Chemichal articles: IRON

Iron is the most important metal in the development of human civilization since the time of ancient Egypt until the modern age as it is today. This metal is the fourth most common element found on earth. Fe metals are present in hematite minerals (Fe2O3), magnetite (Fe3O4), pyrite (FeS2), and siderite (FeCO3). The most processed iron ore is Fe2O3, an iron sand containing SiO2 compounds. The processing of iron ore takes place on a blast furnace.

Blast furnace, ironwork process

Furnace height, way of obtaining iron

Reaction:

600 ° C: 3Fe2O3 + CO -> 2Fe3O4 + CO2

850 ° C: Fe3O4 + CO → 3FeO + CO 2

1,000 ° C: FeO + CO → Fe + CO2

1,300 ° C: CO2 + C → 2CO

1,900 ° C: C + O2 → CO2

The mixture of ingredients incorporated into the furnace comprises:

A) Fe2O3 iron ore still mixed with sand (SiO2) and aluminum and phosphorus oxides,

B) coke as reducing agent,

C) limestone (CaCO3) which serves to bind acidic impurities.

The mixture of the ingredients is fed into the furnace through the top. Underneath there is a hole to remove the reaction products in the form of gas. As fuel is used very hot air through the pipes connected with four stoves. The air is heated to a temperature of 1100 ° C. The pipes are 3 meters and the base of the furnace. The main result in the form of liquid iron and a by-product of slag (slag) is removed through two holes located at the base of the furnace.

The reaction process that occurs inside the blast furnace is as follows.

Very hot air reacts with coke to form CO2 at the base of the furnace.

C (s) + O2 (g) → CO2 (g) ΔH = -394 kJ

CO2 gas then rises through a hot coke layer resulting in CO gas formation reaction.

CO2 (g) + C (s) → 2CO (g) ΔH = +173 kJ

Coke and CO will reduce Fe2O3 through several stages.

Coke and CO will reduce Fe2O3 through several stages.

At 600 ° C, Fe2O3 is reduced to Fe3O4:

3Fe2O4 (s) + CO (g) → 2Fe3O4 (s) + CO2 (g)

At 850 ° C, Fe3O4 is reduced to FeO:

Fe3O4 (s) + CO (g) → 3FeO (s) + CO2 (g)

At a temperature of 1,000 ° C, FeO is reduced to an iron metal:

FeO (s) + CO (g) → Fe (l) + CO2 (g)

At high temperatures, the resulting iron metal is liquid and flows into the base of the furnace. If there is acidic waste (SiO2) then CaCO3 is added. High temperatures cause CaCO3 to break down into CaO (lime tohoR) and CO2 gas. This lime is able to bind the excess sand (SiO2), aluminum oxide, and phosphorus oxide

CaCO3 (s) → CaO (s) + CO2 (g)

SiO2 (s) + CaO (s) → CaSiO3 (l)

Al2O3 (s) + CaO (s) → Ca (AlO2) 2 (l)

P2O5 (s) + 3CaO (s) → Ca3 (PO4) 2 (l)

The mixture of calcium silicate, calcium a1uminate and calcium phosphate is called slag and flows into the base of the furnace. On the base of the furnace, the slag will float over the molten iron and protect the molten iron from the possible reoxidation process. Iron produced in this process is pig iron which contains 95% Fe, 4% C, and 1% Si. Pure iron is very hard and can be cooled as cast iron.

Cast iron (wrought iron) can be used for the manufacture of objects that hold the press, for example chains and anchors on ships. To convert the iron to another form, the carbon content in the crude iron should be reduced, for example steelmaking should have a carbon content of between 0.5% -1.5%. Steel making can be done in several ways such as by Bessemer exchanger, with open heart furnace, and with oxygen furnace. In order to shine and resist rust usually mixed chrome and nickel metal. For example, stainless steel is a mixture of 72% iron, 19% chromium, and 9% nickel. Some types of steel and its properties

Additional Element Type Properties

Manganese steel 11% - 14% Mn Very hard, strong, durable

12% - 18% Cr Chrome Steel Rust and heat

Ni nickel steel 25% Ni Strong and corrosion resistant

Stainless steel 18% Cr, 8% Ni Rust resistant