Manufacture of Compressed Compound Blocks of Substances Con- taining Iron and Carbonaceous Matter, and the Use of such Blocks in the Production of Cast Steel and Ingot Iron.
Year: 1889

page_text: Manufacture of Compressed Compound Blocks of Substances Con-
taining Iron and Carbonaceous Matter, and the Use of such
Blocks in the Production of Cast Steel and Ingot Iron.
1, LUIGI IMPERATORI of Milan, Italy, Engineer, do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
My invention relates to the manufacture of compressed blocks of substances con-
taining iron and carbonaceous matter and the employment of such blocks in the
manufacture of cast steel or ingot iron. The invention consists mainly in mixing
suitable combinations of iron, such as iron ores, iron oxides, slags rich in iron &c.
and suitable reducing agents, such as coal, charcoal, coke &c. both reduced to a
pulverulent condition, and converted into suitably shaped solid blocks by pressure,
which blocks are then smelted in reverberatory furnaces with or without addition
of other ingredients, for producing the desired description of ingot iron or steel.
For the above purpose, the iron ores, iron oxides, slags rich in iron &c., if not
already existing in pulverulent form, are reduced to powder by suitable crushing or
grinding apparatus, and in like manner the reducing agent, whether charcoal,.coke,
anthracite, coal, peat &c. is crushed or ground, and after mixing the two ingredients,
the mixture is moistened with water, and well stirred together until it appears
perfectly uniform, and a sample thereof will be found to cohere when pressed
together. The compound is then either stamped or otherwise pressed in moulds, and
the blocks so obtained are allowed to dry in the air for some days under a shed.
About twelve hours before they are required for use, the blocks are placed near the
smelting furnace so that they may be perfectly dry before being introduced into the
latter.
In the furnace the said blocks replace either partially or entirely the lumps used in
the ordinary Martin process, or the smelting may be effected without the use of the
pig iron bath of that process. It is a characteristic feature of the said blocks that
in either case they do not crumble away when being charged into the furnace any
more than do the lumps in the Martin process. The surface of the block at once
receives a metallic lustre, and the reduction takes place in the most perfect and rapid

page_text: manner, in consequence of the intimate admixture of the constituents and the close
contact of the particles due to the pressure to which they were subjected.
Numerous gas flames soon appear on the surface of the blocks, while they gradually
sink together until they are completely melted.
If the mixture of the pulverised materials is not effectually compressed in the first
instance then, notwithstanding the moistening, the flues or regenerators of the furnace
would soon be destroyed, as the powerful gas currents would carry large quantities of
dust into them from the blocks.
The reducing process would also be less perfect in this case, as it would be retarded
owing to the want of intimate contact of the particles which have to act on each
other.
The removal of the slag formed on the hearth can be effected in the same way as in
the known basic process in the Martin furnace.
The success of the process is dependent upon the composition of the iron ores,
inasmuch as, firstly, these must be very rich in iron, and must contain at least from
one to two per cent. of Manganese, while the carbonaceous material used must contain
little sulphur, and give little ash; secondly, the iron ores must, in the case of an acid
furnace-lining, only contain traces of sulphur and phosphorus, while with a basic
lining, they must also contain but little sulphur.
For the production of the blocks are suited, more particularly, iron ores which
contain no combined water such as magnetic iron ores, roasted Spathic iron ores,
haematite, also rolling-mill scale.
The oxides of these, namely, are converted, by the addition of water and the
moisture of the atmosphere, partially into hydrated iron oxide, H. Fе. O,, and this
substance hardens like cement.
Iron ores with hydrated iron oxide can be used for the production of the blocks,
when mixed with other suitable oxides, but if they are to be used without admixture
they must first be roasted, or be mixed with binding materials, such as lime and tar.
In preparing such blocks salt water or sea water can be used with advantage in
place of fresh water.
In certain circumstances it is advisable to add to the compound of iron ores and
carbon, a quantity of pulverised lime, limestone or dolomite.
For determining the proper proportions of the carbonaceous material and the iron
ore to be used for the blocks, the rule must be observed that the addition of the
reducing agent must generally be confined within such limits that the iron will be
reduced without being afterwards subjected to carburation by an excess of carbon.
The proportion may vary in the case of coke between 20 and 25 per cent. of the
quantity of iron ore used; with coal on the other hand it may vary between 24 and
35 per cent.
When an addition of fluxing materials is employed, the above mentioned two
different modes of application of the blocks have to be differently treated.
When the blocks are used in place of the lumps in the Martin process, the
simultaneous reducing action of the pig-iron bath comes in aid. The proportion of
carbonaceous matter in the blocks is therefore reduced to about 20 per cent. ; the
iron ore which may not be entirely reduced by this proportion will then be dissolved
by the slag and be gradually reduced by the carbon of the melted pig-metal.
If, on the other hand, the blocks are smelted without the use of the pig metal bath,
a higher percentage of charcoal or coke has to be used, and the percentage of lime,
alumina or silicic acid for the blocks will be determined in the same manner as with a
mono or bi-silicate. Lastly, the proportion of carbon can be so determined that,
after smelting, the metal bath shall already have the desired percentage thereof.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The manufacture of compressed blocks for the production of ingot iron and
steel, composed of iron ores, oxides, or slags and carbonaceous bodies, such as coal,

page_text: anthracite, charcoal coke, peat charcoal, and the like, which substances are mixed
together in pulverulent form, moistened, and compressed with or without the use
of fluxing materials such as lime, dolomite, and the like substantially as herein
described.
2. The manufacture of cast steel and ingot iron by means of blocks such as are
referred to in the preceding claim, by smelting the latter either alone or with pig-
metal or iron or steel lumps substantially as herein described.
ABEL & IMRAY,
Agents for the Applicant.