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By William G. Pariseau, Michael K. McCarter

"The challenge of estimating mine-wide subsidence and linkages to seismicity over tabular deposits is addressed by a special finite element technique (dual node - dual mesh). Subsidence and mine-induced seismicity begins near the face when caving occurs and propagates to the surface as extraction reaches a critical extent. Thus, the challenge is to obtain details at the face at the meter scale and also at the surface over the whole mine at the kilometer scale. Interactions between old and new sections of a mine are automatically taken into account with this technique. The finite element method is well established technology based on fundamentals of physical laws, kinematics and material laws. With this technique, no empirical ""scaling"" or fitting computer output by input data ""adjustment"" to mine measurements is necessary. Capability is demonstrated for doing practical whole-mine subsidence analysis from first principles. Mine-induced seismicity is shown to correlate well with face advance and element failure.INTRODUCTIONSeismicity associated with coal mining has been under study for several years by a team at the University of Utah. Team members include mining faculty, research geophysicists and students from the Departments of Mining Engineering and Geology & Geophysics. Mines in central Utah that have been studied include the Trail Mountain Mine (Pariseau, 2015; Pariseau and McCarter, 2015), the Beehive Mine, also known as the Des-BeeDove (Pariseau, 2014), and the Crandall Canyon Mine (Pariseau, 2015). These mines were developed from outcrops in the Wasatch Plateau coal field west of Price, Utah, where the topography is characterized by . steeply incised canyon drainages and high plateaus with relief of a thousand meters or so.Seismicity associated with coal mining in central Utah has been of interest for many years and includes studies in the Book Cliffs to the east of Price, Utah, where mining is still active (Smith et al, 1974; Agapito, Goodrich and Moon, 1997; Arabasz et al, 2001; Arabasz et al, 2002; Fletcher and McGarr, 2005; McGarr and Fletcher 2005; Maleki, 2005) and to the northwest (Ellenberger et al, 2001). Results of many micro-seismic studies are summarized perhaps best by lannacchione, et al (2005) in stating, ""Deviations from normal strata response can provide useful stability information.""This study concerns a fourth underground coal mine in the southern portion of the Wasatch Plateau coalfield, hereafter referred to as the MINE. Focus is on mining from 2004-2008 with the objective of examining mining in relation to seismicity."

Jan 1, 2016

By J. R. Heberger

"The Safety Pays in Mining web application, developed by the National Institute for Occupational Safety and Health (NIOSH) Mining Program, helps mines determine the potential costs associated with mining injuries. This web app groups injuries by type, either by the cause of the injury or by the nature of the injury. When the user selects one of over 30 common types of mining injuries, the app provides information on the distribution of costs of workers’ compensation claims for that type of injury. Based on other user inputs, Safety Pays in Mining will estimate the total costs of the selected injuries, including an estimate of additional indirect costs, the estimated impact of total injury costs on mining company profits, and provide some examples of other items (services, equipment) on which companies could spend the savings that result from the prevention of injuries. This paper reviews the Safety Pays in Mining web application by discussing the development of the app, how it is used to show the true costs of mining injuries, and how mines can benefit from using this app. INTRODUCTION Injuries on the job cause pain and suffering. They can also profoundly affect profits and daily operations. In addition to paying direct costs or increased premiums for workers’ compensation insurance, a company might need to pay overtime for other workers to fill an injured worker’s job role, cover training costs for a replacement worker, or divert administrative resources in the wake of an injury. Safety Pays in Mining is a web app that estimates the distribution of these injury costs and assesses the impact that occupational injuries have on a company’s profits. The costs of specific types of occupational injuries in mining are not readily available as mining and insurance companies don’t usually share this information. As a consequence, companies only have cost information based on previous experience with their own employees. Therefore, if a mine never experienced a finger amputation for one of its miners, it would not be aware of the possible costs associated with this type of injury. In addition, injury costs are unique in that the cost distribution is so wide — with half of the injuries in our dataset having mean costs higher than 90th percentile costs — just using the average cost of a specific injury type does not provide adequate information. Some injuries involve immensely high costs, and even though the risk of these high-cost injuries occurring is low, mines need to be aware of their potential impact on their company’s financial health."

Jan 1, 2018

By K. L. Boyd

"Can the ever-increasing tonnages of ore and waste being mined today be accommodated simply by using bigger and better crushers? This paper reviews the latest primary crushing and large cone crusher designs. It highlights how—in addition to using the larger crushers now available—maximizing the utilization percentages in each of the four stages of the rock size reduction circuit will assist in meeting the larger production requirements of existing and new mining operations. Its goal is to help consultants and operators select the optimal equipment and custom-designed items in the material handling flowsheet from the mine to the mill, maximizing operating hours per year. INTRODUCTION Are larger crushers the answer to meeting the demands of existing or new mining projects for increased tonnage? Boyd (2002) predicted that larger crushers for primary and fine crushing would be beneficial and contribute to the further development of mineral processing. Larger crushers for primary and fine crushing applications are now available. The rock size reduction process from the mine to the selected milling process facility has not changed since man first broke a rock to get at the interesting mineralization within. The rock size reduction process circuit from the mine to the mill can be summarized in four stages: • Stage 1: Mining (rock breakage and fragmentation) • Stage 2: Pre-screening (scalping) • Stage 3: Primary crushing • Stage 4: Fine crushing (secondary, tertiary and quaternary) Plant throughput and ore delivery schedule will form the basis for flowsheet design and equipment selection. Once the project design criteria and the mine plan have been established, the circuit’s utilization percentage (percentage of hours when the circuit is being utilized) can be optimized for each of the four stages. The mining and process departments are the key stakeholders in the selection of the final comminution circuit, and both departments should be familiar with and contribute to the design of the circuit. This paper focuses on the four stages of a rock size reduction circuit from the mine to the mill, equipment selection, various ore and waste handling flowsheets, and improvements in crusher station design, all with the purpose of maximizing availability and plant utilization percentages. What is a large tonnage? From 1907 to 1914, the American Panama Canal excavated 300 million tonnes of material in 7 years (History of the Panama Canal, Wikipedia). Today’s large mining operations can move the same material in 10 months, using large crushers or multiple crushers for ore processing and large crushers and a mixture of truck haulage and conveyors for handling the large waste tonnages. Some examples include:"

Jan 1, 2017

By R. S. Wang

The flotation of pyrite which be pretreated by electrochemical ways under external controlled voltages in different pH is explored. The floatability of pyrite is increased indistinctively after being pretreated in acidic and xanthate environment; Whereas, it is increased obviously between 400~800 millivolt in alkaline and xanthate condition. The reason for higher recovery of pyrite is that oxida-tion reaction, which results in S0 and S02, takes place on its surface, and that ethyl xanthate is oxi-dized into dixanthogen. In the meantime, the kinetics and mechanism is also studied.

Jan 1, 2014

By A. P. Page, G. E. Alexander, L. L. Sirois, A. A. Winer

A knowledge of the electrical surface characteristics of minerals is all-important in the choice of treatments to up-grade and beneficiate them. At their solid-liquid contacts, there are transfers of ionic species, which for insoluble oxide minerals are the H+ and OH-ions. The adsorption density of these ions can be detected by carrying out potentiometric titrations, and this paper describes the automation of such an apparatus. The details are discussed fully and the validity of the method is demonstrated by flotation tests.

Jan 1, 1969

By X. Xie

The dissolution behavior of palladium powder in thiourea solutions has been studied. The variables studied included temperature, stirring speed, and concentrations of thiourea, acid and ferric ion. Palladium was found to be soluble in thiourea solutions in the presence of an oxidant such as ferric ion. The dissolution of palladium in thiourea solutions was found to be chemical reaction controlled with an apparent activation energy of about 2S.3 kJ/mol.

Jan 1, 1995

By J-g. Cui, X-b. Guo, J-j. Wang, J. Qiao, H. Tian

"Rare earth elements have unique properties because of the special electronic structure. In this paper the improvement of refractory material performance by the light rare earth oxides was introduced. The experiments showed that adding a bit of rare earth oxide could obviously improve the performance of the refractory material. INTRODUCTIONIn recent years, refractory materials are widely applied in the steel smelting process as a ladle lining material. In China, although the total production of fire-proof material exceeds normal demand, but the quality and variety of fire-proof material still have a big gap with world advanced level. A number of refractory products need to be imported from abroad. With the rapid development of domestic steel production, the ladle lining with refractory is gradually running after the world advanced level on production technology, production variety, and quality level. It replaces some imported products meeting the needs of the development of the iron making production. Therefore, there is an important significance to research on solving the problems of the ladle refractory reasonably and avoiding or reducing blind and not proper use of the imported refractory ( Jing, 2007).On the other hand, rare earth oxide has some special excellent properties. Firstly, they are very good refractory materials with their high melting point;Next, they have good resistance to water and alkali resistance function;Thirdly, it is easy for rare earth oxide to generated composite oxide reacting with other metal oxide,achieving the purpose to improving the material properties (Xu, 1978; Diao, 1979). China has a variety of rare earth resources,and rare earth resources is more advantageous in Baotou,taking up about 36 percent of world reserves,which is the world's top of rare earth mineral. In recent years the rare earth products output has risen sharply and many varieties and specifications have appeared. So it is necessary to study the new field of rare earth compound to open up new markets. Thus, it has a very vital significance to promote the further development of rare earth industry, adjust the rare earth products structure, ease the contradiction between supply and demand, and improve refractory products quality and grade in order to better serve the main body production.I In this paper, the experiments are mainly for 210 tons of Al2O3-MgO style series refractory materials belong to ladle lining bag from Baotou Iron & Steel Group Corporation Sheet Factory. The improvement to the effect of refractory material performance is explored by using light rare earth oxides as additives."

Jan 1, 2012

By Robert Dickson

Princess colliery is operated by Old Sydney Collieries, Limited, a direct descendant of the General Mining Association of London, England, which, in the first quarter of the nineteenth century, pioneered in coal mining in Nova Scotia. The coal worked is a 5 ft. 6 in. seam known generally through the Sydney coalfield as the Harbour seam but referred to locally as the Sydney Main. Entry is made by shafts, 680 feet deep, sunk in 1871 on a headland forming the northern entrance to Sydney harbour. From them extend the main roadways of the colliery, a distance of 700 feet to the shore line and a further distance of 14,700 feet in submarine areas to a total length of 15,400 feet. It was the first colliery in Nova Scotia designed to work submarine areas. Lateral development extends across a frontage of 16,000 feet and the submarine area from which the coal has been extracted is slightly over 6 square miles. There yet remains sufficient territory ahead of the workings to assure a future life to this colliery estimated at over 80 years at the current rate of production. In this area the seam dips at 6 to 7 per cent and face workings have reached a depth of 1,690 feet below the sea level. Until 1923 extraction of the coal was by room-and-pillar, followed by the drawing of the pillars. At that date the superincumbent strata had reached a thickness of 1,400 feet, resulting in heavy weighting on the roof and severe side pressure on the coal ribs. In combination with a soft, heaving pavement this created a set of conditions involving great difficulties and expense in keeping open places driven in the solid sufficiently long to permit recovery of the coal in the pillars by methods and equipment then available. The operator was forced to resort to extraction by longwall as the only economical method of winning the coal.

Jan 1, 1948

By D. J. Xue

Four kinds of coal-rock combination were subjected to three kinds of stress waves in the SHPB numerical simulation. The wave propagation and the changes of the strain energy in the coal-rock combination during the dynamic impact process were recorded as well as the contact force. The dynamic response law of coal-rock combination was obtained. It was found that the coal had better reflectivity than the rock because of coal with larger impedance. In contrast the rock had better transmissivity. As the crest value of the incident wave increased, the increment in the crest value of the transmitted wave weakened in the coal-coal group, coal-rock group and rock-coal group, in contrast, the increment in the rock-rock group increased.

Aug 1, 2013

By François Tremblay

It is well known that removal of organic material such ,as Jacquer, paint, plastic prior to melting improves aluminum recovery. In addition to being an important economically, decoating of aluminum scrap has a positive impact on the environment, through better control of gaseous emissions. Most of the existing thermal decoaters for aluminum have been designed to operate with scrap containing a level of organic material lower than 10%. The main field of their present application is for recycling of used aluminum can, where levels of organic material are lower than 4%. Alcan has recently developed a new thermal decoating system in order to extend applications of this process to a much wider variety of aluminum scrap. The new decoater efficiently processes aluminum scrap with a level of organic material up to 50%. This new technology features the use of fluidized bed technology to thermally control the process. This innovative feature improves both performance and control over conventional delacquering systems based on hot air convection. This paper describes the basic principles of the technology and the design of the? first industrial unit commissioned by the Alcan Recycling plant in Shelbyville (TN) at the beginning of 1994. Typical applications and operating advantages are discussed.

Jan 1, 1995

By V S. Vutukuri, K Shariar

This paper present a modification of selected strength criteria for coal and rocks containing weakness planes. The three strength criteria, namely, Murrell (1965), Bieniawski (1974a, 1983) and Hoek and Brown (1980) have been assessed for coal (containing weakness planes) by using triaxial strength tests. Triaxial test results indicated that the strength of coal specimens depends on the weakness plane inclination with respect to the principal stress direction. However it is shown that with increasing confining pressure, the effect of weakness planes inclination on the strength of coal specimens is reduced. The constant parameters in the three failure criteria for coal are determined for each weakness plane inclination by using the Datafit computer program (nonlinear regression analysis) and the results are compared with other rock types.

Jan 1, 1999

By Jing Zhang, Qing Xiao, Xulong Liu, Qiuju Li

"Pickling sludge generated from stainless steel production process contains large quantity of Cr, Ni, and Fe. The disposal of and fill sludge directly not only leads to the heavy metal dissolves in the soil and underwater, but also loss value metals. However, the major mineral phases of value metal are hydroxides and there are lots of calcium fluoride and water in the sludge. So the pickling sludge has to be pretreated before reduction-magnetic separation. The TG analysis, reduction reaction and magnetic separation were all used to study the pickling sludge. The result indicated that up to 900°C the total weight loss of pickling sludge was 22.32%. The mass contents of Fe, Cr and Ni in the tailings (non-magnetic) were 4.27%, 0.067% and 0.041% respectively.IntroductionSince 21st century, the stainless steel production in the world has been continuously increasing because of its excellent performance [1]. However, high stainless steel production means a high pickling sludge production. For example, in a stainless steel plant with waste water quantity of 100m3 /h, the production of pickling sludge will exceed 15 Kt/a. Pickling is essential for generating of a homogeneous and corrosion-resistant surface during stainless steel production subsequent process. Pickling of stainless steels is predominantly carried out with an aggressive solution, sulfuric acid H2S04 or composed of nitric acid HN03 and hydrofluoric acid HF [2]. During the pickling process, the pickling acids are recovered through ion exchange and metal ions such as Fe3+, Cr3+ and Ni2+ get into the acids forming the pickling waste water [3]. Then, the pickling waste water is precipitated with lime, forming pickling hydroxide sludge. It is not feasible to recycle or treat the pickling sludge using conventional methods, because the sludge has high contents of calcium fluoride and water but low contents of iron, chromium and nickel. However, it would also pose a potential environmental problem if deposited outdoors over a long term because it contains heavy metals such as Cr and Ni. At present, solidification/stabilization (S/"

Jan 1, 2014

By E. Krystad, G. Tranell

"The kinetics of boron removal from liquid silicon during slag refining, as a process step in the production of solar grade silicon, has been investigated by means of small scale mass transfer experimental series at 1600°C, using a graphite crucible. The slags were SiO2-CaO based, with or without addition of approx. 19 wt% MgO. Experiments were carried out at slag-metal ratios of 1 or 2, where the silicon initially contained approx. 250 ppm boron. The metal-slag mass transfer coefficients for boron were found to be in the order of 1-3 · 10-6 m/s and were largely influenced by slag composition. The mass transfer rate was higher for the MgO-containing slag than the slags without MgO. The final equilibrium distribution of boron between metal and slag, LB, was determined to be in the order of 2.3-3.3.I. INTRODUCTIONRecent years have seen a race in industry and research aimed at obtaining a reliable metallurgical route for production of silicon for solar cells (SoG-Si) from metallurgical grade (MG) silicon. Metallurgical routes can successfully challenge the traditional chemical routes for production of SoG-Si if they generate metal of sufficient purity while being less expensive in terms of production cost and energy consumption. Efficient removal of boron is one of the greatest obstacles in the refining of silicon by a metallurgical route, because the segregation coefficient of boron in silicon makes directional solidification unfeasible; in addition, the vapour pressure of boron is not high enough for removal by vacuum refining. However, the thermodynamic properties of boron makes removal from silicon by oxidation possible, and thus the process of slag refining of silicon has been receiving increasing attention as a method for boron removal."

Jan 1, 2012

By William J. Miles

The markets and applications of Wyoming bentonite deposits are primarily determined by the functional properties of a bentonite ore which results from the unique mineralogy and chemistry of each deposit. Commercial bentonite products contain sodium montmorillonite as the major mineral component, with minor concentrations of accessory minerals such as quartz, opal (silica hydrate), mica, feldspar, gypsum and zeolites. The chemical composition of the sodium montmorillonite influences the functional properties of the bentonite in significant ways. The type and concentration of various accessory minerals also influence the acceptability of the bentonite in each market.

Jan 1, 1995

This study examines the surface alteration and flotation behaviour of synthetic moncheite, PtPd(BiTe)2, in the presence of pentlandite. The telluride minerals contribute around 20% ~ 30% and up to 45% of the PGM present in the Platreef ore and are considered to be slow floating as there is evidence of these minerals reporting to the tailings. It was proposed that oxidation products from other minerals and grinding media would affect the mineral surface composition and floatability thereby causing inadvertent depression of moncheite due to precipitating ions. ToF-SIMS analyses (time of flight secondary ion mass spectrometry) was used to characterise the mineral surface as well as the extent of surface alteration. Microflotation was used to deter-mine the hydrophobicity of the synthetic minerals. Conditioning of moncheite in the presence of pentlandite reduced the flotation response of the + 38 -106µm size fraction from > 99% to 56%. This was due to pentlandite dissolution products (iron and nickel hydroxy species) which formed overlayers on the mineral surfaces thereby inhibiting the adsorption of collector. In addition, further grinding of these samples, with and without pentlandite conditioning showed a negative effect on recovery due to the fineness of the particle size distribution and there was no advantage gained from any possible exposure of fresh sites in the sample.

Jan 1, 2014

By J. M. Mutmansky

This paper outlines patterns of methane emission in both longwall and room-and-pillar operations and the effects that these patterns have on the decision as to whether the methane is most economically handled by ventilation alone or by means of a methane drainage system in addition to ventilation. The costs of handling the methane in the ventilation system and the costs of implementing the methane drainage system will be discussed as well as the costs related to the production of coal. The important issue of production slowdowns and gas outs will also be discussed as well as the proper response of mine management to such a situation. Suggestions concerning the keeping of production records related to methane problems will be made as well as justification for more intensive economic analysis of coalbed methane extraction and utilization.

Jan 1, 1998

By F. W. Brown

In 1942 the Explosives Division investigated electrostatic hazards associated with the manufacture, storage, and use of explosives. A report was issued in 19454/ presenting the data on the spark sensitivities of explosives. In 1948, the apparatus was redesigned and rebuilt to make the routine testing of explosives safer and more convenient. The rebuilt apparatus is described in this re-issue of the former report. Included are details of construction and a list of parts. PRINCIPLES OF METHOD In normal procedures without special precautions, it is possible for static charges to be accumulated on individuals or on ungrounded equipment or structures.5/ Static charges may be produced in many ways, but they are most commonly produced by rubbing or successive contact and separation of unlike surfaces, at least one of which is usually an insulator.

Jan 1, 1953

By R. T. Swinderman

This paper discusses how many of the common practices in conveyor specification and design are out of date compared to the current expectations of users for safe, serviceable, reliable, and fugitive material-free conveyance of bulk solids. Ten of the most common mistakes made in the specification and design stages related to user expectations are reviewed along with the cost vs. price implications of those decisions. A general specification and design hierarchy that designers can use to improve conveyor design is included.

Jan 1, 2010

By Chetan P. Malhotra

This paper describes an online control system and simulation environment for reheating furnaces. The system can be configured for implementing manual control as well as automatic control using either look-up tables or online model predictions. The simulator is also used for offline generation of optimized normal operation and delay setpoints for look-up tables and generating ideal heating curves for model-based control. Finally, it is employed to compare the performance of the above control strategies over a typical period of operation of a pusher-type reheating furnace. Keywords: Reheating furnace, control strategy, model-based control

Jan 1, 2003

By L. C. IlsLey

"There are two general classes of accidents that prevail in and about mines, namely - (1) those that through the nature of mining work can only be lessened, and (2) those that by proper precaution can be eliminated altogether. Explosive accidents that ordinarily take place while explosives are being transported in and about mines belong to the second class, that is, by proper care all such accidents can in general be avoided.The following table gives a brief summary of several accidents and disasters that have occurred in the United States and indicates the need of universal preventive measures as a basic part of all State regulations.ACCIDENTS AND DISASTERS OCCURRING WHILE TRANSPORTING EXPLOSIVES.***"

Sep 1, 1923