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By M. Timmins

Campbell Mine operates a 100 tpd gold autoclave that treats sulphide concentrates at 305 psi and 200 °C. Autoclave feed consists of fresh pretreated concentrate, an acidic oxide slurry recycle as well as other high arsenic sources. The brickwork that is used to construct the five compartments of the vessel must be inspected and repaired periodically. Shutdowns are scheduled to inspect this brickwork and at times replace entire sections of the brick walls or lining. It also provides an opportunity to repair or replace other internal features such as agitator blades or oxygen spargers. Mechanics and contractors are scheduled around the clock to perform the maintenance requirements. There are many safety considerations and precautions that must be taken in order to protect the well-being of the workers and minimize damage to sensitive pieces of equipment. Heat, arsenic and lead contamination and confined space issues are just a few of the hazards involved. The following paper will describe how these safety concerns are addressed and will serve as a guide for future autoclave shutdowns.

Jan 1, 2004

By W. D. Bonisteel

In 1976, Rio Algom Limited began the expansion of uranium production facilities at Elliot Lake. Quirke Mine was the only property in operation at the time, and plans were made to expand its milling capacity from 4,500 to 7,000 tons of ore per day. Following this expansion, other properties in the area will be reactivated to fulfill long-term contracts for uranium. As part of the expansion program, it was decided that in view of the escalating cost and impending shortage of energy, heat reclaim and conservation would be employed wherever practicable. In general terms, heat reclaim applications fall into three main classifications: ventilation, utility and process. Two of the ventilation applications and one process application will be described in some detail. Several other systems will be presented briefly as a matter of general interest. Some future possibilities will also be mentioned, together with their potential for economical heat recovery.

Jan 1, 1979

By Jesus Garcia Iglesias, Jorge Loredo

"Abstract -The Asturian fluorspar district consists of vein and stratiform deposits where mineralization is controlled by a combination of lithological and tectonic factors.It is postulated that these fluorspar deposits have been formed under disequilibrium conditions created during circulation of ascending hydrothermal solutions along faults and other high permeability conduits. Mixing of solutions is inferred from fluid inclusion studies. Cavity filling and replacement processes are very important in localizing the ore deposits and in determining their morphology.Permian volcanic rocks in the area yield a regional positive geochemical anomaly in fluorine implying that Permian vulcanism may be a possible primary source of fluorine.On a regional scale a relationship can be established between some of the ore deposits and important tectonic lineaments. The stratiform deposits preferentially occur within a calcareous-detrital facies located at the margins of basins. These basin margins are related to important synsedimentary faults.Fluorite is the only economic mineral in these deposits. Quartz, carbonates, barite and pyrite are common minerals accompanying fluorite. Other minerals that may occasionally be present as minor components are: marcasite, chalcopyrite, fahlore, sphalerite, galena and related supergene minerals."

Jan 1, 1994

By D. Ofstie, B. Kargutkar

BIM, or Building Information Modeling, is transforming the way metallurgical facilities are built, operated and maintained. BIM provides a digital representation of the facility, complete with all physical and functional characteristics - enabling collaborative planning, concurrent design, construction simulation, sustainable operations and predictive maintenance through a connected information model. Building on experience gained in other industries, Hatch is aggressively applying the BIM process to the mining & minerals processing industry to address inefficiencies inherent in traditional document-based information management. Intelligent 3D models support real-time quantity forecasting and cost trending by commodity type and construction work package. By linking procurement and schedule data, material availability and constructability reviews are visualized to verify construction critical path, ensure work front safety and minimize craft downtime. The BIM digital information model connects engineering, construction, commissioning and vendor data, aiding timely asset-centric handover to plant operating and maintenance systems.

Jan 1, 2015

By Joanna LaForte

"IntroductionIn respect to The Human Dimension by M. Phyllis Bray, this author's impression is that research on long distance commuting (LDC) is long overdue. This type of mining is not new to many workers, especially those from areas such as the Maritimes, who have had to look for work away from their families for at least a decade. Perhaps to the industry the over-all set-up is new, but to workers who have faced mine shut-downs in their areas finding a job was the main objective and if the security of long-term employment was evident, then the families might join them later. This was the situation with which the writer' s family was faced.LDC LifestyleBeing the wife of an underground miner, the author has personally experienced this lifestyle for almost 10 years, and has never experienced accommodation in a company town. The first five years of marriage were spent in a small rural municipality within 50 miles of the worksite, but the town had industry separate from mining and was not affected by the mine shut-down.Since her LDC lifestyle began her family has been pretty much city-based, out-of-province commuters with two children and a third to arrive some years later. She therefore lived a fairly normal married life with a husband home daily. The author has experienced life with a husband who worked away for five-day stretches and then drove long distances to be home weekends or the portion of time left over from driving and fatigue. She has done the 3D-days in/l4-days out routine, and for approximately the past four years has been existing on a two-weeks in/two-weeks out ritual .The author does not agree that the ""bottom line is that mining families go where the jobs are"" . The miners go where the jobs are and the families fend for themselves with the assistance of the pay cheque making it home each pay period.Perhaps because there are many personal frustrations with this type of lifestyle, perceptions may be inaccurate. Having only dealt with underground operations, there may be gross differences between the pressures and demands of other forms of mining."

Jan 1, 1991

By E. Ghali, W. Zhang, C. Su, N. Sorour, G. Houlachi

"Zinc electrowinning process is sensitive to the presence of metallic impurities such as lead ions that could substantially and negatively affect the power consumption and surface morphology. Effect of various concentrations of manganese ions and traces of lead ions up to 2.5 mg L-1 added to the electrolyte during electrowinning have been investigated by electrochemical polarization techniques such as galvanostatic, cyclic voltammetry and potentiodynamic. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were applied to examine the surface morphology and crystallographic orientation, respectively. Microwave plasma-atomic emission spectrometry has been used to determine the lead content in the deposit and in the electrolyte after electrodeposition. It was found that lead ions added to the zinc electrolyte led to the increase of cathodic overpotential and current efficiencies of zinc deposit. However, addition of Mn2+ into the zinc electrolyte resulted in the decrease of cathodic potential and current efficiency of zinc deposit. It can be stated as example that galvanostatic polarisation at 40?C and 52.5 mA cm-2 in presence of lead up to 0.1-0.2 mg L-1 in the electrolyte and 8-12 g L-1 Mn could be better considered as practical working parameters for electrowinning process.INTRODUCTIONApproximately 85% of the global production of zinc metal is produced by electrolytic process (Sinclair, 2005). The main goal of the zinc plant is to obtain pure zinc deposits with high current efficiencies. Smooth and pure deposits with high current efficiency (CE) are always obtained from pure electrolytes (Alfantazi & Dreisinger, 2001). The presence of metallic impurities in the zinc sulphate electrolyte is a major problem for the zinc electrowinning industry, since decreases in current efficiency, changes in deposit morphology and cathodic polarization are observed for electrolytes containing small concentrations of impurities (Ault & Frazer, 1988; Muresan, Maurin, Oniciu & Gaga, 1996). Low level concentrations as parts per million of these impurities are reported to influence negatively the zinc electrodeposition (Beshore, Flori, Schade & O'Keefe, 1987)."

Jan 1, 2016

By Claude Hubert, Robert Sansfaçon

"The Malartic gold camp includes the Malartic Gold Fields, Barnat, East-Malartic, Canadian Malartic and Sladen mines. From 1935 to 1984, these mines have yielded 212 403 kg of gold. They occur within a 900 m wide belt of highly sheared, dislocated and faulted volcanic and sedimentary rocks (Piché and part of the Pontiac groups) herein named the Malartic Tectonic Znne (MTZ). The zone trends WNW-ESE and separates two lithotectonic sedimentary domains, the Cadillac to the north and the Pontiac to the south. The sedimentary domains are characterized by their coherent fold generations consisting of open to tight reclined and recumbent F1 folds that have been refolded into series of asymmetric upright F2 folds. A flat-lying schistosity (S1 ) and a vertical pressure-solution cleavage (S2) are ubiquitous throughout. Discrete sets of brittle and brittleductile faults are synchronous and parallel to each of these two fabrics.The MTZ trends N320° in the northwestern sector of the town of Malartie, changing to N2800 at its easternmost extremity. The Malartie and Sladen faults constitute its northern and southern boundaries respectively. These two faults also bound another set of faults oriented N305°. Throughout the MTZ, the faults at N280° and N320° and those at N305° outline a series of anastomosed motifs that constitute the principal structural feature of the Malartic district. Locally, a fourth set of minor faults at N065° combines with the other three prominent sets. All these faults have disrupted the gold-bearing volcanic, sedimentary and intrusive rocks encountered throughout the MTZ.The MTZ comprises numerous lozenge-shaped blocks of komatiites and basalts or greywackes and black shales which are cut by disjointed dikes, sills and small intrusions of felsic and mafic rocks. The latter includes gabbro, diorite, lamprophyre, monzonite and pegmatite. They frequently fill conjugate sets of fractures. In some areas, they are clustered into coalescent intrusions. The present morphology of these intrusive bodies( cube, chocolate-tablet boudin, parallel epiped and cigar) is not representative of their primary forms but the result of late shearing and faulting indicative of a major tectonic event subsequent to their emplacement. The intrusions were injected during a brittle stage of deformation related to the F1 folding but prior to the development of the F2 folds and subsequent tearing and shearing by late brittle and brittle-ductile faults . The ultramafic and mafic rocks are intensely altered to serpentine, tremolite, actinolite, carbonate, biotite, hematite and pyrite according to the nature of their proto/it h. In the vicinity of the MTZ, all lithologies exhibit mineral assemblages indicative of the upper greenschist or lower amphibolite facies of metamorphism.The structural evolution of the MTZ involved superimposed folding, shearing, transposition, mylonitization, brittle and brittle-ductile faulting. Each lenticular motif results from the combined effect of conjugate sets of shear zones that outline lozenge-shaped blocks where strain markers indicate different strain states from cores to margins. Bedding in ultramafic flows and/or sedimentary rocks is either NW-SE or NE-SW within the blocks but, in the vicinity of the Malartie and S laden faults, it has been rotated to become subparallel to the faults.Ore shoots are most commonly associated with altered and deformed bodies of diorite and monzonite, or some mafic and ultramafic schists and, at the Canadian Malartic, Sladen and East Malartic mines, with metasedimentary rocks. The shoots occur in close proximity to the various faults of the MTZ but the gold itself is intimately associated with pyrite, biotite and carbonate in halos bordering fractures crisscrossing the different host rocks. The density of fractures and the width of their altered zones have been significant parameters in the production of economic ore shoots. Grains of gold are visible in some veins of quartz a"

Jan 1, 1990

By J. L. Jobe

In planning the operation of a new mine or new sections of an operating mine, due provision must be made for the ultimate recovery of as much of the seam as is consistent with safety and economic principles. Each mining district and, indeed, each seam, especially in mining under submarine conditions, has individual problems which render hard and fast rules under all conditions of mining impossible. However, certain basic principles can be applied to all seams under specific conditions. In all mines, the two basic methods of mining, 'longwall' and ?room-and-pillar? or their variations, can be adopted, but certain fundamental factors must be analyzed before either method is finally applied to the extraction of the seam. The factors which enter into the successful, safe, and economic extraction of all seams are, briefly stated, as follows: (1) Character and thickness of the seam. (2) Character of the floor and immediate roof of the seam. (3) Composition, strength, and thickness of the overlying beds to the surface. (4) The depth of cover to the surface or sea bottom. (5) Conditions under which the seam is mined (land or submarine area). (6) Pitch of the seam. (7) Economic value of the seam. (8) Mining laws.

Jan 1, 1947

By Martin G. Wafforn, George J. Greer

"In early 2014, Pan American Silver Corp. commenced a project to construct a second shaft at its La Colorada underground mine located in Zacatecas State in Mexico. This was the first new shaft development project undertaken by Pan American Silver in the history of the company. The existing mine workings permitted the use of a raise bore for the excavation of the shaft opening, utilizing directional drilling in poor ground conditions to advance the pilot hole. This was an interesting project with many challenges and successes, and numerous lessons learned. The project was successfully completed in 2016, with the shaft operating at full mine production capacity within weeks. INTRODUCTION The La Colorada Mine has a long history dating from at least the 1920’s. The mine is located in the northern portion of Zacatecas State in Mexico in the Chalchihuites area, an approximate two hour drive south from the city of Durango. Pan American Silver acquired the La Colorada mining concessions in 1998, with mine production at that time consisting of only a few hundred tonnes per day. Over the course of the following 15 years, with the addition of an oxide processing plant and some expansions to the sulphide processing plant and site infrastructure, production was eventually increased to a maximum of 1,250 tonnes per day, all of it generated from conventional cut-and-fill stopes in the underground mine. An existing shaft was used to hoist the ore to surface, and over the years Pan American Silver had deepened the shaft and had changed out some of the hoisting plant. However, there were historic workings in close proximity to the shaft that made it unsuitable for personnel transport, and shaft maintenance was becoming difficult. The shaft was increasingly considered as a risk to the long term production continuity, and also to further deepening of the mine. In addition, expanding the capacity of this old shaft was not possible. Drilling of the La Colorada mineralization at depth commenced in 2010, with very good exploration success. As a result, by the end of 2013, the mine reserves had grown to a total of 6.5 million tonnes of high grade ore (388 g/t Ag, 0.36 g/t Au, 2.4 % Zn, and 1.3% Pb). Furthermore there were more (and higher grade) sulphide reserves than oxide reserves at depth. Following the completion of an internal study in 2013 with assistance from one of the international shaft contractors, a decision was made to increase the production from the mine with the construction of a new shaft and a new sulphide processing plant, a project with a calculated payback of 2.2 years."

Jan 1, 2019

By J. F. Wright

Gold-bearing quartz veins and replacement chalcopyrite deposits are the two important types of metallic mineral deposits of the east central Manitoba mining district. The gold-bearing veins occur along Manigotagan valley, northwest for 25 miles from Beresford lake, and the copper deposits along Oiseau valley, between Oiseau lake and the east end of Lac du Bonnet. Lithium-bearing minerals of possible commercial value have recently been discovered in pegmatite along Winnipeg river about 10 miles east of Point du Bois. There are also prospect pits with showings of galena, sphalerite, cobaltite, pentlandite, nickeliferous pyrrhotite, arsenopyrite, pyrite, molybdenite, cassiterite, and other minerals, but the various occurrences of these minerals, as exposed, are small. The bedrock and mineral deposits of this mining district are Precambrian and resemble in many respects the formations and mip.eral occurrences of western and northern Ontario. Although prospectors visited eastern Manitoba at intervals during the last fifty years, effective prospecting did not begin until 1913 or 1914, and not until 1923 were skilfully directed, systematic explorations undertaken. It is true, that between 1913 and 1923 considerable sums were expended in a number of attempts at mining and milling the gold-quartz ore, but these enterprises failed partly through poor management or attempts to develop veins that were too small or too low-grade to be worked at a profit under the existing conditions of transportation and power supply.

Jan 1, 1925

By M. H. Allan

"This paper presents the geographic and geological setting of Saskatchewan Power Corporation's Poplar River Mine in south-central Saskatchewan, about 8 miles from the U.S. border. Generally the mine, which is being expanded to four million tons per year, is in an extremely disturbed geological area with severe dewatering problems. The lignite coal, which is strip mined, is supplied directly to an electric power generating station by means of a 7-mile unit-train private railroad.A number of unique reclamation and socio-economic problems were encountered because of the proximity to the U.S. border and because of the lack of experience of the regulatory authorities in projects of this kind. These are described in some detail, as well as the performance of one of the largest draglines in Canada. IntroductionThe Saskatchewan Power Corporation is a publicly owned utility which has the franchise to supply electricity and natural gas to all customers within the boundaries of Saskatchewan.Saskatchewan is a province which can almost be divided in two: the populated southern portion, principally devoted to farming, and the northern portion which is mostly on the Precambrian Shield and consists of lakes, rocks and muskeg. This portion is largely uninhabited except for a number of small villages. However, in the last few years there has been considerable mineral exploration and development, notably for uranium. This has helped considerably in the diversification of the basic agricultural economy of the province.Saskatchewan consists of 251,700 square miles, 761 miles north to south and an average of 335 miles east to west. It has a population of approximately 960,000, giving a population density of four persons per square mile. The Saskatchewan Power Corporation supplies 357,249 electrical arid 221,378 natural gas customers."

Jan 1, 1982

By C Kumar

Scaffolds are temporary structures built to facilitate construction activities on site. A considerable amount of resources are allocated to scaffolding on industrial projects. Variability in geometrical features and space accessibility of structures on industrial projects, in addition to involvement of different trades that share the use of scaffolds, requires an extensive understanding of scaffolding requirements. Hence, it?s important to plan and estimate scaffolding man-hour requirements for the different construction areas on an industrial site. Contributing factors involved in such estimates include the list of trades that work in a construction area, trade working hours, volume of work, geometry of equipment erected, etc. A simulation template for predicting scaffold erection man-hour values for individual construction areas in an industrial project was developed in Simphony 4.0. The template is based on mapping the geometry of equipment and other factors to man-hours of scaffold work. The template facilitates the use of distributions as inputs and produces a range estimate of scaffold man-hours. The mapping is based on a linear regression model derived from existing project data from PCL Industrial Management Inc. The template is being further developed to incorporate the ability to predict scaffold erection schedule and material requirements based on construction work areas or equipment lists of an industrial construction project.

Aug 1, 2013

By Ken Hester, Bruce Arthur

"Introduction""Pebble milling"" is a term used to describe secondary grinding done with rock pebbles rather than steel balls or other steel or metal shapes. This paper discusses pebble milling with particular attention being paid to uranium grinding circuits.Pebble milling is typically employed:a. where the cost of steel balls becomes exorbitant, as may be the case in an isolated area.b. where the extra steel added from steel ball consumption may be detrimental to further processing.c. where the over-all economics favour the use of pebbles rather than ball.Pebble milling differs from autogenous and semi-autogenous grinding in that a sized product has been removed from some part of the primary comminution circuit, and it is this sized product which is added as grinding media to the pebble milling stage. The pebbles do not necessarily have to be produced from the ore- ""foreign"" pebbles can be used. Also, pebble milling generally refers to grinding from a fine size, below about 6 mesh (3360 micron), with relatively small media, that is, secondary grinding. In South Africa, however, primary pebble mills are sometimes used to grind crusher house product, and thus function in place of rod mills. Pebbles for this service are large and heavy as they must weigh as much as balls used in similar service.The first large applications of pebble milling were in South Africa(n. ""Tube milling"" with pebbles started in 1904. The tube mill was simply a tumbling mill with a length to diameter ratio over two. A ""typical"" early tube mill was 5.5 ft. (1.7 m) in diameter and 16 ft. (4.9 m) in length. Diameters increased steadily. King(n mentions 8-ft. (2.4 m) units in his 1949 book. By 1961, the largest units discussed by Jackson('' were 12ft. (3. 7 m) in diameter."

Jan 1, 1989

By R. F. Baxter, C. M. Read, R. I. McCulloch

"Globalization of the aluminium industry continues to increase the pace of change and the intensity of competition, while simultaneously, society demands better products, cleaner technologies and sustainable industries. Bechtel, a global engineering, construction and project management company, is not immune to either the opportunities or the challenges created by globalization. However, and not withstanding the challenges, for aluminium industry ""players"" with a true global perspective, globalization presents very real opportunities that may be leveraged to deliver value creating goods and services. The following paper will focus on the exploitation of one of the opportunities created by globalization in the Knowledge Management domain - the application of high level tools and methodologies to improve global delivery of greenfield and brownfield aluminium smelter construction projects. Specific examples will be presented of value driven solutions that were delivered at the early stages of project engineering."

Jan 1, 2006

By G M. Thorpe

This paper discusses mine research at Inco, giving specific examples of research projects which illustrate the approach to mining problems. The first example covers the development of a new mining method, "undercut and fill," which was originated for mining badly broken-up pillars, but which is now rapidly replacing the square set method of pillar recovery. In the new method, ore is extracted in a series of successive horizontal cuts, progressing downward, a cut being completely mined and filled before the cut below is started. In the second example, improvements to the "cut and fill" method of mining are discussed. These improvements are the result of improved techniques and improved equipment, etc., with, in many cases, the former being made possible by the latter. The advances made have permitted the use of the "cut and fill" method at much greater depths than before. The third example is presented to illustrate research undertaken to obtain the earliest maximum advantage of the introduction of a new piece of equipment or material. For this purpose, the development of the "Under-ground use of AN /FO Blasting Agent " has been selected. Work on this project started in May, 1960, at a time when there was very little in-formation regarding the potentialities of AN /FO for underground blasting, either primary or secondary. By the end of 1961, AN /FO made up 64 per cent of the explosives used under-ground at Inco mines.

Jan 1, 1963

By Cummings. J. B., R. Haworth

"THE OPERATION of the Potash Company of America, Ltd., at its plant near Saskatoon, Saskatchewan, is the result of many years of exploratory and development work, culminating in the construction of a shaft, milling, concentrating and other facilities necessary to the production of potash in a marketable form.The possibility that potash existed in •commercial quantities in Saskatchewan was first indicated in 1943, although it was not until mid-1946, when Bata Petroleums penetrated a potash bed at its Verbata No. 2 well near Unity that substantial in-ter.est was developed in the possible exploitation of this important mineral product.The Potash Company of America, which is the largest producer of pot-ash in the Carlsbad, New Mexico area, a district that has been sup-plying about 90 per cent of the North American potash demand, be-came interested in the Saskatchewan deposits •at an early stage. Its engineers made an intensive study of the western Saskatchewan area in 1947 and continued their review of operating problems throughout the next three years.""Potash"" is the commonly used general term applied to the minerals of potassium, of which there are several. The most common mineral forms in which it is produced are potassium chloride and potassium sulphate. The potash content of potassium compounds is ordinarily ex-pressed in terms of potassium oxide (K20) equivalent."

Jan 1, 1960

By V. Vakiloroaya

The paper aims at developing a hybrid solar-assisted air conditioner system for performance enhancement and energy efficiency improvement. To increase sub-cooling of the refrigerant at partial loads, we propose a new discharge bypass line together with an inline solenoid valve, installed after the compressor to regulate the mass flow rate of the refrigerant vapour passing through a hot water storage tank. For control design, a lumped parameter model is first developed to describe the dynamics of the system in an explicit form of input-output relationship. The system has been fully-instrumented to examine its performance under different operation conditions. The system model is then validated by extensive experimental tests. The predictions from the models exhibit a good coincidence with experimental results, judging by an RMS error less than 15%. Based on the obtained dynamic model, a linear quadratic regulator (LQR) is applied to optimize a cost function of the output errors and control efforts. The key challenge is to regulate the refrigerant temperature entering the condenser by controlling the valve opening. The design approach is then tested in a transient simulation tool to predict the system performance in transient conditions. The experimental results obtained from implementation with PLC demonstrate that the proposed system delivers higher system efficiency owing to the higher refrigeration effect in the direct expansion evaporator. Thus, the novel development is promising for improvement of energy efficiency, enhancement of the system performance while fulfilling the cooling demand. Consequently, between 25 and 43% of monthly electricity can be saved on average.

Aug 1, 2013

By G. Stafford Whitby

N ATURAL gas is found in several provinces of Canada, particularly Ontario, New Brunswick, and Alberta. The largest producer is Alberta, and there the most important field is the Turner Valley, where some low-gravity crude oil and naphtha are associated with the gas. Last year there was produced from the Turner Valley field an average of 3,462 barrels, or about 450 tons, of oil a day. The gas flow from the wells in this field bears such a high ratio to the oil which comes from them that, despite the enforcement of a measure of conservation, it amounted to the vast quantity of 6,000 tons a day, or more than 2,000,000 tons a year. Prior to the application of any conservation measures, the gas flow was at one time of the order of 12,000 tons a day. The heat content of one ton of the gas is almost equal to that of two tons of coal. A certain amount, say, 10 per cent," of the gas is used in Calgary and surrounding towns and in re-pressuring the Bow Island gas field, but the greater part of it goes to waste. What are the possibilities of making use of this waste gas, in whole or part? The possibilities of using it profitably as fuel for domestic and industrial purposes have undoubtedly been carefully considered by the Company which now distributes a part of the gas to cities and towns in Alberta. But the relative sparness of the population and the cost of pipe lines makes such possibilities strictly limited. There are, however, distinct possibilities of making use of at !east a part of the gas for the production of a variety of chemical products and of liquid motor fuel. The present paper is devoted to outlining some of these possibilities. About three-quarters (by weight) of the Turner Valley waste gas consists of methane, the lightest and, chemically speaking, the simplest of hydrocarbon gases. The remaining quarter consists of heavier hydrocarbon gases-ethane, propane, and butane. Formerly, naphtha was separated from the well gas by a simple process of self-refrigeration. The gas coming from the wells at a pressure of, say, 1,200 to 1,800 lb., was passed through simple cylindrical vessels fitted with baffles and known as 'separators'. The pressure was allowed to drop to, say, 300 lb. in the separators, and the cooling effect secured by this expansion brought about separation of the naphtha. The naphtha thus obtained was 'wild', that is, it had a high vapour pressure owing to the presence in it of dissolved and liquefied gas. In order to reduce the vapour pressure to a level at which the naphtha could be shipped, this gas was removed either by distilling it out through a 'stabilizing' column or, according to the practice at many wells, merely by allowing the naphtha to 'weather' in open tanks (heated by coils if necessary) until the gas had been driven off in to the air.

Jan 1, 1936

By S. Koski, J. Vanderbeek, J. Enriquez

"The Cerro Verde copper-molybdenum porphyry mine, majority owned and operated by Freeport- McMoRan Copper & Gold, is located 30 km southwest of Arequipa Peru. The concentrator, which produces copper and molybdenum concentrates, started operating in late 2006 with a 108,000 tpd design capacity, processing primary sulfide ore (mainly chalcopyrite and molybdenite). Plant capacity was recently increased to 120,000 tpd. The comminution circuit consists of one 60” x 113"" primary crusher, four MP-1000 secondary crushers in closed circuit with dry screens, four 2.4m x 1.6m High Pressure Grinding Rolls (HPGRs) in closed circuit with wet screens, and four 7.3m x 11m gearless ball mills in closed circuit with cyclones. The HPGR circuit is fed by the Secondary Crushing circuit product at a T80 of 35 millimeters, and the HPGR circuit product feeds the Ball Mill circuit at a T80 of 3000 microns.This paper describes operating experiences with HPGRs during these first four years highlighting improvements in operating practices and presentation of data regarding operational efficiencies, also discussed are the primary benefits provided by HPGRs such as production of micro fractured particles, reduced ore Bond Work Index, and reduced power consumption. Cerro Verde represents the first installation of HPGRs in both the copper industry and large scale hard rock mining."

Jan 1, 2012

By C. G. Williams

IN preparing this paper on Canadian mine taxation, there has been no attempt to detail the requirements of the various taxing bodies; but rather to consider the matter from the standpoint of its underlying principles and give a general idea of the methods adopted. I have added an Appendix setting forth the principal features of the various Acts, which should be used for general reference only, since new rulings alter minor details from time to time. In current legislation, many important points are left to the discretion of the Ministers and their deputies. We are, indeed, fortunate in having in Canada an able and conscientious body of permanent officials, who bring a sense of justice and courtesy to their work which is most commendable, and which has done much to simplify the working out of general problems. The production of metals may rightly be deemed a form of manufacture, but differs from the average manufacturing business in three important respects: (1) In its early stages, it is wholly speculative, since it is impossible to make any definite appraisal of value or possibilities. (2) The principal asset of any mine, i.e., the ore in the ground, is a wasting asset, and is irreplaceable. (3) Any additional burden by way of taxation cannot be passed on to the public but must be borne entirely by the producer. Having regard to the first of these differences, it is apparent that, since the risk of loss is great, the reward in case of success must be correspondingly great. This fact seems to be constantly overlooked by those who regard the all too few outstanding successes in Canadian mining history as fit prey for predatory legislation. As an illustration of the speculative nature of early mining development, let us consider the Province of Ontario-and I take this illustration simply because I am more familiar with conditions there, and not because I believe it differs greatly from any other province. From 1907 to 1933, 165,243 claims were staked and recorded, from which 43 mines were developed which paid one or more dividends. There was, of course, some duplication through re-staking; also, on some claims very little work was done, and most mines have more than one claim. But, since staking and recording cost real money and effort, each of these claims must have been considered to have had merit.

Jan 1, 1935