Chapter 15

1. Chapter 15 Processing Resources

2. You have learned that natural resources are used to produce products and structures. There are several steps in the production process.

3. Primary processing The goal of primary processing is to convert material resources into industrial materials. Industrial materials are also called standard stock. For example primary processing is to converts wheat into flour; aluminum ore into aluminum sheets, bars and rods; logs into lumber, plywood, particleboard, hardboard, and paper; natural gas into plastic pellets, film, and sheets; and silica sand and soda ash into glass.

4. Extracting & Harvesting Material Resource Material Resource Primary Manufacturing Processing Recycling Industrial Material Consumer Product Secondary Manufacturing Process Using & Servicing Constructed Structures Industrial Product Construction Processing

5. Types of Primary Processing • Primary processing uses many production actions. They can be grouped in a number of ways. One useful way to group processes is by the type of energy used. • Mechanical processes. • Thermal (heat) processes. • Chemical and electrochemical processes.

6. In this chapter you will be introduced to the manufacture of several materials that you come into contact with daily. These materials include lumber, plywood, steel, glass, petroleum products, and aluminum.

7. Mechanical Processes Mechanical processes use mechanical forces to change the form of natural resources. They may use compression to crush the material to reduce its size or change its texture. Shearing forces to cut and fracture the material. Run the material over screens to sort it by size.

8. The processing of forest products uses two methods. The materials may be cut or sheared into new shapes. These mechanical actions are used to produce lumber, plywood, and particleboard. Other wood processing techniques use chemical action. Chemical processes are used to produce hardboard, cardboard, and paper.

9. Thermal Processes Many industrial materials are produced by processes that use heat to melt and reform a natural resource. This type or processing is called thermal processing. Widely used to extract metals from their ores, this process is often called smelting. Other thermal processes are used to made glass and cement. We will look at steel making. Use a combination of thermal and chemical processes. Thermal energy melts the material.

10. Duringthe melting process, chemical reactions take place to produce a new material. The new material is then shaped into standard stock. The shaping process uses mechanical techniques. The material is cast, drawn, rolled, or squeezed into new sizes and shapes.

11. Producing Steel Steel is an alloy, a mixture of iron and carbon. Adding other elements in small amounts gives the steel specific qualities. These elements include manganese, silicon, nickel, chromium, tungsten, and molybdenum. Steel with nickel and chromium is called stainless steel.Molybdenum steels are widely used for tools. Adding tungsten makes the steel more heat resistant.

12. Making steel requires three steps: • Iron smelting • Steel making • Steel finishing

13. Iron smelting produces pig iron, the basic input for steelmaking. Pig iron results from thermal and chemical actions that takes place in blast furnace. The blast furnace uses a continuous process. At no time is the blast furnace empty during the smelting process. Raw materials are added to the top and molten pig iron is removed from the bottom.

14. The operation of a blast furnace is simple. Alternating layers of iron ore, coke, and limestone are added to the furnace. The blast furnace is charged with four parts iron ore, two parts coke, and one part limestone.

15. Very hot air is blown into the bottom of the furnace. Coke burns, causing the iron ore to melt. The oxygen in the iron ore combines with the carbon to make carbon monoxide gas. During the melting, limestone joins with impurities to form slag. The slag floats on the molten iron and can be drawn off. This leaves molten iron with carbon dissolved in it. This material is called pig iron, which is iron with 3 to 4.5 percent carbon.

16. The steelmaking process starts with the pig iron produced in the iron smelting step. Steelmaking actually removes some carbon from the iron. Heat and oxygen are used to take some of the carbon out of molten pig iron.

17. The most common steelmaking process uses the basic-oxygen furnace. There are three steps to making steel in a basic oxygen furnace. The first step is charging. The furnace tilts to one side to receive pig iron, scrap steel, and flux, a material that combines with impurities to form slag. This charge provides the basic ingredients for steel.

18. The second step is refining. The furnace moves into an upright position and the charge is melted. Water-cooled oxygen lance is placed above the molten material. Pure oxygen is forced out of the lance into the iron at supersonic speeds. The oxygen causes the part of the carbon to burn away, producing steel and slag.

19. The final step is tapping. The floating slag is skimmed off the melt. The entire furnace tips to one side and the steel is poured out. It is now ready to enter the steel finishing cycle.

20. Steel finishing changes molten steel into sheets, plates, rods, beams, and bars. The first step involves pouring the steel into ingots or into the head end of a continuous caster. The caster solidifies the molten steel into shapes called slabs, billets, and blooms. A slab is a wide, flat piece of steel. Sheets, plates, and skelp are produced from them. Sheets are wide, thin strips of steel, while plates are thicker. Skelps are strips of steel that are used to form pipe.

21. Billets are square, long pieces of steel. Bars and rods are produced from them. A bloom is a short, rectangular piece used to produce structural shapes and rails. Many steels are finished. They may receive a zinc or tin coating. Zinc coated steel is called galvanized steel. It is used for automobile parts and containers, such as fenders, buckets and trash cans. Tin coated steel is called tin plate. Tin plate is widely used to make food cans.

22. Chemical & Electrochemical Processes Some primary processed use chemical or electrochemical actions. These are used to produce synthetic fibers, pharmaceuticals, plastics, and other valuable products.

23. Producing Aluminum The most common chemical and electrochemical process in use is the one to make aluminum.