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By S. -H. Kim

This work investigated the effect of the concentration of CO2 and lead contamination on the forest ecosystem. Changes of the plant growth, lead concentration in soil, plant, and soil microbial community caused by CO2 concentration (380 ppm and 760 ppm) and lead contamination (500 mg/kg) were measured. Plant growth was inhibited by 50% due to lead contamination. Particularly, shoot growth was inhibited more than the root. However, the root elongation was not affected by the CO2 concentration increase. The diversity of microbial population with AWCD (Average Well Color Development) and PCA (Principle Component Analysis) showed that the lead contamination has an effect com-pared to CO2 concentration. The Shannon index calculated from DGGE profiles was high in soil with Pinus densiflora, while the effect of CO2 concentration was not significant (P<0.5). The similarity of microbial community from each treatment showed that lead has an effect on plant growth and microbial community rather than the CO2 concentration.

Jan 1, 2006

By LeRoy D. Loy

The disposal of excess overburden from surface mining can be accomplished by use of a reclamation technique entitled head-of-hollow or valley fill. This report attempts to assess current valley fill regulations and practices, identifies inherent benefits and deficiencies, and develops concepts to enhance fill technology.

Jan 1, 1978

By Gary Almeraris, Vincent Jr Tirolo

Traditionally, “Means and Methods” were the sole responsibility of Contractors. However, because of a number of litigious projects in the 1970s, Owners and their Engineers began including Suggested Methods of Construction (SMC) in Contract Drawings. By the late 1990s these SMCs were becoming baseline “Means and Methods” with Contractor recommended changes often considered as Value Engineering proposals. By 2004, the word “Suggested” was sometimes changed to “Prescriptive.” Owners are also purchasing TBMs and other mining equipment for Contractors prior to bid. Is limiting the contracting community’s innovation in developing their own “Means and Methods” and selecting their own equipment in the best interests of the Owner? Does it reduce the Owner’s, Engineer’s or the Contractor’s risk? Are claims reduced and finally what is the impact on the bid? A questionnaire was sent to more than fifty senior engineering field and management personnel representing more than 30 heavy construction companies to ask their opinion on these questions.

Jan 1, 2005

This information circular describes research the Bureau of fines has conducted to improve technology for recovering precious metals from low-grade resources. Many of the reported findings are recent, and some of the work described is ongoing. Topics discussed include cyanidation of carbonaceous gold ores to enhance gold recovery, a new method for precipitating mercury during cyanide leaching of gold ores, a staged heap leaching process to generate suitable solutions for direct electrowinning of gold, the use of anion-exchange resins to recover gold from cyanide solutions, and precious metals recovery from electronic scrap.

Jan 1, 1986

By W. H. Strickland

Ultrasonic ranging sensors are inexpensive, have no moving parts, have no lenses to clean, are normally small and unobtrusive, and can measure distances through moderate amounts of dust, smoke, and humidity, so they are well suited to underground mines. In the work reported here, conducted by the U.S. Bureau of Mines, researchers tested ultrasonic ranging sensors for their ability to define rib line features for computer-aided navigation of underground mine mobile equipment. The investigation began with laboratory tests of field of view, angle of incidence, intersensor variation, and ranging accuracy of the individual rangers in a ring array produced by Denning Robotics of Wilmington, MA, The results showed that the sensors have good accuracy and low variability. Additional experiments at AMAX&apos;S Henderson Mine showed the sensors could accurately and reliably measure the distance to mine features, including convex and concave corners and rib intersections. The results showed that when used properly, the ranger data are accurate enough for reliable mine vehicle navigation. When used incorrectly, ultrasonic rangers do not provide the anticipated data. Therefore, this report explains the principles of ultrasonic range measurement, describes the ranger&apos;s strengths and weaknesses, and explains proper ranger use and data analysis.

Jan 1, 2010

By H Ishikawa, H Zhou, M Spagnolo, R Halomoan, S Palaniandy

The Karara Mine concentrator commenced operation in November 2012 to produce high-grade magnetite concentrate. The circuit consists of three stages of comminution plus magnetic separation at each stage for early gangue rejection. High-Pressure Grinding Rolls (HPGRs) are used for fine crushing, followed by ball mills and TowerMills in secondary and fine grinding duties respectively. In recent times, the plant throughput rate has had to exceed design by 18% to maintain the targeted concentrate productivity. Meanwhile, the ore hardness has increased by 25% to 15 kWh/t, leading to changes in the circuit operation and design. These changes led to coarser and harder feed to the TowerMill circuit that affects the subsequent separation processes. Nippon Eirich (the TowerMill manufacturer) has partnered with Karara Mining Limited (Karara) to optimise the TowerMill circuit operation to achieve a circuit product with an 80% passing (P80) of 35 &#181;m. Several activities, including a TowerMill circuit audit and performance evaluation, multi-component analysis, modelling and simulation, were carried out as part of the optimisation exercise. The circuit audit results revealed that the TowerMill circuit feed size F80 had increased and ranged from 67–75 &#181;m. The circuit product P80 ranged between 42–55 &#181;m. The average circuit specific energy was 3.4 kWh/t. Moreover, the differences in density between magnetite and gangue minerals had affected the hydrocyclone performance where the efficiency curve exhibits coarse end deflection indicating that low-density coarse material was bypassing to the overflow stream. A multi-component analysis was carried out to further investigate the coarse end deflection of the hydrocyclone efficiency curve. The analysis showed that the magnetite and gangue minerals had different cut sizes of 32 and 64 &#181;m respectively. Furthermore, 33% of the magnetite (below 35 &#181;m) was being recycled back to the mill due to the density effect. Based on these findings, several recommendations for process improvement were identified and implemented including:• converting to a bottom feeding configuration to improve the grinding efficiency in the mill• additional grinding power in the fine grinding duty to compensate for the increase in plant throughput and ore hardness• improved classification efficiency by converting to smaller size hydrocyclones. Simulation studies carried out to evaluate the impact of these implementations had indicated that a P80 close to 35 &#181;m with a steeper size distribution could be achieved by using the bottom feed configuration with additional grinding power. The TowerMill circuit was converted to bottom feed configuration and the performance was evaluated. The operating work index, size specific energy and circulating load were 30% lower than the top feed configuration, indicating that the bottom feed configuration had a higher grinding efficiency. This paper discusses the outcome of the circuit audit, multicomponent analysis, circuit simulations, improvement strategies and quantification of the improvements. CITATION:Palaniandy, S, Spagnolo, M, Halomoan, R, Zhou, H and Ishikawa, H, 2017. Fine grinding circuit process improvement at the Karara mine concentrator, in Proceedings MetPlant 2017, pp 101–120 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By Merwin H. Howes

In constructing the NORAD Combat Operations Center, controlled blasting techniques were employed to achieve smooth walls and to avoid shattering the rock beyond excavation lines. Extraordinary measures were taken to stabilize the rock to permanently preserve the openings. Rock stabilization was accomplished by means of reinforced concrete and gunite linings, rock boltings, installation of chain-link fabric, and epoxy resin and cement grouting. A particular zone of weakness at B vital location was supported by exceptionally thick reinforced concrete lining, rock bolts, and cement grout.

Jan 1, 1966

By Kenneth K. Humphreys

INTRODUCTION What is automation? Why automate? Webster&apos;s New Collegiate Dictionary defines automation as "the automatically controlled operation of an apparatus, process, or system by mechanical or electronic devices that take the place of human organs of observation, effort, and decision." This definition gives an implied answer to the second question, "Why automate?" Automation, automatic control devices, and process control equipment receive their justification in supplementing or replacing manpower, which results in decreased operating costs. In the past, processes were operated with the minimum amount of instruments needed merely to guide operators. Processes were manually con- trolled by the operator on the basis of simple temperature, pressure, flow, and level indications on a panel. Today the tendency is to design a new plant to operate in a fully automatic manner according to a preset pro- gram utilizing a minimum of manpower. In addition to this direct cost reduction in manual labor, increased equipment capacity results from uniformity of flow and uniform control of process variables. This control eliminates or minimizes surges and permits equipment to be operated at or near its ultimate capacity and, for a given material throughput, permits the use of smaller process equipment. Automatic control, therefore, be it in the field of coal processing or in any industrial field, is simply a problem of economics. Control equipment is justified in terms of its contribution toward increasing productivity, increasing profit margins, or producing a new and salable product at a profit. Instruments and control devices can be divided into two general groups: (1) units which measure and (2) units which both measure and control a process variable.

Jan 1, 1979

By E. Barsky

The composition of multi-component materials is proved to be unambiguously determined by the composition uncertainty parameter (composition entropy). At the same time, every component, depending on its content, introduces a certain value into this parameter. Quality criterion of multi-component separation is determined by the total change of this parameter for all products obtained as a result of the separation process. This parameter can unambiguously estimate both multi-product separation and complicated schemes of modern beneficiation plants. It can be used to estimate binary mixtures separation, too. During the optimization of multi-product separation, another problem arises, which is not peculiar to binary mixtures. In this case, the total efficacy depends on the order of separation boundaries, as well. In the present paper, a specific example of initial product separation into seven products by six boundaries is investigated. It is clear that with respect to a single boundary, two products only can be obtained. In this case, the separation optimum is shown to correspond to the separation of boundary-class particles equally into both products. We have also established that from the point of view of entropy, the maximal possible separation efficacy corresponds to equiprobable composition of the initial mixture, i.e., the fine product quantity in the material to be separated is equal to that of the coarse product. Three groups of experiments were carried out. In the first group, the boundaries were consecutively specified from the finest to the coarsest one. In the second group, the boundaries were set vice-versa, i.e., consecutively from the coarsest to the finest one. In the third group, no sequence was observed. At every separation stage, a boundary was specified in such a way that the separated material composition was as close as possible to equiprobable one relative to this boundary. Total efficacy was different in all the three cases. In third group of experiments, its value is the highest, which confirms the advanced supposition. The obtained results are phenomenological, ? they can be applied to any processes of solid, liquid and gaseous materials separation.

Jan 1, 2014

By P. Mokwena

Paper written on project work carried out in partial fulfilment of BSc (Hons) in Chemical Engineering Diamond synthesis has attracted a great deal of interest because of its exceptional properties and various applications. In this study, the chemical catalytic vapour deposition (CCVD) method was used to synthesize diamond films using acetylene as carbon source and hydrogen as carrier gas at a temperature of 1000°C, and their thermodynamic stability was studied. Photographic analysis revealed that these products are diamond films, Ramman spectroscopy confirmed that they are graphitic while confocal laser scanning microscopic image analyses proved that these diamonds films have structural defects due to iron impurity from the catalyst precursor. The quantity of diamonds films produced is also proportional to the acetylene to hydrogen ratio but these films are larger in size at lower acetylene to hydrogen ratio. Thermogravimetric analyses showed that transformation of these materials begins at 25°C but could not be used to determine if a temperature range below 25°C exists. The stability of these CCVD-synthesized diamonds also increases below 25°C when stored at different temperatures.

Jan 1, 2007

A pilot plant was constructed for the low temperature carbonization of Wallarah (N.S.W.) coal at the rate of 300 lb/hr. The design was based on an entrained state carbonizer developed by Parry and D.S. Bureau of Mines co-workers. Prior to delivery to the client, the plant was successfully operated over periods of several days duration.INTRODUCTIONIn September 1961, the Australian Mineral Development Laboratories (A.M.D.L.) was engaged by the Broken Hill Pty. Co. Ltd. (B.H.P.) to design, construct and test an entrained state coal carbonizer with a capacity of 300 lb/hr of Wallarah (N.S.W.) coal. Char product was required within the specification 15&#183;5 -I- 1 per cent volatile matter. The design was to be based on a pilot plant developed by Parry and others in the D.S. Bureau of Mines Coal Research Laboratory at Denver, D.S.A. The method involved the carbonization of fine coal by entrainment with air in an externally heated reactor. The heat required for the carbonization of the coal was to be supplied to the bed both through the reactor walls, and also by internal combustion of products in the bed. Several D.S. Bureau of Mines Reports of Investigations weFe used as the main guide to the physical layout and proportions of the plant. However, the individual units required detailed designing, before engineering drawings could be prepared and fabrication begun.A 10 ton sample of crushed Wallarah coal was used for preliminary testing of the plant. The first test run on the pilot plant was carried out in February, 1962. After some modification a second test of longer duration was conducted in August, 1962. These operations aimed at running in the plant and also at determining the operating temperature to produce specification char and the maximum capacity of the...

Jan 1, 1963

By E. Fahrenkrog, D. Sbartaro, E. N. Cifuentes

An intelligent supervisor using expert system tools and applied to a crushing plant has been developed with a structure based on a model of a human operator. It consists of a knowledge base containing a qualitative model of the process and a rules base with the heuristic logic used by an operator when supervising a plant. The simulation results obtained show the potential of this type of system to supervise the automatic operation of a plant. There has been very significant development in artificial intelligence over the last two decades. Within this development, two approaches can be distinguished, (Winston, 1984). The "model approach," in which the main objective is to understand and model the be¬havior of living systems. The second approach is the "engineering approach." Here, systems capable of performing tasks usually requiring human intelligence are created. As part of this latter approach, knowledge engineering and its main achievement, expert systems, have been developed. Expert systems arose from the need to incorporate the abilities of a human expert in solving realistic problems in which the conventional approach has great difficulties. The first successful applications of expert systems were in medical diagnosis, geophysics, and fault detection. However, since 1971, when Fu (1971; defined intelligent control as the inter action of artificial intelligence and automatic control, some significant developments in the use of artificial intelligence tools for process control have been achieved (Astrom, 1986; Pinto 1988; Fahrenkrog, 1988; and Porter 1987). The modern control theory has made important advances. And, although successful in some applications, it has failed to cope with the practicalities of many industrial processes. As a result, the automatic operation of a plant has been confined to a small region around a normal operating point and to periods without any great disturbance. One of the main reasons for this is the lack of accurate and structured knowledge of the processes involved. Despite this, operators applying their knowledge, experience, and a little intuition, often obtain good results controlling the plant in such situations. Considering the above, the next obvious step is to include similar reasoning capacities in a computational system. The development of such an expert supervisory system prototype applied to a mineral crushing plant is presented. Problem description The problem is to conceive a control system with the ability to handle quali-

Jan 1, 1989

By Wils L. Cooley

Several aspects of coal mine safety-ground system operation are studied. Evaluations of two sophisticated ground-wire monitors are presented, along with a detailed report of development work on a modular ground-wire monitor. A portion of the report covers stray current flow in the safety-ground system, analyzing in detail conditions surrounding the generation of both dc and ac ground wire current. Considerable detail is provided concerning studies of mine ground beds. Additional progress is reported in the development of a. continuous ground-bed monitor, and new techniques are developed for the design of ground beds and their resistance measurement. New methods of accurately measuring electrical parameters of finite layered conducting structures are also reported. The effects of stray currents in ground beds is included. Touch-and step-potentials associated with mining equipment are analyzed, and methods are presented for determining earth voltage gradients around structures contacting earth. Instrumentation to determine gradients easily is suggested. Finally, an extensive effort is described dealing with lightning transients on open-pit coal mine ground systems. The nature of the transients, their expected frequency of occurrence, and the ways in which they damage equipment are analyzed in detail.

Jan 1, 1977

By D Pilone

The Tyrrhenian micro-nodules, findable at low depths (200/600 m under s l) are a reasonable reserve of manganese. They can be easily and cheaply recovered but do not contain valuable metals as in the case of oceanic nodules. In this work a hydrometallurgical process for manganese recovery from Tyrrhenian nodules is presented. The studied treatment includes the following operations: magnetic enrichment, reducing leaching, leach liquor purification and electrowinning . The study shows that the most important step in the process is the preliminary manganese enrichment. It can be done directly on the platform reducing not only the transport cost, but also the residue mud in the metallurgical plant. The leaching parameters such as status and size of nodules, temperature, composition of leaching solution and S/L ratio have been investigated. After purifying the leach liquor by iron precipitation as ammonium jarosite , the conditions to electrowin manganese have been investigated. The yields of both manganese leaching and iron precipitation together with current efficiency and specific energy consumption in the electrowinning step are given.

Jan 1, 2000

By Paul R. Dingess, Edward H. Hare, Douglas C. Brockie

Mining in the Tri-State district of Missouri, Kansas, and Oklahoma has been nearly continuous from about 1848 until the present day, although the major activity was from about 1880 to 1955. The district, which has produced over $2 billion in zinc and lead concentrates, ranks as one of the greatest mining districts in the world. Unlike other Mississippi Valleytype deposits in the United States, which occur in Cambrian and Ordovician limestones and dolomites, the Tri-State district ores occur in Mississippian limestones containing abundant chert. Zinc is 5 to 6 times more abundant than lead. In the Picher Field, the principal sub-district which has accounted for 61 percent of the total district production, most of the ore has been mined from the single horizon, M bed. Most ore bodies, other than those of the "Sheet Ground" or blanket-type, are in large, essentially flat-lying breccia zones and have a definite mineral zonal pattern. An irregular, generally elongated central dolomitic core is surrounded progressively outward by the main ore run, the jasperoid zone, the muddy or shaly and bouldery zone, the sparry calcite limestone zone, and the fossiliferous, dominantly crinoidal, limestone zone. Some of the zones may be absent or nearly so and may overlap to some extent with an adjacent zone. Although the district has been studied by many authors, much controversy still exists about such items as genesis, paragenesis, and time of emplacement. These subjects are discussed in the paper.

Jan 1, 1968

By H. Doostmohammadi

During the tapping of liquid steel from Electric Arc Furnace (EAF), some slag is carried over into the ladle. High levels of FeO and MnO in slag carryover increase the oxygen activity in steel melt leading to oxide inclusion formation during the ladle treatment. The demand on cleaner steels requires minimization of carryover slag. In this work, the effect of EAF slag carryover on ladle slag-steel equilibrium calculations for a hot working tool steel was studied. Steel and slag sampling were done in Uddeholm Tooling AB in Sweden. XRF and OES techniques were used to determine chemical composition of samples. The quantity of slag carryover was calculated based on a mass balance followed by thermodynamic calculations on metal-slag equilibrium using Thermo-Calc software. The agreement between predictions and experimentally determined compositions was good. This leads to the development of a prediction method for optimizing the production of other tool steel grades.

Jan 1, 2009

By James P. Ulery

In This Chapter [Geologic features associated with anomalous methane emissions Gas outbursts and blowers Methane drainage strategies for mitigating anomalous methane emissions and General considerations for a methane drainage program] This chapter summarizes how certain geologic features may be associated with unexpected increases in gas emissions during coal mining. These unexpected emissions have the potential to create explosive conditions in the underground workplace. Also discussed are the generally used practices to alleviate potential hazards caused by gas emissions associated with these geologic features. INTRODUCTION Unforeseen mine gas emissions in quantities sufficient to create hazardous conditions have been attributed to sources outside the mined coalbed since the first documentation of methane explosions in coal mines [Payman and Statham 1930]. Geologic features such as faults have long been recognized as conduits for gas flow from strata adjacent to mined coalbeds [Moss 1927; Payman and Statham 1930]. Other features such as sandstone paleochannels, clay veins, and localized folding have also been recognized for their impact on gas emissions into mine work-ings [Darton 1915; Price and Headlee 1943; McCulloch et al. 1975; Ulery and Molinda 1984]. The fact that strata adjacent to mined coalbeds can emit large quantities of methane gas into mine workings is not surprising from a theoretical perspective. Many researchers have recognized that during the burial and diagenesis of the organic matter forming today’s minable coalbeds, similar dispersed organic matter in adjacent strata has produced methane in quantities far exceeding the storage capacity of the coal and surrounding rock [Juntgen and Klein 1975]. It is not surprising then that large quantities of methane can remain trapped in these strata. A potential hazard occurs when mining of a nearby coalbed causes pressure differentials and mining-induced fractures conducive to gas flow into the mine workings from these strata. This gas flow may be facilitated or temporarily impeded by the presence of geologic structures or anomalies.

Jan 6, 2006

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 G. E. McElroy

Tae purpose of this paper is to present types of charts adapted to aid in the graphic solution of fan-performance problems of selection and operation, and to urge the adoption of similar charts by the National Association of Fan Manufacturers as standard forms for presenting fan-performance data. As matters now stand, it is difficult for the average engineer to solve such problems because a laree number of variables are involved, and performance data are not presented in a manner that permits their direct application to many problems encountered in practice. The performance of any centrifugal machine is determined not only by the machine itself but also by the fluid-flow system on which it operates. Actual performance of centrifugal fans is therefore e matter of the type, size, and speed of fan, on the one hand, and of the relation of pressure to quantity of flow, as determined by the physical condition of the airway system, on the other.

Jan 1, 1936

By G. E. McElroy

[The purpose of this paper is to present type: of charts adapted to aid in the graphic solution of fan-performance problems of selection and operation, and to urge the adoption of similar charts by the National Association of Fan Manufactures as standard forms for presenting fan-performance data. As matters now stand, it is difficult for the average engineer to solve such problems because a large number of variables are involved, and performance data are not presented in a manner that permits their direct application to many problems encountered in practice. The performance of any centrifugal machine is determined not only by the machine itself but also by the fluid-flow system on which it operates. Actual performance of centrifugal fans is therefore a matter of the type, size, and speed of fan, on the one hand, anti of the relation of pressure to quantity of flow, as determined by the physical condition of the airway s: stem, on the other.]

Jan 1, 1936