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By Nancy C. Mohn

?Even though the age of many existing coal units exceeds 30 years, these units continue to perform with excellent reliability and at a competitive cost with other fossil fuel units. ?NERC data shows a consistent increase in availability for all utility coal generation ?With the opening of power markets, the challenge for coal is to produce competitive electricity while meeting increasingly stringent, and costly environmental limits. ?During the 60s and 70s, subcritical steam power plants dominated the market. The emphasis was on scale-up to larger MW size units. ?In the last decade, we have seen interest in a broader set of technologies with new drivers: ?Fluidized bed technology was developed to respond to increased environmental requirements, particularly with lower quality fuels ?Supercritical pressure units have gained interest for both fuel cost savings and reduced emissions due to higher efficiency.

May 1, 2001

By J. C. Haptonstall

Stoping methods at the Homestake Gold Mine through 1978 had been traditional overhand cut-and-fill, shrinkage or square set. High costs, low-productivity and safety concerns prompted the mine to search for and adopt a "bulk mining" technique as a primary stoping method. Blasthole stoping had been successful but it is very development intensive, and was not suitable for the mine's accelerated mining program. Vertical Crater Retreat stoping was selected, and today accounts for over 50% of ore production. Case histories representing both the successes and failures of VCR stoping in the mine are discussed.

Jan 1, 1986

Fifty to 75 million years ago, hydrocarbon-bearing rocks were formed in the Green River formation of Colorado, Wyoming and Utah. The hydro- carbons can be extracted from these rocks, marl- stone but misnamed oil shale, after crushing and intense heating. At about 900°F the marlstone decomposes to produce liquid shale oil. A press release from the Colony Development Co. describes a process which may permit, for the first time, economically feasible access to shale oil. Shale oil has resisted economic extraction for almost three centuries. According to the USBM, a patent was issued as early as 1684 in England to produce "oyle from a kind of stone". France produced oil from marlstone in 1838 and a dozen years later, Scotland started an oil shale industry, producing kerosine, that lasted nearly 100 years. In both countries, the process involved crushing the stone and retorting it to decompose the kerogen-a long and costly process at that time. In 1859, Edwin L. Drake brought in the first oil well in Titusville, Pa., and shale oil faded into oblivion.

Jan 8, 1965

By Garry Johansen, Andrew McCallum, Sandy Gray, Gary Patrick, Jennifer Abols

"The authors challenge the traditional thinking that whole ore cyanidation followed by Carbon in Pulp (CIP) or Carbon in Leach (CIL) should be applied as a standard process in the majority of gold processing flowsheets. The concept of whole ore leaching by using cyanide can result in unnecessary environmental and capital risk. Alternative, currently available technologies can be used to provide the desired level of gold recovery at a much lower installed cost and less impact on the environment. Gravity concentration, alone or in conjunction with flotation, can produce a gold bearing concentrate that can then be fed directly to a batch or continuous intensive cyanidation unit.The InLine Leach Reactor (ILR) is an intensive cyanidation unit developed by Gekko Systems of Australia. Advantages of this technology include significantly reduced capital outlays for greenfield plants or plant upgrades and increased investor returns. Reduction of onsite cyanide and carbon inventories improves plant safety, materials handling and site security. By using direct electrowinning to treat the gold bearing solutions produced by the ILR, the need for a conventional carbon stripping circuit is removed. Potential also exists to increase grind size – saving energy, further reducing capital and operating costs and decreasing the environmental impact of a mill. Detoxification of cyanide before the release of solution to the tailings dam can minimise tailings disposal and containment requirements.When used in the right application the proposed process will have little or no impact on gold recovery and may actually increase recovery for complex ores. Areas applicable to this type of treatment include: plants in environmentally sensitive regions, lower tonnage higher grade deposits, coarse gold deposits, and preg robbing ores - some of which may not currently be economically feasible using standard processes and flowsheets. We have provided three examples of such projects, where an alternative to whole ore leach and CIP or CIL has delivered these benefits."

Jan 1, 2003

By B. G. Cousins, B. O’Rourke, C. Spence

"Some non-flotation chemicals are added to flotation circuits directly and indirectly to control issues such as scaling and dust in other areas of the operations. Since dosage levels are generally not high, a standard laboratory float test may not be able to determine the effect of a specific chemical on the productivity of the flotation circuit. This paper presents a laboratory testing protocol that uses kinetic float studies to test the effect of normal to extreme doses of antiscalant and dust chemistries (5–100 g/t). Results indicate that this protocol helps to predict potential interference by a particular chemistry on the flotation circuit.RÉSUMÉ Certains produits chimiques ne servant pas à la flottation sont ajoutés directement et indirectement aux circuits de flottation afin de contrôler des problèmes tels que l’entartage et la poussière dans d’autres secteurs des opérations. Étant donné que les niveaux de dosage sont généralement faibles, un essai standard de flottation en laboratoire pourrait ne pas être en mesure de déterminer l’effet d’un produit chimique spécifique sur la productivité du circuit de flottation. Le présent article définit une procédure d’essai en laboratoire qui utilise des études cinétiques de flottation pour vérifier l’effet de doses normales à extrêmes de produits chimiques antitartre et anti-poussière (5 à 100 g/t). Les résultats indiquent que ce protocole aide à prédire l’interférence potentielle d’un produit chimique particulier sur le circuit de flottation."

Jan 1, 2016

By Pesic. Batric

A novel chitosan-pyridoxal-epichlorohydrin was synthesized and evaluated in our laboratories. The evaluation was achieved by performing kinetic and equilibrium studies of copper sorption. The parameters examined were pH, temperature, concentration of copper, particle size and selectivity of copper sorption against iron, zinc, cadmium and cobalt. It was found that pH was the most important parameter, and sorption of copper increased with pH increase in the range pH 2.5-6.0. The low activation energy of the sorption reaction, 1 1.13 kJ/mole (2.66 Kcal/mole), showed that temperature was not an important parameter. The synthesized chitosan was selective against iron, zinc, cadmium and cobalt. The selectivity with respect to last three metals was achieved by the kinetic difference of sorption, as sorption of copper was much faster than for other metals. Iron (Fe2+) does not adsorb on chitosan. The mechanism governing the sorption of copper is intraparticle diffusion. This finding was supported by the dependance of copper sorption on the square root of time, the low activation energy, and the fit of experimental data in the diffusion through the product layer equation.

Jan 1, 1994

By Charles D. Litton

Laboratory experiments were conducted to determine the responses of a prototype smoke detector and a commercially available photoelectric smoke detector to smoke particles generated from various combustion sources. The prototype smoke detector combines optical scattering measurements with ionization chamber measurements in order to reduce/eliminate nuisance alarms due to the presence of airborne dusts or diesel exhaust particles. The commercially available smoke detector is designed for use in harsh environments where airborne dust represents a major problem due to both nuisance alarms and detector contamination. In the experiments, the responses of the two detectors were measured when exposed to smoke particles from the exhaust of a diesel engine and from a variety of fire sources, including wood, coal, styrene butadiene rubber, and No. 2 diesel fuel. For the solid fuels, data were obtained for both smoldering and flaming combustions. This report describes the experiments, their results, and the use of these results as they apply to early-warning fire sensors capable of the rapid and reliable detection of fires in atmospheres that may or may not be contaminated by either airborne dust or the products produced from diesel engines.

Jan 1, 2008

By J. B. Dilworth

I. INTRODUCTION. THE purpose of this paper is, first, to give a general account of a little-known coal-district of SE. Kentucky, its topography, drainage, and mineral resources, for those who may be interested in its economic development; and secondly, so to describe the geologic features of the field as to furnish available data to those engaged on the broader problems of Appalachian coal-geology. The data from which the major portion of the paper has been prepared were obtained, in professional investigations for private individuals and corporations, within the last decade. The area under review, defined by a heavy line on the map, Fig. 1, lies between Little Black and Pine mountains, and extends from Harlan on the west to a N-S. line crossing Looney creek 3 miles from its mouth on the east. This area can be divided for description into a Western and an Eastern Division. The character of investigation pursued in the Western Division, below Fugitt creek, was very different from that employed in the Eastern. In the former, only a rapid reconnoissance was attempted : such coal-openings as had been made by prospectors or by citizens in obtaining fuel were visited, their sections measured and, in many instances, sampled. Elevations were obtained barometrically and approximate locations sketched on a small-scale map. In a field where the coals are so well opened, the reconnoissance method gives a very fair idea of the number and character of the principal beds and their relative positions, and affords much evidence for their correlation over wide areas, without permitting the more refined work required to discover all the seams of the measures and to determine the details of geologic structure.

Feb 1, 1912

By R. P. King

Knowledge of the behaviour of flotation machines had developed and increased considerably over the last few years. Although much work remains to be done on the study of the fundamental processes that influence the collection of hydrophobic particles at an air-water interface, there is enough information to permit the building of realistic models of the gross flotation behaviour of various ores. These models serve as an ideal base for the development of simulation techniques for the steady-state behaviour of entire flotation plants that consist of a large number of individual flotation machines. Simulation techniques have a very real role to play in assisting with the design of new plants and in improving the operation of exisiting plants. Recently, highly efficient data-logging systems have been introduced on flotation plants. These systems are based on the on-line measurement of volumetric flowrate, pulp densities, and metal contents, and they generate enormous quantities of information regarding the operation of the plant. Unfortunately, this information is largely wasted at the present time because efficient data-reduction techniques, although available10 are not in common use. Simulation techniques play a central role in such data reduction because they form the essential link between the fundamental kinetic flotation processes on the one hand and the plant data on the other.

Jan 1, 1974

By S Larbi-Bram, F Shi, E Manlapig

Mining companies have recognised that characterisation of particle breakage plays an essential role in the design and optimisation of comminution circuits. Recently the JKMRC comminution research team has developed a new breakage model incorporating the effect of particle size, and a new breakage characterisation testing device, called the JK Rotary Breakage Tester (JKRBT), which allows rapid testing of particle breakage under high energy single impact and low energy repetitive impact conditions. The latter is believed to be the dominant breakage mechanism in AG/SAG mills. Existing devices, such as the JKMRC Drop Weight Tester, are not suitable for performing repetitive impacts since they are too time consuming. Positive feedback received from mining company sponsors to the new technology has prompted the JKMRC to further validate the device and the model through a formalised experimental test program on professionally designed and manufactured JKRBT machines. The first JKRBT was installed at the Anglo Research laboratory in Johannesburg in March 2007 and four more major mining companies will participate in the project in 2008, with commercial release expected in early 2009. The JKRBT has the potential to revolutionise ore testing, with applications in laboratory impact breakage characterisation of rock samples, drill cores, coal and other materials. It also stands poised to significantly advance the process control of comminution circuits since it is readily adaptable to on-line ore hardness measurement. Can any mine afford to miss out on this technology?

Jan 1, 2008

By M. W. Von Bernewitz

Corduroy is used for saving gold in small Land large milling plants throughout the world. Investigations by the Metallurgical Division of the Bureau of Mine indicate that corduroy blankets, used with or without a trap or jig in the mill classifier circuit, often are effective in concentrating gold and sulfides, especially if the gold does not amalgamate readily and if not enough sulfides are present to warrant the use of a shaking table, flotation cells, or cyanide plant. Most cold-mining countries include several or many small miner, that produce siliceous ores low in sulfides and gold, which can easily be amalgamated or caught in traps or jigs or on corduroy and shaking tables. At these mines the ore is crushed by stamps or bill mills, and the flow sheets include plates, flotation cells, and cyanide treatment, yet probably nearly as much of the pair minerals may be recovered by the less expensive plant. A well-known western maker of mine and mill equipment asserts, as the result of considerable observation of installed plants, that old and other valuable minerals should be caught as soon as they have been released by a mill, end recommends jigs to do this. A supplier of corduroy has informed us that at some mines this material is being replaced by jigs that catch gold as fine as 400-mesh. But for the small operator, inexpensive equipment such as a corduroy table may be better adapted and give a good recovery of gold and associated minerals.

Jan 1, 1939

By M P. Cipold, J F. Bachmann, C C. Bachmann, J Ha, H B. Wurst

In washability, the objective is to establish the set of maximum possible separation performance criteria for a given mineral feed. The method of choice for this has been the conventional sink–?float analysis. Using traditional sink–float method it is not possible to sample and automatically measure. This fact, as well as time, cost and safety aspects, as well as required and manageable sample size of the sink–float method have prompted the search for a new approach for establishing separation performance criteria. This is especially important as performance levels of separator plants can be maximised if reliable information based on an analysis of washability in conjunction with particle size distribution, elemental constituency becomes available in time. The new method to establish washability and associated performance information utilises at least two measurement technologies concurrently: single energy X-ray transmission and image processing. For porous or very inhomogeneous materials the results can be refined further by using dual energy X-ray transmission and image processing.If used as a standard laboratory device the continuous build-up of the washability curve allows to evaluate the statistical significance of the sample size during measurement.The measuring method can even be improved if it is combined with an automatic sampling system that feeds a continuous and representative particle stream to the analyser. Then the value of the collected data increases considerably since the washability data are additionally available in time to be considered in the control of the process plant. The washability curve can be derived and is continuously updated based on the particles measured during the past time interval. Older curves and results are stored in a database and can be retrieved for later reference. This technology now enables automated sampling and integrated automated measurement, which was previously not possible.This incorporation of an automated washability monitor at a representative sample gives near real-time data that would impinge positively on the profitability of the plant operation. The method was extensively tested using a range of samples with different densities, varying from 1 g/cm3 (coal) to 5 g/cm3 (iron ore).CITATION:Bachmann, C C, Bachmann, J F, Cipold, M P, Wurst, H B and Ha, J, 2017. Inline analysis of washability parameters for process control, in Proceedings Eighth World Conference on Sampling and Blending , pp 213–218 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By David Leidel, James Stuart

The 50 ohm resistorized electric detonator is commonly used in the oilfield for initiation of wireline conveyed perforating guns and other downhole explosive tools. This type of electric detonator provides some degree of safety above that of the conventional one ohm electric detonator, since a higher current level is required to initiate the device. In order to obtain the necessary data to develop safe distance tables from RF sources for the 50 ohm electric detonator, laboratory tests were conducted to determine the detonator’s “no-fire” current, AC impedance, and its susceptibility to ESD. The results were surprising as two types of failure modes were observed. The “no-fire’ current levels determined from Langlie “One-Shot” Test Methods were determined for the devices tested providing values for the 0.999 probability “no-fire” power level at a 95% confidence level. This data will serve as the basis for sets of safe distance tables from RF sources that will appear in the forthcoming edition of the Institute of Makers of Explosives Safety Library Publication 20, “Safety Guide for the Prevention of Radio Frequency Radiation Hazards in the Use of Commercial Electric Detonators, (Blasting Caps)”.

Jan 1, 2010

By W. F. NETZZEBAND

THE long-hole drill has been used for prospecting underground in the tri-State district for several years, and its value has been pretty thoroughly proved. An attempt was made to get a statement of their experience with the machine from all the operators who were known to have used the machine. The majority of them replied to the questionnaire so that this paper is practically a summary of the experience of the district, together with some practical details taken from the experience of the Eagle-Picher Lead Company. When the drill was first used by the Eagle-Picher Lead Co., it was put in low headings and was mounted on a cross-arm supported by two drill columns. This was found to be a rather awkward method of mounting, because fairly long moves were made and the same drill columns could not be used on any two successive set-ups. The machine was later moved to a mine with high headings so that this type of mounting was found to be impractical. A heavy tripod was tried and found satisfactory, provided care was taken to see that the set-up was solid. The Evans-Wallower Lead Co. and the Century Zinc Co. report using the double post set-up, but the headings are low in these mines. The Commerce Mining St Royalty Co. first used the double-post mounting in high headings by cutting a niche in the wall and setting the post in it. This proved to be a slow and expensive method and was later abandoned for the tripod. The Federal Mining & Smelting Co. has used a tripod throughout its operations. Great care must be taken in using the tripod to see that the set-up is solid. Wherever possible it is advisable to sludge in the legs and let them set a short time before the machine is put into use. Where high bottom is encountered the Eagle-Picher operator found it advisable to drill jack- hammer holes in the bottom and drive the legs into them.

Jan 1, 1930

By William Gleason

"On April 4, 2017, the largest earth-pressure-balance tunnel boring machine (TBM) ever built finally completed its 2.7-km (1.7-mile) journey beneath Seattle, WA, nearly four years after it began boring the SR-99 tunnel that will eventually replace Seattle’s Alaskan Way Viaduct.By now, readers of this publication are familiar with the ordeal that began on Dec. 6, 2016, when the machine overheated and shut down. Until that point, the TBM, named Bertha, had grabbed headlines for being the largest in the world with a 17-m (57.6-ft) diameter face. But after the incident that stopped the progress, the headlines suddenly stopped focusing on the engineering marvel of the tunnel project and began asking what went wrong. Just 300 m (1,000 ft) into the tunneling journey the machine was stuck, unable to move forward and impossible to retract.The project’s contractors, Seattle Tunnel Partners,(STP JV) – a design-build consortium comprised of Dragados - USA, Tutor Perini, say a 20-cm (8-in.) steel well-casing buried in the path of the machine caused the problems that halted the TBM. The Washington State Department of Transportation (WSDOT) disagrees, and the issue over who ultimately pays for the repairs is now with the courts.Eventually, engineers determined the best way to get Bertha back to work was to dig a 36-m (120-ft), deep concrete lined shaft pit in front of the machine and lift the 1.8-kt (2,000-st) cutterhead out for repairs. The repairs took two years but eventually the machine resumed mining in January 2016. In April 2017, the TBM finished building the tunnel, breaking through at the tunnel’s north end near Seattle’s Space Needle, with little to no ground surface movement measured on the entire alignment.While the cause of the TBM breakdown and who should pay for repairs was debated above ground, the work below ground continued. David Sowers, deputy program administrator, engineering and program management with WSDOT, told Mining Engineering during the 2017 Cutting Edge Conference in Seattle that in addition to the technical marvel that the tunnel became, the fact the parties involved were able to work through the unprecedented challenge is a great example of how to overcome challenges on massive projects."

Jan 12, 2017

By R. Dahlke, J. A. Finch

"A campaign was undertaken during the greater part of 2001 at Noranda’s Brunswick Mine Concentrator to investigate the role of gas (air) superficial rate distribution (Jg profile) to the cells in the final Zn cleaning stage (bank of seven cells). Three profiles were tested: Balanced (each cell with same Jg), Increasing (from cell 1 to 7), and Decreasing, along with an “as found” profile in a parallel control bank. The experimental design allowed for two confounding factors, changes in ore type and circulating load. The Increasing profile consistently gave the best metallurgy (down-the-bank grade / recovery). The reason for improved performance was traced to the response of the first few cells. The Increasing profile gave the highest selectivity of sphalerite against non-sulphide gangue (NSG) in these cells with relatively even recovery per cell down the bank (10-15% based on feed to each cell). The other profiles gave lower selectivity and higher zinc recovery in the first cells (up to 25% in cell 1), which combined to reduce overall bank performance. The increased selectivity with the Increasing profile is attributed to the low gas rate in the first cells reducing water recovery and hence limiting entrainment of NSG gangue. The Increasing profile was subsequently configured for all four stages in the zinc cleaner circuit.INTRODUCTIONThe performance of a flotation circuit is largely the result of the operator’s response to visual clues. This includes manipulation of the gas (air) input and how it is distributed to cells in a bank. A lack of sensors prescribes this approach. Over the past ten years the Mineral Processing Group at McGill University have developed a set of gas dispersion sensors including one to measure gas superficial rate (or simply “gas rate”), i.e., volumetric gas rate per unit cell crosssectional area, Jg (Gomez and Finch, 2002). The device collects bubbles in a tube immersed in the pulp and infers Jg from the pressure-time curve generated after a valve is closed and air starts to accumulate. The usual units are cm/s. It is robust, reliable and suited for plant use.A version of the Jg sensor was tested extensively during 2000 at Noranda’s Brunswick Mine Concentrator (Dahlke et al., 2001). The results were sufficiently encouraging that a sensor was fabricated to suit local requirements (Insta-Jg). The sensor detected malfunctioning field instruments and flotation mechanisms, and demonstrated that gas distribution to cells in a bank “as found” had no particular pattern, or profile. Preliminary testing suggested that a balanced profile (i.e., all cells with the same gas rate) gave superior metallurgy (grade / recovery down the bank) than the “as found” profile. This observation prompted a focused campaign to explore the impact of the gas rate (Jg) profile, introducing the notion of “gas distribution management”."

Jan 1, 2004

By Jun Ohbayashi, Yoshiyuki Yagiura, Hiroaki Miyatake, Masuo Kondoh, Naotoshi Shinkawa

"Reducing the improvement ratio of ground improvement is an extremely efficient way to reduce the construction cost and construction period of mitigation measures for soft ground. The Arch Action Low Improvement Ratio Cement Column (ALiCC Method) is one method for this, and it is being increasingly applied to sites. This method enables us to rationally evaluate the embankment loads that are acting on cement improved soil columns and unimproved ground, by considering the arch action generated in the embankments and from there thusly allocate improved soil columns in spans of a greater distance than those needed for conventional methods. As a result, it serves to reduce construction costs and the construction period, while also minimizing the settling of the embankment and differential settlement, by placing numerous improved soil columns in the ground immediately beneath the embankment at equidistant intervals. In this report, we give a basic overview of the ALiCC Method, report typical construction results from real life cases that have been carried out, and make comparisons with other construction methods in order to report on the effectiveness of this design method.OVERVIEW OF ARCH ACTION LOW IMPROVEMENT RATIO CEMENT COLUMN (ALiCC) METHODIn the area of mitigation measures for soft ground, a significant role is played by ground improvements using improved materials such as cement. For this reason, a reduction in construction costs and construction period required for ground improvements has become of greater importance. The Public Works Research Institute carried out joint research with Kiso-Jiban Consultants Co. Ltd., Kitac Co. Ltd., and Fudo Tetra Co. Ltd. over a period from 1998 through 2002, and, from that, developed the ""Arch Action Low Improvement Ratio Cement Column Method"" (hereinafter referred to as the ""ALiCC Method"") that enables ground improvement with a lower improvement ratio (the improved area ratio is approx. 10% to 30%) than is required for conventional methods, while also ensuring stabilization and minimizing the settling of embankments.In the area of mitigation methods for soft ground by deep mixing, the dominant method until now has been that (50% or more of improvement ratio) shown in Fig. 1. This method comprehensively improves the area under the face of the slopes of both sides of the embankment. This is based on the calculated stability against rotational slip, which states, ""the most effective way to ensure the stabilization of the embankment environment is to carry out improvements of the area under the face of the slope."" Therefore, for the area under the face of the slope, ground improvement by deep mixing was done, and for the soft ground in the area under the middle part of the embankment, accelerated consolidation methods (hereinafter referred to as ""conventional method"") such as sand draining method and paper draining method were used. Mitigation measures that combine these improvement methods have also been mainstream for a long period of time and are used to prevent side deformation around the embankment. However, there have been some problems that have occurred, such as a situation where consolidation settling occurs in the center area under the embankment where no improvement had been carried out. This phenomenon leads to a situation in which the improved soil columns in the area under the face the of slope are pushed to the outside, which results in side deformation occurring around the area of the embankment, and additionally the occurrence of a step due to a situation of differential settlement between the improved ground and the consolidation advancing part, which results in cracks in the embankment."

Jan 1, 2015

By A. Galaitsis

This report summarizes part of the work performed under the USBM Contract No H0155113, "Noise Abatement of Continuous Mining Machines." It describes the noise source diagnosis of a Jeffrey 120M conveyor and the evaluation of several treatments all conducted in a test facility aboveground. The conveyor noise at the operator's position was gradually reduced from 101.5 to 93 dBA using damping, vibration isolation, sound barriers and smoother discontinuities. The underground performance of the selected treatments will be addressed in Volume II of the report.

Jan 1, 1979

By A D. Campbell

Sublevel caving (SLC) is a mining method adopted in a wide range of mining depths and ground conditions with various layouts adopted to suit orebody geometry. Sublevel caving offers more flexibility and versatility compared to other cave mining methods and is a low cost alternative to open stoping. SLC also has the advantage that stopes are not required to remain stable during production, and no backfill is required. This flexibility combined with increasing pressure on mines to target deeper and lower grade mineralisation has led to increased uptake of the method. The implementation of SLC mining methods across a wide range of mining depths and rock mass conditions has led to ground control practices which vary globally from mine to mine. To date, there has been limited documentation of ground control practices in SLC mining and few benchmarks available in the literature. This paper describes the main findings from a global benchmark of sublevel cave mines conducted over three years as part of the Caving 2040 research consortium. The purpose of the project was to document and compare operational practices, technical aspects and hazard management techniques across SLC mines around the world. The review included 21 mines spread over four continents and 17 different mining companies. This paper provides an overview of geotechnical conditions, challenges and ground control practices at each of the benchmarked SLC mines. Mine design and sequencing practices adopted for ground control purposes and hazard mitigation are provided with case studies. The impact of depth and rock mass conditions on mining productivity and development rates is also described.

Nov 29, 2022

By J. Morris, R. Sellaro

Petro-diesel is a common collector for coal flotation, but the partitioning of diesel range organics (DROs) in process streams has not been widely studied. Preliminary research suggested that under normal dosing schemes total residual DRO contents in process waters should be limited to the sub-ppm water-soluble fraction (WSF). Further, polycyclic aromatic hydrocarbons (PAHs) should partition proportionately with DROs. The purpose of this study was to confirm these findings in laboratory flotation tests. Total DRO and specific PAH contents were measured in the waters associated with the concentrate and tailings streams. The results show that concentrate waters consistently had higher amounts of DROs than tailing waters. Moreover, the DRO contents in both streams generally increased with increasing diesel dosage. In line with preliminary research, DROs appeared to be limited to the WSF, and PAHs tended to partition proportionately with DROs. Under typical operating conditions, it appears that residual DROs should not present an environmental concern, but conditions should be avoided that allow significant overdosing of diesel.

Jan 1, 2014