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By Alex Joseph

A tertiary amine containing polyamine in its back bone was grafted to exfoliated graphite oxide by means of a series of chemical reactions.The synthesized amine functionalized polyaniline grafted to exfoliated graphite oxide (EGAMPANI) was characterized using various techniques such as, FTIR, TGA, Raman, and X-Ray diffraction.The synthesized EGAMPANI was blended with carbon paste electrode, and used to study the response of Hg2+ in acetate buffer solution.Preliminary analysis showed that the anodic current intensity using the EGAMPANI modified electrode was higher during a potential sweep and 10-4 M concentration of mercury could be detected which could be improved to 10-6 M using anodic stripping voltammetric technique. Keywords: metal sensor, exfoliated graphite oxide, functionalization, polyaniline

Sep 1, 2012

By David Sinclair, Philip B. Bucky

THE dimensions and shapes of mine structures may at present be determined by (1) field experience, (2) structural calculations, and (3) barodynamic tests.§ None of these, however, provide information as to the stresses, their direction and distribution in a mine structure. For the design of pillars, the placing of openings relative to working places such as gangways, haulage levels, etc., this information is desirable. Photoelastic methods provide this and, while relatively new, their application in all engineering fields is assuming increasing importance. This paper, therefore, will present the method with a few applications to mining, and with sufficient reference for further study by the reader. PART I THE PHOTOELASTIC METHOD The photoelastic method of stress measurement determines the stress distribution in a two-dimensional model by optical means. It makes use of the fact that when a piece of isotropic transparent material, such as glass, celluloid, or Bakelite, is stressed and viewed in polarized** light a picture is seen which indicates by its color bands of light, or fringes, the magnitude of the stresses, their direction and their distribution. GENERAL EXPLANATION The stress at any point 0 in a structure (Fig. 1), may be resolved into two components, P and Q, each a pure tension or compression, at right angles to each other, called principal stresses.1 To fully identify the stress, the values of P and Q and their directions or angle [0] must be known.

Jan 1, 1940

By David Sinclair, Philip B. Bucky

The dimensions and shapes of mine structures may at present be determined by (1) field experience, (2) structural calculations, and (3) barodynamic tests. § None of these, however, provide information as to the stresses, their direction and distribution in a mine structure. For the design of pillars, the placing of openings relative to working places such as gangways, haulage levels, etc., this information is desirable. Photoelastic methods provide this and, while relatively new, their application in all engineering fields is assuming increasing importance. This paper, therefore, will present the method with a few applications to mining, and with sufficient reference for further study by the reader. PART I The Photoelastic Method The photoelastic method of stress measurement determines the stress distribution in a two-dimensional model by optical means. It makes use of the fact that when a piece of isotropic transparent material, such as glass, celluloid, or Bakelite, is stressed and viewed in polarized** light a picture is seen which indicates by its color bands of light, or fringes, the magnitude of the stresses, their direction and their distribution. General Explanation The stress at any point 0 in a structure (Fig. I), may be resolved into two components, P and Q, each a pure tension or compression, at right angles to each other, called principal stresses.' To fully identify the stress, the values of P and Q and their directions or angle F must be known.

Jan 1, 1940

By David Sinclair, Philip B. Bucky

The dimensions and shapes of mine structures may at present be determined by (1) field experience, (2) structural calculations, and (3) barodynamic tests. § None of these, however, provide information as to the stresses, their direction and distribution in a mine structure. For the design of pillars, the placing of openings relative to working places such as gangways, haulage levels, etc., this information is desirable. Photoelastic methods provide this and, while relatively new, their application in all engineering fields is assuming increasing importance. This paper, therefore, will present the method with a few applications to mining, and with sufficient reference for further study by the reader. PART I The Photoelastic Method The photoelastic method of stress measurement determines the stress distribution in a two-dimensional model by optical means. It makes use of the fact that when a piece of isotropic transparent material, such as glass, celluloid, or Bakelite, is stressed and viewed in polarized** light a picture is seen which indicates by its color bands of light, or fringes, the magnitude of the stresses, their direction and their distribution. General Explanation The stress at any point 0 in a structure (Fig. I), may be resolved into two components, P and Q, each a pure tension or compression, at right angles to each other, called principal stresses.' To fully identify the stress, the values of P and Q and their directions or angle F must be known.

Jan 1, 1940

By Irina A. Pulyaeva

Hydrogenetic Fe-Mn crusts play an important role in marine mineral-deposit research because of their widespread occurrence and high concentrations of valuable and rare metals. Most Fe-Mn crust deposits occur on the tens of thousands of seamounts found in the global ocean as well as on ridges and plateaus. Because of these circumstances, it is essential to clarify a number of outstanding issues with regard to Fe-Mn crust history and development, including controls on metal sources and concentrations. The first-order characteristics of Fe-Mn crusts as potential ore deposits include concentrations of metals (grade) and the thickness of crusts (tonnage), which vary depending on Fe-Mn crust structure and texture. Data on the structure, composition, age, and deposit characteristics will help define which factors are key for the creation of mineral accumulation and which combination of factors leads to the formation of potentially economic concentrations of metals. In this paper, we address the structure and characteristics of Fe-Mn crust stratigraphic sections collected from Central and Western Pacific seamounts. We describe the changes in mineralogical and chemical compositions of crust layers of different ages, the occurrence and regional distribution of these layers that correlate regionally, and reconstruct the paleoceanographic conditions that influenced crust growth.

Jan 1, 2010

By S. Floreen

Measurements have been mode of the effects of tempering and austenitizing heat treatments, the work-hardening characteristics, and the effects of test temperature and strain rate on the properties of a low-carbon Fe-18 pet Ni martensitic alloy. In many respects the alloy behaved quite similarly to cold-worked iron. One notable quality was the excellent ductility at temperatures as low as 20°K. Many of the qualities of the maraging steels could he related to the properties of the Fe-Ni matrix. THE 18 pet Ni maraging steels have demonstrated that unusual combinations of strength and toughness may be obtained by age hardening a low-carbon Fe-Ni martensite matrix.' These properties must, to some extent, reflect the properties of this Fe-Ni matrix, and therefore an understanding of the properties of this matrix is a prerequisite to a complete understanding of the steels. There have been several recent studies of Fe-Ni-C martensites, but not much attention has been paid to alloys with very low carbon contents. At low carbon levels the crystal structure of these alloys is essentially bee.2 Electron transmission microscopic examination of a 20 pet Ni binary alloy showed martensite platelets separated by low angle boundaries.3 Plastic deformation of the low-carbon alloys has been shown to proceed by wavy glide.4 The hardness of these martensites is typically RC 28, and their yield strengths are 70 to 80 kg per sq mm.2, 5 Their ductility is excellent. Room-temperature tensile elongations of 18 pet and reductions of area of 70 pet have been observed in an Fe-18 pet Ni binary alloy.5 These observations have provided a qualitative understanding of the flow characteristics of these alloys. To date, however, no thorough study of their properties has been made. In particular, it is not known to what extent the deformation characteristics of low-carbon martensites are similar or dissimilar to those of pure iron or other bee metals. The present work was undertaken to provide more detailed information on the flow characteristics of a low-carbon Fe-18 pet Ni martensite. PROCEDURES, RESULTS, AND DISCUSSION Materials. A 40-lb heat of the Fe-18 pet Ni alloy used in this study was made by vacuum-induction melting. The charge materials were electrolytic iron and electrolytic nickel. A carbon boil was used to achieve deoxidation. After the boil the heat was refined by additions of 0.1 wt pet Ti and Al. These additions are commonly used in the maraging steels to keep the carbon and nitrogen contents in solid solution at a minimum. After casting, the heat was

Jan 1, 1964

By Robert J. Timko, Edward D. Thimons, Robert L. Derick

In early June, 1986, a fire of unknown origin erupted in one of several main entries of a coal mine located in southwestern Colorado. The fire was aggressively fought with high- expansion foam. As a result of several strategic decisions, the fire appeared to be held in check. Unfortunately, sufficient quantities of foam were unavailable and as soon as the foam was depleted, control of the fire was lost. To prevent further damage and the possibility of an explosion, all entries to the mine were sealed. This paper recounts activities from the discovery of the fire to the initial reentry of the sealed mine including location of the fire, the decisions made to best combat it, and the steps taken to rapidly and securely seal the mine when this became necessary. The mine operator requested the Bureau's assistance in obtaining and analyzing mine fire gases taken from sampling ports placed through the mine seals. This report describes how samples were taken and what gases were analyzed. In addition, this work describes the initial exploration of the sealed mine by personnel using oxygen breathing apparatus.

Jan 1, 1987

There are many different challenges when sampling mineral commodities. Sampling is part of many decision-making processes, from control of the number of drops of a reagent to all aspects involved in determining how much to pay for a mineral consignment. However, if all decisions must be supported by correct assumptions, or at least agreed terms, how can this be guaranteed? The main approach is to emphasise the importance of continuous surveying of sampling practices. If they are based on non-recommended protocols, this raises concerns. In addition, safety failures and lack of appropriate behaviour from the technical perspective can lead to disasters, both from the human and business perspectives. Impacts on safety and health are clearly unacceptable. It should be noted that imperfect safety and health practices in sampling operations have a strange correlation with incorrect sampling techniques. The commercial interface can also be affected. Companies have studied extensively the various aspects of measuring quality parameters for mineral commodities to understand the risks for investors and owners, and they take decisions that fundamentally respect the interests of parties in contracts and not result in losses. Every result should be obtained in defensible ways, and neither losses nor profits taken in indefensible ways. Most of such situations are related to bias; a significant systematic difference between a measured value and a reference value for a contractual quality parameter. Bias is always undesirable, because it always implies an incorrect advantage for one party and without doubt an undesired disadvantage for the other party. These situations are solved financially through a third-party arbitrator becoming involved in delicate situations, such as a commercial claim, but the outcome is always tangibly or intangibly bad for one of the parties. Another possibility is a permanent or temporary loss of precision. Poor precision, due its nature, generates reasonably balanced losses and profits, but it may hide out-of-control situations, generate instability and induce financial losses due to actions taken towards clearing commercial disputes involving interlaboratory programs, sample exchanges and duplicated sampling and sample preparation procedures, in the end wasting time and resources and creating a permanent source of commercial tension. While bias situations demand immediate adjustments for correctness, poor precision has to be understood as something that cannot be just calibrated out and is a situation that demands investment of time and effort. Precision optimisation has to take into account best practice for obtaining the required precision as well as cost/benefit analysis studies. Purchasers, engineers, salesmen and all personnel need to recognise that sampling is a major area to understand when taking decisions. The aim is to spread concepts that can really help, such as simple in-house actions to improve productivity and completion of surveys on commercial sampling operations, in order to ensure correct results are obtained and assertively take corrective actions, thereby establishing a healthy relationship with investors, suppliers and purchasers and in the process optimising the business.

Jan 1, 2008

By Richmond Bennett

Airborne geochemistry became a reality with the advent of a high-sensitivity airborne gamma ray spectrometer with large volume NaI (TI) crystal detectors. Small variations in the concentration of potassium (as K40), thorium (as T1208) and uranium (as B1214) along the flight lines can be determined by measuring the gamma radiation with a sensitive airborne spectrometer. Small volume crystal spectrometers are useful only for detection of major surface uranium (Bi214) variations, but the large crystal volume system is an airborne geochemical exploration method capable of locating hydrothermal mineral deposits. Radioactivity as a guide to ore has been discussed in the literature by Damon (1950), Gross (1952) and others. The theoretical basis is that potassium, thorium, and uranium are concentrated in late stage solutions during magmatic crystallization. Thorium and uranium are concentrated in late stage liquids because their large atomic radius and high ionic charge prevent them from entering into the crystal lattice of common rock-forming minerals (Rankama and Sahama, 1950). Potassium, which has a large ionic radius and small charge, also can be concentrated in the high water content late stage fluids (Heier and Adams, 1964). A large proportion of uranium and thorium in rocks occurs around grain boundaries of the essential rock-forming minerals (Hurley, 1950). Uranium and thorium substitute for zirconium in zircon, a comparatively early forming mineral. However, most of the thorium and uranium is concentrated in residuals where they can be fractionated and incorporated into allanite, monazite, xenotime, and other minerals.

Jan 1, 1970

By Herbert F. Nyberg

The Black River Falls Mine is owned and operated by Jackson County Iron Company, a wholly owned subsidiary of Inland Steel Company. It is located in vest central Wisconsin, seven miles east of the city of Black River Falls. This is the first taconite plant in the state of Wisconsin. Iron mining started in this area in 1856 but soon failed due to the low grade ore and crude methods of mining and transportation. Inland Steel Company acquired the property in 1939. Some drilling and test work was done in 1940, but the economics of developing the property at that time were not favolable. Improved methods of concentrating and pelletizing in the 1960's made it possible to build the present plant. Due to the limited ore reserve of 45,000,000 tons with expected recovery of 33% it was necessary to limit the capacity of the operation to 750,000 TPY with a life of 20 years. There was some concern about an operation of such limited capacity. A million ton operation was considered the minimum size plant for a profitable operation.

Jan 1, 1976

By Raymond W. Henn

The 30th annual short course ?Grouting Fundamentals and Current Practice? was held at the Colorado School of Mines, June 22-26, 2009. The field demonstration portion of the course was conducted June 25, at Hayward Baker, Inc.?s yard in Broomfield, CO. The full-scale field demonstration annually presents many different types of drilling equipment being operated as well as various grouting methods being performed under different field conditions. As part of the field demonstration, the class is shown the proportioning, mixing, testing and injection of various cement grout mixes into sand columns under controlled and measured conditions. These sand column demonstrations have been conducted under controlled and measured conditions each year since 1999 as part of the short course. The sand column demonstrations were conducted prior to 1999, but with less quality control and minimal record keeping of the proportioning, mixing, testing, injection pressures and the final permeation results. The goal of the sand column demonstration is to show the students the effect of the water cement ratio and the use of admixture as well as the fineness of the cement, portland versus ultrafine, used has on the engineering properties of the grout and the grout?s vertical permeation through the sand. Test results for the demonstrations conducted in 1999 and for two separate demonstrations, one at the grout course and one at Geo Denver, conducted in 2000 were published in the 2001 proceedings of the Rapid Excavation and Tunneling Conference (RETC) (Henn et al. 2001). The test results for the 2002 and the 2003 demonstrations were published in the 2005 proceeding of the RETC (Henn et al. 2005).

Jan 1, 2009

By Pingchao Ke, Zhihong Liu

"To overcome the problem that scoroditeis not stable in neutral and alkaline solutions, we proposed and investigated a synthesis method of scorodite coated in-situ with hydrated ferric oxide in the Fe(II)-As(V)-H2O system at the initial Fe(III)/As(V) molar ratios larger than 1.0.The synthesis was carried out at 90?,pH 1.5 under atmospheric pressure. During the synthesis, oxygen gas was conducted and bubbled into the system to oxidize Fe(II) ions into Fe(III)ions, and Na2CO3aqueous solution as neutralizing agent was added controllably into the system for keeping the pH constant at 1.5. In this study, three samples of scorodite were synthesized at the controlled initial Fe(II)/As(V) molar ratios of 1.0, 2.0 and 3.0, respectively. The characterizations of the samples by HRTEM, TEM/EDX, and chemical composition indicated that the particle surfaces of scorodite synthesized at the initial Fe(II)/As(V) molar ratio of 2.0 and 3.0 were coated in situ by a film of hydrated ferric oxide with the thickness of several nanometers, while the sample synthesized at the initial Fe(II)/As(V) molar ratio of 1.0 was uncoated scorodite. The TCLP and long-term leaching for the toxicity characteristic of the samples showed that scorodite coated in situ with hydrated ferric oxide was stable in a wide pH range from 3.0 to 10.0, with the arsenic concentrations in the leaching solutions less than 1.0mg/L. Nevertheless, uncoated scorodite was unstable under the conditions from weak acidity to alkalinity, with the arsenic concentrations in the leaching solutions larger than 5.0 mg/L.INTRODUCTIONArsenic pollution is a challenge for environment and health and has been an important issue for scientists (Hopkin, 1989).Arsenicis commonly associated with ores or concentrates of nonferrous metals, mainly as independent arsenic bearing minerals such as arsenopyrite (FeAsS), tennantite(Cu12As4S13), enargite (Cu3AsS4), cobaltite (CoAsS), and gersdorffite (NiAsS), realgar (As2S2), orpiment(As2S3), etc.(Matschullat, 2000; Mandal & Suzuki, 2002; Long & Peng, 2012). In the nonferrous metallurgical processes, arsenic is enriched mainly in such arsenic bearing materials as various flue dusts, residues, and anode slimes, which results in the accumulation of arsenic in the system owing to the circulation of those arsenic-bearing materials back to the system and the pollution to the environment (Harris, et al, 2003).In addition, the utilization of arsenic is limited and has been decreasing owing to its toxicity and carcinogenicity. Therefore, arsenic has to be removed from those arsenic-bearing materials and discarded safely (Dutrizac & Jambor, 1988; Monhemius & Swash, 1999; Drahota & Fillippi, 2009).In this case, how to immobilize arsenic has become a difficult problem which must be solved. Among the methods of immobilizing arsenic which have been proposed and investigated, immobilizing arsenic into a stable mineral to fix it, has been realized as a promising method and becomes a research focus(Dutrizac et al, 1987; Dutrizac & Jambor, 1988; Demopoulos et al, 1995; Fujita et al, 2008a; 2008b).Scorodite has been known as one of the best minerals for immobilizing arsenic, owing to its high stability under weak acidic condition, the arsenic content as high as 32wt%,and good crystallinity benefiting the separation of solid to liquid(Daivid et al, 1999; Zhu & Merkel, 2001). Scorodite can be synthesized from arsenic containing solutions under both hydrothermal and atmospheric conditions, and a lot of work has been done on the synthesis of scorodite and its leaching stability characterization (Filippou & Demopoulos, 1999; Gomez et al, 2011).Two plants for the immobilization of arsenic as scorodite have been putin to operation in Chile and Japan, respectively (Filippou & Demopoulos, 1999; Amir et al, 2016)."

Jan 1, 2017

By Rao Balusu, Bharath Belle, Krishna Tanguturi

A collaborative research project is undertaken by Anglo American Coal and CSIRO to develop appropriate strategies for gas and spontaneous combustion management of longer panels. Extensive computational fluid dynamics (CFD) modelling studies have been conducted and calibrated using operational longwall goaf gas data to obtain a fundamental understanding of goaf gas flow patterns in longwall panels of 1.0-km and 3.0-km lengths and a detailed investigation of the effect of various mining and operational parameters on goaf gas flow patterns. The modelling studies have also been used to investigate the performance of various gas drainage and proactive inertisation strategies during various stages of longwall panel extraction. Simulation results indicated that apart from tailgate (TG) side goaf holes, gas drainage from maingate (MG) goaf holes and the mid panel start-up goaf holes would be useful for flat seam field conditions. Operation of 8–10 goaf holes is recommended for field site conditions with high goaf gas emissions of 6000 L/s. The modelling results indicated that the traditional inert gas flow rate of 500 L/s currently used in some mines would be insufficient to achieve effective goaf inertisation in long panels. Results indicate that 3.0- km-long panels would require 1500 L/s of inert gas and there is a need for multi-point inert gas injection strategy for effective goaf inertisation. In this paper, details and results of modelling investigations and recommended strategies for gas and spontaneous combustion management in 1.0-km- and 3.0-km-long panels are presented.

By D. J. Miller

Environmental considerations are extremely important in planning and carrying out mergers, acquisitions and real estate transfers. It is not inconceivable that potential or actual environmental liabilities could exceed the targeted company's net worth or the book value of the real estate of interest. It is therefore essential that an environmental due diligence investigation (DDI) be performed to quantify environmental liabilities before sales, mergers or acquisitions. This paper will discuss general procedures used in environmental due diligence investigations. The emphasis will be placed on mergers and acquisitions. It should be pointed out that the procedures discussed in this paper are general and must be modified to fit each particular merger or acquisition under consideration.

Jan 1, 1988

A. H. Bromly, Zihuatanejo, Guerrero, Mexico (communication to the Secretary*):—The following criticism of what "is offered as a summary which may be found useful by mining engineers," is not dictated by any captious spirit, but in the intereet of historical and scientific accuracy. The States of Queretaro and Oaxaca have produced sufficient silver to warrant more extended notice. Referring to Pachuca, State of Hidalgo, the eomewhat loose and inexact statement is made that "the ore-depdsit is an andesite, intermixed with quartz-veins, rich from the surface." A better description mould be,—the ore-deposits consist of quartz-veins in andesite. It is notable that many of the rich shoots worked in recent days did not come to surface. In consequence, Pachuca is often quoted by the ill-informed as a camp in which values improve with depth, the truth being that the veins carry shoots, or clavos, some of which were exposed at surface and some not. The name of " electric plow," applied to the mechanical stirrer of recent use, is certainly not to be recommended. The stirrer, or agitator, consists essentially of a traversing gang-plow, operated by power through shafting; drums, and wire-rope. The fact that in certain plants the motive-power used is electricity does not make it an electric plow. Such a name suggests a machine of which the motor is an essential and integral part; which is not so in this case. A lathe in a factory driven by water-power is not called a hydraulic lathe. My experience agrees with Dr. Raymond's note as to azulapue, which in some districts is also applied to blue copper carbonate. The El Oro, Esperanza, and Mexico mines should be allocated to the State of Mexico; the Dos Estrellas being in Michoacan, as stated. The El Oro quartz certainly does not appeal to me

Jan 1, 1910

By J. D. Bittner

The ST separator utilizes electrical charge differences between materials produced by surface contact or triboelectric charging. When two materials are in contact, material with a higher affinity for electrons gains electrons and thus charges negative, while material with lower electron affinity charges positive. This contact exchange of charge is universally observed for all materials, at times causing electrostatic nuisances that are a problem in some industries. Electron affinity is dependent on the chemical composition of the particle surface and will result in substantial differential charging of materials in a mixture of discrete particles of different composition. In the ST separator (Figures 1 and 2), material is fed into the thin gap 0.9 ? 1.5 cm (0.35 -0.6 in.) between two parallel planar electrodes. The particles are triboelectrically charged by inter-particle contact. For example, in the case of coal combustion fly ash, a mixture of carbon particles and mineral particles, the positively charged carbon and the negatively charged mineral are attracted to opposite electrodes. The particles are then swept up by a continuous moving open-mesh belt and conveyed in opposite directions. The belt moves the particles adjacent to each electrode toward opposite ends of the separator. The electric field need only move the particles a tiny fraction of a centimeter to move a particle from a left-moving to a right-moving stream. The counter current flow of the separating particles and continual triboelectric charging by carbon-mineral collisions provides for a multi-stage separation and results in excellent purity and recovery in a single-pass unit. The high belt speed also enables very high throughputs, up to 40 tonnes per hour on a single separator. By controlling various process parameters, such as belt speed, feed point, electrode gap and feed rate, the ST process produces low carbon fly ash at carbon contents of 2 % ± 0.5% from feed fly ashes ranging in carbon from 4% to over 30%.

Feb 27, 2013

By Robert F. Shurtz, William J. Verner

Three basic questions must be answered by an engineer performing an economic analysis of a mineral property: (1) How much can the company afford to pay for the property; (2) At what rate should the property be mined; (3) What will be the return on the investment. These questions often defy reasonable analysis, because at the point in time at which they must be answered little may be known about the grade of ore and the reserve tonnage. The purpose of this report is twofold. First, to derive a method of determining purchase price, rate of production and return on investment which is valid under varying conditions of ore grade and tonnage reserve; and, second, to apply this method to the Margay deposit in an attempt to evaluate it as a business enterprise. This is an actual economic analysis of an existing nickel-copper deposit fictitiously named the Margay. It was carried out for a mining corporation and proved to be the determining factor in the subsequent purchase and development of the property. All data referring to costs, quality and quantity of ore, etc., are accurate and truly represented. Prices used are obsolete but the method is not dependent on those variables. Basic assumptions for the analysis are given in Table I, page 71.

Jan 11, 1966

By Michael Schultz, Gregory Sanders

The City of New Haven is planning to construct the Downtown Storm Sewer Infrastructure Improvement project to mitigate on-going stormwater flooding in the Long Wharf District. The proposed project includes a 685 cubic feet per second (cfs) stormwater pump station and a 3,200 linear feet (975 meter) long tunnel segment with an internal diameter of 120-inches (3.05 meters). This paper presents the aspects of the final design and the use of the cloud-based data management software to make better data-informed decisions. The software was used to create a spatially aware database of the subsurface conditions, as well as improve visualization and analysis of the soil properties.

Dec 1, 2022

By R R. Lovel

In this paper, life cycle assessment methodology has been used to assess the variations in water use associated with different metal production and processing routes and provide insights into the value derived from water usage in the minerals sector. Using water consumption data derived from the literature it has been shown that the æcradle-to-gateÆ water consumption (or embodied water) for production of the various metals considered in the study ranged from 2.9 m3/t for steel up to 252 087 m3/t for gold. The results largely reflect the grade of the initial ore used to produce each metal, and can be approximated by the following equation:W = 167.7 G - 0.9039 where: W = embodied water (m3/t refined metal) G = grade of ore used to produce metal (per cent metal) The study showed that indirect water consumption in the metal production life cycle, in particular that due to electricity generation, can make a significant contribution to the embodied water value, eg aluminium production. When expressed in terms of m3/t ore, the results for all metals considered indicated that the embodied water is roughly, on average, three times the water consumption of the mining and concentration stage. It was also shown that the economic value per m3 of water consumed for the minerals industry exceeds that for the agricultural and industrial sectors, supporting the view that allocating water resources to the minerals industry has a strong underlying economic basis. Water reforms currently taking place in Australia aim to address issues such as competition for water access, reduced security of supply and increase in cost. Consequently the minerals industry, along with others, can be expected to come under increasing pressure to reduce fresh or raw water use and to integrate water use across sectors. While water recycling is an obvious candidate to help reduce water consumption in the minerals industry, issues such as water quality, among others, will influence the extent to which this can be achieved. In addition, wastewater volumes can be minimised using techniques such as pinch analysis to establish and use the minimum water requirement for the process. The use of dry or near-dry processing technologies, for which the demand for water is small or zero, may be a more radical solution to the water consumption problem; however, it is possible that the introduction of dry processing would bring with it a new set of problems, including dust.

Jan 1, 2006

By D. Brady

When deciding to deploy rescue teams underground the decision makers need to be able to determine that there won?t be an explosion whilst the rescue teams are underground. Previously general body concentrations in areas likely to be travelled were compared to explosive limits on a one off basis with no formal process looking at trends or other areas. A new approach is being adopted that takes into account the rate of change of gas concentrations with triggers set to enable a withdrawal of personnel prior to a possible explosion and influences such a barometric pressure changes. This paper explains the rationale behind the changes made and the advantages and implications of adopting such an approach.

Jan 1, 2012