Note: Descriptions are shown in the official language in which they were submitted.
`~
~13~2 D1~
A PROCESS FOR AGGLOMERATING MINERAL ORE CONCENTRATE
UTILIZING EMULSIONS OF POLYMER BI~DERS OR DRY
POLYME~ BINDERS
BACKGROUND OF THE INVENTION
l. Fleld Or the Inventlon
Thls lnventlon relates generally to methods ror
agglomeratlng or pelletlzlng mlneral ore concentrate.
More speclflcally, thls lnventlon relates to methods for
agglomeratlng or pelletlzlng mlneral ore concentrate
uslng water soluble, hlgh molecular welght polymer
blnder system~ ln elther water-ln-oll emulslons or a~ a
dry powder.
2. De~crlptlon Or the Prlor Art
It is customary ln the mlnlng lndustry to
agglomerate or pelletlze flnely ground mlneral ore
concentrate 80 a8 to further facllltate the handling and
shlpping Or the ore. Mlneral ore concentrates can
lnclude lron oxldes, copper oxldes, barytes, lead and
l~ zlnc sulfldes, and nlckel sulrldes. Agglomerates of
coal dust and nonmetallc mlnerals used to make brlcks or
ceramlcs are also rormed. Agglomerate rorms can lnclude
pellets, brlquettes, and slnters.
Methods of pelletlzlng mlneral ore concentrate are
~requently used ln mlnlng operatlons w~ere the ore 18 a
low grade lron ore. Examples Or low grade lron ores are
~,f
~ I *
-
9 1 3 .~
- D-14,834
- 2
taconlte, hematlte, and magnetlte. Numerous other low
grade ores exlst wherein pelletlzing Or the ground
partlcles ls benerlclal to the handllng and shlpment Or
the mlneral ore. Arter the mlneral ore has been mlned,
lt 18 rrequently ground and screened to remove large
partlcles whlch are recycled ror rurther grindlng.
Typlcally, an ore 18 psssed through a lO0 mesh (0.149mm)
screen. The screened mlneral ore 18 known as a
"concentrate".
For example, taconlte mlneral ore concentrate arter
grlndlng and screenlng has an sverage molsture content
Or between sbout 6 to about lO percent. The moisture
content Or the mlneral ore concentrate can be
selectlvely altered. The molsture content arfect~ the
strength Or the pellets that are rormed later ln the
process .
Arter screenlng, the mlneral ore concentrate 18
transported on a rlrst conveyor means to a balllng drum
or another means ~or pelletlzlng mlneral ore
concentrate. Prlor to enterlng the balllng drum, a
blndlng agent 18 applled or mlxed lnto the mlneral ore
concentrate. Commlngling the blndlng agent wlth the
mineral ore concentrate occurs both on the con~eyor
mean~ and ln the means for pelletlzlng. The blndlng
agents hold the mlneral ore concentrate together as
~1332~1~
- D-14,834
pellets untll arter rlrlng.
Balllng drums are apparatu~es comprlslng long
cyllndrlcal drums whlch are lncllned and rotated. The
mlneral ore concentrate 18 slmultaneously rotated about
the balllng drum's clrcumference and rolled ln a
downward dlrectlon through the drum. In thls manner the
mlneral ore concentrate 18 rolled and tumbled together
to rorm roughly spherlcal-shaped pellets. As the
pellets grow ln slze and welght they travel down the
lncllne Or the drum and pass through the ex~t Or the
drum at whlch polnt they are dropped onto a second
conveyor means whlch transports them to a klln ror
rlrlng. Inslde the balllng drum, dlrrerent ractors
lnrluence the mechanlsms Or unlon Or the mlneral ore
concentrate. These ractors lnclude the molsture content
Or the ore, the shape and average slze Or the mlneral
ore pa-tlcle~, and the dlstrlbutlon Or concentrate
partlcles by slze. Other propertles Or the mlneral ore
concentrate that lnfluence the pelletlzlng operatlon
lnclude the mlneral ore's ~ettablllty and chemlcal
characterlstlcs. The characterl~tlcs Or the equlpment
used, such as lts si~e and speed Or rotatlon, can erfect
the er~lclency Or the pelletlzlng operatlon. The nature
and guantlty Or the agglo~eratlng or blndlng agent used
ln the concentrate 1~ also a ractor that determlnes part
~ ~;
Q 1~ 3 ~ D 14, 834
Or the errlclency Or the pelletlzlng operatlon.
The rormatlon Or agglomerates beglns wlth the
lnterfaclal rorces whlch have a coheslve erfect between
partlcles Or mlneral ore concentrate. These lnclude
S caplllary rorces developed ln llquld rldges between
the partlcle surraces. Numerous partlcles adhere to one
another and rorm small pellets. The contlnued rolllng o'
the small pellets wlthln the balllng drum causes more
partlcles to come lnto contact wlth one another and
adhere to each other by the caplllary tenslon and
compresslve stress. These rorces cause the unlon of
partlcles ln small pellets to grow ln much the same
manner as a snowball grows as lt 18 rolled.
Arter the balling drum operatlon, the pellets are
formed, but they are stlll wet. These pellets are
commonly known as "green pellets" though taconlte
pellets, ror example, are usually black ln color. Green
pellets usually have a denslty Or about 130 lb/ft3 ln
slzes between about l/2 lnch and about 3/8 Or an lnch.
The green pellets are transported to a klln and heated
in stages to an end temperature Or approxlmately 2800F.
Arter heatlng, rlred pellets are extremely hard and
reslst cracklng upon belng dropped and resist crushlng
when compressed.
Two standard tests are used to measure the strength
~,.
~ ~L 3 r~
~- ~ D-14,834
Or pellets whether the pellets are green pellets or
flred pellets. These tests are the "drop" test and the
"compresslon" test. The drop test requlres dropplng a
random sampllng Or pellets a dlstance, usually sbout 18
lnches or less, a number o~ tlmes untll the pellets
crack. The number o~ drops to crack each pellet 18
recorded and averaged. Compre~slon strength ls measured
by compresslng or applylng pressure to a random sampllng
Or pellets untll the pellets crumble. The pounds OI
rorce requlred to crush the pellets 18 recorded and
averaged. These two tests are used to measure the
strength Or both wet and ~lred pellets. The drop and
compresslve test measurements are lmportant because
pellets, proceedlng through the balllng drum and
subsequent conveyor belts, experlence rrequent drops as
well as compresslve rorces rrom the welght Or other
pellets travellng on top Or them.
Thermal shock reslstance 18 a factor whlch must be
taken lnto conslderatlon ln any process ror
agglomeratlng mlneral ore concentrate. Increases ln a
pellet's thermal shock resl~tance lmprove that pellet's
ablllty to reslst lnternal pressures created by the
sudden evaporatlon Or water when the pellet 18 heated ln
a klln. If the pellet has numerous pores through whlch
the water vapor can escape thermal shock reslstance 18
., .
01~ 3 ~
D-14,834
lmproved. Ir the sur~ace Or the pellet is smooth and
contlnuous wlthout pores the pellet has an lncreased
tendency to shatter upon rapld heatlng. Thls causes a
concurrent lncrease ln the amount Or "flnes" or coarse
partlcles in the pelletlzed mlneral ore. A blnder whlch
lncreases the pores rormed ln a pellet lmproves that
pellet's ablllty to reslst thermal shock.
Bentonlte ls used as a blndlng agent ln the
pelletlzlng operatlons ror taconite ore concentrate.
Bentonlte produces a hlgh strenBth pellet havlng an
acceptable drop strength, compresslve strength, and
thermal shock re~lstance. Bentonlte has the
dlsadvantage Or lncreaslng the slllca content Or the
pellets that are ~ormed. Slllca decreases the
ef~lclency Or blast rurnace operatlons used ln smeltlng
Or the ore. For thls reason bentonlte requlres a hlgher
energy expendlture than do organlc blnders.
Other blndlng agents have proven to be better
blnders than bentonlte. These agents lnclude organlc
binders such as poly(acrylamlde), polymethacrylamlde,
carboxymethylcellulose, hydroxyethylcellulose,
carboxyhydroxyethylcellulose, poly(ethylene oxlde), guar
gum, and others. The use Or organlc blnders ln mlneral
ore pelletlzlng operatlons 18 deslrable over the use Or
bentonlte because organlc blnders do not lncrease the
~ :v
K ~
~1332~1~
D-14,834
slllca content of pellets and they lmprove the thermal
shock reslstance Or the pellets. Organlc blnders burn
durlng pellet rlrlng operatlons and cause an lncrease ln
the poroslty Or the pellets. Flrlng condltlons can be
, modlrled to improve rlred pellets' mechanlcal propertle~
ror organlc blnder systems.
Some organlc blnders used ln mlneral ore
pelletlzlng operation~ are dlssolved ln an aqueous
solutlon whlch 18 sprayed onto the mlneral ore
concentrate prlor to enterlng the balllng drums. Thls
appllcatlon Or an aqueous ~olutlon lncreases the
molsture content above the natural or lnherent molsture
content Or the mlneral ore concentrate whlch requlres a
Breater energy expendlture durlng the rlrlng operatlon
Or the pellets. Thls lncreased molsture content also
causes an lncreased llkellhood Or shatterlng due to
- lnadequate thermal shock resl~tance durlng rlrlng.
Pellet rormatlon 18 lmproYed wlth the use Or organlc
blnders, but the drop strength and compresslon strength
Or the pellet are rrequently below that deslred or
achleved wlth bentonlte.
Other blnder~ commonly used ror agglomeratlng
mlneral ore concentrate lnclude a mlxture Or bentonlte,
clay and a soap, Portland cement, sodium slllcate, and a
mlxture Or an alkall salt Or carboxymethylcellulose and
2 .~ 1 ~
D-14,834
an alkall metal salt. The agglomerates made rrom these
blndlng agents rrequently encounter the problems
descrlbed above Or lnsurrlclent pellet strength or
lnsurrlclent poroslty ror the rapld release Or steam
S durlng lnduratlon wlth heat. Addltlonally, these
~- blndlng agents are usually applled to a mlneral ore
concentrate ln aqueous carrler solutlons o- as dry
powders. Aqueous carrler solutlons lncrease the amount
Or energy requlred to rlre the pellets and lncrease the
lncldence Or pellet shatterlng due to lnadequate thermal
~hock reslstance.
U.S. Patent Number 3,893,847 to Derrlck dlscloses a
blnder and method ror agglomeratlng mlneral ore
concentrate. The blnder used ls a hlgh molecular
welght, substantlally stralght chaln water soluble
polymer. Thls polymer ls used ln an aqueous solutlon.
The polymers dlsclosed 8S userul wlth the Derrlck
lnventlon lnclude copolymers Or acrylamlde as well as
other polymers. The Derrlck lnventlon clalms the use Or
polymers ln an "aqueous" solutlon. The use Or water as
a carrler solutlon ror the blndlng agents lncreases the
molsture Or the agglomerates or pellets that are rormed.
The hlgher molsture content lncreases the energy
requlred to rlre the pellets and can lncrease the rate
Or destructlon Or the pellets durlng lnduratlon due to
:
~ ~ 3 ~ 2 ~ 1 1
D-14,834
the rapld release of steam through the agglomerate.
The lndustry ls lacklng a method ror sgglomeratlng
mlneral ore concentrate utlllzlng low water content
non-bentonlte blnder systems, such aQ water soluble,
hlgh molecular welght polymer blnder systems ln
water-ln-oll emulslons or dry powders. Thls lnventlon
provldes pellets formed from the mlneral ore concentrate
of hlgh mechanlcal strength propertles.
SUMMARY OF THE INVENTION
Thls lnventlon is a method for agglomeratlng a
particulate materlal such as a mineral ore concentrate
comprlslng the commlngllng Or mlneral ore concentrate
with 8 blndlng amount Or water soluble, hlgh molecular
welght polymers. The polymers are adapted to be
selectlvely usable in at least one o~ either Or two
condltlons Or use. In a rirst condltion Or use the
polymers are applled to the mlneral ore concentrate as a
dry powder. In a second condltlon of use the polymers
are applied to the mineral ore concentrate in a
water-in-oil emulsion.
This inventlon also includes a method comprising
the commlngllng Or dry poly(acrylamlde) ba8ed polymer
onto mlneral ore concentrate whereln the lnherent or
added moisture content Or the mlneral ore concentrate is
., .
2 ~J l ~
D-14,834
su~lclent to actlvate the poly(~crylamlde) based
polymer to ~orm pellets of the mlneral ore.
Thls lnventlon 18 partlcularly deslrable when used
wlth an lron ore concentrate and can al~o lnclude the
appllcatlon Or an lnorganlc salt ~uch as sodium
carbonate, calclum carbonate, sodlum chlorlde, sodlum
metaphosphate and mlxtures Or the~e ln conJunctlon wlth
the polymer. The lnorganlc salt can be applled as a
powder or an aqueous solutlon.
DETAILED DESCRIPTION OF THE INVENTION
Thls lnventlon 18 a method ror agglomeratlng
partlculate materlal such as a mlneral ore concentrate
uslng water soluble, hlgh molecular welght polymer~ in
an amount surrlclent to blnd the mlneral ore
concentrate. The polymers are applled to the
partlculate materlal ln at least one Or elther a
water-ln-oll emulslon sy~tem or a dry powder sy~tem.
The appllcatlon Or the polymers to a mlneral ore
concentrate can be ln conJunctlon wlth an lnorganlc
salt or mlxtures Or lnorganlc salts applled as powders
or ln aqueous solutlons. The polymers and lnorganlc
salt8 are commlngled wlth the mlneral ore concentrate.
Thls composltlon then enters a 8tandard means ror
pelletlzlng or a balllng drum. The means ~or
f
, .
Q 1~ 3 2 ~ 1 D-14, 834
pelletizlng further commlngles the lngredlents and rorms
wet or "green" pellets. The pellets are then
trans~erred or conveyed to a furnace or klln where they
are lndurated by heat at temperatures above about 1800F
and more prererably at about 2800F. A~ter lnduratlon,
the pellets are ready ~or shlpplng or ~urther processlng
ln a smeltlng operatlon such as a blast furnace.
Sultable polymers use~ul ln thls lnventlon lnclude
water soluble homopolymers, copolymers, terpolymers, and
tetrapolymers. In a water-ln-oll emulslon system the
selected polymer ls produced by polymerizlng its
monomerlc water-~ln-oll emulslon precurqor. Sultable
polymers can be anlonlc, catlonlc, amphoterlc, or
nonlonlc. It ls deslrable ln thls lnventlon to use
polymers o~ hlgh molecular welght as characterlzed by a
hlgh lntrlnslc vlscoslty. Thls lnventlon 18 not llmlted
to polymers Or hlgh lntrlnslc vlsco~lty.
Polymers sultable for use wlth thls lnventlon,
whether used ln water-ln-oll emul~lon systems or ln dry
powder systems, are partlcularly deslrable when they are
Or a hlgh molecular welght. The partlcular molecular
welght Or a polymer 18 not llmltlng upon thls lnventlon.
Sultable polymers lnclude synthetlc vlnyl polymers and
other polymers as dlstlngulshed rrom derlvatlves Or
natural celluloslc product~ auch as
"~
~ 1 3 3 2 .~ 1 ~
D-14,834
12
carboxymethylcellulose, hydroxyethylcellulose, and other
cellulose derlvatives.
Useful measurements of a polymer' 8 average
molecular weight are determlned by either the polymer's
lntrlnslc vlscoslty or reduced vlscoslty. In general,
polymers of hlgh lntrinslc vlscoslty or hlgh reduced
vlscoslty have a hlgh molecular welght. An lntrinsic
viscoslty ls a more accurate determlnatlon of a
polymer's average molecular welght than ls a reduced
vlscoslty measurement. A polymer's ablllty to form
pellets of mlneral ore concentrate ls lncreased as the
polymer's intrlnslc vlscoslty or reduced vlscoslty ls
lncreased. The most deslrable polymers used ln the
process of thls invention have an lntrlnslc vlscoslty of
from about 0.5 t~ about 40, preferably from about 2 to
about 35 and most preferably from about 4 to about 30
dl/g as measured ln a one normal (N) aqueous sodlum
chloride solutlon at 25C.
- Water soluble polymers lnclude, among others,
20 ` poly(acrylamlde) based polymers and those polymers whlch
polymerlze upon addltlon of vlnyl or-acryllc monomers in
solutlon wlth a free radlcal. Typlcally, such polymers
~1~?92~1~
D-14,834
13
have lonlc functlonal groups such as carboxyl,
sulfamlde, or quaternary ammonlum groups. Sultable
polymers can be derlved from ethylenlcally unsaturated
monomers lncluding acrylamide, acryllc acld, and
methylacrylamide. Alkall metal or ammonlum salts of
these polymers can also be useful.
Deslrable polymers for use ln this lnvention are
preferably of the following general formula:
` R2
~ 1 ? ~ 2 S l ~
D-14,834
14
whereln R, Rl and R3 are lndependently hydrogen or
methyl, R2+ 18 an alkall metal lon, ~uch as Na+ or K+,
R4 1~ elther
(l) -OR5 whereln R5 i~ an alkyl group havlng up to
5 carbon atoms;
(2)
i~-- O--R 6
whereln R6 18 an alkyl group havlng up to 8
carbon atoms;
o (3) o
Il
- O C R
whereln R7 1~ elther methyl or ethyl;
(4) phenyl;
(5) substltuted phenyl;
lS (6) -CN; or
r
01.~32 ~l`;i
D-14,834
(7)
; and
whereln (a) is from 0 to about 90, preferably from about
30 to about 60 percent, (b) 18 from 0 to about 90,
preferably from about 30 to about 60 percent, (c) ls
from about 0 to about 20 with the provlso that
(a)+(b)+(c) equal 100 percent, and (d) ls an integer of
from about 1,000 to about 500,000.
~1332~
D-14, 834
16
Under certaln condltlons, the al~oxy or acyloxy
groups ln the polymer can be partlally hydrolyzed to the
correspondlng alcohol group and yleld a tetrapolymer of
the followlng general formula:
r CH2~ c H2--c--~H2--c
l , ICHO 1-- l R 4 OH
_ a ~ R2+~ b d
~l~32~
D-14,834
17
wherein R, Rl, R2+, R3, a, b, and d are as prevlously
deflned, R4 ls -OR5 or O
-O- -R7 whereln R5 and R7
as deflned prevlously, c is from about 0.2 to about 20
percent, and e is from about 0.1 to less than about 20
percent.
The preferred copolymers are of the following
formula:
~CH2 C; I~H2 C
l J~
d
D-14,834
18
whereln R2+ ls an alkall metal ion, such as Na+ or K+,
and r 1~ rrom 5 to about 90, preferably from about 30 to
about 60 percent, g ls rrom 5 to about 90, prererably
rrom about 30 to about 60 percent wlth the provlso that
S (f)+(g) equal lO0 percent, and (d) ls an lnteger Or rrom
about l,000 to about 500,000.
The prererred terpolymers are Or the rollowlng
rormula:
~CH2 C ~ ~H2 C--. . CH2 C--_
7-o ~c=o 1
L NH2 i ~ ~2 ~ ~ l ~ h
.,
~ ~ 3
D-14,834
whereln R2l 18 Na~ or K+, R7 18 methyl, ethyl, or butyl
and f ls rrom about 5 to about 90, prererably rrom about
30 to about 60 percent, g 18 rrom about 5 to 90,
prererably rrom about 30 to 60 percent, h ls rrom about
0.2 to about 20, wlth the provlso that (r)+(g)~(h) equal
100 percent and d 18 as prevlously deflned.
The preferred tetrapolymers are of the rollowlng
rormula:
;~CH2--C ~ ~C~'2--C ~ ' ~CH2 C--~CH2--C
~ 2Jf¦ ~ l ~ h~e OH e
ln Rl, R2+, R3~ R7~ f, g, ~, d, and e are a8
prevlously deflned.
.7 ~
~ ~13~514 D-14,834
Other deslrable water soluble polymers ror use wlth
thls lnventlon lnclude those derlved from
homopolymerlzatlon and lnterpolymerlzatlon of one or
more Or the rollowlng water soluble monomers: acryllc
and methacryllc acld; acryllc and methacryllc acld salts
Or the rormula
R8 O
CH2 C . C - O - Rg
whereln R8 ls a hydrogen atom or a methyl group and Rg
ls a hydrogen atom, an alkall metal atom (e.g., sodlum,
potasslum), an ammonlum group, an organoammonlum group
(Rlo)(Rll)(R12) NH+ (where Rlo, Rl and
R12 are lndependently selected from a hydrogen atom, and
an alkyl group havlng rrom l~to 18 carbon atoms (lt may
be necessary to control the number and length Or
long-chaln alkyl groups to a~sure that the monomer ls
water soluble), such as 1 to 3 carbon atoms, an aryl
group, such as a benzyl group, or a hydroxyalkyl group
havlng rrom 1 to 3 carbon atoms, such as
trlethanolamlne, or mlxtures thereof ; acrylamide and
met~acrylamlde and derlvatlves lncludlng acrylamldo- and
methacrylamldo monomers Or the formula:
~,
r O 1 3 3 2 ~ 1 4 D-14,834
~ 21
s~ -
IR13 0 N/ R14
CH2 . C - \Rl~
whereln R13 1~ a hydrogen atom or a methyl group;
whereln R14 1~ a hydrogen atom, a methyl group or an
ethyl group; whereln R15 ls a hydrogen atom, a methyl
group, an ethyl group or -R16-S03X, whereln R16 ls a
dlvalent hydrocarbon group alkylene, phenylene, or
cycloalkylene havlng from 1 to 13 carbon atoms,
preferably an alkylene group havlng from 2 to 8 carbon
atoms, a cycloalkylene group havlng from 6 to 8 carbon
atoms, or phenylene, most preferably
-C(CH3)2-CH2---CH2CH2 ' ~
-CH(CH3)-CH2-, ~ and
~ CH3
CH3
X ls a monovalent catlon such as a hydrogen atom, an
alkall metal atom (e.g., sodlum or potasslum), an
ammonlum group, an organoammonlum group of the formula
(R17) (R18) (R19) NH+ whereln R17, R18, Rlg are
lndependently selected from a hydrogen atom, an alkyl
` 01332511
D-14,834
~ 22
group havlng from 1 to 18 carbon atoms (lt may be
necessary to control the number and length Or long-chain
alkyl groups to assure that the monomer 18 water
soluble) such as 1 to 3 carbon atoms, an a.yl group such
as a phenyl or benzyl group, or a hydroxyalkyl group
havlng rrom 1 to 3 carbon atoms ~uch as trlethanolamlne,
or mlxtures thereor, and the llke. Speclrlc examples Or
water-soluble monomers whlch can be homopolymerlzed or
lnterpolymerlzed and userul ln the process of thls
lnventlon are acrylamldo- and methacrylamldo- sul~onlc
aclds snd sulronates such as 2-acrylamldo-2-
methylpropanesulronlc acld (avallable rrom the Lubrlzol
Corporatlon under lts tradename, and herelnafter
rererred to as, AMPS), sodlum AMPS, ammonlum AMPS,
organoammonlum AMPS. These polymers can be efrectlve
blndlng agents rOr mlneral ore concentrates ln about the
same concentratlons or blndlng amounts used for ot~er
polyacrylamlde based polymer blnders.
These water soluble monomers can be
lnterpolymerlzed wlth a mlnor amount (l.e., less than
about 20 mole percent, prererably less than about 10
mole percent, based on the total monomer~ red to the
reactlon) Or one or more hydrophoblc vlnyl monomers.
For example, vlnyl monomers Or the rormula
01332514
D-14,834
23
R20
CH2 C - R2 1
whereln R20 1s a hydrogen atom or a methyl group
and R21 is - 0 - C - R22, a halogen atom (e.g.,
chlorlne), -0-R23~ ~ R24 or _11_OR25- whereln
R25 ls an alkyl group, an sryl group or an aralkyl group
havlng from l to 18 carbon atoms, whereln R22 18 an
alkyl group havlng from 1 to 8 carbon ato~s, R23 is an
alkyl group havlng from 1 to 6 carbon atoms, preferab-ly
2-4 carbon atoms, R24 ls a hydrogen atom, a methyl
group, an ethyl group, or a halogen atom (e.g.,
chlorlne), preferably a hydrogen atom or a methyl group,
wlth the provlso that R20 ls preferably a hydrogen atom
when R22 ls an alkyl group. Speclflc examples of
sultable copolymerizable hydrophoblc vlnyl monomers are
alkyl esters of acryllc and methacryllc aclds such as
methyl acrylate, methyl methacrylate, ethyl acrylate,
ethyl methacrylate, butyl acrylate, lsobutyl acrylate,
dodecyl acrylate, 2-ethylhexyl acrylate, etc.; vlnyl
esters such as vlnyl acetate, vlnyl proplonate, vlnyl
butyrate, etc.; vlnylbenzenes such as styrene,
alpha-methyl styrene, vlnyl toluene; vlnyl ethers ~uch
01332~1~
D-14,834
24
as propyl vinyl ether, butyl vinyl ether, isobutyl vinyl
ether, methyl vinyl ether, ethyl vinyl ether, etc.;
vinyl halides such as vinyl chloride, vinylidene
chloride, etc.; and the like.
The preferred water soluble monomers of these water
soluble polymers are acrylamide, AMPS and sodlum AMPS,
sodium acrylate,~ and ammonium acrylate. The preferred
-hydrophobic monomers are vinyl acetate, ethyl acrylate,
styrene and methyl methacrylate.
0133251~
D-14,834
Examples of sultable polymers for use wlth thls
lnvention ln water-ln-oll emulslons are llsted in Table
I. This table provldes a representatlve llsting of
sultable polymers for use ln the water-ln-oil emulslons,
but does not encompass every suitable polymer or limit
the polymers that can be used with this lnvention.
01332514
26 D-14,834
TABLE I
Poly(acrylamlde) Emulslonsl
Mole S Intrlnslc S
Anionlc Copolymers PAM/Na Acrylate Vl~coslty Sollds
85/15 16.2 30
76/24 17.3 30
59/41 20.0 30
Catlonlc Copolymers PAM/Slpomer Q5_802
94/16
PAM/N-decyl
Nonlonic Copolymers Acrylamide
99/1 5.8
PAM/NaA/Vinyl
Anlonlc Terpolymers Acetate
47.5/47.6/4.9 10.8 30
23.0 29.5
71/24/5 2030 3
80/15/5 RV ~17.5 30
PAM/NaAMPS/Vinyl
Acetate
87/12/1 10.0
1 abbre~latlons: PAM: poly(acrylamlde); NaA: sodlum
acrylate; NaAMPS: sodlum salt Or 2-acrylamido-2-methyl-
propane~ulfonlc acld.
2 Slpomer Q5-80 18 a catlonlc compound Or
dlmethylamlnoethylmethacrylate/dlmethyl sulrate
quaternary salt.
3 Reduced ~lscoslty.
01332~1~
D-14,834
27
A second class of polymers lnclude~ those polymers
used wlth this inventlon in dry powder form. These
polymers must be water soluble, but do not necessarlly
lend themselves to the formatlon of water-ln-oll
emulslons. Typlcally, polymers whlch form water-ln-oll
emulslons are also useful wlth the invented method as
dry powder. Table II represents a listing of polymers
which are desirable for use with this lnvention as
powders. The powders listed in Table II do not
encompass all polymers which can be used as powders in
this invention.
01332~14
D-14,834
28
TABLE II
Poly(acrylamide) Powders
Nonlonlc Rhone Poulenc AD-lOl
(intrinsic vl~cosity 15.4dl/g)
Approximate
mole %
Anionic . PAM/NaA
Percol 7252 89/11
Percol 726 - 77/23
1 AD-10 is a poly(acrylamide) powder sold by Rhone
Poulenc, 52 Vanderbllt Avenue, New York, NY.
2 Percol products have been analyzed to be copolymers
contalnlng the approximate mole % of PAM and NaA glven
in Table II and are sold by Allied Colloids of
Fairfleld, New Jersey.
\
013~2514 D-14,834
29
Inorganic salts are optionally added to the
mineral ore concentrate before balling operations
primarily to increase the strength of wet pellets
(green drop strength) or dry pellets (dry crush
strength). Inorganic salts can be added either
before, after, or during the addition of the dry or .
emulsified polymer. Polymers alone improve the dry
compression strength of pellets, but not to the same
degree as an inorganic salt. For this reason,
desirable embodiments of this invention include the
addition of an inorganic salt, however, this
addition is not considered limiting upon this
invention. Similarly, neither the inorganic salt
selected nor the method of addition is not limiting
upon this invention. For purposes of this invention
the term "polymer binder system" can include a water
soluble, high molecular weight polymer in a
water-in-oil emulsion system, powder system or as
hereinafter supplementally described regardless of
whether the system includes, or is used with or
without inorganic salt powders or solutions.
Inorganic salts suitable for use in this
invention include alkali and alkali metal salts of
carbonates, halides, or phosphates. Specific
examples of inorganic salts include sodium carbonate
(NaCO3), calcium carbonate (CaCO3, i.e.,
limestone), sodium metaphosphate (NaPO3)n where
n is 2 or more, sodium chloride (NaCl), or as
hereinafter supplementally disclosed, and mixtures
of these. Other inorganic salts can be added to
improve pellet compression strength. Additionally,
inorganic
~'
.
01332514
D-14,834
3o
salts can be added ln mlxtures wlth one another as
powders or ln solutlons. As the concentratlon o~
lnorganlc salt increases ln the mlneral ore concentrate,
the compression strength of the resultlng pellets ls
lncreased.
Sodlum carbonate 18 an lnorganlc salt that achleves
good results ~or lmprovlng the compre~sion strength of
pellets. Sodlum carbonate 18 most errectlve, when used
wlth elther the dry or emulslfled polymer, ln an amount
o~ at least 2 percent and preferably greater than 25
percent, calculated on the total welght Or the added
lnorganlc salt and actlve polymer. Preferably the
concentratlon Or sodlum carbonate as a percent Or the
welght Or the polymer binder system varles from about 25
percent to about 95 percent. More prererably, sodlum
carbonate 18 wlthln the range o~ about 30 percent to
about 90 percent wlth the most optlmum range between
about 50 percent to about 90 percent calculated on the
total welght Or the mlxture of sodlum carbonate and the
polymer.
The lnvertlble water-ln-oll emulslon system used ln
thls lnventlon 18 a suspenslon Or droplets comprl6ed of
both water soluble, hlgh molecular welght polymers and
water ~n a hydrophoblc sub~tance. Examples Or sultable
emulslon systems and methods to rorm sultsble cmulslons
O 1 3 3 2 ~ 1 4
D-14,834
31
are found ln U.S. Patent Number 4,485,209 to Fan et al.
and U.S. Patent Number 4,452,940 to Rosen et al. each of
whlch are bereln lncorporated by rererence.
Desirable hydrophoblc llqulds used ln these
emulslon ~ystems are lsopararrln$c hydrocarbons. A
sultable lsopararrlnlc hydrocarbon ls that sold by the
Exxon Corporatlon known as Isopar M. Other sultable
hydrophoblc llqulds ror use as the external phase ln an
emulsion system lnclude benzene, xylene, toluene,
mlneral 0118, kerosenes, petroleum, pararrlnlc
hydrocarbons, and mlxtures Or these.
In the mo~t deslrable embodlments Or thls
lnventlon, whlch lnclude a polymer bindlng aBent ln a
water-ln-oll emulslon, two surractants are used to rorm
the emulslon. A rlr~t sur~actant 18 used to form the
water-ln-oll emulslon system. Arter the water-ln-oll
emulslon system 18 rormed, a second surractant ls added.
The second surractant 18 a water soluble invertlng
surractant whlch, we belleve, permlts the lnver~lon Or
the water-ln-oll emulslon to an oll-ln-water emulslon
upon contact wlth the lnherent or added molsture present
ln the mlneral ore concentrate. Upon lnverslon Or the
water-ln-oll emulslon the polymer 18 rorced out Or the
lnternal aqueous phase and made a~allable to the surrace
Or the mlneral ore concentrate. Thls release Or the
0133251~
D-14,834
32
polymer onto the sur~ace Or the mlneral ore concentrate
allows ~or rapld commlngllng o~ the polymer wlth the
mlneral ore concentrate. Emulslons that do not contaln
lnvertlng surfactants can be used wlth thls lnventlon.
The surractants sultable ror use ln rormlng
emulslons Or thls inventlon are usually oll-soluble
havlng a Hydrophlle-Llpophlle Balance (HLB) value o~
~rom about 1 to about 10 and preferably rrom about 2 to
about 6. These surractants are normally rererred to as
water-ln-oll type surractants. Sultable surractants
lnclude the acld esters such as sorbltan monolaurate,
sorbltan mono~tearate, sorbltan monooleate, sorbltan
trloleate, mono and dlglycerldes, such as mono and
dlglycerldes obtalned rrom the glycerolysls Or edlble
rats, polyoxyethylenated ratty acld esters, such as
polyoxyethylenated (4) sorbltan monosterate,
polyoxyethylenated llnear alcohol, such a8 Tergltol
15-S-3 and Tergitol-25-L-3 supplled by the Unlon Carblde
Corporatlon, polyoxyethylene sorbltol esters, such a~
polyoxyethylene sorbltal beeswax derlvatlve,
polyoxyethylenated alcohols such a~ polyoxyethylenated
(2) cetgl ether, and the llke.
Water-~oluble lnvertlng surractants ~hich csn be
used lnclude polyoxyethylene alkyl phenol,
2~ polyoxyethylene (10 mole) cetyl ether, polyoxyethylene
~ , .
01332511
D-14,834
33
alkyl-aryl ether, quaternary ammonlum derivatlves,
potasslum oleate, N-cetyl N-ethyl morphollnlum
ethosulfate, sodlum lauryl sulfate, condensatlon
products of hlgher fatty alcohols wlth ethylene oxide,
such as the reactlon product of oleyl alcohol wlth lO
ethylene oxlde unlts; condensatlon products of
alkylphenols and ethylene oxlde, such as the reactlon
products of isooctylphenol wlth 12 ethylene oxlde unlts;
condensatlon products of hlgher fatty acld amlnes wlth
five, or more, ethylene oxlde unlts; ethylene oxide
condensatlon products of polyhydrlc alcohol partial
hlgher fatty esters, and thelr lnner anhydrldes
(mannltol-anhydrlde, called Mannltan, and
sorbltol-anhydrlde, called Sorbltan). The preferred
surfactants are ethoxylated nonyl phenols, ethoxylated
nonyl phenol formaldehyde reslns, and the llke.
The lnvertlng surfactant ls used ln amounts of from
about 0.1 to about 20, preferably from about l to about
lO parts per one hundred parts of the polymer.
The mlxture of both the aqueous phase and the oll
phase of the emulslons used ln thls lnvention can
contain about 20 to about 50 and preferably from about
22 to about 42 percent welght of the hydrophoblc llquid
and the hydrophoblc monomers, based upon the total
welght of the compositlon.
0133251~
D-14,834
The aqueous solution used to form the emulsion
systems of this invention can contaln a mlxture of water
soluble monomers. These monomers have a water
solubility of at least 5 welght percent and lnclude
acrylamlde, methacrylamlde, acryllc acid, methacrylic
acid, and their alkall metal salts, aminoalkyl acrylate,
aminoalkyl methacrylate, dialkylaminoalkyl acrylate,
dialkylamino methacrylate and their quaternized salts
with dimethyl sulfate or methyl chloride, vlnyl benzyl
dimethyl ammonlum chlorlde, alkali metal and ammonium
salts of 2-sulfoethylacrylate, alkali metal and ammonium
salts of vinyl benzyl sulfonates, maleic anhydride,
2-acrylamide-2-methylpropanesulfonic acld, and the llke.
The preferred monomers are acrylamide, acrylic acld, and
sodlum salt of 2-acrylamido-2-methylpropanesulfonlc
acld.
If acryllc acld i8 used as a monomer lt ls reacted
with a base, preferably w1th an equivalent amount of
base, such as sodlum hydrox-ide, so that the sodlum
acrylate solution has a pH of from about 5.0 to about
10.0, preferably from about 6.5 to about 8.5, dependlng
on the type and amount of base employed. Thls solutlon
ls comblned wlth another water soluble monomer, such as
acrylamlde, and then wlth water to form the aqueous
phase.
01332S14
D-14,834
Hydrophoblc monomers which can be userul in formlng
the emulslon sy~tems of thls lnventlon lnclude one or
more Or vlnyl ester~ such a8 vlnyl acetate, alkyl
acrylates such as ethylacrylate, alkyl methacrylates
such as methacrylate, vlnyl ethers such a~ butylvlnyl
ether, acrylonltrlle, styrene and lts derlvatlves such
as alpha-methylstryrene, N-vlnyl carbazole, and the
llke.
Approprlate reactor~ and cataly~ts are also used
wlth thls lnventlon. These compounds can vary.
Examples Or sultable reactors and catalysts can be round
ln the Fan and Ro~en patents ldentl~led above.
Emulslons used ln thls lnventlon are made by any
sultable method. A deslrable method ror maklng
emulslons ls dlsclosed ln U.S. Patent Number 4,485,209
to Fan. Thls lnventlon 18 not llmlted to a partlcular
emulslon or method ror produclng an emulslon.
An advantage to the use Or water-ln-oll emulslons
ln the rormatlon Or pellets 18 that the amount of water
added to the mlneral ore concentrate 18 greatly reduced
rrom that requlred to dellver polymers ln aqueous
solutlons, thus resultlng ln an energy savlngs upon
rlrlng Or the pellets. Also, the hydrophoblc llquld or
oll ln the lnverted water-ln-oll emulslon system 18
2~ consumed durlng the rlrlng operatlon. The burn out Or
01332514
D-14,834
36
the oil droplets from the interior of the pellets
increase the porosity of the pellets in much the
same manner as does the burning of the organic
binder or polymer from the interior of the pellets.
This increase in porosity is believed to improve the
release of water vapor from the pellets and decrease
the occurrence of thermal shock upon firing of the
pellets.
An additional benefit realized by the use
of a water-in-oil emulsion system, or other system
as hereinafter supplementally described, to deliver
a polymer binder to mineral ore concentrate in
pelletizing operations is a decrease in the amount
of contact time required for sufficient commingling
of hte polymer binder with the mineral ore
concentrate. The contact time of a polymer after
the system is sprayed onto the mineral ore
concentrate need only be sufficient to allow
activation of the polymer on the surface of the
mineral ore concentrate. The amount can vary
depending upon the system used and the concentration
of the polymer binder within the system as well as
the total amount of polymer binder sprayed upon the
~ mineral ore concentrate. In desirable embodiments
of this invention, sufficient time for commingling
of the polymer binder system into the mineral ore
concentrate occur by spraying the water-in-oil
emulsion onto the mineral ore concentrate upstream
of where the concentrate enters the balling
apparatus.
~... .~.
D-14,834
37 01332514
Application of a water-in-oil emulsion, or
other system as hereinafter supplementallly
described, at the mineral ore comcentrate treatment
site can be accomplished by applying the system to
the mineral ore concentrate through any conventional
spraying or dripping apparatus. The inorganic salts
are sprinkled from a vibrating hopper or other
dispersing means onto the mineral ore concentrate
and the composition is conveyed towards the balling
apparatus. Alternatively, salt can be delivered
from aqueous solutions of about 5 to about 40
percent solid material depending on the solubility
of the inorganic salt and the temperature. The
activation of the polymers onto the surface of the
mineral ore concentrate is rapid, and because the
polymers are evenly spread or commingled throughout
the mineral ore concentrate, the time required for
sufficient commingling to initiate pellet formation
is about one minute or less.
This invention also includes the
application of binding polymer systems to mineral
ore concentrate that are dry powders. In these
embodiments the dry powdered polymers are mixed
together optionally with the dry inorganic salt.
The resulting powder composition is sprinkled into
the mineral ore concentrate as the concentrate is
conveyed towards the balling apparatus. The
vibration of the conveyor means and the action of the
01332~14
38 D-14,834
balllng drum commlngles the powders lnto the mlneral ore
concentrate. Upon surrlclent contact tlme wlth the
molsture ln the mlneral ore concentrate, the polymers
are adsorbed onto the surrace Or the concentrate.
Sultable contact tlme can be es~entlally lnstantaneous,
but orten 18 between about l mlnute to 3 hours or more.
Further commlngllng occurs ln the mlxlng wlthin the
balllng drum. The use Or the dry powder polymer
embodlments Or thls lnventlon ellmlnates the need ror
emulslon spraylng equlpment. Thls lnventlon also
lncludes the appllcatlon Or powdered blnders to a
mineral ore concentrate ln conJunctlon wlth an
appllcatlon Or lnorganlc salt a~ an aqueou~ solutlon.
The useful range Or the concentratlon Or the
polymer on an actlve ba~l~ 18 between about 0.001
percent to about 0.3 percent based on welght o~ bone dry
concentrate. The prererred range 18 between about 0.001
percent and about 0.1 percent. These range~ are
appllcable for both dry and emulslrled appllcatlons Or
polymer blnders. The userul range Or the concentratlon
Or the lnorganlc salt based upon the welght Or bone dry
concentrate 18 between about 0.001 percent and about 0.5
percent wlth the pre~erred range belng between about
0.005 percent and about 0.3 percent.
The lnventlon 18 rurther understood from the
. . ,
01332514
D-14,834
39
Examples below, but ls not to be llmited to the
Examples. The numbered Examples represent the present
lnventlon. The lettered Examples do not represent this
invention and are for comparlson purposes. Temperatures
glven are ln C unless otherwlse stated. The following
deslgnatlons used in the Examples and elsewhere hereln
have the following meanlngs:
ABBREVIATION DEFINITION
AM acrylamlde
Apx. approxlmate
CaC03 calclum carbonate
cc - cubic centimeter
CMC carboxymethylcellulose
C2 carbon dioxlde
dl/g deciliter per gram
F degrees fahrenhelt
gm/cc grams per cubic centlmeter
gms grams
HEC hydroxyethylcellulose
IV lntrinsic viscoslty
lb pound or pounds
mm milllmeters
NaA sodlum acrylate
NaAMPS sodlum salt of 2-acrylamldo
01332514
D-14,834
-2-methylpropanesulfonic
acid
NaCl sodium chloride
(NaP03)n sodium metaphosphate where
n is 2 or more
Na2C3 sodium carbonate
Na20 sodium oxlde
PAM poly(acrylamide)
psi pounds per square inch
pressure
RPM revolutions per mlnute
RV reduced viscosity
tonne metric ton
U.S. United States
VA vinyl acetate
wt weight
wt % weight percent
percent by weight unless
otherwise specified
.
01332~14
D-14,834
41
LABORATORY EXPERIMENTAL PROCEDURE
In these Examples taconite pelletlzlng conslsts of a
two step procedure. Inltlally, seed balls are prepared
from the taconite ore uslng bentonlte clay as a blnder.
These seed balls are passed through screens to obtaln
seed balls of a slze that pass through a 4 U.S. mesh
screen havlng a 0.187 lnch openlng, but not through a 6
U.S. mesh screen having a 0.132 lnch openlng. The seed
balls are then used wlth additlonal concentrate and the
blnder of lnterest to prepare the larger green pellets.
Flnlshed green pellets are sleved to be ln a slze range
between 13.2mm to 12.5mm. Thls can be accompllshed by
uslng USA Sleve Serles ASTM-E-11-70. Following
slevlng, the green pellets are tested for wet crushlng
strength and wet dropplng strength. Addltlonal green
lS pellets are drled (not flred) and tested for both dry
crushlng and dry dropping strength. For the examples
clted, all testlng was done wlth elther wet or dry green
pellets.
Seed ball formatlon ln these examples ls begun wlth
a sample of 900 grams (bone dry welght) of taconlte
concentrate eontalnlng between 8 to 10% moisture. The
concentrate is sleved through a 9, 10, or 12 mesh
screen and spread evenly over an oll cloth. Next 7.0
grams of bentonlte clay ls spread evenly over the top of
0133251 l
D-14,834
42
the concentrate and mlxed untll homogenous. The mlxture
ls lncrementally added to a revolvlng rubber drum havlng
approxlmately a 16 inch dlameter and a 6 lnch cross
sectlon. The drum 18 rotated at 64 RPM. Humldlty 18
not controlled ln these Examples. Just prlor to
addltlon Or concentrate, the lnslde Or the drum 18 wet
wlth water from a spray bottle. Whlle rolllng, several
handrulls Or the bentonlte-concentrate mlxture ls added
to the drum. Dlstllled water ls added when the rormlng
agglomerates begln to develop a dull appearance. As
seed pellets are formed, they are screened to ~eparate
and obtaln pellets whlch pass through a 4 mesh screen,
but not through a 6 mesh screen. Captured flnes are
readded to the balllng drum and overslzed seeds are
reJected. The procedure of readdlng captured rlnes 18
repeated several tlmes untll surflclent seed pellets of
the deslred slze have been produced. ~he seed pellets
are then rolled for one mlnute to flnlsh the surrace.
Formed seed pellets can be placed ln a sealed contalner
contalnlng a damp cloth ~o as to retard dehydrstlon of
the pellets.
Green pellet rormatlon ln these ~xamples 18 begun
wlth a sample of 1800 grams (bone dry weight) Or mlneral
ore contalnlng bet~een 8 to lOS molsture. The
concentrate 18 added lnto a 12 lnch dlameter Clnclnnatl
01332Sl D-14,834
Muller and mlxed ror 1.0 minute. Thereafter, an amount
Or blnder to be used ln the Example 18 unlformly
dlstrlbuted over the surrace Or the concentrate. In
Examples uslng emulslon polymers, the emulslrled
polymers are unlrormly dellvered dropwlse rrom a
syrlnge. When an lnorganlc salt, such as Na2C03, 18
used ln an Example, lt 18 sprlnkled over the sur~ace of
the concentrate. For those examples whlch employ a
Na2C03 solutlon, a 30 percent salt solutlon ls used.
~or those examples whlch employ powdered polymers, the
powder 18 dry blended wlth the lnorganlc sait and the
resultlng mlxture 18 then unlrormly sprlnkled over the
concentrate ln the muller. The muller 18 then turned on
ror three mlnute~ to mlx the blnder wlth the
concentrate. The unlrorm mlxture 18 then screened
through an 8 mesh screen.
After molstenlng the lnslde Or the rotatlng balllng
drum Or tlre, about 40 grams Or seed pellets are added
to the tlre. Then the concentrate and blnder mlxture ls
lncrementally red lnto the tlre over a perlod Or six
mlnutes wlth lntermlttent use Or dlstllled water spray.
Durlng the lnltlal portlon Or thls proccss, small
~mounts Or the concentrate and blnder mlxture are added
each tlme the surrace Or the pellets appear shlny.
Typlcally, the latter portlon Or the slx ~lnute rotatlng
01332~14 D-14 834
44
perlod requlres an lncreased amount of the concentrate
and blnder mlxture when compared to the lnltlal part of
the rotatlng perlod. Water spray ls applied each time
the surface of the pellets takes on a dull appearance.
After the slx minute rotatlng perlod ls complete,
the balllng drum 1B rotated one additional mlnute to
"flnlsh off" the pellet surface. No water spray ls used
during the final one mlnute perlod. Followlng
completlon of thls procedure, the green pellets are
screened for testlng purposes to a size between 13.2mm
and 12.5 mm.
Compresslon testlng ln these Examples ls performed
by uslng a Chatlllon Sprlng Tester of a 25 pound range
~tModel LTCM - Serlal No. 567). Twenty green pellets are
crushed in the tester wlthin 30 minutes of pellet
completlon at a loadlng rate of 0.1 lnches per second.
The pounds of force requlred to crush each pellet 1B
averaged for the twenty pellets and is herein called-the
wet crush strength. An additlonal twenty pellets are
dried for one hour at 350F. Whlle these pellets are
stlll warm to the touch, the crushing procedure ls
repeated to obtaln the dry crush strength average
measured ln pounds per square lnch (psl).
Drop testlng ln these Examples ls performed with
twenty green pellets whlch are tested wlthln 30 minutes
01 332514 D-14,834
of their formatlon. These pellets are dropped one at a
time from a helght of 18 inches onto a steel plate. The
number of drops to obtain pellet failure is recorded.
Pellet failure ls determined when a crack ln a pellet of
approximately a 0.7 mm or greater occurs. The average
for twenty wet pellet drops is reported. Twenty
addltional green pellets are drled by the procedure set
out for the compresslon test and then each ls dropped
from a 3 lnch helght. The average number of drops to
1~ obtaln pellet fallure for twenty pellets is determlned
and recorded.
Definltlon of acceptable or target pellet mechanlcal
propertles is defined in these Examples, within limits
of experimental error, by a comparison to the
performance of Peridur, a commercial blnder. Perldur was
analyzed to be 68 percent carboxymethylcellulose wlth
about 16 percent NaCl and about 16 percent Na2C03.
Peridur ls known to produce acceptable results in some
plant scale pelletizlng operatlons at a dose of 1.55 lb
product/tonne of concentrate. Slnce the product ls
about 68% sodlum carboxymethylcellulose, Peridur
ls used at an actlve polymer dose of about 1.05
lb/tonne. Perldur is sold by Dreeland Colloids, 1670
Broadway, Denver, Colorado.
Wet drop numbers above about 2.5 and wet crush
. ~1332514
D-14,834
46
numbers above about 3.0 are useful. Dry drop numbers
greater than about 2.0 and dry crush numbers above about
4 are acceptable. Comparisons of pellet mechanlcal
-propertles for dlfferent blnders need to be made at
approxlmately equal pellet molsture contents. Wet
pellet propertles are lmportant because wet pellets are
transported by conveyors and are dropped from one
conveyor to another durlng thelr movemènt. Dry
propertles are lmportant because ln klln operatlons
pellets can be stacked 6 to 7 lnches hlgh or more. The
pellets at the bottom of such a plle must be strong
- enough so as not to be crushed by the welght of the
pellets on top of them. Dry pellets are also conveyed
- and must reslst breakage upon dropplng.
Unless otherwlse stated ln the followlng examples,
the term, water-ln-oll emulslon, refers to a
water-ln-oll emulslon contalnlng an lnvertlng
surfactant. In these emulslons the oll phase ls
Isopar M.
01332514
D-14,834
47
EXAMPLE A
The experlmental procedure descrlbed above was used
to prepare and test two samples Or green pellets of
taconate.concentrate formed wlth a commerclal
CMC/NaCl/Na2C03 blnding agent system. The amount of
bindlng agent used and the results are presented ln
Table III.
TABLE III
Ib Perldur lb actlve
per polymer/ wet wet dry wet %
tonne tonne crush drop crush drop H20
1.18 0.80+ 4.6 2.7 4.2 2.1 ---
4.6 2.5 4.8 2.1 9.2
+ carboxymethylcellulose
EXAMPLE I
The expérlmental procedure descrlbed above was used to
prepare and test two samples of green pellets of taconlte
concentrate formed wlth a PAM/NaA/VA blndlng agent ln a
water-ln-oll emulslon. The mole percent of PAM/NaA/VA ls
47.5/47.6/4.9. The oll used ln the external phase was
Isopar M. The lntrlnslc vlscoslty of the polymer was 23
dl/g. The amount of bindlng agent used and the results are
presented in Table IV.
0133251~
D-14,834
48
TABLE IV
.
lb actlve
lb emulslon polymer/ wet wet dry dry S
per tonne tonne cruqh drop crush drop H20
1.36~ 0.40 4.0 4.5 4.9 2.7 9.1
0.91 0.27 3.5 3.0 3.6 2.4 9.1
also contalns 0.78 lb Na2C03/tonne
Thl~ example show-q that the dual addltlon Or an
emulslon contalnlng the polymer derlved rrom acrylamlde,
~odlum acrylate, and vlnyl acetate ln a 47.5/47.6/4.9
mole ratlo along wlth Na2C03 produce a taconlte blnder
S whlch ls superlor to the blnder system used ln Example A
whlch employs a CMC/NaCl/Na2C03 blndlng agent. At one
halr the actlve polymer dose the PAM/NaA/VA-Na2C03
system gave a hl~her wet drop number than the control
blnder Or Example A.
EXAMPLE B
The experimental procedures descrlbed ln Examples A
and I were used to prepare and test the green pellets of
taconlte concentrate ln this Example. The pellets Or
this Example are rormed with either a commerlcal
CMC/NaCl/Na2C03 or HEC/Na2C03 binder system. The
concentratlon and te6t results are ln Table V below.
~1332514
.
D-14,834
49
TABLE V
lb actlve
polymer/ wet wet dry dry S
binder tonne crush drop crush drop H20
HEC/Na2C03+ 0.78 3 3 4.0 2.5 ---
CMC/NaCl/
Na2C03~+ 1.05 4.0 2.9 5.4 2.8 8.0
+ 50/50 mlxture.
~+ 68/16/16 wt% (average Or 3 runs)
EXAMPLE II
The experlmental procedures descrlbed in Examples A and
I were used to prepare and test green pellets Or taconite
concentrate formed with a PAM/NaA/VA blndlng agent in a
water-ln-oll emulslon. The mole percent Or PAM/NaA/VA ls
47.5/47.6/4.9. The oil used ln the external phase was
Isopar M. The concentration and test results are ln Table
VI below.
01332514 D-14,834
5o
TABLE VI
lb actlve
polymer/ wet wet dry dry S
tonne cr~sh drop crush drop H20
PAM/NaA/VA-
Na2CO3~ 0.78 3.3 6.2 6.8 4.3 9.8
Thls ls a 50/50 mlxture; PAM/NaA/VA had an IV of 10.3 dl/g.
Thls Example show~ that the dual addltlon of a
47.5/47.6/4.9 mole ratlo o~ PAM/NaA/VA bindlng sy~tem wlth a
lower molecular welght as evldenced by an IV o~ 10.3 ln a
water-ln-oll emulslon along wlth Na2C03 produces a taconlte
blnder system whlch 18 superlor to the current art employlng
comblnatlons Or hydroxyethylcelluloQe/Na2CO3 or
carboxymethylcellulose/NaCl/Na2CO3. Note that wet drop
number, dry crush and dry drop were all better wlth the
PAM/NaA/VA-Na2CO3 blnder system.
10EXAMPLES C AND III
The procedure~ ror preparlng and testlng the green
pellets ln these Examples were the same as descrlbed ~or
Examples A and I. These Examples compare pellet strength
resultlng rrom ~arylng concentratlons Or polymer blnder
15systems. The concentratlons and te~t results are ln Table
VII below. ~
D-14, 834
51
01332514
o
ol .. . . .
Op c~J o a~ 0 0
~1
P~ o , ~ o ~ , U~ ,
o . . .
3 C~
_ D 3 ~ U ~ 3 O~
C~ U~ ~ 3 ~ ~I
O~
nl
O 'D ~ t~ D O l~ 3
~t. . .. . . . . ~
~-
r~ U~
~n
. . . S
t~') 3 ~ t~ 3 tr~
o
C
~ ~
Hr~l O
a~ O ~U ~ 0
~~ _1 0 ~ O ~ ~ ~ ~D Z ~
Ct~t~ O O .- O
.s ~c ~a o _, o o o o P ~3
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o ~ ~
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- l o ~ 0
0 ~ ~ O O E O
U~ I o o " C~
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_~ ~ ~ o ~
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0 ~ 0 ~ ~ ~ ~ ~ 0 ~n ~ ~ a ~
C~ 2 ~ 8 ~ z D C
~ ~ N S: N ~ ~ ~1
": 0 :E: 0~C 0 ~ 1~~e 0 ~ 0
P~ Z t:~ ZP~ Z C~ Z ~ Z ~ Z ~ '
K ~ H H
~ 01332S14
~ D-14,834
52
These examples show that mechanical properties~of
taconite pellets formed wlth a PAM/NaA/VA binding agent
in a water-ln-oll emulslon lmprove w1th increaslng dose.
Comparlson of the poly(acrylamlde) based polymer blnder
system ln Exàmple III ls made at each concentration to a
CMC/NaCl/Na2C03 blnder system ln Example C.
EXAMPLE IV
The procedures for preparlng and testing the green
pellets in this Example were the same as described for
Example I. This Example compares the effect of
lntrinslc vlscoslty on pellet s.trength for.a
poly(acrylamlde) based polymer blnder system. The
lntrinslc vlscosltles and test results are ln Table VIII
below.
01332~14
D-14,834
TABLE VIII
DOSE: O. 78 LB ACTIVE POLYMER/TONNE
wet wet dry dry
IV crush drop crush drop H20
10.8 2.8 8.1 5.4 4.3 10.3
23.0 3.2 11.6 5.6 4.1 10.1
~ Mole percent of PAM/NaV/VA 47.5/47.6/4.9 and also
contalns 0.78 pounds Na2C03 per tonne.
Thls example shows that polymer blnder systems of
hlgher lntrlnslc vlscosity produce better mechanlcal
pellet propertles wlth taconlte concentrate when the
polymer blnder 18 a PAM/NaA/VA terpolymer.
EXAMPLE V
The procedures ror preparlng and testlng the green
pellets ln thls Example were the same as descrlbed ~or
Example I. Thls Example compares the er~ect on pellet
stren6th occurrlng when the mole ratlos Or a polymer's
monomers are varled. The mole ratlo~ and the test
results are presented ln Table IX below.
D-14, 834
54
0133251~
.
.
~ I a~ u~ ~ c~
Z ~ N
' U~ O t- ~1
. :~0~ . '
~ ~ ~ ~U ~ ~ C~l.
x ~ . e
oq
~ o ~ ~ ~ ~ ~ 0 ~,
a:l ~ L C~ O
~ ~ ~ ~ ~ 3 3 ~ p,
E-~ h
~ a~
e
:~ .
~,
o ~ C~
a~ 0
o O O ~ O o ~
a~ ~ . . . . ~ ~1
C~ ~ ~ ~ ~ ~ ~ o o
a~
~,
C~
J~ ~ O
C~ C) -
. 6q ~ al ~ o
O J~ :5 U~
a~ L
3 ~) ~ o O ~
bO 00 bO ~1
~ ~ 3 fi
o a)~: ~ o o u~ _~
c~~ ~D X
J~ ~~ . ~~n 3 ~7 o ~ O
C~ ~ ~ ~ ~ ~ ~ ~: C~
d J ~ ~ ~ R
~ O Z ~ 3 u~ Z ~ ~ ~
:,. ~ a ~Ir~ C~J ~ ~ 3 H 1-~ L ~¢
~e~ ~ . ~ ~ ~: ~
o o o ¢ t_ ~ O ct a~ ....
fi~ 3 ~ a~ ~ L~ ~ J ~)3
l~
0133251~
D-14,834
~5 .
Tblo Example ~how~ that NaA bet~een about 15 and
about 41.1 ~ole percent wao not crltlcal to acnle~e
ratl~r~ctory perrormance ln an acrylamide polymer.
EXAMPLES D ~ND VI
T~e procedure~ ror preparlng and tcstlng the green
pelleto ln t~lo Example ~ere the ~ame a8 descrlbed ror
Exampleo A and I. The concentr~t~ons and test re~ult~
are ln Table X below.
iJ
, ?
- 01332514
D-14,834
56
TABLE X
DOSE- 0.39 LB ACTIVE PAM COPOLYMER/TONNE
PLUS 0.78 L~ Na2C03/TONNE
Copolymer
mole S wet wet dry dry S
Example PAM/NaA crush drop crush drop H20
VII 59/411 3.4 5.5 4.4 2.5 9.1
VII 76/242 3.3 4.2 4.6 2.8 8.5
VII 85/153 3.7 4.9 4.8 2.3 8.1
VII 100/04 3.4 2.5 4.4 3.3 8.0
powder
D CMC
Perldur5 4.2 2.6 4.4 2.1 8.2
Control
t tl.O5 lb emulsion/tonne).
1. IV ~ approximately 20 dl/g.
2. IV - 17.3 dl/g.
3. IV ~ 16.2 dl/g.
4. IV ~ 15.4 dl/g, thls powder is AD-10 sold by Rhone Poulenc
5. 1.17 lb/tonne (containlng 0.8 lb CMC polymer/tonne).
These Example~ show that acrylamlde copolymers
contalning O to at least 41 percent Na acrylate are
er~ectlve as blndlng agents ror taconlte concentrate.
~.:
0133251~
D-14,834
57
EXAMPLE VII
The procedures ror preparlng and testlng the green
pellets ln thls Example were the same as descrlbed in
Example I. The concentratlons and test results are ln
Table XI below.
TABLE XI
Dose: As shown ~ 0.78 lb Na2C03~tonne
actlve
copolymer polymer
mole S dose wet wet dry dry S
PAM/NaA lb/tonne crush drop crush drop H20
89/11 0.78 3.9 4.4 6.8 3.1 9.2
77/23 0.78 3.7 6.9 7.9 3.3 9.1
These Examples show that solld poly(acrylamlde)
based copolymers ln powder ~orm are e~rectlve blndlng
agents ror taconlte concentrate.
EXAMPLES E AND VIII
The procedures ror preparlng and testlng the green
pellets ln these Examples were the same as descrlbed ln
Examples A and I. The polymer blnder system used and
the te~t results are ln Table XII below.
.
0l332~l~
D-14,834
58
TABLE XII
Dose of PAM based polymers 0.39 lb active/tonne + 0.78
lb Na2CO3/tonne
wet wet dry dry %
Composition crush drop crush drop H20
PAM/N Decyl
Acrylamlde 2.7 3.0 4.7- 3.0 8.5
(99/1) nonionlc
PAM/Slpomer Q5-801 3.1 2.4 4.4 2.8 8.4
94/6 cationlc
CMC/NaCl/
Na2CO 2
(cont~ol) 4.2 2.6 4.4 2.1 8.2
1 Sipomer Q5-80 is Dimethylaminoethylmethacrylate/Dimethyl
sulfate quaternary salt.
2 0.8 lb CMC/tonne.
These Examples show that emulslons of nonlonlc
poly(acrylamide) based polymers wlth long chaln
hydrophoblc groups and cationic modl~led PAM perform
well as taconlte binders when compared to CMC based
products. The results obtalned from these Examples
demonstrate that an emulsion of PAM/NaA/VA is better
than or roughly equivalent to a CMC/NaCl/Na2C03 bindlng
agent ln both drop tests and compression tests.
0133251~
D-14,834
59
EXAMPLE IX
The procedures for preparing and testing the green
pellets ln thls Example were the same as described ln
Example I with the exceptlon that the lnorganic salt
used in thls example ls applied as a 30 percent aqueous
solutlon. The polymer blnders ln thls example are ln a
water-ln-oll emulslon. These tests were conduc~ted on
taconlte ore concentrate and demonstrate the effect of
applylng the polymer binder emulslon and lnorganic salt
solutlon ln different sequences to the mlneral ore
concentrate. When these llqulds are applled to the
mlneral ore concentrate separately, the flrst liquid ls
mixed wlth the mlneral ore concentrate ln a muller. The
second llquld ls then added and the total composltlon ls
- mlxed for an addltlonal 3 mlnutes. The test results are
presented ln Table XIII below.
. 01332514
D-14,834
TABLE XIII
Dose: emulslon 1.1 lb emulsionl/tonne ~ Na2C03 0.81
lb/tonne
Total
Method of Mlnutes Wet Wet Dry Dry S
Additlon Or Mlxln~ Drop Crush Drop Crush Water
Emul~ion2 6
then
Na2C03 Solutlon 3 6.7 3.8 2.3 5.2 8.9
Na2C03 Solutlon 6
then
Emul~lon 3 8.4 3.7 2.0 4.0 9.1
Emulsion and
Na C0 Solutlon
Appll~d
Together3 6 5.2 3.7 2.2 4.8 8.
1 The emulslon contaln~ 27.6 percent actlve polymer.
2 The emulslon was PAM/NaV/VA ln a mole percent Or
47.5/47.6/4.9.
3 The emulslon and lnorganlc salt solutlon were applled
concurrently to the taconlte ore concentrate rrom
sepsrate contalners.
01332514
D-14,834
61
Thls example demonstrates that an lnorganlc salt
solutlon can be applled ln con~unctlon wlth polymer
blnders to effectively agglomerate a mineral ore
concentrate.
EXAMPLE X
This Example was conducted on taconite concentrate
ln the same manner as Example I. Thls example compares
the effectlveness of a blndlng agent ln a water-ln-oll
emulslon both with and wlthout an lnvertlng surfactant.
Thls test lnvolved a two-step addition. The Na2C03
powder was added to the taconite concentrate and mixed
for three minutes. The emulsion was then added and the
entire composition was mixed an addltional three
mlnutes. The test results are presented ln Table XIV.
01~32S14
D-14,834
62
TABLE XIV
Wet Wet Dry Dry S
Drop Crush Drop Crush -Water
Emulslon
with lnvertlng
surractant 5.1 3.9 2.0 4.4 8.5
E ~ ~
surfactsnt 3.7 3.9 2.0 3.6 8.3
~ Both emulslons contaln PAM/NaA/VA in a 47.5/47.6/4.9
mole ratlo at l.l pounds Or emulslon per tonne and 0.81
pounds Na2C03 per tonne.
,~
~133251~
D-14,834
63
This experlment demonstrates that acceptable green
pellets are formed both with and without an lnvertlng
surfactant in the emulsion.
.
0133251~
64 D-14,834
EXAMPLES F AND XI
The rollowln~ Examples were conducted ln rull scale
plant wlth a full slze balllng drum and klln. In these
Examples 55 tonnes per hour Or taconlte concentrate were
conveyed to and processed ln the balllng drum. The
selected blndlng agent systems were added by spraylng
onto the taconlte ore concentrate Ju~t prlor to enterlng
the balllng drum and by vlbratlng the Na2C03 powder onto
the taconite ore concentrate. The average contact tlme
Or the blnders wlth the mlneral ore concentrate berore
enterlng the balllng drum was approxlmately 0.5 to l
mlnute. The average slze Or the green pellet~ obtalned
were between approxlmately one-rourth to one-halr lnch
ln dlameter.
In Example XI an anlonlc water-ln-oll emulslon Or
PAM/NaA/VA ln a mole percent Or 47.5/47.6/4.9 was used
as a polymer blndlng agent. The quantltles Or blndlng
agents used and the results obtalned by the
poly(acrylamlde) based polymer blnding agents are
detalled ln Table XV. Comparatlve results ~or other
blndlng agents are ln Table XVI.
01332514
D-14,834
TABLE XV
PAM/NaA/VANa2C03 Wet Wet Dry2
Te~tlgal/ lb/ lb/ lb/ Compresslon 18" Compresslon
E~ample Number mln tonne mln tonne psl drop psl
IX 1 0.145 1.4~ 0.73 0.80 --- --- ---
IX 2 0 0 0.73 0.80 --- --- ---
IX 3 0.145 1.45 0.00 0.00 --- --- ---
IX 4 0.10 0.94 0.73 0.80 1.5 8.4 2.3
IX 5 0.11 1.05 0.37 0.40 1.6 7.0 1.8
IX 6 0.14 1.34 0.95 1.04 2.1 10.6 2.8
IX 7 0.12 1.12 1.70 1.85 2.1 9.6 3.1
0 16363 2 5 1 4 D-14,834
TABLE XV CONTINUED
Test Avg. Fired3 S Or Flne~ 18" Drop
Number Compres~lon That Break S S Mln. after ~tart of blnder
addltlon
Cont. p~l Under 200 psl FeO H20 10 20 30
1 320 19 0.43 9.6 __ 16.0 7.3 7.6+
2 -- -- -- 9.2 6.0 4.2 3.6 --
3 -- -- -- 10.1 4.5 11.1 9.3 --
4 194 63 0.35 10.1 8.7 7.8 8.5 --
244 50 0.31 9.4 8.o 9.3 8.0 --
6 118 85 5.1 -- 10.5 18.7 13.2 6.6+
7 259 42 0.31 9.8 12.5 12.1 11.9 --
~,
~ 3
01332514
67 D-14,834
TABLE XV CONTINUED
Slze Dlstrlbutlon Or Pellets
Test
Number
Cont. +1/2" ~7/16" +3/8" +11/32" +1/4" -1/4"
1 2.2 43.2 43.7 7.8 1.4 1.8
2 13.6 57.1 19.9 4.8 2.1 2.5
3 2.9 33.5 40.8 14.3 4.8 3.7
4.7 31.8 46.4 8.5 2.8 5.9
4 2.7 27.9 44.6 15.1 4.6 5.1
1.4 45.4 44.3 6.8 1.1 1.0
6 1.2 14.1 58.6 20.2 3.8 2.1
7 1.9 22.5 57.9 12.9 2.8 1.9
1 Samples were obtalned by (1) rllllng a basket with green
pellets, (2) transportlng the basket through the klln
operatlon, and (3) testlng pellets from the top, mld-top,
mld-bottom, and bottom Or the basket.
2 Pellets contaln no molsture, samples are taken Just prlor
to klln operatlons.
3 Samples are taken after drylng ln klln.
+ 48 MIN
++ 40 MIN
~!133251~1 D-14,834
~1
.,1
~ o~
W ~I
S ~ O . I ~D
I V
.,~
U~
U~
~ ~ I _l o
DJ ~ I u~ ~
~ I ~U ~
r Do
.
K K O
~ a ~ _,
~ ~: ~ o
. o o
~0
_ _
K K
., ~ ~0, ~,
~-~
# ~
_ ~ _ ~ 0 _I
~0 ~ C~ ~0 C _~ 0--
0 ~ 0 0 ~ O C 0 0 K
Z O ~ Z O ~ -~ O--
g ~ C~ ~C~ C~ ~ ~
~0 P C~ ~0 ~
.,~ ~ ~: 0 e~ 0
~; ~ C:~ Z--~ z_~ ~ _ ~ #
'~
~, ~
. i~,
01332514
D-14,834
69
These Examples show that the 18 inch drop number
for wet green pellet~ and the dry compresslon strength
Or dry pellets lmprove wlth lncreases ln Na2C03
concentratlon. Varylng the concentratlon Or Na2C03 dld
not show a trend ln the compresslon strength Or rlred
pellets.
01332514 D-14,834
SUPPLEMENTARY DISCLOSURE
The polymers of this invention may be
applied to the mineral ore concentrate as a
dispersion in a non-aqueous dispersion medium, that
is for example in one or more of the following
forms: (i) a water-in-oil emulsion in which oil is
the non-aqueous portion of the emulsion, or (ii) a
dispersion of fine polymer particles in oil such as
may be made by removing water from a water-in-oil
emulsion or by methods described in U.S, Patent No.
4,325,861 of Braun and Rosen. "Oil" is used broadly
in this context to include any vehicle, preferably
an organic vehicle, which is a non-solvent for the
polymer. The size of the fine polymer particles is
preferably such that, in the selected dispersion
medium, they either resist settling and
stratification, or they have a tendency to settle or
stratify but are easily redispersed before addition
to the mineral ore concentrate. The size of the
dispersed fine polymer particles required for such
stability will therefore depend on the
characteristics of the selected dispersion medium,
particularly its density and viscosity.
01332~1~ D-14,834
71
Additional inorganic salts which may be
used in this invention include dolomite and
magnesium carbonate.
Desirable polymers for use in this
invention include those of the previously described
formulas wherein R2 includes equivalent cations
such as NH4.
The third class of polymers used in this
invention includes those polymers in the form of
dispersions in oil. A representative but
non-limiting list of polymers useful in this form
includes those set forth previously in Table I.
The polymer dispersed in oil systems used
in this invention may be a dispersion of fine
particles of polymer in oil such as may be made by
removing water from water-in-oil emulsions of the
kind described previously. Dispersions of polymers
in oil used in this invention may also be
dispersions of fine particles of polymers prepared
as described for example in U.S. Patent No.
4,325,861 of Braun and Rosen. Desirable hydrophobic
liquids used in these dispersions are the same as
the hydrophobic liquids used in water-in-oil
emulsions referred to previously.
B
72 D-14,834
While the process of this invention
comprises using polymer dispersions or dry powders
alone, it also-comprises their use with other
materials such as bentonite. In a preferred method
of practicing the present invention, the
water-in-oil emulsion contains approximately 30
weight percent of a copolymer (prepared from
approximately 50 weight percent acrylamide monomer
and 50 weight percent sodium acrylate monomer), 35
weight percent water, 35 weight percent Isopar~ M,
and a nonyl phenol ethoxylate as a surfactant.
Before spraying onto taconite concentrate, the
emulsion may be filtered to remove gels which might
clog the spray nozzle. The emulsion is added at the
rate of about 0.6 pounds per tonne. In accordance
with the invention of Canadian Patent Application
Serial No. 509,056-3 filed May 13, 1986, and
assigned to a common assignee, bentonite may also be
added at the rate of 9 pounds per tonne.
Preferably, the bentonite is added after the
emulsion and just before the taconite concentrate
enters the pelletizing drums or discs.
The process of this invention may also be
used to make flux pellets. These pellets are made
I r`' ~
01332514 D-14,834
73
by adding to the taconite concentrate an inorganic
material that tends to reduce the acidity of the
resulting pellets. The inorganic material may be
one or more of the following dolomite (Ca,Mg)CO3),
high calcium dolomite (also known as limestone or
calcium carbonate) and magnesium carbonate. These
may be added prior to, simultaneously with, or after
the addition of the polymer to the particulate
material. Flux pellets are sometimes described in
terms of their basicity -- the ratio of bases to
acids defined as the ratio of weight % (CaO + MgO/
(SiO2 + A12O3). When basicity is measured,
flux pellets may typically have a basicity ratio of
about 1.0 to 1.1.
In addition to the designation used in the
Examples listed previously, the additional
abbreviation (Ca,Mg)CO3 means dolomite.
EXAMPLE XII
Following the procedures used for preparing
and testing green pellets described above in Example
I, dispersions of fine particles of a polyacrylamide
polymer in an oil dispersion medium were added to
taconite concentrate from the Mesabi range at the
rate of 0.36 pounds of dispersion product per tonne
, .
01332514
D-14,834
74
(for an effective rate of 0.18 pounds of polymer per
tonne). These dispersions contained 50 weight
percent light mineral oil, fifty weight percent
polymer and essentially no water. In all cases,
bentonite was also added at the rate of 9 pounds per
tonne. The results obtained are set forth on Table
17.
These dispersions varied in the
polyelectrolyte charge density that they exhibited,
as shown under the column headed "charge" in Table
17. The non-ionic polymer used in Test 1 was
obtained as a homopolymer of acrylamide which
applicants believe had an I.V. of about 15. The
anionic polymers of Tests 2 and 3 were obtained as
copolymers of acrylamide and sodium acrylate; I.V.,
about 15. The polymers of Tests 4 and 5 were
prepared from acrylamide and quaternary salts of
dimethyl-aminomethyl methacrylate; I.V., about 7 to
15.
As a control, a water-in-oil emulsion which
contained 30 weight percent of a copolymer prepared
from acrylamide monomers and sodium acrylate monomers
(approximately 50/50 weight percent) was added at the
rate of 0.6 pounds per tonne (for an effective rate
,~
01332514 D-14 834
of 0.18 pounds of polymer per tonne) with bentonite
added at the rate of 9 pounds per tonne. The results
are also set forth on Table 17.
TABLE 17
% H20
Ionic Green Green Dry in
Test Character Charqe Drop Crush Crush Pellets
1 Non-ionic None 5.2 4.711.4 9.4
2 Anionic Med. 10.1 4.4lO.9 9.6
3 Anionic High 6.5 4.1 9.9 9.4
4 Cationic Med. 5.6 4.713.3 9.4
Cationic V. High5.4 4.911.5 9.5
Control Anionic Med. 7.0 4.7 9.6 9.7
The procedures for preparing and testing
pellets used in the following Examples XIII to XVI
were the same as described for Example I. The
weights per tonne in these examples are based on the
weight of taconite concentrate after removal of all
moisture.
EXAMPLE XIII
Relatively high sodium carbonate systems,
e.g. those having approximately 2.5 to 3 lb/tonne of
added Na2CO3, may be used with the polymer
systems of this invention to obtain improved green
;
01 332514 D-14,834
76
drop performance. In this example, polymer is used
in the form of a water-in-oil emulsion containing
approximately 30 weight percent of a copolymer
(prepared from approximately 50 weight percent
acrylamide monomer and 50 weight percent sodium
acrylate monomer), 35 weight percent water, 35 weight
percent Isopar M, and a nonyl phenol ethoxylate
as a surfactant. Polymer delivered as a water-in-oil
emulsion and Na2CO3 delivered as a powder were
added to a taconate concentrate in the amounts and
with the results shown in Table 18.
TABLE 18
lb.
lb emul- Na2C3
sion per per green green dry % H2O
tonne tonne drop crush crush in pellets
0.8 3.0 5.4 4.0 7.9 8.7
EXAMPLE XIV
In some cases it may be desirable to use
reduced levels of Na2CO3 in order to reduce the
sodium content of the pellets. Sodium in the pellets
is believed to lead to the creation of sodium
cyanides in the furnace which, insufficiently large
amounts, lead in turn to corrosion of the furnace
~;,
01332514 D-14,834
77
walls. Therefore, some furnace operators prefer to
operate at least then about 0.075% by weight of
sodium, which may be expressed as Na2O 0.075%
sodium corresponds to about 3 lb/tonne of Na2CO3
if there is no other significant source of sodium
added or in the taconite concentrate. Most
preferably one may operate at sodium levels of about
0.03% or less of sodium expressed as Na2O (i.e.,
less than about 1.2 lb/tonne of added Na2CO3. In
order to reduce sodium we have used dolomite
[(Ca,Mg)CO3 or CaCO3] in place of Na2CO3 with
the polymer of Example XIII and obtained the results
shown in Table 19. This table shows that dolomite is
not as effective as an equal weight of Na2CO3 but
that a slightly higher dose used with a somewhat
higher dose of polymer required to achieve the same
green drop. This experiment shows a dosage of
polymer and dolomite found to achieve green drop
comparable to that achieved w/Na2CO3 in Example
XVII.
TABLE 19
lb emul- lb dolo- % H2O
sion per mite per green green dry in
tonne tonne drop crush crush pellets
0.8 3(1) 4.3 3.6 3.8 9.2
1.0 6(1) 5.3 3.3 3.2 9.4
(1) Delivered from 20% slurry in water.
"~
~1332514
D-14,834
78
EXAMPLE XV
We have found that by the combination of
both Na2CO3 and dolomite at lower levels with
dolomite and the polymer of Example XIII, the levels
of both green drop and dry crush are unexpectedly
increased to improved levels, as shown in Table 20.
The table also illustrates that limestone (CaCO3)
an be substituted for the dolomite, if desired. We
believe that magnesium carbonate may also be
substituted for dolomite and that combination of
these inorganic salts will be comparably useful.
TABLE 20
lb. lb lb lb
emulsion dolomite limestone Na2C03 % H20
per per per per green green dry in
tonne tonne tonnetonne drop crush crush pellets
0.8 6.0(1) -- 1.2(2) 6.1 3.9 9.1 8.6
0.6 5.0(1) -- 1.2(2) 5.2 4.5 8.5 8.5
0.8 -- 6.o(3) 1.2(3) 5-0 4.1 8.0 8.6
(1) Delivered from 20% slurry in water
(2) Delivered from powder.
(3) Delivered together as Na2C03 dissolved in sufficient
water to make a 35% slurry of the limestone.
EXAMPLE XVI
Table 21 shows that pellets with outstanding
green properties may be obtained when using the
01332514 D-14,834
79
polymer dispersion of Example XIII in flux pellets.
Table 41 also illustrates that the omission of
Na2C03 affects both the green drop and dry crush
of the pellets.
TABLE 21
lb/tonne % H20
green green dry in
Dolomite Limestone Emulsion Na2C03 drop crush crush pellets
112(1) 112(1) 1.0 3.o(2) 9.0 4.3 9.1 9.2
112(1) 112(1) 1.O l.2(2) S.6 4.2 9.0 9.0
112(1) 112(1) 1.O 3 o(3) 6.6 4.3 7.1 9.2
112(1) 112(1) 1.0 0.0 4.7 3.5 3.4 9.6
(1) Added from a 1/1 blend as a 50% slurry in water to 60%
taconite slurry (in water) prior to filtration and prior
to the additional polymer and sodium carbonate.
(2) Added from a water solution downstream of the filtration
of the taconite/dolomite/limestone slurry.
(3) Added from a water solution upstream of the filtration of
the taconite/dolomite/limestone slurry.
B
