Search Documents

By Hevina S. Dashwood

This paper proposes to build on my previous research (Dashwood 2012), which analyzed how and why the norm of sustainable development became institutionalized in the global collaborative corporate social responsibility (CSR) initiatives of major mining companies. Since the late 1990s, the majority of major global mining companies have employed the norm of sustainable development to frame their individual CSR policies and to inform industry collaboration at the global level through the International Council on Mining and Metals (ICMM). This paper proposal seeks to address lingering questions from that research, by developing an explanation for how the normative frame of sustainable development has translated into specific CSR standards adopted by the mining industry. Preliminary findings suggest that, although the global mining industry has reached broad consensus on the meaning of sustainable development in the context of mining, there remains considerable variation between mining companies in terms of which specific global standards they adopt. As members of the ICMM, major mining companies are required to report according to the Global Reporting Initiative (GRI) indicators relevant to mining, and there has been wide-spread up-take of the ISO 14,001 environmental management system standard. However, other global standards, such as the International Finance Corporation (IFC) Performance Standards and the Extractive Industry Transparency Initiative, have not been uniformly adopted by the mining industry. What explains this variation? The paper employs a three-level institutional framework (rational choice institutionalism, historical institutionalism and the ?new? institutionalism in organization theory) to explain the influences on the adoption of CSR standards in the global mining sector. Existing research confirms that institutional context is an important factor in explaining CSR adoption in the mining sector (Dashwood 2012). Are similar forces at work in explaining the variation in adoption of specific CSR standards? A three-level institutional analysis lends itself to uncovering influences both external to mining companies (such as pressures from stakeholders), as well as internal company dynamics (such as managerial discretion). Furthermore, the framework can incorporate dynamics operating at the global level (such as isomorphism), the national level (such as the regulatory regime) and the local level (such as community needs and environmental challenges). The theoretical significance of this framework is that the influences on CSR adoption are more complex than can be explained in a single approach (such as narrow rational choice/cost benefit explanations). On a practical level, insights into how global standards get interpreted and acted upon by individual companies could lead to the development of more appropriate and effective global standards.

Aug 1, 2013

By C. Cornejo, C. Schuffeneger, J. Rosas

"At the end of 2010 the AMSA Esperanza Concentrator started commissioning. Located in the Atacama Desert this project is the first of several large size concentrators developed recently to operate in Northern Chile. In addition to the new operations to be implemented in the short term, many existing installations are planning expansions. The use of large size equipment is one of the common characteristics of the new concentrators, but also new technologies are being considered and innovation is present in most cases. Sea water or desalinated water will be required to process large tonnages of sulphide copper ores as well as gold bearing ores, since process water supply from the Andes will no longer be available. The high cost of sea water or desalinated water supply and the high cost of energy are not a limitation as the current metal market scenario allows obtaining an attractive NPV even from installations designed to process relatively low grade ores. A review of the current concentrators being developed in Chile is presented, including a description of the main design issues related to technology and innovation. An analysis of the Chilean mining industry is also presented, detailing mine and plant capacities as well as expected final products.INTRODUCTION The mining sector in Chile has become a reference when analysing the large concentrator plants projected or currently in operation all over the world. At present and as a consequence of the high price of metal commodities, most South American countries have an active mining sector. Chile is known as a major producer of metals. First records of copper production exported to Spain are dated to the early XVII century. Since then Chile has produced over 13% of the total copper ever produced in the world. After 1990 Chilean mining and the associated cluster of activities has substantially grown to levels never reached before, especially in the production of copper, gold and other non-metallic minerals. This dramatic increase is the result of an economic policy based on delivering comparative advantages and incentives for the admission of foreign capital to offset the weak domestic investment in previous decades. Massive mining of its huge mineral resources has allowed Chile to be a world leader in the production of copper and other base metals and mineral products."

Jan 1, 2012

By J. E. Amadi-Echendu, F. Stober, J. Ndlovu, L. R. Nelson

The Polokwane Smelter Complex (PSC) relies on a single 68MW high-intensity six-in-line furnace to smelt a planned 650 000 t/a dry concentrate to produce a platinum group metals (PGM)-bearing matte. As typical of a greenfields venture, considerable attention was paid to the project development and implementation stages of design, engineering, construction and commissioning. Somewhat unusual though, was the role of a dedicated multi-disciplinary "Operational Readiness" and support team, comprising the owners team and specialists from the furnace designer, HATCH, to effect a safe and rapid ramp-up to the design smelter capacity of 68MW. The challenges encountered in developing an effective partnership will be discussed. The modus operandi and roles of the "Operational Readiness" team during the design, procurement, construction and commissioning stages as well as that of the operational support team within the overall ramp-up objective will be presented. The "Operational Readiness" team was responsible for:

Jan 1, 2005

By W. G. Hubler

It has been within only the last two or three years that enough progress has been made in preferential flotation to warrant metallurgists in recommending the installation of commercial-sized plants for the treatment of copper-zinc-iron ores. Until the new processes had been worked out successfully, the treatment of this type of ore had proved a stumbling block in the path of metallurgical progress. Separation of lead-zinc ore is comparatively simple. A lead-zinc ore low in iron may be separated and concentrated by gravity con-centration, provided it is not necessary to grind too fine. Owing to the specific gravity of chalcopyrite and sphalerite being so nearly the same, however, their separation by gravity concentration is out of the question. Complex lead-zinc-iron ores in which the several minerals are intimately associated, requiring fine grinding to free them, have been successfully treated by flotation for the past fifteen years. Galena is easily floated, and its flotation, unlike that of chal¬copyrite, is not affected by the reagents used to inhibit the flotation of sphalerite and iron sulphides. When an attempt was made to use the methods of lead-zinc se-paration on copper-zinc ores, it was found that the depressant re-agents added to inhibit the flotation of the iron and zinc minerals would, under certain conditions, depress a large part of the copper. It was also recognized that, in the grinding of copper-zinc ore, soluble salts were generated which were detrimental to flotation unless properly controlled. The main part of this paper will be a discussion of solutions in the grinding circuit in relation to the pro¬duction of soluble salts and their effect on flotation.

Jan 1, 1931

By James R. Wickens, David La Rosa, Robert E. McIvor, Adrian Dance

"The comminution circuit at Barrick Cortez Gold Mine uses an open circuit primary jaw crusher followed by a standard SABC grinding circuit. The grinding circuit incorporates a 26’Ø x 11’ SAG mill, an Omnicone 1560 pebble crusher and a 16’Ø x 28½’ ball mill. Both mills are driven by 4500 HP motors.In 2007, several comminution circuit studies were performed to assess circuit performance and map a course for improvement. This paper discusses the results of those studies including an analysis of mine-to-mill opportunities, grinding work index efficiency, and ball mill functional performance. Subsequently, improvements to the circuit were made to enhance operating efficiency. Specifically, improvements to the pebble crusher liner configuration, advanced process control system (expert system) and ball mill classification and ball charge are discussed. In addition, other current and future improvement opportunities are discussed.INTRODUCTIONThe Barrick Cortez property is expanding to include the new Cortez Hills open pit and underground mines. Ore from these new mines will be processed in the existing Pipeline mill facility. In conjunction with ore characterization work, performance of the comminution circuit needed to be quantified. Thus, in 2007, the comminution circuit was surveyed and opportunities for improvement identified.Figure 1 below shows the Pipeline mill flowsheet. It is a standard SABC grinding circuit using an open circuit primary jaw crusher followed by a 26’Ø x 11’ (7.92m Ø x 3.35m) SAG mill, in closed circuit with a Omnicone 1,560 pebble crusher, and a 16’Ø x 28½’ (4.88m Ø x 8.69m) ball mill. Both mills are driven by 4,500 HP (3,357 kW) motors. The SAG discharge screen aperture is 5/16” (8 mm) x 1-1/16” (27 mm) slots. Ball mill circuit classification is done with Krebs D20B cyclones."

Jan 1, 2009

By C. E. Baltzer

This is the fourth in a series of coal technology reviews being prepared. in accordance with a recommendation voted by the Coal Division C.I.M. in session at the Jubilee Meeting, Vancouver, 1948, that the Department of Mines and Resources be requested to arrange for publication by the proper Government authority of a Quarterly Review of Coal Technology for distribution among those concerned in the production and use of coal in Canada. Copies of the first review, which appeared in the November, 1948, BULLETIN, pp. 612-614, of the second review in the June, 1949, BULLETIN, pp. 272-275, and of the third review in April, 1950, BUL-LETIN, pp. 1,9?3-196 (also, respectively, in Transactions, Vol. LI, 1948, pp. 262-264 Vol. LU, 1949, pp. 117-120, and Vol: LIU, 1950, pp. 133-136), were distributed by the Dominion Coal Board and are still available on request. In this review, the first in the series in the field of combustion, development and trends during the period approximately from World War II to the present time are described and therefore the presentation is general. Later reviews will particularize developments in relation to the range of coals available in Canada.-ED. INTRODUCTION THE utilization of coal in heat and power producing equipment has become of paramount importance to the coal industry in maintaining stable and profitable markets. In the past, the chief concern was with mining, transportation, and overall supply problems, but modern conditions demand interest in and knowledge of all phases of the product, from coal in situ to its ultimate disappearance in the form of products of combustion. Even the last mentoined factor has caused complications, as is shown by current widespread activity in the field of smoke abatement

Jan 1, 1951

By K. Turgeon, J. -F. Boulanger, L. Whitty-Léveille, C. Bazin

"Several companies targeting Rare Earth Elements (REE) around the world have completed a Preliminary Economic Assessment showing positive project financial results. Although REE ores may contain high REE value, financing these projects remains difficult in part due to the number of processes required to valorize the elements and the relatively low yield of these processes. Direct ore leaching without the production of a concentrate may reduce the capital and some operating expenditures through process simplification, and increase revenues because of REE recovery improvement.A silicate REE ore is used to test various hypotheses regarding whole ore processing and to develop a simplified flowsheet. An atmospheric leach (200 kg/t H2SO4) of crushed whole-ore containing 0,6% REE, followed by impurity removal and REE precipitation recovers 80% of the REEs in a solution containing REE and Th. The high value contained in most REE deposits makes whole-ore approaches worth considering for most projects, given the losses of valuable species typically associated with the production of a REE mineral concentrate from the ore. INTRODUCTIONRare Earth Elements (REE) find applications in modern and clean technologies, whether civil, industrial or military. With China producing more than 90% of the world’s REE, the embargo imposed by this country in early 2010 increased REE prices for a three year period. With prices having shrunk back many-fold from their peak value, projects put forward during the hike are struggling to secure financing. Owing in part to unconventional processes such as acid-baking and solvent extraction, REE plants are high capital cost and high operating-cost units, and present technological risks (Verbaan et al., 2014)."

Jan 1, 2016

By I. Tinto

"IntroductionEnvironmental pollution problems, caused by gases or effluents, by high noise levels or from air borne dust, are placing increasing demands of the operators, from statutory authorities, and from the general public, to adopt more stringent dust control measures. This requires that a successful plant dust control program be an integral part of any plant operation. While a successful environmental program is a key factor in maintaining productivity and good labour relations, anticipation of future environmental regulations during the plant design phase can avoid the high cost of plant upgrading, or dealing with pulmonary conditions in the work force in subsequent years.Particulate removal, conventionally called dust collection, involves the removal of coarse- and fine-particulates from the airstream. Although generally limited to that required for contro!Hng plant generated air emissions, particulate control equipment also has a wide application for air cleaning and filtration inside the plant, as well as for recovery of usable products.In the late 1950s and early 1960s the public became more concerned with the problems of air pollution. This increasing concern was stirred by an awareness of the extremes to which water pollution had progressed in many of the rivers and lakes, by increasing perception of air pollution as detected by visible smog and harsh chemical odors, by the alarming rate of increase of smog plagued cities and communities, and by specific incidents where ill health could be traced to specific episodes of air pollution. Particle size is perhaps the most important single factor affecting particulate control. Large particles (over 5 microns) constitute the major mass fraction of most sources of emission and economical control equipment dqes exist for their efficient control. However, while these larger particles frequently represent the source of soiling and unsightly smoke plumes, they are not a major health problem as they tend to settle relatively quickly, are more easily scrubbed from the atmosphere by rain, and are not able to penetrate the respiratory system. By far the most important form of particulate air pollution is the fine particulate, (below 3 microns) which is harmful to the pulmonary system. The adverse effects caused by this particulate matter on human health are for the most part related to injury to the surfaces of the respiratory system. Particulate material in the respiratory tract may produce injury itself, or it may act in conjunction with gases, altering their sites or their modes of action. A combination of particulates and gases may produce an effect that is greater than the sum of the effects caused by either individually (i.e. synergistic effect)."

Jan 1, 1989

By J. H. H. Chamberlin

"In the Introduction the author briefly discusses the company history as it relates to the development of its contracts with the Japanese steel mills. The main part of the text describes how Coleman Collieries Limited approached the problem of mining coal profitably in thick, steeply inclined seams. For many years a basic room-andpillar system was worked by conventional methods. Main roadways were driven on strike across the mineable area. These roadways acted as haulage routes for coal, materials and men. Rooms were developed to the rise of the main haulage route by pairs of men using air-operated hand picks. As these rooms advanced the miners would lay and extend a sheetiron chute down which mined coal would gravitate to a controlled loading point, where it was loaded into trains of mine cars. Connecting roadways or ""OFFS"" were driven at predetermined intervals between adjacent rooms, forming pil1ars or blocks. Extraction of the blocks followed on a line conducive to good strata control some distance behind the developing rooms. A need for higher productivity, expansion of the operations and a scarcity of qualified miners resulted in the company deciding to mechanize its underground mines. Joy 6 CM continuous miners and 10 SC shuttle cars were selected as being machines that could reasonably negotiate the problems associated with the pitching seam. The equipment, nonetheless, has definite limitations and Coleman therefore developed a modified version of the room-and-pi11ar system such that the miners and cars could work on cross pitch. In the area described, main roadways were driven to the rise on an average gradient of 12 degrees. Panels, which consisted of two parallel roads with interconnecting cross-cuts, were then developed on strike to a boundary point. Blocks formed in the development of the panels were subsequently extracted on retreat. Problems associated with each phase of the operation are thoroughly discussed, together with roadway support methods and equipment used for the conveyance of coal and materials."

Jan 1, 1972

By Don Peel

Mineral aggregate, the most widely used mineral resource globally, has attracted little academic or public interest. Of all mining developments, the aggregate resource is seldom factored into resource management decisions. This lack of recognition to the strategic aggregate resource has significant economic, environmental, and social implications. Impact to the economics, the environment, and the community coincide with the key elements of the United Nations concept of ?sustainable development?. To build on the concept, the mining sector contracted the International Institute for Environment and Development to assess how mining activity contributes to sustainability. As a result, a useful assessment process was developed by the Mining, Minerals and Sustainable Development (MMSD) Task Group entitled ?Seven Questions to Sustainability: How to Assess the Contribution of Mining and Mineral Activities.? In Alberta, recent opposition to mineral resource development by community residents offers an opportunity to employ the MMSD?s assessment procedure. The public opposition to the mining activity was addressed through a stakeholder planning process initiated by the municipal council of Sturgeon County, Alberta. As a result the Calahoo/Villeneuve Area Structure Plan (CASP) was formulated and adopted. To measure the effectiveness of the CASP planning process in terms of sustainability, this paper applies the MMSD?s Seven Question assessment to the Calahoo/Villeneuve Area Structure Plan.

May 1, 2004

By J. C. Escobedo, J. M. Almanza, A. Flores, Cortés. D. A.

Secondary aluminum dross, which has been exposed for several years to atmospheric conditions, was characterized using chemical analysis, X-ray diffraction, optical and scanning electronic microscopy, and energy-dispersive spectroscopy. Based on the characterization, a method to purify the solids is presented. This method starts with the washing of the dross in boiling water to eliminate the soluble compounds like Na and K, followed by the physical separation of the metallic aluminum by milling and screening. Finally, an acid lixiviation process is applied using three different acid solutions, HCl, HNO3, and H2SO4. The best results were obtained using HCl. The main insoluble components of the dross after lixiviation were Al, SiO2, and Al2O3. MgAl2O4, AlN, Si, and Na2Al22O3·2H20 species were also found. Based on the alumina content, the solid product could be suitable as a raw material in the manufacture of castable refractories or metal matrix composites.

Jan 1, 2005

By R. L. Dunsmore

Introduction If one had been called upon to describe petroleum oil refining seventy-five years ago, he could have acceded to the request quite satisfactorily in about fifteen minutes. Fifteen years ago, an hour and a half would have been sufficient to give a general idea of oil refining, and of the equipment used for this purpose. Today, so extensive has been the research into all phases of the refining and manufacturing of petroleum products, and so rapid the strides in improvement in technique and equipment, that I doubt if a week would suffice to give an adequate outline of ail the ramifications of present-day oil refining. I propose to only 'hit the high spots', dealing particularly with the equipment and methods employed at the Imperoyal refinery, which you are to visit. Crude oil, the refiner's raw material, contains essentially only two elements, hydrogen and carbon. These are not present in the free state but are combined in various proportions as 'hydrocarbons'. A given crude oil is not made up of just one hydrocarbon, but of myriads; some solid, others liquid, and still others gaseous at atmospheric temperature and pressure, ail dissolved one in the other. Moreover, the nature and the relative amounts of the several hydrocarbons vary very considerably in crude oils from different sources. That is, a 'crude' from Oklahoma will contain hydrocarbons not present in crude from Mexico, and is different again from the Venezuela crude. Not only this but oil in a certain well in, say, Peru may be differently constituted from that in a well half a mile distant from it.

Jan 1, 1931

By D. Lindeman, R. M. Nendick

"From a technologist's point of view, there have been few fundamental 'breakthroughs' in the process of gold extraction since the turn of the century. However, the industry has made a great deal of progress in its response to the problems that have arisen: a changing demand for products, lower grade and more refractory ores, inflated labour and materials cost and the increasing control of governmental legislation. The trend in North America and South Africa to alleviate these problems has been to adopt a common policy to process larger tonnages of lowgrade ore through more efficient milling circuits. Here, however, is where the similarity ends.The purpose of this paper is to emphasise the different principles of practice employed by extraction plants in North America and South Africa to achieve the same common goal, namely gold bullion.2.0 INTRODUCTIONTwo very important aspects of extraction metallurgy for which the metallurgical engineer is responsible are plant design and plant commissioning.In North America and South Africa the importance of these aspects is due to the fact that both are related to the financial success of the project of which they form part. Good design is imperative if the capital invested in both the plant and the whole mining undertaking is to reap maximum profit. Furthermore, good design leads to a carefully planned and well executed start-up procedure resulting in bringing the plant into production on time, at designed efficiency and within budget.Due to the competent nature of the quartz pebble conglomerate and quartzite ore on the South African Witwatersrand, the characteristics of the ore type are not much different from one mine to the other. Thus a significant operating knowledge and experience has been built up over the years and there is considerably less risk in selecting a gold extraction process route."

Jan 1, 1992

By J. A. Reid

THE views and observations expressed herein on this old but constantly recurring question are our own, no effort having been made to align them with standard texts. Therefore, while they may find general acceptance amongst fellow engineers, they must stand as personal opinions and as such are open to debate and discussion. In order properly to consider the subject, it should first be 'set in proper perspective. Why are Prospects Examined? Prospects are examined to determine whether they may contain economic concentrations of metals or minerals, the legitimate mining business being run, pretty largely, to make money. Next to food and clothing, modern civilization is based on metals, with which are included in this discussion minerals, oils, and fuels. A constant and increasing demand for the common metals requires the location of replacements for depleted orebodies, while the use and appreciation of new metals brings increasing demand for them. Aluminium is a good example of a metal which has, within recent years, made great progress. Today, we are becoming increasingly aware of magnesium, chromium, tungsten, thallium, and other lesser known, metals.

Jan 1, 1945

By Mike Johnson, Niels Verbaan, David Dreisinger

The Search Minerals Foxtrot project in Labrador represents a significant Canadian resource of rare earth elements rich in the sought after heavy rare earth elements (19.8% HREE/TREE). A preliminary economic assessment of the project indicated that the project is technically feasible and economically attractive. A variety of metallurgical test programs have been undertaken which have led to significant streamlining and simplification of the process flowsheet. The improved flowsheet should allow Search to reach production earlier and will use conventional processing equipment. The results of these test programs are presented and discussed in this paper.

Jan 1, 2014

By F. D. Ball, D. E. Gemmell

"Coal mining in New Brunswick dates from the year 1639, when, as today, coal was produced from the area surrounding Grand Lake near the geographic centre of the province. Current production by N.B. Coal Ltd. is approximately 453,000 tonnes per year and comes from a single, thin Pennsylvanian age seam. The history of development and understanding of the geological setting of New Brunswick coals is discussed, beginning with the work of A. Gesner in 1839. The lithostratigraphic sub-divisions of the Pennsylvanian strata proposed by various workers are summarized and the present hypothesis that only biostratigraphic subdivision is possible is detailed. The Pictou Group, which includes the New Brunswick coals, consists of repetitive sequences of sediments consistent with flu vial and upper delta plain sedimentation. The development of coal mining in the province has progressed from horse-powered stream-bank stripping operations prior to the late 1800s through to the present use of open stripmining techniques utilizing eight walking draglines of various sizes. During the intervening years the introduction and eventual phasing out of underground mining occurred with the near termination of the coal mining industry in the province prior to 1973. The coal seam worked by N.B. Coal Ltd. averages 46 cm in thickness, has never been found to be more than 76 cm thick and has both high ash (12.4 -31.1%) and sulphur (4.9-7.8%) content. The wide variety of coal beneficiation studies and tests completed on New Brunswick coals have lead to the conclusion that a washed New Brunswick coal product could be expected with 10 to 12% ash, 5 to 6% sulphur, and 30,225 to 31,388 1/gm. Recoverable coal reserves, including those in the area licenced to N.B. Coal Ltd. and those licenced, although not yet in production, to both the St. Lawrence Cement Co. Ltd. and Provincial Holdings Ltd. at Lake Stream and Beersvil/e, total 60 million tonnes. At present, coal in New Brunswick is removed from prospecting and staking and all existing and future coal exploration and development will be administered by agreement under the Mining Act. Based on the results of a recently completed drilling project undertaken by the Department of Natural Resources, seventeen coal exploration blocks which carry minimum work commitments will be offered to the New Brunswick Electric Power Commission on a sixty-day first right ofrefusal basis. Those blocks not taken up by the Power Commission will be offered under the same commitments to the private sector."

Jan 1, 1985

By A. T. Jakubick, A. MacG. Robertson

This paper reviews key issues related to the placement of dry (soil) covers on extremely weak, compressible fine tailings. The design and construction of soil covers on such tailings often presents a formidable challenge to the geotechnical as well as the environmental engineer due to the low shear strength, poor traffic ability, and high settlement of under consolidated tailings at the time of reclamation. The geotechnical issues to be considered include: (1) consolidation of near-surface tailings to achieve strength gains, improve traffic ability, and allow safe placement of initial cover layer; (2) stability of tailings slopes during dewatering of tailings ponds and/or cover placement; and (3) long-term settlement of tailings and its impact on cover integrity and final surface shaping. The environmental issues to be considered include: (1) management of contaminated (free) pond water; (2) management of contaminated pore water expelled during tailings consolidation; and (3) management of (uncontaminated) surface water on top of the cover. This paper summarizes recent experiences gained in a large uranium tailings reclamation project. It is concluded that a careful consideration of both geotechnical and environmental issues during the planning stages greatly reduces the costs and environmental risks associated with fine tailings reclamation.

Jan 1, 2000

By Jon R. Maki

"EVTAC, an iron ore mine in Minnesota, had trouble meeting the customer’s pellet silica requirements. In addition, the mine plan was moving towards a lower grade ore and funding was not available for plant improvements to compensate for the change in ore or improving quality. Small changes to optimize various processing equipment resulted in significant improvements in both quality and productivity; for example, productivity on one mill line increased by 10% while producing lower silica concentrate. This paper will provide the methodology that allowed EVTAC to improve quality and productivity through process optimization with little capital investment.INTRODUCTION EVTAC, an iron ore mine in Minnesota, had trouble meeting the customer pellet silica requirements. In addition, the short-term mine plan was changing to a lower ore grade. Because of limited funds, EVTAC did not have the capital for investing in the plant to compensate for the ore change or to make improvements to lower product silica levels. Small changes to optimize process equipment resulted in significant improvements in quality and productivity; for example, one mill line feed rates increased by 10% while also producing a higher quality concentrate. These changes were sufficient enough to allow the mine to lower the target ore grade beyond their initial goal. At one time, a $3M flotation facility was considered as a way to meet quality with the new ore grade. However, the process changes were able to accomplish the same silica reduction with roughly a $50,000 investment in VFDs for sump controls. This paper will discuss some of the modifications that allowed EVTAC to meet the quality and production objectives with little capital investment. It also discusses the methodology used to make these process improvements."

Jan 1, 2014

By E. H. Henderson

Introduction Stamp-Milling and amalgamation is, perhaps, one of the oldest processes of recovering gold from its ores. Many papers, theses, and textbooks have been written on the subject of stamp-milling practice in general, but, to my knowledge, there have been no publications describing the modern stamp-mill as designed, developed, and operated in Nova Scotia. Although it may be said that the gravity stamp-mill is the most primitive, and perhaps the crudest, crushing machine in existence, it is at the same time the most satisfactory all-round milling and amalgamating device yet contrived. Originating in Saxony, and used in North America first in Virginia and Georgia, the stamp-mill, in a primitive form, later found its way to California and Colorado. Here, it speedily developed from an affair of wood shod with iron, and operated with the crudest gearing, to substantially its present form. Briefly, it consists (see Figure 1) essentially of a series of hammers (the stamps), which fall upon a mixture of ore and water contained in a cast-iron box (the mortar). The resulting crushed ore (the pulp) is splashed out through a screen on the front of the box. For some years after the discovery of gold in Nova Scotia, in 1861, the ? arrastra and Chilean mill were used to recover the gold from the rich ores. The stamp-mill followed, and various types were used, principally the California and Gilpin County types. Then, in 1895, Mr. M. R. O'Shaughnessy, one of our foremost amalgamators, conceived the idea of a new type of stampmill, which has since become standard in Nova Scotia gold mines. This mill, unique in its design and operation, is specially adapted for the most efficient extraction and recovery of gold as it occurs in our Nova Scotian ores. It is commonly known as the Underwater Feed type, as opposed to the usual Overwater or Top Feed type, and it may be rightly termed The Nova Scotia Self-Classifying Stamp Amalgamation Mill. It is conceded by experienced mill-men that it is superior to any other type of mill for recovering the very coarse and granular gold typical of the ores of this Province. The particular installation and practice to be described in this paper is that of the Guysborough Mines, Limited, at Goldenville, Guysborough county. Emphasis will be laid on certain operating innovations of extreme simplicity and high efficiency.

Jan 1, 1935

By F. K. McKean

Introduction The present paper may be considered as a sequel to a paper, A Process for Cleaning Molybdenite .Concentrate, which was presented by the author at the annual meeting of the Institute last year. In that paper, a description was given of the laboratory work leading up to the adoption of a new process for treating complex molybdenite ores of the Molybdenite Corporation of Canada. A bare outline of mill performance with the new flow-sheet was included. With this writing, the purpose is to describe the highly interesting work of translating laboratory experience into mill practice, to show what changes were required in design to put the scheme on an operational basis, and to point out the gratifying improvements in mill products which resulted from the new procedure. The process has been placed in operation at the La Corne mine of the Molybdenite Corporation of Canada. This mine was operated during the war by Wartime Metals Corporation, and, earlier, by the Molybdenite Reduction Company, which installed a small plant. The property is situated on the highway from Amos to Val d'Or, Quebec. The claims held by the Company are at the boundary between La Corne and Vassan townships.

Jan 1, 1947