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By Willie M. NeSmith

Cast-in-place piling are a staple of the deep foundation industry, and are used (in various forms) worldwide. In assessing the application of cast-in-place piles, it is of value to reflect on the development of the various systems, in order to understand how the current processes and equipment came to be. This paper traces the evolution of the cast-in-place industry. Emphasis is on developments in the United States; however, since there has been a substantial fusion of US and European processes, notable European developments are also discussed.

Jan 1, 2006

Separation performance of a Floatex Density Separator (FDS) has been studied both experimentally and theoretically. Experimental results reveal that at a lower bed pressure the FDS acts like a classifier. Higher bed pressure is required to attain the concentration effect as proper development of suspension density occurs under these conditions. It is seen that the size or density alone is not able to describe the partition fully. The terminal settling velocity, which includes both the size as well as the density of the particle can be a useful descriptor of separation in a FDS. While a narrowly distributed feed offers better performance of a FDS, a wide size distribution of feed results in large scatter in the terminal settling velocity distribution and renders the separation difficult. The closely sized feed enhances the density effect in concentration. A higher teeter water flow rate also helps in carrying larger-lighter particles to the overflow by increasing the cut off terminal settling velocity as it increases the net upward force. A detailed description of separation performance in a Floatex Density Separator has also been established from theoretical considerations. Separation performance of the separator is described using a simple slip velocity model. The model has been validated com-paring the predicted FDS performance results with those experimentally measured under widely different operating conditions.

Jan 1, 2014

By Vicente Martínez Guerra

Producto de una de las operaciones realizadas en la Cerro de Pasco Corporation, se obtienen algunos elementos y subproductos químicos como el arseniato de calcio que ocupa el primer lugar en ventas en dicha compañía. Por ello, el objeto del presente texto describe el proceso y el uso de As2 O3 para la fabricación del arseniato de calcio en la planta de fundición de La Oroya, como su aplicación de insecticidad mineral en la agricultura. Dentro de este periodo, el elemento químico será recuperado en el cottrell de arsémico, de los humos provenientes de los hornos tostadores de los minerales de cobre, precipitando una concentración oscilante entre 40 a 45% con un contenido de cobre de 4%. donde el polvo sufre una tostación para así concentrar el cobre por sublimación del arsénico. Asimismo en este sistema de fabricación de arseniato, la liberación del As2 O5 del piroarsenIato de calcio se realiza por ataque con ácido sulfúrico, garantizando la pureza de este óxido en la precipitación final del proceso. En consecuencia, la aplicación del arseniato de calcio, como insectida inorgánico mineral protege el sistema ecológico, dado su bajo contenido de arsénico soluble en agua, al tiempo que se ajusta a las reglamentos oficiale vigentes del país.

Jul 20, 1956

By D. E. Walsh

With the exception of the development of large scale mining equipment (haul trucks, draglines, shovels, etc.), there are likely few other candidates responsible for the ability to exploit large tonnage, low grade deposits, than the development of large capacity comminution equipment and circuits; crushers and grinding mills. Ball mills are often the final step in the comminution process and are responsible for providing what should be the optimum particle size distribution of ore to subsequent mineral concentration steps in the flowsheet. Because comminution processes are such high cost centers for milling operations, both capital and operating costs, an enormous amount of research has been conducted to study and model their performance, in order to improve efficiencies (Kelsall, et al., 1969; Austin et al., 1984; Napier-Munn, et al., 1999; Powell and Smit, 2001). With respect to modeling ball mills, estimates of the breakage rates for individual size classes of ore particles are fundamental, as are the particle size class breakage functions (the progeny of particle sizes produced from breaking a coarser particle size class), also termed appearance functions. Fundamental research into particle breakage in tumbling mills focuses on how much energy is input into single particles versus how they break and what size distribution of particles results. Several test methods, including JKMRC?s well known dual pendulum test and drop weight test, have been developed for the breakage of coarse particles down to 6 mm in size (Napier-Munn, et al., 1999). Work on the breakage of finer particles is still an area of intense research and single particle breakage is being investigated as are multiple particle, fixed bed methods (Hoffler and Herbst, 1990; Bourgeois et al., 1992; Whiten, 2007).

Jan 1, 2011

By John E. Lambert

Automatic control of drum head continuous mining machines was investigated as a means of reducing respirable dust generated and operator variabitity. Literature survey, manufacturer interviews and mine visits were the major information sources. Technically feasible automation concepts were Identified to control sump and shear rates, cutter head elevation limits and sumping distance. These are the elements of a programmed cutting cycle which maintains peak penetrating force on the cutter, to maximize depth of cut and therefore reduce dust generation. Based on the industry surveys, successful underground hardware demonstrations must be completed in order to stimulate the market demand for these advanced control features.

Jan 1, 1979

Jan 1, 1969

By D. R. Walker, M. C. Shaw

Dimitri Kececioglu (Allis-Chalmers Manufacturing Co., Milwaukee)—The idea of applying metal cutting theory to comminution and vice versa is very impressive. Among others, the demarcation of wheel-grinding data into two regions, namely Kick's and Rittinger's, draws attention here. A study of Figs. 6 to 9 shows the following: In Fig. 6, 1 point out of 8; in Fig. 7, 4 points out of 26; in Fig. 8 only 1 point out of 13; and in Fig. 9 practically none out of 13 points fall out of curve No. 2. Also when grinding particles smaller than 5x10." in. it is difficult to measure very accurately the grinding forces, chip geometry, and particle size. In view of the above it would be difficult to make a positive and distinct demarcation of the Wheel-grinding data into two regions, namely, Kick's and Rittinger's. The idea of using machine grinding to determine the comminution properties of materials is indeed unique. The following cautions come to mind, however, regarding applicability of machine grinding data to comminution: 1—Grinding gives uniform particle size, whereas comminution gives a variety of particle sizes in the same process. The fact that grinding gives uniform particle size is not necessarily an advantage because in comminution the overall energy under actual comminution is desired and comminution invariably results in the production of a variety of particle sizes. 2—In grinding, a small particle is ground off a comparatively large surface. In comminution small bodies are broken down to smaller bodies. This makes it difficult to establish a concept of reduction ratio in machine grinding. 3—The mechanics of machine grinding involve direct shearing action under very high strain and comparatively high compression at the shear zone, whereas: comminution involves direct dynamic compression and surface friction with comparatively little strain and shear. Consequently the mechanics of machine grinding appear to be different from those involved in comminution. Hence one might arrive at erroneous con- clusions when comminution characteristics are eval-uated from machine grinding results. It is noticed also that functions other 'than Eq. 16 which do not involve the concept of direct proportionality of useful energy input to new surface area created (Eq. 2 and particularly Eq. 12) may be derived to fit the, data of curve No. 2. One such relationship may be u = ct-", where c is a positive constant and n is a positive constant less than unity. This, of course, is made possible because data of a very small range. of particle size are being fitted by the curves of No. 2 and the hereby suggested relationship. A sound comminution theory should be applicable to a relatively large range of particle size. George B. Clark (Department of Mining Engineering, University of Illinois)—While the experimental work of Walker and Shawin this article is of intrinsic value in revealing certain fundamental aspects of machine grinding, milling, and related processes and in adding to the store of information concerning the comminution of solid materials by this particular process, it appears doubtful that the results of their research can be employed to verify either Kick's or Rittinger's theories. Both these laws were originally developed and proposed on the basis of very simple, idealized hypotheses. The creation of parallel idealized physical laboratory conditions which would be required for either their proof or disproof appear to be well beyond the scope of human ingenuity, at least at present. One great weakness of the imputed verification is that the spread of the points plotted on the graphs is not sufficient to permit accurate 'curve fitting. The range of particle sizes included in the belt and wheel grinding is not extensive enough to show any general trends, particularly for the horizontal portion of the curves, said to represent Kick's laws. That the milling; grinding, and turning data obtained by Walker and Shaw for both metals and minerals happen to comply with. certain interpretations of these two theories under certain specialized conditions

Jan 1, 1955

By Jack Eloranta

To improve control of blasting, tests were performed to assess non-electric cap accuracy. Simultaneous testing using a Velocity of Detonation Recorder (VODR), Red Lake Lo-Cam and an Instantel DS-677 blast monitor was done. Favorable comparisons were found in the three records . This testing confirmed the accuracy of an inexpensive and expedient cap testing procedure.

Jan 1, 1992

By Frank Tapia, Aldo Gutiérrez

El presente tiene el objetivo de mostrar las principales actividades que se realizan en la estabilización de taludes a doble banco en Sociedad Minera Cerro Verde SAA (Cerro Verde), con el fin de asegurar condiciones seguras y favorables en las operaciones mineras y trabajos en interacción con los taludes de mina.

Sep 30, 2022

"En 1953, se habilita la nueva planta de flotación de cobre en Paragsha, donde el funcionamiento de las soleras tipo Lorain y la producción del mineral pirita lograron buenos resultados. Empero las nuevas condiciones de proceso, limitaron su funcionamiento y costo. Por tal motivo, el objetivo del trabajo se basa en la construcción de una solera de mayor rendimiento y menor costo, modificando su diseño al de una honda contínua. El primer juego de este diseño fue instalado en el molino de cobre Nº 1, sin aún obtener el dato final sobre su rendimiento. Posteriormente se consideró la solera AMSCO, dado que el diseño fue más eficiente y el costo final por tonelada fue menor. Sin embargo, se encontró que el contorno del valle era muy cerrado y las bolas N°4 se alojaban de modo ajustado, formando una solera muy gruesa. En consecuencia, se construyó otro diseño denominada ""Solera de onda abierta contínua"", el cual fue instalado en el molino de cobre N°7, donde la capacidad de molienda es igual de óptima y los costos son menores. Así, se pensó que la solera de una sola honda, es mejor que la de onda contínua puesto que este diseño tiene una sola honda en el centro de cada plancha de la solera. Luego, se diseño un tercer diseño, donde el promedio de vida era mejor. Por ello, de los tres diseños a seleccionar -la solera Lorain con 10 hondas, la solera de una honda con 20 hondas y la solera de honda continua de 30 hondas -, la última demostró ser la más eficiente. De otro lado, se probaron otros diseños de honda contínua con distintas aleaciones como el ""Nihard"", cuyo promedio de vida es entre 14 y15 meses aproximadamente, con el tonelaje actual de aproximadamente 270 000. Concluyendo que la experiencia anterior con solerasNihard en molinos a rodillos de 4 pies de diámetro, el impacto es mayor, obteniéndose en quebrantamiento de soleras a 3/4 grosor, pero que pese a esto, resulta ser superior a cualquier otra solera usada actualmente y en eñ que Paragsha esté 100% con soleras de molinos Nihard, a excepción de las rejillas dada su fragilidad. "

Jul 20, 1957

By Michael P. Sudbury

Non-ferrous slags are granulated and stockpiled as an alternative to pit cooling or transporting molten slag to a dump. The chemical composition of such slag is determined by the pyrometallurgical process in which it is produced, while the size distribution is set by safety concerns or a desire to reduce wear of pumps, pipelines and other equipment. Relatively few operations give consideration to the effect of granulation conditions on other properties of the granulate as the material is typically accumulated on the smelter site. It is becoming recognized that slag has many potential commercial uses and carries much of the energy applied to the smelting operation. This paper outlines the findings of extensive work to identify uses for granulated non-ferrous slag, the importance of preparation conditions on the properties, impediments to more extensive use of granulated slag, the real costs of slag stockpiling and the opportunities for further productive research.

Jan 1, 2006

By Henry Kreisinger, L. P. BRECKENRIDGE, WALTER T. RAY

The investigations of fuels conducted by the technologic branch of the United States Geological Survey had their inception at the Louisiana Purchase Exposition in 1904. By an act approved Febru- ary 18, 1904, Congress authorized the work of analyzing and testing at the Louisiana Purchase Exposition the coals and lignites of the United States, under the supervision of the Director of the United States Geological Survey. An appropriation of $30,000 was made for this purpose. In the general deficiency bill dated April 27, 1904, the sum of $30,000 was added to the appropriation. To carry out these investigations the Director of the Geological Survey appointed a committee consisting of E. W. Parker, statistician of the Geological Survey; Joseph A. Holmes, State geologist of North Carolina; and Marius R. Campbell, a geologist of the Geological Survey. Under the first act authorizing this work all of the machinery and coal for the tests was to be furnished the Government free of charge. The buildings containing the testing apparatus were all paid for out of the first appropriation. After the close of the Louisiana Purchase Exposition every Congress made an appropriation for continuing these fuel tests. These subsequent appropriations permitted the purchase of appliances better adapted for the testing work.

Jan 1, 1912

By S. Mudau, P. Mohasoa, M. J. Cole

Derelict and ownerless (D&O) mines in South Africa have been an ongoing concern for over a decade. While some progress has been made to rehabilitate D&O asbestos sites, significant work remains, exacerbated by the growth in illegal mining. There are concerns regarding the accuracy and transparency of the D&O database, lack of oversight, and constrained funding, and the government is increasingly looking to the private sector to fund rehabilitation. Given these challenges, a new, sustainable approach to D&O sites in South Africa is needed to bring clarity and transparency to the process, recognise responsibilities and promote partnerships, and explore economic opportunities at D&O sites to reduce the financial liability and respond to the growing demand for critical minerals. This article has three components: i) reviews of international D&O good practices; ii) it analyses South Africa’s current approach and the D&O sites; and iii) proposes a D&O framework that addresses data, risk ratings, responsibilities and rehabilitation, economic opportunities, and stakeholder engagement. The study finds that the majority of the 6,100 so-called abandoned D&O mines are quarries and mine site features, 16% are operational, at least 11% have owners, and only 752 (12%) require rehabilitation. The framework aims to bring clarity and fairness to decision-making and to assign risk and responsibility for rehabilitation and seeks to incorporate economic opportunities to reduce the financial burden of rehabilitation, create jobs for local communities, and respond to the growing demand for critical minerals for the clean energy transition.

Apr 25, 2025

By T. Geyer

The Carbon Disclosure Project (the pre-eminent global initiative for institutional investor collaboration on climate change) groups the business risks (and opportunities) related to climate change into four categories: 1. Regulatory risks from tightening legislation (and opportunities for companies that can make the carbon market work for them), e.g. rising costs for carbon and energy-intensive processes. 2. Competitive risks & opportunities generated by a possible decline in customer demand for carbon/energy intensive products (and opportunities from a consequent rise in demand for efficient / low carbon products). 3. Reputational risks from perceived inaction on climate change (and benefits to those perceived to be ?solutions providers?). 4. Physical risks from changes to climatic patterns, e.g. asset damage from extreme weather events; project delays; water scarcity; resource risks as certain crops become no longer viable in certain areas and new supply chains become necessary; and potential human and socio-political impacts. All of these are already having repercussions for businesses in certain sectors and geographies. The understanding of specific impacts of climate change is still evolving but it is clear that climate change will have a material impact on the value of many businesses, either directly or indirectly. Many commentators and analysts consider that rising energy costs are likely to represent the most direct and immediate investment risk that climate change and the resulting regulatory responses will create for business in the near term. However, it is already possible to identify numerous examples of competitive and reputational risks and opportunities that are leading to significant value creation or destruction in business: the success of the Toyota Prius; the rush by the UK?s leading supermarket retailers to ?green? their brands; and the surging fortunes of companies involved in the manufacture of renewable energy generation equipment, are all manifestations of this trend. In addition, the potential physical impacts of climate change are also making themselves felt in certain sectors: an example is the Australian wine industry, suffering after an extreme and prolonged period of drought. THE PROJECT This paper describes a project undertaken for a multinational mining company to examine the physical risks from climate change across its international business operations. The study addressed 163 components of the business and included operating sites (mines, smelters, and refineries), key transport routes (road and rail) and port links. The inclusion of the transport networks and ports is extremely important; key transport routes (e.g. a key railway link) may often be impacted (e.g. by flooding) far more than individual sites due to their large geographic exposure and multiple potential failure points. Extreme weather events causing loss of life and major economic damage continue to be front page news. According to the World Meteorological Organization, January to July 2007 ?was marked by record weather extremes in many regions across the world.? Inevitably, the associated phenomena are starting to impact business and investments, not so much as deal breakers, but in changing the parameters of risk management and the approaches required to devise mitigation measures. EXAMPLES OF EXTREME WEATHER EVENTS No one event can be presented as directly attributable evidence of climate change, however climate change projections suggest that the frequency and severity of many extreme weather events can be expected to increase in a warming world. In August 2003, a heat wave struck Europe, with temperatures as high as 42°C (108°F). As summer temperatures in much of northern Europe rarely exceed 30°C (86°F), the area was unprepared for the disaster, and many thousands of deaths occurred. In August 2005, Hurricane Katrina caused catastrophic damage along the Gulf Coast of the United States, forcing the effective abandonment of south-eastern Louisiana (including New Orleans) for up to two months and damaging oil wells that resulted in increased oil prices. Katrina killed over 1,800 people and caused at least $75 billion in damages, making it one of the costliest natural disasters of all time. This was followed in September, by Hurricane Rita which left 119 people dead along the U.S. Gulf Coast, causing $9.4 billion in damage. In January 2006, hundreds of people were killed when Russia, Eastern Europe and Scandinavia experienced the coldest weather for decades. In summer 2007, dramatic floods in the south central region of England, UK left 350,000 people without drinking water and many without electricity. Transport infrastructure was severely disrupted; combined with floods which occurred earlier in the summer in Yorkshire (North England), the damage is estimated to total over £2 billion. ASSESSING RISKS FROM CLIMATE CHANGE To date, only a minority of companies have attempted to quantify the risks from climate change. However, investors are seeking greater disclosure of climate change related risks and opportunities and it is expected companies that can demonstrate they are prepared for climate change will attract higher market valuations. Climate Change Threats A variety of climate change threats were examined for their potential to have a potential measurable impact on the mining company?s business operations. Those considered most significant were included in the study and are shown in Table 1 (see Appendix A). Certain threats can be considered as being cyclical in nature and the future predictions may suggest a change in the frequency and severity of such events (e.g. storms/hurricanes, rainfall, drought). However other threats are associated with a gradual change over time (e.g. loss of glaciers, loss of permafrost, sea level rises). A slightly different approach is needed to address this differing nature of the threats, as described subsequently. Climatic Regions Much of the research and data associated with climate change is collected and reported on a regional basis. An example of the climate change impacts predicted for a number of climatic regions is shown in Table 2 (see Appendix A).

Jan 1, 2009

By W. S. Fyfe, G. Southam, T. J. Beveridge

Bacterial populations play an active role in mineral weathering in subsurface and near-surface environments e.g., supergene enrichment of Cu at Morenci, AZ. An invitro bacterial biofilm model was used to examine the interaction between Sporosarcina ureae and ionic gold(which is toxic) or amino acid-gold complexes in gold mobility. The immobilization of ionic gold was between80-90% for 1 week but as the available, cellular reactive sites became saturated immobilization decreased to 14%within 2 weeks. In the asparagine-gold system, gold immobilization occurred at a high rate (80-90%)throughout the experiment with limited toxicity towards Sporosarcina ureae.

Jan 1, 1999

By W. W. Adams

With production of coal per man-hour of work highest in history, the coal mines of the United States established a lower accident-frequency4 rate in 1942 than in any year since 1930, the first for which the Bureau of Mines, United States Department of the Interior, collected complete reports of nonfatal as well as fatal injuries. Reports from mine operators and State mining departments showed that 530,861 men were employed in and about coal mines during the calendar year 1942. This number does not include office employees or coke-oven workers. The figure represents a decrease of 15,831 men from the previous year, owing to losses of men to the military services and to more lucrative employment in the munitions and other industries. The loss of men was offset to some degree by an increase in the number of days of mine activity and the average number of hours of work per man during the year. The volume of work done during 1942 was 910 million man-hours, 11 percent more than in 1941. The average employee worked 243 days, 30 days more than in 1941. Production reached the unprecedented total of 640 million short tons, an increase of 12 percent over 1941; 582 million tons came from the bituminous fields of the United States and 58 million tons from the anthracite fields of Pennsylvania. To produce this quantity of coal 1,471 men sacrified their lives, and 69,564 men suffered nonfatal injuries that disabled them for more than the remainder of the day on which the accident occurred. The nonfatal injuries were divided into three groups: 65 caused permanent total disability, 2,045 caused permanent partial disability, and 67,454 caused temporary disability of 1 day or more but did not result in the loss of, or permanent loss of use of, any part of the body.

Jan 1, 1944

By C. W. Morris

This study was performed for the U.S. Bureau of Mines. An existing computer simulation of a dragline was modified to simulate a dragline dumping into the hopper portion of a cross-pit conveyor system. This revised computer model was then used to study four proposed cross-pit conveyor systems. Parameters such as dragline position, hopper position, and digging procedure were varied to maximize the dragline production. This performance was compared with the conventional side-casting spoil method. I t was concluded that the cross-pit conveyor systems were competitive with the conventional side-casting technique.

Jan 1, 1977

By Homer J. Ballinger

"SUMMARYDuring December 1945, the Bureau of Mines began churn drilling the Winchester zinc deposit, 11 miles south of Joplin in Newton County, Mo. The deposit lies in a virgin area northwest of the Seneca fault. It is one of several deposits partly proven by drilling but never developed.Logs of 28 privately drilled holes had indicated a substantial tonnage without delimiting the deposit. It appeared that additional drilling might increase this reserve sufficiently to justify mining. A, total of 6,33 feet of churn drilling was completed in 17 holes drilled by the Bureau of Mines. Twelve of the holes penetrated minable ore extending the length of the known deposit and materially increasing its estimated tonnage.INTRODUCTIONDuring May 1943, the Winchester property in Newton County, was visited by an engineer 3/ of the Bureau of Mines, accompanied by Dr. A. N. Winchester, owner, and Charles Keith, lessee of the property. At the request and with the assistance of these gentlemen, examination of the property was undertaken. Logs of 28 churn-drill holes were collected, hole locations were surveyed, and available historical data were obtained. It was concluded that although existing drill holes indicated considerable reserves, additional drilling might increase the tonnage substantially. In addition, it was believed that better knowledge of this ore deposit could be obtained by drilling further, and this knowledge could, in turn, be applied to other less proven deposits in the same field."

Jul 1, 1947

By A. E. Boone

"The paper presents critical areas in which improved coordination of effort by industry, government and sup-pliers will be essential to continue the growth record of the Canadian mining industry into the 'seventies'. The analysis includes: exploration, production, mining methods, research and development, markets, management and industrial relations. Performance objectives are suggested where tangible results can be measured. The author suggests the methods by which the 'seventies' can be the greatest decade in the history of Canadian mining. It is indicated that a national mineral policy is essential to the Canadian mineral industry."

Jan 1, 1970

By Peter Shuttleworth, Chris Fesq, Eddie Woods

Precast concrete segmental linings for tunnels have traditionally been designed with conventional steel bar reinforcement. In many cases, this has been satisfactory in service, but in others, major problems have occurred with the durability of the linings. Commonly this has resulted from corrosion of the reinforcement, mainly from chloridesin ground water, causing spalling of the concrete and leading to very expensive and disruptive repair programs. This paper discusses the relative merits of designing tunnel linings with steel fiber reinforcement to provide long-term durability, improved impact resistance and toughness for greater load capacity across joints, enhanced robustness during transportation and erection, plus improved fire resistance with the addition of polypropylene fibers. Guidance is also given in the selection of the correct fiber type, mix design and testing methods to establish the optimum dosage required and production techniques to ensure even distribution and compaction.

Jan 1, 2005