Graphite Electrodes Production and Optimization Practices

Graphite Electrodes Production and Optimization Practices Graphite electrodes are used in both DC and AC electric arc furnaces. Companies who use electric arc furnaces have to cover the cost of these consumable electrodes during production, so optimizing the usage of graphite electrodes is a money-saving opportunity. This paper aims to discuss the production process of graphite electrodes as well as industry practices that are used to enhance the life of electrodes. To produce a graphite electrode, carbon is required. The carbon source for graphite electrodes comes from the petroleum industry as a by-product from the oil refining process. In the refining of crude oil, hydrocarbon chains are cracked in coking units and the resulting fuels are then separated as kerosene, gasoline, and diesel. As chains of hydrocarbons are being cracked in this process, pure carbon becomes deposited on the sidewalls of the coking units. The carbon on the sidewalls accumulates up to a certain point when it is the ground out of the unit. This carbon is called petroleum coke, or petcoke. This is the carbon source for graphite electrodes. After the petcoke is obtained from the oil refinery, it is blended with pitch to make a plastic-like material. (Making a UCAR ® Graphite Electrode) This blend of petcoke and pitch is then extruded through a circular die and cut off in sections. It is then baked at a temperature of above 800 degrees Celsius for a period of one to two weeks. After baking, the electrode is impregnated with more pitch to increase the density of the electrode which lowers electrical resistance and makes it stronger. The electrode is then re-baked at a slightly lower temperature to drive off volatiles found in the pitch. Finally, the electrode is heated to a temperature of about 3000 degrees Celsius to recrystallize the carbon into graphite. This final heating is called graphitization. Graphitization is very important in electrode manufacturing because it provides better mechanical strength and also improves electrical conductivity. The final step in electrode production is machining. The electrodes are machined to specific tolerances. This is especially important at the ends of the electrodes where the joints connect. (D. Klein) A good connection between joints is necessary for mechanical and electrical properties of the electrode. Electrode consumption takes on two forms: Continuous consumption and discontinuous consumption. (Richard J. Fruehan) Continuous consumption contributes 90% of total electrode consumption while discontinuous consumption only accounts for 10%. Even though discontinuous consumption accounts for far less than continuous consumption, discontinuous consumption can also account for furnace downtime which can cost a lot of money. So even though it is a small percentage, it is worthwhile to try to prevent it for the sake of productivity. In continuous consumption, the tip and sidewalls oxidize and the mass of the electrode is reduced. Tip consumption is a function of current and angle. Higher currents and steeper tip angles both yield faster oxidation rates of electrodes. (A. Lefort) Higher currents increase the temperature of the electrode which favors a faster oxidation rate. The steeper the tip angle, the closer the electrode needs to be to the steel bath to arc. Steel is more likely to splash onto the electrode if it is closer to the bath. One way to reduce the oxidation rate of electrodes is to cool them. Water cooled electrodes have been shown to reduce the oxidation rate of the sidewalls by 40% and the tip by 50%. One issue with water cooled electrodes is the flow rate of the water. If the flow rate is too high, water will pour into the furnace and increase the heat loss. The loss of heat can end up costing more than the money saved from reducing electrode consumption, so this is an important factor to conside r in this process. In discontinuous consumption, one of the most obvious techniques to prevent electrode breakage is simply to not ram the electrodes into the steel scrap. Graphite is a soft, brittle material and steel scrap is pretty hard and durable. If these two materials come head-to-head, the steel wins. Another method of discontinuous consumption is tip spalling. (A. Lefrank) This is more prevalent in DC furnaces than in AC furnaces because the DC electrodes see higher temperatures and therefore higher thermal stresses. The temperature gradient can be significant in the tip of a DC electrode and the thermal expansion of graphite can cause enough stress on the tip to break off small pieces. (J. E. Surma) Normally, the arc in a DC furnace will move about randomly, but occasionally the arc will sit in one spot, heating up that portion of the electrode tip creating thermal stresses that cause the tip to spall. Arc deflection control is a practice that has been implemented so when the arc becomes fixa ted on one spot, it will essentially â€Å"push† the arc out from that spot to get it to move about in a random fashion once more. Another practice to prevent the discontinuous consumption of electrodes is to ensure proper torque is applied when installing new electrode segments. The vibrations from the furnace and electromagnetic forces due to the flow of electricity give electrodes a good shaking. This can jostle the segments loose from their joints. This is mainly a problem in DC furnaces because AC furnaces are designed to ensure that the electromagnetic forces work to their advantage. In AC furnaces, the phase sequence is counterclockwise, so the forces on the electrodes due to the electromagnetism of the system only ever tightens the electrode joints. Below is a chart of recommended torque according to electrode diameter from SGL Carbons website and an AC furnace schematic of forces due to phase sequence. One final practice that helps prevent the failure of electrode joints is to turn off the water spray for a few minutes after the addition of another electrode segment. (Richard J. Fruehan) The temperature gradient is much steeper when the water spray operation is active. This thermal gradient can cause a problem when it reaches the joint because of the thermal expansion of graphite. Even if the electrode was tightened with the proper amount of torque, the effects of temperature on the electrode joint is enough to loosen it. This coupled with the furnace vibrations could be enough to cause the electrode joint to fail. In conclusion, graphite electrodes are an essential part of electric arc furnace steelmaking. Since they are consumable, any way to improve the life and efficiency of an electrode saves money in the steelmaking industry. Practices such as water cooling electrodes and optimizing current and tip angle are effective ways of reducing the oxidation of electrodes while taking care not to impact the scrap during melting, ensuring proper torque during installation, and turning off the water spray while adding another segment all help reduce breakage and joint failure. Works Cited: A. Lefort, M. J. Parizet, S. E. El-Fassi and M. Abbaoui. Erosion of Graphite Electrodes. J. Phys. D: Appl. Phys. 26 (1993): 1239-1243. A. Lefrank, W. J. Jones, and R. G. Wetter. DC Steelmaking Conditions and Electrode Performance. Electric Furnace Conference Proceedings 53. Warrendale: Iron and Steel Society, 1995. 337-346. D. Klein, K. Wimmer. DC Electrodes A Key Factor for Progress in EAF Production. Metallurgical Plant and Technology International 18:4 (1995): 54-63. Graphite and Carbon Electrodes. 6 December 2009 . J. E. Surma, D. R. Cohn, D. L. Smatlak, P. Thomas, P. P. Woskov, C. H. Titus, J. K. Wittle, R. A. Hamilton. Graphite Electrode DC Arc Technology Development for Treatment of Buried Wastes. Waste Management 93 Symposia. Tuscon, 1993. Making a UCAR ® Graphite Electrode. 2007. 6 December 2009 . Richard J. Fruehan, Ph.D. The Making, Shaping and Treating of Steel 11th Edition. Richard J. Fruehan, Ph.D. The Making, Shaping and Treating of Steel 11th Edition. Pittsburgh: The AISE Steel Foundation, 1998. 562-574.

Compare and Contrast All Quiet on the Western Front and Dulce et Decoru

The poem "Dulce et decorum est" by Wilfred Owen has a lot In common with "All Quiet on the Western Front." By Erich Remarque although Remarque never fought in the 1st World War. The Imagery in the prose is more detailed as it has more time to describe everything "The fields are flat." Some people think that this is better and it gives it a bit more feeling. Were as in the poem, Owen uses lots of short hard hitting words such as "Obscene as cancer" The poem gives a much more immediate effect in a shorter space of time. The imagery in the poem is quick and dramatic. The titles of the pieces are ironic "All Quiet on the Western Front" and "dulce et Decorum est" which means it is fitting and right. In the Poem everything is tired in the first stanza "Of tired, outstripped Five-Nines" This is a hyperbole as bombs don't become tired. The whole of the war became a sluggish battle. It is also a slow pace to start with in the prose with men looking forward to getting back the huts for some rest. "I wish I were back home. Home - he means the huts" In the second Stanz...

Is Walmart Good for America?

Wal-Mart: An Epic Idea â€Å"Save Money, Live Better. † A greeter welcomes you into the phenomenal discount store we Americans call Wal-Mart. A one stop shop for just about anything and everything you need, Wal-Mart is a major investment to America: 1) Wal-Mart is one of Americas most leading discount stores 2) Wal-Mart employs many people 3) Wal-Mart sells its products for a lower price, making it more favorable to consumers. In 1962, the first Wal-Mart was founded in Rogers, Arkansas. Its growth and succession has lead to its spread around the world. One man, one vision; Sam Walton’s mission was to save people money to help them live a better quality lifestyle. With its earnings and its improvements, Wal-Mart has played a major role in America’s economy. The first Wal-Mart was found in 1962. The year the birth of discount retailing began. The chain of variety stores that Sam Walton owned during the 1950’s faced stiff competition from the many regional discount stores. Before the opening of Wal-Mart, Mr. Walton traveled the country studying just about everything about discount retailing. He noticed that American consumers wanted a fresh new type of store. Acting on instinct, Sam and his wife Helen invested about 95 percent of their income into their first Wal-Mart store in Rogers, Arkansas. In 1972, many other discounters expanded, yet Wal-Mart only opened 15 stores. Later, Wal-Mart stock was offered to the New York Stock Exchange. With the infusion of capital, the company then grew to 216 stores in 11 states by the end of the decade. By the year of 1981, there were 1402 Wal-Mart stores. Employment had increased tenfold; sales had grown from 1 billion in 1980, to 26 billion. Today, 8416 stores and club locations have been opened. Wal-Mart employs more than 2. 1 million associates, serving more than 176 million customers a year. Wal-Mart is a perfect example of how to manage growth without losing sight of your values. America’s most popular discount store, Wally’s World beats all saving stores that promise you some sort of discount. Sam Walton quotes â€Å"If we work together, we’ll lower the cost of living for everyone†¦we’ll give the world an opportunity to see what it’s like to save and have a better life. † In the past 40 years, Wal-Mart has opened 16 markets worldwide. Wal-Mart works with their suppliers to introduce more energy efficient products that can save money for customers’ money for years to come. Wal-Mart saves us as consumers’ money, to improve our way of living. Wal-Mart has teamed up with Mercy Corps and USAID to help small farmers in Guatemala, that’s why you see the Fair Trade Coffee on shelves at Sam’s Club. By collaborating with their communities and suppliers, Wal-Mart helps improve the lives of others. Wal-Mart has a major impact on America’s economy. A leader in sustainability, corporate philanthropy, and employment opportunity, Wal-Mart has ranked number one among retailers in Fortune Magazine’s 2009 Most Admired Companies. Since 2005, Wal-Mart stores have averaged a net sale of 342. 14 billion dollars. Wal-Mart Stores cash flow gas increased 5943 million dollars from Jan, 31 2008- Jan, 31 2009. For the past five years, Wal-Mart has been excelling in their business. Now, more than ever, Wal-Mart is there for their customers. There has been a strong growth; net sales have increased 6. 8 percent to 255. 7 billion. Segment operating income has also increased 7. 1 percent to 18. 8 billion. Wal-Mart has introduced the Project Impact store remodeling plan, under this plan, Wal-Mart expects to update 700 new and existing stores this year, with over 3600 stores in the United States. Walmarts main goal is to save consumers money to improve the quality of their lives. I can definitely say that Wal-Mart is a positive for America. A discount store opened up in Arkansas, now only 40 years later, a major corporation. Wal-Mart helps people, its philanthropic ways have encouraged the store to help others outside the circle of consumers. Economically, Wal-Mart has increased and improved. Who knew one man with a vision could encourage so much growth. Wal-Mart is indeed, good for America. Is Walmart Good for America? Wal-Mart: An Epic Idea â€Å"Save Money, Live Better. † A greeter welcomes you into the phenomenal discount store we Americans call Wal-Mart. A one stop shop for just about anything and everything you need, Wal-Mart is a major investment to America: 1) Wal-Mart is one of Americas most leading discount stores 2) Wal-Mart employs many people 3) Wal-Mart sells its products for a lower price, making it more favorable to consumers. In 1962, the first Wal-Mart was founded in Rogers, Arkansas. Its growth and succession has lead to its spread around the world. One man, one vision; Sam Walton’s mission was to save people money to help them live a better quality lifestyle. With its earnings and its improvements, Wal-Mart has played a major role in America’s economy. The first Wal-Mart was found in 1962. The year the birth of discount retailing began. The chain of variety stores that Sam Walton owned during the 1950’s faced stiff competition from the many regional discount stores. Before the opening of Wal-Mart, Mr. Walton traveled the country studying just about everything about discount retailing. He noticed that American consumers wanted a fresh new type of store. Acting on instinct, Sam and his wife Helen invested about 95 percent of their income into their first Wal-Mart store in Rogers, Arkansas. In 1972, many other discounters expanded, yet Wal-Mart only opened 15 stores. Later, Wal-Mart stock was offered to the New York Stock Exchange. With the infusion of capital, the company then grew to 216 stores in 11 states by the end of the decade. By the year of 1981, there were 1402 Wal-Mart stores. Employment had increased tenfold; sales had grown from 1 billion in 1980, to 26 billion. Today, 8416 stores and club locations have been opened. Wal-Mart employs more than 2. 1 million associates, serving more than 176 million customers a year. Wal-Mart is a perfect example of how to manage growth without losing sight of your values. America’s most popular discount store, Wally’s World beats all saving stores that promise you some sort of discount. Sam Walton quotes â€Å"If we work together, we’ll lower the cost of living for everyone†¦we’ll give the world an opportunity to see what it’s like to save and have a better life. † In the past 40 years, Wal-Mart has opened 16 markets worldwide. Wal-Mart works with their suppliers to introduce more energy efficient products that can save money for customers’ money for years to come. Wal-Mart saves us as consumers’ money, to improve our way of living. Wal-Mart has teamed up with Mercy Corps and USAID to help small farmers in Guatemala, that’s why you see the Fair Trade Coffee on shelves at Sam’s Club. By collaborating with their communities and suppliers, Wal-Mart helps improve the lives of others. Wal-Mart has a major impact on America’s economy. A leader in sustainability, corporate philanthropy, and employment opportunity, Wal-Mart has ranked number one among retailers in Fortune Magazine’s 2009 Most Admired Companies. Since 2005, Wal-Mart stores have averaged a net sale of 342. 14 billion dollars. Wal-Mart Stores cash flow gas increased 5943 million dollars from Jan, 31 2008- Jan, 31 2009. For the past five years, Wal-Mart has been excelling in their business. Now, more than ever, Wal-Mart is there for their customers. There has been a strong growth; net sales have increased 6. 8 percent to 255. 7 billion. Segment operating income has also increased 7. 1 percent to 18. 8 billion. Wal-Mart has introduced the Project Impact store remodeling plan, under this plan, Wal-Mart expects to update 700 new and existing stores this year, with over 3600 stores in the United States. Walmarts main goal is to save consumers money to improve the quality of their lives. I can definitely say that Wal-Mart is a positive for America. A discount store opened up in Arkansas, now only 40 years later, a major corporation. Wal-Mart helps people, its philanthropic ways have encouraged the store to help others outside the circle of consumers. Economically, Wal-Mart has increased and improved. Who knew one man with a vision could encourage so much growth. Wal-Mart is indeed, good for America.

Richman Investments “Internal Use Only” Data Classification Standard

Richman Investments â€Å"Internal Use Only† Data Classification Standard The â€Å"Internal Use Only† data classification standard at Richman Investments will include the most basic IT infrastructure domains to include the User Domain, Workstation Domain, and the LAN Domain. This will encompass all users and their workstations, as well their access to the internet and company server databases and any information in between. The User Domain will enforce an acceptable use policy (AUP) to define what each user can and cannot do with any company data shall he or she have access to it.As well as with company users, any outside contractor or third-party representatives shall also need to agree and comply with the AUP. All users must be properly identified and sign this AUP prior to gaining any access whatsoever to the company network. No exceptions. Any violation will be taken up with company executives and/or the authorities to assess further punitive action. The Workstatio n Domain includes all workstations approved on the company network. No personal devices or removable media may be used on this network. All devices and removable media will be issued by the company for official use only.To access any workstation, a user will need to be first verified, then setup with an account to be logged in with a username and pass code adhering to the IT departments set standards. All systems will undergo regular updates and be provided with anti-virus and anti-malware software for system monitoring. Access Control Lists (ACLs) will be drawn up to appropriately define what access each individual will have. Any violations will cause an immediate suspension of privileges and again the person(s) in violation will be subject to company executives decisions and/or the authorities for punitive action.The LAN Domain will include all data closets, physical elements of the LAN, as well as logical elements to be designated by authorized personnel. Authorized personnel wil l be properly screened and authorized by the IT department head and given a special access card with separate pin code as well their normal username and pass code. Each closet will require this special access card and code to gain admittance. Each server will also require this card and code along with separate username and login credentials.Any hardware, software and equipment is to be installed by these persons only on any machine. Along with that, they will assure proper print, e-mail, and file server setups. They will also be responsible for designating access to users according to ACLs. This includes setup and securing any company Wireless Access Points (WAPs) for use with company devices only. Any violations will be cause for immediate removal of special access rights and suspension of privileges. Again they will be dealt with by company executives and/or the authorities for further punitive action.