Search Documents

By F. T. Cawood

The definition of mineral rents has historically been somewhat unclear, but a growing understanding of the source and composition of the revenues that comprise these rents mean that they can be more easily identified and quantified. Furthermore the way in which the flow of the rents from mineral developments are captured and then distributed has been a point of contention amongst the various stakeholders. Investors, the host government, the resource owners, environmental interests, indigenous groups and land owners are identified in this paper as the principal participants in mineral development and while each is entitled to a portion of the rent, the size of their portions will differ. A competitive rent-sharing model for southern African countries has been established and indicates how the range of stakeholders could be rewarded for their contribution. Acceptance of the sharing ratios amongst the recipients is a function of their understanding of the size of the rent and their position in the hierarchy of stakeholders. At first glance investors appear to receive the largest share of the rent, but they disburse some of the rent to hidden costs, which when all is said and done, means that investors and host governments retain approximately equal shares of the mineral rent. Both the investor and government are faced with the dilemma of how to equitably distribute the rents they have captured to minority stakeholders. Government captures corporate tax, mineral royalties and a wide range of subordinate taxes, but is required to construct policies that will ensure distributional equity among the various levels of government as well as among the provinces that comprise the country. Investors will have to ensure that a portion of the rents they capture are diverted to other stakeholders namely resource owners, environmental interests, indigenous peoples groups and the landowners. This paper identifies the major recipients of rent and provides some indication of equitable distribution ratios for mineral wealth among them?a first step in ensuring that mineral development is compatible with long-term sustainable development and in the best national interests.

Jan 1, 2002

By Aurelio L. Miranda V.

Desde 1938, el estudio de La Brunquita, especie de mineral del zinc, ha conllevado diversos estudios y pruebas de flotación no solo a nivel peruano, sino internacional, a fin de determinar el procedimiento económico para su explotación industrial. En este aspecto, el objeto del presente texto señala los factores, estados problemáticos, como los resultados obtenidos durante del tratamiento del mineral en la mina de Cercapuquio. Entre los factores destacados encontramos: abundancia y ley alta del mineral, cotizaciones actuales en el mercado internacional y la labor de los técnicos. Respecto de las condiciones problemáticas que refiere las características del mineral, tenemos el difícil control rápido de la marcha de flotación, degradación del mineral e imprecisión entre el mineral y la ganga, dado el tamaño de las partículas del mineral. Finalmente, los resultados obtenidos en este proceso, muestra que para el tratamiento de pre-concentración aplicado a los minerales finos de Cercapuquio, se necesita la hidratación ya que facilita la flotación posterior del mineral. Asimismo estas operaciones de pre-concentración no solo aumentan la ley de alimentación a los molinos y la capacidad de las plantas de beneficio, sino también que modificando la composición física del mineral, mejoran las condiciones del tratamiento posterior.

Jul 20, 1956

By Gustavo Mammana, Aníbal Amirá

El escenario que enfrenta la minería chilena en materia de productividad plantea el desafío de definir estrategias que contribuyan a optimizar los procesos de dirección, gestión de proyectos y operaciones, agudizados por el envejecimiento de los yacimientos, la disminución de leyes, la fluctuación de los precios de los commodities, y el costo de la mano de obra e insumos. Este trabajo busca difundir las herramientas empleadas y las mejoras obtenidas a partir de la aplicación del Modelo de Excelencia Operacional –ExOpeHS, orientado a aumentar la eficiencia y la productividad en proyectos de ingeniería y construcción, mejorando los procesos de selección y reclutamiento, logística y control de proyectos; así como de la herramienta denominada TF30D, destinada a mejorar en corto plazo los resultados en las faenas mineras Chuquicamata, Centinela y Sierra Gorda (Chile).

Sep 20, 2019

By Jacolien P. Wyethe

Zincor uses a Roast-Leach-Electrowinning circuit to process zinc sulphide concentrates. It also processes zinc oxide fume, originating from a slag smelting operation in the Democratic Republic of the Congo (DRC). Zincor achieved an average zinc recovery of 90.3% during the period January 2006 to May 2007. The bulk of the losses occurred in the iron and lead silver residues, both as soluble and un-dissolved losses. The un-dissolved losses in the iron residue constituted around 33% of the total zinc lost from the circuit, and were largely attributed to the presence of zinc-ferrite in the calcine used for neutralization during iron removal. As part of Zincor?s continuous improvement programme, the un-dissolved zinc losses in the iron residue were targeted by: the partial replacement of calcine with zinc oxide fume (from the DRC); and the preferential use of ?low-ferrite content calcine? as neutralizing agents in the iron removal circuit. These initiatives, coupled with other operational factors, resulted in a marked improvement in recovery to 92.6% during June to December 2007. The zinc oxide fume, directly fed to the circuit, required investigation of the halide rejection capacity of the Zincor circuit. Rejection of chloride via the magnesium bleed operation was considered adequate. Fluoride was mainly rejected via the iron (~70%) and lead silver (~27%) residues. Fluoride rejection via the lead silver residue varied significantly, probably as a result of variations in the sparingly soluble CaF2 content in the feed. The mechanism for fluoride rejection in the iron residues is uncertain. The fluoride rejection capacity of the Zincor iron residue (comprising of mainly jarosites, schwertmannite and ferrihydrite) at 2 ? 4 mg/L F in solution, was estimated at 0.14 ? 0.19 kgF/tFe residue.

Jan 1, 2008

By L. C. St. Arnaud

"Open pit mines can produce large disturbances within regional hydrogeologic systems. The degree of disturbance and the consequences on the local environment depend on the size of the pit and on the physical setting of the mine. Comparisons and contrasts are presented for three Noranda base metal open pit mine sites.The Brunswick Mining and Smelting No 6 open pit has a surface area of 11 ha and a depth of 185 m. It is located within complexly deformed schists and meta-volcanic rocks. The massive sulphide and iron formations visible along the north and southwest walls of the pit generate acid drainage. Mining ceased in 1983, and the pit is presently being filled with waste rock and neutralized drainage water. Water balance calculations estimated a total fill up time of sixteen years. As the water level rises, leakage to groundwater could take place across a fault zone intersecting the pit.The Mattabi Mines F-Group pit has a surface area of approximately 3 ha and a depth of 50 m and is also set in meta-volcanic rocks and acid generating iron formations. Production at this site ceased in 1982, and the low pH pit water is neutralized and pumped into a nearby lake at least every five years. Major water inflows are from precipitation and groundwater. Groundwater mounds within adjacent high land surrounding the pit provide a natural hydraulic barrier to groundwater flow, except for the southeast side. As a consequence, the pit water elevation is being kept below the elevation of the nearby creek in which some of the pit water could drain.The Bell Copper open pit covers an area of 40 ha and is 270 m deep. With present ore reserves, the mine might be in operation until 1992. The geology around the pit consists of andesitic tufts, siltstones and shales, and the acid generation potential of the rock is relatively low. A recent hydrogeological study estimated fill up time by precipitation and groundwater to be in the order of 260 years.With increasingly more stringent requirements for mine closure, it is anticipated that more detailed hydrological and hydrogeological studies of open pits will be required to determine post-closure environmental impacts and the suitability of open pits for mine waste disposal."

Jan 1, 1990

By P Taskinen, D Lindberg

The increase in metals demand in the electrifying globe means significant growth in the smelting of copper, nickel, zinc, and lead, produced from primary sulfide sources or using sulfide mattes as the intermediates of the process chains. This means that leaner and complex mineral deposits will be evaluated as ores and are in the future traded in the commodity market for smelting and refining to pure metals. An important issue in the trend is the technology metals, like antimony, tellurium, and gallium, which exist as trace elements in sulfide ores and form no ores of their own. Their recovery becomes important in the coming decades as will be the case with growing slag amounts without use in other industries. The key is to produce environmentally acceptable slags in the smelting operations. It sets new boundary conditions to the treatment of flue dusts. This means that all material streams of smelting and refining must be re-evaluated for the deportments of the main and minority metals. In copper smelting, the recoveries of precious metals are today important for the feasibility of the custom smelters but due to low prices of many minority metals they are discarded in slag landfills. It is one of the emerging issues also in the secondary copper smelting today and once the demand grows, the same question will be faced also in the mining-beneficiation-smelting-refining chain of the primary production of nickel, zinc, and lead. The distributions of many technology metals in the copper and nickel smelting have been recently studied using methods where the chemically bound trace elements in the slag and its phases at the smelting conditions have been studied. Thus, the key data about options for process modifications and additional processing steps are piling up. Short processing routes in the metals smelting and refining are attractive due to their simplicity. At the same time, complexity of many raw materials challenges the fluxing at high oxygen partial pressures in low silica slags with high metal concentrations. The compromise between high primary recovery and safe operation is a demanding task in conditions where slag foaming outside the processing window is evident. The increase in the demand of pure nickel is challenging the raw material basis where low-grade sulfide ores are soon smelted along with nickel laterites to matte. It is a demanding task at high MgO concentrations. The low solubility of MgO in iron silicate slags requires new fluxing strategies and new smelting end points for the operation at reasonable temperatures; the direct nickel matte smelting in one-matte mode may be an option.

Aug 21, 2024

By P. J. Foster

A common theme running through recently introduced mining health and safety legislation in many parts of the world is risk assessment. Most recently, risk assessment legislation has been introduced across the mining industry of South Africa and the view that the introduction of risk assessment based legislation provides an ideal opportunity to improve on past health and safety performance is presented. Risk assessment techniques range from highly complex safety system techniques that are used in high technology process industries, to subjective techniques based on simple judgements that are finding use in many other industries. The objective of this paper is to shed some light on risk assessment, not by detailing the risk assessment process but by identifying the crucial elements that need to be considered if risk assessments are to be successful in changing health and safety performance. A case study is presented illustrating the introduction of risk assessment into the Ingwe Coal Corporation, one of South Africa?s largest mining houses, to indicate how the system was developed and how it is being used.

Jan 1, 1998

Bateman Engineering managed the establishment of a second diamond treatment plant at the Letseng Mine in the Mokhotlong District of northern Lesotho, about 100 km from the town of Buthe Buthe. Letseng Diamonds Proprietary Limited, is owned 70 % by Gem Diamonds and 30 % by the Government of the Kingdom of Lesotho. The second plant, which commenced construction in late 2006, doubled Letseng Mines' hard rock processing capacity from 2.6 million t/yr to 5.2 million t/yr, making it the worlds' seventh largest diamond mine by throughput. Bateman Engineering provided the engineering design, procurement and construction management of the new plant.

Jan 1, 2010

This geometallurgical study examines the gangue mineral variability at the Bingham Canyon porphyry copper mine in Utah. Understanding an orebody?s mineralogy is important for mine and mill planning because it provides information on the size, texture, and distribution of ore minerals, the relationship between ore and gangue minerals, and the extent and type of alteration. Quantification of the mineralogical variability and properties of an orebody provides valuable input to the ore model and may have a significant effect on recovery optimization. This study was designed to be carried out on an initially detailed scale in order to develop a robust methodology for measuring and quantifying specific parameters, such as the distribution of mineral phases, alteration assemblages and fractures from key ore domains at the Bingham Canyon mine (Figure 1). Details of the methodology are reported below. This technique can be applied to testing the impact of mineralogy on a number of processing parameters. [ ] Figure 1. Ore domain map of Bingham Canyon (Kennecott Utah Copper, 2003) showing the 33 geometallurgical ore domains. The samples for this study were collected from the northwest part of the deposit circled on the map. PROJECT BACKGROUND Geology The Bingham Canyon deposit is a large porphyry Cu-Mo-Au deposit with associated skarn and base-metal replacement deposits mined in an open-pit mine measuring about 2.5 miles across and 4,000 feet deep. The deposit is hosted by the Bingham Stock, a Late Eocene to Mid-Oligocene intrusive complex. The skarn is hosted by the Late Carboniferous-age Bingham Mine Formation, which is comprised of quartzites and basal limestones (Babcock Jr. et al., 1998). The Bingham Stock is a composite intrusive complex that was emplaced over a period of about two million years. The oldest phase is described as a fine-grained equigranular monzonite (MZ), which intruded the country rocks at 39.8 ± 0.4 Ma (U-Pb zircon TIMS age) (Parry et al., 2001). Subsequently, the quartz monzonite porphyry (QMP) was emplaced, followed by intrusion of a latite porphyry (LP). The final intrusive phase, which forms narrow dikes that crosscut the Bingham Stock, is represented by a quartz latite porphyry (QLP), which is dated to 37.5 ± 0.4 Ma by 40Ar/39Ar dating of sanidine (Deino and Keith, 1998). Also present, are a minette dike in contact with a QLP dike (Waite et al., 1998; Deino and Keith, 1998), and a biotite porphyry (BP), a quartz latite porphyry breccia (QLPbx), and a pebble dike (Redmond, 2002). The copper orebody is centered above the Bingham Stock and forms an inverted cup shape with three high-grade copper zones extending to depth. Molybdenite mineralization occurs within and extends below the copper orebody, but is not correlated with copper mineralization. The main sulfide assemblage is chalcopyrite, bornite, molybdenite, and pyrite. Gold is locally intergrown with chalcopyrite and bornite (Babcock Jr. et al., 1998; Phillips et al., 1998). The surrounding country rocks host skarn deposits with three main ore types - garnet skarns, massive sulfides, and iron oxides. The garnet skarns contain chalcopyrite and pyrite with magnetite veins. In the massive sulfides chalcopyrite and pyrite occur either in banded sulfides or in unconsolidated microbreccias. The iron oxides contain disseminated chalcopyrite with minor chalcocite and bornite (Harrison and Reid, 1998). The deposit is overprinted by several stages of alteration. Potassic alteration is concentrated at the center of the deposit. It is surrounded and partially overlapped by a propylitic alteration zone. Both zones are overprinted by sericitic alteration. In the northern part of the deposit evidence for argillic alteration can be found (Bowman et al., 1987). Similarly, the skarn deposit was also overprinted by several stages of alteration: wollastonite, idocrase, and garnet in cherty limestones, and quartz and diopside forming in calcareous quartzites. Distally, diopside was replaced by talc, tremolite, dolomite, secondary calcite, and pyrite, and quartz and sulfide veinlets with biotite and actinolite selvages are present. Andradite garnet, diopside, quartz, magnetite, hematite, and copper sulfides were overprinted by wollastonite (Babcock Jr. et al., 1998). Because the monzonite, quartz monzonite porphyry, latite porphyry, and quartz latite porphyry host the bulk of the mineralization, our research is focused on these lithologic units. Geometallurgy On the basis of geological (lithology, alteration assemblages, fracture density, copper mineralization) and metallurgical properties, the deposit has been divided into 33 ore domains by mine geologists and metallurgists (Figure 1). In map view, these domains cross geologically defined boundaries (MZ, QMP etc.). These domains reflect regions of the deposit that have particular, mapable attributes or properties. They reflect a combination of geological and mineralogical characteristics that combine to impact processing. Alteration, for example, as shown by talc mineralization, is one such key feature. Hardness may reflect the absence of sericitic but presence of potassic alteration. Structural discontinuities such as faulting, fracturing, or development of void

Jan 1, 2009

Correlation of Air Recovery with Thin Film and Froth Stability in Flotation

Sep 13, 2010

By Phillip J. Mackey, Rodney T. Jones

"Copper and copper alloys remain key materials for society today, with important uses found in the electrical, transportation, and construction industries. Copper demand is rising, with projections indicating that by 2025 global refined copper demand will increase to 29.5 million tons, up from the 22.4 million tons anticipated for 2015. This will require the opening up of dozens of new mines and numerous new smelters over this time period. Fortunately, Africa has significant reserves of copper, and African copper can once again play a key role in contributing to meeting the rising global demand for copper. This paper provides a brief overview of the current copper smelting operations in Southern Africa. INTRODUCTION Copper and copper alloys are essential materials for today’s modern world. The familiar green copper patina colour seen on buildings and other structures sometimes belies its true “green” characteristic – copper is essential for key emerging technologies such as wind turbines, tidal generating systems, solar energy systems, electric cars and the like. Consequently, it is believed that there will be continued growth in copper demand in the years ahead. Projections indicate that by 2025, as an example, global refined copper demand will increase to 29.5 million metric tons, up from the 22.4 million ton level anticipated for 2015. This will require dozens of new mines, and of the order of the equivalent of 10 to 12 new 0.5 million tons of copper/year-sized copper smelters (after factoring projected copper produced by electrowinning (EW))—overall, a huge undertaking. Fortunately, Africa has significant reserves of copper, and African copper can once again play a key role in supplying this rising global demand for copper. Africa’s share of global mined copper production was about 10% in 2014; however this will increase significantly in future if announced new projects eventuate. Southern Africa has an important role to play in this process. The present paper provides a brief overview of copper smelting in Southern Africa."

Jan 1, 2015

By E. Yalçin

The data set often contains one or more secondary variables. These secondary variables are usually spatially cross correlated with the primary variable. The addition of the cross-correlated information reduces the variance of the estimation error by using the cokriging method. The grade estimation results of ordinary kriging and cokriging methods are evaluated and it was found that the estimation variance of cokriging method is slightly lower than ordinary kriging. The effect of variation of block dimension on the estimation results is also investigated and it was seen that the cokriging estimation variance values also decrease as the block dimension increases.

Jan 1, 2005

By C. F. Strydom

Paper written on project work carried out in partial fulfilment of B. Eng (Mining Engineering) degree The Self-directed work team concept is the product of relentless performance pressure on American industries during the late eighties and early nineties from other world industrial leaders like Japan. The concept proved to be a successful vehicle by which the Americans could increase their production and improve their safety statistics. The aim of this study is to evaluate the concept as a means to improve the overall performance on South African goldmines. he study is directed by a historical research section, answering questions like: ?Why do we need to change? ?What is a Self-directed work team? ?What are the principle advantages of the concept? ?What are the essential requirements for the concept to succeed? The study also includes an empirical research section that focuses on the current Self-directed work team situation in the South African gold mining industry. The empirical research section is limited to three case studies within Anglogold due to a study period of only six weeks. The mines chosen for the case studies have been labelled Mine 1, Mine 2 and Mine 3. The latter being the base mine allowing for a more in depth study. This includes a perception analysis towards Self-directed work teams within the mine. The study proves the truth of the Latin proverb ?Tempora mutantur, nos et mutamur in illis? meaning ?The times are changing, and we are changing with them?. The chief change catalysts identified are a dwindling gold price and a projected labour crisis. From the study it is evident that the Self-directed work team concept disposes of the critical parameters required for a dramatic improvement in performance. The study also indicates that for the concept to succeed, certain factors like top-level commitment and management-employee trust have to be in place. Sadly, the concluding part of the study proves that very few of the identified critical success parameters are present in the South African gold mining industry. This can serve to explain why the industry only has success with the concept when monetary gain is the chief motivator. The study only focuses on the reasons why the concept is not performing to its full potential and does not wander into explaining the reasons for the current unsupportive milieu in the industry. Self-directed work teams could well rescue the South Africangold mining industry but currently we are driving a square pin into a round hole! [Terminology SDWT?Self-directed work teams AEL?Adventure Experiential Learning ISW?In-stope worker POLC?Plan, organize, lead and control TEC?Total employee costed Silo?The confinement of departments preventing networking JCI?Johannesburg Consolidated Investment Co. Ltd]

Jan 1, 2002

By Silvana Costa

Rapid changes in technology and human resources trends require the mining industry to plan carefully for new work camps. The abandonment of the “mining town” concept and rapid increases in the adoption of long distance commuting have intensified the need for improved planning and monitoring of existing and upcoming operations. New mines will have an increasing Aboriginal participation in their workforce and will mostly to be located in remote and in extreme weather conditions. In this sense, the intensification of the use of the commuting system has increased the need for improved planning and monitoring of upcoming operations. Given that mining development is experiencing a surge in activity in Canada, particularly in remote and northern locations significant number of individuals will get jobs that involve mine camp communities. Some employees will spend half of their working lives at the mine site for a period of time that can last up to 30 years. Even though investments have been made towards particularly high quality physical environments, mine camp policies, programs and employee quality of life in mine camps have not been studied in any depth.

Sep 12, 2005

This chapter presents proportionate mortality ratios (PMRs) derived from death certificate data in the National Occupational Mortality Surveillance (NOMS) database for the years 1986 through 1993. At the time this report was prepared, 1993 was the latest year for which data were available. Industry is classified under the 1980 U.S. Bureau of the Census classification system [Bureau of the Census 1982]; cause of death, under the International Classification of Diseases, Ninth Revision (ICD-9) [World Health Organization 1977]. A PMR of 100 indicates a mortality risk for a particular industry group that is similar to that for all industry groups combined. A PMR over 100 suggests a higher risk; a PMR under 100 suggests a lower risk. PMRs are subject to many factors that affect their reliability and validity and may not be comparable across populations with very different causes of death. An elevated PMR for a specified cause of death among an occupational or industry group may indicate a relationship between a work exposure and the cause of death specified. However, there are many limitations of PMRs as a measure of risk; they are most useful for generating hypotheses about exposure-disease relationships, which can then be tested in other studies. Selected PMRs are presented separately for males and females for coal mining, metal mining, nonmetallic mineral mining and quarrying (which includes nonmetal, stone, and sand and gravel), and for oil and gas extraction. All PMRs have been adjusted for age and race. In general, PMRs are presented only if the lower 95% confidence limit exceeded 100. If a PMR in an ICD-9 subcategory was above 100, however, the PMR for the larger category into which the subcategory falls is always presented and may be less than 100. PMRs can be expected to be elevated for conditions that have a high prevalence in particular occupational groups. PMRs showed elevated values for conditions known to affect miners, such as coal workers' pneumoconiosis, pneumoconiosis due to silica, tuberculosis, chronic pulmonary heart disease, and injuries. Additional findings of interest were- • An elevated PMR for myocardial infarction among male coal miners (table 2-1); • Elevated PMRs for neurologic disease in general and anterior horn cell disease, in particular among male metal miners (table 2-3); • An elevated PMR for rheumatic heart disease in male metal miners (table 2-3); • Elevated PMRs for malignant neoplasms of the digestive organs and peritoneum and for malignant neoplasms of the colon and rectum in female nonmetal miners (table 2-6); and • Elevated PMRs for non-A, non-B hepatitis and arteriosclerotic heart disease among male oil and gas workers (table 2-7).

Jan 5, 2000

By M Lovitt, T Hewitt

The extraction of drawbells in Lift #2 at Northparkes Mines E26 orebody was achieved by single shot blasting, enabled through the use of electronic detonators. This paper discusses the designs considered at the time of the feasibility study and the various changes made to these designs prior to and during the construction phase of the Lift #2 block cave. Operational issues encountered are highlighted, as are ways in which these were overcome. The amount of personnel utilised to mine the drawbells is also covered. Lists of design and operational considerations to be used for drawbell extractions have been included.

Jan 1, 2005

By G. H. Lind

This paper discusses the traditional costing approach currently used in the underground coal mining industry. Activity Based Costing (ABC) is identified as being a potentially more effective manner in which to cost underground coal mining systems. With the use of a costing framework developed by the author incorporating new thinking to eliminate the shortcomings identified in the traditional costing approach, a comparison of two types of underground coal mining systems, viz. continuous miner and longwall, is conducted. It is found that under certain criteria, in all cases, irrespective of the way in which the systems are costed, the continuous miner system is currently the better investment. It is also observed that when a system is costed using ABC that better investment decisions result when compared to costing the same system using traditional costing techniques. It is further seen that traditional costing techniques tend to overestimate the total costs of a mining system. This paper shows one application of ABC that can be incorporated as a management tool.

Jan 1, 2001

By Johnna Muinonen

"The Thompson Mill processes ores from the Thompson and Birchtree Mines. While the Thompson ore has very little magnesium containing gangue, the Birchtree orebody consists of veins of massive sulphide in a rock matrix that contains a high proportion of magnesium silicate minerals. A significant fraction of the magnesium is floatable, which lead to MgO levels varying from 3-11 wt% in the Birchtree concentrate. The magnesium in the concentrate causes a higher operating temperature in the smelter, reducing furnace life.Birchtree ore represented 20-30% of the mill ore receipts prior to October 2003. Since then the fraction of Birchtree ore has increased to 50%. A reduction of the MgO in concentrate to less than 3% in the total mill concentrate was required to allow safe and economic smelter operation.In October of 2002 a miniplant was set up to simulate the Birchtree plant circuit. Several flow sheet modifications were tested that led to a proposal for a circuit having increased cleaning capacity for the scavenger concentrate and a recleaner on this concentrate. Addition of CMC in rougher cleaner feed was also found to be required. The solution was confirmed through pilot plant testing in the mill in December of 2002. A full-scale installation was designed, engineered, and installed between February and September of 2003 with commissioning in September and October of 2003. Target metallurgy was achieved one week after start-up on slurry to coincide with the Birchtree Mine tonnage increase. This paper highlights the development, design and commissioning stages of the project.The new MgO rejection circuit has successfully allowed the processing of Birchtree ores producing concentrate consistently below 3% MgO. In addition, the new circuit increased overall nickel recovery in the mill.INTRODUCTIONThe Thompson Nickel Belt located approximately 700km north of Winnipeg was discovered in the early 1950’s. Inco first produced nickel from the area in 1960. Over the years the mill has processed several ores from different ore bodies in the area. Currently the Thompson Mill processes two significantly different ores from two mines, Thompson and Birchtree. The Thompson ore is a massive sulphide orebody hosted in schist, containing feldspars, quartz and biotite. Thompson Ore is characterized by high nickel recoveries and clean, low MgO containing concentrates (<2.5% MgO). The Birchtree ore is ultramafic and contains a high percentage of Mg-silicates such as serpentine, chlorite, biotite, amphiboles and talc. Some of these Mg-silicates report to the nickel concentrate and prior to commissioning of the MgO rejection circuit the Birchtree nickel concentrate typically contained 5-8% MgO"

Jan 1, 2006

By Dale S. Preece

The computer program. DMC Qistinct Motion &de), which w&s developed for simulating the rock motion associated with blasting, has been used to study the intluence of row delay timing On rock mOtiOn. The munerical simulations correspond with field observations in that vmy short delays (< 5Oms) and vety long delays(> 3oOms) produce a lower percent-cast thao a medium delay (100 to ZOO ms). The DMC predicted relatio&lp between row delay timing and percent-cast is more complex than expected with a dip in the auve where the optimum timing might be expected. More study is required to gain a full undasranding of this phenomenoo.

Jan 1, 1994

By Ivan Simon, R. K. McConnell

Anticipating the availability of tiltmeters suitable for use in boreholes, this article proposes a method of using one or more of these meters to determine in situ stress distribution before and after mining operations. Several ways of using relief techniques to measure in situ stresses in rocks have been developed. These techniques, summarized by Merrill,1 involve measuring deformations which take place when a specimen of rock is wholly or partially isolated from the stress field in the surrounding rock. Measurements of rock deformation caused by stress relief from mining operations can, in principle, also be used to estimate in situ stress distributions. Müller2 has mentioned experiments being carried on in Austria with a "deformation indicator" to determine the tilting of holes drilled before a mine opening is made. Similar work using borehole extensometers has been reported by Potts? and Duvall4 has called attention to the possible use of tiltmeters in making these measurements. Considerable attention is now being paid to the use of tiltmeters in detecting rock deformation associated with fault movements, earthquakes, earth tides, etc. The instruments used for these measurements have usually been of the mercury tube, water tube, or quartz fiber type, but because of their large size, and/or fragile nature, such instruments would not be suitable for use in mining stress measurements. Recent instrumentation developments, however, give promise that rugged, sensitive tiltmeters small enough for use in boreholes may soon be available.&apos; In anticipation of these developments, this article presents a number of calculations of the possibility of using one or more tiltmeters emplaced in a drill hole prior to mining operations to determine the in situ stress distribution both before and after a mining operation. Consider point p (x, z) near a tunnel of radius a

Jan 1, 1969