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By Joseph Ribak

Grunerite asbestos (amosite) has been shown in epidemiological and experimental animal studies to cause lung cancer, mesothelioma and pulmonary fibrosis commonly referred to as asbestosis. An overview of the human and experimental animal studies describing the health hazards of grunerite asbestos (amosite) is presented. Of the many human studies describing the health hazards of asbestos, only three factories using mainly, if not exclusively, grunerite asbestos (amosite) have been studied. The first is a series of reports on a cohort of 820 workers from a plant located in Paterson, NJ. Among this cohort, 18.7% died of lung cancer and 17 mesotheliomas occurred. The Paterson factory closed in 1954 and moved to Tyler, Texas where it operated until 1972. Among the 1130 former workers in the Tyler plant 6 mesotheliomas were reported with 15.8% lung cancer mortality. The third grunerite asbestos (amosite) exposed cohort was an insulation board manufacturing facility in Uxbridge, United Kingdom. Here 17.1% of the workers died of lung cancer and 5 mesotheliomas occurred. The lung content from 48 Uxbridge workers was analyzed by analytical transmission electron microscopy for mineral fibers. The relationship between grunerite asbestos (amosite) concentrations in the lung correlated with grades of fibrosis and asbestos bodies and was lower than the concentration found in the cases with malignant tumors. The lung cancer cases contained more grunerite asbestos (amosite) than mesothelioma cases, and in the cases of non-alignant disease the concentrations were still lower. In both types of malignancies the concentration of grunerite asbestos (amosite) was very high-over a billion fibers per gram of dried lung tissue. Occupational exposure to airborne concentrations of between 14 and 100 fibers of grunerite asbestos (amosite) per milliliter after 20 year latency causes marked increases in lung cancer, mesothelioma and pulmonary fibrosis (asbestosis). © 2007 Elsevier Inc. All rights reserved. Keywords: Grunerite asbestos; Amosite; Mesothelioma; Asbestosis

Jan 1, 2007

By Jean-Sébastien Lambert, Joseph Kabuya, Richard Simon

Managing a highwall failure risk in an open pit mine by controlling and mitigating the impact of vibrations produced by blasting operations is key to achieving safe and cost-effective operations. The impetus behind this study was the risk of multiple bench failures in an open pit mine that was detected by Slope Stability Radar (SSR) following blasting at the foot of a highwall. The unstable high wall was over 140 meters(459.3 ft)high and 200 meters(656.2 ft)wide. The quantity of associated material was estimated at 3,000,000 metric tons(3,306,934 US tons). The overall slope angle was 44 degrees. In order to continue mining without causing the highwall to fail, this study was initiated as part of a risk management plan to mitigate this major risk by identifying mitigation measures related to blasting operations and assessing the response of the rock mass to each blast. Identifying blasting mitigation measures consisted of optimizing blasting parameters to avoid failure of the highwall. First, a signature hole operation was carried out to obtain seismic records that were georeferenced and associated with known single charges. The method used made it possible to determine the propagation velocity of the P-waves associated with the various lithologies studied and to calculate, from the geomechanical properties of the rock masses, the maximum peak particle velocities to be respected. Subsequently, the targeted area of operation was modelled with the I-Blast software in order to optimize the firing sequences to be used according to the different lithologies present. The model also made it possible to optimally predict the particle velocities associated with each blast and ensure compliance with the previously determined peak particle velocity limits. The assessment of the rock mass’s response using SSR consisted of defining alarm thresholds and an intervention plan for various possible alarms as well as quantifying the damage to the highwall from blasting. Controlling the impact of blast vibrations on the highwall’s stability was successful, as the mitigation measures used during mining did not accelerate the highwall’s movement. No upward trend in the stabilization time of the rock mass was observed by the SSR after each blast. Post-blast geotechnical inspections and analysis of post-blast deformations in the highwall also did not reveal significant damage to the highwall as a direct consequence of the blasting.

By Francis Church Lincoln

"INTRODUCTION During the period from September 18 to November 27, 1944, the Bureau of Mines conducted an investigation and exploratory churn-drilling program in an area immediately north of the Crow Branch Diggings, a district lying approximately 2 1/2 miles southwest of the town of Livingston in Grant County, Wisconsin.The work was undertaken as part of a general Bureau of Mines investigation of the zinc-producing area of southwestern Wisconsin at a time when all effort was being made to increase the production of metals important to the Nation's war prrgram.Although no mining has been done in the district in recent years the Crow Branch Diggings were an important source of galena and may be found today in the dumps remaining from old surface-mining operations.The Bureau of Mines undertook an exploratory churn-drilling program on the northwestern projection of the general strike of the digging in a zone where subsurface,lead and zinc mineralization had been reported from drilling done in the early 1900's."

Feb 1, 1947

By M. Hagfors

When establishing an underwater testing site for the energy measurements of the explosives, the dimensions of the measuring pool have to be measured to find out what is the maximum weight for the test charge. Secondly one has to decide the distance between the pressure gauge and the shooting point. Thirdly the pool has to be calibrated because of the reflections of the explosions by measuring the bubble periods of the calibration charges. The calibration shots can also be used to estimate the minimum weight of the explosive charge for the reliable energy measurements by calculating the shock, gas heave and total energy values and their standard deviations.

Jan 1, 2007

By Mark M. Petersen

As part of the addition of eight new combined cycle generating units at the Florida Power & Light Sanford Plant, 2,129 piles were to be installed. The existing plant elements were supported on driven piles, and the variation in pile lengths during previous work, as well as available subsurface information, indicated a complex stratigraphy. At the request of the owner, the designer/construction manager developed a program to evaluate the use of pressure-grouted displacement piles. A pre-design load test program in areas that represented the apparent extremes in subsurface conditions indicated that the system was feasible; however, the presence of existing features that were to be demolished later precluded the clear delineation of subsurface conditions in advance of construction. A contract was negotiated with the pile installer based on the best estimate of potential pile lengths, with modifications to pile lengths to be set based on additional exploration. A total of 52 cone penetration soundings and five load tests were performed immediately prior to and during pile installation to establish correlations between the CPT data and pile performance. Pile depths were set based on these correlations. Pile installation was completed 6 weeks ahead of schedule and 15 percent under the original budget estimate. This paper documents the evaluation of pressure-grouted displacement piles as an emerging technology, and illustrates the benefits of a close working relationship between the owner, designer, and pile contractor at a site with variable subsurface conditions.

Jan 1, 2002

Vein swarms in metamorphic terranes such as the Otago Schist Belt, New Zealand provide evidence of past hydrothermal flow systems leading to fault initiation and reactivation. A major episode of hydrofracturing and fluid redistribution occurred during early Cretaceous exhumation of the schist belt. As a result, presently exposed lower greenschist facies greyschists in NW Otago are pervaded by abundant quartz-filled hydraulic extension fractures with associated normal faults hosting quartz¦scheelite¦gold mineralisation. Once the effects of Cenozoic folding have been removed, a regional subhorizontal schist foliation contains an aligned array of subvertical hydrofractures striking NNW, striking parallel to a set of low-slip conjugate normal faults; the array extends over an area >1500 km2 and over a depth interval >5 km. The hydrofracture array comprises a mesh of interlinked extensional-shear and pure extension veins. These veins show mutually cross-cutting relations. Extensional hydrofracturing apparently preceded the development of major throughgoing normal faults. Low-displacement normal faults are infilled with laminated quartz (¦ scheelite) veins (

Jan 1, 2002

By Ed Coulter

Nevada has a population of 1.2 million people of which only 21% or 312,rIXl are native born Nevadans. he population between 1980-1990 grew a record of 389%. and ls the fastest growing state in the union. While only 2.5% of the total population are direct employees of the mining industry, excluding Reno and Las Vegas, one out of every three people living in Nevada work for a mining related industry.

Jan 1, 1991

By John F. MacDonald

This paper describes the driving of a 400 m long by 25 m diameter highway tunnel through sensitive, overconsolidated silts and clays. The design concept requires the construction of the permanent support system, consisting of 24 concrete filled perimeter drifts, before excavating the mass core. General construction procedures used during the construction of the perimeter drifts are described.

Jan 1, 1985

GOLD has played a part in the development of Australia. The total yield exceeds SIX hundred million pounds sterling, while the glamour of gold-mining and the unfailing demand for the product have enhanced its influence. The production is still considerable, but the yield is less than one-quarter of that twenty years previously, while the number of men employed has dropped from 70,000 to 11,000. Not only has there been a marked decline in production, but it is anticipated that thisdecline will continue, and continue more markedly. It is therefore desirable to ascertain the causes of the decline and inquire into means for diminishing or preventing it.The problem under discussion is far from being only local. Finlay states: The grand feature of the history of the business has been the progress of an economic cycle unfavourable to gold milling. The USA yield fell from $101,000,000 to $44,000,000.South Afriea has for some time produced one-half of the world's gold; yet in the Mining and Scientific Press of 11th February, IH22, General Smuts is quoted as saying that if the premium disappeared entirely 24 out of 34 mines would shut down. The solution, however, might be either general eg, a great advance in the metallurgy of gold; or local eg, a bonus; but before discussing any of the proposed solutions it will be advantageous to review the situation.STATISTICS OF THE PAST AND PRESENT PRODUCTION OF THE WORLD AND OF AUSTRALIAThe inquirer soon finds that there is a good deal of uncertainty, and that much care is needed in collating figures. In some cases a considerable part of the output is not officially reported, and returns...

Jan 1, 1924

By Brett Zernich, Michael Krulc, Brett Robinson

This paper provides an account of the efforts undertaken to construct the Northeast Interceptor Sewer (NEIS) project, which is a portion of a much larger program in Los Angeles, California to upgrade the city’s wastewater facilities. The project consisted of a number of elements, including both soft ground and rock slurry wall shafts, drilled shafts, soft ground EPBM mining, rock TBM mining, large diameter pipe placement, and underground structure construction. The need to complete the project under strict schedule constraints, in addition to the challenges of underground construction in congested urban areas, necessitated the work be undertaken with the proper balance of state of the art equipment, and thoughtful planning. The paper will detail the means, methods, and equipment used on the project, as well as discuss several of the unforeseen conditions encountered during construction.

Jan 1, 2005

Some important mineral fields are referred to in discussing the formation of placer deposits in Australia.Testing methods include boring by hand, with percussion rigs, with auger and pit digging drills, and by vibro drilling.Sampling errors are minimized by the use of correct techniques and equipment for boring, sampling and sample dressing. A hypothetical set of data is used to demonstrate the final process of evaluation, and somerelevant taxation provisions are discussed.

Jan 1, 1966

By Peter Bigwood

Whether drilling through tough clay or breaking rock, or facing the most severe conditions including mixed face ground, perched water and running and flowing sands, working under-ground certainly comes with no shortage of challenges. In an environment where the unknown is faced on a daily basis, tunneling contractors must be able to rely on their equipment to get the job done properly. Not only that, their equipment must comply with two of the highest priorities: safety and efficiency. In addition to being the number one concern, a proven safety record provides additional benefits to a company. A safe work environment serves as a key component to company growth, including the ability to remain competitive in bidding and maintaining higher-level, more challenging projects.

Jan 1, 2012

The following paper describes the refining practice for the production of lead, silver and gold at the works of The Broken Hill Associated Smelters Pty. Ltd., Port Pirie, South Australia.The refinery is situated on the wharf frontage and is built parallel with it. The refinery occupies an area of approximately 3380 square yards. (Fig. 8)There are two buildings, one containing the softening and de-silverising sections, measuring 225 ft. x 57t ft., while the other building, which measures 225 ft. x 90 ft. covers the de-zincing, lead moulding, retorting, cupellation, and dore parting sections. (Fig. 1)The retorting, cupellation, and dore parting sections are completely isolated from the rest of the plant by strong small-mesh wire gratings welded to steel uprights. The dore parting plant and generator room are further isolated by a brick wall, built up to the roof. The two main buildings are steel structures, with outer walls and roof of "Robertson" corrugated sheeting; the side and end walls are open for some distance above the ground, and this, coupled with the high roof which is 50 ft. from ground level, ensures the free access of air and light. Conditions are such that operators work in a clear atmosphere.

Jan 1, 1937

Effect of Grinding Media on the Flotation of Sulfide Minerals

Sep 13, 2010

By Jeffrey L. Dean

Now in its twenty-fifth year, the ISEE has grown to more than 4000 members representing 75 countries. The Society and its 35 chapters in the US, Canada and Australia work to educate the public about our industry, provide forums for the exchange of explosives technology, serve as a repository of explosives information, offer expert help to governments, develop standardized methods and terminology, and promote research and education by, creating and conducting certificate and trainktg programs and encouraging the teaching of the safe and controlled use of commercial explosives.

Jan 1, 1998

By Z. Xiao, A. R. Laplante

"The recovery of gold by gravity from grinding circuits differs from virtually all other gravity recovery approaches in that stage (or unit) recoveries are low, typically 1 to 5%, but overall recoveries are generally in the 25 to 60% range, because individual gold particles are presented many times to the primary recovery unit. Full-scale recovery is difficult to predict from benchscale tests. Further, maximizing metallurgical recovery is generally not the primary objective, because of the more efficient downstream recovery circuit (flotation or cyanidation). In this paper, a new concept, the gravity recovery effort, is presented to assist in the design and optimization of gold gravity circuits. It is defined as the product of the circulating load treated by the primary gravity unit, the recovery of this unit, and the gold room recovery. Predicted gold recovery is linked to the recovery effort, the size distribution of gravity recoverable gold (GRG), the dimensionless retention time in the mill and the partition curve of GRG. A case study of economic optimization of the gravity recovery effort is presented. INTRODUCTIONPredicting gold gravity recovery from grinding circuits has always been a hit-and-miss exercise. The problem can be traced to the highly variable gravity recoverable gold (GRG) content of ores, high GRG circulating load, fraction of the circulating load treated, and performance of primary gravity recovery and gold room. Typical values, highs and lows are shown in Table 1."

Jan 1, 2001

By L Baumgardner, A. V. Castelli

Barite In 1987, United States mine production of barite increased 15.870, consumption (sold or used by grinding plants) increased by 6.97, and imports are estimated to have fallen by 19.57. World mine production decreased by 137, according to the US Bureau of Mines. The value of US produced barite, fob mine, decreased 1.4%, according to the Bureau. The declared value for cif US port of all imported unground barite during the first 10 months of 1987 decreased from $39.02/t ($35.40 per st) to $37.16/t ($33.71 per st), the Bureau stated. Nevada continued to be the leading US producer of' barite with 637r of the total. It is followed by Georgia, Missouri, California, Tennessee, and Montana. The Bureau of Mines estimates 657 of the US mine production was used as a weighting agent in drilling fluids. The remaining 35°/r was used in barium chemicals, glass or as a filler. Most of the production from Missouri, Georgia, and Tennessee was used in the non-oilfield sector. This sector continued to increase. Of the total consumption (used by grinding plants and chemical manufacturers), it is estimated that 8070 was used in drilling fluids and 2017( in the non-oilfield sector - barium chemicals and fillers in paper, plastics, and glass. The tonnage consumed in the drilling fluids market increased slightly. But the average number of rotary rigs operating decreased from 964 in 1986 to 936 in 1987. This is the lowest number of operating rigs reported since 1949. The increase in consumption in this sector is due to an increase of rigs operating in the US Gulf and other higher consumption areas over 1986. Crude barite imports were estimated to be down by 19.5% in 1987. Still, they accounted for 637 of the barite consumed in the US. During the first 10 months, China continued to be the leading exporter to the US with 86.970, followed by Mexico with 10.997, and Morocco 2.107(. About 5Y of the imported ore was used in the nonoilfield sector. Ground barite imports dropped from 19.8 kt to 8.8 kt (21,800 st to 9800 st) in 1987. Of this amount, 1.4 kt (1598 st) was used in drilling muds and the remainder of the non-oilfield use. During 1987, a few more grinding plants that supplied the drilling fluid market were closed. Along the US Gulf Coast, there are 13 operating plants versus a high of 31 in 1981. Cameron Offshore reopened its grinding plant at Cameron, LA. New Riverside Ochre Co. of Cartersville, GA, purchased a jigging-washing plant in Missouri and plans to place it in operation this year on a new deposit near Cartersville, GA. Milpark purchased Hughes Drilling Fluid in 1987 and operates under Milpark. US mine production will probably stay about the same as 1987. Price increases in the 10 % range for imported ore are expected due to water freight and the weak dollar. Baker Hughes estimates the average number of operating rotary rigs at 1070. A slight increase is expected in the non-drilling fluid market (chemicals, glass, and filler). Bauxite and alumina L. Baumgardner, US Bureau of Mines Domestic bauxite production in 1987, expressed as dried equivalent, was 581 kt (640,400 st), a 14% increase over 1986. US mine production amounted to less than 170 of total world production. Virtually none of the domestic bauxite was consumed in the production of primary alumina metal. About 30% of the bauxite produced by US mines was calcined to produce 117 kt (128,970 st) for use in abrasives, catalysts, chemicals, proppants, and refractories. Most of the uncalcined bauxite was refined to specialty aluminum oxide (alumina) forms. Metallurgical grade bauxite was imported from 10 countries in 1987. Principal suppliers of the 9.8 Mt (10.8 million st) were Guinea (4270), Jamaica (3501,), Australia (127), and Brazil (57). The average value, delivered U.S. ports, cif, as reported to US Customs Service, was $29.50/t ($26.76 per st). Calcined refractory grade baux-

Jan 6, 1988

Study on Influence that Styrene-Phosphoric has on the Surface Property of Rutile Minerals

Sep 13, 2010

By D. W. R. Haysom

"I AM CONSCIOUS of the honour you pay me by having invited me to address you on the subject of the Rehabilitation of the Sydney Steel Corporation. The true architect of the revival and rehabilitation is Robert Burns Cameron. Because of the numerous myths which have grown up around what seems to be the miracle of the revival of the Sydney Steelworks, I propose to go back to the time when they came under the full control of the Province, on the 1st of January, 1968. Late in 1967, the decision was taken by Premier G. I. Smith to keep the Steel Plant running for at least another year, in an endeavour to see whether the enormous losses being sustained by Dosco could be reduced to a level which would permit their continuing operation. When that decision was taken, Dosco was to continue management until the 30th of April, 1968, and in the intervening period, the Provincial Government would seek management of the right calibre to ensure that an objective view of the Steelworks operations could be secured. By a combination of circumstances which can only be described as most felicitous, the man selected for the task was R. B. Cameron. He very quickly determined that to permit Dosco to continue management of the Steelworks until April 30 could only result in heavy losses to the Province and a consequent deterioration in the already critical financial position and a declining morale of the worke"

Jan 1, 1972

By Christopher J. Bise

INTRODUCTION The control of nuisance water in a mine is extremely important; left uncontrolled, nuisance water can have a severe effect on haulage, ventilation, production, and the health and safety of miners. To control water in mines, a four-step process is followed: (1) prevention, (2) collection, (3) transportation, and (4) treatment. This chapter will be devoted to the collection and transportation of mine water because prevention is usually dictated by pre-mining conditions and initial planning, while treatment is variable and highly site specific. A mine drainage system is nothing more than a collection of gathering points (sumps), machines that impart energy to the fluid (pumps), transportation ducts (pipes), and control devices (fittings, valves, etc.). A pump does not pull the fluid up the suction pipe; atmospheric or external pressure pushes the liquid up the suction pipe to the pump. All references in this chapter will be to centrifugal pumps, due to their popularity for mine drainage. PUMP CHARACTERISTIC CURVES The performance of a pump is plotted on a graph as an indication of its characteristic. To develop the data points, a test facility similar to that shown in Fig. 1 is established. The calibrated Venturi meter is used to measure quantity, the Bourdon gage measures pressure, and the wattmeter measures power input. Various discharge pressures are obtained by throttling with a gate valve in the discharge pipe. Quantity and power are measured at each of these pressure levels, giving the necessary data for plotting the characteristic curves. Fig. 2 shows a typical characteristic curve for a centrifugal pump. Notice that pressure is measured as so many feet of vertical water column above the outlet level, or head. Knowing the quantity (in gallons per minute), head (in feet), and power input (brake horsepower), the pump's efficiency can be plotted based upon the following relationship:

Jan 1, 1986