U.S. patent application number 09/751533 was filed with the patent office on 2001-05-10 for high-temperature, water-based lubricant and process for making the same.
Invention is credited to Castro, Michael A., Skiles, Kenneth, Zaleski, Peter L..
Application Number | 20010001096 09/751533 |
Document ID | / |
Family ID | 22725132 |
Filed Date | 2001-05-10 |
United States Patent
Application |
20010001096 |
Kind Code |
A1 |
Skiles, Kenneth ; et
al. |
May 10, 2001 |
High-temperature, water-based lubricant and process for making the
same
Abstract
A high-temperature lubricant comprising a water-base and minor
effective amounts of borate, dextrin, graphite, xanthan gum, and an
organic preservative. A powder for preparing a water-based high
temperature lubricant is disclosed in which the powder comprises
graphite and minor effective amounts of borate, dextrin, and
xanthan gum. A continuous process for making the lubricant is also
disclosed.
Inventors: |
Skiles, Kenneth; (Chicago,
IL) ; Zaleski, Peter L.; (Willow Springs, IL)
; Castro, Michael A.; (Aurora, IL) |
Correspondence
Address: |
COOK, ALEX, MCFARRON, MANZO, CUMMINGS & MEHLER LTD
SUITE 2850
200 WEST ADAMS STREET
CHICAGO
IL
60606
US
|
Family ID: |
22725132 |
Appl. No.: |
09/751533 |
Filed: |
December 29, 2000 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09751533 |
Dec 29, 2000 |
|
|
|
09196372 |
Nov 19, 1998 |
|
|
|
6169059 |
|
|
|
|
Current U.S.
Class: |
508/115 ;
106/38.23; 508/125; 508/126; 508/155; 508/156 |
Current CPC
Class: |
C10M 129/08 20130101;
C10N 2040/32 20130101; C10M 173/02 20130101; C10N 2040/36 20130101;
C10M 2209/12 20130101; C10N 2050/01 20200501; C10M 2201/087
20130101; C10N 2040/40 20200501; C10N 2040/44 20200501; C10N
2040/00 20130101; C10N 2040/30 20130101; C10N 2040/34 20130101;
C10N 2040/38 20200501; C10M 2201/02 20130101; C10M 2201/042
20130101; C10M 2201/041 20130101; C10N 2040/42 20200501; C10M
145/40 20130101; C10M 125/02 20130101; C10N 2040/50 20200501; C10M
2207/022 20130101; C10M 125/26 20130101; C10M 173/02 20130101; C10M
125/02 20130101; C10M 125/26 20130101; C10M 129/08 20130101; C10M
145/40 20130101 |
Class at
Publication: |
508/115 ;
508/125; 508/126; 508/155; 508/156; 106/38.23 |
International
Class: |
C10M 173/02; C10M
125/02; C10M 125/26; C10M 141/02 |
Claims
That which is claimed:
1. A high-temperature lubricant comprising a water base and minor
effective amounts of borate, dextrin, graphite, xanthan gum, and an
organic preservative.
2. A high-temperature lubricant comprising: between about 60 wt %
and 80 wt % water; between about 0.1 wt % and 1.0 wt % of borate;
between about 5.0 wt % and 15.0 wt % of dextrin; between about 10.0
wt % and 30.0 wt % graphite: between about 0.5 wt % and 1.0 wt %
xanthan gum; and between about 0.1 wt % and 0.3 wt % of an organic
preservative.
3. The lubricant of claim 2 comprising approximately 69.8 wt %
water; approximately 0.5 wt % borate; approximately 10.0 wt %
dextrin; approximately 19.3 wt % graphite; approximately 19.3 wt %
graphite; approximately 0.2 wt % xanthan gum; and approximately 0.2
wt % of an organic preservative.
4. The lubricant of claim 2 or 3 wherein the preservative is a 50%
solution of glutaraldehyde; the borate is a 10 mole powdered borax;
the dextrin is between 95% and 100% soluble in water; the graphite
has an average particular size of 30 microns; and the xanthan gum
has an average particle size of 175 microns.
5. A powder for preparing a water-based, high-temperature lubricant
comprising graphite and minor effective amounts of borate, dextrin,
and xanthan gum.
6. A powder for preparing a water-based, high-temperature lubricant
comprising: between about 0.5 wt % and 2.0 wt % of borate; between
about 31.0 wt % and 34.0 wt % of dextrin; between about 63.0 wt %
and 66.0 wt % graphite; and between about 0.5 wt % and 1.3 wt %
xanthan gum.
7. The powder of claim 6 comprising approximately 1.7 wt % borate;
approximately 33.3 wt % dextrin; approximately 64.3 wt % graphite;
and approximately 0.7 wt % xanthan gum.
8. The powder of claim 6 or 7 wherein the borate is a 10 mole
powered borax; the dextrin is between 95 and 100% soluble in water;
the graphite has an average particle size of approximately 30
microns; and the xanthan gum has an average particle size of
approximately 175 microns.
9. A process for continuously making a water-based lubricant
containing suspended graphite comprising: supplying water at a
pre-determined and controllable rate by means of a first metering
pump; supplying a preservative at a pre-determined and
controllable-rate by means of a second metering pump; combining the
water and preservative and injecting the combined water and
preservative into a powder injector; introducing pre-determined
amounts of graphite, dextrin, borax, and xanthan gum into the
powder injector to combine them with the water and preservative;
pumping the water, preservative, graphite, dextrin, borax and
xanthan gum into a high shear mixer; and introducing the resulting
suspension into a container.
10. The process of claim 9 wherein the graphite, dextrin, borax,
and xanthan gum are introduced separately into the powder injector
by means of separate metering screw feeders.
11. The process of claim 9 wherein the graphite, dextrin, borax,
and xanthan gum are combined and introduced into the powder
injector by means of a single metering screw feeder.
12. A continuous process for making a lubricating suspension
comprising: supplying a liquid selected from the group consisting
of water, oil, hydrocarbons and solvents at a pre-determined and
controllable rate by means of a metering pump and injecting the
liquid into a powder injector; introducing pre-determined amounts
of a lubricating particles from the group consisting of graphite,
borax, boron nitride, molybdenum disulfide and talc into the powder
injector to combine the powder with the liquid; pumping the liquid
and lubricating powder into a high shear mixer; and introducing the
resulting suspension into a container.
Description
1. This invention relates to a high-temperature, water-based
lubricant and, more particularly, to a water-based graphite
suspension useful in metal and mineral forming applications and a
continuous process for making the same.
BACKGROUND OF THE INVENTION
2. Many metal-forming operations are performed at high temperature
using dies, molds and the like. In such operations, lubricants
and/or release agents are often used to reduce wear on the dies or
molds and to prevent-the resulting metal products from sticking to
the dies or molds.
3. For example, a fluidized iron ore reduction (FIOR) processing
plant includes a hot briquetting assembly in which direct reduced
iron (DRI) briquettes are formed using iron ore fines as a feed
stock. Such a process is described in U.S. Pat. No. 5,082,251 to
Whipp, which is herein incorporated by reference. The briquettes
are resistant to oxidation during storage and shipping and can be
easily handled and charged in steel-making operations. In the
briquetting process, reduced iron ore fines, lumps, or pellets are
typically metered from a storage drum into a briquetting machine,
such as those generally described in U.S. Pat. No. 3,988,095 to
Mersh et al. and U.K. Patent No. 1,272,617, both of which are
incorporated by reference.
4. In a briquetting machine, the material to be briquetted is drawn
in by rolls rotating in opposite directions and pressed into
briquettes at the nip between the pair of rolls by means of
briquette-shape molds or dies embedded in the rolls. The iron
fines, lumps, or pellets enter a feed drum on the top of the
briquetting machine and are forced between the two counter-rotating
rolls by a feed screw. The rolls are equipped with briquette-shaped
molds which compress the fines into briquettes. The compaction is
achieved by a combination of the high pressure between the rolls
and the high temperature of the iron feed (approximately
900.degree. C.), which makes them more compressible. Roll
temperatures range typically between approximately 200.degree. to
450.degree. C.
5. Pressure is maintained by means of hydraulic cylinders that
exert force against one of the two rollers, one roller being fixed
and the other being allowed to move in order to prevent breakage
should a piece of metal pass through the machine. The briquettes
leave the machine in a web and then are separated into individual
briquettes. The briquettes may then be quenched in a water-filled
tank and discharged onto a conveyor where the moisture is driven
off by the heat remaining in the briquettes.
6. In the past, dry powdered graphite has been used as a release
agent on the briquette rolls used for the DRI hot briquetting.
However, the dry graphite has not proved satisfactory in that it
does not consistently and uniformly stick to the rolls, resulting
in inefficient application of the graphite and high loss of the
graphite during the application, and a concomitant graphite dust
control problem. Further, the dry graphite is also relatively
abrasive, thus resulting in higher wear on the rolls than is
desired.
7. Accordingly, it is an object of this invention to provide a
metal working lubricant and release agent that will both minimize
wear on the forming rolls and facilitate the release of the formed
metal product.
8. It is a further object to provide such a lubricant that can be
efficiently applied to the rolls.
9. It is a still further object to provide a continuous process for
making such a lubricant.
SUMMARY OF THE INVENTION
10. These objects, as well as others which will become apparent
upon reference to the following detailed description are
accomplished by a high-temperature lubricant comprising a
water-base and minor effective amounts of borate, dextrin,
graphite, xanthan gum, and an organic preservative. Additionally, a
powder for preparing a water-based, high-temperature lubricant is
disclosed which comprises graphite and minor effective amounts of
borate, dextrin, and xanthan gum. Ranges for the components and
preferred embodiments are disclosed for both the liquid lubricant
and the powder precursor, as well as processes for making the
lubricant.
BRIEF DESCRIPTION OF THE DRAWINGS
11. FIG. 1 is a schematic representation of a continuous process
for making the lubricant of the present invention.
12. FIG. 2 is an alternative method to that shown in FIG. 1 for
making the lubricant of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
13. The high-temperature lubricant according to the present
invention is exemplified by the following examples showing ranges
for the various components expressed as a percent of the total
weight.
1 TABLE 1 Component Low (wt %) High (wt %) Tap Water 60.0 80.0
Preservative 0.1 0.3 Borax 0.1 1.0 Dextrin 5.0 15.0 Graphite 10.0
30.0 Xanthan Gum 0.1 0.4
14. The tap water can be any water of a quality suitable for
industrial applications, and without harmful impurities. Its
purpose is to carry the solid materials to the work zone and to
lower the temperature of the die due to its evaporation.
15. The preservative can be any material classified as a
preservative, such as a biocide, which is suitable for metal
working fluids, paints, coatings, and/or suspensions. Its purposes
is to protect the organic components of the suspension from
micro-biological decomposition. Preferably, the preservative is a
50% solution of glutaraldehyde, such as Ucarcide 250 preservative
available from Union Carbide or Ucar Carbon Company.
16. The borax may be any material from the inorganic borate
chemical family and is preferably sodium tetraborate decahydrate,
10 mole powder. Its purpose is to control the pH of the suspension
during storage and handling and to enhance lubricity. This material
may be obtained from U.S. Borax Co.
17. The dextrin includes all materials from the dextrin chemical
family, and is preferably greater than 90% soluble in water. With
heat, dextrin cooks into a tacky adhesive and finally decomposes
into carbon, gases and ash. Stadex 126 dextrin available from the
Staley Co. has provided satisfactory results.
18. The graphite may be any material from the graphite chemical
family, both natural and synthetic, and preferably has an average
particle size of 30 microns, with a loss on ignition (LOI) of
greater than or equal to 70%, and more preferably 95% and above.
The graphite prevents adhesion between the iron briquettes and the
briquette mold. In practice, 5033 synthetic graphite from Superior
Graphite Co. has provided excellent results.
19. The xanthan gum may be any materials for xanthan gum chemical
family and preferably has a average particle size of 175 microns.
Xanthan gum is a suspension agent and prevents the solid particles
from settling. The xanthan gum is available from Kelco under the
trademark Kelzan.
20. The preferred composition for the lubricant is as follows:
2 TABLE 2 Component Wt % Tap Water 69.8 Glutaraldehyde, 50% 0.2
Solution Borax, 10 mole powder 0.5 Dextrin, 95-100% water 10
soluble Synthetic Graphite 19.3 Xanthan Gum 0.2
21. A powder for preparing a water-based, high temperature
lubricant according to the present invention is set forth in the
following Table 3, showing ranges for the various components as a
percent of the total weight.
3 TABLE 3 Component Low (wt %) High (wt %) Borax 0.5 2.0 Dextrin
31.0 34.0 Graphite 63.0 66.0 Xanthan Gum 0.5 1.0
22. The preferred composition for the powder is set forth in Table
4.
4 TABLE 4 Components Wt % Borax, 10 mole powder 1.7 Dextrin,
95-100% water soluble 33.3 Synthetic Graphite 64.3 Xanthan Gum
0.7
23. The lubricant may be made in a batch process using a tank and a
propeller-type mixer. Preferably, the suspension is manufactured in
a automated, continuous process, which helps to control costs
through labor minimization, and the elimination of multiple
start-up and shut down procedures.
24. In one such continuous process, the six raw materials, (the
water, preservative, borax, dextrin, graphite and xanthan gum) are
used. With reference to FIG. 1, there is seen a schematic
representation of the process generally designated 10. The water is
collected in a holding tank 12 and is pumped from the holding tank
12 by a metering pump 14 to a liquid injection point 16. A drum 18
containing the preservative is attached to a metering pump 20, and
the preservative is combined with the water at the liquid injection
point 16. The combined stream of preservative and water is fed into
a powder injector 22. The graphite, dextrin, borax and xanthan gum
are automatically unloaded from bulk bags, or similar bulk
containers by screw conveyors 24a, 24b, 24c, and 24d which are
associated with the feeder hoppers 26a, 26b, 26c, and 26d,
respectively. The screw conveyors automatically meter the
respective ingredients into the powder injector 22, which combines
the water/preservative flow with the other ingredients with a
minimum of air entrapment. The suspension is then transported from
the powder injector 22 by a pump 28 to an in-line high shear mixer
30, which completely wets the insoluble solid particles and
completely dissolves the soluble solids into the fluid. The
suspension is then piped into a container 32, which may be, e.g., a
tank truck or large capacity tank.
25. The ratio of the preservative to the water is controlled by the
metering pumps 20, 14, while the ratio of the graphite, dextrin,
borax, and xanthan gum is controlled by each component's screw
feeder rate and the resulting pump rate from the water/preservative
combination. The rates for the pumps 14, 20 and the screw feeders
24a, 24b, 24c, and 24d are controlled by computerized electronic
motor frequency controls, which are well known. This general
process may also be advantageously used for continuously making
lubricating suspensions in which the lubricating particles are not
graphite, but are other solid lubricants, e.g., borax, boron
nitride, molybdenum disulfide, talc, etc. and the liquid in which
the lubricating particles are suspended is either water, oil, or
other hydrocarbons and/or solvents.
26. In an alternative process, the dry ingredients (the graphite,
dextrin, borax, and xanthan gum) are precombined and added to the
water/preservative at the powder injector 22 from a single screw
conveyor 34 and feeder hopper 36 (see, FIG. 2). In order to prepare
the powder, a powder blender (not shown) is required. All the
components are added to the blender and are blended together until
a uniform mixture is achieved.
27. The water-based, suspended graphite lubricant described above
has found particular utility in the hot briquetting of iron used in
direct reduced iron processing plants. Application of the
water-suspended lubricant directly to the dies by spraying has
resulted in energy savings due to the reduction in torque energy
needed to rotate the briquetting rolls and has extended roll life
by reducing the friction between the rolls and the briquettes. The
extended roll life has also increased production due to less down
time and maintenance.
28. Spraying has proved to be an efficient method of applying the
lubricant to the rolls, with the graphite lubricant binding to the
roll surface after the carrier evaporates. Because the lubricant is
water based, the evaporation of the carrier is environmentally
safe. Further, the use of the water based suspension has reduced
the graphite dust control problems associated with the use of dry
powered graphite.
29. While the invention has been described as being particularly
useful for the hot briquetting process, it should also prove
equally useful as a die lubricant or mold release in forging and
other hot metal and mineral forming operations.
* * * * *