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By S. Foged

Umicore and MWH jointly demonstrated that mechanical dewatering of goethite and neutralised tailings significantly increased the life of a 30 ha tailings pond and improved the operation of the pond. Umicore operates one of its zinc production plants in Balen, Belgium. As part of its production process, an excess of neutralised and goethite¬containing tailings is generated. These have historically been stored inside large lined ponds. As the storage area of the current goethite pond was nearing its capacity, Umicore studied the potential for an extension to the existing embankment. However, this extension would face intense regulatory scrutiny, because the environmental and safety impacts were considered important. Together with Umicore, MWH suggested and investigated an alternative treatment approach consisting of mechanical dewatering prior to storage. A feasibility study was prepared where wet storage was compared to dry storage. Differences in safety risks, environmental impacts and economic costs were outlined. The study demonstrated that the life of the tailings pond could be increased from 6 to 22 years, seriously reducing the environmental impacts and safety risks at no significantly higher cost than would have been incurred with the continued operation of the existing pond. The results of the study are presented in this paper.

Jan 1, 2006

By E. W. Greig

This paper is an account of exploration for bauxite in the Amazon Basin, Brazil, and particularly of the discovery, exploration and development by Alcan of the Trombetas deposit so a general account of the Trombetas Project has already been published in E/MJ (Anon. 1975) to which the reader is referred for details on owner-ship, infrastructure and construction as well as the proposal for mining and treating the bauxite. It is impossible to consider the Trombetas deposits in isolation. A regional account of bauxite in and around the Guyana Shield and the northern portion of the Brazilian Shield is included and it is suggested that these deposits all formed during Tertiary time under similar conditions.

Jan 1, 1977

By Hannu Johto

Boliden Harjavalta has operated a flash smelter for nickel sulphide concentrates in Finland since late 1959. The original nickel flash smelting process was modified in 1995 to a novel nickel matte smelting (DON) with semi-low iron where the batchwise operated converting became obsolete. Since that, the process has been applied to multiple chemically variable nickel sulphide concentrates with high environmental performance. In this paper, the status of the current smelter operations is described together with the recent modernizations of the nickel flash smelting furnace and the slag cleaning furnaces.

By M. H. Thomas

Ante la baja perspectiva en el aumento del petróleo, se replanteó el uso del combustible carbonáceo donde los beneficios económicos para cada usuario serán importantes, debido al costo considerablemente menor del carbón en comparación con los costos del petróleo. En ese sentido, el presente texto señala los factores económicos, costo de combustible, costo de capital para la central, factores políticos, la planta de combustión y manejo del carbón, generación de energía y las industrias del proceso para la revaloración de este combustible.

Mar 1, 1984

By Xiao-hui Fan, Xu-ling Chen, Zhi-yuan Yu1, Guanghui Li, Min Gan, Yun-song Huang, Tao Jiang

Compared with the traditional de-NOx processes by cleaning the waste gas, a new approach for reducing the formation of NOx during sintering process is proposed. Since more than 90vol% of NOx comes from the fuel combustion, the influence of sintering coke breeze pretreated by CO(NH2)2 additive on the NOx emission is researched. As adding CO(NH2)2, the reduction agents (NHi) are generated during the pyrolysis of CO(NH2)2, which reinforce the NOx reduction, And the appropriate content of CO(NH2)2 is 1.0 mass% of coke breeze.

Jan 1, 2015

By B. R. Benner

Progressive improvements in crusher design, screening efficiency, and operating experience along with the downsizing of many taconite operations has resulted in the abilitv of some crushing plants to produce a substantially finer product. This finer product opens the possibility of replacing the rods in the rod mill with balls as is the current practice at Sydvaranger, Norway. If this replacement could be accomplished substantial savings associated with metal wear and the elimination of rod charging may be realized. The purpose of this study was to compare the performance of a mill charged with rods with the performance of the same mill charged with balls at the pilot scale. The first objective was to establish whether we could achieve the same throughput rate at the same mesh-of-grind in a mill in which the rod media has been replaced by balls. The second point was to determine whether the ball media would create a significant tramp oversize problem.

Jan 1, 1990

By Just GD, Gillies ADS

There is an increasing need for reliable and comparable coal resource data and it is necessary to standardize the traditional classification procedures by quantifying the three basic evaluation criteria of economic feasibility, geologic assurance and recovery. For well documented deposits, geostatistical methods can consider- ably improve classification quality. A geostatistically based algorithm for classifying coal resources within the current Queensland and New South Wales codes has been developed. Application of the method in classifying resources from a number of seams exhibiting different structural characteristics is assessed. The method is found to give classification results which closely reflect the error associated with an estimate of resource quantities based on current sampling densi- ties. It requires a careful geostatistical analysis with emphasis on geological awareness. Resource category restrictions must be arbi- trarily assigned and remain constant for all deposits being compared. Engineering judgement is needed and interpretation may be required with isolated and peripheral blocks.

Jan 1, 1987

By S Gillies, H W. Wu

A study has been undertaken into mine ventilation systems currently in use within Australian modern coal longwall (LW) extraction mines. It reviews systems and discusses evolving changes being adopted to address the more complex challenges. There is a strong move to longer panels, wider faces, greater extraction heights, increased production rates, more efficient ventilation and decreased personnel. Each of these changes is motivated by improvement in productivity and generally leads to cost reduction. In addition, mine workings are moving deeper, which results in increased ventilation control issues such as higher total and respirable dust levels, greater seam gas contents in parallel with lower in situ permeabilities, spontaneous combustion and heat management issues. A comprehensive database of Australian LW ventilation practice is analysed. Currently there are a variety of LW panel ventilation circuits used in Australian underground coal mines due to various combinations of seam characteristics, gas emission rates, spontaneous combustion, geological features and surface constraints. The main issues usually addressed in the designing and planning of ventilation circuits for LW panels are airway velocity, gas concentrations, LW cutting methods (eg Bi-di, Uni-di or half web), ventilation of control devices, pressure differentials and leakage paths and understanding gas concentrations across the length and width of the goaf. If the ventilation circuit can manage the applied contaminant load (gases, heat and dust) at an acceptable cost and circuit duty, then supplementary controls, such as gas drainage, refrigeration and dust sprays and scrubbers, may not be required. CITATION:Gillies, S and Wu, H W, 2013. Review of Australian longwall panel ventilation practices, in Proceedings The Australian Mine Ventilation Conference , pp 87-94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By Robert R. French

Commercial grade gypsum beds up to 16 feet thick is present in southwestern Indiana. The major deposits are found at a depth of 350 feet to more than 500 feet below the surface. The ore body averages about 75 to 95 percent gypsum. Two companies are currently exploiting a deposit which underlies an area of several square miles near Shoals, in Martin County. Another deposit has been located in southwestern Owen County but has not been developed. The Indiana Geological Survey is currently drilling in Greene County and is considering further exploratory work in Perry end Dubois Counties.

Jan 1, 1965

Controlled Source Audio Magnetotelluric (CSAMT) surveys were carried out by Glass Earth (New Zealand) Limited (Glass Earth) in 2006 - 2007 to investigate epithermal gold targets in the central North Island of New Zealand. The surveys were conducted using a Zonge GDP 32 8-channels receiver and a Zonge XMT 32 transmitter powered by a 16 KW generator. The electric field dipole was maintained at 20 m length (five dipoles per 100 m spread) and the frequency ranged from 4 KHz to 4 Hz. Only scalar (TM mode) signals were recorded, using one magnetic coil per spread. The transmitter bipoles were 1 - 4 km in length and located about 5 to 10 km from each survey area.   Sixteen individual target areas were surveyed by June 2007. The CSAMT survey lines (100 - 400 m spacing) were determined mainly on results from previous ultra-detailed airborne magnetic and gravity surveys conducted by Glass Earth in 2005. The data from each CSAMT line was carefully examined to remove any spurious signals and processed using Zonge SCS2D software, which can produce smooth 2D resistivity inversions of the field data. The results were presented as resistivity sections and maps to help the identification of exploratory drilling targets, mainly from the existence of subsurface high resistivity zones (resistors) that can be interpreted as caused by silicification associated with epithermal mineralization.   An example of processing and interpretation of the CSAMT data is presented in this paper on results from Glass EarthÆs Tahunaatara target, where CSAMT surveys have identified zones of epithermal mineralization confirmed by exploratory drilling.

Jan 1, 2007

By H. H. Schrenk

One phase of Bureau of Mines work in health and safety is promotion of the use of safe, satisfactory, and reliable respiratory protective devices. To insure that such devices will be. available, the Bureau has established schedules of minimum requirements for oxygen breathing apparatus,3/ gas masks,/ supplied-air respirators (hose masks, air-line, respirators, and abrasive blasting helmets, hoods, or masks),5/ and dispersoid (dust, fume, and mist)

Jan 1, 1943

By J. D. Bateman

DURING the summer of 1942 several chromite deposits were discovered in the Lac du Bonnet district about eighty miles northeast of Winnipeg. The deposits are confined to the Bird River complex, a folded composite sill of basic and ultrabasic igneous rocks of early Precambrian age that lies to the north of Bird river (1). The outcrop of the sill represents the trace of an easterly plunging anticline, the south limb extending from the northeast bay of Lac du Bonnet eastward to Bird lake, and the other limb, 6 to 12 miles north, lying between Maskwa river and Euclid lake. The south limb of the sill is 20 miles long, and the northern counterpart 15 miles; but its continuity is interrupted by faulting and by the intrusion of younger granite, so that the total length of outcrop of both limbs does not likely exceed 25 miles. The sill is intrusive into early Precambrian greenstones and associated sedimentary rocks. The chromite discoveries have been made at several localities on both limbs of the sill, and in each case at the same geological horizon. The sill comprises an upper layer of hornblende gabbro and a lower layer of serpentinized peridotite, and altogether is from 500 to 3,500 feet thick. The chromite zone is within and near the top of the peridotite layer, and thus about midway of the sill, both of the limbs of which stand nearly vertical. This geological relationship was established early in the exploration of the initial discoveries and served as the basis for successful predictions of later discoveries. The chromite zone probably persists throughout the length of the sill, but its width and chromite content are not everywhere the same. The initial exploration along both limbs of the sill has shown a combined total length of about 12,000 feet of chromite ore varying in width from 6 to 12 feet. In many places the overburden is thick and obscures the continuity of the chromite zone; but as investigation proceeds the known deposits will be extended and new ones will be found. Thus, although a total length of 12,000 feet of ore has been investigated up to the present time, there is an indicated length of approximately 31,000 feet along which the ore is more than 4 to 5 feet wide. This estimate is based on geological considerations and represents a total tonnage in the order of 15,000 tons per vertical foot of depth.

Jan 1, 1943

By G. L. Gates

The Bureau of Mines in cooperation with the City of Long Beach) Calif.) studied some physical factors effecting the deposition of barium sulfate scale in oil-well rotary pumps. Freshly formed barium sulfate was obtained by combining sulfate in sea water with barium from a barium chloride solution. The rate of scale deposition was measured quantitatively by weighing the pump impellers and diffusers. The results of the tests showed that coating the impellers with plastic significantly reduced the rate of barium sulfate deposition.

Jan 1, 1967

Edward A. UehlinG, New York City (communication to the Secretary*):—Mr. Baker's paper is one that brings up a subject of great importance, and if full statistics could be collectecl of the number of furnace-linings ruined by reason of bad distribution by skip-hoists, it would be found an astonishing array. Unfortunately a universal remedy has not yet been found. The fact that Mr. Baker has apparently succeeded in overcoming the trouble at Sydney, is no guarantee that the same remedy applied at another plant, where very different or even slightly different conditions prevail, mould cure the trouble. That it requires but a slight continuous difference of penetrability in the column of the descending stock of one section, over another, to produce channeling, is clearly demonstrated by Mr. Baker's experiments, by which he reversed the channeling from front to rear instead of remedying the trouble. Every change in the physical make-up of the charge necessarily requires a specific adjustment; even supposing this feasible, the regular working of the furnace is by no means assured, because with the high pressures now customary, the tendency of the ascending gases to plow their way through in a direct course, prevails, and having once opened up a passage, they will persist and cause trouble. Homogeneous filling-, hard driving and regularity of working are incompatible. The higher the furnace, the greater the

Jan 1, 1905

By Pedro Damas Resende

As propriedades físicas e mecânicas de ligas NiTi são fortemente influenciadas pelo seu histórico termomecânico. Este trabalho visa avaliar a influência de uma deformação preliminar (chegando ao escorregamento da martensita) aliada ao recozimento de uma liga NiTi sobre suas propriedades através de DSC (Calorimetria Diferencial Exploratória), ensaios de tração até a ruptura e difração de raios X (DRX). Observou-se um aumento da histerese térmica como resultados dos tratamentos, e as transformações martensíticas passaram a ocorrer com formação de fase intermediária (fase R) para os grupos recozidos. Os valores de tensões de início e fim de patamar do grupo tratado diminuíram em relação ao grupo do material como recebido.

Aug 16, 2017

By J. P. Carson

THE Croton water-shed furnishes the source and storage of watersupply to both the old and the new aqueduct. The Croton river rises in the southern part of Dutchess county, about 68 miles from the lower end of New York city. Its three main branches, called the East, Middle and West branches, flow southward across Putnam county, joining, near its southern boundary, to form the Croton, which continues thence in a general southwest direction across Westchester county to the Hudson river at Croton Point, about 35 miles north of the city. The water-shed above the proposed site of the Quaker Bridge dam extends about 33 miles north and south, with an average width of 11 miles, making in all about 362 square miles, from which, by complete storage, an average daily supply of 250,000,000 gallons may be collected—sufficient for the needs of the city, probably, for the next fifteen years. The water-shed above the Croton dam is 23 square miles smaller, and furnishes the present daily supply of 100,000,000 gallons. By referring to the map it will be seen that the shortest approximately straight line between the proposed site of Quaker Bridge

Jan 1, 1891

By Barry D. Simmons

Abstract -A well-defined approach is essential to ensure the long-term success of a regional exploration program. Teck's approach in eastern Canada is designed to fulfill corporate objectives while recognizing certain unique parameters for exploration in the area. The elements of this approach include clearly defined objectives, technical considerations and personnel policies, all of which are equally important. The goal is a significant discovery before the mid-1990s and the company is confident that this target will be achieved.

Jan 1, 1992

By Felipe Darabas Rzatki

Polyether ether ketone (PEEK) is a high performance thermoplastic often selected for high temperature tribological applications under chemically aggressive environments. The present work evaluate the tribological behavior of a high performance PEEK composite under ambient and high temperature (30 and 80°C, respectively). The atmosphere was also varied (air or tetrafluorethane). An AMTI tribometer equipped with a hermetic chamber and a heating system was used to carry out sliding tests of PEEK cylinders on 304 stainless steel polished discs (Sq < 10 nm) with reciprocating movement and 175 N normal force. Surfaces roughness analyses were performed with a white light interferometer. As expected, there was a strong influence of temperature on the tribological behavior of the samples tested in ambient atmosphere (25% decrease in friction coefficient associated with a 100% increase in wear rate). On the other hand, samples tested in tetrafluorethane atmosphere showed no significant friction temperature dependence.

Jul 31, 2018

By M Fitzgerald

Fimiston Open Pit is operated by Kalgoorlie Consolidated Gold Mines (KCGM) as a joint venture between Barrick Gold and Newmont Mining. Over 110 years of underground mining resulted in the development of nearly 3500 km of underground workings including backfilled and open stopes up to half a million tonnes in size. These voids significantly complicate blasting processes at KCGM, influencing blast movement direction and magnitude. Blast movement monitoring to improve mine reconciliations was identified as an improvement project in the business plan for the geology team in 2008. Following successful trials in 2008 to 2009, blast monitoring and translation of ore blocks were implemented as a permanent grade control program from late 2009 and is now part of the Management Operating System (MOS) of the mine. This paper presents a summary of results from the Blast Movement Monitoring (BMM&#174;) data collected to date. Ore blocks at KCGM are translated primarily using BMM&#174; data. This data is obtained from the BMM&#174; system which measures the movement of a radio transmitter installed in a blast pattern from a preblast position to a post-blast position. The application of the data collected by the BMM&#174; tends to be both mine site and blast specific. At KCGM, an average distance obtained from the BMM&#174; data within a given shot is the primary method used for translation. In the case that BMM&#174; data is unavailable, a theoretical movement vector established from Orica Shotplus with distances gained from the historical BMM&#174; database is used. Data is presented in an ore loss and dilution exercise for a bench undertaken at KCGM to understand the potential effects on reconciliations. Improvements that have flowed from implementing blast monitoring include improved reconciliations when combined with other grade control improvement projects. The increase in liaison between the geology and blast personnel at KCGM has been a significant improvement gained from the implementation of the blast monitoring program. This has allowed a better understanding of blast movement and the effects on ore dilution and ore loss by the mine geology team. In addition, the discussion of blasting tie-in plans between geology and blasting personnel has been improved which leads to more favourable blasting practices that take ore movement into account.

Aug 22, 2011

By Luis Armando Espitia

AISI 410 martensitic stainless steel specimens were low temperature plasma nitrided at 400°C in a mixture of 75%N2:25%H2, during 20 h. Active screen technic was used to avoid any edge effect The nitrided case is composed of expanded martensite (a’N) and e-Fe3N iron nitride, whilst chromium nitride precipitation was avoided. Surface hardness reached 1275 HV0.01. The transverse microhardness profile shows a gentle hardness gradient with a NHT nitrided case depth of 28 µm. Nanoindentation tests were carried out in order to assess the hardness (H), the Young modulus (E), the H/E and H3/E2 ratios and the elastic recovery (We) of both nitrided and non-nitrided specimens. The cavitation erosion mass losses were measured as a function of exposure time. The results showed a decrease of 27 times of the mass loss compared to the non-nitride specimens. Wear rate decreased from 2.56 mg/h for the non-nitrided condition to 0.085 mg/h after nitriding. The increment in the elastic recovery and the higher hardness values are responsible for the greater cavitation erosion resistance exhibited by the expanded martensite. Such results showed that low temperature plasma nitriding and the formation of expanded martensite are effective to increase cavitation erosion resistance of AISI 410 stainless steel.

Jul 31, 2018