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By R. Bruce Tippin

because of the mineral's high monetary value and the spotty occurrence of free gold in the deposit. Setting up a plant sampling procedure by simply applying the usual statistical sampling theory was questionable. Two sampling concepts were considered in the sampling study: o a sufficient number of assays can be taken such that the average determined from these individual samples represents a known quantity of ore. o a sufficient weight of sample can be taken such that when assayed it represents a known quantity of ore. The test program included evaluation of sampling techniques, sample preparation and analytical methods. The overall sampling program is depicted in Figure 2.

Jan 1, 1985

By J. Hanna

The University of Alabama Mineral Resources Institute (MRI) has developed a unique process for selective fatty acid flotation of carbonate gangue from sedimentary apatites (francolite) in the pH range of 4-6 without collector conditioning of the pulp. The process, which does not require an apatite depressant, was modified to benepciate a high- MgO siliceous phosphate matrix from south Florida. The modified process includes two flotation stages, one for car- bonate removal and the other for phosphate recovery from the siliceous gangue. The selective flotation separation of the carbonate and phosphate from siliceous constituents of the matrix at various pH levels and collector dosages are discussed. In the carbonate flotation stage, about 70% of the MgO was rejected in the froth. The phosphate flotation stage produced concentrates analyzing about 31% P2O5 0.7% ? 5 MgO, and 4% insol. The overall P2O5 recovery In the two stages was about 85%

Jan 1, 1991

By S. J. Knoll, D. F. Scott, T. J. Williams

Highly stressed rock in stopes continues to be a primary safety risk for miners in underground mines because it can result in failures of ground that lead to both injuries and death. Spokane Research Laboratory personnel investigated electromagnetic (EM) emissions in a deep under-ground mine in an effort to determine if these emissions could be used as indicators of impending catastrophic ground failure. Results suggest that (1) there is no increase in the number of EM emissions prior to recorded seismic activity, (2) some EM signals are generated during blasting, (3) interference from mine electrical sources mask seismic-generated EM signals, (4) EM emissions do not give enough warning (compared to seismic monitoring) to permit miners to leave a stope, (5) the distance an EM signal can travel in the rock is between 17.7 and 39.6 m (58 and 130 ft), and (6) current data acquisition systems do not differentiate between EM signals generated from seismic activity and random mine electrical noise. These results preclude monitoring EM emissions as precursors of impending catastrophic ground failure.

Jan 1, 2004

By T. C. Rao, Vanangamudi. M., J. P. Barnwal

Experiments were carried out on 76 mm laboratory heavy medium cyclone treating -2.0 t 0.5 mm coal and on two 600 mm industrial heavy medium cyclones treating coal in the size range -13.0 t 0.5 mm. The variables studied were spigot diameter and feed medium gravity. The generalised distribution curve for the separation of coal in these heavy medium cyclones has been defined by the equation [ ] The specific gravity of separation SG has been found to increase linearly with increase in feed medium, gravity (SGf). The relationship for SG of industrial cyclone is given as 50 SG = -6.801 t 6.463 SGf t 0.0327 Spig 50 -0.02625 SGf. Spig. Further, the probable error for the separation has been found to be linearly related to (SG50 - SGf ) according to the equation [ ] The model equations developed have been used to select appropriate levels of operating conditions to achieve an increase in the yield by about 2 to 4% without affecting the quality of the product.

Jan 1, 1990

By Garry G. Lowder

The regional geologic setting is essentially a volcanic island arc built upon an oceanic basement, consisting of basalt and minor pelagic sediments (the Tinombo Formation of Eocene - lower Miocene age. Trail et. al. 1974). -- An east-west chain of intermediate and acid calc-alkaline volcanoes (the Bilungala Volcanics) was built on the oceanic basement during the Miocene. The Bilungala Volcanics are flanked to the north largely by contemporaneous andesites and volcanoclastic sediments of the Dolokapa Formation. During middle to upper Miocene time the Bilungala Volcanics were invaded by large masses of predominantly dioritic intrusive rock and it is within one of these dioritic intrusive complexes, the Bone Diorite, that the cluster of porphyry copper systems occurs. Renewed volcanic activity in the Plio-Pleistocene produced acid pyroclastic rocks (the Pinogu Volcanicsi whose distribution is controlled by present-day topography. Structural trends, largely interpreted from SLR imagery, are pre- dominantly NW or NIWJ. The right-lateral Gorontalo Fault, which trends hW through the town of Gorontalo (Katili, 19691 is the most prominent structural feature. Many of the major structures in the Tapadaa district have similar orientations and may be sympathetically related to the Gorontalo Fault.

Jan 1, 1976

By Dennis C. Martin

Construction of the Cerro Colorado on-off leach pad in northern Chile required about 3 Mm2 (32.3 million sq ft) of fill over an area of about 600,000 m2 (6.5 million sq ft) in irregular terrain with relief of up to 40 m (130 ft). Earthwork construction was completed in about six months using mine waste, placed in 4 to 6 m (13 to 20 ft) lifts with mine haul trucks. The lift thickness was reduced and the compactive effort increased in the upper 10 m (33 ft). This was done to develop a mat for additional resistance to possible differential settlements due to the modest density of the fill and dynamic (earthquake) conditions. A single 2-mm (80-mil) high-density polyethylene (HDPE) liner was used below the leach pads. This was protected from the loading and unloading equipment by bedding and cover systems. It consisted of screened sand, gravel and silt as the bedding and cover layers and a heel of screened gravel and primary crushed low-grade ore.

Jan 1, 1995

By K. O. Groves

Although chlorine oxidation has been found to be effective in destroying the CN ion, an excess of chlorine is needed to drive the reaction to completion. This often results in the formation of residual chloramines, which are toxic to aquatic life and often regulated by various states. The interhalogen, bromine chloride (BrCl), has been found to be just as effective but without the formation of persistent, residual chloramines. The hydrolysis and subsequent disproportionation of the highly-polar BrCl molecule essentially yields a solution of hypobromous acid (HOBr) and nonoxidizing hydrochloric acid (HC1). Studies have been carried out to directly compare the mechanism of CN destruction with chlorine and bromine chloride.

Jan 1, 1982

By J. Köppel, K. Kovári, Ch. Amstad

INTRODUCTION The measurement of displacements in soil or rock in the vicinity of underground openings provide valuable information for a better understanding of the behaviour of the structure. On the basis of systematic observations conclusions can be drawn concerning - safety of the opening in the various stages of excavation - effectiveness of the support measures - nature of the rock pressure to be expected - influence of the construction of the opening on neighbouring structures (settlements of foundations, underpassing other tunnels etc.) - comparison of theoretical predictions with the actual structural behaviour (1). Today there are several types of suitable instruments available that can be employed at reasonable costs for such investigations (2). The most important ones are the multiple point borehole extensometer, the inclinometer and the multiple point borehole deflectometer. As is well-known, the extensometer only measures the displacement component in the borehole axis, while the inclinometer and the deflectometer provide monitoring of rock mass movements normal to the borehole axis. In the following a new instrument is described, which has been given the name Extenso-Deflectometer ISETH. In this single piece of equipment certain features of the above-mentioned three types of borehole instruments are incorporated. it enables the measurement of all three components of the displacement vector at consecutive points along the borehole, the axis of which may have any direction in space. This device is portable like the inclinometer. A simplified version

Jan 1, 1979

By R. G. Bradburn

The events which led to computer control of the grinding circuit at Brenda Mines are described, beginning with mill operating philosophy. High production rates are encouraged so that, despite severe upstream disturbances, a manual control method to meet this philosophy had developed. Unfortunately, due to the time interval between manual control adjustments, losses in production resulted. An analog control method was devised and, although superior to manual control in some situations, was found to suffer from several practical limitations. The data logging capabilities of a control computer seemed warranted. Circuit test- work combined with an analysis of operating data showed that (1) metallurgical personnel, at times could increase production rates by as much as 10 percent over that achieved by grinding operators, (2) the chosen data base required an increase of 2 percent or more to be statistically significant and (3) for a 2 percent increase there would be a significant rate of return of investment in a computer installation, Consequently one grinding circuit was fully instrumented, and a rented control computer was installed by Brenda personnel. Prior to installation, Brenda metallurgical and instrumentation personnel were trained in the use of the computer. An experimental program was devised with short and long term objectives. The short term objective was to develop a practical control strategy which would yield immediate production improvement. This goal has been met as described in this paper. Statistically significant increases in excess of 2 percent have been established. Work is being completed for the permanent installation of computer control on all four grinding circuits at the present time. Long term objectives are (1) off line analysis of the circuit using mathematical models of process units, (2) on line experiments to study alternative contol tactics, and (3) possible expansion of computer facilities to the crushing plant.

Jan 1, 1976

By Irwan Halim, Bhoshaga Mitrran Ravi Chandran, Kevin Huynh

Tunnel segmental lining design constitutes a significant iterative process where modeling and numerical analysis are factors in deciding the number of segments, their dimensions, gasket placements, as well as the locations of dowels and bolts. Consequently, these modifications lead to revisions in the final drawing details. However, the current tunnel engineering practices lack systematic solutions that effectively bridge the gap between the iterative design process and efficient visualization of completed drawings due to the time- consuming nature of redrawing. This paper presents a pioneering application of AI-driven solutions including using Autodesk's API, for the Northside Interceptor Tunnel (NSIT) Project. It showcases the automation of drawing design and the real-time visualization of modifications, thereby streamlining the drawing process.

Jun 23, 2024

By H. C. Juvkam-Wold

The design of an aquifer depressurization system is discussed. The system uses a number of wells surrounding a mine shaft to reduce the aquifer pressure in the vicinity of the shaft. The effect of various parameters such as number of wells, wellbore diameter, time and well location is discussed. It is concluded that, with a properly designed depressurization system, the aquifer pressure and the water inflow rate to the shaft may be reduced to less than 15X of their potential values in the absence of wells

Jan 1, 1980

By A. H. Baldo

Covers a very broad spectrum of problems and solutions. The problems are multitudinous and their solutions are sometimes simplistic, sometimes ingenious and sometimes within a very broad interpretation of the law. However, one thing is quite certain: the problems and their solutions will have a direct impact upon corporate and personal well being. First of all, why does one mine in a foreign land? Since the Bronze Age, when ancient man discovered the metallurgy of copper, tin and zinc, intrepid souls have been wandering afield searching for and exploiting those mineral deposits which would create wealth and security for his city-state or community.

Jan 1, 1981

By Richard E. Ellwanger

Methods of utilizing flocculants as settling and filter aids for mineral processing slurries are reviewed. Broad chemical classifications and techniques for proper dilution, multiple addition, and combination treatments are discussed. A variety of custom built and commercially available systems for make up and delivery of flocculants to the application points are in use through- out the mining industry. Those concepts which, in the author's opinion, are particularly important to the successful make up and use of flocculants are presented in relationship to the available make up and feed systems. Actual industrial applications are included in the presentation.

Jan 1, 1980

By Kim A. Lapakko, David A. Antonson, Jon R. Wagner

This study examined the potential of mixing rotary kiln fines (RK fines), a waste product generated when limestone is converted to lime (CaO), with acid producing mine waste to provide 1) short-term mitigation by neutralizing acid produced by iron sulfide oxidation and 2) long-term mitigation by facilitating the passivation of iron sulfide mineral surfaces. Five loadings of RK fines were mixed with 75 g of Duluth Complex rock to produce neutralization potential (NP) added: acid potential (AP) quotients of 0,0.11,0.22,0.66 and 1.1. The mixtures were subjected to wet-dry cycling laboratory testing for 585 weeks. The rock alone produced acidic drainage, with pH decreasing below 4 after about 20 weeks of reaction and ultimately reaching the approximate range of 3.3 to 3.5; sulfate release did not decrease over time. The RK fines elevated pH and inhibited sulfate release for time periods which increased with the mass of RK fines present. The pH of drainage from the 0.11 quotient (NP added1AP) loading decreased below 6.0 after 75 weeks of dissolution and decreased to 3.6 after 117 weeks, at which time the reactor was terminated. The duplicate 0.22 quotient loadings of RK fines decreased below 6.0 after 95 and 170 weeks. The former was terminated after 117 weeks, and the latter reached a minimum pH of 2.8 after 512 weeks. Drainage pH from the 0.66 quotient decreased below 6 after 581 weeks. For the drainages which acidified, the cumulative calcium release prior to pH decreasing below 6.0 was 92 to 103 percent of that initially present as calcium carbonateloxide in the RK fines. The pH of drainage from the 1.1 quotient typically remained above 8.0 throughout the period of record. Sulfate concentrations in the drainages decreased while the neutralizing fraction of the RK fines was present, but increased after this fraction was depleted.

Jan 1, 2000

By Matthew Deutsch

A common casualty of modern openpit mine optimization is the assurance that the resulting design is actually achievable. Optimized mine plans that consider value and a bare minimum of precedence constraints do not, in general, translate into practical, operational mine designs that can be used in the field. Ultimate pits may come to a sharp point at the bottom. Schedules may require taking small parcels of material from many disparate areas of the pit in a single period, and grade control polygons may be ragged, narrow and not minable with realistic equipment. In this paper, these three fundamental openpit mine optimization problems are addressed by encoding them as maximum satisfiability problems. Maximum satisfiability provides a useful framework for problems that are nonlinear and may guarantee the optimality that metaheuristics cannot.

By B. Catalano, D. Ifrim

The Annacis Island Outfall Project includes two TBM bored tunnels with face pressures above 3.5 bar, with an internal diameter of 4.2 metres. This paper discusses the innovative approach to TBM tunnelling and TBM design at the Annacis Outfall Project. The TBM custom design includes a 3.6 m OD core machine manufactured by Herrenknecht and a 5.0 m add-on by the Contractor (Bessac), acting as an extension kit, with optimized gantry design to accommodate for short tunnel drives and quicker launches. This novel design approach produced safety improvement, cost and schedule savings while streamlining logistics of TBM retrieval.

Dec 1, 2022

By J. Tavares

It is no mystery why the mining industry has such lofty safety standards. In dealing with Mother Nature and gravity, the combination of the two can create significant hazards from high wall and tunnel collapses to huge landslides. The loss of production from a major disruption could be enormous. The price tag on the loss of human life is immeasurable. The evolution of geotechnical instruments and software has been ongoing for years. But the biggest innovations have occurred during the era of cell modems, internet, and wireless networks, allowing for real time data and alarms to be delivered globally anywhere and anytime to one?s computer, laptop and smartphone. Yet in some ways you can thank the urban construction projects for developing much of the technology in use by today?s mines. Due to the density of population and the billions in dollars of structures and infrastructure in cities throughout the US and the world, urban projects have faced intense scrutiny for years. Out of this scrutiny was born the necessity of real time automated monitoring of instrumentation and sensors, a defence against catastrophic failures, and real time early warning systems through alarms that can and do saves lives. It is also possible to identify areas of concern with subsequent remediation prior to failure.

Feb 23, 2014

By N. Arbiter

During the first four decades of flotation practice, close to 200 machine designs were patented, although only about a score were ever used commercially. By the end of that period, the rigors of use had resulted in obsolescence of most pneumatic cells, with a few mechanical cells dominating the field. After World War II, newer designs began to appear but most were modifications in varying degrees of older designs with special features added. Of the dozen or so most recent developments, almost all are pneumatic, relying on compressed air instead of impellers for motive power, although in several cases pumps supplement compressors. Table 1 lists a few of the more fully documented new cells, with their significant characteristics, along with similar characteristics of a widely used mechanical cell. New designs in general are emphasizing: bubble size control; in several cases, methods for delivering feed directly to the froth; methods for introducing and dispersing air through nozzles, eductors, packed beds, or permeable walls; and variable cell volumes, relative to capacities, ranging from very small, with less than a second of retention time, to the largest, with retention times of over 20 min. An important question is the extent to which any of the newer designs are based on locating weaknesses in current mechanical cell designs and then using these as a starting point for innovations. In the present study, the key subprocesses which must take place in a cell are outlined; mechanical cells are analyzed to establish where weaknesses may exist; and then alternative subprocesses are considered which could effect improvements. COMPONENTS FOR CELL DESIGN It is assumed that mineral surface chemistry has been modified as necessary to provide optimum potential floatability. While the cell process may affect this to a degree, cell design is primarily concerned with actualizing the existing potential floatability. The cell design problem is to provide more effectively for the following: 1) Dispersion of air to obtain an optimum bubble size distribution at an optimum ratio of air volume to feed volume. 2) A hydraulic environment which permits most effective contact of potentially floatable particles with bubbles: [Table I - Cell Comparisons* Cell Type Mechanical Column Deister Miller ASH No. of units Multiple Single Single Single Retention time min.10/20 17/27 3.8 ca. is Capacities mt/m3s 0.022/0.066 0.066/0.20 0.11 10.4 st/ft3d 1/3 0.3//0.9 m5.0 469 Air hold-up % 15/20 20 n.a. 50/80 Air escape velocity m/s 0.015/0.0200.020/0.025 n.a. n.a. ft/m 3/4 4/5 n.a. n.a. * References: Mechanical (Harris, 1976,1985), (Bassarear, 1985); Column (Travis, et al. 1987); Deister (Zipperian and Christophersen, 1985); ASH (Air-Sparged Hydrocyclone) (Miller 1989).]

Jan 1, 1989

By Richard J. Goff

Technical Support, one of several major organizational units in the Mine Safety and Health Administration, provides technical assistance to the mining community in all areas of health and safety. One of its many areas of expertise is noise control. Depending upon the needs of the operator or inspector, the services provided can range from locating major noise sources to actually building noise controls. Over the years a vast amount of knowledge has been obtained as to what will work and what will not. DESIGN GOALS While many noise controls have been developed for mining equipment and operations, the most acceptable (ergo successful) have achieved the following design goals: - a noise level reduction of at least 5 decibels; - minimum interference with production; - inexpensive to install; and - effective in reducing low frequency noise.

Jan 1, 1984

By E. G. Noble

Microbial leaching is being investigated as a method for recovering the metal values from a domestic low-grade manganese wad ore. Early work showed that heterotrophic microorganisms present in the ore solubilized manganese when cultured in a glucose-mineral salts medium. More recent shake-flask tests using molasses as the sole nutrient source extracted 97 pct of the manganese from minus 300- µm ore in 4 weeks. Column bioleaching with the molasses medium solubilized 99 pct of the manganese from minus 6.3-mm ore in 50 weeks. The results of flask, column, and lab-scale heap bioleaching studies are presented.

Jan 1, 1991