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By Donald W. Mitchell

The fire hazard of neoprene, polyvinyl chloride, and rubber conveyor belts was studied at the Federal Bureau of Mines Experimental Coal Mine. The effects of intensity of ignition source, velocity of the ventilating air, and type of belt were investigated at three levels in small-scale gallery experiments. Studies were made in the mine on the effects on ignition and flame propagation of belt-entry dimensions, belt widths, and belt configuration. Methods for extinguishing belt fires were also investigated under simulated mining conditions, and during these trials coal dust and grease were placed on the belt. The research showed that conveyor belts will burn. Neoprene, polyvinyl chloride, and rubber belts, with and without carcass, ignited and propagated flame. The highest rate of flame propagation was obtained on rubber belt. The fire hazard increased with increase in intensity of ignition source and air velocity. Flame propagated only when air was forced through the test zone; propagation was not obtained when forced ventilation was not used, as would exist in a neutral entry in a mine. Automatic water sprays and high-expansion foam effectively arrested flame propagation; direct application of water and bicarbonate dusts was ineffective.

Jan 1, 1967

By John Platt, Mark Stephens

"When blasting is required in critical areas and anticipated shot movement and quick cleanup areessential to the success of the project it is extremely important to use the best technology available to achieve the goals expected by the customer. Wampum Hardware was given such a challenge in 2014-2015 when the PA Turnpike and New Enterprise Stone and Lime hired the company to do presplit blasting along the PA Turnpike. The face height averaged 45 feet (13.72m) and the shots had to be controlled to stop within 60-75 feet (18.29-22.86m) of the face or in this situation before they entered the travel lanes on the PA turnpike. In many if not most blasting environments, it is essential in controlling the movement of a blast, to make certain that the face holes are drilled at exactly the right place, with the proper amount and type of burden in front of and to the sides of the borehole. Profiling is an important first step to insure that the holes are drilled at exactly the right place and showing us the correct amount of burden in front of each and every drill hole."

Jan 1, 2016

By S. P. Kinney

[The blast-furnace operator is often confronted with the problem of determining the size of the materials which are used in the furnace burden. The statement is heard that the coke is larger or smaller or that certain ore is finer than that previously used. A screen analysis of the materials used gives a measure of the different sizes of materials in an aggregate. When one is fine and the other is coarse, the difference is obvious; but when the materials are of similar sire, it is more difficult to estimate the degree of finances or coarseness. In considering raw materials it would be desirable to be able to judge the size of the radio ideal materials entering the furnace and the burden as a whole, by one representative value, such as the average size of particle. Previous work by Perrott and Kinney3 developed a method for measuring the average size of particle in a mass of finely ground materials, and an attempt will be made to apply this method to the materials included in the blast-furnace charge and to the entire burden.]

Jan 1, 1930

CHAPTER 1 - GENERALIn the introduction to this chapter a general account is given of the growth of the mining industry in Western Australia from J88G, when the output of gold for the whole State was only £1148, to 1908, when: the output had risen to £6,999,885. In 1903 the output reached £8,770,719.It is quite evident that the discovery of gold in Western Australia was the means of opening up the road to broader industrial expansion, and it is doubted if any other portion of the British Empire more clearly exemplifies the nation-building forces of metalliferous mining than this State.The chapter includes an account of the following situation and history of the field.CHAPTER 2 - GEOLOGYIn this chapter the classification of the rocks of Kalgoorlie, but particularly those on the Golden Mile, is considered. Each rock is described in detail, and microphotos are shown to indicate the most important features in each type. As far as the Golden Mile is concerned, it is held that, notwithstanding the general chemical and more or less dynamical metamorphism which the rocks have suffered, it is possible to divide them into six groups...

Jan 1, 1912

By Gary W. Krantz

Fibered, portland-cement-based gunite products were applied in the Bureau of Mines Lake Lynn Laboratory Experimental Mine using a variety of pneumatic guns and gunning crews, The demonstrated wet-mix (with silica fume), dry-mix, and surface bonding products were sampled by the Bureau and subjected to a suite of engineering analyses. Gunite flexural and compressive strength, rebound, permeability, porosity, dust loading, shooting rate, crew requirements, and cost factors were evaluated. Steel, fiberglass, or polypropylene fibers were contained in all but two of the gunires tested. Both Bureau and private testing laboratory analyses are provided for some products. Electron probe micro-analysis and X-ray diffraction analysis were performed on the silica fume fraction of the wet-mix gunite to characterize the dust. Aggregate size fraction distribution analyses were performed to provide strength relationships. Results indicate that all of the commercially available fibered-gunite materials tested can provide beneficial sealant, spall prevention, or roof stability control attributes for underground mining environments when applied by an experienced crew using a well-maintained gun, in accordance with product manufacturers' recommendations and when used for the designated purpose.

Jan 1, 1984

THE township of Costerfield is situated in the parish of Costerfield, county of Dalhousie, and lies 6 miles east of Heathcote and 30 miles south-east of Bendigo. It is separated from Heathcote by the Mt. Ida Range, which forms the western boundary of the Silurian formation. It is situated at the head-waters of Tin-pot Creek, a small southerly tributary of the Deegay Ponds Creek, which flows east to the Goulburn River.The field was discovered in 1860 by two prospectors, Coster and Field, who were guided there by a shepherd, M Nicol Coster and Field had already discovered an antimony lode about three miles nearer Heathcote, when M Nicol offered to guide them to the larger outcrop. The main Costerfield reef at that time projected above the surface, and was white through oxidation, though the bluey sulphide showed on fracture. No alluvial gold of any consequence was obtained at Costerfield, but a little was obtained, at Redcastle, 7 miles to the north, and in some of the gullies to the east.Following its discovery there came a period of prosperity to Costerfield, while the mining operations were confined to the oxidized zone. The early success of mining at Costerfield was due to the gold values, and it is probable that the oxidized zone was secondarily enriched. The earliest available record of values is a crushing of Coster and Co. on the Antimony reef (now known as the Costerfield reef), when 200 tons from a depth of 70 ft. averaged 4 oz. per ton in July, 1861. At this time a crushing mill had not yet been erected at Costerfield, and the ore was carted and treated at Redcastle. The massive antimony ore, consisting of mixed oxides and sulphides, was separated by hand-picking as "marketable ore," and the remainder crushed for gold. A higher average is recorded from South Costerfield in September, 1861, when a 15' cwt. parcel...

Jan 1, 1922

By Woodcock J. T

When an aqueous suspension of pyrite and manganese ore reacts with oxygen, manganese is dissolved by the ferrous sulphate and sulphuric acid produced by the oxidation of pyrite. The kinetics of certain steps in the overall reaction were studied. A rate equation for the oxidation of ferrous sulphate by gaseous oxygen was derived for the temperature range from 1000 to 200° C. An exact rate equation for the production of ferrous ion from pyrite could not be established but it was shown that the temperature, oxygen pressure, pyrite surface area, and the reduction of ferric ion by pyrite are important. A rate equation was derived for the reaction of manganese dioxide with ferrous sulphate. A major facfor controlling the rate was whether or not ferric oxide was formed by hydrolysis at the manganese dioxide surface.It was shown that if hydrolysis was prevented the factor cpntrolling the rate of the overall reaction ,was the rate of production of ferrous ion, and little ferrous ion was oxidised by oxygen. When hydrolysis of iron did occur, the overall rate was not a simplefunction of anyone factor and much ferrous ion was wasted by oxidation with oxygen.INTRODUCTIONIn another paper (Cornelius and Woodcock, 1958) the results of the reaction of an aqueous suspension of a manganese ore and pyrite with oxygen are reported. It is shown that the ferrous ion and sulphuric acid generated in situ by the oxidation of pyrite, dissolves manganese as manganous sulphate. To obtain a better understanding of the process as a whole, the kinetics of certain steps in the overall reaction were studied.When an aqueous suspension of a manganese ore and pyrite reacts with oxygen, the overall reaction may be conventionally represented by equation (1) (Cornelius and Woodcock, 1958).2Mn02 + 2FeSz + 6i02 + 2HzO= 2MnS04 + 2H2S04+ F'ez03 ... , .. (1)

Jan 1, 1958

By Stephen H. Chung, Kevin Atherton

The main purpose behind this preliminary study was the reduction of costs while maintaining productivity. Finding a way to achieve this balance without compromising controls on safety and quality of blasting results is of continual interest to the mining industry and of particular interest when ore of lower grade is being mined.

Jan 1, 1998

By Ch. D. Taylor

Past studies with blowing face ventilation systems have shown that using a machine-mounted scrubber and water sprays can reduced methane levels at the face. The current research was conducted to determine how the sprays and scrubber interact to reduce methane levels, and what spray configurations provide the best face ventilation when used with a scrubber. Testing was conducted in a ventilation test gallery designed to simulate a full-scale mine entry. In the entry, a model mining machine, equipped with a simulated dust scrubber and water spray systems, was located at the face of a 6.1 m (20 ft) box cut. Face ventilation was provided by a blowing curtain located 12.2 m (40 ft) from the face. Methane released from a manifold at the face was measured at six locations near the face to compare the ventilation effectiveness of the spray systems while operating with and without the scrubber. Airflow movement across the face was affected by the spray configuration and scrubber operation. Average face concentrations were lowest when directed sprays were used with the scrubber. Varying the direction of the scrubber exhaust affected face methane levels.

By J. Noll

Many underground metal/nonmetal mines are using enclosed cabs on mining equipment to reduce the exposure of miners to diesel particulate matter (DPM). However, some enclosed cab systems may not be meeting their expected efficiency in capturing DPM, which could be a result of inappropriate filter use, cab leaks, or insufficient pressurization. NIOSH investigated several types of filters for reducing DPM to determine which type had the best capture efficiency. The laboratory results indicated that a MERV 8 (Minimum Efficiency Reporting Value, as defined by the American Society of Heating, Refrigerating and Air- Conditioning Engineers) filter captured about 50 percent of the DPM, a MERV 16 filter collected 96-98 percent of the DPM, and two HEPA (high efficiency particulate air) grade filters captured over 99 percent of the DPM. NIOSH also performed a field study to measure the efficiency of two cabs at a limestone mine. The cab filtration systems of a loader and haul truck were found to be over 90 percent effective in removing DPM except under certain operating conditions when the efficiency was as low as 41 percent. Evidence seems to suggest that these conditions were when a window was open in the cab.

Jan 1, 2011

By Don A. Toth

Until recently, the fire protection systems used to protect mining equipment were based on generically designed, off the- shelf concepts. These systems were reliant on single agent approaches and were generally comprised of a series of small twenty or thirty pound chemical canisters that would discharge their contents when triggered by thermal detection means. As the equipment grew in capacity, the logic used to increase the protection was to add more chemical canisters to the system. Hydraulic excavators and large-scale mining trucks grew dramatically in size into the 1990?s and beyond; with this growth came the increase in major losses due to fire. This was evidenced throughout this period, and continues to be of great concern today. During this presentation you will learn of the significant changes that have come about as a result of this history. Today, dual-agent products, infrared detection and unit-specific, engineered systems are the primary phrases used when discussing how to best protect this equipment from fire loss. This session is a must for anybody looking to optimally protect their equipment assets and for those looking to renew and/or secure new insurance for high value equipment in the future.

Apr 1, 2005

By Liqun Liang

Various nondestructive testing (NDT) inspection methods are available to evaluate the structural integrity of cast-in-place shafts. The widely used methods include Cross Hole Sonic Logging Testing and Low Strain Testing. Due to its advantages such as low cost, easy operation, quickness and flexibility (no need to plan ahead and prepare inspection tubes or other devices), Low Strain Test is frequently specified in quality assurance programs of many countries or when doubts arise as to the integrity of the finished shafts/piles. The method is well suited for small to middle sized shafts. However it is an indirect NDT testing method and has certain limitations. Data interpretation requires proper training, experience and judgment and, therefore, inconsistent conclusions and reporting may be provided by different testers. To avoid or reduce such inconsistencies, it is best to follow a standardized data interpretation and record classification system. In this paper, a new classification method is presented with examples. A step-by-step data evaluation and interpretation procedure is proposed with examples of real cases to help understand the LST data. The paper also makes recommendations for measures to be taken when anomalies are detected in tested production piles.

Jan 1, 2011

Several Approaches to Enhance the Bioleaching of Enargite Some approaches were investigated to enhance the recovery of Cu from enargite by bioleaching with Acidithiobacillus ferrooxidans using the galvanic interaction with pyrite and activated carbon, and with thermophilic bacteria, Acidianus brierleyi. Addition of pyrite initially enhanced Cu leaching by the Galvanic effect, but after that the formation of secondary minerals passivated the surface of enargite in inoculated batches. Activated carbon improved Cu recovery from enargite much better than pyrite, when it is contacted with enargite. Recovery of Cu from enargite has been recorded to at largest 2.4 per cent within 30 days in the presence of activated carbon when mesophilic bacteria were inoculated at 25¦C. The recovery of Cu from enargite was drastically enhanced by inoculation of thermophilic bacteria, Acidianus brierleyi, up to 60 per cent within 40 days at 70¦C and still not leveled off after 40 days unless the formation of Fe(III) precipitates occurred. After 40 days dissolved molar ratio of Cu/As is around 5.2, suggesting that metal-deficient sulfides and/or ferric arsenate might be formed on the surface of enargite.

Sep 13, 2010

By Khaled Morsy

In the past two decades, high horizontal stress has been attributed to many ground control failures. Most believe that entries parallel to the high horizontal stress is most stable and least stable when perpendicular to it. Entry stability decreases when the angle between entry and horizontal stress increases. The concept of 2-D stress shadow has been proposed for selection of proper panel orientation, often with mixed results. In this paper 3-D finite element modeling was used to analyze the stress distribution at the headgate of a longwall panel subject to high horizontal stress at various angles. It was found that the directions of induced principal stresses at the longwall face and headgate are independent of the panel orientation. The induced principal stresses concentrate or relief at headgate based on the panel orientation with respect to the directions of the induced principal stresses. Accordingly, only 3-D modeling can fully account for the effects of high horizontal stress on panel orientation. The paper illustrates in details the changes in orientation and magnitude of all three principal stresses around the longwall face and T-junction area as panel orientation changes.

Jan 1, 2006

By Lyman G. J

Magnetic separator operation in the recovery of magnetite in heavy medium circuits was studied by conducting a series of tests on a full size wet drum magnetic separator.The significant operational variables were found to be feed pan clearance, squeeze pan clearance, dry magnetite feed rate and separator drum speed. With feed and squeeze pan clearances optimized for typical primary separator operation, magnetite loss and concentrate specific gravity were found to be related in a regular manner to dry magnetite feed rate at any drum speed.A two component model of magnetite loss is proposed, relating total magnetite loss to losses in the feed pan and squeeze pan zones. The experimental curves relating magnetite loss to dry magnetite feed rate at the various drum speeds are interpreted in terms of the two component model.The magnetite particle size distribution in the separator was also examined. The tailings magnetite was found to be finer than the feed magnetite only when the dry magnetite feed rate was low, or immediately following the introduction of a new charge of magnetite when the separator was fed at an intermediate dry magnetite feed rate.

Jan 1, 1983

By Dan Jackson

9:00 a.m., June 28, 1983 MR. MORTENSEN: Good morning ladies and gentlemen. Again, it gives me great pleasure to welcome you to another session of the 79th meeting of the Rocky Mountain Coal Mining Institute. The thing again that has always been impressive are the activities that we've had so far. The success in the meetings has been delightfully encouraging to all of our committee people. Please welcome the chairman of the session, Charlie Margolf. MR. MARGOLF: Thank you, Vernal. Good morning, ladies and gentlemen. It would be my privilege to serve as the session chairman this morning. To allow the maximum time for our speakers, I'll turn the microphone over to Bernie Bernstrom who will introduce our first speaker. MR. BERNSTROM: Thank you. As Vernal mentioned, Dan Jackson will be our first speaker. He is the Western Editor of Coal Age Magazine. Dan really doesn't need an introduction to this group. He's belonged to the Rocky Mountain Coal Mining Institute about 25 years. Dan is a native of West Virginia and he's an ex-coal miner. He graduated form West Virginia University as an electrical engineer and worked for Amherst and West Bending Coal prior to employment by Coal Age Magazine. Back in 1972 Coal Age moved him to Denver from New York City. MR. JACKSON: When Vernal Mortensen asked me speak to the members of the Rocky Mountain Coal Mining Institute earlier this year I found it impossible to say no to the guy because of what he has contributed to western coal. Little did 1 know that the subject he had in mind would be entitled, "An Outsider's View of Western Coal." At first I asked myself-I've been associated with the coal industry for some 38 years, 12 years in national operations and 26 years reporting on it. You might say that I've been married to two industries, coal and the business press for 26 years, but today I'll put on my business press hat and try to make an impression of what an outsider might think of western coal. But at the outset, let's get one thing straight: When you say press, whether it's business press, the media or whatever, and you heard some comments yesterday as far as what the media has done .to this industry and there's been some definitions bandied around as to just what an editor is. One of the most recent ones has defined an editor as a person who can talk on any subject with an open mouth. Now that's not my case. Secondly, I don't give long talks. Several years ago I was giving a rather lengthy talk to a group similar to this and it was halfway through the talk when I noticed one guy on my right looking at his watch quite frequently. I didn't mind that too much because all of us do that once in a while, but when he looked at his watch, took it off and shook it, I thought, "My God, better cut short." But for more than a decade western coal has enjoyed substantial annual increases in production from some 30,000,000 tons in 1970 to some 264,000,000 tons in 1981, but 1982 was a different story. We lost about 6,000,000 tons of production in that year. In 1983 it's expected to be a little worse than '82. Coal historically doesn't rebound from a recession as quickly as other industries. It takes about eight to 10 months longer for us to really get moving again and I'm afraid that you'll still have to don your fighting helmets and flack jackets when you go out into the market to sell your product. Western coal, as you know, has problems and al l of them are not going away when the recession ends and they won't go away overnight. I'm sure most of you are aware of what those problems are. Carl Bagge and Jim Harris, along with other speakers, at this meeting have educated us well on those problems and I'm sure you'll hear more from Jim Watt at today's luncheon. If everyone in this room were asked to list three orfourof the most serious problems facing western coal, I'd make book that the total of the answers wouldn't vary by more than 3 to 5%, if that much. But coal is not the only mining segment in the U.S. with problems. Metal and non-metal mining has its share, too. I'd like to step back into the past for a few minutes, if I may, to a time when our problems were just beginning. Since 1979 a third of the nation's mines, including coal, metal and nonmetal have been shut down. The total volume of all mining in the U.S. in that year totaled some $24 billion. Today that figure has dropped some 21 %. The after tax rate on return for mining companies has fallen from 6'/% in 1980 to minus 3% in 1983. But that's really not where our problems began. They began 20 years ago when a profound change began taking place in the U.S. economy. Our economy had been growing at about 2'/-3% annually without exception except for the great depression. Our inflation rate was about I'/%, interest rates were running about 6%, and the federal budget was $77 billion, really great figures compared to today. From 1960 to 1980 the federal budget increased almost 1.000% and taxed paid by individual families increased by 700% during that same period. Despite the huge increases in taxes, the federal deficit kept getting larger and larger year after year and within this 20 year period the national debt climbed to a trillion dollars. Economic progress of this type can't continue indefinitely without some serious consequences. The result of that economy, well, you know what happened and there is a direct relationship of that

Jan 1, 1983

By J. Iannicelli

Kaolin, normally an inert filler when compounded with polymers, is converted into a strongly reinforcing pigment by prereaction with certain functional silanes. Modification of kaolin with amino and mercapto silanes allows it to form crosslinks and confers significant improvements in modulus, abrasion resistance, compression set and other physical properties of a broad range of polymers.

Jan 1, 1990

By W. E. Lockley

This paper will attempt to answer a number of questions which are important to the safe and continued operation of an electric power system. 1. WHY should electrical protective devices be tested? 2. WHAT devices should be tested ? 3. WHEN should they be tested ? 4. HOW should they be tested? 5. WHO should test them ?

Jan 1, 1977

By M. A. Reyes, L. Yan

Heat and humidity buildup within refuge alternatives (RAs) may expose occupants to physiological hazards such as heat stress. The Mine Safety and Health Administration (MSHA) regulations require RAs in underground coal mines to provide a life-sustaining environment for miners trapped underground when escape is impossible. RAs are required to sustain life for 96 h while maintaining an apparent temperature (AT) below 95 °F (35 °C). The National Institute for Occupational Safety and Health (NIOSH) tested a 10-person tent-type RA, a 23-person tent-type RA, and a 6-person metal-type RA in its underground coal mine facilities to investigate the thermal environment over a 96-h period. The test results showed that mine air and mine strata temperatures surrounding an RA occupied by simulated miners (SMs) increased over the 96-h test period. The test results suggest that RA manufacturers should consider this increase in temperatures when calculating and evaluating RA components during surface and laboratory tests. The findings can equip stakeholders with additional considerations for calculating the interior heat and humidity temperature profiles for occupied RAs not tested in situ

Nov 22, 2019

By Xiong Houjin

In the excavation works of some deep foundation pits within the boundaries of Guang­dong Province of China, though some measures, such as steel sheet piles, diaphragm walls, etc. were taken to protect the walls, the construction of the excavation works was often accompanied by damage of buildings and public facilities, surface settelment. sand boil and collapse of piles. When these happened, only chemical grouting could be used as the most efficient measure for rushing to deal with or rescue the emergencies. Besides, the application of chemical grouting protection wall technique also palys a very important role under the geologic conditions of the coastal areas of Guangdong Province, when applied in the mucky oystershell layer wealthy in water and the deep mud layer, it can not only achieve good results, but also reduce the cost significantly. In this paper, we discuss the water-tight and earth retaining functions of chemical grouting protection wall in weak formation, and introduce the applicable ranges of chemical grouting protection wall in the excavation of deep foundation pits. Some technological principles and design considerations of the construction of chemical grouting protection wall are presented. Different types of protection wall are also introduced.

Jan 1, 1991