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By S. Lin, Y. J. Wang

Through an example three fan ventilation network concepts of subsystem solution and characteristic curves of a multiple fan ventilation system are introduced. The major steps of defining a subsystem, working out the subsystem equations, constructing a solution curve and a characteristic curve, and determining the operating points of the reference fan and the ventilation system are systematically demonstrated through three and two-dimensional curves. Also briefly discussed are the main features of a subsystem characteristic curve.

Jan 1, 1993

By Y. Topkaya, R. E. Johnson, D. Buttinelli, B. R. Palmer, A. Geveci, L. Stoppa, C. Lupi, F. Pochetti

Representative samples of a composite mixture of three typical Cu/Zn complex sulphide ores, namely Black-, Yellow- and Altered-ore, from the Cayeli deposit in Turkey, were used for leaching tests in 2.2 M FeCl3, or 1 M CuC12-2 M NaCl solution in the temperature range from 313 K to 363 K (40O to 90O C), with and without the presence of an organic solvent for elemental sulphur, such as CCl4. The leaching rates of copper and zinc were quite high, as expected, in FeCl3 solution and complete recovery of both metals was obtained at the highest temperature when the solvent was present. However in CuC1, solution, extraction yields of the order of 95% only for Cu and Zn were achieved and the positive effect of the solvent was not clearly shown. The kinetics curves of Cu leaching by FeCl3 indicated a model of reaction rate depending on the particle surface, as in a chemically controlled reaction, in tests with the presence of CCl4. Without the solvent, or in CuCl2 media, the model of the diffusion controlled reaction seemed to prevail. Values of apparent activation energy, in both of the leaching processes, were determined and compared with those reported in literature.

Jan 1, 1993

By J. Robert Denny

The impact of the computer revolution--so pervasive in some industries--has been less startling in the mining industry. Computer techniques have been used successfully to provide drill hole calculations, contour maps, and a variety of conventional maintenance scheduling, and accounting applications. But it is our experience that the real economic payoffs lie in the engineering application of computers to mine planning and the use of systems engineering techniques for mine operations. Since 1964, Newmont Mining Corporation has been engaged in systematic research and development of computer techniques in a variety of mine planning applications. The general objective in using computers has been twofold: first, to arrive at a viable, near-optimum plan for mining a particular orebody, and second, to decrease the financial investment by reducing the man-hours required for mine planning. Three major phases in the evolution of these computer techniques for mine planning are discernible. In phase one, the machine capability for duplicating manual drafting and contour mapping was developed. The necessity of including all recognized geologic characteristics is obvious. Capability for properly incorporating structure, stratigraphic trends, and other geological features was a significant aspect of phase one development.

Jan 1, 1970

By Gregory E. Korbin

The effectiveness of pre-reinforcement as an immediate stabilization measure as well as its contribution to the permanent stabilization of a tunnel were studied through the use of physical (Figure 1) and numerical models (1). Physical models were designed for the investigation of two pre-reinforcement systems: first, reinforcing far ahead of the main excavation (Figure 2); second, spiling reinforcement ahead of the face (Figure 3). In both cases, the use of reinforcement was responsible for permanently stabilizing an otherwise unstable opening. Data from the physical models were used to calibrate a numerical model from which additional information on long term behavior, methods to account for the capacity of a pre-reinforcement system, and the mechanisms involved were ascertained. These studies indicated that pre-reinforcement can stabilize a rock mass effectively as it reduces deformations and thereby deterioration due to strain softening, provides rock mass confinement leading to increased available strength, and maintains rock arch continuity allowing for increased tangential stress in the immediate vicinity of the opening. Field studies verified the capacity of spiling reinforcement to restrain initial deformations.

Jan 1, 1976

By J. Pang

The mechanisms of chalcopyrite oxidation in alkaline solutions have been studied using cyclic voltammetry and AC impedance spectroscopy techniques. Analysis of the impedance spectra using equivalent circuit models has made it possible to suggest layerwise growth of surface films. From the value of equivalent circuit parameters, properties of the surface layers are inferred. These properties change substantially with the change in oxygen and/or collector concentration in solution and give rise to changes In contact angle and flotation response. In agreement with prior investigations, the present study shows that flotation recoveries alone cannot be used to determine the effect of collector on flotation of chalcopyrite. The rate of flotation is a more sensitive parameter to determine the role of collector on floatability of chalcopyrite.

Jan 1, 1989

By Zachary D. Jones

"Construction projects involve a great many risks. The risk that material prices will increase during construction or that the work under construction will be destroyed by fire, storm or some other act of God are just a few examples. In tunneling or other underground projects, one of the most significant risks is that the subsurface conditions encountered during construction will differ from what is expected. Each of these risks must be accounted for, managed and, ultimately, the duty of one party or the other to bear. The primary tool used to allocate the risks among the parties is the construction contract.How construction contracts allocate the risk that subsurface conditions will differ have changed substantially over the past century. Today, construction contracts typically allocate the risk through a series of provisions. The first is the differing site condition or changed condition clause. That clause, when included, typically provides that the owner bears the risk that the subsurface conditions will differ from what is indicated in the contract documents or what is reasonably expected. The second clause is one that provides that the contractor must conduct a reasonable site investigation and bear the risk of any conditions that such an investigation would reveal. The third provision includes disclaimers that are often included in geotechnical data provided by the owner (or the owner’s engineer) to the contractor which attempts to limit the information on which the contractor can rely. Because these risk-allocating devices seem to be somewhat conflicting, a brief discussion of each provides critical insight in understanding how the modern construction contract allocates the risk of differing site conditions.At the start of the 20th century, construction contracts looked substantially different than they do today. For example, one contract for the construction of a public water tunnel in Chicago, IL, drafted around 1895 contained the following clause:The contractor must take the work entirely at his own risk. No extra allowance will be made for quicksand, hardpan or boulders."

Jan 1, 2014

By Harrison R. Cooper

Approximately 40 concentrators throughout the world have successfully adopted computer control for flotation circuit operation since 1969. Successful use of flotation control, gaining up to 2% efficiencies, has largely derived from effective employment of on-stream slurry analyzers and integration of key measurement data through digital processors. Requirements for reliable measurement have also led to improved functional reliability in magnetic flow meters, pH, reagent feed, and other key elements. Methods used in computer control of flotation will be reviewed and variations in operating philosophies will be described with reference to the approaches taken to flotation automation.

Jan 1, 1979

By J. R. B. Lima

The present work emphasizes the selection in the separation of the apatite/calcite by the direct anionic flotation versus the double flotation, with a reverse second stage of the Jacupiranga phosphate ore. The double flotation would allow the obtaining of two concentrated solutions: one of them mainly constituted by a calcium carbonate material (CaCO3) and the other one, phosphatic (apatite). The calcium carbonate concentrated solution is used for the production of cement. The presence of phosphatic material in the calcium solution is not desirable, phosphor being a harmful element to cement. On the other hand, smaller quantities of calcite in the phosphate concentrate would represent a substantial economy in the processes of production of phosphated fertilizers. These processes make use of sulfuric acid to the solubilization of the apatite and the presence of calcium material consumes acid. Also that, when carbonates are solubilized, unwanted products are formed resulting in losses in the process and diminishing the quality of the fertilizer produced. These characteristics are discussed in the paper and are compared to another Brazilian phosphate ore, the reverse route of which can be considered more adequate. The results are discussed according to recent discoveries, and special emphasis is given to the use of corn starch and its crucial role in promoting the selection in the direct flotation process.

Jan 1, 1993

By S. B. Castor

Proceeds from industrial mineral mining in Nevada were approximately equal to those from metal mining during the barite boom in the late 1970s and early 1980s; however, since then the economic importance of industrial minerals has been overshadowed by gold mining (Fig. 1). The total value of industrial minerals mined in Nevada increased by about 60% during the 1980s, reaching an estimated $306 million in 1990 before falling slightly in 1991. The state's most important industrial mineral commodities, in order of estimated value, are aggregate, lithium carbonate, diatomite, lime, cement, gypsum, barite, clay, silica, and magnesia (Fig. 2). Industrial minerals produced on a smaller scale are colemanite, dimension stone, dolomite, perlite, salt, and zeolite. In 1991 industrial mineral commodities other than aggregate were produced at 39 operations in Nevada. Most of these operations are located near the two major metropolitan areas of the state, or along the major transportation routes (Fig. 3).

Jan 1, 1993

By R. Day

Nahcolite is a naturally occurring sodium bicarbonate mineral found principally in the Piceance Creek Basin of northwest Colorado. An 8-m thick nahcolite bed, 610 m below the surface, is the target of this first commercial nahcolite mine. A chamber and pillar mining system is developed by solution mining parallel 8-m tall by 18-m wide by 450-m cavities initiated along horizontally drilled holes. Hot water leaching, cooling crystallization and flash drying is the process. The sodium bicarbonate product is consumed by the baking, animal feed, industrial and acid rain abatement markets. A project overview, emphasizing the combination of horizontal drilling and solution mining technologies, will be presented.

Jan 1, 1994

By C. A. Garcia

The solvent extraction of gold cyanide from alkaline cyanide solutions with monosubstituted guanidines, bis disubstituted guanidines and a tetrasubstituted guanidine was investigated. The guanidine functional group is protonated in alkaline solution and the guanidinium cation is stabilized so that the aurocyanide anion can be extracted even at -pH 12 if an appropriate carrier is used. Typical aprotic carriers including both aliphatic and aromatic solvents limit gold extraction by guanidines to pH 10; whereas the presence of an alcohol extends gold extraction to pH 12. UV spectroscopy suggests that the alcohol facilitates protonation of the guanidines, stabilizes the guanidinium cation, and facilitates gold extraction at high pH.

Jan 1, 1993

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay, Cicek Sena, Zhao Haochen

"Analysis of Longwall Pillar Stability (ALPS) and Analysis of Retreat Mine Pillar Stability (ARMPS) treat the pillar as a passive structure that is designed to carry overburden dead-weight. This dead-weight is calculated by simple rules based on the geometry of the mining, such as “tributary area theory,” “pressure arch theory,” and “abutment angle theory.” Although the pressure arch loading approach indirectly accounts for the generally stiffer overburden response of narrow and deep panels, it does not include the effect of specific geology of the overburden in load calculations. The relationship between successful pillar layouts and overburden geology can be incorporated into the load calculation by using the Ground Response Curve (GRC) approach.This paper introduces the GRC modeling methodology to investigate the effect of overburden geology and excavation geometry on load transfer mechanisms using seven field measurement case studies from four U.S. mines. It was also shown that the modeling methodology used to derive GRC in this study approximates mining-induced stresses and deformations within 5% of the values measured in the field.INTRODUCTIONFrith and Reed (2017) stated that current state-of-the-art pillar design methods ignore the overburden mechanics and use estimated dead-weight of overburden to compute pillar sizes. In the United States and around the world, overburden loading is typically estimated by simple geometric rules, generally with the tributary area theory (TAT). The specific overburden mechanics, structural competence of the overburden strata, geology, in situ stresses, and overburden/pillar interactions are typically ignored. However, these important mechanical responses affect the stability of the mine pillars and openings; therefore, they also affect the safety of the mine workers.Research conducted by the National Institute for Occupational Safety and Health (NIOSH) after the Crandall Canyon mine disaster (Esterhuizen, Mark, and Murphy, 2010) showed that small panel width-to-depth ratios and stiff-strong overburden result in a reduction of the observed pillar loads, much smaller than the TAT estimate. In fact, as a response to the Crandall Canyon disaster, Mark (2010) implemented a pressure arch loading approach into the latest ARMPS program to recognize the inherently greater stability of narrow panels at depth. The pressure arch approach is a first logical step to introducing non-tributary area loading into the practical ARMPS program. Although the pressure arch loading indirectly accounts for the generally stiffer overburden response of narrow and deep panels, it does not include the effect of specific geology and mechanical response of overburden in the load calculations."

Jan 1, 2019

By P. A. Rittenhouse

Reserves of potash are more than adequate to meet future world demand for this primary fertilizer nutrient. The bulk of both reserves and current production is located in only a few countries. Recent attention has focused on potential development of smaller reserves to supply local markets in developing areas of the world. However, most new capacity in the next decade will be built in countries with large current production and reserves. The paper reviews current and future projects that will add to the world supply of potash.

Jan 1, 1985

By B. R. Green, Ms. M. H. Kotze

Ion-exchange fibres (IEF) were prepared by the ir­radiation grafting of styrene onto polypropylene, which was then subsequently functionalized. Strong- and weak-base exchangers were prepared and evaluated Tor their ability to extract gold cyanide selectively. The IEF prepared had loading capacities similar to those of the corresponding resins and they had good selectivities for gold cyanide when contacted with a mixed metal-cyanide solution. The expected advantage of IEF over granular exchangers, that of faster kinetics, was illustrated. The strong-base Iibre in particular seemed to be very effective for the extraction of gold cyanide from dilute solutions such as return-dam waters.

Jan 1, 1990

By Oliver W. Marsden, John O. Marsden

This paper presents the results of a hypothetical case study that evaluates the potential transition of a large copper mining and extraction operation to 90% renewable energy. The case study considers three phases to accomplish such a transition; phase I considers installation of renewable power generation at the site to meet a portion of the current electric power needs, phase II considers conversion of diesel combustion mining equipment to electric equipment, and phase III considers implementation of renewable energy generation coupled with energy storage systems to provide approximately 90% of the total mine site energy requirements. The paper evaluates the results in the context of a range of purchased electric power unit costs ($0.065, $0.100, and $0.135/kWh) as well as various carbon tax scenarios ($0, $5.00, and $37.30/t CO2). While the case study is hypothetical and considers a range of assumptions, it clearly identifies a pathway to potentially economically viable transitions to a renewable energy platform for mining companies. This represents an approach that mining companies can use to help to meet emissions targets, as well as social responsibility and reporting requirements.

Jun 4, 2021

By HJ Marais, J A. van Niekerk

An investigation was initiated by BILLITON Process Research and Gold Fields Limited for the efficient removal of thiocyanate and cyanide from leach solutions. This led to the development of the ASTERTM process, an acronym for Activated Sludge Tailings Effluent Remediation. The biological degradation of thiocyanate and cyanide in effluents provides an alternative treatment to the more traditional processes. This occurs with a large number of micro-organisms which include bacteria, actinomycetes and fungi. Cyanide and thiocyanate are degraded to ammonia and carbon dioxide. Most forms of cyanide-metal complexes are generally removed through a co.mbination of oxidation and sorption into the biofilm/biomass. Since the ASTER™ process has commercial applications, a patent has been lodged for the ASTER™ process. A culture containing thiocyanate degrading organisms has been deposited with the Australian Government Analytical Laboratories (AGAL). The identification of the bacteria is in progress. Tailings arising from a cyanidation process tend to contain cyanide and thiocyanate. The presence of these species prevents the recycling of this water upstream to a bioleach circuit due to its toxicity to the bacterial culture. Increasingly stringent legislation for the land disposal of cyanide containing solutions also necessitates the treatment of the solutions before disposal.

Jan 1, 2000

By Michael R. King

The application and use of steel fibre reinforced concrete in precast tunnel lining design is a growing trend due to its advantages in performance over plain concrete, and ease of manufacture compared to traditionally reinforced concrete. However, the design process and performance characteristics of the material are poorly served by current codes and standards. This paper provides some basic design guidance for segmental linings, and compares the material properties for the different material options. A typical example is considered to compare the possible results of lining arrangement and thicknesses for a plain, reinforced, and fibre reinforced design solution.

Jan 1, 2005

By A. Haghighat

The Missouri University of Science and Technology?s (Missouri S&T) Experimental Mine is a teaching and research facility which has been excavated in limestone by mining engineering students over almost 100 years. The mine is currently being extended to a second level. Available fans for ventilation are two surface fans of 24 kW and two underground booster fans of 12 kW. The design of a ventilation network in conjunction with multi surface fans and booster fans entails a complex procedure. Ventsim Visual software modeling has been used for network analysis to determine the optimum surface and booster fans locations, blade settings, and speeds. Both natural and mechanical induced ventilation pressures have been taken into account. Three working faces on each level have been designated as target points that minimum air quantities are required. The model has been calibrated against a pressure and quantity survey. Design of ductwork, door/stopping positions and different fans characteristics have been examined. The optimum flow rate at identified working faces, efficiency and minimum energy losses and annual network power cost determine the best scenario. The optimum design has been determined for the ventilation network for the next 100 years. The optimum flow rate across working faces is the key criterion selected.

Feb 23, 2014

By W. W. Simpson, S. A. N. Sheya

A procedure was developed by the U.S. Bureau of Mines for recovering gold, silver, cobalt, copper, and zinc from a massive sulfide ore by a hydro-metallurgical process. The procedure consists of (1) oxygen pressure leaching; (2) iron, arsenic, and copper removal from the leach solution by precipitation; (3) selective extraction of cobalt and zinc from solution; (4) electrodeposition of the cobalt and zinc from the strip liquor; and (5) cyanidation of the pressure leach residue to recover gold and silver. The results are discussed in terms of efficiency of metal recovery and conclusions drawn as to possible benefits and broad applications of the process.

Jan 1, 1990

By M. Rosenshine, R. W. Barbaro

This paper presents a cyclic queueing model that evaluates the productivity of a shovel-truck materials haulage system. For a cyclic queueing problem with exponentially distributed service times, a cyclic queueing model provides exact solutions in a fraction of the time that simulation takes to produce an approximate solution. The model is applied to an example problem, and the results are validated with simulation. Simulation is used to show that the assumption of exponentially distributed service times and steady state are not serious problems. A cyclic queueing model can be used to quickly obtain an accurate assessment of the productivity of a shovel-truck system.

Jan 1, 1988