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Патент USA US2122197

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June 28, 1938.
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F. |.. DUFFIELD
PRODUCTION OF IRON FROM IRON ORE
Filed May 4, 1937 k
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Q)
2,122,197
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3 Sheets-Shegt l
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‘June 28,1938.
F-L-DUFFlEl-D
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2,122,197
PRODUCTION OF IRON FROM'IRON ORE
Filed may 4, 19s?
. 3 Sheets-Sheet 2
June 28, 1938-
2,122,197
F. L. DUFFIELD
PRODUCTION OF IRON FROM IRON ORE .
Filed May 4, 19:57
‘ 3 Sheets-Sheet 2»
Patented June 28, 1938.’
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eUNiTED STATES PATENT, OFFICE
‘Frederick Lindley Dumeid, London, England
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Application May '4, 1937, Serial No. 140,618
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In Great Britain May 6, 1936
2 Claims.
(Cl. 75-1-29)
, This invention relates to the production of iron
from iron ore.
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cient to cause the slag to become viscous, with
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attendant wail adhesion, it ?oats on the surface
, Existing methods for producing, molten‘ iron
of such slag, and in that position exposes its car
of high purity are founded on the principle of,
purifying the crude product of the blast furnace»
bon contents to oxidation by the furnace gases,
such carbon thus faiiingin its .intended duty of 5
by treatment in the Bessemer or open hearth fur-
reduction of the iron oxides.
naces. The object of the present invention is to I
obtain pure iron (99.84%) directly from the ore,
thereby avoiding the inclusion of impurities
these defects which operate'against the practical
accomplishment of producing an iron conglomer
@ which entail subsequent elimination by re?ning
methods.
'
It has been found by experimentation that
ate or matter direct from the ore can be over-g m '
,
come by the present invention. _
In the past the production of so-called sponge
-
According to the present invention the iron
iron, i. e._ iron produced at temperatures below ore is mixed in a granulated state with carbo
fusion point, has been attempted to secure a base ' 1111060118 material, moulded _int0 blocks,‘ Slabs,
w of high purity which is intended for melting in
briquettes or other shaped bodies and charged“;
some suitable kind of furnace.
Great difficulty has been experienced in producing sponge iron in a practical manner, and
the applicant has found that even if economical
20 production "of sponge iron were accomplished,
into a furnace heated interiorly by combustion so
that they fall into and are submerged in a bath
of molten slag contained in said furnace, where
by the slag constitutes a protective coating for
the shaped bodies, ‘protecting them against the 20
the product, due to its powdery state and low
conductivity due to excessive porosity, is an’extremely inconvenient and 'dif?cult material to
oxidizing atmosphere of the oxidizing gases in
the furnace, and the reduction proceeds Within
the slagv coating by reason of heat absorbed
melt e?lciently in any kind of furnace.
from the slag,’ whereupon the ore is reduced and
25
>‘
One of the advantages claimed in the produc-
the iron Particles drop to the bottom and coa- 25
tion of sponge iron as an intermediate product
lesceand can be removed from the furnace in
for molten iron and steel production is its adaptability for concentration ,of its iron contents by
the form of relatively-large masses of semi
molten "on with some included slee
magnetic separation. ‘The applicant has found
‘ l The Slag can he removed from the iron mass
30 ‘from long experience that the iron contents or .\ discharged from the reductiolrchamber by sub- 80
the majority of- ores is so intimately physically “sequent treatment in an electric or other fur
combined with its gangue matter that the naceieltematively the slag may be'removed by a
latter becomes entrained in that which is mag- , mechanical Squeezing pl‘oces?
netic, and no su?icient elimination of the orig35 inai gangue matter of'the ore is achieved to rén-
The process may be carried out in apparatus
comprising’ an oscillating furnace provided with 35
der the process‘ serviceable~orfpracticable.U
- a (1001‘ for the discharge of the reduced metal, it
There havegbeen ‘attempts in" the past to re-
taphole for discharging slag, means forcharsine
duce and melt or semi-melt iron ore in rotary
the furnace, means for admitting heating gases
furnaces, "but by long "égpe'?ence it has been
40 found that certain salie'nt‘principles‘ are nece‘s-
into the furnace and an additional air inlet adja
cent to‘the exit" ?ue forJthe ‘heating 3945,95» this 40.
any ‘for ‘its; practical"v and ‘economical ‘accomplishment:
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t
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_Wh_en granulated vor. p0 ' red iron ore: vis
<45 m'xed w -h' ‘5 reqmmdquanmy of granulated
last an‘ ‘inlet ‘being arranged solthat the 9/11’ ad‘
‘
zniigedt‘thfez?by haste/direction which is" opposed
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38.565.
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3'
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The furnace should be of squat shape, that‘ is
to ‘say the length» should not exceed three times 45
ior p‘o'wde‘rqq ppm topmduqtiqn’ whet-ha firstly the diameter so that in; this way a: substantially
lr-‘iaduce-q"bx'heat-m-‘ied idireg?yinto‘“rotary ' uniform-1temperature?sufficiently-‘highto‘lmainn
no
furnace, upon semi-fusion it adheres to the side
tam the 515g in a‘v'k?uid state‘can'be ‘maintained
wallsof the revolving»,;furnace, incurring maxi-
lthrd?ghou?thefumace
expqsurejto. the. effect- ofrthe vxidlzinglrfur-
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' ‘The-invention " ill te-oestnteafwnn reierenee- to,
nece sasestiwhich bum :thetcoal-which:haswbeen
to the accompanying" drawings?'which'tillustrate
added =_for; thelpu-rpose of ?lling “itstfunction‘of
one formiof apparatus‘ which‘ may bewusedvfor
~reduction,~and<a:poorrresultis:
Evendfj fed/upon. abath bf-rmoltenslag
inevitable.atlsuch ‘ carrying;
.Fig. llillustrates
out‘ the, ainvention,
vertical sectionlofvthe
.1;
.
appa
‘55 -a-=-rat,eqthat its-urapid"heatiabsorption;iscinsu?b
ratus;
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2
2,122,197
all times throughout the period of operation is
Fig, 2 is a plan view; and
.
Fig‘. 3 is a central ‘cross section.
to enable the reduction of the iron oxides by
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The oscillating furnace at has a length about ' carbon to proceed and be completed at the low
temperatures, regulated by the conductivity of
twice its diameter and is mounted for rotation
on rollers b, b. “Fuel consisting of coal dust and ' the thickness of the mass constituting the block 5
air is admitted tangentially through aperture c
0r,-_briquette.
and additional
At temperatures ranging between 1150° C. and
1400" 0. fusion of the oxides of iron in combina
tion with silica is effected, producing ferroussili- I
cates, so that little or no practical reduction by 10
air is
admitted tangentially
through aperture d arranged in a‘cylindrlcal end
chamber e. The other ehd of the furnace is pro
10 vided with a main charging passage 1 and an
auxiliary charging passage 9 arranged in the wall
of the charging passage ,f. The passage f also
constitutes an exit ?ue for the gases of- combus
tion, and is completed by a movable ?ue k mount
15 ed on rollers so that it can be moved away’ from
the passage i when it is desired to charge through
this passage. An auxiliary air jet Z is provided
carbon takes place, since silica at such tempera
tures has a greater a?inity for iron oxides than '
carbon. Consequently unless the oxides of iron
are reduced at temperatures below their fusion
point, as provided by slow heat penetration of the 15
block or briquette, a preponderance of reaction
is in the formation of ferrous silicates. Thus if
’ granulated ore andvcarbon were fed in a loose
' in the wall of the passage 1'. and is directed towards the interior of the furnace, i. e. in a direc- ,
(non-briquetted) state on to a ?uid slag, the re
tion which is opposed to that of the exit gases.
A discharge door m is provided in the wall of the
furnace remote from a tangentially disposed tap
hole n for slag.
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spective particles of iron oxide and carbon would 20
fall in their desired reaction, the iron oxide’com
bining with the silica present in the slag and the
carbon being lost by the oxidation of the furnace
'
In order to carry out the process according to
25 the present invention the iron ore to be reduced
is granulated and mixed with a corresponding
quantity of granulated carbon sumcient to effect
the reduction of the iron oxides and attendant
moisture, and is pressed or moulded into blocks
30 or briquettes with a suitable binding agent. The
binding agent may beomitted if desired, as it is
gases.
,
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At temperatures higher than 1400° C. ‘the fer- 25
rous silicates dissociate=\ if su?cient carbon and
lime be present, and metallic iron is precipitated,
but the formation of ferrous silicates is un-'
desirable, ?rstly because of their erosive e?ect on
any furnace lining, and further the metallic iron :80
thus precipitated has not that purity that is ob
tained by its direct reduction at temperatures
.below its fusion point. To retain theslag in a
state of ?uidity advantage is taken of the low
rate of heat transfer to the block or briquette, ‘B5
not absolutely essential in themoulding oper
ation.
“ Slag is" introduced ?rst intothe furnace and is
heated by admitting burning gases from the inlet
apertures c and d until the slag is molten. This ‘ and the rate of feeding the charge is regulated
molten slag forms a liquid bed on the bottom of» to coincide with the heat supply.
the furnace into which the moulded blocks are
As the reduction proceeds the blocks disintev-e
introduced by charging either through the charg
grate/‘and the iron particles drop to the bottom
ing passage f, if the movable ?ue k is removed,
or through the charging passage 9', if the movable
?ue k is in the position shown in Fig. 1. The
momentum of the blocks or briquettes as they are
charged into the furnace causes them momen-'
of thefurnace and coalesce into one or more r40v
masses. When thereduction is ?nished the slag
is first drawn off through the taphole n and the
masses of coalesced iron particles are subsequent
ly discharged by gravity by rotating the furnace
tarily to be fully submerged ‘in the molten slag,
so that gravitation is lowermost.
which adheres to the colder surface of the block
quantity of slag is then reintroduced into the fur
or briquette and providesan enveloping protec
‘nace and the processis continued with a new
tion against oxidation.
a charge.
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The low conductivity of the block or brlquette,
by reason of its thicknesscompared with small
It is essential that the'slag should remain ?uid,
vand this is assisted by the slower uptake of heat
which, in gradually penetrating the blocks or bri
quettes, effects reduction of the oxide contents at
low temperature which is controlled by the limits
60 of its low conductivity. Complete reduction is
effected by this gradual heat penetration without
disturbing the equilibrium ofheat supply and
demand of combustibles and ?uid slag respec
tively.
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By making the furnace of relatively squat
shape, that is to say not too long relatively to
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‘blocks in process of reduction are burned before '50
leaving the furnace by means of the auxiliary
sudden and rapid absorption of heat which would
render the receiving bath of slag surllciently vis
cous ‘to adhere to the walls of the furnace.
'
The combustible gases which emanate from the
granular pieces of ore and coal, prevents a too
751
A sufficient :45
air admitted through the air jet l, which helps to
maintain the required temperature at the outlet
._
endof the furnace‘.
.
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a
,
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in a- recuperator or regenerator with theheat of
the combustion products after leaving the oscil
lating fiu'nace, either prior to or after such com
bustion products have been partially used for cal- '60
cining or drying the ore before being formed‘into
, briquettes.
.
The oscillating furnace shown in the drawings
rotates approximately 270° in’ one direction and
then through a corresponding angle in the re- 65
verse direction. Other forms of furnace may be
its diameter,_the slag melting temperature is re
tained throughout the whole length. If the
length of the furnace were too long relatively to
its width it will be evident that the temperature
at the outlet end of the furnace would fall below
that required 'for making and maintaining the
slag fluid, so that the latter‘ will adhere to the
used for carrying out the process according to the
wall of the furnace and thus cause obstruction.
cording to the present invention readily yields to
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_
All the air admitted through the various air in- ‘55,
lets may be pre-heated, for example by contact
invention.
‘
It has been found by experience that whereas
sponge iron presents the utmost difficulty in melt- 70
ing in the electric furnace by reason of its poor
heat conductive power caused by its excessive
porosity, the conglomerate mass obtained ac
Another reason for keeping ‘the slag ?uid at _ the heat of the electric furnace, and a rapid melt’rglsi...
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2,122,107
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ensues with e?‘icient separation of the molten - against the oxidizing atmosphere of the oxidizing
metal and the minimum of metallic inclusions in gases in the furnace, and the reduction proceeds
within the slag coating by reason of heat ab
the slag.
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What I claim and desire to secure by Letters sorbed from the slag, whereupon the'ore is re
duced and the iron particles drop to the bottom
Patent is:'
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1. Process for- producing iron from iron ore and‘coalesce and can be removed irom the fur
nace in the form of relatively large masses of
which consists in mixing‘the iron ore in a gran
semi-molten iron with some included slag.
ulated state with carbonaceous material, mould
2. Process, according to claim 1 further con
ing the mixture into blocks, slabs, briquettes or
10 other shaped bodies and charging the said shaped sisting in admitting a separate supply of air into
the furnace in a direction opposed to that of the
bodies into a furnace heated interiorlyiby com
bustion so that they fall into and are submerged outlet gases for burning the gaseous reaction
in a bath of molten slag contained in said fur
nace, whereby the slag constitutes a protective
15 coating for the shaped bodies, protecting them
products resulting from the reactionbetween the
iron ore and carbon of the blocks or the like.
FREDERICK LINDLEY DUFFIELD.
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