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By Richard Komarek

When limestone (Ca03) is calcined in rotary kilns to produce quicklime (CaO), it is not unusual for 10% to 20% of the stone to abrade and emerge from the kiln as quicklime fines (-6.3 mm or -0.25 in.). While there are various industrial processes that can use fines, handling and shipping is tricky and dangerous. Due to the highly caustic nature of quicklime, airborne dust easily bums eyes and skin. On the other hand, money has already been invested in mining (or buying) the raw material and in the equipment and energy needed for calcining. Discarding the fines will not only waste that investment, but add even more cost in transportation and possibly dumping charges. So the question becomes, how can fines best be turned into a revenue-generating asset? Some plants convert leftover quick-lime fines into calcium hydroxide - Ca(OH)2, also known as hydrated or water-slaked lime - for sale into agricultural applications. For farm uses, hydrated lime fines are preferred over quicklime because they are easier to handle. And they are favored over raw limestone fines for their higher concentration of calcium and greater solubil¬ity. From the producer's viewpoint, quicklime fines are ideal for this use because they go through hydration faster than the larger chunks of quicklime. Those larger chunks, or "pebble lime," are more readily salable and more easily handled, for such uses as steel, copper, aluminum and magnesium production, water waste treatment, chemical, paper, glassmaking and flue gas desulfurization in coal- fired boilers.

Jan 1, 1993

By O. Barron, C. Felix

In 2023, polymer electrolyte membrane fuel cell membrane electrode assemblies accounted for about 62% of the global fuel cell market share and this demand is expected to grow. Commercialisation requires technologies capable of cost-effective, high-volume manufacturing. The membrane electrode assembly is crucial and represents a significant cost to polymer electrolyte membrane fuel cell manufacturing. Manufacturing the electrode components for membrane electrode assemblies at high volumes can reduce production costs while delivering on the forecasted industry demands. Roll-to-roll is a mature coating technology applied in various manufacturing industries such as batteries, printed electronics, microelectronics, photovoltaics, printing, paper consumables, etc., with significant potential for polymer electrolyte membrane fuel cell manufacturing. While the high-volume production process for membrane electrode assembly manufacturing differs from laboratory-scale, the membrane electrode assembly structure remains unchanged. Roll-to-roll is a continuous coating process with speeds of 10 m/min being achieved. In this work, MicrogravureTM and slot-die coating methods have been adopted and have shown promising outcomes for producing gas diffusion electrodes for membrane electrode assemblies. An overview of the MicrogravureTM and slotdie coating methodologies is provided, and a discussion on preliminary results and challenges are presented. Work on MicrogravureTM gas diffusion electrode manufacturing has already achieved comparable performance with spray-coated gas diffusion electrodes. The influence of coating parameters and drying on the coated catalyst layer quality is discussed.

May 27, 2025

By AIME AIME

EVEN the weather man joined in a friendly conspiracy to make the fall meeting of the Industrial Minerals Division at Rolla, Mo., Oct. 23-25. the splendid surges that it was. Following weeks of rain, the foliage of the Ozarks was still green, merely enlivened here and there by splashes of autumn coloring. In contrast to the tranquil beauty of the School of Mines campus under smiling Indian summer skies, the pace of the meeting was lively. Registration was larger than at any previous meeting and included an unusual number of prominent names and delegates from all over the country. From 125 to 150 were present throughout the three technical sessions, at the Thursday evening smoker, and also at the banquet on Friday; when students trooped in to the technical sessions the audience was augmented occasionally to over 200.

Jan 1, 1941

By C. H. Ferguson

The fact that little if anything has appeared in the technical press or in the Transactions of the Institute on the subject of roll shells proper, used in various grinding appliances…

Jan 1, 1915

By James Ferguson

THE fact that little if anything has appeared in the technical press or in the Transactions of the Institute on the subject of roll shells proper, used in various grinding appliances such as Cornish rolls or Chilean mills, may be taken as an incentive, if not an excuse, for the present article. No attempt is made to enter into a. discussion as to the theory or mathematics of crushing as performed by rolls, the subject being treated in a general way with respect to the manufacture of roll shells 'and some salient points touching on their adaptability and wear in service. While it stands to reason that skill coupled with judgment in the mechanical design of rolls, Chilean mills or other types of grinding machinery, with special reference to strength of parts, nicety of adjustment and other mechanical features, stand for efficiency in their operation .and satisfaction in service, the exceedingly important item. of roll shells or other wearing parts entering into their construction should not be lost sight of. In other words, a well-designed piece of grinding machinery is just as inefficient in service, when equipped with poor roll shells or shells made of the wrong or an inferior grade of metal, as good roll shells made according to the best practice the steel maker knows, working on an old or antiquated set of rolls. Unfortunately there is a tendency occasionally for the machinery builder to blame the steel maker or vice versa if roll shells do not wear well or evenly, or if they break before being worn down to their ultimate thin point. There is no occasion for this attitude, as the product, of each must stand on its own merits. But it is essential that the two work in harmony since the machinery builder usually does not furnish the shells for his rolls or grinding mills, but depends on the steel maker, who makes a specialty of this rolled product, to give the particular needed element of efficiency to his machine.

Jan 9, 1914

By P. W. Ramsey, E. J. Boyle, E. A. Anderson

ONLY a few zinc-rich alloys are in commercial use today, and these depend largely upon solid solution effects for their desirable properties. Typical examples are rolled alloys containing about I per cent of copper, with or without additions of elements such as magnesium,1 and die-casting alloys containing about 4 per cent of aluminum with small amounts of magnesium and sometimes copper.2 A number of elements are capable of forming alloys with zinc, which do not enter into solid solution except in limited degree. The present paper considers one such system, zinc-titanium, in which alloys having potentially useful properties in the rolled form were found. ZINC-TITANIUM SYSTEM The zinc-rich portion of the zinc-titanium diagram, as determined by standard methods in this laboratory,3 is shown in Fig. I. The portion of the diagram of significance in the present work extends from 0 to about 0.5 per cent titanium. Gebhardt4 places the eutectic at 0.45 per cent, but the evidence in favor of the composition given in Fig. I is considerable. The solid solubility of titanium in zinc is very low indeed and possibly places these alloys in a somewhat different category from the commercial alloys previously mentioned. ALLOY PREPARATION All of the alloys used in this work were prepared with titanium metal of 98.9 per cent purity. In most cases high-purity zinc (99.99 per cent) was used but sufficient work was done later to show that zinc of about high-grade composition would yield approximately equal results. Best practice in alloy manufacture seemed to be to prepare a zinc-titanium hardener by adding about 4 per cent of titanium metal to molten zinc and holding under a boric acid cover, with frequent stirrings, at 750°C. until the titanium had dissolved. The desired titanium content could readily be obtained in the final alloy by adding the calculated amount of this hardener. The alloys proved to be quite stable in composition, unless overheated, and, with reasonable temperature control, required no cover or flux to prevent loss of titanium content by oxidation. HOT-ROLLING TESTS Three alloys containing, by analysis, 0.05, 0.12, and 0.23 per cent titanium were selected for preliminary study. Slab cross sections revealed a marked grain refinement* (Fig. 2) in the two alloys of highest titanium content. Cast unalloyed zinc has a columnar grain structure similar to that shown for the alloy of lowest titanium content but without the scatter of small equiaxed grains at the center.

Jan 1, 1944

By R. M. Williams

Introduction Ring roller mills are efficient size reduction machines embodying the following machine functions: 1) Size Reduction: from a feed size of 2 in. to various size products as fine as 400 mesh, or granulation from 2 in. to 6 mesh containing a minimum of fines. 2) Drying: fluid bed drying of wet feed materials. 3) Conveying: negative pressure air system results in dust-free conveying. 4) Beneficiation: liberation and removal of foreign materials from the auxiliary bottom discharge simultaneously while grinding. Operation Operation of the roller mill system, Figs. 78 and 79, is completely automatic. A feeder introduces raw material into the grinding chamber in the base of the roller mill at a rate determined by pressure variations within the roller mill as material is ground and air conveyed away. The feeder will be activated by the reduced static pressure and introduce unground material into the system, thereby maintaining a constant differential pressure. Plows located ahead of each grinding roll direct the material upward and between the grinding rolls and the bull ring where it is ground to size. The grinding rolls are free to swing out centrifugally, which forces them to bear upon and grind the raw material. Being free to pivot axially, the rolls automatically assume the proper position for grinding and need no adjustment to compensate for wear. Rotation of the rolls is by rolling contact. Once ground to size, material is swept out of the mill by the controlled air flow from the centrifugal main mill fan. Air suspended, the ground material passing through the adjustable spinner separator. In the separator, an accurate size classification is made which allows product-size material to be conveyed away from the roller mill while oversize material is returned internally for additional grinding. By varying the speed of the separator drive, more or less cyclonic action is achieved at this location, effectively controlling product size. Product sized material is removed from the airstream by the cyclone collector. Typically, a conveyor or product storage bin will be located to accept the product as it exits from the bottom of the cyclone collector.

Jan 1, 1985

By P. K. Fedotov

At projecting mining-concentrating complex at the deposit ?Zapadnoye? (Russia) it was considered to enable an opportunity of refusal from conventional SAG-mills. First time a scheme of gold bearing ore destruction using Roller Press RP 5-100/90 had been developed and integrated. The plant was launched in summer 2003 and presently it has achieved designed technological parameters, processing throughput comes to 1 million tons of the ore per year.

Jan 1, 2014

By Dr. -Ing. Wolfgang Pietsch

Many primary metallurgical wastes are in the sh.-ape of turnings; borings, chips, dusts, and other particuletes. While such. materials can be easily segregated and/or upgraded to yield high quality ?secondary metals with often known composition for easy recirculation into the production? process; their particulate nature results in various problems. Roller presses are used in an ever increasing number for size enlargement and densification of primary particulate metallurgical wastes for secondary metal recycling. The paper will mention the areas of application from A(luminum) to Z(ink), also including Brass; Cast Iron, lead, and Stainless Steel, as well as dusts from all types of melting and ladle furnaces or converters. Typical systems using roller presses for size enlargement. will be discussed.

Jan 1, 1995

By Wolfgang Pietsch

Roller presses were first invented in the middle of the 19th century, for the economical size enlargement of coal fines as fuels. Coal briquettes became quickly accepted for industrial and domestic use giving rise to a large and sucessful industry, particularly in Europe, Japan, and North America. When, towards the middle of the 20th century, coal was more and more replaced by other energy sources, such as electricity, gas, and oil, roller press manufacturers searched for alternate applications of this equipment. In addition to contemporary coal briquetting, in fields such as smokeless fuel and form-coke, it was found that redesigned and modernized roller presses, which are now capable of exerting high forces, are versatile machines for many tasks in mineral processing. Today they are used for: - the "classic" pressure agglomeration and - the "new" high pressure comminution. In pressure agglomeration, the characteristics of fine minerals are improved by forming briquettes or granulated products from compacts. During size enlargement with roller presses briquettes are directly obtained while granular materials are produced by crushing and sizing of compacted sheets. The processes are carried-out essentially dry and often do not require binders other than those inherently contained in the feed and "activated" by the high forces and/or elevated feed temperatures (e.g. hot briquetting). Therefore, no foreign materials (impurities) are added. Another advantage of the technology is, that wide particle size distributions are acceptable or desirable as feed materials, including millimeter or even centimeter sized particles. Plastic particles deform and brittle materials are crushed during pressure agglomeration. A relatively new application of roller presses in mineral processing is the utilization of the crushing effect when brittle materials pass the nip area between the rollers. It was found that this crushing mechanism is very efficient thus saving energy, particularly in grinding circuits handling large capacities. The paper introduces the fundamentals of the process and describes the design as well as applications of modern roller presses in mineral processing.

Jan 1, 1995

By Carl H. Samans

THE INFORMATION AVAILABLE on the rolling characteristics of the precious metals-gold, silver, the platinum metals and their alloys-is incomplete and mostly from scattered sources. In the present paper an effort has been made to assemble and correlate it and to fill in some of the gaps that exist. GENERAL ROLLING CHARACTERISTICS SOME EFFECTS OF IMPURITIES Gold and its alloys are generally considered to be hot short and hence are usually rolled cold. Cold rolling of the yellow, green, and pink gold alloys. Which customarily contain gold, silver, copper and zinc and frequently some nickel as well, introduces no new problems since reasonable reductions are quite feasible and the alloys show little tendency to fire crack in subsequent annealing. The white gold alloys. which usually contain little or no silver and 10 pct or more nickel, are very susceptible to fire cracking1 and hence wrist he given relatively heavy reductions, i. e., 8-10 pct or more per pass with a total reduction of about 50 pct between anneals, to minimize this tendency. In addition, it is preferable to keep the bar as flat as possible during rolling. Although no comprehensive study appears to have been made of the effects of impurities on the cold rolling characteristics of gold alloys, the observations of Nowack2 on the effects of small

Jan 1, 1948

By William Marsh Baldwin

THE ROLLING OPERATION proper is applied to metals and alloys not only in the production of flat products but also in the production of shapes, rods, wire and even in specialized forms in the production of tubes. The present discussion of rolling copper and copper alloys will be [ ] limited to a consideration of rolling flat products such as strip, sheet, foil, plate, and others. In this case (as in the others listed above), the rolling operation itself is only part of an integrated sequence of operations. In Fig I such a sequence going to make up a brass strip mill is sketched out. It is seen that the rolling opera-

Jan 1, 1948

By Paul Riches

Today’s steel producers face the dual challenge of ensuring on-time delivery and ever demanding product requirements, while also running a lean operation. Every day the management of a long rolling plant requires continuous optimization of both operating and business practices. Imagine a long rolling facility, where individual pieces of equipment communicate with each other, where sensor information can be used not only for control purposes but to also monitor the condition of the equipment, where models are used to verify the process is within working limits and the equipment raises alerts to operators when it requires maintenance! Utilizing the ongoing evolution in technology though data collection, communication, internet of things, control techniques and smart sensors, there is now more information available than ever before. The collection and analysis of this information will both advance control and monitoring of plant performance; revolutionizing long rolling mill plants worldwide and optimizing the entire value chain, along with improved and more flexible production.

Oct 30, 2017

By Atalla YM

Steel rolling mill product finishing pro cesses gradually become or often already are unsuited for current production and marketing conditions. Indications are made as to what has been done to (i) rectify situations of this kind and, (ii) to reduce both product finishing time and costs. The principal features of two separate case studies are reviewed, these being (a) the finishing-end of B.H.P.'s Newcastle o.2 Merchant Mill and, (b) a mixed functions finishing yard and warehouses group (known as he Merchant Mills Loading Yard) which has been perating for a number of years. The areas in ach case are identified as a system while the arious functions, principal product streams nd processing equipment are respectively iden- ified as sub-systems and system elements. etails are given of the models used in each Sub-system dependency on the system as a le is traced by means of an information and ision analysis or by time studies and the sonableness of the system elements is deter- ed by computer programming or by simple com- ison methods. The-accumulated data is used derive improved mill finishing-end or Load Yard,functioning concepts according to pro- rules whilst at the same time considering

Jan 1, 1975

By W. F. Boericke

THE recent completion by the United States Aluminum Company of a $4,000,000 addition to its plant at Massena, N. Y., consisting of a large blooming mill and structural mill, gives this organization, a subsidiary of the Aluminum Company of America, the distinction of possessing the largest aluminum rolling mill in the world, as well as the first mil1 in this country to roll aluminum exclusively. The plant is located near the international boundary line between Canada and the United States, about 3 miles from the St. Lawrence River, to take advantage of the development of cheap hydroelectric power which is needed not only for the manufacture of structural shapes from the ingots, but in the reduction of alumina to the metal by the well-known Hall process as well. A power canal from the St. Lawrence River to the power house on the Grasse River at the plant provides for the waterflow, which, coupled with a drop of 47 ft. in 2% miles, generates 80,000 hp. through vertical turbines. An additional 60,000 hp. is purchased.

Jan 1, 1930

By WILFRED SYKES

THE story of the rolling of strip steel is not limited to any one plant or individual or group of individuals. It is a story with many ramifications. First of all, it should be understood that the strip mills we are considering are continuous mills, in that the steel passes directly from one mill to the other in a more or less straight line. Continuous mills are not new; in fact, they have been used for many years in the rolling of a few simple shapes. They were, however, driven by one motor through jackshafts, and as a result the speed of each roll stand had a fixed relation to that of every other stand in the series. This in turn fixed the reduction that could be made in each stand. The mill could produce simple things, but was not satisfactory for the production of the variety of strip now required. It was, therefore, necessary to get away from the restrictions of that kind of drive. To accomplish this, the designer could either separate

Jan 1, 1936

By G. L. Liu

"Deformation Banding ( DB ) in cold rolled mild steel has been experimentally established by microstructure investigation. Deformation banding model includes such deformation mode when it is applied to rolling texture simulation. The cause for the occurrence of deformation banding is the reduction of the total work for plastic deformation through a relaxation of the deformation constraints. In the first DB model, all grains are assumed to band from the first deformation step. Such an unrealistic assumption has been eliminated in the new model by the introduction of a banding criterion based on an energy minimizing approach. The prediction is closer to the measured texture by applying banding criterion and setting critical resolved shear stresses (CRSS) ratio for { 110 } and { 112 } slip modes to 0.85.IntroductionBased on the continuum theory of plastic flow and deformation mechanism of crystallographic dislocation slip, Taylor's FC ( Full Constrain ) theory [1] has been widely used in texture modeling. As the process of cold rolling of sheet materials produces a microstructure consisting of elongated or equiaxed flat grain or cell, the ""lath"" and ""pancake"" relaxed constraints ( RC ) models [2, 3] were introduced as the successful improvements over the classical FC model. It has been also recognized that crystals may split into different orientations during deformation and the term deformation banding is used to describe such deformation processes [4, 5]. Lee et al. [6, 7] pointed out that the success of the RC theory in predicting textures depends on the physical processes of deformation banding. They developed so called Deformation Banding ( DB ) model by considering DB in the longitudinal plane to be accounted for by the RC method and allowing DB in the rolling plane. DB model was applied to simulate the texture development in bee case [8], the predicted bee rolling textures are in reasonable agreement with the measured textures. In the first DB model, however, all grains are assumed to band right upon the first deformation step. A banding criterion was formulated [7] which states that DB will occur if the work used in DB model is less than that in RC model. Such criterion has been incorporated into the original DB model for texture simulation and is referred to as DBC ( Deformation Banding Criterion ) model."

Jan 1, 1998

By A. L. Holley

IN order to put sufficient work on steel ingots for rails, they must be reduced from about 12 inches square. As this cannot be done at one heat, they are first drawn down to about 7 inches square, and then reheated and rolled into rails. This first reduction or " blooming," is usually done in this country in a 30-inch 3-high rolling-mill, with movable rolls, so as to get several reductions in each set of grooves. The first of these mills has been running at the Troy Steel-works above a year, with great success. Another at the Cambria Iron-

Jan 1, 1873

By R. S. Shepard

A quick glance at a-portion of the title of this discussion -'Rolling With The Punch" may immediately lead you to assume that I am about to expound on the so-called manly art of self-defense. So that you will not have been misled entirely we will devote our considerations to a far more important art and if I may, I should like to begin by quoting Vincent Van Gogh. According to a literal translation the artist in describing one of his famous paintings said "these peasants are eating their potatoes with those very hands that dug them from the earth' and put them in the dish". Vincent Van Gogh may not have realized at that time, that he could likewise have been describing what is probably one of the oldest of all arts - the art of Material Handling - an art that man with the aid of science has tried to improve since the beginning of time.

Jan 1, 1963

By Karl Berger

The paper gives a comprehensive overview of the historical development of various metal rolling technologies and also describes the influence to industrial and socio-economic developments. The rolling of steel, in particular of rails, beams, rebar, strip and plate has enabled the large scale transport and travel, the building of bridges and buildings, the manufacturing of ships and cars. All this has changed the face of the world significantly. Further the paper approaches technological highlights in the design, manufacturing, drive and control of modern mills and the various types developed to create industrial economic units for the different markets and customers’ requirements. An outlook of future challenges is as well discussed in the paper. Various solution approaches for the rolling technologies, from continuous improvement of existing plants to more radical new concepts like endless rolling, near net-shape casting and rolling are approached. A positive conclusion is drawn that rolling technologies will remain a valuable area for engineers with scientific and economic challenges, but also a clear vision for positive contribution to further industrial and social development.

Jul 30, 2018