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By José Vidalón

Dado que las lagunas de Papacocha y la Virreyna sufren los efectos de los drenajes ácidos de minas abandonadas, relaves y desmontes depositados en sus áreas de influencia, se ha previsto el control de los mismos. En este sentido, el presente texto evalúa los pasivos y propone soluciones dirigidas al control del drenaje ácido contaminado con metales disueltos, priorizando los métodos que no requieren la construcción y operación de una planta ni supervisión permanente.

Sep 13, 2001

By Sutham Niyomwas

The Fe-TiC composite powder was synthesized in situ by carbothermal reduction of ilmenite. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the reacting species. The effects of the reaction temperature (1300 °C - 1500°C) and milling time of precursors on the Fe-TiC conversion and powder morphologies were investigated using XRD and SEM method. The synthesized products showed that composite with iron matrix and titanium carbide as a reinforced phase was formed.

Jan 1, 2006

The ultraviolet spectrum of isopropyl ethylthionocarbamate (the principal constituent of Dow flotation collector Z-200) in water and of Z-200 itself in water was found to have an absorption peak at 242 nanometers(nm). The height of this peak was found to be directly proportional to isopropyl ethylthionocarbamate concentrations up to 15 p.p.m. Z-200 contains about 90 per cent isopropyl ethylthionocarbamate and the heightof the peak was proportionately lower, but obeyed the straight line relationship up to 15 p.p.m. This showed the potential value of spectrophotometric measurements for the determination of Z-200 residuals in flotation liquors.Methyl ethyldithiocarbamate (an impurity in Z-200) increased the peak height slightly, but other impurities in Z-200, xanthates, and most inorganic salts present in flotation liquors do not interfere. However nitrate ion and thiosulphate ion have absorption peaks which overlap the isopropyl ethylthionocarbamate peak.The simplest general method to overcome this effect is to extract the isopropyl ethylthionocarbamate into cyclohexane and to measure the absorbance of the extract.The maximum absorbance of the cydohexane extract was at 247 nm and the peak height at this wavelength was found to be directly proportional to the isopropyl ethylthionocarbamate or Z-200 concentration in the original aqueous solution. An alternative method is to measure the spectrum of the original aqueous solution using the aqueous raffinate from extraction as a reference solution. This gives the spectrum due to isopropyl ethylthionocarbamate alone and measurement of the absorbance at 242 nm gives the concentration in the original aqueous solution. Both methods give the same value for the concentration of isopropyl ethylthionocarbamate in the original solution.

Jan 1, 1969

By A. Lyndon

Combined loading tests are described to three 1.2m diameter cast-in-place bored piles, 12m long, formed through cohesionless material into stiff sandy clay. The maximum loading conditions imposed at the pile head were 2400 kN vertical, 160 kN lateral and 3120 kNm in bending, corresponding to twice the working load. Settlements, deflections and rotations of the piles were measured during the tests. An interesting finding which the test results suggest is that, in the short term, vertical movement had apparently no marked effect on lateral performance for piles working at design loadings.

Jan 1, 1989

By Phillip E. Butler

Since early 1973, the Pennsylvania Department of Transportation (PennDOT) has been actively engaged in the utilization of coal mine refuse in the design and construction of highway embankments. The Soils and Geological Engineering Division of the Bureau of Materials, Testing and Research has the task of managing the program which includes field investigations, laboratory testing, engineering evaluation, planning, coordination, implementation, construction control, and review of construction performance. The objectives of the utilization program, in removing colliery refuse banks and utilizing the material in construction, are the environmental and aesthetic rehabilitation of those areas in the Anthracite and Bituminous coal fields which have been plagued for such a long time by air and water pollution, and unsightly landscapes; and the economic rehabilitation of those areas occupied by refuse banks by providing usable land which can now be developed as residential, business, or industrial sites.

Jan 1, 1975

By Robin B. Dill, Mark Pelletier, Daniel J. Dobbels, Subodh Bhaumik, Daniel J. VanRoosendaal

Although primarily cut-and-cover excavations are required for replacement of the existing elevated I-93 interstate highway through the heart of Boston for the Central Artery/Tunnel (CA/T) project, some mined tunnel construction was also undertaken. The mined tunneling conducted was the 22-m-wide northbound roadway structure which passed below a 20-m-deep operating underground subway station that was built in 1913. The innovative underpinning scheme used to support the subway station during construction resulted in the successful mining beneath the subway station with negligible vertical settlement. Two grouting galleries were carefully mined below the subway structure, and pre-grouting of the granulary, pervious glacial soils and weathered bedrock was carried out from these galleries. The reinforced concrete walls of the underpinning structure were constructed within three stacked drifts that were sequentially mined below each grouting gallery. After 11 cross adits were mined between the grouting galleries, cast-in-place post-tensioned girders that spanned between the stacked-drift walls were constructed to support the subway station. The stacked-drift walls also provided lateral support for the 22-m wide by 29-m long by13-m high opening beneath the girders.

Jan 1, 2001

Low displacement fault zones often comprise a mesh of interlinked faults, extensional-shear and purely extensional vein fractures. Hydrothermal mineralisation localised around such structures testifies to their importance as conduits for fluid flow. Mesh structures are most commonly developed in situations approximating bulk pure shear but predominantly simple shear meshes also occur. They appear to develop through the infiltration of pressurised fluids into a heterogeneous rock mass with varying material properties. In some circumstances, mesh formation appears to be a precursor to the development of major through going faults. Mesh formation generally involves hydrofracturing (Pf > s3, at least locally) and the condition Pf ~ s3 to be maintained for the mesh to remain a high permeability conduit, requiring fluid over pressuring at other than shallow depths in extensional-transtensional regimes. The volumetric character of earthquake swarm activity appears to result from the passage of hydrothermal fluids through mesh structures, representing a form of distributed fault-valve action along suprahydrostatic hydraulic gradients arising from magmatic intrusion, compaction overpressuring, metamorphic dewatering, etc. Fluid redistribution in the crust is influenced by maximum hydraulic gradient (not necessarily vertical), by existing permeability anisotropy arising from bedding and other forms of crustal layering, and by structural permeability developed under the prevailing stress field. Strong directional permeability develops in the s2 direction, parallel to fault-fracture intersections within the mesh and orthogonal to fault slip vectors. In particular tectonic settings, stress-controlled permeability allows strongly focused flow through fault-fracture meshes with high potential for mineralisation. Favoured localities for mesh development include short-lived link structures along large-displacement fault zones such as dilational jogs, lateral ramps, and transfer faults.

Jan 1, 1995

By Claude MacDonald, John H. Ashburn

"IntroductionIndustrial growth and technological change over recent years had been accompanied by two major sources of concern to management and employees: (a) increase in occupational injury and illness and the resultant costs involved; and (b) equipment damage and breakdowns in concentrated production lines causing more extensive loss potential.Due to economic factors, management attention has focussed more on production and quality than on safety, health and related loss potential sources. As a result , occupational safety and health activism has grown, government legislation of compensation and occupational safety and health standards have progressively developed and stronger liability attitudes have been taken by courts of law.To improve efficiency and allow development in more competitive markets, rising labour costs, equipment costs and safety related financial losses have dictated that attention be given to conservation of all resources. Conservation of resources, people, equipment, material and environment, can no longer be addressed in isolation but must be managed integrally with production and quality. To this end, systems have developed utilizing sound management principles applied with equal intensity to production, quality and loss potential"

Jan 1, 1987

By R. Dahlke, J. A. Finch

"A campaign was undertaken during the greater part of 2001 at Noranda’s Brunswick Mine Concentrator to investigate the role of gas (air) superficial rate distribution (Jg profile) to the cells in the final Zn cleaning stage (bank of seven cells). Three profiles were tested: Balanced (each cell with same Jg), Increasing (from cell 1 to 7), and Decreasing, along with an “as found” profile in a parallel control bank. The experimental design allowed for two confounding factors, changes in ore type and circulating load. The Increasing profile consistently gave the best metallurgy (down-the-bank grade / recovery). The reason for improved performance was traced to the response of the first few cells. The Increasing profile gave the highest selectivity of sphalerite against non-sulphide gangue (NSG) in these cells with relatively even recovery per cell down the bank (10-15% based on feed to each cell). The other profiles gave lower selectivity and higher zinc recovery in the first cells (up to 25% in cell 1), which combined to reduce overall bank performance. The increased selectivity with the Increasing profile is attributed to the low gas rate in the first cells reducing water recovery and hence limiting entrainment of NSG gangue. The Increasing profile was subsequently configured for all four stages in the zinc cleaner circuit.INTRODUCTIONThe performance of a flotation circuit is largely the result of the operator’s response to visual clues. This includes manipulation of the gas (air) input and how it is distributed to cells in a bank. A lack of sensors prescribes this approach. Over the past ten years the Mineral Processing Group at McGill University have developed a set of gas dispersion sensors including one to measure gas superficial rate (or simply “gas rate”), i.e., volumetric gas rate per unit cell crosssectional area, Jg (Gomez and Finch, 2002). The device collects bubbles in a tube immersed in the pulp and infers Jg from the pressure-time curve generated after a valve is closed and air starts to accumulate. The usual units are cm/s. It is robust, reliable and suited for plant use.A version of the Jg sensor was tested extensively during 2000 at Noranda’s Brunswick Mine Concentrator (Dahlke et al., 2001). The results were sufficiently encouraging that a sensor was fabricated to suit local requirements (Insta-Jg). The sensor detected malfunctioning field instruments and flotation mechanisms, and demonstrated that gas distribution to cells in a bank “as found” had no particular pattern, or profile. Preliminary testing suggested that a balanced profile (i.e., all cells with the same gas rate) gave superior metallurgy (grade / recovery down the bank) than the “as found” profile. This observation prompted a focused campaign to explore the impact of the gas rate (Jg) profile, introducing the notion of “gas distribution management”."

Jan 1, 2004

Large deposits of manganiferous iron ores, representing several million tons of metallic manganese, occur in the United States. The Minnesota deposits of such ore are of outstanding importance because of their size, state of development, ease of mining and proximity to the Great Lakes, which permits water transportation to steel centers. In view of the fact that our steel industry requires large quantities of manganese, for which no satisfactory substitute has been found, and because our reserves of ferro-grade ore are comparatively small, the development of methods that will make our large deposits of manganiferous iron ores available as a source of ferromanganese is an important problem. Realizing the importance of this problem, some years ago the North Central Station of the U. S. Bureau of Mines and the Minnesota School of Mines Experiment Station undertook jointly the development of methods for recovering the .manganese content of manganiferous iron ores in a form suitable for the production of ferromanganese, the 80 per cent. alloy indispensable in producing steel. Two types of manganiferous iron ores have been described in previous reports.' The brown ores are higher in iron and lower in manganese than the black ores; the black ores are more siliceous but contain less phosphorus. The utilization of the iron content of the brown ores in the production of steel appears to furnish the best basis for their treatment. The method of attack has been to work out modifications in iron and steel practice so as to recover manganese in the form of slag comparable to ferro-grade ores. The greater part of the experimental work has been conducted with a 6-ton blast furnace and a 1/2-ton basic open hearth. This paper is devoted mainly to open-hearth tests in which high-phosphorus spiegel

Jan 1, 1930

Operations of the new copper smelter at Mount Isa commenced on the 6th February, 1953. Prior to this date a paper by R. V. Anderson (1953) outlined the smelter layout, proposed operation and expected performance.Nominally a 50-ton per day plant, output is currently at the rate of 85 long tons per day. In the first 3t years, of operation to 30th June, 1956, '71,339 tons of blister copper were produced. Operation has been stabilized' and a number of modifications to plant and operation have been made. This paper reviews the progress made to date.GENERAL LAYOUT AND EQUIPMENTThe general layout and equipment follows well-established practice as study of Figs. 1 to 4, and Appendix II will show. This diagrammatic representation of layout (Fig. 1) and flow sheet (Fig. 2) is intended for the purpose of brevity to take the place of a detailed plant description.Choice of site for the smelter was limited by the necessity for close proximity of the waste heat boilers to the powerhouse.Much excavation was necessary before foundation work commenced, but the plant is compact and further expansion is possible.CHARGE MAKE-UPRoaster charge initially comprised concentrates, purchased ores, revert materials, mine sulphide ore and barren sand. As purchased ore receipts increased and as domestic black rock oxidized ore became available, the latter two fluxes were eliminated from the charge. Fluxes at minus i-in. sizing are trucked from crushing plant or stockpile by motor lorries. Filtered mill concentrates are dropped from an overhead conveyor on to the storage patio floor adj acent to the two concentrate bins.

Jan 1, 1957

By D. F. O?Connor

The health & safety of all workers in an underground environment is paramount to the success of our operations. The diesel emission reduction projects are key to improving such an environment. However, care must be taken to reduce the risk to personnel during such tests and prevent exposure to other hazards. VALE Inco works in a close partnership with its unionized employees, manufactures, suppliers, researchers and government officials to ensure projects are done safely and efficiently to successful completion. The Creighton Mine Diesel Particulate Filter (DPF) project is an example of such a project that is currently under way to evaluate new and innovative technology that will further our search for improved environment for our workplace. This paper will discuss the issues and processes that are followed to ensure Diesel Particulate Filter (DPF) field tests are conducted safely and productively.

Jan 1, 2009

By Floyd D. Varley, C. M. K. Boldt

Toolbox training is often described as short, informal training conducted at a worksite by technically competent persons for the benefit of a work team. The key feature of toolbox training is the focus on a work team and what is important to that group in its workplace. Toolbox training conducted by peers can connect miners and establish the feeling that the hazard is a real threat to them. This feeling can bridge the gap between delivery of a safety message and behavioral changes that can prevent an accident. Toolbox training is a popular form of "maintenance" training that should not be used to teach a new skill. The 10- or 15-minute toolbox session is simply too short a time to teach or learn a new skill and test for skill development. However, the toolbox format is an excellent way to inform workers of changes in workplace rules, conditions, or hazards by bringing the discussion of change to the level of the work group and suggesting how a change will affect the way workers perform their jobs. Toolbox training should be structured to address a very specific hazard. That is, the hazard source should be identified and the effect of the hazard on the worker described. The temptation to discuss a safety subject in broad terms will result in an equally vague result. For instance, discussing "equipment guards" is inappropriate for a 15-minute training session. There simply is not enough time to cover all the hazards and their remedies. A more appropriate topic would be "placing guards on a conveyor return roller" or "hazards of cleaning a conveyor return roller." Each topic is concise enough to allow the trainer time to define a particular threat to the safety of miners and discuss ways to defend against that threat. The clearest way to a safe workplace is to identify hazards methodically and eliminate them. This cannot be done with sweeping, generalized training. Some best practices that will protect a worker from the hazard should be presented, and the hazard should be located at the specific worksite. Toolbox training is an opportunity for the work team to participate in learning and share experiences and knowledge, often through storytelling. Storytelling is an ancient form of passing along information in an entertaining way. It is entertaining because it draws the listener in with imagination and creativity. Stories told within work groups are a way for miners to exchange experiences in which they made mistakes that resulted in an accident or a near-miss and learned a valuable lesson. Thus, co-workers can learn from others without the pain or fear that accompanied the storyteller's learning path. To encourage these shared experiences, the people in the group must be comfortable with one another. Participation doesn't stop with listening to a near-miss story or informing the group of an unsafe work practice. Participation by sharing experiences, knowledge, and skills should lead toward action in changing the unsafe tool, practice, or machine (Wallerstein, 1992). This power to change is called empowerment. Empowered workers use toolbox training sessions to discuss a problem; direct their own knowledge, experience, and talents in the context of their work environment to solve the problem; and put into practice what they have learned by sharing (Baker, 1992). A worker is much more likely to implement changes they have contributed to creating than changes forced upon them. Toolbox training functions best when the group size is small (under 20) and composed of workers with similar job functions. While combining all workers on a shift or multiple shifts may be convenient, the level of participation will drop dramatically as group size increases and participants are less connected. Similarly, when the work group participants are from different job functions, keeping the materials relevant to the individual becomes more difficult. The role of management in the toolbox training system is to communicate among various groups so that all groups at a mine site are hearing the same message. In very small operations, combining work groups can be productive if the trainer can promote open discussions and lead the group to solutions that address the needs of all and not let one group or individual dominate the discussion. WHY USE NARRATIVE METHODS An effective communications tool is to use stories as a means of describing a hazard and its consequences. Historically, using stories to transfer knowledge between individuals of the same and different generations is well established. All good stories share the same elements required to communicate safety principles. Stories require a setting (the part of the workplace), a plot (the circumstances that lead to a hazard), the solution (best practices), the lesson (what can happen), and the result (what will be done to prevent the hazard) (Dennehy, 1999).

Jan 1, 2002

Calculations of the temperatures of metal, coke, and gas at any level in the cupola furn~ce can be carried out by means of heat balances, using data obtained from experiments with an 18 in. experimental cupola. The results can, to a certain extent, be verified by means of heat transfer calculations.The curves thus obtained, showing the variation of temperature with height in the cupola, provide a valuable picture of the heat transfer processes in a shaft 'furnace.INTRODUCTIONThe Brown Coal Research Laboratory, of the University of Melbourne, has been engaged in recent years on a programme of iron-melting tests in an experimental cupola furnace.Although the ultimate aim of this work is to develop brown coal char as a cupola fuel, most of the experimental work so far has been with conventional coke. The testing programme was designed to provide information on the effect of variables such as blast rate, metal-coke ratio, and coke size on the overall melting process, e.g. melting rate, temperature of metal tapped, and stack gas composition.However, in many cases data were obtained on conditions inside the furnace by measuring temperatures and gas compositions. The aim of the work described in this paper was to qevelop a method for using this data to obtain information on the processes taking place in the cupola.Very little research has been done on the combustion of fuels in shaft furnaces. Early work on this subject, as well as the initial stages of the Brown Coal Research Laboratory's programme, has been discussed by Evans (1959). The use of probes for obtaining information on conditions in the interior of a shaft furnace was pioneered by Belden (1913)...

Jan 1, 1963

By Richard Morland

Some simple and fundamental objectives To challenge and inspire our people to embrace safety as a value ?A stand for safety as a value ?A stand for our people ?A stand by our people ?Prevent harm to our people ?Eliminate suffering for individuals, families, friends, colleagues

May 1, 2010

By Paul H. Madsen, Victor S. Romero

The Tren Urbano project in Puerto Rico includes a 19 m diameter tunnel constructed by the stacked drift method, which involves installation of a pre-supported concrete arch using multiple tunnels. Geotechnical conditions consisted of weak rock and highly weathered, unstable alluvial soils. Due to low cover, reinforcement of the arch was required. Ground behavior ranged from firm ground to mixed-face to raveling and flowing ground. Consequently, construction of the individual drifts involved many different soft-ground techniques such as steel set supports, shotcrete support, shield tunneling, forepoling, and consolidation grouting. During construction, the design was modified to improve constructability. Although settlement was experienced during excavation of the drifts, arch movements were within predicted limits and minimal surface settlement was observed upon excavation of the interior.

Jan 1, 2001

By Dennis R. Dolinar

Controlling coal mine roofs subjected to high-horizontal stress conditions has always been difficult and uncertain. Traditional supports such as wooden cribs and posts, concrete donut cribs, and standing supports collapse and fail when the roof and floor move horizontally as mining progresses. The former U.S. Bureau of Mines (USBM) (currently the U.S. Department of Energy (DOE)), in cooperation with Western Fuels-Utah, Incorporated, conducted research to provide an alternative for traditional secondary support systems in a 3-entry gate road system subjected to high horizontal movements. The support system used in several other coal mine operations, consisted of internal high-strength galvanized resin-grouted cable supports. The system virtually eliminates the necessity for external crib, timber, or concrete supports. The support system consisted of 2.4 m (8 ft) full-column resin grouted bolts and 4.8 m (16 ft) long cable supports installed in conjunction with wire mesh and "Monster-Mats." Cable loading and roof deformations were monitored to evaluate the behavior of the immediate and main roofs during first and second panel extractions. Additionally, cable trusses were installed on the longwall headgate to protect the coal conveyance system from roof and pillar falls created by the formation of cutters and gutters. The test results indicated that the designed support system successfully maintained the roof during the extraction of two longwall panels and dramatically reduced the cost of secondary support. This paper describes the theory of high-horizontal roof movements, the advantages of vertical cable supports and cable trusses, and presents the roof and cable measurements made to assess the support performance during longwall retreat mining.

Jan 1, 1996

The Australian metallurgical processing industry has shown great innovation and progressiveness over the past ten years. During the same period, exploration activity, particularly by Australian companies, has increased substantially in Indonesia. Following feasibility studies, the decision was made to establish a metallurgical laboratory and design facility in Indonesia. An Indonesian partner was selected, and legal and corporate matters were determined. The laboratory was established but proved far more difficult than a similar undertaking in Australia. Australian and Indonesian staff were recruited and training programs, including training of Indonesian staff in Australia, were implemented. Difficulties of operating in Indonesia included: ò language difficulties ò _ local pace of life ò culture ò communications. Rewards of the decision to establish the means to present the technology to Indonesia have included: ò a contribution to Australia's export of technology. ò an opportunity to expand Normet's client base. ò the opportunity to learn aspects of a foreign culture. ò the means to establish a sound long term investment. This export of technology from the Australian mining industry to Indonesia is an example of the initiatives and capabilities shown by the Australian mining service industry.

Jan 1, 1989

By A. George Stern

In the examination of bentonitic clay suspensions used for oil-well drilling fluids3/ (and for other purposes, such as a core binder for foundry sand) it is important to have comparative tests for evaluating them. A satisfactory clay for these and other purposes should 'rave the property of forming what is commonly called a "gel," but the measurement of this property has been a real problem. To date the solution has not been satisfactory, and some of the difficulties are considered in, this, paper, which describes a simple form of instrument (identified as an eykometer) for measuring the yield point under hydrostatic conditions of non-Newtonian clay suspensions, including those muds that are thixotropic. An oil-well drilling mud serves several functions, many of which depend on the "gel" characteristics of the mud. Among the more important functions are: (a) To plaster the sides of the hole to prevent caving of the walls; (b) to prevent the loss of the circulating fluid out of the hole by seepage; (c) to carry sand and cuttings out of the hole to the surface as they are formed by the rotary drill; and (d) when circulation of the fluid stops for shut-down or other unavoidable cause, to hold the cuttings in suspension by the setting up of the gel, thereby avoiding the difficulties that result when these cuttings are allowed to fall through the fluid and pack at the bottom of the hole.

Jan 1, 1940

By S. J. Lötter

Analysis of the major and minor components of raw zircon as well as plasma-dissociated zircon was undertaken using inductively coupled plasma optical emission spectroscopy (ICP-OES). Microwave-assisted acid extraction as well as flux fusion using lithium tetraborate were investigated as digestion methods. Microwave-assisted acid extraction samples were analysed with matrix-matched standards. The most successful microwave-assisted acid extractions yielded 44.3(1), 49.75(7), 78.3(3) and 90.0(7) per cent recovery for Zr, Hf, Al, and Fe respectively using sulphuric acid. In no instance was acid extraction capable of complete digestion of the sample matrix. A standard addition method was applied to the flux-fusion samples due to the high complexity of the sample matrix. Method validation for the flux fusion procedure was performed using the SARM 62 certified reference material (CRM) with acceptable recovery ranges being based on the 95 per cent confidence intervals of the CRM. Successful analyses were achieved for Zr, Hf, and Ti with apparent content of 66(6), 1.7(1) and 0.15(1) per cent respectively.

Jan 1, 2012