Search Documents

By Gregory Owen Lewis

The use of gravity concentration as a means of recovering the 'free' gold component from alluvial and milled ore products is widely used and is receiving increasing attention, particularly with the introduction of the centrifugal-type concentrating units. Because of ever-increasing mining and processing costs and a decline in the gold price, it has become important that the recov­ery efficiency from concentrates is improved so as to increase the yield of bankable gold from this primary recovery step. This paper outlines an alternative hydrometallurgical approach aimed at achieving overall gold recoveries in excess of 98%, together with the elimination of any secondary residue streams which, in the case of conventional treatment methods, require re-processing. An adaptation to the Minataur™ Process technology is being applied with the proposed method, incorpo­rating the pre-treatment of the concentrate, oxidative leaching of the pre-treatment residue, followed by precipitation of a high­purity gold. This route is seen to have application in all scales of operation. Selected results from laboratory-scale testwork are presented to highlight the discussion.

Jan 1, 1998

By J. G. Pippenger

The mining industry has been Australia?s major economic driver over the past decade, contributing 8% to Australia?s Gross Domestic Product and 26% of Australian Stock Exchange Market capitalisation. Australia is the world's leading exporter in coal, iron ore, alumina, lead and zinc; and second largest in gold and uranium. While driving the economy, this resource boom has also created a demand for professional and operating talent that has far outstripped the capacity of Australia?s 21 million residents. I moved to Australia some 10 years ago and have not looked back. This unique island continent with its mix of Indigenous and diverse immigrants ? many still proud of their convict ancestry ? has offered life long memories both professionally and personally.

Jan 1, 2011

By Christian Wawrzyniak

An analysis method for modeling compensation grouting based on the finite element method is presented. By this method the design parameters of compensation grouting, grouting pressure and grouting volume, can be evaluated. Also the subsidence of a building due to tunnel driving as well as the lifting of the building by compensation grouting can be simulated. The stress changes in the tunnel lining and in the foundation of the building are computed as well. The application of the analysis method is demonstrated on two examples for compensation grouting in combination with construction of tunnels.

By Jr. Wallace

This paper describes an analysis performed to determine the cool-down time of drifts in the prospective commercial nuclear waste repository in volcanic tuff at Yucca mountain, Nevada. Two emplacement methods are currently being considered at Yucca mountain. The reference configuration stores the high-level waste in short vertical boreholes, and the alternative configuration stores the waste in long horizontal bore-holes. After emplacement operations for each emplacement drift are complete, the drift will be closed off from continuous ventilation. Given time, the radioactive decay of high-level waste will increase the rock temperature around access and emplacement drifts. Air cooling may be required to re-enter these drifts. The paper discusses the analysis procedure and computer programs used to evaluate the time to cool a drift to acceptable environmental conditions 50 years after emplacement of high-level waste. Key assumptions to the analysis are presented. The results of the study show that cooling either vertical or horizontal configuration emplacement drifts is possible in a reason-able period of time.

Jan 1, 1988

The use of controlled recirculation can be dated back to the early 1930s. Although this method has been applied in many mines since then, a generalized comprehensive network analysis is still lacking. This paper presents a unique approach in which the ventilation network with a controlled district recirculation is divided into two subsystems: a main subsystem and a recirculation subsystem. The subsystems are analyzed individually and the results and their relationships are then integrated into discussions of the total ventilation system. The analysis of the recirculation subsystem is facilitated by introducing a non-dimensional parameter A, which represents the ratio of the air quantity for the working face to that for the subsystem. As a result, fan and regulator pressures and air power for various recirculation arrangements can be effectively expressed as a function of A and the subsystem air quantity. Numerical examples are included.

Jan 1, 1995

By D. C. Mahon, P. G. Sagert, M. R. Legeyt

INTRODUCTION Public opinion, over the effect of industrial development on the environment, has required government to institute guidelines for the protection of the environment both during the development of and after the decommissioning of mines. In no other area of mining has this requirement been more consistently applied in recent times than in the development of uranium mines. Uranium mines have been a focal point because of the very real uncertainties associated with the detrimental effects of radionuclides and the possible hazards of radiation. In order to determine if there is an environmental effect caused by a development or the storage of the mine waste as tailings, it is necessary to know what the quality of the environment was prior to the production of the tailings. This is the reason for baseline data programs. It is neither technically nor economically feasible to completely define the environment in any given region. Therefore, judgement decisions must be made prior to the development as to what aspects of the environment are more likely to be affected by the presence of the tailings, and to what degree. These decisions have evolved over a period of time based on information generated from existing facilities, scientific research, and the development of strong public opinions. This process is not static, but evolves with the growth of information and the technological developments which permit greater control of industrial pollution and waste management. A well-designed baseline program will reflect changes in science, technology and public attitude, even in advance of government regulations to enforce policy changes. RATIONALE FOR PREOPERATIONAL BASELINE STUDIES There are three distinct phases to be considered in the construction of an environmental assessment for a uranium mine tailings containment facility. I. Pre-operational 2. Operational 3. Post-operational (decommissioning and long term).

Jan 1, 1980

Researchers at National Institute for Occupational Safety and Health (NIOSH) are investigating how fiber-reinforced shotcrete mix designs can be extrapolated from proven designs employing wire mesh. This paper explains the results of round determinate panel tests and relates the flexural strength and toughness of fiber-reinforced shotcrete to known energy absorbing properties of wire mesh. The energy absorbed with central deflection is strongly influenced by the amount of fibres. The higher the energy absorption the more load cracked shotcrete can support. Two types of fiber-reinforced shotcrete were investigated, one with steel fiber and another with polyfiber. The residual load supported in Round Determinate Panel Tests can be matched with the strength of wire mesh, thus providing equivalent bag strength values for fiber reinforced shotcrete panels. There is also evidence of a panel crack width comparison to the load holding capabilities of the fiber in the shotcrete mixes. In practice, this provides designers with a method for comparing the ground support provided by fiber-reinforced shotcrete with that supplied by wire mesh.

Jan 1, 2010

By C. Clark, R. Pakalnis, B. Seymour, L. Martin, M. Stepan, M. Roworth, C. Caceres

The National Institute for Occupational Safety and Health (NIOSH), Office of Mine Safety and Health, Ground Control Engineering Branch is investigating the use of shotcrete in weak rock mass mines with the objective of reducing fatalities and injuries resulting from rock fall accidents. When shotcrete is used as part of a multielement ground support system, there is a need to know the support characteristics that the shotcrete contributes to the overall system. To quantify the support provided by the shotcrete, flexural strength tests were conducted with two common, commercially available fiber-reinforced shotcrete (FRS) mixes using the round determinant panel (RDP) test method, ASTM C 1550. A portable RDP test machine developed by NIOSH researchers was used to determine the peak flexural load and residual load capacity for a steel FRS and a synthetic poly FRS that were sprayed using dry mix procedures and equipment. Besides the flexural strength and loading behavior determined from these tests, a method was also developed for measuring the width of cracks exposed on the underside of a shotcrete panel during a RDP test and relating these measurements to residual load values. Quantifying the peak flexural load and residual loads of a shotcrete mix through on site testing at a mine and visually assessing the loading cycle and load-carrying capability of the shotcrete applied to underground workings will improve mine safety by providing a better assessment of the stability of shotcrete supported entries.

Jan 1, 2010

By J. T. Crawford

The purpose of this paper is two fold. It will: (1) examine leasing analysis as a project evaluation criterion, and (2) compare the cost of leasing with other methods of financing. The use of leasing has grown extensively in recent years as a method of obtaining equipment. The computer industry has been highly dependent upon leasing from its earliest days to dispurse its equipment to the customer, while airlines and railroads acquire large segments of their aircraft and rolling stock by leasing. Over the last few years the mining industry has leased haulage trucks, bulldozers and other equipment of similar nature.

Jan 1, 1974

By A. Sadik

The proliferations of media sources and non-profits organizations in Ghana have put the negative impacts of mining on the ?spot?; this has resulted in public outcry about mining. Although, the gold mining industry has responded by implementing several voluntary measures to ensure sustainable mineral development, these critics label such measures as ?green wash?. In this study, a content analysis of newspaper articles of the Ghana Web Database was carried out after the collection of a total of approximately 900 newspaper articles from it. The data were statistically analyzed to chronologically examine the main media view points and the changing perception of mining issues as reported by private and public media. The results showed government, mining industry (Gold), illegal miners and non-profit & community groups as the main media view points and total of twenty-eight related gold mining sustainability issues. The findings of this study could be used by the gold mining companies to improve upon the communications of their unknown sustainable mineral development measures and to design effective communications and education programs for the public.

Jan 1, 2009

By L. M. English

In the past 30 years, the research arena has changed significantly in all fields, mining included. The relative representation of the topics of research, how the research is performed, and who has performed the research have all changed significantly over these decades. Although there are a lot of subjective ideas concerning these changes, and there is a fair amount of anecdotal "analysis," there has been no actual study of these trends to verify the facts. The period studied is divided into six five-year periods for the purposes of comparison. Some of the trends analyzed are as follows: ? Co-authorship ? Research areas ? Research sponsors ? Cooperative efforts

Jan 1, 1995

By Joseph D. D?Annunzio

The report on cut and cover construction as assembled by the Organization for Economic Co-operation and Development covered 17 different countries based on a total of just under 400 individual replies of which about 30% of the replies were from the United States. In general, the review of replies to the questionnaire led to the impression that cut and cover construction is a very inadequate method which needed many improvements. This unfavorable judgment, however, resulted in the manner in which questions were asked rather than in the method itself, It can be concluded that the cut and cover construction method has proved itself as an excellent method and that it has reached a high degree of technological perfection, but inadequacies stilt exist, and for purposes of complete evaluation, comparisons with mining tunnelling methods should be carried out. The principal problem in cut and cover construction is the interaction during construction between the construction process and the existing use of the surface and subsurface environment. The greatest impediments to cut and cover construction have little to do with the physical works being constructed, but more with creating a site in which the work can be performed. Utility relocation, traffice maintenance, and protection of existing structures are major problems for the construction contractor, and too frequently receive insufficient attention in preconstruction planning and design. Some OF the areas in which research should be undertaken are as follows:

Jan 1, 1970

By Richard J. Robbins

This paper is presented with particular reference to the findings of the OECD Advisory Conference on tunneling held last July in Washington D. C. A great deal has been said about the Conference in the past few months, but it may be appropriate to review briefly the background and objectives of the Conference to better understand how the mining community can relate its underground excavation problems to the results of the Conference. OBJECTIVES OF THE OECD CONFERENCE The world demand for tunneling (the term tunneling is used here loosely to include almost all forms of underground excavation) is expected to grow at an in- creasing rate. During the decade of the ?70's, the demand is expected to at least double by comparison with the previous decade. Much of this increase in demand will be due to the rapid growth of urbanization around the world. As urban populations grow larger and denser, the conservation of surface land and the quality of the environment become more important. This aspect of the increasing demand poses a difficult challenge to those who must plan and implement urban development.

Jan 1, 1970

By Eugene F. Casey

An immersed tube tunnel is one which is composed of elements that are prefabricated in a dry dock or on shipways, usually away from the actual tunnel site, floated into position and then lowered into a preexcavated and graded trench below a body of water. The elements or segments are then connected to each other under water, and the entire immersed tube tunnel covered with a protective blanket. Because water is essential, this method of construction offers advantages in a relatively limited field. By the very nature of the method, lowering elements to the bottom of an underwater trench, immersed tube tunnels are primarily used for crossing bodies of water, such as rivers, bays, straits, canals, etc. Although this method of construction was first used for a subaqueous railway crossing under the Detroit River in 1906-1910 and again in 1912-1915, for a four track subway tunnel under the Harlem River in New York, the reason immersed tube tunnels construction has not been used more extensively is simply a matter of economics. Bridges, compressed air tunnels and similar structures could be constructed at a lower cost.

Jan 1, 1970

By Sriram Padmanabhan, Jan M. Mutmansky

The subject of quartz occurrences in respirable coal mine dusts has been of increasing concern in recent years. The primary impetus for this concern has been provided by better measurement technology that has detected an increased number of mines with high quartz content in their respirable dusts. This paper presents the results of statistical analyses of quartz levels in multi-stage impactor samples from eighteen different coal mining sections located in Pennsylvania, West Virginia, Ohio, Illinois, Kentucky, Colorado and Utah. The quartz and kaolinite determinations were then determined by combining impactor stage loadings to provide larger dust masses and applying the infrared spectrometry procedure outlined in Bureau of Mines/MSHA Method P7. The results will be presented using two categories of data collected during two separate phases of the research: (1) quartz concentration data from mines where quartz was known to be present in relatively high concentrations, and (2) quartz concentration data from mines chosen at random. The aspects of the occurrence of quartz in coal mine airborne dusts that will be reported include the size dependence of the quartz content, quartz variations with location in the mining section, and variations due to mining region. The results of the study show a strong pattern of size dependence of the quartz content in mines for which high quartz concentrations exist. A similar, though less pronounced, pattern exists in mines chosen at random. Quartz levels appear to have a varying relationship to section location and strong geographical patterns do not appear to exist in the data collected. Kaolinite content was found to be similar to that of quartz with patterns that are somewhat more consistent.

Jan 1, 1989

By J. B. Seymour

This paper provides an overview of the current use of backfill for ground support in underground metal mines in the United States and a summary of recent accident data reported for these mines by the Mine Safety and Health Administration (MSHA). Backfill mines comprise a major part of the underground metal mining industry and are particularly important in terms of the fatalities and injuries impacting this workforce. Ground falls are the leading cause of fatal accidents at these mines accounting for 50 percent of the total fatalities (4 out of the 8 fatalities that occurred from 2006 through second quarter of 2011). MSHA reported several different types of accidents involving backfill at these mines. While backfill ground falls do not occur frequently, these accidents result in a much higher proportion of fatalities than host rock ground falls. Backfill ground fall accidents are especially hazardous in underhand cut-and-fill mining operations where employees work directly beneath the backfill. An analysis of recent MSHA accident data supports the need for further cooperative research with the mining industry to identify and address ground control problems in underground metal mines using backfill.

Feb 27, 2013

By A. Wahab Khair, Negendra P. Reddy

INTRODUCTION The continuous mining machines which were introduced in the 1950's now account for more than half the production of coal from underground mines. Unfortunately, these continuous miners which were designed for increased productivity have also increased the concentration of respirable dust in mines. Inhalation of this respirable dust by miners causes the Coal Worker's Pneumoconiosis (CWP). Concern for CWP increased in the United States following a 1963-65 survey that showed definite x-ray evidence of CWP in 9.8 percent of working miners and in 18.2 percent of nonworking miners in the Appalachian bituminous coal region (Breslin and Niewiadomski, 1982). One of the major objectives of the Federal Coal Mine Health and Safety Act of 1969 was the prevention of CUP. This law initially limited the daily average exposure of coal miners to 3 mg/m3 of respirable dust. However, following the results of a probabilistic model developed by Jacobsen, et. al. in 1971, the limit was reduced to a mass concentration of 2 mg/m3 unless quartz content exceeds 5 percent, a rare occurrence in mines. Based on x-ray categorization prior to death it is believed that the mass concentration in the respirable fraction is a parameter of primary interest for hygenic evaluation of dust exposure. Elorgan, Burgess and Jacobson (1973) suggested that the quantity of inhaled dust, although influential is not the only aspect of exposure which is significant in producing CWP. Miners working in higher rank coal (anthracite) mines are more susceptible to CWP (Morgan, Burgess and Jacobson, 1973). This also confirms the findings of the British (Bennett, Dick and Kaplan, 1979 and Hurley, et. al., 1979) and Germany (Reisner and Rubock, 1977). Based on the cy to toxicological evidence Reisner and Rubock (1979) suggested that when coal properties are similar, increasing quartz and mineral content increases toxicity. David, Ottery and Le ?oux (1975) examined that as the severity of the CWP increased the retention of the coal dust content in the pulmonary region remained the same, while that of quartz content increased significantly . Leiteritz, Baur and Bruckman (1971) studied the various components of coal dust and showed that coal particles comprised a smaller fraction of the mass of fine dust than did particles , of quartz and minerals. It is ironic that quartz and mineral matter both comprise smaller fractions of the higher rank coal dust (Dodgson, et. al., 1971 and Dwiggins, 1981). Results of a recent research revealed that quartz or any other mineral examined had no strong or consistent effect on the incidence or progress of CWP (Attfield,

Jan 1, 1986

By A. Podlesny, E. N. Rubinstein, J. J. Sammarco, B. Demich

Roof bolting typically follows the extraction of a commodity to help keep the roof from collapsing. During 2004 to 2013, roof bolter operators had the highest number of machinery-related injuries, accounting for 64.7 percent, at underground coal mines. This paper analyzes U.S. roof bolter fatal and nonfatal lost-time injury data at underground work locations for all commodities from 2004 through 2013 and determines risk indices for six roof bolting tasks. For fatal and nonfatal incidences combined, the roof bolting tasks in order of the highest to lowest risk index were bolting, handling of materials, setting the temporary roof support (TRS), drilling, tramming, and traversing. For fatalities, the roof bolting tasks in order of the highest to lowest risk index were handling of materials, setting the TRS, bolting, drilling, traversing, and tramming. Age was found to be a significant factor. Severity of injury, indicated by days lost, was found to increase with increasing age as well as with increasing experience, largely due to the confounding of age and experience. The operation of the roof bolting machine used in underground mining should be a research priority given the high frequency and severity of incidents. The results also suggest that temporal factors may exist, so additional research is warranted to better understand these factors and potentially develop interventions. This research provides a datadriven foundation from which future research can be conducted for safety interventions to reduce the frequency and severity of incidences involving the roof bolter activities of bolting, handling of materials, and setting the TRS.

Jan 1, 2016

By J. M. Mutmansky

The SIMAN (SIMulation ANalysis) computer language is a general-purpose, discrete-continuous simulation language for modeling a variety of multi-component systems. The language has been described by its author in a textbook (Pegden, 1985) and in a paper (Pegden, 1986) and is available in a mainframe version, a minicomputer version and a microcomputer version. The language was designed for and has been extensively used for modeling manufacturing systems but possesses many features that are advantageous in the modeling of mining materials handling systems. Consequently, the authors have applied the language to the simulation of an open pit shovel/truck operation to test its usefulness for simulating mine materials handling systems. This paper presents a short background on simulation languages, the capabilities and modeling framework of the SIMAN language, a description of the application of SIMAN to a shovel-track operation and some results and conclusions on the use of the language for mining materials handling systems.

Jan 1, 1988

By Yoginder P.

ACKNOWLEDGEMENTS Authors sincerely appreciate the interest, cooperation and technical support of the coal company management and staff in conducting the study. Without their assistance this study would not have been possible. INTRODUCTION AND SPECIFIC OBJECTIVES An area in the midwest overlying abandoned room-and-pillar mine workings at, shallow depth has been experiencing subsidence movements with associated damage to surface structures. Other coal companies in the area have also been having similar experience. A 16 - month cooperative study between a mining company and the Department of Mining Engineering at SIUC was developed with the following objectives. 1) Determine the extent to which surface and subsurface movements were complete in the area, 2) Identify the mechanism(s) of subsidence in the area, 3) Determine the influence of geology and hydrology of the area on subsidence movements, 4) Observe the conditions of abandoned underground workings with a borehole TV camera, 5) Characterize the extent of damage and monitor possible progressive damage to selected surface structures, and 6) Make recommendations to a) minimize further damage to surface structures in the area, b) identify future areas that may be affected by these movements and c) modify mining systems to minimize these movements.

Jan 1, 1986