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By B. W. Wallace

Permitted explosives in South Africa are those explosives approved by the relevant State authority for use in fiery coal mines. The main tests that an explosive must pass for this approval are the gallery tests derived from the Buxton (U.K.) classification. These tests are described briefly. In addition, the safety of permitted explosives is affected by their ability to deflagrate, and to produce a naked flame after blasting, rather than to detonate fully. Tests done on this phenomenon are discussed. A further potential hazard of explosives is after-blast fume. The testing and behaviour of several permitted explosives in this respect are covered, both in the laboratory and in the field. Performance testing of permitted explosives, specifically the double-pipe, underwater, and ballistic mortar tests, and their relationship to field use, are considered in some detail. The application of traditional and new tests to permitted explosives leads to guidelines for the safe and efficient formulation and use of these products.

Jan 1, 1986

By K. R. Vost

Variation in air temperature in a cross-section of an underground airway by K. R. VOST, B.Sc. (Glas.), M.Sc. (N.S.W.) (Visitor) Measurements of air temperatures in underground airways are normally made at only one point in a cross-section, and the air tem peratures at other points in the cross-section are assumed not to differ significantly from this. This paper discusses measurements made at a number of points in fifty crosssections in airways with different air velocities and wetness of floor. These measurements show that significant variations of air temperature can occur in a given cross-section at a given time. The effects of such variations on the accuracy of measurement of rises in air temperature as air passes along an airway are discussed. The importance of considering experimental error in the measured rises in air temperature when attempting to validate theoretical and empirical methods of predicting such rises is also discussed.

Jan 7, 1976

By Chang-hong Peng

Solubility phase equilibrium in the ternary system of Me2+-NH4+-SO42--H2O (Me2+ represented Mn2+, Zn2+ and Fe2+) was studied by the isothermal method at 298K and physicochemical properties of the saturated solution such as density, refractive index and pH were also investigated. The experimental results show that the solubility isothermal phase diagrams of these systems consist of three invariant branches, two invariant points and three crystallization fields. Corresponding to the three crystallization fields, there have three phases of solid, that is MeSO4?nH2O, (NH4)2SO4 and (NH4)2Me(SO4)2?6H2O, respectively. At the eutectic point, the concentration and the refractive indexes of the saturated solution change evidently. Otherwise, the pH value change slowly in all the systems. The calculated results of the density and refractive index agree with the experimental results.

Jan 1, 2006

COLUMBIA LOCAL SECTION STANLY A. EASTON, Chairman, FREDERIC KEFFER, Vice-Chairman, L. K. ARMSTRONG, Sec.-Treas., P. O. Drawer 2154, Spokane, Wash. The fifth annual meeting of the Columbia Local Section was held in Wallace, Idaho, November 19-20, 1915, with headquarters at the Samuel Hotel. The afternoon session scheduled for November 19, was adjourned to give the members an opportunity to hear the testimony in the case between the Alameda and Success mining. companies on trial in the Superior Court of Shoshone County. The Success Company offered some excellent mine models and maps and furnished some interesting testimony. In the evening a technical session was held at which Stanly A. Easton presided in the absence of the Chairman and Vice-Chairman of the Section. The following papers were read: Progress in Ore Dressing By D. W. Buckby,.. Mine Accounting for Small Mines, By J. E. Chapman. Zinc Smelting and Smelter Rates, By W. E. Henry.

Jan 2, 1916

By Justus B. Deen

Given that the majority of mine ventilation operating costs are imposed by shafts, the need to predict the resistance of a planned shaft with reasonable accuracy is important. During conceptual design, shaft resistances are usually predicted by use of published friction factors, k, based upon lining and fitting configurations. More often than not, published friction factors do not directly coincide with "real" shafts, so their use is somewhat limited. For more accurate shaft resistance determination, equations both theoretical and empirical may be employed if there is detailed knowledge of the shaft. These equations treat the shaft resistance as discrete components, with their sum being the overall shaft resistance. This paper describes the basic shaft resistance equations and verifies these equations by comparison to field measured shaft resistances. Several shafts were examined which varied in depth, shape and fitting arrangements. Results are presented and conclusions drawn to show that the shaft resistance equations are accurate.

Jan 1, 1991

All the TECHNICAL PUBLICATIONS and CONTRIBUTIONS published in 1935 are available at Institute headquarters, unless otherwise noted. They are also on file in many public, university and technical libraries and, when so indicated in the list, may be found in the TRANSACTIONS. Copies of the TECHNICAL PUBLICATIONS have been mailed to members of the Institute that are registered in the different classes: A-Metal Mining; B-Milling and Concentration; C-Iron and Steel Division; D-Nonferrous Metallurgy; E-Institute of Metals Division; F-Coal Division; G-Petroleum Division; H-Industrial Minerals Division (Nonmetallics); I-Mining Geology; J-Mineral Industry Education Division; K-Mining Administration; I-Geophysical Prospecting. Other members may obtain copies by writing to the Secretary. Copies of CONTRIBUTIONS may also be obtained from the Secretary's office. Additional copies are sold at the rate of 1 cent per page; minimum charge, 25 cents. Nonmembers may purchase the papers at the prices mentioned. [ ]

Jan 1, 1936

By Ali M. Heidarieh Zadeh, Raghu N. Singh

The paper presents a stability investigation of shaft intersections and pit bottom roadways in the vicinity of upcast and downcast shafts at a colliery in the U.K. Aschemeof instrumentation was aimed at monitoring the strata displacement surrounding the pit bottom roadways and shaft intersections with a view to ascertaining the origin of the strata movement and effectiveness of the control measures. The bore- hole instrumentation results together with a theoretical analysis suggested that the cause of instability could be attributed to the drivage of a roadway within the shaft pillar. A semi-empirical technique was used to calculate the amount of support resistance required to reinforce the pillar to take additional abutment load. A rock bolting system was designed to provide a required increase in thrust capacity of the roadway support. The results indicated that roadway closure was effectively controlled after installation of bolts indicating efficacy of the control measures adopted.

Jan 1, 1982

By Richmond Bennett

Airborne geochemistry became a reality with the advent of a high-sensitivity air¬borne gamma ray spectrometer with large volume NAI(Tl) crystal detectors. The high-sensitivity spectrometer measures small variations in the concentration of potassium (as Ks°), thorium (as Tl308) and uranium (as Bi.214) along the flight lines in the area surveyed. Hydrothermal dispersion patterns are indicated by anomalous measured values of the concentrations of potassium, thorium, uranium, or their ratios. In two recent Australian survey areas, copper mineralization was located along favorable structures within hydrothermal dispersion patterns delineated by airborne geochemical surveys. In metamorphic terrane where there had been po¬tassium metasomatism, the hydrothermal dispersion patterns were indicated by high potassium/uranium ratios (K40/Bi). In a sedimentary environment that had been intruded by a stock, the path of hydrothermal fluids was indicated by uranium (Bi214), thorium (TV'), and uranium/ thorium (Bi214/Tl208) ratios.

Jan 1, 1972

By J. Partyka, Trevor R. J. Kelly

This paper presents the results on noise testing of a fan only, as well as the results of a steel silencer and of flexible silencers that were connected directly to a fan. On-site facilities and free-field method set by the British Standards Institution were used to measure and then compare the fan only and different practical silencer configuration setups. In order to determine the fan-silencer combination that would give the maximum noise attenuation, total noise intensity, noise contributed to by the fan motor only, as well as aerodynamical noise created through air interacting with the fan parts were considered to obtain decibel readings for the octave bands. Subsequently, the optimal configuration found was the setup with flexible silencers on the fan inlet and the fan outlet. If only one silencer is used, it should be installed on the fan inlet. The aerodynamic noise affects the low frequencies. The flow noise is then overtaken at 1 kHz by the mechanical noise.

Jan 1, 1995

By J. L. Huiatt, D. G. Foot

The Bureau of Mines devised a direct flotation method for treating low-grade carnallite (KCl*MgC12*6H20) and sylvinite (a mixture of KC1 and NaCl) ores characterized by a high content of water-insoluble impurities. The procedure consists of flocculation-depression of the insoluble slimes; decomposition leach (carnallite only); potash rougher, cleaner, and recleaner flotation; and final product leaching. The technique eliminates the necessity of removing the water-insoluble slimes by mechanical or flotation desliming. Laboratory results demonstrated that the direct flotation procedure, when compared with conventional techniques, yielded equivalent or improved flotation results with equal or less reagent consumptions. The direct flotation method recovered 81.6% of the solid phase KC1 from camallite ore and 79.7% of the KCl from sylvinite ore in final products containing 60.5 and 60.9% K2O, respectively. A flowsheet incorporating the described flotation procedure is presented.

Jan 1, 1983

By Walter Küng

The Henderson Coarse Ore Conveying System is a three flight belt conveyor system transporting primary crushed molybdenum ore 24 km (15 miles) underneath the North American Continental Divide. One of the conveyors is 16.8 km (55,200fi) in length with 8,200 kW (11,000 HP) of installed power. The overland conveyor contains 11 vertical curves and 9 horizontal curves, some with radii as small as 1,500 m. he system began full operation in December 1999 and is one of the longest and most complicated belt conveyor systems yet constructed. he design of this conveyor system utilized many innovative engineering concepts including low-energy belt covers, low-resistance idlers, torque-controlled tail drives, combined gravity and active winch take-up systems, small radius horizontal curves and belt turnovers. his paper reviews the start-up of the system, discusses the success of the design and addresses the lessons that can be learned from the first 4 years of operation of this unique conveyor system

Jan 1, 2004

By J. Shahabpour

"Breccias with angular and rounded clasts of a late-mineralization, ""barren"" hornblende porphyry dike set within a comminuted matrix consisting of rock fragments and quartz, cemented by quartz and K-feldspar of hydrothermal origin is observed in diamond drill cores from the Sar Cheshmeh porphyry copper deposit. Studies of age relationship between vein types, phyllic-altered clasts and the breccia groundmass suggest that the brecciation is a late event. The breccia clasts record evidence of hydrothermal reaction between the clasts and fluids responsible for the brecciation.Formation of bornite, in the breccia clasts of the originally barren hornblende porphyry dike, and in the breccia matrix, along with the scarcity of bornite in the Sar Cheshmeh deposit itself suggest involvement of fluids which are later and of different composition from the fluids responsible for the known mineralization at Sar Cheshmeh. These later fluids may be related to a later plutonic event and suggest the possibility of a later, and concealed deposit."

Jan 1, 1994

By P. Woo, N. Brodusch, R. Gauvin, H. Demers

For developing new technologies, it is important to characterize the microstructure of materials with high spatial resolution at the nanoscale. To achieve high resolution, field emission scanning electron microscopes (FE-SEM) were developed. These microscopes allow working at low accelerating voltage, below 5 kV, to take advantage of the reduction of the interaction volume with accelerating voltage. Furthermore, their higher gun brightness compared to conventional thermo-electronic emitters, allow a probe size at the nanoscale. At low accelerating voltage, the emission volume of backscatter and secondary electron (SE) of the type II signals approach that of SEI signals. However, it is not enough to reach the highest resolution. A magnetic field above the sample improves the spatial resolution by collecting mostly high-resolution signals. In addition, the energy-filtration of the electron signals allows selecting the type of contrast detected: topographic, compositional, or crystallographic. The development of these new technologies permits to extend the imaging capabilities of the SEM towards new nanoscale applications.

Jan 1, 2014

By Li N, Grimsey E. J

A technique has been developed for the fast measurement of the liquidus temperature of molten salt systems. The method employs a type K thermocouple embedded within the centre of a copper cylinder. The cylinder is immersed into the molten salt bath and the resultant heating curve is recorded using a PC-based data logging system. Upon immersion of the cylinder into the bath, a layer of salt freezes from the melt onto the surface. When this layer remelts during heating, the shape of the heating curve exhibits a change. The onset of this change can be detected by numerical differentiation of the heating curve, and the temperature at the onset represents an estimate of the liquidus of the melt. This work describes the technique and its application to the measurement of liquidus temperatures of MgC12 - NaCl and BaC12 - NaCl salt mixtures, in addition to a number of solidus temperatures.

Jan 1, 1996

By R. Pakalnis, Richard P. Curtin, Lewis A. Martin

Instrumented cable bolts developed at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health were used in conjunction with existing ground control to monitor rock mass loads at various field sites (FMC Granger, Getchell, Meikle, SSX, K-2, and Stillwater). Axial and shear loads were determined by strain gauges to levels of instrument accuracy of ±5 N or ±5 microstrain as these loads were transferred to the instrumented cable bolts. These gauges were 12.5 mm long and embedded into are manufactured king wire that replaced the conventional king wire. Cable bolt performance, quality of grout, and installation techniques were also assessed. By using instrumented cables, a mine operator can determine axial load along the cable at predefined gauge locations. By monitoring load on and displacement of the rock mass, more effective ground support can be selected and installed, which will lead to safer working conditions for miners.

By E. A. Trillo, L. E. Murr, R. D. Flores, J. C. McClure, B. M. Nowak

Complex vortex and swirl-like solid-state flow phenomena have been observed in the residual microstructures characterizing the friction-stir welding (FSW) of copper to 6061 aluminum; 2024 aluminum to 6061aluminum,2024 aluminum to 1100 aluminum, 2024 aluminum to 7039 aluminum and 2024 aluminum to 2195 aluminum. These flow phenomena are characterized by intercalation lamellae composed of dynamically recrystallized grain structures of the dissimilar metals which provide a super-plastic-like mechanism for the FSW flow in the solid state; there is no melting and temperatures at the weld center do not exceed about 0.8 TM (where TM is the absolute melting temperature (K)). In experiments to be described and illustrated, optical or light metallography (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques are utilized in examining residual FSW microstructures corresponding to tool rotation (stirring) speeds ranging from 400 to 1200 rpm, and traverse (or actual welding) speeds of 1 to 2 mrn/s.

Jan 1, 1999

Book review Proceedings of the Symposium on Mining Methods. London, Institution of Mining and Metallurgy, 1974. 160 pp. The Symposium was held from 30th October to 1st November, 1974, and the papers include an interesting range of subjects in coal-mining operations, covering the improvements achieved to date, current practice, and required development for the future. Salamon, M.D.G., and Oravecz, K. 1. Rock Mechanics in Coal Mining. 119 pp. NIM reports Report no. 1822 Stability constants and linear free-energy relations for the platimtm-group metals. (22nd Oct., 1976). Report no. 1852 A revised method for the dissolution of platiniferous materials by the sealed-tube technique. (18th Oct., 1976). Report no. 1828 y-picoline adducts of the nickel, copper, and zinc chelates of 2-thenoyltrifluoroacetone. (26th Nov., 1976) Report no. 1847 A pilot-plant investigation of a kinetic model for flotation.(19th Nov., 1976)

Jan 2, 1977

By Warwick Hoffmann, Robin Batterham, David Conochie

CRA has been actively involved in developing a bacterial oxidation process for the treatment of low grade, refractory gold resources. Success in this application is dependant on the design of large, energy efficient reactors. It was identified at an early stage, that the conventional, bottom sparged bioreactor is inherently inefficient because air must be compressed to a pressure above that at the bottom of the tank. This inefficiency increases as the size of the reactor increases. CRA has developed a novel approach to the aeration problem. In this, venturi aeration is used to aspirate air into a liquor stream. The stream is then reintroduced at the top of a draft tube bioreactor. The advantages found with this technique include · low energy requirements and high oxygen utilisations. From results at the 30 m3 scale, we predict an energy usage of -500 kWh/t sulphur oxidised at a scale of 1000 m3.

Jan 1, 1993

By T. Watanabe, M. Nakagawa, K. Kimapong

Ultrasonic wave was irradiated on metal surface in water to introduce compressive residual stress. The ultrasonic wave that was oscillated with 19.5 kHz ultrasonic transducer and amplified with a step type horn was irradiated. Slight plastic deformation occurred at the surface region of pure metal such as Cu and compressive residual stress was introduced. It seemed that the plastically deformed depth from the metal surface corresponded approximately to the depth of introduced residual stress. The higher compressive residual stress could be introduced into the surface of Cu-Zn brass and SUS304 stainless steel because work-hardening was simultaneously induced to those alloys. Furthermore, since martensitic transformation was induced by the plastic deformation in the case of SUS304, the compressive residual stress could be introduced more deeply into the surface region. The residual stress of SUS304 reached to the maximum value of 574 MPa by irradiating for 5min.

Jan 1, 2004

By Zay Jeffries

A. G. WORTHING, Nela Park, Cleveland, Ohio (communication to the Secretary*).-The paper by Mr. Jeffries is very interesting. He is to be commended for his pioneer work in the study of equilibrium systems at the very high temperatures which one obtains with tungsten and molybdenum. There is one statement, however, to which I must take exception. On page 1227, a statement is made which would seem to indicate that the Nela Research Laboratory joined Dr. Langmuir in the recommendation of 3,300°C. as the most probable melting point of tungsten. This is not the case. In. the paper referred to by Mr. Jeffries, I have given 3,630°K. or 3,357°C. as the melting-point temperature for tungsten. Confirming observations by other workers in our laboratory justify the belief that this latter value is correct to within a small part of the discrepancy between the two values quoted.

Jan 12, 1916