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By B. P. Sereda

The properties, characteristics and phase structure of chamotte refractories produced with the usage of mullitecorund chamotte and caoline have been given. The comparison of new refractory C-45 obtained by us and refractory C-43 produced by traditional method has done. The physical-chemical properties of refractories is reviewed. The visual porosity, density and pore characteristics of given refractories was calculated. It is established that C-45 has the less gas permeability then C-45 that gives melting units more stability. The petrographical microstructures of refractories have been done. The main phase structures and their influence on refractories properties have been observed. It is established that refractories with mullitecorund chamotte adition has more advantages then refractories gained by traditional method and can be applied to melting units.

Jan 1, 2010

By Terry J. Close

In 1985, at the request of the U.S. Bureau of Land Management, the U. S. Bureau of Mines studied part of the 56,623-acre South McCullough Mountains Wilderness Study Area (NV-050-435) in order to evaluate its identified mineral resources. The area studied is located in Clark County, NV, about 30 miles southwest of Boulder City. No mineral resources were identified. The study area contains the eastern part of the unorganized McCullough Mountain (McClanahan) mining district which has had no recorded production. Between 1911 and 1982, 23 lode claims were located in the part of the mining district that is in the study area; four of these claims are currently held by assessment (1986). A total of 11 mineral sites were found and examined during the U.S. Bureau of Mines investigations; 26 mine workings were examined. Of the 11 sites, four are within the study area, and seven are nearby. Of the seven nearby sites, six are adjacent to the west boundary and consist of precious-and base-metals bearing vein occurrences in metamorphic rocks. The seventh site is near the east study area boundary, and consists of a tungsten-bearing vein occurrence that is also in metamorphic rocks. The four sites within the study area consist of vein occurrences in metamorphic rocks that contain silver, gold, arsenic, lead, zinc, and copper. The veins at these four sites are too small and low grade to be classified resources; however, there are indications that three of the sites may have silver and gold resources at depth. Detailed delineation of the veins, and determinations of tonnages and grades are needed. This would entail additional mapping and sampling, trenching and drilling, and opening inaccessible workings.

Jan 1, 1987

By C G. Ryan, T P. Mernagh, S R. Hunns, R A. Both, R R. Large, J B. Gemmell

 The Hellyer and Mt. Chalmers deposits are mound-style volcanic-hosted massive sulphide (VHMS) deposits in Australia. Textural, petrographic and microthennometric investigations of fluid inclusions in the Hellyer stringer system indicate that Type I, primary, liquid-vapour inclusions are 10 - 15 J.UIl in size, and yield homogenisation temperatures of 170 - 220¦C in early 2A veins, 165 - 322¦C in main-stage 2B veins and 190 - 256¦C in late-stage 2C veins. These data suggest a waxing and waning thermal history. However, the average salinity remained between 8 - 11 NaCl equiv. wt % in all Stage 2 veins. At Mt Chalmers, Type I inclusions up to 20 urn are found in quartz from the mineralised zone, and these inclusions yielded homogenisation temperatures of 160 - 268¦C and salinities of 5 - 8 NaCl equiv. wt %. Laser Raman spectroscopic (LRS) analysis indicates the presence of CO2 (<1 mole %) in the Hellyer and Mt. Chalmers VHMS systems. Semi-quantitative SEM/WDS microprobe analyses of fluid inclusion decrepitates indicate that the Hellyer and Mt Chalmers ore fluids were enriched in potassium and calcium but depleted in magnesium relative to seawater. PIXE microanalysis of fluid inclusions in quartz also indicates a significant base metal concentration in these fluids. Cation composition and higher salinities relative to seawater suggest that recycled seawater alone cannot be the sole source of the ore fluids. High base metal content and the presence of CO2 in the fluid inclusions imply that magmatic input of ore metals during seawater leaching of the footwall volcanic pile is a distinct possibility.

Jan 1, 1995

By Darrell L. Beddard

The Loma Prieta earthquake occurred on October 17, 1989 at 5:04 PM, Pacific Daylight Time. It measured 7.1 in magnitude and was felt from Los Angeles north to the Oregon state line and east to western Nevada. The epicenter of the earthquake was located along the San Andreas Fault, in the Southern Santa Cruz Mountains just north of the City of Watsonville, California. It was the largest earthquake to occur in the San Francisco Bay area since the 1906 earthquake. A total of 87 aftershocks of Magnitude 3.0 or larger were recorded within 21 days after the seismic event. As a result of this earthquake thirteen State-owned and five locally-owned bridges were closed to traffic. Three of the most publicized State-owned structures closed to traffic were Struve Slough Bridge, San Francisco-Oakland Bay Bridge and Cypress Street Viaduct. Struve Slough Bridge was twin slab bridges that collapsed and were rebuilt and open to traffic three months after the earthquake. San Francisco-Oakland Bay Bridge experienced collapse of upper and lower spans at Pier 9 and was reopened to traffic one month after the earthquake. The Cypress Street Viaduct experienced collapse of 48 bents that resulted in the upper roadway falling onto the lower roadway.

Jan 1, 1996

Upgrading and Removing Phosphorus from Low-Grade and High Phosphorus Containing Iron Ores

Sep 13, 2010

By Manuel Pérez-Tello, María M. Salazar-Campoy, Óscar Rodríguez-Hoyos

A common problem during the operation of the Kaldo furnace is the formation of accretions and blockage of the injection lance due to splashing. This typically occurs during the processing of anodic slimes for the production of doré. In this work, a 1:7 scale model of the Kaldo furnace currently in operation at Metalúrgica de Cobre, Mexico, was built in transparent acrylic plastic. Water and colored oil were used to represent the doré and slag, respectively. The model was used to determine the maximum penetration distance of the injection lance under a variety of experimental conditions at room temperature. Input variables included two types of oil, rotation speed, inclination angle, and the fraction of the vessel volume occupied by the liquids (φ). A mathematical correlation for the dimensionless maximum penetration distance of the injection lance d ∗ as a function of φ, the Froude number of the liquids in the vessel (Fr), the Reynolds number of the gas jet (Re), and the oil-to-water kinematic viscosity ratio (η)was developed. Reasonable agreement between the calculated and experimental values was obtained. Digital images showed that splashing was caused by the turbulent gas jet impinging upon the free surface of the liquids, whereas the cascade effect was negligible. The results of this work have been useful to improve the operation of an industrial Kaldo reactor.

By Forrest T. Moyer

Injury experience at coal mines and mechanical-cleaning plants (excluding officeworkers ) in 1967 was 222 fatal and 10,115 nonfatal disabling work injuries during an exposure time of 241.8 million man-hours. These injuries occurred at a frequency rate of 42-75 per million man-hours worked; the severity rate was 7,699 days lost or charged per million man-hours. Each of these general measures of injury experience was lower than similar data recorded for 1966. Employment at 6,885 coal mines and 569 mechanical-cleaning plants, excluding officeworkers, averaged 139,312 men in 1967. The average number of days worked was 220. Coal production totaled 560.8 million short tons, at rates of 2.32 tons per man-hour and 18.32 tons per man-day. A total of 2,779 onsite officeworkers at coal mines and mechanical- cleaning plants worked 5.2 million man-hours in 1967 without a disabling work injury.

Jan 1, 1972

The Effect of Ionic Strength of Plant Water on Valuable Mineral and Gangue Recovery in a Platinum Bearing Ore from the Merensky Reef

Sep 13, 2010

Analysis for pillar extraction potential (A-PEP) is an intelligent tool, which could be used as a preliminary output indicator when considering the secondary extraction of regional support pillars in the Witbank and Highveld coalfields of South Africa. The safe and economic extraction of underground coal pillars is of paramount significance and importance to the South African coalmining industry to ensure continuity of supply of this fossil fuel. Pillar extraction practices in South Africa have been responsible a significant proportion of safety and fatality statistics in relation to its relative output (less than 5 per cent of total South African coal production) and, as a result, research was undertaken in local pillar extraction operations and extended to similar operations in New South Wales, Australia to assess a way forward for pillar extraction in South Africa. It was found that, although little in the way of new technologies has emerged in this field in the recent past, significant contributions could be made in the field of risk analysis to obtain a generic design methodology for pillar extraction in South Africa. The resultant A-PEP tool to assess pillar extraction potential is based on certain physical, risk and economic factors, which combine to indicate operational success in terms of economic, health and safety attributes. At the time of A-PEP?s development there was alack of operating underground coal pillar extraction operations, which made it difficult to validate its applicability. Since then, however, A-PEP has been successfully tested and validated against two unique underground coal pillar operations, which is the discussion of this paper. One operation is situated in the Witbank coalfield and is extracting pillars, which are 20 years old and at a depth of 80 metres below surface, while the other operation is situated in the Highveld coalfield-which is extracting 6 month-old-pillars underneath a massive dolerite sill at a depth of 220 metres. A-PEP has shown that its predictive nature is consistent the workings at both operations, irrespective of their unique conditions, and as such it can be successfully used as a mine planning tool. The A-PEP mine planning tool thus represents a positive step toward an integrated approach to underground coal pillar extraction when considering legal and operational aspects, which could form the basis for legislative guidelines when considering the future of pillar extraction in South Africa.

Jan 1, 2005

By Mark Kennedy

New technology projects, particularly those involving first-of-a-kind metallurgical facilities, have a poor track record of achieving their overall financial targets, as they incorporate technological risks in addition to normal project risks. Traditional project management tools focus on risk from concept development through implementation, but typically fail to address the additional risks associated with a new technology project including slow start-up, slow ramp-up, and failure to achieve design performance (quality or throughput). These additional risks affect future cash flows produced by the project and hence its value, typically measured as net present value (NPV) or internal rate of return (IRR). Common accounting practice is to reduce the present value of future cash flows by applying a chosen discount rate, often reflecting the corporation?s cost of capital. This discount rate does not contain an allowance for technological risk, which is often underestimated or misunderstood by both the financial and engineering project managers. This paper will focus on the topic of project risk and new technology, and how these play a role in the probability of achieving the predicted future cash flows. By properly addressing technological risk in the form of risk-weighted returns, marginal projects can be prevented from proceeding, while sound projects can be given the additional time and resources required to achieve the optimal level of front-end-loading (the level which returns the maximum risk-weighted net present value). A simple set of mathematical tools should enable engineers and financial professionals to establish a common level of understanding, thereby leading to a more accurate assessment whether a new technology project is ready to pass through its next level of approvals.

Jan 1, 2013

By Bjöm Böhle

Top-down construction (or cut and cover construction) is providing important advantages when comparing with conventional construction techniques for commercial developments with deep basements, underground car parks or near surface infrastructure and traffic tunnels. Main features are substantially reduced restrictions to surface usage, avoidance of intervention with adjacent property, provision of rigid substructures resulting in minimal deforma­tions and settlements and, last but not least, accelerated construction pro­gramme. The present contribution illustrates the construction method in general and elaborates in detail on the special foundation works for a major urban commercial high rise development requiring a six level basement structure.

Jan 1, 2006

Contents.SummaryIntroductionSituation, climate, topographyHistorySize of depositsPrevious investigationsGeological History of AreaMap compilationHistorical summaryNature and Significance of Granitic RocksSynchronous granitesMain subsequent granitesSignificance of types of bathylithsGeological StructureNorth-south anticlineCross-foldingFormation of channelwaysHydrothermal Depth-Zoning at CobarAssociation of Ores with PorphyryOrigin of replacement porphyriesTransgressive porphyriesSummary of ore-porphyry relationshipsSource of the Copper and GoldProspecting Targets, Cobar-NymageeGeneral ApplicationBroken HillThe Bendigo FieldKalgoorlie-Coolgardie, Western AustraliaConclusions

Jan 1, 1950

By Willem Le Roux

Occupational health and safety is regulated by statute and common law. South Africa has, like many other countries, legislated extensively on occupational health and safety. Despite the body of legislation, the common law continues to play an important role as far as it concerns contractual, delictual and criminal liability. Two major Acts regulate occupational health and safety viz. the Occupational Health and Safety Act, No. 85 of 1993 (?OHASA?) and the Mine Health and Safety Act, No. 29 of 1996 (?MHSA?). The MHSA applies to mines and works as defined and related aspects. OHASA applies to other industries but does not apply to employers and workplaces to which the MHSA and certain matters covered by the Merchant Shipping Act, No. 57 of 1951 apply. See section 1(3) of OHASA. 2 The employer?s health and safety obligations in terms of the MHSA 2.1 Section 2(1) of the MHSA provides amongst others, as follows: ?The employer of every mine that is being worked must: (a) ensure, as far as reasonably practicable, that the mine is designed, constructed and equipped: (i) to provide conditions for safe operation and a healthy working environment (ii) ... (b) ensure, as far as reasonably practicable, that the mine is commissioned, operated, maintained and decommissioned in such away that employees can perform their work without endangering the health and safety of themselves or of any other person?.

Jan 1, 2011

This paper reviews the development and operation of a small underground tin mine in NE Tasmania. Tin mineralisation was discovered in the Lottah area in the 1880s with early alluvial and eluvial workings leading to the development of large low grade open pit operations. Apart from short lived activities operations ceased in 1915. Intensive exploration in 1978 - 1981 outlined substantial tonnages of low grade tin mineralisation (0.2% Sn) of open pit material. An underground ore body was also located (800 000 tonnes 0.6 per cent Sn). Spectrum Resources Australia Pty Limited acquired a 98 per cent interest in the property in 1988. Mine and mill development began in early 1989 based on an underground mine utilising trackless mining using room and pillar with fill stoping. The milling circuit involves primary jaw crushing, Barmac secondary crushing to 1 mm, Mogensen and DSM screens with jigs and tables to make a wet concentrate. Final tin concentrates are produced by high tension and magnetic separation. Planned production rates are 500 t/day with a mine life of six to seven years.

Jan 1, 1990

The Leigh Creek Coalfield is owned and operated by the Electricity Trust of South Australia to supply fuel to the Northern Power Station. To supply electricity at lowest cost, a costing and decision process that establishes the role of the Leigh Creek Coalfield in the overall system planning and operation is required. The costing is integrated in that it is based not just on a particular mine plan but on the wider need to supply a particular electrical demand. The detail costing has evolved over time from manual to main-frame computer to microcomputer techniques. Now there is a choice between fast consistent costs and a slower but more detailed and flexible costing.

Jan 1, 1990

This chapter summarizes data on crude mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are tables that show the principal mineral commodities exported from and imported into the United States, and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of volume I and in the State chapters of volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at 'any of several stages of extraction and processing, the stage of measurement used In this chapter is what is normally termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the product of auxiliary processing at or near the mines.

Jan 1, 1977

By M. P. Board, J. K. Whyatt, T. J. Williams

The U.S. Bureau of Mines has been conducting a series of rock mechanics investigations at the Lucky Friday Mime in the Coeur d'Alene Mining District of northern Idaho. In the present study, the energy release rate (ERR) index was used to evaluate three underhand stope backfill parameters--cement content, density, and placement gap-to determine their influence on rock bursts. This index provides a relative measure of the likelihood of rock bursting for a given rock mass. It is known that the elastic idealization of the rock mass inherent in this method causes underestimation of stope closure and hence underestimation of the influence of backfill on rock bursting. However, this evaluation still showed that (1) changing from present practice to one in which backfill was omitted altogether would increase the ERR by 42 pct and (2) perfect placement of backfill would reduce the ERR below present practice levels by 28 pct. The easiest step toward perfect placement would be elimination of the placement gap, which accounted for half of the difference in ERR between present practice and ideal placement conditions. There was no indication that increasing initial fill strength through increased cement content would affect the ERR.

Jan 1, 1992

By Dachun Liu, Baoqiang Xu, Bin Yang, Yong Deng, Heng Xiong, Xiumin Chen

"In this paper, vacuum distillation technology has been employed to study the possibility and regularity of separating copper and enriching lead, silver and other valuable metals from copper- based multi component alloys. The result of experiment indicated the practicability of vacuum distillation dealing with copper base complex multi-component alloy to separating lead and silver, when the vacuum distillation temperature was 1637K, distillation time was 60min; residual gas pressure was 20-30Pa, the removal rate of silver was 95.86%, of lead was 99.63%; the evaporation rate of copper was 0.745%. The removal rate of arsenic, antimony and tin respectively were 83.09%, 48.12% and 24.54%. Vacuum distillation method is applicable for dealing with the copper-based multi component alloys, silver and lead can realize effective recovery.IntroductionCopper generally go with lead mineral, therefore, to remove copper from lead becomes an inevitable link in lead smelting. Dross from removed copper usually contains lead, arsenic, antimony, tin and noble metal silver. In abroad, soda ash-iron dust is adopted to process copper dross of this kind. The outcomes of this process are lead matte, wet lead, scoria smoke dust etc[1~5] The dominant components of all the outcomes are copper and lead. Moreover, in the process of tin smelting, copper contained by-products are produced, such as, crude tin alloy, tin lead electrolytic anode slime and so on. Copper content of all the products are ranging from few percentages to several tens percentage. Those products, no matter merge into main producing process, or separate treatment cost losses of valuable metal. For one hand, the containing of copper of outcomes from pyrogenic attack is less than 50%, for the other hand, a lot of valuable metal need to be processed, which increase the cost of retrieve."

Jan 1, 2013

By T Albinson

Mexican epithermal deposits can be broadly grouped into two types based on their contained metals, distribution, associated igneous rocks and fluid inclusion compositions. Silver-gold deposits (eg Tayoltita) mostly occur in the western part of northernMexico where host rocks consist of Eocene, intermediate composition volcanic and intrusive rocks; fluid inclusion studies indicate that mineralising fluids were <300¦C and dilute (=3 eq. wt. % NaCl). In contrast, silver-lead-zinc deposits (eg Fresnillo) mostly occur in the central part of northern Mexico where they are temporally associated with Oligocene-Miocene volcanic rocks and intrusions of felsic composition, but commonly hosted within underlying Paleozoic-Mesozoic sedimentary rocks; fluid inclusion studies indicate that mineralizing fluids ranged from 200 to 400 ¦C and were saline (=10 eq. wt. % NaCl). The distribution of these two deposit types, crosscutting major crustal sutures, and the close spatial-temporal relationships between mineralisation and magmatism, together suggest that magmatic processes were more important in the formation of mineralising solutions, as a source of both ligands and metals, than the segments of crust hosting deposits.

Jan 1, 1995

By Jai Ghosh, Aprad E. Torma, Roger Guay

The catalytic effect of ferrous ion in the industrial biohydrometallurgical heap and dump leaching processes is explained. During the bacterial leaching of metal sulfides, ferric ion will partly be hydrolyzed and a variety of sols, gels, amorphous and/ or crystalline mono- and polynuc- lear hydroxo- and sulfato complex species formed, especially by olation and aggregation reactions. There are many problems associated with these iron precipitates especially in the purification of leach solutions. The present study will discuss the iron precipitation reactions; gives kinetic and thermodynamic evaluations of the effect of temperature on pyrite and ferrous iron oxidation; and reports on the tolerance of heavy metal ion concentrations by Thiobacillus ferrooxidans.

Jan 1, 1989