Book NotesSustainability Considerations - Steelo Steel is one of the world’s most recycled materialso 2007 – 78% of all steel was recycledo The recycle rate for construction structural steel was 97.5%o More steel is recycled than paper, aluminum, glass, and plastic combinedo The depletion of equality raw materials will require even more recycling and development of different production methods for steel products if the current rate of use of steel is to continueo Disadvantages of using lightweight steel framing instead of wood framing Steel is not a renewable source unlike wood The high thermal conductivity of the metal framing when compared with that of woodo Advantages of using lightweight steel framing instead of wood framing Cost and ease of construction and less to environmental concerns Easier to handle on the job and easier to erect Less scrap to dispose of on a job siteo Iron ore, coke, and limestone are the principal materials used in making iron- Aluminumo 14% of aluminum used in US is used in constructiono Expensive to produce primary aluminum because of the refinery process which uses an electricityo The energy used to produce a pound of aluminum is about 7 times that needed to produce a pound of steel o Energy management must be prime objectives for the aluminum industryo Recycling aluminum saves almost 95% of the energy and emissions associated in productiono 2001 – 33% of recycled aluminumIron and Steel Materials and Productso Ferrum - Chemical element that is the chief ingredient of the metals known as iron and steelo Ferrous Metals – generic name of the iron-based alloys o Iron is mined as iron ore, which is the chief source of irono Iron and steelmaking involve extracting iron from ore, combining it with carbon and other elements, and then forming it into shapeso Pure iron is soft, ductile, easily shapes, and relatively weako Wrought Iron – nearly pure iron that is strong enough for many construction purposeso the many irons and steel used in modern construction and manufacture get their strength and hardness mainly from the element carbono Most steels have the best combination of properties when carbon is present in amounts less than 1.2% Ferrous metals containing substantially larger amounts of carbon become so hard and brittle that they cannot be readily shaped by either got or cold working methods These metals are formed by being cast into molds and are referred to as cast iron- Raw Materialso Iron and steelmaking starts with the separation of the metal iron from its oxide, which is the way iron appears in iron ores This is done by heating iron ore while it is in contact with coke – a form of carbono Coke (fuel) – a fuel with few impurities and a high carbon content, usually made from coalo Pig Iron – a carbon rich crude iron whose name comes from the shape of the trenches into which the molten iron from early furnaces ran The iron was poured into a main trench and ran along it into smaller connected trenches where it hardened into ingotso The primary raw materials used to make pig iron are iron ore, fuel (coke), air, flux, and refractories o Taconite & Jasper – names referring to a wide variety of iron-bearing rocks with iron contents ranging between 22% and 30%- Beneficiationo Beneficiation - process that improves (benefits) the economic value of the ore by removing the gangue minerals, which results in a higher grade product (concentrate) and a waste stream (tailings)o The beneficiation of ores generally consists of Grinding and concentrating them to increase the iron content  Agglomeration, which increases the ore’s particles to a size suitable for blast furnace use- 2 forms of agglomeration are pelletizing, used for jasper and taconite, and sintering, used to recycle iron ore dust- Direct Reductiono Direct reduction includes various processes in which ore is concentrated to a high iron content comparable to that of molten iron from a blast furnace - Fuelso Of the 3 main fuels used in the iron and steel industry – coal, oil, and natural gas – coal supplies more than 65% of the industry’s heat and energy requirements o The chief fuel used in a blast furnace is coke, which is produced in coking ovens from selected types of bituminous coal-- Fluxeso Fluxes – minerals that have an affinity for the impurities in iron ore or pig irono They combine with these impurities and separate them from the molten metal in a furnace by forming a liquid slago Classified as basic or acid Basic – limestone and dolomite Acid – sand, gravel, quartz rock - Refractorieso Refractories – nonmetallic materials with superior heat and abrasion resistance used as linings of steelmaking furnaces, flues, and vessels- Alloy Oreso Alloy – a metallic substance made by combination of metal with other types of elements generally done in order to enhance properties like strength, ductility, corrosion resistance, etc. o Ore – a source of minerals which occurs naturally usually found in forms of rockso Manganese – all steel contains manganese, improves hardness and wear resistanceo Chromium – provides stainless steels with resistance to heat, rust, and corrosion To other alloy steels and cast iron, it provides hardness and wear resistance Important as a coating metal o Nickel – increase hardness Steel containing nickel are especially suitable for case hardening, the process of surface hardening by absorption of carbon at high temperatureso Silicon – serves as a deoxidizer and as an alloying element When used in large percentages, it enables cast irons to withstand highly corrosive acidso Tungsten – provides heat resistance and is used in cutting tools of high speed steel and to make tungsten carbide, an abrasion-resistant material almost as hard as a diamond o Molybdenum – increases hardness and corrosion resistance of steelso Vanadium – used in conjunction with other alloying elementso Boron – used as a hardening agent in steel- Iron Makingo Smelting – a metallurgical operation by which metal ore is heated to separate the metal in it from impurities with which the metal may be chemically combined or physically mixedo Reduction – the separation of chemically combined iron and oxygen o Pig iron is made in a blast furnace by smelting, which extracts the iron by reduction of its oxide and by physically separating it from other impurities- Steel Makingo Requires lowering the carbon