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By Derek J. Fray

"A need exists for fast and accurate analysis of species in various phases at elevated temperatures. Although modern analytical techniques are very efficient, the equipment is usually situated some distance from the industrial operation and time is spent taking the sample and sending it to the analytical facility. Several minutes can easily lapse and, during this time, heat must be supplied in order to keep the system molten and, if the composition is changing rapidly due to a refining process or reaction with the environment, the information may only be of retrospective use. Perhaps more important reasons for the use of on-line sensors are that instantaneous analysis gives better control, process optimisation and the minimisation of energy losses and pollution. To date oxygen has been the only element which is measured widely using solid electrolytes. However, the analysis of many more elements is required and possible electrolytes for other species are discussed. For some elements, ~here is no suitable conducting electrolyte and, therefore, a different approach is adopted where the electrolyte, in which one species is mobile, comes to equilibrium with another species. IntroductionThere is an ever increasing demand for the development of sensors for on-line measurements in most areas of technology and, in particular, metal processing. This is especially relevant in situations where greater control can be achieved by monitoring the chemical composition of the melt during processing and where a minor constituent in the melt can have a major effect on the properties of the finished alloy. Although modern analytical techniques are fast and reliable, the equipment due to its complexity, is frequently situated away from the process area and valuable time may be spent in sampling and transportation. During this period, heat may have to be supplied to prevent solidification and the refining reactions may be continuing, and, therefore, the analytical information may not be of direct use."

Jan 1, 1988

By Dudley L. Davis, E. C. Peterson

Introduction The Darwin District is 30 miles east of Olancha which is 220 miles north from Los z4ngeles via U. S. Highway No. 6. The ore deposits occur in the Darwin hills that have been elevated above the Darwin plateau by typical basin and range-type faults. Some of these faults have been active quite recently as shown by the displacemerit of Quaternary (?) basalt flows and the rejuvenation of erosion in Darwin wash. The ore bodies occur as fissure fillings and replacement of favorable beddings in a thick series of Paleozoic limestones, dolomites, shales and quartzites. Rich oxidized lead-silver ores were dis'Overed in the early seventies. BY 1875, Darwin had a population Of about 5000, and by 1880 several small mills and smelters had been built. Early exhaustion of surface ores, the isolated location of the district, and fluctuation Of metal prices caused intermittent operations until World War 11. The district production is estimated at about $3,000,000 prior to 1900 and perhaps $4,000,000 between 1900 and 1945 when Anaconda purchased the major producing mines. 'or the Past two Years, daily production has averaged 75 tons of direct shipping and 150 tons of milling-grade ore. At present, 300 tons of mixed oxide and sulphide ore are treated by flotation, the oxidized lead minerals being activated by addition of sodium sulphide after galena and sphalerite have been recovered from the circuit. Extraction averages 85 pct of the lead, 80 pct of the silver, and about 33 Pct Of the zinc in a bulk concentrate. The mill is designed so that minor changes permit selective flotation of pyritic lead-zinc ores encountered at depth. General Geology The oldest rocks in the Darwin hills are a series of Paleozoic limestones, dolomites, shales and quartzites probably pennsyl-vanian in age. These rocks have been intruded on the Rest by the Coso granite batholith and on the east by a granodiorite stock. Numerous sills and dikes grading from orthoclase granite to gabbro are exposed in the underground workings. The sedimentary rocks have been considerably folded and faulted, the most prominent structure being a northwest pitching anticlinal fold, the crest of which lies just west of the ridge line of the Darwin hills, The east limb of this fold has been intruded by the granodiorite stock and east of the stock the sediments show several closely spaced anticlines and synclines. The minor flexures on the west flank of the major fold are structurally important in localizing the ore in the Defiance and Essex mines of the Darwin group. There are three principal systems of faulting and fissuring, most of which are post-intrusive and premineral in age, with minor amounts of postmineral movement. The Darwin tear fault is the largest, most persistent fault in the district. It strikes N 60 to 75°W, dips steeply south and is traceable for about 10 miles. It is a normal

Jan 1, 1949

By F. J. Alcock

The Appalachian region of Canada comprises the three maritime provinces; Nova Scotia; New Brunswick; and Prince Edward Island; and that; part of the Province of Quebec lying south and east of Logan's fault. This; major thrust runs in a gently curving line from lake Champlain to Quebec; city and thence down the valley of the St. Lawrence to pass between Anticosti; island and Gaspe peninsula. To the northwest lies the St. Lawrence; Lowland division of the Interior Plains geological province; a region underlain; largely by early Palxozoic strata; which for the most part lie horizontal; or with low dips; where faults occur they are predominantly of the normal; type; and only locally are the beds cut by intrusive rocks. To the southeast; on the other side of the fault zone; an entirely different set of conditions is; encountered. There; Lower Devonian and older strata stand at high angles; are sheared and thrust faulted; and are intruded in many places by granitic; igneous bodies. The present paper is designed to outline briefly the geological; and structural history of this geological province and to emphasize; the part that structural conditions have played in connection with mineral; deposition.

Jan 1, 1954

By Yanlong Li, Lifeng Zhang, Ying Ren

In this work, a multiphase mathematical model for the fluid flow in argon-stirred steel ladles was established and validated by experimental measurement of wood's metal. Alloy dispersion in the molten steel was calculated. The melting and mixing of alloy was faster with smaller size of the alloy particles, larger superheat and bigger slip velocity. The current mixing time is approximately 300 s with 30 mm alloy diameter and 91.5 K superheat.

Jan 1, 2014

By Charles W. Huggins

Electron diffraction and electron microscopy were used to determine the unit cell parameters of garnierite [(Ni,Mg)3 Si2O5 (OH)4] and to examine its crystal habit. Bundles of ribbons, many less than 200 A. in cross section, make up the bulk specimen of the garnierite Electron diffraction revealed the unit cell to be monoclinic. Unit cell parameters were: a, 5.33 A,; b, 9.23 A.; c, 14.96 A.; and ß, 94°441.

Jan 1, 1961

By T. Richard Davies

This paper primarily deals with the application of wearfacing materials and their role within a well-established preventive maintenance welding program. Some examples are shown, as well as a synopsis of possible benefits and a compendium of methods and materials.

Jan 1, 1979

Following the experimental work of Denny, Robson, and Irwin, and the clinical investigation by Crombie and Blaisdell, an investigation of aluminium therapy was begun at Washington, Pa., which is situated In a very large industrial section of the State. Some of the men to be studied were from plants manufacturing silica brick, refractories used in steel and glass manufacturing, and semi-porcelain table-ware; others were workers in foundries, sand blasters, and men engaged in the quarrying of ganister rock.This group of workmen gave an opportunity to study the effects of aluminium on various types of silicosis which differed somewhat from that found in hard-rock miners.EXPOSUREIn their occupations, the men studied were exposed to silica dust concentrations ranging from 17 to 97 per cent free silica. In the silica brick industries, the unfired product averages 96 per cent silica in the form of quartz, whereas the fired brick contains 50 to 62 per cent. cristobalite plus 11 to 80 per cent. tridymite, forms of silica that, on account of their higher solubility, are more toxic than quartz. The operational dust counts in the plants varied from 15 to 9,500 particles per c.c., and the median particle size from the aerial samples was 1.0 micron for the green product and 2.0 microns for the fired product. The length of exposure varied with the occupation as well as with the individual plant, but disabling silicosis could be produced in less than four years in certain exposures. The average time needed to produce radiological silicosis in those susceptible to this disease was eight years. Some of the men in our series of cases have been treated as long as fifteen years after exposure had ceased, and have improved under treatment.The dust counts mentioned above had been reduced prior to the aluminium therapy studies and the presen.t exposures do not exceed '900 particles per c.c., the average being 370 particles. per c.c. This improvement in dust conditions was due to improved dust control apparatus, which was installed before aluminium therapy was instituted. Aluminium powder is not a substitute for dust control.PATHOLOGYThe pathological picture of silicosis in men engaged in the ceramic industry is somewhat different from that in hard rock miners." Due to exposure to high concentrations of dust containing high percentages of silica of varying degrees of solubility andvery small particle size, these men are subject to a relatively rapid type of silicosis, which sets up an acute...

Jan 1, 1945

By M. W. Gilmore, J. Ndlovu, T. Sepoloane, Anglo American Platinum, L. R. Nelson, R. N. Varty, L. J. Bryson, B. Peyper, J. P. Hagemann

"As part of Anglo American Platinum’s Rustenburg Base Metals Refinery (RBMR) expansion, a new Nickel Electrowinning Tank House, with a nameplate capacity of 32 400 tons per annum, was constructed. Commissioning of the new electrowinning technology, which involved world first full deposit plating, commenced in 2011.The old nickel electrowinning process at the RBMR used starter sheets which, along with a divided cell configuration, was very labour intensive and exposed operators to high levels of aerosols that contained both nickel and acid. To overcome this problem two key design intents of the new technology are aerosol abatement and minimising labour in the electrowinning cell environment, with a design target to reduce the nickel occupational exposure limit (OEL) to half the legislated limit of 0.1 mg.m-3.Commissioning of the new technologies adopted to achieve mist abatement is described, together with a review of technical and operational challenges relating to the titanium blank edge strips, blank roughness and sandblasting optimisation, blank quality control, electrode spacing, polyconcrete cell dimensional stability and cell top furniture. The impact of these on process performance is presented and the development of fault checking and rectification methods, to maintain high process performance, is explained.INTRODUCTIONThe expansion of Anglo American Platinum’s Rustenburg Base Metals Refinery necessitated the construction of a new Nickel Tank House to achieve two primary objectives, namely increasing the nickel electrowinning capacity from 22 500 tons per annum (tpa) to 32 400 tpa nickel, and a design to reduce the nickel aerosols to 0.05 mg.m-3 as a time weighted average over 8 hours, which is half of the legislated occupational exposure limit (OEL) of 0.1 mg.m-3."

Jan 1, 2016

By M. J. DeJong, R. J. Mair, S. Ritter, G. Giardina

"For urban tunneling projects it is essential to predict and prevent building damage. Although various case studies and experiments have shown that buildings considerably modify greenfield soil movements, widely accepted damage assessment methods neglect this soil-structure interaction and simplify structures as linear elastic beams. This paper summarizes an experimental investigation of the response of more realistic structures to tunneling-induced deformations. Small scale structural models with façade openings and brittle material properties were 3D printed and tested in a geotechnical centrifuge. Soil and structure displacement data were obtained by image-based measurement. Results demonstrate that structures notably mitigate differential greenfield ground displacements. It is also shown that maximum soil settlements, horizontal soil displacements beneath the structure and structural damage in the form of cracking significantly depend on the position of the structure in the settlement profile. The results provide a basis from which to predict building settlement response with greater certainty. INTRODUCTION With continuing population growth and increasing urbanization expected in the next decades, there is an urgent need for a next generation of infrastructure. It is likely that a large part of this infrastructure will be underground. Such creation of urban underground space frequently involves the excavation of shallow tunnels in close proximity to existing structures and utilities. For example, along the Crossrail project in London more than 1,200 structures are located within a possible influence area of the tunnel construction (Torp-Petersen and Black 2001). The assessment of building damage plays a vital role throughout the planning, design and construction stage of urban tunneling projects. However, while predictions of tunneling-induced deformations in the greenfield can generally be made with some confidence, much uncertainty exists about how structures interact with ground movements arising from tunnel construction."

Jan 1, 2016

By Lev Filippov, Lorène Dessalas, Inna Filippova, Yves Foucquet

"Seafloor massive sulphide (SMS) deposits, similar in composition and genesis to terrestrial volcanogenic massive sulphide deposits, are generally found in volcanic seafloor environments along major rifts and mid-ocean ridges. Theyare associated to extensional tectonic settings such as nascent-arc, rifted-arc and back-arc environments. They may represent important source of base metals and be an alternative to on-land resources. Seafloor massive sulphide deposits have particular mineralogical compositions and textural features differentiating them from terrestrial one. When extracted from salty water and exposed to the ambient air, massive sulphide samples strongly oxidize and soon become covered by thin layers of iron, copper and zinc rich sulphates and oxides, as well as elemental sulphur. The textural properties vary according to the degree of maturity and the sample position within the hydrothermal deposit. The total porosity of that type of samples is also relatively high, especially for immature samples such as black smoker chimneys, which can reach 15% of total porosity. Because the secondary mineralization and porosity level are different, seafloor massive sulphides ores respond differently from terrestrial ore to processing methods. Froth flotation, commonly applied to separate all type of sulphides from the gangue, is one possible technique for processing seafloor ore. Sulphide recovery rate is, in most cases, excellent (>90%) however separation of the various mineral phases is difficult to obtain even when applying known methods used for terrestrial ore. Moreover, the flotation behaviour decreases drastically with the time of conservation at the surface, even when the samples were stored in a confined environment. High pH values, which is a good way to depress pyrite and therefore to favour the flotation of copper and zinc sulphides, do not have the same effect on seafloor ore. Consequently, careful flotation procedure must be elaborated to obtain efficient mineral separation technique for this specific marine ores."

Jan 1, 2014

By Ande&apos, Bengt n

The first Model 480 SALA-HGMS R carousel high gradient magnetic separator was recently manufactured (Figure 1). The carousel's design was based upon the high gradient magnetic separation technology developed and owned by Sala Magnetics Incorporated, Cambridge, Massachusetts. After a short (approximately 300 hours) in-house mechanical and electrical test and break-in period, the carousel was ready for a long term demonstration test. This paper describes the demonstration plant and operational performance of the Model 480 HGMS treating a low grade iron ore tailings. A location convenient to Sala International's main office in Sala, Sweden was desirable because Sala engineers and technicians were to operate the demonstration plant. The Strassa iron ore mine in central Sweden was chosen because it fit most of the criteria that was important for a good demonstration site. The Strassa mine is part of the state owned Svenskt Stal AB. The mine produces about 320,000 tons of iron concentrate per year consisting of 200,000 tons of magnitite concentrate and 120,000 tons of hematite concentrate.

Jan 1, 1980

By Hemendra N. Kalia

Several attempts have been made in the past sixty or so years to commerciliaze the vast oil shale deposits of the United States of America. However, the industry has yet to become viable and economic. To date, it has not been possible to produce oil from the oil shales at a competitive price when compared to the oil produced from oilfields by conventional methods. However, the development work has been quite fruitful in furthering the art of thick bed mining and technology of in situ retorting. The in situ method has the potential of recovering oil from thick beds and the resource recovery potential is much greater than that from underground mining and surface retorting. In situ methods require that the shales/ marlstones be fragmented ' in place to induce adequate porosity and permeability to allow in situ' heating of the fragmented shales. This can be accomplished by using explosives. However, it has been found that the existing blasting systems, though very efficient, are somewhat lacking. The explosive become insensitive when shot in multiple vertical decks. They can also become insensitive when spaced horizontally at close proximity to other charges. Also, since the blasting is done in a very limited free face, this limits the delay time that can be allowed between charges. Consequently it is not always possible to predict the performance of the blasting system on a routine basis. Furthermore, since it is not possible to undertake secodary blasting, it is imperative that the blast design function properly. Recent, successful retorting by Occidental Petroleum Company of retorts seven and eight suggests that some of these problems may have been overcome. This paper addresses some aspects of in situ retorting and problems those have impeded the development of a viable oil shale industry in the U.S.A.

Jan 1, 1983

By M D. Uttarwar, R R. Yerpude

India is the world’s third-largest producer of coal and is endowed with the fifth-largest coal reserves in the world. Surface mining straddles the entire domain of the Indian coal mining industry, yielding over 88 per cent of production. With continually rising domestic demands, it has to shoulder the responsibility of sustaining the requisite increase in coal production and chasing commensurate stripping targets. Such an ambitious task calls for the deployment of smart technologies. In such a demanding situation, cast blasting of overburden has emerged as a promising alternative for enhancing production and productivity of dragline pits.The cast blasting technique reduces stripping costs significantly as it utilises the chemical energy of explosives in place of mechanical energy to move large volumes of overburden quickly. Proper application of cast blasting not only reduces overall mining costs but also increases coal production. This paper investigates and evaluates the potential of the cast blasting technique, with special reference to dragline pits employing the rehandle method of extended bench. The economic feasibility of the technique is also ensured under different scenarios so that considerable benefits would accrue to the individual surface coalmines. To underline the efficacy of the technique, different cast blasting models have been formulated under a range of operational and economic scenarios that resemble present day practices in India. In order to test for economic variability in the application of the technique, a risk analysis of all the formulated cast blasting models is performed using net present value.CITATION:Uttarwar, M D and Yerpude, R R, 2015. Potential of the overburden cast blasting technique in Indian surface coalmines – a modular approach and its financial implications, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 655–664 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By D Walker, A Tsvetkov, P Voigt, O Kloiber-Deane

The GPM Gold Operation has been employing an Albion Process™ plant at its Sotk (Zod) gold mine in Armenia since 2014. Long term data from the operation is now being published for the first time. The data presented includes concentrate throughput, as feed to the Albion Process™ plant (tonnes per day), sulphur grade in concentrate (% S), total sulphide sulphur oxidation in the Albion Process™ plant (% SOx) and gold recovery from Albion Process™ plant residues (%). The data provides a basis for evaluation of the effectiveness of the commissioning, ramp up and operation of the Albion Process™ plant. Notwithstanding the impact of a slower concentrator commissioning than expected, the plant demonstrates Series 1 behaviour on McNulty ramp up curves, indicating successful commissioning and fast ramp up. Interrogation of the data and operational experience indicates that this successful operation is a result of a process that is flexible, robust and stable, one that was designed well based on solid testwork results and pilot plant trials during the study phase undertaken by Glencore Technology and Core Resources, and where the local operators were provided with appropriate training in operation of the plant. CITATION:Voigt, P, Walker, D, Kloiber-Deane, O and Tsvetkov, A, 2018. Ramp-up and long-term performance of the Albion Process™ plant at GeoProMining Gold Armenia, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 339–350 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By V. Panayotov, M. Panayotova

"Wastewater from ores processing is often polluted by molybdate and sulfate (SO42-) ions. Sorption is one of suitable methods for removing those pollutants when presenting in low concentrations. This work reports results on adsorption of sulfate and molybdate ions on metal modified (with barium - Ba and lead - Pb) and organic reagent modified (with Hexadecyl-trimethyl-ammonium bromide - HDTMA) clinoptilolite. Zeolite’s modification with Pb, Ba and HDTMA increases its uptake capacity with respect to Mo(VI) at pH 3, with the uptake capacity decreasing in the order CL-Pb > CL-HDTMA > CL-Ba. Lead-modified clinoptilolite shows high uptake with respect to Mo(VI) in acidic, neutral and slightly alkaline conditions. The presence of SO42- in concentrations twice higher than the amount of Mo(VI) do not interfere with the Mo(VI) removal by CL-Pb. Zeolite’s modification with Ba and Pb renders it able to immobilize SO42- from water in the pH range 3-9. Kinetics of the uptake process is best described by the pseudo-first order kinetic equation. Increasing the initial concentrations of Mo(VI) and SO42- increases the removed amount of pollutants. INTRODUCTION Wastewater from copper-molybdenum ores processing is often polluted by molybdate and sulfate ions. Molybdenum (Mo) migrates easily in water and consequently the Mo polluted areas could extend for hundreds and thousands of meters (Ryzhenko, 2010). Molybdate anion is the only Mo(VI) species in natural water, i.e. at pH > 6.0. Its median freshwater hazardous concentration affecting 5% of the species (HC 5.50%) is 38.2 mg Mo/L (De-Schamphelaere et al., 2010). The marine water chronic toxicity (HC 5.50%) is assessed at 5.74 mg Mo/L (Heijerick et al., 2012). The predicted no-effect concentrations (PNEC) are 12.7 mg Mo/L and 1.92 mg Mo/L correspondingly for freshwater and marine water (Heijerick et al., 2012a). When sulfates present in drinking water in excess of 250 mg/L they cause a cathartic action (especially in children) in the presence of sodium and magnesium, and when the concentration exceeds 600 mg/L, diarrhea. When sulfate-rich effluents are discharged into the environment, they may increase the acidity of water bodies and soils (Guimarães and Leão, 2014). Because of the adverse effects to human health and the environment, limits are set for SO42- concentrations in waters and wastewaters in the range of 250 / 500 mg/L."

Jan 1, 2018

By P. Lenegan, R. Masethe, R. I. L. Ferreira

Underground mining in high rock-stress environments can induce unanticipated dynamic rockmass deformation, posing a serious risk to the workforce. Data collected by seismic networks are imperative for the design-as-you-mine process. Often an inappropriate assessment of the seismic hazard is done when unnecessary data are included in analytical techniques, particularly short-term time frames. Depending on the methodology or application of data analysis and interpretation, some of the information may not be relevant and even detract from the objective. By using the spatial event clusters associated with active workplaces to define the shape and size of the polygons for data selection for subsequent analysis, a problematic subjective component can be eliminated. The mining of tabular reefs in South Africa, be they gold- or platinum group metals, is very extensive, and underground workplaces are often widespread. Production stoppages are very costly, especially for marginal mines, so there is just cause not to evacuate an entire operation’s workforce following the occurrence of a large mining-induced seismic event. A rationale based on the damaging peak particle velocities (PPV) of the past seismicity can exclude the unaffected underground personnel and allow a quick orderly withdrawal where required. Micro-deformation may precede rockbursting, which can occur on-shift close to the workface. A mine-wide array of geophones suitable for the accurate location and analysis of seismicity may not be able to detect these higher-frequency emissions. Inexpensive but fit-for-purpose accelerometers, providing real-time, continuous measurement of acoustic rockmass deformation near the workplace, integrated through underground and surface communications networks, are shown to record ‘rock-talk’, clearly distinguishable from the instrument background noise, which can be in the order of hours leading up to an imminent damaging seismic event.

Jan 12, 2025

By Toshihiko Emi

The quest for cleaner steel is driven by increasingly stringent requirements from the manufacturing and construction industries. Key issues are the occurrence and removal of inclusions; These are discussed in the context of the unit processes of deoxidation, refining, transfer and casting of molten steel. Process thermodynamics and kinetics are also discussed. Recent progresses achieved and problems yet to be solved are elaborated, and an integration of the unit processes into a system to produce extra clean, steels with better performance is presented.

Jan 1, 1999

By Georges Cote, Ehsan Alavi, Eren Kusdogan

The City of Toronto's Coxwell Bypass Tunnel is currently being constructed by North Tunnel Constructors (NTC) ULC, a joint venture of Jay Dee Canada, C&M McNally Tunnel Constructors and Michels Canada. This project includes construction of approximately 10.5 km of 6.3 meter finished diameter rock tunnel, five 20 meter diameter storage shafts and eleven tunnel connection drop shafts, along with associated deaeration and adit tunnels. 120 m of Starter tunnel and 70 m of Tail tunnel were excavated with roadheaders to help with the launch of the TBM and as part of the contract base scope work. JayDee Canada in Collaboration with Everest Equipment Co. developed an innovative approach to design and build a stand-alone Ring Machine Erector nicknamed Enterprise to erect precast segmental lining in Starter and Tail tunnels in lieu of Cast-In- Place concrete. This paper describes the design and provides feedback on the innovative procedure used to install the rings.

Jun 23, 2024

By Kyle A. Perry

Pillar design formulae have existed for decades, and the guidelines for design stability factors are generally accepted by regulatory agencies and broadly used within the coal industry. Nearly all design pillar formulae are based on geometrical parameters of pillars resulting from empirical investigations, with primary focus on the pillar width-to-height (W/H) ratio and associated shaping constants from regression. The most widely used modern pillar design formula in the coal industry, the Mark- Bieniawski equation, also adheres to this principle. Common practice when applying Mark-Bieniawski equation is to use a coal compressive strength of 900 psi. This reduces the design equation to sole dependence upon geometry. However, recent studies have shown that pillar strength is highly dependent on roof and floor properties, particularly the interfaces between the roof-pillar and pillar-floor. This study utilized numerical modeling using FLAC3D to evaluate the relative effects of varying roof and floor interface and mechanical properties. The results confirm that pillar strength is significantly influenced by the properties of the coal pillar interfaces with roof and floor. The mechanical properties of the roof and floor material have only a minor impact on pillar strength when compared with interface effects. These results were used to formulate design recommendations for existing pillar design methods.

Jan 1, 2013

By M. W. Pullen

It is recognized that the determination of electrical resistivity of the earth within a given area may furnish information concerning the location of certain mineralized strata of economic importance. Present knowledge of the electrical resistivity of the various rock formations is almost nil, and the geophysicist who is detailed to make a survey of an area without any data as to the relative resistivity of the underlying rocks is greatly handicapped. Such surveys are usually made within areas known to contain mineral deposits to aid in locating desirable points for drilling. Usually these areas have been prospected by diamond drilling, and drill cores of the various rocks and ores are usually obtainable. Were it possible to make resistivity tests in a laboratory of the drill cores or from pieces of the rocks and ore within an area before attempting a field survey, this would indicate not only the advisability for such a survey but would aid considerably in the interpretation of the results of such a survey. To be of most value a definite method should be used for all such tests, and as yet such a method has not been established.

Jan 1, 1929