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By Tan Zhenxiang

INTRODUCTION Koolyanobbing is an open cut iron ore mine, which is located in Yilgarn region of Western Australia. To prevent the operators from suffering silicosis diseases and protect the air from being polluted, a series of dust control measures have been taken. These measures include ventilation and dust control system for sample preparation shed, dust collecting system for drill rig, dust suppression system for ore processing plant, dust control for haul road. The details related to individual dust control measure are dealt as follows. SAMPLE PREPARATION SHED DUST CONTROL The sample preparation is one of the major dust sources at Koolyanobbing. The activity is being carried out at the sample preparation shed. It typically needs to go through the following stages, that is, crushing, splitting, drying and pulverising. The amount of dust generated from crushing and splitting is mainly determined by the moisture content contained in the pre- pared sample. A significant amount of dust is generated at the sample pulverising stage due to cleaning sample bowl with com- pressed air. To protect the sample preparing personnel's health and make the dust level in the air meet the requirement from the health and safety authority, a central ventilation and dust control system has been installed at the sample preparation shed. As shown in Fig. l, the system consists of suction heads, suction lines, dust collector and vacuum fan. The fan creates vacuum environment in the system, therefore the dust is drawn into the dust collector through the suction heads and suction lines. The dust collector is of fabric filter. When the dusty air comes to the filter, the dust in the air is collected and retained on the surface of the filter while the clean air passes through and enters the atmosphere. The retained dust is blowed out by the pressured air pulses and deposits into the dust bin underneath the filter. A time relay device is used to control the cleaning time and the cleaning interval. DRILL RIG DUST CONTROL A hydraulic percussion drill is used to drill blast holes. To carry out the drilling operation properly and efficiently, the cut- tings are being flushed out of the hole by the compressed air. In order to prevent from the fine particles in the cuttings escaping to the air, a dust collector is attached to the drill. The collector mainly consists of suction head, cyclone and bag filter. Refer to Fig. 2. The suction head is installed at the lower end of the feed beams and is movable. The moving range is up to 250 mm. It is not only used to restrict the cuttings, but also used to prevent water from entering the filters when drilling wet hole. A 406 mm diameter primary cyclone is used to separate the heaviest particles in the cuttings. It is also used as blast holes sampling equipment. One part of the dust particles are collected by a sample bag through a splitter attached to the end of the cy- clone. The rest of the particles fall down to the ground through the closing rubber. The bag filter is driven by a hydraulic motor (1). It is used to collect the lighter particles in the cuttings. The filtering area is 16 m2 and the dust separation efficiency is up to 99.9%. The working principle of the filter is demonstrated in Fig. 3. When the rock drill (9) flushing is turned on, the pressurised air from the compressor is directed to the rock drill and to the pres- sure switch (10). The pressured air will open the pressure switch to de-energise and close the solenoid valve (4) The pressure affecting the cut-off cylinder (5) keeps the exhaust port flap open. When the flushing valve (8) is closed, the pressure affecting the cut-off cylinder disappears and the internal intake opening flap is closed by a spring. The pressure also ceases to affect the pressure switch and the spring switches the contact to the point 2. The time relay (11) is now activated and gives a 0.5 second current impulse to the solenoid valve and keeps the current cut off for approx 8 seconds. When the solenoid valve is live, it opens and lets an impulse of pressured air to the filters (2). These impulses will clean the filters.

Jan 1, 1997

By Graham A. Mathieson

The precise definition of an ultimate or economic pit has, over the years, received much attention in the literature on the subject of mine planning. Unfortunately, relatively little has been published in the area of pit sequencing and scheduling--an aspect which is typically of much greater economic significance both during the life of a mining operation, as well as in the evaluation of an exploration project. This paper discusses an overall mine planning methodology with emphasis on the design of an optimal sequence of pit expansions or phases. Although the concepts given are not new, it is hoped that some practical suggestions will be made. The paper will also describe graphical techniques which have been found useful in comparing the merits and impacts of alternate planning strategies and production schedules.

Jan 1, 1982

By Richard Keith Corbin

INTRODUCTION The purpose of this paper is to assist explorationists and entrepreneurs in deciding whether to invest in gold mining concessions in lesser developed countries (LDCs) and, if so, in deciding which LDCs provide the best opportunity. The first decision is difficult in the face of common notions that foreigners are not welcome - only their money; that the best gold deposits were worked out long ago; that even if you survive the mal- aria, and in spite of 51% control by a national partner, you manage to profit from a new discovery, they will tax your operation to death, or worse yet, nationalize it. Close scrutiny of what happened to foreign investors in LDCs during the “Mexicanizationt” of the 1930's through the "Zambianization" of the 1970's shows that many of these concerns are well-founded historically. But the trend of knowledgeable writers over the past decade seems to be away from this gloomy foreboding, and towards a cautious optimism, based on recently perceptible metamorphoses in certain LDCs' conditions and attitudes. If the explorationist or entrepreneur decides to seize on this apparent opportunity, the second decision -- which of these certain LDCs to invest in -- is doubly difficult, because of the formidable tasks of coming up with a rating system to provide rational comparison, and then gathering enough current, reliable information to apply. To assist in these tasks, a suggested rating system and case studies, respectively, follow a brief review of recent writings on the subject

Jan 1, 1987

By Håkan Stille, Jalaeddin Y. Rafi, Fredrik Johansson

"INTRODUCTIONIn tunneling projects, pre-grouting is performed with the purpose of establishing an impervious zone around the tunnel periphery. This is obtained by reducing the penetrability of the most conductive fractures in the rock mass. The main attention, besides economy of the project, is given to limiting the ingress of water into the tunnel to a certain amount during construction s well as operation period. Failure in pre-grouting process may, according to Bruce (2007), significantly affect the project in terms of safety, performance, cost and time. In this respect, determination of design parameters (pumping pressure, properties of the mix and stop criteria) affects these projects significantly. In current practices, depends on the geological conditions and requirements of the project these parameters differ widely. Weaver (1991) recommends selection of design parameters, specifically grout injection pressures, based on site specific factors and the conditions at each specific hole into which grout is to be injected (grout hole logging and water pressure test data). Houlsby (1990) correlated the allowable grouting pressure to the quality of the rock mass and the rock cover above the grouted fracture. In his methodology, grouting should be continued until the maximum pressure was attained. Later, Lombardi and Deere (1993) introduced the Grout Intensity Number (GIN), which limits the combination of injection pressure and injected grout volume in order to control the energy induced in the fracture i.e. avoid fracture jacking. Even though the GIN method was a step forward in understanding of the mechanism of the fracture deformation, there are ambiguities connected to this methodology, thus determination of the intensity number is challenging (see e.g., Rafi and Stille 2015)a.A main problem when no theoretical solution is practiced is that effects from the chosen injection pressure, such as possible increases of transmissivity and changes in total grouting time, remains hidden in the overall grouting process. The question is if a high or a low pressure should be used to fulfil the requirements of the projects at the lowest possible cost."

Jan 1, 2016

By Pierre J. Wauters, Eddy J. Jacques

Starting up a fan or modifying its setting point either by rotational speed variations or blade angle changes, obviously results in new ventilation conditions in the network, which is, of course, the object of the operation. However, since transient phenomena may then occur, particularly in complex networks, there may be a need to simulate these situations prior to any action. This is all the more true, if we are dealing with a multiple interactive fan sys- tem. Simulations with a transient model have shown that the flow in certain airways could be temporarily reversed due to the pres- sure variations that reach both its ends with a different time lag. This phenomenon may cause dangerous situations to occur in cases of fire or outburst of methane. It is also true that the air flow could be reversed in secondary and less powerful fans, while still rotating in the normal direction. The study and the experimental investigation of the extension of the reverse flow characteristic is therefore justified from two points of view : • a numerical simulation model for transient flow conditions must be capable of handling temporary reversed flows, and thus have appropriate fan characteristic curves available over the entire operating domain; • while operating fans, reversed flows should be avoided or at least reduced. Therefore, the design of start-up procedures or real time control algorithms should take these phenomena into account. A particular interesting application is the operating of two fans in parallel. In order to investigate experimentally the characteristic curves of a fan under reversed flow conditions a small scale model was built. This facility was designed in such a manner that it was possible to carry out experiments concerning flow reversions and to try out sequential start-up procedures for two fans in parallel.

Jan 1, 1997

By Dennis K. Mortensen

Improvements in flotation technology are continually being made in the attempt to achieve the mineral processor's goal of maximum mineral concentrate grade and recovery at zero cost. Technology that cannot be totally proven in the laboratory must be tested under plant conditions either in a pilot plant or in the existing circuit. Problems associated with new technology can be solved effectively by the mineral processor who approaches each of the problems objectively.

Jan 1, 1989

By R. D. Schmidt

An in situ leaching geochemical simulator consisting of flow, mass transport, and graphics support programs has been developed. Two dimensional flow in heterogeneous porous media is modeled using a semi-analytic boundary integral technique. This method involves mapping streamlines to straight line segments in the complex potential plane. Leachant concentration and mineral values are modeled in this plane using the (one dimensional) potential coordinates. A fully implicit finite difference scheme is used to solve the resulting coupled system of four concentration equations. Graphical representations of streamline patterns, concentration histories, profiles and recovery curves are generated. An application of the model to uranium leaching in a heterogeneous aquifer and ore zone setting is presented.

Jan 1, 1985

By A. Dadgar, R. H. Sergent

Changes in the ore types available and increased environmental concern have created a demand for an alternative technology to cyanide for the extraction of gold from ore. Great Lakes Chemical Corporation (Great Lakes) believes that halogen chemistry, in particular bromine chemistry, is the best available alternative to cyanide for gold extraction. Great Lakes is a Fortune 500 chemical company with sales of approximately one billion dollars per year. Great Lakes extracts elemental bromine from naturally occurring brines in Southern Arkansas. Great Lakes has developed a family of proprietary bromine compounds to aid in the extraction of gold. In addition to proprietary bromine compounds for gold extraction, Great Lakes has developed a method of recycling bromide ion in the leach circuit. Various recovery methods, including ion exchange and solvent , extraction are currently being studied.

Jan 1, 1990

By R. E. Weeks, D. J. Millenacker

Utilization of true in situ technologies for mining copper in Arizona will involve a complex environmental permitting process. This process is a key factor in determining the feasibility, costs, and implementing time- frames required for development of this innovative mining method. The regulatory structure in Arizona is presently changing due to enactment of the Environmental Quality Act (EQA) of 1986 and development of new aquifer protection rules and regulations. The US Bureau of Mines has reviewed the comprehensive hydrogeologic characterization, ground water monitoring, mechanical integrity testing, well construction, contingency planning, and other regulatory elements that will serve as mechanisms to assure protection of ground water resources. The purpose of this paper is to inform the domestic copper industry of the significance of the new Arizona regulatory structure and its implications for prospective in situ operators.

Jan 1, 1987

By Y. Topkaya, R. E. Johnson, B. R. Palmer, R. B. Bhappu, J. Brent Hiskey, Gürses Öner

Currently there is considerable interest in applying in situ leaching technology to recover copper from oxide ores. In many instances, the distribution of copper mineralization in these deposits is fracture controlled. Laboratory core-leaching experiments have demonstrated that leaching response is sensitive to the dissolution of copper from and the formation of channels along main fractures. Solution short- circuiting can be a major limitation of this technology. This paper describes the application of macromolecular polymers to achieve flow-profile control during leaching. Pre- and post-leached fractures were characterized by computerized tomography (CT) analysis.

Jan 1, 1993

By James E. Monsees, Wayne A. Carbiener, Michael R. Wigley

This paper illustrates an approach to quantitatively document the degree of technical conservatism to be incorporated into the design of a waste isolation system in bedded salt. It is anticipated that for an actual repository site the key performance constraints and/or design bases identified in this paper will be reviewed, and modified or supplemented as required. Ultimate acceptance of a repository will be dependent upon scientific peer input and scrutiny of the demonstrated conservatism inherent in each specific repository site and design.

Jan 1, 1981

By D. Rajkovic

Geothermal sources are exploited in two basic forms, i.e., the primary form of thermal energy and that converted into electrical energy by using an adequate thermodynamic cycle. There is a possibility of applying several processes for the conversion of thermal into mechanical or electrical energy, which depend on the thermodynamic characteristics of the geothermal water. Geothermal sources in Croatia do not contain steam of relatively high temperature, like in Italy, although both countries are nearly in the same position with respect to geothermal belt. Geothermal sources in Croatia are mostly so-called low-temperature geothermal sources with water temperatures lower than 100°C (Cubric and Jelic, 1993). A few of them have been exploited, although the percentage of utilization of their available power is still very small. The low-temperature potential is a major disadvantage when it comes to power generation, since state-of-the-art geothermal power plants require reheated steam or hot water to operate. There is a common belief that the optimum way of exploiting low-temperature geothermal sources is heat generation. Therefore, this analysis is especially aimed at potential users and showing the technical and economical possibilities of using low-temperature sources for conversion of thermal energy into mechanical work and electrical energy.

Jan 1, 2003

By A. Sfougaris

A study on fauna distribution and abundance is being conducted in the Giona Mountain, in central Greece, area of bauxite mining. The specific aims of the study are: a) to estimate and map the distribution of mammals, and especially of the Balkan chamois, b) to estimate and map the distribution and abundance of breeding birds, c) to count the bird species using the area during spring and autumn migration and winter, d) to update the list of mammal and bird species of the mountain, with emphasis on rare and endangered ones, according to 79/409, 92/43 EU Directives and other relevant conventions, e) to compare the bauxite mining areas and species distribution and assess the possible overlap and compatibility of mining activities - species conservation, f) to assess the possible habitat loss due to planned mining activities. All estimations of mammal species distribution and abundance are being carried out by fieldwork using spotlight during the night along selected routes. Especially for chamois, line transects and vantage points with the aid of telescopes and binoculars are being used. Birds are being counted with the point count method in randomly selected plots distributed in all available habitat types and altitudes. The species distribution and mining areas will appear on thematic maps with the aid of a geographical information system (GIS). Finally, solutions for environmentally compatible mining activity in the area will be proposed.

Jan 1, 2007

By Richard L. Patterson, Alan P. Finch

Twenty years ago, when tunnel projects in the UK were generally procured by the public sector, many were completed late and over budget. Now a significant proportion of new infrastructure is developed by the private sector. Seeking more certainty in cost and programme, promoters have tried new and radically different methods of procurement and contract forms. The paper will review these developments, then examine the approach adopted for some of the largest current UK tunnelling projects (both in the public and private sectors) including the Channel Tunnel Rail Link, the Heathrow Terminal 5 Development and new highway tunnels.

Jan 1, 2003

By Anna Marabini

This paper provides a summary of the studies performed over a period of more than fifteen years by the Italian National Research Council's Mineral Processing Institute in Rome to develop applications for the use of chelating reagents in the flotation of metallic minerals. A description is given of the various phases through which the studied progressed, starting with the combined use of commercial chelating reagents and a neutral oil and then moving on to the synthesis of new long-chain chelate collectors for the flotation of sulphide and oxidized Pb, Zn and Cu minerals. After a series of preliminary tests which confirmed the possibility of floating various metallic minerals with commercial reagents containing chelating groups exerting specific action on given cations, the studies were addressed to the development of a theoretical method of choosing chelating groups that exert selective action on one metallic mineral rather than others. The theoretical approach was based on thermodynamic data concerning the chemical equilibria in solution. The validity of the method has been proved in numerous cases by flotation tests on pure minerals. Subsequently the research was directed towards the design and synthesis of reagents with a mixed aliphatic-aromatic structure containing chelating groups for Pb and Zn and an alcoxyl chain of various length, position and configuration. The flotation results obtained on oxidized and mixed Zn-Pb ores provided interesting pointers for designing the nonpolar portion. The structural criteria identified via these studies were interpreted on the basis of chemical and steric considerations. A description is given of a new synthetic chelate collector which is effective in the selective flotation of Cu minerals from complex sulphides. The fact that this reagents is more selective than xanthate is demonstrated by comparative flotation tests on actual ores.

Jan 1, 1994

By E. A. Brecke

The Cave-In-Rock Flourspar District is located in the northeast part of Hardin County, Illinois and is the most northeasterly occurrence of flour spar of the Illinois-Kentucky Flour spar Area. The occurrence of these deposits is confined to an area about one and one-half miles wide and five miles long parallel to the Peters Creek Fault (Fig. 1) The delineation of several features that may be described as breccia pipes has permitted the definition of the point of ascent of solutions to the host horizon and the lateral spread from these points.

Jan 1, 1962

By K. Rajamani, L. B. Hales

Much of the process control effort in the mineral industry uses proportional-integral-derivative controllers that require periodic retuning. Retuning hundreds of controllers typically employed in a single plant is a formidable task for the control engineer. Adaptive controllers offer an alternative to this problem, since they are designed to tune themselves. Four schemes of adaptive control-gain scheduling, model reference adaptive control, self-tuning regulator, and optimal adaptive controllers-are discussed with process examples. The control of a ball mill circuit with a multivariable self-tuning regulator is illustrated. This controller encompasses the advantages of the other three controllers and is applicable for a wide range of process variability.

Jan 1, 1988

By John C. Brower

Bolivia is nor a major gold producer but has produced continuously since pre Inca times. Production reached a peak in 1964 of about 4,000,000 grams and is currently about 1,000,000 grams. Production is mainly from the Tipuani River valley north of La Paz and is derived from Pleistocene basin fill: the Cangalli conglomerate and overlying terraces. Abandoned Pleistocene lake terraces south of La Paz in the Oruro area are another source of gold whose potential have not been realized. In both the Tipuani and Oruro areas, primitive hand methods are the principal means of production, with the exception of a single modern dredge. In spite of a long history of production, probably very little of the gold potential has been mined.

Jan 1, 1979

By P. D. Lafleur

A concerted effort to determine the quantities and effects of trace elements in the environment requires the application of a number of different analytical techniques in the same or in different laboratories. The interpretation of analytical data is often difficult because of differing results between analysts or even by the same analyst at different times. Standard Reference Materials (SRM), which are certified for their trace element content and are in a matrix similar to the one of interest, can greatly increase the accuracy of analysis and the reproducibility between laboratories. The United States National Bureau of Standards (NBS) has developed a number of SRMs applicable to the determination of trace elements in environmental materials. Two of these, SRM-1571, Orchard Leaves, and SRM-1577. Bovine Liver, are excellent for biological tissue analyses. Several new standards are of value for fossil-fuel analyses. These are: SRM-1632. Trace Elements in Coal; SM-1633, Trace Elements in Fly Ash; SM-1634, Trace Elements in Residual Fuel Oil: and SRM-1635, Trace Elements in Gasoline. In cooperation with the US Environmental Protection Agency, the NBS has recently concluded an interlaboratory comparison involving analyses by more than 60 laboratories on these fossil-fuel materials. The resulu of this intercomparison and the broad range experience with the biological materials will be presented showing both intratechnique and intertechnique variations, and the sensitivities and comparisons with the values certified by NBS.

Jan 1, 1975

Integrated mining information and process control systems can reduce information delays, enhance decision making and improve the responsiveness of mining operations to, for example, variations in market conditions, mineral grades and ground conditions. This paper examines developments in the areas of: monitoring, data analysis and diagnosis,' communications systems; integrated mining support system;, and process and machine control. It concludes that the development of a comprehensive information technology plan is fundamental to the phased implementation of these technologies. In addition, hardware and software standards and concurrent digital design and simulation practices in selected manufacturing industries are examined and concluded to have relevance to the mining industry. Integrated information and process control systems will lead to emergence of the "digital mine". Such advances in mining information infrastructure as well as mining equipment will enable mining operations to shift from mass production methods to leaner production techniques. "Lean mining" aims to enhance and accelerate cash flow over the life of a mine by focusing on reduction of' throughput times; stockpiles for volume and quality control; and wastage and rework.

Jan 1, 1995