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By M. L. Tucker, William H. Langer

Many countries, provinces, territories and states in the European Union, Australia, Canada, the United States and elsewhere have begun implementing sustainability programs. Most of those programs, however, stop short of sustainable management of aggregate resources. Sustainable practices do not always have to be conducted under the title of sustainability. This case study describes how Lafarge implemented the principles of sustainability even though there was an absence of existing local government policies or procedures addressing sustainable resource management. Jefferson County is one of three counties in the six-county Denver, CO, region that has potentially available sources of crushed stone. Crushed stone comprises 30percent of the aggregate produced in the area. And it plays a major role in regional aggregate resource needs. Jefferson County is home to four of the five crushed stone operations in the Denver region. Lafarge operates one of those four quarries.

Jan 1, 2004

By W. C. Lacy

Stratabound copper ore bodies in thick Proterozoic metamorphosed sedimentary and volcanic rocks at the Tong Kuang Yu Mine in southern Shanxi Province of China were considered as possibly being amenable to block cave mining. Initial evaluation of caving characteristics was based upon old calyx drilling records, limited underground mining experience and geological mapping, a few diamond drill holes and measurements in surface subsidence features. Classification and mapping distribution of rock quality types aided in mine design, prediction of fragment sizing and explosive requirements, cave assist and ground support requirements. Comparison is made between early feasibility predictions and actual mine experience.

Jan 1, 1989

By Vinay Kumar Agrawal, Rama Nath Praharaj

IMFA Group is the largest producer of Charge chrome not only in India but also in Asia. This Group has plants situated at Therubali and at Choudwar. They also have a Thermal power plant at Choudwar which not only caters to the power requirement of Choudwar plant but also supplies power to Therubali. The plants are fed for Chromite ore through the captive mines namely Nuasahi Chromite mines (40.47 Ha) , Bangur Chromite mines(37.34Ha), Sukinda chromite mines (116.76 Ha), Mahagiri Chromite Mine(73.777 Ha) and Chingudipal Chromite mines (26.62 Ha). Nuasahi Chromite Mine, which is situated in Keonjhar district, is an underground mine and is based upon best technological advancements in the industry. The underground mining operation is certified under ISO-9002, ISO-14001and OHSAS 18001. This not only shows the concern for the quality, environment but also for the health of the employees. The Nuashahi is the first chromite mine to backfill the opencast excavations created during the last 50 years and carry out the production from underground area below the opencast workings. This paper deals with the state of art technology of sub-level open stopping in thin ore bodies. The under-ground mine openings was started in the year 1997. In next four years the production of chromite from underground was started.(2001). At present the mine is in a good shape with several running stopes. Today it is producing around 10,000 Mt per month of chromite. The development of the mine is carried out with an average of 200 mtr per month of tunneling. The mine is having a mechanical ventilator having a capacity of24000 M3 per hour at 50mm water gauge, thus feeding sufficient air for the persons working in underground. The mine is being dewatered through a most modern positive suction sump, having a capacity of 500 cum and operated with 120 HP pumps. After commissioning of this sump in the year 2003, the mine has taken a quantum jump in production with remarkable saving in power consumption.

Jan 1, 2007

By José Cuadros

"El presente trabajo señala el proceso de evolución del método de minado en la mina Chupa, perteneciente a la unidad minera de Iscaycruz. La evolución del método de minado se determinó por la búsqueda de mejores condiciones de seguridad y eficiencia en la operación. En ese sentido, los resultados logrados con cada una de las alternativas de minado por subniveles, indica que se ha logrado optimizar las diferentes variables mineras y cumplir con el plan estratégico de Empresa Minera Iscaycruz S.A. (EMISA). Para cumplir con el citado plan estratégico, se debe optimizar el método de minado de Chupa, a través de una mayor producción a un menor costo,así como del aprovecho de las labores de desarrollo y preparación ejecutadas según el planeamiento inicial del minado. Por ello, la secuencia del avance del minado y la reestructuración del sistema de relleno de la mina son los aspectos importantes para lograr este objetivo. "

Jul 31, 2003

Experiments in the bolting of a mine roof were commenced at Elrington Colliery on the South Maitland Coal Field early in 1949, following the appearance of an article in the American publication, "Coal Mine Modernisation Year Book" 1948. Prior to this, although bolting had not been used in the maintenance of satisfactory roof conditions, the principle of roof bolt anchorage had been illustrated in instances such as the hanging of a trolley locomotive power wire using an expanding shell type of bolt anchorage, or the insertion of an eye bolt with a split and wedge, as used to suspend a rope block over a winze being sunk in a metalliferous mine.The experiments at Elrington Colliery were the first efforts in this country to supplement the work of timber supports under a mine roof with systematic placement of roof bolts.Following the series of experiments at Elrington, full scale bolting was commenced at that Colliery in a trackless mobile section in April, 1950.The obvious success of the system at Elrington indicated that it might also be a success in the support of weak roof strata immediately overlying the workable section of the Victoria Tunnel Seam at John Darling Colliery.The system was commenced at John Darling Colliery in April, 1951, in one mechanical section on the Victoria Tunnel Seam, and the scope was gradually widened until by December, 1952, ail'six mechanical units then operating on this seam were working under bolted roofs.

Jan 1, 1954

By K. Wenrich

The uranium industry has made a dramatic turnaround in the past three years that even the most optimistic economist was not willing to predict during the uranium downswing of the 1990s. Uranium reached a 30-year low in February 2001 of $6.50/lb. By the end of February 2006 it had soared to $38.50/pound. This nearly 600% increase in the uranium spot price within 4 years dwarfed the increase in gold price that has barely mustered a 100% increase. The initial slow rise from $6.50 in February 2001 to $10.75 in April 2003 (fig. 1) was primarily driven by the decrease in the value of the dollar. Since then several factors have contributed to the soaring price: (1) The awakening of many to the simple fact that uranium supply has not met demand for several years and that the world’s stockpiles are being drawn down, (2) How sharply this fragile supply can be impacted by disasters at the world’s major uranium production facilities, such as a) the flooding of the McArthur River Mine in the spring of 2003, b) fires at Olympic Dam, c) the potential that Rossing, with an annual capacity of 4000 tonnes uranium might close by 2007, (3) the withdrawal of Tenex from the HEU (highly enriched uranium) feed agreement, and (4) the announcement by the Chinese of their intent to build 30 new nuclear reactors.

Jan 1, 2007

By Mark E. Smith

Oxide ores can consume enormous amounts of expensive sulfuric acid. The problem is amplified with increasing heap heights. One solution is to provide a thin liner and drainage system between each lift of ore, thereby intercepting the pregnant leach leach solution (PLS) after it exits the active lift. However, these liner systems require special attention to hydraulics, slope stability and geomembrane design criteria. Inadequate attention to the first two can result in reduced recoveries, increased acid consumption andsystem failures. The geomembrane selection criteria are different from the base liner, and optimizing its selection can have significant effects on the operation’s bottom line.

Jan 1, 1996

The Bureau of Mines is active in programs pertaining to solid waste disposal and land reclamation. Nine reclamation projects of mining companies and six projects of the Commonwealth of Pennsylvania were investigated to provide information on the procedures, costs, and results obtained from reclamation projects of bituminous coal-waste disposal areas. Refuse disposal costs of mining companies ranged from 9 to 28 cents per ton-mile, and quantities disposed of ranged from 600 to 4,500 tons per day. Spreading and compacting the refuse at the dump site ranged from 3 to 20 cents per ton. Cost of covering with soil and planting ranged from $750 to $1,646 per acre. Total costs of reclamation for the Pennsylvania projects ranged from about $1,800 to more than $15,000 per acre. Refuse preparation costs ranged from $772 to $5,550 per acre. Soil covering and planting costs ranged from $1,083 to $5,086 per acre. The best results were obtained by soil preparation and conditioning prior to planting. The type and depth of soil and effect of climate were also factors.

Jan 1, 1973

By J. Greg Sanchez

The New South Ferry Terminal in the New York City Transit system represents an important milestone for the city. This is the first station designed and built in the 21st century. The design of the fire safety system included relying on Computational Fluid Dynamics to analyze the dispersion of heat and smoke, and modelling of people egress to determine the egress requirements. The project also looked into how to protect the structure from the heat exposure in order to meet the fire rating requirements. This paper provides an overview of the fire safety design approach taken to design the new South Ferry Terminal station in lower Manhattan and looks into fire modelling, structural fire protection, and station evacuation.

Jan 1, 2008

By Fogarty J. G H

Ausmelt Technology has a unique capability of removing the impurities, phosphorus and sulphur, from the feed materials to the process. Sulphur is removed to the gas phase almost completely because of the interactions of ore and coal in the reaction region at the top surface of the slag bath. Phosphorus is removed to the slag phase, with both basic and higher, controlled iron oxide levels in slag being achieved in the process. The significance of these features of the process relate to the production of pig iron with very low levels of these impurities for the further processing to steel, and to the treatment of high phosphorus and high sulphur raw materials. The marketability of pig iron and the raw materials are discussed in relation to this feature of Auslron.

Jan 1, 1999

By Carmel Bofinger, Maureen E. Hassall, David Cliff, Eric Stemn

Incident investigation is of utmost importance in most high-risk industries and is often used to improve organisational safety. This study was undertaken to examine the content of past incident investigation reports to determine the effectiveness of the incident investigations. The study uses a semi-quantitative method to assess the effectiveness of incident investigations in the Ghanaian mining industry by evaluating the quality of past investigation reports. The assessment tool consists of five elements with several indicators and rating scales for assessing the quality of an investigation report as a measure of the effectiveness of the investigation. The method was applied to 304 investigation reports of three Ghanaian large-scale gold mines, and the results correlated with incidence rates of the mines to determine if any relationship existed. The results showed that the mines differ significantly in the quality of their investigation reports, suggesting differences in the effectiveness of their investigations. In addition, the incidence rates of the mines negatively correlated with some elements of the assessment tool. In general, the method was found useful and revealed areas where improvement is needed.

By Carmel Bofinger, Maureen E. Hassall, David Cliff, Eric Stemn

Incident investigation is of utmost importance in most high-risk industries and is often used to improve organisational safety. This study was undertaken to examine the content of past incident investigation reports to determine the effectiveness of the incident investigations. The study uses a semi-quantitative method to assess the effectiveness of incident investigations in the Ghanaian mining industry by evaluating the quality of past investigation reports. The assessment tool consists of five elements with several indicators and rating scales for assessing the quality of an investigation report as a measure of the effectiveness of the investigation. The method was applied to 304 investigation reports of three Ghanaian large-scale gold mines, and the results correlated with incidence rates of the mines to determine if any relationship existed. The results showed that the mines differ significantly in the quality of their investigation reports, suggesting differences in the effectiveness of their investigations. In addition, the incidence rates of the mines negatively correlated with some elements of the assessment tool. In general, the method was found useful and revealed areas where improvement is needed.

By M Rattenbur, A B. Christie, S C. Cox

A new minerals initiative to increase the level of understanding of New Zealand's mineral resources and to promote the development of minerals began earlier in the year in a partnership pilot-project between Crown Minerals and the Institute for Geological and Nuclear Sciences (GNS). The project aims to gather a set of comprehensive geoscientific data and build a series of digital GIS packages to highlight New Zealand's mineral prospectivity. The pilot study was carried out at a regional scale, and is focussed on mesothermal gold mineralisation in the South Island. A significant amount of geological data and information was sourced from open file technical reports held by Crown Minerals and from various databases held by GNS and has now been compiled into a single GIS dataset, which will soon be made freely available to interested parties. In addition to this comprehensive data compilation, prospectivity modelling using Weights of Evidence techniques was undertaken to highlight those areas likely to contain ore deposits. It is clear from this study that the South Island of New Zealand remains highly prospective for mesothermal gold mineralisation. Many of the highly prospective areas, which also contain historic mine workings, remain open for exploration. The study not only highlights these areas, but also other areas where the potential for similar mineralisation exists, in all likelihood with no surface expression. The study has also highlighted the value of many of the open-file technical reports held by Crown Minerals and the need to carry out additional studies using this and other available data at a more detailed level, possibly as the basis for a web-based minerals information system.

Jan 1, 2002

By T Hughes

The Gekko InLine Pressure Jig (IPJ) was unleashed on the World gravity separation market in 1996 and has since sold over 150 units in applications including tin, diamonds, silver, coal, garnet and gold. During the past twelve years the knowledgebase of the best applications and capabilities of the IPJ has greatly increased. Improvements to the original IPJ design have included engineered ceramic ragging in specific gravities from 1.6 to 5.0, full automation and improved designs of feed presentation and tailings and concentrate handling systems. The IPJ has been found to be able to handle a wide feed size range and recover mineral at liberation size without significant addition of water to the mass balance. Test work carried out during full-scale operation of the IPJ has shown the IPJ can recover diamonds down to 0.5 mm, sulfides down to 0.3 mm and gold down to 0.1 mm which greatly expands its application in the mineral processing industry. A significant volume of data now supports the symbiotic benefits of an IPJ and flotation circuit combination to pre-concentrate an ore and minimise downstream processing requirements.

Jan 1, 2008

By David G. Winter

The first test pile for the carrier pier and south wharf at NAVSTA Puget Sound was driven on December 27, 1989, and the final pile was tested on February 26, 1990. Implementation and modification of the test pile program were done by the owners (WESTDIV and ROICC-Everett), the engineers (ABAM and Hart Crowser), and the contractor and his subcontractor (General Manson Joint Venture and GRL). The site is located as shown on Figure 1. SUMMARY OF THE SOIL CONDITIONS A soil profile along the pier is shown as Figure 2. The soil units can be generalized as follows: ? Upper Silts - Fill, sandy silt, and clayey silt extending from the mudline to an elevation of about -80 feet; ? Intermediate Sand - A medium dense to very dense silty sand unit which is about 30 feet thick near the shore, but thins and disappears offshore; ? Lower Silts - Sandy silts and clayey silts in a medium stiff to stiff condition; ? Deep Sand - A very dense overconsolidated sandy soil encountered at an elevation of about -145 feet.

Jan 1, 1990

By Org de Wet

This paper summarises the strategy for selection between a two module coal plant incorporating large, but less equipment, and a three module coal plant with more but smaller equipment. The two options were evaluated in terms of three main categories: ? Size ? size of the equipment and the effect on the process efficiency as well as the difference in physical dimensions of the plant to accommodate the larger equipment; ? Cost ? capital savings between a two and a three module plant, processing the same ROM (run-of-mine) tons per hour (t/hr); and ? Practicality ? in terms of constructability of the plant, safety of using larger equipment and maintainability of the equipment. Decisions that were taken to reduce the risk associated with size, cost and practicality on the chosen option of a two module plant will be highlighted.

Jan 1, 2006

By A. Moskowitz, L. S. Redmerski

The corrosion resistance of stainless steels can be strongly affected by surface treatments. Changes in corrosion resistance can relate to surface composition, integrity and stability of the passive film, and to surface profile (roughness). Operations producing oxidation at the surface, such as annealing, heat treating, and welding, can result in a chromium-rich scale and a chromium-depleted metal surface. In order to restore full corrosion resistance, chemical or mechanical clean-up techniques must remove not only the oxide, but also a very thin layer of metal. Laboratory and field test studies show that these factors are particularly significant in less highly alloyed steels. Annealing stainless in a reducing atmosphere (bright annealing) avoids chromium depletion, but as-bright-annealed material does not display optimum corrosion resistance in certain environments. Electro passiva-tion can be applied to improve pitting resistance without significantly changing bright surface appearance. Potentiometric studies show that electropassivated material also displays significantly greater resistance to breakdown of passivity in acid solutions. The application of special surface finishes for appearance purposes can affect corrosion resistance. Roughness is a key factor. Samples of related appearance but with different surface profiles can show significant differences in corrosion resistance. Thus nonreflec-tive stainless with a relatively smooth surface produced by a special rolling process is much superior to material chemically etched to a similar low reflectivity. THE corrosion resistance of a stainless steel is affected by other factors in addition to its bulk composition and metallurgical structure. These other factors include those relating to the specific chemical and physical condition of the steel's surface. This paper will consider certain aspects of surface condition in relation to corrosion resistance. In particular, studies will be described on the effects of oxidation encountered in heat treating or welding operations, of passivation after bright annealing, and of different surface finishes. EFFECTS DUE TO OXIDATION When stainless steels are exposed to high temperature in an oxidizing environment, as in annealing or welding, the oxides formed are relatively rich in chromium. As a consequence of oxidation, the metallic layer directly beneath the scale may be low in chromium to some very thin but finite depth.1"8 Such a change in chromium content could lower the corrosion resistance at the surface, whether or not the oxide layer is removed. Studies were performed relating to the effect of oxidation and chromium depletion produced during annealing and welding on the corrosion resistance of stainless steels. The nominal compositions of steels used in this study and others are given in Table I. A) Annealing Studies on 17 pet Cr Steels. 1) Effects of Pickling Treatments. Studies were performed to investigate the corrosion resistance of air annealed type 430 stainless as a function of the amount of electrolytic pickling after annealing. The material used in this study had been air annealed and electrolytically pickled in the mill. All scale had been removed, and yet the material showed unusually poor corrosion resistance. Laboratory electrolytic pickling studies were performed to determine whether additional metal removal from the surface would improve corrosion resistance. Electrolytic pickling was performed in a sulfuric acid bath using various conditions of bath acidity, temperature, time, and current density. The samples were then rated for corrosion resistance in a ferric chloride spot test. For this spot test, a solution was prepared by dissolving 10 g of FeCl3 . 6H2O, 5 g of NaCl, and 2.5 ml of concentrated HC1 in 200 ml of water. An area on a specimen was cleaned and a drop of test solution was placed on the prepared area. After 5 min, the drop was rinsed off and the area wiped dry. The spot was then rated between 1 and 5 by visual comparison with standard spots. The numerical rating of the standard spots can be described as follows: 1—No clouding of surface; 2—very slight clouding of surface; 3—slight clouding of surface; 4—moderate clouding of surface; 5—strong clouding of surface. A rating of 1 or 2 was considered to have passed the test, a rating of 4 or 5 represented failure, and a rating of 3 was considered borderline. The severity of etching in this test has been related to the actual chromium content at the surface.4 Etching (clouding) occurs on type 430 stainless (rating of 4 to 5) when the surface chromium content is 14 pct or less. The effects of current density and retention time when electrolytically repickling this material in 6 pct sulfuric acid are shown in Fig. 1. Increasing the cur-rent density or retention time improved corrosion resistance as measured by the spot test. Similarly, increasing acid concentration of the bath or bath tem-perature was found to improve corrosion resistance. The conditions making for improved spot ratings resulted in increased metal removal, regardless of specific pickling conditions used, Fig. 2.

Jan 1, 1970

The Ngakuru zeolites are located about 20 km south of Rotorua and comprise a number of deposits dispersed along several fault lines. Relatively recent volcanic activity (250,000 years ago) resulted in ash depositions that vary in depth and mineralogy. Subsequent variable thermal alteration intensities generated predominantly clinoptilolite and mordenite zeolites with a range of physical characteristics. Typically the zeolites have low density (650 kg/m3), have high liquid (60% of dry weight) and odour absorption characteristics, and a high affinity for soluble cations (CEC =: 100 meq/100 g). Traditional kitty litter and oil absorbency markets are being expanded. New opportunities in waste and potable water treatment, organic and synthetic slow release fertilisers, use as a light weight aggregate for speciality concretes, and pozzalome activity are currently being researched.

Jan 1, 2000

By G. S. Austin

The St. Cloud Mining Company extracts clinoptilolite about 6.5 km south of Winston, Sierra County, New Mexico. Production is about 18,000 mt/year. Natural zeolites are good adsorbents for positively charged solutes such as ammonium. St. Cloud’s production is used in animal hygiene, animal feed, environmental mitigation, air and water filtration, and other applications. By a simple chemical treatment with a surfactant, zeolites can also be modified to adsorb negatively charged solutes such as nitrate and arsentate, and neutral organics such as solvents and fuel components. These surfactant-modified zeolites are used in treating groundwater contamination, stormwater runoff, and solvent vapors from painting operations.

Jan 1, 2002

In the 1980s and?90s the gold mining industry in South Africa came under pressure from the continued poor dollar gold price and escalating Rand based costs, furthermore the external impacts on the industry were changing. Thus, the Chamber of Mines (COM) shifted its focus away from many historical areas of support towards the new industry challenges in safety and health, labour markets, environmental responsibility, mineral rights legislation and social responsibility. During 1997 the lack of funds and the changes facing the tertiary institutions were often subjects of discussion at the various sub-committee meetings. The Metallurgical Sub-committee of the Chamber Education Fund or the Sub-committee of Consulting Metallurgists as it was known identified the need for the funding structure to change with the times. Up to this time the Chamber of Mines operated an Education Fund that supported mining industry academic departments at various South African tertiary institutions; these funds were derived exclusively from the country?s gold and coal mines the basis of Chamber membership. Funds of less than R5 million per annum were available for distribution by the three disciplinary sub-committees of mining, metallurgy and geology.

Jan 1, 2003