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By S. D. Morrison, J. L. Watson

It is well known that the density and viscosity of a mill pulp have optimum levels for grinding efficiency, and sophisticated control loops are employed to control pulp density in industry. However, these control loops rely on a number of plant measurements, and often the input data will not permit effective determination and control of the mill pulp density. The use of a single remote pulp density measurement has obvious advantages, and it is suggested and demonstrated for laboratory batch grinding that mill noise measurements can indicate the effective density of the mill pulp. In addition, the mill noise is shown to indicate the actual effective pulp viscosity in the mill and hence permit the identification of the dynamic rheological regime existing in the mill. It is demonstrated that mill noise increases with grind time and, at any given grind time, with increasing pulp density in the pseudoplastic range. This increase in mill noise level with pulp density is interpreted as indicating a decreasing pulp viscosity. The results show that the transition from dilatant to pseudoplastic conditions within the mill, with increasing pulp density, can be identified by this increase in mill noise. When the pseudoplastic pulp started to exhibit yield characteris- tics, the mill noise fell dramatically. The technique of mill noise analysis is then used to investigate the effect of a grinding additive on the batch grinding of two ores. With a magnetite ore, the additive was shown to increase the mill noise, and hence decrease the pulp viscosity, in the pseudoplastic region and to increase the effective grinding. The molybdenite ore, however, did not show significant noise level changes and did not show improved grinding efficiency.

Jan 1, 1987

By 000-000-604

HISTORIACAL INTRODUCTION Mineral processing has three principle branches, to quote Taggart, "Ore Dressing, which comprises the methods of separation of solids in inorganic crude by means which do not affect substantial chemical change; Extractive Metallurgy, which utilizes chemical reactions for separations of constituents from solids in inorganic crude; and, Fuel Technology, which employs both physical and chemical methods for separating and rearrangement of liquid gaseous and solid components in crude oil and natural gas, tar sands, shale oil, or coal." The scope of this handbook covers the first two classifications, that is, "ore dressing" and "extractive metallurgy," which have been combined in one term: "mineral processing." For a brief history of the development of mineral processing, one could well refer to the Introduction, Sec. I of the Handbook of Mineral Dressing by Taggart, Froth Flotation, Principles of Mineral Dressing by Gaudin, and the original Richard's Ore Dressing, volume No. 1, first published in 1903-1905. In these references and the references given in them a coverage of the history of "ore dressing" can be found and studied at the reader's leisure. For the history of extractive metallurgy as well as ore dressing, the bibliography in General References, taken from a History of Ex¬tractive Metallurgy by F. Habashi, will give a good background for those who are interested in more detail on the history of metallurgy in general. Mineral processing covers a very wide field as is illustrated by the topics discussed in Part II of this handbook and dates back to the early history of man which started with the production and use of native minerals such as gold, silver, copper, mercury, and meteoric iron which were washed or picked from deposits on the surface of the earth and worked because of their malleability. Later, melting was discovered and then it was possible to cast objects of these metals, excluding mercury. The discovery of a method for reducing the metal¬lic oxide probably was developed from melting fragments of oxides or roasted sulfides with charcoal, so that the native metal could be produced in simple blast furnaces such as are used today in rural parts of Spain, China, and elsewhere. Eventually, it was learned that iron could be readily worked when hot, which resulted in its replacing bronze for tools, weapons, and cutlery. Carbon dating and correlation with the Brittle Cone pine has

Jan 1, 1985

Crushing and grinding activity in 1989 followed the rapid pace of the mineral industry. Use of existing installations, demand for expanded capacity, and implementation of entirely new operations contributed to a high level of activity. At the 1989 SME-AIME Annual Meeting in Las Vegas, NV, the crushing and grinding session focused on wear materials in crushers and mills. Another session joined the process control group in its simulation-modeling and control of crushing and grinding circuits. Both sessions addressed the optimization in operating effectiveness. Specific subjects covered grinding media wear of forged and cast grinding balls and rubber lined mill liner wear. Also, the Semi Autogenous Grinding (SAG) Mill Conference in Vancouver in September 1989 provided a valuable update on the progress of SAG operations in recent years. Operationally, gold grinding and roasting circuits were implemented in 1989. Freeport McMoRan Gold started up two operations in Nevada. Two other circuits, both using SAG mills, are scheduled to start in 1990. These will be in Nevada and British Columbia. Elsewhere in gold, additional capacity continues to be brought onstream, both domestically and worldwide. In copper, expansions continue to call on additional crushing and grinding units. The unrest at Bougainville in Papua New Guinea has fueled a continued, strong demand for comminution in the copper sector. Specific equipment installed or started in 1989 included the ac variable frequency drive SAG mills in Australia, Alaska, and Papua New Guinea. Also, the gearless drive SAG mill in Chile provides tremendous flexibility in terms of mill speed. The trend toward moveable in-pit crushers continues -even at established operations.

Jan 1, 1990

By Robert A. Haney, David J. Atchison, Kenneth G. Fields

Mining systems with greater than a 20-foot face advance (deep cut) have become popular due to their increased productivity and safety. The face dust collection system used in many of the mines employing the deep cut systems, incorporates a machine mounted dust collector with either a blowing or exhausting line brattice and a remote control operated continuous miner. In order to characterize and quantify the parameters used to control dust with these systems, the Dust Division conducted studies on four mining sections using continuous miners with deep cut mining systems. On each section, the dust control system incorporated line brattice with a machine mounted dust collector. The remote control made it possible for the continuous mining machine to advance further while permitting the operator to remain under supported roof and away from dust generated during mining. The purpose of these studies was to evaluate the effectiveness of deep cut mining systems using dust collectors to control respirable dust exposure. This paper summarizes the results of the studies conducted. At each mine face workers were sampled to determine their full-shift dust exposure. Additionally, fixed point dust samples were collected at various locations to determine relative concentrations of dust generated from mining. Air quantities were measured at each working place to determine the amount of air delivered to the face area. Evaluations were made by comparing worker exposures to respirable dust samples taken at appropriate locations upstream and downstream of the coal faced being mined. An estimate of the amount of the respirable dust being generated at the face during mining and the amount of respirable dust being removed by the dust collectors was made by balancing the air quantities and the dust concentrations immediately upstream and downstream of the coal face. Results of the studies showed that the dust control systems, were effective for controlling workers exposure to respirable dust. Dust collector efficiencies were determined to be approximately 85 percent. While the dust collectors were effective in removing respirable dust, the success of the systems with line brattice greater than twenty feet from the face, was dependent on the use of the remote control which permitted the continuous miner operator to remain out of the high concentration dust cloud in the working face. Dilution from intake air, combined with the dust collector efficiency, maintained exposure of other section workers below applicable standards.

Jan 1, 1991

By William A. Griffith

The recent recession has severely impacted the performance and results of virtually all of our natural resource companies. The depressing climate continues to linger and recovery maybe sometime away. Problems remain for resource companies in the steel and petroleum industries as well as the mining business. In February, at the AIME Annual Meeting in New York, an All-Institute session presented a variety of views on the situation. A. T. Yu, chairman of ORBA Corp., Mountain Lakes, NJ, organized presentations by top management personnel of four natural resource companies. This well attended session heard management strategems for the present and views for the future. A compilation and synthesis of these presentations, gathered by Dr. Yu, are presented here for ME readers. Leading off will be William A. Griffith, president and chief executive officer of Hecla Mining Co., Wallace, ID. Other speakers presented here include Wilfred P. Schmoe, executive vice president of Du Pont Co., Wilmington, DE; Frank W. Luerssen, chairman and chief executive officer of Inland Steel Co., Chicago, IL; and Adam H. Zimmerman, president and chief operating officer of Noranda Mines Ltd., Toronto, Ontario. First, then Griffith's remarks. Introduction The key to successfully managing a natural resource company in austere times is good management in good times. In other words, position the company during prosperous times to survive the times when the well dries up. Although we know how to manage properly, for various reasons we sometimes do not do it. We forget the lessons of history. We allow ourselves to be carried away by our egos. We fail to position our companies properly in good times. As a result, in bad times we find ourselves in deep trouble. We need constant reeducation in the things we already know. In the natural resource industries, proper positioning in good times involves becoming a low-cost producer, retaining the flexibility to pull in our horns, developing a lean and effective organization, and maintaining a healthy balance sheet. Nothing improves the chance of survival during austere times as much as being able to produce at a lower cost than your competitors. In our business, that means having low-cost mines - low cost because the ore bodies are high grade or favorably located, and because they are efficiently operated. It also means recognizing the competition. The key numbers are the cost to produce an ounce of silver or gold. Nothing else really counts. And our competition is every other precious metal mine in the world. Flexibility is important when one gets stuck with a high-cost operation, often because things do not work out as we expect. It is important to be able to shut down an operation quickly and easily, without high holding costs, and without disrupting the corporate organization. A lean and mean, effective organization of competent people is vital during bad times. A company will not have that if it is not developed and maintained during good times. Finally, a natural resource company has to develop a healthy balance sheet during good times if it is to survive the bad. Money in the

Jan 6, 1985

By Hugh E. Cronin, Joseph J. Coluccio

The Columbia Slough Consolidation Conduit Project is a 12 ft. 0 in. inside diameter—15 ft. 4 in. excavated diameter tunnel, 8,300 lf. in length. The tunnel is divided in two parts a 4,460 lf. reach to the West and a 3,770 lf. reach to the East separated by a flow regulation structure in the middle. The project was built for the City of Portland, Oregon Bureau of Environmental Services (BES) by the Frank Coluccio Construction Company (FCCC) Seattle, Washington under a $22,600,000.00 contract starting in 1998 and completing the contract in 2000 at a total cost to the City of $25,448,000. An increase of 12.6% from the original contract. The tunnel was constructed in an alluvial sediment that ranges up to 1,500 feet thick. The sediment varies from ?ne silty sand and sandy silt (SM-ML) to coarse sand and gravel (GP-GM) with varying quantities of cobbles and boulders. Most of the tunnel was constructed above the water table although one reach of almost 1,000 lf. had water to above the tunnel crown. The contractor, FCCC, used a Lovat 15 ft. 3 in.900 hp shielded TBM with multiple doors (4) of variable opening to excavate and support the tunnel. Tunnel supports were 5 in. WF 16 lbs. per foot at 4 ft. spacing and4 in. Douglas Fir lagging. Tunnel excavation was worked in 10 hour shifts with additional equipment maintenance and repair on the off time. The original Geotechnical Design Summary Report (GDSR) established a baseline for contractual purposes of slightly over 5 boulders (between 12 in. and48 in.) per foot of tunnel. (Table 1) At the pre-bid conference, three test pits were excavated to approximately tunnel invert, one at each end of the project and one in the middle near the flow regulation structure. The test pits encountered a few boulders but did not seem to support the five boulders per foot (varied from one boulder per foot of tunnel to eight b/lf.). Subsequent to the pre-bid meeting and the test pits, BES issued any addenda which changed the baseline boulder quantity in the GDSR to 1.7 boulders per foot of tunnel (varied from0.2 to 3.5 boulders per foot) a reduction of 67% from the original baseline. It is interesting to note the two separate tunnel reaches and how they were evaluated in the GDSR. Originally the Eastern portion of the work was projected at5.08 boulders per foot of tunnel and the Western portion at 5.30 boulders per foot of tunnel for a variance of less than 5%. In the revised quantity the Eastern portion was projected at 2.01 boulders per foot of tunnel and the Western portion at 1.42 boulders

Jan 1, 2003

By Peter Zhang, Daniel Su, Bo Kim, Berk Tulu

This paper summarizes significant findings from the ongoing NIOSH Gas Well Stability research over the past decade; in particular, the important ground control engineering considerations. Longwall-induced surface and subsurface deformations may induce gas well casing deformations and stresses, depending on a few parameters such as overburden depth, overburden geology, topographic relief, strata dip, gas well setback distance, and a gas well casing cementing alternative. Overburden depth to the mining seam is one of the most influential factors; shallow overburden depth induces large horizontal displacement and resulting casing deformation and stress, while deep overburden depth induces large longwall-induced vertical pressure. Overburden geology is another important factor affecting the longwall- induced casing deformations and stresses; the large contrast of bending stiffness at the soft-to-hard rock interfaces tends to induce large casing deformations and stresses. Large surface topographic relief and the presence of soft-to-hard rock interfaces below the stream valley bottoms may shift longwall-induced subsurface gas well casing deformations closer to the surface, thus having less impact on underground. mining operations. Strata dip magnifies longwall-induced deformations by 20% per degree of strata dip for down dip longwall excavations. The gas well setback distance is also a critical geometric parameter; the effect of longwall-induced deformation decreases exponentially as the setback distance increases. Longwall-induced casing deformation and stress will be mitigated or totally uncoupled for uncemented production casing.

Jun 25, 2024

The process design of a metallurgical plant follows logical steps, one built on another, to define the circuit requirements. The methodology used and documentation produced is the same for a pre-feasibility study, feasibility study or a complete design, regardless of the process complexity or the commodity. The only difference is the amount of detail developed at each stage. SRK Consulting, an independent, international consulting practice that provides focused advice and solutions to clients, mainly from earth and water resource industries, has consulted on many mining projects around the world. The company was formed in 1974 and now employs more than 1,600 professionals in more than 50 offices on six continents. According to SRK experts, the first element in plant design is collecting metallurgical testwork or operating data from an existing plant. The testwork identifies the process, the metallurgical recoveries and product qualities and establishes the process parameters for economic recovery of the commodity. Test samples must represent both the whole orebody and the feed over the life of the mine, showing the mineral?s variability. With this data available, the process design can be developed.

May 1, 2013

By Paul D. Tomlingson

Maintenance costs in the mining industry often account for as much as 18-20% of total operating costs and with the cost of labor and materials rising, they threaten to become an even larger percentage of the total. Yet, without an effective maintenance program costs can soar beyond what they would be without a program. In other words, when production equipment is down, there is no production and no product to sell in the marketplace. This cost of downtime in lost product far exceeds the actual cost of maintenance, which is defined here as labor and materials. Thus, mine management must have an effective maintenance program to avoid downtime and meet production targets. Attaining an Effective Maintenance Program Many mine management and operations supervisors believe that an effective program is a function of how hard they push maintenance. Yet, when vital production equipment is inoperable and production is lagging, no amount of pushing helps. In actuality, maintenance has little control over its own destiny and needs support from other departments to deliver good service. Success of the maintenance program depends on gaining control of those factors that directly influence maintenance. Consider the following. Organization-The maintenance organization must be structured for maximum responsiveness to production needs. Unfortunately, some needs are immediate and many are unknown in advance. The maintenance department has little control over them. These outside influences limit the department manager's ability to control his own organizational structure. Preventive maintenance procedures-Routine lubrication, equipment inspection, minor adjustments and the like are controlled mostly by maintenance. Yet, scheduling preventive maintenance depends also on the availability of equipment controlled by other departments. Planning-The purpose of planning maintenance jobs is to ensure that the best use is made of maintenance resources. If the production department creates an environment of running repairs and emergencies, there can be little planning. Even well-planned jobs will suffer if there is less than full cooperation in carrying them out. As a consequence, the maintenance department is not blocked from planning, but the value of its planning is reduced. Scheduling-Maintenance scheduling should be a joint effort. Although maintenance does the planning, production must agree to the scheduled maintenance of its equipment. Workload-As a service organization, the maintenance department has limited control over its workload because it must consistently respond to other department's demands. At best, maintenance controls only the fixed portion of its workload-utility work, janitorial service, maintenance shop work, and assigned repetitive and preventive maintenance duties. Unscheduled and emergency work are initiated by operations. Major maintenance actions require full cooperation. Labor productivity-The effective use of labor is tied to other key functions of maintenance. These include organization, preventive maintenance, planning, scheduling, and emergency work. An area type organization, for example, can often respond more quickly to immediate needs than a centrally controlled maintenance group. Yet, area maintenance can result in lower labor productivity unless tight control is exercised. One of the advantages of a good "detection-oriented" preventive maintenance program is early discovery of problems and better opportunity to schedule corrective work in advance. Under planned work conditions, use of labor can be more productive. Complete planning and scheduling can minimize time spent on each job, increase effectiveness of supervision, and improve labor productivity. Finally, if emergency work is minimized, there are fewer delays, less lost time, better coordination, and more productive use of labor. While labor productivity is an important factor in carrying out maintenance, it also is influenced by outside factors. However, few realize the impact of being able to improve maintenance productivity. By improving the productivity of 30 men from 30% to 40%, maintenance could accomplish the same work value as if it had added 7.5 men working at 40% productivity. 30 (1800) (40%) = 21,600 man-hr/yr 30 (1800) (30%) = 16,200 man-hr/yr Difference = 5,400 man-hr/yr 1800 (40%) 7.5 men Leadership-The maintenance department can have significant control over its own leaders, the front-line foremen, but they must

Jan 12, 1982

By Paul M. Keyser, Donald G. Foot, Jeffrey D. Mckay

In the past 30 years, there have been tremendous advancements in the uses and applications of column flotation. From their first use as final cleaners that could produce excellent grades at the cost of recoveries, columns are now being used in every stage of the flotation circuit as well as is SX-EW. Columns as roughers, final scavengers and even at the end of CIL circuits, are finding their way into the marketplace. Operational results of these new uses are presented. INTRODUCTION Flotation columns have been in use since the early 1950's in the U.S. (Hollingsworth, 1952) and the early 1960's in Canada (Trembley, Boutin, Wheeler, 1963). Application of column flotation has been somewhat diverse. In the early years, columns were used predominately for molybdenum cleaning in Canada and for phosphate flotation in the United States. Unfortunately, results met with skepticism and disdain as the columns were hard to operate, temperamental and although producing high grades, could not achieve acceptable recoveries. Since the inception of column flotation technology, the degree of knowledge for design and operation of columns has vastly improved. Despite improvements in the technology, there is still some reluctance by mineral producers to investigate the use of column flotation cells for processing stages other than cleaner flotation. This characterization is in part due to the proven advantage of flotation columns in reducing gangue entrainment in the froth product which results in higher grade products and/or fewer processing stages. Also, during the development of column technology, different types of spargers have been used with varying degrees of success. Furthermore, the general knowledge base of parameters affecting column flotation design and operation have advanced tremendously. Inefficient, or primitive, sparger design, coupled with the lack of column design and operating knowledge and experience, resulted in poor metallurgical and mechanical performance in many cases. Unfortunately, this lack of knowledge caused many column installations to be characterized as failures. The industry felt that columns could not achieve high recoveries, especially when dealing with coarse particles. Therefore, columns were characterized as cleaners, where low recoveries could be tolerated as recirculating loads rather than direct losses and froth cleaning advantages of the quiescent column flotation regime could be realized. Fortunately for the minerals industry, some producers have stood at the forefront of technology and allowed the column to be utilized for new applications. In the last decade, column flotation applications have expanded to virtually every mineral system and plant location throughout the world. The expanded application of columns has generated a new wave of interest for processing various streams. One of the most notable is in the use of columns as rougher cells. This is of particular interest to "green-field" plants and plants where expansions are taking place. Here, metallurgical superiority can be combined with maximum capital and operating cost advantages for a rapid return on investment. The superior results experienced to date, have generated a cohesive vision of the future in mineral processing where flotation columns function as single stage primary separation devices (roughers) with a single stage cleaner, if necessary. The advantages of column flotation go far beyond their original uses. We now have seen columns used as final tail scavengers, in SX-EW plants and even at the end of CIL circuits. Some of these cases will be reviewed. CASE STUDIES In an attempt to show the diversification of column flotation to many facets of the mineral processing plant, a variety of case studies will be discussed. Some of these were designed by the authors while others have been provided by plant sources. It is important to note that in each successful case, the columns were designed using the author's design and scale-up approach. This method assures that the columns are designed correctly for their particular application. For successful

Jan 1, 1993

By J. E. Moyle

Introduction In October 1983, Rio Algom Ltd. decided to develop the East Kemptville tin deposit. This decision was the result of intensive geological and metallurgical evaluation work, as well as careful studies of environmental and marketing aspects. The property is located about 54 km (34 miles) northeast of Yarmouth, Nova Scotia, near the village of East Kemptville. Geology The geological setting is a granitic intrusive at the contact with metasediment. The tin mineralization is in the form of cassiterite (SnO2), which is about 80% tin. Sulfides are associated with the deposit containing silver, copper, and zinc, which are recoverable as byproducts. The mineralization is associated with quartz veins and greisen alteration. In the center of the deposit, the zones are so close together they have the appearance of a massive or porphyry type deposit. Ore Reserves The mine plan is based on 56 Mt (62 million st) at 0.165% tin. Up to the ninth year, mill feed will average about 0.2% and lower grade material will be stockpiled. In later years, the average grade will be 0.16% tin. A 0.08% cutoff grade is planned for the entire 17 years of production. East Kemptville is a relatively low grade tin deposit, and only a combination of favorable circumstances has made it economic. • The ore body is situated at, or very close to the surface, permitting mining by open-pit methods at a very low stripping ratio. • The tin occurs in relatively large crystals that allow for good recovery by gravity techniques. • It is ideally located in a well-settled area, with all essential infrastructural requirements already in place. • The positive and cooperative response from various governmental agencies involved are encouraging. Mine Plan The mine plan incorporates an initial pit, followed by three expansions to the ultimate pit. Mining will be at 14 kt/d (15,000 stpd) and will include 9 kt (10,000 st) of ore plus 5 kt (5,500 st) of waste and low grade. After five years, the mining rate will increase to 21 kt/d (27,500 stpd). It is planned to drill vertical 165-mm (6.5-in.) blast holes on a 6-x 6-m (20- x 20-ft) pattern. Bulk slurry explosives will be used to break the rock. Loading will be with hydraulic shovels into 70 t (77 st) haulage trucks. The trucks will deliver the ore to a 13 x 20 m (42 x 65 ft) gyratory crusher, where it will be crushed to 150 mm (6 in.). Secondary and tertiary cone crushers will be used to further crush the ore to 13 mm (0.5 in.). Process Design Tin extraction technology is practically unknown in North America, but Rio Tinto Zinc, which has a 53% ownership in Rio Algom, is involved in tin production in the UK. Rio Algom has used this experience and expertise in metallurgical evaluation work and in tin-related aspects of plant design. Mineralogical and metallurgical test work have been performed, both on laboratory and pilot plant scales. Mineralogical work was done largely in the UK, the laboratory test program was carried out at the Lakefield research facility in Ontario, and pilot plant work was conducted in Australia. This program has resulted in significant improvements in recovery and concentrate grades, over best projections that could be made before this work was carried out. Concentrating Process The concentrator is being designed to process about 9 kt/d (10,000 stpd). The first step is to reduce the size of the ore to -700 µm (-24 mesh) in a rod mill/ball mill grinding circuit. The ball mill will operate in closed circuit with high capacity banana-type screens. The screened product will be deslimed to 30 µm (560 mesh) with cyclones, then passed over the pri-

Jan 4, 1984

By John Relser

The production processes that are developed in the mining and minerals industry are manufactured to be exposed to very aggressive environments. Chemical, abrasion, and impact expose structures and equipment, steel or concrete, to a significant deterioration. This causes damage and adds high costs to operations that can be reflected in the destruction of equipment and structures in the arrest of the production process, which becomes very costly. Also, there is the potential for personnel accidents, which would require large sums of compensation for an employee, thus directly harming the image of the mining operation and company. Manufacturers of paints and coatings that have major centers for research and development (R&D Labs) distributed globally have developed high-tech products for durable protection from the elements for structures and equipment used in the mining industry. The difference between these paintings and coatings and what is normally known as conventional paints (e.g., those called domestic or decorative), is its chemical composition, structured around polymeric components that have highly resistant, chemical and physical properties to cope with extreme conditions to which they are exposed. With this, and only this, longer life of components can be achieved for equipment and structures used in the production processes of the mining industry. Today, in addition to the important features mentioned, some manufacturers of the paints and coatings dedicated to this highly modernized process have invested large sums of money in developing new products that add operational elements to the painting process. These coatings provide added value and significant performance to companies mining operations and that we can describe in three fundamental concepts:

Feb 1, 2014

By Felicia F. Peng

In operation of column flotation of fine coal, the smaller bubbles are required to effectively recovery of fine hydrophobic particles. However, smaller size bubbles alone does not ensure an efficient flotation for fine particles. The sufficient available bubble surface area per unit column are essential for effective column flotation. The experiments are conducted in a lab-scale column using two different bubble size distributions and three different particle size distributions for flotation of Pittsburgh No.8 seam coal. The interaction between particle size, aeration rate, feed rate and wash water addition are examined in this investigation to establish the optimal operation conditions for flotation of fine coal. Despite of wide range of operation conditions used in this study, it is found that the experimental data fall in a single characteristic recovery-ash curve for a given bubble size distribution and particle size distribution. The major parameters affect the flotation performance points along -the characteristic recovery-ash curves are aeration rate/frother dosage, feed rate and wash water rate-.

Jan 1, 1994

By H. I. Morrison, A. J. deVilliers, D. T. Wigle, H. Stocker

INTRODUCTION At the end of 1959, high levels of radioactivity attributed to radon and its daughter products were discovered in the fluorspar mines at St. Lawrence, Newfoundland. These levels were presumed to be the cause of an unusually high incidence of lung cancer among the fluorspar miners (deVilliers & Windish, 1964) (Parsons et al. 1964). The mining of fluorspar (calcium fluoride) began in 1933 as open pit operations but converted to standard underground mining procedures in 1936. During the second world war, production was greatly expanded as a result of increased demand for fluorspar used in the production of steel. Wet drilling was first introduced into general use in 1942. Ventilation was mainly by natural draft occasionally supplemented by small blowers. The amount of ventilation varied greatly between mines as well as over time. For example, one large mine, the Iron Springs mine, had only a single small raise to the surface some 600' from the central shaft. Other mines, such as the Director mine, had a number of raises to the surface and, as a result, had far better ventilation. Mines also varied by the amount of ground-water which seeped into them. In the early 1950's, an unusually large number of lung cancer cases were diagnosed among the fluorspar miners. As a result, in 1956 and 1957, J.P. Windish of Canada's Department of Health and Welfare tested for possible causative agents in the mines. Unfortunately, radon measurements were not conducted until 1959 and 1960 when Windish tested Director mine as did the A.D. Little company in 1960. As a result of the high radon levels found, mechanical ventilation was introduced and the concentration of radon dauthers fell, on the average to well below 1 WL. During this period, lung cancer cases continued to be diagnosed with 29 lung cancer deaths recorded by 1964 and 71 by 1971. As of July 1981, 105 lung cancer cases had been identified (Hollywood, 1981). Previous reports concerning the fluorspar miners have dealt in detail with the factors in the occupational environment and discussed occupational mortality patterns. The purpose of this paper is to review further the mortality experience with particular reference to lung cancer in relation to cumulated radiation exposure and to describe briefly our ongoing study of this group. METHODS Occupational histories were prepared for men who had been employed by the mining companies at St. Lawrence during the period 1933 to 1977. The histories were compiled from company records except for the period 1933 to 1936, records for which were lost in a fire; however, the occupational histories for this period were completed by searching census records and interviewing company officials, ex-employees and others. In addition, occupational and smoking histories were also obtained for some miners during a survey conducted in 1978. Occupational records included name and date of birth as well as the type, place and hours of work by year. For each year prior to 1960, hours of work were converted to working months (1 WM = 167 hours) and were multiplied by the estimated average radon daughter concentration in working levels (WL) to yield the annual radiation exposure in working level months (WLM). Pre-1960 radiation levels were estimated on the basis of the history of mining methods employed, ventilation history of the mine, type and place of work and conditions under which the first radiation measurements were made in 1959 and 1960 (deVilliers and Windish, 1964). During the period from 1960 to 1967, the average exposure was about 0.5 WL. Beginning in 1968, radiation levels were measured more frequently, and, beginning in 1969, daily exposures for each worker were recorded based on radiation levels in the place worked on a given day. Mortality data were obtained from medical certificates of death. In a small number of cases, medically certified death certificates were unavailable. In these cases, probable cause of death were obtained from forms completed by the local clergyman (returns of death), parish records, information obtained from interviews with family members of the deceased and/or hospital information, before assigning a cause of death. Data obtained from these sources were found in Tables 1, 2 and 4, cover the time period 1933 to 1971. Data in Table 3 as well as in Figures 1 through 3 cover deaths from 1933 to 1977, and includes only those miners for whom medical certificates of death were available. Two medically certified causes of death were changed from other causes to lung cancer on the basis of pathology reports.

Jan 1, 1981

By C. J. Gilbert

The mining method at the Cannon Mine uses heading and bench stopes, which are subsequently backfilled with cemented high-strength fill prior to pillar removal. The dimensions of the pillars, 24 feet wide by G5 to 95 feet high, re-quire careful blasting in order to not damage the rock, compromising pillar strength and complicating later removal. Additionally, the proximity of dwellings makes vibration control a must for good-neighbor relations. A blast monitoring study was conducted in order to optimize bench blasting practices to maximize fragmentation, reduce costs, minimize well damage, and minimize ground vibration.

Jan 1, 1989

By Kwangmin Kim, Taehee Lee, Minkyu Kim, JUNHYEOK PARK

Mine tailings storage facilities (TSFs) can be a significant source of fine, respirable dust. About 25 percent of the mass fraction of tailings from a hard-rock mine consists of particles of a respirable size (smaller than 10 μm) [1]. This dust poses concerns, especially for nearby communities, because of its detrimental impact on respiratory health. Respirable tailings dust, primarily composed of quartz or free silica (SiO2), may cause silicosis, chronic pulmonary disease, bronchitis, collagen vascular diseases, and chronic granulomatous infections [2]. 

By CLAIRE STREBINGER, ADITYA JUGANDA, JURGEN F. BRUNE, GREGORY E. BOGIN JR.

Methane gas explosions are a major risk in underground coal mining operations. The severity of such explosions can range from local area damage to massive loss of miners’ lives along with significant damage to mine infrastructure and ventilation controls that may lead to mine closure and loss of the entire operation. This study demonstrates the viability of integrating a computational fluid dynamics (CFD) combustion model into a longwall mine ventilation model to simulate methane gas explosions in the longwall face area. The resulting 3D methane gas explosion simulation can provide better understanding of the fundamental physics and the potential impact of an explosion in an underground longwall coal mine.

Aug 1, 2022

By R. H. Smith

The total energy demand in the United States increased about 4 per cent annually during the 1960's 1 and is expected to increase at the same rate during this decade. Z Fuel oil growth in the 1960's was only Z per cent per year until 1968, but it increased to 8 per cent in 1969 and 11 per cent in 1970. Fuel oil demand is expected to grow at a 6 per cent rate through the 1970's. Part of this rapid increase in demand has been caused by restrictions placed on the sulfur content of fuels. High sulfur coal can no longer be burned in many parts of the country and has been replaced by low sulfur fuel oil. An insufficient supply of natural gas has also contributed to fuel oil demand. Air pollution regulations have not only caused an increase in fuel oil consumption, but they have also caused a reduction of sulfur content in residual fuel oils. Current regulations call for 1 per cent maximum sulfur content fuels over much of the country. Sulfur contents of fuels are limited to 0. 3 per cent in certain areas on the east and west coasts. Sulfur in residual fuel oils from high sulfur imported crude oil is reduced to 1 per cent currently. However, sulfur reduction to 0. 3 per cent is difficult and expensive.4 As a result, refiners may be hard pressed to supply the market for low sulfur fuel oil. The oil shale deposits in Colorado and Wyoming potentially are a huge source of low sulfur fuel oil. It will be shown that the low sulfur content and more importantly the sulfur

Jan 1, 1972

By John Litz

The term "refractory gold ores" refers to a wide number of ore types which are not readily amenable to direct cyanidation. A number of processes have been used commercially, and a number of others have been proposed and in many cases pilot tested. The selection of the appropriate process for an ore should not be arbitrary. Ore grade may preclude some processes, but a good understanding of the ore mineralogy can guide the selection. Many present gold operations and many potential gold operations have faced or are facing problems with refractory gold mineralization. We at Hazen Research have had the opportunity to perform bench testwork and in some cases, pilot plant testing on a number of refractory ores. The data included in this paper are excerpted from the testing of fifteen ores which cover a wide range of mineralogical compositions. This paper is not intended to be a treatise on the processing of refractory gold ores. In many of these gold projects, not all of the standard process alternatives were evaluated, nor was adequate mineralogical work performed. Such is the dilemma of contract research. "If I believe that I don't need it, why should I pay to have it done." The intent of this presentation, therefore, is to show how different ores respond to the various processes, and to demonstrate that one must have an open mind when developing a process for a specific refractory gold ore.

Jan 1, 1998

"The 33rd annual American Mining Hall of Fame Awards Banquet and Fundraiser sponsored by the Mining Foundation of the Southwest (MFSW) will be held at the JW Marriott Tucson Starr Pass Resort & Spa on Saturday, Dec. 5, 2015. Each year, one living Hall of Fame inductee, two Medal of Merit recipients, several honorees from Mining’s Past, an Industry Partnership Award and a Special Citation are recognized for their respective contributions to the mining industry.Conrad E. Huss, cofounder of M3 Engineering & Technology Corp. located in Tucson, AZ, will be honored as the 2015 Hall of Fame Inductee and will serve as the keynote speaker at the awards banquet. Huss has served his company as chairman of the board for its entire 30 years and guided M3 to become a full discipline firm. Now M3 offers complete project execution through engineering, procurement and construction management procedure and has become a major engineer of large observatories around the world. The company now has more than 1,000 employees with offices in Arizona, North Carolina, Mexico, Argentina and is incorporated in Guatemala, Peru and Canada.The Medal of Merit will be awarded to Charles Michael (Mick) Lownds, founder of his eponymous consulting firm in Salt Lake City, UT, for his 42 years in commercial explosives following tenure at Sasol and at Orica. Originally from South Africa, Lownds immigrated to the United States in 1998 and has made significant advancement on electronic initiation systems. Lownds has published numerous technical papers, is an inventor with 12 awarded United States patents and was also the recipient of the President’s Award from the International Society of Explosives Engineers in 2000.Medal of Merit for young professionals will be awarded to Fiorella Giana, Freeport- McMoRan Inc.’s (FCX) mine manager at Bagdad. Born in Buenos Aires, Argentina, Giana left the small cattle farm where she was raised in 2001 to pursue higher education in the United States. For the past decade at FCX, as a result of her extraordinary combination of technical skill, leadership and commitment to excellence, she has been given positions of progressively greater responsibility from an entry level engineer to senior mine engineer, to chief engineer and now as mine manager, a position rarely held by woman."

Jan 1, 2015