Search Documents

By G. E. Slagel

On August 3, 1987, a hearing was held by the House Subcommittee on Energy and the Environment to commemorate the tenth anniversary of the Surface Mining Control and Reclamation Act (SMCRA). Four panels of environmental/citizen group representatives went before the Subcommittee to report on the state of affairs (from their perspective) of the coal industry and the Office of Surface Mining, Reclamation and Enforcement (OSMRE) As expected, these groups had little positive news to report and continued to focus on glaring deficiencies within the surface mining program. They indicated that gross abuse of SMCRA has continued over the past ten years and the states have performed poorly. Congressman Udall's opening comments perhaps best characterized the mood of the group with his statement that "The Act has not accomplished what I or the people of the coalfields had hoped." and " ? a segment of the coal industry has continued in its bitter and implacable opposition to the most basic of environmental controls."

Jan 1, 1988

By Haldane J. S.

(Paper presented at the Institution of Mining Engineers' general meeting held in London on 8th June 1916.) It was shown in the last Supplement to the Registrar-General's Reports, in connection with the census of 1901, that the general death-rate among colliers was considerably lower than in the great majority of occupations but that there is an exception to this in the case of colliers above the age of 55. Examination of the statistics finds that the excessive death-rate among old colliers is to a large extent only apparent, and that the real excess of bronchitis from which they have suffered has greatly diminished. It is concluded: (1) that good ventilation is of considerable importance to the health and continued working efficiency of miners, as well as to their safety from accidents; and (2) that there is no real statistical evidence of harm resulting from the inhalation of coal-dust or shale-dust in the quantities ordinarily breathed by miners, and a strong presumption that the dust they breathe protects them against serious dangers from bacilli that are removed from the lungs by the dust-clearing cell mechanisms

Dec 1, 1916

By Keith Gordon

The recent discoveries of hydrothermal activity in the ocean off New Zealand have created interest in the business community in the commercial possibilities of mining associated marine polymetallic sulfides. This interest is more so, as this hydrothermal activity is in much shallower depths, between 120 ? 1800 meters, than the typical 2400m in other parts of the oceans. Mining for other ocean deposits around NZ, such as phosphate nodules and off-shore deposits from gold bearing river beds is also attracting interest. The question is: - how can these deposits be mined without spending the enormous sums of money required for specialized mining technology? There are no dedicated off- the-shelf systems designed exclusively for underwater mining. Such systems require expensive development and manufacturing processes and then, are most probably designed for only one specific purpose. The costs involved place such equipment beyond the means of smaller entrepreneurial groups and only the big companies have the resources required. However, large companies are normally reluctant to take the risk of investing large sums of money into deep ocean projects. Australia and New Zealand, until recent times, have been somewhat isolated from European and North American technical resources - especially in the field of underwater technology. Over the past century such isolation has often led to solving problems with what has become locally known as ? ?the number 8 gauge wire method?. This approach to problem solving entails using whatever is available to get the job done and keep costs down. In the old days with NZ technology being mainly based around farming, a piece of No. 8 gauge fencing wire, although not designed for the purpose, was often used to fix various problems ? hence the term.

Jan 1, 2002

By D François-Bongarçon

The link between geostatistics and Theory of Sampling (TOS) is examined again in view of new findings made while trying to compare predicted sampling variances and estimated grades (using geostatistics) on the same material, and this provides an important consistency requirement whenever calculations are made that involve both theories in a comparative way. It also briefly explores the relationship to De Wijs fractal model of mineralisation and eventually provides new support for the use of consistency theory for calibrating TOS variance formulas.CITATION:François-Bongarçon, D, 2017. Theory of Sampling and geostatistics – the ultimate link, in Proceedings Eighth World Conference on Sampling and Blending , pp 391–394 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Ruddle R. W.

Magnetite occurs in the reverberatory furnaces, blast furnace and converter (a) as the result of its presence in the materials charged, and (b) as the result of oxidation of the FeS in the charge in the absence of sufficient SiO2 to slag the FeO as it is produced and thus prevent its subsequent further oxidation. Magnetite is reduced by FeS according to FeS+3Fe3O4=10FeO+SO2 and similar reactions. This reaction is markedly affected by temperature and does not proceed to any important extent below about 1200°C. To ensure comparative freedom from magnetite it is therefore necessary to raise the temperature of the furnace to the highest practicable figure and to use plenty of siliceous flux. Since the maximum operating temperature is likely to be limited by the resistance of the refractories to attack by the slag, investigation of the factors affecting this attack should be helpful. It is reasonable to suppose that the formation of magnetite might be minimized by ensuring intimate admixture of matte and slag during conversion so that silica is readily available for combination with ferrous oxide as the latter is formed. The literature gives no clue to the importance of this factor and some experimental work on this aspect might be fruitful

Jan 1, 1953

By Dany Pelletier, Yeves Breau, Ahmed Bouajila, Claude Gagnon

"In flotation circuits, direct measurement of the volumetric flow rate delivered by electromagnetic flowmeters is often difficult to obtain particularly due to piping and flow constraints. However, on-line material balance calculation could offer a reliable alternative to flow rate sensing. This paper describes an on-line material balance software package as applied to a copper flotation circuit for mass flow rate estimation mainly based on the output of an x-ray fluorescence onstream analyser. Rule-based procedures for the management of the main calculation modules are designed and integrated to a Comdale expert system. Attempts to diagnose the flotation process from mass flow rate data are also discussed.INTRODUCTIONThe need for improved process diagnosis, control and optimisation has become more evident for the mineral processing industry in the last decade. Therefore, new process variables need to be inferred or measured particularly in highly multivariable processes such as flotation. This process is subject to a wide variety of disturbances mainly generated by frequent and sometimes abrupt changes in physical and chemical characteristics of the ore and due to some irregularities in manual process operating procedures.A flotation circuit scheme is always a complex network counting more than two dozens of slurry streams. Information about those streams (%solids, metal content analysis, and flow rates) are important for process diagnosis, performance evaluation control and optimization (1,3).On-line sensing instruments such as x-ray fluorescence (XRF) on-stream analysers (OSA), gamma density gauges and electromagnetic flowmeters have been developed for the measurement of those variables. Unlike the other variables, stream flow rates could be determined by different ways:"

Jan 1, 2000

By H. E. Urtubia, C. W. Bailey

"BHP-Billiton’s Minera Escondida Limitada is one of the world’s largest copper producers. It treats a combined 88 million tons of copper ore per year through its two concentrators: Los Colorados and Laguna Seca. Over the past three years, metallurgical sampling has been performed at the Laguna Seca concentrator to calibrate both the JKSimMet and JKSimFloat grinding and flotation simulators. In the past, the calibrated simulators have been used to predict the effect of changes in operating conditions in the grinding and flotation circuits separately. To assist in the development of future processing options, predictions were required of the effect of changing grinding circuit conditions on flotation performance. This was achieved by using an integrated grinding and flotation simulation. The grinding circuit performance was predicted under different operating conditions (such as tonnage rate and product grind size) using JKSimMet, and these results were then used in JKSimFloat to predict the flotation performance for the new grinding circuit product. This combination of the simulators allows both the effects of residence time and grind size on flotation performance to be investigated.This paper presents the first combined grinding and simulation modelling and simulation case study using JKSimMet and JKSimFloat. The modelling and simulation methodologies for the grinding and flotation circuits are discussed along with the circuit simulations that were performed. The simulator predictions are presented in conjunction with independent laboratory results of the new operating conditions. The ability to predict flotation circuit performance based on changes in grinding circuit performance is also discussed. This methodology provides improved predictions of flotation circuit performance when grinding circuit changes (including grinding capacity increases) are made.INTRODUCTIONOver the past decade, the grinding and flotation research groups at the Julius Krutschnitt Minerals Research Centre - JKMRC (Brisbane, Australia), University of Cape Town (Cape Town, South Africa) and McGill University (Montreal, Canada) have been developing a methodology for optimising grinding and flotation plants using actual plant data together with semi-empirical sub-process models. The project is being conducted as part of the Australian Minerals Industry Research Association (AMIRA) P9 Project, titled “The Optimisation of Mineral Processes by Modelling and Simulation”. The project first commenced in 1962 and is currently in its “Nth” phase."

Jan 1, 2007

By H Zhang, A Lawrence

To accommodate the fast growing need for services in Singapore’s Marina Bay downtown area, Marina South, the construction of a common services tunnel (CST) was required. The CST includes various services such as telecom cables, power lines and water pipes. A deep excavation and temporary earth retaining system (TERS) was required to facilitate the construction of the tunnels. Marina Bay is reclaimed land over thick soft marine clay which is likely to be still consolidating. The deep soft marine clay poses a big challenge for deep excavations in downtown areas where highways and sensitive structures are close by. This paper presents a case study of part of the CST Phase 1B and 2 at Marina South, in particular a 26 m deep excavation supported by a 46 m diameter temporary caisson. The construction started in late 2006 and the basic structure was completed in early 2011. The caisson was formed by 1.0 m thick overlapping diaphragm wall panels with a capping beam and three ring beams at different depths. Two-dimensional finite element analyses were conducted to predict the ground settlement, lateral displacement, bending moment and hoop stresses in the diaphragm wall and ring beams during different excavation stages. A comprehensive instrumentation and monitoring scheme was established to verify the design predictions, control excavation safety and trigger the contingency plan to protect public safety. The impact of construction activity, unbalanced temporary stockpiles and adjacent deep excavation for a mole removal will be discussed.CITATION:Zhang, H and Lawrence, A, 2014. A case history of a deep excavation in a big circular shaft in Singapore marine clay, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 581–588 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By K. L. Woodruff

Shredding is the usual first step in processing municipal solid waste (MSW) for resource recovery. This unit process requires high capital cost and, usually, considerable maintenance cost. In addition, some shredders at times will render certain components of the MSW in a form difficult to recover. This is particularly true in the way metal cans are distorted and the way glass is pulverized. A trommel screen was proposed (1) to pre-process packer truck refuse prior to shredding. Part of the logic for this step is that the portion of raw refuse already within the specified shredder output particle size range would bypass the primary shredder and proceed directly to further processing, such as to an air classifier or secondary shredder. This would reduce the throughput of the primary shredder and allow certain recoverable materials, such as glass, to remain in larger piece sizes, important for recovery. In this way, operating costs for the shredder would be reduced and the recoverability of materials, and hence the revenue, increased.

Jan 1, 1975

By AIME AIME

STEADY advance has been made in the art of lead smelting and refining during the year. The bringing of natural gas to the Salt Lake valley has led to its adaptation to lead smelting operations. The Tooele plant of the Anaconda Copper Mining Co. has put into practice the high blast pressure and constant volume for lead blast furnaces, which we understand was first advanced by John F. Austin. It would appear that within limits, capacity is nearly proportional to the volume of air. If the charge is dense, a constant pressure, as in the old practice. did not get much air through the charge and the furnace slowed up. The constant volume idea makes the charge smelt at the same rate as if the charge were porous. The cost of a little additional power insures capacity operation at all times.

Jan 1, 1932

Bag stackers who use semi-automated palletizing machines and air slides may be exposed to high concentrations of dust. To reduce dust exposure, use an exhaust ventilation system in conjunction with an envelope of clean air over the bagstacker provided by an overhead air supply. Description of Hazard Mineral processing plants in the United States and throughout the world process material that is finely ground and placed into bags for shipping to the consumer. These bags normally range from 50 to 100 pounds in weight. Once the material is placed in these bags, a bag stacker loads the bags onto pallets. A bag stacker is exposed to a lot of dust that is mainly released by the force from loading the bag onto the pallet. The two main sources are the dust on the outside of the bag and the dust that escapes from inside the bag as it is loaded. The Mine Safety and Health Administration's (MSHA) records indicate the bag stacker's dust exposure is one of the highest of all workers at mineral processing operations. Ways to reduce the dust exposure and strain to the bag stacker are in constant development. Recently, automated systems have been built. These systems range from fully automated, which totally remove the worker from the bag-stacking process, to semiautomated systems, in which the bag stacker still performs some of the functions. This Hazard Control deals with controlling the bag stacker's dust exposure during use of a semi-automated palletizing machine. The worker slides the bags into position on the palletizing machine. Once an entire layer of bags is positioned, the bag stacker operates the controls on the palletizing machine to lower the layer of bags onto the pallet. An air slide is built into the semi-automated palletizing machine so the bags are easier to move. This slide uses a metal table with air jets that exit through small holes at high velocities, similar to an air hockey game. The dust problem occurs because the air slide causes dust to blow up onto the bag stacker, significantly increasing the dust exposure.

Jan 7, 2001

By B. Birol, M. N. Saridede

"Slag density is a significant factor in determining the process efficiency of the electroslag remelting (ESR) process, where calcium fluoride (CaF2)-based slag is formed synthetically to refine metal ingots. Although there are some former studies investigating the density of CaF2-containing slags, the prediction models focusing on them are applicable only to some specific systems. The present study aims to build a model to predict density for a wide range of CaF2-containing ESR slags. To investigate density for various slag compositions, CaF2-Al2O3-based and CaF2-Al2O3-CaO-based slag compositions were prepared. Additionally, some minor constituents like FeO, MgO and MnO were added to a 5:3:2 CaF2-Al2O3-CaO slag in order to investigate the effects of these constituents on the slag. The volumes of the prepared slags were measured in a tube furnace at 1450-1550 °C using the sessile drop technique, and their densities were calculated. The results showed that for the slags, density is related to optical basicity, and therefore a prediction model based on an Arrhenius equation was built. The model was tested with data from literature, and its limitations and validity are discussed.IntroductionThe electroslag remelting (ESR) process is a refining method in which a metal ingot is remelted under a synthetic slag. These synthetic ESR slags are mainly composed of calcium fluoride (CaF2), calcium oxide (CaO) and aluminum oxide (Al2O3). Other constituents like iron oxide (FeO), magnesium oxide (MgO), manganese oxide (MnO) and chromium oxide (Cr2O3) are added to this system in relatively low amounts, according to the type of steel ingot to be refined. The prediction of slag properties, such as electrical conductivity, viscosity and density, is crucial for the selection of the synthetic slag in order to obtain the required process parameters, like temperature, the passing time of the molten metal droplet through the slag, and metal-slag separation (Akbari, Reitz and Friedrich, 2009; Hara and Ogino, 1981; Mattar, El-Faramawy and Fathy, 2002; Mehrabi, Rahimipour and Shokuhfar, 2005; Presoly, Korp and Schneider, 2008).As slag density affects metal-slag separation in the ESR process, predicting the density of an ESR slag is important for appropriate refining and improved product quality. Although there are many studies investigating the density of slags (Akbari, Reitz and Friedrich, 2009; Aune, Hayashi and Sridhar, 2005; Hara and Ogino, 1981; Matsushita, 2011; Mills and Keene, 1987, 1981; Seetharaman et al., 2013; Shu, 2007; Shu and Chou, 2013; Sikora and Zielinski, 1974; Xu et al., 2012; Zhang and Chou, 2010), the prediction models built are generally valid for oxide-containing slags (Aune, Hayashi and Sridhar, 2005; Bottinga and Weill, 1970; Mills and Keene, 1987; Seetharaman et al., 2013; Shu, 2007; Xu et al., 2012; Zhang and Chou, 2010). These models were built on either the molar volumes of the constituents (Bottinga and Weill, 1970; Mills and Keene, 1987) or the thermodynamically calculated enthalpy or free energy of mixing, which can be applied to a system containing constituents sharing an ion, such as an O- ion for oxide systems (Aune, Hayashi and Sridhar, 2005; Hillert, 1980; Persson et al., 2007). Some recent studies modeled the density of some oxide slags on their optical basicity (Shu, 2007; Shu and Chou, 2013; Xu et al., 2012; Zhang and Chou, 2010)."

Jan 1, 2016

By H. A. Tucker

This Bureau of Mines investigation was conducted to determine the appropriate quantities of rare-earth methals (REM) in the form of silicides to add to an alloy steel for the purpose of increasing toughness and ductility. The work was conducted in a vacuum induction furnace with the rare-earth additions required to deoxidize and desulfurize a simulated basic oxygen furnace (BOF) vacuum-degassed steel initially containing 0.013 to 0.016 percent sulfur. The product proved to be as good or better than the best basic electric furnace steel of the same composition made by the steel industry. Twenty-three experimental heats of 5 Ni-Cr-Mo-V steel were made, cast into 50-1b ingots, and hot-worked in a press and a rolling mill to ½ inch plates which were then heat-treated to 130/150 ksi4 yield strength. Impact and tension tests showed that the addition of 0.025 to 0.100 percent, or ½ to 2 lb per ton, respectively, of rare-earth metals when compounded with silicon were appropriate for increasing toughness and ductility. These quantities resulted in retained cerium contents between 0.014 to 0.025 percent, and increased the Charpy V-notch energy absorption and the percent reduction of area significantly as compared with base heats at the same sulfur content levels. All the test heats, including those with additions of REH of as much as 4 lb/ton, had greater Charpy V-notch energy absorption values than the base composition could have developed at the starting sulfur range of 0.013-0.016 wt pct.

Jan 1, 1968

Develop an easy-to-use, reliable, resin-grouted cable support system capable of being installed as primary and secondary roof support in coal mines.

Jan 1, 1994

By Eugene R. Rice

(Canal Zone Meeting, November, 1910.) THERE are many methods for determining the meridian, but all of those in common use involve at least two separate observations, one for latitude and one for azimuth. Such observations made upon a south star at any hour are open to the objection of possible inaccuracy due to ignorance of the absolute refraction, and also to slow change in the altitude of the star when near the meridian. The method of observing a circumpolar star at elongation, besides requiring a separate observation for latitude, is open to the serious objection that clouds may obscure the star at the critical moment. Moreover, a tedious wait for the star to come to elongation is sometimes necessary. Many of us can recall long, cold, weary vigils, waiting for Polaris to reach elongation. For observing a circumpolar star at any hour, not only the latitude, but also the true time, must be known. This it is practically impossible to obtain, except in regions reached by the telegraph, and usually then one has to know the longitude also, in order to reduce "standard time" to "local time." The results obtained by this method, when the star is at culmination, are not very good, unless the true local time is absolutely known. The methods of obtaining the meridian from the sun, by means of a solar attachment, or by direct observation, while good, are not absolute, by reason of refraction, change in declination of the sun, and small change in vertical angle, when the sun is near the meridian. For these two methods, latitude, time, and approximate longitude have to be known. In the method here described, only one observation is needed, and from it azimuth, latitude, and sidereal time are computed. In other words, one can observe a circumpolar star-Polaris

Nov 1, 1910

Competition in the mining industry is the main driving force for both equipment manufacturers and end users to develop and apply the most cost efficient solution to a mining problem. Therefore the challenge to find new solutions is usually met by several suppliers under various factors of influence affecting specifications. Time and timing are particularly important, but all new developments ultimately have to successfully perform on site.Consideration of all aspects of planning, manufacturing, user liaison and ultimate satisfactory commissioning hinges on the necessities of assessing of all the expectations in the mining application and the requirements of the concept and layout team. To apply the maximum available technical competence with solid thorough workmanship is the best possible foundation for success of underground machinery development.

Jan 1, 1991

By The Staff of Dames & Moore

Five factors are required for the formation of uranium deposits: a source, transporting medium, host, trap, and preservation. Locating and evaluating uranium deposits requires ail integration of methods and techniques to determine if the above factors are present. A typical exploration program consists of selection of a favorable area, field reconnaissance, land acquisition, and target definition and evaluation. Target definition and evaluation utilizes a combination of geologic mapping, geochemical surveying, geophysical surveying, and drilling and logging. Each overlaps the others to some degree.

Jan 10, 1978

By P. Somasundaran, G. Anastassakis, Z. Pan, D. R. Nagaraj

Gums are often used as depressants for talceous gangue minerals in the flotation of nickel and platinum bearing ores. However, the mechanisms of gum adsorption on talc are not clearly established. In this work, adsorption of guar gum at the talc-solution interface is investigated using spectroscopic and allied techniques. Guar gum adsorption on talc is not affected significantly by changes in solution conditions such as pH and ionic strength. Electrokinetic studies showed that guar gum decreased the negative zeta potential of talc but did not reverse the charge. Fluorescence spectroscopy studies conducted to investigate the role of hydrophobic bonding using pyrene and dansyl probes showed no evidence of the formation of hydrophobic domains at talc-aqueous interface. Urea, a hydrogen bond breaker, reduced the adsorption of guar on talc to the same extent as that for guar/alumina system, in which hydrogen bond plays an important role. All of the above results suggest that one of the main driving forces for guar adsorption on talc is hydrogen bonding rather than electrostatic or hydrophobic force.

Jan 1, 2003

By Christoph Miller

About 80 years ago the mining industry saw an advertisement of a machine manufacturer: ?One man ? one machine?, meaning the productivity gain by using a pneumatic rock drill instead of manual tools. Mechanization in mining had started. In the 1950's and 1960's when mechanization progressed the word could be transformed into the meaning of ?one man ? one drill rig?. During the 80's automatic functions were added to the machines. Automation started. In the 90's, the first autonomous machines were seen, transforming the advertisement from the 1920's into ?one man ? multiple machines? operated from a remote control room. Soon, the productivity gain achieved by pure automation will also be flating out meaning that the margin cost of further productivity gain will be inefficiently high. What next? In mining operations there is still a high potential of unused productivity lost by ?trivial? things like organization, logistics and operational management. Changing the focus from mechanization and automation towards optimizing the overall mining process will unleash another big potential for cost cuttings and for enhancing efficiency of production. Optimizing an overall process is a task of much higher total complexity compared to an isolated machine automation focus. And a successful process integration requires the collaboration of machine vendors, infrastructure suppliers, IT services and the mine itself. It requires a number of of important preconditions to be fulfilled: ? Integrated IT systems with seamless interfaces between all components and peripherals involved ? Real time information access in all locations ? Real time overview of all operational aspects A crucial aspect for all of these issues is a seamless communication both above and also under ground and IT interfaces which are easy and price efficient to implement. This paper highlights ways to achieve productivity gains by process optimization. It also discusses needs for industry wide activities in order to enable cost efficient performance of mine process optimization projects.

Oct 1, 2009

By A. J. Mcintosh

PRICE changes in competing fuels in the last three decades have reflected the changes in the consuming habits of the people of the United States. Prior to World War 11 the importance of fuel oil and fuel gas increased almost constantly while the relative importance of both bituminous and anthracite coal decreased. During this same prewar period coal prices increased to a much greater extent than oil prices. In fact, in many years, oil prices declined and in most cases are now no higher than they were back in 1925-26. During the war natural economic trends were entirely upset because of the tremendous petroleum requirements of the Army and Navy. Under these conditions many industrial plants were converted to the use of coal and the new installations in home heating and industrial plants of all kinds which might have used oil were practically eliminated. Although petroleum prices were rigidly controlled by OPA coal prices increased several times during the war. An over-all statement as to the rela-

Jan 1, 1947