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By D. Rylander

The operation of Quarry and Aggregate sites are similar to factory production, since it contains sequential production processes, tasks and activities to produce the output product. Compared to the plant though, the quarry processes are generally not synchronized and controlled towards the overall throughput of the site in real time. Some quarries control parts of the production but do generally not utilize real-time technologies for the whole site and all its activities. This fact indicates a general improvement potential in increased productivity at quarry sites, but also unsolved challenges for the same reason. The main contribution of this paper is the presentation of a Lean based method for how to describe the processes to identify control improvement potential within a site. The aim of the identified improvements is to increase overall site productivity by optimizing site, fleet and machine utilization towards the overall throughput, and minimizing operational expenses and inventories. Further the paper exemplifies the method?s usability with field studies at operational quarry plants successfully identifying and quantifying potential wastes and improvements. In addition the identified productivity improvements based on increased control and automation indicate challenges and needs in wireless communication and sensing technologies.

Aug 1, 2013

By J. George Gregr

"This paper gives a brief review of grinding mills installation procedures with special emphasis on future maintenance. The importance of cooperation between the customer, construction contractor and manufacturer's representative is discussed, as well as the imparlance of complying with standards, specifications and the keeping comprehensive installation records.Fundamentals of mill maintenance are explained with the aim being to maximize the equipment availability and to minimize unscheduled downtime. The paper also includes development of wear items design, based on operating conditions, drive components and bearings, and how to keep large gears healthy thus eliminating surprise failures.Experience with installation of a large gear on a 34-foot diameter mill in Lornex and successful application of a computer program for the gear alignment on the mill are given.IntroductionSuccessful operation of a concentrator begins with the engineering of the project and continues through selecting the right equipment, its installation , start-up period, and ends with final tuning of the process. machinery and the human factor into an efficient and viable industrial complex.The following is a brief review of grinding mill installation procedures with special emphasis on future maintenance. Fundamentals of mill maintenance are discussed with the aim being to maximize the equipment availability and to minimize unscheduled downtime, with some specific points on key grinding mill components such as bearings and drives.Finally, the experience is recounted with the installation of a large ring gear on a 34-foot diameter mill at Lornex, and the successful application of a computer program for the gear alignment on the mill."

Jan 1, 1985

By S. Akhlaghi

In many electronic/optoelectronic devices, interaction between the metal stack and solder is undesirable. If a reaction happens, a nonuniform joint containing spikes and voids is likely to form and as a result the heat dissipation deteriorates significantly, which in turn, leads to the degradation of the bond. In the present work the interaction between Ti/Mo/ Au metallization system, which was sputter deposited on AlN substrates, and Pb-Sn solder was studied by using scanning electron microscopy (SEM). Also, an EDX system was used to trace the changes in chemical composition of the layers after solder tests. The microstructural examinations show that the Ti and Mo layer from the Ti/Mo/ Au metallization system are not impermeable enough and thus Ca from the surface of the substrate moves all the way up to the interface of Au/Mo and forms an intermetallic at the interface, which grows over time.

Jan 1, 2006

By Yu Chen, Charlie C. Li

The application of rock bolts for the stabilisation of underground openings needs a good understanding of the response of the bolts during rock excavation. The pull-and-shear performance of two types of rock bolts—that is, the fully encapsulated rebar and the D-Bolt—has been studied both experimentally and numerically. The rock bolts were tested under a pull-and-shear load at five displacing angles (i.e., 0°, 20°, 40°, 60°, and 90°), and at the same time, the strains on the bolts were monitored during testing. The two types of rock bolts have similar loading capacities, while the loading angle has obvious influence on the deformation capacity of the D-Bolt. The ultimate total displacement of the D-Bolt decreases from 140 mm under pure pull loading to 70 mm under shearing. The displacement capacity of the rebar is not significantly influenced by the loading angle but remains at a quite low level from 29 to 53 mm. The D-Bolt yielded in a longer section the rebar bolt under pure shear. A trilinear material model was used to simulate the strain hardening behaviour of the bolt steels in the numerical code FLAC3D. The numerical results show that the axial load in the bolt decreases exponentially with the distance from the loading position for the rebar bolts, but it remains constant in the bolt sections between the anchor positions for the D-Bolts. When the bolt is subjected to a lateral load, shear stresses are created on the D-Bolt surface within a short distance from the loading position.

Jan 1, 2015

By Olav Mejia

The rising energy costs and environmental considerations in mining necessitate the development of energy-efficient copper and gold processing plants. This paper presents an analysis of technical strategies aimed at reducing energy consumption in these plants. Key approaches include the integration of advanced ore sorting technologies, High Pressure Grinding Rolls (HPGR), Coarse Particle Flotation (CPF), and high-intensity flotation. Ore sorting enables early-stage waste removal, reducing the downstream processing load and associated energy use. HPGR technology, recognized for its energy efficiency, contributes to significant energy savings in comminution circuits by reducing reliance on traditional grinding methods. CPF technology further optimizes flotation performance by enabling the recovery of larger particles, thereby decreasing the need for fine grinding and reducing overall power demand. High-intensity flotation units enhance separation efficiency and mineral recovery in a compact footprint, offering further reductions in energy consumption. Together, these technologies provide energy saving opportunities to achieve a more sustainable and economically viable processing operation. This paper evaluates the effectiveness of each method, highlighting their potential impacts on energy consumption, operational efficiency, and cost-effectiveness in copper and gold processing

May 4, 2025

By J. M. B. Scarborough

This paper deals with measures taken to maintain effective operation of heavy-duty equipment in open-pit mining. at Pine Point, N.W.T., during periods of extreme cold weather. The points covered include equipment modifications designed to improve cold-weather performance, effective lubrication of machinery that is vulnerable to extreme cold and operating procedures designed to prevent equipment damage.

Jan 1, 1966

By Graham A. Davis, Michael Samis

The dramatic fluctuation in metal and energy prices in the last few years is causing mining companies to consider alternative analytical methods for mine design and valuation. The goal is to improve insight into unforeseen changes in the economic and project environment and to design projects that take advantage of management's ability to respond to these changes. Such flexibly managed projects will contain value that cannot be measured using traditional engineering economic approaches, further motivating the used of alternative, modern valuation methods. This paper considers the valuation of an uneconomic low-grade resource at an open pit gold mine using two of the most popular modern valuation methods, Dynamic Discounted Cash Flow and Real Options. Our analysis demonstrates that the conventional valuation method may incorrectly represent the value and risk attached to mining this type of resource because it is unable to recognize management's ability to respond to future events in a manner that minimizes losses and exploits advantageous business conditions. The results of this paper highlight the importance of recognizing flexibility and business uncertainty in both mine design and valuation.

Jan 1, 2003

By Walter Greaves

THIS paper describes a series of tests performed at the Hollinger mill during the past four years, in which both metal and rubber-lined pumps were used for pumping sand and slime. While conditions will not be the same at other mills, it is felt that the information gained from the tests should be of value to other operators and of assistance to them in selecting the most efficient size of pump and kind of lining for economical operation. For the successful operation of pumps with rubber linings there are certain conditions, which, if recognized at the outset, will save the operator a good deal of work and trouble. First is the necessity of keeping sharp pieces of steel, or anything that might cut the lining, out of the pumps. This can be effected by placing screens in the proper locations. Second is to recognize the fact that the rubber lining of the shell, and the rubber cover of the impeller, are subjected to very different conditions. The shell lining, :being at rest and well supported by the metal case, has a relatively easy job compared ? with the impeller covering, which is subjected to centrifugal force and has a tendency to tear itself away from the metal core. Also, the pulp travels through and past the impeller at a high velocity. These two factors, centrifugal force and velocity of the pulp, would appear to set a limit to the speed at which, for a given set of conditions, it is economical to run a rubber-covered impeller. Therefore, a pump should be large enough for the work to be done. To get the best mechanical efficiency, it must be operated somewhere near the limit of its capacity, but this may not give the best overall cost, because the saving in power, due to the high efficiency, may easily be lost through excessive wear on the lining. It would appear that this condition is more critical in a rubber-lined pump than in one lined with metal.

Jan 1, 1939

By Adam Jordens

Along with gravity separation and froth flotation, magnetic separation is one of the most common techniques for separating minerals. Minerals are separated by a magnetic force that is dependent on a combination of the applied magnetic field, the magnetic field gradient and the magnetic properties of the minerals themselves. Minerals may be classified as diamagnetic, paramagnetic or ferromagnetic based on the way they interact in a magnetic field. The magnetic susceptibility of a material may be determined by using a vibrating sample magnetometer to determine the magnetic moment of the material in an applied magnetic field and then converting this measured moment into the material?s magnetic susceptibility. In the case of rare earth minerals, magnetic separation is commonly used to remove ferromagnetic iron-bearing gangue minerals and to concentrate paramagnetic valuable minerals such as monazite and xenotime. These magnetic separation steps are frequently preceded by a gravity separation step as many iron oxides and rare earth minerals have specific gravities that are much larger than those of typical gangue minerals. By varying the magnetic field intensity it may be possible to use magnetic separation to selectively separate the paramagnetic and ferromagnetic minerals that report to the concentrate after gravity separation. Test work on a Canadian rare earth ore has shown that a gravity concentration step using a Knelson concentrator was able to selectively concentrate heavy magnetic minerals as evidenced by increased recoveries, relative to the Knelson tailings and fresh feed, after processing through a wet variable intensity magnetic separator. Mass pull to the Knelson concentrate was 4.5 % and the magnetic recovery of this concentrate, at 0.94 T, was approximately 40 % higher than the magnetic recovery from the Knelson tailings (70 % versus 30 %). The products of the wet high intensity magnetic separation were also analysed using a vibrating sample magnetometer to determine the magnetic susceptibilities of the various concentrate and tailings products.

Aug 1, 2013

By Barry W. Schmitke, J. M. Marino

"Cigar Lake Mining Corporation is presently operating an underground test mine in northern Saskatchewan, with a view to developing a high grade uranium deposit. The mining test is intended to demonstrate that the innovative mining methods designed are safe and economical. Two vertical mining methods are considered for the test:• box hole boring from the lower level;• blind boring from the upper level.In both cases, it is anticipated to freeze the ground before excavation to ensure hole stability and limit the inflow of water. Special care will be taken to minimize radiation exposure of personnel.Remote controlled equipment will be used where applicable.The access to the orebody was an important component of the test. After shaft sinking to a depth of 500 m, development work commenced at the 420 level in fractured sandstone which was grouted to restrict the inflow of formation water. The drifting continued in a section of poorly consolidated sand, clay and sandstone; this area was frozen to allow stabilization prior to excavation. At the 480 level relatively little water was encountered in the altered basement gneiss and grouting was not necessary; however, extensive ground support was required in the soft ground areas."

Jan 1, 1992

By T. Joseph, E. Zheng, M. Curley

"Hydraulic transportation efficiency and production optimization are considerations in the surface extraction of Athabasca oil sand deposits. To reduce the dependence on haul trucks, it is possible to extend the hydraulic transport system to production faces using a mobile at-face slurry system (AFSS). The flexible arrangement of connected pipelines transports slurried minerals from the mining face to the processing plant. An experimentally verified mathematical model indicates the friction loss of oil sand slurry associated with the AFSS. Laboratory-scale testing enables extended analyses for examining pipeline slurry transport in an oil sands environment.RÉSUMÉ L’optimisation de l’efficacité du transport hydraulique et de la production sont des considérations importantes dans le domaine de l’exploitation à ciel ouvert des gisements de sables bitumineux de l’Athabasca. Afin de réduire la dépendance envers les camions de transport, on envisage d’étendre le système de transport hydraulique aux fronts de taille à l’aide d’un système mobile de transport des matériaux sous forme de boue à partir du front de taille (AFSS, de l’anglais at-face slurry system). L’organisation flexible des conduites reliées permet le transport de minéraux à l’état de boue du front d’exploitation jusqu’à l’usine de traitement. Un modèle mathématique vérifié de manière expérimentale indique la perte de charge par frottement des schlamms provenant du traitement des sables bitumineux associée à l’utilisation de l’AFSS. Des essais en laboratoire permettent de mener des analyses approfondies portant sur le transport de boues dans des conduites dans un environnement de sables bitumineux. INTRODUCTIONObjectives and scope of studyThe at-face slurry system (AFSS) concept has become a competitive means for materials handling to optimize haulage system efficiency and cost. The mobile and flexible arrangement of the AFSS introduces a unique set of hydraulic transport problems. This paper will focus on developing the mathematical models governing the friction and head losses within the AFSS concept.Background of the problemLarge-capacity shovels and dump trucks are increasingly used for excavation, loading, and hauling in the operation of surface mining. Production cost and efficiency optimization are demanded during the Athabasca oil sands (Alberta, Canada) mining process to secure North America’s energy supply. Increasing haulage distances, rugged terrain, and a constrained mine environment are conditions that will reduce the effectiveness of the shovel-truck haulage system (Frimpong, Szymanski, & Changirwa, 2003). In such conditions, the tire heat index and weight, distance, and time limits for truck haulage can be exceeded, simultaneously creating extreme tire wear and high maintenance costs. In addition to low production cost and equipment effectiveness, a mining environment also requires efficient waste-material recycling and distribution. Waste materials need to be recycled from the processing plant to a new destination such as a tailings dam, or replaced in mined-out areas such as backfill. The Athabasca oil sands configuration and location characteristics result in a mining environment that would benefit from flexible pipelines for constant production and an efficient waste-material recycling process."

Jan 1, 2017

By B. J. Fryer, R. P. Taylor

"As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth element s (LREE), reflecting their high pH, low fluid/rock ratios, and the dominant role of CI- complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F - and CO, 2- become important in metal (e.g. Mo, W,) transport through complexing, and their activity in the hydro thermal fluids is illustrated by mobilization of the heavy rare earth elements (HREE).The relative involvement of CI- versus F - versus CO32- in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F' and CO32- in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geo chemistry, particularly when integrated with fluid inclusion and isotope studies, can provide (1) an effective method for identifying the physicochemical controls of metal transport and (2) a useful criterion for elucidating metal distribution."

Jan 1, 1983

By D. J. Scarpato

"Slope construction in shale can present some interesting challenges for geotechnical design engineers and contractors alike. There are challenges that can be expected and designed-for; however, all too frequently, such challenges manifest themselves as “surprises” in the field. Common constructability challenges can include those such as drill hole deviation during drilling for controlled blasting; and, excavation slope instability arising from inconsistent perimeter control drilling. Drill hole deviation results from the cumulative effects from both drilling mechanics and rock mass conditions. Once a hole has initiated the deviation trajectory, it is difficult to rectify drill steel position. Although such challenges are not necessarily unique to shale, they are often exacerbated by weak, weathered and transversely isotropic nature of bedrock conditions. All too often, the working assumption is that shale is “soft” and easily excavatable; however, this blanket assumption can prove to be costly. This paper is intended to provide design professionals and contractors with the practical considerations needed to avoid the “surprises” associated with drill hole deviation, and minimize the potential for costly claims.INTRODUCTIONFor all the slopes that have been excavated worldwide, and for such advancements in excavation technology and field characterization, one might be tempted to believe that the industry almost has slope development down to a science. This is frequently not the case, especially for weak/weathered and anisotropic bedrock. Excavation contractors are still pushed to the limits of what their technology can achieve, and engineers are all too often called to the field during construction, to make potentially risky onthe- fly decisions relative to excavatability, short and long-term slope stability, and project safety. Although there have been a host of other research papers and journal articles that have been written on the subject of deviation over the past 30 years (Brown, Geen, Sinha, 1981), the problems associated with drill hole deviation are still all too frequent. This fact is especially true for civil engineering surface excavations in bedrock."

Jan 1, 2015

By Don McColman

"Tires, although not always the largest single cost item in open-pit mining operations, will place in the top three, along with explosives and fuel. How this high-cost supply is controlled is dependent upon on an efficient tire program. The success of this program is, in turn, dependent upon the people who are directly associated with tires and their use, namely: the mine's tire personnel, the tire sales representatives and a technician for the rubber company. The technician will relay his observations and information received from the mine personnel back to the manufacturer with recommendations to overcome current problems .Haulage truck tire life and costs in a hard rock open-pit mine are governed and controlled by four important factors:I) Field control.2) Operating within manufacturer's guidelines.3) Different tire purchasing methods.4) Scrap piles.Field ControlPerhaps the most influential people involved in this program are those who live with the tire through every hour of its lifespan: the truck driver, the shovel operator, the dozer operator, the grader operator and the shift boss. Of these, the truck driver has the most control, in that he can drive over or around rock s as these situations arise. The loading area, the edge of the haul road and the dump account for most of the tire injuries.This is why shovel, dozer and grader operators must appreciate their influence on haulage tire life. Spillage cleanup must be ongoing and is not being done adequately if any of these operators are idle. The shift boss that drives by a rock on the road without removing it or calling for a cleanup has little recourse with the truck driver who runs over it-he has sanctioned the driver's actions by his own neglect."

Jan 1, 1986

By W. S. Tremaine

When the Hedley Mascot mill was built in 1935, it was designed as a straight flotation plant. The ore to be treated at that time was a gold ore in which the gold was intimately associated with arsenopyrite and pyrrhotite in highly silicified and garnetized limestone gangue. This material was ground to 85 per cent minus 325 mesh in two-stage grinding and floated in standard flotation cells to produce about a 5-ounce concentrate, which was shipped to Tacoma smelter for refining. This arrangement gave us a recovery of about 89 per cent. Test work indicated that the best way to improve this recovery would be to build a cyanide plant to treat our flotation middling. Arrangements for the construction of this plant were finally approved and work on it was started in the spring of 1940. This plant was of the conventional type in which the flotation middlings were thickened, filtered, and then put through the usual cyanide process. Its capacity was 50 tons of middlings per day. This arrangement worked quite satisfactorily and gave us an increase in overall recovery of 4 per cent. Unfortunately, about the time the plant was completed, we developed, and started to ship to the mill, ore that differed entirely from that met with up to that time. Instead of being hard, it was very soft, the orebody from which- it came being much faulted and brecciated. In many sections, the sulphides were oxidized and the breccia was filled in with a very soft, hydrous iron silicate known as chloropal. When this new ore was mixed with the old ore and sent to the mill, the whole operation was disrupted. The chloropal slimed so badly that the classification, flotation circuits, and cyanide plant would not handle it. The difficulty in the cyanide plant was at the head end, where the 10 ft. by 20 ft. thickener and the 8 ft. by 8ft. drum filter would not handle the middlings containing a large percentage of primary slime and chloropal. This material would not thicken to more than 30 per cent solids in the thickener and, when pumped to the filter, would forma very thin, slimy cake. Overall recovery dropped to between 83 and 84 percent and it was quite apparent that some extensive changes would have to be made in our flow-sheet before this ore could be treated successfully.

Jan 1, 1947

By J. G. Bensley, K. S. Detheridge

"Many plants use computers for process control and most have computerized Management Information Systems but few have been able to have these systems interact with one another. Developing this system interaction is not a one-step process but requires careful planning and implementation. This paper describes two projects that were implemented to provide the bridge between the process control and management information systems of Cominco Limited. Both projects include the replacement of essentially process control systems installed in the late 1960s. These original systems provided an enhanced level of control in the form of Direct Digital Control (via computer/manual analogue control stations) and a management reporting capability of process data. The experience gained from the use of these systems over a period of fifteen years formed a basis for the evaluation and planning for the new systems. The new systems were commissioned in 1985 and 1986 and operating and further developments leading to a totally integrated process information and control system are underway. INTRODUCTIONThe concept of hierarchical control involves a control structure consisting of a number of defined levels. Each level performs a defined function with information consolidated and combined as it moves up through the hierarchical structure. The commonly accepted structure of a hierarchical control system echoes the structure of the plant which is being controlled. Referring to Figure 1:Level 0 - Sensors and ActuatorsSensors and actuators, such as thermocouples and flow control valves, interface directly to the process and are generally connected directly to the controllers or multiplexers at Level I.Level 1 - Regulatory ControlThis level provides basic PID control (proportional/integral/ derivative) typically using microprocessor based controllers and programmable controllers for digital control of motors and machines. Systems at this levelare usually segregated by plant unit, e.g, crushing, flotation, drying. Control is concentrated on achieving optimum conditions for a particular feed rate."

Jan 1, 1989

By M. Lahtinen, B. Saxén, M. Latva-Kokko

The conventional jarosite precipitation process with neutralization by zinc calcine is widely utilized in the zinc industry. However, it has a significant drawback of causing losses of valuable metals like zinc, lead and silver to the jarosite. This comes mainly from the content of these metals in the calcine used for neutralization. As the zinc plants today want to maximize metal recoveries and minimize the amount of residues, this matter has become more and more relevant for zinc producers. Outotec developed and patented in early 2000 an improved version of the jarosite precipitation process in which the need for neutralization can be minimized, thus the metal losses to the jarosite also can be minimized. At the same time, the iron content of the jarosite increases and the amount of produced jarosite is smaller. The main feature of this process is to start the precipitation from ferrous iron after having reduced all the iron by zinc concentrate in a separate step before jarosite precipitation. Iron is then oxidised back to the ferric form simultaneously with jarosite precipitation. By this method, the formation of sulphuric acid is only half that compared to the conventional method and the need for calcine for neutralization can be avoided. High mixing and oxygen dispersion capability are needed in this jarosite precipitation process. Such capabilities are found in the Outotec OKTOP® reactor series. High performance reactors are not only needed to generate high quality precipitates, but also to maximize oxygen utilization; i.e., to minimize operation costs. Outotec’s latest development in this area is the OKTOP® plant product in which not only the reactors, but also all the accessories are designed, manufactured and delivered by Outotec. One responsible supplier ensures efficient and fast delivery and can provide mechanical and performance guarantees for the entire plant unit.

Jan 1, 2016

By G. A. Peebles

"This paper describes the various types of radiometric instruments and the techniques of their operation for grade control, sampling, assaying and probing drill holes at Eldorado Nuclear's uranium mine in northern Saskatchewan. Modifications that have been made to these instruments are discussed, and suggestions are made for the development of more refined and specialized radiometric equipment."

Jan 1, 1969

By C. Bazin

"Discrete transfer functions which use the grinding circuit feed tonnage to predict mass flowrates at reagent addition points in the flotation circuit were calibrated using a dynamic grinding/flotation simulator. Predicted values are multiplied by g/t ratios to calibrate reagent flow. The transfer functions are currently integrated into the distributed control system at Les Mines Selbaie.INTRODUCTIONThe development of adequate tools for the control of flotation processes is a continuous challenge. Since the early 1970's there have been numerous publications dealing with practical applications of flotation process control. A review of that literature shows that basic feedback and feedforward controls are the two preferred strategies for flotation processes. Some advanced control schemes started to emerge (e.g. Zaragoza and Herbst, 1988). Feedforward and feedback aim at reducing the effect of the following flotation process disturbances (e.g. McKee, 1991):0 Changes in throughput;0 Changes in feed grade;0 Changes in particle floatability (size, liberation, surface oxidation ... );0 Deliberate changes of set-point;Feedforward strategy acts on manipulated variables, mainly reagent addition, to attenuate the effect of disturbances such as changes of feed rate and grade. The feedforward strategy is driven by measurements of disturbances. Feedback control acts to compensate unmeasured disturbances, such as ore floatability, and to bring process variables to targeted set-points of concentrate or tails grades. The feedback control action is driven by set-point error, caused by either a deliberate change of set-point or unaccounted disturbances.This paper proposes a way to improve feedforward control schemes by addition of a simple model of solids transportation. The feedforward strategy considered in this paper is of ratio type, i.e. the manipulated variable is changed according to a predefined ratio between this variable and the measured disturbances. A typical example is the ratioed reagent addition to mass flow of ore."

Jan 1, 1993

By J. Lu, J. B. Wiskel, D. G. Ivey, E. Niemi, H. Henein

Simulated TMCP using a Gleeble was undertaken to evaluate the effect of the austenite to ferrite cooling rate, coiling temperatures of either 400°C or 500°C and the magnitude of plastic deformation at the coiling temperature on the hardness of a Grade 483 (X70) steel. For comparable apparent cooling rates and deformation conditions, the hardness of the samples were independent of coiling temperature The application of a minimum compressive deformation > 8% was required to increase hardness at both simulated coiling temperatures of 400°C and 500°C. An increase in hardness was also observed with increased cooling times between 800°C and 500°C (i.e., slower cooling rates).

Jan 1, 2005