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The dynamic response of holdup in a continuous ball mill has a direct influence on the rate function of grinding kinetics and is useful for predicting the variation in the size distribution of the finished product with time.A model was proposed involving three interacting, completely mixed chambers and this was used to derive analytically the transfer function of the system, from which the unit impulse response and the unit step response of the holdup with feed rate were obtained.The theory was confirmed by comparing it with previously published experimental data for the residence time distribution of particles passing through a ball mill.

Jan 1, 1975

By H. M. Lawrence

"Florida, the State that supplied 82 per cent of the phosphate rock sold in the United. States in 19284, has two producing areas - the hard-rock and the land pebble districts. Production of the hard-rock field, decreasing importance in recent years, is now confined to mines near Dunnellon, in Marion and. Citrus Counties. The land-pebble district, with a production of almost 80 per coat of the nation's requirements, is located, in Polk and Hillsborough Counties. In the land-pebble area the phosphate deposits - probably Pliocene in age, derived by marine action from underlying, older, phosphate-bearing formations - consist of beds of phosphate matrix, covered by practically barren sands and clays. The overburden, ranging in thickness up to 45 feet, is removed by hydraulic methods or by drag-line excavators. The matrix, ordinarily less than 25 feet in thickness, is mined by hydraulicking and is pumped to adjacent washing plants for beneficiation. The dried product of the washing plants is the Florida pebble rock that is sold in foreign as well as domestic markets.The beneficiation of phosphate ores in the land-pebble district of Florida has been largely limited in the past to the recovery of the coarser pebbles. By washing and screening the crude matrix a separation is effected at about 20 mesh (0.033 inch). The coarser material is the phosphate-rock product of the plant and the finer material is discarded. The amenability of the washer- rejects to treatment by other processes is being investigated. Of methods that may have some application to the treatment of the low-grade phosphatic sands that comprise the greater portion of the washer-rejects, gravity concentration has received some study.Laboratory experiments to determine the amenability of phosphate sands to gravity methods of concentration were first performed in October, 1927. Later, in the winter of 1928-1929, a further series of teats was made,. In these later tests phosphatic sands were concentrated by hydraulic classification, and. also by hydraulic classification followed by tabling. In these experiments concentrates with an analysis above the minimum grade of commercial phosphate rock (66 per cent bone phosphate of lime - B.P.L.) obtained. The recovery of the phosphate varied but was promising enough to warrant further study. A more comprehensive investigation was therefore outlined. This paper presents the results obtained from an investigation, of classification and tabling of phosphatic sands recently completed by the United States Bureau of Mines Su cooperation with certain Florida phosphate companies, the Missouri School of Mines and Metallurgy, and the University of Alabama."

Jul 1, 1930

By Raymond Rivera

El presente texto describe la evaluación desarrollada por INGEMMET donde se analiza el potencial de los depósitos minerales en el Batolito Andahuaylas, Yauri, así como el potencial de algunas zonas que presenten características geoeconómicas importantes, utilizando herramientas geológicas como geocronología, isótopos radiogénicos, geoquímica de rocas y sedimentos, petromineralogía y geología estructural.

Sep 12, 2011

By R. Adsero

The analysis of equipment trends in AUSIMM?s Revision of Monograph 19; Australasian Mining and Metallurgy Operating Practices (AMMOP) in the paper by Dight et al (in press) raised some interesting and in parts disturbing trends in the Open Cut Mining Industry. According to the US Bureau of Labour Statistics the US mining and petroleum industries? productivity is down by 12% since 2004 while the Australian Bureau of Statistics shows the productivity of the Australian mining industry is down by 34% since 2001. In terms of open cut equipment median output for draglines is down by 15% since 2003; electric rope shovels are down by 41% since 2003; hydraulic excavators are down by 39% since 2008; front end loaders are down by 39% since 2007 and trucks are down by 41% since 2006. Clearly the boom has not been good for the efficiency of the mines. During this same time, best practice (defined as the average of the top 10% by annual output per unit of input) has declined but not by as much as the median (eg. shovels down by 8%, excavators down by 19% and FEL?s down by 5%). This paper will build on the analysis of AMMOP to understand the differences occurring between median and best practice and identify the factors contributing to the decline in performance. As the industry enters a period of potentially lower prices for commodities and reduced margins pressure will be brought to bear on mine sites to start moving more with the equipment they have. An understanding of where efficiency has been lost will be a key component in that. The information contained in AMMOP, and the subsequent analysis of that information in papers such as this one will be crucial to reversing the decline in open cut equipment performance.

Feb 27, 2013

By D. Craig Camp

conditions. The soils included 65 m of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2, 130 meters of soft clay, silt, and sand not exceeding 30standard penetration test SPT blows per 300 mm, and 220 m of rock ranging between an UCS of 400-600 kgf/cm2. The river crossing, utilizing 1778 mm OD x 19 mm wall x600 mm steel casing pipe without intermediate jacking stations, was part of a seven kilometer liquefied natural gas (LNG) transmission line in South Korea. This 440-m, 1,442-ft, river crossing was microtunneled through three different ground conditions and completed in just over three months. The crossing was achieved with an average of 25 m of ground cover and 15 m of water cover. The Kwang Yang River Crossing was part of a 7 km liquefied natural gas pipeline project for POSCO, a Korean steel producer. The microtunneling machine was custom built for this project. The microtunneling machine selected for this project was tooled with 7 button bits and 2 roller bits. None of the cutter bits were replaced during the drive. Inside the machine, before the spoils laden slurry was pump back to the surface, it would pass through an independent cone crusher. The crusher is placed in the slurry flow to make sure that none of the spoils are so large as to stop the return flow of the slurry. An additional requirement was for the inclusion of a compressed air lock. The air lock was required in the event that the cutter tools required replacement. The cutters were back loaded so that the workers would have access to change the cutters in the event of cutter failure or wear out. No intermediate jacking stations were installed for the drive. The soils included 65 meters of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2 with production averaging between 7 and 20 mm/minute. The second zone contained 130 meters of soft clay, silt, and sand not exceeding 30 standard penetration test (SPT) blows per 300 mm with production averaging between 80 and 180 mm/minute. The third zone contained 220 m of rock ranging between an UCS of 400-600 kgf/cm2 with production averaging between 7 and20 mm/minute. The steel casing pipe was 1778 mm OD x 19 mm wall x 6000 mm long. The project profile, see Figure 1, shows the soil conditions. The hand written numbers locate just above the pipeline are the production dates. The circled numbers are the 10 pipe joint increments. The project required 74 pieces of pipe to span the440 m drive. Figure 2 and Figure 3 are the jacking information. Figure 3 is a continuation of the information from Figure 2. The top section of the graph is the jacking force. The jacking

Jan 1, 2001

By Garth Howlett

In 1998 the Matanuska-Susitna Borough formed the new port district at Point MacKenzie, known as Port MacKenzie, located directly across the Knik Arm from Anchorage. In 1991 PND Engineers Inc. (PND), working with the Matanuska-Susitna Borough manager and port director, envisioned a fill structure at Port MacKenzie with a 500-foot-long Open Cell? sheet-pile bulkhead face extending to EL -20 feet Mean Lower Low Water (MLLW) at the face. Now under operation the fill created 5.5 acres of tideland property using local materials for fill. The fill is protected from 2- to-3 foot-thick ice pans and 9 feet per second (fps) tidal currents by an envelope of armor rock. Construction required working in water with 30 to 40 feet of tidal variation. Construction required placement of frozen fill in water depths possibly exceeding 50 feet, creating real concerns about soil consolidation and long-term maintenance issues. A plan was prepared to consolidate the soils using Vibracompaction. Soil Density and consolidation were monitored during the work. In 2003 the port district and NPI, a wood chip export company, formalized an agreement to construct a deep water port facility at Port MacKenzie for cape-class bulk carriers. PND provided planning, studies, geotechnical investigation, design documents and construction inspection for a 500-foot-long trestle with a platform dockhead and dolphins providing 1,100 feet of dock face in EL -70 MLLW as shown in Figure 1. Design included installation of large-diameter spin-fin piles driven on a 2V:1H batter. Also included was a 300-ton tension test of smaller spin-fin piles.

Jan 1, 2006

By Ian Gordon Hall

El presente texto describe el proceso de recuperación de las partículas ultrafinas de casiterita en los relaves de la mina San Rafael a través de diversas pruebas metalúrgicas, donde se usaron dos tipos de concentradores centrífugos, los cuales indicaron la posibilidad de una recuperación de 50%, produciendo concentrados de 50% Sn. Asímismo, se instala una planta piloto donde se verifica el proceso de las distintas configuraciones y combinación de equipos, como el efecto de las cargas circulantes. Paralelo a ello, se realizan pruebas para aumentar la ley de los concentrados primarios y así obtener concentrados finales a través de concentración gravimétrica.

Sep 12, 2005

By C. Carlson, W. Muir

"The oxygen demand of the complex lead-zinc-iron feed at the Cyuro Anvil concentrator was determined denendent on the cyanide ion con-contration of the pulp. By redistribution of the cyanide [ ] the grinding circuit in direct proportion to the amount of surface area created, a more activated flotation feed in obtained.Monitoring the oxygen demand of the flotation feed and grinding mill discharge has proved useful in diagnosing metallurgical problems day to day operation."

Jan 1, 1976

UNITED ENGINEERING TRUSTEES, INC. James L Head, '55 E C Meagher, '52 Gail F Moulton, '53 Advisory Committee to Real Estate Committee Cleveland Dodge Herbert Hoover J Paul D Merica THE ENGINEERING FOUNDATION E. R Kaiser, '54 W. M Peirce, '52 E C Meagher, ex officio as President, UET Research Procedure Committee E. R Kaiser ENGINEERING SOCIETIES LIBRARY BOARD James L Head, Chairman Frank T Sisco, '54 E M Wise AMERICAN STANDARDS ASSOCIATION Mining Standardization Correlating Committee Otto Herres, '53 J K. Richardson, '53 H H Otto, '53 E W Bullard, '53 - Alternate

Jan 1, 1952

By J. D. Steenkamp

Southern Africa has a history rich in the pyrometallurgical processing of ores. Two of the alloys produced are high-carbon ferromanganese (74?83 per cent Mn) and silicomanganese (59?67 per cent Mn and 14?31 per cent Si). The largest land-based manganese ore deposit in the world is based in the Northern Cape Province of South Africa. In 2010, 6.3 Mt of ore from the deposit was exported, mainly to China, Norway, Japan, and India, and an estimated 1.1 Mt beneficiated locally to produce manganese ferroalloys. In southern Africa the producers of manganese ferroalloys are Metalloys and Assmang, and of silicomanganese Transalloys, Mogale Alloys, and Match Corporation. Submerged arc furnace technology is utilized in the production of high-carbon ferromanganese (HCFeMn) and silicomanganese, applying the discard slag practice in both instances. The carbon content of HCFeMn is reduced using converter technology and that of SiMn using the Perrin process. Ninety per cent of the world?s manganese ferroalloys production is consumed by the steel industry. The consumption (and production) of manganese ferroalloys therefore closely follows worldwide steel production. From 2001 to 2010, the doubling of the worldwide production of manganese ferroalloys can be attributed to an increase in production capacity in Asia and Oceania, with the largest increase in the production of SiMn. Manganese ferroalloys produced in Asia and Oceania are mainly for the local market, with North America, Europe, Russia, and Turkey the major markets for alloys from southern Africa. The major challenges faced by the southern African manganese ferroalloy producers are increasing electricity tariffs and productivity of labour, which require a concerted effort by all parties involved to achieve a satisfactory solution. Keywords manganese ferroalloys, ferromanganese, silicomanganese, southern Africa, South Africa, manganese ore, high-carbon ferromanganese, refined ferromanganese, refined silicomanganese.

Aug 1, 2013

By Greg Rasmussen

"Huckleberry Mines Ltd is an open pit porphyry copper-molybdenum mining operation located 120 km south of Houston, British Columbia with a 18,000 tpd milling facility. Huckleberry Mines is owned 60% by Princeton Mining Corporation, the operator, and 40% by Japanese partners.The Huckleberry deposit is one of several porphyry systems located in the Tahts a district of the intermontane belt of British Columbia. The principal economic minerals are chalcopyrite and molybdenite. The ore deposit is split into two ore deposits, the Main Zone, consisting of24,241,000 tonnes of mineable reserves grading 0.484 %Cu and 0.013 %Mo, and the East Zone, consisting of 66, 131,500 tonnes of mineable reserves grading 0.523 %Cu and 0.014 %Mo.The milling begins with gyratory crushing. This sizes the product down to 100% passing 6 inches. This product is discharged onto a stockpile by a stationary conveyor. The stockpile was designed for a capacity of 144,000 tonnes with a live capacity of 20,000 tonnes. Two apron feeders draw the ore from the bottom of the stockpile and discharge onto a SAG mill feed conveyor which in turn feeds a grinding circuit consisting of one 32' x 15' SAG mill and two 30' x 16.5' ball mills. The grinding cyclone overflow feeds bulk flotation at 55 -65% minus 200 mesh.The bulk flotation uses conventional rougher and column flotation methods to float a bulk concentrate recovering 92.6% copper on the East Zone and 95% copper on the Main Zone with 75% recovery molybdenum on both zones. The bulk concentrate feeds the bulk thickener which produces a density of 60 %solids. This in turn feeds the molybdenum circuit, which separates the copper and molybdenum, by depressing the copper then using conventional rougher and column flotation produces a copper concentrate of 27 %Cu and 0.02 %Mo, and a molybdenum concentrate containing 1.5 %Cu and 54 %Mo at 67% recovery. These concentrates are separately thickened, filtered, dried, and shipped to the smelter for processing."

Jan 1, 1998

A research project was commissioned by the Australian Coal Association Research Program (ACARP) to improve the understanding of tailgate strata mechanics and to provide a more rigorous engineering basis for tailgate support design. A deformation mechanism termed æskew roofÆ was defined which relates the regional influence of differential horizontal strata movement (shear) about longwall extraction to gateroads. Confirmation of the mechanism was achieved by field investigations which included measurement of the shear displacement along weak interfaces. Under geological and mining conditions where the skew roof mechanism operated, strata units were found to move progressively further towards the goaf with height into the roof. 3D numerical modelling was used to assess the major geotechnical factors controlling the mechanism and to determine appropriate support strategies within a æskew roofÆ environment including the role of cables versus standing supports. The skew mechanism is considered relevant to; all roadways in the vicinity of longwall extraction including the faceline itself, chain pillar design, and support design.

Jan 1, 2005

By G. A. Smyres

A GaC12--B2 l-eachtng procedure and meEal-recovery method for treating an arsenical Cu-Co sulfide concentrate was developed by the Bureau of Mines as an alternative to smelting, which is no longer considered an environmentally acceptable method for treating arsenic-containing ores. The procedure involved leaching in a CaC12 solution with CaC03 for 96 h at 26 pct solids (concentrate and CaC03), 1150 C, and a pressure of 50 psig (345 kPa) with oxygen. More than 98 pct of the cobalt and 97 pct of the copper were extracted, and 99.98 pct of the arsenic and 99.9 pct of the iron remained in the leached residue. A filtration rate of 2.9 gal/(ft2.h) [118 L/(m2.h)] and a cake formation rate of 36 Ib/(ft2.h) [172 kg/(m2.h)] were obtained by filtering reacted pulp at 1000 C. More than 99 pct of the copper in the pregnant solution was extracted as CuCl2 by golvent extraction with a new copper extractant. Copper was stripped from the loaded organic with a sulfate-chloride solution, which was used as the anolyte for electrowinning of copper in a membrane cell. Copper plate produced was more than 99.99 pct pure and requi.red 0.81 (kW'h)/lb Cu [1.78 (kW·h)/kg Cu]. Cobalt sulfide was precipitated at pH 3 with Ca(HS)2.

Jan 1, 1986

By E. Vahidi

In this study, a hydrometallurgical treatment involving solvent extraction of zinc using D2EHPA (di-2-ethylhexyl phosphoric acid) has been investigated to recover zinc from an industrial zinc leach residue. The residue was leached with sulfuric acid producing leach liquor which was subjected to solvent extraction for enrichment of zinc and removal of impurities. Operating variables for the zinc extraction process, such as pH of the mixed solution (0.5~5.0), concentration of D2EHPA (5%~40%, w/w), temperature (25~60°?C), A/O volumetric phase ratio (1/2~4/1), concentration of tri-butyl phosphate (TBP) as modifier (3%~7%, w/w), concentration of NaR2RSOR4R in aqueous phase (0.05M, 0.1M, 0.2M) were also studied. Practically all zinc was extracted from the aqueous solution at pH 2.5 with 20% w/w D2EHPA in kerosene. At this operating condition, zinc could be extracted at one theoretical stage at A/O phase ratio of 1/1, as calculated by the McCabe-Thiele method.

Jan 1, 2014

This technical note describes a problem with WANG82, a ventilation network analysis programme. The problem was highlighted by Renison Ltd when using the programme on large, complex networks. Under certain circumstances the programme produced incorrect results or failed to converge to a solution.

Jan 1, 1986

Apr. 26-May 11, Liege International Fair, Liege, Belgium. May 4-8, Electrochemical Society, Inc., Spring meeting, Benjamin Franklin Hotel, Philadelphia. May 5-6, National Air Pollution Symposium, Huntington Hotel, Pasadena. May 5-7, American. Mining Congress, coal convention, Netherland Plaza Hotel, Cincinnati. May 6-9, Scientific Apparatus Makers Assn., annual meeting, Edgewater Beach Hotel, Chicago. May 9-10, AIME, joint meeting, Industrial Minerals Div. and Metals Branch, Davenport Hotel, Spokane, Wash. May 11-14, American Institute of Chemical Engineers, Atlanta Biltmore Hotel, Atlanta. May 17, AIME, Chicago Section, President's night dinner dance, Shoreland Hotel, Chicago. May 27, AIME, Morenci Subsection, Longfellow Inn, Morenci, Ariz. June 2-4, Chemical Institute of Canada, annual conference, Montreal. June 4-14, Mechanical Handling Exhibition and Convention, Olympia, London.

Jan 1, 1952

By Kelly E. G

NZ Steel's flushing slag typically contains 1.2 per cent V203. Extraction of vanadium from powdered slag using a salt (NaCI or Na2CO3) roast/leach process was investigated. With NaCl, optimum extraction conditions were a charge containing 10 per cent NaCI, roasting in air at 875°C for 4 hours, followed by leaching in dilute H2SO4. Extractions were typically 30-50 per cent. NaCI roasting did not chemically attack the slag; the phase transformations that occurred were due to high temperature oxidation. Slag particle size had a significant effect on extraction.Optimum conditions for extracting vanadium by Na2C03 roasting were 20 per cent Na2CO3 in the charge and roasting in air for 3-4 hours at 850-875°C followed by water leaching.Na2CO3 roasting involved chemical attack that resulted in the formation of perovskite (CaTiO3) and carnegieite (NaAISiO4).The extent of vanadium extraction depended on the amount of Na2CO3 added and the original slag SiO2 content.Compared to the separate roasting treatments, simultaneous treatment with NaCI and Na2CO3 gave lower vanadium extraction, while requiring considerably higher roasting times and temperatures.

Jan 1, 1982

By Zwaan J, Kepa J

Ok Tedi mine has become one of the major copper producers in the world. In the process of becoming of age, it overcame the challenges of operating in a locality which is young in geological terms, experiences very high rainfall and has a topography which gives rise to frequent landslides. This paper discusses some of the geological, mine and geotechnical engin- eering aspects of the Mt Fubilan ore deposit.

Jan 1, 1991

By R. V. Kumar, C. Schwandt, S. Subramanian, S. Sampath, S. Vimalnath

Waste waters and industrial effluents containing toxic heavy metals such as Pb, Hg, As and Cr, beyond permissible limits (0.1 ppm, 0.01 ppm, 0.02 ppm and 0.05 ppm, respectively) (WHO, 2011), pose serious threats to the ecosystem, when discharged into the environment. It thus becomes imperative to monitor the concentration of the toxic heavy metals and treat them before discharging. In this study with the above objective in mind, a microbial sensor has been developed using P. aeruginosa cells drop coated onto a carbon paste electrode (CPE) for the detection of Pb(II) ions in aqueous solutions. Detailed biosorption experiments confirmed that complete bioremoval of lead could be achieved using P. aeruginosa cells under optimum conditions of pH and biomass loading. For the electro-analytical determination, the Pb(II) ions were initially preconcentrated on the P. aeruginosa modified CPE, reduced and then anodically detected with oxidation of Pb0 using differential pulse anodic stripping voltammetry (DPASV) technique. All the experiments were carried out in the presence of 0.1 M sodium acetate buffer and KNO3 as background electrolyte. The parameters namely pH, scan rate, biomass loading, deposition potential, deposition time and concentration of Pb(II) ions were optimized for the biomass modified CPE, to obtain maximum voltammetric response. Under the optimized conditions of pH 5.6, scan rate of 0.008 V/s, biomass content of 1.7–1.8×109 cells/mL, deposition potential of –1.2 V, and deposition time of 500 s, the developed microbial sensor showed a linear response for the peak current between 0.5×10-5 M and 1×10-8 M of Pb(II) ions with the R2 value of 0.9979. The lowest limit of detection (LLOD) was determined as 2.4×10-7M of Pb(II) ions (0.05 ppm). The redox mechanisms of Pb(II) ions on the P. aeruginosa modified CPE surface are discussed.

Jan 1, 2016

John Langton, New York, N. Y. (communication to the Secretary*):—In Mr. Firmstone's discussion (Trans., xli., 912) the formula he gives for the periodical payment—his equation (2)—may be simplified in form. The expression given by Mr. Firmstone is : q=S(l+ r) 1-(1+r)-(1+r) r which is a simpler form to use in calculations. Where S= principal to bc extinguished. Q = periodical payment or charge for sinking-fund, r = rate of interest per period (i. e., interest on $1 per period). n = number of payments or periods. Kent's Mechanical Enyineer's Pocket Book, under the heading Annuities, equation No. 5, gives : " The annuity which $1 will purchase for any number of ytlars n is * Received Jiily 16, 1911.

Jan 1, 1912