METAL ELEMENTS IN HUMAN LIFE

IRON

Iron is the most important element in the lives of mankind since the times of ancient Mesopotamia to today's modern era. No other metals that their use exceeds the amount of iron. Very reasonable if the production of iron metal in the world reached 1 billion tons / year.

The main iron ore is hematite. (Fe2O3). Other ores are magnetite, pyrite and siderite. Place the iron ore mining in Indonesia is in Cilacap, Central Java and in some places in East Java were smelting iron ore and steel industry located in Cilegon, West Java.

a. The use of iron
Iron is the metal most widely enough usage, that is about 14
times the total use of all other metals. This is didasrakan by:
1. Iron ore is relatively abundant and scattered in several places around the world.
2. Processing of iron is relatively easy and inexpensive.
3. The properties of iron easily modified.

The major use of iron is to make the steel that can be used to create toys, kitchen tools, industrial vehicles, construction of buildings, bridges, railroads. Stainless steel is widely used to make tooling sepereti scissors, screwdrivers and keys, kitchen tools such as spoons and pans. Famous steel is stainless steel as a combination of iron with chromium (14-18%) and nickel (7-9%) which has the properties of hard, clay used to make weapons and wire.

b. Metal Processing
There are 2 stages to process iron, which is aiming to reduce the smelting of iron ore so that the re-smelting of iron and useful in the manufacture of steel.

Iron smelting carried out in a blast furnace (blast furnaces). Blast furnace is a building about 30 meters high and has a diameter of about 8 feet made of stainless steel coated with heat resistant brick. Materials used are carbon reduction denagan reaction principle:
  2FeO3 +3 C
  4Fe + 3CO2

Materials included in the furnace there are 3 kinds:
• iron ore sand littered
• Carbon (coke) as a reducing agent
• Limestone (CaCO3) to bind the sandy dirt (flux)
The temperature in the reaction is very high so that the iron is called pig iron melt and
(Pig iron).

Liquid iron is generally immediately processed to make steel. But, also dilairkan into molds to make cast iron (cast iron) containing 3-4% carbon and less impurities such as Mn, Si, P. Iron-containing carbon is very low (0.005 to 0.2%) is called wrought iron (wrought iron).

Sebagaifluks limestone function, namely to bind the acidic impurities, such as SiO2 to form slag. Slag formation reactions are as follows. At first, decompose the limestone to form calcium oxide (CaO) and carbon dioxide (CO2).
  CaCO3 (s)
  CaO (s) + CO2 (g)
Calcium oxide then reacts with sand to form calcium silicate, a major component in the slag.
  CaO (s) + Si O2 (s)
  CaSiO3 (l)
This slag floats on liquid iron and must be issued within a certain time interval.

c.Pembuatan steel
Steelmaking process are:
1. Lowering the carbon content of 3-4% in pig iron menjaadi 0 to 1.5% by mengoksidasikannya with oxygen.
2. Disposing of Si, Mn, and P and other impurities through the formation of slag 3. Adding metal crate aliase Cr, Ni, Mn, V, Mo, and W in accordance with the type of steel desired.

Tegnologi processing of pig iron into steel in a cheap fast distinction was introduced by Henry Bessemer tahun1856. in 1860 developed an open fireplace (open herth furnace) by William Siemens. Today more stoves are made with oxygen furnace furnace bassemer is not used anymore.

Various kinds of substances added to the processing of steel which is useful as a "scavangers" (binding impurities), especially for the oxygen and nitrogen. Scavangers most important thing is aluminum, ferrosilicon, and ferotitan feromangan. These substances react with nitrogen or dissolved oxygen to form oxides which is then separated into the slag.

Steel can be classified into 3 groups, namely;
1. Carbon steel, composed of iron and carbon.
2. stainless steel (stainless steel), has low carbon content and contains about 14% chromium.
3. Aliase steel is a special steel containing a certain element pursuant to the desired properties.

To prevent perkaratan on steel can be done by:
1. Adding other metals.
2. Using the protective layer.
3. Using a metal that can be sacrificed.
4. Protecting the cathodic.