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By P. van Zyl, M. Lombaard

The 14MW SAG mill at Tarkwa, Ghana, experienced a frozen drop charge incident on 10 February 2010. This caused downtime of 112 hours, a repair cost of $200k and production loss of 162,000 tons, corresponding to a loss of $8.9M. A new locked charge protection system was installed on the two Tarkwa mills on 30 July 2010, mitigating this risk. This system calculates the ore angle in real time while the mill is starting up and trips the mill if the ore angle exceeds a trip angle setting. The calculation of the ore angle is derived from the mill motor rotor currents only - no mechanical transducers are required. The head of Gold Fields West Africa, Peter Turner, says of the new system: "This is excellent work and the type of technology that has had and will continue to have, major opportunity cost impacts on our business."

Jan 1, 2012

By Ann G. Kim

The Bureau of Mines estimated the methane content of a coal, which depends primarily upon rank and pressure, from the adsorption equation V =kpn, where k and n are constants related to rank. By incorporating corrections for moisture, ash, and temperature, and estimating pressure and temperature as a function of depth, the methane content of coal in place can be estimated from the following equation: [ ] Values calculated with this equation generally are in reasonable agreement with direct determinations. By assuming a standard moisture and ash content, and using the hydrostatic head to estimate pressure, a graph of rank and depth versus gas content was constructed. Although estimated values were consistently high for several high-volatile bituminous coals from an area where the pressure is known to be less than hydrostatic, the estimated methane content for most coals shows reasonable agreement with values determined by the direct method.

Jan 1, 1977

By Hale C. T, Carnie W. A

Rosebery mine has had over 100 years of mining activity. The reserve has remained static for the last eight years with an expected mine life of six years. A move to rectify this was made in 1994 with the birth of the Deep Exploration Project (DEP). $45 M was committed to drill 100 km of underground exploration diamond drilling and develop 5.5 kin of decline aiming to add 9.5 Mt to the reserves and minimise lead time for development of P and K lenses discovered in the early-1990s. In 1996 this aim was expanded with the objective to build the resource base to 20 Mt by June 2000 allowing the mill to operate at 1.0 Mtpa (0.9 Mt from underground). Preliminary results of the project to-date are outlined and exploration diamond drilling techniques and strategies are described.

Jan 1, 1997

By D Tucker, K Harney

Hatch forecasts that an increasing share of seaborne traded iron ore will be ultrafine, being either concentrate or pellet feed. This provides several challenges for the iron and steel industries, but the principal concern is: how much ultrafine iron ore can be consumed on sinter strands and with a minimal effect on productivity?This paper will identify new supply by project through 2020. Demand will be estimated for sinter production and practical steps will be identified to increase ultrafine consumption in sinter strands. The long-term iron ore price will be forecast to balance supply and demand. The paper will conclude by assessing how the pricing of ultrafine ore will develop relative to the Chinese iron ore indices.CITATION:Tucker, D and Harney, K, 2015. Iron ore ultrafines challenges and opportunities, in Proceedings Iron Ore 2015, pp 501–504 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Chao Li, Shi Sun, Hongxu Li, Jiaqi Fan, Qi Liu

With the great demand of consumer electronics (CE) and electric vehicles (EV), cobalt has become one of the more scarce energy metals.The recovery of cobalt from a copper converter slag, which contained over 2.4% Co and was accumulated as industrial waste, by reduction-sulfurization smelting was explored. Quantitative analysis of treated slag showed that activated carbon and ferrous sulfide can be used to settle cobalt into matte as Co–Fe alloy. The experiment was carried out at 1673 K with a reducing atmosphere of burning electrode graphite crucible. It was found that the recovery of Co would increase within creased added activated carbon, was unaffected at higher carbon additions, and for low additions of carbon increased at higher FeS additions. Over 95% Co, 99% Cu and 62% Fe could be settled into matte. Preliminary separation of Co from converter slag by pyrometallurgical smelting is proposed.

Mar 1, 2017

By William E. Ford, Edward Salisbury Dana

The monoclinic Wolframite Group and the tetragonal Scheelite Group are included here. Wolframite Group WoIframite (Fe,Mn)W04 a : b : c = 0.8300 : 1 : 0.8678 B = 89' 22' Hiibnerite MnW04 048362 : 1 : 0.8668 89' 73' WOLFRAMITE. Monoclinic. Axes a : b : c = 0.8300 : 1 : 0.8678; B = 89' 22'. mm"', 110 A 1TO = 79" 23'. ay', 100 A 101 = 62' 54' at, 100 A 102 = 61" 54'. $', 011 A 011 = 81" 54'. Twins: (1) tw. axis c with a (100) as comp.-face; (2) tw. pl. k (023), Fig. 449, p. 171. Crystals commonly tabular (1 a (100); also prismatic. Faces in prismatic zone vertically striated. Often bladed, lamellar, coarse divergent columnar, granular. Cleavage: b (010) very perfect; also parting (1 a (100), and 11 t (102). Fract,ure uneven. Brittle. H. = 5-5.5. G. = 7.2-7.5. Luster submetallic. Color dark

Jan 1, 1922

By T. Cuscino, D. D. Lane, C. Cowherd, T. E. Baxter

Three types of commercially-available dust suppressants, commonly used in the surface mining industry to control fugitive particulate emissions from unpaved roads, were tested in the laboratory for cohesive strength and resistance to reduced effectiveness by large water addi¬tions. Results indicate that each product tested varies in cohesive strength with a range of 34-300 kPa (5-44 psi). Total cohesive strength depends on the aggregate moisture content and the means by which the sample is dried. Results show that laboratory testing can be used as a decision¬making tool concerning the type of dust suppressant for a particular mining operation. Also, the road surface aggre¬gate moisture content u critical to successful dust suppres¬sant performance. Large water additions to the aggregate road surface after initial suppressant application can pro¬duce nondesirable results. A modified wet sieving analysis is presented to test the effect of water addition.

Jan 1, 1984

New York Meets first Wednesday after first Tuesday of each month. J. E. JOHNSON, JR., Chairman. EDGAR RICHARD, Vice-Chairman. D. M. LIDDELL, Secretary, 7 Wall St., New York, N. Y. C. A. BOHN, Treasurer. JOHN V. N. DORR, LEWIS W. FRANCIS. Boston Meets first Monday of each winter month. R. L. AGASSIZ, Chairman. JAMES G. CARLETON, Vice-Chairman. E. E. BUGBEE, Secretary-Treasurer, Mass. Inst. of Technology, Cambridge, Mass., W. E. C. EUSTIS. G. A. PACKARD. Columbia Holds four sessions during year. Annual meeting n September or October. W. H. LINNEY, Chairman. OSCAR LACHMUND, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. STANLY A. EASTON, S. SHEDD. Puget Sound Meets second Saturday of each month SIMON H. ASH, Chairman. I. F. LAUCKS, Vice-Chairman. CHARLES SIMENSTAD, Secretary-Treasurer, 425 Lyon Bldg., Seattle, Wash. GLENVILLE A. COLLINS, JOHN N. POTT

Jan 7, 1917

New York Meets first Wednesday after first Tuesday of each month. J. E. JOHNSON, JR., Chairman EDGAR RICHARD, Vice-Chairman D. M. LIDDELL, Secretary, 7 Wall St., New York, N. Y. C. A. BOHN, Treasurer JOHN V. N. DORR LEWIS W. FRANCIS Boston Meets first Monday of each winter month. R. L. AGASSIZ, Chairman JAMES G. CARLETON, Vice-Chairman E. E. BUGBEE Secretary-Treasurer, Mass. Inst. of. Technology, Cambridge, Mass. W. E. C. EUSTIS G. A. PACKARD Columbia Holds four sessions during year. Annual meeting in September or October. W. H. LINNEY, Chairman OSCAR LACHMUND, Vice-Chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. STANLY A. EASTON S. SHEDD Puget Sound Meets second Saturday of each month SIMON H. ASH, Chairman I. F. LAUCKS, Vice-Chairman PERCY E. WRIGHT, Secretary-Treasurer, 2012 L. C. Smith Bldg., Seattle. Wash. GLENVILLE A. COLLINS JOHN N. POTT

Jan 11, 1917

By Cleusa Cristina Bueno Martha de Souza

Hydrometallurgical techniques for processing metals are becoming an efficient method for recovering metals. Although batteries' manufacturers have got rid of mercury content, some efforts have been made for recovering other metals enclosed in the battery formula. This paper discusses the bench scale experiments in the purification process of leached solutions from alkaline spent batteries. After leaching process using sulfuric acid as leachant, the solutions containing Fe, Cd, Pb, MIl, Zn and K were neutralized to precipitate iron hydroxide. In a second step, the purification experiments were carried out with excess of zinc dust to try to remove Cd while Mn and Zn still remain in the solution to be recovered in an electrolysis stage. The purification experiments procedures were conducted at different temperatures and times to find out properly conditions from the viewpoint of metals removal After filtration the solutions were submitted to chemical analysis to certify the metals content extracted.

Jan 1, 2001

By R. L. Murray-Smith, M. E. A. Robertson, M. J. Prosser

The AZTEC is an automated instrument, for the non-destructive analysis of gold ore samples, which uses energy dispersive X-ray fluorescence (XRF), This is achieved by X­ray tube excitation of gold K X-rays. The first production instrument was commissioned at Vaal Reefs Chemical Laboratory (VRCL) in November 1987, followed by two second generation instruments in 1989. AZTECs have also been installed at Western Deep Levels and at Anglo American Research Laboratories (AARL). A further unit is being assembled at Ashanti mine, Ghana. At VRCL the AZTECs are used primarily for the evaluation of mine (stope) samples. Each of the production instruments can routinely analyse 650-700 samples per day, with the aid of a robotic sample transfer system. Various techniques have been evaluated for increasing sample throughput. For example, higher value samples can be counted for a shorter time to obtain the necessary relative precision.

Jan 1, 1991

[Appalachian Petroleum Section: James M. Kimbrough, chairman; John H. Adair, first vice-chairman; Walter L. Diddle, second vice-chairman; Byron M. Finch, secretary-treasurer. Balcones Section: Robert V. West, chairman; Frank W. Jessen, first vice-chairman; Zane V. Morgan, second vice-chairman; Brantley G. Myers, secretary-treasurer. Meets 4th Wed., Petroleum Club (San Antonio) or Terrace Dining Room (Austin) Billings Petroleum Section: Charles B. Evans, chairman; L. M. Lyon, first vice-chairman; Gordon E. Lansford, second vice-chairman; Fred. A. Haddenhorst, secretary-treasurer. Meets 3rd Tues., Billings Petroleum Club. California Coastal Section: Robert L. Richardson, chairman; David K. Hayward, first vice-chairman; W. Jackson Bransford, secretary; William N. Harwell, treasurer. Meets 3rd Thurs., Pierport Inn, Ventura. Caracas Petroleum Section: Edwin A. Moo re, chairman;. Jose Cirigliano, vice-chairman; Frank B. Davis, secretary; Robert N. Powers, treasurer. Meets 2nd Tues., Caracas Theater Club.]

Jan 1, 1961

By K. N. Han

The leaching behavior of palladium in ammoniacal solutions was investigated by using the rotating-disk technique in an autoclave. The study included the effects of rotation speed, temperature, oxygen pressure, composition of ammoniacal solutions and catalysts on the overall leaching rate. The dissolution of palladium in ammoniacal solutions was discussed in terms of the thermodynamics and a kinetic model. Even though the Eh-pH diagram suggests that palladium metal can dissolve in ammoniacal solutions at room temperature, it was found that the dissolution was very slow at temperatures below 100 °C but was significantly improved at higher temperatures. It was also found that the rotating speed of the palladium disk had no effect on the leaching rate. The apparent activation energy was found to he 69.7 kJ/mole. Based on the results obtained, it was concluded that the dissolution of palladium is controlled by chemical reaction.

Jan 1, 1999

By Robert M. St. Louis, Janet M. Edgecombe

The Mercur Mine's autoclave is an alkaline pressure oxidation system, operating at 220°(428°F) and 3061 kPa (444 psig) (total). Up to 725 metric tons (800 st) of ore, grading 2.02 g per mt (0.059 oz/st) Au and containing 1 to 2% sulfide sulfur, are treated daily in this circuit. A mineralogical and chemical investigation was initiated to locate the cause of lower than anticipated gold recoveries. Greater than 70 wt. % of reduced sulfur is oxidized; therefore, the autoclave is operating at specification. The low recoveries were attributed to increased concentrations of organic carbon in refractory ore. Activated carbon concentration in the attached CIL circuit was increased from 15 to 40 g per 1, leach temperature held below 21°C (70°F), and carbon flow changed to counterflow. These measures resulted in gold recovery improving from 75 to 82%.

Jan 1, 1990

New York Meets first Wednesday after first Tuesday of each month. J. E. JOHNSON, Jr., Chairman EDGAR RICKARD, Vice-Chairman D. M. LIDDELL, Secretary, 7 Wall St., New York, N. Y. C. A. BOHN, Treasurer JOHN V. N. DORR. LEWIS W. FRANCIS Boston Meets first Monday of each winter month. R. L. AGASSIZ, Chairman JAMES G. CARLETON, Vice-Chairman E. E. BUGBEE Secretary-Treasurer, Mass. Inst. of Technology, Cambridge,Mass. W. E. C. EUSTIS G. A. PACKARD Columbia Holds four sessions during year. Annual meeting in September or October. W. H. LINNEY. Chairman OSCAR LACHMUND, Vice-Chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, P. 0. Drawer 2154, Spokane, Wash. STANLY A. EASTON S. SHEDD Puget Sound Meets second Saturday of each month SIMON H. ASH, Chairman I. F. LAUCKS, Vice-Chairman CHARLES SIMENSTAD, Secretary-Treasurer, 425 Lyon Bldg., Seattle, Wash. GLENVILLE A. COLLINS JOHN N. POTT

Jan 10, 1917

By Wanchai Teparaksa

Pile deviation generally can happen after installation of driven pile particularly in soft soil layers. In this case study, all 242 diameter 0.8 m spun piles were deviated from 20 to 820 mm. The large deviation was caused by lateral soil movement in the top very soft clay layer of thickness about 23 m. This very soft marine clay is very sensitive and anisotropic having high water contents of over 120% and low undrained shear strength of 5-10 kN/m2. The remedial works were carried out based on theory of load transfer and soil-structure interaction. All deviated piles were rectified and used as the foundation piles with strictly controlled pile load tests. The construction of a nine-storey building was successfully completed founded on the rectified piles and it has been opened for the service for over two years.

Jan 1, 2002

By Augustus Locke

THE technical sessions at the Regional Meeting of the A.I.M.E. in San Francisco are to be de- voted LO changes, current or predictable, which may be expected to alter today's practices in mining and metallurgical engineering. Our present condition may be summarized as follows: Capacity to produce is excessive for domestic needs in molybdenum, copper, iron, and oil; sufficient in lead, zinc, and potash; deficient in aluminum, manganese, tungsten, chromium, and tin. Gold and silver are complicated by their use as money. Or, to look at it in another way, the "growth curles" of production, as C. K. Leith emphasizes, characteristically rise slowly at the beginning, show a second stage of rapid growth, and a third stage of leveling off. The third stage is already reached here in coal. copper, iron, lead, and zinc. But still in the second slage are oil, molybdenum, potash, and others.

Jan 1, 1939

The 14MW SAG mill at Tarkwa, Ghana, experienced a frozen drop charge incident on 10 February 2010. This caused downtime of 112 hours, a repair cost of $200k and production loss of 162,000 tons, corresponding to a loss of $8.9M. A new locked charge protection system was installed on the two Tarkwa mills on 30 July 2010, mitigating this risk. This system calculates the ore angle in real time while the mill is starting up and trips the mill if the ore angle exceeds a trip angle setting. The calculation of the ore angle is derived from the mill motor rotor currents only - no mechanical transducers are required. The head of Gold Fields West Africa, Peter Turner, says of the new system: "This is excellent work and the type of technology that has had and will continue to have, major opportunity cost impacts on our business."

Jan 1, 2012

By John Pekrul

Coeur Rochester Inc. located in north central Nevada, operates an open pit mine moving a total of 16 - 18 million short tons of material per year. A three stage crusher produces approximately 8 million tons of a minus half inch product that utilizes truck stacking to construct a heap leach with a zinc precipitation recov­ery plant. Coeur Rochester recovers approximately 6.0 - 7.0 MM ounces of silver and 60 - 80 K ounces of gold annually. Current metal prices and good operating practices require contin­ued review of operating systems that support the operation, thus the development of a Strategic Mine Plan. This Strategic Mine Plan provides managers, engineers and supervisors a means to improve their operations through three main objectives: 1. Reduce operating costs, 2 .. Increase production, 3. Increase mine life (reserves). These three main objectives will be reviewed in context to their current status and past performance.

Jan 1, 1999

By G. W. Healy

The smelting of calcium carbide has always been plagued by eruptions, too often with serious injury y or loss of life. To find their causes, the author calculated an internal energy balance using 1992 data for CaC2 and CaO, and older data for the remaining items. The heat content of the charge, and that of the hot gases formed at the reduction temperature, showed that only a fraction of its heat content can be supplied by these gases. Laboratory data on the electrical resistivity of fine mixtures of coke and non-conductive solids were extrapolated to a commercial carbide charge, and then used to calculate the heat produced by current flowing through the mix from the electrode surface to the hearth, which, under favourable conditions, sufficed to bring the charge to 1900 K and higher, at which temperatures reduction could take place.

Jan 1, 1995