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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

Introduction The frigid regions of Canada's high arctic islands are well-known for major oil and gas explorations. But mining leads the way in development. Cominco Ltd.'s Polaris mine is in its second full year of commercial production, and outstripping the rated production capacity foreseen by its planners. The Polaris mine is located on the shore of Little Cornwallis Island, near the settlement of Resolute Bay. The mine property is compact. It occupies about 3 km2 (0.5 sq miles) of the vast Arctic landscape. A number of mining and technological firsts were necessary to bring a mine into production at this 76° North latitude. Development constraints that had to be overcome included climate, remote location, and the limited ice-free shipping season. Construction of the entire process plant and ancillary facilities took place on a barge in the South where labor and supplies are plentiful. The plant was towed through ice-strewn waters to its permanent location at the mine site 1450 km (900 miles) from the North Pole. Freighters moved the first shipments to the South during ice break-up in late summer 1982. Most of the zinc concentrate is sold to European smelters. The remainder is tolled at a custom smelter in Europe, and the resulting metal is sold by Cominco. Lead concentrate is sold to European smelters. The mine was designed to produce 177 kt/a (195,000 stpy) of zinc concentrate and 41 kt/a (45,000 stpy) of lead concentrate. Actual production in 1983 was considerably greater, with both mill throughput and feed grades being higher than forecast. Production was 217 kt (239,300 st) of zinc concentrate and 51 kt (56,300 st) of lead concentrate. Average milling rate was 2.3 kt/d (2500 stpd), well above the designed capacity of 2.1 kt/d of (2300 stpd). Arctic Climate Extremes The climate is typical of the Arctic: very dry with short, cool summers and long, cold winters. From November through February, there is continuous darkness. Continuous daylight prevails from April to August. Precipitation is light, rivaling the Sahara desert at about 127 mm (5 in.) of rain and snow a year. An almost continual wind forms deep snow drifts against any obstacle on the ground. Temperatures range from a winter low of about -50°C (-58°F) to a relatively pleasant 15°C (59°F) during sunny days in August. Freeze-up begins in September and ice thickness increases from less than 0.3 m (1 ft) in early October to a maximum of about 2.1 m (7 ft) in May. The permanently frozen ground extends to a depth of about 427 m (1400 ft). Only a few inches of surface ground thaws in the summer. Exploration Activity Zinc-lead mineralization was

Jan 10, 1984

By William G. Pariseau

The purpose of this paper is to present a design procedure for the quantitative estimation of support load requirements in underground mines. Emphasis is upon the basic features of support behavior common to a large variety of support systems-bolts, timber sets, stope fill, steel arches, concrete liners and so forth. A strong reliance is placed upon fundamental principles and modern computing techniques for their quantitative implementation. Example problems illustrate the approach. Where artificial support is required, the ground in the vicinity of the face usually stands unsupported long enough for the support to be installed. At the time of installation, the load transferred to the support from the adjacent rock is essentially zero, although in some cases there may be an initial set load, for example, from timber blocking. With the passage of time and advance of the face, ground motion loads the supports. If the support system is properly designed, then the additional loading poses no threat to the safety and productivity of operations. If not, then difficulties may arise including high maintenance costs, hazardous work conditions and reduced productivity. Of course, over-design can be equally wasteful. Quantitative estimation of support loads is therefore essential to overall efficiency in mining.

Jan 1, 1975

By Y. C. Kim

An alternate development drilling strategy to the one currently in use at the nine was investigated using geostatistics for a portion of the pit. The study area consisted of 4,000' x 5,000' in plan and 1,080' in elevation. The massive orebody, the three-dimensional nature of the problem, and the location of ultimate pit limit in the study area all created some unique problems in devising the development drilling strategy, as compared to the two-dimensional tabular deposits such as coal deposits. Rather than using the confidence interval of the global reserve estimate as the main criterion for development drilling, the confidence interval of short and medium range mine planning blocks was used as the objective. Based on somewhat arbitrarily selected level of confidence, the results from this study showed that a total of 50 DDHs rather than the planned 62 DDHs is sufficient in the study area, if the selected confidence levels are acceptable to the management. This paper also emphasizes the importance of the particular objectives being used in development drilling and how they influence the "optimai" place- ment of the development drill holes.

Jan 1, 1981

By B. Seymour

The National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop safe practices for the use of shotcrete as ground support in underground mines, particularly mines operating in weak host rock. As part of this research, tests were conducted with a commercial poly-fiber reinforced shotcrete mix to develop a practical means of measuring shotcrete adhesion strength. Full-scale tests were conducted in a test frame equipped with concrete panels having three distinct surface roughness profiles. Adhesion test fixtures either embedded or epoxied in the shotcrete were overcored into the underlying concrete, and direct tensile tests were conducted to determine the bond strength of the shotcrete cores to the substrate after a selected shotcrete curing interval (1, 3, 7, 14, 28, or 90 days). Measured adhesion strengths typically ranged from 0.5 to 2.0 MPa depending on the curing age of the shotcrete samples. This paper presents the results of these tests, describes the portable test system components, and addresses some of the design issues encountered in the development of a rugged and reliable method for determining shotcrete adhesion strength in underground mines.

Jan 1, 2010

By Peter Zhang, Daniel Su, Bo Kim, Zoheir Khademian

Building on the research results and knowledge obtained from the ongoing National Institute for Occupational Safety and Health (NIOSH) Gas Well Stability Research, researchers from the NIOSH provided detailed analyses on potential longwall mining and gas well casing interactions at an unconventional shale gas well pad in a West Virginia longwall mine. Following the recommendations from recent research findings, the 5-1/2-inch production casings in all five wells were left uncemented from 4,200 feet below the surface to the surface. Prior to the first longwall panel excavation, NIOSH researchers conducted sophisticated three-dimensional numerical modeling to predict longwall-induced deformations and gas well casing stresses, which were compared with post-first panel and post-second panel mining 40-arm caliper surveys. The pre-mining predictions and comparisons with post-mining 40-arm caliper surveys were presented to all parties involved, including the coal and gas operators, Mine Safety and Health Administration (MSHA), Pennsylvania Department of Environmental Protection (PADEP), and West Virginia Department of Mines (WVDOM), prior to the re-entry operation on December 13, 2022. To date, the re-entry operation is a resounding success.

Jul 1, 2023

By Stephen H. E. Phillips

Geological and hydrological conditions in the strata overlying the Salado Formation vary considerably in the Carlsbad, New Mexico area. The first four shafts sunk at international Minerals and Chemical Corporation's property have been located in competent and essentially dry conditions, while other shafts on adjacent properties have had such adverse conditions that ground freezing has been chosen as the water and ground control technique for shaft sinking. At the location of the IMC No. 5 Shaft there has been extensive-erosion and salt dissolution in the Rustler Formation which has led to collapse of some zones of the strata. Both ground freezing and pregrouting were considered as alternative methods of stabilizing the extremely poor ground conditions and controlling the potentially very heavy water inflows it was decided that pregrouting the shaft was feasible and would offer substantial cost and time saving over a ground freezing technique. This paper describes the pregrouting techniques used and illustrates the requirement for flexibility in a grouting program so that it can be codified to reflect any new or additional information which is obtained during the progress of the grouting.

Jan 1, 1984

By R. Hogg

Sedimentation in highly flocculated suspensions of fine particles such as clays occurs through individual settling units (flocs) which have very open structures and correspondingly low density -typically less than 5% solids by volume. It follows that such settling processes rapidly lead to the build-up of a bed of flocs which are essentially close-packed, with inter-floc porosity of perhaps 50%, but with an overall solids content of no more than about 2-3 percent by volume. An important consequence is that the thickening process is dominated by the consolidation of this bed rather than by simple settling of the individual flocs. Experimental measurements of sediment consolidation in flocculated clay suspensions indicate that for a given system, consolidation rates are essentially determined by solids concentration and can be evaluated using the classical Kynch treatment. However, these rates are strongly dependent on the physical as well as chemical conditions of the flocculation process. Furthermore the extent to which gravity consolidation proceeds depends on the total weight of sediment (i.e. on both height and solids concentration). The implications with respect to thickener operation and the requirements for laboratory testing for thickener design are discussed.

Jan 1, 1992

By A. D. Davis

The disposal of spent ore from cyanide heap-leach processing facilities is of concern to the mining industry, regulatory agencies, and the public. Disposal of several hundred million tons of additional spent ore is planned in the western United States during the next decade, with increased amounts likely if gold prices rise. In the past decade, more than fifteen million tons of spent ore have been disposed of in the Black Hills. South Dakota's off-loading criterion for cyanide has been set by the state's Department of Environment and Natural Resources at 0.5 parts per million (ppm) as weak acid dissociable (WAD) cyanide. Nitrate off-loading limits vary for each mine in the state, depending on ore type and other factors. Nitrate concentrations in leachate from spent ore depositories could be caused by conversion from other nitrogen-containing species. One likely source of nitrate is residual explosives from blasting of ore. Previous work on the combustion products of nitrogen explosives has shown incomplete 3xidation (Johansson and Persson, 1970). Another likely nitrate source is degradation of cyanide to ammonia, followed by oxidation to nitrite and nitrate.

Jan 1, 1994

By C. H. Cox

The Alumet Company of Golden, Colorado, is currently engaged in the development of their Diamond Creek and Lanes Creek phosphate ore bodies located near Soda Springs, Idaho. The Alumet Company is a partnership of National Steel, Southwire Co., and Earth Science Inc. Davy Powergas, Inc., of Florida was contracted by Alumet to perform an evaluation study of these properties and, in general, determine the tonnage of altered and unaltered phosphate reserves which would be amenable to beneficiation and production of merchantable phosphate rock (defined as material with a P2O5 content of 3 1.0% and greater). The Colorado School of Mines Research Institute was retained by Davy Powergas to develop a beneficiation method for the studies of the altered and unaltered ores. Ore reserves were classified by Davy in a comprehensive range of categories such that any partial grouping could be made as dictated by future mine planning, mine or mill design, or prevalent economic conditions. Categories included ore horizon, stripping ratio, degree of certainty of their existence, and physical and chemical characteristics. The last category was of interest for beneficiation considerations in that it dealt with the degree of alteration of the phosphate ore.

Jan 1, 1979

By B. W. Madsen

Experimental results obtained from large scale (7 tons), long-term (500 days) leaching of low tenor copper sulfide ores were interpreted by a geometric model involving the movement of a reaction zone through the ore fragments. The postulated leaching mechanism involved mixed kinetics and included diffusion of the reacting species through the host rock and a chemical reaction at the surface of the mineral particles. Ore properties which were considered were ore particle size and shape, grade of ore, and mineral content. Excellent agreement between the mixed kinetic model and the laboratory leaching results was obtained when minus ½ inch ore particles were not included in the leach. Also, a satisfactory prediction of copper recovery from plus ½ inch ore with a different particle size distribution was made; however, it was necessary to modify the shape factor in the model. Predictions of copper recovery from an ore sample which included the minus ½ -inch fine fraction and leaching for 460 days was 56.5 percent, and the recovery from leaching was 47.0 percent. The presence of fines caused channeling and uneven solution distribution and inhibited the leaching rate.

Jan 1, 1974

By H. Lind

Mining in Estonian oil shale deposit mainly takes place in the Ordovician, Keila-Kukruse aquifer. The aquifer is affected by mining and is fully dried out around the working mine areas (Perens and Savitski, 2008). The groundwater level is decreased down to 30 m, to the mine floor elevation using about 30 pumping stations (Lind, 2005). The pumping rate is very high - depending on the season, ranging from 10 up to 40 m3 per ton of produced oil shale (Reinsalu et al., 2006). The Estonian oil Shale Company mined 15.5 million tons of oil shale in 2007 (Source: Estonian Oil Shale Company). In order to predict the effects, and avoid the social and environmental impacts, there is a need to continuously monitor the situation and run software simulations aiming at decreasing the pumping rate. This becomes even more important since the environmental taxes on usage of groundwater resources increase every year. Therefore, it is necessary to monitor groundwater level and quality, and develop a groundwater model for the overview of the situation during mine operations and also for a number of years after mine closure.

Jan 1, 2008

By Solomon S. Katz

As more and more computer software is written for geological mapping applications, the users of the software are discovering the problems of transferring data between the programs, maintaining correct data and integrating maps produced last week with those produced today. One way to deal with these situations is by using a geographic information system (GIs). Last September the USGS and National Academy of Science held a 5-day GIs symposium on integrating technology and geoscience applications (USGS, 1988). It was followed in October by GEOTECH '88 (Peters and Krajewski 1989) which had a session exclusively for GIs applications in the Geo-Sciences. Editorials in Geobyte (Leonard, 1986, 1988) suggested that geographic information systems will be the next major computer programs to be adopted by the mineral industries. As far- back is 1985, the Computer Oriented Geological Society (COGS) printed An Introduction to GIs in their newsletter (Katz, 1985). About 20 years ago, a revolutionary idea occurred in the world of business data processing. It was the idea that all related data be stored in a standard format, in a single place and that all related computer application programs would use the same data.

Jan 1, 1989

By M. J. Hughes

Kaiser Steel Corporation's Eagle Mountain operations are located in Southern California at a distance of about 130 miles east of the Corporation's steel plant at Fontana, California, and at a distance of about 225 miles from the nearest harbors which are located at Long Beach and Los Angeles, California Although the Eagle Mountain ore bodies are strategically located with respect to the steel plant and the harbor facilities, they are not of a very high grade and 'the geologic nature of the deposit makes it very difficult to mine and to concentrate. The iron ores occur as partial replacement of older zones mainly within dolomites and to a lesser extent within quartzites and quartz monzonites. The alteration was extremely variable and generally resulted in the formation of pyritic magnetic which, in part of the ore body, was leached to remove the pyrite and change the magnetite to hematite. Although the overall ore body is large, a major portion of it contains sulfur in the range of 1.0% to 5.0%. Obviously, this is too high a sulfur content for direct use in blast furnace feed.

Jan 1, 1968

By L. Adler

A fairly complex analysis is required to select, or evaluate a piece of excavating and bulk handling equipment and obtain its performance. At present there is little agreement as to what specific points should be considered, and even less on what procedure to follow. This paper provides both of these in a consistent and direct form. The analysis applies to all types and sizes of equipment from the bulldozer and the continuous miner, to the B.W.E. The importance of the equipment characteristics, job activities, and work conditions are stressed and separate analytical stems are established in a flow chart for these. They are combined using suitability tests in the following steps: 1) problem statement, 2) natural conditions, 3) suitability guidelines, 4) appropriate equipment types, 5) operational activities, 6) encumbered space, 7) geometric design, 8) equipment sizing, 9) failure and limits, 10) performance and consumption, 11) public policy checks, and 12) costs and profitability. Public policy and economics while considered throughout receive emphasis towards the end. The procedure is iterative, containing distinct feedback loops. Specifying the steps and sequence provides a necessary structure which has long been overdue.

Jan 1, 1983

By Steven A. Elmquist

Although past investigations (2, 5)have been conducted to determine crushing relationships, no program which covered a broad range of crushing conditions had been conducted. The previous studies appear to concentrate on small segments of the overall picture and did not fullfill our desired information objectives. The Crusher Variables Research Program conducted at the Mineral Research and Test Center (MRTC) of Rexnord, due to the broad range of variables utilized in a production size crusher, is believed to be the most comprehensive study of its kind as of this date. The principles developed by the Symons brothers in 1925, when they patented the cone crusher as we know it today, are still being used in the machine known as the Symons Cone Crusher, During the development of this novel crushing concept, a technique known as the fall of material (called the Bouncing Ball Theory1 by some) was used to determine an idea as to the proper head angle, eccentric and speed of eccentric rotation, The final variables used for the Symons Cone Crusher design were, therefore, the logical conditions to start with and use as a reference against which other variables could be compared.

Jan 1, 1979

By W. Dan Hausel

In previous reports by Hausel et. al., (1979 a, b, and c), Leighton and McCallum (1979), and McCallum (1974;1979), several exploration procedures were examined as to their effectiveness in locating kimberlite intrusives in northern Colorado and southeastern Wyoming, where approximately 90 kimberlites have been recognized within 5 districts (Figure I). Briefly, geological mapping and stream sediment sampling for indic- ative heavy minerals of kimberlite (pyrope garnet, chrome diopside, and magnesian ilmenite) proved to be the two most effective methods in isolating kimberlite occurrences within the granitic terrain of Colorado and Wyoming (Hausel et. al., 1979 a, b, and c; Leighton and McCallum, 1979). Where a kimberlite intrusive is deeply weathered, remote sensing using color and color infrared aerial photography may be a potential reconnaissance tool in kimberlite exploration. The kimberlitic eluvium supports thicker grassy vegetation, and at least one species of grass (the Bluebunch Wheatgrass) is found to grow only within the eluvium. The result is that vegetation in the kimberlitic eluvium is a better infrared reflector than the vegetation in the surrounding granitic soils (Hausel et. al., 1979 b; McCallum, 1974

Jan 1, 1980

By J. J. Kollé

A compressed-water hydraulic pulse generator (HPG) for nonexplosive blasting of rock and concrete is described. Energy is stored in the HPG by compressing water to ultrahigh pressure. A large, fast-opening valve discharges the compressed water, resulting in a high-energy impulse. The HPG can be used for small-scale bench blasting by discharging the water through a nozzle that is closely fitted into a borehole. A bench blasting system requires an HPG, a drill and an indexing mechanism to allow insertion of the HPG nozzle into a drilled borehole. Systems with discharge energies ranging from 40 to 250 kJ have been used to excavate hard rock, including andesite, granite and quartzite. The largest system can excavate 15 t/h (16.5 stph) of massive quartzite based on a 2-min cycle time for hole drilling. Blasting with an ultrahigh -pressure hydraulic pulse generator was demonstrated as an effective means of excavating hard, massive rock under the confined conditions of a tunnel opening or underground sloping panel. Hydraulic blasting provides a continuous mechanized mining capability that is well suited for deep-level mining and urban excavation sites where explosives are prohibited.

Jan 1, 1998

By R. K. Amankwah, E. K. Asiam

Changes in the thermal-oxidation behavior and other properties of gold-bearing waste activated carbon when milled in both a ball mill and a vibratory mill were investigated. It was found that significant changes occurred in the oxidation temperature of the vibration-milled waste carbon as a result of increases in surface area and mechano-chemical activation. The mechano-chemical action brought about modifications in the crystal structure of the waste carbon. As a result, the vibration-milled sample was completely oxidized at a temperature of 450°C. Thus, the study established that vibration milling is a better way of lowering the temperature of oxidation of the waste carbon. Furthermore, the gold was found to be concentrated in the ash and, when leached with cyanide for 20 hrs, the gold recoveries from a sample having a head grade of 2 kg/t was 99.5% for the vibration-milled sample and 82% for the ball-milled sample. The lower gold recovery for the ball-milled sample was attributed to sintering of the ash, which was caused by the higher temperature required for its oxidation.

Jan 1, 1997

By A. L. Muler

Since 1956, when Broadbent and Callcott 1 proposed to analyze breakage processes by matrix methods, several authors and their co-workers have proposed various models of grinding that, in principle, could lead to fully automated grinding circuits. In particular, Meloy and Gaudin2, Gardner and Austin3, Kelsall and Reid4, Neloy and Bergstrom5, Callcott and Lynch 6, and Draper and Lynch have, by either computer simulation or by experimental data, or by a combination of the two, verified that comminution is reasonably well described by at least two functions: a selection function and a breakage function. The stage concept proposed by Callcott and Lynch6 requires that a classification matrix be included to completely describe breakage in an open circuit rod mill. The purpose of this work, portions of which are herein described, is to accumulate sufficient information on the breakage characteristics of quartz and magnetite in an open circuit rod mill, so that several of the theoretical and experimental approaches proposed in the literature can be compared with each other. Data is being gathered to compare the experimental method used by Kelsall and paid against the stage approach of Callcott and Lynch.

Jan 1, 1968