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By Richard Franchot

DISCUSSION of a paper is sometimes more in-teresting in what has not been said than in what is said. In the present case the paper is mainly directed to certain thermo-dynamic relation-ships in the blast furnace. Careful reading of the dis-cussion fails to show a single use of the term, heat unit, or its equivalent. If we wish to know very-much about the furnace action it is necessary to count calories or B.t.u. Nothing much is. said about the availability of heat at high temperatures, although it will be generally admitted that in seeking underlying limiting factors in the furnace economy the hearth heat relations offer-the most promising clues. Those discussing the paper, with exceptions of course, apparently have failed to recognize an outstand-ing fact. It is a fact that the heat actually generated by the air oxygen in CO formation (including the blast heat) is in excess, after charging off radiation, etc., by from 70 to .90 per cent over the heat absorbed in melting the iron and slag and calcining the stone reduction by CO absorbing no heat. The fact stands out as plainly as does the fact that the furnace functions largely as a gas producer. The surplus heat is there. It is in the picture. Why not take a look at it, face the fact? That the surplus heat is necessitated by the hearth conditions admits of very little if any doubt. The furnace is really two separate pieces of apparatus: the hearth, doing certain work, and the superimposed shaft, doing certain other work. The combustion of fuel in the hearth, primarily serving the hearth pur-poses, generates much more heat and gas than the shaft requires, or can use, in smelting work. The result is surplus heat makes still more gas in the heat-absorbing reaction between CO, and coke; what is left of the surplus going to top heat. Here we have a simple yet adequate sketch of the furnace action. Having obtained a fairly comprehensive view of the existing heat relations of both hearth and shaft, the way to improvement seems quite plain. Either do more of the work above the hearth or put more heat into the hearth. Since there is already a great surplus of heat above the hearth, probably little needs to be done by way of increasing the proportion of the work done in the shaft. The shaft can, however, probably do much more work than it is now doing provided that a way, can be found to get more work, done in the hearth. The hearth heat is nicely balanced. Losses by radiation and water cooling and other losses are already taken care of. Any increase of hearth heat development could be utilized in taking care of increased smelting work. Aside from the possibility of increased blast heat, there is one sure way of putting more heat into the hearth, and this is to blow more air. And since the shaft already has more gas than it needs, the increased gas resulting from the greater blast volume can be withdrawn from the bosh after it has done its work in the hearth. Now an increase of burden will cool the shaft, cut down solution loss and thereby supply addi-tional coke in the hearth to burn with the additional air blown. The hearth heat per pound of coke charged will be proportionately increased. The balance between hearth and shaft will be better. Gruener's ideal will be more nearly attained, if not exceeded. Most inter-esting of all perhaps, the more the burden is increased, the more coke will reach the hearth and the more burden can be added. The effect is to be cumulative.

Jan 3, 1927

THE paper on "Specific Efficiency of the Blast Furnace" by Richard Franchot, which was pub-lished in the September issue of MINING AND METALLURGY, was presented for discussion at the Pitts-burgh meeting. The session opened with a discussion among S. P. Kinney, Mr. Franchot, and J. N. Reese as to the methods and results in sampling for cyanides in the blast furnace. This is covered in detail in writ-ten discussion below. T. T. Read objected to the use of the term specific efficiency as likely to be confusing. The blast furnace has to perform the function of reducing Fe, 03 to Fe as well as that of fusing the metal and, since the reduc-tion of Fe, 0? involves a CO equilibrium, it seems mis-leading to calculate efficiency on the basis of burning the , all carbon to CO? since it is not possible. Mr. Franchot replied that he used the term in the sense defined by Richards in his "Metallurgical Calculations;" but a subsequent search failed to reveal the term in Richards, who says (page 245, 1st edition): The practical conclusion is that a blast furnace generates in itself not much over 40 per cent of the calorific power of the fuel used, and rejects nearly 60 per cent; by using part of the waste gases to heat the blast, however, some of this rejected heat, to an amount representing net 5 to 10 per cent of the calorific power of the fuel used, is returned to and injected bodily into the furnace, thus rendering available for the purpose of running the furnace about 50 per cent of the calorific power of the fuel as a maximum. The efficiency with which the furnace applies this 50 per cent usefully to the objects of the reducing and smelting is another question for investigation.

Jan 2, 1927

By V. M. Paretsky

Most recent developments made in the Gintsvetmet Institute in the field of technologies and equipment for single-stage autogenous smelting of copper sulfide raw materials to produce white metal and blister copper on the basis of oxygen-flame smelting process and separation of highly basic calcium-containing slags have been discussed. This technology includes the oxygen-flame smelting process (KFP Process) to produce highly basic self-disintegrating ferrite-calcium slags with their subsequent flotation to recover copper and a basically new sparging smelting process (FBP Process) to produce combined slags subjected to decopperizing inside the same furnace. Results of special investigations of the slag structure obtained in the KFP and FBP processes and substantiating selection of their chemical and phase composition have been presented. It has been demonstrated that the above processes meet the stringent world-level requirements to advanced technologies with respect to energy conservation and environmental safety with different scales of production and within a wide range of specific conditions of particular operations.

Jan 1, 2006

By Reid T. W

This paper describes the results of investigations into the relationship between specific gravity and chemical composition in the Cockatoo Island orebody, In the early investigations the samples were classified into groups according to porosity. This resulted in high, medium and low porosity groups, the latter being further subdivided into ore and waste. Whole number tonnage factors were assigned to each group. In the later investigations the reciprocals of bulk specific gravity and true specific gravity were ex- pressed as linear combinations of iron, silica and alumina using stepwise regression. The efficiency of the models as predictors was tested by dividing the data into two sets; one of which was used to calculate the regression equation and the other to test the efficiency of the equation as

Jan 1, 1976

Every estimate of ore reserves necessarily contains an assumption in regard to the specific gravity of the ore. This assumed figure may be based on experimental data, on textbook data, or on a reconciliation of past tonnage estimates and production figures. Not infrequently it is simply a guess - shrewd or otherwise.Errors in the density factor are not likely to be serious in gold-quartz mines-or, at least, not so serious as in base metal mines. It is to the closer determination of ore density in the latter that this paper is devoted. Moreover, the remarks apply to ores which show no appreciable pore space.Not many ore bodies are sufficiently homogeneous to allow of a truly representative factor being obtained by the simple testing of a few specimens of ore, or by the weighing, after breaking, of a carefully measured block. The empirical figure derived from a comparison of past ore reserves and actual production can never truly describe conditions other than those now past; no real link with ore as yet unmined is provided. The dilution of heavy ore by waste is not exposed by this method, but is effectively cloaked. Anyerrors in past estimations of ore reserves are transmitted, by way of the density factor, as a source of error in all future estimates.ObjectIons may be raised to the practice of weighing measured blocks of ore in the case of any but a very homogeneous ore body. Even then, the exact composition of the block weighed, and an indication of whether its moisture content is representative of the whole, are difficult to determine.

Jan 1, 1940

By Wei Huang, Anh V. Nguyen

"Potash flotation is an industrially proven success of flotation of soluble salts, but its collector adsorption mechanism remains elusive. In this paper, specific ion effects in NaCl-KCl flotation with carboxylate collectors were investigated. Flotation recovery and contact angle were determined as a function of brine composition of NaCl and KCl. The experimental results have shown that wettability of KCl and flotation of the soluble salts with laurate collectors were dependent on brine ion composition. Specifically, adding Na+ to brines decreased hydrophobicity of KCl crystals and their flotation recovery. Both KCl and NaCl could be floated with laurate collectors. However, flotation of NaCl was greatly enhanced by adding K+ to brine whereas flotation of KCl was significantly suppressed by the presence of Na ions. The decrease in KCl recovery upon adding Na+ is attributed to the counter-ion binding in the pulp. The flotation recovery enhancement of NaCl in the presence of K+ is explained by two effects: 1) increasing K+ concentration leads to a better dispersion of collector colloids in the pulp and 2) K+ enhances the collector adsorption at NaCl crystal surfaces. The water affinity matching rule can explain the specific ion binding behaviors and supported by the SFG spectroscopic results.INTRODUCTIONPotassium is an important fertilizer. Its primary source comes from potash ores, which are a mixture of sylvite (KCl), halite (NaCl) and many other complex double salts such as carnallite (KCl·MgCl·6H2O), alkali nitrates such as KNO3 and NaNO3, and sulfates-langbeinite (2MgSO4·K2SO4) with water-insoluble minerals such as clay and carbonate minerals. Previously, these salts were recovered with a lengthy hot leaching method, with further crystallization of potassium salts from saturated saline solutions. Selective flotation has been preferred since 1940s. Various collector adsorption mechanisms have been proposed soon after the industrial introduction of potash flotation. These include the formation of the insoluble compound model (Halbich, 1933; Singewald, 1961), an ion exchange model (Fuerstenau and Fuerstenau, 1956), a heat of solution model (Rogers, 1957), the surface hydration model (Schubert, 1988), the surface charge model (Roman, 1966; Miller et al., 1992), the interfacial water structure model (Hancer and Miller, 2000) and the colloid adsorption model (Leja, 1983; Burdukova and Laskowski, 2009). Most of the early exercises attempting to propose a unified rule on collector adsorption mechanisms can be seen as heroic endeavors due to the consideration of a vast number of salts in the pulp including alkali halides, nitrates, and sulfates, even the practically insoluble heavy earth metals. Additionally, several types of surfactants with different polarization features and alkyl chain length have been employed. As for the recent models, due probably to the preferential application of long chain amines as collectors in industrial potash flotation, most researchers are only devoted to collectors with low polarization features like amines and sulfonates (Hancer and Miller, 2000; Du et al., 2014). Collector adsorption mechanisms are therefore proposed based largely on a neglect of carboxylates as collectors. However, carboxylates remain an important collector type in soluble salt flotation systems where both salt minerals can be floated using anionic collectors and cationic collectors. Fatty acid type collectors are still one of the widely used collectors for soluble salt flotation and also one of the first to be applied on an industrial scale for the separation of potash ore (Hernáinz et al., 2003; Titkov, 2004). Here we examine some recent models that are relevant to our study to reveal a long neglected specific ion binding effects in potash flotation."

Jan 1, 2016

By L. E. Mylting

Modern ash handling systems exist in considerable numbers and a great deal of design and operating experience has been accumulated, It is the endeavor of this paper to point to a number of frequently recurring problems, A general appreciation of these problems will be helpful in both design and operation of systems. The light fly ash and the heavy bottom ash present different problems, and each will therefore be treated separately. Fly ash is collected in the ducting from the furnace to the stack and beneath the mechanical and electrostatic dust collectors. The greatest amount of dust is collected beneath the mechanicals and electrostatics. Hoppers are generally provided as integral parts of the collector. Suitable valves and piping are connected to these hoppers for removal of the dust. The size and shape of these hoppers are important factors in determining frequency of handling and the capacity of the system.

Jan 1, 1958

By Peter Loehr

Full-face tunnelling machines were introduced into German coal mines 12 years ago. It was aimed to utilize these highly efficient systems to drive mine tunnels in rock so that the large demand for development work in some mines could be met. A characteristic feature of coal deposits in Germany - and particularly in the Ruhr Area - is a thick overburden strata. Access is therefore only possible through vertical shafts. A network of horizontal drivages leading from these shafts open the deposits between the different mine levels. The hardcoal-bearing formations are multi-folded and heavily tectonically stressed. Apart from a few extensive fault zones there are many single faults of different natures in the carboniferous strata. During the course of decades coal mining has penetrated to ever increasing depths. Nowadays coal is mined from depths of between 600 m and 1,200 m. The effects of ground pressure in connection with extremely varying rock strengths and high temperatures are particular difficulties which have to be overcome during drivage work. The first full-face tunnelling machines to be applied in the mines had originally bee deigned and developed for tunnelling projects. Not only the machines themselves, but also the back-up equipment had to be adapted to meet the special demands of German coal mines.

Jan 1, 1983

By Lothar Anheuser

The appearance of very large shielded softground TBM's, of 14 m (46 ft) O.D. and more, as needed for two-lane highway tunnels, calls for a thorough search of overall stability and new solutions for front support during maintenance operations in the cutting chamber. The paper deals with the development of a shield for the planned 4 th tunnel crossing under the river Elbe in Hamburg. Specific problems arise from the high water head, the shallow overburden of loose soil and the stone-bearing mixed ground. The choice of the tunneling method and the different features provided to overcome the problems are discussed.

Jan 1, 1995

By Arch J. Alexander

This paper is a resume of a study undertaken by the West Virginia Department of Mines. The underlying and direct causes of accidents are determined in each occupational group. Then from this study, accident prevention courses, visual and written, are to be taken to the various working groups in the mines.

Jan 9, 1950

By D J. Brake

There are many sources of gas in underground mines including development and production blasting, strata gases, spontaneous combustion, diesel equipment, chemicals used for a wide range of functions, welding activities and fires.It is only in relatively recent times that electronic gas monitors (or detectors) have become both safe and affordable for routine use.In modern mines, gas monitors should be in daily use by the ventilation department as well as blasting re-entry (or clearance) crews, and are often used by drilling crews, shift supervisors, hygienists and mine rescue or fire fighting crews.When first released, electronic gas monitors needed to be sent off-site periodically for calibration at a suitable accredited laboratory. Between calibrations, their accuracy was unknown. More recently, ‘bump testing’ and field calibration has become possible on the mine site, improving both reliability and safety as well as reducing the total number of gas monitors that need to be in use.There has been almost an overwhelming increase in the number and sophistication of gas monitor features in recent years. This paper reports on a case study into the key criteria that ventilation practitioners should be aware of with respect to the specification and selection of the most recent gas monitoring systems, and recommends good practice for site-based operation and calibration.CITATION:Brake, D J, 2015. Specification and selection of hand-held gas monitors (detectors) for underground mines, in Proceedings The Australian Mine Ventilation Conference, pp 143–154 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By Carter S. Cole

Mr. Chairman, Fellow Members and Guests, our chairman this morning got over into the geneological field, so perhaps I may be pardoned if I revert to some of my ancestral training and give you a text. I always like to talk about some special little text that may illustrate what we want to say. So the text that I will take for this afternoon is a very simple one, "Win the War." That is the guide for all of our actions, or should be. We should question everything we do to see what it does to contribute to winning the war. If we fail to do that, nothing else is going to count. On the wall of the office of one of the branch chiefs in the Copper Division in Washington there is a little slogan which I think we should take very deeply to heart, "The difficult we do right away. The impossible takes a little longer." I think that is a very good guide for us to follow in the work that lies ahead of us in the metallurgical field and in the handling of these secondary metals and the things that result therefrom. My subject is "Conservation and Specifications." Some people would wonder just where that fits in, and how you might define "conservation." One very good definition would be "the utmost use of our resources." If you will pardon my going back to some of my earlier experience for a little simile, those of you who know me know that for ten years after the last war I was in the railroad business. If we are with the engineman in a cab, and we have a green signal ahead of us, that is a clear signal and tells us to proceed at full authorized speed. Now suppose we come to a yellow signal that is caution, slow down to one-half authorized speed and be prepared to stop. Now if you do slow down, the chances are that that obstruction that was ahead of you will move out of the road, and you may get another yellow or caution signal at the next block, and be able to keep going at a slow speed. As of the date of Pearl Harbor our tin supply took on a very yellow tinge, and it threw the caution sign right in our faces. If we had not heeded that sign, and cut down our consumption of tin, we would not have any today; but because we have done so we are in a much better position today than we were a year ago, that is comparing our visible supply with our present rate of consumption as contrasted with the visible supply a year ago and our then rate of consumption.

Jan 1, 1943

By V. Svalbonas

Presently the U.S. mining industry is very conscious of costs. It is timely, therefore, to review the dominant specifications used in the industry for procuring large size-reduction equipment. These are compared with other specifications and procurement methods, such as ASME and DOD, using the criteria of resulting costs, safety/ quality, and fitness-for-service.

Jan 1, 1987

By A. J. Hendron, L. L. Oriard

INTRODUCTION Controlled blasting is used at some time during most civil engineering projects where there is rock excavation. Controlled blasting is often necessary because the blasting must take place in the near proximity of adjacent structures. In other instances, the blasting is controlled because a smooth perimeter is desired to minimize rock support and overbreak. The construction of tunnels and shafts for subways, rock excavations for foundations and the excavation of road cuts for interstate highways, sometimes require blasting operations which must be conducted in an urban environment. Unfortunately, blasting operations produce unwanted sounds and vibration along with their beneficial effects. Thus, in the writing of specifications for blasting in an urban environment, potential damage to adjacent structures by ground vibrations must be considered, possible damage to windows from airblasts must be considered, potential damage from fly rock must be considered, and the discomfort to people from ground vibrations, airblast, and noise must be taken into account. The contractor or the owner's engineer is faced with determining the maximum weight of explosives which may be detonated without damage to structures on adjacent property. If the weight of explosive is overestimated, the resulting damage to adjacent structures may result in costly losses. But, if the engineer or contractor is too conservative, and the weight of explosive becomes too restrictive, progress of the project may be curtailed and the cost of excavation will increase accordingly. The potential for damaging adjacent property is becoming more important in construction operations today. In the past, the plaintiff had to prove negligence in some states in order

Jan 1, 1997

By William F. Daly, William H. Hansmire

Installation of initial tunnel support is often the most uncertain element of work in the design of, and a contractor bidding on, construction of a rock tunnel. The risks the construction contractor and owner assume are delineated to a great extent in the technical specifications portion of the contract documents. It is intended that this paper identify current practices for specifying initial tunnel support and the impacts each case has on the assignment of risks associated with providing the initial tunnel support. Examples of recently completed tunnel designs are given.

Jan 1, 1985

By J. E. Gray

Before specifications are discussed it may be well to define the term "Mineral Aggregates." Professor K. B. Woods (1) defined "Mineral Aggregate--An aggregation of sand, gravel, crushed stone, slag, or other material of mineral composition used in combination with a binding medium to form bituminous and portland cement concrete, macadam, mastic, mortar, plaster, etc., or alone as in railroad ballast, filter beds, and various manufacturing processes, such as fluxing, etc. " This definition is too all inclusive for the purposes of this paper; therefore, this discussion will be confined to specifications for natural aggregates which means sand and gravel and crushed stone, and limited primarily to coarse aggregate which is aggregate larger than one-quarter inch in size. To the uninitiated, this may seem to be a very limited subject on an unimportant material. However, aggregates are essential in all types of construction. The tonnage and value of these two aggregates produced in the United States during 1959 as reported by the Bureau of Mines were as follows: Sand and Gravel 729,895,000 tons valued at $728,527,000 Crushed stone 581,721,000 tons valued at $824,411,000

Jan 1, 1961

By M. Jack Snyder

The problem of effective utilization of fly ash has been given wide attention for a number of years. Although the effort devoted to the problem has led to some applications of demonstrated usefulness, the full utilization of fly ash has been held back by lack of concerted research and development activity, by lack of effective dissemination to potential users of fly ash of the knowledge that is available from laboratory and field studies, and by the obvious variability of the product. Because of the variability in fly ash from one power plant to another and from time-to-time in the same plant, specifications have been set up defining compositional or property limits within which a fly ash must fall to be used in certain applications. This paper discusses the bases for such specifications and examines them in the light of recent research on the characterization of fly ash. Other limitations and restrictions on the use of fly ash and what is being done to overcome them are also discussed.

Jan 1, 1968

By R. Tanaskovic

Unfavourable climatic conditions in stopes are of significant economic and social importance due to the following reasons: - Working effect is much lower leading to decreased output and work productivity disregarding implementation of mechanization. - Manpower operating capability decreases much faster under unsatisfactory climatic conditions. Under normal climatic conditions a workman would expend much less effort in line with a shorter effective time for the achievement of identical production effects since the work would be more efficacious. The objective of study of problems and climatic conditions is to make the working environment in mines suitable for normal development of operations. Lowering of mining works to increasing depths and winning of a growing number of small orebodies over a broad area makes the problem of creating suitable climatic circumstances more complex. Mining costs are growing due to bench conditions in line with decreasing metal content in the ore, so frequently the investments required for creating favourable climatic conditions represent, in addition to the selection of mining technology, a very important parameter when making decisions regarding exploitation. As known, the basic factors affecting climatic operating conditions in mines-are: temperature, humidity and speed of air flow, implying that the climatic operating conditions are closely related to mine ventilation. Usually, the concept of unfavourable climatic operating conditions includes increased mine air temperature and humidity and low air flow velocity so that heat exchange between human organism and the working environment is impeded or reduced to minimum. Metal mines in Yugoslavia are characterized by the existence of a large number of active faces - stopes and horizons and lowering of mining operations to increasing depths, so that face ventilation solutions are more and more complex. Since its foundation (1961), our Institute is engaged in investigation of factors influencing climatic circumstances improvement of calculations for air distribution and distribution control in complex ventilation networks and study of problems related to ventilation of large volume and irregular configuration faces, as well as application of gained knowledge in our mines. The paper presents the knowledge and experience gained in the case of Lead and Zinc Mine "Trepca" - Stari Trg.

Jan 1, 1980

By Y. M. Shneerson, P. V. Zaytsev, I. V. Fomenko, M. A. Pleshkov

A thermodynamic description of the equilibrium in liquid and gas phases under specific conditions of refractory gold pressure oxidation was generated using the HKF theory. The gold behavior was considered at 190-225°C in the presence of 1-100 mg/L of chloride ion, and under oxidationreduction potential (ORP) of +700 to +1030 mV. The calculations show that the predominant form of gold(I) occurrence is [AuOH]° compared to [AuCl2]?. High ORP favors the formation of [AuCl4]? as a predominant form of gold(III). It is noted that this complex is responsible for the gold losses buildup during POX. Laboratory test results for double refractory concentrate POX are shown. The combined negative effect of (i) organic carbon of the concentrate and (ii) dissolved chlorides in POX slurry on gold recovery is demonstrated. The effects of carbonate blending to the POX feed concentrate and incomplete oxidation of sulfides on POX performance were studied. The pilot tests results of continuous pressure oxidation are also shown and generally confirm the laboratory results and theoretic dependencies. A comparison of the experimental data with the results of thermodynamic calculations is made. As a result of current research, an effective process for POX treatment of carbonaceous sulfide concentrates in the presence of chlorides was developed.

Jan 1, 2014

By John Matthews

During 1982 and 1983, it became increasingly clear that North River No. 1 Mine would have to buy a set of replacement longwall shields. Despite extensive efforts to make improvements, the shields that were in place at that time were incapable of holding the roof. North River Energy had limited experience in specifying and acquiring longwall roof supports, but a great deal of experience with our conditions and needs. We there- fore compiled a shield evaluation method that uniquely responded to our situation. The resulting system emphasized teamwork among operating, maintenance and engineering personnel. The charge from management was threefold: select shields to support maximum expected loads, optimize face operations, and pay attention to detail. Final selection was made objectively, based on all available information. We chose a 5516 KN (620 tons) support with a minimum yield load density of 760 KN/m2 (7.9 tons/ft2). This paper reviews our process of specification, design, prototype testing, and fabrication, and offers some relevant suggestions.

Jan 1, 1986