development costs often exceeding $100 million, and power generation $1 billion, it is logical that a technique that can indicate the degree of confidence associated with a reserve estimate (fuel supply), and thus also the degree of risk, is highly desirable to the coal producer, the financiers, and those desiring to commit to coal utilization under short or long-term supply arrangements.

Jan 1, 1983

By L. G. Sobral, J. E. Hoffman, T. J. Keefe, A. J. Monhemius, O&apos

The kinetics of electrodeposition of gold from dilute solutions of alkaline KAu(CN)2 at different gold and free cyanide concentrations on a gold rotating disk electrode were investigated by use of a steady-state linear potential scan technique. The design and performance of a laboratory electrowinning cell with a reticulated nickel cathode, operating in the flow-through mode, for the removal of low levels of gold ions from aqueous cyanide media is described. During the batch recirculation of oxygen-free gold cyanide solutions, the gold concentration was reduced from 10 ppm to <0.5 ppm with current efficiencies of up to 80%. The influence of solution flow rate through the cathode and of the pore size of the reticulated nickel foam is discussed. The removal of gold ions from solutions of low ionic strength was also investigated.

Jan 1, 1993

By W. Ghyoot, J. Boonstra, H. Dijkman, C. Buisman, M. Picavet

Paques and Umicore have demonstrated the feasibility of biological treatment of the highly complex Hoboken wastewaters in a1 m3/h pilot plant at Umicore Precious Metals, Hoboken, Belgium. In the first step arsenic was precipitated from copper smelter effluent as As2S3using biogenic produced H2S. Other metals such as copper, lead and cadmium were also removed as MeS to concentrations well below the discharge levels. Subsequently, sulfate and nitrate were removed to low concentrations (<300 mg/l and < 5 mg/l respectively) in high rate engineered bioreactors. Sulfide produced in the sulfate reduction process was recycled to step 1 for metals precipitation. Selenite/selenate was partly removed in the sulfide precipitation step, whereas the excess was biologically reduced and removed as selenium to concentrations <0.2 mg/l.

Jan 1, 2003

By K. Morsy, S. S. Peng

A new method of pillar stability evaluation was proposed. The unique feature about the method is that it estimates two types of stability factors for the pillar. The first stability factor is to measure how much the applied stress at that point is smaller than its strength, and the second stability factor is to predict whether or not the pillar will fail violently. The strain-softening behavior of coal pillars was simulated by the Drucker-Prager yield criterion. A new algorithm that simulates the strain-hardening behavior of the gob was used. A numerical technique to estimate the local mine stiffness (LMS) was introduced and verified by both numerical and analytical methods. A case of massive pillar failure in a room-and-pillar mine was used to define the stability limits for the proposed method.

Jan 1, 2003

By W. Bassow

In June 1972, when the United Nations convened its historic Conference on the Human Environment, only 24 countries had established government agencies with environmental responsibilities. Of these, 11 were in the industrialized world, 13 in the Third World. By 1985, the number had dramatically surged to a world-wide total of 145, with the greatest growth among the developing countries to 110, an increase of almost 1000%.

Jan 1, 1988

By William J. Kohan

Milling has traditionally been considered more art than science. In the last 10 years, significant improvements in process equipment have been made and we are finally taking significant steps toward approaching grinding as a science. Two machines have been at the center of this development. These are the roll press and the high efficiency separator. The former can be considered as a new technology or adaptation of existing i.e. roller mill. The latter is clearly an improvement of existing technology. Other machines have been introduced to a lesser degree and later. Among these are the CKP and Horomill. The purpose of this paper is to provide an over- view of the currently available modifications for operating systems and options for new milling circuits with some comments on their application and history.

Jan 1, 1997