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By Lifeng Li, Jhon Silva-Castro

"Signature Hole Technique is one method to assess the vibration waveform of a production blast.Methematically, it is the convolution between a prior measured waveform of a single blast hole (signature) and a given time delay sequence (comb function). Being an advantage, the inverse operation of convolution, known as deconvolution, can be used to estimate the signature."

Jan 1, 2017

By Karl Fetters, John Chipman

The relationship between the composition of the slag and that of the underlying metal during the refining of a heat of liquid steel may best be studied in the light of the two broad physicochemical concepts of equilibrium and reaction rate. Actual steel-making processes, typified by basic open-hearth practice, involve such complexities of operating variables that it is impossible to distinguish with any degree of certainty between the general limiting conditions imposed by chemical equilibrium and the effects associated with rates of diffusion or of chemical reaction. Further advances in the physical chemistry of steelmaking will depend upon our ability to distinguish clearly between these two kinds of effects, and the experimental work that must be done falls naturally into two classifications. The first is the study of chemical equilibrium that cannot be carried out with assurance under operating conditions but must be done in the laboratory. The second is the -subject of rates of reaction and diffusion and the mechanism of the process as a whole, which can best be studied under operating conditions. The latter is not entirely independent of the former, since its interpretation often requires a knowledge of the equilibrium state. It is the purpose of this and of several papers that will follow to present the results of labora- tory investigations of equilibria involving liquid steel and slag. Open-hearth slag is a complex mixture containing at least eight major components and perhaps twice as many whose influence may be classified as probably minor. It is not surprising that progress toward a complete understanding of such a material at high temperatures has been slow. Attempts to apply the established principles of physical chemistry to the behavior of the individual components of this mixture have been beset by an almost complete lack of data on its chemical properties in the liquid state. This has necessitated the adoption of various methods of approximation based upon such assumptions as, for example, that for a given component the ratio of its mol fraction in the slag to that in the metal is a constant, or that the molecular composition of the liquid slag is the same as its crystalline constitution after solidification. From the thermo-dynamic viewpoint, such assumptions are merely useful dodges, which enable one to hazard a guess as to the magnitude of the more fundamental quantities, the chemical potentials and activities of the components of slag. The problem of determining the activity of each substance in an eight-component svstem seems too complex to be undertaken without the aid of generalizations derived from experimental data on similar systems containing a smaller number of components. Accordingly, it was planned in the present investigation to study the equilibrium of molten iron with the simplest

Jan 1, 1941

By Karl Fetters, John Chipman

The relationship between the composition of the slag and that of the underlying metal during the refining of a heat of liquid steel may best be studied in the light of the two broad physicochemical concepts of equilibrium and reaction rate. Actual steel-making processes, typified by basic open-hearth practice, involve such complexities of operating variables that it is impossible to distinguish with any degree of certainty between the general limiting conditions imposed by chemical equilibrium and the effects associated with rates of diffusion or of chemical reaction. Further advances in the physical chemistry of steelmaking will depend upon our ability to distinguish clearly between these two kinds of effects, and the experimental work that must be done falls naturally into two classifications. The first is the study of chemical equilibrium that cannot be carried out with assurance under operating conditions but must be done in the laboratory. The second is the -subject of rates of reaction and diffusion and the mechanism of the process as a whole, which can best be studied under operating conditions. The latter is not entirely independent of the former, since its interpretation often requires a knowledge of the equilibrium state. It is the purpose of this and of several papers that will follow to present the results of labora- tory investigations of equilibria involving liquid steel and slag. Open-hearth slag is a complex mixture containing at least eight major components and perhaps twice as many whose influence may be classified as probably minor. It is not surprising that progress toward a complete understanding of such a material at high temperatures has been slow. Attempts to apply the established principles of physical chemistry to the behavior of the individual components of this mixture have been beset by an almost complete lack of data on its chemical properties in the liquid state. This has necessitated the adoption of various methods of approximation based upon such assumptions as, for example, that for a given component the ratio of its mol fraction in the slag to that in the metal is a constant, or that the molecular composition of the liquid slag is the same as its crystalline constitution after solidification. From the thermo-dynamic viewpoint, such assumptions are merely useful dodges, which enable one to hazard a guess as to the magnitude of the more fundamental quantities, the chemical potentials and activities of the components of slag. The problem of determining the activity of each substance in an eight-component svstem seems too complex to be undertaken without the aid of generalizations derived from experimental data on similar systems containing a smaller number of components. Accordingly, it was planned in the present investigation to study the equilibrium of molten iron with the simplest

Jan 1, 1941

By Tad S. Golosinski, R. Larry Grayson

Online education is not new. During the last decade, it has reached the stage where many universities offer a variety of courses, degrees and programs without any associated residency requirements. The most successful of the online universities, University of Phoenix, offers hundreds of accredited programs for close to 100,000 students throughout the world (www.phoenix.edu). Online education is considered to be a valid equivalent to traditional, classroom-based education. It is best suited to the needs of mature students with full-time jobs and a desire to deepen their knowledge. While most of the e-business has experienced severe setbacks during the last two years, e-education shows no signs of slowing down. On the contrary, the number of students and institutions offering online education keeps growing. The value of e-education associated expenditures was expected to reach $300 billion in 2001 (Sanoff,2001), making it a serious and mature industry.

Jan 1, 2002

By T. W. Guy

THE increased moisture due to water¬spraying for coal dust control is of interest even for mines from which the coal is to be wet-washed before screening, because in many cases wet coal dust materially decreases the loading efficiency of men an equipment at the faces. It also causes serious increase in the normal wear and deterioration of all equipment with which it comes in contact. It is important to the consumer if it increases his as-receive moisture. No attempt will be made in this paper t cover the entire subject of water-spraying of coal for dust control. It will be confine to discussion and data on (r) percentages c dust in bituminous coals, (2) moisture increases due to spraying for dust control in mines or plants by methods which have proven satisfactory for periods of one to five or more years, and (3) a few suggestions for research. SIZE AND PERCENTAGE OF COAL DUST The U. S. Bureau of Mines1 classifies a coal dust all bituminous coal passing 20-mesh sieve (0.0328 in. square opening; The percentage of such dust to be found is ROM coal, of course, varies widely wit. the characteristics of the seam, and with the methods used in the mining and in the preparation of the coal. ROM screen analyses of 12 U. S. coals selected at random from personal files given in Table I show: A few other screen analyses examined indicating 40 pct or more of 2o-mesh X o dust in 3/8 in. X o-sizes were not included because of uncertainty that they were representative. The number of results in Table I is not sufficient to give a reliable estimate of the average, or of the range to be expected, but it indicates that in every case the coal dust is a relatively large percentage of the total ROM coal, and, of course, a progressively larger percentage of resultants as the larger sizes are separated for marketing.

Jan 1, 1948

Lower costs associated with hands-on training in donning and using a CSE ,self-contained self-rescuer (SCSR). Background In June 1987, the Mine Safety and Heath Administration (MSHA) issued an Emergency Temporary Standard (ETS) requiring that all persons entering underground coal mines must be given bands-on SCSR training. The ETS will shortly be replaced by a new standard requiring this hands-on training. Bureau of Mines research has shown that the most effective means of delivering this training is to have the trainee go through a six-step training procedure while in a kneeling position. Once the miner has looped the neckstrap over his or her head, he or she completes the donning sequence in this order: 1) activate oxygen; 2) insert mouthpiece; 3) put on nose clips; 4) put on goggles; 5) adjust neck and waist straps; and 6) replace miner's cap and prepare to move out. This procedure is repeated until the miner demonstrates that he or she is proficient at the task.

Jan 1, 1988

By E Widzyk-Capehart

The conventional ammonium nitrate fuel oil (ANFO) loader utilises a pneumatic system to control the flow of ANFO (via rotary actuator/ball valve) and air (via an auxiliary air valve). This system, though relatively simple and reliable, has several drawbacks with respect to ease of control and level of automation. In this paper, a radio frequency (RF) remote control for explosives charging is discussed. The system design incorporates electric solenoid valves to control the rotary actuator and the auxiliary air valve. All operations associated with explosives charging are selectable at the remote and are completed according to a modifiable time sequence. This allows the following charging sequence to be reduced to a single momentary application of the remote:removal of water from the hole prior to charging with ANFO; charging of the hole for a preset but adjustable period of time; and removal of the remaining ANFO from the ANFO hose. A specially developed remote switch allows the operator to maintain two-handed control of the ANFO hose whilst achieving full control of the charge-up process. Failsafe electronic architecture is incorporated into the systemÆs design to increase safety to the highest level. Should the RF remote control fail, a wired remote is included in the system to allow for the charging process to continue, albeit at a reduced level of control. The application of the RF remote control system in an underground explosives charging operation minimises and/or eliminates many problems associated with the use of the conventional charging system. These include: the wet-hole problem, trip and entanglement hazards, air embolism and the two-man loader control requirement. The developed remote control unit proved to be effective at removing water from wet holes leading to increased face advance per drilling operation. It proved to be economically feasible, allowed for an increase in systemÆs dependability and safety factor and for a truly one-man operation which resulted in reduced manpower.

Jan 1, 1999

By Pedro Henrique Teshima Shioga

Quando processos de engenharia de superfícies multifuncionais que combinam fases de propósito orientadas são aplicados a substratos moles, uma combinação de alta resistência ao desgaste, suporte de alta carga e baixos coeficientes de atrito podem ser obtidos. Neste estudo, os efeitos de diferentes camadas nitretadas no comportamento tribológico de revestimento Diamond-Like-Carbon (DLC) depositado sobre aço SAE 1040 são investigados. A nitretação foi conduzida sob diferentes temperaturas e misturas de gases para criar três camadas de nitretos distintas: duas camadas de compostos com predominância de fases e e ?’ e uma camada de difusão. Todas as superfícies foram então revestidas com DLC, depositado via Plasma-Enhanced-Chemical-Vapour-Deposition (PACVD). As fases de nitreto foram analisadas utilizando difração de raios-X e a topografia da superfície foi analisada por interferometria de luz branca e microscopia eletrônica de varredura. O comportamento tribológico foi investigado utilizando esfera e plano com movimento alternado com carregamento incremental até a falha do filme DLC. Os testes tribológicos indicaram que o melhor desempenho foi alcançado por uma específica combinação de dureza, rugosidade superficial e tipo de nitreto. A melhor capacidade de mancalização entre o revestimento DLC e o substrato mole foi alcançada quando a camada de nitretos constitui-se apenas de uma camada de difusão.

Aug 16, 2017

By Dale A. Sketchley

"Abstract - Large differences in gold content between rock fragments or small volumes of unbroken rock, commonly referred to as the nugget effect, are related to sample and subsample weights, crushing and pulverizing sizes, and density, shape and size distribution of gold grains. Gy’s sampling theory, which relates gold grain characteristics to sample weight, fragment size, and error, provides a method of estimating a sampling constant that quantifies deposit characteristics that contribute to the nugget effect.Sampling control tests provide methods for determining the sampling constant. Sampling control charts, comprising nomographs that relate sample weight, error and particle size, use the sampling constant to optimize sample weights and comminution sizes, and to minimize the variability introduced by incorrect or inadequate sampling and sub-sampling procedures. The sampling constant is useful in classifying ores into arbitrary categories according to expected sampling difficulties. Spatial variations in the sampling constant can be used to aid in defining ore types for modeling geological domains, which should have unique sampling protocols. Examples that illustrate the relationship between the sampling constant and expected sampling problems, and the spatial variation of the sampling constant, are given for various deposits. Case histories of sampling programs are presented.Quality control procedures consist of monitoring sample contamination amd accuracy and precision of analytical results. Accuracy, precision and contamination are monitored by including standards, duplicates and blanks into batches of samples being analyzed. Analytical results of standards and blanks are plotted on a batch-and-time basis with control lines at plus or minus two/three standard deviations as confidence limits of the accepted round-robin value. Examples are given that illustrate a laboratory system in statistical control and the various types of problems encountered when interpreting quality control data. These include sample transcription errors, degradation, contamination, sampling errors, detection limit problems, instrumental drift, lack of statistical control, laboratory bias, procedural problems and data tampering.Where bias is negligible, precision, as a function of concentration, can be obtained from duplicates using the Thompson-Howarth precision algorithm, which also allows calculation of the practical detection limit. Examples are given that illustrate variations in precision, with grain size, for different types of duplicates, as well as mineralogical changes and sampling errors."

Jan 1, 1998

By R. W. Charles

The Los Alamos National Laboratory, under the sponsorship of the U.S. Department of Energy; is involved with laboratory and field experiments to assist in development of the Hot Dry Rock concept of geothermal energy. The field program consists of experiments in which hot rock of low permeability is hydraulically fractured between two wellbores. Water is circulated from one well to the other through the fractured hot rock. Our field experiments are designed to test reservoir engineering parameters such as heat-extraction rates, water-loss rates, flow characteristics including impedance and buoyancy, seismic activity, and fluid chemistry. Laboratory experiments were designed to provide information on the mineral-water reactivity encountered during the field program. Two experimental circulation systems tested the rates of dissolution and alteration during dynamic flow. SOlubil ity of rock in agitated systems was studied. Moreover, pure minerals, samples of the granodiorite from the actual reservoir, and Tijeras Canyon granite have been reacted with distilled water and various solutions of NaCl, NaOH, and Na.CO.. The results of these experimental systems are compared to the observations made in field experiments done within the hot dry rock reservoir at a depth of approxi-mately 3 km where the initial rock temperature was 150 to 200°C.

Jan 1, 1981

By Dougherty. E. Y., S. W. Zoldok, John W. Cole

"INTRODUCTION During its wartime program of exploration for minerals essential to the national economy, the Bureau of Mines was instructed to investigate sources of raw materials used in the manufacture of iron and steel. As a part of this investigation, some work was done on the iron deposits on the Neutral and Aztec claims on Buckhorn Mountain Canogan County, Washington, which was designed chiefly to indicate the nature and behavior of the ore deposits below the surface exposures. Diamond drilling was started in June and completed in July 1945. Preliminary laboratory tests on iron, ore from Buckhorn Mountain were completed during the fall and winter of 1945. This report presents the data obtained from the investigation.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final re¬port. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests."

Apr 1, 1947

By M. J. Lawrence

Independent natural resource Valuers are an essential link between miners and mineral explorers on the one hand and the finance industry on the other. Investors (and regulators) expect the mining and financial industries to be vigilant against the use of inappropriate methodology or use of illogical steps within the chosen valuation method. The Australian Corporations Law generally requires an Independent Expert Report to support mergers and takeovers (as well as for capital raising activities). The introduction of the VALMIN Code (1998) by The Australasian Institute of Mining as Metallurgy, has meant that such Reports, when prepared in compliance with it, are now much more comprehensible and reliable than before. This is because the key requirements of the Code are for transparency and materiality in the Technical Assessment and Valuation Reports prepared in connection with the transaction involved. Transparency is particularly important because it allows the reader to identify and understand the assumptions made to derive a value and to then form a view as to the reasonableness of the result. Even though many elements of resource asset valuation practice are undeniably subjective, there must be some basis of objective rationality to it. Where the reasoning is patently illogical or the inputs are chosen to achieve a particular result, the estimated value must be viewed as virtually worthless. Experience, qualifications, competence and repute are the hallmarks of a professional technical auditor and valuer.

Jan 1, 2000

By Thomas W. Chapman, Shi-Chern Yen, I-Min Lu

"An electric field was applied to a metal-bearing kaolinite specimen to investigate the efficiency of electro-osmosis in removing heavy metals from contaminated soils. The electric field induces a flow of water through the porous medium, called electro-osmosis, which is superimposed on the hydraulic flow. Because the electro-osmotic flow is relatively stronger in smaller pores, it can enhance the displacement of contaminated solution by fluid convection. Furthermore, local changes in pH caused by the electrode reactions can affect adsorption equilibria and the distribution of solutes between the solution and the solid surfaces.The electro-osmosis experiments were conducted by applying either a constant current or a constant voltage across 8-cm inside diameter, 25 to 30-cm long specimens of kaolinite clay with graphite electrodes. Samples of the pore fluid and of the clay were analyzed to determine metal content, pH, and conductivity as functions of time and position. Results show that removal of heavy metals from soil can be accomplished effectively by electrokinetic treatment of sufficient duration. Approximately 95% of the lead was removed after 189 days.IntroductionRemediation of soils contaminated with toxic chemicals is a difficult and expensive task. Washing or leaching are not particularly effective if the contaminate is sequestered in small pores; hydraulic flows of water pass through larger pores leaving the smaller pores relatively untouched. Electro-osmosis appears to be the most promising new technology for removing heavy metals and organic substances from contaminated soils (Segal, 1980; Hamed et al., 1991, Masliyah, 1994).Electro-osmosis is one of several electrokinetic phenomena that occur through the interactions among an electric field, fluid motion, solute adsorption, and the existence of a net charge on a solid-fluid interface (Newman, 1991, Masliyah, 1994). Electro-osmosis refers to the fluid flow in a porous medium that results when an electric field acts on the mobile region of the electrical double layer, the solution-side region of charge separation that exists at the pore walls."

Jan 1, 1996

By Arthur E. Granger

IN the early days of the science, and until the recent past, geologists worked as individuals or in small groups. Prior to 1930 perhaps the largest single group under one administrative head was the Geologic Branch (now Division) of the U. S. Geological Survey, which employed at that time (including temporary help) 100 to 150 geologists. Today that same unit employs some 1500. In industry some companies employ as many as 100 geologists in a single department. These numbers obviously pose a need for administration. The basic qualifications for good administration are the same for any group of human beings, but the administration of geologists presents some special problems. Choosing Administrative Personnel: There are two kinds of personnel needs: 1) technical, which requires professional geologists who have proved their capabilities in the field, and 2) clerical and fiscal, which provide the necessary supporting or housekeeping functions. This discussion will be concerned only with the first category, except to point out the need for competent and understanding help from clerical and fiscal people and close relationship between top administration, technical or professional personnel, and the clerical and fiscal groups.

Jan 7, 1957

By Chuanfu Zhang, Liwei Liang, Yanxin Wu, Jinliang Wang

"According to the reaction shaft operation characteristics during the flash smelting process, 15 groups of slag samples containing high Fe3O4 were prepared by some chemical reagents, and then the slag viscosities were measured using a RTW-10 type synthetic test instrument for melt physical property by the rotating cylinder method. The effects of Fe/SiO2 ratio (mFe/mSiO2), Fe3O4 content (wFe3O4), Cu2o), MgO content (WMgO) and Cao content (wCaO) on the slag viscosity were also studied. Results show that slag viscosity is decreased with the increase of temperature, mFe/mSiO2, wCu2o, wMgO and wCao, and with the decrease of wFe3O4, under the range of slag contents: mFe/mSiO2 1.36~1.78, wFe3O4 17.83%~21.18%, wCu2o 3.51%~8.34%m wNgI 2.21%~6.57%m w/caI 6.22%~9.387% and temperature range if 1250 o/c~1450 oC. Only wFe3O4m and w/caO have great influence on the slag viscosity when temperatures as high as 1400 oC. Only wFe3O4 and wCaO have great influence on the slag viscosity when temperatures as high as 1400 oC or so. To form a freeze slag with higher viscosity inside the reaction shaft, wFe3O4 should be more than 20% and wCaO should be less then 6%.IntroductionSince its appearance in 1949, Outokumpu flash smelting technology has making continuous innovation and has become the most competitive intensified smelting technology [1], widely considered to be the standard clean smelting process [2]. At present, flash smelting technology is adopted to newly build or reconstruct most of the world's copper or nickel smelting enterprise [3]. Reaction shaft is the most important part of the flash smelting furnace. During the flash smelting process, reaction shaft must be able to withstand the following harsh conditions at the same time: 1) high temperature varying from 1400 °C to 1500 °C. 2) strong oxidative atmosphere containing 50% - 80% oxygen. 3) solid particles and melt with speed up to l00 m/s. 4) high acidic or basic slag with strong chemical corrosiveness. 5) smelting gas containing 50% - 80% SO2. 6) matte with strong dissolution."

Jan 1, 2012

By T. G. Hawkins, T. M. Naciuk

"The Katie Cu-Au deposit is situated in southeastern British Columbia, 425 km east of Vancouver. The deposit is a member of the alkaline group of porphyry Cu-Au deposits associated with potassically and propylitically altered andesitic volcanic rocks.The Katie porphyry system occurs in mafic to intermediate alkaline volcanic rocks of the Lower Jurassic Elise Formation of the Ross/and Group. Host metavolcanic rocks include andesitic to basaltic flows, flow breccia, massive fine tuff and crystal tuff Gabbroic intrusions alternate with the volcanic rocks in drill core. The lack of chilled margins and shear contacts, as well as their similar composition to the volcanic rocks, suggest that the gabbro was synvolcanic.Alteration exhibits a zonal pattern spatially related to zoned porphyry-style mineralization. Propylitic alteration is common and assemblages consist of epidote, chlorite, sericite and calcite. Potassic alteration zones are accompanied by elevated copper-gold grades and are composed of K-feldspar, plagioclase, quartz, biotite and chlorite. Narrow drillhole intervals of secondary magnetite, generally less than 2 m across, occur above the potassic alteration zones. A thick oxidized cap lies above the mineralized zones, although only local supergene enrichment has been identified. The lack of supergene enrichment is perhaps due to intense near-surface fracturing and leaching from a high energy groundwater environment.Sulphide mineralization consists mainly of pyrite within the propylitic halo, and pyrite and chalcopyrite with trace pyrrhotite, sphalerite, tetrahedrite, bornite and molybdenite within the potassic alteration core. Malachite, azurite and traces of chalcocite occur within the oxidized cap.Discovery and exploration techniques have included airborne geophysics, regional stream sediment sampling, prospecting, geological mapping, ground geophysical surveys, soil sampling surveys, and diamond drilling. Two primary targets of porphyry copper-gold mineralization have been identified by exploration. The Main zone strikes northwest, has an apparent true thickness ranging from 70 m to 135 m, and is a minimum of 500 m in length. The 17 zone strikes northwest, has an apparent true thickness of 90 m, and is a minimum of 300 m in length. The two zones are defined by grades that generally exceed 0.2% Cu and 0.25 g/t Au. Both zones are open along strike and to depth."

Jan 1, 1995

By Owen Collins

In surface mining, designing patterns to reduce the probability of flyrock and optimizing fragmentation through powder factor calculations are important for safe, efficient blasts. The designed powder factor is established for the blast once parameters such as burden, spacing, stemming, and powder column height are determined. In practice, these parameters are usually constant throughout a production blast with row-to-row burden and spacing. However, challenges can arise with the introduction of an open face. Many variables could necessitate the adjustment of the face row to optimize blast results. Variables include drill accessibility, challenges with toes, overhangs, and geology. The approach is often, but not exclusively, determining how to keep a consistent powder factor from the open face through the body of the blast. However, the solutions used vary case-by-case and rarely are two blasts the same. Technology has improved the ability to deal with challenging face conditions. 3D modeling with the aid of drones allows the application of angled holes to be more effective and simpler. This is just one instance where technology has improved blast results. This paper will present solutions to challenging face conditions. Thoroughly analyzing instances where challenging open-face variables were met with an effective blast solution could help provide insight as to what yields consistent blast results.

Jan 26, 2026

The manpower and time involved in primary blasthole stemming at Kennecott Copper Corp.'s Bingham Canyon mine have been reduced considerable through the use of a mobile stemming machine invented y three mine employees. The patented machine, developed 2% years ago at an estimated cost of $5000 for two units, is the brainchild of Thomas R. Carlson, mine plant superintendent; Alvin J. McIntosh, drilling and blasting engineer; and Jay K. Buehler, field repair general foreman. According to McIntosh, the machine has been well received by the mine employees, who have been relieved of the tedious task of hand shoveling drill cuttings into the blastholes. It is estimated that the stemming machine has saved the mine approximately $25,000 per year in overtime and regular labor costs.

Jan 12, 1976

The Pilbara iron ore industry has seen rapid growth over the last five years and is now bracing itself for another expansion which will take its seaborne trade to beyond 500 Mt/a. To effectively utilise port capacities, port stockpile turnover will become extremely rapid and each stockpile built will have to be of a quality which is precise and unbiased.Sampling systems at the older Pilbara mine sites were generally designed during the 1980s and reflect the practices which were considered adequate at the time. Hence, the precision of measurement at production sites is generally unknown and quality assurance (QA) of sampling facilities falls short of what current best practice suggests. This paper suggests practical improvements in sampling practices and quality assurance, which will assist the industry in achieving quality objectives in times of rapid mining expansion.

Jan 1, 2008

Hamersley Iron Pty. Limited has maintained an interest in the screening of iron ore fines (nominally -6 mm). However, no dry screening process had successfully demonstrated acceptable separating efficiencies at high tonnage rates, low operating costs, and mechanical reliability when screening iron ore fines (containing up to 6% free moisture) at sizes of around 1 to 2 mm. A new type of vibrating inclined screen has recently been developed which is claimed to have a non-blinding screening surface. It was decided to test a pilot scale unit in an existing pilot plant located at Hamersley's facilities at Dampier, Western Australia. The appropriate operating parameters such as vibration speed and feed rate were determined using one fine ore type. Mats with different aperture sizes, and different feed moisture contents were also tested. Trials were then conducted on various fine ore types to indicate the effect of different size distributions on separating efficiencies. The effects of feed moisture content were determined with these ore types, and a blend of lump (nominally -30+6 mm) and fines was tested to compare the screen's performance with that of the bottom deck of the minesite product Screens.

Jan 1, 1991