CA1144541A - Lower alkanoic acid derivatives of a diethanolamine/fatty acid condensate - Google Patents
Lower alkanoic acid derivatives of a diethanolamine/fatty acid condensateInfo
- Publication number
- CA1144541A CA1144541A CA000369032A CA369032A CA1144541A CA 1144541 A CA1144541 A CA 1144541A CA 000369032 A CA000369032 A CA 000369032A CA 369032 A CA369032 A CA 369032A CA 1144541 A CA1144541 A CA 1144541A
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- Prior art keywords
- coal
- fatty acid
- acid
- composition
- flotation
- Prior art date
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
- B03D1/00—Flotation
- B03D1/001—Flotation agents
- B03D1/004—Organic compounds
- B03D1/01—Organic compounds containing nitrogen
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- Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
Abstract
ABSTRACT
The title compositions exhibit superior effi-cacy as conditioners in the flotation of coal. These com-positions are prepared by condensing diethanolamine with a C10-C24 fatty acid in a molar ratio of 1:2 and then introducing one-half the equimolar amount, relative to the condensate, of C1-C4 alkanoic acid.
The title compositions exhibit superior effi-cacy as conditioners in the flotation of coal. These com-positions are prepared by condensing diethanolamine with a C10-C24 fatty acid in a molar ratio of 1:2 and then introducing one-half the equimolar amount, relative to the condensate, of C1-C4 alkanoic acid.
Description
LOWER ALKANOIC ACID
DERIVATIVES OF A DIETHANOLAMINE/FATTY
ACID CONDENSATE s This invention is directed to lower alkanoic acid derivatives of a diethanolamine-fatty acid conden-sate that are useful in the froth flotation of coal.
The condensation products of alkanolamines and higher organic acids are known. U.S. Patent 2,173,9~9, granted to Kritchevsky, September 26, 1939, discloses that fatty alkanolamides can be employed in ore flotation, par-ticularly in a slightly acidic medium. U.S. Patent
DERIVATIVES OF A DIETHANOLAMINE/FATTY
ACID CONDENSATE s This invention is directed to lower alkanoic acid derivatives of a diethanolamine-fatty acid conden-sate that are useful in the froth flotation of coal.
The condensation products of alkanolamines and higher organic acids are known. U.S. Patent 2,173,9~9, granted to Kritchevsky, September 26, 1939, discloses that fatty alkanolamides can be employed in ore flotation, par-ticularly in a slightly acidic medium. U.S. Patent
2,609,931, granted to Rodman et al., September 9, 1952, teaches that mono fatty amide derivatives of N,N-dihydroxy-alkylethylenediamine are useful filtering agents; the ace-tate salt of these compounds is alleged in column 6, lines 43-47 to be particularly useful in some applications. U.S.
~atent 2,993,919 describes the use of acid salts of mix-tures of fatty alkanolamides and diethanolamine in oreflotation.
~ .
28, 735-F
' ~ , 114~541 The present invention is a composition of matter comprising the reaction product of two components:
~1) a condensation product of diethanolamine and a C10-C24 fatty acid condensed in a mole ratio S of about 1:2; and (~) about one-half equimolar amount of a Cl-C4 monocarboxylic acid or mixtures thereof, based on the moles of condensate.
The condensation products of diethanolamine and fatty acids are known in the art, but generally an excess of at least an equimolar amount of diethanolamine relative to fatty acid is employed in preparing these condensates. The term "condensation product" is employed herein to distinguish this product from the ammonium salt of the fatty acid produced at lower reaction temperatures.
The condensation product in the subject novel composition i6 prepared using a ratio of from about 1.8 to 2.2 moles of fatty ~cid for each mole of ~iethanolamine.
The fatty acid condensed with diethanolamine can operably be a fatty acid having a saturated or unsat-urated alkyl group. The fatty acid can suitably bear hydroxyl substituents on its al~:yl portion, but such sub-~titution does not impart any substantial advantage. Fatty acids such as oleic, lauric, linoleic, palmitic, stearic, myristic, and mixtures thereof are operable. The esters correspondinq to ~he fatty acids, such as glycerides, are also operable, as they produce the same condensate, but are less preferred. For reasons of economy, it is pre-ferred to use crude mixtures of fatty acids with minor amounts of rosin acids, lignin and unsaponifiable mate-rial, such as tall oil, coconut oil, pa~m oil, palm ker-nal oil, cottonseed oil, linseed oil, olive oil, peanot 28,735-F - -2-11~4541 , oil and fish oil. Tall oil and tall oil heads are espe-cially preferred mixtures of fatty acids, are well-known compositions, and are described in the Kirk-Othmer, EncY-cloPedia of Chemical Technoloqy, 2nd Ed., Vol. 19, pp.
614-629 (1969).
The preferred crude mixtures of fatty acids do not have a single molecular weight. For the purposes of this description one mole of such a crude fatty acid contains fractional moles of constituent fatty acids totaling one mole.
The fatty acid or corresponding ester and the diethanolamine can be readily reacted by mixing these reactants and heating until substantially complete con-densation has taken place, as indicated by the water dis-tilled overhead or by infrared spectrophotometric anal-ysis of the condensation product. Generally, a reaction temperature of from about 120~C to about 250C is oper-able. The condensation product contains predominantly an amide ester with a remaining amount of principally amide, and amide diester derivatives.
The subject composition is prepared by adding the water-soluble lower alkanoic acids, i.e., formic, ace-tic, propionic or butyric acids or a mixture thereof, to the above-described condensation product at a temperature which does not effect substantial additional condensation.
The te~perature during addition of this lower alkanoic acid is operably from about 10C to about 100C, prefer-ably from about 20C to about 50C. Substantially all of this lower alkanoic acid added to the composition can be titrated with an alkali metal hydroxide, which suggests 28,735-F _3_ . . , -114~541 that a hydrogen-bonded acid complex is formed and not a salt. Analysis of infrared and proton magnetic resonance spectroscopy supports the theory that the resulting com-position is an acid complex, but this structural eluci-dation is not definitive and the instant composition isnot limited thereby.
The subject compositions have shown excep-tional activity as conditioners in the froth flotation of coal. Froth flotation of coal is used in the art to beneficiate finely-divided coal. The use of condensates of alkanolamines and fatty acids and salts or other acid derivatives of these condensates as a conditioner in coal flotation is taught by W. C. Meyer, R. D. Hansen and R. E.
Hefner, Jr. in Canadian Applicatin Serial No. 344,307, filed January 24, 1980 for "Conditioner for Flotation of Coal". The relevant portions of this application further describe the utility of the instant compositions in the flotati~n of coal.
The coal to be floated can suitably be anthra-cite, bituminous or subbituminous. The instant composi-tion is preferably employed to float coal which cannot ~e floated with conventional frothers alone, and is particu-larly effective in the flotation of bituminous coal of intermediate or low grade, where the surface of the coal is oxidized to an extent which significantly impedes the flotation of the coal using conventi~nal agents.
The size of the coal particles to be separated by flotation is important because generally particles lar-ser than about 28 mesh (U.S. Sieve Size) are difficult to float. In typical operations, coal particles larger than 28 mesh, preferably larger than 100 mesh, are separated 28,735-F -4-1~144541 from both the inert material mined therewith and more finely divided coal ~y gravimetric separation techniques.
However, if a substantial fraction of the coal in the flotation feed comprises particles larger than 28 mesh, S it is desirable that the feed be comminuted further prior to flotation.
The sized coal flotation feed optionally is first washed and then mixed with sufficient water to pre-pare an agueous slurry having a solids concentration which promotes rapid flotation. Generally, a solids concentra-tion between a~out 2 to about 20 weight percent solids, more preferably from about 5 to about 10 weight percent, is preferred. The aqueous coal slurry is advantageously conditioned with the instant composition, a frother, fuel oil and other adjuvants, such as activators, dispersing reagents, depressing reagents and conditioning reagents, by mixing with the slurry in a n-anner kno~n to the art.
Generally, for coal that is difficult to float, it is advantageous to contact with mixing the coal slurry with the conditioner and fuel oil for a period of time prior to flotation, so as to effect intimate contact of the conditioner and fuel oil with substantially all of the coal. Where the aqueous coal slurry is prepared in a container distinct from the flotation cell and then is conveyed to the flotation cell through conduits, the desired intimate contact can conveniently be attained by introducing the conditioner and fuel oil to the slurry upstream from the flotation cell. The frother, however, should be introduced to the slurry shortly
~atent 2,993,919 describes the use of acid salts of mix-tures of fatty alkanolamides and diethanolamine in oreflotation.
~ .
28, 735-F
' ~ , 114~541 The present invention is a composition of matter comprising the reaction product of two components:
~1) a condensation product of diethanolamine and a C10-C24 fatty acid condensed in a mole ratio S of about 1:2; and (~) about one-half equimolar amount of a Cl-C4 monocarboxylic acid or mixtures thereof, based on the moles of condensate.
The condensation products of diethanolamine and fatty acids are known in the art, but generally an excess of at least an equimolar amount of diethanolamine relative to fatty acid is employed in preparing these condensates. The term "condensation product" is employed herein to distinguish this product from the ammonium salt of the fatty acid produced at lower reaction temperatures.
The condensation product in the subject novel composition i6 prepared using a ratio of from about 1.8 to 2.2 moles of fatty ~cid for each mole of ~iethanolamine.
The fatty acid condensed with diethanolamine can operably be a fatty acid having a saturated or unsat-urated alkyl group. The fatty acid can suitably bear hydroxyl substituents on its al~:yl portion, but such sub-~titution does not impart any substantial advantage. Fatty acids such as oleic, lauric, linoleic, palmitic, stearic, myristic, and mixtures thereof are operable. The esters correspondinq to ~he fatty acids, such as glycerides, are also operable, as they produce the same condensate, but are less preferred. For reasons of economy, it is pre-ferred to use crude mixtures of fatty acids with minor amounts of rosin acids, lignin and unsaponifiable mate-rial, such as tall oil, coconut oil, pa~m oil, palm ker-nal oil, cottonseed oil, linseed oil, olive oil, peanot 28,735-F - -2-11~4541 , oil and fish oil. Tall oil and tall oil heads are espe-cially preferred mixtures of fatty acids, are well-known compositions, and are described in the Kirk-Othmer, EncY-cloPedia of Chemical Technoloqy, 2nd Ed., Vol. 19, pp.
614-629 (1969).
The preferred crude mixtures of fatty acids do not have a single molecular weight. For the purposes of this description one mole of such a crude fatty acid contains fractional moles of constituent fatty acids totaling one mole.
The fatty acid or corresponding ester and the diethanolamine can be readily reacted by mixing these reactants and heating until substantially complete con-densation has taken place, as indicated by the water dis-tilled overhead or by infrared spectrophotometric anal-ysis of the condensation product. Generally, a reaction temperature of from about 120~C to about 250C is oper-able. The condensation product contains predominantly an amide ester with a remaining amount of principally amide, and amide diester derivatives.
The subject composition is prepared by adding the water-soluble lower alkanoic acids, i.e., formic, ace-tic, propionic or butyric acids or a mixture thereof, to the above-described condensation product at a temperature which does not effect substantial additional condensation.
The te~perature during addition of this lower alkanoic acid is operably from about 10C to about 100C, prefer-ably from about 20C to about 50C. Substantially all of this lower alkanoic acid added to the composition can be titrated with an alkali metal hydroxide, which suggests 28,735-F _3_ . . , -114~541 that a hydrogen-bonded acid complex is formed and not a salt. Analysis of infrared and proton magnetic resonance spectroscopy supports the theory that the resulting com-position is an acid complex, but this structural eluci-dation is not definitive and the instant composition isnot limited thereby.
The subject compositions have shown excep-tional activity as conditioners in the froth flotation of coal. Froth flotation of coal is used in the art to beneficiate finely-divided coal. The use of condensates of alkanolamines and fatty acids and salts or other acid derivatives of these condensates as a conditioner in coal flotation is taught by W. C. Meyer, R. D. Hansen and R. E.
Hefner, Jr. in Canadian Applicatin Serial No. 344,307, filed January 24, 1980 for "Conditioner for Flotation of Coal". The relevant portions of this application further describe the utility of the instant compositions in the flotati~n of coal.
The coal to be floated can suitably be anthra-cite, bituminous or subbituminous. The instant composi-tion is preferably employed to float coal which cannot ~e floated with conventional frothers alone, and is particu-larly effective in the flotation of bituminous coal of intermediate or low grade, where the surface of the coal is oxidized to an extent which significantly impedes the flotation of the coal using conventi~nal agents.
The size of the coal particles to be separated by flotation is important because generally particles lar-ser than about 28 mesh (U.S. Sieve Size) are difficult to float. In typical operations, coal particles larger than 28 mesh, preferably larger than 100 mesh, are separated 28,735-F -4-1~144541 from both the inert material mined therewith and more finely divided coal ~y gravimetric separation techniques.
However, if a substantial fraction of the coal in the flotation feed comprises particles larger than 28 mesh, S it is desirable that the feed be comminuted further prior to flotation.
The sized coal flotation feed optionally is first washed and then mixed with sufficient water to pre-pare an agueous slurry having a solids concentration which promotes rapid flotation. Generally, a solids concentra-tion between a~out 2 to about 20 weight percent solids, more preferably from about 5 to about 10 weight percent, is preferred. The aqueous coal slurry is advantageously conditioned with the instant composition, a frother, fuel oil and other adjuvants, such as activators, dispersing reagents, depressing reagents and conditioning reagents, by mixing with the slurry in a n-anner kno~n to the art.
Generally, for coal that is difficult to float, it is advantageous to contact with mixing the coal slurry with the conditioner and fuel oil for a period of time prior to flotation, so as to effect intimate contact of the conditioner and fuel oil with substantially all of the coal. Where the aqueous coal slurry is prepared in a container distinct from the flotation cell and then is conveyed to the flotation cell through conduits, the desired intimate contact can conveniently be attained by introducing the conditioner and fuel oil to the slurry upstream from the flotation cell. The frother, however, should be introduced to the slurry shortly
3~ before or during flotation to provide maximum frothing.
28,735-F -5-5~1 The loading of the instant novel composition in the flotation medium which effects the greatest recov-ery of combustible carbonaceous matter with a tolerable amount of inert matter is affected by the sizP, grade, S degree of oxidation and inert matter content of the coal feed, as well as the loading of frother and other adju-vants. Generally, where the novel composition is employed with only fuel oil, the condensate is advantageously employed in a ratio of from about 0.00~ to about 1.0, preferably about 0.002 to about 0.2 kilogram of conden-sate per 1000 kilograms of coal flotation feed.
Fuel oil is employed in the flotation medium as a collector. Representative fuel oils include diesel oil, kerosene, Bunker C fuel oil and mixtures thereof.
The fuel oil can generally be advantageously employed in a ratio of from about 0.02 to about 2.5 kilograms fuel oil per 1000 kiïograms of coal flotation feed. The opti-mal loading of uel oil in the flotation medium is influ-enced by numerous factors, such as the size, degree of oxidation and grade of the coal to be floated and the loading of condensate and frother. Therefore, the load-ing of the fuel oil should be optimiz2d empirically to effect the greatest selectivity and recovery during flo-tation. In one preferred embodiment, the Cl-C4 alkanoic acid derivative of the diethanolamine/fatty acid conden-sate is charged to the flotation medium dispersed in fuel oil. Preferably, the alkanoic acid de~ivative comprises greater than about 0.1, more preferably 0.25 and less than about 70, more preferably 50 volu~e percent of the total fuel oil dispersion This fuel oil dispersion is believed to be a novel composition. Likewise, a composi-tion of the alkanoic acid derivative a~d frothing agent Z8,735-F -6-and optionally further comprising fuel oil is believed novel.
A frothing agent should be present in the flo-tation medium to promote formation of a froth. Conven-tional frothers, such as pine oil, cresol, C4 to C8 alka~nols containing one or two tertiary or one quaternary car-bon atom, e.g., isomers of amyl alcohol, are suitable for this purpose. However, methyl isobutyl carbino~ and poly-propylene glycol alkyl or phenyl ethers are preferred as frothers, with polypropylene glycol methyl ethers having a weight average molecular weight between about 200 and about 600 being most preferred. The optimal loading of frother in the flotation medium is influenced by a num-ber of factors, most important of which is the grade and degree of oxidation of the coal. Generally, a ratio of from about 0.05 to about 0.5 kilogram frother per 1000 kilograms of coal feed is advantageous.
The coal is operably floated at the natural pH of the coal in the aqueous slurry, which can vary from about 3.4 to about 9.5 depending upon the composition of the feed. However, a pH adjusting conlposition is option-ally used as necessary to adjust and maintain the pH of the aqueous coal slurry prior to and during flotation to a value from about 4 to about 9, preferably about 6 to about 8, which generally promotes the greatest coal recov-ery. If the coal is acidic in character, the pH adjust-ing composition can be an alkaline material, such as soda ash, lime, ammonia, potassium hydroxide or magnesium hydroxide, with sodium hydroxide being preferred. If the aqueous coal slurry is alkaline in character, a carboxylic 28,735-F -7-li4~541 acid such as acetic acid, or a mineral acid such as sul-furic acid or hydrochloric acid, are operable to adjust the pH.
The conditioned and pH-adjusted aqueous coal slurry is ~erated in a conventional flotation machine or bank of rougher cells to float the coal. Any suitable rougher flotation unit can be employed.
The practice of the process employing the instant invention can be used alone to beneficiate coal.
Alternatively, the process can be used in conjunction with secondary flotations following the presently described process to effect even greater beneficiation of the coal.
The following examples illustrate the inven-tion and its ut,lity. Unless otherwise indicated, allparts and percentage~ are by weight.
Exam~le 1 A lO00-U.S. gallon, steam-heated Pfaudler reac-tion vessel was charged with 2851 kilograms (9876 moles) of a tall oil fatty acid reactant. This tall oil fatty acid contained 39 percent rosin acids, 29.3 percent ol,eic acid, 23 percent linoleic acid, 3.7 percent conjugated linoleic acid, 1.8 percent stearic acid and about 3 per-cent other acids and components. To the reaction vessel were added 519 kilograms (4938 moles) of diethanolamine with stirring. This reaction mixture was sparged with nitrogen and heated to a temperature o~ about 137C, at which time water began to evolve. The heating of the 28,735-F -8-11~4541 mixture was continued until the evolution of water ceased. A maximum reaction temperature of 158C was reached.
A small sample of the resulting condensation product was analyzed by infrared and proton magnetic resonance spectroscopy. This condensate was determined to contain predominantly an amide ester with lesser amounts of amide and amide diester.
The condensate was cooled in the reaction vessel to a temperature of 43C and then 221 kilograms (3679 moles) of acetic acid were introduced with stir-ring. Analysis of a sample of the resultant product by proton magnetic resonance spectroscopy indicated the presence of the acidic proton in acetic acid, which sug-gests that a salt is not formed. The acetic acid in theproduct was titrated stoichiometrically with 0.085 nor-mal KOH, which confirms that an acetic acid salt is not formed.
Example 2 Five flotation runs are performed in the lab-oratory using a #1 diesel oil dispersion of 1:2 conden-sate of diethanolamine/tall oil fatty acid (DEA/TOFA) or an acetic acid or propionic acid derivative thereof (an 8 volume percent dispersion in the diesel oil) as the Z5 combir,ed conditioner and collector. These acid deriva-~ives consist of 0.5 mole of acetic or propionic acid for eacn mole of the condensate. In each run, 200 grams of coal containing 14.4 percent ash in 3 liters of water 28,735-F -9-~14~541 is introduced into a flotation machine and conditioned for 7 minutes. The pH of the slurry is adjusted to the values tabulated in Table I with a 1 normal aqueous solu-tion of ~aOH or HC1.
The slurry is a~itated while #l diesel oil containing the conditioner is charged to the slurry to effect a loading equivalent to about 1.5 kilograms of diesel oil per 1000 kilograms of coal feed and 0.12 kilogram of the condensate per 1000 ~ilograms of coal.
A small amount (G.04 cc) of a conventional frother is added to the slurry, the slurry agitated for 10 seconds and then air is introduced. The results and identifying parameters for each run are tabulated in Table I.
TABLE I
% %
Coal Ash RunConditioner ~H RecoverY Content (1)DEA/TOFA 5.1 88.0 9.8 AAcetic Acid Deriva- 5 0 88 010.2 tive of DEA/TOFA
Propionic Acid BDerivative of 5.0 87.9 9.7 DEA/TOFA
(2)DEA/TOFA 8.0 79.3 9.3 tive of DEA/TOFA 8.0 80.7 9.3 (1) Comparative A
~2) Comparative B
28,735-F -10~ -~A .
114~541 Example 3 A 1:2 condensate of DEA/TOFA and an acetic acid derivative thereof is employed in a coal flotation plant. The acetic acid derivative consists of 0.5 mole 5- of acetic acid for each mole of condensate. The condi-tioner is added to #1 diesel oil in a quantity suffi-cient to effect an increase of 10 percent in volume. The mixture of conditioner and #1 diesel oil is introduced at a rate of 200 cubic centimeters per minute to the tank used to collect the smaller than 100 mesh coal prior to introduction to the four banks of Daniel flotation cells.
In one instance, diesel oil alone is introduced for pur-poses of comparison. The pH of the coal slurry in the collecting tank is determined for each run. To each bank of cells at the air port of the first of the four cells in the bank, is introduced 67 cubic centimeters per min-ute of a polypropylene glycol methyl ether frother having a weight average molecular weight of about 40Q. For each run, a sample of the coal feed is recovered as it is intro-duced to the first cell of a bank of cells. Samples ofthe material recovered by froth flotation are taken from near the end of the second cell in each ban~ of four cells.
Tail materials are sampled at the overflow weir above the 6and gate.
The samples of coal feed, floated material and tail material in each instance are dried and then - weighed. One-gram samples of the coal feed, the floated material (or concentrate) and the tail material are then each burned, and the weight of the unburned ash deter-mined. The difference in the weight of each of the frac-tiOIls before and after combustion is assumed to be the weight of coal present in each fractian. The percentage of the ash-free or "clean" coal recovered is then calcu-lated by the formula:
28,735-F -11-Percent Clean Coal = 100 x where~
C = 100-(Percent Ash in Concentrate) F = 100-(Percent Ash in Feed Material) T = 100-(Percent Ash in Tail Material) The results and identifying parameters are tabulated in Table II.
TABLE II
10. % Clean % Ash % Ash in Coal Run Conditioner _pH in Feed Concentrate Recovered Acetic Acid D Derivative of 6.9 47.8 13.8 38.0 ~1) DEA/TOFA 6.8 ~0.1 13.8 21.1 (2) None 6.7 42.7 lI.5 10.6 (l)Comparative C
; ~2)Comparative D
The data compiled in Table II indicate that the claimed acetic acid derivative of the DEA/TOFA con-densate is much more effective in floating certain coals in a commercial floating operation than diesel oil alone or diesel oil containing the DEA/TOFA condensate but not 2 5 aceti c ac i d .
28,735-F -12-Although in the foregoing Examples the inven-tion composition and diesel oil collector are added upstream and the frother is added at the cells, it is also possible and generally preferred.to add the three components at the cell feed box to simplify operations.
28,735-~ -13-.
28,735-F -5-5~1 The loading of the instant novel composition in the flotation medium which effects the greatest recov-ery of combustible carbonaceous matter with a tolerable amount of inert matter is affected by the sizP, grade, S degree of oxidation and inert matter content of the coal feed, as well as the loading of frother and other adju-vants. Generally, where the novel composition is employed with only fuel oil, the condensate is advantageously employed in a ratio of from about 0.00~ to about 1.0, preferably about 0.002 to about 0.2 kilogram of conden-sate per 1000 kilograms of coal flotation feed.
Fuel oil is employed in the flotation medium as a collector. Representative fuel oils include diesel oil, kerosene, Bunker C fuel oil and mixtures thereof.
The fuel oil can generally be advantageously employed in a ratio of from about 0.02 to about 2.5 kilograms fuel oil per 1000 kiïograms of coal flotation feed. The opti-mal loading of uel oil in the flotation medium is influ-enced by numerous factors, such as the size, degree of oxidation and grade of the coal to be floated and the loading of condensate and frother. Therefore, the load-ing of the fuel oil should be optimiz2d empirically to effect the greatest selectivity and recovery during flo-tation. In one preferred embodiment, the Cl-C4 alkanoic acid derivative of the diethanolamine/fatty acid conden-sate is charged to the flotation medium dispersed in fuel oil. Preferably, the alkanoic acid de~ivative comprises greater than about 0.1, more preferably 0.25 and less than about 70, more preferably 50 volu~e percent of the total fuel oil dispersion This fuel oil dispersion is believed to be a novel composition. Likewise, a composi-tion of the alkanoic acid derivative a~d frothing agent Z8,735-F -6-and optionally further comprising fuel oil is believed novel.
A frothing agent should be present in the flo-tation medium to promote formation of a froth. Conven-tional frothers, such as pine oil, cresol, C4 to C8 alka~nols containing one or two tertiary or one quaternary car-bon atom, e.g., isomers of amyl alcohol, are suitable for this purpose. However, methyl isobutyl carbino~ and poly-propylene glycol alkyl or phenyl ethers are preferred as frothers, with polypropylene glycol methyl ethers having a weight average molecular weight between about 200 and about 600 being most preferred. The optimal loading of frother in the flotation medium is influenced by a num-ber of factors, most important of which is the grade and degree of oxidation of the coal. Generally, a ratio of from about 0.05 to about 0.5 kilogram frother per 1000 kilograms of coal feed is advantageous.
The coal is operably floated at the natural pH of the coal in the aqueous slurry, which can vary from about 3.4 to about 9.5 depending upon the composition of the feed. However, a pH adjusting conlposition is option-ally used as necessary to adjust and maintain the pH of the aqueous coal slurry prior to and during flotation to a value from about 4 to about 9, preferably about 6 to about 8, which generally promotes the greatest coal recov-ery. If the coal is acidic in character, the pH adjust-ing composition can be an alkaline material, such as soda ash, lime, ammonia, potassium hydroxide or magnesium hydroxide, with sodium hydroxide being preferred. If the aqueous coal slurry is alkaline in character, a carboxylic 28,735-F -7-li4~541 acid such as acetic acid, or a mineral acid such as sul-furic acid or hydrochloric acid, are operable to adjust the pH.
The conditioned and pH-adjusted aqueous coal slurry is ~erated in a conventional flotation machine or bank of rougher cells to float the coal. Any suitable rougher flotation unit can be employed.
The practice of the process employing the instant invention can be used alone to beneficiate coal.
Alternatively, the process can be used in conjunction with secondary flotations following the presently described process to effect even greater beneficiation of the coal.
The following examples illustrate the inven-tion and its ut,lity. Unless otherwise indicated, allparts and percentage~ are by weight.
Exam~le 1 A lO00-U.S. gallon, steam-heated Pfaudler reac-tion vessel was charged with 2851 kilograms (9876 moles) of a tall oil fatty acid reactant. This tall oil fatty acid contained 39 percent rosin acids, 29.3 percent ol,eic acid, 23 percent linoleic acid, 3.7 percent conjugated linoleic acid, 1.8 percent stearic acid and about 3 per-cent other acids and components. To the reaction vessel were added 519 kilograms (4938 moles) of diethanolamine with stirring. This reaction mixture was sparged with nitrogen and heated to a temperature o~ about 137C, at which time water began to evolve. The heating of the 28,735-F -8-11~4541 mixture was continued until the evolution of water ceased. A maximum reaction temperature of 158C was reached.
A small sample of the resulting condensation product was analyzed by infrared and proton magnetic resonance spectroscopy. This condensate was determined to contain predominantly an amide ester with lesser amounts of amide and amide diester.
The condensate was cooled in the reaction vessel to a temperature of 43C and then 221 kilograms (3679 moles) of acetic acid were introduced with stir-ring. Analysis of a sample of the resultant product by proton magnetic resonance spectroscopy indicated the presence of the acidic proton in acetic acid, which sug-gests that a salt is not formed. The acetic acid in theproduct was titrated stoichiometrically with 0.085 nor-mal KOH, which confirms that an acetic acid salt is not formed.
Example 2 Five flotation runs are performed in the lab-oratory using a #1 diesel oil dispersion of 1:2 conden-sate of diethanolamine/tall oil fatty acid (DEA/TOFA) or an acetic acid or propionic acid derivative thereof (an 8 volume percent dispersion in the diesel oil) as the Z5 combir,ed conditioner and collector. These acid deriva-~ives consist of 0.5 mole of acetic or propionic acid for eacn mole of the condensate. In each run, 200 grams of coal containing 14.4 percent ash in 3 liters of water 28,735-F -9-~14~541 is introduced into a flotation machine and conditioned for 7 minutes. The pH of the slurry is adjusted to the values tabulated in Table I with a 1 normal aqueous solu-tion of ~aOH or HC1.
The slurry is a~itated while #l diesel oil containing the conditioner is charged to the slurry to effect a loading equivalent to about 1.5 kilograms of diesel oil per 1000 kilograms of coal feed and 0.12 kilogram of the condensate per 1000 ~ilograms of coal.
A small amount (G.04 cc) of a conventional frother is added to the slurry, the slurry agitated for 10 seconds and then air is introduced. The results and identifying parameters for each run are tabulated in Table I.
TABLE I
% %
Coal Ash RunConditioner ~H RecoverY Content (1)DEA/TOFA 5.1 88.0 9.8 AAcetic Acid Deriva- 5 0 88 010.2 tive of DEA/TOFA
Propionic Acid BDerivative of 5.0 87.9 9.7 DEA/TOFA
(2)DEA/TOFA 8.0 79.3 9.3 tive of DEA/TOFA 8.0 80.7 9.3 (1) Comparative A
~2) Comparative B
28,735-F -10~ -~A .
114~541 Example 3 A 1:2 condensate of DEA/TOFA and an acetic acid derivative thereof is employed in a coal flotation plant. The acetic acid derivative consists of 0.5 mole 5- of acetic acid for each mole of condensate. The condi-tioner is added to #1 diesel oil in a quantity suffi-cient to effect an increase of 10 percent in volume. The mixture of conditioner and #1 diesel oil is introduced at a rate of 200 cubic centimeters per minute to the tank used to collect the smaller than 100 mesh coal prior to introduction to the four banks of Daniel flotation cells.
In one instance, diesel oil alone is introduced for pur-poses of comparison. The pH of the coal slurry in the collecting tank is determined for each run. To each bank of cells at the air port of the first of the four cells in the bank, is introduced 67 cubic centimeters per min-ute of a polypropylene glycol methyl ether frother having a weight average molecular weight of about 40Q. For each run, a sample of the coal feed is recovered as it is intro-duced to the first cell of a bank of cells. Samples ofthe material recovered by froth flotation are taken from near the end of the second cell in each ban~ of four cells.
Tail materials are sampled at the overflow weir above the 6and gate.
The samples of coal feed, floated material and tail material in each instance are dried and then - weighed. One-gram samples of the coal feed, the floated material (or concentrate) and the tail material are then each burned, and the weight of the unburned ash deter-mined. The difference in the weight of each of the frac-tiOIls before and after combustion is assumed to be the weight of coal present in each fractian. The percentage of the ash-free or "clean" coal recovered is then calcu-lated by the formula:
28,735-F -11-Percent Clean Coal = 100 x where~
C = 100-(Percent Ash in Concentrate) F = 100-(Percent Ash in Feed Material) T = 100-(Percent Ash in Tail Material) The results and identifying parameters are tabulated in Table II.
TABLE II
10. % Clean % Ash % Ash in Coal Run Conditioner _pH in Feed Concentrate Recovered Acetic Acid D Derivative of 6.9 47.8 13.8 38.0 ~1) DEA/TOFA 6.8 ~0.1 13.8 21.1 (2) None 6.7 42.7 lI.5 10.6 (l)Comparative C
; ~2)Comparative D
The data compiled in Table II indicate that the claimed acetic acid derivative of the DEA/TOFA con-densate is much more effective in floating certain coals in a commercial floating operation than diesel oil alone or diesel oil containing the DEA/TOFA condensate but not 2 5 aceti c ac i d .
28,735-F -12-Although in the foregoing Examples the inven-tion composition and diesel oil collector are added upstream and the frother is added at the cells, it is also possible and generally preferred.to add the three components at the cell feed box to simplify operations.
28,735-~ -13-.
Claims (7)
1. A composition of matter comprising the reaction product of two components:
(1) a condensation product of diethanolamine and a C10-C24 fatty acid condensed in a mole ratio of about 1:2, and (2) about one-half the equimolar amount of a C1-C4 mono-carboxylic acid or mixture thereof, based on the moles of condensate.
(1) a condensation product of diethanolamine and a C10-C24 fatty acid condensed in a mole ratio of about 1:2, and (2) about one-half the equimolar amount of a C1-C4 mono-carboxylic acid or mixture thereof, based on the moles of condensate.
2. The composition as in Claim 1 wherein the fatty acid is a tall oil fatty acid or a mixture of tall oil fatty acids.
3. The composition as in Claim 1 wherein component (2) is acetic acid.
4. The composition as in Claim 1 wherein component (2) is propionic acid.
5. The composition as in Claim 3 wherein the fatty acid condensed in component (1) is a tall oil fatty acid mixture.
28,735-F -14-
28,735-F -14-
6. The composition of Claim 1 which further comprises fuel oil in such an amount that said reaction product constitutes 0.1 to 70 volume percent of the total volume.
7. The composition of Claim 1 which further comprises an effective amount of a frothing agent.
28,735-F -15-
28,735-F -15-
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000369032A CA1144541A (en) | 1981-01-21 | 1981-01-21 | Lower alkanoic acid derivatives of a diethanolamine/fatty acid condensate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000369032A CA1144541A (en) | 1981-01-21 | 1981-01-21 | Lower alkanoic acid derivatives of a diethanolamine/fatty acid condensate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1144541A true CA1144541A (en) | 1983-04-12 |
Family
ID=4118981
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000369032A Expired CA1144541A (en) | 1981-01-21 | 1981-01-21 | Lower alkanoic acid derivatives of a diethanolamine/fatty acid condensate |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1144541A (en) |
-
1981
- 1981-01-21 CA CA000369032A patent/CA1144541A/en not_active Expired
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