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By T. Panhorst

Evaluation of through-deck blasthole sample reliability at the Lone Tree gold mine revealed a non-systematic bias in the sampling system. Ore is primarily hosted within the Powerline fault zone. Clay gouge, present in the fault zone and typically enriched in gold content, forms agglomerates during blasthole drilling leading to a segregation error during sampling. Replicated samples split from blasthole cuttings piles show through-deck samples to be either significantly enriched or depleted by 1.5 standard deviations or more from the mean gold content of their respective cuttings pile quality of through-deck samples correlates strongly with quantity of clay present.

Jan 1, 1999

By A. W. Khair

This paper presents a strength formula for the design of coal pillars. The formula is derived from results of laboratory experiments, studying the effects of primary factors influencing the strength of the coal specimens/pillars. Five primary factors, significantly affecting the strength characteristics of the coal specimens/pillars were identified and extensive laboratory investigations were carried out. The five primary factors were namely 1) coefficient of friction between loading platens and coal specimens, 2) elastic properties of the loading platens, 3) coal specimen geometry, 4) coal specimen size, and 5) rate of loading. Four to nine levels of variation for each primary factor on the strength of coal were studied. An empirical formula, implementing the variation of the primary factors affecting the strength of coal specimens/pillars, has been developed. A comparative analysis of the results provided by this and some well known formulae is also presented.

Jan 1, 1994

By A. R. Laplante

A test to determine the amount of gravity recoverable gold (GRG) in an ore is described. Typical GRG results are given; an error analysis is detailed; possible uses are discussed. Of the 38 samples tested, the lowest GRG content was found to be 25% (most below 25 11m, or 600 mesh), and the highest 94% (most above 300 11m, or 50 mesh). The average GRG content was 63%, with a standard deviation of 19%. Error analysis shows the test to be reproducible within 5 to 10%, depending on the size distribution and grade of GRG, and the sample extraction protocol. When using the same primary sample, reproducibility improves, 2 to 5%, depending on the amount of gold coarser than 850 11m (20 mesh) and sample weight. The test has been applied to greenfield project and retrofit applications, to determine the suitability of gravity recovery. For existing circuits, it has been coupled with a model of gravity recovery for optimization studies.

Jan 1, 1996

By D. W. McGlashan

[Comideha;tion o 4 chyakd- chem and aLtuctund phopetttiu o auRdide nm&, The in~o/uncction gained h ;to be uned ;to iM;tmph& ( I! dnukey bho hen mind-aundacu , ( 2 ) modidicakio~n 06 ;the minmd n~tdacu, and (3) eac;tiom at ;the mind adac fnom ;thu e baic din oipfina, concep;tc, wLth hegattd ;to .the changen kha;t awtgacu undehgu, heac;tiom kha;t might take place, ,the geom&y 04 ;the inkmduce, ;the nkde 04 diddmenk &om and iom in ;the intmdace, and okhm phyaicd and chemicd pttopemXu od an intmdace mun;t be developed, weighed and appfied. The au/tho~ ded wah thue concep;tud connidmatiom @om which hypokhuu me n& ko denchibe khe envhomenkd-ivttadaciae hela;tiomhipa doh nevmd nddide minettah, The ch&enge and moltivation in khe hu eattch h in a henhe a deattch doh baic dad and helcctiomkipa needed doh accompfi he&.] INTRODUCTION Qualitative and quantitative explanation of particulate solid separations are unknown entities because of the lack of adequate models and mathematical relationships to explain the activity occur- ring between the solid and liquid phases. It is a transitional region in which it is difficult to ascertain the mechanisms of adsorption of ions, molecules, etc. on mineral surfaces, as well as other secondary reactions which occur in interfacial regions. Thus, in this paper the authors deal with conceptual considerations from which hypotheses are set forth to describe the environmental- interfacial relationships for sulfide minerals.

Jan 1, 1968

By F. G. Crack

This paper is based on the philosophy that the management structure and strategy required for mine construction and development projects are different from that required for routine production and maintenance operations in a mine. The purpose of this paper is to present an integrated approach to the management of mine development projects. This paper highlights the four major aspects of the integrated approach. First, a brief review of the various types of contract documents is provided. Second, the management organization of a project is discussed. Third, the project manager's role and the field supervisor's responsibility are briefly outlined. Finally, the use of scientific techniques for planning, scheduling, executing, and controlling projects is presented. Each of these aspects is important; however, each by itself cannot be expected to bring order or unifying impact to the complexities involved in overall project management. When all these aspects are coordinated, the result will be a sore successful project from conception to completion.

Jan 1, 1982

By Shailendra Chawla, Ashok Jaiswal, Sonu

Side spalling/skin failure occurs due to the high-induced stress in underground structures. In such cases, rock bolting or other support systems are being used to control the skin failure or spalling of the pillar. The nature of these support systems is passive, which acts during the deformation. These support systems restrict the displacement considerably of the side/or roof surface of the excavation. Ultimately, it improves the stability of the structure because of the increment in residual strength of rock mass. It is noted that these passive support systems give very low confinement in the range of 0–0.015 MPa at the onset of failure. As the level of confinement will be very low and dependent with progress of failure, triaxial test was not found practically suitable. Thus, an alternative procedure of testing has been proposed. In the procedure, sides of sample have been restricted little bit by using adhesive tape. It provides the limited boundness on the lateral direction (LBLD) of rock specimen. The uniaxial compression strength (UCS) test has been performed on 30 numbers of cylindrical rock specimens using the servo-controlled stiff testing machine. Specifically, two rock types (medium-coarse–grained and coarse-grained rocks) were studied in terms of stress–strain behaviour so that a full residual strength envelope for each specimen was obtained. This study reveals that the residual strength of limited confined rock specimens has been significantly increased as compared to unconfined rock for both groups of rock types. The average residual strength of LBLD specimens of fine-grained rock and medium coarse-grained rock has been increased around 12 times, and five times as compared to unconfined rock, respectively. The average peak strength of LBLD rock specimens has been increased in the range of 30.5 to 48.6% for coarse-grained rock. The results of this study have been presented in terms of peak strength, residual strength and Young’s modulus of rock, and the post-peak failure behaviour of rock specimens was also critically analysed through a stress–strain curve.

Mar 21, 2024

By B. J. Scheiner

The Bureau of Mines, U. S. Department of the Interior, is conducting research on a dewatering technique for fine particles generated during the mineral beneficiation process that will recover a portion of the water now being lost using conventional waste disposal methods and significantly reduce the time required for land reclamation. The technique utilizes a flocculant, polyethylene oxide (PEO), that forms strong stable flocs that can be dewatered rapidly on static and/or rotary screens. In field tests, phosphate clay waste has been dewatered from a nominal 2.5 percent solids to greater than 20 percent solids. In other field tests, coal-clay waste has been dewatered from a nominal 3 percent solids to greater than 55 percent solids, in addition, small-scale continuous tests have shown that bentonitic clays can be dewatered from 12 percent solids to 40 percent solids.

Jan 1, 1983

By J. Hanna

The University of Alabama Mineral Resources Institute (MRI) has developed a unique process for selective fatty acid flotation of carbon-ate 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 beneficiate a high Mgo siliceous phosphate matrix from south Florida. The modified process includes two flotation stages, one for carbonate removal, as mentioned above, 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 and the phosphate flotation stage produced concentrates analyzing about 31% P2O5,0.7% HgO and 4% insol. The overall P2O5 recovery in the two stages is about 85%.

Jan 1, 1989

By Davar Abi-Zadeh, Cillian Brown, Deepak Kandra

"Grout backfill strategy for a particular subsurface concrete tunnel (~4.9km long, 3.5m in diameter, carrying 20” gas pipeline) was based on achieving 1:100 slope of the fill in order to progressively fill the tunnel, in a series of 350m section. Grout rheology, particularly its non-Newtonian and thixotropic behavior, determines the final fill slope for given backfill strategy. The objective of this study was to simulate the two-phase grout mix backfill process using Computational Fluid Dynamics (CFD) and determine the slope of the fill to validate and optimize the backfill strategy. Three dimensional CFD study showed that for a 500m long tunnel section with a single injection point of grout, given its rheology, it will likely keep flowing without filling the 500m section height wise. Design optimization for filling was carried out using two dimensional studies to make the backfill process “slope independent” by incorporating a 2.5m high bulkhead at ~1,000m. INTRODUCTION As part of a gas field development a 20” onshore gas pipeline is required from the landfall site to the processing terminal some 8km inland. At the landfall site the gas pipeline is routed in a ~5km underground tunnel underneath a bay. For operational reasons and planning consents as well as to mitigate environmental impact based on an environmental impact study, once the gas pipeline and the associated services and spares have been installed, the subsurface gas tunnel will be fully grouted. There will be no permanent access to the tunnel after construction is completed and the site compounds have been reinstated once works are complete. One of the key requirements is that “full grouting of the tunnel” is desired. The grouting material used is a non-Newtonian and thixotropic fluid mixture of bentonite, cement, plasticizer, retarder/stabilizer and water. The tunnel is filled progressively in 350m sections using a combination of existing and new pipework assuming the grout rheology will yield a fill slope of 1:100 in a 350m section. The proposed grouting system used one pump at the grouting compound to pump the grout into the tunnel using the existing tunneling pipework. For the longer runs a second booster pump was used in series to pump the grout to its final discharge location. The filling process is controlled via a system of flow meters, pressure transmitters and a tunnel CCTV system."

Jan 1, 2016

By K. Lang

A test section of the upper most lift and underlying lifts of a large scale copper heap leach operation was instrumented and monitored with advanced wireline geophysics, fiber optics and resistivity electrode arrays. Elemental Capture Spectroscopy (ESC) copper measurements, resistivity measurements from an Array Induction Tool (AIT), electrical resistivity tomography (ERT) and distributed temperature sensing (DTS) with fiber optics provided integrated near real time data about the performance of the heap. During the leaching cycle, ECS provided continuous vertical measurements of copper in the upper most and underlying lifts in the test section of the heap and was used to generate a copper recovery curve. ERT inversion modeling provided high resolution 3D resistivity measurements, which were used to evaluate moisture distribution. DTS measurements of temperature were used to track the PLS front and calculate velocity. AIT induction provided highly precise bulk resistivity measurements. In-situ samplers provided PLS chemistry at multiple points. Properly integrated monitoring data can provide the heap leach operator with information that can be used to evaluate the hydrodynamics and metallurgy of the leaching process in near real time. Problems in the heap, such as pooling, channeling, longer lag and breakthrough times, excess acid consumption, increased solution in inventory, toe saturation and slope stability can be detected in near real time with the in-situ measurements evaluated.

Feb 23, 2014

By Kevin Andrews, Zach Agioutantis

Analysis of Coal Pillar Stability (ACPS) software, released in 2018, integrates numerous empirical pillar design techniques. The ACPS program incorporates methodologies originally available as design tools from the National Institute for Occupational Safety & Health (NIOSH), including Analysis of Longwall Pillar Stability (ALPS), Analysis of Retreat Mining Pillar Stability (ARMPS), Analysis of Multiple Seam Stability (AMSS), and concepts including Coal Mine Roof Rating (CMRR), the Mark-Bieniawski pillar formula, and pressure arch loading. The design methodologies that are the basis of ACPS were developed via analysis of significant amounts of real-world data and have been standards of the United States coal industry for decades. While there are empirical factors built into ACPS, making it ideal for use in U.S. coalfields, the concepts in the program have proven to be applicable in variable mine settings, and the software was developed to allow for user-based, site-specific modifications of key design inputs. Application of ACPS to cases outside the regions for which it was developed must be approached carefully, and continuous development of site-specific data is mandatory. A case study is presented involving the application of ACPS to assess pillar stability and assist future design for an underground lignite mine in Eastern Europe. Assessment of in-mine observations, review of the geology of the lignite mine, and evaluation of specific conditions associated with a failure event resulted in “calibration” of key input factors to ACPS. Scenarios evaluated with ACPS suggest that pillar strength and overburden depth are key factors for the determination of pillar stability and design in future areas.

Jun 25, 2024

By Derek J. Barratt

The existence of a critical size buildup in an autogenous or SAG mill can be predicted from proper examination of drill core and ore samples. Methods of dealing with such critical size in a primary mill are reviewed in the context of ore properties, whether or not pilot plant-scale testwork has been conducted, and also with respect to the design of new plants or the retrofitting of existing operations. The implications of not planning for pebble crushing in situations where it is appropriate are discussed.

Jan 1, 1992

By H. Askari-Nasab, B. Osei, K. Awuah-Offei

The U.S. coal mining industry consumes approximately 142 billion kWh/a of energy. The U.S. Department of Energy estimates that the industry’s annual energy consumption could be reduced by 49%. This constitutes nearly $3.7 billion of potential savings on coal production costs at 5.3¢/kWh of energy. Additionally, with climate change regulation on the horizon, any benefits from energy savings in the near future are compounded by associated reductions in CO2 emissions. Research indicates that operating conditions significantly affect energy efficiency. Modeling and simulation have been shown to be a cheap and reliable means of evaluating the effects of process interactions and operating conditions. The goal of this work was to apply stochastic process simulation to model the energy efficiency of a typical truck-and-shovel mining system and use the model to evaluate production strategies to improve energy efficiency. The research team conducted energy audits of truck-and-shovel overburden removal and used the results to develop regression models describing truck and shovel fuel consumption. The team then built a stochastic simulation model of the truck-and-shovel overburden removal operation and used it to assess a variety of improvement measures by simulation experimentation. Valid fuel consumption models for shovel loading and truck haulage have been formulated, based on the energy audit results. Valid stochastic process models of truck-and-shovel operations have been formulated to study energy efficiency. The following strategies, in decreasing order of impact, provide the most energy savings for truck-and-shovel overburden removal at the mine: (1) shorten haul roads, (2) increase shovel capacity and (3) increase shovel utilization through optimal truck matching. Additional data will be required to adequately describe operator effects on energy efficiency.

Jan 1, 2011

By J. Baz-Dresch

A custom-designed shotcrete system, consisting of an 8-m3 (10-yd3) transit mixer and a shotcrete spray boom carrier, is used bya 2-man crew to transport and place up to 25 m3 (32 yd3) of steel-fiber reinforced, dry, silica fume shotcrete per II-hour shift. Shotcrete is custom blended by a local supplier and delivered predampened. Mix design and quality control is performed with a computer program that develops and graphs a properly balanced mix based upon the materials sieve analyses.

Jan 1, 1991

By Richard C. Corson

The new 9300 TPD sinter plant being built for China Steel Corporation is incorporating the latest computer technology for plant control systems. The control system will use a central computer and distributed micro-processors to control instrument loops and switching logic in the blending yard and sintering plant. All plant functions, including combustion and fan controls, will be controlled by remote microprocessors located throughout the plant, and connected by a communications link to the centrally located computer and control room. The design, programming, construction and operation of a microprocessor based control system presents new challenges to the control engineer. With microprocessors in the control system, more power exists in the individual control loop and many supervisory functions may be added at the loop level. The specification of the microprocessor system and the resolution of hardware design and control system design can lead to development of powerful systems capable of higher level control and optimization functions

Jan 1, 1981

Stillwater Mining Company has an extensive history with tunnel boring machines (TBM) at the Stillwater and East Boulder underground PGM mines in Montana. The first use of a TBM was a 4 m (13 ft) diameter main beam unit at the Stillwater mine starting in 1988, where 6.4 km (4 mi) of tunnels were driven parallel to the J-M Reef orebody on four different levels. TBM?s were central to the development of the East Boulder Mine as two 4.6 m (15 ft) TBM?s drove two 5,639 m (18,500 ft) parallel tunnels to access the J-M Reef; one of these units is still in service driving a 2,591 m (8,500 ft) access West of the East Boulder mine for the Graham Creek project. For the Blitz Project, a 5.5 m (18 ft) diameter main beam unit will be utilized to drive a 6,858 m (22,500 ft) ventilation and rail haulage level East of the Stillwater mine. TBM?s have been preferred method for developing new mines and sections of the J-M reef as the geometry and geology of the Stillwater Complex allow for faster development compared to conventional methods.

Jan 1, 2012

By W. H. Langer

Quaternary alluvial deposits in the modern stream channel of the Agua Fria River west of Phoenix, Arizona, is mined and processed to provide aggregate to the greater Phoenix area. The alluvium occurs as three distinct, stratigraphic layers. Samples from each of the three layers were examined for gravel clast lithology, grain size distribution, and engineering tests, which revealed noteworthy differences in properties. The engineering properties of the gravels are dependent on a combination of factors including gravel clast lithology, the distance the gravel clasts have been transported from their source areas, the age of the deposits, and the degree of weathering. Knowledge of these characteristics may affect the methods that aggregate operators employ to extract and process gravel from the Agua Fria River.

Jan 1, 2010

By Frank Pollard

The Australian coal industry over recent years has experienced the situation whereby exploration and mine development are moving into geographical areas where the coal seams have never been mined to any extent in the past, if at all, and particularly where there is no history of experience in preparation of these seams. Additionally, the demands have been such that the development of a mine up to production stage should proceed with minimum delay. This is a situation which is of some importance and concern, in view of the coal quality requirements now experienced within world markets which can only be met, in most cases, by careful preparation. Costs are such that the preparation plant should operate as required by the situation and with maximum efficiency, which means that laboratoty information of breakage and washability characteristics which are required for preparation plant design should be accurate and available as soon as possible, even to a certain extent during the progress of the exploration.

Jan 1, 1981

By Paavo Eerola

In May of 1984, it was decided that Outokumpu Oy would design and build a new nickel flotation mill to process ore from the newly discovered Enonkoski mine in eastern Finland. Since there hart peen a number of successful process charges in the existing mills, the design effort included the study and incorporation of several new developments, including all-autogenous grinding, "flash flotation", lane cell roughing, large cell cleaning and a computer-based, profit optimizing, process control system. The paper discusses the background and results of those studies, and a description of the resulting mill which will begin production in 1986.

Jan 1, 1985

By Long An, Chao Wu, Yuanhui Li, Xing Sun, Shuai Xu, Changyu Jin

Stage open stope mining (SOSM) maintains the stability of excavation openings by leaving a large number of rib pillars. Affected by the strong unloading due to stage mining and the low width-to-height (w/h) ratio of the pillars remaining, largescale destabilization disasters of rib pillars or excavation openings easily occur when the distribution of ground stress or the size of rib pillars is unreasonable. In view of these problems, a physical SOSM model test was carried out based on an underground metal mine in Chifeng City, China, revealing the deformation and failure characteristics of the SOSM pillar group by overloading. The physical model test results of SOSM and room-and-pillar mining (RPM) with a weak pillar were compared, and the failure process of the SOSM pillar group showed the characteristics of rapid and severe damage. The strength difference between a weak pillar and the adjacent pillars enhanced the stress rebalancing effect and extended the failure process of the pillar group. Similar to the SOSM pillar group with a low w/h ratio, some high-strength pillars can be used to avoid large-scale destabilization disasters caused by the synchronous failure of pillars.

Mar 8, 2023