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By D. Lauriski, E. D. Thimons, A. C. Smith, D. C. Fredley

The National Institute for Occupational Safety and Health (NIOSH) and Northwest Barricade LLC (NWB) conducted a study to evaluate the effectiveness of a novel fire blocking gel for use in underground coal mines to extinguish or retard the growth of a coal fire. The gel agent was subjected to controlled laboratory testing to assess its ability to delay coal ignition. It was then evaluated to determine if manual fire hose application could be used to apply the agent to mine roofs and ribs to provide a safe egress for mine rescue teams from a fire area. The gel agent was also evaluated in a water sprinkler system to determine its potential for use in conveyor belt fire suppression systems. The agent was then tested in live-fire exercises to examine its effectiveness in retarding and extinguishing a deep-seated coal fire and wood fire. Lastly, the ability of a mine rescue team to quickly and safely apply the gel agent to a mine entry during a simulated mine fire exercise was determined.

Jan 1, 2011

By Mory M. Ghomshei

"The cost of deep underground mine cooling depends on a number of geological, environmental and economic factors such as the temperature gradient in the mine, the outside air temperature, and the local price of energy. While geological factors, being static, can be controlled to some extent during the mine design, the environmental and economic factors dynamically change and therefore can only be controlled through a flexible mine ventilation system.With an average temperature gradient of 20–25°C/km, the virgin rock temperature at 2,000 m can reach 45–60°C. Conventional cooling at such depths could lead to exorbitantly high costs. In-mine geothermal heat pumps can considerably reduce the cost of cooling through energy communication with the centralized absorption chillers, which service the mine from the surface.It is shown that in-mine heat pump systems can be a viable option for reducing operating expenses and providing some degree of flexibility to cope with fluctuating energy costs. The price of Natural gas and electrify are the most important variables for optimizing the level of interaction between the surface and inmine cooling systems. Deep mine waters can be used to carry a portion of the mine heat to the surface, where the heat from mine can be used as a supplementary energy source for absorption chillers. As an extra benefit, the heat output of the chillers can be used for district heating and or greenhouse growing.The case of cooling deep levels of deep mines in Sudbury Canada (e.g. Creighton Mine) has been discussed. It is shown that an initial 1MW in-mine geothermal heat pump system can save significantly on the cost of cooling. Such a demonstration project will allow R&D on viability of larger similar systems to be incrementally added in the future.INTRODUCTIONThe amount of heat generated in deep and ultra-deep mines depend primarily on the regional temperature gradient and the thermal conductivity of mine rocks. The conductive heat flow is quantifiable and can be minimized or optimized in the process of mine design. Another important heat source can be related to underground equipment such as diesel machinery which often have low efficiencies (approximately 25–35%). This heat source can be controlled and reduced though improving efficiencies or using electrical equipment, which offer a much better efficiency (approximately 80–90%). Mine waters can also be a significant heat source (convectively bringing large amounts of heat into the mine workings)."

Jan 1, 2019

By Raymond S. Suglo

Increasing depths of mining coupled with the mechanization of most underground mining operations have led to growing complexities in the mine environments with the production of large amounts of gaseous and particulate contaminants. Over 100,000 lives have been lost due methane gas and dust explosions in coal mine workings in both the US and Canada since 1900 when the methane concentrations exceeded stipulated levels in some workings. There is therefore the need to constantly assess and evaluate the performance of the existing mine ventilation systems to maintain safe and acceptable mine environmental conditions in workings to meet the requirements of federal, state or provincial laws. This paper uses the results of continuous monitoring of methane concentrations conducted in selected development headings in coal mines in North America to assess the effectiveness of existing auxiliary ventilation systems in the control of methane gas concentrations in the headings. The results show that the average quantities of fresh air required to dilute, disperse and remove methane concentrations within set levels of one minute varied from 5.43 m3/s in Heading #11 (Condition 2) to 27.97 m3/s in Heading #10 (Condition 1) and this represented about 12 to 26% of the quantities required to dilute methane concentrations to safe levels within one minute under Condition 1 and 32 to 139% under Condition 2. The average dilution times in the headings studied were less than 8 minutes. The forcing efficiencies of the auxiliary systems in the headings studied ranged from poor to excellent implying that the auxiliary ventilation systems were capable of controlling the methane concentrations below statutory levels but may not be able to cope with large and unusual methane concentrations in the headings. This study is important to prevent methane gas and coal dust explosions in coal mines and thus avoid any loss of lives and property.

May 1, 2001

Hard rock TBMs are very often open machine layouts, with just a part roof shield over the front of the machine. The whole system is designed for fast face advance and the economy of the project often depends entirely on the rate of advance. Typically, hard rock conditions will demonstrate stable and good ground for a major part of the tunnel. However, short sections of crushed shear zones with clay and gouge material may cause serious time delays. Spiling rock bolting has been proven to be very efficient under such circumstances, provided the fully grouted rebar bolts can be placed in a controlled and practical manner.Environmental restrictions are becoming more and more a part of tunnel excavation projects. Even hard rock TBM tunnelling may require a strict ground water control, because of consequences on the ground surface from lowering the ground water level. Such consequences may be surface settlement, negative influence on ground water resources or damage to vegetation.Pressure injection ahead of the advancing tunnel face (in this paper named pre-injection), using microfine cement and chemical grouts, is today a proven technology. As examples can be mentioned (Garshol, 1997) about 100 km of pre-injected tunnels below Oslo City and about the same length of subsea tunnelling elsewhere in Norway. Examples from other parts of the world are also available, like below Stockholm, Sweden, the Inland Feeder project and Hollywood Metro both in Southern California.To take advantage of spiling rockbolts and pre-injection, it is an obvious prerequisite to be able to drill the necessary boreholes in the right positions and at the correct angle. In drill and blast excavation this is simple, but in TBM projects it has repeatedly turned out to be difficult. More than once owners have accepted bids containing reassurance from the contractor that the drilling method will be sorted out later. Experience shows that if ælaterÆ means after start of the TBM operation, it is often too late.

Jan 1, 1999

By W. M. Small

From the one producing well in Austria, 7000 bbl. of heavy oil was produced and sold in 1933. This well, owned by the Raky-Danubia, was completed late in 1932 in the formation called Flysch (Upper Cretaceous or lower Eocene) near Zistersdorf north of Vienna. Two wildcats drilling in the vicinity have not yet reached the producing beds. Near Vienna, the European Gas and Electric Co. drilled five shallow wells for gas, three of which were failures. One gas well was completed for 8 million cu. ft. capacity at 260 meters depth and with a pressure of 570 lb. Another is being tested following blowouts. One gas well and one dry hole were completed in the pool in 1932. In Upper Austria, the same company abandoned one wildcat at 679 m. and is drilling at 280 m. on a second. No gas was sold during the year, but a line is being completed to supply fuel to boilers of the Vienna Electric Works. Hungary No deep drilling was done in 1933. Oil and gas concession was granted by Parliament to the European Gas and Electric Co. on Trans-danubia. Active geological and geophysical investigation is in progress. Czechoslovakia In the Gbely and Hodonin shallow fields, some 26 wells were drilled of which three were reported as failures. The total production of the fields was 111,736 bbl. of oil and 40 million cu. ft. of gas used as fuel in the field. At Vacenovice, where there were already two small gas wells, a third producer was completed at 420 m. This pool markets a small amount of gas, which is compressed and used to light railway carriages. Wildcat wells were reported drilling at about 300 m. depth at both Jasina and Telnice. One 700-ni. wildcat near the Hodonin field was abandoned. Another failure was reported completed and abandoned at 820 m. near Holic.

Jan 1, 1934

By L N. Loganathan

Risk exposure in tunnel projects is extremely high due to various factors such as variability of subsurface conditions, selection of inappropriate design and tunnelling methods, improper risk assessment on adjacent surface and subsurface structures and utilities, and inadequate contractual practices. The risks in tunnelling must be borne by the contractor, designer and the owner of a tunnelling project. There have been a number of improvements in the last ten to 15 years in the manner in which tunnel projects are developed and implemented in terms of their design, construction, financing and operations. One significant improvement has been the manner in which underground conditions and their risks are being managed. Owners are less willing to transfer the full responsibility to the contractor for managing the underground conditions, although this is a familiar manner in which underground major urban projects have been previously contracted and managed. The owners of tunnel projects in Singapore have advanced the risk management process for their projects through geotechnical interpretative baseline reports (GIBRs), geotechnical data reports (GDRs) and project specifications (PSs). This paper discusses industry practice and its development as well as the application during the preparation and use in Singapore on the Deep Tunnel Sewerage System (DTSS) and the Marina Coastal Expressway (MCE) project in Singapore. The DTSS trunk sewer is 48 km and ranges from 3.3 m to 6 m finished diameter up to 50 m below the ground. The underground conditions ranged from Old Alluvium, strengths of about 1 MPa to competent Bukit Tima granite, with strengths of over 230 MPa. The total route length of the MCE is about 5 km. About 3.6 km will be constructed underground, consisting of dual five-lane carriageways. The underground construction will be cut-and-cover, and 2.6 km will be constructed about 13 m underground, and 1 km of tunnel will range from 13 m to 24 m as the tunnel passes under a 420 m wide reach of Marina Bay, whose crossing will be constructed as a two-phase cofferdam.

Jan 1, 2008

By Saul Hissaci de Souza

A liga de alumínio AA 7075 recebida no estado T6 (conformada e envelhecida artificialmente) sofreu tratamento térmico a 300°C com o objetivo de causar o engrossamento das partículas de MgZn2, intermetálico responsável pelo endurecimento do material. As amostras foram então deformadas 45% em redução de espessura por laminação e recozidas isotermicamente a 200°C e a 250°C por tempos variados para estudar a cinética de amolecimento por meio de medidas de dureza Vickers. Os resultados indicam que a cinética de amolecimento em ambas as temperaturas de recozimento aproxima-se do comportamento previsto pelo modelo Johnson-Mehl-Avrami-Kolmogorov (JMAK) com boa concordância (coeficientes de correlação de 0,9725 e 0,9140 a 200°C e a 250°C, respectivamente), ainda que as micrografias ópticas da amostra recozida a 300°C por 4 horas não evidenciem a ocorrência de recristalização.

Oct 30, 2017

By O Dominguez

Mine value chain reconciliation (MVC) is a necessary procedure to evaluate a mine’s performance against the assumptions and models used to plan mining and processing operations. Using nomenclature from Parker (2012), F2 reconciliation is the ratio between material received at the mill, compared with material sent to the mill, commonly reported in terms of tonnes, grade and metal. Measurements of material sent to the mill can be estimated in many ways, including: fleet management system (FMS) records, truck counts, or volume reduction. Most time-based reconciliations (for example, month-end reconciliation) use short-term model depletions of in situ rock measured by periodic topographic scans or surveys.

Mar 22, 2022

By R. T. Saxon

Prior to November 1975 there were several failures of front -wheel spindles on large haulage truck s in B.C., attributed to fatigue cracks. Since that time, a non-destructive test program has succeeded in detecting the cracks before catastrophic failure, However, the author regards the failures as just one example of a. general unreliability in large high-strength steel castings and urges the industry to look to forgings for sensitive components of heavy equipment.

Jan 1, 1977

By Dominique Francois-Bongarcon

The world mining industry is facing a severe recession. Thus, it is time to recall the value of geostatistical methods which were formerly developed as a money-saving and productivity-increasing tool. The situation has worsened, but the techniques of geostatistics have dramatically changed. Up to millions of dollars can be saved during exploration with simple use of variograms; then, during reserves estimation with kriging methods; and finally, with the parameterization of reserves, when evaluating a project and optimizing its global mining parameters.

Jan 1, 1983

Background Carbon monoxide (CO) is an odorless, colorless gas that can cause illness and death by asphyxiation. Although the toxicity of CO is understood, CO exposure can occur from unrecognized sources. On April 2, 2000, a couple and their newborn infant were poisoned by CO migrating through the ground from blasting at a nearby coal strip mine into their home near Kittanning, Armstrong County, PA. They were treated at the hospital and diagnosed with CO poisoning. The infant had a carboxyhemoglobin level of 31%, the father 28%, and the mother 17%. Carboxyhemoglobin is the compound formed in the blood when CO is breathed. Persons not exposed to CO have carboxyhemoglobin levels of 0.3%-0.7%, and cigarette smokers have levels of up to 9%. Following release from the hospital, the family installed a CO detector in the basement of their home with the help of the local fire department. This Technology News briefly describes this incident to help increase awareness of the problem. It is discussed in more detail by Eltschlager et al. [2001]. Figure 1 shows the coal strip mine believed to have generated the CO. The initial suspect for the source of the CO was the furnace in the house. Only later did it become apparent that blasting at the nearby strip mine might be the culprit. A State investigation concluded that CO had migrated approximately 500ft from the blast, through the ground, and into the home. Figure 2 shows the locations and order of blasts at the mine. Initially, the mine did not plan to blast. Overburden generally consisted of weathered shale that could be dug without blasting. However, the mine decided to blast when hard sandstone that could not be dug out was encountered within 3 ft of the coal top. The blasting was intended to break up the sandstone. Blasting was done using bulk ammonium nitrate-fuel oil (ANFO) in 6.25-in holes 25-30 ft deep on a 16-ft by 16-ft pattern, with charge weights ranging from 17 to 170 lb. The closest blast to the home was 430 ft on April 17, 2000. The distance from the home to the blast area on the day when CO was first reported (March 31, 2000) was 500 ft. Twenty blasts were detonated at the mine between March 7, 2000, and April 20,2000. The blaster was careful to prevent fly rock since another home was only 150 ft away and a garage was 50 ft away. The quantity of explosive used in the blasts was sufficient to break the sandstone, but was less than would normally be used to blast overburden. The holes were typically one-third explosive and two-thirds stemming, with powder factors averaging 0.43 lb/yd3. Additionally, the muck was not immediately excavated after each blast. The heavy confinement on the explosive acted to prevent the typical release of blasting fumes into the atmosphere. Instances of CO migrating from blasts into homes have occurred before, but generally the distances involved were under 150 ft. It is believed that the blast design contributed to the confinement of CO in the ground, and discontinuities in the ground strata facilitated migration toward the residence. Upon inspection of the blast pitwall, a regular system of joints was observed. These joints are oriented roughly from the blast pit toward the house (figures 3-4).Blast-generated CO appears to have been driven into the joint system, displacing the air. When the joint system was saturated, the next succeeding blast pushed the CO into an uncased well next to the house (a high level of CO has been measured in the well shortly after a blast). From there, the CO entered the French drain system and then the basement of the house. The joints are vertical cracks through rock layers that occur on a regular spacing (figure 3). They are most common near valley slopes and are caused when valley walls converge as the stream cuts down through the rock layers. Often called hill seams, they roughly parallel the valley walls, but can curve and split, creating a pathway for gas movement (figure 5). These fractures are often encountered when underground mining proceeds close to outcrop. The system of fractures at the Kittanning blast pit was well developed and provided a path for transmission of CO both through the sandstone and up and through the overlying shales. Blasting engineers should be able to distinguish naturally occurring fractures from blast fractures and note the frequency, development, and orientation of the hill seams and their proximity to occupied houses. The limits of transmission of

May 1, 2001

The primary purpose of the Institute is to advance those sciences embraced by it through interchange of knowledge This can best be done by the presentation and discussion of technical papers by its mem¬bers Short practical papers are especially welcome In any case the author should satisfy himself that his material is of a quality that will be a credit to him and to the Institute The preparation of a good paper frequently leads to a reorientation of the author's thoughts, which is extremely valuable, and pertinent dis¬cussion thereof contributes in no small way to the professional standing of the author Members are urged to submit papers presenting the results of their work Attention to the following suggestions will greatly further the prompt and efficient handling of manuscripts 1 Subjects: The subject must be within the field of the Institute Original work, the results of field, plant, laboratory or theoretical investigations, new views on old but important problems and occasion¬ally reviews of timely and important subjects of wide interest to our members may constitute the basis of a paper The mere fact that the work is original does not necessarily justify publication it must be of a substantial nature, of value to a reasonable number of our members and worthy of permanent record It is rarely desirable to subdivide the results of a single research for publication in a variety of journals Pre¬vious publication is a bar to acceptance 2 Construction : Papers should be clearly and concisely written in good English Care in this regard insures wider reading and the saving in space permits the Institute to publish more papers The terminology and units employed should be those current in the particular field An examination of Institute publications will afford useful guidance in such

Jan 1, 1937

By Dongjie Zhang, Shuxin Liu, Jianduo Wang

Broken rock mass and unreasonable stope structure parameters can cause excessive ore loss and dilution in sublevel caving; this is the main problem faced by caving mining in recent years. This paper proposes a stope structure parameter optimization method suitable for steeply inclined medium-thick broken ore bodies and evaluates the reliability and effectiveness through case studies. To solve the problem of large ore loss and dilution in the high-end wall sublevel caving method of Xilinhot fluorite mine, it is necessary to select proper stope structure parameters. Based on the theory of random media, an end-wall ore drawing experiment was carried out, and the bulk flow parameters needed to optimization of stope structure parameters were determined. In the experiment, it was found the draw-out body of high-end wall ore drawing showed a fine top and a thick bottom; the granular media had good fluidity. The reasonable caving step is determined to be 1.2 m instead of the 1.6 m originally used. Through the optimization experiment of the mining route position along the vein, the study found that the best route position is different with the ore body inclination. When the inclination angle of the ore body was 90°, the reasonable route was located in the center of the ore body. When the inclination angle of the ore body was between 85° and 90°, the route moved from the center of the ore body to the footwall at a rate of 22.5%. When the inclination angle of the ore body was between 80° and 85°, the route moved to the footwall at a rate of 54.8%. When the inclination angle of the ore body is not greater than 80°, the route should be arranged on the boundary of the footwall. Field application results showed the dilution rate reduced by 7.66% and the recovery rate increased by 7.31%. Field test results verify the effectiveness and applicability of the optimized stope structure, which corroborates the effectiveness and applicability of the optimized stope structure.

Mar 10, 2022

By Hojong Kim, Isehaq Al-Nafai, Kwadwo Osseo-Asare

The standard Gibbs free energy of formation (ΔGo f, 298) of bastnasite, (Ce, La, Nd, Pr)FCO3, was estimated using four different methods. The obtained average values were − 1589.5 kJ/mol for CeFCO3, − 1599.5 kJ/mol for LaFCO3, − 1589.1 kJ/mol for NdFCO3, and − 1595.4 kJ/mol for PrFCO3. The value for cerium bastnasite, CeFCO3, was used to construct a potential vs. pH (Eh-pH) diagram to investigate the stability relations of cerium bastnasite. The diagram shows that CeFCO3 is stable in neutral to basic conditions (pH ~ 6.5–11).

By Tom Snyder, John Brulia

PART 3 – UN Identifi cation Markings for the Highway Transportation in Commerce of Bulk Explosives, Oxidizers, and Combustible Liquids

Jan 1, 2015

By Nasib Al Habib, Hooman Askari-Nasab, EUGENE BEN-AWUAH

In-pit crushing and conveying (IPCC) is getting popular in deeper open pit mines as a suitable alternative to truck haulage because it offers a lower operating cost due to shorter haulage distance and less truck requirement. Semi-mobile in-pit crusher, currently the most popular IPCC system, is relocated every two to five years, and the short-term plan needs to be updated accordingly. To the best of our knowledge, short-term planning with IPCC is an area of research that has yet to be explored extensively, and hardly any model can generate a shortterm extraction sequence considering an IPCC. This research work proposes a mixed integer programming model to develop a short-term production plan within a time horizon of 12 months. The model's objective is to optimally allocate shovels to minimize the cost of material handling and maximize revenue subject to meeting plant requirements, maximum allowable tonnage variation and IPCC location constraints to achieve production and NPV targets set by the strategic plan. The proposed model will be implemented in an iron ore mine case study for verification. The model is developed and solved using MATLAB. The comparison of results between scenarios with and without IPCC justifies the use of IPCC in large open pit mines from a short-term perspective.

Jun 25, 2023

By AIME AIME

THAT the copper industry is in serious straits is admitted. So are the lead and zinc industries, and both lead and zinc are tariff protected. Conditions in the Western lead, zinc and silver mining districts are desperate. These are illustrated by the present disastrously low prices of these metals compared with the levels of two and three years ago and by the comparative rates of metal production and the present activity of the western mining camps. The January production of copper was 32.2 per cent of the 1929 average rate, of steel was 32.3 per cent of the 1929 average, while January production of pig iron was only 27.6 per cent of the monthly average of 1929. The copper industry is only one of many industries that are suffering in this tragic depression. It has been exceedingly prosperous and will be prosperous again when business recovers. Its difficulties are not unique and it does not deserve the tariff equivalent of a dole. The burden of subsidizing through an effective tax or tariff the minority group of high-cost mines would be a heavy one on the consuming public of the United States. On the basis of 1929 consumption figures, an effective 5c. tariff would result in an increased copper bill to the country of over $109,000,000, of which the electric manufacturers would contribute $26,000,000, the telephone and telegraph companies $16,000,000, and the automobile manufacturers $14,000,000. And of this total bill, only $33,000,000 would go to those who are urging a tariff and the balance of $76,000,000 would be paid to those who do not admit either its necessity or usefulness under present conditions.

Jan 1, 1932

By Nestor Torres-Acuña, Fathi Habashi

Metallic copper of purity equal to commercial electrolytic copper is deposited during the anodic dissolution of technically available white metal, Cu2S, in m acidic solution of' copper(II) sulfate as electrolyte and copper sheets as cathodes. The process may be applied on commercial scale since it has the advantage of by passing the converting and poling steps, decreasing pollution problems due to SO, and recovering the sulfur of the white metal in the elemental form. The anodic dissolution is believed to take place in three steps: The working conditions that lead to 98 pct cathodic current efficiency are: 30 gpl Cu2+ and 100 gpl H2SO4 in electrolyte, current density 1.0 amp per sq dm, and tetnperature of bath 40°C'. DURING the smelting of copper, nickel, lead, and zinc sulfide ores, large amounts of sulfur dioxide are produced. Because the release of this gas in the atmosphere causes pollution problems, many attempts were made in the past for its recovery either in liquified form or processed to sulfuric acid. Although these two forms of sulfur are the usual forms that are consumed by the chemical and metallurgical industries, their storage and transport usually raise economic problems. It was realized, long ago, that a process by which sulfur can be recovered directly in the elemental form would be most attractive. Elemental sulfur is easily stored and transported, and is readily converted to SO2, H2S, or H2SO4 when needed. Processes aimed to recover the metals from their sulfide ores, and at the same time by-product sulfur in the elemental form, were recently reviewed.' As early as 1882, Marchese2 patented a process in which a matte having the composition: Cu 15, Pb 14, Fe 41, and S 25 pct was electrolyzed. According to cohen3 the process was applied on a pilot scale by the Aktiengesellschaft fur Bergbau-, Blei-, und Zinkhiitten-betriebe at Stolberg, Rheinland, Germany. The process was unsuccessful, however, owing to the contamination of the electrolyte during electrolysis. Studies in this field were reported by Bernfeld4 and Egli.5 Borchers et a1.6-8 developed the process further by using white metal (Cu 78.2 pct, S 19.6 pct) instead of the matte, and a pilot plant was operated by the Mansfeldschen Kupferschiefer Co. at Eisleben, German~.~ It appears, however, that the process never went into commercial operation. Further studies in this direction were carried out by Russian workers.10-23 The International Nickel Co. of Canada erected a pilot plant at Port Colborne in 1951 to apply the process to nickel matte which is essentially pure nickel sulfide."'- 26 Full-scale plant went into operation at the Thompson Refinery in Manitoba in 1964.27 In this method nickel sulfide matte is melted and cast into anodes analyzing 76 pct Ni and 20 pct S with small amounts of copper, cobalt, and iron. These anodes are then electrolyzed in an aqueous solution of NiS04 at pH 4. Further work on this method was reported in the literature.28-31 In this paper, experiments on the anodic dissolution of white metal in aqueous copper sulfate solution are reported. EXPERIMENTAL White metal, Table I, obtained from The Anaconda Co., was cast in form of anodes 10 by 7.5 by 1 cm, Fig. 1. The anodes are mechanically strong and do not break easily; when polished they gave a shiny gray metallic appearance. From the chemical composition shown in Table I, it can be seen that the atomic ratio Cu:S corresponds approximately to the formula CU2.06S. The copper in excess to the formula Cu2S is most probably present as a separate phase since metallic copper could be seen under the microscope, Fig. 2. Fig. 3 shows the X-ray diffraction pattern of white metal which matches fairly well with that of reagent-grade Cu2S.

Jan 1, 1969

By Ezequiel Pomachagua Quijada

En el Perú, el cierre de yacimientos es una etapa nueva de la vida productiva minera, pues a partir del año 2005 la norma rige y se les otorga un plazo de un año para elaborar y lograr la aprobación del plan de cierre de todas las unidades mineras. Sin embargo, en el año 2008-2009 se iniciaron las actividades de rehabilitación en unidades mineras que no habían logrado su aprobación. En ese sentido, el presente artículo señala la experiencia sostenida por la empresa C.M Centauro como ejemplo de cierre progresivo en botaderos de desmonte. La restauración se inició con el botadero suroeste a través de tres etapas: cierre progresivo, cierre final y postcierre. Así también planificó el cierre de los componentes desde el diseño mediante actividades como la estabilidad física, remoción, perfilado y conformación de banquetas, estabillidad química, extendido de caliza, batido de caliza, compactado de sustrato estabilidad hidrológica, biológica y revegetación.

Aug 1, 2015

By C. Jay Hodgson, P. J. MacGeehan, T. Sanders

"The orebodies of the Campbell and Dickenson mines are localized within an anomalously fissile and deformed zone that transects the eastern margin of a dominantly mafic volcanic complex close to its contact with a synchronously formed sedimentary basin containing clastic and chemical sedimentary rocks. The ore zones are mainly quartz-carbonate fissure veins and siliceous replacement zones formed during deformation and metamorphism, although there are some syn-volcanic exhalative ore zones in the mines. On a regional scale, the volcanic rocks have been affected by syn-volcanic spilitic alteration which has involved the leaching of Fe, Mg, Au and As from, and the addition of Na and variable amounts of Si to bleached zones enveloping primary permeable structures in the rocks. The leached constituents were deposited on the contemporaneous sea floor as iron-rich chemical sedimentary rocks. Although this alteration is not closely related, spatially, to the ore zones, it is characteristic of the general environment, and may serve to distinguish gold-prospective from gold-barren areas on a mining-camp scale.Closely associated spatially with gold deposits is a zone of feldspar-destructive alteration within which the volcanic rocks are characteristically feldspar-free, enriched in As, Au and to a variable degree in Si, and depleted in Na, Ca and to a variable degree in Mg, Fe and K. The alteration zone is also characterized by abundant, variably transposed, small quartz-dolomite to ferrodolomite veinlets formed during deformation and metamorphism, and includes, but extends outside of, the anomalously fissile zone hosting the orebodies. The alteration zone is interpreted to have formed syn-volcanically within the upper part of a major submarine hydrothermal discharge zone."

Jan 1, 1982