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By E. Barnea

This paper simplifies and provides a strict mathematical proof for an equation developed by R. J. Woody for the c alculation of solute recoveries in countercurrent decantation. The equation offers a convenient method for the optimization of flowsheets involving a simple countercurrent-decantation circuit.

Jan 1, 1978

By K Marler

The Water Act 2000 includes provisions to manage the take of overland flow water. Overland flow water is water that runs across the land after rainfall either before it enters a watercourse, after it leaves a watercourse as floodwater, or after it rises to the surface naturally from underground. To ensure adequate environmental flows and long-term security for water users, it is necessary to balance the amount of water taken as overland flow water and the amount left to flow into watercourses. A water resource plan made under the Water Act 2000 establishes the basis for the sustainable management of this type of water. Of the water resource plans that have been prepared for Queensland catchments, six include provisions to manage the take of overland flow water. This paper discusses some of the common features of these plans and the management approaches adopted. The paper identifies and explains key aspects of the Water Act 2000 framework for managing the take of overland flow water by the mining industry. In particular it explains key concepts of this framework, such as the ability to take overland flow water using existing works, uses of overland flow water that a water resource plan permits, situations where a specific entitlement under the Water Act 2000 is required, and the means for controlling works that take overland flow water. Future initiatives for the regulation and management of overland flow water are then identified and particular challenges for the mining industry associated with using overland flow water highlighted.

Jan 1, 2006

By Normand Bédard

This presentation highlights Cambior?s initial approach for recruiting and retaining its international employees, the importance of proper preparation and the support needed to ensure a competent and stable workforce. In general, most of the training and information available for human resources personnel prepares the specialist for handling various aspects of labour relations, recruitment and hiring, benefits administration, employee relocation, etc. This is usually done in a Canadian context. Only recently, has more specialized training been developed to prepare human resources practitioners for the complex issues related to expatriate employees and dealing with human resources issues in other countries.

May 1, 2003

By Boyd R. Davis

Like many pyrometallurgy researchers, Ralph Harris? work extended over both light metals (lithium and magnesium) and base metals. His work looked at feed preparation, primary production, and secondary treatment. The thermodynamic principles of chemical metallurgy allowed Ralph to move between these two groups of metals. However, these metals have few similarities when projects are being developed. The traditional ?deposit-based? drivers for base metal operations do not apply to the same degree with light metals projects. While high purity, low cost feed is important to light metals projects, it should not be considered as the main reason for a smelter project. While it is clearly understood that technology (energy costs) is the driver for aluminum production, it is less considered for other light metals. This paper will look at the break down of base and light metals? production costs to try to quantify the balance between feed costs and technology for each metal group.

Jan 1, 2013

By R. Kanniganti, M. Karmis, C. Haycocks

An extensive review of multi-seam under-mining literature was conducted and a data base of case studies was assembled . A critical review of the design principles outlined in this literature resulted in the compilation of specific design criteria for the design of lower seam mines. Analysis of this criteria demonstrated the necessity for a protocol for the design of unsymmetrically loaded pillars. Such a design criteria was developed using finite element methods for a wide range of possible loading conditions. This design criteria can be utilized for underlying pillar design when the loading conditions can be determined. To facilitate using all the under-mining research results by field/planning engineers a Windows TM based software package was developed. This software package contains a multi-seam tutorial, analytical tools and a case history database. The package is user friendly and fully interactive and supported with extensive on-line help. The package contains numerous case studies of multi-seam mines that can be reviewed to facilitate analyses.

Jan 1, 1996

By Paine GG

In coal mining each of the unit operations are interrelated with each preceding operation having an effect on subsequent operations. This presents difficulties for determining when the lowest overall costs for a particular mining system are achieved. Drilling and blasting is the first mining operation for production and is known to have an effect on the subsequent loading, hauling and crushing operations. Computer blasting models developed over the past 15 years can be used to describe the drilling and blasting operation. This paper describes the ICI Blasting Model "SABREX" in detail. Methods of using the model are discussed. This involves field measurements of geological structure, shallow refraction seismic surveys, laboratory measurements of rock properties and high speed photography of blasts. The predictions are compared with actual blast results for fragmentation sizing and muckpile profiles. Outputs from the model are described and these can be used for input to models of subsequent operations.

Jan 1, 1987

By Erdal Unal

In underground mining today, safety and economical aspects demand a better understanding of the rock-mass conditions, particularly for design of underground mine openings excavated in weak and stratified rock mass. The rock mass classification systems, in essence, are empirical approaches utilized during preliminary design stage. These systems have been developed for specific purposes and rock mass types, therefore, direct utilization of the classification systems in their original form, for characterization of complex rock-mass conditions is not always possible. This is probably one of the main reasons why designers continue to originate new systems, or modify and extend the ones already existing. RMR and Q systems, for example, although widely used in mining and tunnelling, can not fully describe the specifications of the weak, stratified and flay bearing rock mass. Consequently, the engineering applications that would be carried out based on original RMR and Q ratings could be inadequate for making design decisions even during the preliminary design stage.

Jan 1, 1990

By Porter Hoagland

There has been a recent surge of interest in existing and proposed institutional mechanisms that would govern the exploration and disposal of nonfuel minerals within the U.S. ocean jurisdiction. The Minerals Management service, a bureau of the Interior Department, has begun to promulgate regulations to allow the exploration and leasing of lands for nonfuel mineral development on the outer Continental Shelf of the united States. At the same time, a bill has been introduced in the U.S. Congress that would create a new ?national seabed? and authorize the allocation of exploration licenses for marine nonfuel minerals. Because only limited efforts have been devoted to the discovery of marine nonfuels in areas beyond the territorial sea of the United States (and no production has occurred), exploration and the generation of resource information are two primary foci of these regulatory and legislative efforts. Generally, minerals exploration activities (and associated R&D on exploration and production technologies) are eligible for the same institutional incentives available for other industrial efforts, including tax preferences for research and experimentation, patent protection, small business innovation research grants, and even the new leniency in antitrust rules

Jan 1, 1988

By C. A. Rowland

Introduction Ball mills are lined drums, either cylindrical in shape or modified cylinders that have either one or both ends of the shell, consisting of conical sections, that rotate about the horizontal axis. Fig. I I shows a cylindrical mill, Fig. 12 a conical ball mill, and Fig. 13 a Tricone ball mill (Hardinge tradename). Steel or iron grinding media, generally in the shape of spheres, are used to grind the ore to the specified product size. In order to obtain more contact area for grinding and to simulate the shape of worn balls, balls have been made with two concave surfaces diametrically opposite each other. Some concentra¬tors, such as Erie Mining Co., have used slugs cut from worn and broken rods to supplement the balls in ball mills and save money otherwise lost as rod scrap. Cylindrical and conical shapes have been tried instead of balls, but balls remain as the most common shape grinding media used in ball mills. Ball mills were a logical development from the earlier pebble mills that used hard natural pebbles such as flint pebbles or sized ore pebbles (obtained from the ore itself) as grinding media. In the early 1900s36 it was found that when cast iron or cast steel balls were used in place of flint or ore pebbles, the mills drew more power and gave greater production capacity. Advances in technology have resulted in the manufacture of ball mills up to 18 ft diam inside shell, drawing up to 8,000 hp. Ball mills are employed to grind ores, especially the more abrasive ores, to finer sizes than can be produced economically in other size¬reduction machines such as roll crushers, hammer mills, and impactors. Ores can be ground dry-dry grinding-or in a slurry-wet grinding-using ball mills. Dry grinding nominally refers to less than I %v moisture by weight. If the moisture content increases by several percent, dry grinding capacity is significantly reduced as shown in Table 17. The usual range of solids content in wet ball-mill slurries is from 65 to 80% by weight. Wet grinding is used to prepare the feed material for unit opera¬tions such as flotation, magnetic separation, gravity concentration, and leaching that require a slurry of liberated valuable mineral and unwanted gangue particles. Dry grinding" is employed to produce feed for agglomeration, pelletizing, and pyrometallurgy processes that require feed that is dry or nearly so and for finely ground industrial mineral products used in the dry state. Dry grinding is also used when minerals cannot be dewatered economically to the required moisture level or when the ground product reacts unfavorably with liquids. For example, cement clinker must be ground dry. Dry grinding requires about 30% more power than wet grinding for comparable size reduction .28 The total power required in a dry¬grinding ball-mill plant including drying may be double that required for a wet-grinding plant. Grinding-media and liner consumption in dry grinding reported as pounds of metal consumed per kilowatt-hour per ton of ore" is 10-20% of that used in wet grinding. The Wabush pellet plant, Point Noire, Que.3o reported ball consumption dropped from 6.3 lb per ton of ore ground to 2.5 lb per ton of ore ground when they converted from wet to dry grinding, and a 30% increase in power consumption. A number of comparisons made on wet and dry grinding of cement raw materials show metal consumption in dry grinding to be 10% of that in wet grinding. The capital costs for wet grinding are generally lower than for dry grinding. When thickening and filtering of the wet-ground product are required, dry grinding may have a lower capital cost. With open-circuit grinding the ball-mill discharge passes directly to the next processing step without being screened or classified and no fraction is returned to the ball mill (Fig. 14). In closed-circuit grinding the ground material, undersize, in the ball-mill discharge is removed either using a screen or a classifier with the oversize being returned to the mill for additional size reduction (Fig. 15). The over¬size material that is returned to the ball mill is called the circulating load. Open-circuit ball-mill grinding requires more power than closed¬-circuit grinding for products containing similar amounts of top-size material. The less the amount of oversize allowed in the product, the longer the ore must remain in the ball mill when grinding in open circuit. This increases the production of extreme fines and thus the consumption of more power. The power required for open-circuit ball-mill grinding can be estimated using the multipliers listed in Table 18 and knowing the power required for closed-circuit grinding to yield the desired product particle size. For example, assuming the desired grind size is 90% passing some specific top size, open-¬circuit grinding would require 1.40 times the power to achieve similar results as closed-circuit grinding.

Jan 1, 1985

By E. Cetin

The authors describe the general problem of cut-off grade optimisation for multi-mineral deposits and outline the use of genetic algorithms for optimal cut-off grade schedules for deposits with up to three constituent minerals. Case studies are given and a comparison is made with Lane's multi- mineral cut-off grade algorithm.

Jan 1, 2002

By J. W. C. Wong, S. D. Miller, J. J. Jeffery

Pre-mining identification of acid forming mine and waste materials is of concern to the mining industry because of the potential for the generation of acid mine drainage, acid rock drainage, and soil acidity problems. Accurate identification of acid forming material is essential for developing appropriate waste management strategies to reduce environmental problems related to acid generation from sulphide containing wastes. The acid-base accounting procedure, in its various forms , is commonly used for pre-mining screening of mine and mine waste materials. The procedure is generally effective when used and applied correctly but is prone to incorrect interpretation of results which can have significant financial and environmental implications. This paper examines the acid-base accounting Procedure and the possibility of misuse of this method with special emphasis on the sampling method, the sulphide forms, the acid neutralization capacity, and the interpretation of results. Data from numerous coal, base metal, and gold mining operations are used to illustrate the application of the acid-base account. The data base indicates that overall, approximately 1/3 of all waste generated by mining and mineral processing is potentially acid forming indicating the need for correct identification and management. Problems associated with simple application of 'absolute' acid-base criteria for classifying acid forming material are highlighted and the need for developing site specific or 'relative' criteria is discussed and illustrated by case study.

Jan 1, 1991

By Sean Gallagher, Thomas G. Bobick, William S. Marras

Twelve healthy, experienced underground cool miners performed lifting capacity tests in stooped and kneeling postures using a modified psychophysical procedure. Subjects adjusted weight in a lifting box to the maximum they could handle without undue fatigue in an asymmetric lifting task. Lifting periods were 20 min in duration and the frequency was 10 lifts/min. Tests were performed under a 48-in. roof that restricted the subject&apos;s posture. Psychophysical. physiological, and biomechanical dependent measures included the maximum acceptable weight of lift (MAWL), heart rate (HR), rate of oxygen consumption (VO2), ventilation volume rate (VF), respiratory exchange ratio (R), and integrated electromyography (EMG) of eight trunk muscles. Results indicated that the MAWL was significantly lower when kneeling than when stooped (p < 0.05), Furthermore, metabolic demands were greater in terms of HR (p < 0.005) mid VO2 (p < 0.05) when kneeling. Left and tight erectores spinae muscles exhibited increased EMG activity- in the kneeling posture (p < 0.001). It was concluded that psychophysical lifting capacity is decreased, while the metabolic stress and internal load on the spine are increased, in the kneeling posture. Results of this Bureau of Mines study indicate that it may be advisable to reduce the weight of materials that are handled repetitively in the kneeling posture.

By K Thorpe

Amorphous silica deposits have been identified at Tikitere and Taheke near Rotorua. Two areas at Tikitere have been surface sampled and drilled to establish a resource of amorphous silica in excess of one million tonnes. A pilot plant was established to develop a process to manufacture a high quality super pozzolanic material. This development process took two years before a commercial product was introduced to the construction industry in 1996. The amorphous silica product, marketed as Microsilica 600, is used as a pozzolanic material to produce high quality strong and durable concrete, sprayed tunnel linings, mortars and grouts. Microsilica 600 has been used locally and exported to 11 countries.

Jan 1, 1999

By H. E. Bartlett

This paper deals with the sampling and mass measurement for ore delivered from a shaft to a processing plant and the contribution of the data from these measurements to the metal balances from shaft deliveries to final metal production. Accurate measurement of the grade and tonnage of run-of-mine ore is important for four main reasons; ? It enables the measurement of the production from different profit centres to within statistically determined confidence limits for daily, monthly, or annual averages. The profit centres could be individual shafts within a mining complex or ore treated on a toll basis ? The monthly production at shaft head is compared to the grades and tonnage determined from underground sampling and mass measurement in terms of a shaft call factor ? The sum of the production from the shafts is the input to concentrators. This input is a major part of the total input into a complex with concentrators, smelters, and refineries. In terms of the Codes of Practice for Metal Accounting the inputs are compared to outputs and inventory changes to assess the efficiencies and unaccounted losses or gains at the various stages in the flow of metal from source to market ? On a daily or daily moving average basis, the grades and tons from shafts are monitored and compared against these quantities from underground measurements. This acts as a control on off-reef mining, dilution, and other factors underground. Accurate measurement of grade of ore at the shaft head has been a challenge because of the large particle size. The conventional wisdom has been that ore can be sampled accurately only after it has been milled to give a slurry that is sampled as feed to a flotation process. However, when the ore fed to a flotation plant comes from multiple sources each source has to be sampled separately. So, relying on the grades determined using the sampling of concentrator input with cross-stream slurry samplers is not an option for determining the grade from an individual shaft. Impala has developed a system for sampling and weighing run-of-mine ore from multiple shafts. The system involves sampling the inputs to the plants using cross-belt (hammer) samplers and weighing the deliveries using in-motion railway weighing systems. Many samples are taken. Individually they have a high variance but, as a consequence of the averaging effect of large numbers and as shown by statistical analysis, the mean results are fit for the purposes of daily grade control for shafts and for monthly accounting of production from individual shafts. In the metal accounting systems at Impala, the measurement of input, including ore and toll-treated material is compared to the output in the form of final metal and tailings losses, as well as any inventory change that takes place, in order to determine a final metal balance from mill feed to product. The calculated inventory is compared to that measured, and the difference, or unaccounted- for metal, is then reported as a percentage of input. The balances obtained over several years yields balances for platinum that are below 1% imbalanced. Keywords metal balancing, platinum mines, AMIRA codes of practice, metal accounting, sampling, run-of-mine ore, statistical analysis.

Jan 1, 2014

By Dewey W. Marino

Conventional remote sensing applications for the exploration of natural resources has largely been the domain of low resolu­tion Earth orbiting systems such as Landsat™ which can sample a broad range of the spectrum. As the classic application of remote sensing, it has proven its worth through the discovery of numerous mineral deposits worldwide. Often this technique relies more on the spectral content of the imagery for narrowing potential sites on the ground, but often cannot reveal the detailed context of the observed response. As the dawn of the new era in remote sensing grows closer, high-resolution imagery is proving its worth for the definition of mineral potential and its cost sav­ing advantages for mine management.

Jan 1, 1998

By T. Vincze

Effective coal mine face ventilation, for remotely controlled and automated mining systems, is essential for the control of methane. The evolution of new mining equipment and methods has required changes and improvements in face ventilation methods. One emphasis today is on the use of remotely operated and automated mining systems that can be used to make continuous cuts of 6 m (20 ft) and deeper. U.S. Bureau of Mines research is studying ways to more effectively ventilate these extended cuts. Two face ventilation techniques that utilize either blowing brattice or a jet fan for deep cutting are examined in this paper. Bureau of Mines procedures for evaluating face ventilation systems are also discussed.

Jan 1, 1992

By Katherine L. Heineken, Timothy J. Tope, Kim David Murphy

One method for small arms disposal is the use of a deactivation furnace or explosive waste incinerator. There are numerous hurdles a facility typically encounters to get the furnace or incinerator fully operational and permitted. For example, one Department of Defense installation was in the permitting process 7 years, which included numerous facility upgrades and modifications. This paper will discuss the technical approach for proactively addressing permitting issues and requirements and will identify potential pitfalls to avoid as well as ways to reduce costs. For example, when determining the waste profile, the facility should forecast its treatment needs (taking into account the net explosive weight limits of the furnace/incinerator) and then classify the wastes into "chemical families" based on the type and composition of the wastes. One waste from each family should then be selected for potential inclusion in the trial burn. Modeling the waste disposal can help to narrow down the number of wastes requiring characterization during a trial burn, as well as the number of analyses.

Jan 1, 1997

By F. L. D. Cloete

The Relix process is based on direct contact between an ion-exchange resin and undiluted pulp, thus avoiding prior solid-liquid separation. The resin particles float near the surface of the pulp, forming an inverted fluidized bed with the pulp flowing downwards. The basic idea was demonstrated on a full-scale pachuca tank at Stilfontein Gold Mine in 1970, followed by a small-scale demonstration run in a laboratory at the National Institute for Metallurgy. A pilot plant based on a throughput of 60 tons of ore per day was subsequently operated at West Driefontein Gold Mine for several periods over two years. Although the plant proved operable from a mechanical point of view, the metallurgical performance was not up to expectation. The basic cause of the poor metallurgical performace was shown to be backmixing of both the resin and the pulp between stages. The values obtained for resin losses were inconclusive. Further development of resin-in-pulp processes for the recovery of uranium should be focused on the performance of various techniques for the screening of resin from pulp.

Jan 1, 1981

By Guilian Gao

TbFeCo is a common choice for many rare-earth transition metal films currently used as the magneto-optic layer for magneto-optical: recording devices. Since the environmental stability of RE-TM alloys is typically poor compared with traditional metal oxide particle media, such devices rely on multiple functional overlayers (metallic and/or dielectric) and organic coatings for durability. This paper presents an electrochemical evaluation of the degree of protection of several candidates for the reflective layer, Al, AlCr and AIPt and for the dielectric layer, SiN, AISIN and AIN. Cyclic voltammetry In 0.2M K2SO4 solutions at room temperature revealed that AIPt film offers superior corrosion protection compared to Al and AICr films. Of the three dielectric layers examined, SIN seems to be the most corrosion resistant. Examination by optical and scanning electron microscope confirm the findings of electrochemical experiments. The corrosion resistance of single layers of Al, AICr and AIPt has also been examined and factors affecting their performance are discussed.

Jan 1, 1992

By Y. J. Wang

This paper describes a graphical technique by which the operating points for a two-fan ventilation system can be represented as the intersection of the modified fan curves. In constructing the diagram, the air quantities associated with the fans are considered to be independent variables and employed as the axes of a rectangular coordinate system. The diagram may include, in addition to the modified fan curves, contour lines for resistances, pressures, and air powers. Procedures for drawing the diagram are discussed and illustrated with an example of the ventilation system.

Jan 1, 1985