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By F. Aurelian

The development of the uranium mining industry in Romania started in 1950. The exploitation of Bihor region, one of the most important metallogenic zones of the country, began in 1962. Uranium exploitation activities were ceased in 1995 due to the exhaustion of the ore deposits. Between 2001 and 2002, due to the entire mining zone closure, ecological rehabilitation and decommissioning was initiated. The proposed solutions, concerning terrain, equipment and buildings utilization were elaborated according to the guidelines of the Romanian Environmental and Nuclear Authority.

Jan 1, 2006

By A. L. Mular

Si define la simulación digital y las técnicas de simulación son revisadas. La metodologia tipica conlleva la selección de modelos, el ajuste o reajuste de los datos primarios, la selección de una estrategia de acoplamiento, la valoración de la precisión del modelo en un sentido estadistico, y el desarrollo de estructura de simulación ejecutiva. La simulación sirve de ayuda para los ingenieros de procesos para evaluar la viabilidad de un esquema de flujo propuesto y el efecto de la modificación de un flujograma ya existente. Por otro lado, la simulación juega un papel importante en la optimación "off-line" y en la evaluación de estrategias de control de circuitos alternativos. Son presentados varios ejemplos para ilustrar estas utilizaciones para la simulación, incluyendo aplicaciones en los circuitos de trituración, circuitos de molienda y circuitos de flotación. Es de opinión de los autores que, dentro de la próxima década, las plantas de proceso de minerales serán estudiadas rutinariamente a través de una simulación digital durante las etapas preliminares de diseño. La simulación constituirá un importante componente en la toma de decisiones de un proceso.

Jan 1, 1982

By A. K. Bhowmick

Size reduction is very energy intensive and is the single most power-intensive operation in mineral processing plants. Research has shown that only a small part of the energy is utilized efficiently. One of the major thrusts of all equipment manufacturers has been to improve this efficiency. Choosing the right equipment to maximize energy utilization in any comminution application has always been the utmost criteria. Due to the high energy cost and depletion of good grade minerals, it is becoming essential to optimize all the subsystems within a given comminution system for the overall economic success of such ventures. Bradley Pulverizer Company of Allentown, Pennsylvania recognized this and started offering its Feeder Controller in 1988 for automatic feed control. After its first successful operation, Bradley made this as a part of all of their grinding system standard offering. It was also recognized that the Feeder Controller was just a beginning and more automation and controls would be required for an overall, efficient grinding system.

Jan 1, 1993

By B. J. Arnold, B. W. Parker

Rosebud Mining Company added a classifying cyclone/spiral concentrator circuit addition to its McVille Preparation Plant, Freeport, PA, in mid-2002. This paper will describe the plant addition, which was implemented fully by plant staff, and review improvements in cleaning plant performance and economics.

Jan 1, 2003

By Tsuneyoshi Funazaki, Takayoshi Nakamura, Keizo Miki, Takashi Imaishi

The underground portion (about 10 km) of Tokyo Wan Aqua-Line consists of eight shield tunnels connected with Kawasaki Man-Made Island in between, at four underground locations. The connection work had to fulfill strict precision and safety requirements in the ground about 60 m below soft seabed, but was completed successfully in May 1997. This report describes the connection work in detail, featuring the method of investigating shield machines’ relative positions, ground freezing method and connection mechanism and procedures. It also mentions the present state of Tokyo Wan Aqua-Line that was put in service on December 18, 1997.

Jan 1, 1999

By Michael Bayerl

The HILTI OneStep rockbolt was implemented for roadway development in German deep coal mines in 2004. The development by HILTI Company is based on a technical joint venture with RAG Deutsche Steinkohle AG. The technical development of a One-Step bolting system was required for weak strata conditions at the roadway development face. Standard resin bolting has reached the limit of performance when boreholes are squeezed and cannot be filled with capsules. In some cases the heading face is brittle and requires additional support for installation of the bolts and a person working immediately next to the borehole. The Hilti One-Step system allows automated and safe processing at the heading front and provides the key technique to avoid these problems.

Jan 1, 2009

In underground coal mining, one of the biggest challenges is spontaneous combustion, which will not only present safety hazards but result in reserve losses as a result of burnt coal. The released heat coupled with other combustible gases commonly encountered underground will significantly increase the risk of explosion. In this paper, three-phase foam as an environment-friendly fire fighting agent composed of nitrogen, water and fly ash is introduced. The nitrogen facilitates inertization of the fire zone; the water helps cool down the fire and the fly ash can closely cover the coal to isolate the oxygen. What's more, the fly ash and the foaming agent are good free radical absorption. The comprehensive merits mentioned above make three-phase foam quite effective in quenching spontaneous combustion. Experiments indicate that three-phase foam can significantly slow down the temperature rise of coal during oxidation. The comparison between slurry and three-phase foam shows that the latter one is capable of flowing upward in the porous media so as to extinguish the high-point fire and concealed fire.

Jan 1, 2011

By Juan H. Rojas

The Chuquicamata mining and metallurgical complex is the main division of CODELCO-CHILE. Its comparative advantage in the world of primary copper producers had deteriorated severely and, consequently, its top management launched an extensive modernization plan. This paper shows how Chuquicamata recovered its position as a low-cost copper producer and is now well positioned to face the end of this century, as far as competitiveness is concerned. It also shows the company's vision for the )(XI century. Given the volume of its ore reserves, one possibility is expanding the sulfide production line capacity, while in the case of the oxide production line, ore reserves are limited so that there is a need to maximize the effectiveness of both organization and technology use. A final consideration has to do with the balance of supply and demand. Most observers of the copper market agree that supply is growing faster than demand. On the other hand, copper is facing severe environmental problems, especially in the piping business, plus the usual threat of substitution. Nevertheless, copper producers are making very weak efforts to defend the market and increase copper consumption through the promotion of new uses of the metal. This issue is crucial and must be considered if copper producers want to maintain a profitable market.

Jan 1, 1998

By M. P. Hardy, C. J. H. Brest van Kempen, H. N. Maleki

To evaluate the influence of uniformly tensioned roof bolts on roof stability, mechanically anchored roof bolts were installed using the conventional bolter and a specially developed thrust and torque controlled retrofitable box mounted on a bolting machine. Thirteen thousand bolts were installed over 19 crosscuts in a 4 heading development in an operating coal mine. Geological , bolt and mine parameters were recorded at bolt installation, and bolt tension histories, roof sag and other changes evident in the rooms, crosscuts and intersections were recorded over a 2 month period. In all, 24 variables and 11 responses were quantified at 67 bolt clusters. These data were analyzed statistically to determine the significant variables influencing roof stability. As the mine development was safe and stable during the monitoring period, roof sag after two months was used as an index to quantify "stability." The variables of significance were shown to be coefficient of variation of bolt tension, bolt anchorage capacity, roof lithology, roof shape, standard deviation of bolt tension, and dip of roof lithologies. It was concluded that of the variables with which the mine operator has control, bolt tension uniformity was the most significant parameter at this mine. Other variables, such as intersection type and time between mining and bolting , were not significant, whereas, some other potentially significant variables such as horizontal stress or roof joint frequency did not vary sufficiently for their influence on stability to be evaluated.

Jan 1, 1986

By R. E. J. Putman

The past ten years have witnessed substantial development of electronic equipment for execution of process control functions. The methodology of giving instructions to the data-handling system and the organization of the system, both the equipment and instruction coding taken together, have developed simultaneously. Examples of the technology specific to the mineral processing industry can be cited. Approaches to system design developed for the Pinto Valley concentrator incorporating slave and master data processing have been described by Arney, and his associates (1974). Madge (1970) has described the hierarchical systems employed at the operations of Cominco Ltd. The Kennecott Garfield smelter is controlled by a system of microprocessors linked to a general purpose data processor (Marchant, et al., 1977). These systems provide innovative approaches to couple advancing technical capability in electronic data processing to the objectives of process management. The current state of the art described in this chapter is certain to require updating in the 1980's with the advances in technology anticipated.

Jan 1, 1979

By R. V. Ramani, K. V. Raj

"The air flow problems in open pit mines are complex. Computational fluid dynamics (CFD) models provide a detailed knowledge of the airflow pattern and velocity distribution, temperature, and pollutant concentration within an enclosed domain of the open pit. A range of turbulent model can be selected for varying complexity and accuracy. Pollutant transport models, however, differ in their assumptions and structure as well as in the algorithm they use; as a result, prediction varies from model to model. This paper presents a study of pollutant transport in an actual open pit mine under stable boundary layer. The objective is mainly to test two turbulence models using the same input conditions, model constants, and similar geometry. Measured data are used to compare results of the two CFD models, namely, the kappa-epsilon (?-e) model and the Large Eddy Simulation (LES) model. Despite the complex synoptic situations, different meteorological input data and the fast changing conditions, the simulation results from both the models are in good agreement regarding the dispersion of pollutants.INTRODUCTION Modeling of contaminant transport under Arctic air inversion is an important step for an assessment of the amount of pollutants within the open pit. The Airflow in open pit mines is of larger scale and does not follow the principles of pipe flow. The air flow problems in actual open pit mines are thus far more complex. CFD models provide a detailed knowledge of the airflow pattern and air velocity distribution, temperature, and pollutant concentration within an enclosed domain of an open pit. There is no known application of CFD in three-dimensional modeling of air flow in large open pit mines. Two equation RANS kappa-epsilon (?-e) and Large Eddy Simulation (CFD) models, however, have been developed to solve the stable boundary layer (SBL) problems in Atmospheric Sciences (Baklanov 2000, Basu and Porté-Agel 2006, Dop and Axelsen 2007, Bandopadhyay et al. 2014). Because an exact flow situation in open pit mines is not known a-priori, it is therefore, necessary to investigate various turbulent models to identify the appropriate model that would simulate the flow phenomena with reasonable accuracy, and predict the contaminant distributions within the pit. Dispersion models differ in their assumptions and structures as well as in the algorithm they use and, as a result, predictions vary from model to model. Furthermore, it is also important to investigate the behavior of a CFD model in simulating a complex phenomenon such as the transport and distribution of contaminants in open pit mine under Arctic air inversion. The simulation of an enhanced period of turbulence in SBL is of particular interest because traditional air pollution dispersion models cannot explicitly treat such intermittent events, and yet the SBL is often the worst-case scenario in an open pit pollution transport"

Jan 1, 2015

By Stephen C. Tadolini, Thomas M. Barczak

Western mines have had limited choices for standing support. Wood cribs were often too soft and unstable. The introduction of the Can support in the early 1990’s provided a very effective alternative and remains the dominant form of tailgate support. Water-filled prestressing cells are now used to cap the Can and preload it to provide an active roof load. The Cluster Prop, consisting of three timber wedge props bundled together, provides more capacity than an equivalent sized Can support and improves transport efficiency. However, the Cluster Prop is less stable and does not maintain a consistent load throughout its loading profile. Pumpable roof supports are another alternative support, but they have not been proven in high deformation environments. Alternative supports are also being used in longwall recovery operations. These include the Rocprop and Omni Prop, which are extendable support systems. They also provide active roof loading which can be beneficial in these applications. Specialty supports, such as the Sand Prop and Spider Prop, have also been introduced into western longwall operations. This paper compares the performance characteristics of these various support systems.

Jan 1, 2005

By S. Frimpong

The coal mining industry is an important sector of Canada?s economy. The cost of mining and haulage of coal in Western Canada is a major focal point when compared to inexpensive coal from Australia. Spot coal price volatility affect contractual price arrangements and this creates pressure on companies? profit margins and their competitive edge. In order to alleviate this pressure, companies may have to take short-term drastic measures that may hurt their strategic positions in the long-term. Companies must also create a mix of their products to ensure effective maintenance of profit margins given various quantity and quality constraints. In this paper the authors provide extensive analysis based on detailed probabilistic production systems for coal extraction and haulage in Western Canada. An optimization model is formulated for typical coal mining operations, processing and haulage from mine sites to the Vancouver Ports using linear programming algorithm. A stochastic model is also formulated to analyze the associated risks and uncertainties. These models are validated using data from five operating mines in Western Canada with varying quantity and quality products and uncertainties. The results show that the five mines studied have to produce between 180,000 and 2.10 million tonnes of metallurgical coal and between 70,000 and 2.16 million tonnes of thermal coal to enhance their profitability given the underlying constraints. The average expected probability of success associated with production capacities from these mines is about 66%. This results in a failure probability of 36%, which is extremely high under contractual arrangements. The results also show that management?s profit expectation of $83 million can be achieved at a zero percent failure probability. With a higher risk of failure of 10%, this expectation increases by 21% to $100.3 million.

Jan 1, 2011

By Yashar Pourrahimian, Roberto Noriega

Truck fleet dispatching plays a crucial role in reducing operational costs and fulfilling operational targets in open-pit mining operations and is subject to large uncertainty arising from the operating cycles of trucks and loading equipment. This paper proposes a reinforcement learning-based truck dispatching system. Reinforcement learning is a machine learning area that deals with learning an optimal sequential decision-making strategy in an uncertain environment. An open-pit load-and-haul simulation is developed that also captures the truck movements and interactions in the shared road network, and a Neural Network is successfully trained to suggest truck dispatching decisions in a real-time manner.

Jun 25, 2023

By G. L. Alston

Rigid urethane foam can be used effectively for improving mine air conditioning systems by reducing heat and moisture transfer from mine rock to ventilating air and from mine rock to ventilation ducts, for erecting mine ventilation stoppings and overcasts, for sealings around door frames and bulkheads to prevent air leakage, for preventing spalling and sloughing of roof and rib and for erecting fire-resistant powder magazines and transformer or compression stations. Rigid urethane foam is a tough, cellular material, made by nixing diisocyanate and polyether polyol resin in accurate proportions through an applicator system, then the two chemicals react, the mixture expands thirty times its original volume with 85 to 95 percent closed cells. Within seconds, the mixture solidifies and takes a preset which will adhere to overhead or vertical surfaces. It will adhere to brattice cloth, steel, wood, concrete and rock, Excessive wetness will reduce the adherence, but in such cases adherence can be improved by preliminary application of an absorbent dust such as cement.

Jan 1, 1963

By Mark R. Bowie

Air-fall tuffs have been altered to zeolite via reaction of volcanic glass with local pore solutions at the six localities discussed in this paper. These are in the southern Basin and Range Province of Arizona and New Mexico, and in the Trans-Pecos and Coastal Plain regions of Texas. Zeolitization occurred in either closed- hydrologic, open-hydrologic, or hydrothermal groundwater systems. The tripping Spring Valley (DSV) chabazite in Arizona and the Buckhorn clinoptilolite in New Mexico originated in a late Cenozoic network of closed-hydrologic, lacustrine basins extending from southeast Arizona into southwest New Mexico. At DSV, two potentially commercial chabazite-rich tuffs are interbedded with lacustine mudstone. The main zeolite tuft contains up to 90 percent chabazite. The upper zeolite tuff averages approximately 67 precent chabazite. At the Buckhorn deposit, two clinoptilolite-rich tuffs are interbedded with lacustrine m udstone in the upper part of the Gila Conglomerate. The lower zeolite tuff contains up to 90 percent clinoptilolite. The upper zeolite tuff contains over 60 percent clinoptilolite. The Casa Piedra clinoptilolite is in the Trans-Pecos region of Texas. It formed during the Tertiary in a closed basin containing a playa lake. The Casa Piedra tuff averages about 60 percent clinoptilolite. Air-fall tuffs of the Cuchillo Negro, New Mexico and Tilden, Texas clinoptilolite deposits were zeolitically altered by either percolating ground waters in open-hydrologic systems or locally by ponded, saline, alkaline solutions. Cuchillo Negro tuffs are Tertiary and average approximately 50 percent clinoptilolite. Clinoptilolite-rich tuffs of Ebcene age have been mined from four quarries at the Tilden deposits. Tufts from the Kuykendall and Buck Martin quarries contain approximately 50 to 60 percent clinoptilolite. Low temperature, SiO2 - rich, hydrothermal solutions altered air-fall tuff to clinoptilolite and chabazite in the Foster Canyon area of the Tertiary Cedar Hills and Seldon Hills volcanic-vent zone in southcentral New Mexico. Poster Canyon tuffs contain up to 60 percent zeolite and average 40 to 50 percent clinoptilolite. The dominant mineral in the zeolite tufts at the six deposits studied is generally microcrystalline and either chabazite or clinoptilolite. Lithic fragments, unaltered volcanic glass, other zeolites, quartz, calcite, opal-CT, cristobalite, feldspar, evaporites, clays, and mafic minerals are also constituents of the tufts.

Jan 1, 1987

My "outside exploration" began in November 1908, only 16 months after I had come to Bisbee as a raw engineer. The well publicized reputations of eminent engineers up to that time, including John Hayes Hammond, Herbert Hoover, James Douglas, D.C. Jack- ling, J. Park Channing, and a few others had been due to new mines they had found or brought to successful operation. And here was I, a mere youngster, given a chance to join the group. I knew there would be disappointments but I had no idea how many of them. In spite of the many prospects that turned out to be worthless I never looked at a new one without the feeling that this one might turn out to be the big success. This confidence, blind as it was, gave every arduous examination a zest and it made me climb every mountain on which the owner said there was something worth seeing, or on which T could see a distant staining that might mean ore. If I looked at every showing the owner suggested he at least would think I was honest and would bring other properties to our attention. This reputation of never refusing to go to see an outcrop, no matter how hot the desert sun or how rough the terrain, was probably one of my best assets. High as my hopes were at the start, they proved not to be exaggerated and if I were given a chance to do it again I would not hesitate, in spite of the jaundice, rheumatic fever, and other maladies that beset some of the expeditions. On the whole the results have equaled all my hopes. Toward the end of my years of active exploration I totaled up the score. Out of the prospects submitted to us about two out of three were eliminated after questioning the owner or prospector, without an examination. This left about a 1000 mines or prospects that seemed worth at least a preliminary look. One out of seven of these was worth a little development and a seventh of this seventh turned out to be a modest success or better. And nine or ten in all, or one out of 1000

Jan 1, 1976

The need for an integrated approach to optimization of unit operations in both the pit and the mill has long been recognized, but the complexity and nature of the overall problem has up to now resisted solution. This paper reports on a modeling methodology which couples symbolic and numeric computing to unify operations in both the pit and mill. The ultimate goal of this work is to optimize all operations that are influenced by blasting. Blasting plays a key role in all facets of operations. Obviously, drilling and blasting costs are determined by blast design, but the down-stream costs that are closely related to blasting results are often treated as separate functions: loading, hauling, cleanup, and crushing and grinding are all heavily influenced. Diggablilty and bucket fill factor are a function of fragmentation, the condition of the floor and uniformity in the shape of the muck pile. Likewise, cycle times and loading delays partially determine haul cycles, while fragmentation distribution and size determines the efficiency of truck loading. Removal and breakage of oversize causes loading delays and increases cleanup costs. The influence of blasting doesn't stop at the crusher. Mill productivity, power consumption, and maintenance are a function of the feed. Even at the SAG mill a reduction of a critical particle size during blasting can increase throughput. Thus, a bottle-neck for production far removed from unit operations in the pit can be alleviated by a modification in blast design. The question is: how do we optimize blasting with respect not only to itself but to al\ related mining and milling operations? For that matter, how do we even model blasting so that we can control the results of a blast?

Jan 1, 1991

By Rudolf Kvapil

INTRODUCTION Sublevel mining is a mass mining method based upon the utilization of gravity flow of the blasted ore and the caved overlying waste rock mass. As with any other mining method, sublevel caving has advantages and dis¬advantages which must be carefully considered and evaluated. The major advantages of sublevel caving are dis¬cussed as follows: Because all of the mining activities are executed in or from relatively small openings, sublevel caving is one of the safest mining methods. Drifts, which are the pri¬mary working places, are distributed in a uniform pat¬tern on all levels. Normally the maximum dimensions of the sublevel drifts are about 5 m wide and 3.7 m high. The transportation drifts can have the same section, or the height may be increased to about 4.5 m when trucks are loaded in the transport drifts. The stability and safety of such drifts in competent rock can be easily controlled by smooth blasting or by a combination of smooth blasting with shotcreting. In less competent rock masses, stability can be achieved by combined reinforc¬ing, for example, by a combination of smooth blasting, shotcreting, and rockbolting. The major mining activities can be broken down into three groups: drifting and reinforcing; ore fragmenta¬tion, i.e., production drilling and blasting; and ore draw¬ing, loading, and transportation, and all are relatively simple. Because of the repetitive nature of the mining system, one can standardize almost completely all min¬ing activities. This means that a high degree of work efficiency can be achieved. Because the components of mining production in sublevel caving can be standardized, a high degree of mechanization is possible. In modern sublevel caving the sections of drifts and tunnels are sufficiently large to allow the introduction of large trackless mining equip¬ment. The advantages of a trackless system can be then broadly utilized not only for direct mining but also for all services, including the transportation of mining per¬sonnel to the working place. The flexibility of mining is very good. Standardiza¬tion and specialization of mining activities and equip¬ment on separate levels (lower level or levels in de¬velopment, upper level or levels in production mining) together with the trackless system yield a high degree of flexibility. This allows a rapid start-up of mining and good flexibility in making production rate changes. The method lends itself to good work concentration, organization, and working conditions. Normally, on the lower levels, various phases of development are under¬way. Upper levels are in various stages of extraction. Therefore the work can be easily organized into a sys¬tem which excludes interference between mining activi¬ties. Safety of mining (in small dimension openings), good work organization, high mechanization using large modern mining equipment, etc., comprise very good working conditions. Naturally such a system enables a high work concentration and rationalization of separate specialized mining activities and therefore mining by sublevel caving can be effective and relatively in¬expensive. The major disadvantages of sublevel caving, on the other hand, are: There is a relatively high dilution of the ore by caved waste. Various types of ore loss can occur. When the ex¬traction limit (that point yielding the maximum accept¬able amount of dilution) is reached, the remaining highly diluted ore represents an ore loss. Some ore is lost in passive zones located on the level of extraction between the active zones of the gravity flow. Part of the ore from these passive zones can be recovered together with ore extraction on the lower sublevel, but some un¬diluted and often not fragmented ore located in passive zones above the plane of the footwall is lost. In gen¬eral, these losses are larger as the inclination of the ore body and the footwall is reduced. A relatively large amount of development is re¬quired. This includes transport drifts, usually located in the footwall waste rock on each sublevel, and sub¬level drifts, which connect the active mining areas to the transport drifts and as a result are partially in ore and partially in the waste rock of the footwall. The waste rock length increases as the inclination of the ore body and footwall decreases. It also includes orepasses, used for transport of the ore or waste from the separate sublevels downward to the main haulage level, and normally driven in waste; and inclined drifts or tunnels, which provide a connection for the trackless equipment between the main haulage level and the separate sublevels and are driven in waste. Finally there is the de¬struction of the surface through subsidence. To maximize the ore recovery, minimize the dilu¬tion, and achieve a high efficiency of mining by sub¬level caving, good data regarding the gravity flow pa¬rameters for the blasted ore and the caved waste are of utmost importance. The exact type and amount of data required depend upon the purpose and needs of the study. For the first feasibility study, it may be sufficient to utilize the data from other sublevel caving operations with similar conditions and circumstances. For any higher level of mine planning it is clear that more exact data, including analytical and experimental analyses up to full-scale in-situ testing, are necessary. Basic gravity flow principles and design guidelines for the application of the sublevel caving mining method are presented in the following sections. Although some¬what simplified, they should provide a basis for mine planning and operation. The gravity flow principles described can be effectively applied to other mining situations, with some modification. Also, steep dipping coal seams can be effectively mined by modified sub¬level caving.

Jan 1, 1982

By J. L. Goodier

The paper points up the hesitance of private capital to pursue development of offshore mineral mining endeavors due to the deterrent effect of the clouded legal status of such endeavors. Some states have no laws or regulations to protect the potential exploiter. Others have regulations which give no proprietary rights of exploration to mineral discoveries. The above factors and others are discussed and analyzed in some detail, covering, in turn, summations of the federal regulations and of each of the coastal states. Some comparative analyses are provided, and some recommendations for encouragement to capital investors are made.

Jan 1, 1968