Search Documents

By Lu Lin, Yan-ping Bao, Min Wang

In order to forecast the cost of dephosphorization during BOF process, and achieve economical dephosphorization of BOF. The mathematical model of dephosphorization cost for BOF process was established. The model calculations show that, when the silicon content and phosphorus content are increased in hot metal, and the final phosphorus content of BOF is decreased, the dephosphorization cost will be increased. The silicon content of hot metal is increased of 0.1% in the plant, the dephosphorization cost is added by 9 RMB/ton steel. The De-P cost of mode A is much higher than the other two modes for three typical production modes of single slag melting process, when the phosphorus content of hot metal is higher than 0.14%, an increase in the phosphorus content by 0.01%, the De-P cost of mode A is added by about 7 RMB/ton steel. Meanwhile, when the phosphorus content of hot metal is lower than 0.165%, the De-P cost of mode C is higher than mode B’s. For BOF single slag melting process, the dephosphorization cost calculated by model is between ± 2%, proving that the model is reliable for the prediction of dephosphorization cost.

Jan 1, 2015

By E. A. C. Chamberlain

New techniques for the continuous sampling and analysis of mine air are expected to replace traditional methods used for the early detection of spontaneous combustion. It has been established that the rate of evolution of carbon monoxide is the earliest indicator of incipient spontaneous combustion. Two methods of continuous monitoring of this gas are available and are now in use in the UK collieries. The first is the UNOR infra-red gas analyser, which is flameproof and may be used underground; the second is a system of tube bundles, which permits air to be drawn from any critical point in a colliery and analysed on the surface. Each system has its advantages and disadvantages but both provide the colliery manager with far more information on the condition of his pit than could previously be obtained by spot sampling and laboratory analysis. This paper describes the two systems presently in use and assesses likely future developments.

May 23, 1905

By W. F. Watts

In 1980 the Bureau of Mines developed the Mine Inspection Data Analysis System (MIDAS). MIDAS is a computerized, industrial hygiene data base capable of statistically analyzing environmental data collected in coal and noncoal mines and mills by Mine Safety and Health Administration (MSHA) inspectors or mine operators. The objectives of this report are to describe the current contents of MIDAS, to report analyses of coal and noncoal mine respirable dust samples collected by MSHA inspectors and to evaluate the proposed change in the metal and nonmetal respirable dust standard from a formula based upon the percentage of quartz identified in the sample to 100 µg/m3 of respirable quartz. Based on samples collected by MSHA inspectors, changing the noncoal respirable dust standard would result in 4 pct fewer samples with dust concentrations exceeding the standard. Analysis of respirable coal dust data collected by MSHA inspectors showed that mines with longwall plows or shears had the highest geometric mean concentrations (1.64 and 1.29 mg/m3, respectively). Mine operations using continuous rippers out-numbered longwall mine operations about 10 to 1 and had a geometric mean concentration of 0.66 mg/m3.

Jan 1, 1987

By Gregory B. Beacher

Analyses have been performed on geotechnical properties of copper, uranium and phosphate (gypsum) tailings materials, with the intent of identifying typical measures of variability within and among sites, and of characterizing such variability for use in reliability modeling of tailings embankments. In all, data from approximately 41 sites were analysed. Fairly consistent results were obtained for within site variabilities. However no one probabilistic model was found to be applicable to all sites. The distributional forms for most of the data sets are regular, and tend toward Normality when spatial trends are removed. At many of the sites sufficient in situ data were available to allow estimates of vertical autocorrelation distances and measurement noise. Available data indicate that variability in pore pressures may have a more important effect than strength property variation. A major problem in interpreting available strength property data results from the unknown drainage conditions during testing.

Jan 1, 1983

By S. Amid, D. Fisk

"Wireless technologies are permeating the mining and metals industry and enabling a myriad of benefits. With standards such as IEEE 802.11 for wireless devices and ISA100.11a for wireless field instruments protecting their investments, customers look to benefit from the cost and flexibility offered by wireless devices. Using wireless field instruments, plants are eliminating the costs associated with wired system by 50 to 70% and using these savings to install more field instruments, which, when used smartly, enables them to optimize their processes efficiency and equipment reliability. Wireless also empowers a mobile workforce by allowing them to have access to key process and maintenance data directly from the field. This paper describes how wireless can help operations and maintenance personnel to be more effective. Three case studies, illustrating how the mining and metals industry is taking advantage of the technology today, are presented:1.,Optimisation of the water recovery process using wireless2.,Field operations improvement with wireless handhelds3.,Improving fleet maintenance through wireless mobile equipment management"

Jan 1, 2011

By Seth H. Hamblin, John E. Regan, Dimitrios Palantzas

"Through reliability-based calibration of larger pile load test databases, recent developments of the Load Resistance Factor Design (LRFD) methods, which include geotechnical load and resistance factors for deep foundations design, have advanced the state of practice for geotechnical engineering. These load test databases upon which the current geotechnical load and resistance factors have been developed are limited, however, and do not provide sufficient data to support the development of resistance factors for uplift (tension) pile capacity. As such, some recommended resistance factors for uplift capacity estimation methods are simply derived by reducing the recommended resistance factors for piles in compression by a factor of 0.10.The results of three (3) tension loading tests performed to failure on 508 mm (20- in) square precast, prestressed concrete piles, driven though granular soil in southeastern Massachusetts, are presented and compared to static pile capacity calculations and dynamic analyses performed using the Pile Driving Analyzer (PDA) during installation. These results are presented along with current recommended LRFD resistance factors for driven piles under uplift (tension) loading conditions. These comparisons offer an assessment of the applicability and limitations of current resistance factors methods for piles under uplift loading and may be useful additions to the existing database for future calibrations of LRFD resistance factors for driven prestressed concrete piles in sand.IntroductionIn 2010, two (2) natural draft cooling towers were constructed by Kiewit (Kiewit) Construction Company of Woodcliff Lake, New Jersey at the Brayton Point Power Station in Somerset, Massachusetts. These massive 500 foot tall, 400 foot diameter cooling towers were designed to convert the existing “open loop” system into a “closed loop system” thereby dramatically reducing the thermal impact to Mt. Hope Bay.Based on design guidance from the German VBG Design Code and the Massachusetts State Building Code (MSBC), tension (i.e. uplift) and lateral loads due to wind loads and design seismic events represented the critical loading conditions.Weighing approximately 190,000 kips upon completion, the cooling tower loads are transferred to 44 foundation nodes (i.e. pile caps) evenly spaced along ring beams which run the circular perimeter of each tower base. Each pile cap node was designed to resist a 2,000 ton compression load, 200 tons in tension (i.e. uplift), and 600 tons in the lateral direction."

Jan 1, 2015

By David J. Boron

The United States has the largest total (364 billion metric tons) and recoverable (182 billion metric tons) coal reserves in the world.1 However, progressive coal utilization in this country has been hampered by environmental constraints, such as restrictions on sulfur dioxide, nitrogen oxides, and particulate emissions. New technologies are being pursued both to appease these environmental concerns and improve economic performance and process efficiency. These technologies, however, have not reached the level of effectiveness required for optimum operation. If more stringent emission standards are imposed, it is likely that the coal industry, and the industrial and utility sectors will look increasingly toward the successful development of new and advanced coal cleaning technologies in order to continue and promote the use of coal in this country. The EPA New Source Performance Standards In 1979, the Environmental Protection Agency in response to the amendments to the Clean Air Act of 1977 issued new source performance standards (NSPS) for utility and industrial boilers. The NSPS set emission standards for sulfur dioxide, nitrogen oxides, and particulates affecting boilers of 250 MM Btu per hour heat input or 'greater that started construction after September 1978. Plants starting construction or in operation before September 1978 remained subject to the provisions of the regulations promulgated in 1971, i.e., SO2 emissions of 1.2 15/MM Btu. The NSPS for SO2 emissions provides a sliding scale for SO2 reduction depending on the sulfur content of the run-of-mine coal, with an upper limit of 1.2 lb of SO2 per million Btu and a minimum emission level based on 70% SO2 removal. Table 1 summarizes the EPA NSPS for SO2 emission standards.

Jan 1, 1983

By John W. Tieman

The increasing magnitude of our nation's pollution problems seems to stem from two main factors: urbanization and technical advance. In 1920, less than half the country's 106 million people lived in cities. Forty years later, the urban population accounted for 70 percent of the nation's 179 million. It is predicted that by the end of the century, 95 percent of the U. S. population, estimated at 280 million, will live in urban areas. As these people live increasingly in city concentrations, their residues also concentrate. With technological advances to support the increasing population, the variety and quantity of goods that we use also increases. New materials and processes result in increases in pollutants, some of them new. The harmfulness of these pollutants is sometimes known, but sometimes only suspected. One pollutant of concern at the present time is sulfur dioxide, the product of combustion of sulfur-containing fuels. Research on processes to remove sulfur oxides from flue gas has been in progress for many years. Pioneers in this field were the British who, in the early 1930's, installed a full-scale flue gas scrubbing unit on a 120 MW boiler using alkaline water from a Thames estuary plus chalk. Since that time, various methods have been studied by many investigators. Federal laws covering air pollution started with the 1955 Air Pollution Control Act. With the advent of the Air Quality Act of 1967, and subsequent publishing of criteria and available technology for control of sulfur oxides in January 1969, the clamor for information on commercially available control techniques to remove sulfur from fossil fuels has rapidly increased. Although many state-of-the-art papers have deluged the literature during the past several years, the research going on in the area of sulfur oxides control is of such importance that periodic reviews are justified. It is the purpose of this paper, therefore, to again review the state-of-the-art, but this time from the stand-point of what is immediately commercially available

Jan 1, 1972

By Jingzhi Liu, Xueping Hu, Huai Wang, Simin Yang, Baoqiang Yu, Deguang Zhan

In this study, response surface methodology (RSM) and Box-Behnken design to improve copper extraction from refractory copper oxide ore were investigated. Based on single factor tests, quadratic polynomial equation to describe the relationship between influencing factors (particle size, leaching temperature, sulfuric acid concentration, leaching time) and copper leaching rate could be obtained by RSM. The optimum parameters determined by the model are as follows: particle size 64.60% − 74 μm, leaching temperature 74.15 °C, sulfuric acid concentration 0.49 mol/L, and leaching time 140.85 min. Under these conditions, experimental copper leaching rate of 85.12% could be achieved, which was very close to the predicted maximum value (85.34%) by the model, indicating the quadratic polynomial model was accurate and reliable. Copper leaching rate increased approximately by five percentage points comparing to the result of single factor tests. This study indicates that response surface methodology is an effective method to optimize experiment conditions and achieve an ideal experiment result.

Aug 17, 2022

By O. Lashkari

Manipulation of pouring temperature is an efficient way to produce different microstructural features. In order to characterize the microstructure of rheocast billets due to different superheats of 615-695 °C, the parallel plate compression method was employed. Foundry 356 Al-Si alloy with different morphologies of primary a-Al particles were tested at different initial pressures of 4,8, 11,2 KPa, The resulted strain-time graphs were further treated mathematically to calculate viscosity of SSM billets. The interrelationships of viscosity, the microstructure and primary phase flow during compression are discussed, It is shown that the dendritic primary a-Al structure has the highest viscosity number which is almost three orders of magnitude greater than those for globular morphology, The current research have, for the first time, shown the validity and reliability of "parallel plate compression viscometry" method in characterizing microstructural evolution of Rheocast SSM billets.

Jan 1, 2005

Reliable and discriminating small, laboratory scale methods of study have been developed and used successfully in the critical evaluation and interpretation of the carbonization characteristics of a wide range of raw and prepared materials, the variable factors in the coking process, and' the mechanical properties of the carbonized products. The simple and highly economic technologies have been successfully and effectively integrated with detailed surface and subsurface geological exploration programmes (particularly in the coalfields of the .Central Bowen Basin of Queensland) as well as with quality and utilization studies of a nUII!ber of representative Australian and Japanese coals. Previously, only the results of comparatively large, laboratory scale studies have provided information reasonably indicative of those to be anticipated hi industrial practice, but these suffer serious disadvantages in terms of economy of material, time and resources; they have been difficult or even impossible to use as an essential part of any normal or comprehensive exploration programme. On the other hand, although previously developed smaller scale laboratory methods derive considerable advantage from their flexibility, amenity to critical control and inherent potential for speed and economy, they have hitherto permitted no effective or direct comparison with the results of industrial practice or full scale assessment. Comprehensive study results achieved through technologies developed recently at the University 'of Sydney demonstrate that carefully controlled small laboratory scale methods of evaluation quite suitable for use in exploration and, other programmes may be used to predict with considerable accuracy and reliability (in some cases exceedingthat of pilot scale study) the principal strength index of one of the established and internationally recognized full sc:ale tests-the Japanese Industrial-Standard Drum Test. It is probable that further study may establish satisfactory correlations with the results of other standard industrial procedures.

Jan 1, 1969

During the period 1979 thru 1982, Multi Mineral Corporation conducted a mining I research program at the United States Department of the Interior's Bureau of Mines Oil Shale Mining Environmental Research Facility in the Central Piceance Creek Basin, Rio Blanco County, Colorado. The program consisted of mining, environmental and geotechnical research data and, the results are described in this report.

Jan 1, 1983

By D. W. Leyshon

The fluidized solids technique for the calcination of phosphate rock has been well established for over 10 years. This paper is intended to review the recent performance of many of the Dorr-Oliver FluoSolids* calciners. In addition, design features of these three compartment refrac¬tory construction reactors will be described and a comparison made with fuel requirements for single compartment calcination. Also presented will be certain, aspects of the use of the rock including a discussion of non sulfate sulfur in the rock. A system is described for producing a blended mixture of calcined and uncalcined rock.

Jan 1, 1972

By R. Hogg

A standard procedure for determining size-specific gravity distributions of fine coal (including the -400 mesh fractions) by sieving and centrifugal sink-float separation is described. The significance of using a centrifugal sink-float technique and the effect of the magnitude of the centrifugal force on the separation of fine coal are confirmed in the present study. The relative merits of cumulative versus incremental sink-float are discussed. The procedure is evaluated quantitatively using data obtained for the products of froth flotation of -100 mesh coal.

Jan 1, 1994

By P F. Knights, P Boniwell

This paper investigates the causes of low effective utilisation of the production drill fleet at the Telfer Underground Gold Mine, as measured by the percussion hours per shift. The first part of this paper focuses on a site time and motion study conducted to accurately identify shift time allocation and optimal drilling parameters (manual versus automatic, and suitable flushing mediums for varying ground conditions) as well as quantifying the business potential for automated or remotely operated production drilling. The second part of the paper focuses on the rate of successful hole completion for automated production drilling during shift changes. Two main areas of drill optimisation were identified. Firstly, a site-specific drilling procedure was established so as to ensure that all operators were drilling using optimal parameters. Total production metres per rig increased by 10.7 per cent as a result of the implementation of this standard. It was observed that a 25 per cent faster overall drill cycle was achieved using air mist flushing, and that manual drilling achieves a 19 per cent faster overall drilling cycle in comparison to automated drilling. Secondly, routine provision to the maintenance department of automation reliability reports that outlined the principal causes of unsuccessful hole completion led to an increase in production metres of a further 4.1 per cent, measured between January 2007 and August 2007. First hole automation reliability increased from 39 per cent to over 77 per cent over the same time period. Second hole automation completion was increased to 74 per cent, leading to a higher proportion of production achieved through automated technologies.

Jan 1, 2008

By Lloyd R. Nelson

Experimental results of three-phase mixing in a physical model of a CCRL for metals refining are presented. The system was operated above a critical lower liquid height-to- width ratio (H,/W) of unity, with adequate bottom gas injection through a line of central, single tuyeres (Q,/A = 7.5 cm/min, or c = 17 W/m3) to sustain levels of interphase transport considered appropriate to an industrial pyrometallurgical refining operation. The application of a thermal tracer technique to elucidate both longitudinal mixing and interphase heat transfer is discussed. The results indicate that even under conditions of significant bottom gas injection, it should be possible to maintain acceptably low longitudinal mixing 1 (D, < 20 cm /s and D,/uL < 0.1) in the CCRL. Interphase mass transfer coefficients of the order of 0.004 cm/s are predicted from the measured interphase heat transfer coefficients (h = 1.3 to 2.0 kW/m2K), using the heat and mass transfer analogy. Adequate rates of rehning are predicted for an industrial CCRL operated under such conditions.

Jan 1, 1995

By E. Dalgaard

During linear friction welding of titanium alloy Ti-5A1-5V-5Mo-3Cr (Ti-5553), the weld zone exhibits beta (B) grain refinement and alpha (a) phase depletion that have the combined effect of deteriorating the mechanical performance of the weldment. In this work, linear friction welded Ti-5553 was subjected to pre- and post- weld heat treatments in order to determine the conditions under which a phase depletion could be mitigated in the weld zone and thermomechanically affected zone (TMAZ). The mechanical response of the welded samples to the heat treatments was determined by performing tensile testing at room temperature. While the pre-weld heat treatments had no significant effect, the post-weld heat treatments were instrumental in restoring the strength of the starting (heat-treated) material.

Jan 1, 2011

By S L. Martin, M Wimberger

The binary indicator coding of assay and lithological data according to a single criterion or multiple criteria is a powerful technique for representing mineralised shapes through the modelling of probabilities. This can be as simple as using a single indicator to model the probability of occurrence of a condition, usually a grade threshold or a lithology, but it can also be used with a number of categories. Case studies are presented to show the power of this approach, where the geological controls on mineralisation or on the distribution of a rocktype or alteration, often coupled with mineralisation, are unclear. The categorical approach is often used as a de facto grade filter in disseminated or stockwork mineralisation. The ultimate expression of the indicator formalism is in multiple indicator kriging (MIK), where a conditional distribution of probabilities is generated for each estimation panel. This has applications in recoverable resource estimation, as the input for continuous or categorical simulation, where the distribution of sample grades is multimodal, or when there are superimposed mineralisation events with different orientations. However, in some cases, MIK is being used as an excuse for ignoring a quality geological interpretation. Examples from the public domain show the abuse of the categorical and MIK approaches to modelling probabilities, together with a plea for greater consideration of the geology.

Mar 22, 2022

By Li. Jiarong, Zuojian Liang, Qingyan Xu, Baicheng Liu, Shizhong Liu, Hailong Yuan

Single crystal solidification of turbine blades is a key technology for the production of reliable and high efficiency gas turbines. The solidification process of single crystal investment castings causes a number of problems that have to be solved such as the increase of casting defects and complexity of production process. Computer modeling and simulation is helpful to predict the defects and improve the process design. In the paper, a mathematical model for three dimensional simulation of solidification and single crystal growth of investment castings was developed based on CA, mechanism of crystal growth and basic transfer equations such as heat, mass transfer equations. Many factors including constitutional undercooling, curvature undercooling and anisotropy, which had vital influences on microstructure evolution, were considered in the model. Temperature, crystal growth interface and structure defects of investment castings of single crystal superalloy were investigated at withdrawal rates of 4.5mm/min and 7mm/min. Simulated results showed that microstructure evolution and structure defects were predicted reasonably and calculated results were coincident with experimental ones. The study indicated that three dimensional solidification simulation technique is a powerful tool for understanding the fundamental of solidification and the formation of structure defects in single crystal investment castings and finally for optimizing process design.

Jan 1, 2004

By R Moreby, J Kok, L van den Berg

The high production rates achieved from mass mining methods such as block caving, sublevel caving and longwall mining require large conveyor belts, trucking loops (diesel/electrical) and rail systems for ore handling. However, the ore handling systems used in mass mines introduce a significant amount of heat into the overall ventilation system, which may be problematic at depth or in mines located in hot climates.In particular, the heat load from a conveyor system is not always well understood and consists of various components, including frictional heat from idlers, heat from electrical motors, heat from the drive train and heat from broken rock transported on the conveyor system. This paper presents results from a study that investigated the heat introduced to the ventilation air from a large conveyor system. The conveyor system transports ore with a maximum virgin rock temperature of 41&#176;C from a depth of over 1 km. Air, belt and rock temperatures were measured in the conveyor system to evaluate the distribution of heat loads.CITATION:van den Berg, L, Moreby, R and Kok, J, 2015. Heat load estimation from conveyor systems in mass mines, in Proceedings The Australian Mine Ventilation Conference, pp 63–70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015