Ferrous Scrap and its Collection and Recycling...

Ferrous Scrap and its Collection and Recycling Ferrous scrap also referred to as, iron and steel scrap, or simply scrap comes from end of life products (old or obsolete scrap) as well as scrap generated from the manufacturing process (new, prime or prompt scrap). It is metal that contains iron. Iron and steel scrap can be processed and re-melted repeatedly to form new products. Due to the value of metal in the ferrous scrap, it is recycled or reused wherever it is possible.  In fact, ferrous scrap is being recycled long before current awareness of environmental concerns started. Ferrous scrap is generated during the production of iron and steel, fabrication or manufacture of iron and steel products, or when the product made of iron and steel reaches its end of life. Due to the high value of the metal, the ferrous scrap is largely being recovered. Given the chemical and physical properties of the material, iron and steel produced from ferrous scrap can, in almost all applications, compete with primary iron and steel produced from ore. However the amount of scrap collected and finally recovered depends on many factors, such as the collection system, the possibility and techniques used for the collection, etc. as well as a variety of legislation. The main sources for ferrous scrap are those products, for which iron and steel is the main constituent. These are namely, vehicles (including ships and rail coaches and wagons), products of construction, machinery, electrical and electronic equipment, and packaging etc. There is a difference between carbon steel scrap and stainless steel scrap since the carbon steel differs from stainless steel by composition and treatment. Carbon steel scrap is mainly used for the production of steel in induction furnace (IF), electric arc furnace (EAF) and partly...

Clean Steels

Clean Steels There are various definitions of clean steel. The term clean steel is also vague. Clean steels are generally those steels that have low levels of the solute elements sulfur, phosphorus, nitrogen, oxygen and hydrogen; controlled levels of the residual elements copper, lead, zinc, nickel, chromium, bismuth, tin, antimony and magnesium; and, a low level of non metallic or oxide inclusions. The requirements vary with the steel grade and its end use. Clean steels used for one application may be often not acceptable for a different use. Steels with low levels of solutes are sometimes termed as ‘high purity steels’ while steels with low percentage of tramp elements are often called ‘low residual steels’. Sometimes steels with a low frequency of product defects that can be related to the presence of oxide inclusions are called clean steels. Hence the definition of ‘clean’ is not absolute. Instead it is based upon the product formed from the casting and the in-service use or life of the product. In addition, the definition ‘clean’ is comparative since the cleanliness standard desired by the customer is continuously changing as a function of time and technological improvements. The term ‘clean steel’ is therefore continually variable depending upon the application. Effect of solute elements on steels The individual or combined effect of solute elements such as carbon (C), phosphorus (P), sulphur (S), nitrogen (N), hydrogen (H) and total oxygen (T.O.) is known to have a remarkable influence on the steel’s properties, such as tensile strength, formability, toughness, weldability, cracking resistance, corrosion resistance, and fatigue resistance etc. The extent of control of the solute elements needed in the steels depends on the performance expected from the steel. The influence of the solute elements on the properties of steels is given in...

Use of Hot Metal in Electrical Arc Furnace Jun04

Use of Hot Metal in Electrical Arc Furnace...

Use of Hot Metal in Electrical Arc Furnace Steel making by the electric arc furnace (EAF) has very good flexibility with respect to the selection of charge materials. The traditional charge material for the EAF process has been 100 percent cold scrap but as the issues regarding scrap such as its availability and quality, market price fluctuations and restrictions imposed by scrap in making some steel grades due to residual elements and nitrogen level etc. have increased, EAF operators intensified the search for alternative iron materials. Direct reduced iron (DRI), hot briquetted iron (HBI), pig iron (PI) and hot metal (HM) are the alternative iron materials which have been used in varying percentage successfully by EAF operators. The use of hot metal is more popular in those areas where there is shortage of scrap and/or electric power. The source of hot metal is blast furnace hence hot metal can be used in those EAFs which are in close proximity of the blast furnace, otherwise the EAF operator has to use pig iron. Pig iron will need extra energy for its melting. Presently EAF can be designed for using up to 80 percent of hot metal in the charge. Influence of HM on key parameters of EAF process In recent times the main emphasis in EAF steel making has been related to achieving maximum energy efficiency. Further the feed charge materials are influencing the design of the EAFs and their operation practices. The influence of HM as a charge material on various key parameters of an EAF process of steel making is detailed below. Residual elements – Residual elements also known as tramp elements cannot be removed from the steel during processing. Therefore, the amount of these elements in the product is a direct function...

Direct Reduced Iron and its Production Processes Mar16

Direct Reduced Iron and its Production Processes...

Direct Reduced Iron and its Production Processes Direct reduced iron (DRI) is technically defined as iron ore which has been reduced to metal without melting it. Hot briquetted iron (HBI) is a densified form of DRI to facilitate its handling and transport. History The first patent was in 1792 in United Kingdom presumably utilizing a rotary kiln but the development of the modern direct reduction (DR) process began in the middle of 19th century. Since 1920 more than 100 DR have been invented and operated. Most of them have not survived. The modern era of DR production began on December 5, 1957 when the HYL process plant first started production at Hylsa. The  first plant using Midrex process came into operation in May 17, 1969 at Oregon Steel mills in Portland, Oregon. DRI Production process A DRI production process is one in which the solid metallic iron is obtained directly from solid iron ore without subjecting the ore or the metal to fusion. The process principle is shown in Fig. 1. Fig 1 DRI process principle Major DRI production processes are either gas based or coal based. Feed material in a DRI process is either iron ore sized to 10 to 30mm or iron ore pellets produced in an iron ore pellet plant. In the gas based plant the reactor, the reduction reaction takes place is a shaft furnace. The shaft furnace works on counter current principle where the iron ore feed material moves downward in the furnace by gravity and gets reduced by the up flowing reducing gases. The pressure and temperature in shaft furnace in HYL process is 5-6 bars and 800-850 deg C. The same in Midrex process is 1-1.5 bar and 800-850 deg. C. In a coal based plant the...