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By K. Whiting

In October 1993, the first two of a series of full scale passive biological treatment cells were constructed to treat mine drainage from the Burleigh Mine (located approximately 48 km west of Denver, Colorado in the Clear Creek/Central City Superfund Site). The two cells are each 19-21 m long, 10.7 m wide and 1.2 m deep. Each cell contains approximately 216 cubic meters of substrate (composted manure) and is designed to treat 60 L/min of mine flow. One cell is designed as an upflow reactor and the other cell is designed as a downflow reactor. The differences in flow hydraulics and treatment efficiencies will be tested in these two cell for approximately nine months before the remaining cells are built to treat all the discharge. The substrate material was selected based on a series of bench scale tests. During the tests, the amount of metals removed was determined. The design flow rate was based on a sulfide generation rate of 400 nanomoles of sulfide generated per cubic centimeter of substrate per day. Metal removal results for the first three months of operation of the two cells will be presented and compared to results of bench and pilot studies at other sites.

Jan 1, 1994

By Kirsten Corin, Belinda McFadzean, Cyril O’Connor, Jenny Wiese

As orebodies being mined globally are of ever-decreasing grades, the focus on the concentration process has moved increasingly to the challenges faced in management of the gangue minerals. This is especially so in the flotation of platinum group minerals (PGMs), where head grades are typically in the region of 4–7 g/t. Hence, in PGM operations, a typical recovery of about 80 percent requires depressing about 85 percent of the gangue minerals. In a flotation cell the main control parameters are reagent type and dosage, froth depth and air addition rate. This paper reviews research projects carried out over an extended period aimed at optimizing the depression of gangue minerals: both those that are naturally floatable and those, such as chromite, that are entrained.  This has involved comparing the two major depressants used in the industry — guar and carboxymethylcellulose (CMC) — in the depression of the relevant gangue minerals, as well as investigating their consequent effect on the behavior of the froth phase. Because most PGM flotation plants treat the ore as if all the PGMs are associated with sulfides, copper sulfate is widely used as an activator, but this can also lead to inadvertent activation of gangue minerals. Finally, chromite levels must be kept below 3–5 percent to avoid any negative effects on smelter performance, and thus it is important to reduce chromite recovery which mainly occurs due to entrainment through, for example, froth depth control.   

By C. Botha, M. J. Walls, C. T. O'Connor

The role of copper sulphate in the flotation of pyrite has been studied. A survey of a number of pyrite flotation plants using copper sulphate showed that in correct dosages, it was able to increase both grades and recoveries. This was confirmed in batch tests. Copper sulphate had no significant effect on the rate of adsorption of PNBX onto pyrite. Copper adsorbed irreversibly onto the pyrite when the latter was slurried in a copper sulphate solution. Copper sulphate had a significant effect on the maximum froth height obtained in static three-phase froth tests. Proposals to explain these observations are made.

Jan 1, 1998

By T. Bajpayee, L. Prosser, A. Iannacchione

Reducing the number of roof fall injuries is a goal of the NIOSH mine safety research program. Central to this effort is the development of assessment techniques that will help to identify the nature of the risks associated with working under potentially hazardous roof conditions. This paper discusses a method to determine the roof fall risk using a qualitative risk analysis technique. The ability to determine roof fall risk has been a long-standing goal of safety professionals and can provide the kind of information, needed by on-site personnel responsible for worker safety, to mitigate roof fall injuries.

Jan 1, 2007

By B. Andersen

An accurate knowledge of Interactions among mineral particles and between such particles and dissolved and precipitated species Is Important in developing efficient separation processes. In this investigation interactions in Florida phosphatic clay waste, that are relevant to dispersion and selective reagent adsorption, the two main prerequisites for selective flocculation, were studied. Initial studies with artificial slimes, consisting of pure clay and phosphate minerals, showed dispersion of artificial slimes to be relatively easy. The problems that were encountered during selective flocculation of the artificial slime were due to unselective polyacryllc acid adsorption on clay, which was caused by the presence of multivalent calcium ions on the exchangeable cation positions on the clay surfaces. This problem could be solved by exchanging calcium for sodium, which reduces the interaction between the polymer and the clay surface. This procedure, however, was not successful for mineral mixtures. Natural slimes were found to be much more difficult to disperse. This was attributed to the presence of cementing materials such as humic substances and Ai and Fe (hydr)oxide precipitates. Selective removal of these cementing materials resulted in good dispersion and partial separation. Further increase in separation of natural slime is likely determined by the presence of calcium on the clay surfaces, as was found for the artificial mixtures.

Jan 1, 1992

By Gerhard Sauer, Heimo Gold

The main advantage of the New Austrian Tunneling Method over conventional drill and blast techniques, TBMs and shields is its outstanding flexibility. Many different support concepts help to cope with all but the most adverse conditions. A considerable variety of unique additional support measurements provide a functional tool when dealing with particularly difficult conditions or restricting requirements. The resulting adaptability of NATM with respect to geometric and geologic changes is a cornerstone to providing an economic design and to a safe and unhindered execution of the tunnel work. To take best advantage of this flexibility and to emphasize its cost-saving capacity, NATM explicitly extends the design period into the construction phase. In accordance with corresponding ground classes or other anticipated conditions, a number of basic support categories and an array of additional support measurements are established during the actual design phase. The decision for applying a particular support category at a specific location and for necessary additions to the given support scheme, however, is regularly made on site after each advance, and is determined by the key persons involved in the construction. Contract documents must reflect this approach to facilitate the execution of the work and to curtail construction costs. Biased distributions of risks, however, can adversely effect the envisioned benefits. Consequently, the respective responsibilities of engineer, contractor, and client need to be redefined.

Jan 1, 1989

By Richard C. Fountain

The Central Florida Phosphate District is located in southwestern Polk, southeastern Hillsborough, Manatee, and Hardee Counties, Florida, flanking the.southern end of a major structural uplift known a the Ocala arch. Ore control problems here are varied and unique due to non-homogeneity of matrix and high volume mining operations. Overburden stripping and matrix mining are performed by large draglines, the matrix being slurrified and transported to the processing plants hydraulically. Production geologists' responsibilities include, 1) prediction of special mining problems, 2) prediction of ore quality and quantity, and 3) the physical control of the ore quality and recovery during mining. prediction is based on core drilling and visual inspection and analysis of the core samples. Basic economic, and physical minability criteria are thus established. Ore grade and tonnage recovery are of particular importance with emphasis being placed on coordination between mining and processing personnel. Routine inspection of the working pit face is of prime importance and both physical and quality variations are pointed out to the mining supervision. Physical problems in ore control occur due to erratic clay, dolomitic limestone and sand lenses. Near surface ground water is abundant, posing a threat to recovery. Contaminants of the phosphate ore are large quartz grains, pebbles of cemented quartz sand, clay balls, iron oxide laminac and dolomitic limestone particles. Success of the ore control program is predicated on a balance between predicted ore tonnages and grade and actual production. The geologists' primary attention is directed toward this balance.

Jan 1, 1972

By John Keefner, Charles Kocsis, Kyle A. Scalise

Geotechnical modeling of mines is crucial for understanding the many factors that can pose potential hazards or limit production opportunities. The process of back analyses for modeling is often used, but in many instances, the back analyses can be cumbersome and time inefficient.While thesemodels and back analyses may be accurate, these types of back analyses may not be ideal to be used at mines and by engineers because the process is so time-consuming. This paper introduces event-based back analyses that utilize prior events to create more accurate models while eliminating large modeling time because the models are back analyzed from previous events. The completed analyses supply a more detailed insight into the potential hazards at Round Mountain, an open pit operation, as well as provide a better understanding of how improper risk analysis results in missed opportunities. The more we understand about mining activities and processes through modeling, the safer and more productive mines will be.

May 24, 2021

By Adrian Molinari

A radioisotope probe (Minexan 202) capable of simultaneously analyzing a mineral slurry for five elements and pulp density has been developed by Outokumpu Oy, Finland. The probe is designed to operate immersed directly in a process stream, or it can be equipped with a flow cell through which passes a continuous sample of the main stream. A minicomputer (PDPII) is used to control the probes and calculate the assay data. This paper describes the probe as applied to slurry analysis and compares it to the conventional x-ray on-stream analyzer (Courier 300).

Jan 1, 1977

By S. Kmet, A. Nguyen-Van, H. J. Schulze

The P/B collision and attachment interactions in fine particle flotation have been quantitatively analyzed. New models for attachment probability and kinetics of ‘true flotation’ have been developed. The results are given for both a single bubble and a bubble swarm. The mechanism of the attachment event is also examined. It is shown that (i) impact collision mechanism and rolling mechanism can be ignored in actual fine particle flotation and sliding mechanism is of importance for attachment of particle onto the bubble surface (ii) the attachment probability of fine particles is independent of bubble size and determined by the kinetic measure induction time of hydrophobicity. The theoretical predictions are also compared with the experimental data.

Jan 1, 1995

By M. Fig, A. Juganda, M. Zurhorst, J. Brune, C. Strebinger, G. Bogin

"Understanding the airflow patterns in and around the longwall panel can help to identify poorly ventilated areas that may be prone to methane accumulation. Ventilation network modeling provides quick simulation time, and flexibility in adjusting airway parameters and ventilation controls. Such modeling is effective for analyzing linear ventilation networks in underground mines, but cannot compute flows in caved areas of hard rock mines or longwall gobs. The use of Computational Fluid Dynamics (CFD) enables a more detailed investigation of the interaction between the airflows in these caved areas but requires much longer computational times, designing complex meshes and determination of a variety of modeling parameters. Airway friction factors and ventilation controls are simple to implement in a network model but can be difficult to model and adjust in CFD. This paper will focus on using mine ventilation network simulation to identify and analyze key parameters that are affecting airflow distribution in and around the longwall panels, prior to more detailed analysis with CFD modeling, using the example of a longwall coal mine. INTRODUCTION In longwall coal mine ventilation systems common in the U.S., the main purpose of bleeder ventilation is to dilute methane gas and prevent the formation of explosive gas mixtures in the caved, poorly ventilated gob areas and adjacent mine workings. In longwall operation, these critical areas include the development headings inby the longwall face, and the gob. Methane-air explosions in these areas may be ignited by spontaneous combustion, rock-on-rock friction and other sources. Although rare, ignitions due to rock-on-rock friction caused by roof falls caving into the longwall gob are possible and were suspected in the Willow Creek mine explosions in 1998 and 2000 (Elkins et al., 2001; McKinney et al., 2001). Rock-on-rock frictional ignitions are difficult to prevent, as they occur in inaccessible areas. Therefore, rendering the gob area inert is essential to prevent the formation of explosive mixtures. Research by Gilmore et al. (2015) and Brune et al. (2015) has shown that gob inertization can be a difficult or impossible when using bleeder systems, since the flow of gases through the gob depends on the gob permeability and the amount of fresh air leaking from the face and the immediate roof caving conditions cannot be controlled by the mine operator. Having the ability to predict the location where explosive gas zones (EGZs) form inside the gob will be helpful for designing the best ventilation setup to minimize explosion and fire risks."

Jan 1, 2018

By S. Saklar, i. Bayraktar

The effect of the feed size distribution on the kinetic parameters in pyrite flotation was studied. The kinetic parameters of the particular sizes were determined as a function of whether other particle sizes were present. From the data, a relation between the pyrite flotation rate and the particle size distributions was obtained. It was shown that the flotation rate constant (k) is a function of the size modulus (dt) of the Gates-Gaudin-Schuhmann distribution, and its variation may be expressed as k = a • exp(b . d,) for either individual size fractions or composite feed. Parameters a and b are dependent on the particle size distribution of the feed. Specifically, parameter a increases linearly as the distribution becomes coarser. The above relationship was also tested under conditions in which the collector (KAX) dosage was varied from 130 to 278 g/t. It was shown that the established relation was not dependent on the collector dosage.

Jan 1, 2002

By Brian Flintoff

SCOTT COULTER: Our second speaker today is Brian Flintoff. Brian graduated from the University of Alberta in 1973 with a master's of science degree and worked as a project metallurgist at Brenda Mines until 1977. He returned to the University of Alberta in late 1977 to work on his Ph.D. and later joined the faculty of engineering in 1980, leaving in 1988 to rejoin Brenda in the newly formed process technology division. In 1998 he left Svedala-Brenda to take a position with Simons International's newly formed enterprise development services group. His topic today is "People: Reduce, Reuse, and Recycle." INTRODUCTION BRIAN FLINTOFF: Historically, the mining industry has relied on the people within a corporation to get things done. The culture of most companies was one of a slow but sure development of people, processes, equipment, and technology. Many of the larger companies supported in-house engineering and research organizations. However, the metal market pressures of the 1980s and the emergence of the global economy in the late '80s and early '90s put enormous financial pressures on the industry. As the old adage says, "necessity is the mother of invention," and the mining industry, like many others, has undergone a transformation. A cornerstone element of the transformation was the downsizing (or right-sizing) that was calculated to "trim the fat" from the capital and operating budgets. The goal was and is to find the highest sustainable operating profit.' While I'm sure one can find examples of losers (e.g., those who can be classified as suffering from corporate anorexia or institutional Alzheimer's) in such business reengineering efforts, there is little doubt that, on the whole, the transformation has been successful. The reality that now faces mill management is "How to do more with less?" At the risk of oversimplifying, one can look at this on two levels:

Jan 1, 1998

By John B. Spencer

Earlier this year, Simplot Phosphates achieved a safety milestone at its Vernal, UT phosphate operations. In March, the entire operation reached achieved seven years without a lost time accident. And the mine operations at Vernal reached the 1 million hours benchmark without a lost time accident. This million hour achievement has been 19 years in the making. This achievement reflects the mine’s strong attitude towards safety, the company said. Safety is an integral part of its culture and requires diligence and considerable work. Attention to even the smallest of details cannot be allowed to slip. This is a record Simplot Phosphates said it hopes to improve on every day.

Jan 1, 2004

By John E. Feddcck

New York City's $360 million North River Water Pollution Control Project is part of New York State's plan to clean up the Hudson River. The project is to provide a sewage treatment facility capable of accomodating a peak waste water flow of 330 MGD which will in great measure eliminate the 192 MGD of raw sewage that N. Y. C. discharges into its surrounding waters. Eleven miles of intercepting sewer lines must be constructed along the west side of Manhattan Island to service approximately one-half of the island. The first contract award was for a 4134 ft. sewer tunnel with a finished inside dimension of 16' x 16'. This main intercepting sewer will feed a sewage treatment plant located on and adjacent to the Hudson River. The tunnel is parallel to the river and is located under 12th Avenue between 125th Street and 143rd Street. The Penn- Central Railroad tracks are above and just to one side of the tunnel location. The working tunnel diameter is 21 ft. and numerous problems of support, mining method, and ground control have been encountered. (see Dwg. 1)

Jan 1, 1970

By Bill Morgan

This paper discusses the economic zones of application for several different types of earthmoving equipment: dozers, wheel loaders in load-and-carry applications, wheel tractor scrapers, articulated trucks, rigid-frame trucks and wagons. Only the medium to large pieces of equipment were considered. From this chart (Figure 1), you can see the size range, in tons of carrying capacity, of Caterpillar equipment and the specific models analyzed.

Jan 1, 1994

By Stephen Navin, Pablo Ferradas, Carlos Silvestri, Alexander Markov, Jon Kaneshiro

In the high Andes of Peru, two tunnels are being constructed totaling nine kilometers in length at an elevation of over 4,500 meters. The tunnels convey freezing and crystal-clear waters from rainfalls, streams, and lakes for the consumption of Lima. The drill and blast 3-meter wide by 4-meter high tunnels are being driven from both ends through folded and sheared volcanic tuff, andesite, agglomerate,and limestone, where groundwater inflow is high. This paper describes the design geological and groundwater inflow investigations and construction.

Jan 1, 1999

By Alfred G. Hoyl

The author, in exploring a virgin area vertically in two known ore shoots requiring decline shaft sinking, drifting, crosscutting and diamond drilling, chose to use electric, electric hydraulic, and diesel rubber-tired equipment. A rebuilt hoist, and electric hydraulic shaft shovel (mucker), hydraulic sinking drills, single boom electric hydraulic jumbo, electric hydraulic LHD, and electric hydraulic diamond drill were used successfully. Slides of the equipment and its use are shown. The advantages and disadvantages of the equipment are discussed, together with costs and production.

Jan 1, 1984

By Bryan Ulrich

Knight Piésold?s annual roundtable discussion was held at the Red Lion Hotel and Casino in Elko, NV on March 14. This year the title was, ?Roundtable discussion on material co-disposal/ co-placement in the mining industry.? This topic was chosen because of the benefits that the mining industry could realize through the advancement of improved methods of storing tailings and mine waste and from reducing short-and long-term environmental hazards while reducing the footprint of these facilities and making strides toward attaining a walk-away solution. Knight Piésold had a local representative, Bryan Ulrich, as well as representatives from its Denver, CO office, including Tom Kerr, president of Knight Piésold?s U.S. practice, and Jeff Coffin, Ph.D., geotechnical engineer, to help facilitate the discussion. The event played host to about two dozen attendees from several western states. Attendees included personnel from more than 10 mining properties, various corporate offices and academia. The purpose of the roundtable was to exchange ideas and information pertaining to broad topics revolving around the subject of co-disposal/co-placement in the mining industry. Compared with traditional conferences and symposia, the roundtable forum tends to provide a less inhibited format for discussion. In the roundtable format, lively discussions and applicable tangential departures are encouraged. This was the seventh in the series of the Elko Roundtable events. Previous roundtables pertained to: ? Heap leach pad design, construction and operation. ? Design, construction and operation of tailings storage facilities. ? Site-wide water considerations. ? Mine closure and cover design. ? Strides toward sustainability in mining. ? High-density tailings, paste and filtered tailings. Acid rock drainage for engineers and environmental scientists.

Nov 1, 2013

By Kurt M. Larson

Future haulage cost projections led Foster Yeoman Limited into developing a fully mobile crushing and conveying system at its Torr Works quarry in Somerset, England. The purpose-built system has an effective throughput of 2,500 tonnes/hour and features an Orenstein and Koppel (O & K) manufactured walking frame, a Fuller-Traylor type 54 X 74 TC gyratory crusher, and unique mobile conveyor modules designed and manufactured by Foster Yeoman. Used in a single-bench operation in this 6 million-tonne per annum limestone aggregate quarry, the system is fed at the production face by 2 Caterpillar 992C loading shovels. The entire system is moved on a daily basis following production face locations.

Jan 1, 1986