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By A. Ersoy, M. D. Waller

Because of a shortage of diamonds for the drilling industry in the 1970s, efforts were made to develop synthetic diamonds. The resulting development of polycrystalline diamond compacts (PDC) enabled the evolution of a new generation of rotary-drilling drag bits. Bits based on PDC cutters were very successful in drilling soft, abrasive and medium strength rocks. However, because of their thermal instability, they failed rapidly when drilling hard rocks. Thermally stable diamond (TSD) was then developed for hard-rock drilling. The rate of penetration (ROP) and bit life significantly influence the drilling cost. The ROP and the life of the TSD bits or cutters are affected by a number of complex factors. However, in laboratory testing and infield operations, the principal factors that need to be considered in predicting drilling and wear rates are bit design characteristics, bit operating parameters and the characteristics of the penetrated rock. These characteristics are comprehensively reviewed for both laboratory and field drilling results using TSD bits. Optimization of these parameters increases the drilling rate, prolongs the bit life and reduces the drilling cost.

Jan 1, 1998

By J. E. Shigley

The gemological properties that allow natural emeralds and blue sapphires to be distinguished from other gemstones are summarized in this paper. A variety of synthetic and laboratory-treated emeralds and blue sapphires are also encountered in the jewelry industry today. Gemologists distinguish these latter materials from their natural counterparts based primarily upon features seen with magnification, such as inclusions and/or growth zoning. In some cases, however, these observations and standard gem-testing methods are insufficient, and the use of non-destructive analytical methods, such as optical spectroscopy and chemical analysis, are required for positive identification. The commercial value of synthetic and treated gems are much less, and can be insignificant in comparison to that of an important untreated natural gemstone. Identification of synthetic and treated gem material is essential to maintaining integrity in the jewelry industry. Loss of consumer confidence in the gemstones sold at the jewelry counter could have a negative impact on the exploration and mining of natural emerald and blue sapphire.

Jan 1, 1998

By Courtney A. Young

Cyanide is a critically important chemical to the mining and metallurgical industry. It has a strong affinity for metals making it favorable as an agent for metal finishing and treatment as well as a lixiviant for metal leaching, particularly gold. These technologies are environmentally sound but, because cyanide is very toxic, safeguards are required to prevent accidental spills and treat effluents before being discharged. Various methods of cyanide remediation by separation and destruction for cyanide management purposes are therefore reviewed. The methods have been broadly categorized as physical, -adsorption. complexation and oxidation methods including photolysis and other advanced-oxidation processes. Reaction mechanisms for these methods are presented throughout this paper, Finally, the methods are compared in regards to their effectiveness in treating various cyanide species: free cyanide, thiocyanate, weak-acid dissociables, and strong-acid dissociables.

Jan 1, 1998

By H. Y. Sohn, S. PalDey

"A new chemical synthesis process for the preparation of intermetallic compounds has been developed. It involves the vapor-phase reduction of mixtures of constituent metal chlorides by magnesium vapor to produce intermetallic compounds in the form of fine powder. The advantages of the process include (a) the use of inexpensive raw materials, (b) low reaction temperatures, and (c) products in the form of fine particles. Titanium and nickel aluminides were prepared by this method. The effect of AlCl/TiCl3 partial pressure ratio on the formation of different titanium aluminides was studied. A two-phase mixture containing 80 mol % of TiAl and 20 mol % of TiA13 formed at an AlC13/TiC13 ratio of 10. The amount of TiA13 was maximized to 72 mol% at an AlC13/TiC13 ratio of 16. The maximum conversion of the limiting chloride TiCl3 was 94 % . In the case of nickel aluminides, NiAI, NiAl3, and Ni2Al3 were formed by reducing mixtures of NiC12 and A1Cl3 vapors. The effect of the partial pressure ratios AlCl3/NiC12 and Mg/NiC12 on the formation of nickel aluminides was studied. The maximum content of NiAl obtained was 98 mol % . At the AlC13/NiC12 ratio of 19, a two-phase mixture of 17 mol% of NiAl and 83 mol% of NiA13 was produced. The product particles were very fine in the size range of 0.05 to 0.2 µm.A. IntroductionIntermetallic compounds are attracting much attention [1]. Titanium and nickel aluminides have attracted a great deal of attention from the aerospace as well as automobile industries because of their potential for high-temperature application (e.g., low density, good oxidation resistance, and high-temperature strength retention [2, 3]). Gamma TiAl and two-phase (TiAl and Ti3Al) alloys [4] are used for gas turbine engine rotational components as well as automobile exhaust valves. TiAl3 is one of the most extensively investigated aluminum-rich intermetallics. Nickel aluminides are attractive because of their low densities, relatively high melting point and good high-temperature strength properties. For example, Ni3Al shows increasing rather than decreasing yield strength with increasing temperature [5]."

Jan 1, 1998

By A. Dale Wunderlich

With the price of precious metals at an 18-year low, every ounce of metal produced is important. The theft of metals from mining and refining sites can mean the diffrence between profit and loss for many mining companies. Low metal prices do not reduce the potential for the theft of precious metals. History has shown that the price of gold has little to do with the desire for employees to steal precious or base metals. There is actually evidence that the theft of precious metals increases when the price of this commodity goes down. Several of the major precious metal thefts in the past year took place at silver mines when the price of silver was less than 16 cents/g ($5/oz). How does the lowest gold price in 18 years affect the need for security at precious metals properties? There is no short answer to this question. One reason is because the exposure to theft of precious metals is unique to each property. This makes it important that each property be evaluated individually. More than 95% of all precious metals thefts can be attributed to those working at the mine site. So preventing employee theft is the primary concern. One consideration is the location of the property. Gold selling at any price is still an attractive commodity in countries where the employees are making between US$400 and US$600 a month. It is not uncommon for employees at mines in countries where low wages are the norm to consider the value of a gram or two of gold to be a significant amount of money. A gram or two of gold a day may not seem like much. But if 15 employees steal two grams a day, that equates to a significant amount of money during a year. The type of property where the precious metals product is being recovered is also important. For example, a property with a gravity circuit is more likely to suffer from the theft of gold product than a property where all gold is finely disseminated and the only gold seen in the ore body is through a microscope. Gravity circuits increase an operation's exposure to theft because the grinding circuit that is associated with a gravity circuit often becomes a giant concentrator. Areas such as the bottom of grinding-mill pump boxes, cyclone-feed-pump clean out traps and the sumps often become locations where precious metals concentrate (Figs. 1 and 2). Muck concentrations in these locations can be as high as 25% to 40% of gold or silver. Not long ago, muck was removed from a barren-solution sump at a Merrill Crowe circuit that had concentrated to more than 40% gold. At a milling site in the Pacific Rim, residents of the community adjacent to the mine learned about the value of the concentrates in the sump under the ball mill and committed an armed rob¬bery. While several of their co-conspirators held the em¬ployees at bay with machetes, the others emptied the contents of the sump into buckets and removed it from the site. Armed robbery is not as common as employee theft. However, while this article was being written, an armed robbery occurred at a gold property in Central America. Armed perpetrators took as hostages the night shift employees at a process plant and used cutting torches that were on site to cut into the high-security and gold-storage areas. The perpetrators then stole a company vehicle to remove the stolen gold buttons and sludge from the site. Unfortunately, this type of activity goes on regularly. But managements of most mining companies are reluctant to discuss theft scenarios. So information pertaining to the theft of precious metals seldom becomes a newsworthy item. An audit conducted at a mine site with a gravity circuit recommended that the gravity recovery area be shut down until adequate protection could be provided. Although it was not connected with the audit, it was necessary to shut down the gravity area for a pro¬longed period because of problems with the gravity table. In the two months that followed, gold production at the site increased by about 31 kg/month (1,000 oz/month). It is difficult to attribute all of this increase to the theft of concentrates. But there was a good chance that at least part of the increase was due to the fact that concentrates were being stolen from the gravity area.

Jan 1, 1998

By Daniel K. Kim

The charge for the copper refinery is a mixture of anodes produced at San Manuel from BHP source concentrate and copper purchased from external sources. Control of unwanted impurities in the tankhouse - is very important and beneficial. Currently available removal/recovery technologies were reviewed for the control of bismuth and antimony levels in the electrolyte. Recent studies have focused on solvent extraction (SX) technology and generated successful results for the removal and subsequent recovery of bismuth and antimony. The SX system employs the reagent, ACORGA SBX-50, in conjunction with a patented high chloride stripping system. The latter enables recycle of the eluant, avoiding the high costs associated with conventional systems, such as regeneration of resin. Concerns over potential transfer of organics and chloride ion to the electrolyte were readily addressed, solved and demonstrated using conventional, established technology. This paper describes the benefits of electrolyte purification, the flexibility afforded by the SX system, the operational practices necessary for maintaining adequate control of bismuth and antimony impurities in the electrorefining environment and possibilities for future development /exploitation of the Zeneca SX system at the San Manuel refinery.

Jan 1, 1998

By Herbert Pöllmann

The mineralogical and chemical compositions of various waste materials undergo different reactions when treated thermally The heavy metal contents can be bound to stable phases. These minerals are called reservoir minerals. The main property of these minerals is the stability in their geochemical surrounding containing the heavy metal cations and anions. Examples for these minerals are apatites, spinels, garnets, perovskites and also water containing minerals like ettringites, metal-metal-hydroxi salts, jarosites and zeolites. When the chemical compositions of different wastes are mixed according to the compositions of the new formed minerals, a probable reuse of these wastes can be obtained. The use of waste incineration ashes for the production of cementitious binders and the use of flue gas desulfurization products for cement additives are shown. Also the transformation of highly contaminated materials into stable reservoir mineral assemblages are shown including the study of stabilization and immobilization techniques.

Jan 1, 1998

By Jose R. Parga

In mining operations, cyanidation is the ,predominant method by which gold and silver are recovered from their ores and it is recognized that cyanide consumption can be a major factor that contributes to the operating costs for such operations. Also after extraction and recovery of precious metals a certain amount of cyanide is delivered to the tailings pond and must be considered with respect is environmental problems due to the toxicity of cyanides. In this regard, the Air-Sparged Hydrocyclone (ASH) has been used as a reactor for the treatment of cyanide solutions in two ways; first for cyanide recovery by acidulation using the Mexican modification of the Mills-Crowe process and second for cyanide destruction by oxidation with the use of chlorine dioxide (ClO2). In both cases, excellent performance can be achieved using the high capacity ASH system.

Jan 1, 1998

By D. W. Collins

The uptake of gold from halide solutions by activated carbon has been investigated using various techniques. Halide systems typically exhibit combined adsorption-reduction type behavior. In an attempt to gain more information about the nature of these processes, samples of synthetic highly-oriented pyrolytic graphite (HOPG) were contacted with aqueous solutions of gold-iodide. HOPG represents a model structure for activated carbon comprising of basal- plane sites, edge sites, and various defect sites. Two basic instrumental methods were used to examine the uptake of gold by HOPG. The first was standard X-ray photoelectron spectroscopy (XPS). The other involved several scanning probe techniques. XPS clearly indicated a preferred uptake of gold at edge sites. However, iodine appeared to be distributed on both basal-plane and edge sites. At low iodine additions, tapping mode AFM showed that clusters were concentrated along steps and surface defects. At high iodine concentrations, the HOPG surface was uniformly covered by iodine.

Jan 1, 1998

Two key elements in the design of a pastefill or high density hackfill system are the preparation of the backfill material and its distribution underground. This paper examines these two areas. Owing to the essentially impervious nature of total mill tailings, preparation of pastefill and high density fill from current tailings involves a physical dewatering process. There are currently three methods available for this process: I. Vacuum or pressure filters. These represent the 'traditional' approach to the preparation of pastefill. 2. Paste production storage mechanism. This is a thickening/storage mechanism developed with the specific objective of producing paste/high density backfills. 3. Fluidization. This system utilises silos fitted with simple dewatering devices and nozzles. Recently developed by CANMET, it provides the simplest and most economical approach. This paper describes and compares the three preparation methods, from a practical and an economic point of view. Once the pastefill/high density fill has been prepared and binder added, the backfill must be distributed underground into the stopes. A fundamental factor in the design of a distribution system is the rheology of the material- No two materials will exhibit the same properties, and a sequence of rheological and related testing is required prior to the completion of the design of the underground distribution system. This paper covers the testwork normally required and discusses the fundamental design parameters of pastefill distribution systems. The final section of this paper summarises the use of pastefill at three mincsin Canada.

Jan 1, 1998

By Lock PR

The Silver Swan nickel mine is located at the Black Swan Nickel Project, 53 kin north east of Kalgoorlie, Western Australia. The Silver Swan orebody is a massive sulphide nickel deposit dipping 70¦ east with an average in situ grade of 14 per cent. Mining of the massive orebody is by Mechanised Ramp Cut and Fill (MRCF). A mining recovery of 98 per cent and minimising dilution are primary goals in extracting the high-grade ore. Placing a distinguishable marker bed (working platform) on rock fill was identified as a key method to achieving these goals. Gravel from a pit located onsite was considered the most suitable material for the marker beds. Research undertaken to design the marker beds using the gravel revealed conventional methods used in mining would not suffice, but that road stabilisation methods could be a viable alternative. Trials used a road recycler to mix cement and gravel in situ and several test beds were constructed on the surface to determine the final design. The trials attempted to replicate a marker bed's life cycle of construction and placement and mucking of ore from the marker bed.

Jan 1, 1998

By N. Gopalakrishnana, R. Beccard, S. Lourdudoss, R. Holz, M. Deschler

"Rapid growth of conducting and/or insulating InP, GaAs, Gao.47In0.53As, and GaAs0.6Po.4 on one or more of (001), (110), (111)A, (3ll)A and (3ll)B surfaces by Hydride Vapour Phase Epitaxy (HYPE) is demonstrated. The maximum growth rate of the binaries lies between 12 and 300 µm/hr and of the ternaries between 7 and 170 µm/hr. A simple model is developed to describe the influence of crystallographic orientation on temperature dependent growth rates. The growth rates predicted by the model is compared with the experimental values. Room temperature resistivity of insulating InP:Fe can be as high as 5xl09 ohm cm. Temperature dependent differential resistivity is also analysed. This feasibility of growing conducting and insulating layers rapidly on different orientations is very useful for electronic and optoelectronic devices.IntroductionRecently there is a renewed demand for very thick layers of III-V compound semiconductors for high performance electronic and optoelectronic devices [1]-[2]. Long wavelength high speed lasers that can be modulated up to 30 GHz necessitate epitaxial growth of semi-insulating (SI) layers [3]. There is also an increased interest on the growth of epitaxial layers on surfaces other than (001) surface. Epitaxial growth of these materials on such surfaces is of theoretical importance besides being technologically relevant. These demands led us to focus on the growth of conducting and insulating III-V compounds by Hydride Vapour Phase Epitaxy (HYPE). lnP, GaAs, Gao.471no.s3As on lnP and GaAso.6Po.4 on GaAs were grown as conducting materials using Low Pressure HYPE (LP-HYPE) on (001) 2° off substrates. Gao511no.49P on (001) GaAs substrate and lnP on lnP substrates of (001), (110), (l 11)A, (31l)A and (3 ll)B orientations were grown as semi-insulating materials using Atmospheric Pressure HYPE (AP-HYPE). In this report we present the growth aspects of these materials. We also present a simple model on the growth of InP on substrates of various orientations. The theoretically obtained temperature dependent growth rates are compared with the experimental values. Differential resistivities of semi-insulating lnP grown on substrates of various orientations as a function of temperature are also summarised."

Jan 1, 1998

By Wilson I. L. Lim, Jonathan J. Campbell, Luis A. Tondo

An important issue in the use of high pressure grinding rolls when grinding ores is wear of the rolls. Due to the abrasive nature of the ores, significant wear rates have typically occurred. Attempts to address the wear problem require a better understanding of the wear mechanisms. A probable wear mechanism is the abrasion of the rolls surface due to extrusion of the compacted material as it leaves the rolls. This paper presents the results of a study on a number of ores to examine the extent of extrusion that occurs. The study involved laboratory, pilot and full-scale high pressure grinding rolls. The effect of variations in parameters such as grinding pressure, rolls speed, initial gap settings, feed topsize and moisture was investigated. The results indicate that extrusion increases with increasing grinding pressure and rolls diameter, while the use of studded or profiled rolls significantly reduces the extrusion effect compared to smooth rolls. It was also found that rolls speed and feed moisture can have significant effect on extrusion, depending on the material.

Jan 1, 1998

By Brian Flintoff

"When I was first asked to prepare this paper and presentation in late June, I thought it might be fun to ""step back and paint the bigger picture."" Having attempted to do this, fun is not the first descriptor that now comes to mind, and speaking dyslexically, I've had 'nuf.'Unlike Nostradamus, or even Orwell, I've discovered that I'm ""clairvoyantly challenged"" and not even the psychic hot-line was of much help, at least with respect to process control! I am somewhat comfortable speculating on evolutionary change, but the radical developments that will arise from revolutionary changes are well beyond my mortal capabilities. Even with evolutionary change, I'm reminded of the lessons of time series analysis which show the prediction error to grow exponentially as the horizon moves into the future. As Macluhan is reported to have said: ""Predicting the future based on the past is a little like driving your car while looking in the rearview mirror!""Having honestly presented my qualifications, allow me to try to look at process control and to offer some conjecture on where we're probably headed. In the end, it is said that: ""The plant of the future will have only two employees, a man and a dog. The dog will be there to keep the man from touching the equipment.1""IntroductionA little less than a decade ago Andy Mular and I co-edited a monograph entitled ""A Practical Guide to Process Control in the Minerals Industry."" The work was commissioned by the senior management of a consortium of Canadian mining companies, since it was widely perceived that control was an area of great economic potential, but one that had not been effectively tapped. The concern was that if the industry could not soon deliver on the ""potential"", the term may well have appeared in the epitaph of what was, to these men, a very attractive investment opportunity. I think it is fair to say that over the past few years process control has clearly established itself as an essential technology in plant operation and optimization. That isn't to say that we get it all-right, all-the-time, but, the circumstances are much different than they were. In the eyes of many, process control has attained the distinction of being considered a mature technology, even though there are still countless avenues for exploration."

Jan 1, 1998

By H. Y. Sohn

The considerable progress made in the sulfide smelting technology since the first International Sulfide Symposium of 1983 is discussed. The new developments and innovations have largely been driven by the recognition of environmental concern as well as the need for increased productivity. The smelting technologies for various nonferrous metals are reviewed, with an emphasis on the industry trend towards larger plants and continuous processes. The tremendous advances made in process modeling and computer simulation to describe the complex smelting processes are also reviewed. The goal of these mathematical models is the quantitative description of the processes and the reactors that will provide a means for the control and optimization of smelting operations as well as the optimal design of the operating conditions and the reactors. Environmental issues remain a key consideration in the smelting industry. One of the most remarkable improvements made in the last fifteen years since the 1983 Sulfide Smelting Symposium is the rapid increase in the sulfur capture by nonferrous smelters. This and other related issues are briefly discussed. Finally, the challenges that the smelting industry faces as the new millenium approaches are discussed. The industry continues to face technical challenges to improve productivity and efficiency, while being responsive to ever-increasing public pressure for environmental protection. It also faces external challenges from factors that may cause the reduction of metal uses as a result of substitutions by other materials. Another serious challenge and dire consequence that the primary metals industry is expected to face is the serious diminution of university-educated manpower as well as basic-research output. To remain competitive and healthy, the industry should take up the void left by the complete disappearance, at least in the U.S., and the reduction in other nations, of the governmental support of higher education and basic research in the field of primary metals production.

Jan 1, 1998

By M Gwynne

McArthur River Mine is located approximately 50 km south-east of the NT township of Borroloola and approximately 120 km from the Gulf of Carpentaria. The mine hosts a series of layered shallow dipping tabular orebodies, with current reserves of approximately 22 Mt, grading 13.6 per cent zinc, 6.3 per cent lead and 65 g/t silver. Owing to economic considerations, the lower most orebody (No 2 orebody) has been selected for initial mine production. Following the completion of the No 2 orebody, mining will transfer to the lower grade and metallurgically more complex No 4 orebody. The mine employs a total of 235 people throughout the underground and surface areas. The majority of the workforce work a fly-in/fly-out, seven-day- on/seven- day- off roster with 12-hour shifts. Presently, a further 18 contractors are involved in trial mining areas. An apparent dip room and pillar technique has been selected as the primary mining method. Officially opened in September 1995, the current production rate of 1.2 Mt per annum will eventually escalate to 1.5 Mt per annum. Though most production is achieved through the use of conventional loaders, trucks and jumbos, the recent development of methods utilising scrapers, hand held machines and modified jumbos has produced encouraging results in steeper dipping areas of the mine. Initial production has been hindered by several factors including extensive and largely unpredictable faulting, worse than expected ground conditions and difficulties with some mining equipment. Compounded by the relatively thin 3 m ore seam, initial mining resulted in high dilution and poor production. This paper describes the development of unique planning and production systems that were evolved in order to overcome these problems and achieve the targeted production rates and head grade.

Jan 1, 1998

By J. K. Gowans

The Research and Design group of the Project Development Division (PDD) of Placer Dome Inc. includes metallurgical, electrical, civil and mechanical engineers. They provide metallurgical research and conceptual flowsheet development, feasibility concepts for the processing and ancillary facilities, and manage the detailed design of the facilities once approval has been given to a mining project. This paper describes how this group works, within the Project Development Division, to help develop feasibility studies with the Evaluations Group, manage detailed design, and provide support for the Construction Group. The paper briefly reviews the history and growth of the group and describes how it is evolving. The role of outside engineering firms and how they are incorporated into the division’s objectives are also discussed. The paper highlights the differences between Placer Dome’s Project Development Division and other mining groups, and why this approach fits the way Placer Dome does business.

Jan 1, 1998

JIM ARNOLD: Questions? Comments? Gary, were you gone when I made the comments about corporate puke? [laughter] SPEAKER: You were hiding. BRUCE CAVENDER, BHP Copper: Having worked in both places, I'd like to address the issue of the plant versus the corporate office. One thing to keep in mind is that we are all very engaged with the technical elegance of a lot of the work we do. There's some tremendous technical expertise in the plant. But remember, the guys in the corporate office are only thinking in one denomination, and that's dollars. So we'll see something like a spill, and for us it's a problem. At the end of the day, what the corporation cares about is the financial impact. So we've got to be careful to couch our solutions in dollar terms. JIM ARNOLD: Rebuttal? [laughter] DOUG HALBE: Are you going to rebut this one, Andy? ANDY CARTER, Oxidor Gold Corporation: No, I don't think so. I'm not up to it. I'd just like to address a question both to our panel and the floor. Those of us who've been in this industry any length of time have seen these same mistakes made over and over again. Wherever you go, year after year, plant after plant, you see the same problems. I guarantee you, Doug, that if we have a similar conference down the road, you're going to see the same thing. My question to the panel and to the floor is what is it about our industry that stops us from learning from our mistakes? What characteristic is it that prevents us from learning and makes us repeat the same mistakes over and over again? DOUG HALBE: That's a great question. Someone said in a meeting 10 years ago that if the people who design plants designed airplanes, the planes would be falling out of the air all the time. GARY SIMMONS, Newmont Gold Company: I've got an answer to your question as to why many plants are poorly designed. It's that the minute anybody demonstrates any sort of competence in plant design, they're promoted to a higher-paying job, and the talent pool is left with people of lesser experience. Just think about it: The people who have the experience and have demonstrated it more than once have moved up. JIM ARNOLD: I think that there's another reason, too. Seven or eight years ago I was chairing a session, and I challenged everyone in the session to some day publish an article about the design mistakes they'd made because we never talk about our mistakes. I'll

Jan 1, 1998

By A C. Robertson

Over the past decade there has been continual change in the way that mines have been managed and the component roles of those people who make up the total mine management system. Major issues have included the change in the business structure of mining companies, the change in on-site infrastructure, increased personal liability of managers for the safety and health of employees and increasing social and environmental pressures on managers and their staff. This paper looks at the changing roles of two of the many groups of professionals associated with the mining industry - the equipment supplier and the mining consultant. The profiles of the ACME Group Pty Ltd, suppliers of ventilation equipment and ancillary canvas and plastic products to the mining and construction industry, and Tennent, Isokangas Pty Ltd, Consulting Mining Engineers, are presented.

Jan 1, 1998

By Yimin Ruan

"An inverse design method is developed to obtain the optimal cooling conditions for the continuous quenching of precipitation hardenable sheet alloys to achieve the required yield strength. The yield strength of a precipitation hardenable alloy is obtained by allowing solute to enter into solid solution at a proper temperature and rapidly cooling the alloy to retain the solute in the solid solution. An aging process may be needed for the alloy to develop the final mechanical properties.The objective of the design is to optimize the quenching process so that the required yield strength can be achieved. With the inverse design method, the required yield strength is specified and the sheet thermal profile at the exit of the quenching chamber can also be specified. The conjugate gradient method is used to optimize the cooling boundary condition during quenching. The adjoint system is developed to compute the gradient of the objective functional. An aluminum sheet quenching problem is presented to demonstrate feasibility of the inverse design method.IntroductionQuenching is a critical step in metal production to achieve desired material properties, such as yield strength, hardness, etc., for precipitation hardenable alloys. In most cases, rapid quenching from the solution heat treatment temperature is necessary to obtain the required material properties, but rapid quenching may cause other problems such as excessive distortions of the quenched materials.In a solution heat treatment, the alloy is heated to a suitable temperature, held at that temperature to allow the soluble alloying elements to enter into the solid solution, and cooled rapidly (quenching) to retain the alloy elements in the solid solution. An aging process, which controls precipitation of fine particles at room (natural aging) or elevated temperatures (artificial aging), is generally followed after the quenching process to develop the final mechanical properties of the heat treated alloys."

Jan 1, 1998