Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
I 178042
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1 This invention relates to surface treatment of
2 particulate solids to prevent water-wetted surfaces from
3 freezing together at water-freezing temperatures.
S }3ackground of the Invention
When the surface moisture on particulate solids
7 freezes, the ice acts as a powerful adhesive holding the
8 particles together in a mass, e.g., coal with as little as
9 4 percent moisture will, when frozen, cohere so strongly as
to require special handling to break up the frozen mass.
11 It thus becomes difficult to unload or dump railway cars,
12 trucks and other conveyances used to transport coal, miner-
13 al ores and other finelv divided solids. It also makes
14 difficult the movement of coal out of outdoor coal storage
piles in a condition for fuel or other use. Unloading fro-
` 16 zen coal from railroad cars is-time oonsumlng,can result in
17 blocked dump chutes and can often leave as much as 30 to 6~
18 tons of coal in the car. Various techniques such as vibra-
~9 tion, steam lances, fires under the cars, infrared heating
in warming sheds and even dynamiting have been tried to un-
.21 load frozen cars. Another approach is to chemically modify
22 the environment contiguous with the particulate sur,aces.
23 Sodium chloride and calcium chloride salts have been added
24 to moist coal as it is being loaded with some degree of
success toward reducing the freezing problem. However,
26 such salts contribute to the corrosion of all equipment
27 with which the solids come in contact and are detrimental
28 to the coking process when used with coking coal. Oil has
29 been used to freeze-proof coal with questionable effective-
3G ness. Oil soluble surfactants have been added to the oil
- 31 but with questionable results. Ethylene glycol has been em-
32 ployed, but although successful, the cost of treatment has
33 been very high.
34 Referring now to the patent literature there is
35 included:
36 U.S. Pat. No. 4,117,214. A composition for reduc-
'
~'
0 4 2
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1 ing the strength of ice featuring (1) a water-soluble
2 Polyhydroxy compound of a monoalkylether and (2) a wat-
3 er soluble organic nonvolatile compound having a hydrophi-
4 lic group such as amine, carboxyl or carboxylate groups in
an amount to provide an effective amount, e.g., on the or-
6 der of about 0.25-5 weight percent, of (~) plus (2) based
7 on the weight of water;
8 U. S. Pat. No. 3,298,804 is directed to the pre-
g vention of freezing together of coal particles. That is
10 accomplished with a composition of hydrocarbon and a given
11 class of surface-active compounds;
12 U. S. Pat. No. 3,794,472,treats coal with an e-
13 mulsion to prevent freezing of the coal; and,
14 U. S. Pat. No. 4,225,317 treats the coal by
15 spraying coal particles prior ,O freezing with an effect-
16 ive amount of a hydrocarbon liquid solution of a nonionic
17 surfactant havingan HLB between 9.5 and 11.0
18
19 Summary of the Invention
A method for treating particulate solids such as
21 coal having surface moisture has been discovered which
22 comprises spraying such solids with a minor but at least
23 effective amount of a hydrocarbon liquid solution of a mix-
24 ture of an anionic surfactant, i.e., a water soluble salt
25 of an alkyl aryl sulfonic acid, and a nonionic surfactant,
26 said mixture having an HLB of at least 12. The amount of
27 anionic and nonionic surfactants in the hydrocarbon liauid
28 typically is between 0.5 to 50 ~ by weight.
29 While the invention has utility in the treatment
30 of a variety of particulate solids having surface moisture
31 to prevent sticking due to freezing, its greatest useful-
32 ness is found in the treatment of coal particles during
33 cold winter weather.
34
DETAILED DESCRIPTION OF THE INVENTION
36 As previously indicated, the mixture of anionic
37 surfactant and nonionic surfactant should have an ~LB of
- 1 178~42
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1 at least 12. HLB refers to the so-called Atlas ~LB Sys-
2 tem which is described in the publication en_itled, The At-
3 las HLB System, 4th Printing, Published by Atlas Chemical
4 Industries, 1963.
The preferred surfactant mixtures of the inven-
6 tion are in the middle of the HLB scale and, therefore,
7 they tend to have both hydrophilic and hydrophobic proper-
8 ties. The surfactants may be further defined in that they
9 are capable of forming either oil-in-water or water-in-oil
10 emulsions depending upon the particular ratio of water to
11 oil being emulsified. Thus, if there is a preponderance of
12 water, an oil-in-water emulsion would be fo~med; whereas,if
13 oil is in the preponderance, then a water-in-oil emulsion
14 would be formed.
15 The Anionic Surfactant
16
The anionic surfactant of the mixture according
to this invention can be generally considered as a salt of
an alkyl aryl sulfonic acid of the general formula
tR)r. Ar S03M wherein (R) represents 1 to 5 alkyl
groups which may be the same or different and at least one
alkyl group containing from 8 to 16 carbon atoms, n is an
integer of from 1 to 5, Ar represents an aryl group which
may be further substituted and M is an organic or inorganic
cation. M may be an alkali metal such as sodium or potassi-
um or a nitrogenous base such as a quaternary ammonium or
quaternary amino which may for preference be ethoxylated.
It has been found that excellent results occur when one al-
` kyl group contains from 10 to 14, optimally about 12, car-bon atoms. Preferred is the monoethanolamine salt of do-
decylbenzene sulfonic acid.
31
32 The Nonionic Surfactant
33 The nonionic surfactant is generally of the class
34 of ethoxylated alkylphenols such as ethoxylated octyl phe-
nols, ethoxylated nonyl phenols and ethoxylated dinonyl phe-
36 nols. The preferred nonionic surfactant is dinonyl phenol
37 which has been re~cted with 9 moles of ethylene oxide.
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1 17804~
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1 The weight ratio of the freeze conditioning comb-
2 ination of a~ionic surfactant to nonionic surfactant gen-
3 erally is within the range of 10:1 to 1:4. Preferably the
4 range is 5:1 to 1:2, and most preferably about 10:3.
6 The hydrocarbon liquid
7 The hydrocarbon liquid acts as a carrier for the
8 surfactant mixture which allows a liquid formulation to be
9 produced. It further is emulsified with the water coated
around the particles to be treated. While any normally li-
11 quid hydrocarbon may be employed, it is preferred to use a
12 predominantly aliphatic hydrocarbon oil such as No. 2 die-
13 sel fuel oil. Other organic liquids that can be used are
14 naphthas, kerosenes, pure hydrocarbon liquids such as white
oil, and the like.
16 In certain instances, it is beneficial if from
17 0.5-10% by weight water is added to the oil which acts as
18 a cosolvent for the surfactants, thus allowing more of the
19 surfactants to be dissolved in the oil. A typical composi-
tion of the invention, Composition X, is 6.4 weight ~ di-
21 nonyl phenol reacted with 9 moles of ethylene oxide, 19.9
22 weight ~ of the monoethanolamine salt of dodecylbenzene sul-
23 fonic acid and 73.7 weight % of No. 2 diesel fuel oil.
24
Cosolvent
26 Under certain circumstances, par~icularly when the
27 freeze conditioning agent is exposed to low temperatures, up to
2~ 10, generally 2 to 4, weight percent of a cosolvent is in-
29 corporated to prevent low temperature separation of the an-
ionic and/or nonionic surfactant. The cosolvents are of t~e
31 class of alkylene glycol monoalkyl ethers,C2 to Cs alkanols
32 and mixtures thereof. Representative cosolvents include
ethers such as ethylene glycol monopropyl ether, ethyl-
34 ene glycol monoethyl ether,ethylene glycol monomethyl ether,
ethylene glycol monobutyl ether, diethylene glycol mono-
36 methyl ether, diethylene glycol monoethyl ether, diethyl-
37 ene glycol n-butyl ether, propylene glycol monomethyl eth-
1 1~8042
1 er, dipropylene slycol monomethyl ether and tripropylene
2 glycol monomethyl ether, and alkanols which include
3 straight and branched chain members such as ethanol, pro-
4 panol, butanol, and pentanol. Of the alkanols, isopropyl
alcohol is preferred. Of the ethers, ethylene glycol mono-
6 butyl ether is preferred.
7 Evaluation of the Invention
8 In order to evaluate the invention, the follow-
g ing test method was used:
Coal containing 15-20 wt.% total moisture is
11 sized through a 0.5-inch screen to remove large coal part-
12 icles. Ten pounds of this coal is put in a tumbling de-
13 vice(cement mixer). The experimental freeze conditioning
14 agents are sprayed onto the coal at a rate of 1-6 pints/ton
while it is being tumbled. After complete mixing the
16 treated coal is transferred to polyethylene bags and tight-
17 ly sealed.
18 Cylindrical samples of treated coal are prepared
19 by placing 150 g of treated coal in 2-inch I.D. (internal
diameter) sections of polyvinyl chloride (PVC) pipe and com-
21 pacting the samplesby compressing both ends (sealed with
22 heavy plastic film and ~umberlO rubber stoppers). These sam-
23 ples are then placeain a freezer maintained at 0F for a mini-
24 mum of 20 hours. The froæen coal is then removed from each
PVC mold and heldat0F for an additional 24 hours.
26 The compressive strength of each sample or ~rozen
27 coal is measured using an Instro ~Testing device. The In-
28 stron tester was modif`ed to ensure 0F environment during
29 the compressive strength measurement.
31 Examples 1-5
32 Monterey No. 1 coal was subjected to freeze con-
33 ditioning treatment by four hydrocarbon based formulations.
34 The utility of each system was evaluated according to the
above test at a treat rate of 4 pints per ton, with the
36 following results:
,:
~< ~R~ p~ n7 f }
,,~
1 1~8042
1 ExamDle Hydrocarbon Crush Strength
:
2 Based System psi (average of 6 tests
4 1 No. 2 diesel fuel oil 175+8
6 2 6.4~ dinonylphenol ethoxylated 159+25
7 with 10 moles of ethylene ox-
8 I ide, balance No. 2 diesel
9 fuel oil
11 3 26.6% dinonylphenol ethoxylated 134+17
12 with 10 moles of ethylene ox-
13 ide, balance ~o. 2 diesel
14 fuel oil
16 4 20 wt.% dodecylbenzene sulfonic 143+18
17 acid-monoethanol amine salt,
18 balance No. 2 diesel fuel oil
!; 1 9
20 5 Composition X 113+14
21
~ 22 ~he test results significantly indicate;tbat: a
. 23 relatively low concentration of a nonionic surfactant in
.' 24 fuel oil does not markedly reduce the strength of frozen
`. 25 coal relative to coal treated with fuel oil alone; a rela-
.. 26 tively high concentration of an anionic surfactant in fuel
27 oil only marginally reduces the strength of said frozen
28 coal; and, surprisingly, the combination of said low con-
~ 29 centration of nonionic surfactant and said high concentra-
j 30 tion of an anionic surfactant in fuel oil markedly reduced
.. 31 the cohesive strength of frozen coal.
. 32
'. 33 The invention in its broader aspect is not lim-
34 ited to the specific details shown and described, and de-
partures may be made from such details without departing
.~ 36 from the principles of the invention and without sacrific-
37 ing its chief advantages.
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