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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 W. V. Mutler

Present day capital costs are analyzed for a 2,000 metric tonne per day (MTPD) pyrite burning plant and compared with a sulphur burning plant of the same capacity. Power, raw material and steam production rates are then compared for the two facility types. A sensitivity analysis is conducted to highlight the impact changing sulphur, pyrite, capital and operating costs have on the relative economics of these feeds. Technological improvement effects on capital cost and energy recovery are also discussed. Besides the steam produced from the burning of pure sulphur or pyrite, plants using an advanced form of heat recovery can produce up to 10 bar steam using heat from acid formation. The quantity depends on the overall water balance which is influenced by such factors as gas strength and product acid concentration. Modern materials and innovative process design also improve the ability to increase the high pressure steam from the roaster boiler in pyrite plants above the traditional 1.25 kg of superheated steam per kg of acid produced.

Jan 1, 2009

By W. V. Mutler

Present day capital costs are analyzed for a 2,000 metric tonne per day (MTPD) pyrite burning plant and compared with a sulphur burning plant of the same capacity. Power, raw material and steam production rates are then compared for the two facility types. A sensitivity analysis is conducted to highlight the impact changing sulphur, pyrite, capital and operating costs have on the relative economics of these feeds. Technological improvement effects on capital cost and energy recovery are also discussed. Besides the steam produced from the burning of pure sulphur or pyrite, plants using an advanced form of heat recovery can produce up to 10 bar steam using heat from acid formation. The quantity depends on the overall water balance which is influenced by such factors as gas strength and product acid concentration. Modern materials and innovative process design also improve the ability to increase the high pressure steam from the roaster boiler in pyrite plants above the traditional 1.25 kg of superheated steam per kg of acid produced.

Jan 1, 2009

By W. V. Mutler

Present day capital costs are analysed for a 2 000 metric tonne per day (MTPD) pyrite burning plant and compared with a sulphur burning plant of the same capacity. Power, raw material and steam production rates are then compared for the two facility types. A sensitivity analysis is conducted to highlight the impact changing sulphur, pyrite, capital and operating costs have on the relative economics of these feeds. Technological improvement effects on capital cost and energy recovery are also discussed. Besides the steam produced from the burning of pure sulphur or pyrite, plants using an advanced form of heat recovery can produce up to 10 bar steam using heat from acid formation. The quantity depends on the overall water balance which is influenced by such factors as gas strength and product acid concentration. Modern materials and innovative process design also improve the ability to increase the high pressure steam from the roaster boiler in pyrite plants above the traditional 1.25 kg of superheated steam per kg of acid produced.

Jan 1, 2009

By Jacob Reeese

I HAVE discovered a new method by which steel and other metals may be burnished by the automatic action of the burnishing machine, and by which the cost is greatly diminished, and more perfect work produced. And in addition to the polishing and burnishing action of

Jan 1, 1881

During the four years that Burr A. Robinson has held the position of Assistant Secretary of the Institute he has not only won the regard and admiration of the Directors and his associates at headquarters because of his unselfish devotion, efficiency and painstaking application, but lie has formed a wide circle of friends among the members of the Institute. All will learn with regret that he has voluntarily severed his connection with the Institute in order to take a position with the United States Rubber Co., which offered such flattering prospects for the future that the Board of Directors, in spite of their disinclination to lose his services, did not feel justified in urging him to decline.

Jan 8, 1917

Burr Mineral Resource has: ?Grade / Thickness / Tonnage ?Dry Caprock ?Low Carnallite ?Low Clay / Insolubles ?Flat & Continuous Deposit ?Proper depth

May 1, 2009

By Wilfrid Comeau

Vibrograms, which last significantly longer than the actual blast (say 10 to 15 cycles or more), may be signalling an elastic response, which is not uniquely blast related. For example, geophones mounted on a part of a structure, which can elastically resonate at a frequency included in the seismogram, may not show the structure’s real reaction to the blast. This resonance usually amplifies the ground vibration. This contribution examines one particular case where blasting excited and amplified a resonant ground response, and the method used to significantly reduce or eliminate this undesirable condition.

Jan 1, 2007

How do you think the US Bureau of Mines closing will affect SME? The demise of the bureau represents a challenge, an opportunity and, above all, new responsibilities for our profession. A lot of good professionals are seeking new positions. A lot of worthwhile research is available for transfer to the private sector. Logic dictates that worthwhile projects of any defunded government activities should find support in the private sector. The bureau may be gone but its legacy is deeply rooted in the profession. The bureau’s contributions will be remembered as long as there are mines and miners. Its1994 research program was divided into three major areas: environ-mental technology; health, safety and mining technology; and minerals and materials science. There must be a place in either the government or private sector to continue these worthwhile activities.

Jan 1, 1996

By Hanes J

More than 200 bursts in coal occurred at Leichhardt Colliery prior to December 1978 during mine development in the 6 m thick Gemini seam at depths approximating 400 m. Three large bursts each displaced more than 300 tonnes of coal and stone. Two of these which occurred in continuous miner developments, are described and compared. Geological settings, mining strains including induced cleavage and roof failures associated with bursts are described. A shotfiring technique replaced mechanised mining following a major incident at the colliery. Present mining procedures, the apparent improvement in stability of workings and ongoing geotechnical monitoring programme are discussed.

Jan 1, 1980

By B. Cavender

Safety departments have traditionally been held responsible for the safety performance of their division or company. This approach leads to a lack of ownership of safety issues by the larger organization. An alternative paradigm is significantly more effective: the members of the work force (managers as well as workers) are fully responsible and accountable for safe production. The safety department is not extinct, however. Its role has changed, to focus on training, litigation, and external relationships such as community relations. This approach was implemented at BHP Copper's Superior mine and mill in Arizona. By obtaining the genuine commitment of the work force to accident-free production, the mill's MSHA incident rate immediately dropped from 7.4 to zero. The mill also ran one year with no MSHA citations. When this philosophy was implemented at the divisional level, the division's incident rate decreased from 9.5 to 1.1,an 88-percent reduction in six months.

Jan 1, 2000

By D. P. Ziegler

Formulas relating economic optimum busbar cross sectional areas to busbar cost, electric price and financial parameters are reviewed and revised. Application of the formulas is illustrated with discussion of the appropriate choice of parameter values and the sensitivity of the optimum to the parameters. The extension of the single busbar concept to optimization of more complicated arrangements of bus for smelting pots is complicated by the constraint of obtaining a specified current distribution. An example problem illustrates the optimization of a section of a bus network containing a fork, with the imposed limitation of achieving a specified uniformity in the current. In cases where the current in the individual conductors may vary, Kelvin's law does not apply. Further extension of the technique to a full pot set of conductors poses additional problems which are discussed, but whose solution has not yet been accomplished. Aluminium 2006 45th Annual Conference of Metallurgists ofCIM Montreal, Quebec, Canada Edited by

Jan 1, 2006

By Rodrigo Werneck Athouguia

O cerne desse trabalho consiste em demonstrar os resultados obtidos pela implementação de um programa de Lubrificação Confiável na Samarco Ubú com objetivo de reduzir custos através da busca contínua pela lubrificação classe mundial. A Samarco Ubú entende que uma lubrificação de qualidade contribui diretamente para os equipamentos, aumentando a vida útil. A gerência de manutenção lançou no final de 2013 um programa de Lubrificação Confiável com objetivo de buscar continuamente as melhores práticas de lubrificação no mundo.Esse programa abrange desde o recebimento do lubrificante até a manutenção do mesmo no equipamento em condições ótimas de trabalho, capacitação da equipe e as melhores práticas de lubrificação.

Aug 16, 2017

By Corale L. Brierley

The depressed economic condition resulting from normal cyclic behavior, a more fundamental structural alteration, or both, is a mandate for change within the mining industry. Although several strategies for change have been proposed, the option of applying high technology processes to this smokestack industry offers the greatest opportunity for regaining global competitiveness and a new vitality. Research and development to secure new technologies require a corporate commitment for substantive change, a tech¬nologically enlightened management, a well¬funded and stable science and engineering effort, and a dedicated and motivated technical team--features in short supply in the mining industry today. However, an alternative to in-house development of frontier technologies is available to this beleagured industry through entrepreneurial, high-tech companies. These entities, with their dedicated focus toward product development, motivated and streamlined teams, high productivity and efficiency, and low costs offer a unique opportunity for large corporations to obtain high-tech products and services. These commodities are available through traditional commercial channels and an array of creative business arrangements. The latter offers notable benefits to large companies including windows on frontier technologies and mitigation of risk. Likewise, entrepreneurial companies profit through manufacturing and marketing relationships and an expanded financial base.

Jan 1, 1985

By Doug Halbe

?Many are called, but few are chosen.? The biblical adage applies not only to life, but also to hydrometallurgical processes. There have been, in the past, many outstanding successes with new processes ? and also some dismal failures. What are the odds of success for a new process? When there have been problems, why? What can you do to make sure these problems don?t occur with your process? What effect will a slow startup have on project economics? How do financial institutions ? the people who loan your company money for the project ? feel about new processes and why? Is it possible to predict or estimate the time required to reach design parameters?and if so, how do you sell this estimate to management ? and financial institutions? Probably most important ? when do you start thinking about the answers to these questions?

Jan 1, 2003

By G. A. Johnson

Basic management principles will be discussed (as they apply to minerals education efforts), especially in light of the changing nature of volunteerism in today’s society. Also, the “minerals education tree” will be presented, along with public opinion / public policy realities.

Jan 1, 2001

By Jason N. Scott

CFA piling is a ?blind? construction process that relies heavily on the rig instrumentation to produce sound piles. If the data measured and recorded during construction can be made available to engineers and managers within hours after construction then there are many economic and quality control benefits that can be realised. A state of the art CFA instrumentation and data management process has been developed in the UK. The key components of the instrumentation, GSM data service and the central database are described. Many benefits to the business have been realised and, where possible, these are quantified.

Jan 1, 2006

By Thomas D. Kaufmann

Introduction Mining has always been sensitive to the fluctuating income of downstream customer industries. The industry is now becoming more vulnerable to booms and busts as economic pulsations increase and demand for mining products shows little or no long-term growth. As the general economy has become more cyclical in the last decade, the capital-intensive primary industries have become more aware that timing as well as preparation of survival plans are vital in investment decisions. Strangely, however, some of us have not yet included the business cycle in our feasibility studies. Cyclic prices and volumes and fluctuations in profits and cash flows do not fit our linear models. The increased cyclical nature of our economy is recent and poorly understood. Forecasting peaks and troughs is still more an art than a science. Nevertheless, avoiding business cycle parameters can lead to error in value estimation and contingency planning of new projects. Metal and Mineral Industries More than half the iron and steel, aluminum, copper, lead, zinc, manganese, tin, nickel, molybdenum, cobalt, and chrome that we mine, smelt, upgrade, and recycle goes to construction, transportation, capital goods, and consumer durable industries. All are cyclical. Their products are consumed slowly, so replacement can be postponed in recessions. Purchases of such goods are usually financed by debt, and their customers are sensitive to highly cyclical changes in interest rates. During prosperous periods, people tend to buy capital goods despite high interest rates. Upstream industries also tend to be whipsawed by inventory cycles. With high interest rates and good transportation, downstream fabricators can lighten their inventories during recessions. They know that upstream suppliers can deliver supplies and raw materials immediately, And, with the advent of electronic accounting, the fabricator with timely inventory information can afford to hold fewer contingency stocks. Likewise, when recovery returns, inventories surge back through industry pipelines, accelerating demands on primary supplies. The price elasticity of most primary products is low. Their share of the value of finished products of the industries they supply is generally small. The 60 kg (130 lb) of aluminum in a car is vital. But whether it costs $80 or $130 will not visibly influence the demand for an automobile. With low elasticities of demand, the primary producer is hit with decreases (or increases) in prices and in sales volume, during recessions as well as recoveries.

Jan 6, 1984

By M. C. Roberts

The consumption of industrial minerals, like most other commodities produced from the earth, depends on the demand for the goods and services that use these materials. Minerals are not generally used directly by final consumers (table salt is a notable exception) but instead are used to either make products that are then purchased by customers, or the minerals are used to make industrial products that eventually contribute towards producing other goods and services. Therefore the demand for industrial minerals in most uses is derived from the ultimate demand for goods and services by consumers. The problem for producers of industrial minerals is that the demand for their mineral product fluctuates greatly in response to the changes in the production of goods and services over the course of the business cycle. In this respect, the producers of industrial mineral are innocent victims, subject to market fluctuations outside of their control. Because the demand for most minerals depends on the demand for the product and because minerals typically make up a minor portion of the costs of producing the product, changes in the price of the mineral often do not influence demand for it to a significant degree in the short run. This is described as a very low price elasticity of demand, as shown by the steep slope of the hypothetical demand curve in Figure 1. This demand curve shows that changing the price of the mineral does not alter the quantity demanded very much, but shifts in the demand curve will be the important determinant of the quantity of the mine.ra1 that is sold. The shifts are caused by the changing demand for the products using the mineral over the course of the business cycle.

Jan 1, 1994

By F. Alsobrook

Industrial minerals are receiving increased attention by metals, coal and other companies seeking to diversify and stabilize earnings. Each industrial mineral has a unique set (and sub-sets) of business dynamics, however, and the diversity can present a bewildering maze to the corporate planner. Shrugging off this complexity and relying on serendipity for entry opportunities often results in unsuitable acquisitions. An effective alternative used in exploration can also be applied to strategic planning. By providing focus and direction, this flexible methodology can prevent wasting corporate resources on random pursuits and result in a quicker, more satisfactory achievement of diversification goals.

Jan 1, 1990