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Advances in Thickener Feedwell Design via Computational Fluid Dynamics Modelling

Sep 13, 2010

By Qiang Zhang

Hybrid composites are fabricated by adding two reinforcements into matrix materials so that the expected excellent properties can be achieved through the combined advantages of short fibers, and different size particles (micron or submicron), which provide a high degree of design freedom. In this paper, hybrid preforms were produced with the different size reinforcement of the Al2O3 particles and short fibers. The Al-Si alloy-based hybrid composites were fabricated by preform-squeezing casting route. The structure and performance of composite materials were studied with the Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). The results show that the reinforcements, both particles and fibers, distribute homogeneously in the matrix materials, and the properties of composites are found to improve in comparison with the matrix Al-Si alloy.

Jan 1, 2009

Recent and on-going studies on the leaching of gold, the properties and activity of carbon, developments in the elution of gold from carbon, and methods of recovering gold from solution are reviewed. Emphasis is placed on Australian contributions, and their impact on gold metallurgy. Consideration is given to the future development of selective solvent extractants, ion exchange resins or alternative reagents for cyanide.

Jan 1, 1987

By E. Shekarchi

A year after the Soviet Union invaded Afghanistan and replaced President Amin with their choice, President Karmal, Afghanistan remained in turmoil. In some respects, the political and economic situation in Afghanistan was no better by the end of 1980 than it was preceding the December 1979 invasion. The Government faced widespread and growing alienation and resistance, virulent factionalism within the ruling party, and an acute shortage of material. The mining sector of the country did not fare better either; the only raw material produced in a significant amount was natural gas, which was exported mainly to the Soviet Union. No statistics on production of other minerals and materials were available by yearend. Most of Afghanistan's gas production was from the Hodja-Gugerdag Field, southeast of Shibarghan. The gas flow from this field had been about 300 million cubic feet per day since 1961. An estimated 230 to 250 million cubic feet per day of Hodja-Gugerdag's production was moved by pipeline across the Amu-Darya River into the Soviet Union. Most of the remainder was transmitted eastward to a 105,000-ton-per-year fertilizer plant and an electric power station built near Mazar-i-Sharif with Soviet assistance. After the Soviet invasion, the second gasfield, Djar-Kuduk, in the Shibarghan area, was brought under production. This field, which will produce about 200 million cubic feet per day, consists of four gas zones in the Jurassic and lower Cretaceous zones between 3,000 and 8.500 feet deep. The gas has a high hydrogen sulfide content, with considerable carbon dioxide, A new treatment plant was built at Djar-Kuduk by Soviet technicians under a turnkey contract at the end of 1980. It is believed that most of the Djar-Kuduk's initial flow will be sent to the Soviet Union.

Jan 1, 1982

By R. A. Franks, G. F. Friel, J. C. Edwards, L. Yuan

Two mine-fire experiments were conducted in the National Institute for Occupational Safety and Health's (NIOSH) Safety Research Coal Mine (SRCM) at the Pittsburgh Research Laboratory (PRL) which demonstrated that smoke from diesel-fuel fires of 500 kW and 660 kW heat-release rates in a return airway can develop, without causing a complete air flow reversal, into a roof layer that can migrate upwind forming a counter flow to the primary airflow in a crosscut. Subsequently, smoke can penetrate into an intake airway and create a hazardous atmosphere in the intake airway upwind from the fire. Visibility conditions less than 13 m were created by the smoke in the intake airway downwind from the crosscut. Modeling of the event with a three-dimensional, time-dependent, computational fluid dynamics (CFD) program correctly represented the smoke movement.

By Don W. Lake

Of all the blast monitor& instrumentation systems and techniques av&able today, highspeed photography and videography remain as the most valuable, stand alone, diagnostic techniques to evaluate full scale blasts in the mining and explosives industries. Highspeed image data, coupled with information from other instrumentation systems, such as continuous VOD records, seismographs, laser surveying systems, refraction seismographs, etc. can eIiminate many assumptions about what actually took place in a blast. Thus, diagnostic confidence in evaluating both good and bad blasts is increased, and optimum blast designs are achieved considerably faster when compared to the trial and error approach or relying on just the experience factor.

Jan 1, 1992

By C. J. Badenhorst

The scope of this project was to research, develop and eventually produce a personal occupational hygiene and safety exposure monitor system to assist in recording and analysing various stress factors that could affect the health, wellness and safety of employees, i.e. that could result in injury or ill health of workers, create stress build-up within individual workers that could negatively affect worker alertness and safety, and, may even result in permanent disability or death. Utilized systems at the time were all reactive, whereas the DOHEMS (Proactive Digital Occupational Hygiene and Safety Exposure Monitoring) System enabled the measurement of exposure (and associated risk) in a proactive manner via real-time exposure and digitized recordings. The idea of the development was to create a unit that is so cost effective, small and light that every worker can use a system on a daily basis. The development will eventually replace current, bulky and expensive monitoring equipment. The device must be a portable battery operated device and monitor the immediate working environment by periodic sampling for vibration, noise, toxic gasses (NO/NOX/CO/VOC, etc.), body temperature and heart rate. The samples must be time and date stamped, utilizing a real-time clock (RTC) synchronized with the closest regional secondary time source and related to synchronized real-time video captured samples. These samples are then recorded onto a rugged non volatile storage device with the capacity to store a vast number of samples covering the entire working shift of eight (8) hours plus. The system has been fitted with a clear visual local alarm indication system, indicating any excessive exposures or stresses, for the worker?s supervisor to respond to. This system allows for a pro-active approach. The system is also a wireless system (to the external environment) so as to not affect the mobility of an employee and flameproof to allow for use in explosive environments. Keywords: safety, digital, exposure, monitoring, proactive.

Jan 1, 2010

By Américo Pérez

La política ambiental de Centromin Perú S.A. promueve el aprovechamiento de los recursos minerales sin comprometer la capacidad de las futuras generaciones para satisfacer sus necesidades y desarrollo. En ese sentido, los objetivos de la empresa comprenden la protección de la salud y seguridad pública, la prevención del medio ambiente a largo plazo y el uso productivo de las áreas afectadas, retornándolas a su estado inicial. Por ello, el presente trabajo señala los avances en la resolución de los pasivos ambientales de la ex unidad de Casapalca y el Programa de Adecuación Ambiental de la unidad de Morococha, en actual operación.

Sep 13, 2001

As part of its research and development activities concerning coal mine operational/emergency communications sys terns, the Bureau of Mines commissioned several contractors to conduct electromagnetic (EM) noise studies and measurements that would aid the development of improved coal mine operational/emergency communications systems. The bulk of the noise studies and measurements were conducted in 1971. The Pittsburgh Mining and Safety Research Center (PMSRC) inherited the responsibility for monitoring the electromagnetic noise activities by mid-to-late 1971, and initiated a review and evaluation of the current and planned electromagnetic noise work. Arthur D. Little, Inc., (ADL) was asked by PMSRC to assist it in performing this review and evaluation by placing stronger emphasis on certain tasks of existing Contract No. H0122026. This technical memorandum report presents the findings, conclusions, and recommendations of our review and evaluation of the electromagnetic noise measurements of the five contractors we were asked to examine. Our review and evaluation effort included meetings and telephone discussions with technical staff of each contractor; serving as Technical Discussion Leader of a "Contractor's Round Table Meeting on EM Noise, Surface and Subsurface, Operating and Non-Operating Mines" called by the Bureau of Mines; examination and discussion of contractor reports and relevant open literature; sample verification calculations; and the documentation of our findings, conclusions, and recommendations by this report.

Jan 1, 1972

By F. G. Scott

This document is a proposed program plan for mining environmental research to be conducted by the U.S. Bureau of Mines in support of industrial oil shale mining and processing. This program plan is one of three research alternatives being considered by the Bureau, each based on a different level of anticipated funding. This report documents the mid funding level program plan.

Jan 1, 1980

By A. C. Johnson

This circular is one of a series published by the Bureau of Mines describing mining and beneficiation methods and costs at various mining operations throughout the United States. Inclusion of the Abbott mine in this series is of particular interest, as the complex geology and the character of the deposits make their exploitation a unique operation. The mine operates on a high-cost, comparatively small-scale basis, and only the persistence of an aggressive management has enabled it to maintain its rank among the major mercury producers of California. Rising costs and decreasing metal prices, which continuously threaten the low profit margin, are reflected in increased efficiency of operation. This report summarizes past operations and describes, in detail, the geology and ore deposits; exploration and mining methods; and furnacing and condensing operations. It covers the entire operation from initial exploration to the actual production of mercury. Comparative production costs for 1944 and 1958 are of special interest.

Jan 1, 1962

By James R. Aggson

This Bureau of Mines report describes floor heave ground control problems that have been encountered in a new underground coal mine in West Virginia. Previous experience in the coal seam, the results of physical property investigations, and in situ rock stress determinations are discussed. The apparent cause of the ground control problems is the existence of a high, biaxial, horizontal stress field coupled with a floor member that has time-dependent deformation characteristics, A theoretical analysis of the failure process is developed. The analysis is assisted by finite element techniques. Mine design recommendations based on this analysis are presented.

Jan 1, 1978

By William H. Pomroy

The Bureau of Mines, through a 4-year program of combined in-house and contract research, has developed the necessary hardware and software technology to provide rugged, reliable automatic fire protection for surface mining mobile equipment. One element of this program was a continuing effort to help foster rapid mining industry acceptance of the technology by keeping end user costs reasonable. This report is an analysis of the economic impact of surface mining mobile equipment fires and the cost benefit of utilizing automatic fire protection systems to abate these losses.

Jan 1, 1982

By R. A. Kearns

Biennially the Bureau of Mines issues a list of equipment that has been accepted as approved or permissible during the two calendar years immediately preceding the date of publication of the listing. By so doing the mining industry is kept informed of the availability of the latest equipment for safe use underground. This list supplements Bulletin 543, Permissible Mine Equipment Approved to January 1, 1953; Information Circular 7722, Permissible Mine Equipment Approved During the Calendar Years 1953-54; Information Circular 7840, Permissible Mine Equipment Approved During the Calendar Years 1955-56; and Information Circular 7957, Permissible Mine Equipment Approved During 1957-58. This list includes equipment meeting those standards that have been revised since Information Circular 7957 was .issued. Schedule 16E,4 a revision of Schedule 160, was approved May 19, 1960.

Jan 1, 1961

By J. A. Hudson, X. D. Pan

A rock mass responds to excavation according to the properties of the intact rock, the network of contained discontinuities and the susceptibility of the rock mass to weathering. Large deformation often occurs when one of these components causes the rock mass to have a low strength relative to the stress conditions. Analysis of such large deformations forms a significant feature of current numerical modelling in rock mechanics. A practical large deformation problem of roadways in a coal mine is described, demonstrating the requirements for improving numerical techniques. The development of a numerical model is then summarised with particular attention to several concepts pertinent to large deformation analysis in geomechanics. A numerical case study is presented in which the developed finite-element model is used and the results are compared with the in-situ measurements. Conclusions are drawn for rock engineering that are also relevant to both civil engineering and mining engineering projects

Sep 1, 1991

By P. E. J. Pitfield, S. D. G. Campbell

The regional structure of shear and deformation zones in the belt, which is recognisable in plan view on Landsat TM images, is interpreted in terms of a conjugate-shear model. Gold mineralisation is related to this framework at a variety of scales. The principal recurrent structural geometries hosting deposits at mines such as Motapa, Durban, Charliesona, Cecil, Sunace, Turk group, Queens district, How, Peter Pat, Matabele Sheba, Goodenough, Old Nic and Bushtick are associated with shear zones and folds and include conjugate systems (shears, shear intersections, kink sets), side-step systems (en echelon segmentation, duplexes, monoclinal inflections, antiform-synform couplets) and interactions of the two. Linear sections of shear zones are generally poorly mineralised. The same geometries are identifiable on all scales from local to regional, so sections of regional structural lineaments or areas within mines should be prioritised for further investigation or development on the basis of the gold-bearing geometries observed to be dominant locally

Apr 1, 1996

By D. A. Wilson

A cyclic leaching process was developed for selectively leaching and recovering cadmium from nickel-cadmium scrap battery waste. The six major steps in the process are the following: (1) washing the plates to remove KOH electrolyte, (2) roasting at 550° to 600° C to oxidize metallic cadmium and decompose cadmium and nickel salts, (3) leaching with an ammonium nitrate solution, (4) precipitation of the leached cadmium from solution as cadmium carbonate using CO2 gas, (5) removal of CO2 from the lixiviator by adjusting to pH 4.5, heating, and evacuating the system, and (6) removal of small amounts of leached nickel from the lixiviator using a solvent extraction technique. The regenerated lixiviator is then recycled to leach additional plates. Cadmium extraction was 94 percent and the cadmium carbonate product contained 0.14 percent nickel and 0.12 percent cobalt impurity. The leached plates were smelted to a high nickel-low iron alloy with no detectable amounts of cadmium.

Jan 1, 1971

Longwall mining has existed in Utah for more than half a century. Much of this mining occurred at depths of cover that significantly exceed those encountered by most other U.S. longwall operations. Deep cover causes high ground stress, which can combine with geology to create a coal burst hazard. Nearly every longwall mine operating within the Utah’s Book Cliffs coalfield has been affected by coal bursts.

Jan 7, 2020

By G. Richards

Research shows that having more women in the top mining jobs can bring bottom-line benefits. Mining companies are starting to embrace the need for greater gender diversity at board and senior management levels, figures and examples are given.

Jul 1, 2015

By D. C. Bailey, D. I. Hodson

Paper presented at the annual joint meeting of the IMM and IMinE held in Harrogate, 31 January 1991. The Neves-Corvo copper-tin mine is the highest-grade large-tonnage copper operation in the world and is now arguably the most significant producing base-metal mine in Europe, rating in the top ten world producers of both copper and tin. A description is given of the initial exploration work and the development of the project from the orebody discovery in the Iberian Pyrite Belt of southern Portugal in 1977 to full operating capacity in 1990. The chronological account includes discussion of the main organisational, financial, technical and environmental decisions and of the various difficulties encountered, and the challenges of the future are identified. The project was brought in on schedule and within budget

Jan 1, 1991