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By N. Arbiter

During the first four decades of flotation practice, close to 200 machine designs were patented, although only about a score were ever used commercially. By the end of that period, the rigors of use had resulted in obsolescence of most pneumatic cells, with a few mechanical cells dominating the field. After World War II, newer designs began to appear but most were modifications in varying degrees of older designs with special features added. Of the dozen or so most recent developments, almost all are pneumatic, relying on compressed air instead of impellers for motive power, although in several cases pumps supplement compressors. Table 1 lists a few of the more fully documented new cells, with their significant characteristics, along with similar characteristics of a widely used mechanical cell. New designs in general are emphasizing: bubble size control; in several cases, methods for delivering feed directly to the froth; methods for introducing and dispersing air through nozzles, eductors, packed beds, or permeable walls; and variable cell volumes, relative to capacities, ranging from very small, with less than a second of retention time, to the largest, with retention times of over 20 min. An important question is the extent to which any of the newer designs are based on locating weaknesses in current mechanical cell designs and then using these as a starting point for innovations. In the present study, the key subprocesses which must take place in a cell are outlined; mechanical cells are analyzed to establish where weaknesses may exist; and then alternative subprocesses are considered which could effect improvements. COMPONENTS FOR CELL DESIGN It is assumed that mineral surface chemistry has been modified as necessary to provide optimum potential floatability. While the cell process may affect this to a degree, cell design is primarily concerned with actualizing the existing potential floatability. The cell design problem is to provide more effectively for the following: 1) Dispersion of air to obtain an optimum bubble size distribution at an optimum ratio of air volume to feed volume. 2) A hydraulic environment which permits most effective contact of potentially floatable particles with bubbles: [Table I - Cell Comparisons* Cell Type Mechanical Column Deister Miller ASH No. of units Multiple Single Single Single Retention time min.10/20 17/27 3.8 ca. is Capacities mt/m3s 0.022/0.066 0.066/0.20 0.11 10.4 st/ft3d 1/3 0.3//0.9 m5.0 469 Air hold-up % 15/20 20 n.a. 50/80 Air escape velocity m/s 0.015/0.0200.020/0.025 n.a. n.a. ft/m 3/4 4/5 n.a. n.a. * References: Mechanical (Harris, 1976,1985), (Bassarear, 1985); Column (Travis, et al. 1987); Deister (Zipperian and Christophersen, 1985); ASH (Air-Sparged Hydrocyclone) (Miller 1989).]

Jan 1, 1989

By Gordon R. S. Smith

This paper is in two parts. The first part describes Membrane Back-Pulse Filtration and the effects of very short filter downtimes on cycle filtration rates. Part II describes the use of Membrane Back-Pulse Filtration for combined thickening and polishing soda ash thickener feed material followed by a description of computer modeling of CCD circuits by Iterative solver.

Jan 1, 1991

By K. S. Narasimhan, T. C. Rao, R. Bhima Rao

Investigations have been carried out to evolve a grinding aid useful in grinding a 40% iron-bearing magnetite containing quartz as the major gangue, based on studies conducted with pure magnetite, pure quartz and its synthetic mixture. These investigations established that an addition of 200 g of CaO per metric ton of ore was the most effective in grinding quartz preferentially over magnetite at 75% solids concentration by weight. The limited rheological studies conducted suggest that the effect could either be due to dispersion or the structural modification of quartz. More importantly, a new concept, that of Critical Solids Concentration, where two different minerals behave like one with respect to response to communication in a tumbling mill, has been introduced for the, first time. Above this concentration, one of the minerals is ground at a faster rate than the other, whereas the reverse is the case below this concentration.

Jan 1, 1992

By John D. Hanifin, C. Kevin Moon, Eric C. Wang

Value Engineering on Connecticut DOT’s Walk Bridge selected the trenchless option for utility relocation to address the channel crossing’s environmental concerns. The design and construction considerations of the twin micro-tunnel drives and associated shafts are presented. Key challenges included vertical alignment selection to achieve minimum one-tunnel diameter stable cover within thin glacial till underlying extremely soft clay, limited choice of pipe and joint materials meeting stringent non-metallic conduit requirements, thermal grout backfill application, and the close proximity of temporary trestle piles. Mitigation measures were developed for potential point loading pipe damage from remnant boulder fragments in the annular space.

Dec 1, 2022

Evver since it first displayed an autonomous mining truck at the 1996 MinExpo show in Las Vegas, NV, Caterpillar has been building the blocks to a fully autonomous mine. In May, the company unveiled another block in that progression, the new Cat MineStar System that it says is ?the industry?s broadest, most comprehensively integrated miner operations and mobile equipment management system.? The full system is comprised of five capability sets ? Fleet, Terrain, Detect, Health and Command ? to help operators define the size and scope of their management system based on the needs of their mining operations. Michael Murphy, technology and autonomy manager for Cat Global Mining, explained that the customers were not ready for an autonomous mining truck in 1996, but that many customers wanted the building blocks to eventually get to autonomous mining. After 15 years of work, Murphy said the building blocks have come together in the form of the Cat MineStar System.

Jan 1, 2011

By Steven J. Schatzel, Kayode M. Ajayi, Marcia M. Harris, Zoheir Khademian

Predicting rockmass permeability is critical in evaluating various engineering designs, including estimating gas inflow to a longwall mine in the case of a hypothetical breach in the gas well. This study conducted field permeability measurements to validate a geomechanical model capable of predicting rockmass permeability during longwall mining. A series of slug permeability tests were conducted in an active mine in Pennsylvania. A model of the mine was constructed in 3DEC numerical modeling software, and permeabilities were calculated. The modeling results agreed well with the pre- and post-mining permeability measurements, showing the applicability of this tool to evaluate gas well stability near mine workings.

Feb 1, 2024

By R. J. Sheets

"What is the primary responsibility of geo-engineers in mining? Early in my career, I was asked this question by an experienced engineer. After explaining some various tasks, I was informed that the main responsibility was to monitor. Although this proved true for many cases, I came to understand that monitoring is merely one means to achieve the primary responsibility of a geo-engineer — ensure the safety of all personnel. The potential for groundwater to impact stability allows this responsibility to be shared with hydrogeologists as well. Inherently, we monitor to identify risks; we analyze designs and develop models to mitigate risks; and we are provided opportunities to explain to supervisors the geo-risks to personnel and mine plans that will result from particular courses of action. A couple years ago, I took an opportunity to share experiences from the first several years of my career as a geotechnical engineer with junior geoengineering staff within my company. The intent was to share situations that were a part of my development, so they could learn and understand their responsibility to the safety of all personnel. Similarly, the purpose of this article will be to share these thoughts with new geo-engineers in the industry in order to help prepare them for the challenges they will face.What is our purpose?A senior hydrogeologist shared an experience that occurred in their career. The experienced hydrogeologist had spent some time with the hydrogeology staff, most of them relatively new to the mining industry, to understand how they viewed, and carried out, what they perceived as their responsibility at an active mining operation. After a couple months of observing and mentoring, the senior hydrogeologist met with everyone and posed the question “What is our purpose?” I am sure that most junior geo-engineers would start explaining different tasks or projects that they must complete. The list would include monitor ground water levels, track slope movement, evaluate designs, build models, oversee drilling programs, etc. These individuals did as well their supervisor. After going around the room allowing each individual to answer, the experienced hydrogeologist provided them the real answer to the question: Safety. If you examine the root intent of nearly every responsibility geotechnical engineers and hydrogeologists have, it is to apply our professional skills to ensure the safety of our workforce. When the objective of safety from the geotechnical and hydrogeology disciplines is achieved, inherently accomplishing the mine plan should follow suit, or it should significantly minimize the impact by gravity or ground water."

Jan 9, 2018

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 J. C. Gathje

The Robinson copper ores were mined for many years from pits containing varying ore grades, sulfide and oxide ore types, and differing mineralogy. The ores also contain gold and molybdenum values, and their recoveries are an integral part of the flowsheet development. Metallurgical responses were characterized using a standard flotation procedure. Further studies investigated primary and regrind particle sizes, reagents, and other variables. The metallurgical testing was supported by mineralogical studies. Results demonstrated a high degree of metallurgical success for flotation. Final copper concentrates ranged in grade from approximately 28 to 30% copper and copper recoveries were 89 to 95% based on laboratory and pilot plant data.

Jan 1, 1992

By Francesco Chiappalone, Franco Gasperin, Fabrizio Fara

This document describes the challenging task of mining through tiebacks using a 21'-8" diameter Tunnel Boring Machine (TBM) as part of the Ship Canal Water Quality Project. The mining operation involves navigating through 17 tie-backs that are evenly spaced at 8-foot intervals, with many intersecting the full face of the cutterhead. Detailed analysis and review of TBM parameters specific to this area have been conducted to ensure operational efficiency and safety. Hyperbaric interventions have been planned and coordinated, encompassing pre-mining preparations, continuous monitoring and adjustments during the mining process, as well as post-mining measures. The document highlights the complexity and importance of strategic planning and execution to successfully overcome the tie-back intersections during the mining operation.

Jun 23, 2024

By R. R. Klimpel

In this first report, we present a preliminary model based on the simple binary sys¬tem of component B occluded in a matrix of compo¬nent A, for the case where fracture planes can pass with equal ease through A or B. By assuming that the volume fraction of B in AB in the overall matrix is small, which is realistic for many prac¬tical systems, the problem is reduced to a one-¬dimensional treatment which is conceptually easy to understand. The model was programmed for Monte Carlo simulation, and an analytical solution also developed based on the assumption of zero or one mineral fragment per particle. Preliminary ex¬perimental confirmation using a synthetic "mineral¬-host matrix" of known amount and size of B in AB is presented.

Jan 1, 1983

By R. L. McNearny

A comparison study was conducted between an actual physical model and a numerical model based on the physical model of the block cave mining method. Results from the numerical analyses closely simulated the blocky behavior of the physical models, including bridging and interlocking of the simulated orebody during draw. The draw-down patterns and the rate of draw developed during numerical modeling also closely simulated the physical models. An unexpected result from the numerical modeling was the development of a zone of downward deflection which preceded the development of the zone of material movement.

Jan 1, 1997

By R. L. Virta

Common clay is a natural, fine-grained material composed of hydrous aluminum silicates. Shale is a laminated sedimentary rock formed by the consolidation of clay, mud and (or) silt. Government and legislative programs The U.S. Environmental Protection Agency (EPA) invited industry to nominate representatives to a review panel that will help the EPA develop rules to regulate air toxics from the production of brick and structural clay products. The EPA was required to establish a review panel because these regulations will significantly affect small businesses. The regulation of air toxics falls under the Clean Air Act.

Jan 1, 2010

By John F. Burst

For several generations now, the high alumina clayey sediments of Southeastern Alabama and Southwestern Georgia have supplied those regions with steady, mineral-based income although the impact of that income has been relatively minor until recently. Since World War II, mining activity has increased algebraically with over half of the total ore value in the Alabama area having been recovered since that time. The Georgia area production increases are even more dramatic. The trends are continuing and the next decade should see ore winning figures which will dwarf all previous production. It's time for the mining engineers to take note of this development as the mining methods, similar to the production, have developed rapidly and now offer challenges for the most competent professional. The development of mining techniques has followed a classic pattern. Beginning almost a hundred years or so ago, with the loading of weather-resistant surface boulders into mule-drawn wagons, mining methods have progressed to discovery of limited surface exposures in outcrop and eventually to stripping and development of non-obvious, subsurface deposits. Little by little, the overburden thickness of new pits has increased until, at present, pits with 100' -125' of overburden are being actively worked. Ground water problems in the Eufaula District are particularly challenging. At A. P. Green's J. W. Baker Pit, #l, in Barbour Co., Alabama, it is necessary to continually pump groundwater at the rate of about 400 gallons per minute from wells on the periphery of this large pit in order to keep the water table low enough to allow mining of the ore body.

Jan 1, 1972

By K. T. Dreher, J. A. Brierley, C. L. Brierley

Water from underground uranium mines located in the Ambrosia Lake district near Grants, New Mexico, U.S.A., is treated to reduce levels of uranium, selenium, radium and molybdenum. The treatment system consists of a series of ponds and an ion exchange plant. Bacterial and algal populations present in the pond system are considered agents which actively assist in removal of the pollutants present in the water. Pondbottom sediments maintain a reducing zone and a large population of sulfate-reducing bacteria of the genera [Desulfovibrio] and [Desulfotomaculum]. Uranium, molybdenum, and selenium accumulate in the pond sediment. Stimulation of the microbial sulfate-reducing activity resulted in a decrease of soluble concentrations of these elements in laboratory systems. Predominant components of the treatment ponds’ algal flora are the filamentous [Spirogyra] and benthic [Chara]. Laboratory study indicates that [Spirogyra] is more active than [Chara] in removal of uranium and molybdenum from solution. However field-collected algal samples of both of the genera contain uranium and molybdenum. Laboratory studies indicate that death and decay of the algae in association with pond sediment does not result in return of cellbound uranium and molybdenum to the water. The algae appear to act as bio-filters for accumulation of particulate pollutants and agents for adsorption and/or absorption of soluble pollutants.

Jan 1, 1980

By R. L. De G. Solms

INDEX 1. INTRODUCTION 2. FLOODING 3. THE PLUG 4. THE FIRST ATTEMPT 5. THE SECOND ATTEMPT 6. PUMPING 7. TIGHTENING OF THE PLUG 8. SHAFT REPAIRS 9. POST-MORTEM 10. CONCLUSION

Jan 1, 1987

By Eva K. Fernandez, Paul Y. Louie, Derek S. Adams, Renée L. Fippin

The Folsom Area Stormwater Improvement Project is part of SFPUC’s flood resilience efforts under the Sewer System Improvement Program. This 4,000-foot-long, 12-footinside- diameter tunnel will help reduce the risk of flooding in San Francisco’s low-lying Inner Mission neighborhood. The project is in a high seismic hazard zone and extends through a complex geologic corridor that includes full-face soft, compressible Bay Mud, Colma Sands, and full-face rock with several stretches of mixed-face conditions. Additional challenges include removal of 99 piles beneath an existing box sewer, tunneling under commuter rail tracks, and an underground tie-in. This paper examines these challenges and how they are being addressed.

Jun 13, 2023

By Brianna Eiter, Max Barham, Tim Bauerle

While not well established, there is evidence that the mining industry is encumbered by several work-related fatigue risk factors. Compared to other industries, mine workers are more likely to report inadequate sleep and work longer hours per day. Given these observations, there is a critical need to identify effective ways to intervene, manage, and mitigate mine worker fatigue and sleepiness when present. One barrier to this is confusion around the similarities and differences between fatigue and sleepiness, which can result in these terms being treated as interchangeable regardless of context and make it difficult to assess and mitigate safety risk.

May 1, 2024

By C. D. Taylor, A. L. Mazzella, A. L. Martikainen

In fluctuating airflow, continuous air velocity recording is the most reliable method of air velocity measurement. It allows for fast recognition of changes and the calculation of long-term averages. Also, it enables the mine operator to identify when the airflow has decreased to a point requiring action. Using ultrasonic anemometers provides an accurate option for continuous air velocity monitoring. This paper provides information about the effect of common obstructions in underground mining on air velocity readings. Stationary and moving obstructions are used to represent workers and equipment that would cause discrepancies in measured airflow. Also, it is important to know how large of a sample size is required to ensure reasonable accuracy of results. Statistical analysis is used to evaluate the required sample size. The sampling procedure is further studied by comparing two different sample rates. The results show that obstructions provide noticeable differences in air velocity measurements. Also, movement of obstructions can be recognized from changes in results. Surprisingly small sample sizes provide reliable air velocity information. Standard sample rates are found to be suitable for the underground environment.

Jan 1, 2011

By Donald A. Dahlstrom

If you have ever driven on the Autobahns of Western Germany, you are well acquainted with the "fast lane." There is no speed limit; there are only two lanes in the direction you are going, and if you choose to drive in the fast lane, you had better be prepared to drive faster than anyone or someone will tailgate you with a constant screeching horn until you move to the "slow lane." The prize for this mastery of the fast lane is some kind of a "macho" feeling and getting to your destination sooner than your competitor. This has some comparisons with today Is liquid-sol id separation. We've certainly had our moments in the fast lane but we've also had other countries forcing us into the slow lane at times. It can be very embarassing when someone almost runs over your back and then shakes a fist at you as you shakily scatter to the much slower and overcrowded lane. Because of necessity, there will be many new improvements and added requirements in the next decades into the 21st century and beyond. Those countries and industries that can maintain the pace in the fast lane will be successful while the others may well be relegated to the non-competitive lane. Before considering what will be the challenges in the future for competitive liquid-sol id separation performance, it would be wise to review progress over the past forty years in this area. The author has to admit his ancient age and believes he can act as an evaluator of these many advances. To place the beginning of the 40 years (the author predates his initiation into liquid-sol id separation by one more year), the United States was still building smelters and operating them with little or no sulphur dioxide removal , practically

Jan 1, 1989