Search Documents

By F. M. Isik

Due to not to being our own sources, some energy sources such as oil and natural gas which are used frequently, are not reliable energy sources for our country. Coal is an important energy source that Turkey also has a certain reserve as many countries have. To be able to use for many years the reserves of this source that comes from fossils, there is a great need to make more investigation and development activities on it. On behalf of using more productively the current sources, briquetting facility is represented that commenced production in The Aegean Lignite Establishment in 2005 which is in Manisa, Soma. This facility is a part of General Directorate of Turkish Coal. This facility is run by Soma Coal Establishment that works in return for royalty in a licensed field that belongs to TKI. As the demand of market for 0.5 mm dust coal diminishes, we had to accumulate and stock unmerchantable dust coal. Besides, we have intermixed 0.5- 1 mm powder coal and 0.1 ? 0.5 mm fine powder coal obtained as a result of washing in coal washer with thermic coal with low price as we could not find a client in the market. In this study, the production stages of briquette coal with high quality produced as a result of pressing by mixing 0.5- 1 mm powder coal and 0.1 ? 0.5 mm fine powder coal with molasse and lime, quality control, and data?s obtained about calories and solidity of products were presented. By briquetting of 0.5- 1 mm powder coal and 0.1 ? 0.5 mm fine powder coal washed in coal washer, it became possible to sell these coals on a high unit price and by providing the demand of coal of the market, we contributed to productivity of our firm. Keywords: briquette coal, briquetting, producing stage

Sep 1, 2012

By A. Manohar Rao

Underground mining in general and more so the coal mining is a hazardous venture as it is a struggle against nature and natural forces. The stability of roadways has a direct impact on production and productivity. The roadway stability can be strongly influenced by the direction of the drivage. The stress studies are useful to provide a frame work for understanding the influence of drivage direction on roadway conditions, and to illustrate how mapping techniques can enhance this understanding. The act of mining can concentrate and re-orient the original stresses. Whenever coal is removed, the overburden weight that it carried is transferred. Vertical stresses are similarly affected when the roof is deformed or failed. The Singareni Collieries Company Ltd., a joint Public sector undertaking of the Government of Andhra Pradesh and India is conducting coalmining operations in the Godavari Valley Coalfield and is catering to the needs of a large part of South India. With the technology update, it is looking for safe mining and to achieve higher production. As a part of this, an attempt is made to understand the stress conditions prevailing on the mine blocks by different ways and means in terms of geology, structure and tectonics of the Godavari Valley coalfield, satellite imagery studies, cleat pattern, stress measurement studies conducted in different mine blocks, and stress mapping technique.

Aug 1, 2013

By R. M. Hardgrove

PULVERIZED coal was first used for firing cement kilns about 45 years ago, with such success that it has continued in general use. Based on cost, pulverized coal is usually the most economical fuel. In some localities natural gas or oil is cheaper, but 85.5 per cent of all cement kilns at present are fired with pulverized coal. The pulverized-coal flame is well suited to kiln conditions. Its soft, luminous nature gives it a high radiating property and the length of the flame can be readily varied to suit conditions in a kiln of any length. Ash and slag cause most of the difficulties incident to the burning of coal. In a cement kiln, however, the ash, being similar in composition to the raw mix and being deposited uniformly in the mix and clinker, occasions no difficulty as long as it remains constant in quality and quantity. Until 6 years ago almost all cement kilns using pulverized coal employed the bin system. The coal was dried and pulverized in a separate plant and delivered into a bin at the kiln. Thus the bin system requires driers, storage-type pulverizers, conveying systems, individual kiln bins, pulverized-coal feeders and primary air fans. The direct-fired system requires only a pulverizer and a blower. Fig. I shows typical plants. The first installations of direct-fired pulverizers were of the impact type but fineness of pulverization was both inadequate and variable. About 1927 a few direct-fired installations employing tube-type pulverizers were made, which were much more satisfactory. As more efficient pulverizers were developed from 1934 on, equipment for direct firing was installed at a large number of plants, until now 196 of about 900 kilns in use in the United States are direct-fired. Most of these replaced antiquated bin systems. PROCESS OF BURNING CEMENT CLINKERS The process of burning cement clinkers is fundamentally one of heat transfer. In boilers and other heat-exchange apparatus the area of the surface receiving heat from the gases is the best unit for comparing output. This seems to be equally true for kilns. The inside kiln surface is the heat-receiving surface and its area is used as the unit of kiln size in the following comparisons. Heat input is based on British thermal units in the fuel. E. G. Bailey,1 in his work on boiler-furnace heat absorption, has used the unit "B.t.u. available." This is the practical calorific power of the fuel, plus the heat in the air used for combustion. In other words, it is the heat available for useful work in the furnace or kiln. The unit of kiln output is barrels per hour. The composition of the raw mix, the percentage of water in the slurry of wet plants and hardness of burning all affect the output. These conditions, however, are hard to evaluate and probably have less effect on the output than irregularities of raw feed and clinker discharge and inexpert control of combustion. WET VS. DRY PLANTS The study presented here covers 88 plants, of which 41 are wet and 47 dry. Of

Jan 1, 1941

By M. Howard Berliner

The Harding pegmatite dike is well known for the production of spodumene and lepidolite in the period 1920 to 1930. It attained greater prominence during the last war by being the largest producer of domestic tantalum ore from the rare mineral microlite. The deposit is believed to be the only proved reserve of tantalum ore in the United States today. In 1943 the main portion of a large tantalum-bearing zone in the Harding dike was developed by the Bureau of Mines with the assistance of the Federal Geological Survey. Analysis of this zone from 39 diamond drill holes and quarry exposures showed a large deposit containing 2 pounds of microlite per ton and 21 percent spodumene, In September 1948, the Bureau of Mines resumed development of the deposit with a view to extending the tantalum-bearing zone farther to the southwest or delimiting the ore body. Seven diamond-drill holes failed to penetrate the ore zone in its southwestward projection, Much of the following general information is summarized from the report on the first exploratory work of the Bureau of Mines by John H. Soule.2/

Jan 1, 1949

By E. Herrera Alarcón, L. Mariscal Samaniego

The Teniente Converter (wet charge type) was commissioned in august 1995 and was designed to smelt 744 tpd (metric tons per day) of dry copper concentrates. Its products are white metal (73% Cu) that is sent to the Peirce Smith converters, slag that is cleaned in Reverberatory Furnaces and the process gases that are sent to the Sulfuric Acid Plant. Since its start up, the Teniente Converter smelting capacity was increased 1.6 times, from 800 tpd to 1,280 tpd using 33% oxygen-enriched air, and reaching an operative availability of 97%. By the other hand its campaigns have reached a record duration of 530 days without hot patching tuyeres and a partial refractory lining repair in the last four campaigns. This paper describes the most relevant improvements, as well as the strategies that had been used to reach these achievements.

Jan 1, 2007

By Ananda Moreira Vaz Ourique de Avila

High and intermediate temperature fuel cells (FC) are power generators characterized by high efficiency and their use in cogeneration systems. The single fuel cells are connected in series by the use of interconnects to form a fuel cell stack. Ferritic stainless steels have been used in the making of high and intermediate temperature operation solid oxide fuel cells interconnects. However, at high temperatures, on the order of 700-8500C, these steels can present significant oxidation and degradation processes, promoting increased electrical resistivity and corrosion losses that result in contamination of the electrodes and reducing the performance and the useful life of the FC. Intensive R&D activities have been made to minimize these problems and the use of composite coatings on metallic substrate has been considered. This paper evaluates the use of coatings of copper and nickel, with particles of La2O3, Y2O3, CeO2, LaCrO3 and doped chromites applied on ferritic stainless steels AISI 430, AISI 441 and Crofer22APU produced by electrodeposition. The produced samples were evaluated by microscopy techniques, gravimetric analysis and by electrothermal characterization. The most significant results were obtained with chromites coatings (LaCrO3 pure, mono- and multiple-doped) showing the combination of the best features of metal coatings, substrates and ceramic particles with semiconductor properties.

Aug 7, 2018

By Xiangwen Wang

Electrochemical measurements associated with the electrowinning of lead metal from concentrated brine (NaCI) - lead chloride (PbCI,) electrolytes at temperatures in the range 328 to 353°K (55 - 80°C) were conducted. The electrodeposition of lead metal onto a lead rotating-disk electrode may be described by the electrodic reaction: {PbCl 4 2 + 2e- = Pb° + 4Cl-} The deposition-overpotential requirements are low (approximately 41mV per decade of current density - Am+), with a corresponding high exchange current (approximately 0.018 A.cm2). The diffusion coefficient of the electroactive PbC142- species in a 3.5 NaCl electrolyte at 353°K was insensitive to the total PbCI, concentration (0.01 to 0.1M), and its value was found to be (1.21*0.1)~10-5 cm2Is with a temperature-sensitivity coefficient (E,/R) of approximately 1.98x103K-1 (328OK(T<353OK).

Jan 1, 1993

By Jianxun Song, Hongmin Zhu, Qiuyu Wang, Jungang Hou, Shuqiang Jiao, Xiaobo Zhu

This work presents the results of a study on the Ti3+/Ti2+ couple redox potentials vs. Cl–/Cl2 at the temperature range (673 to 1073 K) in fused LiCl-KCl eutectic by direct potentiometric method. Initial concentrations of TiClx in solvents did not exceed 5.0 mol%. Basic thermodynamic properties of the reactions TiCl2+1/2Cl2(g)=TiCl3 were calculated using the temperature dependencies of apparent standard potentials of the couples E* Ti3+ /Ti2+.

Jan 1, 2014

By Mark Abernathy

When most people think of a motor vehicle accident, the direct costs resulting from that accident, such as vehicle repair or towing charges, are generally easy to quantify. However, the indirect costs associated with an accident are often overlooked. These indirect costs can take a tremendous toll on a company in more ways than you might think.

Jan 1, 2006

By K Sherry, N Shahbazi

Scope 3 emissions are a set of often overlooked indirect greenhouse gas emissions within a company’s value chain and represent the majority of emissions for many sectors. These emissions arise from activities conducted by entities beyond the reporting organisation’s ownership or direct control and are often challenging to calculate. Scope 3 emissions typically encompass purchasing goods and services, transportation and distribution, managing operational waste, downstream processing and utilising sold products. Within the mining sector, scope 3 emissions often constitute a significant portion of the overall carbon footprint. Therefore, these emissions are a significant aspect of the future of sustainable mining. As the journey towards a world committed to achieving Net Zero Emissions has started, the time to spark a transformative conversation in the mining industry has arrived. Consequently, a better knowledge of scope 3 footprints allows organisations to assess their emission mitigation projects against the total carbon impact of their operations and products.

Sep 1, 2024

By R. V. Ramani

In a 1985 seminar, we were told that overoptimism abounds in Artificial Intelligence (AI), that A1 is neither a science nor a technology yet, and that we will be both exhilarated and disappointed with AI. In fact, even today, there is no single accepted definition of AI; however, certain features have been identified by AI researchers as essential to consider an entity.(e.g: machine or program) to be intelligent. According to Shank (1987), these features include communication (to be able to communicate with), internal knowledge (knowledge about itself), world knowledge (awareness and knowledge about the world outside), intentionality (knowing what one wants and a plan to seek it, ie. goal seeking behavior), and creativity (being adaptable to changing conditions). None of these figures would individually define intelligence; however, each would be a part of intelligence in its own way. The prospects for the development of entities with AI have never been as good as they are now. The combination of advancements in computer hardware and software along with new insights into the ways in which we store knowledge and use it for problem solving has enhanced the potential for the creation of intelligent entities. After some unbounded optimism of a major breakthrough in the fifties and frustrating disappointments in the two following decades, it appears now that AI has emerged from research labs to industrial practice. This is confined by the growing number of repeat applications of AI in business and industry to the extent that AI can now be considered a technology.

Jan 1, 1989

By Piyush K. Dutta

This report describes the design, development and manufacture of a prototype quiet hard rock stoper drill and results of its field tests. It is shown that the stoper drill noise level can be reduced from 118 dBA to below 100 dBA by using this design. The design concept of this drill is based on a valveless independent rotation system, use of an integral muffler and pivot mount. The drill was manufactured in a standard commercial drill manufacturing setup and organization. The design and production technology proved that commercially viable quiet drills can be made available for mine use.

Jan 1, 1985

By John E. Frost

The Gibralter Mines Ltd. complex is 61 km (38 miles) north of Williams Lake in central British Columbia, Fig. 1. The discovery of these deposits evolved in stages such that each stage revealed a bigger piece of the elephant. When the elephant was mostly revealed, Placer Development Ltd. brought the property into production. Although Gibralter is aporphyry copper deposit, it is certainly not a typical one. Copper and minor molybdenum mineralization occur in a foliated and saussuritized quartz diorite. Ore bodies tend to be tabular in form because foliation exerts a major control on localizing mineralization. A generalized geologic map of the Gibralter-Pollyanna area is shown in Fig. 2. Mineralization was first identified in 1917 in the Pollyanna area. Several shallow pits were sunk on flashy, but low grade, lenticular quartz veins. Duval Corp. made the initial commercial discovery, the Pollyanna ore body, on what were then called the Pollyanna claims. These claims, staked by R.C. Glen and C. Gennis in 1963, were the first to be optioned by Duval in British Columbia in October 1964. Placer Development joined Duval in late 1966 as a 50% joint venture partner, and after optioning the adjoining Gibralter claims, proceeded to evaluate and develop the four ore bodies that make up the Gibralter deposit. The Gibralter claims south of the Pollyanna claims provided the name for the Gibralter deposit.

Jan 1, 1991

By Samuel Rigert, Marco Bettelini

"INTRODUCTION AND OBJECTIVES Long rail tunnels require in most cases powerful mechanical ventilations. Besides requirements related to normal operation and maintenance, operational safety always requires a high level of smoke management. Identifying the optimum ventilation concept is essential for achieving proper performance and safety while keeping investment and operational cost at a reasonable level. For the purpose of the present paper, long tunnels have a length of typically 20 km or more. This is related to the European classification of trains (TSI 1303/2014), where the maximum distance from the portals to a firefighting point and between firefighting points is limited to 20 km (only category B passenger rolling stock allowed) or 5 km (general case). From TSI 1303/2014 it can be concluded, that tunnels over 20 km require in any case emergency stations with complex mechanical ventilations. Based on the experience arising from a number of recent projects in the European area, including in particular Gotthard (GBT), Lötschberg, Lyon-Tourin (LTF), Brenner (BBT) and Gibraltar, safety-relevant issues related to the ventilation of long railways tunnels are reviewed in this paper. Amberg Engineering is directly involved in these challenging design tasks and can provide first-hand experience and know-how. As a particular highlight, special attention is devoted to the longest tunnel worldwide, the 57 km long Gotthard Base Tunnel, which will be commissioned in 2016. THE GOTTHARD BASE TUNNEL Overview The Gotthard Base Tunnel will be commissioned in 2016 (official inauguration on the 1st of June and beginning of regular operation on the 11th of December) and will be the worldwide longest tunnel. Its complex and powerful ventilation system is very representative for many other long tunnels and is used as reference in this paper. Therefore, a few key characteristics of the Gotthard Base Tunnel and its ventilation system will be described in some detail in this initial chapter. The Gotthard Base Tunnel (GBT) consists of two single-track tunnel tubes with connecting galleries every 312 meters. Two so-called multi-functional stations (MFS), located at roughly 1/3 and 2/3 of the tunnel length, host the key equipment for normal and for emergency operation. At these locations, double crossovers allow trains to switch from one tunnel tube to the other. An emergency station is located in each multifunctional station, allowing trains to stop in case of emergency. The general layout of the GBT is presented in Figure 1."

Jan 1, 2016

By R. Frank Chiappetta

A new blasting technique has been developed by International Technologies, LLC. to eliminate subgrade drilling, lower ground vibrations, improve fragmentation and reduce explosive consumption. The new technique utilizes a uniquely designed borehole plug, with a bottom hole air deck and a predetermined stemming mass on top of the plug. This combination is referred to as the Power Deck?. Single holes and full scale tests were conducted by Blasting Analysis International, Inc. (BAI) to determine how the system works, the mechanisms behind its success and the best design parameters to use for the given rock conditions. Results have shown reduced or eliminated subgrade drilling, ground vibration reductions of up to 33%, reduced explosive consumption by 16 to 25%, and improved fragmentation by up to 25%. This paper summarizes the methodology, field test setups, analyzes procedures and results for one series of single hole and full-scale tests which were performed in a Pennsylvania, USA quarry.

Jan 1, 2004

With commodity prices rising again and market conditions stabilizing, the Metals Economics Group (MEG) found that most mining companies increased their exploration budgets in 2010. In the groups 21st edition of the Corporate Exploration Strategies (CES), MEG found a 44-percent rise in the estimated worldwide exploration total for 2010. MEG found that the estimated total 2010 budget for nonferrous metals exploration reached $12.1 billion, reinstating almost two-thirds of the industry?s $6 billion in cuts to exploration in 2009. Nonferrous exploration refers to expenditures related to precious and base metals, diamonds, uranium and some industrial minerals; it excludes iron ore, aluminum, coal, and oil and gas. In 2008, exploration budgets were at an all-time high of $14.4 billion. This capped a six-year run in which budgets rose. In 2009, nonferrous exploration budgets dropped 42 percent in 2009 as the global economic crisis and declining prices for almost all commodities took their toll on the industry. Metals prices - the primary driver of exploration spending - have improved markedly since bottoming in early 2009, and have traded well above their long-term trends throughout 2010. In response, major, intermediate and junior companies have all increased their aggregate exploration allocations in 2010. In particular, the significant improvement in the availability of equity financings for the juniors over the past 12 to 18 months has allowed this group to account for the largest share of the overall increase in exploration spending this year.

Jan 1, 2011

By N. Arbiter

The theoretical analysis of tumbling mill energetics and performance has largely neglected mill dimensionality, and, in particular, the importance of the length/diameter ratio. This is in spite of the fact that practice varies substantially in this area: geographically, for semi-autogenous and autogenous mills, as between North America and South Africa/Scandinavia; historically, for overflow ball mills, for which the L/D ratio has increased significantly from the earliest small mills to/the largest mills currently. The present study is concerned primarily with the influence of the L/D ratio on the design and operation of overflow ball mills; on the occurrence of the overload phenomenon; and on the limits, if any, it may impose on mill capacities because of critical pulp axial velocity limits. It will be shown that the shape face or is of major importance in this area; and that its adjustment to the extent that this is practical should remove the diameter limitations previously postulated for this mill type.

Jan 1, 1990

As the question of zino recovery from lead blast furnace slags has lately become such an important subject with lead metallurgists, the following description of some of the work carried out in this oonnection by the Sulphide Corporation, at CockleCreek, should prove of interest to those concerned. Early in the life of the works it was realised by the metallurgical staff that a very wide field for investigation lay before them. At the head of these was the late Mr. F. H. Evans, and it was due to his work and suggestions that the question has grown from a mere hypothesis to a commercial undertaking, in so far as these works are concerned. A great deal of the early work was carried out in the form of small laboratory expe!iments, those giving the best results being ear-marked for subsequent trial on a larger scale. One of the main obstacles in the way of research was the lack of any data or information of similar work done in other...

Jan 1, 1920

By R. M. Hardgrove

PULVERIZED coal was first used for firing cement kilns about 45 years ago, with such success that it has continued in general use. Based on cost, pulverized coal is usually the most economical fuel. In some localities natural gas or oil is cheaper, but 85.5 per cent of all cement kilns at present are fired with pulverized coal. The pulverized-coal flame is well suited to kiln conditions. Its soft, luminous nature gives it a high radiating property and the length of the flame can be readily varied to suit conditions in a kiln of any length. Ash and slag cause most of the difficulties incident to the burning of coal. In a cement kiln, however, the ash, being similar in composition to the raw mix and being deposited uniformly in the mix and clinker, occasions no difficulty as long as it remains constant in quality and quantity. Until 6 years ago almost all cement kilns using pulverized coal employed the bin system. The coal was dried and pulverized in a separate plant and delivered into a bin at the kiln. Thus the bin system requires driers, storage-type pulverizers, conveying systems, individual kiln bins, pulverized-coal feeders and primary air fans. The direct-fired system requires only a pulverizer and a blower. Fig. I shows typical plants. The first installations of direct-fired pulverizers were of the impact type but fineness of pulverization was both inadequate and variable. About 1927 a few direct-fired installations employing tube-type pulverizers were made, which were much more satisfactory. As more efficient pulverizers were developed from 1934 on, equipment for direct firing was installed at a large number of plants, until now 196 of about 900 kilns in use in the United States are direct-fired. Most of these replaced antiquated bin systems. PROCESS OF BURNING CEMENT CLINKERS The process of burning cement clinkers is fundamentally one of heat transfer. In boilers and other heat-exchange apparatus the area of the surface receiving heat from the gases is the best unit for comparing output. This seems to be equally true for kilns. The inside kiln surface is the heat-receiving surface and its area is used as the unit of kiln size in the following comparisons. Heat input is based on British thermal units in the fuel. E. G. Bailey,1 in his work on boiler-furnace heat absorption, has used the unit "B.t.u. available." This is the practical calorific power of the fuel, plus the heat in the air used for combustion. In other words, it is the heat available for useful work in the furnace or kiln. The unit of kiln output is barrels per hour. The composition of the raw mix, the percentage of water in the slurry of wet plants and hardness of burning all affect the output. These conditions, however, are hard to evaluate and probably have less effect on the output than irregularities of raw feed and clinker discharge and inexpert control of combustion. WET VS. DRY PLANTS The study presented here covers 88 plants, of which 41 are wet and 47 dry. Of

Jan 1, 1941

By G. B. Gould

EVERY mathematical statement of a measure of anything (as distin-guished from a count) is followed by a qualification always implied if not explicity stated--that the statement is only an estimate, which may vary from absolute accuracy within certain limits, according to the accu-racy of the measuring instrument. This basic fact, so obvious to engineers, is not so well understood by many that make use of laboratory coal tests. The tolerances that must be allowed in measurements of coal quality are very important in both their commercial and engineering applica-tions-and the significance of these tolerances depends upon the use made of the laboratory coal test. Only in recent years has there been any intensive study of this ques-tion of tolerances as applied to measurements of coal quality. There is very little in our published literature on the subject, and what has been published is not, readily comprehended by those who sell coal, or buy coal and use it, unless they happen to have made a study of the subject them-selves. There is great need for more widespread understanding of what has been discovered and how it applies to the use of laboratory coal tests. What follows is an attempt to condense into a few pages the results of the major investigations so far reported, and to explain their meaning in simple nontechnical language, with the addition of some recent illustrative experiments.

Jan 1, 1937