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By C. Pamukcu

In this paper, which is aimed to serve as a review article, first of all a breakdown of the earth?s total water reserves is given. The usage areas of water in the mining industry are mentioned and these uses are briefly outlined, together with the main pollution potential of each. According to this, most of the water (almost 80% of it) is utilized in processing. Later on, probable damages that the mining would give to groundwater as a result of acid mine drainage, heavy metal pollution, euthrophication and deoxygenation is described. Finally, the measures and controls that should be taken against water contamination in mines are presented.

Jan 1, 2008

By Xiaojie Yang, Gang Yang, Zhenli Hao, Manchao He, Ruifeng Huang, Zheng Wang, Chaowen Hu

Preventing the spontaneous combustion of remnant coal, which is indicated by carbon monoxide (CO), is a significant issue for coal mining safety. The N00 longwall mining method with Z-type ventilation is advantageous for the prevention and control of CO; however, research regarding this topic is limited. To investigate the distribution of CO in a goaf and working face, a sealing material and technique for blocking the goaf were introduced after proposing a forming method for a Z-type ventilation system; furthermore, a monitoring method was designed and applied in the field. The results demonstrated that the CO concentration during mining in the upper corner and return airway ranged between 4–6 ppm and 3–7 ppm, respectively. More importantly, no CO was generated in the goaf. The results indicate that the advantages and mechanisms regarding the prevention of spontaneous ignition using the N00 longwall mining method with Z-type ventilation are as follows: (1) The adoption of the downward ventilation technique is not only beneficial for reducing the air pressure difference between both ends of the working face, but also prevents CO accumulation in the upper corner. (2) The basis of a spontaneous combustion disaster is eliminated owing to the absence of coal pillars reserved in the goaf. This study proposes a superior method for mitigating spontaneous combustion disasters related to remnant coal in the goaf in a coal mining field and contributes to the better understanding of the N00 longwall mining method for coal mining safety.

Nov 28, 2022

By Liu C. H, Juang Y. F

Coal/gas outbursts were one of the rather difficult safety problems faced in the coal mines of this Country, with coal fields characterized by frequent disturbances of folds, faults and pinch-offs. With average mining depth about 500m below surface, several such accidents occurred with up to 500 tonnes of coal outburst. In recent years, after a series of improving countermeasures had been undertaken, gas outburst accidents had been greatly decreased. The characteristics of gas outbursts in Taiwan coal mines include relating to coal petrography, mining depth and the other deformation forces. All these have been investigated, trying to determine the parameter of outbursts under natural conditions. The preventive countermeasures include predicting tests, de-stressing boring in coal seams, the emergency procedures during outbursts and certain improving options.

Jan 1, 1988

Lewis, B. LINDEMUTH, ?New York, N. Y.-I would like to confirm Dr. Howe's supposition that a process could be worked out for steel along similar lines. About 1 ½ years ago, F. D. Carney and myself were working on the elimination of columnar crystals which are particularly evident in nickel steel. We discussed rotation and varying speeds of rotation, but figured that with just rotation the steel would eventually catch-up to the motion of the mold and that the desired effect could not be obtained in that way, so we decided to alternate the direction of rotation. We rigged up in ordinary commercial turntable and on the same mounting attached a blast, furnace and mud gun, which is a simple steam cylinder, and mounted an 18-in. ingot mold on the turntable. The turntable had a stroke of about 10° to 12°, with stops at the ends. The steam cylinder would bang the table against the stops so that the stopping was so violent that it would tend to keep the metal in motion when the mold stopped and thus wash away any crystals that would form. We made quite a few interesting experiments; the results of which were that the columnar crystallization was entirely eliminated. At the same time we cast ingots in a similar mold, allowing the molds to remain stationary; these showed columnar crystals of from 2 to 4 in. in depth. The grain structure of the balance of the ingots, which were rotated, was very much finer than the grain structure of the ingots that were cast and allowed to cool slowly. The experiments were made on a 0.35 per cent. carbon nickel steel, which is probably more susceptible to columnar crystallization than any other. I think that the rolling properties and the forging properties of some alloy steels could be very much improved by a similar method, or some commercial method of casting ingots to eliminate this columnar crystallization.

Jan 5, 1919

By Mario SINNAEVE, Olivier LEMAIRE, Gisèle WALMAG, Sébastien FLAMENT

Many hot rolling mills worldwide face nowadays bonding zone fatigue problems before reaching scrap diameter of the work rolls. This phenomenon is nowadays known to occur in reversing roughing mills both in stainless steel and in carbon steel rolling. The phenomenon can be explained through longer rolling campaigns, inadequate backup or work roll maintenance, harder steel grades or increased throughput by reduced amount of passes to achieve the same thickness. In order to help users in optimizing the roll use, we developed a numerical tool to evaluate and optimize roll maintenance. This paper will review the influence of roll geometries on stresses generated at the roll surface but also at the bonding zone. We will also show how roll geometries can decrease contact fatigue damages by modifying crowning and chamfering procedures, shell thickness, material design or campaign length

Oct 1, 2019

By L. Salnais

"Aluminum alloy structural components f or aircraft designed prior to the early 1970s, were machined from 2024, 7075 and 7079 plate, bar and forgings in either the T3xxx of the T6xxx tempers. Protective treatments for these parts consisted of chromic acid anodizing and alkyd zinc chromate primer, plus a nitrocellulose lacquer for exterior parts.The major service problem with these parts was the frequent occurrence of exfoliation corrosion and stress corrosion cracking (S. C. C.). Therefore, 2024 and 7079 alloys, with min or exceptions, were not used in aircraft designed after the early 1970s. Replacement materials were 7075 and 7050 alloys in the overaged, exfoliation corrosion and S. C. C. resistant, T73xxx tempers.The use of improved materials together with the upgrading to chromated epoxy primers, polyurethane enamels and the introduction of water displacing corrosion inhibiting compounds have significantly reduced corrosion in aircraft. IntroductionThe prevention of corrosion in aircraft has been a challenge to aircraft designers for many decades. With the design of the first all-metal aircraft, the designer and builder were thrust into the relatively new field of protective treatments as corrosion started to become more prevalent. This resulted from the continually increasing importance and wider utilization of aircraft, and their exposure to a wider variety of ho stile environments such as urban industrial pollution, high humidity tropical areas and salt ladened marine environments.Corrosion advanced another significant step when, after World War II, designs of new and larger aircraft utilized larger and thicker metal sections in the manufacture of structural components. With thicker mill products came higher residual heat treat, fabrication and assembly stresses resulting in an increased number of stress corrosion and exfoliation corrosion problems.Apart from the exterior environment, aircraft interior s can be exposed to a number of fluids which are either directly or indirectly responsible for corrosion. The most common of the fluids is water which is usually introduced as a result of condensation, especially in pressurized fuselages, and spillage from lavatories, galley s and electrolytes from batteries. These fluid s have a degrading effect on protective treatments and are also corrosive to the substrate metal. Fluids such as phosphate ester hydraulic fluids and ester based turbine engine lubricating oil s are not corrosive to the substrate metal, albeit they do contribute to corrosion by the degrading effect on protective treatments."

Jan 1, 1988

By E. Ghali, B. Arsenault

Aluminum alloys play an important role in the manufacturing of air and ground vehicles. However, with such alloys, corrosion damage is often found on structural components subjected to fatigue loading. The alloying provides large benefit in terms of the high specific tensile strength (ultimate strength/density ratio) to the aluminum alloy but causes the aluminum alloy to be more sensitive to localized corrosion due to complex microscopic heterogeneities such as secondary phases. This paper investigates thermal spray coating namely arc spraying to evaluate the protection against environmentally assisted cracking (EAC) and localized corrosion on Aircraft structural 7075 T651 aluminum alloys. In particular, EAC and pitting corrosion at the interface coating-substrate are a challenge for thermal spray protective coatings on aluminum alloys under cyclic load and immersion. To address these issues, different surface preparation techniques prior to arc spraying were considered such as chemical de-oxidation, laser ablation, shot peening and grit blasting. Results indicate that surface preparation and improved coating process parameters play an important role to provide a coating conferring a protection against both localized corrosion and EAC.

Jan 1, 2006

By S. Abe

An extensive study has been carried out to determine the true cause of floating slimes precipitation which sometimes occurs and badly affects the quality of copper cathodes. Soluhilities of floating slime compounds systematically measured for the ternary system As-Sb-Ri added solely or in combination with conventional copper electrolyte (63°C) and bench scale electrorefining experiments done by varying electrolyte composition, have shown conclusively that the level of Sb(V) ions plays a substantial role in the precipitation mechanism. It was, therefore, speculated that controlling the level of the less soluble S b ( V ) ions below a certain critical level should result in a complete elimination of the undesirable precipitation. This can be easily achieved, for instance, by the addition of a reducing agent such as SO2 gas and the simultaneous employment of a certain type of cheating agent that effectively removes excessive Sb and Bi from the contaminated electrolyte. Long-term pilot testing conducted in line with the above speculation has confirmed the SO2/chelating resin scheme to be industrially very attractive and feasible.

Jan 1, 1987

By W. G. Courtney

The prevention of frictional ignition with a ripper-type continuous mining machine using conical bits was investigated in the laboratory using cutter-drum-mounted water sprays. Results indicated that frictional ignition during dry cutting of sandstone with conical bits was readily obtained even at low drum rpm, while wet cutting with a carefully-designed water spray nozzle located behind the bit substantially reduced the likelihood of frictional ignition. However, the orientation and operation of the spray nozzle is critical and involves almost no margin for error. A Lee-Norse 265 ripper drum has been modified to include durable water seals and is presently being field tested underground.

Jan 1, 1987

By P. C. Thakur

Frictional ignitions (also called face ignitions) is defined as the rapid oxidation of a mixture of methane and air with a visible flame that could last from a few seconds to several minutes. These ignitions have a potential to turn into a mine explosion and eventually a large-scale mine fire. Over the last 22 years, U.S. coalmines have had 1566 frictional ignitions. There were no fatalities but serious injuries have occurred. Every effort, therefore, should be made to prevent frictional ignitions. The preventative measures fall under four categories: (a) degasification of coal seams prior to mining, (b) adequate ventilation, (c) wet cutting or water-jet assisted cutting and (d) machine design to minimize ignitions. The paper discusses each of these techniques in detail.

Jan 1, 2006

By A. J. Lanza

THE prevention of illness among the employees of the mining industry is especially important in view of the importance of the industry, the unsettled conditions of labor, which emphasize the economic necessity for conservation of labor, and for humanitarian reasons. The burden of chronic illness is altogether unwarranted and unnecessary. If the industry is to maintain its labor supply in an efficient manner and keep the standard high, it is essential that it make every effort to keep its labor in good physical condition. The basic principles underlying health conservation are the same for any industry, but they are here applied especially to the mining industry, and more particularly, perhaps, to metal mining, as it is with this phase of the industry that the writer is most familiar, and as it is conceded that metal mining presents more health hazards than coal mining. The first step in the prevention of illness lies in securing employees who are in sound health and free from organic disease. I do not mean that all men who go underground should be physically perfect, but they should be free from organic defects of the heart, lungs, and other organs, or from anatomical defects that would- markedly increase their liability to accident. The number of men working underground in mines in this country whose physical, condition totally unfits them for such work presents-a situation that should not be allowed to continue, and which I believe is 'not equalled in any other, industry in the country. There is but one way to secure men who come up to the required standard, . and that is by a thorough physical examination before employment. I am fully aware of the objections felt toward such a procedure by many employers and employees. There is much to he said on both sides, but to any one who is at all familiar with the mining industry as it is today in this country, and who approaches the matter with an unbiased mind, there can be absolutely no doubt as to the necessity for physical examination. As a purely logical proposition this is self-evident, but there remains the further necessity of placing physical examinations on such a

Jan 2, 1919

J. J. CARRIGAN, Butte, Mont. (written discussion*).-I think all who have had experience in the operation of metal mines will agree with Dr. Lanza that many improvements can be made in the underground workings to improve health conditions. Physical examination would no doubt be a good thing and would do a great deal in abating the diseases now so common among metal miners, but I cannot see how it would be possible to put this examination into practical working order. Dr. Lanza says, "For the sake of argument, this physical examination should be under state supervision." I think if, this were attempted it would result in nothing but argument. While such a law possibly could he passed in a few states, I feel certain that in the greater number the miners would fight such legislation with the same determination that they would

Jan 4, 1919

CHARLES F. WILLIS,* Bisbee, Ariz.-(written discussion?).-The consensus of the discussion of the paper of Dr. Lanza indicates that the physical examination, while it is probably a good thing, is fought by the workingman, and that, because of this fact, it has been proved unsuccessful. The physical examination standing alone is worth but little, and could easily be made a subject both of ridicule and dissension unless the company having such examination shows its own good faith in promoting a thoroughly better health program. It is easily seen why a workman would resent his employer expecting him to be physically fit, if at the same time the employer provides un-healthful, unsanitary, working conditions, or if the town in which the employees are expected to live is dirty and unkempt. One mocks the other. The employer cannot say, "You must remain healthy so that I can get by with unhealthy conditions." But if working- conditions are as good as can be obtained to keep men well, the employer can ask his men to be in a healthy condition. A State examination and standard would have many difficulties, owing to the fact that a man would pass or would not pass the standard set, thus eliminating the discretion on the part of the employer in placing men whose physical condition might well permit working in one place and not another. Any physical examination that is run for the purpose of eliminating the physically unfit is unjust, both to the worker and to the nation as a whole; a State examination would make a distinct dividing line, whereas examination by the employer is conducted with a vision of the positions available. The workman's opposition to the physical examination comes from the fact that he has been taught to believe that it is an interference in his personal affairs, that he can be clean or dirty as he chooses, that he can he healthy or unhealthy, and that it is nobody's business but his own. The war has taught us, however, that the individual is no longer the unit and that all such propositions must be based on the greatest good for the greatest number.

Jan 6, 1919

By P. Payson

INTERGRANULAR corrosion in corrosion-resistant chromium-nickel steels has been widely discussed in the last few years. So far as the author knows, nothing has been published which definitely shows that this tendency can be eliminated, although suggestions have been made that a remedy is possible if certain specifications are satisfied. Strauss, Schottky and Hinueber1 suggested an increase in chromium content to an extent that would prevent the impoverishment of chromium on carbide precipitation sufficient to cause impaired corrosion resistance in the matrix. Pilling2 suggested an increase in nickel, so that the stability of the austenite matrix would be increased. Aborn and Bain,3 say that "intergranular attack-may be eliminated by preventing carbide precipitation (e. g., by lowering the carbon content or somehow raising its solubility) or by precipitating it permanently under conditions which will not remove chromium from solid solution so drastically at any points." In a later paper Aborn and Bain4 state that many different metallic elements, tungsten, vanadium, copper, aluminum, molybdenum, titanium and zirconium, have been added in small per-centages to increase the stability of these alloys, but that it has been reported that according to the copper sulfate test these added elements act only to retard the intergranular corrosion, and that increased nickel and chromium contents have similar effects. Newell5 showed that the lower the quenching temperature before reheating, the less severe was the intergranular attack.

Jan 1, 1932

By Takefumi Takuma, Masashi Nagano, Koji Kajino

As part of the construction of a multi-span pre-stressed concrete girder bridge for Japan’s new high speed rail line, landslide preventive piles were installed on the flank of a steep slope. The rotary pressin piling method was selected to install three parallel rows of long (up to 36m, i.e., 118ft) and large diameter (1,200mm, i.e., 47.2in) pipe piles safely into the slope as a deterrent measure. They were spaced at 2.5 Dia (3.0m, i.e., 9.8ft) on center and were staggered to allow the groundwater to migrate between the piles. Each pile had a sacrificial cutting shoe welded at its toe for speedy installation and was rotated and simultaneously pressed into soil on the slope through the stable bedrock thereunder to achieve a robust landslide prevention in a relatively short period of time.

By K. V. Konigsmann

"Mattagami Lake Mines Ltd operate a zinc-copper mine with an annual output of about 200,000 tons of zinc and 30,000 tons of copper concentrates. Zinc concentrates arc shipped to a company owned smelter in Valleyfield (a distance of 690 miles), for Export to Quebec City and also to Josephtown, Pennsylvania (1,060 miles, Figure 1.)The protection of concentrates in open gondola rail shipments has been a matter of concern since operations commenced. Considerable financial losses did occur at times because of wind erosion. Operating difficulties were also encountered by customers because of excessive moisture accummulation in the concentrates. Test shipments made in 1969 established the magnitude of losses in open cars. The results and subsequent investigations at our mines and elsewhere confirmed that load protection is an economic necessity.Many types of covers were experimented with, more or less successfully. In 1972 we agreed on a joint program with Dupont of Canada Limited. A new type of cover was developed by early 1973. It has been in use since, undergoing several improvements as experience accumulates."

Jan 1, 1975

By C. Droun

"Low back pains account for about 13 per cent of all compensation claims made to the Quebec Workmen's Compensation Commission and cost the employers a sum exceeding ten million dollars. The frequency and cost of these health problems in Quebec metal mines are proportional to the provincial trends. An elaborate review of the literature on the causes, nature and prevention of low back pain is made in this presentation. A prevention program for low back pain has been designed in cooperation with a team of seven medical specialists and two physiotherapists for the Quebec metal mines. The program is especially designed for persons who have had low back pain, in order to prevent a recurrence, and for persons beginning to feel chronic difficulties. It is based on existing programs at the Hawthorne Plant of Western Electric Company and at Minnesota Mining and Manufacturing, but it requires a much different approach because of the nature of medical care available at the mining sites. The program is difficult because it involves a change of attitude for every employee and every supervisor. The program, so far, is beneficial because several men are now seriously engaged in an active program of reconditioning and because the problem of low back pain ie beginning to be seen from a new angle."

Jan 1, 1973

By D. C. Van Aken, O. J. Rajtora

A research effort sponsored by the Department of Energy (DOE) and several steel producers, is investigating the benefits of coating steelcasting nozzles with various materials. Coatings were applied to casting simulation nozzles made from industrial tundish nozzles (primarily of magnesia) and industrial submerged entry nozzles (SEN's) (primarily of alumina-graphite) in order to extend casting time prior to nozzle clogging. Nozzles were coated by air plasma spray (APS) using a 9M series APS system from Sulzer-Metco. The ability of these coatings to provide protection from clogging was evaluated using a steel casting simulation. Substrate-coating compatibility was characterized using optical and SEM microscopy.

Jan 1, 2004

By G. L. Spence

Prevention of cuprous and cupric oxide formation on stored ETP copper rod is a major concern for copper rod and wire producers. During normal storage periods copper oxide layers can increase from less then 100 A to more then 1000 A exceeding ASTM specifications and discoloring the rod surface. Various types of corrosion inhibitors are tested and compared in effectiveness for prevention of copper oxide formation on stored copper rod. Aromatic triazole compounds are also compared to a non-azole containing compound.

Jan 1, 2007

By Jian Yang

The mechanism of resulfurization in the desulfurization process with magnesium vapor produced in situ by aluminothermic reduction of magnesium oxide was clarified in the present work. The influences of various operating parameters on the resulfurization were studied and the methods that could prevent resulfurization were proposed. There are two kinds of mechanisms of resulfurization in the desulfurization process with magnesium. One is decomposition of the desulfurization product of MgS under the inert atmosphere. The other is oxidation of MgS under the oxidative atmosphere. Under the present experimental conditions, lowering operating temperature and oxygen partial pressure in the atmosphere could effectively prevent the resulfurization. Adding CaO onto the melt surface was an effective method for preventing the resulfurization due to transformation of the desulfurization product of MgS into the more stable compound of CaS. Since addition of the activated charcoal powders greatly decreased the transfer rate of oxygen in the atmosphere to the melt surface, it also reduced the resulfurization remarkably.

Jan 1, 2006