Search Documents

By P. D. Kovscek

High-pressure streams of water, known as water jets, can be used to improve the cutting efficiency of mechanical bits. During prior testing by the Bureau of Mines, the cutting performance of a longwall shearer, equipped for water-jet-assisted cutting, was evaluated. The performance of the shearer did not improve while using water jet assist because the pressure of the water delivered to the rock surface was inadequate. The study, described in this report, resulted in a determination of the major cause of water pressure loss on the shearer, and an evaluation of the techniques for increasing the water pressure at the rock surface. The results show that the major pressure loss, which occurred between the nozzle and rock surface, is directly affected by the amount of fluid turbulence that develops just upstream from the nozzle. Preventing a sudden change in the direction of the flow channel can increase the stagnation pressure as much as 400 pct. Smoothing the surface of the flow channel in the shearer bit block would increase the stagnation pressure delivered to the rock surface by 35 pet.

Jan 1, 1989

By J. M. Gaines, C. H. Herty

IRon oxide (FeO) plays an extremely important part in the manufacture of steel. In the open-hearth furnace and the Bessemer converter it is the chemically predominant compound and controls to a large extent both the operation of the furnaces and the composition and quality of their products. Almost all of the refining action is carried out through the medium of FeO, which oxidizes carbon, manganese, silicon and phosphorus. At the end of any open-hearth or Bessemer heat the steel contains dissolved iron oxide, which must be wholly or partly eliminated. The type of deoxidation product depends on the amount of dissolved iron oxide and on the deoxidizer used. After the heat has been deoxidized and while it is being teemed, iron oxide diffuses from the ladle slag into the metal, causing losses of deoxidizer and increase in iron oxide content of the steel. It is generally believed that non-metallic inclusions are responsible for a great many failures of steel in service and for decreased yield of steel during rolling. The basis of most non-metallic inclusions is dissolved iron oxide. This investigation was undertaken in order to determine the amount of iron oxide that will dissolve in iron under various conditions. Steel-making slags are complex and it has been thought best to determine solubility under simple slags as a first step. The study is being continued under slags whose compositions approach those of operating slags Previous Investigations The solubility of oxygen in iron has been determined by a number of investigators (see Table 1) but their effort's have been directed toward the

By W. T. Millar

Graphite in the Suffern deposits near Hillburn, N. Y., consists of flakes ranging in size from fines to one-half inch in diameter. The Bureau of Mines investigated the Suffern deposits in the spring of 1943. Gneiss outcrops were examined, and five trenches excavated and sampled. The graphite is not confined to any definite zone but occurs in small, local pockets. Eleven samples were collected and combined for laboratory tests. Tests by the Bureau of Mines indicate that the graphite ore can be beneficiated by stage crushing, "skin flotation" of coarse flakes, and wet flotation of minus 10-mesh flakes. Over 90, percent of the graphite was recovered.

Jan 1, 1949

By K. K. Kelley

This report contains heat-content values for hexagonal crystalline germanium dioxide between 298.15° and 1,350° K., and for germanium dioxide glass between 298.15° and 1,800° K. experimentally determined by the Federal Bureau of Mines. No similar data for these substances are to be found in the literature. The heat-content and corresponding entropy-increment data are presented both in tabular form and by equations. Free energy of formation values are estimated for germanium dioxide glass at 298.15° and 1,800° K.

Jan 1, 1961

By N Taylor, P Hewitt

The Northern Beaches Storage Project (NBSP) is part of Sydney Water’s SewerFix™ Program to improve the wastewater system and protect public health and the environment. It was built by the SewerFix Wet Weather Alliance (the Alliance), a partnership between Sydney Water, RPS, MWH, Parsons Brinckerhoff and United Group Infrastructure.The project temporarily stores excess wastewater diverted from the Narrabeen Submain during wet weather. The project considered a below-ground storage facility, which involved constructing a deep tunnel from Brookvale to Fairlight, connecting into the Northside Storage Tunnel and a storage tank, which was subsequently adopted and constructed.The storage tank scheme included a pumping station and inlet and outlet pipes installed by microtunnelling. The storage tank site is in the Brookvale industrial area situated in an area of deep marine sediments overlying Hawkesbury Sandstone at about 30?m below ground. Microtunnelling for the inlet pipe was conducted from a 12?m deep jacking shaft. The jacking shaft and 14?m deep pumping station excavations were carried out from within secant pile earth retaining structures adjacent to existing buildings.Construction activities had the potential to cause settlement of the adjacent buildings. During excavation and microtunnelling the water ingress, adjacent groundwater level and settlement of the adjacent buildings were monitored. The monitoring data was assessed against an action plan, which modified construction activities as required to minimise the risk of damage to buildings from settlements caused by lowering of the groundwater table outside the excavations. The secant pile construction, excavation, microtunnelling and pumping station construction proceeded without incident or damage to adjacent buildings.This paper highlights that tunnel/underground options should be considered during options development, describes the original storage tunnel scheme and presents details of the successful microtunnelling and deep shaft construction adopted on the NBSP.CITATION:Taylor, N and Hewitt, P, 2014. Tunnelling on Northern Beaches Storage Project, Sydney, to improve water quality, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 451–458 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By E. J. Matson

The Little Castle Creek chromite deposit was examined in February and May 1941, respectively, by W. O. Vandenburg and O. H. Metzger, engineers of the Bureau of Mines. The Federal Geological Survey started a magnetometer survey of the area in November 1940 and completed its work during April and May 1941. Field work by the Bureau of Mines was conducted during May and June 1941. The purpose of the Bureau of Mines investigation was to search for a continuation of the chromite mineralization. The property at one time was the largest chromite producer in California.

Jan 1, 1949

By R. K. Hopkins

Fox a great many years fusion welding has been used in and around petroleum refineries, but it is only within six or seven years that the more important pressure vessels have been constructed by this process, because before that time the properties of fusion welds would not withstand such rigorous service. Since the adoption of fusion welding for the construction of this equipment, the refiner has required pressure vessels suitable for operation over a very wide range of conditions. On the one hand, vessels must operate at extremely high temperatures, in the range of 950° to 1000° F., and on the other vessels must be suitable for operation at sub-zero temperatures down as low as -75° F. Also, vessels are required suitable for operation at pressures upwards of 1000 lb. per sq. in., and as low as a 29-in. vacuum. In addition, vessels are required to withstand the attack of very corrosive mediums. It has been a rather difficult task for the fabricator to meet all of these requirements, but as a result of the extensive research carried on by steel manufacturers and several fabricators of class I vessels, practically all of these demands have been met. In order to meet the refiners' requirements for this wide range of conditions, the fabricator has worked closely with the metallurgist. This has enabled him to choose the proper base metal for each service condition, but it has been the fabricator's problem to develop a welding rod and welding technique, as well as a heat-treatment, that would produce in the welded vessel characteristics in and around the weld comparable to those in the base metal. Where corrosion is not a serious problem, and where the operating temperatures are not too high, ordinary carbon steel has served very well. But when corrosion is serious, and/or when the temperatures are either very high or very low, it is necessary to use some form of alloy steel to give satisfactory service.

Jan 1, 1935

By A. Noble

"In coal and mineral processing, several numeric parameters are used to quantify the separation performance of unit operations. For density-based separations, the partition curve is used as the starting point for many stages of diagnostic analyses. The curve is often quantified by its midpoint slope sharpness, and this single value is subsequently used for technical evaluation, benchmarking, and comparison. While this analytical approach does depict misplacement by relative density class, it inherently prioritizes middling separation and does not consider process economics or the micro-price value of individual classes. Alternatively, the organic efficiency parameter does consider process economics; however, it does not reveal information on the root cause of lost revenue or misplacement. In this paper, a new analytical approach is introduced which reconciles the technical misplacement data derived from the partition curve with the economic data derived from micro-pricing. The result is a new analytical procedure which reflects a better use of performance data. INTRODUCTION Partition curves are commonly used in the characterization, evaluation, and simulation of various physical separators. In mineral processing, partition curve analysis is routinely applied to hydrocyclones, screens, and density separators. Graphically, the partition curve depicts the recovery of particles as a function of a physical property on which the separation is based (e.g. particle density, size, magnetic susceptibility, etc.). Given the probabilistic nature of many real separators, the partition curve often exhibits a characteristic “S” shape (Fig. 1), similar to a cumulative normal distribution. Other geometric features of the curve are also depicted in Fig. 1, including the high and low closeout (or bypass) values, the midpoint slope, and the separation cut point (property value with 50% recovery). Partition curve analysis was originally proposed to evaluate coal washability (Tromp, 1937). Given the limited computational resources at the time, the analytical methods relied heavily on graphical construction and interpretation of the curve. Owing to the simplicity of the calculation and interpretation, many of these graphical approaches are still widely used for performance analysis today. The most common calculations are based on the slope of the partition curve at the midpoint. Increased slopes correspond to enhanced separation performance, since a perfect separation exhibits a stepwise transition from 0 to 1 at the desired cut point (i.e. an infinitely large slope). One common formulation of this slope, the Ecart Probable (Ep), is derived by evaluating the slope between the 25% and 75% recovery points:"

Jan 1, 2015

By R. K. Hopkins

For a great many years fusion welding has been used in and around petroleum refineries, but it is only within six or seven years that the more important pressure vessels have been constructed by this process, because before that time the properties of fusion welds would not with-stand such rigorous service. Since the adoption of fusion welding for the construction of this equipment, the refiner has required pressure vessels suitable for operation over a very wide range of conditions. On the one hand, vessels must operate at extremely high temperatures, in the range of 950° to 1000° F., and on the other vessels must be suitable for operation at sub-zero temperatures down as low as -75° F. Also, vessels are required suitable for operation at pressures upwards of 1000 lb. per sq. in., and as low as a 29-in. vacuum. In addition, vessels are required to withstand the attack of very corrosive mediums. It has been a rather difficult task for the fabricator to meet all of these require-ments, but as a result of the extensive research carried on by steel manu-facturers and several fabricators of class I vessels, practically all of these demands have been met. In order to meet the refiners' requirements for this wide range of conditions, the fabricator has worked closely with the metallurgist. This has enabled him to choose the proper base metal for each service condition, but it has been the fabricator's problem to develop a welding rod and welding technique, as well as a heat-treatment, that would produce in the welded vessel characteristics in and around the weld comparable to those in the base metal. Where corrosion is not a serious problem, and where the operating temperatures are not too high, ordinary carbon steel has served very well. But when corrosion is serious, and/or when the temperatures are either very high or very low, it is necessary to use some form of alloy steel to give satisfactory service.

Jan 1, 1935

By R. K. Hopkins

For a great many years fusion welding has been used in and around petroleum refineries, but it is only within six or seven years that the more important pressure vessels have been constructed by this process, because before that time the properties of fusion welds would not with-stand such rigorous service. Since the adoption of fusion welding for the construction of this equipment, the refiner has required pressure vessels suitable for operation over a very wide range of conditions. On the one hand, vessels must operate at extremely high temperatures, in the range of 950° to 1000° F., and on the other vessels must be suitable for operation at sub-zero temperatures down as low as -75° F. Also, vessels are required suitable for operation at pressures upwards of 1000 lb. per sq. in., and as low as a 29-in. vacuum. In addition, vessels are required to withstand the attack of very corrosive mediums. It has been a rather difficult task for the fabricator to meet all of these require-ments, but as a result of the extensive research carried on by steel manu-facturers and several fabricators of class I vessels, practically all of these demands have been met. In order to meet the refiners' requirements for this wide range of conditions, the fabricator has worked closely with the metallurgist. This has enabled him to choose the proper base metal for each service condition, but it has been the fabricator's problem to develop a welding rod and welding technique, as well as a heat-treatment, that would produce in the welded vessel characteristics in and around the weld comparable to those in the base metal. Where corrosion is not a serious problem, and where the operating temperatures are not too high, ordinary carbon steel has served very well. But when corrosion is serious, and/or when the temperatures are either very high or very low, it is necessary to use some form of alloy steel to give satisfactory service.

Jan 1, 1935

By Kelly F. Bailey

Introduction On June 20, 1986, the Occupational Safety and Health Administration (OSHA) published revised asbestos exposure standards for general industry and construction. The standards reflect OSHA's attempt to adequately control workplace exposures to minerals it considers carcinogenic - minerals capable of causing or contributing to cancer. These standards specifically identify asbestos as: chrysotile, an asbestiform serpentine mineral; and the amphibole minerals amosite, crocidolite, tremolite asbestos, actinolite asbestos, and anthophyllite asbestos. Each of these has a more common nonasbestos mineral analog that exists in nature in a crystalline, blocky shape rather than the hair-like or fibrous shape of asbestos. The mineralogical names for three of these nonasbestos minerals are unique: antigorite for chrysotile, cummingtonite-grunerite for amosite, and riebeckite for crocidolite. The other three nonasbestos analogs do not have unique mineralogical names. They are simply designated as actinolite, tremolite, and anthophyllite without the word asbestos following their names. The 1986 OSHA standards not only cover exposure to the six asbestos minerals, they also cover specifically the nonasbestos forms of actinolite, tremolite, and anthophyllite (AT&A). The new standards regulate these minerals exactly like asbestos (OSHA, 1986). The construction aggregate industry views this as a major problem because these nonasbestos minerals are common amphibole rock-forming minerals in the earth's crust. They exist in small quantities over large areas of the United States (Kuryvial et al., 1974). These minerals, unlike asbestos, are not mined for a specific commercial purpose. They are unavoidable components in much of the aggregate used for construction throughout the US. They are also common in the gangue material of metallic ores. There are areas of the US where amphibole-bearing bed¬rock is common. Not every rock mass in these areas contain amphiboles, however. It does mean, though, that amphiboles are physically compatible with many of the rocks in those areas. And given the correct geochemical conditions, they will be present primarily in the nonasbestiform variety. In addition, these amphiboles will probably exist in the natural drainage system, sand and gravel deposits, stream sediments, lake shores, valley basins, or ordinary beach sand within these areas. There has been little quantification of nonasbestiform AT&A in dusts and soils in the US. This is not surprising since these nonasbestiform minerals are not commercially valuable. However, an example of the pervasive nature of these minerals can be found in a 1981 Geological Society of America publication where about 0.7% tremolite-actinolite was found in the desert dust in and around Tempe, AZ (Pewe, 1981). Since OSHA standards treat these common nonasbestos minerals as carcinogens in the same way as asbestos, large natural areas in the US are implicitly being labeled as hazardous by OSHA. When a substance is identified as a carcinogen, another OSHA standard comes into play, the Hazard Communication standard. There are also right-to-know laws in 9 states that essentially duplicate this federal standard. These standards require that a product containing 0.1% or more of an OSHA-designated carcinogen be labeled as such (OSHA, 1983). This means that much of the stone and sand gravel products occurring naturally and mined in the US could be labeled a carcinogen when, in fact, they are not. The National Stone Association (NSA) and the domestic construction and mining industries believe that OSHA has seriously erred. The NSA has studied the health, mineralogical, technical, economic, and legal basis for OSHA's action. These studies concluded that there is no justification for the agency regulating nonasbestos minerals as if they were asbestos. Health issues The preamble to OSHA's 1986 asbestos standard states that evidence for asbestos-like health effects from exposure to nonasbestiform varieties of AT&A is inconclusive (OSHA, 1986). The fact is, not only are the data inconclusive, they are nonexistent. During 1986-1987, NSA's occupational health and epidemiology consultant, Environmental Health Associates (EHA), reviewed all available health studies related to AT&A. EHA found evidence that malignancies in both experimental animals and humans are associated with the asbestos forms of these minerals. No experimental or epidemiological evidence was found that indicated such pathogenic effects occur from exposure to nonasbestiform varieties of these minerals. There are relatively few scientific studies of the health effects of exposure to nonasbestiform varieties of AT&A. In three different animal studies, exposure to either nonasbestiform tremolite or actinolite did not result in pulmonary fibrosis on in excess tu-

Jan 11, 1988

By L. A. Panek

A new pillar strength formula is presented, incorporating a function P of size and shape, which takes into account the size-shape interaction effect as well as the enhanced strength exhibited by wide pillars. Existing pillar formulas, lacking these capabilities, are not suitable for extrapolating small-specimen test results to mine-pillar sizes and shapes. Interpreting compressive-strength test results as function of P clearly reveals wide-pillar behavior in much old test data. Model relationships are discussed, along with their scaling implications.

Jan 1, 1994

By K. Feledi

"A booster fan is an underground mechanical ventilation equipment installed in series with a main surface fan that is used to boost the air pressure provided by the surface main fan passing through it. As mining continues to expand and go deeper, the need for improved and efficient ventilation increases. This has led to the use of booster fans and other auxiliary ventilation devices in underground mines. This paper details experiments and results carried out at Missouri S&T Experimental Mine that investigated air leakage and recirculation caused by the use of booster fans. The results were compared with the situations where booster fans are used and not used.The variables considered were the booster fan blade angle and the fan combinations. Air quantity measurements were taken at each individual stopping under a number of scenarios and across four blade angle settings. The first set of situations examined were; the main surface Joy fan only running, the main Joy, and the west booster fan running, and the main Joy fan and east booster fan running. Observations were made which lead to the conclusion from the experimental analysis that booster fans affect the behavior of leakage and recirculation. The locations of the booster fan and the blade angle setting have the most effect on leakage and recirculation. To limit the potential for system leakage and recirculation, the location and size of a booster fan in a ventilation system should be thoroughly evaluated.INTRODUCTION Missouri S&T Experimental Mine ventilation system The Missouri S&T Experimental Mine has two shafts. One currently serves as the main intake shaft. Air is forced through the main shaft by a Joy Manufacturing Vane Axial fan and follows the direction shown on the map on Figure 1. The air is currently naturally exhausted through the Wheeler portal. As indicated on the map there are eight stoppings in the mine, with stoppings number 2 and 8 fitted with man doors. The mine also consists of three raises which are either fully or partially blocked, two portals with one acting as an exhaust and the other generally closed by a hydraulic Kennedy door."

Jan 1, 2015

By Mah Alla D.

Previously existing heat-of-formation values for the oxides of vanadium were rudimentary. They were subject to uncertainties of 1 to 5 kilocalories per gram-atom of contained oxygen. This fact has been the only adverse influence on the accuracy of thermodynamic calculations involving these substances, as the requisite entropy and high-temperature heat-content data are known with reasonable accuracy. This report presents new heat-of-formation data for four oxides of vanadium (VO, V203, V02, and V205), obtained by combustion calorimetry. It is believed that the uncertainties have been reduced to 0.1 to 0.3 kilocalorie per gram-atom of contained oxygen. The new heat-of-formation data were combined with existing entropy and high-temperature heat-content values to obtain free energies of formation of the four oxides at temperatures up to 2,000° K.

Jan 1, 1961

"With a total value to date of well over $200,000,000.00 for its ore production, the Tintic mining district, which is about 100 miles southwest of Salt Lake City, ranks as one of the three main ore producing areas of Utah. In it are located the biggest silver mines of the country, silver having been the chief metal produced in the camp since its start. Tintic's silver production to date has a total value of over $ 100,000,000, approximately half of the value of the camp's ore production, the balance being roughly divided among lead, gold and copper.Discovery of the camp was made in the late sixties. Lack of transportation and ore reduction facilities delayed extensive development of the area for nearly a decade.In recent years Tintic's ore production has ranged from 350,000 to 400,000 tons annually. In 1 924 the camp produced one-eighth of the silver produced in the nation with an output of 7,729,700 ounces. Its lead production was 77,765,000 pounds and its gold production 26,285 ounces.The known mineralized area of the district is found in a broad syncline striking north and south. The west limb plunges sharply and extends for a distance on its dip of approximately one and a half miles to the trough. The east limb raises gently through a distance of about two miles to the east limit of known mineralization. This general structure is broken by local faulting throughout the district, the local structural conditions playing an important part in the ore deposition. The north end of the fold is obscured by a rhyolite flow and the south end stops against a monzonite stock."

Jan 1, 1925

By W. D. Sinclair

"Between 1934 and 1956, nearly 31 million grams of gold were produced in the Matachewan area from deposits on properties belonging to Young-Davidson Mines Limited and Matachewan Consolidated Mines Limited. In 1979, production from these properties was renewed by Pamour Porcupine Mines Limited.Most of the gold produced has come from relatively lowgrade deposits (3.4 gl t or less) that occur in an east-trending belt of dykes and irregular bodies of trachytic syenite. Although small by comparison, these deposits have some of the characteristics of porphyry copper-molybdenum deposits. The mineralized syenite contains up to 5 per cent disseminated pyrite and is highly fractured and cut by quartz and quartzcarbonate veinlets. Gold occurs as native gold along fractures, in quartz veinlets and as minute inclusions in pyrite. Minor chalcopyrite and trace amounts of scheelite, molybdenite and galena are also present. Mineralization was accompanied by potassic alteration, consisting mainly of potassium feldspar.Some gold was also produced from small, but higher-grade, deposits in volcanic rocks. These deposits occur near the syenite-hosted deposits and consist of quartz veins and stringers mineralized .with pyrite and gold. Minor gold is present in some low-grade, porphyry-type copper-molybdenum occurrences and, locally, in large, isolated quartz veins.Lead isotope analyses suggest that the gold deposits were formed at about 2700 Ma and were locally remobilized at approximately 2400 Ma, following the Kenoran orogeny. The deposits appear to be genetically related to felsic magmas emplaced in an epizonal environment and deposited from hydrothermal solutions relatively concentrated in S and K20."

Jan 1, 1982

By C. A. Rowland

Wet grinding rod mills have been used for 50 years to grind ores and to make specification sand. The application of wet grinding rod mills is well understood. Until recently, there have been very few installations of dry grinding rod mills. The basic principles learned from wet grinding rod mills that were used in the application of dry grinding rod mills are 1. It is possible to extrapolate the performance of 5' and 6' diameter wet grinding rod mills into larger diameter rod mills with the larger mills performing as predicted. Wet grinding rod mills as large as 14' diameter (inside shell) by 20' long using 19.5' long rods are in use operating satisfactorily. 2. Wet grinding rod mills generally grind more efficiently when the fines are left in the mill feed than when the fines are removed from the feed. 3. Wet grinding rod mills produce little tramp oversize and generally can be operated in open circuit except when very close control on the top size in the product is required. When operated in closed circuit, the circulating load is normally less than 100%. 4. The power required for the desired grind can be accurately determined from the work indices obtained from rod mill grindability tests on the material to be ground. Where required it is necessary to, apply inefficiency factors for oversize feed and for larger or smaller than normal- ratios of reduction. Recent applications for rod mills have developed where it is required that dry grinding be used. These recent applications cover the grinding of 1. Lead sinter, lead slag and limestone. 2. Iron ore. 3. Silica for making glass sand. 4. Cement clinker. 5. Coke.

Jan 1, 1968

By J. Yianatos

The regrinding stage is necessary to achieve the particle size (liberation) for the final upgrade in the cleaning flotation process. At present, vertical mills (Vertimill) are employed at industrial scale, using small steel balls as grinding media. The regrinding process characterization requires mixing regime knowledge along with the mean residence time of the liquid and solid phases. The residence time distribution (RTD) and the actual mean residence time estimations from theoretical relationships are complex due to the presence of three components (solid mineral, balls and water), mass transport characteristics and segregation affecting solid holdup. Therefore, the experimental RTD determination is suitable for industrial mills. In this work, RTD measurements were performed in two different industrial flotation plants. Both plants operate with Vertimills of 1000-1500 HP in the regrinding process with different circuit arrangements according to the plant treatment capacity. The RTD was measured using the radioactive tracer technique. This technique allows for non-invasive tracer detection where the procedure consists of selecting a liquid (Br82 in aqueous solution) or solid (irradiated solid) tracer for RTD data acquisition in real time. The RTD was modelled by the Large and Small Tanks in Series (LSTS) model, which allowed the characterization of the different mixing regimes for both liquid and solids in the regrinding mills. Effective mean residence times in the range 2-11 min were obtained with RTD shapes similar to those obtained in tumbling ball mills. It was found that residence times of liquid and fine particles were similar, which is consistent with results observed in other mixing systems, e.g. mechanical flotation cells. Also, the mean residence times estimated from the RTD allowed the mass balance adjustment to be validated from metallurgical sampling data. RTD estimations are useful for better understanding the Vertimill behaviour and to identify the actual breakage rates. Keywords: vertical mill, residence time distribution, particle size, modeling

Sep 1, 2012

By J. LaForest, R. Riggle

In today’s challenging mining environment, everyone is focused on minimizing cost per ton. With haulage costs approaching up to 45% of the overall mining costs, and loader performance driving production, optimizing payload on the truck is a big opportunity. This paper will focus on technology’s role in loaders achieving the truck target payload. There are constantly new innovations in technology, but not everyone uses them correctly. Technology is intended to help achieve the next level of performance, but still requires the right people and processes to effectively utilize the benefits. In today’s mining business, miners, engineers, trainers, supervisors, and managers have ever increasing roles and responsibilities as never seen before in past decades. Technology can make these roles more efficient, but fully relying on the technology can detract from optimization. Sometimes the old-fashioned method of loading to a consistent pass match will provide a lower cost per ton. Before blindly trusting your technology feedback, know these three areas discussed in this paper: (1) Prerequisites to utilize technology in payload management; (2) Types of payload management technology; (3) How to use the data to manage operator behavior. The objective of this paper is to provide low-cost recommendations to efficiently increase production. INTRODUCTION Whether miners claim to have been around and experienced it all, or they are the data-driven new generation on the mine site, miners are expected to execute the mine plan at the lowest cost possible. So why is it so difficult to execute this task? Shouldn’t supervisors just have to staff the equipment, tell operators to have a safe day and tally up the numbers at the end of the shift? Let the technology system do the rest; what could go wrong? Lots. Having examined numerous mining operations that use the latest loading technologies over the past several years, one common denominator is the opportunity to improve loader operator performance. Mining companies seek help from consultants, training departments, performance reporting systems and an arsenal of resources. Armed with all this information, but the improvements don’t happen, what could have gone wrong? It comes down to people, not managing the resources to drive the right behavior and as a result, the mine’s performance is not where it should be. Understanding how to make “Great Miners” out of these people is critical to this constant struggle to move more with less and get the costs down. Extraction CPT (Cost-Per-Ton) is most sensitive to optimizing loader production which can be generalized into 3 categories of influence: machine specifications, cycle timing, and continuous management using technology. After establishing a basic production machine configuration, utilizing technology to manage cycle times, operator efficiency and payload can be advantageous. Prerequisites to Utilize Payload Management Technology It is important to begin with the primary considerations that enable the use of technology to continuously manage loading productivity. All systems are interdependent in mining, but these are divided into the simplest terms to remember. First, fix your timing and geometry.

Jan 1, 2019

By Frank Harwood Riddle

Products made from the ores of the sillimanite group, and synthetic substitutes for them, have unique properties, and service tests prove that they are playing, and will continue to play, a major part in improvements in metallurgical processes. Also, they are examples of how comparatively useless, rare, or "museum" minerals have been made available in commercial quantities. Until research developed uses for them, the minerals had been observed only in small, scattered masses, or crystals. Improvements in ceramic processes and compositions have come about very gradually. In the last 10 or 15 years, several outstanding developments have been made. Of greatest interest to the mining and metallurgical engineers are those affecting the composition, necessitating the mining of new minerals, and improvements in ceramic products used in metallurgical processes. Sillimanite and Mullite Sillimanite (Al2O3.SiO2), then known as Fibrolite, according to Dana,' was first reported in 1792. In 1796, cyanite (Al2O3.SiO2) was first described.2 In 1873, Behrens published results of his microscopic study8 of porcelain. He showed that it contained what appeared to be crystals, which dissolved less readily than quartz and glass in hydrofluoric acid. Hussak4 described the presence of needlelike crystals as occurring in some instances in small amounts in certain porcelains. In 1908, Plenske and Zoellner both studied porcelain structure.5 Plenske observed that "sillimanite" might be present in masses of exceedingly minute grains which apparently were amorphous. Zoellner advanced the theory that the needlelike crystals were formed by a molecular change in the clay,

Jan 1, 1932