Search Documents

By DV Boger

Rheology is the science which deals with the deformation and flow of matter. Thus nccology is concerned with the flow of any material. The mining industry is concerned with digging things out of the ground, extracting the good stuff and throwing away the had stuff. In the upgrading processes associated with mining, is mineral processing, wet techniques are used where the primary material being handled is a particulate fluid, ie a suspension. After the processing operation, with the concentrates extracted, what is left behind generally is a wet material in suspension form, which may or may not contain reagents harmful to the environment. The amount of waste generated in any of the mining processes is large, in fact, the mining industry is the largest generator of solid waste in Australia. In order to minimise the waste generated within the industry it has become of interest to handle the particulate fluid wastes, or suspensions, at high concentrations, thus removing water and some of the reagents which may be harmful to the environment. The resultant highly concentrated suspension is a non-Newtonian hold Rheology deals with the flow of non-Newtonian fluids; therefore i combination of rheological understanding of high density suspensions. ill conjunction with an understanding of the environmental problems hero' faced by the mining industry, can and has led to improved methods of waste disposal in the industry, ie waste minimisation. This paper describes the progress that has been made in the development of dry disposal technology in the mining and minerals industry in Australia.

Jan 1, 1998

By A Annor, L J. Chen

The production of paste backfill has typically been accomplished through the adaptation of existing technology. Thickeners and disc filters have several drawbacks when applied to production of tailings paste backfill. Personnel at CANMETÆs backfill research laboratory in Sudbury, Ontario, Canada have been carrying out research into and development of methods to produce paste backfill using total mill tailings since 1991. Using a silo for production of paste is not a new concept but has been refined to a marketable level. This technology is based on a fluidization principle that assists in settling the tailings to an homogenous state in a silo. Other developments include patented de-watering technology for use in the silo to speed the settling of the solids to a suitable solids content, optimisation of silo geometry, and instrumentation related to paste backfill production and transportation. The advantages to fluidisation technology are in reduced capital cost, reduced operating costs and in the environmental benefits of using full plant tailings over classified tailings or alluvial aggregates. Another major advantage is in the ability of this technology to be retrofitted to existing hydraulic backfill plants to further reduce capital cost. This paper details the development of the new technology as well as the associated cost savings over other technologies. It will also look at the research and development of unique components that make this technology work.

Jan 1, 1998

The author reviews design evaluation theory and existing optinustion tools and then describes how these have guided recent developments in Whittle Programming's strategic mine design package: Four-X. A new package - Reserve Estimator is also d

Jan 1, 1998

By Charles "Chick" Rodgers, Anthony Sarion

"With declining feed grade and increased production targets, it became necessary to upgrade Key Lake's eight stage counter current decantation (CCD) circuit. Following laboratory trials, mill operations recognized that dilution of the feed slurry and buffering of the feed density variations would improve thickener throughput. Plant testing resulted in the installation of Outokumpu's Supaflo ""Floe-Miser"" system. The circuit's flowsheet, instrumentation and control strategy were also upgraded along with the thickener feedwell modifications. The paper will also discuss these modifications and the implementation of the current control strategy.IntroductionCameco Corporation's Key Lake operation is the largest single uranium producer in the world. Current production is fourteen million pounds of uranium oxide (U 308) per year. It is owned 2/3 by Cameco and 1/3 by Uranerz Exploration and Mining with Cameco as the operator.The mine is 570 kilometres north of Saskatoon on the southern edge of the Athabasca basin. Access to the mine is by an all-weather road and a private airstrip.Process DescriptionThe Key Lake milling process consists of five individual plants: crushing and grinding; leaching and counter current decantation (CCD); solvent extraction; yellowcake precipitation and ammonium sulphate crystallization; and bulk neutralization (Figure 1 -Simplified Mill Flowsheet). A detailed mill flowsheet can be found in the appendix."

Jan 1, 1998

"Mechanical alloying (MA) synthesizing technology and thennohydrogen processing (THP) were utilized to produce nanocrystalline Ti-MMC's reinforced by TiB intermetallic compound by using TiH2-B powder mixtures. Powders MA'ed up to 8 hours were examined by X-ray diffraction and SEM study. All MA'ed powders afterwards were HIP'ed at 700, 800 and 950EC for 1 hour. Detailed XRD, SEM and TEM study of the samples were carried out to determine the structure and micrography of the Ti-TiB MMC material processed by MA+THP approach followed by HIP'ing at high temperatures.IntroductionThe fiber reinforced titanium base composites [1,2] which possess a great resistance to high temperature have been investigated. In these studies fibers of C and SiC were used as reinforcing materials. However, these fibers react with Ti-matrix at elevated temperature resulting in product formation at the interface between the matrix and the fiber. Because of the chemical reactions, strength of the product MMC material diminishes.In conventional techniques of whisker reinforced composite material production, the mixtures of matrix metal powders and dispersed fibers are consolidated by hot pressing, HIP and/or hot extrusion. These techniques, however, have some shortcomings. Hard and brittle fibers could be broken during mixing cycle of the processing. Consolidation techniques could also be the cause for fiber breakdown. Attaining of the uniform dispersion of fibers into the metal matrix is not an easy process. The chemical reactions at elevated temperature exposures in the interface between the matrix material and fiber reinforcement cause product formations leading to poor mechanical properties."

Jan 1, 1998

By Rich Perry

HARRY HINDS: Our second speaker today is Rich Perry. Rich is the manager of leach and dewatering at Newmont Gold Company's Carlin operations. He has been the operator of Newmont's refractory leach development program for the past three years. Prior to joining Newmont in 1994, he was plant superintendent at the Big Springs and Jerritt Canyon Roasting Mills for Independence Mining Company. He graduated from the University of Nevada's Mackay School of Mines, and has lived with his wife and three children in Elko, Nevada, for the past 12 years. Please welcome Rich as he presents "New Facility Design Engineering: On-Site Versus Engineering Companies' Offices." RICH PERRY: Newmont Gold Company has been mining and processing gold ore at its Carlin, Nevada, operations since 1965. Processing is done using oxide milling, heap leaching, and whole ore roasting methods. Newmont began development of refractory leach processing technology at its research and development facility in 1988. The R&D staff focused on developing processing methods for low-grade refractory gold resources at Carlin that could not be economically processed by refractory milling methods. The term refractory ore refers to those ores that contain quantities of sulfides and/or organic carbon that result in low recoveries using conventional cyanide leaching. The R&D staff developed two potential processes deemed worthy of further testing: heap biooxidation to liberate gold occluded by sulfides and ammonium thiosulfate leaching for gold recovery from carbonaceous preg-robbing ores. These were piloted in small heaps by the staff of the R&D and Carlin metallurgical labs from 1990 through 1994. By 1994, Newmont's R&D and metallurgical staffs had unlocked the chemistry and kinetics of the two processes, and it was decided that the operations group would be brought in to begin development of a commercial plant. A project manager at Newmont's Denver office was assigned to the project. Scale-up issues such as biooxidation leach pad design; on/off heap heights; handling of various ore types during stacking and reclaiming; operating costs; and environmental, health, and hygiene concerns using a new process chemistry remained unanswered.

Jan 1, 1998

Editor's note: Biographical information about Ihor Kunasz, president, Newmont Uzbekistan, can be found in the February 1998 issue of ME, page 94 and in the May 1996 issue, page 92. Your personal assessment of the minerals business. Gosh! When I think about what has happened to the minerals industry over the past 27 years that I have been a member of SME! There have been fundamental structural changes in the industry. And I think that SME has been quite successful in coping with these changes as well. There has been a reorientation in how the minerals industry does business. It used to be called rationalization. Today we call it reengineering. In addition, the minerals industry has become more complex and more global. Shareholders have become more vocal and demanding in the management of the business, asking for protection of their shareholders' value. In the 1980s, a fundamental change was precipitated by a merger and acquisition fever in all industries, including the minerals industry. Raiders such as T. Boone Pickens put enormous demands on companies that, in turn, had to spend substantial management time to fend off the raiders. This resulted in a major restructuring of the mining houses. Today, for example, Anaconda, Kennecott and Amax are only historical names.

Jan 1, 1998

By P. Lostritto, G. E. Agar, G. Labonte, M. Cherevaty

"A locked cycle flotation test was done on a sample from the ovoid portion of the Voisey 's Bay copper-nickel sulphide ore. The chemical conditions for this test were generated by prior independent testing. In this test work the time in each of the five separation stages was optimized prior to executing the locked cycle test. A numerical simulation of the continuous circuit material balance was done prior to the locked cycle test. The test results were not fully satisfactory because the flotation of pyrrhotite in the bulk rougher and cleaner stages was not consistent. The preliminary indication was that the samples had oxidized to varying degrees during storage.INTRODUCTIONINCO has performed batch laboratory flotation testing on ore from Voisey's Bay which is a mixture of chalcopyrite, pentlandite and pyrrhotite. Earlier, Lakefield Research was contracted by Diamond Field Resources to test the ""flotability"" of the ore, which included a pilot plant trial. INCO's J. Roy Gordon Research Laboratory has repeated many of the batch tests that Lakefield did to verify their results. Based on their own work, INCO has modified the circuit proposed by Lakefield Research. The modified circuit is based on batch test work, but no locked cycle test (LCT) was done. It is believed that this circuit will produce a copper concentrate at 29-30% copper and a primary nickel concentrate at 15-20% with recoveries of 80% or above.For several years the University of Toronto has been working with INCO to provide ""hands on"" experience for undergraduate students as an Industrial Research Project (IRP). This year, the objective for IRP was to optimize the time for each of the five separation stages for the Voisey's Bay ore then to numerically and experimentally simulate the material balance for a continuous circuit."

Jan 1, 1998

By Harry L. Siebert

Pre-splitting was substituted for line drilling to achieve stable rock slopes and reduce excavation beyond the pay line on a Connecticut highway project in 1962-63. Changes have occurred in developing rock slopes that were not foreseen by Alan Bauer and Jim Scott who in the early days understood the relationship of explosive energy to stable slopes. Cushion blasting as currently used produces slopes designed to blend or complement the natural landscape with slope holes detonated after the main body of holes. Pre-splitting is the opposite. The best results have been achieved by detonating the pre-split line of the holes first to allow readjustment of the slope plane fracture and a separate blast for the main body of loaded holes.

Jan 1, 1998

By T. Maruyama

Tamano Smelter of Hibi Kyodo Smelting Co., Ltd. has been operating with one Flash Furnace (FSFE) and three Peirce-Smith Converters since its start-up in 1972. Anode production capacity has increased from 101,000 to 263,000 t/y by the several expansion programs, while converter capacity has increased and stable operation has been established by several improvements as listed below. - Expanding the furnace body (length) - Development of two kinds of automatic scrap charging system for each converter. (Increasing the in-stack time and better control of the melt temperature) - Oxygen enrichment at slag blow and copper blow - Increasing the blowing rate This paper reports the details of these improvements.

Jan 1, 1998

By André. C. Louw

Diamond production from the reworked beach and river channel gravels along the west coasts of South Africa and Namibia is well known throughout the world, not only for the exceptional quality of the diamonds, but also for the sheer scope of the operations. To date an estimated 140 million carats have been produced from the resource worth some US$40 billion in today's money terms. It is therefore not surprising that it didn't take long before the attention turned towards the possible extension of this valuable diamond resource on similar submerged beaches in the adjacent territorial waters of South Africa and Namibia. This has proved to be a very successful move as the marine production in Namibia today constitutes 48% of that country's total diamond production. Although small scale recovery of diamonds from the sea commenced in the 1950's, the first large scale production came from the operations of the Texan entrepreneur, Sam Collins, in the 1960's. The De Beers Group, which took over Sam Collin's operations in 1969 had all the concession areas, as well as the financial and human resources to tackle the new mining frontier in the correct way by years of data gathering (ie diamond reserves and seafloor terrain studies) before commencing with large scale mining operations in the 1980's. Those who are familiar with the beach mining operations along the South African and Namibian west coasts will have appreciation for the daunting task of surgically removing the payable portion of diamond deposits from the non-payable material on the one hand, and the complex uneven fractured and gullied bed-rock floor of the deposits on the other hand. Not to mention the additional complexities of large boulders and hard calcretised diamond gravel layers (conglomerate) which are sometimes associated with the deposits. It was a natural development that the sea diamond mining operations were approached with the known information of the land operations, attempting to duplicate land mining operations in the sea, but taking cognisance of the variations of the terrain in the different areas. For instance, we encounter the following variations, and combinations, off the Namibian Coast. ? Close inshore - holocene sand cover often masks large areas of potentially diamondiferous gravels. ? In midwater areas (40m - 100m)

Jan 1, 1998

By P Salmon, M Kennedy

Sun Metals Corporation Pty Ltd (SMC), a wholly owned subsidiary of Korea Zinc Co Ltd (KZC) is a company formed to develop, construct and operate a zinc refinery, 11 km south of Townsville in North Queensland. The project opportunity exists because of on-going consumption growth for refined zinc metal, technological, environmental and economic obsolescence of existing zinc processing plants, and a prolonged ædroughtÆ of new zinc processing capacity under construction. The Project will utilise proven technology developed by KZC at the Onsan refinery in Korea. The Townsville Refinery has been designed to be the most environmentally-friendly zinc refinery in the world, and in particular to resolve the issue of secure, long term treatment of the ironbearing content of the zinc raw materials.

Jan 1, 1998

Jan 1, 1998

By B. G. White

Traditional interpretations of vein ore deposits in the Coeur d' Alene Mining District, such as the view that these deposits formed in a transcurrent tectonic regime during the Precambrian, are being supplanted by the view that the deposits (1) formed in low-grade metamorphic shear zones similar to those that host an important type of gold deposit, (2) display features, such as wall rock carbonate zoning and vein zoning, that are common to ore deposits elsewhere, and (3) are probably Mesozoic and possibly related to emplacement of the Idaho batholith. In recent years, new interpretations have led to major ore discoveries that are likely to extend the life of the district for decades.

Jan 1, 1998

By D. Kaja

The Symons Cone Crusher was invented by Edgar B. Symons in 1923. It was quickly accepted as a superior secondary and tertiary crusher. Nordberg manufactured crushers for the Symons Brothers Co. and in 1928 acquired the Symons Cone business. Since then, the Symons cone has become the standard of the Mining Industry. This is due to the basic rugged design and Nordberg's continued efforts to modernize and upgrade the crusher design over the years. In 1930, the Heavy Duty model was introduced with a 225 kW (300 HP) rating. Then in 1931 the Short Head version was developed to handle finer crushing applications. In 1950, the 7 Ft. XHD design was produced which provided higher crushing force capabilities for harder ores and for smaller product size requirements. Finally, in 1978, the 7 Ft Super Heavy Duty design was created to expand the power rating to 500 HP and to further increase the crushing force limits. The first 7 Ft. Super Heavy Duty crushers were delivered to Bougainville Copper Ltd. in 1978 for the production of primary ball mill feed in a three stage crushing plant with the third stage in closed circuit. The product size was 80% minus 6.35 mm (1/4 in).

Jan 1, 1998

By L. Alan Weakly

The Powder River Basin is the largest strippable reserve of compliant coal in the United States. It is the mother lode, for this Basin is currently supplying 25 percent of the coal produced in the US annually. This paper updates what has happened in the Basin since 1993 in terms of increased production, higher productivity, changes in mine ownership, safety statistics, new equipment, latest coal technologies, and electrical deregulation ramifications.

Jan 1, 1998

By David Miller

Longwall gateroad support can be supplied by a variety of methods. The system of support also needs to be flexible as conditions change. This is especially true in the complex geological conditions of the west Kentucky # 13 seam. Methods of gateroad support used in this seam will be presented along with the successes and failures of the systems as conditions changed Lodestar Energy's gateroad support progression through the seven longwall panels retreated to date will provide an insight into planning for future panels

Jan 1, 1998

By G. B. Glass

In 1996, 92.5% or 233 Mt (257.4 million st) of coal produced in Wyoming came from the Wyodak coal zone in the eastern Powder River Coal Field. While the mined portions of the zone consist of one to three beds of coal with an aggregate thickness between 15 and 33.5 m (50 and 110 ft), the thickest expression is 61 m (200 ft). The delivered coal from this zone averages 0.33% sulfur, 5.12% ash, and 19.98 MJ/kg (8,590 Btu/lb). This coal zone occurs at or near the top of the Paleocene Fort Union Formation, which is overlain by the Eocene Wasatch Formation. There is also production from two coal beds in the lower portion of the Wasatch at the southern end of the basin. Production of coalbed methane derived from the Wyodak coal zone is currently an estimated 10.2 billion cu ft a year. This production is occurring just west and downdip from the coal mines and is increasing each year.

Jan 1, 1998

By Karen Tempel

Newmont's Lone Tree Mine is located 30, miles east of Winnemucca in Humboldt County, Nevada. Starting in February 1994 a pressure oxidation circuit was commissioned to treat refractory gold ores. Gold is leached and recovered from the oxidized slurry in a six-stage carbon-in-leach (CIL) circuit. Lone Tree has been able to maintain tighter control' of cyanide addition and reduce cyanide consumption its CIL circuit through the installation of Degussa's Cyplus® CCS Cyanide Control System in the spring of 2000. 'The Cyplus® CCS, along with additional inputs' from plant sensors, has allowed tor a more efficient and effective control strategy over the manual control method used ,in the past. This paper documents the key aspects of the Cyplus® CCS installation; the development of the control strategy, and the benefits achieved from enhanced control.

Jan 1, 1998

By E. Stolarski

The circulating fluid bed (CFB) technology can proudly point to its history of more than a quarter of a century of commercial operations. Over 80 CFB units operate in aluminum calcining, coal combustion and gold roasting. This paper describes the invention of the circulating fluid bed and chronicles its development and evolution from calcining through coal combustion to gold roasting. It presents performance data of Lurgi's CFB units in operation and highlights the six gold roasting plants currently operating throughout the world.

Jan 1, 1998