Search Documents

By F. R. Deist, R. P. Plewman

Discussion: A. Hazell (Associate Member) and T. J. Kotze (Graduate Member): The authors must be congratulated on the development of a versatile computer programme for determining the stresses and displacements resulting from mining operations. As a design tool it will no doubt take its rightful place together with the analogue computer. Union Corporation made use of this digital computer programme whilst still in its development stage to determine the stress distributions which were causing the unexpected failure of the Marievale sub-incline shaft. Two features arising from this investigation may be of interest to members, namely: A. The solution to the problem of stabilizing a rectangular inclined shaft, which turned out to be contrary to accepted mining practice, and B. A comparison between the results obtained with the pure digital system and the analogue computer. A. The shaft is nine ft high and 20 ft wide, dipping at 9° to the horizontal and crossing the bedding planes. Fig. 1 is a plan and Fig. 2 is a section of the sub-incline shaft pillar area showing the relative positions of the shaft and reef as well as their respective dips. The deepest point in the shaft is 3 300 ft below surface and the requirement of a stress free ground surface may not be satisfied. It also means that the original gravitational stresses are low. A 900 ft wide pillar was left to protect the bottom section of the shaft, the top section being understoped years ago. Extraction of the pillar was started at the beginning of last year, mining operations being carried out in the accepted manner, starting beneath the shaft and mining outwards. The approach did, however, turn out to be the wrong one, because failure of the shaft was noticed soon afterwards. Even small movements were serious in this case due to the low clearance between the skips and the shaft supports. During October, 1968, failure between benchmarks 8 and 10 (see Fig. 1) became so excessive that hoisting speeds had to be reduced. Failure continued to occur and, by the end of March, 1969, failure had propagated up the shaft as far as benchmark 7, and down as far as benchmark 12. As this shaft had a tight hoisting schedule it was imperative that a quick solution be found to arrest the failure.

By P. Roy

Smelting or converting of sulphide concentrates and mattes in a batch operation presents a challenge when directing the off- gas to a conventional acid plant. The Hindustan Zinc Ltd. (a division of the Vedanta Group of companies) Chanderia Lead Zinc smelter was presented with such a challenge that was met with the adoption of the Cansolv® SO2 Scrubbing System. The Ausmelt top submerged lance technology used at Hindustan Zinc generates a furnace gas stream that containsbetween 0.1 vol% and 12 vol% SO2 during the three stages of batch smelting. Cansolv® SO2 Scrubbing Technology captures the SO2 to ensure that treated flue gas exits the facility at a concentration below 100 ppmv SO2 and it releases SO2 in a controlled fashion, to more closely match the needs of the existing acid plant. The application of a regenerable scrubbing system to capture SO2 from a batch-operated furnace and convert it to acid in a conventional acid plant was a first of its kind in the world. This paper provides an update on the design and operation of the Hindustan Zinc SO2 recovery system and suggests two improvements to the basic flow sheet that optimize the cost of SO2 scrubbing further.

Jan 1, 2007

The growth of "Unit Load-cargo handling technology in world cargo lin- er trades over the last decade has cre- ated a situation in which special pur- pose-vessels (cellular container ships, roll-on/roll-off vehicle deck ships and Lash type vessels) are rapidly replac- ing conventional cargo ships, the principal means previously available for transporting heavy lifts. Consequently heavy lift traffic has tended to accumulate awaiting ship- ment, especially where discharge is required in "off beat" locations. A partial solution to this problem will be provided by new and small but exceptionally versatile ocean going heavy lift carriers now finding their way into world trade routes. These new ships combine extremely high lifting capacity, high manoeuvreability and exceptionally shallow draft with bow and stern Ro/Ro capability. They can handle rolling loads of exceptional size and weighing up to 1,000 tons Each. But the problem is a far larger and more serious but essentially a domestic one. Major industrial pro- jects in Australia will require pro- gressively heavier and larger plant and construction sites are becoming much more inaccessible. Whereas these new ocean going heavy lift carriers have ample capacity to satisfy part of the total transport requirement, there is clear evidence to show that domestic transport resources have little if any potential for increase in capability at the same rate as demand or at the same rate as sea transport facilities. Resolution of the larger problem is within reach but only through a pro- perly co-ordinated approach to future planning for the overall needs of large scale projects on a national basis. This co-ordinated approach must involve Federal and State government transport administrators, railway and highway authorities, shipping and road haulage interests and finally the planners of the projects which require these improved heavy haulage services.

Jan 1, 1973

By S. Panigrahi

The SO2-ammoniacal ammonium sulfate leach liquor generated by leaching of manganese nodules, after removal of minor quantities of iron and manganese, contained copper, nickel, cobalt, zinc and (NH4)2SO4. After extraction of copper from the leach liquor with LIX 84I, stripping of ammonia from the Cu-barren raffinate was carried out followed by precipitation of metal ions from the ammonia-stripped solution as sulfides. Leaching of the sulfide precipitate was carried out with H2SO4 to obtain a leach liquor containing 0.58 kg/m3 Cu, 2.67 kg/m3 Zn, 2.00 kg/m3 Co, 24.68 kg/m3 Ni and 10.0 kg/m3 (NH4)2SO4. After extraction of copper and zinc from the sulfate leach liquor with LIX 84I and D2EHPA, respectively, the solution was left with Co and Ni. Extraction of cobalt from the Cu- and Zn-free solution was carried out with 0.1 M PC88A and stripping of the cobalt-loaded organic was carried out with the cobalt-spent electrolyte (pH 1.4). Extraction of nickel from the cobalt-free solution was carried out with 90% neutral 1M NaPC88A followed by stripping of the nickel-loaded organic with 120 kg/m3 H2SO4 solution. Extraction of metal ions increased with increasing equilibrium pH and extractant concentration. The maximum separation factors, with respect to the pH and extractant concentration variation studies, were 3796.7 and 15350.0, respectively. The extracted species for the metal ions were CoA2?3HA and NiA2?5HA.

Jan 1, 2009

By Luis Valentim, John E. Wiegand

Highwall or face profiling has long been used to facilitate the design and placement of front row blastholes to ensure optimum burdens. Traditionally, a large number of laser measurement points obtained from the rock face or highwall, were input in profiling software packages. This method can be time consuming and requires access to the rock face with a complete view of the highwall, to be successful. Stereo photography has also been used to generate the rock face surface, but this method also requires access to the highwall (and pit floor in some instances) for measurement of reference targets or points.

Jan 1, 2016

By Alfred E. Hunt

The charge to be described was made in a seven-ton furnace, with a hearth twelve feet long and eight feet wide, with three gas and three air ports on each side. The stock of the entire heat was charged cold in one hour and five minutes, a part of the pig being first placed upon the bottom to protect it, then upon it the plate-scrap and blooms, and finally the remainder of the pig—some two thousand pounds. In fire hours and twenty-five minutes after beginning the charge the metal was melted down level, and two hundred pounds of hot twelve-per cent. spiegel was charged, care being taken to have it entirely immersed in the bath. In two hours more the bath was thoroughly melted and hot, and began to boil, i. e., the carbon began to be oxidized and evolved through the bath of covering slag as carbonic acid and carbonic oxide gases. Seventy-five pounds of lumps of Republic specular iron ore were added at this time, increasing the action, so that in ten minutes after the metal was in active ebullition. A test of the metal showed it to have about 0.90 per cent. carbon. One hour after the first ore was added a test was again taken, after thorough rabbling of the metal, and it was found to be 0.37 per cent. carbon. One hundred pounds more of lump Republic ore and about seventy-five pounds of limestone were then added, and fifty minutes later, after the bath was thoroughly rabbled, a -test showed the metal to have 0.23 per cent. carbon. Twenty-five pounds more of Republic iron ore were added and the metal allowed to boil for twenty minutes, when a test, after rabbling, showed the carbon to be 0.18 per cent. and the manganese to be 0.01 per cent.; the slag fracture was vitreous and of a very dark-green color. About forty pounds of limestone were added, and, the metal being hot and in a state of quiet ebullition, a hickory pole of twelve feet length and about four inches diameter, was run through the aperture in the centre door and held in a steady inclined position in the bath, with the end touching the bottom, the pole being shoved in further as it was burned away. The bath was carefully watched to see that the action that ensued was not too violent, the pole being several times

Jan 1, 1884

By Virginia E. Gleason

In this report, recommendations are made for programs to develop workable techniques to stop or prevent acid mine drainage formation in those underground coal mines where acid production could take place. These recommendations include development of mine closure technology, development of surface water infiltration control procedures, study of the effect of roof collapse on mine water characteristics, evaluation of the long-term effects of flooding underground mines above drainage, investigation of the effectiveness of section sealing in active mines, development of a simple model for predicting mine water quality and quantity, preparation of a manual on mine drainage abatement procedures, and development of a program to disseminate information on mine drainage abatement to the coal industry. These recommendations are based on an in-depth evaluation of information acquired over years of research on acid mine drainage formation, on numerous laboratory and field studies of methods of preventing or minimizing acid mine drainage formation, and on review of the geological, hydrological, and mineralogical factors involved. There are 772 references.

Jan 1, 1978

By Andre Vien, Jean-François Dupont

"Over the past several years, Svedala has developed a continuous charge monitor (CCM) for tumbling mills. It consists of a strain gauge embedded into a rubber lifter and associated electronics. This paper describes the installation and use of such a device on a SAG mill at the Holt-McDermott Mine. Comparison to measured static volumetric load and bearing pressure and inclusion of the measurement into a control strategy and its potential for condition monitoring is discussed. INTRODUCTIONWhile the measurement of load is very important in all kinds of grinding applications, the biggest benefits are expected from AG and SAG milling. This is what motivated Holt-McDermott to take a closer look at this problem, with a view to optimizing SAG mill performance.In many cases, the SAG mill control problem can be stated as maximizing throughput while avoiding a volumetric overload, with the other constraints (e.g. power, grind size, upstream/downstream equipment constraints, etc.) playing a less important role. This is certainly true at Holt-McDermott where the SAG mill is the production bottleneck about 90% of the time, and anything that can be done to increase SAG mill throughput will have a significant impact on operating profit.Although the goal of maximizing throughput while avoiding volumetric overload is simple to state, it has proven to be much more difficult to achieve. The mineral processing industry has expended a great deal of time and effort to devise control strategies in the pursuit of this objective. While much progress has been made, there is still room for considerable improvement. Across the industry it is probably fair to say that overloads occur relatively infrequently, but the real losses accrue as a result of the tendency to run rather conservatively."

Jan 1, 2001

By George B. Clark

COMMERCIAL strip mining of coal was first begun in the state of Illinois in 1911.1 The annual tonnage of coal produced from coal strip mines in the state was very small until 1924, when the strip mines shipped 1.68 pet of the total state shipping mine tonnage. Since then, strip mines have gradually come into their own by producing a sizable percentage of the coal produced in the state. Table 1 shows the coal tonnage shipped from both underground and strip coal mines in the state of Illinois for selected years. The table illustrates the major role that strip mines play in the state's coal industry. Today, strip mining is generally conducted in areas where the coal seams lie so close to the surface of earth that a stripping method of mining the coal seam is cheaper than an underground method. Strip mining not only recovers 100 pct of the coal deposit, but may also be used as a method of mining large acreages of coal abandoned by the closing of underground mines.

Jan 1, 1949

By WM. E. Mlligan

IN the last year, much information had become available as to the extent that zinc participated in the war effort. The importance of foreign zinc in this program had been indicated by Bateman (M&M April 1945) as of the order of 400,000 tons annually in zinc or contained zinc. Pehrson (M&M April 1945) reviewed the domestic ore-reserve situation with respect to most minerals and metals and showed the extent to which commercial zinc ores had become depleted in this country. This picture was further darkened by O.P.A. figures appearing in E.&M.J. July 1945 in which figures for total production during the three previous years were broken down into percentages produced under ceiling and various quota price categories. True, factors other than depleted ore reserves contributed to this picture. Among the more important of these, were shortage and high cost of labor, both skilled and unskilled, and the general difficulty and cost of maintaining adequate equipment and supplies. The cost of production in the Tri-State district was most affected.

Jan 1, 1946

President Howe : It is not so clear to me that the facts which Dr. Waldo brings forward really argue that the nature of the combination between copper and aluminum differs from that of the combination between copper and zinc or copper and tin. As regards electric conductivity, I suppose that the fact, which he thinks points to a special intimate kind of union between aluminum and copper, is that the line in his Fig. 1 is neither straight nor uniformly curved, but that its curvature varies rapidly, not to say abruptly. But we find just such variation in like curves for the copper-zinc and copper-tin alloys. Thus, a slight addition of zinc or tin to copper causes a change in color wholly out of proportion to the quantity added; and, as we add zinc or tin to copper, the tenacity rises very greatly, only to fall off abruptly with further additions of either of these metals. Dr. Waldo : My curve related only to electrical conductivity. The President : If irregularity in one physical property argues

Jan 1, 1895

By D. Moradkhani

The heap leaching of oxide copper ores with copper cathode recovery by solvent extraction and electrowinning is now well established as a low-cost method of copper recovery. The main purpose of this study was to extract copper from the copper low-grade oxide ore of Chodarchaei mine using column leaching. The copper oxide ore contained 1.1% Cu and 1.75% Fe. The mineralogical analysis indicated the malachite (Cu2(OH)2CO3) was mainly composed of oxidized phases. The sulfuric acid leaching experiments were performed under the laboratory conditions. The influence of several parameters on the course of the reaction such as particle size, acid concentration, flow rate, and time was examined. The optimum collective extraction of copper and iron was obtained at a particle size of +10-15 mm for a leaching duration of 3 days with sulfuric acid concentration of 100 gpl and using a flow rate of 2.5 cc/min. Under these conditions, the recovery of copper and iron were 98.54% and 41.99%, respectively. Keywords: column leaching, copper, iron, working diagram.

Sep 1, 2012

By O. A. Ojo, E. Anisimov, A. K. Khan

Electro-spark deposition (ESD) has recently generated a great deal of interest in processing aerospace materials. This is due to its potential for joining and repairing difficult-to-weld precipitation strengthened nickel-based superalloys without having problems of welding cracking that often plaque these materials. The short duration of current pulses involved in the process combined with the intermittent contact results in extremely rapid thermal cycle that produces nearly no heat affected zone in the substrate material. The microstructure of electro-spark deposited superalloy was meticulously studied in this work by scanning electron microscopy (SEM) and analytical transmission electron microscopy (TEM). The results show that in contrast to general assumption, the extreme rapid cooling rates involved in the ESD process did not produce partition-less solidification that is devoid of second phase microconstituents in the material. The secondary microconstituents were found formed along the intercellular regions of the solidification microstructure. The nature of these particles and the possible implication of their formation on mechanical properties of ESD processed material are reported and discussed.

Jan 1, 2015

By Gerry Houlahan

The east span of the 3.5 km long SF-Oakland Bay Bridge is supported by different types of foundations along its span. Starting from the west, its first 460 m section comprising twin concrete box-girders is supported by sands and rock on Yerba Buena Island. A 620 m long steel suspension span then bridges a 25 m deep channel that is formed in sediments overlying rock. Twin concrete box girder structures, each 2.4 km long, complete the stretch over the remainder of San Francisco Bay to the engineered earth fill landing at its east end. For most of its length, the Skyway bridges water 3 to 10 m deep over soft surficial Young Bay Mud. The foundation types include spread footings with hold-downs, steel and concrete piles that are set in drilled rock sockets up to 3 m in diameter and 2.5 m diameter steel tubular piles driven to penetrations of up to 100 m. The design and construction-related considerations are presented. The different foundation types, influences of the site geology and earthquake demands on the substructures are discussed. The seismic motions of the bridge superstructures and substructures, as well as the depth-varying soil motions, influenced the foundation design. Together with performance-based design criteria, including post-earthquake footing displacement limits, these seismic demands influenced various aspects of the foundation design, including the use of battered and vertical piles.

Jan 1, 2005

By Bruce F. Bohor

Silica sand has been mined in Illinois from the St. Peter Sandstone since the turn of the century, especially in the area around Ottawa on the Illinois River in the north-central part of the state. Production of this sand, consumed mainly by the glass and foundry industries but also sought after for many other uses, has grown with the economy, and last year's output in Illinois exceeded 4,000,000 tons. Such an important commodity was given the early attention of the Illinois State Geological Survey, and a very complete report was issued in 1928, authored by J. E. Lamar. The mining and processing of the sand has changed very little during the intervening 40 years, so that much of Lamar's data and descriptions are applicable today. More recently, the stratigraphy of the St. Peter Sandstone in north-central Illinois has become better known from the work of Willman and Payne (1942). The present authors have borrowed generously from Lamar's publication, and we wish to acknowledge the contribution of both of these studies to our work.

Jan 1, 1969

By R. Hazael, R. Alford, R. Critchley

The ability to compare explosives is fundamental. Numerous methods are used and while simple conversion factors are often used, the use of TNT Equivalency (TNTe) is not a simple subject as explosives exhibit very different equivalencies depending on whether the pressure or impulse are being considered as well as other conditions. The scaled distance has been found to have a significant effect on the TNTe but due to the difficulty of taking measurements at very close ranges, no TNTe have been quoted for charges in direct contact (Z=0). This paper describes the use of a ballistic pendulum to measure the impulse from contact charges and presents some surprising results that require a two-stage propulsion, as originally described by Backofen, to be explained.

Jan 1, 2024

By Brian Khalighi, Massimo Franceschi, Giovanni Giacomin, Gianni Porta

Headrace Tunnels and parts of the Access Adit Tunnels of Kárahnjúkar Hydropower project, KAR-14, in Iceland will be excavated using three full-face Robbins Tunnel Boring Machines (TBM). TBM sizes range from 7.23 to 7.63 meters in diameter and the total headrace tunnel length is approximately 40 km. The crushed rock is transported on conveyor belts to disposal areas near each Adit. The estimated average excavation rate is approximately 25 meters per day per machine. Electricity will begin to flow in April 2007, and the project is scheduled for completion in 2009. This paper is divided into four sections. In the PROJECT OVERVIEW section, a short overview of the scope of the project is presented. In the GEOLOGY section, the geological condition along the tunnel drives is briefly introduced. The TBM DESIGN section discusses the various design criteria and the resulting machine specifications. The paper concludes in the TBM OPERATION section with a case history describing the tunneling operation from start-up to the time of the writing of this paper.

Jan 1, 2005

By D Laurence

Australians are at the forefront of exporting their mining expertise in a number of areas. Minerals education is just one example. The growing economies of Southeast Asia host some of the most prospective mineral fields in the world. Laos for example, hosts the world class Sepon and Phu Kham copper-gold deposits. The Philippines has the fifth largest global mineral resource inventory. These and other countries in the region lack the mining engineers, geologists and metallurgists required by international mining companies to ensure their operations are sustainable. This paper describes the author’s experience in working with mining schools in Southeast Asia and specifically the Philippines, Cambodia, Laos, Thailand and Vietnam. Various strategies to ensure sustainability and lessons learnt are presented.

Nov 22, 2011

By Amir Asadi

Various damage modes that evolve with time in polymer composite laminates, such as transverse cracking, vertical cracking, delamination, and fiber fracture, as well as the interaction among them, influence the time-dependent degradation in modulus (creep) and strength (creep rupture) of polymer composite laminates. This study is focused on modeling the time-dependent evolution of transverse cracking in [90] plies of a multidirectional polymer composite laminate [0m/190n]. This model uses a two-dimensional variational analysis to determine the stress state at any given creep time. The elastic stored energy, determined using this stress state, is compared with a critical energy for fracture to determine the crack evolution with creep time. Model predictions are compared with experimental results to validate the model.

Jan 1, 2010

By Liow Jong-Leng

A survey of the interactions of large gas bubbles formed from top and bottom injection of gases into melts was carried out. Spherical cap bubbles were found not to produce much splash when they break through the bath free surface except for that formed by plunging of the-spout at its edges. In contrast, the bursting of balloons produces cavities which give rise to liquid jets being ejected from the bath free surface. The position of the balloons relative to the bath free surface is an important parameter in the formation of the liquid jet. It is found that the interactions of multiple bubbles close to the free surface is important in determining the splash behaviour of gas injected systems.

Jan 1, 1996