U.S. patent application number 11/631552 was filed with the patent office on 2008-02-07 for dust suppression and reduction of surface oxidation for mineral agglomerates.
Invention is credited to Stephen Adkins, Susan Margaret Hey, Martin Geoffrey Neale, Paul Stocks.
Application Number | 20080028890 11/631552 |
Document ID | / |
Family ID | 32947489 |
Filed Date | 2008-02-07 |
United States Patent
Application |
20080028890 |
Kind Code |
A1 |
Hey; Susan Margaret ; et
al. |
February 7, 2008 |
Dust Suppression and Reduction of Surface Oxidation for Mineral
Agglomerates
Abstract
The present invention provides a composition consisting
essentially of a mineral substrate and a dust suppresant, which is
adhered to the surface of the mineral substrate, and methods of
reducing dust generation of a mineral substrate by applying a dust
suppresant to the surface of the mineral substrate. The dust
suppresant is a natural or synthetic triglyceride.
Inventors: |
Hey; Susan Margaret;
(Bradford West Yorkshire, GB) ; Adkins; Stephen;
(Cleckheaton West Yorkshire, GB) ; Neale; Martin
Geoffrey; (Bradford West Yorkshire, GB) ; Stocks;
Paul; (Bradford West Yorkshire, GB) |
Correspondence
Address: |
CIBA SPECIALTY CHEMICALS CORPORATION;PATENT DEPARTMENT
540 WHITE PLAINS RD
P O BOX 2005
TARRYTOWN
NY
10591-9005
US
|
Family ID: |
32947489 |
Appl. No.: |
11/631552 |
Filed: |
July 18, 2005 |
PCT Filed: |
July 18, 2005 |
PCT NO: |
PCT/EP05/53439 |
371 Date: |
January 4, 2007 |
Current U.S.
Class: |
75/770 |
Current CPC
Class: |
C22B 1/244 20130101;
C22B 1/14 20130101; C22B 1/2406 20130101 |
Class at
Publication: |
075/770 |
International
Class: |
C22B 1/14 20060101
C22B001/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 27, 2004 |
GB |
0416700.3 |
Claims
1. Composition consisting essentially of a mineral substrate and a
dust suppressant, which is adhered to the surface of the mineral
substrate, wherein the dust suppressant is a natural or synthetic
triglyceride or a mixture comprising triglycerides.
2. Composition according to claim 1, wherein the dust suppressant
is a natural triglyceride or a mixture comprising natural
triglycerides.
3. Composition according to claim 1, wherein the mineral substrate
is an ore pellet.
4. Composition according to claim 1, wherein the mineral substrate
is an iron-ore pellet.
5. Composition according to claim 1, wherein the amount of dust
suppressant is chosen in the range of from 0.05 to 2.5% by weight
per weight pellet.
6. Composition according to claim 1, wherein the dust suppressant
is adhered to at least 80% of the surface of the mineral
substrate.
7. Method of reducing dust generation of mineral substrate
comprising applying a dust suppressant to the surface of a mineral
substrate having a temperature in the range of from 150 to
250.degree. C. and an amount in a range of 0.05 to 2.5% by weight
per weight of mineral substrate, wherein the dust suppressant is a
natural or synthetic triglyceride or a mixture comprising
triglycerides.
8. (canceled)
9. Method of reducing dust generation of mineral substrate
comprising applying a dust suppressant to the surface of a mineral
substrate having a temperature in the range of from 100 to
250.degree. C. and an amount in a range of 0.05 to 2.5% by weight
per weight of mineral substrate, wherein the dust suppressant is
applied in the form of a nonaqueous foam.
10. Method according to claim 9, wherein the dust suppressant is
applied in the presence of a surfactant.
11. Method according to claim 9 wherein the dust suppressant is a
natural or synthetic triglyceride or a mixture comprising
triglycerides.
12. Method according to claim 9, wherein the mineral substrate is
an ore pellet.
13. Method according to claim 12, wherein the ore pellet is an
iron-ore pellet.
14. Dust suppressant in the form of a nonaqueous foam.
Description
[0001] The present invention relates to a composition consisting
essentially of a mineral substrate and a dust suppressant, which is
adhered to the surface of the mineral substrate, and to methods of
reducing dust generation of a mineral substrate by applying a dust
suppressant to the surface of the mineral substrate.
[0002] WO 03/052149 A1 describes iron ore pellets having
incorporated saturated hydrocarbons such as paraffin oils or
synthetic oils in order to make the iron ore pellets resistant to
abrasion, sticking, degradation and emission of dust. The saturated
hydrocarbons are incorporated into the iron ore pellet at
250.degree. C.
[0003] WO 2004/099452 A1 describes iron ore pellets, wherein the
surface layer of the pellets is coated with polymer or synthetic
oils. The amount of polymer or synthetic oil is 0.14 to 1% by
weight per weight pellet. The polymer or oil is applied to the
pellets at 250 to 300.degree. C. The addition of the polymer or oil
is best accomplished through the preparation of the polymer or oil
diluted in 50 to 80% water.
[0004] The disadvantages of dust suppressants described in WO
03/052149 A1 and WO 2004/099452 A1 are they are saturated
hydrocarbons or synthetic oils that are not very convenient to work
with. They can be toxic and flammable and thus represent a health
risk and they are usually not biodegradable and thus can cause
environmental problems when spilt or lost due to wind carry.
[0005] Therefore, it is an object of this invention to provide a
composition consisting essentially of a mineral substrate and a
dust suppressant, which is adhered to the surface of the mineral
substrate, wherein the dust suppressant is biodegradable and does
not constitute a health risk.
[0006] This object is solved by the composition according to claim
1 and the method according to claim 7.
[0007] The dust suppressant of WO 2004/099452 A1 has the additional
disadvantage that it is applied to the iron ore pellets as a
preparation diluted in 50 to 80% water. This aqueous dust
suppressant preparation causes spitting problems when applied to
the hot iron ore pellets as it instantaneously boils.
[0008] Therefore, it is a further object of this invention to
provide a more convenient method of applying dust suppressants.
[0009] This object is solved by the method according to claim
9.
[0010] The composition of the present invention consists
essentially of a mineral substrate and a dust suppressant, which is
adhered to the surface of the mineral substrate, wherein the dust
suppressant is a natural or synthetic triglyceride or a mixture
comprising triglycerides.
[0011] Triglycerides are esters of glycerine and fatty acids. In a
preferred embodiment the triglycerides are natural such as soybean
oil, sunflower oil, coconut oil, palmitic oil, cottonseed oil,
castor oil etc. Further triglycerides are described e.g. in Rompp
Lexikon Chemie, 10.sup.th edition, p. 1320 f., Georg Thieme Verlag.
In a particular preferred embodiment the triglyceride is selected
from the group consisting of soyabean oil, sunflower oil, coconut
oil, palmitic oil, cottonseed oil, and castor oil and mixtures
thereof.
[0012] The inventive method can be applied to all mineral
substrates, which can be a source of dust. In particular, all known
ore pellets can be used, preferably iron-ore pellets are used.
[0013] The amount of dust suppressant usually can be chosen in the
range of from 0.05 to 2.5% by weight per weight of the mineral
substrate. Preferably it is chosen in the range of from 0.1 to 1.5%
by weight per weight of the mineral substrate.
[0014] The dust suppressant can be adhered to at least 50% of the
surface of the mineral substrate. Preferably it is adhered to at
least 80% of the surface of the mineral substrate and more
preferably to at least 90%.
[0015] The first method of the present invention of reducing dust
generation of mineral substrates comprises applying a dust
suppressant to the surface of a mineral substrate having a
temperature in the range of from 150 to 250.degree. C. in an amount
in the range of 0.05 to 2.5% by weight per weight of mineral
substrate, wherein the dust suppressant is a natural or synthetic
triglyceride or a mixture comprising triglycerides.
[0016] Preferably, the mineral substrate is an ore pellet,
preferably an iron-ore pellet.
[0017] Generally, the dust suppressant is of ambient temperature
when applied to the hot pellets, but, if desired, the dust
suppressant may also be of a temperature as high as the temperature
of the hot pellets.
[0018] The dust suppressant may be applied by well-known methods in
the art such as spraying or dipping etc., spraying being
preferred.
[0019] The process can be carried out batch-wise or continuously,
e.g. using a conveyor belt on which the mineral substrates or
pellets are sprayed and then further cooled down or transported to
its storage site.
[0020] Usually the thus treated pellets are cooled down to ambient
temperature and then can be stored, transported or further treated
as desired.
[0021] Also part of the invention is the use of triglycerides as
dust suppressants.
[0022] The second method of the present invention of reducing dust
generation of mineral substrates comprises applying a dust
suppressant to the surface of a mineral substrate having a
temperature in the range of from 100 to 250.degree. C. in an amount
in the range of 0.05 to 2.5% by weight per weight of mineral
substrate, wherein the dust suppressant is applied in the form of a
nonaqueous foam.
[0023] The dust suppressant can be a liquid nonvolatile
hydrocarbon, a nonvolatile polyol, a synthetic oil or a natural or
synthetic triglyceride or mixtures comprising liquid nonvolatile
hydrocarbons, nonvolatile polyol, synthetic oils or triglycerides.
Examples of liquid nonvolatile hydrocarbons are petroleum oil and
petroleum oil products such as mineral oil. Examples of mineral
oils are fuel oils, e.g. gasoline, diesel fuel, heating oil and
kerosene, and lubricating oils. Examples of nonvolatile polyols are
glycol and polyethyleneglycol. An example of a synthetic oil is
silica oil.
[0024] Preferably, the dust suppressant is a natural or synthetic
triglyceride or a mixture comprising triglycerides. More
preferably, the dust suppressant is a natural triglyceride or a
mixture comprising a natural triglyceride. Examples of natural
triglycerides are given above. Most preferably, the dust
suppressant is selected from the group consisting of soyabean oil,
sunflower oil, coconut oil, palmitic oil, cottonseed oil and castor
oil or mixtures thereof.
[0025] Preferably, the mineral substrate has a temperature in the
range of from 150 to 250.degree. C.
[0026] The dust suppressant is preferably applied in the presence
of a surfactant. Examples of suitables surfactants are HCF-740,
which is a mixture of fluorosurfactants and hydrocarbon solvent,
HCF-730, which is a nonionic mixture of silane surfactants,
HCF-720, which is a nonionic mixtuture of silane surfactants and
fluorosurfactants and HCF-710, which is a nonionic mixture of
silane surfactants and sulfonic acids, all sold by Clearwater.
[0027] The surfactant can be used in amounts of 0.2 to 5% by weight
per weight of dust suppressant. Preferably, it is used in amounts
of 0.5 to 2.5% w/w and more preferably in amounts of 1 to 2%
w/w.
[0028] The dust suppressant nonaqueous foam can be applied to the
mineral substrate by dipping the mineral substrate onto the surface
of the foam or by passing it through the foam, which can be either
a static or moving mass. Alternatively, the foam can be applied to
a moving mass of mineral substrate, e.g. at a transfer point on a
conveyor belt.
[0029] Generally, the dust suppressant nonaqueous foam is of
ambient temperature when applied to the hot pellets, but, if
desired, the dust suppressant may also be of a temperature as high
as the temperature of the hot pellets.
[0030] Preferably, the mineral substrate is an ore pellet,
preferably an iron-ore pellet.
[0031] Also part of the invention are dust suppressants in the form
of a nonaqueous oil. Dust suppressant is as defined for the second
method of reducing dust generation of mineral substrates.
[0032] The dust suppressant nonaqueous foam of the present
invention has the advantage that it does not cause spitting when
applied to hot mineral substrates. In addition, it avoids the
enhalation risks connected with spraying a dust suppressant and
also allows an enhanced control of the amount of adhered dust
suppressant and a better distribution of the dust suppressant on
the pellets, when very low amounts of adhered dust suppressant are
desired.
EXAMPLES
Example 1
[0033] 1.1. Preparation of a composition of iron ore pellets and
soyabean oil using sprayed oil 40 plant-fired spherical iron ore
pellets, (diameter from 10 to 14 mm; total weight 133.92 g) are
heated to 200.degree. C. for 1 hour (in order to simulate the
temperature after leaving the furnace). The hot pellets are
transferred to a wire basket and sprayed with soyabean oil, which
is at ambient temperature, six times, the total amount of sprayed
oil being 1.59 g or 1.19% by weight per total weight of the
pellets. The contents of the wire basket are then gently agitated,
by hand, for a few seconds to increase transfer of the oil from
surface to surface. Thereafter the pellets are further cooled down
to ambient temperature without further agitation.
1.2. Dust Measurement
[0034] 35 of the thus treated pellets are then selected, weighed
(111.94 g) and afterwards transferred to a sealable metal tube (6.5
cm diameter by 17.5 cm length). In order to simulate handling of
the pellets the tube and its contents are then tumbled, end-to-end,
in a Roaches "Dye Bath" for 2 hours at ambient temperature.
Thereafter, the contents of the tube are transferred on a 500 .mu.m
sieve, where the fine material is separated from the remaining
pellets. The final weight of these 35 pellets is 110.41 g, and the
fine material (<500 in), is 1.53 g or
(1.53/111.94).times.100=1.37% by weight per weight of the untumbled
pellets.
1.3. Pellet Surface Observation
[0035] A colour change from grey (plant fired pellet) to red
(rustic) is an indication of surface oxidation. This change is
quantifiable from a visual perspective (% surface coverage). The
treatments noted here infer that surface oxidation is reduced when
soyabean oil is used instead of water.
Example 2
[0036] 2.1. Preparation of a composition of iron ore pellets and
sunflower oil using sprayed oil Example 1.1 is repeated, except
that sunflower oil is used instead of soybean oil, the number of
pellets is 35, the total weight of the pellets is 130.79 g and the
amount of oil is 0.21% by weight per weight of pellets.
2.2. Dust Measurement
[0037] Example 1.2. is repeated. The total weight of fine material
is 0.98% by weight per weight of the untumbled pellets.
2.3. Pellet Surface Observation
[0038] A colour change from grey (plant fired pellet) to red
(rustic) is an indication of surface oxidation also infer that
surface oxidation is reduced when sunflower oil is used instead of
water.
Comparative Example 1
[0039] Example 1 is repeated, however the 35 pellets employed
(total weight 129.70 g) are not treated with a dust suppressant.
The percentage of fine material is 5.56% by weight per weight of
untumbled pellets.
Example 3
[0040] 3.1. Preparation of a composition of iron ore pellets and
soybean oil using foamed oil Nitrogen is bubbled in a mixture of
100 mL soyabean oil and 2 mL HCF-740, a mixture of
fluorosurfactants and hydrocarbon solvent, which is sold by
Clearwater in order to generate a stable foam. 35 plant fired
spherical iron ore pellets (6.5 cm diameter by 17.5 cm length) are
heated to 200.degree. C. for 1 hour (in order to simulate the
temperature after leaving the furnace). The hot pellets are
transferred to a wire basket and dipped onto the surface of the
foamed oil, which has ambient temperature. The total amount of oil
being adhered to the pellets is measured and the percentage (weight
adhered oil/weight pellets).times.100 is calculated. The contents
of the wire basket are then gently agitated, by hand, for a few
seconds to increase transfer of the oil from surface to surface.
Thereafter the pellets are further cooled down to ambient
temperature without further agitation.
3.2. Dust Measurement
[0041] The thus treated pellets are weighed and transferred to a
sealable metal tube (6.5 cm diameter by 17.5 cm length). In order
to simulate handling of the pellets the tube and its contents are
then tumbled, end-to-end, in a Roaches "Dye Bath" for 2 hours at
ambient temperature. Thereafter, the contents of the tube are
transferred on a 4 mm sieve, where the fine material (<4 mm) is
separated from the remaining pellets. The weight of the fine
material is measured and the percentage (weight fine
material/weight untumbled pellets).times.100 is calculated.
Example 4
[0042] Preparation of a composition of iron ore pellets and
paraffin oil using foamed oil Example 3 is repeated except that SN
150, a paraffin oil, is used instead of soyabean oil, and 1 mL
HCF-740 instead of 2 mL.
Comparative Example 2
[0043] Example 3 is repeated, however the 35 pellets employed are
not treated with a dust suppressant. TABLE-US-00001 TABLE 1 Dust
measurement and pellet surface observation of iron ore pellets
treated with foamed oils. Fine material Adhered oil [%(w fine [%(w
oil/w material/w Pellet surface Example pellet)] untumbled pellet)]
observation Comparative 0 5.72 Red surface example 2 Example 3 0.22
1.54 Gray surface Example 3 0.26 1.10 Gray surface Example 3 0.29
0.77 Gray surface Example 4 0.29 1.4 Gray surface Example 4 0.30
1.71 Gray surface Example 4 0.31 1.56 Gray surface Example 4 0.37
1.47 Gray surface Example 4 0.46 1.27 Gray surface Example 4 0.49
1.47 Gray surface Example 4 0.58 0.90 Gray surface Example 4 1.04
0.91 Gray surface
[0044] The results show that oils can be successfully applied as a
foam to reduce dust generation and surface oxidation of iron ore
pellets. Soyabean oil was more effective than paraffin oil at
equivalent dosages.
* * * * *