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By Warfield Garson

Few, if any, of the non-ionizing radiation health hazards to be found in either surface or underground coal mining are uniquely different because of their being found in the work environment. Hence, they can be considered generally for their bio-effects on the worker when found in the mining work environment. The same may not be said, however, for the lack of non-ionizing radiation and its bio-effects, particularly as it relates to underground coal mining. The term "non-ionizing radiation" refers to various forms of electromagnetic radiation of wavelengths longer than those of ionizing radiation. As the wavelength gets longer the energy of electromagnetic radiation decreases. Therefore, all non-ionizing forms of radiation have less energy than cosmic, gamma, and X-radiation. In order of increasing wavelength, non-ionizing radiation includes ultraviolet, visible light, infrared, microwave, and radiofrequency radiations. The energy frequency and wavelength range of both the ionizing and non-ionizing electromagnetic forces are shown in Table I. To convert the wavelengths of various radiations to Ångström units, one multiplies millimicrons by ten. In a vacuum, all electromagnetic radiation has the same velocity, namely 3 x 1010 centimeters per second. The natural source of radiant energy here on earth is our sun which emits radiation continuously over a wide spectrum. This radiation on average reaching earth ranges from 290 nm in the ultraviolet range to over 2,000 nm in the infrared range with a maximum intensity of about 480 nm in the visual range. You will note this falls into the visible blue wavelength and accounts for our blue sky and blue ocean and deep water effects. We are all familiar with the fact that the passage of solar radiation through the atmosphere to the earth changes the spectrum considerably because the atmosphere absorbs and scatters many of the sun's rays. The ozone in the upper atmosphere absorbs the shorter ultraviolet wavelengths and water vapor absorbs some of the infrared wavelengths. Smoke, dust particles, gas molecules and water droplets scatter the rays, especially those of shorter wavelengths. In addition to the sun, every gas, liquid or solid object at a temperature above absolute 0° radiates energy. Solid objects emit almost continuous spectra. At low temperatures only radiation of the longer wavelengths in the infrared range is emitted, but as the temperature of the object is increased, more and more of the shorter wavelengths are added. This fact is most readily demonstrated by heating a piece of steel. When a piece of steel reaches a temperature of about 1,700° Fahrenheit, it gives off radiation at the red end of the visible spectrum and appears dull red. As the temperature is further increased, the shorter rays are also emitted, until at about 2,100°F, the metal appears white, due to the emission of wavelengths throughout the entire visible range. Gasses, on the other hand, when heated emit radiant energy only at certain wavelengths, which are characteristic of their chemical structure. This latter fact is of importance in underground coal mining as high intensity gas and vapor lamps are becoming more and more utilized for illumination in underground coal mining. The biologic effect of non-ionizing radiation exposure depends upon the type and duration of exposure and on the amount of absorption by the miner. The effects of this radiant energy on the miner fall into four distinct types: (1) the heating effect of infrared radiation, (2) the effect on the eye of visible radiation, (3) the effects of ultraviolet radiation, and (4) the growing potential effects of the misuse of microwave radiation. Each non-ionizing type of radiation will be considered individually. ULTRAVIOLET RADIATION The sun is the major source of ultraviolet radiation, which is of concern in open pit and surface mining at certain seasons and in certain climes necessitating protection for the surface miners under those conditions; nonetheless, there are some man-made sources such as electric arc lights, welding arcs, plasma jets, and special ultraviolet bulbs for illumination underground that demand surveillance in the underground environment to be aware of whether the miners are at risk above the threshold limit values allowable. Since ultraviolet radiation has little penetrating power, the organs that are affected are the skin and the eyes. Ultraviolet radiation is strongly absorbed by nucleic acids and proteins, and the effects in man are largely chemical rather than thermal. Short-term effects on miners include acute changes in the skin. These are of four types: (a) darkening of pigment, (b) erythema (sunburn), (c) increase in pigmentation (tanning) and (d) changes in cell growth. Ultraviolet radiation also causes acute effects on the tissues of the eye. Overexposure can lead to keratitis, inflammation of the cornea, and conjunctivitis. Long-term effects of ultraviolet exposure include an increase in the rate of ageing of the skin with degeneration of skin tissue and a decrease in elasticity. Late effects of ultraviolet on the eye include the development of cataracts. The most serious chronic effect of ultraviolet exposure is skin cancer. Ultraviolet radiation effects are increased by some industrial materials and drugs. After exposure to such compounds as cresols, the skin is exceptionally sensitive to ultraviolet radiation. Photosensitivity reactions occur after exposure to a variety of other chemicals and drugs including dyes, phenothiazines, sulfonamides, and sulfanylureas. On the other hand, we must remember that ultraviolet radiation has an important role in the prevention of rickets. Vitamin D is produced by the action of

Jan 1, 1981

By David J. Leeds

Increased interest in the utilization of the underground environment for water conveyance tunnels, vehicular tunnels, room and pillar type storage chambers, and military installations has focused attention on the possible effects of seismic activity on the stability of these types of structures. Earthquake experience has generally been related to the seismic stability on the surface of the earth. To establish aseismic design criteria, we attempt to predict the seismic exposure of a given site, both in terms of the spectrum of motion to which the structure must react favorably, and the recurrence rate of that motion. Experience gained from studying the effects of the Plowshare underground nuclear tests on existing tunnels and mines, coupled with the experience of the behavior of tunnels and mines in earthquake regions, provides us with an insight to predict the possible effects of earthquakes on underground openings and to establish design criteria. The type of damage ranges from minor fracturing and movements along pre-existing joints or faults through deformation of openings to collapse. The methods used to establish the seismic design criteria for an underground opening require modification of surface criteria to account for the difference in both amplitude and spectra underground. An aseismic evaluation should be performed on all important projects in areas exposed to possible earthquake motion. To perform this evaluation, information is required pertaining to the geometry and properties of structure and ground. Dynamic as well as static properties are required. A prediction of performance can be derived by exposing a model of the site, expressed in terms of its properties and geometry, to a design earthquake.

Jan 1, 1997

By D. L. Passmore

The development of microcomputer software that provides an analysis of pit-specific accident and production data for the mining industry is seen as a vital component in a total loss-control system. The Mine Injury Reporting System (MIRS) allows users to access accident and production data prepared by the Health and Safety Technology Center of the Mine Safety and Health Administration of the United States Department of Labor for any particular state and to generate a simple, yet informative, report.

Jan 1, 1988

By Bryan A. Bartley

High intensity, autogenous grinding has been developed in the hard rock, quarry industry and is finding wide application in mineral processing. The autogenous vertical shaft impactor is described and action within the machine is illustrated. This machine is compared with the cascade mill, in the three characteristics of impact, inter-particle rubbing and nipping, of which impact is the most important. There is a seven fold increase in impact level over that of the cascade mill. The autogenous impactor has characteristics of crushing and grinding, preferential crushing, abrasion resistance and drying. These are illustrated by examples of industrial applications, where the machine is now used and range from abrasives, such as Carborundum to phosphate rock.

Jan 1, 1998

By Thomas P. Bligh

Underground and earth covered construction offers a real and significant opportunity for saving energy, reducing building costs, and preserving valuable land resources. These methods lend themselves to mass production techniques without the adverse effects of endless visible repetition and can effect an energy savings of 75% or more.

Jan 1, 1976

By Chester R. Harris

With the passage of the Occupational Safety and Health Act (OSHA) on December 29, 1970 and the formation and growth of the OSHA Agency it spawned, public consciousness of occupational safety was raised. It became accepted that employees had the right to "a safe and healthful workplace". With the possibility of OSHA inspections, employ ers (particularly those with large workforces) began to give serious con sideration to engineering controls, safety programs, and training in a more uniform manner than previously.

Jan 1, 1991

By P. Petropoulakis

Computer technology in the mining activities of our company has been applied in the last decade. In this presentation the experience gained by applying this computer technology in mining spescific applications are reported. Attention is given to the problems phased out and to the methodology used for software selection, centralized and decentralized development, data processing personnel and end users training and support. The paper concludes with a report of the first results obtained and a look at the future developments of the system.

Jan 1, 1989

By J. Jeremy Burden, Bruce S. Brown

A major question in the design and permitting of a tailings storage facility is the quality and quantity of seepage which will occur from the base of the tailings facility into the underlying foundation and groundwater regime. A corollary to this is what liner system, if any, is necessary to protect the groundwater regime from unacceptable contamination. Modern tailings storage facilities are generally designed as drained tailings deposits whereby all free water is removed from the facility by decant, drainage and evaporation. This removes the source of on­going seepage and allows for efficient and timely reclamation of the facilities. Quantifying the residual seepage from the base of the tailings deposit is complicated due to the following factors:

Jan 1, 1992

By T. Orgodol, P. Korpi

This paper describes the Boroo Gold Company (BGC) ore processing plant which is the first CIL/CIP plant in Mongolia. BGC is the first foreign investment in Mongolia since 1990 and follows the highest safety and environmental standards. Commissioning of the plant commenced in October 2003 and commercial production began in March 2004. Gold recovery is by gravity and conventional leaching and carbon adsorption. Detoxification of the leach tails is by the SO2/Air method before discharging the tails to the tailings pond. Ore types treated at Boroo are predominantly oxide with some transition ore as mining reaches the lower sulphide zone. There are several interesting technological issues and projects ongoing at Boroo which will also be discussed.

Jan 1, 2007

By James Barker, Jacques Renault, Chris McKee

Previous XRD work by us (McKee, Renault, Barker; 199Oa, 1990b) showed that by using pressed powder briquettes and a peak deconvolution technique, quartz in perlite can be routinely determined at <0.1 wt. %. In the present report, we discuss two additional methods of standardization: 1) chemical determination of quartz in silicate standards and 2) addition of a large amount of quartz to an unknown mixture. The first method applies the concept of mass balance and is sensitive to the analysis of silica and a monitor element. The second minimizes mixing errors; its equation is non-linear and is derived from the two component case with unequal mass absorption coefficients treated by Klug and Alexander (1974).

Jan 1, 1991

By Randall D. Peterson

Economic operation of a mine ventilation system must include some means by which operating costs can be quantified and evaluated periodically. Current practice at most mines relies upon the best judgement of foremen, engineers and managers to identify high cost or problem areas in the system and to estimate potential costs and benefits of work proposed to reduce inefficiencies. The problem with this is that significant savings can be overlooked or sub-economic projects may be undertaken when sufficient attention is not paid to the interrelationship between airflow characteristics and corporate financial criteria. In order to accurately determine costs and benefits it is necessary to view the solution of each potential ventilation problem as a separate economic opportunity.

Jan 1, 1993

By D. Greene

The close integration of mine planning and mine operation continues to be the goal of mine operators. Depending upon the complexity, size and sophistication of the mine, limited success has been achieved in this area. Despite tremendous strides in the development of computer-aided mine planning, digital plans must usually be converted to error-prone paper maps and physical ground surveys for actual excavation and reclamation. However, advances in global positioning systems (GPSs), operator displays and mobile computers now enable equipment operators to work directly from on-board digital plans. A computer-aided earthmoving system (CAES) offers reduced survey costs, faster field transition time and improved excavation accuracy, coupled with faster, more informed decision making regarding key mining operations.

Jan 1, 2000

By J. E. Garlanger, R. K. Shrestha

During mining, the surficial aquifer and, in some cases, the top of the uppermost confining unit within the mined areas are excavated. Portions are removed from the area for resource recovery. Until the mined areas are reclaimed, the surrounding unmined area continues to dewater. The impact of mining and subsequent restoration of the surficial aquifer on the ground and surface water resources of the watershed affected by the mining will be described. This will be done in terms of ground water recharge, ground water levels, and base flow and runoff to surface streams. Data from actual mining situations will be used in analyses and discussion. Recommendations will be made for further research.

Jan 1, 1992

By Y. K. Yen, J. D. Miller, C. L. Lin

A PC image-based, on-line coarse particle size analysis system is being developed for the control of crushing and grinding circuits. Initial results had indicated that the system is accurate when tested with irregularly shaped particles which are stationary and do not overlap with each other. Now the system has been successfully tested in the dynamic mode with a moving belt conveyor. On-line size analysis for actual plant operations is discussed and includes: (1) the video system with respect to lighting and data acquisition requirements for a rapidly moving belt and, (2) image sampling, specifically the number of observations needed for accurate sampling and the total time required to perform the calculations for a representative data set.

Jan 1, 1993

By E. Ghali, L. Tremblay, M. Lanouette, J. McMullen, G. Deschenes

Since the start of this decade, our society has attached great importance to matters concerning environmental protection. Currently, most mining operations use the cyanidation process in working gold deposits. While this process is efficient, the dangerous aspects of cyanide are delaying the development and marketing of cyanidation in underground sites. There is a growing need to consider installing an underground leaching system that will make the processing of low-grade gold ore profitable by reducing certain major operating costs (transportation, crushing and grinding). Underground leaching is performed in two ways. The first way is in-site or underground and the second way is in-situ. CANMET (Harrison et al.), in collaboration with Dennison Mines, developed the underground leaching of uranium. This process is used commercially. Copper, salt and sulphur are recovered by in-situ leaching (Jacobson and Murphy). The recovery of gold and silver is under development (Van Staden and Laxen).

Jan 1, 1992

By Myles G. Hyams

A mining project is proposed for the state of Pahang, Malaysia. The proposal involves the mining of a sulphidic ore body and initial processing to form a sulphide concentrate which will be transported to a roaster/acid plant for the production of sulphuric acid. An outline is presented on the potential environmental impacts of the project which have been assessed by superimposing project infrastructure and processes on to the physical, biological and social environment during the early design and planning stage of the project. The potential impacts eliminated by engineering design and the techniques employed are presented. However, there are a number of potential impacts that require careful consideration and planning for long term management. These include surface water drainage, waste rock leachate, tailings disposal and the social environment. Environmental management designed to minimise or alleviate these impacts as a result of project implementation concludes the paper.

Jan 1, 1991

By Hugh K. Herbert, R. John Watling

Laser Ablation-Inductively Coupled Plasma-Mass Spectrom­etry (LA-ICP-MS) has been used successfully to "fingerprint" gold in forensic investigations within Australia and abroad. By comparison of the elemental associations it has been possible to relate gold to specific mineralising events, mines, bullion samples and fabricated articles. The methodology facilitates identification of the provenance of gold thereby providing definitive scientific evidence in criminal investigations. "Gold" samples for analysis span a wide range of materials with many requiring exhaustive prior separation and treatment to present the contained gold in a chemically "unmodified" state, and in a form, suitable for LA-ICP-MS fingerprinting. The quality of the fingerprint, and hence its value in evidence, is directly related to the rigours of prior sample preparation and evaluation, to an appreciation of the history of the gold under investigation, and to the skill of the analyst.

Jan 1, 1995

By Manuel Diaz del Rio

At the present time there are over 5,000 Kms of railway tunnels in existence throughout the world. In many cases these tunnels were built over a century ago using techniques obsolete today. Supervision and maintenance of these tunnels is essential to the economy of each country involved. For this purpose an electro-optical measuring system has been designed incorporating highly complex soft and hardware (15 mW laser, high resolution TV camera and processing computer), mounted on a vehicle. Its job is to scan, record and compare sectional gauge values (profiles) and strains inside tunnels both momentarily in situ and on permanent record, as an aid to the supervision work. From the state of the strains observed, in conjunction with an infrared spectrum of the tunnel lining and soil involved, the mechanical stresses in the tunnel can be deduced by applying the boundary elements method.

Jan 1, 1981

By P. T. Perdue, F. F. Haywood

INTRODUCTION Monitoring devices used for detecting and measuring airborne radon in mines are limited due to the rugged environment in which they must operate. Personnel monitors now available are either passive or require filters and an air pump. Area air monitors usually have bulky batteries or require electric power service to the instrument. Thus, there are few instruments presently in use in mines capable of discriminating between the various radon isotopes and their daughters. Occasionally it is desirable to determine which radon daughters are the principal dose contributors in mine air. In some areas, such as the Elliot Lake mine in Canada, there exist sizable quantities of 220Rn in the mine air due to 232Th in the ore (Cote and Townsend, 1981). Since there has been recent interest in radon daughters in homes and factories, as well as caves and mines, methods and instrumentation are being developed to address these cases. Some of these methods can be employed in uranium mines. Although there have been very few determinations of the three radon isotopes (222Rn, 220Rn, and 219Rn) and their daughters made in uranium mines, these isotopes have been measured in process buildings and in private homes under circumstances that suggest these isotopes could also be present in uranium mine air (Perdue, Leggett, and Haywood, 1980; Yarborough, 1980) METHODS Cryogenic air sampling was developed about 15 years ago (Rasmussen, 1972) to concentrate various airborne chemicals for later fractional distillation and measurement of various organics using gas chromatography. A version of this technique has been developed to measure tritium, krypton, and other radioactive gases in nuclear power station buildings (Anon, 1980). In this method, fractional distillation is used in conjunction with various detectors to identify the radionuclides present. The cryogenic method to be discussed here was developed at Oak Ridge National Laboratory (ORNL). It uses the liquid air accumulated in a sampling device for a direct analysis of all gamma-ray emitters present. The air sampler (Fig. 1) could be employed in a mine to liquefy air, using the difference between the point of liquefaction of air (~80 deg. Kelvin) and the boiling point of liquid nitrogen (77 deg. Kelvin) to liquefy an air sample. By using a proper orifice at the entry to the sampling vessel, air of any dust concentration and relative humidity [ ] may be sampled. The energy for sampling is provided by the slow evaporation of the liquid nitrogen; no other power source is required. This type of sampler could be used to augment the usual filter and pump, or passive system presently employed to estimate personnel dose from radon daughters. It would also allow measurement of any combination of daughters from the three radon isotopes. Upon completion of sampling, the sampler is closed and removed from the mine. This sampler, with its liquid air contents maintained by the slow evaporation of liquid nitrogen, is taken to the place of measurement. There, the sampler is opened, the accumulation of water and ice in the neck is chiseled down into the liquid air, and the sample is transferred quickly to a precooled counting dewar (Fig. 2). This counting dewar is then placed upon a gamma radiation detector; we recommend a high purity germanium detector. A determination of all the radon daughters can be made in 1 to 4 hours after the sample is taken.

Jan 1, 1981

By Andy Cole, Stanley Bunk, Steve Dunn, Thom McCord

In 1994, Goldstrike initiated a research program to investigate processing options for treating what was then the small amount of carbonaceous ore identified in the reserves. The focus of the research was on developing a process which incorporated the autoclave technology already utilized at Goldstrike. Over the next two years, Barrick pursued the development of an ammonium thiosulfate leaching (ATS) process. During the period in which the ATS research was being conducted the amount of carbonaceous ore in Goldstrike's reserves increased substantially and continued growth was projected. By 1996, significant advancement was made on the development of the ATS process. The work culminated in a series of integrated pilot plant runs incorporating autoclaving, ATS leaching, resin in leach, stripping and cementation. Several questions about the process chemistry remained unanswered, preventing commercial development. Barrick was committed to producing gold from the carbonaceous ore reserves by 2000. A due diligence review of carbonaceous ore processing options was initiated during the second half of 1996. Processes considered in addition to ATS were fine grinding/autoclaving, as practiced then by Santa Fe, and whole ore roasting as practiced by Independence Mining and Newmont. The objective by year-end was to recommend the most robust and economical process for Goldstrike's carbonaceous resources. In the fall of 1996, a detailed review of roasting as a processing alternative for Goldstrike was initiated. Throughout the ATS development period, whole ore roasting was used as the benchmark. All the ATS metallurgical and financial results were compared to roasting bench top test results. It was clear this data was too imprecise for use in due diligence study, a more definitive recovery value was needed to complete the carbonaceous ore review. The primary goal of the roasting review was to conduct pilot plant roast tests to gain a more thorough understanding of Goldstrike's carbonaceous ore's response to roasting and its effects on gold recovery. Using the test facility at Hazen Research, four pilot plant campaigns were conducted to determine optimum roast conditions and further define metallurgical design parameters. Conventional two-stage fluid bed technology based on Freeport­McMoRan's roasting patent was the specific process basis for testing. The ore's response to roasting exceeded expectations. In January 1997, a preliminary economic evaluation comparing ATS and roasting was presented, and the outcome was approval to proceed with a roasting prefeasibility study. In July 1997, approval for Goldstrike's Roaster facility was received and basic engineering started immediately thereafter. Detailed engineering _began in January 1998 and plant construction commenced in October 1998,t, Goldstrike's Roaster facility is designed to treat 12,000 tpd of a refractory gold ore, which contains both pyrite and organic carbon. Circuits in the facility include primary and secondary crushing, dry grinding, roasting, gas handling, neutralization, thickening and standard CIL. Gold desorbtion and recovery is carried out at Goldstrike's existing refinery. Plant start-up of the first dry grinding and roasting train is scheduled for March 2000, with the second train coming online in May 2000.

Jan 1, 1999