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By J. A. Brierley, S. N. McIntosh, C. L. Brierley, E. G. Baglin, E. G. Noble, D. L. Lampshire

The U.S. Bureau of Mines investigated column bioleaching as a means of recovering manganese from a domestic low-grade oxide ore. Manganese was solubilized from the ore using indigenous heterotrophic microorganisms and molasses as the nutrient source. The effects of medium flow rate, molasses concentration, and frequency of medium replacement on the rate of manganese extraction were examined. Results showed that flow rates between 0.4 and 8.1 L/min/m2 had little impact on manganese extraction, while an increase in the total amount of molasses applied during leaching directly affected the extent and rate of manganese extraction. Manganese extractions of more than 90% were achieved in 12 weeks of bioleaching in column tests using 500 g charges of ore. Sugar utilization by the microorganisms and formation of organic acid metabolites were monitored by high performance liquid chromatography (HPLC). Two methods were evaluated to recover manganese from the sugar- depleted bioleaching medium: (1) adsorption onto weak cation exchange resin, followed by stripping and precipitation techniques; and (2) direct precipitation of the manganese as MnCO, using ammonium carbonate. Both recovery methods removed at least 95% of the solubilized manganese from the medium as a carbonate salt. The stripped molasses medium was replenished with fresh molasses and recycled back through the bioleach column, successfully leaching more manganese.

Jan 1, 1993

By C. J. Pritchard

I commend the authors on examining an interesting method of shaft lining and attempting to improve safety in a dangerous environment by remotely installing the shaft lining. It is important, though, to not trade off shaft lining safety for long-term mine safety by lining an intake shaft with combustible material. In many operations, the mine utilities are installed next to the lining of the intake shaft, supplying a possible ignition source if damaged or overloaded. Although the polyurethane studied in the paper is of relatively high density, no mention is made of the flame retardency of the samples. When exposed to heat, small amounts of polyure¬thane will melt and bum but are extinguished when the heat source is removed. If large surface areas of combustible polyurethane - a tunnel or mine shaft - are exposed to ignition heat sources that are not removed or extinguished early, an uncontrollable, fuel rich fire may result with high carbon monoxide levels, low oxygen concentrations, and greatly increased burning rates that can have devastating effects on the ventilation system and miners' safety.

Jan 1, 1990

Diamond wire rock cutting is the most widely used technology in carbonate stone quarrying owing to technical performance and block face quality. Interest is also growing for siliceous deposits. This paper deals with the problem of optimum wire utilization under restrictions regarding a set of variables and parameters. A computer program of general applicability has been set up with the aim of studying the most suitable combination of technologies and the effect on the technical and economic results of bench geometry, overall quarry yield, market -stone value, quarry size as well as the quantity, productivity and price of human and material resources and their organization in the elemental working cycle. Two quarrying problems are considered as significant instances a granite and a travertine quarry. The results are illustrated and discussed.

Jan 1, 1989

By J. J. Kellar

The near-infrared (NIR) (12,000-4,000 cm-1) region of the electromagnetic spectrum, between the mid-infrared and visible, has often been viewed by spectroscopists to be of limited utility. This is unfortunate, and recently the use of the NIR has increased greatly, primarily for the quantitative analysis of food and agricultural products. However, many other areas of application of NIR spectroscopy remain unexamined. In this paper a novel use of NIR in the area of flotation chemistry is demonstrated. Specifically, it is shown that NIR/Internal Reflection Spectroscopy (IRS) can be used to quantify collector adsorption reactions in-situ.

Jan 1, 1990

By T. Hudaverdi

Several studies have been conducted on blastability and prediction of fragmentation. The term blastability is used to refer the susceptibility of the rock to blasting and is closely related to fragmentation. Parameters that determine fragmentation by blasting may be divided into two groups. The first group consists of blasting design parameters. The blast design parameters are controllable parameters and determined by the explosive engineers. The burden, spacing between holes, bench height, drillhole diameter, stemming height and explosive density are all design parameters. The second group consists of rock mass parameters that are referred to as uncontrollable parameters. The uncontrollable parameters are physical and mechanical properties of rock and rock mass structure. The strength, modulus of elasticity, density of rock, number of joint sets, joint orientation and joint spacing are among uncontrollable parameters. The rock mass parameters and blast design parameters should be considered together to explain fragmentation process. In this study, a blast database was accumulated to use for multivariate analysis. The blast database contains the blasts performed near Istanbul region quarries and the blasts that were preformed in various mines in the world by the blasting researchers. The cluster analysis was used to separate the blast data into different similarity groups. Group memberships were analyzed and checked by the discriminant analysis. Then, the multivariate regression analysis was used to develop a prediction equation for blast fragmentation for each group. Finally, a validation of the suggested models was performed for various mines. The model comprises blast design parameters, mechanical properties of rock and rock mass structure.

Jan 1, 2011

By Fengyu Ren, Ruslan Puscasu, Kunpeng Yu, Gideon Chitombo, Liangliang Kang

Weak rock mass and poor flow of material can cause excessive ore loss and dilution in sublevel caving. This paper proposes a method to establish design parameters for an inclined deposit within a weak rock mass and evaluates its effectiveness through a case study. In order to solve the problem of low production capacity and poor safety conditions of sublevel caving mining at the Yingfangzi silver mine in China and to ensure a smooth production from the refractory ore body, it is necessary to select appropriate stope structure parameters. Based on random medium theory of gravity flow and the improved equation of ore discharge in random medium, an end wall drawing experiment is carried out to determine the optimum design and flow parameters. It was observed from the experiment that, due to the influence of the randomness of particle movement, there is a mismatch in the flow parameter measurement. The flow characteristics and distribution of the marker particles are different from that of the tested particles resulting in large drawbody shape distortion. The study finds that the flow parameters obtained by the new method are more practical and account for drawpoint width and recommends that the new method for determining the sublevel stope height is used when the drawbody is a non-standard ellipsoid. The outcomes have shown a significant reduction in the dilution and improvement in the recovery rates, and the safety and efficiency of mining have been greatly improved.

By K. Heasley, A. Yassien, A. Khair, S. Peng

There are three major components of a fully grouted roof bolt which primarily determine its ability to develop and sustain load: the steel rebar, the resin annulus, and the rock/grout interface. The untensioned, fully grouted roof bolt is subjected to loading only when the surrounding rock deforms. Vertical rock deformation is generally a result of strata sagging and bedding plane separation, whereas horizontal deformation is typically a result of bedding plane sliding. These two types of deformation create different types of internal loads with-in the roof bolt, tensile stress for vertical rock deformations and shear stress for horizontal rock deformations. Also, as a result of the mutual load transfer between the rock and bolt, shear stress will be developed along the grout/rock interface. According to the exact bolt loading conditions, different failure modes may occur: bolt axial failure, bolt shear failure, and shear failure along the grout/rock interface. Understanding these possible failure modes and their root causes is the key to eliminating roof failures in underground mines employing fully grouted resin bolts. Using ABAQUS 5.8, a finite element model was developed to simulate the components of the fully grouted bolt and its interaction with the surrounding roof strata. Several models were conducted to investigate how load transfer occurs between the rock and the bolt under different geological and mining conditions. The effects of bed-ding plane location and properties, and strata sequence on bolt stability were studied. Also, the effects of hole roughness on bolt stability were discussed. Bolt axial failure was not observed within the range of the studied parameters; however, a combination of high overburden depth, a bedding plane located at 2 to 3 ft from the roofline or a low coefficient of friction along the bedding plane caused strata sliding and shears failure in the bolt. Also, in the case of a weak immediate roof, the shear stress at the grout/rock interface could exceed its ultimate capacity lead to slippage.

Jan 1, 2004

This chapter looks at the development and use of the operating budget. This is management's plan of action in the short term, usually one year. The operating budget includes all expensed production costs (i.e., all costs reported as cost of goods sold) but does not include expenditures on capital equipment, which are usually justified using discounted cash flow techniques.

Jan 1, 1999

By James A. Erdman

This overview briefly describes some examples of applications and difficulties in using plants that are drawn from the literature and from field experience. Because of the generally low Au concentra¬tions found in plants, the analysis of plant tissue is critical to the successful application of the biogeochemical method of prospecting. Neutron activation analysis is the most widely used method to detect Au in plants, due largely to its sensitivity; levels in the parts per billion range are easily attained. Two general types of sampling media are used in prospecting for Au: humus and living plants. Humus has been widely used in Canada, but the sampling of plants has increased there and elsewhere in recent years. The use of douglas-fir (Paeudotsuga menziesii) at a Au-bearing stockwork in Idaho is a prime example. A maximum Au concentration of 14 ppm was detected in the wood ash of this coniferous tree, well above the normal background concentration of about 0.15 ppm. Among shrubs that might be useful in Au prospecting, sagebrush or wormwood (genus Artemisia) could be sampled because it is extremely responsive to concealed mineralization. It has been used extensively in the Soviet Union and could be used in areas of the western United States where disseminated Au occurrences might be located. Among the problems one may encounter in using plants for Au prospecting are (1) physiological barriers, by which many plant species simply do not absorb Au at detectable levels; (2) misconceptions of soil-plant correlations; (3) localization of Au in plant tissue; and (4) the variation of Au concentrations due to season. Despite these limitations, biogeochemical techniques can complement or replace other geochemical methods currently used.

Jan 1, 2013

By Wm. J. McCracken

HISTORICAL REVIEW OF BOARD OPERATIONS The Ontario Worker's Compensation Board was established in law enacted by the legislature of the Province of Ontario in 1915. It was designed to pay insurance benefits to injured workers, and at the same time to protect employers from legal suit. It was based upon an enquiry system rather than an adversary system such as that used in the courts process. Initially, the system was designed to pay compensation benefits and subsequently, to pay for the cost of medical treatment and pensions for disability and disease resultant from the effects of traumatic injury. In 1947, the Act was changed to include industrial or occupational generated diseases, not specifically related to traumatology. Such occupational diseases were therefore accepted and benefits paid subsequent to that date. As will be discussed in several minutes, even today the vast preponderance of compensation claims with the Ontario Board continues to be related to the effects of trauma. HISTORICAL REVIEW OF EXPOSURE TO RADON GAS DECAY PRODUCTS In some areas of Ontario, especially in Northern Ontario, there is a natural leaching of radon gas from the underlying rock formation. This constitutes very low levels of radon gas decay product radiation exposure to those persons coming in contact and inhaling these substances. This paper however is designed to discuss the occupational generated types of radon gas exposures. For many years dating back to the 1930's, partially refined ores were being shipped from Northern Canada to a refinery located at Port Hope, Ontario, still in operation and currently operated by Eldorado Nuclear Limited of Canada. Initially, the purpose for the operation was extraction of radium to be sold on world markets for medical treatment purposes. With the advent of World War II, this market collapsed. Subsequent to World War II, the availability of other sources of radiation for medical radio-therapy generally replaced the requirements for radium. During World War II, a new market opened up for the Port Hope refinery however as work into nuclear chain reactions and the development of the atomic bomb identified the need for uranium and enriched uranium. During the period of operations where radium was being extracted at the Port Hope refinery, it is now known that an identifiable radon gas hazard did exist. This hazard disappeared when the production line for extraction of radium ceased operations. In 1954, uranium mining operations opened up in Ontario at two locations, Bancroft and Elliot Lake. At the peak of operations, 16 mines were operational and 11,000 workers were employed in these mining operations. A high level of mining activity continued over a 10 year interval with the Bancroft Mines closing permanently in 1964 following a 10 year life of operation. The other mines in Elliot Lake closed about the same time with the exception of two uranium mine operations which have continued to be operational up to the present time. By 1965, due to a dramatic drop in world demand for uranium, the total work force had fallen to 1/10 of the peak work force, and approximately 1,300 workers remained in employment. It is of interest to note that one significant difference in the work environment between Elliot Lake and Bancroft was the high silica content of the Elliot Lake ore. This gave rise to a number of cases of silicosis developing in relatively short intervals of time in the Elliot Lake miner population. No cases of silicosis were identified from the Bancroft operations. Based upon the experience in investigating and evaluating actual cases of lung cancer in the uranium miners over the years, the medical staff at the Ontario Board also developed the impression that radiation levels were much higher in the Bancroft operations, especially in the earlier years of operation, than at Elliot Lake. This resulted in accumulation of higher levels of Working Level Months (WLM), usually over a shorter exposure interval in many of the cases. This aspect will be further evaluated in this presentation. Subsequent to 1965, the work force remained quite static in numbers until 1975. At that time, there began to develop an increase in the work force, and this increase is continuing at a moderate rate up to the present. INITIAL METHOD OF HANDLING LUNG CANCER CLAIMS The first lung cancer claims in Ontario from uranium mining operations were accepted on the perceived cause-effect relationship. This relationship was based upon the data from the Colorado observations and the Czechoslovakia data. Initially, a series of regression equations on mortality were developed and used to estimate the effect of exposure to low cumulative doses of radon daughters as it might relate to the frequency of occurrence of lung cancer at any particular cumulative exposure level. A probability of cancer being radiation induced as against it being caused from other factors was calculated. This method was discontinued subsequent to 1972 due to problems encountered in carrying out this complex evaluation. Thereafter, each case was dealt with on an individual basis, being based upon whether or not the tumour was of the oat cell type, a cumulative exposure in excess of 120 WLM; latency periods in excess of 10 years, commencement of mining prior to

Jan 1, 1981

By Lawrence K. Nordell, Vinit Sethi

Published standards and specifications do not adequately cover engineered class pulleys for modern high strength steel cord belt conveyors. This paper discusses the Conveyor Dynamics, Inc. (CDI) design criteria and stress analysis techniques emphasizing the finite element method (FEM), fatigue failure criteria, design limits and manufacturing requirements to ensure successful and safe pulley installations.

Jan 1, 1993

By William L. Young

I think I should let you in on one of Canada's best-kept secrets, if you will promise not to tell it all over the place. Believe it or not, good, honest, enterprising capitalism is still alive and flourishing north of our common border, and I am living proof that capitalism is still working for the little guy. My personal story of mining development in Canada isn't all that rare -- you've probably heard something like it from other areas and other days several times -- but my case brings it up-to-date. I would like to Tell you briefly the history of Northumberland Mines Limited, a contemporary case of individual enterprise getting a mining operation underway. And if I can do it you probably can too.

Jan 1, 1981

By F. Alsobrook

Industrial minerals are receiving increased attention by metals, coal and other companies seeking to diversify and stabilize earnings. Each industrial mineral has a unique set (and sub-sets) of business dynamics, however, and the diversity can present a bewildering maze to the corporate planner. Shrugging off this complexity and relying on serendipity for entry opportunities often results in unsuitable acquisitions. An effective alternative used in exploration can also be applied to strategic planning. By providing focus and direction, this flexible methodology can prevent wasting corporate resources on random pursuits and result in a quicker, more satisfactory achievement of diversification goals.

Jan 1, 1990

By J. B. Pautler, A. E. Gross, M. G. Strominger

The U.S. Bureau of Mines research on the use of cement as an agglomeration aid allowed precious metals heap leaching to become an economically viable method of precious metal recovery during the 1980's. However, many agglomerated ore bodies still exhibited poor heap/agglomerate strength. Precious metal recovery was often too slow or required prohibitively high levels of cement to be economically sound. Problems with heap ponding, blinding, and solution channeling and "wash-out" indicated that there was a need within the industry to improve on existing agglomeration technology. An in-depth research effort was undertaken to satisfy this need. Three years of research led to a patent on the use of vinyl addition polymers as effective agglomeration aids. A close working relationship between Brewer Gold and Nalco Chemical Company aided in the development of this program. This paper details the pilot test work, the full-scale evaluation at Brewer Gold Company, and conclusions.

Jan 1, 1990

By J. R. Cobble

The Bureau of Mines has developed a process to improve the leaching kinetics of diffusion controlled systems. The system features the Bureau-developed turbomill, an attrition grinder which scrubs the reaction product coating away from the unreacted mineral grains during leaching. The system can be continuously operated at any temperature up to the boiling point of the leaching agent. This paper describes the research on the dissolution of chalcopyrite with acidified ferric sulfate which forms a sulfur product on the unreacted chalcopyrite surface. This method is a hydrometallurgical alternative to chalcopyrite smelter technology which eliminates S)2 emission problems with its associated costs. Batch testing at 90? C with the chalcopyrite/ferric sulfate system resulted in better than 99-pct extraction of copper. At an optimal energy consumption of 1,520 kW h/st, 95 pct of the copper was extracted. Recent work has been directed to development of a continuous system and SX/EW treatment of the resulting pregnant liquor from the chalcopyrite/ferric sulfate leach.

Jan 1, 1991

By Gary G. Grim

The reliable performance of the coal reclaim system is essential to the continued availability of a coal-fired electric generating unit. The control of fugitive coal dust within the areas housing the reclaiming equipment is necessary not only to minimize maintenance and clean-up costs, but is also a safety and health consideration. This paper describes the reclaim system control and dust suppression systems as initially installed, the shortcomings of these systems and the steps eventually taken to correct these shortcomings.

Jan 1, 1983

By D. Malhotra

Climax byproduct-plant tailing assayed 0.019 percent WO3. Pilot-plant and laboratory tests were performed to investigate the possibility of recovering additional tungsten values from the byproduct-plant tailing. The paper discusses the methodology used in the study and the results of this investigation.

Jan 1, 1985

By Robert J. Watters, Peter C. Kelsall, Joseph G. Franzone

Two separate studies investigated the compressive strength of basic igneous rocks and its relation to index properties such as porosity, density and soundrave velocity. The rocks tested were weathered dolerite from S. W. England and vesicular lavas from California. In both cases strength was affected considerably by porosity. In the dolerite, strength was also affected by fissures (microcracks) which were formed in the parent rock by shearing and later accentuated by weathering. While test results show that porosity, density and sound velocity are not reliable indices of rock strength, these properties are useful in interpretation of strength test results. Index testing can be used to classify samples according to similar behavior and to recognize the influence of fissures.

Jan 1, 1986

By Claus Becker

In Europe, approx. 50 km of traffic tunnels are under construction using Slurry-or EPB Shields or Convertibles of all sizes, among them the biggest slurry shield ever built up to now with 14,20 m diameter. Main characteristics and special features of the machines will be explained relating to geology, cover and water pressure. This gives a comprehensive overview of the latest developments of this kind of machines.

Jan 1, 1999

By John A. Herbst

Mathematical models of mineral processing unit operations have been developed and used for a variety of purposes. Models, defined as equations which mathematically approximate the behavior of process units, are being employed in simulators to evaluate proposed flowsheets, to investigate flowsheet modifications, to study the effect of variables on circuit behavior, to optimize the performance of circuits off-line, and to compare alternate control strategies (Mular and Herbst, 1978). Models developed for mineral processing operations may be placed in one of two general categories: phenomenological (based on mechanism) and. empirical (based on experimental data only). Dynamic models (including time as a variable) .are useful for control studies, while steady-state models (independent of time) are employed in flowsheet evaluations. Phenomenological models are potentially more flexible and accurate than empirical models. However, models constructed from theoretical knowledge are less easily developed compared to empirical expressions fitted statistically to experimental data. The latter apply only over the range of data acquired. Most often, models used in practice are the result of a combination of theoretical and empirical approaches.

Jan 1, 1979