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By John F. Abel

Convergence measurement across the 17.4 m (57ft) high shaft station/loading pocket at Mt. Taylor provided continuing verification of stability and safety. Three levels of instrumentation, consisting of three lines each, were installed and monitored. The instrumentation showed that the flexible lining restrained the adjacent rock. The flexible lining consisted of pea gravel with neat cement between rock and liner plate, wooden crush blocks between liner plate and steel ring beams. The loading pocket is elliptical, 11.6 by 9.6 m (38 by 31 1/2 ft) I.D. The crush blocks were designed to allow 15 cm (6 in.) of convergence. Maximum predicted convergence was 7.0 cm (2 3/4 in.) and 5.7 cm (2 1/4 in.) was measured. Convergence measurements also demonstrated decreasing deformation with respect to elapsed time and distance from the measurement station to the temporary bottom of the shaft excavation.

Jan 1, 1984

By Naj Aziz

Both bolt profile shape and spacing (rib spacing) have been found to influence the bonding capacity of the grouted rock bolt. The bolt surface profile configuration has greater importance to rock bolting in strata reinforcement in mining than the steel rebar used in civil engineering construction. This is because a rock bolt in mining usually is subjected to greater dynamic loading than the steel rebar in civil engineering construction. The increased bonding capacity of a bolt is important when supported ground is either heavily fractured, faulted or the supported ground is of soft formation, typically that of coal measure rocks. Past laboratory studies have identified the bolt profile spacing as of significant relevance to bolt resin rock bonding increase, however, no attempt has been made to determine the optimum spacing between the bolt profiles spacing. Accordingly, a series of laboratory tests were carried out on 22 mm core diameter bolts, commonly used in Australian mines, installed in cylindrical steel sleeve. The study was carried out using both push and pull testing methods. The push test was carried out in 150 mm long sleeves while the pull testing was conducted in 115 mm long sleeves. Profile spacing tested include, 12.5, 25.0, 37.5, and 50 mm lengths. Additional studies undertaken include modelling the profile of the load-displacement data of pull testing. Bolts with a profile spacing of 37.5 mm were found to provide optimum load bearing capacity as compared to other tested profile spacings.

Jan 1, 2009

By R. Bernard

This paper will discuss innovative strategies that combine the capabilities of an Enterprise Asset Management (EAM) solution, sometimes referred to as a Computerized Maintenance Management System (CMMS) and E-Commerce solutions. Strategies discussed include solutions that minimizes the costs of operations through maximized equipment productivity and availability. Thusly, achieving the ultimate goal of keeping the cost per production unit as low as possible.

Jan 1, 2001

By Tim Haldane

Cyanide consumption at the Gold Fields Operating Company Mesquite Mine has shown a steady decline since the heap leach operation started up in 1986. A series of solution strength changes and equipment design improvements have resulted in a reduction of sodium cyanide consumption from peak levels above 1.0 pounds NaCN per ton of ore in 1986 to current levels at 0.15 - 0.20 pounds NaCN per ton of ore. Aside from the obvious cost benefits associated with this reagent consumption reduction, the property has also enjoyed environmental benefits which go hand-in-hand with these cost savings.

Jan 1, 1990

By A. L. Coello Velázquez

The subject of this paper is particle population balance models (PBM) that describe mineral impact crushing behavior; it is mainly concerned with the selection and fragmentation distribution function due to their importance in this context. The data obtained by Datta (1999) by applying impact pendulum testing to single limestone particles, used by Austin (2002, 2004a and 2004b) to obtain the principal parity of fragmentation functions, were processed in order to compare them with the results of other authors, such as Nikolov (2002 and 2004) and Vogel and Peukert (2003 and 2005) so as to increase knowledge of impact crushing. From this data it has been possible to obtain the performance models of the principal parameters of fragmentation function, thereby reducing the number of experiments necessary to model the impact crushing process. The authors also propose a simplification of the selection function model posited by Austin (2002).

Jan 1, 2011

By W. M. Cross

The hydrophobic character of sapphire surfaces in SDS solutions was examined with respect to the aggregative nature of the adsorbed surfactant phase. It was found that, at equilibrium, sapphire surfaces having adsorbed SDS bi-layers exhibited no contact angle. Conversely, when the adsorbed SDS was found to be mi-cellar in nature, sapphire surfaces developed significant hydrophobic character. The surface states as detected by Fr -IRIIRS conformational analysis were found to be reversible with temperature. The variation in adsorption density with temperature was studied by in situ Fr-IRIIRS. The isosteric heat of adsorption was calculated to be -1.6 kcal/mole. Although the adsorbed SDS was found to undergo a reversible phase change between 25 and 32°C, similar to SDS in solution, the extent of adsorption was not reversible with temperature.

Jan 1, 1993

By James A. Curry

Table I identifies the maximum cost of the individual provisions with spoil disposal in Appalachia leading at $3.98 per ton, This was followed by deep mine subsidence control and monitoring at $1.66 per ton. At the request of the U.S. Department of Energy, the Bowser-Morner Testing Laboratories of Dayton, Ohio, evaluated Consol's cost estimates for 14 of the 21 regulatory provisions the company studied. It is interesting to note that Bowser-Morner concluded that Consol's estimates of costs were very conservative and that the actual costs will be substantially higher than what the company reported. In 1978 a joint committee of the National Coal Association and the American Mining Congress made estimates of cost impacts under 11 OSM permanent rules (see Table II). Six rules applied to mid-western strip mining were projected to cost $6.52 to $17.17 per ton. Five rules applied to mid-western strip mines showed costs ranging from $.91 to $6.11 per ton. Three rules applied to deep mines (regardless of region) were seen raising costs from $ .57 to $2.67 per ton. The joint committee reported trouble developing overall figures because member firms used widely different assumptions in calculating their costs. That same statement could no doubt be made when comparing most cost data available today.

Jan 1, 1980

By G. P. Larson

We define a specialized mineral market as follows: Specialized Markets are markets where a low volume of a given mineral is used to convey a large benefit to a specific product. Sales of these value added minerals to small markets generally require a different marketing approach compared to bulk or commodity markets for traditional minerals. Specialized and commodity markets are differentiated by several characteristics as listed in Table 1.

Jan 1, 1990

By Richard C. Corson

The objective of blending materials in a bedding pile is to reduce the variation in successive samples taken from the materials to be blended. In designing a bedding and reclaiming operation, several mechanisms are available to effect the reduction of variability, or increase in homogeneity, of the materials. These mechanisms can act before stacking, in the stacking process, in reclaiming and after reclaiming. In evaluating alternative methods of stacking and reclaiming, the potential user must judge each method on the basis of certain criteria; the capital cost of the equipment, the allowable absolute variability of the reclaimed product and the effectiveness of blending. Several stacking and reclaiming methods have been tested using a computer simulation. Based on the results of this program, factors were developed to describe the effectiveness of blending for chevron stacking of discrete materials and preblended materials, bucket wheel reclaiming and drum reclaiming. From these factors, the total effectiveness of a combined stacking and reclaiming system can be determined.

Jan 1, 1985

By Paul J. Henkels

Synthetic gypsum is the calcium sulfate co-product of a number of industrial processes. Synthetic gypsum utilization as an alternative to the naturally occurring mineral continues to grow in the gypsum industry. In particular, flue gas desulfurization (FGD) gypsum produced by the electrical utility industry has had a significant impact and a far-reaching effect on the gypsum wallboard manufacturing industry. This paper will discuss the various synthetic gypsum sources verses natural gypsum and highlight issues of use in gypsum wallboard and related products.

Jan 1, 1999

By Fred T. Towne

There are a number of air classifiers manufactured throughout the United States and the rest of the world. The classifiers manufactured by Alpine, A. G. of Augsburg, Germany, are unique in their abilities. It is this uniqueness that I wish to delve into and in this respect we will limit this discussion primarily to the classifiers as manufactured by Alpine. It has been reported in the past that these classifiers were introduced into the. United States in the late 50's. Until the introduction of the Alpine Classifiers, air classification seldom produced a satisfactory fractionation of a product below 45 microns (325 mesh) or above approximately 22 mesh. It has been a common practice to classify fine materials which used water as a carrier medium The use of centrifuges are today producing thousands of tons of finely partitive powders in the very small particle size range. The use of centrifuges in connection with wet grinding mills has increased the rates of production of these mills considerably.

Jan 1, 1965

By Y. Guan

The dissolution behavior of silver and copper from silver/copper alloys in ammoniacal solutions has been investigated using a rotating disc. Oxygen was used as an oxidant. The effect of composition of alloys, concentration of lixiviants, stirring speed and temperature on the overall dissolution kinetics has been studied. Silver / copper alloys of three compositions were used in this study. The atomic percents of silver in these alloys were 76.9, 46.9 and 24.1. The results on the rate of dissolution obtained for these alloys have been compared with that of pure silver and copper under the same testing conditions. A particular emphasis has been given to the galvanic effect on the overall dissolution rates.

Jan 1, 1993

By J. K. Pandey, ebashish Mishra, D. P. Mishra, N. K. Mohalik, S. K. Ray

The increasing demand for coal and depletion of shallow depth reserves are pushing towards deeper mining. In deeper coal mines with multiseam workings, the problem of ventilation surges many folds primarily related to air quantity requirement, heat, humidity and spontaneous heating/fire in goaved (gobbed) out areas. The paper describes the design of a new approach to improve the ventilation system of a real-life deep underground coal mine with multiseam workings. For this, the ventilation problem of one deep underground coal mine 6&7 pits Bhutgoria Amalgamated Colliery of Tata Steel Ltd. with multiseam workings has been studied in detail to determine an appropriate solution. A ventilation survey of the mine and computer simulation of the ventilation network has been carried out to reach a practical solution. Ventilation survey results have been analysed to develop a representative ventilation network of the mine for both qualitative and quantitative analysis. Further, computer simulation of the ventilation network of the mine has been performed to virtually verify the application of a highcapacity booster fan in the present ventilation circuit without disturbing the vulnerable areas. Field validation is also carried out after the implementation of the solution in the mine to determine its efficacy. Thus, the findings of this paper can be directly applied for the installation of booster fans to achieve the required air quantity in deep underground coal mines with multiseam workings having spontaneous combustion liabilities of upper seam goaved out areas.

Jun 2, 2022

By J. D. Bittner

The ST separator utilizes electrical charge differences between materials produced by surface contact or triboelectric charging. When two materials are in contact, material with a higher affinity for electrons gains electrons and thus charges negative, while material with lower electron affinity charges positive. This contact exchange of charge is universally observed for all materials, at times causing electrostatic nuisances that are a problem in some industries. Electron affinity is dependent on the chemical composition of the particle surface and will result in substantial differential charging of materials in a mixture of discrete particles of different composition. In the ST separator (Figures 1 and 2), material is fed into the thin gap 0.9 ? 1.5 cm (0.35 -0.6 in.) between two parallel planar electrodes. The particles are triboelectrically charged by inter-particle contact. For example, in the case of coal combustion fly ash, a mixture of carbon particles and mineral particles, the positively charged carbon and the negatively charged mineral are attracted to opposite electrodes. The particles are then swept up by a continuous moving open-mesh belt and conveyed in opposite directions. The belt moves the particles adjacent to each electrode toward opposite ends of the separator. The electric field need only move the particles a tiny fraction of a centimeter to move a particle from a left-moving to a right-moving stream. The counter current flow of the separating particles and continual triboelectric charging by carbon-mineral collisions provides for a multi-stage separation and results in excellent purity and recovery in a single-pass unit. The high belt speed also enables very high throughputs, up to 40 tonnes per hour on a single separator. By controlling various process parameters, such as belt speed, feed point, electrode gap and feed rate, the ST process produces low carbon fly ash at carbon contents of 2 % ± 0.5% from feed fly ashes ranging in carbon from 4% to over 30%.

Feb 27, 2013

By Kanaya Koichiro

Doyashiki Concentrator in Hanaoka mine of Dowa Mining Co., Ltd. started the operation in 1943, treating the ore mainly from Doyashiki ore deposits. After the cessation of mining of Doyashiki ore body in 1973, Doyashiki concentrator began to treat the ore from Fukazawa mine instead in the same year, and furthermore the ore from Ezuri mine In 1979. Currently Doyashiki concentrator treats 30,000 tons of ore per month from both mines. The ore treated is complex sulfide ore, called "Kuroko" (black ore), and the principal minerals contained in the ore are chalcopyrite, galena, sphalerite, pyrite, and barite, accompanied by bornite, tetrahedrite, tennantite, covellite, stromeyerite, argentite, polybasite, pearcite, and electrum. The Principal gangue minerals are quartz, gypsum and clay. The grade of the feed to the concentrator averages 0.9 p/t Au, 110 g/t Ag, 1.1 %Cu, 2.8 %Pb, 9.2 %Zn, 5.0 % Pyrite-S and 13% BaS04. The feed is, after washing and two-stage crushing, ground to 88% minus 200 mesh in a rod mill and ball mills with cyclone classifiers, and five concentrates are recovered by flotation. Primarily copper-lead bulk concentrate is recovered by sulfurous acid-lime flotation method, and then from the bulk concentrate copper concentrate is floated by hot pulp flotation method, sinks being lead concentrate. Zinc concentrate is recovered from the tailing of copper-lead bulk flotation, pyrite concentrate from zinc flotation tailing and barite concentrate from pyrite flotation tailing. The final tailing is sent to the dam.

Jan 1, 1982

By D. Spindler

Pursuant to the Federal Surface Mining Act of 1977 and the Illinois Surface Mining Act of 1980, Illinois has adopted revegetation success standard regulations that include the Agricultural Land Productivity Formula. The Formula establishes yield goals and standards to measure the success of meeting yield goals for reclaimed prime farmlands. The formula compares the quality of the pre-mining soils in the permit area and the county, to the crop production achieved on the reclaimed permit area and the county crop yield in a given crop year. The regulations also specify acceptable crops, erosion control requirements and time frames for demonstrating success.

Jan 1, 1986

By Martial P. Corriveau

The preparation of coal is essentially the same for export as it is for the domestic market. The big difference, I would say, is that, while coal for certain domestic uses (utilities, for instance) need not always be of the highest quality, as long as it is uniform, the buyer of coal for export invariably demands a well-prepared, top-quality product. And he is willing to pay for it, as long as he knows what he is buying. This is where quality control enters the picture. The day is long past since the export market was the dumping ground for coals which could not be sold on the domestic market. Today, the export buyer wants American coals not so much for a price but for the necessity of blending the American coals with foreign coals to achieve the desired chemical and/or physical characteristics, To blend intelligently, he must know in detail what are the qualities of the coals to be blended. Sampling and chemical analysis facilities at the piers provide the information on the coals exported, These facilities are maintained for the export buyer by independent laboratories; however, in one instance, the buyer operates his own laboratory. With very few exceptions, and Clinchfield?s Moss No. 3 mid-volatile coal is one, cargoes shipped overseas are loaded as blends of two or more coals. Up to now, foreign requirements have not been too clearly defined; therefore, shippers must be prepared to blend mixtures of the desired combination. Successful blending requires an accurate knowledge of the coals shipped. And this makes it necessary for the coal producer to maintain his own control laboratory.

Jan 1, 1959

By R. Brough, T. K. Moller

There are differences in design aspects between steel and rubber linings in grinding mills. This paper describes the basic design rules for rubber liners for different grinding applications. When converting a mill from steel to rubber liners, the design must be changed from such familiar steel liner shapes as wedge bars and plates, wave liners, and ship-lap, to take advantage of the characteristics of rubber. Very little of the knowledge of the wear properties of steel can be used for the design of rubber mill liners.

Jan 1, 1990

Laboratory tests were conducted in a full-scale continuous miner test gallery to evaluate resulting dust levels for changes in face airflow, spray water quantity and pressure, and mining height. The minimum and maximum values tested for each parameter were as follows: airflows between 1.42 and 6.14 m3/sec, water flows between 56.8 and 132.5 lpm, nozzles pressures between 413 and 1379 kPa, and mining heights between 1.52 and 2.74 m. Each of these parameters were evaluated for four common spray system designs. Respirable dust samples were collected in the operator's cab on the miner and in the immediate return. Second-order polynomial models were used to represent expected dust levels and multiple stepwise regression was used to identify significant control parameters for inclusion in the models. Separate models were developed for dust levels at the operator and return locations and for each individual spray system. Interaction between control parameters and curvature effects were found in most models. The analysis indicated that at the operator location, airflow and mining height had the most significant impact on respirable dust levels. In the return, airflow and water pressure were typically the most significant parameters. The models developed for each spray system design can be used by mine operators to guide application of control parameters for a variety of operating conditions and mining heights.

Jan 1, 1994

By Steve Kral

Reducing the cost per ton and increasing productivity are key factors in a mine’s profitability. Mining companies can do little about commodity prices. So to keep a mine operating at a profit, management must reduce costs and improve worker and equipment productivity in every facet of a mining operation. From mining to crushing to processing, mine management is constantly seeking new methods and technologies to improve the way it mines minerals. And it is willing to borrow techniques used by other operators.

Jan 1, 2002