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By H. P. Jacobi

"The last 25 years have seen tremendous economic pressure placed upon the base metal processor. Industry has responded with technological innovations that have contributed to significant reductions in capital and operating costs. Major changes in processing machinery and philosophy are highlighted for the main unit operations of a base metal mill. Changes in our attitudes on what is environmentally acceptable are also discussed.INTRODUCTIONNewton's law of motion paraphrased states that nothing will change unless there is a pressure to do so.Aase metal processing as a primary commodity related industry has been under severe economic pressure over the last 25 years. This has been brought on by over capacity from new operations in the L.D.C. 's, through material substitution in a host of traditional base metal applications and generally reduced world-wide economic activity. In addition to shrinking markets our collective environmental consciousness has raised effluent standards and workplace hygiene and the employee's as well as government's economic expectations of how much ought to be derived from ''nature's riches''.Industry has responded with technological changes which, it was hoped, would counteract the cost squeeze in which it found itself.I would like to briefly enumerate the major changes, as I see them, that have taken place in the main unit operations that form the normal processing chain for base metals.While the following paper will mention several brands of products, I would like to emphasize that these are the ones that I am most familiar with and is not to say that they are the only manufacturers which have contributed to changes. In fact it ls fair to say that all makers of mining and processing equipment have made improvements to their products, to a greater or lesser degree; they have had to, to still he in business in 1986."

Jan 1, 1987

By P. Burke, V. Vuaroqueaux, A. Doyle, C. Petit, Kipouros. G. J.

Magnesium and its alloys are attractive for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. The present work reviews the efforts to improve the attractiveness of magnesium through non-traditional processing, and presents results of current work on producing magnesium alloys via powder metallurgy (P/M). P/M can be used to alleviate the formability problem through near-net-shape processing, and also allows unique chemical compositions that can lead to new alloys with novel properties. The surface layer formed on the Mg powders during processing acts as a barrier to diffusion and sintering is problematic. The layer contains oxides, hydroxides and carbonates of magnesium, formed by reactions with the atmosphere. There are several means to possibly overcome this barrier. Alloying additions have been identified that may promote surface layer disruption during sintering. Processing variables such as sintering atmosphere may reduce the layer or allow the formation of less detrimental compounds. Post-sintering processes such as hot working may disrupt the layer and improve density. The experimental effect of all these processing parameters is presented in this paper.

Jan 1, 2010

By M. Reda

Inorganic oxidizing agents of the type MeOx-z such as Chromate, Vanadate, Tungstate, and Molybdate... etc. are widely used as corrosion inhibitor. In non acidic solution these oxidizing agent are reduced on the surface of the meta, according to OX + m e + p H20 Red + n OH" In which y = (n-m)/m. The purpose of this publication is to show that for many metals the value of y for any oxidizing agent determines the possibility of that oxidizing agent being an inhibitor or activator for the corrosion process. The inhibition efficiency for other ions such as Pertecnetate and Tellurate which have not been extensively studied can be predicted. A mathematical, equation was derived to express the relationship among the concentration of oxidizing agent, degree of retardation of the corrosion process I cord cor ° (ratio of corrosion current in the solution containing inhibitor to the base solution) , ionic strength of the solution and the coefficient y. The validity of y and the mathematical, equation were verified by many experimental, works on various metals such as zinc, aluminum and steel. Al, the above research works are based on the published research works of Prof. Mikhailoviskii (from 1979 til, 1998) from the Russian Academy of Science.

Jan 1, 2010

By C. R. Stelck

"AbstractThe Cardium formation of northeastern British •Columbia •contains an erosional unconformity that becomes progressively more severe northward until, •at Liard river, the stratigraphic hiatus eliminates the underlying Lower •Cardium sandstone, the Kaskapau formation, and the upper Dunvegan sandstones. The area of unconformity roughly coincides with the distribution of the continental facies of the earlier Dunvegan formation. Along Wapiti river, the zone fossil Scaphites ventricosus Meek and Hayden is found in the Bad-heart member of the overlying Wapiabi shale; Scaphites :preventricosus. Cobban marks the base of the Wapiabi shale; Scaphites cf. corvensis •Cobban is found in the middle shale member of the •Cardium formation. The log of the Red-Willow No. 1 well shows close similarity to the outcrop sections south of Wapiti river. The Cardium formation is mainly late Turonian in age. Two other pre-Cardium Turonian sands of north-eastern British Columbia are named the Wartenbe and Tuskoola sands.IntroductionTHE Upper Cretaceous Cardium (Bighorn) sandstone formation of the Foothills of northeastern British Columbia carries within its formational limits an erosional unconformity. The unconformity decreases to the southeast, becoming in immediate shoreline regions, now under the plains, a minor diastem. Such diastems, or stratigraphic intervals of non-deposition, occurring in the shallow unda-zone are paralleled in the deeper portions of the unda-zone by the phenomena of sub-aqueous winnowing. '.This winnowing and re-working •at critical depths creates sand areas with porosity."

Jan 1, 1955

By M. Alvarez-Silva, A. Uribe-Salas, J. A. Finch, M. Mimezami

The point of zero charge (PZC) of electrokinetically anisotropic minerals (chlorite and serpentine) was determined using the Mular-Roberts (M-R) titration technique, and compared to isoelectric point (IEP) obtained from electrophoretic mobility measurements. To validate the M-R technique, the point of zero charge and isoelectric point of two isotropic minerals (alumina and silica) were shown to be comparable. For serpentine and chlorite, respectively the PZC was found at pH 4.3 and 4.6, while the IEP occurred at pH 3.2 and <3. Settling tests showed that the maximum settling rate, which corresponds to aggregated particles, for chlorite was around pH 3, i.e., close to the IEP; lizardite did not show a conclusive maximum.

Jan 1, 2009

By A. Alfantazi, E. Asselin

"The corrosion of commercially pure titanium (CP-Ti) was studied from room temperature up to medium temperature (~160°C) under conditions relevant to medium temperature chalcopyrite leaching processes. The corrosion rates were measured by immersion and electrochemical tests in sulfuric acid. The influences of chloride, cupric and ferric ions on the corrosion rate and behavior were also investigated. Corrosion of the CP-Ti did not account for the total current density measured by linear polarization tests. The corrosion rates of CP-Ti under medium temperature leaching conditions were surprisingly high. The corrosion rate measured in ferric containing solution at 160°C was approximately 20 mm/yr.INTRODUCTIONTitanium exhibits excellent corrosion resistance in many aggressive environments because of the formation of a very chemically stable, highly adherent, and protective oxide film on its surface (Mitsuo et al., 2002). Because titanium is the only metal available at a reasonable cost that resists the high temperature corrosive slurries in many leaching processes, it is often chosen as autoclave liner material where it is subjected to severe conditions of acidity, temperature and pressure (Grauman and Say, 2000).A number of distinctly different hydrometallurgical processes for the pressure leaching of chalcopyrite have been developed and patented by various companies and they can be classified into low, medium and high temperature regimes (McDonald and Muir, 2007). For example, chalcopyrite concentrate may be processed at medium temperatures (115-175°C) and pressures of 800-2200 kPa (Dreisinger, D., 2006; Sahu and Asselin, 2011). The lixiviant may contain 20 to 55 g/L sulfuric acid, 8 to 12 g/L chloride ions, 10-25 g/L Cu2+ (Jones, 1995, 1997, 1999), and less than 1 g/L Fe3+ (Defreyne et al., 2005). The amount of these additions is determined by the grade of the ores and details are shown in Table 1."

Jan 1, 2012

By Pierre Gaucher

It is possible to selectively mine an orebody by combining the use of the SSW probe with any bulk mining methods as well as narrow vein exploitations. In other words, thanks to the use of the SSW probe, mining operators will be able to reduce and control dilution that is generally associated to every mining operation. Already, quick and substantial savings have been obtained. Falconbridge mines have demonstrated in Sudbury and Raglan operations, that the SSW probe can log nickel, copper and iron sulphides in blast holes. They have raised the grade and reduced dilution by outlining the limits of the ore zones before selectively loading explosives in the blast holes. By lowering the probe in a blast hole, a profile of the ore content is instantly measured and recorded. Logging cored diamond drill holes at the mine have demonstrated that the ore content (nickel, copper, cobalt, PGM) as assayed is proportional to the intensity of the probe?s electromagnetic response (EM), probably because the nickel / pyrrhotite ratio is uniform within a given orebody. The probe also measures the intrinsic conductivity of the sulphides and the percentage of magnetite. All probe readings are displayed and automatically stored at a 10-cm interval within the same reading unit. A 30-meter blast hole takes less than 2 minutes to survey. The whole instrument is light (12 kg) and very simple to use. One operator can carry the SSW system and survey either down or up-holes. The probe works from ?40°C to +50°C. Plotting the measurements of the SSW probe in blast holes (2-3-4-6-10 inches in diameter) before blasting allows to determine the exact shape of the orebody within the waste rock and uneconomic low-grade ore. Thus, only the portion of the holes that contains ore is blasted. The dilution is then much reduced and, by leaving the waste and low-grade ore in place, the mine saves on transportation, blasting, crushing, backfilling, milling, etc. Thousands of dollars are thus saved. Some savings may also be achieved during the development of stopes by guiding development drifts and by replacing diamond drilling by percussion drilling. In some circumstances, when the probe shows that some of the rich ore was not drilled-off, additional blast holes will allow to recover pockets of rich ore that otherwise would have been abandoned in the walls of a stope.

Oct 1, 2001

By A. Pearson, F. A. Auld, S. O. Colbeck

"""The theory of buckling of shafts and Steel tunnel-linings"" was published by E. Amstutz in 1970 and commented on by S. Jacobsen in 1974. The authors have revised and enhanced Amstutz’s work to address Jacobsen's comments on its limitations and to extend its validity over a wider range of pipe/shaft geometries, including those commonly found in deep mine access shafts. The author has looked at Amstutz’s assessment of strengthening with flexible shear anchorages and adapted the theory of non-linear shear deformation response of bolts to develop a method of assessing increased buckling capacity utilising the full plastic shear capacity of studs. INTRODUCTION “Amstutz Buckling” refers to the buckling of pipe embedded in concrete under external uniform pressure. In terms of a mining environment, this relates directly to the design of a watertight shaft. This load case will commonly occur where a main shaft is cast against a geostatically stable primary liner and the only load applied to the final shaft is that of a uniform ground water load. Ernst Amstutz wrote his first paper on buckling of pressure-shaft steel linings in 1950 and subsequently improved his theory (Amstutz, 1970), which was then widely adopted for use within the industry. Years later, an alternative approach (Jacobsen, 1974) was proposed. Within his paper Jacobsen critiques Amstutz work, identifying some mathematical inconsistencies and highlighting limitations of the theory imposed by approximations adopted by Amstutz. Despite these limitations Amstutz work has still been used as the favoured design theory for use in the mining industry. In reviewing this body of work the author realised that with the advent of readily available computing software it was possible to adopt an iterative approach using Amstutz approximate formulae to find a solution to the original precise formulae, thus eliminating the limitations highlighted by Jacobsen The shear deformation to load characteristics of bolts has long been established (Crawford & Kulak 1968) and used for the plastic design of bolted connections in shear. This relationship is directly transferable to the design of shear studs, typical properties are well known, and actual values easily established in simple lab tests. The author has taken this relationship and modified Amstutz theory (Amstutz, 1970) for shear anchored strengthened liner buckling, to give a more efficient solution, using readily available material properties."

Jan 1, 2019

By J. N. Brooke

"This paper deals with the training of the mining and mineral engineer and the role that these professional people must play in their company environment, particularly in relation to management.THERE IS SOME CONCERN in the mining industry that the numbers of engineering graduates attracted to it and the academic training that these people have received is inappropriate. Evidence for this is:1. -The meetings and studies initiated by the various mining engineering societies to discuss:(a) attracting students and graduates to the industry; and (b) the appropriateness of the present academic training for the needs of the industry."

Jan 1, 1968

By L. Lui, A. Cauchon, A. R. Laplante

"The gravity circuit at Les Mines Camchib Inc. consists of two pinched sluices to bleed a feed to one of two 76 cm (30"") Knelson concentrator. The Knelson concentrate is upgraded to smeltable grade with a smaller Knelson (18/30 cm) and a riffleless table. Their tails are column cyanided and washed prior to recycle to the grinding circuit. This paper details size-by-size circuit performance. The Knelsons recover around 90% of free gold (as determined by Mozley Laboratory Separator), even below 37 µm. The sluices are ineffective, with upgrading ratios around 2, but approaching unity in the fine sizes. Much of the effectiveness of the circuit lies in the high gold circulating loads in the grinding circuit, which partly atone for the poor sluice performance, and the ability of the Knelsons to recover free gold. Secondary upgrading recovers slightly above 99% of the primary concentrate gold, 90% of it in a 65% Au concentrate and the balance in a heavily loaded (10 to 20 oz/st) pregnant solution. INTRODUCTIONBackgroundThe operating performance of the mill of Les Mines Camchib Inc. has been described earlier (Laplante et al., 1989). The presence of significant chalcopyrite (1 % and up) makes flotation necessary prior to cyanidation, to limit cyanide consumption and minimize environmental impact. In 1982, the presence of very high gold circulating loads in the grinding circuit lead to the commissioning of a gravity circuit, schematically shown in Figure 1. Gravity recovery of gold has been found beneficial because it increases metallurgical recovery by 1-3% (Laplante et al, 1987), as only part of the flotation tail is cyanided, and economic recovery, because of the lower net smelter return of gold in the flotation concentrate (as compared with the gravity concentrate). The latter increase is estimated, with a net smelter return of 95%, at 1.5% when gold recovery by gravity is equal to 30%. In early 1988, a sampling program was initiated to characterize the behaviour of gold in the grinding/gravity circuit. This paper reports on the results of this study."

Jan 1, 1990

By Norman B. Davis

Introductory Feldspar is one of the most important mineral products consumed by the various branches of the ceramic industry. In the manufacture of table ware, electric porcelain, floor tile, and enamels, it supplies the chief fluxing ingredients necessary to bond the other more or less inert materials together when moulded into desired shape and fired in a kiln. Feldspar is used in the manufacture of bottle glass as a means of introducing alumina in a form easily assimilated. It is also used in certain scouring soaps particularly designed for cleaning enamel and glass surfaces. Feldspar, as it finds its way to the trade, is not a single mineral but is rather a mixture of various proportions of the feldspar silicate series, either in natural intergrowth or blended in the milling process, to produce a desired result. It is often further modified by the presence of quartz in amounts up to 30 per cent. The table on the next page gives typical commercial analyses of feldspar from various sources. Canadian feldspar produced to date has consisted mainly of the high-potash, relatively low-soda, variety, and has enjoyed a good market in the United States for the manufacture of enamels, electric porcelain, and vitrified table-ware. About eighty per cent of the output has been exported to the United States, but, with increased milling facilities in Canada and changes taking place in domestic United States sources of supply, the proportion exported will be reduced next year.

Jan 1, 1931

By E. Dernedde

Industrial plants located in the province of Quebec, Canada, are subjected to large variations of the ambient air temperature, Building ventilation systems of these plants must have some flexibility in order to meet industrial hygiene standards (TLV for chemical substances, heat stress and cold stress) at any time of the year, The building ventilation of a bath treatment plant of an aluminium smelter in Quebec was examined under summer and winter conditions, Part of the plant has periodic emissions of hydrogen fluoride gas and heat from hot anode butts, CFD modeling was used to optimise the building ventilation of the bath treatment plant, The present study proposes a modified building ventilation system, which improves the internal environment, complies with industrial hygiene standards and also reduces heating costs by 20 % during winter.

Jan 1, 2005

By J. Laganiere

A considerable part of the sulphuric acid requirements of the Aluminum Company of Canada&apos;s Arvida smelter comes from the burning of 180-200 tons per day of zinc &apos;"&apos;sulphide concentrates in a 22-ft.-diam-eter fluidized bed roaster. The plant and its operation were fully de-scribed in a publication that appeared about ten year ago (1). A simplified flowsheet of the roasting and gas-cleaning sections of the plant is given in Figure 1. The wet zinc sulphide concentrates are un-loaded into a pug mixer, by means of a Pay loader, and mixed with water in a mixing tank to make a slurry of 80 per cent solids. The slurry is transferred to a .feed tank and then introduced into the roaster at a point four feet above the constriction plate, which is the height of the settled bed of zinc calcines. The roasting temperature is con-

Jan 1, 1963

By L. A. Ayres da Silva, J. P. G. Negri, A. L. M. Ayres da Silva

"Rock hardness is dependent on the type and quantity of the various mineral constituents of the rock and the bond strength that exists between the mineral grains. As the book “The Complete ISRM Suggested Methods For Rock Characterization, Testing and Monitoring:1974-2006” explains, hardness is a concept of material property. As such, the quantitative measure of hardness depends on the type of the test employed.Among the three types of tests that have been used to measure the hardness of rocks and minerals: 1) indentation tests; 2) dynamic and rebound tests; 3) scratch tests, the authors of this paper chose indentation tests, more specifically the Vickers test, and complementary verified the correlation between the results of the Schmidt sclerometer tests (rebound tests) and the Vickers microhardness tests in a set of the same 9 (nine) granite rocks.The objective of this research was to verif y the correlation of one created index, based on the Vickers test that can be able to represent the rock material hardness. We know that Vickers tests determine the microhardness of individual rock minerals. A pyramidal shaped diamond is applied to the surface with a specified force. The area of the permanent residual deformation divided by the applied force is a measure of the hardness. Using the relative participation of the mineral components of the rock, we established a hardness index denominated EVM (Equivalent Vickers Microhardness).The correlation of the EVM with others strength properties and application parameters like UCS (Uniaxial Compressive Strength) to study sawability of granite blocks have presented very good results. The association of equivalent microhardness with others strength parameters, allowed to find powerful algorithms for analyzes of the rock materials behavior under diversified circumstances, as the sawability of granite blocks, as we can see in Fig. 1.Other very interesting correlations were found as the EVM values and that were obtained by the use of the Schmidt impact hammer for the superficial hardness determination."

Jan 1, 2015

By H. A. Hamza, J. Visman

"This is a report on the combined application of ""long-chain"" flocculants and classifier cyclones in the field of slimes treatment, with emphasis on the simultaneous thickening and clarifying of industrial effluents, at low cost. The principle of the process described below involves: (1) the formation of small floes of relatively great strength, by sequential dispersion and conditioning, with average floe size of about 1501 microns; (2) the floes being of sufficient strength to withstand the shearing forces operating within a cyclone and consequently behaving as solid particles with an equivalent diameter (Stokes) that exceeds the size cutpoint of the classifier cyclone; (3) the removal of flocculated solids by means of a classifier cyclone the size cutpoint of which permits effective separation of these solids from the water. Results of test work to date indicate that a broader use of cyclones in industry is possible with the above types of flocculants because the submicron particles and colloidal material are readily collected and clear water is produced, with the attendant advantages of compact construction and low cost that are characteristic of centrifugal separation. The process generally permits classifier cyclones of medium throughput capacity (e.g. 12-in. diam.) to be used for clarifying effluents that contain minus 10-micron particles."

Jan 1, 1973

By H. C. Gunnings, C. O. Swanson

"The Sullivan mine; at Kimberley in southeastern British Columbia; is the largest silver-lead-zinc mine in the Empire and one of the largest in the world.The original discovery was made in 1892 by four prospectors. Until 1899, when the branch line of the Canadian Pacific railway from Cranbrook to Kimberley was completed, little work was done on the property. In 1900, systematic development was started, and during the next 3 years 5,000 tons of ore was shipped to the smelters at Nelson and Trail. By 1903, some 300,000 tons of ore was developed, and a smelter was started at Marysville, about 5 miles from the mine. However, this smelter closed down in 1907 because of metallurgical difficulties after treating 75,000 tons, and the property came under the control of the American Smelting and Refining Company. An option on the property was taken in 1909 by the Consolidated Mining and Smelting Company of Canada, who exercised their option in the following year. During the next 5 years by selective mining and sorting 188,000 tons of high-grade ore was produced and shipped to Trail. This tonnage came from the upper levels, about 4,600 to 4,800 feet in elevation. At the same time, deep drilling down to the 3,900-foot level showed the presence of an immense body of complex ore. In 1915, the main adit-the 3,900-foot level-was started, and by 1919 this had been driven a distance of 2 miles to develop the ore above this level. Meanwhile, progress was being made in overcoming the milling problems. An interesting account of this work was written by the staff ( 4). In 1923, the first unit of the present concentrator was erected, with a capacity of 2,500 tons a day, and thereafter the rate of production increased rapidly. In 1934 it was around 8,000 tons a day, and to date a total of about 30,000,000 tons of ore has been sent to the mill. In recent years, a considerable part of the production has come from levels between the 3,900-and 3,350-foot, which were opened by an internal incline shaft started in, 1930. In 1942, tin was added to the products separated at the concentrator."

Jan 1, 1954

By Klaus Tietz, Hamish Adam, John Selby, Ian Glazier, Brian Sinfield

"Room-temperature tunable diode laser (TDL) analyzers are gaining in acceptance for highly critical safety monitoring applications in a variety of industries. This paper describes the testing, evaluation and deployment of a laser-based hydrogen cyanide monitoring system at the Campbell Complex of Goldcorp’s Red Lake Gold Mines in Balmertown, Ontario, Canada.A trial, single channel installation was followed by a staged multi-channel installation. Unexpected technical issues with the multi-channel installation were addressed and resolved.INTRODUCTIONLaser-based gas detection has several advantages over existing gas detection techniques (Ballangrud, 1993; Silver, 1992; Bomse, 1995; Table 1). For practical purposes, lasers generate light at a single wavelength. Room temperature tunable diode lasers (TDL) emit light in the near infrared (NIR) part of the electro-magnetic spectrum. Many gases of interest, including HCN, NH3 and others, absorb energy in the near infrared (NIR). Each gas has a unique absorption signature, or spectrum, made up of a large number of individual “absorption lines”. A TDL can be tuned to select a single absorption line of a target gas, which does not overlap with absorption lines from any other gases. Therefore, laser gas sensing is selective and does not suffer from interference from other gases. The single-wavelength nature of laser light also means that laser gas analysers have a linear response over a wide dynamic range.Tunable Diode Lasers (TDL) generate only a few mW of power. However, all this power is concentrated at one wavelength, the wavelength where gas absorption occurs, resulting in high signal-to-noise ratios and short response times, typically of about 1 or 2 seconds (Ballangrud, 1993). This also means that long path lengths can be used, enabling accurate measurements of very low concentrations, even with weakly absorbing gases. Tunable Diode Lasers provide all the advantages of other semiconductor devices: they are small, solid-state devices, operate at room temperature, and have long-term reliability (over 15 years). Currently, they can be obtained for any wavelength throughout the NIR (700nm to 2000nm). Because many gases absorb in the NIR, the technique is widely applicable."

Jan 1, 2011

By Earl Sweet

This overview of economic and financial market prospects examines the current and future state of the global and Canadian economies with a focus on commodities. Housing prices and global conflicts all have effects on the overall economy and metal prices and mining developments in particular. This presentation outlines where we are today and where the author and BMO see the economy moving over the next few years.

Jan 1, 2016

By Qin-yong Ma, Jing-shuang Zhang, Bo Han, Pu Yuan

In order to improve the utilization rate of blasthole and blasting effect in vertical shafts, 5 kinds of millisecond blasting model tests with three circle vertical blastholes have been conducted in various delay times with concrete as model material. The blasting effects of millisecond blasting model tests are investigated from cutting volume, cutting depth, and blasting fragmentation, then a reasonable delay time is obtained. In the middle of concrete model, there are 4 blastholes uniformly distributed in the first circle, 6 blastholes uniformly distributed in the second circle, and 10 blastholes uniformly distributed in the third circle. Each blasthole is charged with one millisecond delay electric detonator, and the rest is blocked with stemming. The depth of blastholes in the first and second circle is 180mm, which is 20mm deeper than those in the third circle. After initiation, the blasting cavity is cleaned up, then the cutting volume and cutting depth are measured. Meanwhile, the blasting fragments are gathered and have analysed by function Rosin-Rammler. The test results show that when the inner two circle blastholes initiated simultaneously and the third circle blastholes initiated with millisecond delay, the reasonable delay time is 50 ms. At this time, the cutting volume and cutting depth of blasting model are 3920 cm3 and 68 mm respectively. The fragmentation indexes of blasting fragments, X50 and X80, are 53.2 mm and 74.6 mm respectively. While when all three circle blastholes initiated with millisecond delay, the reasonable delay time is also 50 ms. At this time, the cutting volume and cutting depth of blasting model are 10705 cm3 and 118 mm respectively. The fragmentation indexes of blasting fragments, X50 and X80, are 51.0 mm and 81.7 mm respectively. The researches indicate that for millisecond blasting with multiturn blastholes, the reasonable blasting scheme is multiturn blastholes initiated in millisecond delay and the reasonable delay time is 50 ms.

Jan 1, 2015

By A. L. McAllister

"MASSIVE sulphide deposits are found in two areas of New Brunswick, the St. Stephen area and the Bathurst-Newcastle area. In both, the geology in the immediate vicinity of the sulphide bodies is largely inferred from drilling results as outcrop is not plentiful and is, in fact, almost lacking in most places. With few exceptions these deposits have not been explored by underground methods. Consequently much of the. detail on the geology will only become known over a period of years as economic conditions make mining feasible.Much of the information contained in this paper has been supplied directly by company geologists. As a result of the number of contributors, some confusion of nomenclature bas to be anticipated. Cross-sections and plans of the individual deposits are, in most cases, as supplied by the companies concerned. Most of the interpretations are the responsibility of the author."

Jan 1, 1960