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A powerful, interactive metallurgical process simulator for use on micro- computers has been developed in the Department of Metallurgy and Materials Engineering at the University of the Witwatersrand. MICROSIM presently allows simulation of all ore-dressing flowsheets and a selection of hydrometallurgical unit operations, and is extendable to all such processes. MICROSIM is written in Pascal. This modern language provides very versatile data structures which can be effectively used to solve the major problem in generalised simulation programs, namely storage and transmission of data relating to liquid and solid phases. Dynamic memory allocation allows optimal utilisation of computer storage space. The simulator utilises very efficient precalculation algorithms that determine the tear streams for optimal sequential modulator calculation convergence. Microcomputer graphics simplifies flowsheet specification, and form-filling data capture with supplied default values eliminate most common input errors.

Jan 1, 1987

I find that during the short time I have been in this district, the majority of boilers are, and have been, receiving very bad usage owing to the difficulties which they have to contend against, viz., oil and bad water. Oil on the heating surface of a boiler is of a highly dangerous nature inasmuch as it allows the surface to become overheated, owing to the water not coming into direct contact with the plates, and it naturally follows that when the crown sheets of a flue or firebox become overheated, you lose a considerable amount of the strength of the plate, and the flue or crown comes down. Referring to the oil question, I find that too much care cannot or exercised on the part of engine drivers in order to minimise as much as possible the internal lubrication of the various engines under their control. For I consider that it is here that the most of the trouble is caused. My reasons for stating such to be the case, are:-That the majority of enginedrivers before coming to this field have been used to driving engines that have been exhausting into the atmosphere, and probably they have been taught that it is far better to use a little extra lubrication than to have a hot bearing. So far so good. But one thing that must not be overlooked is that on these fields the conditions are altered in this respect, as the majority of engines in this district are not exhausting into the atmosphere, but are condensing their exhaust steam and using the water so condensed for feed purposes.

Jan 1, 1901

By Stanley F. French, Bruno F. Koch

Although the amount of dust that will be actually recovered in the six main dust-control systems cannot be accurately stated until the tests mentioned previously are carried out, it is estimated that the average air entering the wet collectors will contain around 5 grains of dust particles per cubic foot. This means that the six systems handling a total of about 133,000 cu.ft. of air per minute will return about 68 1/2 tons of dust to the concentrator per day and since the copper in this dust will average around 2 per cent, the total recovery is approximately 1.37 tons of copper every 24 hours. This important copper recovery is not due entirely to the dust-control system since in a plant without control only the duct that is dispersed to the atmosphere represents a loss. A conservative estimate of the recovery of copper solely due to the dust control system would be about half of the total or approximately 0.70 tons of copper per day.

Jan 1, 1942

By U. A. Peuker

"Steam Pressure Filtration (SPF) is a modified cake filtration process and is characterized by both washing and excellent de-watering of the filter cake. Compared to conventional gas differential pressure filtration, the filter cake is treated with saturated or superheated steam replacing pressurized air. Invented in the early last century, Steam Pressure Filtration has reached technical maturity in the 1990ies for inorganic particle systems, fine chemicals and coal. Especially the de-watering performance for fine particles systems below 50 µm make Steam Pressure Filtration an excellent option for the processing of fine tailings streams, to produce a stable material, which can be described by the methods of solids mechanics instead of paste rheology. The washing, which is due to the condensing steam, is able to reduce the ion load of the solid. This additional effect is able to generate a dry tailings material, which shows a reduced leaching potential of mobile ions, which originally derive from the process water. INTRODUCTION Steam Pressure Filtration is a process concept especially of hyperbaric filtration, which started its market entry in the 1990ies (Bott 1996, Bott 2002). Even though there have been many attempts to apply steam on filters before, the success story began with the combination of hyperbaric filtration and steam application and the technical solution to limit the steam treatment to a defined zone on the filter. This resulted from the scientific findings that steam mainly enhances the de-watering during the mechanical filtration (Gerl 1999). There are no or minor positive effects of steam application to a filtration process during cake filtration and after the steam breakthrough has occurred. Furthermore that time a sufficient control technology to regulate the steam consumption as well as suitable filter cloths became available. There is a growing need for de-watering technology in the mining industry, not only for the concentrate but also for the tailings streams. Several reasons argue against the established solution of damping the tails as suspension or paste into tailings ponds. There are ecological, political, societal and economic reasons, which question the tailings ponds more and more. Due to the increasing costs in the building and monitoring of tailings dams, which contain the tailing ponds, the concept of dry stocking using filtration technology comes into the game (Jansson 2016). Dry stocking converts the tailings stream form the suspension or paste state, into a material, which can be stockpiled. The latter typically is a moist flowable disperse particle system. The conversion involves a de-watering step, in which different types of filter equipment can be used, e.g. filter presses, membrane filter presses, automatic press filters or hyperbaric filters. For coarse products also vacuum filter can be applied. Due to its excellent de-watering performance and the easy scale-up properties Steam Pressure Filtration is further option for dry tailings stacking."

Jan 1, 2018

WINDING engines are one of the most important units in the equipment of a mine. Upon the winding machinery depends not only the output of the mine, but it supplies in most cases the only means by which workmen enter and return from the mine, and consequently the utmost care and attention is desirable in its design. The efficiency of a direct acting winding engine, as a machine is very low. In other words, the proportion between the useful work performed and the actual work the engine is capable of performing (under the most favourable conditions) is very small. The reasons for this are:-1. The intermittent nature of the work; the engine is stopped from 20 to 25 %(or even more) of the time which would constitute a useful day's work.2. The large amount of power that is absorbed applying the brakes to bring the load to rest.3. That the net useful load raised is small in comparison with dead load to be lifted, and the parts to be set in motion.4. That, owing to the frequent stops, initial condensation in the cylinders is always greater than in a continuously running engine, whilst radiation from steam pipes, valve chests, &c., goes on whether the engine is running or...

Jan 1, 1911

Currently raw brown coal is fired in the Latrotx; 'ahcc th,iki~, Lanying with it two major penalties, (a) boiler efficiency of 65 - 70 per cent (in terms of GCV), (b) much higher boiler cost than for black coal. Drying the coal, in energy-efficient, and cost-efficient manner, opens the way to efficiencies of order 88 per cent and enables the lower cost black coal type boilers to be used. With the higher boiler efficiency goes much higher combustion temperatures and the effect of this on radiative heat transfer is a major factor in reducing boiler cost. In a fluidised-bed combustor the temperature is controlled to 800C - 900C. In a pulverised fuel combustor higher temperatures are however achieved and can increase boiler fouling due to the salt content of the coal. This is a problem which needs to be solved. Victoria has the prospect of lifting efficiency from 28/29 per cent to 35 per cent, of reducing carbon dioxide output correspondingly and reducing cost of power stations. So far as gasification is concerned, efficient removal of liquid water from the coal is important to the overall efficiency.

Jan 1, 1992

By H. M. Ziesemer

PRIOR to 1909 that mountain of porphyry, known as. Sacramento Hill, had remained hardly touched but had always aroused suspicions as to the presence of ore within.. During that year, exploratory work was started by underground methods; drifting and raising continued until 1913. It was proved that a mineralized zone existed, the limits of which had not been determined; so, because of the lower costs of exploratory work and the greater desirability of vertical sections, it was decided to prove the extent of the ore zone by churn drills. Drilling continued until the year 1917, when it seemed almost certain that the horizontal limits of the orebodies had been determined. Ore continued in depth in one direction beyond a point where it was economical to explore by churn drilling; this extension is still being developed by underground methods. The irregularities of the boundaries of the ore zones, together with the variable grades of ore encountered, made it necessary to drill on the corners of 100-ft. squares. Two ore zones were proved, known as the East and West Orebodies. The Sacramento Hill porphyry stock intruded into the Dividend fault. The fault ran roughly east and west with a dip to the south, having pre-Cambrian schists on the north against Paleozoic limestone on, the south. This intrusion was accompanied by a silica breccia on the south periphery, along the limestone contact side. The ore lay in the silica breccia and in the porphyry, some distance from the breccia. No ore was found in the heart of the porphyry mass on the north side, along the schist contact. The West Orebody is elliptic in shape, having a major axis of 1200 ft. (366 m.) and a minor axis of 800 ft. (244 m.); these diminish with depth until, at 300. ft., the axes are 500 ft. and 300 ft., respectively. The ore consists of chalcocite, some bornite, chalcopyrite, and considerable pyrite in a silicious gangue. About 30 per cent. of the copper is caused by

Jan 2, 1922

The Australian Coal Combustion Testing and Research Facility has been operating commercially for one year and during that period coal product evaluations have been conducted on behalf of four coal companies and one electricity commission. The facility is equipped to assess the behaviour of steaming coal in milling, combustion (including flame stability, burnout and heat transfer), ash deposition and erosion, fly ash collection and gaseous emissions. The relevance of the results of the pilot testing to industrial practice was demonstrated during the calibration of the facility using four coals burnt in Australian power stations. The calibration coals were from the Tarong and Gladstone Power Stations in Queensland, tluja Power Station in Western Australia and Bayswater Power Station in New South Wales. Also an opportunity arose to visit an overseas power station to observe a full scale test burn using one of the early coals tested on a commercial basis in the combustion test facility. The calibration trials showed excellent agreement with industrial coal performance in t:orms of flame stability, turndown, carbon burnout and gaseous emissions. Encouraging correlations were also found in the case of furnace radiation, boiler deposits (slagging and fouling) and electrostatic precipitation. In the case of the last group the only real reservations about the correlations are due to the non-availability or qualitative nature of results collected around the power stations. In all cases there is a high degree of confidence in the facility's ability to predict the relative performance of different coals and in some cases direct numerical predictions can be Made.

Jan 1, 1987

By Marius B. Wechsler

A mathematical analysis is developed for the determination of the cases when HP-piles might be replaced by precast concrete piles. The analysis focuses especially on the "integral abutment-bridges" which are used on large scale in the Great Plains of the United States of America, The theoretical considerations are illustrated by a numerical example.

Jan 1, 1992

India is on fast economic growth. Even in the turbulent years of global crisis, it could achieve a growth of over eight per cent. In recent past, Indian Government has been contemplating a faster growth in all the sectors of economy so as to make the nation an economic power in the world.Steel is a versatile material. It has its role in most of the major industrial activities, such as infrastructure, automobiles, urbanisation, consumer durables and other. In other words, steel is a part and parcel of industrial expansion, urban and rural development. It is rightly admitted that steel acts as pillar of any development model. Volume of steel consumption is the barometer which measures economic progress and/or industrial status of any country.India and China are the two countries in Asia which have the significant impact on the global steel industry. Of course, China is much ahead of India in consumption level of steel.

Dec 6, 2010

By J. L. Humphrey

The origin of roof bolting is obscure, but is believed to have begun some 40 years ago in the mines of St. Joseph Lead Co. in southern Missouri. It was not until after World War II, and more particularly after 1949, as a result of the concentrated effort of the USBM, that roof bolting attracted widespread interest. It is estimated that at the end of 1954, 26 pct of all bituminous coal mining in the U. S. was being done under roof bolts. Those mines alone use nearly 2,000,000 roof bolts per month, according to USBM statistics. Uses in metal mines are increasing rapidly, as confidence and knowledge grow. The application has found equal success in other fields, such as tunneling work for dam and waterway construction and right of way maintenance on highways and railroads.

May 1, 1956

By A. G. McGregor

IN THE Southwest a number of large steel chimneys discharge the gases from the copper smelting furnaces. Some of these chimneys show no deterioration after twenty years, others show serious deterioration after tour years service. A steel stack 20 ft. 7 ½ in. (6.3 m.) in diameter by 279 ft. (85 m.) high, Fig. 1, used for roaster gases only at the Calumet & Arizona Mining Co.'s plant at Douglas, Ariz., was lined to the top of the bell, 40 ft. (12 m.) from the base, with common brick placed on end, lime and cement mortar being used. Above the bell, the stack was lined with 4 by 4 by 8 in. (10 by 10 by 20 cm.) building tile, placed on end, making a lining 4 in. thick. The tiles were supported on angle-iron rings, riveted to the inside of the chimney shell about 15 ft. apart. The chimney was put into use in the latter part of 1913. Four years later, considerable of the tile lining had fallen out of place and mixed with the flue dust at the bottom of the chimney. About a year later, several . flattened and distorted sheets were noticed about 70 ft. below the top. An investigation showed that the thickness of these distorted sheets, which was originally ¼ in., had been reduced one half. One year later, or six years after the chimney went into use, several holes, a square foot and smaller in area, appeared near the flat spots mentioned. Soon afterwards, when the chimney was shut down for repairs, it was found that most of the tile lining for 125 ft. from the top had fallen out and that the steel shell was badly corroded; but where the lining remained in place the shell was undamaged. Many of the tile which had fallen out of place had become soft or flaky and crumbling, others were as hard as when placed. An analysis of the hard and soft tile is shown on p. 2. These tile were of a fireclay mixture, and were used instead of common brick on account of lower cost. The steel forming the upper 125 ft. (38 m.) was replaced, and a 4 ¼ -in. (11-cm.) lining of firebrick was laid from the bell to the top of the chimney. The brick were placed on end, wedges and keys being used. After each 8-in. course was set, keyed, and wedged tight, thin mortar -water, sodium silicate, and finely ground silica-was worked into the joints. The brick are supported on angle-iron rings, every 15 ft., in the same way as the tile.

Jan 1, 1921

By R. Dekkers, J. Plessers

The feasibility of using hydrogen to obtain clean steels is investigated. High hydrogen contents are generally considered as detrimental due to the risk of flakes, bubbles and breakouts during casting. Hydrogen can nonetheless be removed by degassing of the steel. The results of industrial campaigns, where total oxygen content and hydrogen content were monitored, are presented. High resolution microscopy of inclusions and laboratory experiments on the rate of inclusion removal by CaO-Al2O3 slags at different partial hydrogen have been carried out. So far, evidence that hydrogen may influence inclusions or the steel cleanliness is not clear. Keywords: hydrogen, cleanliness, inclusions.

Jan 1, 2004

By Remi Tremblay

This paper describes the laboratory study which permitted an exploration of high grinding ball consumption in the secondary open circuit wet grinding mills at the Sidbec-Normines plant, Port Cartier, Québec. Corrosion undoubtedly exists but is of minor importance. Abrasion resulting from the physical nature of the company's iron concentrate is the main reason for the high ball wear. It was found that at least 30% reduction in ball consumption is possible by decreasing attrition grinding through the use of lifters in the mill. At the industrial level this would entail more lifters and/or higher lifters in the mill linings.

Jan 1, 1984

By Lawrence K. Nordell

Historical methods of designing steel cord belt splices are compared with modern finite element modeling (FEM) methods. Dependence of the belt strength rating on the splice dynamic fatigue strengths is reviewed. A number of splice schematics are examined, using simple spring theory and FEM methods. Steel cord wire rope design is discussed. The importance of the insulation gum rubber properties and their splice dimensional factors and tolerances are analyzed. Splice fatigue lie analysis procedure is reviewed. This may be used to predict splice life or time of failure, depending on how the conveyor belt is operated.

Jan 1, 1993

By Galyn Rippentropp, Finn Erik Overlie

INTRODUCTION The wet shotcreting system utilizing steelfiber microsilica shotcrete with remote controlled equipment (The Robocon System) was developed in Norway 7-8 years ago. Norway was the natural origin for this system due to several factors. Almost 30% of all underground hydro-power stations in the world are located here. These projects created a need for high productivity shotcreting rigs for the rock support work in the caverns and in the connecting tunnels. During the period of 1976-1980, more than 1000 miles of tunnels were completed in Norway. Secondly, the utilization of microsilica in concrete was also developed in Norway due to a concentration of the world's ferroalloy p ants there. Robocon has presently placed approximately 110,000 m (150,000 cu. yds.) of this superior shotcrete, and has consequently an extensive experience in the shotcreting method. During a relatively short period of time (1975-1980), Robocon had a change from hand-operated, dry-process shotcrete to remote-controlled, wet-process shotcreting, because of improved productivity, reduced rebound, safer and cleaner working conditions. The introduction of microsilica and water-reducing admixture made it possible to produce wet-process shotcrete of high strength.

Jan 1, 1987

By Peter Shuttleworth, Chris Fesq, Eddie Woods

Precast concrete segmental linings for tunnels have traditionally been designed with conventional steel bar reinforcement. In many cases, this has been satisfactory in service, but in others, major problems have occurred with the durability of the linings. Commonly this has resulted from corrosion of the reinforcement, mainly from chloridesin ground water, causing spalling of the concrete and leading to very expensive and disruptive repair programs. This paper discusses the relative merits of designing tunnel linings with steel fiber reinforcement to provide long-term durability, improved impact resistance and toughness for greater load capacity across joints, enhanced robustness during transportation and erection, plus improved fire resistance with the addition of polypropylene fibers. Guidance is also given in the selection of the correct fiber type, mix design and testing methods to establish the optimum dosage required and production techniques to ensure even distribution and compaction.

Jan 1, 2005

By Mike Dry, Rod Dry

If humanity is truly serious about reducing emissions of carbon dioxide into the atmosphere, today’s power plants burning fossil fuels will have to be replaced by power plants that do not emit CO₂. Unless carbon capture/sequestration becomes practical, the new power plants will be hydroelectric, wind, solar or nuclear installations. Hydroelectricity requires the appropriate geography. Solar installations can only deliver power as and when sunshine is available, and wind installations when the wind blows. Therefore, power from these sources will be intermittent, but the demand for electricity does not follow the patterns of sun and wind. That will require large-scale electricity storage and/or load following by the remaining power suppliers, increasingly so as the use of fossil fuelled power generation declines. Modern nuclear power plants are designed for demand following. However, operating at lower than design output has a negative impact on the economics of nuclear power plants because the overall cost of the electricity they generate is dominated by capital cost. Primary (blast furnace) iron smelting is responsible for a significant part of global CO₂ emissions because the reagent used is carbon. Were it available in sufficient quantity (and at a low enough cost), hydrogen could replace carbon in the manufacture of raw direct reduced iron (DRI), using technology such as modified HYL (Tenova Hyl, 2018) or Midrex (Ravenscroft, 2017). This paper examines a scenario in which, instead of demand following, nuclear power stations are operated at their design capacities and surplus power is used to generate hydrogen in off-peak periods. This hydrogen is then used to replace carbon in the manufacture of raw steel.

Jan 1, 2020

By Jeongbok Seo

The Dulles Corridor Metrorail Project (DCMP) involves the design and construction of a 23.1-mile extension of the Washington Metropolitan Area Transit Authority (WMATA) rail system. The initial 11.7-mile extension, with five transit stations and a new service and inspection yard, is to be constructed. The construction plan for the initial 11.7-mile extension includes installation of a total of an estimated 4,250 or 160,000 linear feet of driven 12x53 steel H-Piles at more than 80 different locations. At the time of this paper, approximately 40 percent of the piles have been installed and the remainder of piles will be installed by the end of 2010. This paper describes: 1) subsurface investigation program, 2) application of existing Codes and impact on the design of H-Pile, 3) design methods to determine geotechnical bearing capacity and pile tip elevation, 4) verification of capacity including PDA and Static Load Tests, 5) project specific pile load tests, and 6) QA/QC during pile driving.

Jan 1, 2010

By James W. Weaver

The 2,120-foot long cable stayed Penobscot Narrows Bridge that carries US Route 1 over the Penobscot River between Verona Island and Prospect, Maine is supported on four foundation units, one below each pylon and one at each abutment. Due to varying subsurface conditions along the bridge alignment, the structure was designed to be supported on foundations consisting of high-capacity steel H-section piles (Verona Pylon), a mat bearing on a prepared bedrock surface (Prospect Pylon) and spread footings bearing on compacted rockfill (abutments). The 70-foot by 80-foot (plan area) Verona Pylon foundation was designed to be supported by 288, 430-kip design capacity steel H-section piles (HP14x117, 50 ksi steel) driven through up to 100 feet of dense glacial till deposits containing cobbles and boulders up to 3 feet in diameter. The piles were installed using a single-acting diesel hammer (Delmag D62-22) with a maximum rated energy of 165 kip-ft. Thirteen representative piles were selected for dynamic testing (ASTM D-4945) to verify pile capacity, hammer efficiency and pile stresses. Dynamic testing determined that four different pile driving criteria were needed across the site due to variation in the bedrock and soil resistance below the footing plan area. Approximately 4 percent of the production piles were damaged/rejected due to misalignment and/or damage as a result of encountering the cobbles and boulders embedded in the glacial till. The rejected piles were located randomly throughout the plan limits of the foundation mat. Subsequent structural analyses indicated that the foundation was capable of safely supporting the design loads without the need for installing replacement piles. Evaluation of dynamic testing results with signal matching and pile driving records provided valuable information on pile side and tip resistance. Evaluations were made regarding predicted versus actual pile lengths, pile bearing material, distribution of skin friction and end bearing capacities.

Jan 1, 2011