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By A. Lashgari

Surface coal mining in the Appalachian region consumes a significant amount of energy in the form of diesel fuel and blasting agents. emission of oxides of nitrogen (Nox) from these sources represents an environmental challenge to the mining industry. this paper presents the results of research work related to determination of Nox emission of mining equipment and blasting agents, which is part of a broader industrial project conducted by the Appalachian research Initiative for environmental research (ArIeS). Data for this project are collected from an operating surface coal mine in West Virginia. the research work presented here may be used by mining professionals to aid in quantifying Nox emission and determine strategies for reducing its overall environmental impact.

Oct 1, 2013

By H. Zhao, R. Liao, W. Qin

Theoretically, controlling redox potential to a relatively low value and inhibiting jarosite formation on the chalcopyrite surface would be an effective strategy to accelerate the bioleaching of chalcopyrite. In this work, using limonite as seed crystals, the effects of the goethite precipitation process on the bioleaching of chalcopyrite were studied for the first time. The bioleaching results showed that the addition of limonite controlled the redox potential in an appropriate range and promoted chalcopyrite dissolution through the removal of ferric (Fe3+) ions. X-ray diffraction and scanning electron microscope analyses indicate that limonite significantly induced the goethite precipitation process and inhibited the production of jarosite. We conclude that promoting the goethite precipitation process with limonite is an effective strategy in accelerating the bioleaching process of chalcopyrite.

By James L. Patton

Automation of mining increases the productivity of labor, thereby reducing the unit cost of labor. Such cost constitutes the largest portion of the direct or variable costs of producing coal. Therefore, any increase in productivity directly reduces variable cost. The large investment in mechanical equipment carries with it the burden of increased fixed charges. As the proportion of fixed cost to the total cost increases, the effects on the cost of production changes are amplified. Therefore, equipment must be fully utilized at all times. Averaged fixed costs rise with any decline in production. Such a situation forces coal companies to seek every means of main¬taining full production. Figure I will reflect the story on the relationship of production to cost.

Jan 1, 1962

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 Bruce D. Hanson

A computer model capable of simulating the basic production system in a variety of underground mining methods has been developed at the Twin Cities Mining Research Center. This Bureau of Mines paper describes the simulation of the basic production system at the working face, which includes drilling, blasting, mucking, and roof bolting. The model is event-oriented; that is, the status of the system is updated at the occurrence of an event. All event or activity times, including failure and repair of equipment, are treated as stochastic variables. A location dimension, in addition to the time dimension, is used, allowing the simulation of multiple location systems. To aid the user in determining the efficiency of his system, the model provides several reports. An event or activity report gives the frequency of occurrence total active time, and cumulative delay statistics for each event. An equipment report delineates the availability and utilization of all equipment. A production report provides information on various performance measures such as tons produced and holes drilled. The cost report gives the cost of various elements in the system. Operating data from an actual mining situation were used in validating the model. In addition to the description of the model, examples of simulation experiments which were performed on a room-and-pillar mine system are given. Use of the model to determine methods for improving the efficiency of the system is discussed.

Jan 1, 1974

By Andrew J. Neale, Chelvan Veloo

P.T. Freeport Indonesia currently operate a 600,000 t/d mining and 125,000 t/d milling operation in the remote highlands of Irian Jaya, Indonesia. The isolated location and generally difficult working conditions make for challenges not encountered in most North American operations. In spite of this, the mill technical groups have been able to develop and maintain a highly effective level of plant wide automation. This has been achieved through the appropriate selection of available technologies and the implementation of innovative management practices. This paper provides an overview of the control systems currently installed and focuses on those practices which have resulted in the long term success of process control at Freeport.

Jan 1, 1997

By Joseph F. Shirley

A froth flotation plant to recover by-product molybdenite must be designed specifically for the selected separation process and the type of ore being treated. However, some general rules concerning by-product molybdenite plant design can be suggested that would be valid for most processes. The term by-product molybdenite in this paper is limited to the recovery of molybdenite from copper porphyry ores, which essentially amounts to selectively separating molybdenite from copper and iron sulfide concentrates. In addition, most of the discussions would apply only to the almost universally used approach of floating the molybdenite and depressing the copper and iron sulfide minerals.

Jan 1, 1979

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 W. D. Macleod

This paper describes a mineral dressing process for the upgrading of tin ores. The process described is called 'agglomeration' and. is similar in many respects to flotation. Many variables have been examined experimentally both on batch and continuous operations and are reported upon herein... Using a Mt. Pleasant tin ore, assaying 0.5% Sn, an upgrading to 8% Sn, with a recovery of 95% could be obtained by this process.

Jan 1, 1966

By W. E. Bardelmeier

The high speed conveyor type self unloading bulk carrier concept has been around for about 70 years. Although the design was developed, refined and steadily improved in the Great Lakes, to date limited numbers of such vessels have emerged in the bulk ocean trades, and these have tended to concentrate within specific mineral trades. For example, North American gypsum companies have embraced conveyor self unloaders to the point where such vessels almost exclusively carry the gypsum requirements of this part of the world. One major aluminum company has developed an impressive fleet capability in self unloaders. Application of other ships tends to be fragmented through several mineral trades. A few years ago a new phenomonen began to appear on the Great Lakes. Whereas it had historically been accepted in that region that self unloaders were effective vessels for the minor bulk trades including limestone, coal, salt, gravel and sand; they had seldom been employed heavily in the big volume iron ore trades. Suddenly, however, the new generation of 60,000 ton Lakers which emerged were all designed as high speed self unloaders. The new vessels intended to trade especially in ore, or alternatively especially in coal, have somewhat different internal features, but the important point is that all are self unloaders.

Jan 1, 1979

By William F. Riggs

Inspiration Consolidated Copper Company, located in a semi-arid climate in Arizona, continually struggles with a water problem. This applies to quality as well as quantity. When the EPA considered installing a new centralized sewage plant to handle the combined waste from the municipalities of Globe and Miami, Arizona, they automatically assumed that He could use the sewage effluent for process water in flotation. The treatment plant was to be a tertiary system producing 1600 gpm of sewage effluent. Inspiration decided that this could possibly be a source of additional process water. It was decided to test sewage effluent from Miami Treatment Plant at the rate of 400 gpm since it was only a primary treatment plant. The 400 gpm was combined with the 5000 gpm of process water going to the Concentrator. After one week the results were disastrous. The recovery and final grade had each dropped approximately 5%. With the results from this brief run, it was concluded that sewage effluent from a primary treatment plant could not be used. Research was then brought into the problem to begin an evaluation of sewage effluent in flotation.

Jan 1, 1977

By C. G. Hunkin

In situ, or in-place leaching is concerned with the extraction of metals from natural mineral disseminations without removal from their geologic location which, in many cases, amounts to the reversal of the deposition process accompanied by a presumed increase in velocity of the processes, if the project is to be profitable. Solution mining processes involve removal of minerals such as sulfur, common salt, and potash, generally leaving cavernous voids, in contrast to in situ leaching which term is applied to the selective dissolution of a mineral from its gangue without sensible disturbance of the formation. Where such a process can be operated, the advantages are manifold and have been so recognized by miners from the earliest days of mining. Recent technological developments have encouraged a reassessment of the status of in situ leaching, and it now appears possible to extend the application of the method from a few isolated special situations to many uranium and copper deposits. Anaconda's interest in the techniques stems from long experience with vat and heap leaching, 'dump leaching, and natural leach activities associated with several established mines. Increasing activity through-out the industry has been noted, particularly in leaching low grade pillars and the peripheral zones of operating mines, often by the introduction of leach solutions via boreholes drilled from surface. Reactivation of dormant mines] using similar techniques has been successful. Over the long term, environmental improvement activity will lead to excess sulfuric acid production, even to a disposal problem. The cost of leach solutions and reagents must be reexamined in this light. The mineral industry now classifies as uneconomic deposits of readily soluole minerals whose potential value, on a per acre basis, may De several times that of many currently profitable oil field reser-

Jan 1, 1971

By J. A. Barrera-Godinez

Traditional batch flotation tests produce a limited number of data points from which to evaluate the kinetics of the process. In this research, continuous weighing of froth, from a modified circular flotation cell, using a computer/data acquisition system., has been coupled with chemical analyses from intermittent froth sampling. This combination has permitted the experimental data to be smoothed such that the flotation kinetic parameters could be determined with enhanced confidence. To demonstrate the procedure, a galena ore was floated to permit flotation kinetics to be investigated as a function of cell parameters. It was shown that the kinetic data of this lead flotation most closely correlated with the Huber-Panu three parameter model. In addition the results illustrated the effect of froth thickness, froth scraper rate and air flow rate on the cell performance, in terms of mass flow, grade and recovery.

Jan 1, 1990

By James R. Jones

It has been 2-1/2 years since the Congress passed the Surface Mining Control and Reclamation Act of 1977 (PL95-87) the Office of Surface Mining every deadline specified in the Act. Hopefully the Congress will begin to realize that specifying unrealistic deadlines does not accomplish the end desire of legislation any sooner -- it only adds to the confusion, and actually hinders orderly, efficient progress. OSM has been sued by all categories of involved parties -- environmental activitist organizations, the states, and the coal operators. This situation has resulted for two reasons: (1) insufficient time was allotted by the Congress to properly develop the regulations and program, and (2) OSM?s philosophy that it must dictate every detail of reclamation operations from Washington, even though many of its people are inexperienced with coal mining. These law- suits are now demonstrating their value. OSM is showing signs of "pulling-in-its horns" and, hopefully, will approach the revised regulations in a more realistic fasion.

Jan 1, 1980

By B. R. Benner

Progressive improvements in crusher design, screening efficiency, and operating experience along with the downsizing of many taconite operations has resulted in the abilitv of some crushing plants to produce a substantially finer product. This finer product opens the possibility of replacing the rods in the rod mill with balls as is the current practice at Sydvaranger, Norway. If this replacement could be accomplished substantial savings associated with metal wear and the elimination of rod charging may be realized. The purpose of this study was to compare the performance of a mill charged with rods with the performance of the same mill charged with balls at the pilot scale. The first objective was to establish whether we could achieve the same throughput rate at the same mesh-of-grind in a mill in which the rod media has been replaced by balls. The second point was to determine whether the ball media would create a significant tramp oversize problem.

Jan 1, 1990

By S. J. Ripke

To pelletize fine moist magnetite concentrate, a 40% water slurry must be dewatered to about 10% by filtration, before it can be agglomerated into pellets. Slurry pH, typically ranging from 8 to 11, gives the magnetite particle surface a strong negative charge and thus causes two adverse effects. First, this negative charge attracts calcium and magnesium cations, which strongly retard the effectiveness of the bentonite clay binder added during agglomeration. Second, a repulsive force created by the negative charge functions as a dispersant that reduces filtering production rates. Tests were conducted to remove these cations during filtration, by rinsing the moisture remaining in the filter cake with a small amount of water adjusted to pH 6 with HCl. Laboratory work was also conducted at Michigan Technological University (MTU) and at Cliff’s Mining Services Company (CMSC) to corroborate the plant tests. In some cases HCl caused filter bag blinding, therefore CO2was investigated to reduce pH. The CMSC lab tests showed that using carbon dioxide to reduce slurry pH from 7.6 to 7.0 improved filtering production rates by 11%. Plant-scale filtering rates were improved by 23.7% when carbon dioxide addition reduced the slurry pH from 8.6 to 6.7.

Jan 1, 2004

By Manoj Khandelwal, Minghui Liu, Jian Zhou, Kun Du

The waste rock and tailings backfill into the mined-out areas are the most effective method for solving the environmental pollution and surface disasters for nonferrous metals mines. In practice, the success and availability of backfill operations are dependent on the slurry fluidity and the strength properties of cement backfill. The transport of the slurry through the pipeline to the designated backfilling area relies on its eximious flow properties, while the appropriate strength of the filling body ensures the safe operation of the stope. In this paper, the effects of cement and aggregate types on the slurry fluidity and strength characteristics of cemented backfill are studied in detail, which are often ignored in other pieces of literature. Diffusivity is used as an indicator to evaluate the slurry fluidity. Various slurries whose concentrations ranging from 70%, 73%, 75%, 78%, and 80% are made with different aggregate ratios and cement-sand ratios are tested. It has been shown that slurry fluidity is inversely related to its concentration, but 78% is the “stopping point” for the deterioration of fluidity. The addition of rod-milled sand improves or worsens the cemented backfill (CB) strength depending on the amount of rob-milled sand. The uniaxial compression experiment results on 216 CB specimens produced by different combinations of influencing variables showed that CB specimens made from cement with superior mechanical properties have a higher uniaxial compressive strength (σucs). It has been also found that the effect of aggregate ratio on the CB strength is not singular, but works in conjunction with the curing time and the cement-sand ratio. The longer the curing time and the higher the cement content, the higher the CB’s σucs. To avoid the time-consuming and costly problem of obtaining the strength of the CB from indoor experiments, an SVR model capable of predicting the uniaxial compression strength of CB specimens is proposed, which is optimized by genetic algorithm (GA) and particle swarm optimization (PSO) algorithm. The results of the three performance indexes (MAPE, MSE, and R2) show the superior performance of the GA-SVR and PSO-SVR models and the agreement of the predicted results with the experimental results, which indicate that these two models can accurately predict the σucs of CB.

Feb 3, 2022

By Mark E. Gershon

The development of long term plans and schedules for strip mines now faces many companies, especially those developing large properties in the West. The rule of mining the lowest strip ratios first, while delaying equipment acquisitions and recouping investment the fastest, creates the situation where stripping ratios are too high in the latter years of mining operations. A program concept taking life of mine return on investment into account is developed in this paper to optimize mine scheduling and equipment acquisition. In addition, quality considerations (heat content, ash, sulfur, washability) can be considered by including the appropriate blending constraints to meet contract requirements.

Jan 1, 1983

By Matthew S. Sanchez, Richard J. Lee, Matthew D. Zock, Drew R. Van Orden, Yumi Kamiya, Edward B. Ilgren

In many developing countries, asbestos is still used for friction products, insulation, and asbestoscement products. However, there is very limited modern data evaluating the airborne concentrations of asbestos fibers in operating asbestos plants. We have conducted an Industrial Hygiene survey, using state of the art PCM and TEM analysis, of a Bolivian asbestos cement plant that uses crocidolite during the production of roofing shingles and water tanks. The study is the first to use modern analytical measurements in an uncontrolled asbestos environment. Thus, this study offers insight into the historical airborne exposures at asbestos plants operating before modern dust control measures were introduced or airborne fiber levels regulated. The results suggest that fiber concentrations are far in excess of those for which current models would predict the onset of asbestos disease and mesothelioma. Significantly, the plant and community do not have an elevated incidence of asbestos disease or mesothelioma. Airborne fiber levels during comminution and fiber sizing ranged from 100 to as much as 1,000 f/cc. Fiber levels in the mixing, forming and finishing areas ranged from 0.5 to 9 f/cc. Based on the number of overloaded samples and estimates of their concentration, historical estimates of exposure may be underestimated by an order of magnitude. Also, an excellent correlation (1:1) between the PCM and TEM fiber concentrations (for fibers _0.25 um diameter) were obtained, raising questions about the conventional wisdom that the PCM systematically undercounts fibers. The results of this study further indicate that current models may overestimate the risk of asbestos disease and mesothelioma.

Jan 1, 2012

By Harry Perry

Although the markets for coal in the United States have changed rapidly over the last three decades, the uses of coal, namely, to produce heat and power or coke have been left almost unchanged. The coke is used either as a chemical reducing agent alone or as a reducing agent and source of heat. Most of the heat and power markets for coal require no coal processing, although for more than 50 years, many proposals to skim the more valuable substances in coal before burning have been advanced. Thus, the only large tonnage market requiring processing of coal is high-temperature carbonization to make coke. At present, coal requires processing for some small markets, but for future potential large markets, such as gasification, conversion to liquid and gaseous fuels, and conversion to chemicals, coals will require more processing than is now being done.

Jan 1, 1962