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By F. Ikumapayi

Hydrogen peroxide production was measured during the grinding of a complex sulfide ore, and its oxidizing effect on solid surfaces was investigated using Fourier transform infrared spectroscopy (FTIR) with diffuse reflectance attachment measurement. In turn, an attempt was made to correlate the formation of hydrogen peroxide, surface oxidation and sphalerite flotation. Additionally, in order to predict and minimize detrimental production problems due to the recycling of process water in sulfide ore processing, the effects of major components of calcium and sulfate species present in recycled process water and the effect of temperature on sphalerite flotation were investigated through bench-scale flotation tests using complex sulfide ores. The significance of process water species in flotation was studied using tap water, process water and simulated water containing calcium and sulfate ions. Formation of hydrogen peroxide was revealed during the grinding of the complex sulfide ore, and its formation was counteracted by diethylenetriamine (DETA). The FTIR spectrum of the pulp solid fraction showed varying degrees of oxidized surface species, which are related to the concentration of H2O2 analyzed in pulp liquid. Bench-scale flotation using two different complex sulfide ores showed that sphalerite recovery is better in process water than in tap water. Flotation results also indicated a varied recovery of sphalerite at different temperatures in either tap water or process water.

By John Newby, Edward Kennedy, Ulf Gwildis

Alluvial deposits of major rivers often provide relatively uniform tunneling conditions. However, these conditions pose specific challenges due to the tunneling behavior of the granular soils as flowing ground, if unsupported. This paper describes the design considerations and construction experiences gained during the Tunnel Boring Machine (TBM) drives for the Annacis Island WWTP New Outfall System in the Vancouver, B.C. metropolitan area. Meeting the design criteria for connecting two (2) deep on-land shafts with an in-river riser manifold required advancing a 5-meter-diameter slurry TBM through the Fraser Rivers sands and at a tunnel invert elevation with a baseline hydrostatic head of 3.4 bar.

Dec 1, 2022

By E. Watkins, S. J. SCHATZEL, K M. AJAYI, V. Gangrade, Z. Khademian

A stochastic discrete fracture network (DFN) model is developed based on mine site core log data to predict the horizontal and vertical permeabilities from the surface to the top of the caved zone at a longwall mining site in southwestern Pennsylvania. One hundred DFN realizations were generated to determine permeabilities for the isolated zone over an abutment pillar after mining the second panel. The results from this study show that the vertical and horizontal permeabilities from the DFN model agree closely with field measurements, which indicates that the resultant permeability obtained from the field measurements is representative of the predicted permeabilities. With this agreement, the aperture data for other zones of the mine could be obtained from the geomechanical model — specifically, for the fractured zone over the gob. Based on the successful validation of this model, this model could be further developed to predict the permeability of the fractured zone over the gob with fracture aperture obtained from the geomechanical analysis. This will complete the fracture characterization of the overburden, which could be used to predict potential shale gas flow to the mine in the event of a breach. This prediction could provide information on the associated risk of a casing breach and determination of methods to proactively prevent such an occurrence.

Feb 1, 2023

By David Kwietnewski

Roadheaders are gaining widespread acceptance in North America as a means for mechanical tunnel excavation. Until recently, almost all of the large-scale North American tunnel projects were excavated one of two ways ? the tried and true drill-and-blast method or with the use of tunnel boring machines (TBM), the hi-tech super-excavators. TBMs enjoyed fast-growing popularity worldwide as TBM manufacturers offered greater technology to meet the demand of the civil tunnel industry in the late 20th century. Recently, though, more tunnel projects, large and small, can thank the brute force of a roadheader for getting the job done.

Jan 1, 2011

By V. Voller

A relatively simple model of grinding which incorporates both the Bond grindability equations and the population balance equations has been extended to form a comprehensive simulation package that can describe most kinds of conventional grinding circuits. The package has two programs, with the first consisting of an input program which helps the user to specify the prescribed circuit, while the second program performs the actual simulation. The package serves two main purposes - i) as a check on mill design, with the output providing not only predictions for the product passing size but also of the full product size distribution, and ii) as a means to assess the likely effects on the product size distribution of operating under different sets of conditions.

Jan 1, 1981

By John P. Anderle

A tectonically disturbed sequence of Mississippian age evaporites expressing a 5 milligal negative gravity anomaly near Sussex in southeastern New Brunswick, Canada, was investigated by a program of drilling, geologic and geophysical work over the past 27 months. Seventeen of twenty-one drill holes have penetrated 10 to 140 feet of potash mineralization in a salt sequence underlying 2 000 to 3 000 feet of arenaceous, conformable red beds, also of Mississippian age. Bromine and borate studies, lithological characteristics and geophysics, have facilitated improved understanding of the salt structure. The salt sequence has been affected by f1owage which has resulted in both major and minor folding. In the more disturbed areas, the potash interval was extensively subterraneally eroded at the upper anhydrite-salt contact.

Jan 1, 1978

By Julián Ortiz C., Clayton V. Deutsch

Indicator simulation allows specification of different continuity of high and low values through the use of grade thresholds. The sequential implementation of indicator simulation has been widely used, but the problem of order relation deviations remains a significant drawback. A new procedure for "Hierarchical Indicator Simulation" is introduced that avoids order relations and offers greater flexibility than the conventional sequential approach. The new implementation simulates all locations at the largest threshold and then considers decreasing thresholds in turn. All nodes with grades that are above the previous threshold are excluded from the domain of the current threshold and therefore, they are not used as conditioning data. The probability of being above or below the threshold is calculated using simple indicator kriging using all conditioning data in the domain, thus the covariance structure is preserved. The theoretical framework of this new approach is fully developed. Practical implementation details are discussed. Application to a copper deposit shows the advantages and drawbacks of the method. Finally, the possibility of incorporating multiple-point statistics is discussed.

Jan 1, 2002

By R. D. Smith

The Bureau of Mines (BOM) evaluated the technology, capital investment, and annual operating costs of emission control for further reductions of lead in ambient air at the East Helena, Montana, smelter, and the Glover, Herculaneum, and Buick smelter-refineries in Missouri. This study seeks to analyze the technology available to the domestic primary lead industry for attempting to further reduce lead emissions below 1985 levels. Through enclosure of concentrate unloading and handling areas and all lead-processing buildings, followed by venting these enclosures to the atmosphere through baghouses and the application of appropriate local controls, emissions can theoretically be reduced by a total of 2,424 pounds of lead per day from 1985 levels at the three Missouri operations. Using conventional technology, aggregated additional capital costs of $250,014,000 and annual operating costs of $18,507,800 are estimated for the four operations, resulting in a total cost of $0.063 per pound of refined lead. Continuous drossing techniques would assist in meeting OSHA standards in process areas. Continuous drossing would change capital and operating costs to $258,344,800 and $16,104,700, respectively, for a total cost of $0.062 per pound of refined lead. First quarter, 1986 open market price for refined lead was $0.184 per pound.

Jan 1, 1986

By Louis P. Gignac

The Lac Shortt gold deposit is located in Northwestern Quebec, at some 115 km west of the Opemiska Division and 380 km northeast of the Lac Dufault Division, as shown on Figure 1. Falconbridge's exploration crews drilled the first six holes in the gold-bearing ore zone in 1979. After further diamond drilling from surface in 1980, the decision was taken to carry out an underground exploration program. A three-compartment shaft was sunk to a depth of 340 metres in 1981 and 1982; it was followed by an extensive exploration program, which included 1073 metres of cross-cutting and footwall drifting, 645 metres of ore drifting and 11 200 metres of diamond drilling. The underground work was completed by mid-winter 1983. It was followed by a complete feasibility study of the Lac Shortt Project. After some $Can 14.2 millions in exploration expenditures, the Board of Directors of Corp. Falconbridge Copper approved in July 1983 additional expenditures of $Can 45 millions to bring the Lac Shortt Mine in production at the capacity of 261 000 tonnes per year. Gold price was $US 425 per ounce at the time.

Jan 1, 1985

By R. S. C. Rogers

The present study examines the use of two vs. one stage of hydrocyclones in a pilot scale ball mill circuit. The approach used for doing this is based on computer simulation with mathematical models that explicitly account for the grinding mill/classification system interaction. Parameters for the ball mill model are obtained using a short-lived radioactive tracer method in open circuit tests of the study mill. The hydrocyclone model, based on the size selectivity concept, is developed and validated in standalone testing of the study hydrocyclones. Simulation procedures are validated through actual tests of the closed circuit grinding configurations of interest. Results of the evaluation indicate that two stages of hydrocyclones in the study circuit would improve classification, increase productivity and lead to more closely sized circuit products when compared to the conventional one stage hydrocyclone circuit. A computer simulation approach for comparing these circuit configurations in larger scale grinding circuits is also suggested.

Jan 1, 1981

By L. Alan Weakly

The U.S. Department of Energy (DOE) has entered into a $l.5 million Cooperative Agreement with Alpine Equipment Corporation/Astro International Corporation ("Alpine") of State College, Pennsylvania, for the evaluation of water-jet-assisted (WJA) mechanical cutting of oil shale under actual mining conditions. A commercial-sized, heavy WJA mechanical miner is being assembled based upon the successful "factory testing" of a smaller prototype miner utilizing standard tungsten-carbide and Polycrystalline Diamond Composite (POC) bits in large oil shale boulders. Actual field testing of the machine will be conducted in an oil shale mine located in the Piceance Basin of Western Colorado. In-mine logistical support is being provided by several oil shale companies through the Colorado Mining Association (CMA) and the U.S. Bureau of Mines (USBM).

Jan 1, 1990

By S. R. Dindarloo

"Truck-shovel systems are the dominant material loading and haulage machinery in open pit mining operations. Optimal selection, sizing, and allocation of this capital intensive equipment is highly desirable for both achieving production targets and improving the mine’s economics. In this study, discrete event simulation technique was applied for modeling material transportation in Golegohar open pit iron ore mine in Iran. Direct observation of the material loading and haulage for duration of three months resulted in statistical modeling of the operation in the form of probability distribution functions. These probability models were used as the inputs of a stochastic simulation model constructed in GPSS/H simulation language. The model was validated through comparison with the actual operation and was used to test different what-if scenarios and sensitivity analysis of the current system. Some modifications in the number of trucks, shovels, and dispatching strategies were proposed. Simulation resulted in considerable improvements in the mine’s production and economics.INTRODUCTION There are three different mechanisms of discrete, continues, and hybrid material transportation in open mines, including but not limited to: i) in-pit crusher and conveyor belts (hybrid), ii) slurry piping (continues) and iii) truck-shovel system (discrete). Although, each mechanism has its advantages, the truck-shovel system is the dominant method of material loading and handling in open pit mines owing to its high production rate, excellent flexibility, relatively low operating and capital costs, and good maintainability. General objectives of optimal equipment selection include: i) meeting the long and short term requirements of production rates, ii) human & equipment safety, iii) environmental protection, and iv) economic operations (Figure 1).The two most important decision factors on a truck-shovel system selection and sizing are the equipment geometry and size. Geometry (equipment width, weight, turning radius, swing angle, etc.) is mostly controlled by mine’s designs and layouts, as well, as operational constraints. After selection of a favorable geometry based on the constraints; the next step is to select the equipment manufacturer. Once the geometry and manufacturers are selected; the next step is to decide on models (e.g. Bucket size) and required number of each unit"

Jan 1, 2015

By Stefan Mede

Robot Supported Moulding—this is the name of Herrenknecht Formwork’s entry to the world of automated segment production. What had been considered impossible for a long time, has been achieved by Herrenknecht experts together with the Swiss company Marti AG: unmanned segment production on the working line. The moulds open and close autonomously with the help of a hydraulic system. A robot cleans and greases the moulds at one work station and inserts the injection sockets at another. The next step will include further automation and digital networking of all processes from production to installation in the tunnel.

Jun 13, 2021

By William Gleason

"Speakers and attendees of the 2016 Cutting Edge Conference could not be faulted for keeping one eye on the presentations taking place at the Hyatt Regency at LAX in Los Angeles, CA on Nov. 7 and 8 and another on the results of the historic election in the United States that took place on Nov 8. While there was certainly interest in the presidential campaign, there was also a great deal of interest in Measure M on the California ballot. Measure M, which passed easily, is a half-cent sales tax increase that will fund the most ambitious transit expansion in Los Angeles County history.In the coming years, the ballot measure will transform a traffic-choked region by funding the construction of nearly a dozen new rail lines with an estimated $120 billion raised in four decades. Among the projects that could come to fruition are a twin-rail tunnels project through the Sepulveda Pass and new connections in the city.During the update on West Coast projects, Bill Hansmire summed things up with a slide asking “How much work is there on the West Coast,” and his answer was “Billions.”From Seattle, WA south to Los Angeles, there is already a lot of work for tunneling and underground construction experts, and Measure M ensures that there will be plenty of work for decades to come.Currently, The Los Angeles County Metropolitan Transportation Authority (Metro) has three rail projects underway that were funded by Measure R in 2008 — the Regional Connector, the Purple Line subway extension and the Crenshaw/LAX Line that are designed to alleviate the traffic pressure with an eye to more solutions.Measure M is the fourth sales tax increase to fund transportation in L.A. County, bringing the base sales tax rate to 9.25 percent. In some cities, which already levy their own sales tax, the rate would be higher, The Los Angeles Times reported.About 35 percent of the revenue will fund major new transit projects, such as the subway under the Sepulveda Pass, extension of the Gold Line to Claremont, extension of the Crenshaw Line to West Hollywood and acceleration of the Purple Line Subway construction along Wilshire Boulevard to finish in 2024, 10 years earlier than scheduled.About 17 percent would fund a dozen highway improvement projects, such as widening parts of I-5 in the Antelope Valley and southeastern county, adding bus lanes to the Sepulveda Pass section of the 405 freeway and adding truck-only lanes to a section of the 710 freeway."

Dec 1, 2016

By John S. Cummings

In this paper the phrase "exploration for blind metal deposits" refers to exploration activities geared to the discovery of metal deposits which cannot be located by visual surface inspection. The word "system" refers to all of the components (people, money, corporations, techniques, etc.) which collectively result in an exploration process. The details of the system or systems which I have employed in exploration will not be discussed because of client relationships. However, some of the more severe problems in exploration result from how the system's components interact and our attitudes as to what exploration data is telling us, if anything. It is these items which will be discussed. Exploration for blind metal deposits, which has been relatively intense over the last 2S years compared to rather minor outlays prior to World War II has often been an uncoordinated assortment of various specialists employing various techniques (see Dickerson -1). In a program geared to the location of blind deposits, the lack of outcropping deposits or occurrences should not be a deterrent to a well conceived and well planned program. The severe cyclical swings in exploration activity, although often coinciding with depressed metal prices, by and large result from the failure of exploration operators to present a coherent and realistic program to management. It is my opinion that the stream of complaints criticizing management for cyclical exploration support are mostly unwarranted, as many of the programs and goals are ill defined. Although depressed market conditions may serve as the catalyst for exploration cuts, the underlying cause is that when the "chips are down", the non-directional, non-specific nature of many programs is revealed. Thus management should not be castigated for eliminating such programs during bad times, but rather they should be castigated for supporting them during boom periods.

Jan 1, 1978

By A. Bascetin

Materials produced in quarries have been used for different intentions such as concrete and cement raw material, asphalt and embankment aggregates, railway ballast. Especially in cement manufacturing, the chemical composition and the uniformity of the raw materials play a strategic role in the economy and quality of the cement process. Therefore, it is necessary to achieve uniformity and desired chemical composition and maintain these at all production stages according to the type of cement produced. To achieve this goal the production planning and pit design play an essential role. This paper briefly outlines the production optimization of cement raw materials in a quarry in Istanbul western part of Turkey. For the purpose it was used the 3D ore body modeling and the geostatistical techniques. The variation of chemical components (%CaO, %Al2O3, %Fe2O3 etc.) and quality control parametres (LSF, SR, AR and etc.) obtained from the quarry were determined. Then the values of unknown chemical components and quality control parameters in the ore body were estimated using Kriging which is one of the geostatistical interpolation methods. The open pit design was also created by specifying wall slopes and taking into consideration of the grade distributions of the benches. The most important revolution in the paper is investigating the effects of the block dimensions in block modelling which is important for reserve estimation. The other important point in the study is using the different range values in variogram analysis for determination optimal reserve estimation. n this study, the effects of two parametres on reserve and waste amount estimation were determined according to CaO% distribution. The study was pointed out that the changing of the two parameters are very important for the optimal mine planning and environmental considerations.

Jan 1, 2010

By C. Garcia, C. L. Lin

Characterization and analysis of multiphase particles and/or particulate systems (such as the packed particle bed) are of great technological importance for mineral processing applications. In general the performance of these applications depends on the statistical characteristics of particle microstructures, such as composition distribution, surface exposure of mineral grains, pore network structure, etc. For continued technological progress in the field of multiphase particulate processes, the need for quantitative spatial analysis of multiphase particles in three dimensions has increased sign6cantly. Such quantitative information must be accurate enough that the measured values can be used as parameters for simulation models, process design procedures, and control strategies. Modern 3D image-acquisition techniques, such as X-ray microtomography (XMT), offer a unique imaging capability that can produce high-resolution (a few micrometers) three-dimensional images of the internal structure of multiphase particulate samples. These three-dimensional image data present new challenges for image analysis, image processing, and visualization. Furthermore, important issues should focus on how to use the 3D information and derive new insights into the improvement, design, and operation of mineral processing processes. In this paper, utilization of XMT for characterization and analysis of leaching process involving multiphase particulate system is discussed.

Jan 1, 2005

By Stephen H. Partney

Waste clay ponds are a necessary part of phosphate rock beneficiation. They are large, averaging 2.6 km2 (1 sq mile). They are unsightly in that they protrude 6 to 15 m (20 to 50 ft) above natural grade. Stabilization and reclamation is slow and they have had a history of catastrophic failure. Florida has never published a specific rule regarding the configuration or height of these ponds. But it has enforced several policies along these lines. The phosphate industry has been forced to make major monetary decisions that affect mine economics for decades. The Florida Bureau of Mine Reclamation believes that the direction of regulation has been solidified but changes are still anticipated. Phosphate rock has been mined in Florida since 1890 (Fig. 1). Three notable technological changes occurred in the industry that led to major shifts in mining technique and volume. By about 1915, hydraulic mining had been replaced by centralized washers. Hydraulic mines usually started at an outcrop in or adjacent to a stream of the pebble zone. Water was pumped out of the stream through high-pressure monitors and sand and clay were washed away from the pebble. Mobile grizzlies and screens were used in conjunction with animal and human labor to concentrate the pebble and haul it away. Populations were sparse and the clays washed into the stream were considered an acceptable price for the commerce. The clays were not voluminous because the pebble zone typically contained relatively small amounts of them. Machines largely replaced animals by 1910 and provided greater efficiency of production. Centralized washers replaced mobile trommels. They allowed greater ease of access to shipping routes by rail. Some clays were placed in mine cuts from 1915 to 1930. Some were dammed off to increase the capacity of a given site. Some of these also failed, leading to clay plumes that were visible all the way to the Gulf of Mexico. By concentrating the waste clays (slimes) in impoundments, the solids concentration had increased, making plumes persistent for long distances. There were complaints. But there was no litigation against the companies during that time. In 1930, flotation technology allowed the recovery of the phosphate from deeper zones. This was because the "concentrate" size phosphate rock was in the sand-size range and could not be screened out. Centralized beneficiation plants grew into a three-step process - washing and screening, feed preparation and flotation (Fig. 2). Reagent storage, safety and the flotation cell complex made the plants into large capital installations. Larger draglines were required to dig deeper into the matrix. These had dramatically larger production capacities, which were then figured into the overall material balance for a given plant. The number of operators shrank and the production per operator grew. Larger areas were being bermed off for waste clay storage. An economic incentive became apparent for storing as much waste clay as possible in each settling area. At the same time, the population was steadily growing and more eyes were watching the activities of the phosphate mines. Phosphate mining, focused on production and profit, was earning a bad name from its neighbors. When the subject of phosphate mining

Jan 1, 1998

By Shaojun Bai

Siderite ore with high phosphorus content was reduced isothermally at 1,050° C with pulverized coal and different dosages of sodium carbonate. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energydispersive analysis of X-rays (EDAX) were used to characterize the samples. The influence of sodium carbonate on the carbothermic reduction process was investigated. Sodium carbonate and its dosage played a considerable role in the carbothermic reduction. The iron particle size in the reduced ore was below 20 µm, and fayalite was abundant without sodium carbonate additive. With a mass ratio of Na2CO3-to-ore of 5% additive, the iron particle size in the reduced ore was generally above 50 µm, and the diffraction intensity associated with metallic iron in the XRD pattern increased. The effect of sodium carbonate on the phase transformation of fluorapatite during carbothermic reduction was also addressed via thermodynamic calculations and aqueous leaching experiments. The results showed that the fluorapatite was not reduced to P2 at 1,050° C, and a portion of the fluorapatite was converted to soluble phosphate. The reduction of siderite can be catalyzed by adding an appropriate amount of sodium carbonate. This catalytic activity was caused by an increase in the reducing reaction activity of FeO and the acceleration of the carbon gasification reactions. The decrease in phosphorous content in the iron concentrate was attributed to an improvement in the separation of the iron phase from the slag phase when sodium carbonate was added and with the formation of soluble phosphate.

By G. R. Hart

The expected 1990 Clean Air legislation is providing electric utilities with a series of challenges and decisions as the utilities prepare strategies to comply with the resulting regulations. This paper addresses the strategy development of a coal-based utility --the legislation, the process used, the fuel issues, the options available, and the decisions to be made.

Jan 1, 1991