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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

By Oliver Bowles

WHILE vast quantities of limestone and dolomite. are used in metallurgy, the estimated production in 1926 being 23,860,000 tons, there are many problems connected with their use which have not received adequate study. The literature of metallurgy is notably lacking in comprehensive discussions of fluxing or furnace stone. Approximately 900 lb. of limestone is used for every long ton of pig iron produced in the blast furnace, but this important constituent of the charge receives little attention compared with the intensive study that has been applied to ores and fuels, the other important constituents of the charge. In an effort to elucidate some of the doubtful points, the writer has made a wide review of metallurgical literature, and has had the disappointing experience of finding not more than a paragraph or two on metallurgical stone' for each two or three thousand pages of literature reviewed. Furthermore, the limited information supplied is in some instances contradictory and even absurd. For example, a correspondent in a reputable metallurgical magazine classifies magnesia and silica together as impurities in flux "that must be melted and run off as slag." From the furnace operator's viewpoint it is desirable that as complete knowledge as possible be obtained concerning the effects of chemical composition and physical character of the stone on its action in the furnace and on the quality of the metal produced. A better knowledge of these features is advantageous also to the quarry operator in that it enables him to work more intelligently in producing stone that will best satisfy the metallurgists' requirements. The following pages comprise a brief compilation of data now available. Much of the information is well established and probably acceptable to most metallurgists. On some points there is room for debate, and the chief purpose in presenting a paper at this time is to arouse discussion which will throw more light on controversial points and thus assist the author in preparing a more comprehensive and accurate discussion of metallurgical limestone problems.

Jan 1, 1928

By Oliver Bowles

WHILE vast quantities of limestone and dolomite are used in metallurgy, the estimated production in 1926 being 23,860,000 tons, there are many problems connected with their use which have not received adequate study. The literature of metallurgy is notably lacking in comprehensive discussions of fluxing or furnace stone. Approximately 900 lb. of limestone is used for every long ton of pig iron produced in the blast furnace, but this important constituent of the charge receives little attention compared with the intensive study that has been applied to ores and fuels, the other important constituents of the charge. In an effort to elucidate some of the doubtful points, the writer has made a wide review of metallurgical literature, and has had the disappointing experience of finding not more than a paragraph or two on metallurgical stone for each two or three thousand pages of literature reviewed. Furthermore, the limited information supplied is in some instances contradictory and even absurd. For example, a correspondent in a reputable metallurgical magazine classifies magnesia and silica together as impurities in flux "that must be melted and run off as slag." From the furnace operator's viewpoint it is desirable that as complete knowledge as possible be obtained concerning the effects of chemical composition and physical character of the stone on its action in the furnace and on the quality of the metal produced. A better knowledge of these features is advantageous also to the quarry operator in that it enables him to work more intelligently in producing stone that will best satisfy the metallurgists' requirements. The following pages comprise a brief compilation of data now available. Much of the information is well established and probably acceptable to most metallurgists. On some points there is room for debate, and the chief purpose in presenting a paper at this time is to arouse discussion which will throw more light on controversial points and thus assist the author in preparing a more comprehensive and accurate dis¬cussion of metallurgical limestone problems.

Jan 1, 1928

By H. J. Sloman

"INTRODUCTION Industry, including coal mining, has come to realize that to prevent accidents the human element must be given more consideration than was customary in the past. In formulating safety rules and regulations and in the enactment of laws governing mining, too often enforcement is emphasized rather than the means of gaining willing compliance.' The purpose of this paper is to call attention to the human side of accident prevention, and the approach to this important and much-discussed subject will deviate somewhat from the usual discussions.The human being is a complex mechanism, both physically and mentally. It is difficult to establish a common denominator for the actions of humans, except in general. In establishing mining laws, rules, regulations, and standards, the ultimate objective should be to gain the best possible response of workmen, so that optimum results in accident prevention may be obtained. The complexity of human beings is apparent when the many ways 1n which they differ are considered. Some of these differences are manifested in emotional and phlegmatic types, degrees of intellect or native intelligence; and in hopes, desires, aspirations, and philosophies of life. How much simpler ac¬cident prevention would be if the response to laws, rules, regulations, or standards were equivalent to the definite movements of puppets responding to pulls on strings. Each time, the strings are pulled in exactly the same way, the puppets will respond in exactly the same manner. Human beings, although having many similar characteristics, do not respond uniformly to identical ""string-pulling""; therefore, much study is necessary before the desired re¬sponses can be obtained. To achieve the ultimate in accident prevention, it must be ""worked at"" constantly. Regardless of the adequacy of safety laws, rules, regulations, or standards, good accident records will not ""roll in"" if dude consideration is not given to the personal traits of those most likely to be involved in accidents."

May 1, 1948

By M. Dean Kleinkopf, John Callahan, William M. Shepard, R. N. Schnepfe

Despite lower prices and the uncertain future of nuclear power, uranium continued to be the big attraction in 1979 exploration activity. Uranium again dominated exploration programs across the US-not only in primary producing states such as New Mexico and Wyoming, but in potential producing areas from the northern counties of Minnesota to the Grandfather Mountain region of North Carolina. The moratorium on uranium leasing was lifted in Colorado and Montana, and exploration activity intensified accordingly. In Wyoming, what may be the biggest uranium deposit in the state was discovered by Anaconda Copper Co. near Jeffrey City, but in general, there were few major discoveries and activity was concentrated on existing exploration programs. The Department of Energy expects 1979 uranium exploration expenditures to total $339 million, compared to the $314 million spent by industry in 1978. Surface exploration and development drilling in 1979 is estimated at 16.1 Mm, up slightly from 1978 figures. Gold demanded its share of the spotlight in 1979. Soaring prices lured prospectors, investors, operators, and speculators to Alaska, California, Colorado, and Washington in a small-scale gold fever. Exploration for molybdenum remained strong in Alaska, Colorado, and Washington, where mineralization at the Mt. Tolman prospect is now estimated at 816 Mt averaging 0.09% copper and 0.10% molybdenum disulfide. Again this year, one of the major deterrents to exploration was the drive to set aside huge areas of land as wilderness preserves. In Alaska, where Interior Secretary Cecil Andrus has withdrawn millions of acres under the Antiquities Act, BP Alaska decided to close its Anchorage office, reportedly due to the lack of public lands available for mineral exploration. In both geophysical and geochemical activity, the year is best characterized as one of consolidation and development of previous advances in the state of the art, without any fundamental breakthroughs. Many companies were active in the development of instrumentation. Continuing interest in spectral IP resulted in the introduction of two instruments, one by Phoenix Geophysics, the other to be announced shortly by Geotronics Corp. Radiometric and borehole logging equipment received considerable emphasis, reflecting the continued interest in uranium exploration. MINING ENGINEERING'S review of 1979 exploration activity, including state-by-state highlights and a review of geophysical and geochemical activity, begins on the following page.

Jan 5, 1980

By D. S. Choi, R. Stefanko

There are a number of complex factors that influence the effectiveness of anchorage to maintain tension in rock bolts. However, a plastic analysis of the anchorage site employing certain simplifying assumptions with application of the Mohr-Coulomb criterion appears to explain the observed phenomena. Such an analysis has been made and a correlation sought with field and laboratory tests. Field tests were made in an anthracite mine in eastern Pennsylvania and included pull tests and long-term tests of a variety of anchorage devices in two basic lengths, 30 and 42 in. in two widely differing seams. Performance is reviewed for wedge, expansion shell, and resin anchorage. Laboratory tests duplicated many of the field conditions but in addition compared the performance of shells with normal and reversed serrations. This performance was compared with the predicted results from the plastic analysis. One of the major problems in conducting long-term underground tests is the selection of suitable instrumentation. All installed bolts were fitted with spherical and hardened washers to insure the best possible torque wrench readings. In addition, commercially available load cells were used. Finally, the performance of a specially developed strain-gage-equipped ring cell is viewed. Rock bolting as a method of support continues to increase with applications in many other industries in addition to mining. Nevertheless, with nearly 55,000,000 roof bolts installed in coal mines alone last year, this remains as the single greatest use. While bolts have frequently supported ground where conventional timbering could not, there are relatively few design criteria; and trial-and-error procedures prevail. Furthermore, there has been a lag in development of suitable instrumentation that is simple to install and read out, sensitive, durable, reliable, safe, and economical in evaluating the effectiveness of a bolt over long periods of time. Therefore, the pull test continues to be the most popular method of evaluating the applicability of a certain type of roof bolt under specific installation conditions. At The Pennsylvania State University in the Dept. of Mining, research has been conducted for a number of years to measure bleed off in carefully controlled laboratory experiments as well as in underground investigations."-' Unfortunately, most of the instrumentation developed has been primarily suitable only for research purposes, not possessing all of the aforementioned characteristics desirable for routine underground use. Other groups also have met with restricted success. Therefore, while relatively crude, the torque wrench continues to remain as the most widely used load measuring device. While both field and laboratory tests continue to be con- ducted, analytical analyses are attempted to discover the more important design parameters in order that more efficient anchorage might be devised. Bolts are being used for a greater variety of purposes in mining. Suspending wire sideframe belt conveyors from roof bolts is a common application. The suspension of a monorail transportation system presents yet another. One such system has just been installed in a recently reopened anthracite mine and is presently being evaluated under production conditions. Preliminary studies revealed that a considerable cost reduction was possible by suspending the monorail on bolts anchored in the top. The monorail was to be installed under two widely differing conditions—a competent sandstone above the Buck Mountain seam and a softer shale top above the Skidmore. The type of anchorage device, length of bolt, and long-term performance, consistent with economy and safety, had to be established for the installation once the decision was made to suspend the system on rock bolts. This paper describes some of the testing procedures leading to a final selection. Theoretical Analysis of Expansion Shell Anchorage A detailed look at an expansion shell assembly might shed some light on the factors involved in the design of a suitable shell, Fig. 1. When a bolt is rotated, the tapered plug is forced downward, expanding the leaves laterally to grip the sides of the hole. Two friction surfaces are present: (1) the interface of the plug and leaf and (2) the interface between leaf and rock. The relationships of these friction planes, geometry of expansion shell, and properties of the rock are important in the design of an expansion shell. Therefore, an analysis assuming the rock to behave as a rigid plastic material with its yield governed by the Mohr-Coulomb criterion was made." Furthermore, the effect of friction between the leaf and rock produced by serrations was analyzed.

Jan 1, 1971

By R. Karl Zipf

Highwall mining is an important coal mining method. Upwards of 60 highwall miners are presently in operation, and they may account for approximately 4% of total U.S. coal production. A review of the Mine Safety and Health Administration (MSHA) accident data over the 20 year period from 1983 to 2002 identified 9 fatalities attributable to auger and highwall mining of which inadequate ground control accounted for 1/3. In the past 5 years, 1 fatality occurred in highwall mining. Estimates of the manpower requirements in highwall mining suggest that its fatality rate is essentially the same as for surface coal mining, thus highwall mining appears to be a very safe modern mining method. Highwall stability is the major ground control related safety concern, and operators are required to develop and follow an appropriate highwall mining ground control plan. The plans usually specify the following geotechnical parameters: hole width, maximum hole depth, maximum overburden depth, seam thickness, web pillar width, barrier pillar width and number of holes between barriers. Calculated web pillar stability factor exceeded 1.3 for most designs evaluated. This study examined records from 5,289 highwail miner holes with a total completed footage of about 2,560,000 feet to understand the reasons for early pull out. Average lost footage is typically about 20% of planned footage. Only 35% of the holes reached planned depth, and 20% were short due to rockfalls. Water and adverse geology accounted for 15% of the losses. Mechanical/electrical problems, guidance, and slope stability problems accounted for the remaining 30%. Web pillar stability factor for these holes also exceeded 1.3 in 95% of cases. Trapped highwall miners present a safety hazard to workers during their recovery. Best practices to avoid trapped highwall miners include: avoid mining in stream valleys, avoid mining near outside corners, careful alignment of each hole and the use of an onboard guidance system, Several issues in highwall mining ground control require further investigation including highwall mining through old auger workings, highwall mining near old underground mines, multiple-seam and multiple lift highwall mining and finally the size and frequency of barrier pillars.

Jan 1, 2004

By Omar A. Muhtadi

6.1 INTRODUCTION The three most critical factors in successful heap leaching operations are: • The methods employed to pretreat ore (i.e, crushing and agglomeration); • Placement of ore on the leach pad (heap building techniques); and • Wetting of the ore with cyanide (solution application techniques). Improper execution of any of these initial steps may result in a substantial sacrifice of total metal extraction or, in the worst case, in project failure. Ore preparation in terms of crushing and agglomeration was discussed in Chapter 5; this chapter therefore focuses on commonly employed techniques for heap construction and solution application. The main objective of heap construction is to obtain the most homogeneous heap possible. "Channeling" of leachate in heaps with preferential seepage paths leads to preferential leachate distribution and uneven/incomplete extraction. The two main contributing causes of channeling are inadequate attention to heap construction and uneven solution application. These pitfall s can best be avoided through a knowledge of the various techniques available and the applicability and success of these techniques with various ore types and site conditions. The remainder of this chapter provides a discussion on these two subjects. 6.2 HEAP BUILDING TECHNIQUES Successful heap building techniques vary with the type of ore and, since no two orebodies are exactly alike, some slight modifications are usually necessary for each specific project. However, it is possible to generalize in terms of the appropriate techniques to be used with ores having similar characteristics. This section discusses the three most commonly used methods of heap construction and provides some guidelines with regard to ore types, construction constraints, and lift height parameters for each of the three. 6.2.1 Run-of-Mine Dumping and Dozing The run-of-mine method of heap building can only be used with ore of a highly silicious nature (i.e., ore which will not generate a large amount of

Jan 1, 1988

By B N. Morrison

In all metallurgical plants metallurgists require analyses of the various intermediate products, eg flotation feeds, flotation concentrates, tailings, mattes, slags, etc to monitor the efficiency of the plant processes and for plant control purposes. Traditionally these samples have gone to off-site laboratories and there can be some considerable delay before analytical data are received. On-line monitors have to be used for plant control purposes and these are difficult to maintain and can give poor quality data. Recent technological advances in automation in analytical laboratories now allow a far quicker turn-around time for analytical data so they can be of more use to the metallurgist. Automation, which involves the use of robots and fewer people in laboratories, has the added benefit of providing higher quality data as the possibility of human error and bias is minimised. Differences between conventional manual laboratories and automated laboratories are described. Automated analytical laboratories are now becoming the laboratories of choice for mining companies which require large numbers of samples to be analysed on a 24/7 basis on similar sample types using the same sample preparation methods and analytical procedures. Automated laboratories have now been installed in platinum, iron ore, copper and aluminium producing mining companies. A further advantage to metallurgical plants is now the possibility of siting automated analytical laboratories in-plant and designing the plant around the laboratory. Concentrator streams, slags, etc can be sampled by automated samplers, the samples transferred by automation to the in-plant laboratories and all sample preparation and analyses carried out by automated processes. These laboratories require a minimum of staff. Such automated in-plant laboratories have been installed on a platinum mine flotation plant, a platinum mine smelter and steel plants. One is in process of being installed on an iron-ore mine with the sampling being carried out by an automated sampling tower. The procedures followed in planning an automated analytical laboratory for a metallurgical plant are described in detail in the paper. The platinum plant smelter automated system which includes rapid transport of samples by air-tube to the laboratory for the analysis of the samples by XRFS is also described in the paper. It is concluded that automated analytical laboratories can be retro-fitted to most metallurgical plants but they are best suited to greenfield sites.

Jan 1, 2008

By A. M. Guadin

Direct quantitative comparison of the results of concentrating operations on different ores is frequently desired but almost impossible to obtain if comparison has to be made by means of two quantities for each ore, as must be done at present. This paper represents the outgrowth of attempts to arrive at a single-number quantitative measure of the segregation between minerals or metals as the result of concentrating operations. The usual practice in estimating the effectiveness of concentrating operations, particularly those of ore dressing, has been to determine the recovery of the metal or mineral of interest and the grade of the concentrate. The difficulty in quantifying the effectiveness of concentration by the usual criteria may be illustrated by a few examples. Consider, for instance, two lead ores which yield by flotation the same recovery of lead, say 92 per cent., and the same grade of concentrate, say 60 per cent. Pb. If a substantial difference in the grade of the feed had existed, say if one ore contained 5 per cent. Pb and the other 10 per cent., it is clear that the concentrating operation was more effective in the case of the lower grade ore. It is difficult, however, in the light of these data to state how much more effective was the concentration of the lower grade ore. Consider again two lead ores containing 5 and 10 per cent. Pb and yielding concentrates containing 60 and 72 per cent. Pb respectively, with recoveries of 93 and 92 per cent. respectively; it is well-nigh impossiblc to tell from these figures which results represent the best separation of the minerals. It may be noted that in the usual method of estimating the effectiveness of the segregation of mineral values, no consideration is given to the rejection of the unwanted substances from the concentrate, except in the very indirect manner in which it enters into the grade of the concentrate. Consideration of the rejection of gangue from the concentrate, adequately weighted with recovery of the desired mineral in the concentrate, should supply an adequate criterion of concentration effectiveness.

Jan 1, 1930

By F. G. Tryon

This paper treats only of the practicability of introducing a standard classification into the records of production and distribution of coal which we try to keep in the Bureau of Mines. From the point of view of gathering and analyzing statistics, the requirements of a satisfactory classification are that it shall be so definite as to eliminate the factor of arbitrary judgment, that it shall be reasonably simple and, finally, and most important, that it shall be understandable to the trade. In other words, to be woven in the statistical record it must be adapted to the raw material which flows in from the 7000-odd mines that produce the coal. The success of any scheme of classification, from the point of view of use, will depend largely on the degree to which it utilizes the accumulated experience of the trade and employs as far as may be possible the accepted trade designations. The experience of the Tidewater Coal Exchange during the war would be an excellent point of departure for a use classification of the coals of the Eastern Appalachians. Although the exchange long since passed out of existence, coal is still quoted and sold by the old pool numbers, and they have shown rather extraordinary vitality. Some years ago, in the Geological Survey, the experiment was tried of getting operators to classify their own coal by offering them a list of standard designations on the annual statistical questionnaire. The results were more amusing than informative. What with the confusion in terminology and the natural temptation to put one's best foot foremost, there was a general tendency to grade up the quality. Floods of semi-bituminous coal flowed in from many sources, millions of tons from districts where not a pound of that quality has ever been produced. The producers of semianthracite in Arkansas almost without exception would report their product as anthracite and their neighbors in the little Paris field, producing a fine blocky house coal averaging about 17 per cent, volatile, would say, "Our coal isn't anthracite; it's a semianthracite." Finally we discontinued the publication of those data as being more misleading than helpful.

Jan 1, 1930

By J. C. Cook

In solution-mining of underground salt and similar minerals, using drilled wells for access, it is desirable to monitor the lateral growth pattern of the resulting fluid-filled cavern. Therefore, a process of seismic surveying from the surface of the ground has been conceived in which the amplitudes of waves reflected from and transmitted through the soluble formation are measured. The large acoustic impedance contrast between solid and fluid should produce striking amplitude anomalies, especially if shear waves are employed, since thick fluid bodies are opaque to shear waves. Horizontally-polarized (SH) shear waves are best for preventing conversion to P waves at the numerous horizontal interfaces in the ground. Field tests to date have shown that a truck-mounted, half-ton hammer striking horizontally against the end of a trench produces usable SH-wave energy at lateral distances up to about 850 ft. Horizontally-directed explosive wave sources were effective to about 2000 ft. Conventional magnetic-tape recording and processing were used, but with the detecting geophones oriented to favor SH waves. An irregular solution cavity in bedded salt at 500-ft depth has apparently been located by SH-wave and SV-wave reflections. Further field work is planned to corroborate and extend this result. The Brine Cavity Research Group, an association of 11 chemical and salt producing companies, is supporting this work. Major deposits of salt in tabular beds lie beneath some 300,000 sq miles of land in the central and northeastern U.S. This salt is a basic source of soda ash and chlorine, and has been extracted as brine from drilled wells for about a century. During the past two decades, the U.S. solution-mining industry, following the lead of European operators, has greatly improved the extraction process through the application of engineering and science.' In 1957, the Brine Cavity Research Group, an association of 11 chemical and salt producing companies, was formed. This group proceeded to attack certain common problems through the support of research. An outstanding problem has been that of determining the shape and location of the growing solution cavities in the underground salt, so that measures can be taken to maintain operating efficiency. The problem has been partially solved by the Dowel1 sonar mapping service, which employs a pulse-echo device lowered into the cavity through the well.2 However, the working range of this equipment is at present insufficient for large cavities, and echoes are not returned from highly sloping walls nor from behind such obstructions as rock debris. Therefore, an independent means of mapping the cavity, for example, from the surface without interfering with operation of the well, would be desirable. THEORY OF THE METHOD Seismic waves are the only physical agent known to be capable of sufficient resolution and penetration to define typical solution cavities from the surface of the ground. The geometry is unfavorable: cavity widths are generally less than half their depths below the surface; resolution and lateral location of boundaries and channels to within 50 ft at depths of 500 to 3000 ft is desirable. Conventional seismic surveying, as used for petroleum prospecting, is probably not the answer: isopach mapping, for example, is not thought accurate enough to define the cavity by the slight additional delay time it would introduce (of the order of 0.005 sec for a 50 ft-thick cavity in hard Paleozoic rocks). Refraction surveying has also been considered, but seismic specialists see little promise in it for this problem. In 1957, in correspondence with industry personnel, the writer suggested a seismic method based upon careful measurement of reflection amplitudes. As Table I illustrates, seismic reflection coefficients r for typical brine-rock interfaces are considerably higher than those for typical interfaces between different kinds of solid rock. This fact can be utilized in two ways, illustrated in Fig. 1: 1) If the cavity roof is reasonably flat (which it may sometimes be since the unsaturated top brine will be in contact with an insoluble rock stratum), extra-strong seismic reflections will be received from the salt stratum where the solid has been replaced by liquid.

Jan 1, 1964

By A. Güney, G. Önal

"The tailings of the Bigadiç Colemanite Concentrator at the West of Turkey which contain 18 % B2O3 and 1.57 % SO3 are collected at the tailing dams near the Concentrator. In this research, it was aimed to obtain colemanite concentrates with a minimum content of 40 % B2O3 and a maximum 0.5 % SO3 from the tailings. At the experimental studies, decrepitation methods were systematically applied following attrition scrubbing and sizing. At the end of the tests, the best decrepitation result were described, at 500oC temperature for 15 min. duration, the final concentrate having 57.84 % B2O3, 0.44 % SO3 with 73 % recovery was obtained.Boron ores reserves of Turkey are about 2.5 billion tons and Turkey has the 63% share of the World’s boron reserves. The boron reserves are located at Eskisehir (Kirka), Kutahya (Emet), Balikesir (Bigadic) and Bursa (Kestelek) districts in Western Turkey. In 2002, the total amount of boron production of Turkey was about 1.4 million tons, which is 40 % of the World boron production.Bigadiç colemanite (Ca2B6O11. 5 H2O) ore with a content of 30-31 %B2O3 are concentrated by attrition tumbling and classification process. So the final concentrates with contents of 40 and 42 % B2O3 are obtained at the size fractions of –125+25mm and –25+ 3 mm respectively. The tailings materials with an 18 % B2O3 content are collected at the tailing dams near the Concentrator. In this research, it was aimed to obtain colemanite concentrates with a minimum content of 40 % B2O3 and a maximum 0.5 % SO3 from Bigadic tailings having 18 % B2O3 and 1.57 % SO3.In experimental tests, attrition scrubbing, wet sieving, gravity separation, electrostatic separation, flotation and decrepitation were adopted to the colemanite tailings, and optimum beneficiation conditions were obtained."

Jan 1, 2003

By S. S. Clarke

LATE in 1942, the increasing demand for zinc, coupled with the growing shortage of miners and the knowledge that some abandoned mines would have to be reopened for prospecting and development, led to considerable thought as to the possibilities of further mechanization in order to conserve man power. The ore bodies, locally termed "sheet ground," are an important ore bed in some mines and are in the lower part of Boone formation of the Mississippian Series. Some mines contain interbedded layers of nearly pure galena and sphalerite in horizontal sheets ranging in thickness from a thin seam to several inches and is persistent over large areas. This type of ore body offered the best opportunity for study and experiments. The use of jumbo drill carriers was advanced but some doubt was expressed as to the adaptability of jumbos as then in use to mine headings as compared to post and arm mounting (Fig I). Another consideration was the introduction of truck haulage when several mines were trackless. A drill frame, built to carry 2 4-in. drifters, was mounted on a truck chassis. This design proved a failure as it was not rigid and the resiliency of the tires and springs allowed too much play. Long screw jacks were then used to hold the truck firmly in place, but placing the jacks and securing the truck required more effort and time than setting up post drills, so the truck carrier was abandoned. The use of a bull dozer underground had been under consideration for some time to be used in "brunoing" the broken dirt from behind pillars and other inaccessable places so the slusher drags could load without double dragging the dirt. A dozer with hydraulic blade lift was purchased and R. I. Tuthill, Superintendent of Section 30 Mines, suggested that a long drill arm be substituted for the blade, and the drills mounted on the cross member. The hydraulic lift would permit drilling holes at any required spacing. The "cat" was very mobile and answered the problem of a trackless mine. The initial tests showed that the "cat" would make a good carrier, but the hydraulic controls Were not positive enough to keep the drills in alignment while drilling. The next step was to build a small hoist. This hoist was attached to the power take-off on the "cat" and by means of sheaves and a double line of 3/8-in. hoist cable, a positive control for raising and lowering the boom was obtained. To avoid serious injuries to the drillers should the cable break, a safety chain was fastened to the drill boom and hooked into a slot in the back of the "cat" frame. A different power unit was obtained for the "cat," as a state law prohibited the use of internal combustion engines in mines. A custom machine shop had just placed on the market a small hoist powered by a Model A Ford engine that had been very ingeniously converted to a slide valve engine using compressed air. To use this unit on a "cat," our master mechanic de-

Jan 1, 1947

By Ronald P. Hollenbeck

Shales in the Appalachian Region of Kentucky and Tennessee were sampled and tested to determine their use as raw materials for the manufacture of lightweight aggregate by the rotary-kiln method. Nine samples were obtained from eastern Kentucky and 143 samples were obtained from eastern Tennessee. As a result of preliminary testing of these samples, two sources in eastern Kentucky and 11 sources in eastern Tennessee were resampled for rotary-kiln tests. The rotary-kiln tests showed the two sources in Kentucky and seven sources in Tennessee contained shale that would produce satisfactory aggregate. Lightweight aggregate processed from these nine sources was tested in concrete shapes and was found to be suitable for use in structural concrete.

Jan 1, 1968

By Joseph C. Platt

It is not the object of the present paper to give a description of the minerals found on Mine Hill, in Sussex County, N. J., nor even to touch upon all the forms of the ores named, but to place upon record and call to the attention of the Institute some interesting facts concerning them. In May, 1875, after the Dover meeting, some of the members visited this locality, and, no doubt, it is fresh in their memories, being one of the best known mineralogical points in our country. It will be only necessary to describe it very briefly. Mine Hill and Stirling Hill, in Sussex County, N. J.,—the former being at the village of Franklin Furnace, and the latter near Ogdensburg,—are the only localities in the State where zinc ores are found in workable quantities.* Mine Hill is the more northerly, and mineralogically differs from its neighbor, chiefly in having no hydrated ores to speak of, while at Stirling this deposit is considerable. At both points Franklinite, red oxide, and silicate of zinc occur in large quantities. Mine Hill lies on the east side of the Wallkill River, above which it rises to an extreme elevation of about 150 feet. On the summit the outcrop of the Franklinite vein appears, while the lowest worked points are perhaps 10 or 15 feet above the level of the stream. Cornmencing at the northern end, where the Hamburg Road crosses it, this outcrop runs along the northwestern brow of the hill a distance of about 2000 feet, in a general southwest direction, to a point where is a large, cavern-like opening, called the "Southwest Opening." " Double Rock," about the highest point on the hill, lies near the middle of this 2000 feet of outcrop, and over or near it passes a property line, to which allusion will hereafter be made. At the Southwest Opening the vein bends abruptly towards the east,—the angle between the two parts being perhaps 45°,—and this easterly branch continues some 700 feet. From the northern part of the Stirling Hill deposit to the southern part of the Mine Hill deposit is about two miles, and in this interval the vein carrying Franklinite

By M Noy, P Hawkes

Improvements in the drill and blast process can impact on loader performance in a number of ways. The main effects being improved loading cycle times, less non-productive cycles such as oversize removal, clean-up and face raking and better bucket fill factors. The impact of improved loading cycle times on the overall cost and productivity of the load and haul cycle is very much dependent on the loader truck match and the management of the haul fleet. Previous work has shown that a 20 per cent improvement in dig cycle times may only lead to three per cent or less improvement in the overall productivity of the load and haul process. However, improving the mass loaded per pass by five per cent will lead to a five per cent improvement in productivity for any given haul fleet situation, assuming sufficient truck capacity. Work by Orica Explosives at Lab ChrysotileÆs Thetford Mine, Quebec, Canada showed a relationship between muckpile fragmentation and truck payload. With this in mind, work was carried out to determine the effect differing muckpile fragmentation distributions can have on excavator bucket fill factors. This work was performed in the laboratory to a 1:100 scale. Nine different distributions were used. These were characterised by the Rosin Rammler parameters, xc the characteristic size, and n, the uniformity index. The values of xc and n used were modelled on those previously measured at a Sydney quarry. For the range of distributions measured, it was found that the fill factors were lowest at a low characteristic size and a high uniformity index and highest at a high characteristic size and a low uniformity index. In other words the best fill factors were achieved with a more dispersed muckpile distribution with a larger characteristic size. The difference in fill factors was 16 per cent indicating that controlling the drill and blast process to produce a specific muckpile distribution can have a significant impact on the overall cost-efficiency and productivity of the load and haul process. Field measurement by Orica Explosives at a quarry in Canada supports this conclusion showing improvements of up to seven per cent in average bucket load by either increasing the characteristic size or decreasing the uniformity index of the muckpile.

Jan 1, 1999

By H. Evans, L. A. Hunt

The raw materials used in the blast furnaces at the Geneva Works of U.S. Steel Corp. have a high degree of variability in size-consist and chemical content. To overcome the problems caused by the use of highly variable raw materials in the blast-furnace operation, large blending piles are used. An investigation of the blending system showed that variability was significantly reduced by the use of these blending piles. This paper describes the blending system, the method used to evaluate the effect of the blending system, and the results of the investigation. The remarkable improvement in blast-furnace performance since World War II has been in large measure due to the use of beneficiated burdens to reduce the variation of both chemical analysis and size consist. This practice allows the operator better control of his blast furnace, enabling him to operate more economically and to produce chemically uniform hot metal. Planning for uniformity usually begins during mining by extracting ore from several locations within a pit to produce a final product with a specified analysis. Another approach is to stockpile ores having widely varying analyses in individual piles and then drawing the required amounts from each stockpile to provide a blend with a predetermined analysis. A further improvement in blending procedures is to take ores from several sources, bedding them horizontally in layers and reclaiming by vertical slicing from the blended pile. The last procedure, when properly executed, is one of the best methods for achieving maximum uniformity with highly variable ores. U.S. Steel Corp.'s Geneva Works initially obtained iron ore for their blast furnaces from the Cedar City area of southern Utah. These ores were formed primarily by the replacement of limestone and siltstone formations with solutions containing iron and several other elements. The original iron content of the ores in the ground varied from a high of 70% to practically zero with a minimum acceptable iron content for shipping of 37%. Substantial amounts of silica, calcium, magnesium and alumina were found in the ores along with minor amounts of copper, lead, zinc, nickel, titanium, manganese, phosphorus and sulfur which were sometimes present in detrimental amounts. Iron-to-silica ratios varied considerably throughout

Jan 1, 1968

By J. F. Martin, L. M. Melnick, R. Rapp, R. C. Takacs

Recent studies on the determination of hydrogen in steel have shown that the hot-extraction method for removing hydrogen from a solid sample is preferable to its removal from a molten sample by vacuum fusion or by fusion in vacuum with tin. A number of techniques are available, however, for determining the hydrogen so extracted. They include: thermal conductivity, gas chromatography, pressure measurement before and after catalytic oxidation of the hydrogen to water and removal of the water, and pressure measurement before and after diffusion of the hydrogen through a palladium membrane. These techniques have been evaluated on the basis of initial cost, maintenance, speed and accuracy of analysis, and applicable concentration range. The results of this study showed that the palladium-membrane technique is best suited for routine use. FOR some time investigators have been concerned with the origin, form, and effect of hydrogen in steel. In such stdies', the analysis for hydrogen constitutes one of the most important phases. It is quite apparent that the results for hydrogen concentrations in a given steel are dependent on the method of obtaining the sample, storage of the sample until analysis, preparation of the sample, and analysis of the sample, including all the facets inherent in the calibration and operation of an apparatus for gas analysis. There are a number of means available for determining hydrogen. This is a critical study of some of the more common techniques in use today. In most conventional melting and casting methods, hydrogen concentrations of 4 to 6 parts per million (ppm) in steel are quite common. Because of the undesirable effects of hydrogen on steel there has been increased use of techniques such as vacuum melting,' vacuum casting, and ladle-to-ladle stream degassing, which lower the hydrogen content to levels on the order of 1 to 2 ppm. Therefore, the method used for determining hydrogen in steel must be sensitive and precise. In any analytical procedure for gases in metals there are two distinct operations—the extraction of the gas from the metal and the analysis of the extracted gas. To extract the gas from the steel, three methods have been employed: 1) fusion of the sample with graphite at high temperature; 2) fusion with a flux, such as tin, at a lower temperature; and 3) extraction of the hydrogen from the solid sample at a temperature below the melting point of the steel. Fusion with graphite is the least-acceptable method. The blank in this method is higher and more variable than in either of the other two methods. The hydrogen fraction of the total gas composition usually is between 10 and 50 pct; thus, a larger analytical error is possible. The vacuum-tin fusion4 extraction of hydrogen is probably the most rapid method in use today; the extraction time is usually about 10 min. However, with this system a bake-out of the freshly charged tin for 2 hr is necessary and a change of crucible and a charge of fresh tin are required after each day of operation whether one or thirty samples have been analyzed. In addition, frequent checks of blank rates are required since CO and Na are continually being given up by the steel samples dissolved in the tin bath. The composition of the gas in this method lends itself readily to analysis; although the hydroge concentration may fall to as low as 50 pct, more often it is above 90 pct, thus allowing a more precise analysis (because of less interference from other gases). In 1940 ewell' published the hot-extraction method for extracting hydrogen from the solid sample, comparing analysis for hydrogen extracted at 600°C with similar analysis for the gas extracted at 1700°C by fusion with graphite. Good agreement for hydrogen was obtained between these two methods, provided sufficient time was allowed for extraction at the lower temperature. carsone obtained good results in his comparison of this hot-extraction method with vacuum-tin fusion. Subsequent work by Geller and sun7 and Hill and ohnson' has shown that steel samples should be heated to at least 800°C to effect the release not only of the diffusible hydrogen but also of the "residual" hydrogen that may be present as methane. Since the rate of evolution of hydrogene9l0 depends on such factors as sample size and composition, thermal history, and extent of cold work, a fixed extraction time is not possible. Extraction times of 30 min are normal, but 2 hr are not unusual. Induction or resistance heating may be used in the hot-extraction method. With resistance heating the

Jan 1, 1964

By G. D. Just

INTRODUCTION Large scale underground mining involves the bulk handling of fragmented material. The cost and efficiency of the mining systems is there- fore significantly influenced by material flow characteristics. Flow problems may occur in the form of ore pass blockages which interrupt the free flow at extraction openings. The costs of such delays can be readily assessed and compared to the costs incurred in reducing blockages by improved fragmentation or larger ore passes. In practice the problem is more complex than this statement suggests because it is generally un- economic to design for zero ore blockages. Another major flow problem occurs in the form of relative movement of ore and waste as the fragmented material is extracted. This produces waste dilution in the recovered ore and influences total ore recovery. This flow problem is much more complex than the ore block- age phenomena. Many questions concerning the precise flow characteristics remain unanswered because of the variability of size distributions, particle shapes, material properties and the total extraction layout and design. Model studies can provide a visual and quantitative illustration of probable flow characteristics but full scale data collection is necessary to evaluate the precision of such information. The methods and types of data obtained must be carefully selected to recover the maximum volume of useful information for operational control and future design. It is essential that honest precision levels are assigned to the data and any subsequent analyses. Grade control data may give misleading short term information on flow characteristics because of the difficulty in knowing the true grade of the mass of material before extraction commences. However, in the long term control of extraction grades is vital to the profitable operation of the mining system. The most efficient extraction design and operational schedule can only be determined after all of the facts and variables are known. This is usually only possible after the orebody has been completely extracted. However, if design and operational personnel have a full appreciation of the nature and variability of material flow under different conditions the best possible results should be achieved. The most significant features of material flow are out- lined in this paper in order to provide mine planning and mine management personnel with some of the necessary information relating to material flow. Available facts and reliable figures from selected publications are noted in association with unbiased and hopefully accurate opinions of the relevance of the data to mine design and mine system control. Possible future developments and profitable areas for research into material flow problems are also detailed. MATERIAL FLOW AND MINING METHODS The effects of material flow on the design and operation of an integrated underground ore handling system is one factor which is common to most mining methods. Analysis of the system as detailed by Just, 1980, permits the identification of unit process objectives. For example, a typical underground ore handling system as illustrated in Figure 1, involves the following unit operations:- (i) Gravity flow of ore in stope (ii) Ore extraction at base of stope (iii) Ore haulage on the production level (iv) Dumping of ore into ore pass system (v) Gravity flow of ore in the ore pass (vi) Underground crushing of ore (vii) Haulage of crushed ore to shaft (viii) Hoisting of ore to the surface. Average flow rates in each of these unit operations can be misleading due to variability in incremental capacity caused by flow blockages and machine delays. Thus to effectively analyse the probable performance of the system, it is necessary to have a measure of the flow loading and haulage rate variability. Mechanical equipment performance specifications can be used to provide such information for loading, haulage and crushing; however, in the case of the gravity flow of material field measurements are required to relate the probability of "hang-ups" to the degree of fragmentation. Factors affecting the frequency of flow stoppages are, size, distribution and cohesiveness of broken material and the geometry and size of the flow channel. Ore pass channel design is relatively simple since regular cross-sectional shapes are used

Jan 1, 1981