Search Documents

By John D. Campbell

"IS YOUR MANAGEMENT CONTROLLOOP FUNCTIONINGMineral processors make use of hundreds of control circuits in their mills, process plants, smelters and refineries, to optimize throughput and recovery and minimize cost. This afternoon, I would like to discuss what is probably the weakest circuit in any mineral processing operation - the management control loop.In their recent book ""The Winning Streak"", Goldsmith and Clutter describe extensive research on unsuccessful companies. They conclude that ineffective control, which does not immediately identify the problems, is one of the main failings of unsuccessful companies.We will look at the three key components of control which, from the manager's point of view, ensure that the loop is complete. These three are:• measuring what's happening,• assessing its significance, Rnd• altering performance.If we compare management control to process control as shown in this first figure, ""We see that parameter sensing by the analyzer in a process circuit is analogous to performance monitoring by management in a responsibility centre. The analyzer senses temperature, pressure, flow, weight or some surrogate indicator such as colour to indicate ion concentration. For manage1nent, the performance to rnonitor is dependent upon the objectives of the responsibility centre, and the key factors which affect these objectives."

Jan 1, 1985

By X. Cao

Friction stir processing (FSP) is used to produce wrought microstructures at the surface of sand-cast aerospace grade magnesium alloy ZE41A-T5. It is found that the microstructure is significantly refined in the stir zone and the flow arm. The stir zone is largely comprised of equiaxed magnesium grains of approximately 4.5 pm compared with about 50 µm in the base cast material. In the stir zone, however, abnormal growth of some grains is also observed. Vickers microindentation hardness tests indicated that the stir zone experiences some increases in hardness. Single surface passes with low distortion, lack of pores and cracks were successfully obtained indicating the great potential of the FSP technique for modifying, improving and repairing magnesium alloy castings. This will probably open new opportunities to apply magnesium alloys in aerospace industry.

Jan 1, 2007

By A. Philipp, A. S. Middleton, G. A. Harron, A. B. Durham

"Basal till sampling techniques were used to search for gold mineralization in the Timmins, Ontario area. During 1978 and 1979, approximately 90 overburden sampling drill holes were completed in Murphy and Hoyle Townships to test specific geophysically defined target areas. A conventional tricone dual tube drill system, and a unique retractable tricone/rock coring system were used to various advantages.First pass till sampling at 800 to 1200 ft intervals perpendicular to ice transport direction yielded anomalous gold values in till and carbonatized quartz pyrite-rich bedrock chips, and lateritic soil. Subsequent induced polarization-resistivity surveys defined the areal extent of a pyritic carbonate alteration zone. A second pass till sampling/limited rock coring program evaluated the gold mineralization potential of the alteration zone. Diamond drilling has substantiated the till and bedrock gold anomalies. Further evaluation of this mineralization is currently in progress. IntroductionThis paper describes an integrated geochemical/geophysical gold mineralization discovery case history in Hoyle Township. This discovery is on a property jointly owned (I983) by Canamax Resources Inc. and Du Pont of Canada Exploration Limited. Exploration of the property began in 1978 by Rosario Resources Canada Ltd. and in 1979 a joint venture agreement was signed with Du Pont of Canada Exploration Limited. Rosario Resources Canada Ltd. was taken over by Amax Minerals Exploration in 1981, which became Canamax Resources Inc. in 1982.The work described in this paper deals with a gold mineralization discovery located three-quarters of a mile northwest of the gold deposit currently being readied for underground exploration and development. Further drilling is required to investigate the economic potential of the gold mineralization herein described."

Jan 1, 1987

By J. P. Weiler

The increasing use of high-pressure die-cast magnesium alloys in the automobile industry requires a better understanding of the mechanical properties, the microstructure, and particularly, the relationship between these two. The goal of this study is to first understand the microstructural features which control the mechanical properties observed from an AM6OB magnesium alloy, and second, to be able to predict the local mechanical properties based on microstructural features encountered in different areas of the die-cast component. The two main tools used in this study are spherical indentation testing, used on local areas of the die-cast magnesium alloy AM6OB to detect changes in microstructure and mechanical properties, and X-ray tomography, used to non-destructively investigate the internal porosity in a sample. The results from these tests are then used to predict the local mechanical properties such as the yield stress, the strain-hardening characteristics, and the fracture properties of the AM6OB component.

Jan 1, 2006

Phelps Dodge has recently operated a commercial scale, super fine grinding circuit of copper concentrates for use in a medium-temperature pressure leaching process. Two 355 kW vertical stirred mills were installed in series, targeting a grind of 80% passing 7.5 µm and 98% passing 15 µm as outlined in Phelps Dodge's concentrate leaching patent portfolio. This paper details the operation and results of the test program at Bag dad, as well as some of the operating challenges encountered.

Jan 1, 2007

By G. Deschênes

The Eleonore property (James Bay district of Northern Québec), owned by Goldcorp, hosts gold within stockworks of quartz-tourmaline-arsenopyrite veins and veinlets contained within microcline (potassic alteration) and brown tourmaline replacement zones. The preliminary investigation to recover gold from drill core samples showed that flotation followed ultrafine grinding and cyanidation is the preferred option. Ultrafine grinding is used to liberate gold finely disseminated in sulphides. The flotation concentrate used in the investigation had a P80 of 11 microns and contained 75.5 g/t Au, 5.0 g/t Ag, 10.3% S, 0.07% Cu and traces of antimony (0.03%). The mineralogical characterization showed the presence of 65% gangue minerals, 23% pyrrhotite (hexagonal), 9.6% arsenopyrite, 2.2% pyrite and 0.08% chalcopyrite with trace amounts of galena (0.05%) and sphalerite (0.03%). Gold was in the form of native gold and electrum. A straight cyanidation conducted at pH 11.0, DO of 3-5 ppm, 2000 ppm NaCN, 20 C 72 hours extracted 97.0% Au and consumed 31.5 kg/t NaCN. The equilibrium was reached within 24 hours. Increasing the dissolved oxygen to 16 ppm reduced the consumption of cyanide to 22.0 kg/t with 96.7% Au extraction. A 16-h pretreatment with 2.0 kg/t lead nitrate, followed by a 24-h cyanidation reduced the cyanide consumption to 6.0 kg/t with a gold extraction of 97.5%. Increasing the lead nitrate addition to 6.0 kg/t reduced the cyanide consumption to 1.2 kg/t by passivating the surface of pyrrhotite. The gold extraction remained at 97.0%. It was possible to decrease the concentration of cyanide to 800 ppm NaCN without compromising gold extraction. The associated cyanide consumption was 1.2 kg/t NaCN. The passivation of gold grains was an issue when the cyanide concentration was decreased to 550 ppm NaCN. The gold extraction decreased to 92.2%. The average lime addition for all the tests was 7.4 kg/t and the average silver extraction was 80%. Efficient cyanidation of an ultrafine sulphide concentrate with only 800 ppm NaCN represents an advance in leaching of ultrafine sulphide concentrates.

Jan 1, 2013

By Jane Li, Kevin Tom

"Research has shown that broken rock on conveyor transport systems can contribute upwards of 50% towards the overall heat load in underground mines. However, few studies have made significant efforts to predict the temperature distribution of the ore and air simultaneously, which can help implement heat management strategies. The present investigation explores a transient, analytical heat transfer model to track ore-pile temperature distributions, along conveyor systems in an example underground mine. Production rate, ambient conditions, ore pile thickness and belt velocity are adjusted to evaluate the effect on dry and wet bulb temperatures.INTRODUCTIONWith an ever increasing demand on Earth’s resources due to a multitude of factors like population growth and step changes in technology, pressure on the mining industry to bring out more ore with improved margins is a persistent challenge. Typically, high-volume producing mining methods (i.e., exceeding 5000 tons per day (tpd)) such as sublevel and block caving, room and pillar, and longwall shall utilize belt conveyors instead of trucks as the primary haulage method to surface to save on operational costs (de la Vergne, 2014). However, studies have shown that when such material transport systems are installed at mine depths with virgin rock temperatures (VRT) above 40oC, the heat dissipated by the conveyed ore can account for over 50% of the underground heat-load (Pareja, 2000; Bluhm, Jones, Moreby, & von Glehn, 2012; van den Berg, Moreby, & Kok, 2015).Unlike other types of heat sources encountered in underground mines, such as diesel machines, strata, electrical devices, and autocompression, heat transfer by conveyed broken rock is much more difficult to estimate. The seminal work of McPherson (1993) states that broken rock heat transfer is a function of its surface area, and the air’s psychrometric condition. It is additionally a function of the VRT, its specific heat, production rate, heat transfer coefficient and the residence time (Bossard, 1997; Ross, Tuck, Stokes, & Lowndes, 1997). Consequently, few studies have attempted to analytically quantify the significance of ore heat flow."

Jan 1, 2019

By John D. Godfrey

Geological mapping on the Canadian Shield in northeastern Alberta outlined severalgranitoid rock massespotentially suitable as building stone. A particularly attractive prospect, the Chipewyan Red Granite, was subjected to an aerial survey and ground check. The petrologic and fracture characteristics critical for quarrying and use as a building stone were assessed in the course of detailed mapping at two of the most favourable sites. The extension of good rock was tested to shallow depths at one site by shallow diamond-drill coring. , The Chipewyan Red Granite displays a warm red colour, medium grain size and fairly massive texture, and takes a good polish. Deleterious geologic features studied in outcrop and subjected to structural analysis included regular joint systems, quartz veins, pegmatite dykes, basic shear zones and fault zones. Many of these key geologic features are systematic and hence predictable for stone quarrying purposes; other features, such as irregular fracelM tures, are non-systematic and arefar less predictable. The megascopic structural features studied show similar preferred orientations which appear to be collectively related to the tectonic history.

Jan 1, 1979

By Hans Lundberg

Introduction Today, geophysical exploration is recognized as a special science wedged between geology and mining. Universities and technical institutes have special professors teaching geophysics applied to oil and ore prospecting. The list of literature on geophysical exploration has grown from practically nothing at all some twenty-five years ago to ~ several thousands of books, some of them very imposing volumes. Most of the methods now used have been developed since the first World War, and very large systematic exploration campaigns have been carried out in many places, in many countries. It has been rather difficult to obtain enough information as to what is going on in Canada. However, since the Associate Committee on Geodesy and Geophysics of the National Research Council became more actively engaged in promoting geophysical research, it may be easier to obtain information and, in the future, the quarterly issued Canadian Geophysical Bulletin may throw considerable light on the current geophysical activities in Canada. Some twenty crews have been engaged the last few years in geophysical prospecting for ore. In the United States, between 500 and 600 crews are employed exclusively in geophysical prospecting. Most of these, however, are engaged in oil exploration. During the winter 1942-1943, the German Government employed some fifty crews on geophysical exploration, and some ten crews were working for private enterprises.

Jan 1, 1948

By Francis Gray

Mr. F. W. Gray: It is not my intention to read my paper as it is too long, so I will touch only on the high lights. The Sydney field is the most favourable example of undersea coal mining that exists, and I have not been able to find anything like it elsewhere. The nearest approach to it is a field in England where the Whitehaven collieries are operating, but it has a lot of faults. The net result of these faults so far met with in the seaward advance of the workings has been to increase, by something over 100 feet, the gain in depth of cover, in a distance of approximately three and three-quarter miles. In the Sydney field there are no faults of any consequence. On the east side, the English measures rise. In Australia the sea bottom fell and the cover became too light. On Vancouver Island the coal ran out, and in Japan the seams are steep and contorted. The Chilian fields resemble our own to some extent. An inundation of two collieries took place there some time ago, due, it is said, to the rise workings being allowed to approach the sea bottom too closely in the vicinity of a fault. The Cape Breton undersea field has been proved over a frontage of about thirty miles and has been attacked and penetrated for a considerable distance along that front. We have passed the prospecting stage and now generally use developed land areas as points of attack to win the undersea coal. Of our mining under the sea, it can be said that, with the exception of No. 1-B and Princess colliery, Sydney Mines, no real attempt has been made to win the undersea coal.

Jan 1, 1927

By Gordon R. Harris, Raymond Chalk

Descriptions of typical pulp and paper manufacturing processes are presented, with particular emphasis on the use of minerals and derived products. Some consideration is given to the future demand for these minerals by the pulp and paper industry. Possible influences of techno-logical change and social legislation are suggested and their effect on saltcake demand by the pulp industry is discussed. Predictions are made regarding trends for new and existing paper products.

Jan 1, 1968

By Antonio Segatori, Bjørn Holmedal, Kai Zhang, Trond Aukrust, Knut Marthinsen

"The visual appearance and mechanical properties of aluminium alloy extrusions are strongly dependent on the microstructure and texture of the extruded profiles, where the desired microstructure and texture may depend on the specific applications. In the present work, the evolution of deformation, as well as recrystallization textures during extrusion of AA6xxx aluminium alloys, have been experimentally and numerically investigated. Extrusion trials were performed in a laboratory extrusion set-up, which enabled immediate water-quenching of the profiles at the exit of the die, and thus the possibility to capture the deformation texture prior to post-extrusion recrystallization. The textures and their through-thickness variations were experimentally measured by the electron back-scatter diffraction technique (EBSD, and the deformation textures numerically modelled by coupling FEM flow simulations and crystal plasticity (CP) simulations. Different CP models as well as different choices of model parameters were employed and evaluated for texture predictions. With an appropriate choice of crystal plasticity model and model parameters, the deformation texture can mainly be predicted, although the accurate intensities are hard to reproduce. The corresponding recrystallization textures, either generated through spontaneous recrystallization of the extruded profiles or through post-extrusion annealing, are far more challenging to reproduce with available recrystallization models.INTRODUCTION Extrusion is a widely applied thermal-mechanical process to produce aluminium profiles. The properties of the profiles, for example mechanical, fatigue, fracture, corrosion as well surface appearance, are strongly dependent on the underlying microstructure and texture, and the requirements with respect to these aspects may vary with applications (Ralston et al., 2010; Dumoulin et al., 2012; Donati et al., 2013). Moreover, it is often a challenge to produce extrusions with a consistent and homogenous grain structure and texture along as well as through the cross section of the profiles. It is thus vital to understand and be able to predict (model) how different microstructures and textures are formed and how they evolve during and after extrusion, as basis for controlling the final appearance and properties of extruded profiles."

Jan 1, 2018

By Claude MacDonald, John H. Ashburn

"IntroductionIndustrial growth and technological change over recent years had been accompanied by two major sources of concern to management and employees: (a) increase in occupational injury and illness and the resultant costs involved; and (b) equipment damage and breakdowns in concentrated production lines causing more extensive loss potential.Due to economic factors, management attention has focussed more on production and quality than on safety, health and related loss potential sources. As a result , occupational safety and health activism has grown, government legislation of compensation and occupational safety and health standards have progressively developed and stronger liability attitudes have been taken by courts of law.To improve efficiency and allow development in more competitive markets, rising labour costs, equipment costs and safety related financial losses have dictated that attention be given to conservation of all resources. Conservation of resources, people, equipment, material and environment, can no longer be addressed in isolation but must be managed integrally with production and quality. To this end, systems have developed utilizing sound management principles applied with equal intensity to production, quality and loss potential"

Jan 1, 1987

By E. Wasmund

"Sandfire’s DeGrussa Copper-Gold operation in West Australia is a new high grade copper sulfide mine, which includes a 1.5 Mtpa concentrator which was completed in 2013.Early after commissioning, it was identified that the flotation capacity in the all-mechanical cleaner circuit was not sufficient. In order to improve recovery, the tail from the cleaner scavenger was sent back to feed the rougher scavengers. Test-work was done on-site to evaluate the possibility of using a flotation column as a pre-cleaner. A CavTube™ sparging system was selected, which is especially effective for fine ore particle flotation. Test-work was conducted at site using a 150 mm diameter unit, and then confirmed on a 500 mm diameter unit. A 4250 mm diameter full scale unit was installed in Q4 2014 and commissioned in Q1 2015. This unit gave some significant advantages including a reduction in re-grinding requirements, elimination of a circulating load and increase in the recovery of copper in the cleaner circuit and overall circuit.In this presentation, the benefits of columns and cavitation sparging for floating fine particles and rejecting fine entrained gangue will be explained. Also, the results from a lab unit and a pilot unit will be compared against the results of the full-scale unit. The paper will demonstrate the scalability of flotation columns, and which phenomena and scale-up criteria must be considered to be successful. Finally, some general observations will be made about the importance of columns in copper cleaning circuits.IntroductionSandfire Resources’ DeGrussa copper-gold concentrator is located approximately 900 km north-north-east of Perth in Western Australia. The project area landscape is scrubby mulga lands with few notable features. The climate is arid with high temperature and heavy summer downpours."

Jan 1, 2016

By Michel Massé

Eleonore Project- Agenda ? Purpose and Technical Overview ? SmartEXEC Control Capabilities ? SmartEXEC System Archetecture ? SmartEXEC System Advantage Eleonore Project- Purpose and Technical Overview ? Control air quality while maintaining target production levels at minimum energy operating cost ? Improve safety, work place conditions and operation flexibility ? Reduce energy consumption and green house gases footprint

Aug 1, 2013

By K Belanger, J. Mclachlan, F. Stober, G. Norval, B. Snider, A. Munsch, T. Koehler, E. Piantino, J. Carlos Queiroz

The project to rebuild the smelting furnaces at the Anglo American - Barro Alto ferronickel smelter, located in Goias, Brasil, was initiated in September 2013. To optimize the capital cost, while maximizing furnace integrity and robustness, a design basis giving flexibility to ore composition variation was developed in order to ensure sustained nameplate production. The resulting capital efficient, fasttracked project execution was accomplished through the creation of an integrated project team of Anglo American and Hatch through FEL 3 and FEL 4 phases of the project. The integrated team addressed the project challenges through a cooperative and versatile approach, created by access to knowledge, experience and systems in both Anglo American and Hatch. The team could operate at an optimized speed of execution, as demonstrated in the FEL 3 and FEL 4 completion durations, as well as efficiently mitigating any risks of increasing cost or delaying schedule by utilizing lessons learned and team knowledge from Anglo American on the original green-field project and Platinum smelters and Hatch on similar reference ferronickel furnace rebuilds. Other critical drivers of project cost minimization and revenue loss/generation (considering production revenue of each furnace) are scheduled durations for construction, commissioning and ramp-up. The integrated team commenced construction, commission and ramp-up planning almost one year in advance of the shutdown and this paper will discuss the strategies developed to reduce risks and optimize the construction schedule to mitigate revenue loss and optimize ramp-up time to sustained operation at nameplate capacity.

Jan 1, 2015

By Krishna Parameswaran

"This paper discusses energy use and conservation in the primary copper industry and illustrates eco-efficiency considerations, using select examples of practices at ASARCO LLC, an integrated primary copper producer and others in the industry that promote eco-efficiency. The World Council for Sustainable Business Development first publicized the concept of eco-efficiency at the Rio Earth Summit in 1992. Eco-efficiency is a management concept linking environmental and economic performance and is aimed at generating added value for a business through, among other things, increased resource and energy conservation and reduced environmental impacts throughout the life cycle of the product or service. This concept differs from sustainable development in that focus is only on economic and environmental factors and does not include social considerations. In the metal mining and processing context, this added value can be realized by implementing practices that promote conservation of water and mineral resources, conservation of energy, minimization of waste, reduced emissions and effluents and increased recycling. The examples from the primary copper industry used to illustrate eco-efficiency considerations include: water and energy conservation in mineral processing, adoption of flash and bath smelting processes, emission reduction and process improvement associated with fire-refining, implementation of green chemistry in electrorefining, promoting product stewardship initiatives and fostering renewable energy project on disturbed mined lands.INTRODUCTION ASARCO LLC (Asarco) was organized in 1899 as the American Smelting And Refining Company. Originally a consolidation of several lead-silver smelting companies, it evolved over the years into an integrated producer of primary non-ferrous metals, including copper, lead and zinc and associated co-products. Grupo México, S.A.B. de C.V acquired Asarco in 1999. Today, Asarco is a vertically integrated producer of primary refined copper and associated co-products such as gold, silver, molybdenum, selenium and tellurium. Asarco operates three open-pit mines and mills, two leach, solvent extraction-electrowinning (SX-EW) plants and a copper smelter in Arizona and a copper refinery in Texas."

Jan 1, 2017

By Keith Merriam, Jim McDonnell, Peter Radziszewski, Rob Rotzinger, Ian DeHart

"Taseko Mines Limited Gibraltar copper-molybdenum mine recommenced operation in 2004 with the initiation of a series of development projects to increase throughput capacity as well as modernize the mine.In the second staged development project, a VTM-1250-WB regrind mill was selected to replace the existing conventional ball regrind mill to achieve a target grind size of 80 % passing 45 µm. In the third staged development project, a second VTM-1250 regrind mill was selected for installation in Concentrator #2, to match the existing Concentrator #1 Vertimill. This resulted in approximately 25% spare regrind capacity in the Concentrator #2 design, complete spare parts interchangeability and potential future expansion capacity to 50,000 t/d with no circuit upgrades.In this context, a study was initiated to assess not only the performance of a Vertimill grinding circuit processing a copper concentrate to a particle size of 80% passing 17 µm but also to provide Taseko’s New Prosperity project specific design information for grinding to particle sizes below 80 % passing 25 µm.The objective of the work described in this presentation was to explore Vertimill ultrafine (sub 100 µm) grinding test methodologies at both the lab and pilot scales, compare the scale-up data with operational data from the VTM1250 at Gibraltar Mines and subsequently apply this information to particle sizes down to 80% passing 17 µm. The presentation will describe the results obtained preceded by a description of the Gibraltar regrind circuit historical operation and operational performance as well as a description of the Vertimill technology.INTRODUCTIONTaseko Mines Limited is a mining company headquartered in Vancouver, British Columbia, Canada. In addition to mining development projects for copper, copper-gold, gold, and niobium properties, Taseko Mines is seventy-five percent owner and the operator of the Gibraltar Mine near Williams Lake , British Columbia. Taseko Mines Limited’s Gibraltar copper-molybdenum mine recommenced operation in 2004 with the initiation of a series of development projects to increase throughput capacity as well as modernize the mine.Metso is a leading process performance provider, with customers in the mining, oil and gas, and aggregates industries. It has corporate headquarters in Helsinki Finland, offices in 50 countries and manufacturing facilities on five continents. Amongst other types of equipment and services, Metso designs and manufactures VERTIMILL® (VTM) Grinding Mills."

Jan 1, 2015

By M. W. Franklin, D. W. Hendriks

"Changing ore types, feed grades and c1rculat1ng loads are some of the many factors that can make flotation feed-back control difficult. To control a flotation circuit using conventional fixed-parameter control algorithms, one must either tune the controllers very often or tune the controllers to the middle of the normal operating range. The former approach is very time consuming, while the latter approach can lead to long periods of either very sluggish responses or highly reactive responses which can lead to instability. The problem becomes compounded if feed-forward variables are introduced, creating even more variables to tune. An alternative to a fixed-parameter control algorithm is an adaptive control algorithm. An adaptive control algorithm continuously retunes itself based on previous reactions to its changes. Feed-forward control also becomes much more viable because the algorithm will tune the feed-forward parameters and the feed-back parameters simultaneously. Using the combination of feed-forward and feed-back tuning is an effective way to decouple the loops needed in flotation circuits where one circuit feeds into another. The advantages of adaptive controllers over conventional controllers will be introduced through the use of a simulator. Also discussed will the be the implementation of adaptive controllers at Brunswick Mining and some of the modifications that are available to help solve more difficult control problems.Brunswick Mining is located just outside of Bathurst, New Brunswick. The concentrator processes approximately 10250 tonnes per day of ore that assays at approximately 8.9 %zn, 3.6 %Pb, 0.3 r.cu and I 00 gram/tonne of Ag. The four products produced are zinc concentrate assaying 51 %Zn, lead concentrate assaying 34 %Pb, copper concentrate assaying 21 %Cu, and a bulk concentrate assaying 32 %Zn and 18 %Pb."

Jan 1, 1986

This paper describes results of an investigation of fracture during tube expansion of 5052 and 5754 aluminum seam-welded tubes to optimize the forming of aluminum tubes during hydroforming. The tubes were produced in laboratory by press forming of tubular blanks and pilot-scale high frequency induction welding. The effect of property mismatch between the weld and base metal has been investigated. The material work-hardening was obtained by roll forming of sheet blanks in the 0-temper and H32 temper condition. The results showed that a significant work-hardening can be present in aluminum tube without causing weld fracture during tube expansion. The work-hardening increases the yield-strength mismatch between base metal and weld. Annealing reduces the hardness of base metal leading to more uniform deformation during tube expansion. As a result the occurrence of weld fracture is reduced. The study showed significant deformation of the welds during tube expansion. Weld thinning can be as large as parent-material thinning before fracture. To avoid fracture at the weld joint, good formability and high yield strength of the weld is needed. FEM simulation showed that minimizing the width of the weld joint can reduce thinning of the weld.

Jan 1, 2004