Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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~l2~730~
TITkE:,
Proce~R for ~ lomer~tion of Mineral Ore Particles
Utillz~n~ a ~lxtul~L~ LdroxYeehylcellulose
~nd Sodium C~rbonAt~
Field of the Invention
Thls inventlon relates to ~ process for
~gglomerating or pell~tizlng miner~l ore particles
by commingling the miner~l ore particles with a
binding amount of ~ ~ixture of hydroxyethylcellulose
and sodium c~rbonste. Thls lnventlon ~lso relates
to pellets of minersl ore produced by ~uch ~ process.
B~ck~round o the Inventlon
Certain mineral ores, ~uch as iron ore,
must be reduced to finely divided p~rtlcles for the
purpose of benificlation. It i3 often necessary to
agglomer~te the~e partlcles to f~cilitate su`bsequent
h~ndling ~nd storAge of the miner~l ore, e.g., ~or
efficlent proce~ing in ~ bl~t ~urn~ce. This
Qgglomer~tlon h~lps to pravent dusting, crumbling or
c~kin8 o~ tha ore. The pellets, sinters or
briquet~es thus formed ~rom thi~ ~gglomer~tlon
proce~ should be porous and su~1ciently skrong
enouKh ~o re~ist ~braslon ~nd crumbllng durlng
s~or~ge and h~ndling.
Known methods ~gglomer~te the ore p~rtlcles
wlth blnders such ~ hydroxyethylcellulose,
bentonite clsy, ~ mixture of bentonite and ~ S08p,
portl~nd cement, sodlum ~illc~te or a mixture of an
~lk~li s~lt of c~rboxymethyl-cellulose ~nd en ~lk~
metal salt. Use of these Xnown blnders, howev~r, i~
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sometlmes dlsadv~ntsgeous. For ln~itfince, the
p~llets formed may l~ck ~u~lc~ent re~l~t~nce to
abr~ion; or the p~llet~ m~y cont~in und~sir~ble
level~ of contaminatlng compound~; or ~n undei~irably
hlgh rstio o~ binder to ore msy be necess~ry fvr
effeclent ag~lomer~tion.
Accordingly, it i8 an ob~ect of the present
invention to provide 8 proces~ for ~gglomerQt~ng
mineral ore particles ~hich does not iguffer from the
disadvan~ges described ~bove. A p~rtlcular ob~ect
of th$s lnventlon ls to provlde a novel proce~s for
~gglomer~ting mineral or~ p~rticlei~ whlch comprlses
commingling the mineral ore partlcles with ~ binding
~mount o~ ~ mixture of hydroxyethylcellulosie and
sodium c~rbonflte. Another obJect of this invention
is to proYlde novel mlner~l ore pelleti~ produced by
this procei~s.
DescrlPtl~o~of the~ Inven.tion
This lnvention relates to ~ process ~or
agglomer~tion o~ miner~l ore p~rticles whlch
comprise~ commln~ling the mlneral ore p~rtioles with
Q binding amount of ~ mlxture of
hydroxyethylcellulose ~nd sodium carbon~te, ln the
prei~ence oiE wster. The binding amount of the
mlxture wlll v~ry dependlng upon the agglomer~tlon
method to be used, the n~ture of the ore and the
propertles desired in the pelletis of the miner~l ore
thus formed. In gener&l the binding amount o~ the
mixture wlll be an amount Rre~ter than about 0.01%,
calcul~ted on the welght of the dry ore. For iron
ore p~rtlcle agglomer~tion the prefer~ble amount of
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~he ~lxtur~ r~s~r th~n ~bout O.O5S, ealculated
on the weight of ~he dry ore.
In princ~el ~11 eype2 of ~sssn~islly
~ter-solubla hydroxyethylcellulo~e can be used to
produce mlxture~ useful ln the proce~s of ~hls
lnv~ntlon.
The ~lxture of hydroxyethylcel 1U1Q8e and
sodium c~rbonate ç~n be usQd alone or ~n combinstlon
~l~h 8 ~uit~ble carrier~ ~ sult~ble c~rrisr for the
purpo3e of thls inven~ion 18 ~ carrier which ls
w~ter-dlsperssble snd which has no deleteriou~
~ffect on the blndlng o~ the mixture with the
minersl ore. Sultable csrrier~ include clQy~, such
~s bentonite, gums, such ~ gu~r gum, complexin~
agents, ~uch as sodium tctrsborate, or other
lnor~anlc ~Alts, ~uch ~s sodium chloride or c~lcium
carbonste.
The mlxture oF hydroxyethylcellulose ~nd
sodlum cQrbon~te cont~lns sodium c~rbon~te in an
AmoUnt o ~t le~t 2~, prefer~bly 8re~ter th~n 25~,
c~lculated on the total weight of the mixture.
Prefer~b~y the concentr~tlon of sodlum carbonate
will vflry ~rom ~bout 25~ to sbout 75~, more
pre~erAbly From ~out 30~ to 6S% ~nd mo3t prefer~bly
from ~bout 40~ to ubout 60~, c~lcul~ted on the total
weight of th~ mixture of hydroxye~hylcellulose and
~odlum carbonate.
The weter present in the agglomerstion
mixture m~y be ad~usted durln~ or prlor to ~ddltion
of the mixture of hydroxyethylcellulose ~nd sodium
carbonate eo the ore. The ~mount of wster present
18 the amount necessary for sflt~f~ctory
~gglomerstlon. This amount wlll vary dependln~ cn
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~L2~L7306 '` )
~ype of miner~l ore u~ed snd the desired propertles
o~ the QgglomerQt~d ore particles but, in general,
18 equal to or ~rester than ~bout 5~ o the ~et
mlxture. Pre~er~bly the ~mount o~ ~ter r~nge~ from
about 5S to ~bout 20S of the wet mixture. For
proper pI59ticlty of lron ore pellet~ the pre~erred
amount of w~ter r~nges from about 7~ to ~bout 12S of
the wet mixture.
Commlngling the miner~l ore pArticles wi~h
the mixture 3f hydroxyethylcellulQse and ~odium
c~rbonate can be ~ccomplished in any mRnner commonly
used for ~gglomer~tion purposes, ~uch ~s in
convention~l disc pelletizer or rolling drum
pelletizer, or in a roll press.
The pellet~ thus formed ~re referred to ~s
"green" or "r~w" pellets. These pellets possess
limited ~mount o~ structur~l ~trength.
Con~quantlyl the green pellets ~re then dried for
about 0~5 hour to Rbout 24 hour~, pre~erubly from
about l hour to ~bout 2 hours, ~t elevated
temper~ture~, preeerQbly between ~bout 100C to
~bout 300C. During this drylng st~p the pellets
reach their m~ximum ~tren~th. The strength and
qu~lity o~ ~he ore pellet is usually ch~r~cterlzed
by quantlties ~uch a8 drop number and compressive
8 tren8th.
The present invention will be further
described in the following ex~mples.
Example I
Equ~l ~mounts by weight of
hydroxyethylcellulose (solutlon viscoslty of 6000
centlpoise ~ me~sured on a 1~ aqueous solution on 3
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Brookfield Vi~cometer on ~ ~o. 4 splndle ~t 30 rpm)
~nd sodium csrbon~te were uniformly mixed in ~ twin
ahell blender to be u~ed ~8 the binder composi~ion.
Finely dlvlded iron ore pertieles were
initi~lly homogenlzed ~nd moisturized wlth w~ter in
drum until the moi~ture content of the ore w~s
~bout 4~0 Sample~ ~30 Kg. e~ch) of the moistened
ore were m~nuslly mlxed with v~rious smounta of the
binder composition for one minute And then uniformly
fed into a di~c pelletizer. W~ter was ~ed to the
disc by ~ proportloning pump through two spr~ys to
att~in the deaired percentage of mo~sture in the
pellets ~see T~ble I).
The pellets thus produced ran8ed ln size
from lO to 14 ~m. The "green" pellets for e~ch
re~pectlve concentr~tion of binder ~nd w~ter were
segmented into lot~ of 15 each for testing:
I. Drop Test
This te~t consl~ted oP droppin~ the green
pelle~ ~rom ~ height o 450mm onto an lron b~se.
The ~ver~ge number o~ drop~ requlred to c~use
~r~cture of ~he 15 pellets in the lot is the drop
number.
II. Compres~lve Stren~th
A. Green Pellets
Thl~ t~t conslsted of loading each pellet
to breakage with the ald o~ a hydraulic pres~ moving
at ~ const~nt speed of 50mm/min. The number
~epresents the aver~ge compresslve strength 1n 8r~ms
required to bre~k the pellet~ o~ e~ch lot.
~ . Dry Pellet~
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(~ 124r730~
Green pellet~ produc~d by the ~gglo~er~tlon
process were plscQd in ~n oven and drled ~or 2 hours
~t about llO~C, ~nd then sub~eet~d to the
compres~ive strength test de~crlbed above.
The result~ of these te~ts are summ~rized
In r~ble 1.
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TABLE I
Qu~1ity of Pe11e~s Wlth and Without Binder
tlS P~ t8 er t@st?
Compre~ive
Te~t Binder* Drop Stren~th(R)
No. ~dditlon Moi~ture Number Green Dry
.
1 0 7.5~ 2.00 450 600
2 ~ 8.30 2.00 620 820
3 200 7.51 ~.87 600 830
4 200 7.87 1.80 670 840
200 8.03 2.00 840 950
6 ~00 8.26 2.40 740 910
7 200 8.37 2.13 830 970
8 200 8.52 ~.60 980 1150
9 350 7.95 2.27 830 1460
400 7.73 2.20 ~50 1310
11 400 7.80 1.87 730 1260
12 400 8.20 2.93 1010 1450
13 400 ~.38 3.67 1180 1500
14 4S0 8.13 2.60 810 1q60
~00 7.70 2.13 800 1810
16 600 7.93 2.60 900 1690
17 600 8.13 3.07 900 1540
18 600 8.60 4.33 720 1960
19 6~0 8.79 4.13 980 1930
600 9.05 2.67 7~0 1470
21 1000 8.41 3.53 750 36gO
22 lS00 8.70 7.20 ~30 5190
* Grdm~ of the S0/50 blend of hydroxyethyl
ccllulo~e Qnd ~odlum c~rbon~to per ton of lron ore
~.
~......
.
~3
The ~rocedure de~crib~d abo~ W88 repe~ted
u~nR ~ mixture of b~ntonl~e clay ~nd the binding
composition as the pelletl2in~ ~ent. The resul~
o~ thls ~3t ~re summ~rized in T~ble II.
ABLE II*
QualitY of Pellets Produced
With Bentonite Addition
Compressi~e
Binder ~nd Moi~ture Drop Stren~h~L
Bentonite~ (S) Number Green Dry
(~/t~
Bentonite
1700 8.53 2.07 8~0 1850
Binder
300
.
* 15 pellets te~ted
Gr~m~ o ~entonite ~nd binder per ton of iron ore
The ~ollowing binding compositlons were
prep~red by uniPormly mixln~ the lngredlent~
~percent~ges Qre all ~y welght):
A. S0~ hydroxyethylcellulose (HEC I)
(BolUtion v18c081ty of 6000 centipoise
flS measured on a 1~ aqueous solutlon
on ~ Brookfield V1BCOmeter On ~ NO .
~pindle ~t 30 rpm)
50~ sod~um c~rbon~te
B. 50~ hydroxyethylcellulose (HEC II)
(solutlon viscoslty of 300 centlpoi~e
~g me~sured on ~ 2~ ~queous solutlon
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on a Broo~fleld ~i~comet~r on a N0. 2
~pindle ~t 60 rpm)
50~ sodlum c~rbon~te
C~ 35~ HEC I
65~ ~odium c~rbon~te
D. 25~ HEC I
25S Guær gum
50~ sodium osrbon~te
Finely dividsd taoonlte ore particles
(-8.5~ moi~ture) were mix~d with one o~ the
b~nd~ng eompositlon described ~bove for each tes~.
Concentr~tlon ~f the b1ndins composition for ~11
tests w~s 1.55 pounds per ton of t~conlte ore~
After mixlng, the ore plus bindlng composition w~s
uni~ormly fed into ~ rotating b~lllng tlre for
pelletizlng. W~ter W8~ sdded ~s requlred a~ ~n
~tomized mi~t. The pellet~ thus formed ran8ed in
size ~rom 12-14mm~ The pellet3 were then segmented
into lots of 20 e~ch for testlng.
I. Drop T~t
A. Green pellets
~ me test ~8 da~crlbed in Example I except
th~t the psllet~ were dropped from a hel~h~ of 18
inchcs.
9. Dry Pellet~
Green pellet~ were pl~ced ln ~n oven ~nd
dried for 30 minutes at 350 F ( 176C). The dried pellets
were then sub~ected to the drop teRt described above.
II. Compres~ive Strength
A. Green Pellets
Thls te~t eonsiQted of lo~dlng e~ch pellet
to bre~k~g~ u~1ng a Ch~tillon Spring Te~ter of 25
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lb. r~nge ~t ~ const~nt ~peed of 0.1 ~n./sec. The
number repres~nts the ~ver~ge compressive strength
~n pounds required to br~k the pellet of ~ach lo~.
B. Dry Pellets
Gr~en pellets were pl~ced ln ~n oven and
dried for 30 ~inute~ ~t 35QFt~176C). The dried
pellets ~ere ~hen sub3ected to the compre~sive
strength test described ~bove.
The re~ults of the~e tests are summ~rized
in T~BLE III.
TABLE III
Qu~llty of Pellets
UsinR Dlfferent ~indin~ ComPositions
(Aversge o~ 20 pellet~ per test)
Bindin8 Compresslve
Compo- Moisture Drop Number _StrenRth* _
~ition ~ Green DrY Green DrY
A - 3.65 2.76 3.57 4.54
B 8.7g 3.45 2.55 3.39 4.52
C ~.49 2.61 2.15 3.06 3.23
D 8.07 3.36 3.65 3.16 4.35
* ~veruge compre~sive strength ln pounds
- Not determlned
EXAIIPLE I I I
~ lnding compo~ltlons comprising varlou~
blends o hydroxyethylcellulose (solution vlscosl~y
of 6000 centlpoise ~s me~ured on ~ queous
~olution on 8 Brookfield Vlscometer on s No. 4
splndle st 30 rpm) Rnd ~odlum csrbons~e were
.,
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pr~p~red by unlformly ~ixlng the
hydroxyethylcellulose and sod~um c~rbon~te ~8
~ollows ~perc~nt~ges sre Rll by wei~ht):
E. 50S hydroxye~hylcellulo~e
50S sodium cflrbonate
F. 6Q~ hydroxyethylcellulose
40~ ~odium c~r~on~te
G. 75S hydroxyethylcellulo~e
25~ sodlum c~rbonate
H. lO0~ hydroxyethylcellulo~e
0~ ~odium carbonste
Finely dlvlded t~conlte ore partlcles
(~8.5~ molsture) were mixed wlth one o~ ~he
binding compositions descrlbed above ~or each test.
Concentratlon of the blnding composition in the ore
varled for each composition but the percentage of
hydroxyethylcellulose ln ~he ore remalned the same,
i.e., 0.78 lbs~ per metrle ton o ore. A~ter
mixing, the ore plu~ blnding compo31tion wa~
pelletized ~nd te~ted a8 described in Example II.
The re~ults o~ these te~ts ~re ~umm~rlzed
in T~ble XV.
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T~BLE_IV
Qu~lltY of P~ t~ Usin8_Different
Bl~nds of Hydroxyeth~lcellulo~ and
Sodlum C~rbon~te as Blnders*
LBSI - ColDpre~give
BindingMetric DroP Number Str~n8~h(LBS)Moisture
ComPosltion Ton W~t DrY Wet Dry_
E 1.55 3.2 2.9 3.5 4.8 8.3
F 1.30 3.1 ~.1 3.3 3.5 8.6
G 1.04 3.7 2.0 3.1 2.9 8.7
H 0.78 3.6 2.0 3.5 3.1 8.3
*Average o~ 20 pellets per te~t
The proce~s of this invention 1~ pre~ersbly
employed for iron-containing ores and ore concentrates~
~uch ~s magnetlte and hematlte concentra~es, natural ore~
~nd pyrite resldue& but the process is al~o suitsble for
use with non-ferrous ore mQterlsls.
Although the method of thls lnvention h~s
been described generslly ~or prepar~tion o pelle~s of
minersl ore, lt will be under~tood by those skllled ln
the art that ~his method 18 equally uppllcable for the
prepuration of other ~gglomerated form~, such as
briquettes ~nd ~inters.
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