Search Documents

By John Conley

THE production of lime by the burning or calcination of limestone, including all varieties from true dolomites and magnesian limestones to high-calcium types, continues as one of the essential basic industries. In 1937, a total of 4,124,165 tons of lime valued at approximately $30,091,000 was produced in the United States.1 The importance of any contribution to our knowledge on the mechanism of the lime-burning process is, therefore, obvious. The burning of limestone has been practiced since the earliest days of our civilization, and the literature on the various phases of the industry is voluminous. Calcination of the various types of limestone has been studied by many previous investigators, but some points require addi-tional research. Each occurrence of limestone provides an opportunity for specific investigation, because the characteristics of stones in different localities vary. Knibbs13 has given an excellent discussion of available data on the theory of lime and magnesia burning. The thermal dissociation of calcium carbonate has been studied more recently by Johnston,2 Smyth and Adams,3 Ralston et al.,4 Furnas,5 Potapenko,6 and Southard and Royster.7 As a result of these investigations the dissociation temperature at atmospheric pressure has been established as 894° to 898° C. The dissociation of dolomite and magnesite, although studied by several investigators, 4,6,8 still requires clarification by additional data. The calcination of limestone was studied for a twofold purpose: (1) to extend our information on the mechanism of the lime-burning process and (2) to standardize the conditions for calcination of high-calcium and dolomitic limestones for subsequent hydration tests on the lime.

Jan 1, 1939

The Committee on Papers and Publications has set June 1, 1919, as the closing date for the receipt of manuscripts intended for the Chicago meeting, which is to be held in September, 1919. Manuscripts must be received by the Secretary on or before this date. If they are sent through members of the technical committees they must be sent to those committees long enough in advance to be forwarded and in the hands of the Secretary by the time specified.

Jan 4, 1919

By Marshall Pease, R. J. Brandon

A UTILITY that has a large consumption of coal must insure an adequate and sound supply of fuel. The Detroit Edison Co., which has an annual coal consumption of about four million tons and spends approximately $32 million a year for coal, including freight charges, has developed a program for fuel procurement and for evaluation and selection of fuel for reliable and efficient plant operation. Fuel Procurement Coal Purchasing Division: The Fuel Supply Div. of the Purchasing Dept. combines all of the procurement functions in one group, which must maintain adequate stocks of fuel. In addition to its usual purchasing duties, the division also governs transportation, follow-up, invoice and freight bill, in cooperation with the Accounting Dept. The Fuel Div. is comprised of the fuel agent, an assistant fuel agent, a coal buyer and five coal clerks, who follow the movement of each car, initially approve freight bills and invoices, and file claims whenever there is a shortage of one ton or more. The fuel agent reports directly to the purchasing agent of the Company, and all major programs are planned jointly with the chief purchasing officer. The apparent individuality of the fuel section is necessary because of the tremendous volume of coal cars handled each day, sometimes as many as 500, which must be handled promptly to complete the fastest possible move from the mines to the plants. Determining Annual Coal Volume: Through the combined studies of a Production Dept. Load Committee and the Controller's office, accurate predictions of coal requirements for any given year are provided the Fuel Dept. from 12 to 15 months in advance. This is divided into the requirements of all individual power plants and central heating plants. This in turn determines the quantity and quality for plants whose specific fuels vary with the type of equipment installed. In the Detroit area, which has a high industrial load, early estimates of annual coal consumption usually are resolved at the end of the year within 4 or 5 pct of the original plan. Operating in a highly developed industrial area eases the task of estimating primary output; and, with the residential demands increasing in a steady and fairly well-defined pattern, the overall coal schedules are not subject to radical changes during any given year. Selecting Suppliers: At any time, but especially during or before an emergency, the coal supply factor must be made secure. This is particularly true in the procurement of utility fuel. There are always extreme quantities of so-called "bargain" coal available during the buyers' markets, such as recently prevailed. These opportunistic offerings may be considered a means of averaging down overall price, rather than as a steady and dependable supply source. Coal is purchased on contract from mine operators and sales agents who have proved reliable. They are not opportunists who desert for higher dollars in times of duress; they do not fail to fulfill contracts when markets rise or overship when markets dip. The progressive operator today who is willing to expend capital to improve quality and service deserves much more consideration than a matching of short-term pennies. When a company has a high volume of annual needs, all phases of the mine supply must be considered. The mine must be able to produce the quality required at a fair price and be able to sell oversizes of coal in enough volume to screen sufficient nut and slack. It must crush coal and sell mine run at prices in line with competitive nut and slack and be willing to do so when there is no demand for prepared sizes. Determining Price: The public utility is in direct competition with any of its customers who can, if savings are guaranteed, generate their own power. Today, to a greater extent than ever before, private industry must do a better overall job than Government-controlled operations. The price of coal must be realistically balanced with the price paid by almost all industries and the railroads as well. The supply-demand ratio in coal is not difficult to discern. There is access at all times to Govern-

Jan 1, 1952

By E. J. Wasp, T. C. Aude, F. B. Raymer

Abstract-The following paper deals with technical aspects of terminal facilities for western coal pipelines. The information is taken from the Ohio and Black Mesa pipelines and the proposed one in Wyoming. This paper first discusses the feed terminal, the product that it must produce, and the reasons for coal cleaning. Then, in the delivery terminal section, the various methods of dewatering the coal and some recent innovative ideas on bunkering the dewatered product and storing the dewatered coal in large outdoor piles are discussed.

Jan 2, 1978

By F. V. Tideswell

THE suggestion, which appears to find increasing favor, that the elementary composition of coals should be used as the basis of their classification, makes it important that our methods of expressing this elementary composition should be refined. It is doubtful whether many published ultimate analyses of coals are accurate within 1 per cent. carbon. Many are probably as much as 3 or 2 per cent. in error in carbon. It is, perhaps, not always realized that the extreme variation in carbon content over the range of bituminous coals is but 16 per cent. An error of 1 per cent. in carbon on analysis corresponds therefore with one-sixteenth of the whole range, an amount which is unjustifiable even for the application to commercial needs of a system of classification based on ultimate analysis. For the purposes of scientific research such limited accuracy is of little value. The object of this paper is to examine one important source of error in ultimate analysis, that due to the occurrence in coal of inorganic material, and to emphasize the need for the quantitative measurements (of carbon more particularly) on coals to be rendered independent of their contents of such material.

Jan 1, 1928

By Nelson Severinghaus

Consolidated Quarries Corp. must conduct operations for an average sales price of $1.25 per ton, about the same price at which stone was sold 25 years ago when the dollar was worth twice what it is now. To maintain success in a competitive business, the company must solve the usual production problems, which will be discussed here in the order they occur in the flowsheet. Most crushed stone quarries must first remove soil and decomposed rock. Although seasons of lower sales sometimes release regular quarry excavating and haulage equipment for this purpose, overburden is often too extensive for this method to be used. In such cases, special equipment must be assigned or the job may be contracted. As many earthmoving contractors have heavy duty specialized equipment well suited to overburden removal, they should be seriously considered before the job is undertaken. Pockets of clay beneath peaks of hard stone sometimes defy mechanized removal. Pick and shovel laborers at this point might be supplanted by more ingenious use of pumps and water or some other mechanical means. Where overburden is extremely heavy or difficult to remove, underground mining must be considered.

Mar 1, 1956

By Hugh Tiemann

(San Francisco Meeting, September, 1915) THE desirability of employing the centigrade scale for the measurement of temperatures is becoming more and more recognized in this country, particularly in view of the fact that this scale is used almost exclusively in technical papers and publications-exclusively in those published in French or German. There are, however, a large number of factories and laboratories which still employ the Fahrenheit scale. It therefore frequently becomes necessary to convert one into the other and the accompanying chart (Fig. 1) has been found very convenient for this purpose.

Jan 6, 1915

By Charles R. Isaacs

In 1972 Kennecott Explorations, Inc. conducted a three month cruise to the central Pacific as part of a study of deep-ocean manganese nodules. One of the objectives of the voyage was to collect at least 200 tons of nodules for use in extractive metallurgy research and various engineering tests. It was determined to cut off production at a maximum of 200 tons, should we reach that amount before the end of the 38 on-station days. We were able to reach that goal; 200 tons of nodules were collected, representing an average return of 2340 lb from 171 dredge runs. Once equipment and techniques were refined, normal returns consistently exceeded 2 tons per haul. Up to this time, Kennecott had sampled extensively with the use of small free-fall devices using wire rope and winch equipment. These devices have never offered a viable method for collecting nodules in bulk, and we sought to develop a dredging capability which would give some assurance of meeting future requirements with efficiency and economy. After testing a series of increasingly complex dredge designs at sea, it was decided to utilize two of the simpler configurations, which after modification provided the basic design for the dredge used.

Jan 4, 1974

By Dennis V. D’Andrea, Robert C. Steckley, William C. Larson, Richard A. Dick

A fragmentation experiment was performed in cooperation with Duval Corporation in a porphyry copper molybdenum deposit near the Sierrita pit south of Tucson, Ariz. A 10-hole test blast was detonated to establish relationships between blasthole spacing and the resulting fragmentation. Blastholes were 9 in. in diameter and 110 ft deep. The 10 blastholes contained a total of 17,400 lb of aluminized slurry blasting agent in 50-ft columns with 60 ft of stemming. Blasthole spacings of 25, 20, and 15 ft were tested. Diamond drill core examination was the primary method used to determine the condition of the rock before and after blasting. Topographic surveys were used to measure the rock swell produced by the blast and a fragment size distribution was obtained for the rubblized material on the surface. The rubble zone at the surface was ideal for in situ leaching. Fragmentation to depths of 110 ft was excellent from the 15- to 20-ft blasthole spacing patterns. Good breakage was also produced by the 25-ft pattern although the effects of the blast were not as obvious. In situ leaching tests were not conducted. However, based on size consideration only, all three blasting patterns produced adequate breakage for successful leaching.

Jan 1, 1974

By Richard E. Chism

The dry methods of assaying mercury-ores and other combinations of mercury all rest upon the volatility of this metal as a beginning. After the separation of the mercury in the form of vapor from the matrix upon which the assay is performed, the mercurial vapors are either condensed upon cold surfaces or received upon a gold plate into which the mercury is absorbed.

Jan 1, 1899

By Joseph F. Shirley, Harry K. Burke

On January 9, 1964, the molybdenite extraction circuit at the San Manuel concentrator was switched from the sodium hypochlorite-ferracyanide process to the present process described in this paper. This moment was the culmination of over three years of laboratory and pilot plant test work. COPPER CONCENTRATOR Even though San Manuel's molybdenite plant begins with the thickened copper concentrates, it is necessary to describe briefly the copper sulfide circuit, because San Manuel's excellent molybdenite recovery actually begins with the primary grinding of the ore.

Jan 3, 1965

By H. M. Chance

WITHIN the last 10 years the subject of mine taxation in its relation to coal-mining interests has come to have growing importance, not only to those engaged in the mining of coal, but also to the owners of land underlain by coal. A disposition has developed among legislators to accept the principle, which has been laid down y many judicial decisions, that coal underlying the surface must be regarded as a part of the real value of all properties so underlain, and as such is chargeable with such burdens of taxation as the necessities of the government may impose. These necessities arise from the normal expense of maintaining State and local governments, and in the past have been met principally by, taxes based upon assessments of real estate values, which values in many cases have been confined principally or wholly to the value of the surface, without taking into consideration the value of minerals underlying the surface. It is not proposed here to deal with the question of Federal taxation, whether levied on production, or on products transported from one State to another, or exported from the country, or upon thegross or net earnings of corporations engaged in interstate commerce, or upon the production of materials which may be transported from one State to another, or levied. upon the profits or upon the obligations of corporations. The present discussion will be confined to the appraisal of coal lands as assessed for State, county, township, or borough taxation. The methods heretofore and at present in use in the different States vary widely and have resulted in more or less litigation. Discussions appearing from time to time in the technical and trade journals and in the proceedings of mining and engineering associations frequently direct attention to the need for the adoption of fixed principle in levying taxes, and of uniform methods for applying such principles, but there does not seem to be a general demand from the public for the adoption of such methods.

Jan 7, 1914

By Richard L. Gordon

Minerals long have been important commodities in international trade. As an inevitable result, the governments of the world have employed a wide variety of programs that affect the flow of trade. Roughly speaking, we may distinguish between the desire of more developed countries (MDCs) like the United States, western Europe, and Japan to control imports of minerals and the concern of less developed countries (LDCs), like India, about exploiting and exporting their minerals. The terminology used to describe different countries and the classification of specific countries into groups is unsettled and often changing. The poorest countries have been characterized as backward, undeveloped, underdeveloped, and developing. The problem seems to be in selecting a term that is both accurate and polite. Less developed seems, for reasons outlined by Hagen [pp. 51-57], the most convenient term. The borderline between an LDC and an MDC is always open to dispute. Objective measures are difficult to develop because of deficiencies in basic data, and enormous conceptual problems arise in making valid comparisons from even good data [see Hagen, pp. 7-28]. Thus, policies of the MDCs can be evaluated chiefly by using a few basic arguments for protectionist attitudes towards international trade. In dealing with the LDCs, a more far-ranging evaluation that covers general economic policy goals, the role of foreign investment, and the indirect effects of trade is required. This duality breaks down when trying to deal with the depressed areas in an MDC; here the issues are more akin to those associated with problems in an LDC. Similarly, variants of arguments used in LDCs appear in debates about foreign investments in MDCs. The whole discussion of minerals in LDCs, moreover, has obvious implications for MDCs like Canada and Australia. They, too, must face problems about the best utilization of their resources. THE RESTRICTION OF MINERAL TRADE BY DEVELOPED COUNTRIES[a] At least to some extent, the world's leading industrial nations have intervened to control the inflow of minerals. Such regulation is particularly pronounced for energy. Both the United States and western Europe employ

Jan 1, 1976

By William D. Schwab

In the technical literature of 1965 and 1966, there were several papers about future power for mining and construction equipment. Most of these papers made the same predictions: •More power •Better reliability and durability •Ease of service and maintenance •Operating economy •The possibility of future environmental concern •The entrance of the gas turbine In the five years that have since passed, some of the 1965-66 predictions have at least partially come true, while others have not been fully realized. Actually the list still appears sound today. Priorities may have changed and details may be different, but the main points cover the requirements for future prime movers quite well.

Jan 1, 1971

By R. Hogg

The mathematical description of solids transport in mills is an important aspect of the development of comprehensive models for the analysis, simulation and control of grinding systems. The basic mechanisms of particle transport and mixing, including gravity flow, carrier fluid transport, and "diffusion", are reviewed and their relative importance in wet and dry ball mills is discussed. Specific models for transport and mixing in dry, grate-discharge and wet, overflow ball mills are described. The limitations of the models, parameter estimation problems, scale-up criteria etc. are discussed and the conditions which lead to particle size dependent transport, and hence to internal classification in the mill, are described in detail.

Jan 1, 1984

By R. P. Killmeyer, B. S. Gottfried, J. T. Wizzard

The US Department of Energy's Coal Preparation Branch has developed a computer program to calculate the performance characteristics of coal washing devices. This program uses specific gravity analyses of the clean coal and refuse streams as input, and generates dependent and independent performance criteria for the washer. Partition curves are internally represented in a functional form by a Weibull function. Comparisons are made between performance criteria calculated by hand and the performance criteria calculated by the program for 120 different dense medium cyclone tests. Results show that the computer program gives results in close agreement with hand-calculated values while greatly reducing the amount of time involved in performing the analyses.

Jan 1, 1984

By E. H. Crabtree, T. C. King

THE ferrosilicon grinding unit at the Central Mill of the Eagle-Picher Mining & Smelting Co. near Picher, Okla., was completed in March 1947. The object of the plant was to grind pigs of ferrosilicon, having a size of approximately 1 ½ by 4 by 12 in. and an analysis of 85 pct Fe and 15 pct Si, to approximately 100 mesh by crushing and wet grinding in a ball-mill classifier circuit. The minus-loo mesh ferrosilicon had formerly been purchased, and was used as medium in the heavy media process for treatment of lead-zinc ores. From the standpoint of dollars and cents, the cost of minus-100 mesh ferrosilicon was roughly $40.00 per ton more than pigs of the corresponding alloy delivered to the mill. Estimated wet grinding costs were considerably below this figure. The possible saving in cost of make-up medium for the cone plant was particularly attractive since, at that time, the plant losses averaged over four tons of minus-100 mesh ferrosilicon per day. Aside from the probable saving on the grinding charge, the need for such a unit was twofold. First, periodic fluctuations in the differential between the top and bottom densities of the cone were thought to be detrimental to metallurgy. There was little doubt that an intermediate differential existed at which the heavy media separation was most efficient, representing a compromise between concentrate grade and tailing loss. Furthermore, if a finer, but considerably cleaner, medium could be obtained, there was the possibility that the differential could be decreased without increasing the viscosity, or conversely, the viscosity of the medium decreased without increasing the differential. Preliminary to experimental work aimed at pegging the cone differential and circulating medium viscosity at whatever values were found to be most efficient, it was essential to have control over both the non-magnetic content of the medium and the particle size of the contained ferrosilicon. The latter was possible by means of a grinding unit at the mill. Second, whereas the ferrosilicon alloys are made by a number of manufacturers, only two, to our knowledge, grind it in any quantity for use in heavy media plants. For all practical purposes, the Central Mill was limited to one source of supply, a particularly vulnerable position. In case the supply was cut off, it was thought that pigs of the 85 pct Fe, 15 pct Si alloy could be obtained elsewhere, providing means of grinding them was available. There was no published information available covering wet grinding of ferrosilicon. Dry grinding in batch mills and in continuous mills with air classification was being practiced, but the cost of grinding was excessive and the dust condition objectionable. It appeared that primary and secondary crushing was no particular problem, providing heavy duty equipment was used;

Jan 1, 1947

By O. C. Ralston

THE use of copper sulfate for improving the flotation behavior of sphalerite is probably at least 15 years old. The original discovery of its activating influence is somewhat obscure. The story goes that in the mill at Mascot, Tenn., its favorable action was discovered by accident, early in 1914, as follows: The original laboratory test work on a sphalerite ore gave favorable flotation results, but after a mill had been built the flotation concentration of the ore was very unsatisfactory. In diagnosing the probable reasons, one fact pointed out was that the laboratory test machine had been constructed of bronze whereas the commercial machine allowed pulp to come in contact only with wood and iron. A plate of sheet copper was hung in the flotation machine and results immediately improved. At first fanciful explanations of electrolytic and electrostatic behavior were given credence, but when the copper plate was removed and a small amount of copper sulfate substituted in the pulp an even more favorable result was obtained. Toward the end of 1914 copper sulfate was also adopted in the acid flotation circuit of the Butte and Superior Copper Co. Just who is responsible for the original discovery the present writers do not know: It seems strange that in that era of flotation litigation this discovery was not patented. While for pragmatic purposes it may be sufficient to know that the mere addition of copper compounds to a flotation pulp is sufficient to activate the flotation of the sphalerite, for scientific purposes it is quite desirable to know more about how the action takes place. It is the purpose of this paper to present certain evidence dealing with the mechanism of the beneficial effect. The description of the effect as activation in contradistinction to depression is now common in both the English and German languages. It makes no assumptions as to whether the zinc sulfide surfaces have been filmed with copper compounds. In fact, the principal differences of opinion expressed in the literature deal with whether there is an actual formation of CuS (or even Cu2S) on the surface of the sphalerite.

Jan 1, 1929

By Maurice E. Peloubet

This discussion of accounting will describe the statements and the information that the accounting system produces, from the point of view of those who use such systems rather than of those who prepare them and who do the detail and technical accounting work. In any well organized mine, quarry, or other enterprise exploiting a mineral deposit, no matter how small, some clerical and accounting work must be done. Miners and other employes must be paid, supplies must be purchased and issued, and various tax and information returns, which even the smallest enterprise must file, have to be prepared. In this chapter it is assumed that the enterprise has employes of this type and that they understand the fundamentals of record keeping and accounting. It would be impossible here to give sufficiently full explanations to enable a man with no previous clerical and accounting training to set up and operate an accounting and cost system for even the simplest extractive operation. Rather, we shall hope first, to tell the investor and the operator, from the chief engineer or president down to a subforeman, what to expect from the accounting statements and records and how to use this information in his daily work; and second, that it will enable the man with some knowledge of accounting or bookkeeping, but with little or no experience in any extractive industry, to set up and operate a satisfactory system for a mine or other extractive enterprise. For readers who wish to go further, the bibliography at the end of this chapter contains many references. The emphasis has, therefore, been placed on the statements to be produced and the purposes for which they are to be used rather than the underlying books and records. These are, with a few exceptions which will be described later, essentially what might be found in any industrial enterprise and would probably, in the extremely small enterprise, consist of handwritten journals, ledgers, analysis books, payroll books, and stores ledgers. In the larger enterprise, various types of mechanical accounting would be introduced in proportion to the complexity of the operation.

Jan 1, 1959

By Walter H. Ortel, George B. Wallace

INTRODUCTION A greater understanding is required about the factors which control tunneling operations if we are to meet the expected demand for tunnels. Much of the needed information can best be achieved by the proper use of instrumentation and advanced engineering concepts. Tunnel measurements and their analysis may prove to be the key which will give the insight necessary to understand the relationship of rock, tunnel supports, and linings. There are three main areas which can be improved through the use of tunnel instrumentation. First, and of prime importance, is safety for men and the project. When unstable conditions occur, sets become distorted. Even without measurements, it is sometimes possible to tell when trouble is approaching. In effect, the set acts as a load cell. Distortions in the set indicate reinforcements may be required to maintain stability. Additional sets or rock bolts, if they are placed soon enough, may provide this stability. However, when large rock displacements occur in short periods of time, it could be too late. Figure 1 is an example of the difficulties encountered in stopping moving rock. To stop the movement and possible failure, large props were placed above the spring line and the massive concrete gravity buttress was constructed along the legs. Rock bolts from the buttress deep into the rock were also used in an attempt to stabilize the rock mass. However, this work is for a highway tunnel and eventually these props and buttresses must be removed.

Jan 1, 1971