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By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

7. Development of Acoustic Seal Checking System The acoustic approach was shown in Section 4 of this report to be the most promising concept for checking the seals. This section describes the development of this concept into a working hardware system to be used later in the field test program. This development effort included: (1) Theoretical analysis of the acoustic behavior in the mine using acoustic modeling- techniques. (2) Experimental determination of acoustic patterns in mine passages. (3) Refinement of the theoretical model. (4) Verification of final theoretical predictions in the quarter-scale laboratory model of a mine passage and seal. (5) Development of system specifications. (6) Development of the Acoustic Prototype Seal Checking System. 7. 1 Analysis of the Acoustic Seal Checker Concept The acoustic seal checker concept is based on a model which combines corridor acoustics and hole transmission theory. The idealized model for the mine sealing application is shown schematically in Figure 66. A high intensity acoustic- source is located in a corridor at a, position adjacent to the location to be sealed. The acoustic signal transmitted through the seal is monitored by a microphone pick-up placed on the opposite side.

Jan 1, 1973

By T. A. Sullivan

Research undertaken by the Bureau of Mines in 1938 has resulted in the development of titanium from a laboratory curiosity to a commercial metal. Along with processes for producing the metal, it was necessary for the Bureau to develop methods for analyzing the metal, raw materials, and intermediate products. Some of the methods developed have been published.3 4 5/ General Services Administration (GSA) was responsible for purchasing titanium metal under Defense Production Act contracts with commercial producers. GSA designated the Federal Bureau of Mines to analyze this metal and establish its compliance with Government specifications. A substantial quantity of tin was found in some of the samples analyzed, and in July 1957 tin was added to the list of impurity elements to be determined. The specifications limited the amount of tin in titanium sponge to a maximum of 0.10 percent. A program was immediately initiated to investigate methods and techniques for determining tin in the range of 0 to 1.0 percent. A method accurate at the 0.10 percent level was necessary, as this level was the critical range for acceptance or rejection of the metal.

Jan 1, 1960

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 Bluhm S. J, Feio L, Ramsden R

A new mining area at the Vaal Reefs gold mine is to have a shaft. system which will extend to a depth of 4 200 m and will require 130 MW of cooling. A novel feature of the proposed cooling system is a large underground air cooling installation in which an ice slurry is sprayed into the ventilation air. The design of the ice slurry bulk air cooler, in the form of counter.flow cooling towers, is discussed. Comparative thermal tests with cold water and ice slurries (with ice mass fractions up to 22 per cent), were carried out in a 5 m high test tower. The presence of the ice in the water spray increases the resistance to heat flow and reduces the overall thermal characteristics of the air cooler by 8 per cent. Notwithstanding this, the use of ice slurries is indeed beneficial in terms of overall costs. It is concluded that a 25 MW air cooler should use 410 kg/s of ice slurry with a 10 per cent ice mass fraction to cool 550 kg/s of air which is 75 per cent of the total air flow rate.

Jan 1, 1988

Membership at the end of the year 1951 was 19,711 including 2228 Student Associates. The data in the third column include these Student Associates. 1. This includes all the cash dues income received from new and old members of all grades. 2. All cash initiation fees received. 3. Net income received from advertising in the three journals. The figure was $72,273, for MINING ENGINEERING; $39,844 for the JOURNAL OF METALS; and $31,564 for the JOURNAL OF PETROLEUM TECHNOLOGY. Income in 1950 was $54,572, $30,390, and $18,443 from these sources, respectively. 4. Receipts from individual sales, nonmember subscriptions, and multiple subscriptions of members. 5. Includes Transactions volumes and the Petroleum Statistics volume. 6. Sales of all other printed matter except special volumes sponsored by certain Funds. Includes a considerable sale of preprints and reprints of technical papers. 7. Does not include dividends and interest from certain Funds whose income reverts to those Funds. 8. Miscellaneous income not included in any of the above categories. 9. The total income compares with $493,197 -in 1950, an increase of $29000.

Jan 1, 1952

By Robert C. Freas, William H. Lane, David J. Krohn

Maysville, Kentucky, is the location of Dravo Lime company's new 9 070 mt(10,000 tons) per day limestone mine and 2 727 mt (3000 tons) per day calcination plant. This complex has been designed as a unit, and capitalizes on recent technological advances. Geologically the Dravo facility is.located on the eastern flank of the Cincinnati Arch, with the high calcium limestone being found at a depth of approximately 274 m (900 ft). A systems approach has been employed in designing and equipping the mine. This allows for maximum production while maintaining flexibility and versatility. All hydraulic drilling, large LHD equipment, and an extendable mine conveyor system are utilized in a five-part mining cycle. A modular concept modifies the room and pillar system to optimize ventilation. The limestone is calcined in three 5.18 x 61.87 m (17 x 203 ft) KVS rotary kilns with a design capacity of 909 mt (1000 tons) per day of lime per kiln. The kilns are coal fired and equipped with preheaters. Lime storage is provided by three 57 m (186 ft) high concrete silos with a combined capacity of 40 909 mt.

Jan 1, 1976

By D. J. de Clerk

Global trends stipulate the need to optimize existing assets while reducing environmental impacts. This paper illustrates the procedure that was followed to achieve such goals at one of the coal burning flash dryer units at an Anglo American smelter. An in-depth study of the process and related literature led to the development and installation of a revised control philosophy. This system includes modifications to the existing regulatory control structure as well as a hybrid rule-based and model-predictive advanced process control (APC) layer. Since commissioning of the APC, this flash dryer?s average throughput has increased by more than 6%, despite higher feed moistures. Furthermore, even though coal consumption has increased slightly, operating efficiency has improved by close to 5%. This was made possible by improving stability of the drying column outlet temperature by approximately 40%, which in turn enabled selection of a more optimal setpoint. Recent data has shown that APC utilization now exceeds 95%. This is indicative of a successful controller installation with good site acceptance. The same philosophy has therefore since been rolled out to most of the other flash dryers in the group.

Jan 1, 2012

By K. O. Bennington

The thermodynamic properties of pollucite [(Cs0.650Na0.185Rb0.028)(AlSi2) (05.8630H0.137)?0.19H201 were determined by the Bureau of Mines in collaboration with the Argonne National Laboratory. The standard enthalpy of formation determined by hydrofluoric acid calorimetry is ?Hf°298 = -3,098.52 ±3.63 kJ mol-1. The standard enthalpy of formation from the oxides is ?H298 (from oxides) = -209.50 ±2.38 kJ mol-1. Low-temperature heat capacities were determined by adiabatic calorimetry from 5.0 to 306.1 K. The derived standard entropy is S°298 = 207.24 ±0.43 J mol-1k-1. Enthalpy increments above 300 K were measured by copper-block drop calorimetry from 349 to 674 K. Various experimental data were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of measurements. Standard enthalpies of formation and Gibbs energies of formation are given as functions of temperature. The Gibbs energy of formation is ?Gf°298 = -2,919.9 W mol-1

Jan 1, 1983

By F. P. Schwarz, A. J. Erickson, S. M. Weber

The Mount Hope stockwork molybdenum deposit, Eureka County, Nevada, occurs In a small igneous cauldron complex 32 to 38 mybp in age. The deposit is characterized by alteration zones and mineralized shells symmetrically distributed around multiple intrusive. For samples from the 25000 meters of 1981-82 drilling, an appraisal of error in in-house sample preparation and in commercial assaying has been made. After splitting, drill core is crushed and reduced in volume (8: 1 at 10-mesh, 8: 1 at 70-mesh, 6: 1 at 200-mesh) to supply 25 grams of 200-mesh pulp for replicate analyses. A 0.5 g portion of the pulp 1s used for dissolution and atomic absorption analyses. Factors which initially generated unacceptable data variances have been minimized by planning, repeat analyses, introduction of standards, and routine monitoring. Assuming that error between replicate assays defines a Gaussian distribution with its average ideally equal to zero, precision (from preparation including core splitting and analysis of 8400 pairs of molybdenum samples) is on the order of ± 25%. The error distribution is not based. Accuracy is approximately 4% lower than absolute as determined by replicate assays of commercially prepared samples.

Jan 1, 1984

By J. Dufour

Although the recovery of nitric and hydrofluoric acids from stainless steel pickle liquors has been solved by several methods, such as solvent extraction, acid retardation, evaporation or pyrohydrolysis, metals (mainly iron, chromium and nickel) are usually obtained as a waste or by-product that has to be disposed. Alternatively, the treatment requires a high liquor flow to be economical, as is the case for pyrohydrolysis. A new process has been developed for metals recovery, that produces metal oxides with a low fluoride content. This new technique is based on a selective precipitation mechanism, which produces nickel hydroxide with a purity of 90%, separate from a mixture of iron and chromium oxides and hydroxides suitable for recycling. The reaction mechanism is based on the precipitation of fluoride compounds of iron and chromium, K2FeF5 and CrF3. For this purpose, free fluoride must be added as potassium fluoride. Also, solid fluoride compounds are hydrolysed, releasing free fluoride. A part of the fluoride is recycled to the selective precipitation operation and the remainder is fed to the acid recovery stage. Nickel does not react in this operation; it remains in solution giving a high separation yield.

Jan 1, 2006

By Y. Tanaka, H. Miki, Y. Aoki, H. Okamoto, G. P. W. Suyantar, T. Hirajima

Due to environmental limitations and the scarcity of freshwater, flotation using seawater or desalinated seawater as process water becomes more common for mining operations. On the other hand, seawater has been reported to affect the flotation behavior of sulfide minerals. Few reports are available on influence of pyrite depression, recycled seawater and lime consumption on flotation by using seawater. In this study, the flotation tests were performed using ore sample to investigate the effect of pH with seawater and process water used in plant on the flotation behavior in a laboratory-scale flotation cell and a pilot plant-scale. The results of laboratory scale flotation indicated that copper and molybdenum flotation kinetics decreased with increasing pH. Furthermore, the iron (mainly pyrite) recovery decreased with increasing pH. The pilot plant-scale flotation test showed that water with a higher concentration of magnesium and calcium (plant processes water) consumed a higher amount of lime. Because of low lime consumption and high copper and molybdenum recovery and grade, pH 8 is suitable compared with pH 8.5 for flotation. Keywords: seawater, process water, copper-molybdenum rougher flotation, pH, pilot test

Jan 1, 2020

By David Mitchell

THE production of fluorspar is one of the smaller nonmetallic indus-tries in the United States with a capital investment-about $10,000,000. Shipments from United States mines' in 1936 totaled 176,231 short tons valued at $3,111,268, an average price of $17.65 per ton. The United States produces about 40 per cent of the world's fluorspar, of which about 90 per cent comes from the Illinois and Kentucky deposits along the Ohio River.2 Further detailed information on the fluorspar industry in the United States is given by Hatmaker and Davis.28 Fluorspar is marketed according to the following relative quantities and specifications: Consump- Specifications, Per Cent Use Form tion in 1936, Per Cent CaF2 SiO2 Fe2O3 Metallurgical Gravel 79 +85 -5 or lump Ceramic,. Ground 10 +95 -3 -0,1 Acid Ground 11 +98 -1 The concentration of the coarser sizes presents relatively little diffi-culty, good recoveries being obtained with jigs and tables. However, sizes smaller than about 10 mesh cannot be successfully treated by ordinary gravity separation methods and so have been accumulating as

Jan 1, 1938

By J. J. Kollé

A compressed-water hydraulic pulse generator (HPG) for nonexplosive blasting of rock and con¬crete is described Energy is stored in the HPG by compressing water to ultrahigh pressure. A large, fastopening valve discharges the com¬pressed 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, 1997

By Robert Stefanko

Roof bolting in coal mines has progressed very rapidly in the last decade, and today this method of support is in general use. There are many theories concerning the functions of roof bolts, but the importance of beam building is indisputable. Proper tension in the bolts minimizes shearing along bedding planes and creates a thick, competent beam from individually weak layers. Bolting must be accomplished immediately upon exposure of the roof, and bolt tension must be maintained if roof failure is to be prevented. Seams are being mined today with roof bolt support where conventional timbering was not effective1. The widespread use of continuous mining equipment was made possible by roof bolts which permit long supported spans free of obstructions.2 Since adequate anchorage is the key to successful bolting, better methods for determining the efficiency of anchorage are continually being sought. Attempts have been made to measure bolt loads, thus assessing anchorage efficiency by employing sensing devices between the bolt head and roof. 3,4,5 None of the techniques appears to be very accurate, and all have at least one serious deficiency.

Jan 5, 1962

By W. H. Eddy

The Bureau of Mines conducted laboratory batch-and small-scale continuous flotation processing tests on waste granite fines from Georgia, to determine the feasibility of recovering usable feldspar and quartz products by flotation. Two flotation methods were utilized for the removal of biotite and other iron-bearing minerals: One was in an acid-cationic circuit, and the other in an alkaline-anionic-cationic circuit. Feldspar was recovered using an acid-cationic method. To produce commercial-grade feldspar and quartz products it was necessary to employ either two sequential froth flotation circuits or one froth flotation circuit supplemented by wet-magnetic separation techniques to remove iron contaminants. Continuous flotation processing yielded a commercial-grade feldspar concentrate containing, in percent, 3.8 Na20, 5.4 K20, and 1.10 CaO, with recoveries of 77.8, 70.3, and 64.4, respectively. The feldspar tailing was high-quality glass sand containing 98.2 percent SiO2 and 0.024 percent Fe2O3. About 42 percent of the quartz was recovered at glass sand specifications. An effective separation of, potash feldspar from the bulk feldspar concentrate was achieved by batch flotation in a mineral separation cell.

Jan 1, 1974

By E. C. Robertson

Observations of faults in mines, at outcrops, and in the laboratory lead to the conclusion that the displacement d of a fault increases irregularly but monotonically with the thickness t of its associated fault gouge and breccia, not including adjacent undisplaced jointed rock. The general trend of data points has a slope d/t of about 100. (The correlation coefficient of a logarithmic regression line is r = 0.94.) The rather wide scatter of the points can be accounted for by inaccuracies in measurement of d and t, and by variation in the conditions at faulting of confining pressure, rock type, water pressure, and deformation history. Limestone is an exception to the relation. Until the data can be corrected and refined, the relation should be used only qualitatively for estimating displacement of ore bodies in mines. The suggested relation is based on observations of 48 steeply- dipping normal and reverse faults and nine small flat-dipping thrust faults, with displacement less than 5 km (3 miles). It does not apply to large strike-slip and low-angle overthrust faults because their large displacements are poorly determined and their breccia thicknesses are widely variable.

Jan 1, 1984

By L. R. Nelson

Cyprus Pima is a medium-sized open-pit copper mine located 35 km (22 miles) south of Tucson, AZ. The ore body was discovered using geophysical prospecting methods in 1953 and was originally worked as a small underground mine followed by small open-pit operations. As mining equipment grew larger and the economic ore grade dropped, the operation grew in size, through four expansions, to the present 50 500 tpd (56 500 stpd) milling rate. The remaining stripping ratio is about 2.5 to 1. Mining equipment includes 11 electric shovels ranging in size from 6 to 15 m3 (8 to 20 cu yd) and 42 diesel-electric haulage trucks ranging in size from 89 to 223 t (100 to 250 st). Mine planning is performed at Cyprus Pima to serve several functions. The most important is to plan ahead, one year at a time, to predict the ore grade and stripping requirements on a month-by-month schedule. This yearly plan is necessary for budget preparation and is revised once each quarter to incorporate variations in actual production experienced during the preceding quarter.

Jan 1, 1979

By John A. Folinsbee

Placer Dome Canada owns and operates the Campbell mine and mill at Balmertown, in the north western corner of Ontario. The mine operates at 1.3 kt/d (1,500 stpd). It produced more than 9.3 t/a (300,000 oz/year) of gold during the last three years. Changes to the gravity concentration circuit have resulted in a 10% to 15% increase in gravity recovery. The mill head grade at the Campbell Mill is relatively high, averaging 18.5 g/t (0.54 oz/st) over the total reserve tonnage. During the past several years, the head grade was averaging close to 20 g/t (0.6 oz/st). Before 1994, gravity concentration was achieved by using a combination of conventional mineral jigs and tables. Jig concentrates were upgraded on shaking tables to produce a concentrate, which was refined to bullion. In May 1994, management decided to buy two Knelson CD 760-mm (30-in.) concentrators. The objective was to replace the existing jigs and increase gravity gold recovery by up to 15%. Gravity recovery with jigs averaged between 30% to 35%. Gravity recovery was anticipated to increase to about 50% with the Knelsons.

Jan 1, 1997

By John M. Logan, John Handin

Quasi-dynamic triaxial compression tests have been done for the first time at confining pressures to 7 kb. The intermediate strain-rate apparatus employs a gas loading cylinder which allows axial strain rates up to 102/sec on a sample 2 cm in diameter and 4 cm long. Samples can be deformed at confining pressures to 7 kb. Strain gages bonded to the loading piston and to the jacketed specimen allow internal measurements of load and sample strains respectively. Westerly granite has been deformed at confining pressures to 7 kb, room temperature, and axial strain rates of 10-2 to 1/sec. An increase of ultimate strength with confining pressure was found as expected. The ultimate strength was also found to vary directly with increasing strain rate; the rate of rise increases with confining pressure. Brittle deformation has dominated the sample behavior. Solenhofen limestone has been deformed at confining pressures to 3 kb, room temperature, and axial strain rates of 10- to 10/sec. The brittle-ductile transition was found to take place at about 1.5 kb confining pressure at a strain rate of 10/sec.

Jan 1, 1971

By N. Wagner, P. den Hoed, J. D. Steenkamp, S. Soqinase

In pyrometallurgical processes, metal oxides are reduced from molten slag through carbothermic reduction. It is of interest to evaluate the reactivity of the carbonaceous materials towards substances such as slag. Characterization techniques such as coal petrography can provide insight into the influence of feed coal properties and how they potentially dictate reductant performance. This study aimed to compare the petrographically determined organic composition of coal to reductant reactivity. Two South African medium-rank C bituminous coals and one anthracite sample were investigated together with high-carbon ferromanganese industrial slag. The reductant reactivity tests were conducted at 1500°C in a muffle furnace to assess the potential of carbonaceous reductant in reacting with the main slag components. SEM-EDS was applied to understand the extent of MnO (and to a lesser extent, SiO2) reduction from the slag. Coal 2, consisting of a greater proportion of vitrinite (59.5 vol% on a mineral matter-free basis and 54.7 vol% including mineral matter) was the most reactive reductant. The anthracite sample, with the highest inert maceral proportions (71.8 vol% including mineral matter and 76.8 vol% on a mineral matter-free basis), was the least reactive reductant.

Feb 6, 2023