Chemical elements
  Iron
    History of Iron
    Mineralogy
    Isotopes
    Energy
    Production
      Detection
      Estimation
    Application
    Physical Properties
    Chemical Properties
    Corrosion
    Iron Salts
    PDB 101m-1aeb
    PDB 1aed-1awd
    PDB 1awp-1beq
    PDB 1bes-1c53
    PDB 1c6o-1ci6
    PDB 1cie-1cry
    PDB 1csu-1dfx
    PDB 1dgb-1dry
    PDB 1ds1-1e08
    PDB 1e0z-1ehj
    PDB 1ehk-1f5o
    PDB 1f5p-1fnp
    PDB 1fnq-1fzi
    PDB 1g08-1gnl
    PDB 1gnt-1h43
    PDB 1h44-1hdb
    PDB 1hds-1i5u
    PDB 1i6d-1iwh
    PDB 1iwi-1jgx
    PDB 1jgy-1k2o
    PDB 1k2r-1kw6
    PDB 1kw8-1lj0
    PDB 1lj1-1m2m
    PDB 1m34-1mko
    PDB 1mkq-1mun
    PDB 1muy-1n9x
    PDB 1naz-1nx4
    PDB 1nx7-1ofe
    PDB 1off-1p3t
    PDB 1p3u-1pmb
    PDB 1po3-1qmq
    PDB 1qn0-1ra0
    PDB 1ra5-1rxg
    PDB 1ry5-1smi
    PDB 1smj-1t71
    PDB 1t85-1u8v
    PDB 1u9m-1uyu
    PDB 1uzr-1vxf
    PDB 1vxg-1wri
    PDB 1wtf-1xlq
    PDB 1xm8-1y4r
    PDB 1y4t-1ygd
    PDB 1yge-1z01
    PDB 1z02-2a9e
    PDB 2aa1-2azq
    PDB 2b0z-2boz
    PDB 2bpb-2ca3
    PDB 2ca4-2cz7
    PDB 2czs-2dyr
    PDB 2dys-2ewk
    PDB 2ewu-2fwl
    PDB 2fwt-2gl3
    PDB 2gln-2hhb
    PDB 2hhd-2ibn
    PDB 2ibz-2jb8
    PDB 2jbl-2mgh
    PDB 2mgi-2o01
    PDB 2o08-2ozy
    PDB 2p0b-2q0i
    PDB 2q0j-2r1h
    PDB 2r1k-2spm
    PDB 2spn-2vbd
    PDB 2vbp-2vzb
    PDB 2vzm-2wiv
    PDB 2wiy-2xj5
    PDB 2xj6-2ylj
    PDB 2yrs-2zon
    PDB 2zoo-3a17
    PDB 3a18-3aes
    PDB 3aet-3bnd
    PDB 3bne-3cir
    PDB 3ciu-3dax
    PDB 3dbg-3e1p
    PDB 3e1q-3eh4
    PDB 3eh5-3fll
    PDB 3fm1-3gas
    PDB 3gb4-3h57
    PDB 3h58-3hrw
    PDB 3hsn-3ir6
    PDB 3ir7-3k9y
    PDB 3k9z-3l4p
    PDB 3l61-3lxi
    PDB 3lyq-3mm8
    PDB 3mm9-3n62
    PDB 3n63-3nlo
    PDB 3nlp-3o0f
    PDB 3o0r-3p6o
    PDB 3p6p-3prq
    PDB 3prr-3sel
    PDB 3sik-3una
    PDB 3unc-4blc
    PDB 4cat-4erg
    PDB 4erm-4nse
    PDB 4pah-8cat
    PDB 8cpp-9nse

Iron Production





Production

The main volume of produced iron is in forms of cast iron and steel. The main iron metallurgical principles did not changed during millenniums. The furnace-charge consists of iron oxide ore, coke and flux such as dolomite CaCO3 MgCO3, while a blast of heated air is forced into the furnace at the bottom. In the furnace, the coke is burnt in oxygen of the air blast to produce carbon monoxide. The carbon monoxide reduces the iron oxide (III) ore to molten iron, becoming carbon dioxide in the process:

2Fe2O3 + 3CO = 4Fe + 3CO2

The steel manufacturing is based on melting of cast iron in the presence of oxidizers, during which the carbon concentration falls until 1.5-2%, as a result FeO is formed and involved in redox reaction, in which the impurities are oxidated and iron is reduced.

The highly pure iron (containing less than 0,001% contaminations), prepared by carbonyl complex: distillation and chemical decomposition of purified iron pentacarbonyl Fe(CO)5 which in its turn is the product of commercial iron treatment under pressure, at 150-200°C by carbon monoxide. The carbonyl iron, which usually has the appearance of grey powder, is the product of this process.


Preparation of Iron

  1. One of the earliest methods of obtaining a pure iron consists in reducing ferrous chloride by heating in an atmosphere of hydrogen. The iron is deposited in the form of cubic crystals of microscopic size.
  2. Reduction of iron oxide, carbonate, or oxalate in a current of hydrogen results in the formation of a very pure iron. The reaction is fairly rapid at 600° C., but higher temperatures are more efficient, whilst at lower temperatures the product is usually contaminated with ferrous oxide.
  3. Iron may be reduced from its salts by means of zinc. Thus at high temperatures ferrous chloride is reduced by zinc vapour, whilst aqueous solutions of ferrous salts are reduced by metallic zinc at their boiling-points, yielding finely divided iron.
  4. An exceptionally pure form of reduced iron has been obtained by Lambert and Thomson by reduction of pure, colourless crystals of ferric nitrate. The crystals were first converted into oxide or basic nitrate by ignition in an iridium boat. The whole was then introduced into a silica tube and heated in an electric resistance furnace to just above 1000° C. in a current of pure hydrogen gas, obtained by the electrolysis of barium hydroxide solution.
  5. Electrolytic Iron. - Iron may be obtained in a high state of purity by electrolysing a mixed solution containing 20 per cent, of ferrous sulphate (calculated as FeSO4.7H2O) and 5 per cent, of magnesium sulphate (MgSO4.7H2O). Some 25 grams of sodium hydrogen carbonate are added to every 6 litres of the solution, whereby a skin of ferric hydroxide forms on the surface of the bath and protects the liquid from oxidation. A precipitate settles to the bottom and is allowed to remain undisturbed. An anode of wrought iron is employed, the cathode being made of copper, thinly silvered and iodised, and maintained in rotation. The best results are obtained with a current density of 0.3 ampere per sq. decimetre of cathode, and a temperature of 15° to 18° C. The bath is kept continuously at work, and 20 to 25 grams of carbonate are added every three or four days.
Both the magnesium sulphate and the sodium hydrogen carbonate appear to be essential constituents of the bath, and the good quality of the metal is attributed to the small concentration of hydrogen ions which prevents the deposited iron from containing occluded hydrogen.

Numerous attempts have been made to prepare iron by the electrolysis of ferrous chloride, but with this salt an elevated temperature is essential for good results, namely, 60° to 70° C. The current density at the cathode should not exceed 0.4 ampere per sq. decimetre, and the quality of the deposit is improved by rotation of the cathode.

According to Noyes, the minimum potential required for the electrolysis of an aqueous solution of a ferrous salt at 20° C. is 0.66 volt, when electrodes of electrolytic iron are employed. This value falls by 0.007 volt per degree rise in temperature up to 110° C., when it attains a minimum. Further rise in temperature necessitates an increased voltage.

Hicks and O'Shea recommend the electrolysis of a 5 per cent, solution of ferrous chloride to which ammonium chloride has been added in sufficient quantity to establish the ratio

FeCl2 to NH4Cl = 1 to 2.

Any ferric chloride present is reduced to ferrous by shaking with reduced iron. A thin copper plate serves as cathode, is cleaned with dilute nitric acid, rubbed with cotton-wool and sand, and finally washed with potassium cyanide and then with water. Swedish iron constitutes the anode, and is placed in a porous cell to prevent the spongy carbon, which normally separates from the metal, from reaching the cathode. The sulphur in the metal passes into solution as sulphate, and requires removal at intervals with the anode liquor. A current of 0.08 to 0.2 ampere per sq. decimetre of cathode surface is recommended, the voltage being 0.7. The iron content of the bath should not fall below the equivalent of about 4 per cent, of ferrous chloride.

Skrabal obtained a very pure iron by electrolysis of a solution of ferrous ammonium oxalate, the metal being deposited on a cathode of platinum foil. The electrode thus prepared was now used as anode in an acidified solution of ferrous sulphate, an E.M.F. of 0.4 volt being employed, the cathode again consisting of platinum foil. The metal thus obtained was white and crystalline; it dissolved slowly in warmed, dilute sulphuric acid, leaving no residue, and evolving a pure, odourless hydrogen. To prevent oxidation of the bath, the electrolysis was carried out in an atmosphere of carbon dioxide, and the cathode separated from the anode by means of a porous diaphragm. Excellent results were also obtained with ferrous ammonium sulphate. With this salt a concentration of 70 grams of the hexahydrate (NH4)2SO4.FeSO4.6H2O per litre is recommended, with a maximum cathode current density of 0.5 ampere per sq. decimetre, working at a temperature of 15° to 18° C., or not less than 26 grams per litre, with a cathodic current density of 0.2 to 0.65 ampere per sq. decimetre, the surface of the bath being protected from oxidation by a layer of solid paraffin, a stirrer being employed, and the wrought-iron anodes enclosed in linen bags; or a saturated solution, with a current density of 1 ampere at 30° C. Acidified solutions of ferrous sulphate have been used under various conditions, the best results being obtained, according to Pfaff, with a current density of 2 amperes per sq. decimetre at the cathode, a temperature of 70° C., and a concentration of at least two equivalents of ferrous sulphate per litre and 0.01 equivalent of sulphuric acid.

Electrolytic iron deposited from solution at ordinary pressures and temperatures is apt to be admixed with ferric hydroxide, and to contain hydrogen and carbon. The last-named element is commonly derived from the oxalates or tartrates in the baths, when these are used, and as the result of transfer from the anodes. The carbon may be free, combined as carbide, or present as occluded carbon monoxide or dioxide.

Electrolytic iron is frequently brittle, a property that is usually attributed to occluded hydrogen, but there are probably other auxiliary causes.

Iron has also been obtained from solutions of its salts in organic solvents by electrolysis between platinum electrodes. A solution of ferric chloride in methyl chloride conducts electricity well, and may be used for the purpose. Produced in this way, however, the metal is particularly liable to be contaminated with carbon.

Electro-deposition of Iron on Copper

Deposits of iron are frequently applied to engraved copper plates to harden their surfaces and thus increase their life for printing purposes. Various solutions are recommended for this purpose. A simple one yielding good results consists of

Ferrous ammonium sulphate1 lb. or 100 grams.
Water1 gallon or 1 litre.


This solution must be perfectly neutral for use. Another useful mixture contains ferrous chloride and ammonium chloride in molecular proportions to the extent of 50 to 60 grams per litre, or

FeCl2.2NH4Cl½ lb., or 50 grams.
Water½ lb., or 50 grams.


This works well with a current density of 0.15 to 0.17 ampere per sq. decimetre, the initial density being 0.2 ampere until a thin deposit has been obtained on the cathode. Voltage 0.7. The anodes should consist of pure Swedish charcoal iron. These become covered with a black carbonaceous slime after a time, and require cleaning. It is desirable that the anodic area should somewhat exceed that of the cathode.

Electro-deposition of Copper on Iron

It is frequently desirable to protect iron by coating it superficially with copper. The following bath is recommended for the electro-deposition of this metal upon iron -

Copper sulphate60 grams.
Sodium hydroxide50 grams.
Sodium potassium tartrate159 grams.
Water1000 grams.


with a cathode density of 0.1 to 0.5 ampere per sq. decimetre and an anode density not exceeding 1.04 amperes. As this bath evolves no dangerous fumes, it is preferable to cyanide baths.
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