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By Peter I. Brooker

Elementary estimation methods in which blocks are assigned values according to a geometrical area of influence concept are investigated for a tabular deposit. This quantitative assessment of the estimation technique is made using Matheron's geostatistics which allows the variance of the error between actual block values and estimated values to be found once the semi-variogram is known. For the deposit in question it is shown that the elementary technique makes poor use of the available information. There is a 20% relative error associated with it, whereas by using the optimal technique of kriging this can be reduced to 9%. An infill drilling program, which might have been suggested on area of influence results, would reduce the estimation variance only marginally over that of the current campaign; the relative error being lowered to 6%. Thus the geostatistical analysis shows this would be an unnecessary expense. The accuracy of an earlier drilling stage is also studied and it is shown that with the information available at the earlier stage block values could have been known with a relative error of 13%. Drilling could have stopped then if this were reckoned a tolerable error level. These results are all obtained for blocks whose size is dictated by the mining engineer and is set at the current grid size. In the area of influence approach smaller blocks are considered as the grid becomes finer and a study of the accuracy of area of influence estimates and kriged estimates for differing block sizes is presented. Between drilling stages more information from which the semi- variogram is calculated becomes available. The sensitivity of the estimation to changes in the semi-variogram parameters between earlier and current drilling programs is investigated.

Jan 1, 1977

By Julien Deby

THE sinking of a deep shaft is always a serious undertaking, especially when the strata to be traversed are of great hardness, or when they are feebly coherent or highly saturated with water. In the, first case, that of solid rock, modern appliances, such as the rock-drill, put into motion by air-compressors, along with suitable explosives, will generally answer the purposes of the mining engineer until he has reached the main water-levels. When these have

Jan 1, 1877

By Julien Deby

The sinking of a deep shaft is always a serious undertaking, especially when the strata to be traversed are of great hardness, or when they are feebly coherent or highly saturated with water. In the. first case, that of solid rock, modern appliances, such as the rock-drill, put into motion by air-compressors, along with suitable explosives, will generally answer the purposes of the mining engineer until he has reached the main water-levels. When these have

HeRbert A. MeGRaw, San Luis de la Paz, Guanajuato, Mex. (communication to the Secretary*) :—Although Mr. Bordeaux prefaces his paper with the statement-that it is a general outline of practice in the Republic, many of his statements seem to be made from the view-point of a particular case, which does not always agree with general practice. For the purpose of calling attention to some of these variations, I respectfully offer the following comments: The operation of crushing and grinding is performed by so many different methods and systems that it is useless to select any one as the standard. However, primary crushing in rock-breakers followed by stamps is thus far so general that it might be so classified. Whether or not it is the best way, is open to question. Regrinding may be performed by any of the various types of Chilean mills, Huntington mills, or similar machines, or the material may be taken directly from the stamps and delivered to the tube-mills. Mr. Bordeaux's statement that " the slimes can be treated only by decantation; the new Butters slime-filter, as used in Nevada, does not seem to be successful with silver-ores," is surely an error. All over Mexico many of the purely silver-ores are being successfully handled by the Butters or similar filters, such as the Moore and the Burt filters, and a letter to the manufacturers of these filters will undoubtedly bring a list of the silver-ores now being successfully treated in this way. The statement that crushing silver-ores in solution is impossible is equally erroneous. Most modern mills crush the ore in solution, in some cases containing as much as 0.12 per cent, of KCN. I cannot for the moment recall any modern mill in Mexico which does not follow this practice. There may be some reason for it in particular instances, but, generally speaking, the practice is to crush in solution. Care in installation avoids any mechanical loss of cyanide, and the chemical loss is so small as to be negligible.

Jan 1, 1910

By M. C. Fuerstenau

Enrollment in the mineral engineering departments at many of our universities has decreased substantially over the past few years, a fact that is due to a number of reasons. Some of the more obvious reasons are: (l) lack of student stimulation in the classroom, (2) absence or lack of salesmanship by the mineral industry faculty, (3) minimal financial support of academic programs by industry (some companies have been very generous, while others have given nothing), (4) failure of some companies to utilize the engineering backgrounds of personnel, (5) salary in some instances, and (6) job location in some in- stances. As some of these problems have been recognized, appropriate steps have been taken to correct them. Only one of the reasons listed is not subject to change, and that is job location. One university' that found itself in the position of reduced enrollment in the mineral industries is the University of Utah. Since the author was in the Department of Metallurgical Engineering at that university, and since data on enrollment and scholarship support have been published by that department, that department will be used for illustrative purposes to show the effect that active scholarship incentive can have on undergraduate enrollment. As Fig. I shows, there were approximately 35 total undergraduates in the department in 1966. Extrapolation of the freshman line from 1965 to 1966 (and previous years) suggested that no freshmen would be enrolled in metallurgical engineering by 1969 unless something drastic were done to alter the trend. In the Spring of 1966, 20 scholarships were offered to high school seniors as an incentive to enroll in metallurgical engineering. These scholarships were financed from a private endowment to the department, but at the present time industry is also contributing to the program. With these incentives, the department essentially doubled its total enrollment in three years, as shown in Fig. 1. Cornparison of this figure with the number of students on scholarships (Fig. 2) shows a direct correlation between undergraduate enrollment and the number of students on scholarship support.

Jan 1, 1970

By L. D. Fetterolf

The New Jersey Zinc Zompany operates at Depue, Illinois, an integrated zinc smelting plant using tie vertical retort reduction process. The overall operation comprises green concentrate roasting, sintering, vertical retort smelting and metal refining. In the roasting operation, the fine concentrate is pelletized, the dried pellets fluidized and autogenously roasted with air in a “fluid column” with minimal formation of dust requiring recirculation. The roasted pellets and any associated roaster dust are agglomerated in a rotating drum and laid down, in combination with coal for fuel, on a Dwight-Lloyd sintering machine which converts to a semi-fused mass - a physical state more suitable for vertical retort smelting. The smeltins plant of 27 vertical retorts rated at 8 T zinc each per day on average requires the following major processing steps - mix preparation and briquettine, briquet coking, vertical retort reduction, vapor condensation and slab casting of metal. A portion of zinc production is converted to 99.99+ percent purity by boiling and fractional distillation in columns consisting of externally heated, superimposed trays of high-conductivity refractory.

Jan 1, 1970

J. M. Wadsworth,' Okmulgee, Okla. (written discussion).—It seems to me that thc young man must first be absolutely sure that the work he has taken up is to his liking and then I would advise that he get into the practical end of it and learn as much about it as he can as fast as he can. For instance, in the refinery business the college man, graduated in chemical engineering, should ground himself by going through the various departments in a refinery and working in them until he is thoroughly familiar with the operating problems. In a short time he would be able to apply many things which appear in the abstract form in his college work and this would opcn up an opportunity for him to capitalize on them, promoting his own interest. I do not criticize the present-day college men as a class, but I have found that many of them come into your plant with the idea that mere possession of a diploma should insure rapid promotion; in a short time they are impatient and usually leave. We have found in employing men that the single attribute most difficult to find in them is a lot of energy and whole-hearted interest in the work at hand, and it seems to me that if a man combines these with a careful technical training he should be fairly well equipped to gamble on his future. They must learn that the biggest satisfaction to be gained in life is in their work. Procedure for Attaining Objective of Young Petroleum Engineer H. B. Fell,+ Ardmore, Okla. (written discussion).—Of course, the first thing to be ronsidered in any proposition is the ultimate objective that is desired to be attained. 1 presume that the desired objective of most of the young men graduating in petroleum engineering will be that of chief executive of one of the companies in the petroleum industry, or one of the allied industries, or to become an independent oil producer, or oil refiner, or possibly an oil distributor. The next phase then to be considered is the procedure which should most logically be followed to attain the objeckive of the indivitlual, since in these cases these young men will have been trained in a course in petroleum engineering and it would logically be presumed that the attainment of their objective should be through the operating end of the branch of the business with which they are connected. The operating end is, of course, the department of each branch of the business that develops the resources, or refines the products, or distributes the products, from which the profits are derived, and is a part of any business which is filled with enough interesting work to appease the desires of the most ambitious young men. In order to get the best possible training it would appear to me that the place for a young man to start after graduation would be at the bottom of that branch of the industry which he expects to follow. For example, if he is going in the producing end he can gct no better training than is secured by starting as a roustabout in the ficltl, where he romes in constant rontact with the character of work that is necessary

Jan 1, 1928

By W. O. Philbrook

An engineering analysis indicates that the coke rate in present blast-furnace practice is set not by chemical or thermal needs but to give adequate charge permeability for economical driving rates. An equation showing interrelations among pressure drop, gas flow, and charge characteristics has been derived. Flooding conditions and the location of the fusion zone are discussed. Maximum ore size is probably limited by chemical re-ducibility rather than by heat transfer. THE intention of this paper is to show that the ].imitations on the production rate and coke requirement of the iron blast furnace are not primarily chemical or thermal in nature but are related to characteristics of the burden and operation that govern gas flow, heat transfer, and stock movement. A semiquantitative analysis will be developed in terms of standard engineering principles to give a useful picture of the relative importance of physical and mechanical factors in contrast with the chemical features of the process that are more commonly emphasized. Most of the details of calculation have been omitted in the interest of brevity and to avoid submerging the rnain points in a sea of arithmetic. Numerical values have been arrived at by objective methods from reported operating data or by reasonable estimates of material properties where exact data are lacking and then tested to see how well they fit practice, rather than by working backward to find what assumptions are needed to give the desired answers. The analysis is oversimplified in many ways because exact engineering relations have not yet been studied for bed distributions as complex as are known to exist in the blast-furnace stock column. One objective of this paper is to show that the blast furnace, in spite of its complexity, can be at- tacked by engineering methods in the hope that this viewpoint will stimulate the kind of research needed for a more exact treatment. The basic ideas and many of the conclusions presented are qualitatively well known. A careful literature survey to credit the source of all observations not original to the author would indeed be voluminous, and such has not been attempted. T. L. Joseph's Howe Memorial Lecture' gives an excellent background of what is known about the internal workings of a blast furnace. Other important reference works or sources of specific information will be noted. It is hoped that the present paper will contribute something new, in method of attack and interpretation, that will aid in a clearer understanding of how to operate the blast furnace to best advantage. Factors Limiting Production and Coke Rates The rate of combustion of coke in a blast furnace, as in any fuel bed, is exactly proportional to the rate at which air is supplied. It is axiomatic, then, that the production rate of a furnace is limited by the rate at which it will take wind, i.e., burn coke, and the amount of coke that must be burned at the tuyeres to make a ton of iron of suitable composition. These two possible limiting factors will be considered briefly in the order mentioned. One common restriction on wind rate is flue-dust production. Since the volume of top gas is nearly proportional to the blast volume (by a factor of about 1.35 on a dry basis), an increased wind rate causes a correspondingly increased linear velocity of top gas in the throat of the furnace. The higher

Jan 1, 1955

Planning for a surface coal mine includes selecting the best means and equipment for uncovering the coal, loading it, and transporting it to the preparation plant. The machines and methods that will ensure optimum production will depend upon the location and characteristics of the seam to be mined. Stripping Techniques The choice of stripping units is influenced primarily by the system of mining, such as contour or out-crop mining as contrasted to mining in a region of rolling terrain with relatively flat upland surfaces. Factors such as the life of the mining operations production requirements, types of overburden, local and regional dip of coal, and land reclamation are other important considerations.

Jan 10, 1967

By Ralph Sweetser

THE present state of iron blast-furnace practice is metallurgical rather than mechanical; the tend-ency is toward intensity rather than toward ex-tension. The engineers have built blast furnaces big enough and strong enough, and have furnished accessory equipment ample and accurate enough for the present state of the art, but the metallurgical side has been too much neglected; the metallurgist, rather than the engi-neer, is now the man on whom the present and future progress in iron blast-furnace practice depends. The mining engineer has produced great tonnages of iron ores, and has kept ahead of the demands for quantity; now the metallurgist is improving the chemical and physical qualities of this product by ore-dressing and other forms of beneficiation. For a generation or more, the principles of mechanics have had most influence in the advancement of iron blast-furnace practice; atten-tion now is given more to the principles of metallurgy, chemistry, and ore-dressing. This metallurgical progress is taking place inside and outside the blast furnace. The two great determining factors of the inside operation are the slag, and the rate of combustibility of the coke. Outside the fur-nace, the progress is, and will be, along the lines of more careful mixing of ores and iron-bearing materials, in the sizing and washing of limestone, and in the char-acter and structure of byproduct coke.

Jan 3, 1922

By KENNETH CROPPER

USUALLY we forget about the things which move along smoothly. There are no causes for worry when there are no troubles. But when troubles arise we must put forth some thought and effort to alleviate them. No one "worries about his automobile until it begins to knock, develop flat tires, or refuses to start. However, when these ailments become apparent we get wide awake on the spot, and do our best to repair the car. So we find ourselves now. The old bus seems to hit all the ditches. There is rough ground on all sides and none of us is able to do anything toward improvement. A state of pessimism stares us in the face, and there is sufficient cause for it. With lead at 3.75 cents, copper about 8 cents, zinc under 4 cents, -and silver about 26 cents, one has a reason for grief. When we think of the 5000 or less men employed in Utah mines and smelters in 1931, as compared with about 12,000 in 1929, the calamity seems even worse. In view of the present economic crisis we cannot even think of new men getting a job.

Jan 1, 1931

By AIME AIME

MECHANIZATION of operations and the development of much more refined preparation practices have been conspicuous achievements in coal-mine engineering in the last two decades. To both, Paul Weir was an outstanding contributor during his seventeen years' service with the Bell & Zoller Coal & Mining Co. and its aliates, the Centralia Coal Co. and the Crescent Mining Co. From 1920 to the end of 1936, when he resigned to go into consulting work in Chicago, he was successively chief engineer, general superintendent, and vice-president of Bell & Zoller. He changed its Zeigler mines from hand to mechanical loading, and planned and built a central mechanical cleaning plant.

Jan 1, 1939

By F. G. McCutcheon

UNTIL about 1930, the universal practice of horizontal-retort zinc smelters in the United States, as far as the writers are aware, was to operate the retort furnaces on a 24-hr cycle; that is, the retorts were charged in the early morning of one day, and in the early morning of the following day the residues were cleaned out, the retorts recharged, and a new cycle started. During the business depression of the early thirties, zinc production fell off to the extent that zinc smelters had idle retort capacity. Rather than continue to run some of the retort furnaces on a 24-hr cycle and shut down the remainder, a few companies decided to try out a longer cycle. Although the output of zinc per retort per day is lower, the longer cycle permits a larger charge per retort and improved zinc recovery. Advantages of the longer cycle were soon evident, and the practice spread rapidly. Various lengths of cycle were used, typical examples being 28-hr, 32-hr, 36-hr, and 48-hr. The 48-hr cycle fits in best with the standard routine of smelter practice that was built up on the basis of the 24-hr cycle; that is, the retort furnace "maneuver" always comes at the same time of day, and can be performed in the cool hours of the early morning. Under some conditions, particularly in some of the older plants, where the retorts are smaller than in newer plants, a 48-hr cycle is longer than necessary, and some intermediate length of cycle may theoretically be most economical. Use of an intermediate cycle, however, means that the maneuver comes at different times on consecutive days, and that sometimes it comes during the hottest part of the day. The work on the retort furnaces is extremely hot and arduous at best, and it is much worse, of course, if it is done during the heat of a summer day. When labor was plentiful and tractable, many plants were able to operate on cycles of intermediate length, but the workmen did not like the working hours. Under present labor conditions, it is hardly practicable to operate with a cycle of intermediate length, so the choice has narrowed down to the alternatives of 24-hr or 48-hr cycles. In any discussion of economics, too comprehensive generalization is not warranted, because local conditions affecting economics vary greatly. The best economic practice at one plant at any given time may be uneconomical at another plant, or even at the same plant at another time. To determine the length of cycle that is the better practice at a given plant at a given time requires a weighing of the advantages and disadvantages of each cycle, taking into consideration all the local conditions. Some of the factors that must be considered in making the comparison are discussed briefly in the following paragraphs.

Jan 1, 1947

By B. M. Harra, F. G. McCutcheon, O&apos

Until about 1930, the universal practice of horizontal-retort zinc smelters in the United States, as far as the writers are aware, was to operate the retort furnaces on a 24-hr cycle; that is, the retorts were charged in the early morning of one day, and in the early morning of the following day the residues were cleaned out, the retorts recharged, and a new cycle started. During the business depression of the early thirties, zinc production fell off to the extent that zinc smelters had idle retort capacity. Rather than continue to run some of the retort furnaces on a 24-hr cycle and shut down the remainder, a few companies decided to try out a longer cycle. Although the output of zinc per retort per day is lower, the longer cycle permits a larger charge per retort and improved zinc recovery. Advantages of the longer cycle were soon evident, and the practice spread rapidly. Various lengths of cycle were used, typical examples being 28-hr, 32-hr, 36-hr, and 48-hr. The 48-hr cycle fits in best with the standard routine of smelter practice that was built up on the basis of the 24-hr cycle; that is, the retort furnace "maneuver" always comes at the same time of day, and can be performed in the cool hours of the early morning. Under some conditions, particularly in some of the older plants, where the retorts are smaller than in newer plants, a 48-hr cycle is longer than necessary, and some intermediate length of cycle may theoretically be most economical. Use of an intermediate cycle, however, means that the maneuver comes at different times on consecutive days, and that sometimes it comes during the hottest part of the day. The work on the retort furnaces is extremely hot and arduous at best, and it is much worse, of course, if it is done during the heat of a summer day. When labor was plentiful and tractable, many plants were able to operate on cycles of intermediate length, but the workmen did not like the working hours. Under present labor conditions, it is hardly practicable to operate with a cycle of intermediate length, so the choice has narrowed down to the alternatives of 24-hr or 48-hr cycles. In any discussion of economics, too comprehensive generalization is not warranted, because local conditions affecting economics vary greatly. The best economic practice at one plant at any given time may be uneconomical at another plant, or even at the same plant at another time. To determine the length of cycle that is the better practice at a given plant at a given time requires a weighing of the advantages and disadvantages of each cycle, taking into consideration all the local conditions. some of the factors that must be considered in making the comparison are discussed briefly in the following paragraphs.

Jan 1, 1949

By Henry G. Granger

A residence of 14 Sears in the Republic of Colombia, spent . in almost continuous traveling and prospecting-trips, has given me an intimate knowledge of the resources of that wonderful country. The man who best knows Colombia is unquestionably General Rafael Reyes, President of the Republic for the past three years, and with seven years more to serve in his present term. Such is the strength of his personality and the wisdom of his policies that his term of office will no doubt endure as long as he is milling to serve. The vastly improved economic situation and the brilliant outlook for Colombia are so directly due to the influence of President Reyes that a few lines concerning him will not be amiss, if they serve towards a better understanding of his personality. Born of a distinguished ancestry in the mountain~ of Boyaca, he is now 57 years old, just the age of his friend Porfirio Diaz when he began the work which has placed Mexico in the rank of great modern nations. It was Reyes who came to Washington to protest against the action of the government of the United States of America in

Jan 1, 1909

By Goerge F. Weaton

Since 1909, when an agreement between Minnesota's Tax Commission and the University of Minnesota's School of Mines was worked out, it has been the annual responsibility of the School to evaluate and classify the iron ore deposits within the State. These unique duties of an academic institution have provided School officials with an excellent view of the past, present and probable future of the mining industry in Minnesota as the average grade of iron ore (excluding taconite) * diminishes while at the same time it competes with beneficiated taconites and foreign high-grade ores for use in America's eastern blast furnaces. SYSTEM OF EVALUATION In the latter part of November of each year, the Mining Division of the Department of Taxation makes a preliminary study of the active mines which the Department wants the School of Mines to review. These are discussed with the engineers of the Ore Estimate Division of the School of Mines and with the mining companies. After these discussions, a list of the mines of each of the major operating companies is submitted to the Ore Estimate Division of the School of Mines with the request that these properties be reviewed by them as of the next assessment date (May 1st). At the same time, a letter is sent to the mining companies requesting that they submit to the Division their own estimates on the selected mines operated by them, together with all computations, drill records, maps and cross-sections. The mining companies are re- quested to send in this information during the first half of the year, and, as far as is possible, they have always complied with this request promptly. Much of this information received by the School of Mines is of a confidential nature and is treated as such.

Jan 1, 1965

By Theo B. Comstock

TO the large majority of visitors the unique features of the National Park are interesting chiefly on account of their novelty. Scientists of all schools may find here food for reflection, and much that is rare and marvelous; but the real, practical uses of the reservation, aside from its pleasure-giving adaptations, are not as yet fully appreciated. Since 1873, the writer has on frequent occasions expressed freely his own views upon the proper means of utilizing the Park for the best interests of science.* Some of the recommendations made have been adopted by the authorities. At the suggestion of friends I present here a brief statement of facts concerning matters which may be of advantage for visiting engineers to know, hoping that the very limited stay of the Institute may thereby be rendered a little more profitable, and that our common profession may possibly receive some benefit. First, then, it should be understood that, as in many other cases in. the West, the present routes to the Park from the south are not the most direct. The expedition of Captain (now Major) Jones in 1873 discovered a practicable route for a, wagon or railroad via the head of Wind River, through To-gwo-tee Pass and Two-Ocean Pass, by which the distance from Point of Rocks, Wyoming, on the Union Pacific R.R., to the Yellowstone Lake, is only 290 miles. Eventually, it is probable that a railway line from Cheyenne or some other point in Wyoming will be constructed, which, taking advantage of

Jan 1, 1888

APRIL 10-Officially, spring comes to the Great Lakes on March 21 as it does elsewhere in the country but in the Superior district continued snow and freezing until late in March have caused citizens in Duluth to place their bets on April 15 for the first ore vessels if the ice breakup is left to Mother Nature. North and west of Duluth and near the eastern end of the Mesabilies the little town of Aurora, population 1100. As the little v-nosed snowplow, pride of the community, shuttled back and forth clearing Aurora's few sidewalks, the crowd in Bradich's Cafe were more interested in the impending high school state championship basketball tournament in Minneapolis than in the outcome of Erie Mining Company's petition for water rights for their proposed 10 million ton taconite concentrating plant. Such a plant would employ 4500 workmen, and at the prevailing ratio of 10 people for every mine worker in Minnesota, this would mean a 45,000 increase in population for Aurora and the vicinity in the next few years. Downstate fishermen are alarmed at the flurry of activity by the mining companies in pushing plans for large scale recovery of iron from taconite. Inconvenience to these gentlemen will be inconsequential when compared with the vast increase in payrolls for range communities. Oliver is pushing the construction of a fine ore agglomeration plant at Virginia which will give them valuable experience for projected taconite processing. Oglebay, Norton & Co. is ready to go at Beaver Bay, north of Duluth, as the right of way for a railroad from Babitt to Beaver Bay is secured as well as permission to dispose of tailing into Lake Superior at the site of the proposed concentrating plant. This company is also doing research in agglomeration at Ashland, Ky., in cooperation with other interests. The financing is yet to be worked out. Of the four possibilities for agglomerating taconite concentrate-sintering, pellitizing, nodulizing and briquetting-the prospects for pelletizing appear the most favorable., It seems likely that 60 cents per ton can be saved by this process over sintering because only 1 to 2 pct of coal is required as compared with 7 pct for sintering. One reason for the lower coal consumption is that the chemical transition of magnetite to hematite which transpires in the pelletizing process is exothermic.

Jan 5, 1950

There are no data available of shipments until 1858, and then estimated, when railroad service became available. By reason of the iron made in the county, and the large amounts of salt, the tonnage used locally was quite large, and until 1860 these are estimated from the probable salt and iron production. After 1859 the tonnages shipped by rail are partly estimated from the total shipments of the Allegheny Valley Railroad from four counties. It is believed that the totals are below, rather than above, what the actual production was. While considerably larger for the same years than figures given by the Secretary of Internal Affairs and census reports, these data were always too low in those days, partly because of lack of facilities for gathering them, but more largely because of the strong prejudice existing in those days against furnishing such data to any governmental agencies.

Jan 1, 1942

Three years ago, when Sun Energy Development Co. (Sunedo) dedicated its Cordero mine in Wyoming, the company noted that its decision to venture into the coal industry was prompted by the need for domestic energy self-sufficiency. Now, as the energy situation assumes crisis proportions and the cry For coal intensifies, Sunedoo has begun a $21 million expansion program that will double the mine's productive capacity by the mid-1980s. When the Cordero come was originally conceived, Sunedoo obtained permission from permitting authorities to produce up to 11 million t/y (12 million stpy) of coal. But seeing opportunities in the coal market, Sunedoo returned to the agencies in 1976 and came away with permission to produce 22 million t/y (24 million stpy). Of that total permitted capacity, Cordero is expected to produce about 3.6 million tons (4 million st) this year.

Jan 9, 1979