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By A. M. Khan, I. Fatt

A new type of steady-state thermal conductivity apparatus is presented and described. Results of measurements on Berea sandstone, Solehofen limestone, Bandera sandstone and Bakelite are presented. The measurements were made in a two-hour period at temperatures up to 80C and axial stress to 125 bars. Results show that the thermoelectric heat pump and tbermistor-controlled electric heater can be used in a steady-state apparatus for measuring thermal conductivity of mck. Steady-state is reached within two hours. With Urethane foam insulation, not more than 3 per cent of heat is lost by radial flaw. The apparatus can be used as a comparator or for absolute thermal conductivity determinations. INTRODUCTION Calculations of heat flow through the earth, both for scientific purposes and engineering design, require thermal-conductivity data on rock. However, the high variability of rock often makes handbook thermal-conductivity data of little value. For engineering purposes in particular, it is desirable to have measured data on samples of the rock mass under study. Laboratory methods for measuring thermal conductivity of rock use either time-dependent1-3 or steady - state temperatures .4,5 The time -dependent (transient) techniques give thermal diffusivity from which thermal conductivity can be calculated if the specific heat and density of the sample is known. Most transient techniques require lengthy and involved sample preparation. Also, the accuracy tends to be low. Steady-state techniques are more exact and are the most commonly used. The steady-state methods, however, also have their difficulties. A long time is often required to reach steady state, troubles have been encountered in establishing good thermal contact between the heating and cooling elements and the rock sample, and unaccounted-for heat losses are difficult to prevent. In this paper we present a description of a new type of steady-state thermal conductivity apparatus. With it, measurements have been made in two hours at temperatures up to 80C and axial stress to 125 bars. Sample preparation is simple and no thermal conductivity standard is needed.6 APPARATUS Our steady-state apparatus is an improvement . over the conduction pile used by Zierfuss and van der vliet4 and Somerton.5 A linear heat flux is established through a conduction pile consisting of the rock sample and a standard material of known thermal conductivity in series. The thermal conductivity of the sample is calculated from the ratio of the temperature drop across the sample

Jan 1, 1966

By Brad McBain

Agenda ? Accurassay Laboratories and Automation ? History and experience ? Features and benefits of automation in the lab ? Tata Steel Minerals Canada (TSMC) Iron Ore Laboratory ? State-of-the art systems and design ? The integration of fusion systems and XRF units ? Meeting deliverables: quality, reliability, safety

Aug 1, 2013

By W. R. Reed

The National Institute for Occupational Safety and Health (NIOSH) uses light-scattering dust monitors (nephelometers) in its research to develop dust controls to reduce respirable silica dust overexposures in miners. Recently, the model 1500-pDR, an active nephelometer, was introduced by Thermo Scientific. Testing was completed to ensure compatibility with the metal/nonmetal mine dust personal sampling unit (M/NMDPSU). Results of testing demonstrated that gravimetric concentrations measured from the 1500-pDR are comparable to the gravimetric concentrations measured using the M/NMDPSU, without need for correction, under commonly observed dust loading conditions.

Jan 1, 2012

By Eric S. Weiss

The National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted joint research to evaluate explosion blast effects on typical U.S. mine ventilation stoppings in the NIOSH Pittsburgh Research Laboratory?s (PRL) Lake Lynn Experimental Mine (LLEM). An innovative Australian-designed brattice stop-ping was also evaluated. After mine explosion accidents, MSHA conducts investigations to determine the cause(s) as a means to prevent future occurrences. As part of these postexplosion investigations, the condition of underground stoppings, including the debris from damaged stoppings, is documented as evidence of the approximate strength and the direction of the explosion forces. The LLEM data showed that a typical dry-stacked and coated solid-concrete-block stopping survived a total explosion pressure of ~6.7 psi (~46 kPa) and was destroyed at a total explosion pressure of ~7.6 psi (~52 kPa). In comparison, a typical dry-stacked and coated hollow-core concrete block stopping survived a total explosion pressure of ~3.4?4.3 psi (~23?30 kPa) and was destroyed at a total explosion pressure of ~3.6?5.2 psi (~25?36 kPa), depending on the length of the pressure pulse and the value of the pressure-time integral. A typical steel panel stopping design survived a total explosion pressure of 0.8 psi (5.5 kPa) and failed at a total explosion pressure of 1.3 psi (9 kPa). The LLEM data also showed that an obstacle blocking the path of a pressure wave resulted in a higher reflected pressure at the obstacle. An 8-in (20-cm) thick wet-laid solid-concrete-block stopping coated on one side survived a total explosion pressure of ~26 psi (~180 kPa); this stopping was not tested to failure. A 6-in (15-cm) thick wet-laid solid-concrete-block stopping coated on one side survived a total explosion pressure of ~14 psi (~97 kPa) and was destroyed at a total explosion pressure of ~25 psi (~172 kPa). An innovative Australian woven cloth stopping survived an explosion pressure of 4.0 psi (27 kPa) and was destroyed at an explosion pressure of ~6.1 psi (~42 kPa). These results will help investigators determine the approximate explosion forces that destroy or damage stoppings during actual coal mine explosions.

Jan 1, 2008

By Lavers G

Factors governing the dissolution of nickel and iron in pentlandite and pyrrhotite concentrates from Mt. Windarra were studied for aqueous solutions at normal temperatures and pressures. The effects of dissolved dioxygen, carbon dioxide, hydrogen ions, and chloride ions are described. The direct reaction of aerated water wiili pyrrhotite is much faster than with pentlandite, and reaction rates are proportional to the dissolved dioxygen concentration. In both cases divalent metal sulphates are produced initially. The subsequent oxidation of iron(II) to iron(III) and its oxolation produces acid solutions which rapidly attack both minerals. The presence of carbon dioxide or chloride ion has little effect on these rates.

Jan 1, 1976

An assessment of methods currently available for the accurate determination of low concentrations of platinum in ores and mineral concentrates indicated that prior treatment of the sample by fire assay procedures is necessary. To enable rapid determinations to be carried out, instrumental methods applied to the metallic bead produced from the fire assay treatment have been evaluated, considering maximum flexibility for concentration variations, minimum chemical operations, and adequate sensitivity.Atomic absorption spectrometry proved suitable, giving solution determination limits of 0·4 p.p.m. Pt, 0·1 p.p.m. Pt, or 0·06 p.p.m. Pt under various extraction conditions using aqueous and organic agents. Thesedetermination limits related to 1 assay ton of sample (32·67 g) produced easily readable and accurate readings within the range of platinum contents (0·03-2·0 p.p.m.) of economic interest in deposit evaluation and prospecting. The technique shows promise of also being suitable for determination of palladium and gold.

Jan 1, 1970

By L. Yuan

To reduce fire hazards from spontaneous combustion of coal in longwall gob areas, a series of computational fluid dynamics (CFD) simulations were conducted by National Institute for Occupational Safety and Health (NIOSH) to model the spontaneous heating of coal in longwall gob areas. The previous modeling results demonstrate that spontaneous heating of coal usually occurred behind the longwall shields and along the face with a bleeder ventilation system. Assuming a stationary longwall face, the spontaneous heating could turn to a spontaneous fire in several days for the most reactive coal under favorable conditions. When the longwall face advances, the spontaneous heating process will be significantly affected. In this study, the effect of longwall face advance on the spontaneous heating in the gob area is investigated using the CFD model developed in previous studies. One longwall panel with a bleeder ventilation system is simulated. The width of the panel is 300 m, while the length of the panel is changed between 1,000 to 2,000 m. The same permeability and porosity profiles are used for gobs with different lengths. The spontaneous heating first develops in the gob when the longwall face is stationary. Then, the face advances at a certain rate. The face advance is simulated as a series of discrete movements, and the effect of the face advance on the maximum temperature developed during the face stoppage is examined. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Jan 1, 2009

By M. Mirnezami, D. Lascelles, J. A. Finch, E. El-Ammouri

"In a previous publication, the depressant action of Mg above pH 10 on Cu-activated sphalerite was described (Lascelles et al., 2001). In the present communication, a second role, aggregation is introduced.Aggregation (i.e., the tendency of particles to cluster) is measured using settling rate and turbidity converted to an aggregation index (AI) where 0 corresponds to dispersed and 1 to aggregated. Surveys of Cu and Zn flotation stages at four concentrators showed the A1 increased significantly above pH 9. The metal ions identified in the process waters, principally Ca and Mg, were tested to determine which might be responsible. The presence of Mg was found to be the most important, 50 ppm Mg having a greater impact than 500 ppm Ca fkom pH 9 to 1 1. In one plant, poor repeatability in A1 was suspected to be related to varying Mg levels; doping with Mg significantly increased AI.In both aggregation and depression, therefore, the common feature is the impact of Mg at pH > 9. Over this pH range Mg forms a range of hydroxy species, including Mg(OH)2 precipitates. Suggested aggregation and depression mechanisms associated with these precipitates are introduced. Possible problems and opportunities arising from the findings are discussed.INTRODUCTIONProcess waters in flotation circuits contain a variety of metal ions that may introduce unwanted activation or depression. Two common metal ions are calcium and magnesium. Typical concentrations are in the range 50 ppm Mg and 500 ppm Ca (Marticorena et al., 1994, Basilio et al., 1996, Negeri et al., 1997, Nesset et al., 1998)."

Jan 1, 2002

By Jan E. Nesset, Colin Hardie, Peter Radziszewski, Donald P. Leroux

"The successful introduction of new high intensity stirred milling technologies (e.g. IsaMill, SMDetritor) to the mining industry in recent years prompted Noranda-Falconbridge to initiate a study comparing these technologies to the conventional technologies of ball milling and existing vertical stirred mills (e.g. VertiMill). The study was unique in that it utilized the same material (Brunswick Mine zinc cleaner regrind mill feed), the same sizing instrument (a Malvern laser difractometer) and sampling protocol, and media size and type (for the high intensity stirred mills). The paper compares the net energy efficiency (kWh/t) of the various technologies, their power intensity (kW/m3) and product size distribution spread (P80/P20). A key finding is that media size is critical to achieving optimal performance. As part of the performance comparison, an analysis of the four methods of power measurement was made (Prony brake, shaft torque, grinding chamber reaction torque, “no-load” correction) and followed-up with an experimental test procedure using three of these methods. The findings include divergent results for power measurements and some explanations based on the observations are proposed. The direct shaft torque and Prony brake calibration methods are shown to be the methods most suitable for stirred mills.INTRODUCTIONThe motivation for the investigation reported here was the lack of a suitable comparison within the available literature of relative grinding efficiency for the emerging crop of new industrial fine grinding technologies. Such comparisons are potentially fraught with inconsistency, from ore samples and grinding media used, to testing methodology, to size measurement techniques, to the power measurements themselves. The collaboration of the industrial suppliers (at the time MIM Technologies and Svedala, now Xstrada Technologies and Metso Minerals) and McGill University (P. Radsiszewski) were sought in order to ensure as valid a comparison as possible. The work was performed between October 2000 and November 2002, led by the mineral processing group at the Noranda Technology Centre (NTC) in Pointe-Claire, Quebec. The paper is presented in two sections; Part A considers the different power measurement methods and a comparison of the results for the SMDetritor (SMD) technology, while Part B reviews the grinding performance of the 5 technologies investigated using the selected performance criteria."

Jan 1, 2006

By Madgwick J. C

A new strain of Thiobacil/us ferrooxidans (SPK I) has been isolated which has a higher copper to iron release ratio (2.04) than the standard T ferrooxidans (CPBI) (1.12). The diminished iron oxidizing ability enables almost quantitative release of copper (93 per cent) from a chalcopyrite-rich concentrate without interference by iron reprecipitation. In a single batch leach, Bougainville copper concentrate yielded 9.3 grams/litre soluble copper from a 4 per cent w/v suspension in 100 days at 32°C.Solvent extraction recovery of soluble copper is recommended as a final step in a leaching process.

Jan 1, 1983

The range of environments which control the level of ground support required vary greatly in terms of rock type, rock structure and the mining method used. At the operating mines visited during this review the level of ground support was such that incidence of rock-fall- related accidents were rare. It was also found that methods existed to support most of the conditions encountered. The main problem areas were weak rock, major geological structures, areas of heavy jointing, high development density and areas affected by high mining-induced stresses and blasting. With stope support the level of success was much lower than that achieved in development; the larger spans and more rapid changes in geometry of open stopes compared with cut and fill stoping (where cables were originally used) led to significant problems. Before a useable design method for cable support of stope walls and pillars can be obtained the precise failure mode of the walls and pillars, and the interaction of the support and the rock mass must be investigated.

Jan 1, 1982

By R. E. McIvor, Brian Cornish, J. A. Finch, Yue Tan, Claude Gagnon

Fred C. Bond is recognized throughout the mineral processing world as the father of comminution equipment applied science and engineering. The Bond Work Index became a universal standard, and is the most widely used measurement tool for comminution energy consumption. This biography is the story of his lifetime of study, work experiences, experimentation, analyses and findings. His numerous published writings are reviewed. His legacy is one of comminution process engineering that will be used in perpetuity.

Feb 1, 2024

By Fraser M. Walsh

The objective of this program was to determine by laboratory experiments the kinetics and mechanics of the reactions that produce acid in coal mine drainage. The program was divided into three phases: In Phase I, five coil mines, representative of Appalachian coal mines, were chosen for sampling and an experimental design was identified suited to accomplish the program objectives. In Phase II, the five mines were sampled and test protocols applied. The results showed most pyrite weathering to be based on oxidation in the presence of water. Iron bacteria, especially Thiobacillus ferrooxidans, catalyzed the rate of pyrite weathering by a factor of three. An increase in initial iron concentration in a system that modeled the nine environment acted to inhibit bacterial catalysis of weathering. In Phase III, five tailings piles were sampled and the material obtained was used to evaluate this method of bacterial catalysis inhibition. The evaluation verified method effectiveness; inhibition of over 80% of the release of weathering products was observed.

Jan 1, 1982

By Alexander Filotti, Stanley Merjan

"Abstract. The paper shows the benefits and accomplishments of this relatively new but established product on the pile foundations market in the United States. The first part of the paper describes general aspects of the design, construction, and geotechnical capacity (designed and in situ) of Tapertube piles. The qualities resulting from the design and manufacturing of the Tapertube pile will be presented first.The second part of the paper describes the installation of Tapertube piles for an addition to Terminal One at JFK International Airport and The Edge development. A carbon print analysis for both projects is developed using the EFFC-DFI carbon print calculator. For the JFK project the benefits of using BIM in redesigning the project for Tapertube piles are explored.General description.The tapertube pile consists of a tapered tubular bottom section attached to a conventional pipe extension. The 50 ksi steel for the taper is mechanically folded into a polygonal cross-section (usually 12-sided) with a longitudinal welded seam. The tapers are fabricated in many sizes with bottom diameters varying from 8 to 14 inches, top diameters from 12 to 20 inches, lengths from 10 to 35 feet, and steel thicknesses from 3/16 to 1/2 inch. A conical steel shoe or a flat plate is welded to the bottom of the taper and the top of the taper is circularized to match the outside diameter of the pipe extension. The inclination of the tapers is generally between 1.5% and 2.5%.The pipe extension is fully butt welded to the taper and has the necessary length for the pile to develop the requisite capacity. Concrete fill for the piles is generally 4,000 p.s.i. or more. Typically the piles are shopassembled and shipped to jobsites in lengths to 80 feet."

Jan 1, 2014

By J. Hartikainen

Kemi cardboard mill is founded on the alluvial bed of Kemi river at the north-eastern cost of Botnic Culf in Northern Finland. The alluvium consists of sandy and silty layers underlain by thick medium dense silty moraine layer. The first cardboard machine, having a belt width of 7,4 m, was constructed in 1972 on 7,5 to 9,5 m long wedge-shaped precast driven piles. Because of the excessive differential settlements and sometimes unexpected dynamic malfunctioning of the machine it was decided to strengthen the foundation before installing the partly new machine and increasing the running speed from 500 to 750 m/min. Piling was done under extremly strick limitations concerning space, vibrations, settlements, dust etc. Extra vertical support was made by using 23...25 long x-form steel piles driven by compressed air pile hammer down to rock. The piles were held together with old piles by a conctrete frame with diagonals, which made the total system - machine - foundation frame, piles and ground - ridgid enough to avoid resonance during dynamic loading.

Jan 1, 2010

By J. A. Meech, R. J. Tucker

"Since the establishment of froth flotation as an effective method of mineral beneficiation there has been both academic and industrial interest in the levels of the various reagents required to perform the desired separations. Academic interest was spurred by a desire to understand the mechanisms involved - industrial interest by a need to improve the efficiency of the process. These efficiency improvements can take two forms: cost reductions due to reduced reagent consumption and/or improved separation efficiencies. The latter are indicated by either improved grade-recovery relationships for removal of a valuable mineral from gangue, or improved separation of two similar valuable minerals.The processing of lower grade ore bodies at higher tonnage rates has necessitated increased interest in both reagent consumption and metal recovery. Furthermore, the development of accurate and functional on-stream analysis equipment in the 1960's and 1970's has allowed for a better understanding of the dynamic processes involved in a flotation circuit and has required a more concrete statement of the relationships and reactions between the minerals and chemicals in the flotation pulp. Development of these relationships is necessary in order to make use of on-stream analysis to control the process at, or near its more efficient level."

Jan 1, 1984

By S. Junnikkala, K. Föhr

"Experiments were performed with plant feeds with a continuous 1,8 m3 cell at Pyhasalmi mine with Cu flotation feed in order to test the applicability of the bubble surface area flux as an indicator of the flotation rate constant. It was found that bubble surface area flux could not predict the rate constants of coarse Cu containing fractions. In the middle size fraction, the correlation coefficient in the rate coefficient estimation was higher but not statistically significant. Only the fine fraction showed a linear relationship with a moderate correlation coefficient.The bubble surface area flux was shown not to be a function of the impeller velocity above a threshold value. The flux was an almost linear function of the superficial gas rate enabling to use the superficial gas rate instead of flux if the operation of an existing cell is to be estimated.INTRODUCTIONBubble area flux seems to offer a simple way of modeling flotation. It relates the flotation rate constant with the bubble surface area flux by a simple linear equation. Due to this, there has been a considerable interest in using the bubble area flux for flotation computations. It has even caused claims that a cell producing a high bubble surface area flux automatically produces a high rate constant and therefore a high recovery.This paper discusses some of the assumptions of the relationship and gives some plant results during two sampling campaigns.The bubble surface area flux s b is describing the area of bubbles available for flotation in a cell per unit area. The bubble surface area flux is related to the superficial gas rate J, by the Sauter mean diameter as follows"

Jan 1, 2001

By M. Mononen, J. Huuskonen, M. Vauhkonen, J. Kourunen, A. Lehikoinen

"A new approach to measure process conditions in flotation cells is presented. Real scale flotation cells in a Zinc circuit are imaged using Outotec LevelSense sensors based on electrical resistance tomography. The latest results from long period plant tests show that the sensors together with FrothControl analysis give new information that correlates well with other process parameters. The sensors can compensate for electrical contact contamination using an automatic calibration technique and they are basically maintenance free. The results indicate that using the LevelSense sensors and FrothControl solution, the process control and optimization can be done automatically, stabilizing and improving the metallurgical performance of the flotation process.INTRODUCTIONThe froth flotation process is widely used in mineral industry for the separation of minerals from low-grade ore slurry. Different property parameters of froth and slurry could be measured to monitor and control the flotation process: air bubble size distribution, flow dynamics, thickness of the froth bed, amount of solids in the froth, etc. Some techniques already exist that can be utilized in studying these important parameters on-line. Examples of the techniques are the high-speed video imaging, simple conductivity probes, ultrasound techniques, floats and pressure transducers (Maldonado et al., 2008). These techniques, however, often suffer from some limitations. For example, the video imaging only gives information from the surface of the froth, simple conductivity probes suffer from contamination and the floats may get stuck and therefore do not give reliable signal for process control and optimization."

Jan 1, 2013

By Mark S. Sanders

The purpose of the present study was to develop and test improved Type V workvests for use on dredge operations. The goal was to design workvests that would be more comfortable to wear, would interfere less with task performance, and would better meet the needs of dredge workers. It was hypothesized that by attaining these goals, the resulting vests would be worn more often and would be kept buckled more of the time than traditional vests. The study involved three major phases. In Phase I, visits were made to dredge operations and a definition of the problem was developed. Problems with current vests were identified and working conditions and tasks surveyed In Phase II, prototype vests were developed and laboratory tests were per-formed to assess comfort and interference. In Phase III, the prototypes were modified and field tested with actual dredge operators and workers.

Jan 1, 1985

By Thomas Weyand, Thomas Claridge, Dale Nickels

"This paper addresses the initial results of a project to evaluate the suitability of copper mining tailings as raw material for the production of structural products using PMET’s patented technology. Preliminary testing indicated that high performance structural products were possible using these materials. A demonstration scale project produced approximately 1,500 bricks in various colors. These products fall under under ASTM C- 73 and were found to present properties suitable for severe weather applications. Although the products in this project were of typical brick dimensions, other products are possible, for example concrete block substitutes or pavers. These products from the PMET process are commercially known as Brixx. This paper will provide operational details of the production process, mineralogy and mechanical properties of the products.INTRODUCTIONPMET has developed process technology that can convert various siliceous waste materials into competent structural products. This technology is the subject of US patent # 6,068,803. In general, the process consists of mixing lime, water and the major feed stock, pressing to form a “green” shape, and curing the product in an autoclave for 6 hours with saturated steam at ~200oC. The curing process forms Tobermorite, which acts as a crystalline binder. Freeport-McMoRan approached PMET to see whether mine tailings from the Sierrita mine, containing significant amounts of clay, might be a suitable feed material for the production of structural products. “Brixx” is the commercial term used to describe the resultant structural product formed in the test work. This paper is a preliminary evaluation of a technology that is being considered by Freeport-McMoRan. This report is not an endorsement by Freeport-McMoRan of the process or products, nor is it a commitment to use this technology."

Jan 1, 2008