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By W. A. Crosby

All mine operators using explosives want to maximize explosive performance while minimizing blasting costs. Use of bulk explosive products such as AN/FO, heavy AN/FO, slurries and emulsions has greatly improved blasting efficiency over the years. Many operators have improved energy output from these products by adding aluminum. A major problem facing them is the fluctuation in aluminum price. The question therefore becomes, when is it economically advantageous to use aluminum in bulk products? This paper answers this question by first reviewing the energy output from the main types of aluminized and non aluminized bulk mixed explosives and then by showing the relationship between the different products on a cost and energy basis. The paper finally presents examples of charts and tables which will aid mine operators to conveniently select the most economically correct bulk explosive, including the level of aluminum addition.

Jan 1, 1991

By P. Duwez, L. Zwell

L. S. BUSCH—We have had presented two methods of measuring these variations in powder compacts. E. OROWAN—Tn connection with the rolling mill research work carried out at. the Cavendish Laboratory, Cambridge, with the help of the British Iron and Steel Research Association. Dr. E. A. W. Hoff, Mr. J. Los, and myself, have determined coefficients of friction at ex- treme pressures for a number of liquid and solid lubricants, both by direct measurement, and by calculation from measured values of the roll force. The most efficient lubricants at these high pressures (for the small amounts of sliding that, occur in rolling) were camphor and. in particular, borneol (Borneo-camphor). Perhaps such lubricants could be used with advantage in the kind of work described by Dr. Wulff. L. S. BUSCH—1 think Dr. Wulff has in the past mentioned experiments which have been performed in the extrusion and rolling of metals and which led to conclusions which can be applied to the compacting of metal powder. A. SQUIRE*—There have been some recent developments in the field of high pressure lubricants which indicate that boron nitride might be a very desirable material to employ as a die lubricant. At the present time its cost is prohibitive, but as the need arises for the material it will undoubtedly come down in price. The present price is $200. a pound. It is my understanding that one of the reasons for vacuum pressing both in ceramics and metal powders, is to prevent

Jan 1, 1950

By Lucas Andery Reis

No processo de beneficiamento mineral, a moagem é o último estágio da etapa de cominuição de minérios responsável pela redução das partículas à liberação do mineral a ser concentrado nos processos subsequentes. Um problema presente nesse processo é a moagem em excesso do material, que aumenta a potência consumida na moagem, dificulta a recuperação das partículas muito pequenas nas etapas de concentração e prejudica a operação de filtragem do processo de pelotização por entupimentos ocasionados pelo material mais fino do que o especificado. Para melhorar o desempenho da moagem e reduzir seu custo operacional, se faz necessário estudar estratégias de controle adequadas que controlem melhor as diversas variáveis existentes nesse processo. Nesse sentido, o objetivo desse trabalho foi utilizar um simulador de circuito de moagem com o intuito de comparar o desempenho da planta sendo controlada por controle clássico (PID), que é amplamente utilizado em circuitos de moagem, e por controle preditivo por modelo (MPC), que é aplicado em uma camada acima dos PIDs. Foi possível concluir que o circuito de moagem sendo controlado por MPC obtém melhor desempenho do que o PID, possibilitando trabalhar com as variáveis mais próximas de seus limites ótimos de operação.

Oct 30, 2017

By E. K. Albert

Computer oriented simulation techniques can be effective in the design and analysis of complex mining systems. In fact, a number of computer software products are available for mine systems simulation. While providing a useful tool for the investigation of mine planning problems, the availability of graphic output was limited or non-existent. Computer graphics is a natural extension of mine simulation methods and provides a more dramatic level of understanding and interface with an engineer. With today's high cost of venture development, the need for an easy to use but complete systems model which includes the major elements of mine planning with an interactive graphics interface has never been more apparent. In this paper, the underlying philosophy of design of an interactive interface to a complete surface mining simulation model is described. The basic structures of the surface mining system and the simulation model are discussed. The methods and algorithms used to implement the various subsystems are presented. Practical considerations of the design of displays and user interaction are illustrated, especially as they apply to the application of the package by a mining engineer. A simple example is provided to demonstrate the concepts embodied in the model and to show how a simulation is built from mine data.

Jan 1, 1984

By J. A. Eisele

The Bureau of Mines has reviewed the literature related to the recovery of A1203 (alumina) from coal ash. A small amount of unpublished data is also reported. Of the processes studied, the alkaline-sinter process is the most promising from a technical standpoint. However, owing to the high cost of processing coal ash, the dispersed location of powerplants, and the domestic availability of higher grade alternate materials, coal ash does not rank as a primary source material for replacing imported bauxite.

Jan 1, 1979

By Tadeusz W. Wlodek

THE known phenomenon that a test-piece of ferro-magnetic steel is magnetic after it has been broken in tension indicates that, while it is being loaded, the steel acquires magnetic properties. In the present investigation of the influence of the stress on the magnetic flux, repeated pulsating stresses of increasing amplitude, varying from zero to the maximum tensile value, i.e., pull-pull loading, were employed. The specimens were prepared from two types of carbon steel and two of alloy steel. The magnitude of the magnetic flux was determined indirectly. The voltage and mode of variation of the electromotive force induced in a coil surrounding the stressed steel specimen were measured as an indication of the varying magnetic flux within the specimen. Curves representing the electromotive force induced by the varying magnetic flux show that as the tensile load increased so also the magnetic flux increased, with a corresponding increase in measured e.m.f. At a certain stress there is a sharp bend in the voltage curve (point Win the diagram, Figure 5); this critical stress corresponds very closely with the yield stress (0.2 per cent permanent strain). Beyond this point, slight increases in the stress produce large increases in the voltage. The wave form of the e.m.f. was registered on an oscillograph. Analysis of the curves so obtained demonstrated the necessity of continuing these experiments, in order to determine the type of induced wave form associated with various types and amplitudes of stresses. In these experiments, the shape of the stress wave was sinusoidal, although the shape of the induced e.m.f. was sinusoidal only up to a certain load and became more and more complex above this load.

Jan 1, 1944

By E. Öğretici, S. Kahraman

The indirect estimation of intact rock properties is particularly useful for preliminary investigations in engineering projects. In this paper we examine the usability of electrical resistivity, a nondestructive measurement, for the prediction of physical and mechanical rock characteristics. Physico-mechanical tests (uniaxial compression, Brazilian tensile, density, and porosity tests) and electrical resistivity measurements were performed on specimens of 36 rock types. Before the resistivity tests, the specimens were completely saturated with saline solution. Evaluation of the test results showed that there are medium or strong correlations between resistivity and rock properties. There are also strong or stronger correlations between the two parameters for the rock classes. The regression equations developed were statistically tested, and their validity was confirmed. The results were also compared with previous studies. The conclusion is that electrical resistivity measurement can be used for reliably estimating physical and mechanical rock characteristics.

Aug 8, 2024

By Elton L. Litchfield

The Bureau of Mines determined minimum energies for direct initiation of expanding gaseous detonation waves in acetylene-oxygen mixtures. Composition limit ranges for the initiation of detonation with fixed energies have been compared to data in the literature. Assuming that the stored electrical energy is completely converted to thermal energy, the agreement between the energy of primary explosive initiators and the energy of electrical discharge initiators was good. Minimum energies for initiation of detonation in the most sensitive composition (40 percent C20 plus 60 percent 0 2) were: 0.64 joule at an initial pressure of 1/4 atmosphere, 5.0X10-2 joule at 1/2 atmos¬phere, and 3.7X10-3 joule at I atmosphere. Fuel concentrations in mixtures initiated to detonation by 4.9X102 joules ranged from 10 to 65 percent C2H2 at 1/4 atmosphere, 10 to 67 percent C2H2 at 1/2 atmosphere, and 9 to 68 percent C2H2 at 1 atmosphere.

Jan 1, 1967

By A. H. Baldo

Covers a very broad spectrum of problems and solutions. The problems are multitudinous and their solutions are sometimes simplistic, sometimes ingenious and sometimes within a very broad interpretation of the law. However, one thing is quite certain: the problems and their solutions will have a direct impact upon corporate and personal well being. First of all, why does one mine in a foreign land? Since the Bronze Age, when ancient man discovered the metallurgy of copper, tin and zinc, intrepid souls have been wandering afield searching for and exploiting those mineral deposits which would create wealth and security for his city-state or community.

Jan 1, 1981

By J. D. Isbister

Coal is the most abundant and most economical source of energy in the United States, however, combustion of coal results in release of pollutants to the environment. The release of sulfur dioxide and oxides of nitrogen during combustion of coal contributes to the deterioration of the environment. Energy independence in the United States must include the increased use of coal reserves. Increased reliance on coal for energy will dictate the necessity for making coal a cleaner fuel. New technologies employing a variety of techniques from harsh chemical treatment to mild physical separations to clean coal are rapidly becoming available. Success for any coal cleaning process is in economics which translate into efficient removal of sulfur with high recovery of combustibles as well as low capital and operating costs for the process. Conventional coal cleaning processes remove water soluble sulfates and a portion of the pyritic sulfur and ash from coals. Removal of additional sulfur from coals requires more advanced coal cleaning techniques. Coal contains many organic sulfur forms which are the most difficult of the sulfur types to remove from coal. The heteroaromatic sulfur species, such as the comlex thiophenes, are the most commonly found organic sulfur forms. These sulfur forms are resistant to chemical attack and are considered to be refractory compounds. Atlantic Research Corporation has developed an "unique" microorganism, CB1 (Coal Bug 1), capable of oxidizing thiophenic sulfur in coal to form water soluble sulfates.

Jan 1, 1986

By A. Berthet

In the past two decades, of the successive steps leading from iron ore to finished steel, the production of liquid steel and its preparation for the casting operation has probably undergone the most drastic evolution. The reason for this is the development of oxygen converters (top blown and later on bottom blown) and UHP arc furnaces which are replacing the conventional processes such as the open hearth and basic Bessemer processes. These new processes have been great advances, but it would certainly be quite hazardous to assert that the situation will remain the same for the coming decades. In fact, with the advent of continuous steelmaking a new generation of processes has now arrived. The research and development programme at IRSID on continuous an a steelmaking began ten years ago has progressed systematically in the following stages : First a comparison was made on a small pilot scale of various techniques : for example, refining in a runner by top or bottom blowing, pulverizing the metal stream by oxygen, using the mixing effect of a vortex, etc. but for various reasons these processes proved unsatisfactory and were abandoned in favour of a method using the so -called "emulsion refining".

Jan 1, 1972

By Andrés Gómez

El estudio considera la fusión de simulación y gestión de flota como una estrategia de innovación para seguir incrementando el rendimiento de los equipos en el proceso de la mejora continua que se aplica en la minería superficial. Como resultados se tiene el incremento de la producción en las minas que se aplicó en prueba, aunque en un principio no fue fácilmente recibido por lo complicado al inicio de la aplicación. En conclusión, esta innovación de fusión de simulación con los sistemas de gestión de flota en la empresa minera permite mejorar la producción y esto representa un incremento significativo de la producción

Sep 29, 2023

By Roland Hoet, Jim Patilla, Nick Madison

Increasing conveyor capacity and reliability is a common goal for many underground mines. This task is especially challenging when you must work with existing structure, belt, etc. Meeting this challenge, The Pittsburgh & Midway Coal Mining Co. North River Mine switched from constant fill to actively controlled fluid couplings, realizing a capacity increase from 2,100 tons per hour (2,300 stph) to 2,550 tons per hour (2,800 stph), with improved reliability. This paper will present a case study of The Pittsburgh & Midway Coal Mining Co.'s North River Mine underground conveyor haulage system. These conveyors included the main line conveyors as well as a tension controlled tripper booster panel conveyor. Characteristics and performance of the coupling and control system will be illustrated, demonstrating the systems controllability, simplicity, and dependability.

Jan 1, 2002

By B. Comley, M. C. Harris

There is as yet no accepted method of predicting flotation frother performance in plant processes based on laboratory scale characterisation techniques. This paper investigates the use of dynamic surface tension, using the maximum bubble pressure method, as a means of evaluating frothers and frother mixtures. An adsorption model is presented, which has been used to quantify the role of frother type and concentration during frother bubble interaction, based on the correlation of model parameters to physical frother characteristics. This approach was found to provide useful insight with respect to blending and selection of flotation frothers to meet specified flotation performance criteria.

Jan 1, 2001

By Roy L. Zuber

Identification and analysis of mining hazards involves the correlation of accident, injury and illness information from all segments of the mining industry. It would not be feasible to process the volume of data involved without substantial reliance upon a computerized information system similar to that maintained by the Health and Safety Analysis Center. Numerous statistical programs are applied to the computerized accident-injury-illness data base to identify those mining tasks and associated activities which are responsible for most of the injuries and occupational illnesses. These programs are used to flag those mining tasks or conditions at specific mines or segments of the mining industry where either a significant increase in the injury/illness trend has been reported or where the number of injuries/illnesses related to specific mining tasks or conditions are high. Upon identification of those mining hazards which warrant further analysis, a computerized search of the coded accident data is performed to correlate the predominant categories by cause of injury or illness, source of injury, nature of injury, type of accident, etc. From this correlation, those factors most common to the conditions responsible for the hazard may be identified. Based upon analyses of this form, recommendations are made regarding the appropriate engineering, training, and/or operational improvements necessary to alleviate the hazard. In addition to mining hazard analysis, the computerized data base also has application in the area of optimum resource allocation. Computer programs have been developed to assist management in allocating resources based upon organizational requirements and historical accident - injury trends.

Jan 1, 1983

By C Mason, A Littleboy

This paper presents the results of a large scale survey of The Australasian Institute for Mining and Metallurgy (AusIMM) membership. This survey aimed to understand and define the key issues and drivers that AusIMM members perceived would shape the development of the Australian minerals industry over the next 20 - 30 years. Nine hundred and fifty-nine participants rated the importance of 11 issues and six drivers (generated from interviews with AusIMM members), and 236 of these participants also provided qualitative descriptions of the future. Issues were defined as problems or opportunities for the minerals industry that may be controlled or influenced by the industry, while drivers were defined as those factors that will influence the direction of the industry that are not within the control of the industry. The quantitative data revealed that the top four issues, in order of their perceived importance to the Australian minerals industry, were: investment in exploration, workforce, health and safety, and innovation. The top three drivers in order of their perceived importance, were: economics of mining, global context and Australian society. While the top four issues were largely consistent across professional groups examined, metallurgy and mineral processing professionals rated water inputs and energy inputs significantly higher than the other professional groups. For the list of drivers, there was strong agreement regarding their ranked order of importance across the professional groups examined. Within the qualitative data, however, a single issue (technology) and a single driver (economics of mining) dominated participantsÆ descriptions of the future. These findings provide important input into a broader program of scenario development for the Australian minerals industry being undertaken by CSIRO and its partners. The results of this study demonstrate the importance of using a mixed methodology in generating these inputs to understand more fully how important stakeholders view the future and the factors that will shape it. The results of this study are also discussed with respect to the role that CSIRO may play in facilitating the exploration of uncertainty around the future of the Australian minerals industry.

Jan 1, 2009

By M. Saghaeian, R. Hejazi, M. Mohammadinejad, M. Zare

"Water quality and quantity at the Tailing Thickening Section of processing plants is considered to be a crucial factor and impacts the performance of several sections. Therefore, gaining stable and effective performance at the Tailing Thickener Section is one of the principal goals of minerals processing plants. Different factors such as: qualitative and quantitative sustainability of plant feed, the balance between the mass of input and output water flow, the dissolving method and distribution of flocculant and the amount of dirt, solid percent of thickener inlet pulp, affect the performance of Tailing Thickener. The present study investigates the successful improvement of Tailing Thickener performance at Jalal Abad Hematite Iron Ore Concentrate plant through optimizing the above operational parameters. For this purpose, the following optimizations have been done: homogeneity and sustainability of plant input feed rates, fine pulp removal collected by the bag filters at the input of the thickener, adding an quietness box before moving the tail pulp into the thickener to reduce the pulp turbulence, replacing flocculant pump and injection pipes, improving water mass balance which leads to optimizing and stabilizing the concentration of input tail pulp into the thickener, adding a mixer to increase the flocculant preparation time, increasing the locations for adding flocculant to thickener from 1 point to 6 points. Applying the above modifications and monitoring the Tailing Thickener performance over the course of months, has led to the improvement of recovered water quality from 500 ppm to 200 ppm, increasing the solid underflow of the thickener from 40% to 48.5%, and similarly, reducing water loss by 60%. Of other important effects, due to improvement of water quality, grade of final concentrate 0.5% increased and because of 73% increase in monthly working hour, concentrate tonnage 55% increased. Finally, sludge thickener optimization has had a significant effect in selecting and designing the dewatering system from the underflow of the sludge thickener."

Jan 1, 2018

By W. H. Yarroll Discussion by W. A. Griffith

W. A. Griffith (Head, Research Department, Phelps Dodge Corp., Morenci, Ariz.) - It is gratifying to see the increasingly common use of classical statistical procedures by metallurgical researchers. Mr. Yarroll has given excellent illustrations of the utility of multiple correlation analysis of complex metallurgical data. Our experience in applying these procedures to historical plant operating data has differed, however, from that which he suggests. The uninitiated frequently assume that the volumi-

Jan 1, 1969

By Pedro Jorge Walburga Keglevich de Buzin

A presença de elementos residuais nas sucatas ferrosas pode influenciar a qualidade do aço produzido na aciaria elétrica. Além disto, o cloro existente nos materiais orgânicos que acompanham as sucatas leva a problemas de ordem ambiental. Por este motivo, o acompanhamento destes contaminantes através de métodos de amostragem de sucata se torna uma tarefa importante na aciaria elétrica. Neste trabalho são apresentados alguns procedimentos de amostragem de sucata, bem como uma análise comparativa de sucatas processadas por moinhos do tipo shredder e sucatas sem processamento. Os resultados mostraram um aumento da densidade e a redução do teor de contaminantes (matéria orgânica, alumínio e aço inox) para a sucata processada por shredder em comparação com a sucata sem processamento. Complementando, é apresentado um perfil da concentração de cloro em diversos materiais orgânicos comumentemente encontrados nas sucatas.

Oct 30, 2017

By Eric Sitorus, Septian Prahastudhi, Roy William, Wieda Azani

In July 2020, massive slope failure occurred in the southeast corner Grasberg open pit. This was the final episode in the breakthrough of Production Block 2 South (PB2S) of the Grasberg Block Cave to connect to the surface. This breakthrough had been rapidly evolving during the first half of 2020 and occurred as expected with no adverse impacts to safety or operations. To manage and safeguard the exposure to the workforce and operations, numerous hazards were identified and anticipated. The failure of the sill pillar between the open pit and PB2S cave was identified as the main area of interest and was closely watched during the failure process. This paper reviews the systematic approach developed to convert monitoring data into information around the collapse of the GBC PB2S cave sill pillar. The data that was interpreted consisted of micro-seismic, piezometric, ground-based radar and observational inspections. Geological structures on the boundary of the PB2S cave were clearly involved in the breakthrough process. As the cave propagation reached these structures and triggered instability, the resulting acceleration and breakdown were clearly shown by IBIS radar units associated with high movement in the slope. The focus of this paper is on the evolution of changes seen in the micro-seismic data and how it was used to understand the rapidly changing conditions of the sill pillar. The seismic parameters evaluated were event distribution, Es/Ep value, and the seismic moment tensor inversion. The changes of breakthrough indication seen in these parameters were substantiated by Shear Wave Splitting (SWS) analysis that showed a close correlation with the fractured zone above the PB2S cave as indicated by the increasing anisotropy.

Jan 1, 2022