Search Documents

By Lim Thi Duong, Du Duy Bui, Thuat Ngoc Pham, Chuc Ngoc Pham, Que Anh Nguyen, Hoa Anh Bui, Chi Thi Ha Nguyen, Hoan Thanh Nguyen, Bac Quang Nguyen, Kien Trung Nguyen, Dung Trung Doan, Nhiem Ngoc Dao

The microstructures and kinetics of a rich iron ore ( TFe = 65.84%) of Na Rua mine, Vietnam, used for the iron production were investigated in this study. Thermal behaviors of iron ores were well-examined by heating microscopy, thermogravimetric analysis, and differential thermal analysis. After being pelletized and then oxidatively fired at 500–1200 °C for 2 h, the pellets fired at 1200 °C (P1200) displayed a hard and dense structure with a decent compressive strength of 317.9 kg/pellet whereas those fired at 500 °C (P500) had a soft and spongy structure. The reduction of iron pellets conducted in a flow of a 60–100% CO2/ Ar gas mixture at 900–1100 °C showed significantly higher efficiency than the reduction using coal. The spongy pellets showed superior performance for the reduction in the CO/Ar gas mixture compared to the dense ones, compatible with the production of sponge iron. When mixed with an amount of coal, P1200 designed for iron production in the blast furnace demonstrated an impressive reduction activity compared to P500 and previous studies. The kinetics of pellet reduction was determined by the diffusion of substances through the solid product layers having the mathematical model of 1 − 2 3 f − (1 − f )2∕3 = kt . The microstructures of pellets during the oxidative firing and reduction were also examined by X-ray diffractometry; scanning electronic microscopy; energy-dispersive X-ray spectroscopy; and Brunauer, Emmet, and Teller method.

Jun 7, 2022

By A. C. Fieldner

"INTRODUCTION In a previous report3 prepared for the American Gas Association, the influence of washing coal on coke properties and on gas and by-product yields was discussed on the basis of answers to questionnaires sent to coke-oven superintendents and a review of the literature on the subject. This review indicated that the elimination of free impurities by cleaning coal improved coke quality by (a) reducing ash and sulphur, (b) decreasing clinker trouble in burning the coke, (c) diminishing cross fractures in the coke, resulting in greater resistance to breakage on handling, and less small coke and breeze, and (d) greater uniformity in chemical composition and physical properties of coke. Washing also reduced the sulphur in coke and gas and increased the yield of gas and by-products per ton of dry coal charged.This paper is supplementary to the previous report and presents some experimental data obtained with Pittsburgh bed coal from Pennsylvania and Mary Lee bed coal from Alabama.ACKNOWLEDGMENTSGrateful acknowledgment is made to F. J. Pfluke, of the Rochester Gas and Electric Cc., of Rochester, N. Y., for the plant test data on screened lump and washed coal; and to Ray W. Arms, Manager of the Coal Cleaning Department, of Roberts & Schaefer Co., of Chicago, for the data on effect of air cleaning."

May 1, 1931

By O. T. Barrett, R. F. Aberethy, H. N. Cooper, Thomas Fraer, William L. Crentz

"INTRODUCTION The object of the techniques described in this report is to determine the possibilities of separating the components of a raw coal into such grades as may be necessary to recover some exceptionally clean functions for special purposes.To do this commercial gravity methods would require separation at very low specific gravities, entirely outside the range of conventional practice. Hence, a technique has been developed for breaking down cool ample, into very close fractions within the gravity range of the (-lean coal matter as well as for separating it from the refuse and particles.Such data on the fundamental specific-gravity consist of the clean-coal matter will serve to appraise the difficulty of the problem and to chow be accomplished if and when effective methods of making such separations commercially are developed."

May 1, 1945

By M. I. Al-Wakeel

Nile sediment was collected as a waste from one of the water treatment plants in Cairo, and subjected to petrographical investigation and granulometric, chemical, and mineralogical analyses. It was expected to find diatomite in that sediment but it was a surprise to find that the diatomite content amounted to about 52.01% by volume in addition to quartz, orthoclase and clay minerals. The latter are represented by montmorillonite and illite minerals. The sediment is light gray in color, soft and has low density and high surface area, such density and surface area generally decrease with temperature. The sediment absorbs 317% of its weight in water. The diatomite skeletons are the main factor responsible for its high porosity producing microporosity and low density, and these particles are concentrated in the very fine silt size fraction (11x2µm). The common diatoms in such sediment include Cyclotella ocellata Pant, and Melosira granulata (Ehr.) Ralfs. It seems that this Nile diatomaceous sediment has many advantages over the fossil diatomite, such as Fayium diatomite in Egypt, with the absence of carbonate minerals that require grinding and calcination those cause destruction of the cellular structure and energy consumption. This Nile diatomaceous sediment can be processed using sequential classification to obtain diatomite concentrate of 88.8% grade at 90.6% recovery, and a middling product of 19.4% grade and 5.8% recovery. The suggested flow sheet is quite simple to produce diatomite product for different industries at a low cost. The unusual particulate structure and chemical inertness make diatomite an ideal mineral to be used as functional filler in a wide range of industries, and as catalyst carriers and insulating material. Key words: Egypt, Nile sediment, Diatomite, Beneficiation, Sedimentation, Classification.

Jan 1, 2008

By Charles J. Zablocki, Robert J. Kamilli

"Abstract - Buried, possibly mineralized granite cupolas at the Silsilah tin deposit in Saudi Arabia (lat. 26°06' N, long. 42°40' E) have been successfully located using a closely spaced electric-field-ratio profiling technique. In this study, electrical fields at 27 and 270 Hz across grounded electrodes spaced 50 m apart were measured along six traverses. This method is interpretable by inspection, unlike the dipole-dipole technique, which requires mathematical modeling for interpretation.In the study area, the technique allowed the authors to identify and distinguish among unroofed granite cupolas, cupolas with their aplite-pegmatite apical contact zones intact, strong (quartz-rich) and weak (relatively quartz-poor) greisens, dikes, faults, and pervasively argillized rocks.This method should be useful in the valuation of other shallow mineral prospects in similar settings in other parts of the world, especially deposits for which the location of vertical contrasts is important, such as veins or mineralized zones associated with the apexes of small igneous cupolas."

Jan 1, 1993

By A. A. Beland, R. J. Dawson, S. Shewchuk

"Shovel buckets, scraper blades, dipper teeth, mine car wheels and hammermills are examples of equipment which require routine maintenance due to abrasion. Service life can be extended by the use 0/hard/acing and buildup materials. Mining and milling applications are described and field welding procedures discussed.A high-stress abrasion test used to select hard/acing and buildup materials/or hammers in a hammermill is described in detail. Field tests of the selected alloys confirmed their performance, and maintenance records showed a significant saving in down time and cost.The relationship between the abrasion resistance of the alloys and their hardness, work hardening, composition and microstructure is summarized. IntroductionLarge volumes of ore are handled daily by the mining industry. The abrasive nature of most ores results in extensive wear to both handling and processing equipment. If such wear is neglected it may cause lost production time and also, in extreme cases, require the complete replacement of expensive equipment. The well-planned maintenance of components subject to abrasive wear by means of buildup materials and hard facing can result in substantial economic benefits. Such benefits can , however, only be realized through the correct choice of welding process, consumables and deposition methods available to maintenance personnel. Hardfacing MethodsHardfacing is applied by a variety of methods; the three most widely used being arc welding, oxyfuel gas and thermal spraying. Table 1 summarizes the major processes used within each method. Filler metals in the form of rod, wire or powder are necessary to fulfill the individual requirements of each process. The filler rods are available in the cast form or, in the case of ductile metals or alloys, as wrought rod or tube. All types are supplied bare or flux covered. Wire is supplied in two forms, drawn flux cored and drawn solid. Powder filler metals are available in many metals or alloys; they may be simple mechanical mixtures or prefused and atomized alloys made to a specific size range and shape for optimum results for each applicable process."

Jan 1, 1980

The deposit was discovered during systematic reconstruction of the geological history of glacial overburden, which averages 6 m in thickness over 80% of Sweden, by geochemical sampling and searching for small grains of eroded bedrock. The gold is mainly concentrated in and around high-grade quartz veins within a broad shear zone, though the correlation coefficient between quartz and gold in samples is not significant. Production from two pits, now connected, in the Central and Eastern orebodies has increased steadily from 1 238 kg Au in 1989 to 2 120 kg in 1994, the highest in Europe. The mine has adapted and improved its mining methods to achieve significant productivity increases and cost reductions. Most of the improvements have been achieved through a better understanding of the controls on mineralisation and of the implications of those controls for selective mining. Geostatistics has played an important role in the quantification of grade variability and gold occurrence. Better blasting and loading techniques have improved selectivity, grade control has been enhanced by a grade-control drilling programme, and significant improvements in mineral processing have been made

Dec 1, 1995

By Carl Hendricks

Aquila Mining Systems Ltd., is the world leader in drill monitoring, control and GPS-based machine navigation systems for the mining industry. This paper will review the design and application of AQUILA’s drill monitoring, control and positioning systems currently in use throughout the world and some of the benefits that derive through their use. In 1993, AQUILA became the first company to install a high precision, cm level, real-time GPS receiver on a blasthole drill. In fact, this was likely the first application of GPS on any form of production mining equipment. To date, AQUILA has installed over 90 GPS based drill monitoring systems worldwide. Since 1992 AQUILA has continued to lead in the advancement of new technologies for drilling including real-time geology recognition and automated drilling control systems. The AQUILA DMseries drill systems offer mines the ability to collect and transmit to the mine office; drill production statistics, ore and waste intersections, exact collar elevations, hole positions and depths, maintenance information and consumables tracking. Unique office software developed by AQUILA provides an encompassing Windows environment within which to manage and coordinate all aspects of data communications and information management between the drills and various mine departments. AQUILA and Caterpillar, along with Mincom and Trimble Navigation are partners in a technology alliance that is providing the surface mining industry with vehicle tracking and navigation systems for all mobile production equipment.

Jan 1, 2000

By C. A. Pickles, J. M. Toguri

The refining of two molten Ag-Cu alloys, containing 7.5 and 11.2 mass% Cu, with a borosilicate slag was investigated using both air and pure O2 to determine the effects of the following variables: flow rate of oxidising gas; injection time; mass of sodium borosilicate flux; and injection of the oxidising gas into either the slag or the metal. The results demonstrate that more than 90% of the Cu can be removed with Ag losses of less than 5% and that refined metal with a Cu content of less than 0.5 mass% can be produced. Ag losses to the slag increased with the amount of Cu removed, and a mechanism is proposed to account for this

Dec 1, 1995

By Yonghong Qin, Songbo Ma, Qi Zhang, Peng Gao, Jianwen Yu

Herein, the coal-based reduction was proposed to utilize the ferronickel slag of Jingchuan company. An excellent index with metallization rate of 99.22%, iron grade of 77.91%, and iron recovery of 92.79% was obtained at carbon addition coefficient 2.0, reduction temperature 1573 K, reduction time 60 min, the particle size of coal and ferronickel slag − 2.0 mm, and CaO content 15%. The 2FeO·SiO2 was reduced to Fe and SiO2 with the increase of temperature. The CaO could promote the reduction of iron oxide. Most of the sulfides (Fe, Cu, Co, and Ni) in the sulfonium were reduced to metal. The reduction degree increased with the reduction time and reduction temperature. The higher reduction temperature represented the higher peak value of reduction rate and the shorter time of reaching the peak value. The isothermal reduction process included three stages: early stage, middle stage, and late stage. The mechanism function were f(α) = 1/2(1 − α)3, f(α) = 3/2(1 − α)4/3[(1 − α)−1/3 − 1]− 1, and f(α) = 4(1 − α)[− ln(1 − α)]3/4, respectively. The activation energy of three stages was 183.498 kJ·mol−1, 420.077 kJ·mol−1, and 656.619 kJ·mol−1, respectively.

May 24, 2022

By Floyd G. Anderson

A study was made of the effectiveness of dust-control methods being employed in connection with continuous-mining operations. Airborne dust exposures of workmen and dust loadings of return air were determined for six types of continuous-mining machines. The conditions required for control of dust exposure are summarized and include ventilation of the working face by an exhaust system. Return-air dust loadings ranging up to 13 pounds per hour are reported.

Jan 1, 1963

After nine years of negotiations, the U.N. Conference on the Law of the Sea approved a Law of the Sea Treaty text in April. Israel, Turkey, the United States and Venezuela voted against the text and 17 other nations including Belgium, the Netherlands, Italy, the Soviet Union, the United Kingdom and West Germany abstained. These nations still have the option of joining the treaty when it is opened for signing in December. However, the Reagan Administration has stated that several provisions of the deep seabed mining portion of the text are unacceptable and it seems unlikely that the United States, at least, will change its position. ALUMINUM Reynolds Metals Co. has criticized an Oregon state plan to relax air pollution standards for aluminum plants. The company feels that relaxation of the rules does not go far enough. Reynolds officials say that they have spent about $31 million at their Troutdale plant for state-of-the-art pollution control equipment, and if they are required to make the pollution reductions called for in the 1986 rules, Reynolds would be forced to close the 40-year-old plant.

Jan 1, 1982

Geology grads mine heated job market Salaries up 44 per cent in three years ?[Geology student] passed up a $100,000-a-year job at a mining company last December when he finished his degree in geology. The 24-year-old Canadian said he?s confident he?ll get a better offer.? Rob Delaney and Stewart Bailey, Calgary Herald, Published: Saturday, March 15, 2008 Massive shortages across the mining industry > Trades and operators are a large component > Technical people are equally hard to find > Students are in an excellent positions to secure exciting jobs > Experience is at a premium. Why?

May 1, 2008

This Bureau of Mines report concerns two subjects important in the application of electric power in mining systems. Electrical transients and their suppression are discussed, and several considerations are explored with regard to the use of explosionproof or other electrical enclosures.

Jan 1, 1979

By M. S. Fleming

The objective was to evaluate central lubrication systems for potential use on underground mining equipment. Previous use on continuous mining equipment resulted in poor system performance because of improper selection of lubricants, component failures, and an inconsistent delivery of lubricant to the bearings. The principles and operational characteristics of systems are reviewed and evaluated, and it was concluded that systems are available which can provide reliable central lubrication if properly applied, installed, and maintained. The procedures for applying a system to a continuous miner are discussed. Investigation revealed the lack of significant information on lubrication-related equipment failures and injuries related to maintenance and repair operations, the lack of significant failure rate data for central lubrication system components, and the lack of performance standards for central lubrication systems and components. To continue the development of systems for underground mining equipment it is recommended that a data bank on failures and reliability for equipment with and without central lubrication systems be created, and standardized specifications and performance criteria be developed for central lubrication systems and components which will be used on underground mining equipment.

Jan 1, 1979

By T. Marin, J. E. Seccatore, M. Cardu

The most energy-intensive process in the mining industry is particle size reduction – comminution. The first phase of this process is blasting to fragment the rock from the initial Boussinesq’s halfspace size. Scientific literature demonstrates that the output of a blast in terms of fragment size distribution can be manipulated by varying the specific charge (powder factor) and charge distribution. This study focuses on the influence of blasting on the internal resistance of the blasted fragments; in particular the influence of the spatial distribution of charges. Small-scale blasts were performed on 14 marble blocks using different powder factors and charge distributions. Three control blocks were fragmented by mechanical means for comparison. The results show the correlations between charge distributions and the specific energy of mechanical comminution. Opportunities for adjusting charge diameter and distribution in opencast blasts to improve the performancet of comminution circuits are discussed.

Aug 8, 2024

By J. Crummy, I. K. Anderson, A. J. Hall, R. S. Haszeldine

Bedrock gold mineralisation has been located in association with an extensive float train 25 km west of known alluvial gold. It is in the form of open, matrix-supported breccias comprising pyritic quartz/sericite clasts in a vuggy, cherty chalcedonic and crystalline quartz matrix. Fluid inclusions in pyritic clasts indicate trapping temperatures for gold mineralising hydrothermal fluid of 170-240 degrees C. This mineralisation could represent the upper part of a feeder zone to an exhalative hydrothermal system. It is possible that other high-level feeder zones could be preserved elsewhere in the area. Deep weathering of such a system could provide a source for the alluvial gold localities near Helmsdale. It is suggested that east and central Sutherland presents good prospects for exhalative epithermal gold mineralisation and the associated feeder zones

Jun 19, 1905

By Charles E. Whieldon

Because of the importance of recovering more oil from known petroleum reserves, increased emphasis has been placed on the application of secondary-recovery methods. It is hoped that these reports will stimulate interest in improved waterflooding techniques, thereby discouraging premature abandonment of oil leases. Previously published reports3 4 5/ have described the results of water-flooding in Roane, Pleasants, and Wetzel Counties, W. Va. (fig. 1). This report describes the South Penn Oil Co. Yawkey waterflood property, Berea sand, Griffithsville oilfield, Duval District, Lincoln County, W. Va. (fig. 2).

Jan 1, 1961

The history of soft and hard rock underground mining is blemished with regional instabilities of mine workings. Whilst the potential consequences of regional instability events are recognised to be high, there is a false perception that the probability of them occurring is very low. In fact, Australia has averaged more than one event per year for the past 20 years. At least five fatalities and over $100 million of losses have been associated with the events. As such, they are a core risk to underground mining and have a significant effect on the quadruple bottom line of business û safety, environment, community acceptance and economics. This paper explores the important roles that risk management has in reducing the probability and consequences of regional instabilities. It concludes that education and continuing professional development are essential elements for effectively managing the risk.

Jan 1, 2003

During the period 1979 thru 1982, Multi Mineral Corporation conducted a mining research program at the United States Department of the Interior's Bureau of Mines Oil Shale Mining Environmental Research Facility in the Central Piceance Creek Basin, Rio Blanco County, Colorado. The program consisted of mining, environmental and geotechnical research data and the results are described in this report.

Jan 1, 1983