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By Barnaby J. Watten, Sibrell. Philip L., Brian J. Vinci, Andrew E. Friedrich

We evaluated a new process for remediation of acid rock drainage (ARD). The process treats ARD with intermittently fluidized beds of granular limestone maintained within a continuous flow reactor pressurized with CO2. Tests were performed over a thirty day period at the Toby Creek mine drainage treatment plant, Elk County, Pennsylvania in cooperation with the Pennsylvania Department of Environmental Protection. Equipment performance was established at operating pressures of 0,34,82, and 117 kPa using an ARD flow of 227 L/min. The ARD had the following characteristics: pH, 3.1; temperature, 10 OC; dissolved oxygen, 6.4 mg/L; acidity, 260 mg/5; total iron, 21 mg/L; aluminum, 22 mg/L; manganese, 7.5 mg/L; and conductivity, 1400 uS/cm. In all cases tested, processed ARD was net alkaline with mean pH and alkalinities of 6.7 and 59 mg/L at a CO2 pressure of 0 kPa, 6.6 and 158 mg/L at 34 kPa, 7.4 and 240 mg/L at 82 kPa, and 7.4 and 290 mg/L at 117 kPa Processed ARD alkalinities were correlated to the settled bed depth (p<0.001) and CO2 pressure (p<0.001). Iron, aluminum, and manganese removal efficiencies of 96%, 99%, and 5%, respectively, were achieved with filtration following treatment. No indications of metal hydroxide precipitation or armoring of the limestone were observed. The surplus alkalinity established at 82 kPa was successful in treating an equivalent of 1136 L/min (fivefold dilution) of the combined three ARD streams entering the Toby Creek Plant. This side-stream capability provides savings in treatment unit scale as well as flexibility in treatment effect. The capability of the system to handle higher influent acidity was tested by elevating the acidity to 5000 mg/L with sulfuric acid. Net alkaline effluent was produced, indicating applicability of the process to highly acidic ARD.

Jan 1, 2000

By F. Leschhorn

A computer model for long-term production scheduling is presented. By combination of different operations research algorithms it has been possible to design a system which is able to solve difficult long-term planning problems. The practical application of the model by a west-german hard coal mine is shown. It is proven that the EDP-model provides substantial support to the planning engineer by solving complex optimization problems.

Jan 1, 1989

By R. A. Jankowski

Although the number of operating longwall mining systems has remained relatively constant, longwall production levels during the last five years have increased significantly. In the United States, longwall mining now accounts for approximately 50% of all underground coal production. While longwalls are highly productive and offer other advantages, operations employing this method of mining continue to experience dust-compliance problems. This increased longwall productivity has meant that far more dust is being produced. An improved understanding of the longwall face-ventilation system and the advancement of face-ventilation technologies are necessary to ensure all face personnel are allowed to work in an environment that is free of excessive levels of airborne respirable coal mine dust. The Dust and Toxic Substances Control Branch, National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, examined several basic principles of the long wall face-ventilation system and has evaluated the effectiveness of numerous improved face-ventilation techniques for longwall mining systems. These include identifying improved techniques for measuring face-ventilation parameters on longwall mining sections and investigating the fundamental relationship between face airflow and the entrainment and dilution of respirable coal mine dust. Studies have been completed to determine the impact on face dust levels of using belt entry air to ventilate the longwall. Novel methods have been identified to increase the face air¬flow and to manage face airflow to effectively minimize dust exposure to face workers. Unique systems of auxiliary face ventilation have been developed and evaluated at full-scale, simulated longwall test facilities. The theoretical and applied aspects of each of these principles and technologies are discussed. Application of these results throughout the longwall mining industry, as documented from surveys conducted in the early 1980s and 1990s, have reduced the health hazard associated with excessive exposure to respirable coal mine dust.

Jan 1, 2000

By Kevin Hegerle

The Henderson Mill has operated over a wide range of production rates, feed grades, manpower levels and recovery targets since start-up in 1976. Henderson Mill personnel, both management and hourly, have successfully responded to these changes by not only maintaining unit costs, but by actually decreasing unit costs. Methods of cost reduction have included conventional austerity programs, innovative technological improvements and creative work schedules. This paper addresses both maintenance and operating cost reductions and efficiency improvements.

Jan 1, 1986

By Calvin L. Stevenson

The probability of a particle passing through a maze is predictable and consistent. This principle may be utilized to effect a particle size separation of materials by presenting a physical maze to a stream of material that will allow the fine particles to pass, while deflecting the coarse particles. A maze is effective even though all apertures encountered are many times larger than the particles being separated. By designing a machine that allows the probability parameters to be controlled and varied without changing physical dimensions, probability sizing becomes a useful tool for the separation of granular materials.

Jan 1, 1967

Seven legendary figures of American mining will be enshrined in the National Mining Hall of Fame in ceremonies on Saturday, Sept. 7 at the Little America Hotel in Salt Lake City, UT. The 15th annual induction banquet will begin with a reception at 6 pm, followed at 7 pm by the dinner and the program. Of the seven inductees, one is living. He is Alexander Murray (Bud) Wilson, 80, of Los Altos, CA. Wilson led Utah Construction (later Utah International) to become one of the world’s most diversified and successful mining companies in the 1960s and 1970s. It was acquired by General Electric in 1976.

Jan 1, 2002

By Song Xiaotian

Studies have been carried out to optimize the VCR&apos;s mining sys- tem on the basis of synthetic analysis at Fankou Pb-Zn mine in Southern China. The synthetic e- valuation method is proposed for selection of mining alternatives and stope dimension optimization techniques. Theoretic calculation and computer optimization of the fragmentation of rock blasted by multispherical explosive charges are discussed. The mathematical and optimal fragmentation models are built. The optimum model is built for the main mining operations such as drilling, blasting and haulage. Lt can be used to evaluate VCR?s mining projects, select mining parameters and provide design fundations. From the point of view of system research on the geomechanical process, stoping technological process and benefit, the complex method of optimization is proposed for VCR&apos;s mining. Using computer simulation, based on this model, the optimal parameters are established and analysed. An effective approach is provided for research on the mining method optimization and getting better economical benefits from the application and improvement of VCR&apos;s method.

Jan 1, 1986

By T. J. Joiner

A critical demand exists to develop new mineral resources, and the need for exploration techniques to supplement costly test drilling is becoming; more acute. In the past few years more industries have begun experimenting with geophysical methods to locate and define mineral deposits and delineate reserves. The new techniques have proven profitable in many instances. As a part of a broad long range program to study the mineral resources of Alabama, and in response to requests from land owners and mining companies, the Geological Survey of Alabama is investi¬gating the occurrence of bauxite and kaolin deposits in the Eufeula area. This project is supported by special funds appropriated for this purpose by the Alabama Legislature.

Jan 1, 1966

By William T. Barrett

It is said that Thales of Miletus, 600 B.C.,1 was aware of the attraction of lodestone toward iron and highly magnetic minerals. However, the birth of magnetic concentration followed shortly after the invention of the first electromagnet by Sturgeon in 1825. Sturgeon&apos;s magnet was described in the annals of electricity.2 The first attempts to concentrate minerals by the use of magnets date back to about 18473 but the first commercial drum-concentrator was apparently invented by R. Cook in 1849. Credit must also be given to the invention of P. Righter&apos;s machine in 1867,5 and to the highly successful Wenström separator devised in Sweden in 1883.8 Since the advent of these early separators there have been virtually hundreds of patents granted covering minor modifications of drum-type magnetic separators. The more important advances from a technological viewpoint have been the design of stable power supplies for d.c. magnets, the advent of ceramic permanent magnets which are now replacing electromagnets for the concentration of ferromagnetic minerals, and advances in general magnet and machine configurations.7 One of the problems facing both the designer and the user of magnetic separators is the evaluation of the body forces acting on particles in the magnetic field of the separator. Perhaps the most elegant method of evaluating the body force associated with a drum-type magnetic separator is that recently suggested by W. F. Brown.8 Brown measures the radial component of the field intensity one-half inch from the drum surface and fits a Fourier series in the angle about the drum axis (Figure 1). Once the coefficients of the series are known, it is then possible to calculate [ ]

Jan 1, 1970

By Wolfgang Sand, Alex Schippers, Tilman Gehrke, Thore Rohwerder, Peter-Georg Jozsa

Metal sulfides are degraded via thiosulfate (pyrite) or via polysulfides and sulfur (sphalerite, galena, chalcopyrite) by leaching bacteria The attack on the crystal lattice is either effected by only iron(III) ions or by iron(III) ions and protons, respectively. Consequently, different endproducts are formed. For a control of ARD-processes, these reactions need to be hown to regulate them. Experiments in percolators up to 65 m3 with inorganic compounds like fluoride, concrete, or SDS resulted in differently lasting inhibition. Microcalorimetric measurements of microbial leach activity allow monitoring of these effects with respect to active bacterial cells, and, in addition, the amount or rate of dissolved metal sulfide allowing prediction of possible endangerment by ARD.

Jan 1, 2000

By M. P. Roy, P. K. Singh, A. K. Mishra, Ashish K. Vishwakarma, Vivek K. Himanshu

Ground vibration is one of the major hazards produced by rock-blasting operation. The accurate prediction of vibration is necessary for designing controlled blasting parameters. The existing vibration predictors consider maximum explosive charge weight per delay and distance as the parameters responsible for ground vibration. These predictors are based on the assumption that the geometrical parameters of the blast will be constant for a site. However, the mining sites with bigger production targets have varying geometrical parameters to suit the excavator utility. Accordingly, the other blast design parameters will also have an impact on ground vibration intensity. A principal component analysis is a dimension reduction technique. This technique along with multivariate logarithmic regression has been used in this paper to predict the ground vibration. The technique has classified the blast design parameters into four principal components. The regression with the scores from these principal components has been carried out. The evaluation of the model performance of predictors along with the existing empirical predictors has been carried out using R2 and RMSE values. The evaluation suggests that the predictor with logarithmic regression followed by principal component analysis gives better performance with respect to the existing empirical predictors.

Jul 30, 2022

By Z. T. Bieniawski

In the past 15 years, rock mass classifications have experienced unprecedented development and have emerged as powerful practical methods for assessing ground conditions and tunnel support. Such methods as the RMR System (Geomechanics Classification) and the Q-System have provided many advantages over the classical Terzaghi rock-load method introduced in 1946. These new classifications have found wide applications all over the world but some doubts have been expressed and shortcomings pointed out. The author, who developed the RMR System, takes a penetrating look into the promises and the pitfalls of modern rock mass classifications. He dispels some misconceptions and shows how rock mass classifications can serve as effective and dependable design aids in tunneling.

Jan 1, 1987

By V. J. Kecojevic, W. A. Wilkinson

Mining companies are increasingly looking at Global Positioning System (GPS) technology coupled with 3D mine planning and visualization systems to deliver increased productivity and reduction in operating costs in drilling and blasting operations. Leveraging GPS into drill and blast operations requires that a drilling plan be developed and imported into the GPS to guide the operation to a planned and desirable outcome. State-of-the-art mine planning software systems provide the engineer with a 3D environment in which to design and visualize drill and blast plans. This paper discusses producing and exporting 3D drill and blast plans to GPS and how some coal companies are utilizing GPS and mine planning software technology in the drill and blast process.

Jan 1, 2004

By Pramod C. Thakur

Floor gas emissions on wide longwall faces are common occurrences in the Northern and Central Appalachian basins. It creates unsafe working conditions on the face and results in very costly production delays. This paper discusses various methods of mitigating the floor gas emissions including hydrofracing of underlying strata, use of cross-measure boreholes and specifically completed gob wells.

Jan 1, 2005

By Jan Wolski, Jack Barry

Ventilation ductlines with a single fan or with a series of fans are analyzed. The duct friction loss factors are discussed. Numerical solutions, presented in the paper, applies to any fan number and locations along a duct line. The findings are compared with formulas available in the technical literature. Values of the air leakage factors are presented in the SI, technical metric, and US unit systems. A method is shown of how to determine the leak- age factor for a given ductline. Optimum solutions for the sample duct lines with two and five fans in series are discussed and presented in a graphical form. Performance of fans in series is discussed in conjunction with both friction pressure loss and leak- age.

Jan 1, 1997

By N. Rajmohan, K. T. Jacob

Presented is a thermodynamic feasibility analysis of extracting base metal chlorides from low-grade, multi-metallic oxide ores using CaC[1]2 as a chlorinating agent in the presence of SO2 and O2. The oxides react to form corresponding chlorides, while CaC[1]2 is converted to CaSO4. The Ellingham diagram is used for comparing the standard Gibbs&apos; free energy change for the sulfation-chlorination reaction of a large number of oxides. Except for alumina, silica and chromia, most of the other metal oxides will be converted to their respective chlorides. The volatile chlorides can be condensed, and the chlorides present in the condensed state can be leached. A process is proposed that uses a nontoxic chlorinating agent and gives an efficient separation of the metallic values from the gangue.

Jan 1, 1993

By Keith Sarbutt, I. Jackman

The recovery of gold from a high grade telluride/sulphide flotation concentrate was investigated. Conventional cyanidation resulted in very slow rates of gold extraction. Historically, the refractory nature of tellurides has been overcome by fine grinding, the use of excess lime and long leach times. In some instances, pre­oxidation of the tellurides has also been necessary, to render the gold soluble in cyanide solutions. The former conditions did improve the rate of gold extraction from the present sample, but final recovery was still unacceptable. Chemical oxidation of the tellurides and leaching with oxygen improved gold recovery further. However, it was found that simple modifications to the cyanidation conditions overcame the detrimental effects of the complex chemistry involved in leaching a telluride concentrate. The incorporation of a solution change, or the application of a carbon-in-leach procedure increased the recovery of gold to over 97 percent in 96 hours. In every case, leaching was enhanced by the addition of lead salts.

Jan 1, 1990

By Roy Norcross, Stephen Gos

For over 100 years Degussa has worked together with the min­ing industry not only providing quality products but also develop­ing technologies to support these products through value added goods and services. For cyanide, these technologies include leach enhancement processes such as PAL™ and Solidox™, and cyanide detoxification with peroxygen based processes such as SILOX™ and Caro's acid using our DegOX™ technology. Degussa has also made important advances in how sodium cyanide is packaged and shipped with our liquid NaCN plant joint venture with MSI, CYANCO in Winnemucca, Nevada, and our Advantage SLS™ solid to liquid cyanide delivery system. All of these innovative technologies developed to support NaCN in mining, provide value to our customers and show Degussa's commitment to Responsible Care·11.1 and dedication to product stewardship. With Responsible Care and the customer in mind, Degussa has developed Advantage CCS™ cyanide control system, which will soon be available for the North American market. Currently there are several CCS units in service installed by Degussa AG (Germany), and we are in the process of designing the next gen­eration of the CCS which should be completed by late '98. Based on our experience working with gold and silver mines all over the world, there appeared to be an opportunity to further assist our customers by providing a better more automated way to control their cyanide additions. By providing the mine with an accurate method for maintaining their desired cyanide levels in their leach circuits, we could help them avoid underdosing and the associated gold and silver losses, and overdosing the cyanide which not only wastes cyanide but may increase treatment costs as well. In the early 1990's, when we began to introduce our CCS units, there were several cyanide controllers and on-line analyzers avail­able. However, they appeared to be too complicated and not made to stand the harsh conditions inside a mill. This resulted in exces­sive downtime and poor analytical results. We also found that many units would be installed but not commissioned by the sup­plier. Based on these observations, along with filtration and con­trol problems on some existing units, Degussa decided to design its own cyanide control system based on our extensive knowledge of cyanide chemistry, using the best components available worldwide.

Jan 1, 1998

By R. K. Simpson, C. S. Eldridge, M. H. Tyler, J. P. Hodgkison

The WMC Olympic Dam Operation in South Australia is an integrated site, involving brown fields exploration through to production of copper cathode, uranium oxide, gold and silver bullion. The Geology and Analytical Services (GAS) Department reflects this totality and, therefore, is perhaps a unique construct in the industry. It comprises Geology, the Metallurgical Laboratory and the Analytical Laboratory, offering a single point of contact in matters of metal discovery and tracking through mine design, production, beneficiation and final product certification. This structure promotes value adding by removing traditional barriers between groups that can deliver more, collectively, than as individual units. This approach to value adding by bringing disparate groups together is echoed in each of the three sections where enhancements in the traditional value adding activities have been delivered by multi-skilling and encouraging overlapping involvement.

Jan 1, 2002

Compagnie Miniere Esperance (CME), a mining company based in French Guyana, operates a gold primary ore body in open pit. The ore is processed through crushing, grinding and gravity separation. Tailings are stored in a ?fine? pond. Analyses of the fine ponds proved a residual gold grade sufficient for a chemical treatment. However, direct cyanidation would require a too large installation, regarding the local conditions (accessibility, supplying and rainforest meteorological conditions). It has been then decided to test the feasibility of a pre-concentration using flotation. Lab tests have been carried out by SGS Lakefield (Canada) in March 2007, which proves the technical feasibility. Therefore, CME asked Caspeo to: ? Carry out an on-site flotation pilot campaign. ? Design an industrial flotation circuit. The tailings reprocessing will contribute to a better tailings management and a dry up of the gold resource, limiting the risk of illegal mining after remediation of the CME site. CME MINE The Esperance gold mine is located in French Guyana, in the vicinity of several gold deposits as Omaï, Rosebel or Camp Caïman, holded by Iamgold and Newmont. These main gold deposits are located on the figure 1. Esperance was put into operation in the early 90?s. The first years were devoted to the mining of alluvial gold in the gravel of the Esperance Creek. Since then, operation was led in the primary gold deposit. Annual production is on average 254kg for a total production in fifteen years of 4300kg. Geology Esperance deposit is located in the greenstone belt of the Guyana Shield. Mineralization is in tectonic contact between sedimentary basin of Maroni and a granitic massif. Clastic series, composed of conglomerate and lamina sandstone, overlie a volcano-sedimentary basement (series called "Paramaca"). The area is strongly folded by shear movements, resulting from granite deposit. Gold is in interlacing quartz veins intersecting the clastic series. Gold is present in association with pyrite. Other elements, as silver or arsenic, are in negligible quantity. Exploitation The Maroni River is the only access to the Esperance mine. Only the saprolite and a part of the transition rock are extracted in the open pit. Excavation works are done using shovels Hyundai 450 (4 units) and haulage works using articulated dumpers Terex TA35 (4 units). These two sorts of equipments are presented figure 2. Mill The mill is composed of crushing and grinding processing plants. After gravity concentration, both plants produce tailings that are stored in two ponds: the first pond contains coarse product which segregates the particles crushed to 2mm upstream and settled clays downstream; the second pond contains the fine product made of particles ground to 200µm. These two ponds, bordered by dams and diversion canals, are located on former alluvial sites of Esperance Creek (see figure 3). [ ] The CME mill is currently producing gold concentrate, with a global recovery of about 67%. The ore is crushed by one jaw crusher and two hammer crushers. The ore then passes through a Knelson KC 48 gravity concentrator, producing a first gold concentrate. The

Jan 1, 2009