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Патент USA US2134103

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Patented Oct. 25, 1938
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UNITED STATES PATENT OFFICE ..
‘No Drawing. Application March 2, 1937,
Serial No. 128,669
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(01. 15-1)
’ - This invention relates to the treatment of ores
for the bene?ciation thereof.
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I
tures of advantage, some of which, with the fore
going, will be set forth in the following descrip
In various of the known deposits of iron ore
throughout the world and in particular those of
f: the Missabe Range of the Lake Superior district,
there are large bodies of ore which have physical
characteristics making them heretofore undesir-
tion. In this description, for the purpose of exam
me, there is set forth the best embodiment of
the invention now known, but such embodiment
is to be regarded as typical only of many possible
able or unsatisfactory as sources for the manufacture of pig iron. The Missabe Range contains
ited thereto. The present invention is of par
ticular value in the treatment of vcertain.types
1" large deposits of two typesof ore which it has
hitherto been uneconomical to utilize. The Missabe ores are mainly soft and hydrated hematites
and limonite, and they vary» in condition from very
of iron ores which have hitherto been considered,
because of theirphysical conditiomeither impos
sible of utilization for the extraction of their iron
content, or uneconomical for such ‘purpose be
?ne dust to fairly coarse and granular ore and
15 there are also large quantities of so-called sandy
cause of the prohibitive cost of correcting and
handling them, _
the reducing furnace and they also give rise to
ores from which the free moisture will not readily
large amounts of ?ue dust. For these reasons
evaporate naturally consists in intimately mixing
they are considered not very attractive as sources
with such ores a water absorbent medium which
embodiments, and the invention is not to be lim
ores. The dusty and sandy ores'tend to choke up
, In a broad aspect the treatment herein for wet ~
20 for the production of pig iron.
has an affinity for the\water of the ore greater .20
Another type of ore, of which there are large than that of the ore for the water and from which
quantities in the Missabe Range particularly, is - medium water will evaporate. In other words,
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the very wet or muddy type which has hitherto the ore is treated with a material that will draw
been considered practically valueless because of the water out of the ore in a manner which may
25 the low concentration of iron due to the presence ' be'conveniently referred to as capillary» action.
of considerable water. Water or moisture adds
to the weight of ore to be transported. Some of
The water is then allowed to evaporate from the
absorbent medium leaving a relatively dry mix.
the soft ores of the Lake Superior region contain ture or agglomeration of dehydrated ore and dried '
as much, as 9% of their weight as hygroscopic absorbent medium. It is found as a Part Of the
139 water, and some as much as 25%. This moisture‘ invention, that a highly satisfactory» absorbent 3
content is quite constant under varying weather
medium having‘the above described and other de
conditions.
sirable characteristics‘, is cement, preferably Port
Since the moisture is distributed
evenly throughoutthe ore, it does not evaporate
readily and the added cost of transporting and
3-3 handling so much moisture makes these ores very
uneconomical. It has been proposed to remove
land cement.
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In practice, there is‘ added to the crude wet ore
as it comes from the mine, about 6% by weight 3
of Portland cement. The materials are ‘then
, the excess'water by sintering, but the cost of so
thoroughly mixed such as in an ordinary cement .
doing is generally prohibitively high.
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The prime object of the present-invention is
4'.) to provide for dehydrating such ores or freeing
mixer or other suitable apparatus, carebeing
taken not to exert any substantial crushing ac
?lm, and the mixture is then Spread-Out 0n the
, them from the water content thereof in a sim-
ple, inexpensive, expeditious and eminently satisfactory manner, so as to reduce the weight of a
given amount of ore and thus facilitate the han43 dling, transportation and storage of the treated
ore while at the same time putting the ore in a
ground, floor or other, suitable surface in a rela
tively thin layer. In a'shed at ordinaryatmos
pheric temperatures it is found that the material
will" dry and that a substantial amount of the ~
free or suspended moisture will evaporate in about
twenty-four hours. The setting and drying of
condition for satisfactory and economical reduc-
the material may be hastened by the application
ing in a blast or other reducing furnace.
of a relatively small amount of heat. It is gen
A further object is to provide for the beneficia-
erally preferable not to heat the mixture above
50 tion of ores in a manner which is effective not
212° F; and it is found that the most economically
only for the correction of the ores, but which will
extend influence and benefits to the reducing operation for the extraction of the desired mineral
constituents of the ore.
55 The invention possesses other objects and fea-
satisfactory drying temperature is around 200° F.
Heating above 212° F. tends .to drive off the water
of crystallization, which is not desirable, and may
also exert some destructive effect upon the chem
ical composition of the ore by its converting ac- 55
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a,is4,1os
the iron mineral contained therein.‘v The ore is
10 naturally from said ore. It is found, however,
that the‘ moisture in the ore has a greater a?inity for cement than for the ore particles, and.
when about 6% by weight 01' Portland cement
is thoroughly mixed with the ore, practically all '
15 of the tree moisture is absorbed by the cement
material and it will then readily evaporate from
the cement, leaving the ore dehydrated ‘or with
cientiy free from water that it may be economi~
nuxing properties oi ordinary limestone which is
‘ basic ?ux in the blast furnace,
As an example of the concentrating elects oi
I the present method 01' benei'iciation, the follow
ing tables are illustrative:
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Table 1' represents an ?nalysis 0! a- typical
wet and muddy hematite ore or limonite ore
carrying 20% by weight of free or suspended
water and in‘ which they concentration of M0,,
the desired mineral, is only 57.12%.
cally and satisfactorily utilized.
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Table 2 is an analysis of the dried or set mate‘
20‘ The exact nature of this action and-the man- rial resulting from the admixture with an ore
25 by the cement in thehydration reaction. How-
to constitute 67.12% and forming a material of
to have entirely lost the major portion of its
, I
water content and the weight .01’ the material
,
tab’? 1
correspondingly decreased. Possibly, thismay be
80 due to continuing evaporation oi’ water from ad-
1
Per cent
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Table 2
a
by "618m
Per cent
by weilht
.ia'cent the outside surface of the ccmentvcoating
F920:--------- -, 57-12
F820: _________ _-
of the ore particle accompanied by the conse-
510: --------- _-
8.00
S10: _________ __
quent ability and strong tendency of the cement
MnOz____v ____ __
1.60 MnO:_____>__-_-
to take up from the ore particle more water to
A1201 --------- _-
I‘ replace that lost by evaporation. A noticeable I Ignition loss-~-
6-48
67.12
9.40
‘180 l
A120: ______ __4_-
7.00
5-30 1811mm! loss____
8.00
change inthe wet ores after the hereindescribed
H20---------- -- 20.00, Cement ______ -_
, --~-
—_
character or structure of the ore, which is
100-00
1100.00
treatment with cement occursv in the physical
6.00
40 granular form approaching a gravel-like condi- ' comprises a method or "?tment for the bene_
45 change in the physical condition or structure ‘of
The cement surrounds and coats each indi-
viduai particle of ore and it is not desirable to
what is claimed
tam undesirable amounts of
ms” c water
and of‘ changing the“. form tolgmt appprgacmnz
ream]? broken up for transportation to and 1'e‘ hygroscopic water and thereby e?ecting concen
ducmg 1.“ the blast furnacetration of the ore, and whereby elimination of
The above described treatment Wm "111°"! water and hardening of the cement causes the
practically all of the free or suspended water so
treated ore to name a granular condition
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