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By G. J. C. Young

In 1986 the city of Johannesburg celebrates its first century of existence. The fact that the city was founded to exploit the gold deposits which underlaid it, prompts this review of the gold process development in the mining industry of South Africa. Clearly a complete history of, the gold recovery process to date is not called for and it is proposed therefore to outline the most significant developments which have taken place since the middle 1930's, that is to say the last 50 years or so. Prior to this period the industry had seen the development of comminution processes employing cone crushing in closed circuit with vibrating screens followed by grinding in rotating mills and the gradual disappearance of stamp mills. The all sliming process was well established as a viable route and continuous dewatering in thickeners, continuous leaching and filtration were serious rivals for the earlier batch processes. Continuous processes for gravity concentration had also been developed and the recovery of gold from pregnant solutions employed cementation on zinc dust as opposed to shavings. Thus at the beginning of the half century under review the industry had adopted, or started to adopt, many of the processes still accepted as modern practice. However in some areas little change was evident this was especially so in the smelthouse where some thirty more years were to elapse before the hand stoked coal fired calcine and reverbatory furnaces were replaced by more environmentally acceptable electric furnaces. The most significant feature in recent history has been the mining of progressively lower grades of ore and the retreatment of tailings from earlier operations, much of the latter comprising tailings only a decade or even less in age. Notable among these operations are those on the East Rand near Springs in the Transvaal, in the Orange Free State at Welkom and more recently, massive reclamation of tailings close to the city centre itself. The carbon in pulp (CIP) process has been much publicised in recent years and all new plants erected during the 1980's have adopted this route for gold recovery. However the major proportion of tonnage milled in the industry is still subjected to the more traditional process of liquid solids separation by vacuum filtration. The discussion that follows will centre largely on the developments in the traditional process route, which for the sake of completeness is listed below: Comminution Dewatering Leaching Liquid solids separation Gold recovery Smelting

Jan 1, 1985

By AIME AIME

THE Tuesday afternoon session", H. A. Bedworth chairman and T. S. Fuller, vice-chairman, was opened with D. J. McAdam, Jr.'s paper entitled "The Influence of Cyclic Stress on Corrosion." This paper dealt with the influence of cyclic stress on corrosion of alloy steels, corrosion-resisting steels, monel metal and aluminum alloys. The paper was discussed by T. S. Fuller, who pointed out that steels under stress corroded more than unstressed steels when subjected to steam.

Jan 1, 1930

Using Dynamic Simulation Throughout a Process Plant's Life Cycle

Sep 13, 2010

By J. Hupka

Some aspects of kerosene penetration into tar sand have been investigated. The natural tar sand porosity was measured and used to analyze the performance of the hot water process. Subsequently, pretreatment experiments, using 20 kg tar sand samples (Asphalt Ridge and Whiterocks, Utah), and kerosene as a diluent were carried out at the expected summer temperature (26°C) and the expected winter temperature (-14°C). The natural tar sand porosity accessible by diluent has a crucial impact on the reduction of bitumen viscosity, and influences the penetration time required for successful bitumen separation from tar sand by hot water processing. Thus the tar sand porosity is an important variable which determines appropriate operating conditions. Experimental results indicate that diluent penetration into the Asphalt Ridge tar sand (high porosity) is almost complete after 30 min, whereas for the Whiterocks tar sand (low porosity) the penetration process is much slower, and still not complete after 15 hours regardless of the ambient temperature.

Jan 1, 1992

By D. H. Dvorak

Two pilot-scale biological reactor systems were installed to treat metal-contaminated water. The reactors consisted of barrels and tanks filled with spent mushroom compost, within which bacterial sulfate reduction became established. Concentrations of Fe, Zn, Mn, Ni, and Cd were lowered by over 95% as these metals were precipitated as insoluble sulfides by reaction with bacterially generated H2S. The chemistry of the reactor systems is examined, and opportunities for maximizing their metal-retaining and alkalinity-generating potentials are discussed.

Jan 1, 1991

By Alison Savage, Michael Terry

"For decades, the International Market Place (IMP) has been an icon in the heart of Waikiki in Honolulu, Hawaii. It was famous for Duke Kahanamoku’s restaurant where people flocked to hear Don Ho sing in the ’60s and ’70s. Later, it was a bustling, open-air hub of small vendors who peddled everything from Hawaiian souvenirs and jewelry to food court meals and farmer’s market produce. Small buildings and shacks that housed the businesses were located on a curved tract of land — just one block off the beach — that stretches from Kalakaua Avenue to Kuhio Avenue. The entrance to the complex is dominated by a huge, old (circa 1850) Banyan tree. This tract is owned by the Queen Emma Land Company. Queen Emma was a Hawaiian Queen from the 1800s. Revenue from the land has supported the Queen’s Medical Center in Honolulu for decades.The reimagined IMP is owned by Taubman Centers, of Bloomfield Hills, Mich., and CoastWood Capital Group of San Francisco, Calif. The IMP will offer a distinctive collection of upscale fashion and lifestyle retailers, including Hawaii’s only Saks Fifth Avenue store, as well as ten sit-down restaurants, including concepts by award-winning chefs Michael Mina and Roy Yamaguchi. The mall features two large open-air courts, the first of which has the huge Banyan tree as its entryway centerpiece. The second open-air court, called Queen’s Court, includes a stage and mature monkeypod trees and a few palm trees. Foundation SelectionAfter a geotechnical exploration that was directed by SME, Plymouth, Mich., and performed by Geolabs, Honolulu, it was discovered that the historical site had hidden and challenging foundation conditions. The subsurface conditions included a very deep but now in-filled ancient river valley containing more than 180 ft (54.9 m) of lagoonal deposits consisting of normally consolidated plastic clayey silts and silty clays with blow counts mainly varying in N-value from 1 to 6. The silt was underlain by several soft coralline layers, some overconsolidated clays and various basalt layers. The static groundwater level on the site was at a depth of about 5 ft (1.5 m), closely matching sea level.Although driven piles had previously been used as the preferred deep foundation support for adjacent structures, this area of town is now fully developed and local noise ordinances preclude their use. Augercast piles were initially considered, but when the general contractor dck/FWF, Pittsburgh, Pa., asked for bids for the augercast piles, several foundation contractors offered alternate systems. The practical installation depth of augercast piles was limited and due to the depth of the in-filled alluvial valley, this system could likely have left soft silt below the tips of the piles over much of the site."

Jan 1, 2016

Of the twelve known ore zones on the Sunro property, acquired by Cowichan Copper Co., only the "B" and "C" orebodies of the "River Zone" had been explored sufficiently to indicate the grade and tonnage. The "B" zone was selected for initial production. The portion of this orebody above the main adit level was developed for horizontal-ring, longhole mining. Ore from the stope would be scraped directly to the coarse ore bin. The lack of a suitable mill site on surface, as well as the 8,000-ft. tramming distance, led naturally to the installation ground. I N November, 1960, a lease was obtained by Co-wichan Copper Co. Ltd. (N.P.L.) from Sunro Mines Ltd., covering the main ore (River) zone of the Sunro property. A total of twelve zones had been located on the property. Nine of these lay within the leased area. With the exception of the "B" and "C" orebodies of the River Zone, there had been insufficient exploration for tonnage and grade calculations. Exploration by previous companies had

Jan 1, 1965

By David Wright, Jerome Chamfray, Anthony Harding, Brian Boye

Conway’s Law states that unless we intentionally design automation tools around what we need, we will simply replicate our existing processes. While we may achieve some savings this way, there is an opportunity for greater benefits if we re-imagine the way we, as an industry, perform design. This paper examines current technology and shows how even small departures from merely encoding what we currently do could reap significant benefits. From these examples a framework is developed for a new and innovative approach tvo automation that will allow us to design more quickly, to a higher quality, and communicate outcomes more effectively.

Dec 1, 2022

By R. A. Matuszak

Throughout the history of power excavating machines, engineers have continuously tried to shape the main drive speed-torque characteristics to provide an optimum performance from each main motion. Selection of prime mover for the various motions has been the subject of many engineering studies and most forms of energy conversion have been tried. A new form of electrical power conversion looms on the horizon' as the most optimum yet. Controlled frequency operation of a squirrel cage induction motor increases the reliability of the most reliable form of energy conversion (electrical) found thus far and at the same time improves the performance characteristics.

Jan 1, 1977

By W. Clark Ashby

Trees are an essential ingredient of sound reclamation in nearly all surface mining regions. There are, however, possible problems in current reclamation regulations and practices which need to be evaluated and remedied. Recognition and accomodation of growth requirements for trees and other plants will greatly increase reclamation success. Surface mining encompasses a series of processes from a pre-mining baseline study to bond release following revegetation. Land owners, and society, have a great interest in subsequent plant growth on reclaimed areas and in future land values.

Jan 1, 1981

By J N. Farrell

Metallurgists frequently use a small number of large samples to characterise expected mill performance, with the a priori assumption that these few samples are representative of the entire deposit. Geometallurgical sampling is becoming more prevalent as a way to use many smaller samples to indicate the expected recovery as part of the Mineral Resource or Ore Reserve estimation.The evaluation of magnetite deposits involves specialised approaches to sample preparation, sample analysis and resource estimation. The sampling protocol for magnetite deposits will typically include the use of Davis Tube analysis. The Davis Tube is a mini-pilot plant that is used for determining the mass magnetic recovery from a small amount of sample ground to a specific size. The magnetic concentrate may then be analysed and together with the mass magnetic recovery, may be used to simulate the expected mill recovery. The magnetite sampling protocol is specific to each deposit, and is typically designed around a specific metallurgical flow sheet.During resource modelling, the mass magnetic recoveries and concentrate grades may be estimated directly or assigned to a block model using regressions with other chemical constituents. For estimation, the concentrate grades are weighted to account for the different mass magnetic recoveries of each sample and the impact of these differences on the concentrate estimates.

Sep 5, 2011

By Alessandro Navarra, Amir Arash Rafiei, Kristian Waters

Mathematical programming (MP) is fundamental to systems engineering and operations management, but has not been widely adopted by mineral processors. The current paper presents an interdisciplinary approach, using MP to incorporate basic notions of mass balancing into an optimization framework. The optimization is typically related to economic profitability. Two- and three-product formulas are extended to give formal descriptions of alternate modes of operation, and a global representation of the concentrator. At this global level, the framework may assist plant managers to make tactical decisions based on incoming feed data. The MP framework is demonstrated through sample calculations describing a lead-zinc concentrator.

Jan 1, 2015

By J R BISHOP

Geophysical techniques are being increasingly used down exploration drill holes as deeper and more elusive targets are sought. This paper lists the various methods available and discusses the applications using a number of examples.

Jan 1, 1992

By D. Shen, J. Cheung

Variable reactance arc control by the SPLC (Smart Predictive Line Controller) has been installed at many different mining sites and steel processing plants around the world. Since its first installation 18 years ago, many advances have been made to both the technology, and to its integration with furnace processes and plant operations. The SPLC has helped to improve electric arc furnace stability by reducing electrode movement while maintaining flat line arc power. Stable furnace operation at higher average power increases productivity. This paper summarizes the progression of electro-technology at Hatch since the 1970s, including fixed and variable reactance, digital electrode regulation, and fast variable speed hydraulics for Soderberg electrode, as demonstrated and benchmarked through projects and lessons learned over the years.

Jan 1, 2015

By J. V. Vogel

Jan 1, 1969

By Janet Torma-Krajewski

Job tasks that involve exposure to work-related musculoskeletal disorder (WMSD) risk factors may impact both the risk of injury and production downtime. Common WMSD risks factors associated with mining tasks include forceful exertions, awkward postures, repetitive motion, jolting and jarring, forceful gripping, contact stress, and whole body and segmental vibration. Mining environments that expose workers to temperature/humidity extremes, windy conditions, and slippery and uneven walking surfaces also contribute to injury risk. National Institute for Occupational Safety and Health (NIOSH) researchers worked with powder crew members from the Bridger Coal Company to identify and rank routine work tasks based on perceived exposure to WMSD risk factors. This article presents the process followed to identify tasks that workers believed involved the greatest exposure to risk factors and discusses risk reduction strategies. Specifically, the proposed prill truck design changes addressed cab ingress/egress, loading blast holes, and access to the upper deck of the prill truck.

Jan 1, 2009

By J. S. Lewis

Beneficiation and physical and chemical processing of non-terrestrial materials borrow strongly from terrestrial experience, but also involve the necessity of handling literally un-Earthly feedstocks, reagents, and environmental conditions. The present state of scientific and engineering understanding of the processing of non-terrestrial minerals, gases and hydrocarbons is reviewed with the production of rocket propellants, life-support fluids, structural metals, and refractories as the goal.

Jan 1, 1992

By D. Lynn Gordon, Larry B. Weston, Michael W. Manhart, Patrick R. Bowden, Michael W. Redmond

Study of confinement effects on detonation characteristics and subsequent fitting form development as a function of confiner strength and thickness.

Feb 1, 2020

By Lewis Carroll

AS he contemplates the numerous good things the hard-working committees have evolved for the 140th Meeting of the Institute, the Editor knows just how the walrus felt when he uttered his memorable, if somewhat lugubrious lines. For there are the Annual Reception and Dinner at the Commodore, 'the Gold Supply Symposium, the luncheons, general and special, and the Annual Institute of Metals Lecture, a Round Table on Iron Ore and a wonderful Informal Dance at the Grand Central Art, Gallery, substantial general sessions, a Smoker-and many other things. -Old, friends and new, reminiscences and confidential chats, horizons pushed back by new information and adjusted perspectives, courage revived and ambitions stimulated-one with a flair for the modernistic might make something-or nothing-of the kaleidoscopic preview 'of the coming Annual Meeting.

Jan 1, 1931

Jan 1, 1947