JPS6255901B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to foam flotation of coal-containing ash, coal sludge or coal-containing residue to recover coal containing a low percentage of impurities. In particular, the invention relates to the use of condensation products of alkanolamines and fatty acids as conditioners for the flotation of fine coal. The natural process of "coalization" deposits some non-combustible mineral matter along with the naturally combustible carbonaceous solids. Although most of the noncombustibles can be removed by sieving or other gravity concentration techniques, other cleaning methods are more effective in removing fine materials that are intimately associated with carbonaceous solids. Coal foam flotation
floatation is used in this technique to beneficiate fine coarse coal. Bituminous coal generally has natural hydrophobic properties, so that the coal can be flotated in the presence of a frother, such as methyl isobutyl carbinol, preferably with a relatively mild collector such as kerosene. It is. However, anthracite, as well as all grades of coal whose surface is at least partially oxidized, do not flotate well in said media, resulting in the loss of significant amounts of combustibles in the tail from the flotation. There is. The charging amount of oil type collector is generally per 1000 kg of coal feed for medium or low rank bituminous coal.
The charging amount is 0.05 to 1 kg, which is relatively large for lignite and anthracite flotation. However, good recovery of oxidized coal or lignite can only be achieved at high oil-type collector loadings, in which a significant amount of inert material is floated together with the combustible material. Sun Trans.AIME, 199:396~
401 (1954) suggests that medium aliphatic amines can be utilized as co-collectors in the flotation of oxidized coals to provide enhanced recovery. However, even these amine collectors suspend substantial amounts of ash with the coal and provide only partial recovery of combustibles. The present invention provides a foam flotation process for beneficiation of coal that (a) separates the coal from flotation size particles; and (b) contains a fuel oil collector and an effective amount per mole of alkanolamine. condensed with a fatty acid or fatty acid ester, with a molar ratio of at least 0.8 moles of fatty acid or fatty acid ester; [wherein R ₁ is a β-hydroxyalkyl group or an inertly substituted β-hydroxyalkyl group having 2 to 5 carbon atoms; and R ₂ and R ₃ are independently R ₁ , hydrogen, 1 -4 carbon atom alkyl group or formula (wherein y is 2 or 3, and R ₄ and R ₅ are independently R ₁ , hydrogen or 1-4
is a monovalent group corresponding to the alkyl of the carbon atom of] ] A condensation product of an alkanolamine corresponding to
Alternatively, the method is characterized by flotation of the coal sized in (a) above in a foamy aqueous medium containing an acid derivative of the condensation product. The present invention also provides the following reaction products: (1) a condensation product of diethanolamine and a _C10 - _C24 fatty acid condensed in a molar ratio of 1:2; and (2) based on the number of moles of the condensate: Encompasses compositions containing half an equimolar amount of _C1 - _C4 monocarboxylic acids or mixtures thereof. The alkanolamines utilized as a component of the condensation product in the practice of this invention may be unsubstituted or N
-Alkyl-substituted monoethanolamine; diethanolamine; triethanolamine; hydroxyethylethylenediamine; N・N′-di(hydroxyethyl)ethylenediamine; N・N-di(hydroxyethyl)ethylenediamine;
N′-tri(hydroxyethyl)ethylenediamine; N・N・N′・N′-tetra(hydroxyethyl)ethylenediamine; and the ethylene moiety is substituted by a propylene group, and/or the hydroxyethyl group is 3 to 5 is a related compound substituted with a β-hydroxyalkyl group having carbon atoms of . For economic reasons, this hydroxyalkyl group is preferably a hydroxyethyl, 1-methyl (hydroxyethyl) or 1-ethyl (hydroxyethyl) group. However, unsubstituted alkanolamines as defined above having only hydroxyethyl and ethylene moieties are preferred. Diethanolamine, triethanolamine and di-, tri- or tetra(hydroxyethyl)ethylenediamine are particularly preferred alkanolamines, with diethanolamine being the most preferred. The alkanolamines can be a single compound or a mixture of the available alkanolamines, the latter being preferred for economic reasons. These alkanolamines are commercially available or can be readily prepared by reaction of alkylene oxides with ammonia or alkylene diamines in a manner known in the art. As the fatty acid to be condensed with the alkanolamine, a fatty acid having a saturated or unsaturated alkyl group can be used. The fatty acid may suitably have hydroxyl substitutions on its alkyl portion, but such substitutions do not confer any substantial advantage. Fatty acids such as oleic acid, lauric acid, linoleic acid, palmitic acid, stearic acid, myristic acid, mixtures thereof and other related fatty acids can be used. Esters corresponding to these fatty acids, such as glycerides, can also be used, but are less preferred. For economic reasons, fatty acids with small amounts of rosin acids, lignin and unsaponifiables, such as tall oil, coconut oil, palm oil, palm kernel oil, cottonseed oil, linseed oil, olive oil, peanut oil and fish oil. It is preferred to use a crude mixture of Tall oil and tall oil heads are particularly suitable fatty acid mixtures. Tall oil and tall oil head are Kirk-Othmer,
Encyclopedia of Chemical Technology, Part 2
19, pp. 614-629 (1969). The fatty acid or corresponding ester and alkanolamine are mixed and heated by mixing and heating these reactants until the desired degree of condensation has occurred as indicated by overhead distilled water or infrared spectral analysis of the condensation product. Therefore, the reaction can be easily carried out. Generally, reaction temperatures of about 120<0>C to about 250<0>C can be used. This reaction is referred to herein as condensation to distinguish it from the formation of ammonium salts of acids at relatively low temperatures. Depending on the alkanolamine, the condensation product can be an ester, an amide or both. Although it is desirable for the condensation reaction to be complete for the most efficient utilization of the reactants, the condensation product can be used as a conduiter for coal in the presence of substantial amounts of unreacted fatty acids and non-condensed alkanol ammonium salts of acids. However, it is less effective. The term "conditioner" indicates that the condensation product is primarily effective in increasing the hydrophobicity of the coal surface. However, the use of the descriptive term "conditioner" does not exclude the possibility that this condensation product acts as a co-collector with the fuel oil. The utility of the present condensation products is greater when the reactants are condensed in specific molar ratios. Although it is desirable to condense at least a stoichiometric amount of a fatty acid or its equivalent (ie, an aliphatic ester) with the alkanolamine, less than equimolar amounts can be used. The molar ratio of fatty acid or aliphatic ester to alkanolamine is at least 0.8, and preferably about
1.5:1 to about 5:1, more preferably about 2:1 to about 3:1. However, to avoid waste of fatty acids, the number of moles of fatty acid and ester in the condensate should not exceed the number of moles of alkanolamine times the average number of reactive sites on the molecule of the alkanolamine. The term "reactive site" refers to exchangeable hydrogen substitutions on amine groups and reactive hydroxyl substitutions on hydroxyalkyl groups. These react with fatty acids or fatty acid esters to produce amides and esters, respectively. In this flotation method, not only the condensate itself but also the acid derivatives of the aforementioned condensation products can be used. These derivatives are produced by adding an inorganic or organic acid to the condensate to lower the PH of the resulting mixture. This derivative may be a salt, partial salt or acid complex. Organic acid derivatives are generally more easily dispersed in aqueous flotation media than the parent compounds. These derivatives may exhibit greater or lesser activity than their parent compounds, but this relationship is not completely understood. Common inorganic acids that can be used to prepare acid derivatives include phosphoric acid, nitric acid, boric acid, hydrochloric acid, hydrobromic acid and sulfuric acid. Although these inorganic acid derivatives can be used, they are not preferred. Organic acids that can be used include fatty mono-, di- or tricarboxylic acids; lower alkyl carboxylic acids; mono- or dihydroxy lower alkyl carboxylic acids; amino-substituted carboxylic acids and unsubstituted aliphatic carboxylic acids. Typical examples of these organic acids are formic acid, acetic acid, hydroxyacetic acid, propionic acid, butyric acid, isovaleric acid, lactic acid, gluconic acid, aminoacetic acid, malonic acid,
These are succinic acid, adipic acid, malic acid, tartaric acid, glutaric acid, fumaric acid, citric acid, salicylic acid, benzoic acid and naphthalic acid. Fatty acids can be used, but are not preferred. Acetic acid, as well as other lower alkyl organic carboxylic acids, especially C1 _{- C4} organic acids, are suitable for this purpose. In one particularly preferred embodiment, 0.5 mol of acetic acid or propionic acid is added per mole of condensate prepared from 1 equivalent of diethanolamine condensed with 2 equivalents of tall oil fatty acid. Base titration of the acetic acid or propionic acid derivatives of the resulting condensates and infrared and proton magnetic resonance spectroscopy indicate that an acid complex rather than a salt is formed. The charge of condensation products in the flotation medium that provides maximum recovery of combustible carbonaceous material with an acceptable amount of inerts depends on the size, grade, degree of oxidation and inerts content of the coal feed, and the foam content. and the amount of other adjuvants charged. The term "effective amount of condensation product" is used herein to indicate the amount of such product required to increase the recovery of coal by foam flotation in the presence of fuel oil and frother. Ru. Generally, if the condensation product is used with fuel oil only, the coal flotation feed 1000
About 0.001 to about 1.0, preferably about 0.002 to about 0.2 per Kg
It is advantageous to use a condensate with a ratio of Kg of condensate. activator, conditioner
The condensation products can be utilized in combination with co-collectors or other auxiliaries, such as reagents), dispersants, blowing agents and depressing agents. Fuel oil is used as a collector in the flotation medium. Typical fuel oils include diesel oil, kerosene, Bunker C fuel oil and mixtures thereof. Fuel oil is generally a coal flotation feed
Advantageously, a ratio of about 0.02 to about 2.5 kg of fuel oil per 1000 kg is used. The optimum charge of fuel oil in the flotation medium depends on the size of the coal to be flotated,
It is influenced by many factors such as the degree and grade of oxidation and the condensate and blowing agent charges. Therefore, the fuel oil charge should be optimized experimentally to obtain maximum selectivity and recovery during flotation. In one embodiment, the condiner is charged to a flotation medium that is dispersed in part or all of the fuel oil charge. A blowing agent should be present to promote foam formation in the flotation medium. Customary blowing agents are suitable for this purpose, such as pine oil, cresol, _C4 - _C8 alkanols having one or two tertiary or one quaternary carbon atoms, e.g. isomers of amyl alcohol. It is. However, methyl isobutyl carbinol and propylene glycol alkyl or phenyl ethers are preferred as blowing agents, with propylene glycol methyl ethers having an average molecular weight of about 200 to about 600 being most preferred. The optimum charge of blowing agent in the flotation medium is influenced by a number of factors, the most important of which is the rank and degree of oxidation of the coal. Generally, a ratio of about 0.05 to about 0.5 Kg per 1000 Kg of coal feed is advantageous. The coal to be flotated by the method can suitably be anthracite, bituminous or sub-bituminous coal. This method is suitable for flotation of coal which cannot be flotated using conventional blowing agents, and where the surface of the coal is oxidized to the extent that it significantly interferes with flotation of coal using conventional agents. It is particularly effective in flotation of medium or low grade bituminous coal. The size of the coal particles to be separated by flotation is important because particles larger than about 28 meshes (US sieve diameter) are generally difficult to flotate. In typical operations, coal particles larger than 28 meshes, preferably larger than 100 meshes, are separated by gravity separation techniques from both the inert material and the relatively fine coal that is mined with them. . However, if a substantial fraction of the coal in the flotation feed consists of particles larger than 28 mesh, it may be desirable to further grind the feed prior to flotation. The sized coal flotation feed is optionally first washed and then mixed with sufficient water to obtain an aqueous slurry with a solids concentrate that promotes rapid flotation. Generally, a solids concentration of about 2 to about 20% by weight, more preferably about 5 to about 10% by weight, is suitable. This aqueous coal slurry is advantageously conditioned by mixing the slurry with condensation products, blowing agents, fuel oil, and any other adjuvants in a manner known in the art. Generally, for coals that are difficult to flotate, the coal slurry is contacted with the condi- tioner and fuel oil for a period of time prior to flotation to achieve intimate contact of the condi- tioner and fuel oil with substantially all of the coal. It is advantageous to implement. If the aqueous coal slurry is prepared in a vessel separate from the flotation cell and then conveyed to the flotation mine through a conduit, the conduitant and fuel oil may be introduced into the slurry against the flow from the flotation cell. Thus, the desired close contact can be conveniently achieved. However, the blowing agent should be introduced into the slurry shortly before or during flotation to obtain maximum foaming. Coal can be flotated at the natural PH of the coal in an aqueous slurry, which can vary from about 3.0 to about 9.5 depending on the composition of the feed. However, a PH adjusting composition is optionally used to adjust the PH of the aqueous coal slurry from about 4 to about 8, preferably from about 4 to about 7, before and during flotation.
control is maintained, which typically facilitates maximum coal recovery. If the coal is particularly acidic, the PH
The conditioning composition includes soda ash, lime, ammonia,
Alkaline materials can be used, such as caustic potash or magnesium hydroxide. If the aqueous coal slurry is alkaline in nature, a carboxylic acid such as acetic acid or a mineral acid such as sulfuric acid or hydrochloric acid may be used to adjust the PH. The conditioned and PH-adjusted aqueous coal slurry is aerated in a conventional flotation machine or in a bank of relatively irregular cells. Any comparatively rugged flotation unit can be used. Coal can be beneficent using the embodiment of the method of the invention alone. Alternatively, this method can be used in combination with a secondary flotation after the method to produce even larger coal beneficiation. In the following examples, all parts and percentages are by weight unless otherwise indicated. Example 1 In a series of similar flotation experiments, differing in the presence or absence of the blowing agent and the alkanolamine/fatty acid condensation product used, a 200 g charge of ground coal was diluted with deionized water to 6.67
% solids was obtained. Coal has a high oxygen content (14.3
%) is a low-grade, bituminous coal with a high oxidation surface. The fraction of particles larger than 25 mesh of the coal feed is separated and ground prior to dilution and then recombined with the remaining coal. In crushed coal feed, more than 90% of particles are smaller than 80 mesh. Approximately 14.7% of the coal is charged into the slurry.
Contains ash. This aqueous coal slurry is introduced into a flotation machine having a 3 liter cell. The pH of the slurry was measured to be approximately 4. The coal slurry is stirred for about 7 minutes to fully moisten the coal, at which time refined kerosene is added to the slurry to provide a charge of about 2.5 kg of kerosene per 1000 kg of coal feed. In two flotation experiments that are embodiments of the present method, condensate prepared from a molar ratio of 1 part diethanolamine (DEA) to 2 parts tall oil fatty acid (TOFA) was combined with kerosene to produce approximately 0.125
Introduced into the aqueous coal slurry in a charge of Kg. According to conventional analysis, this tall oil fatty acid reactant contains 39% rosin acid, 29.3% oleic acid, and 23%
of linoleic acid, 3.7% conjugated linoleic acid, 1.8
% stearic acid and approximately 3.2% other acids and ingredients. A two-control flotation experiment is also conducted that is not an embodiment of the invention in which kerosene is the collector added to the slurry. After adding the kerosene to the slurry, the slurry is stirred for 1 minute to condition the coal. Next, a blowing agent is added to the slurry and
Charge 0.2Kg of blowing agent. In separate experiments, methyl isobutyl carbinol (MIBC) and polypropylene glycol methyl ether (D-1012) having a weight average molecular weight of about 400 are each used as blowing agents. Condense the aqueous coal slurry by stirring for 1 minute, then begin aeration of the medium and continue for 4 minutes. Collect a foamy concentrate during aeration. The collected concentrate is first dried and then weighed. The recovery rate of coal by flotation is determined from the weight of the coal in the concentrate divided by the weight of the coal in the 200 g charge (i.e. the total weight minus the weight of ash). Completely burn a 1 g sample of concentrate;
The ash content of the concentrate is determined from the weight of the material remaining after combustion. The table displays the type of conditioner and blowing agent as well as the coal recovery and ash content in the concentrate for each experiment. Also included in the table are comparative flotation results in which a prior art aliphatic amine co-collector, dodecylamine hydrochloride (DDA HCl), was used in place of the DEA/TOFA concentrate in the flotation, but otherwise the same as described above. It can be done. [Table] The data in the table is the TOFA of DEA during flotation.
The presence of condensation products with kerosene is shown to greatly enhance the recovery of oxidized coal compared to flotation systems utilizing only kerosene. Furthermore, in experiment A
The DEA/TOFA condiner exhibits higher coal recovery and less ash co-flotation than the prior art aliphatic amine utilized in Comparative C. Example 2 A series of experiments are carried out similarly to Example 1, with minor differences disclosed below. PH of water-based coal slurry
After measuring the pH, the pH is adjusted to 7 and 9 respectively in two separate experiments by addition of caustic soda. In the third experiment, the PH of the coal slurry is measured but not adjusted. The coal in each of the three slurries is then flotated in the presence of DEA/TOFA, kerosene and PPGME blowing agents as in Example 1 and at the stated charges. The results and identification parameters for each experiment are displayed in the table. [Table] The data in the table prove the effectiveness of slurry PH on the recovery of clean coal by flotation of this particular oxidized bituminous coal. Example 3 Seven flotation experiments are carried out as in Example 1, except that the condensation product is used as a condishioner. The condensation product is prepared by condensing the tall oil fatty acids of Example 1 in each case with an alkanolamine selected from the mixture of diethanolamine (DEA), triethanolamine (TEA) and hydroxyethyl-substituted ethylenediamine (HEEDA). . The HEEDA mixture consists of about 10% aminoethylethanolamine, about 75% di(hydroxyethyl)ethylenediamine, about 12% tri(hydroxyethyl)ethylenediamine, and about 3% tetra(hydroxyethyl)ethylenediamine. Alkanolamine (AA) and tall oil fatty acid (TOFA) are condensed at the molar ratio shown below. The coal in each of the three slurries was added to the coal feed with kerosene and PPGME blowing agents in the manner and charge described in Example 1.
Flotation is carried out at a condensation product content of 0.125Kg per 1000Kg.
The results and identification parameters for each experiment are displayed in the table. [Table] [Table] Example 4 Fourteen flotation experiments are carried out in the general manner of Example 1, except that different coals are used. Seven different coking coals with the ash contents indicated below were flotated in each pair of experiments, with DEA/TOFA 1:2 in only one of the pairs.
The condensate is used and the other experiment serves as a control. In each case the coal is introduced into the flotation machine as an aqueous slurry. Measure the PH of the slurry and then
PPGME blowing agent, kerosene and DEA/TOFA condensate per 1000Kg of coal feed specified in the table.
Kg charge is introduced into the slurry. After flotation is completed, the concentrate is recovered and the ash content and coal recovery determined in the manner described above. Table: The data presented demonstrate that the condensation product of DEA with TOFA enhances the recovery of clean coal from each of the coals tested. Moreover, this improvement is despite the fact that a lower kerosene charge is used in the condensate experiments than in the control experiments. EXAMPLE 5 Five flotation experiments are carried out in the general manner of Example 1 using an 8% dispersion of a 1:2 DEA/TOFA condensate or its acetic acid or propionic acid derivative in No. 1 diesel oil as the conduit collector. These acid derivatives consist of 0.5 mol of acetic acid or propionic acid for each mole of condensate. These derivatives are considered to be hydrogen bonded acid complexes since the acetic acid introduced can be titrated stoichiometrically with 0.085N KOH. Infrared and proton magnetic resonance spectra also indicate the presence of an acid complex with hydrogen bonds. In each experiment, 200 g of coal with 14.4% ash in 3 liters of water are introduced into the flotation machine and conditioned for 7 minutes. Adjust the pH of the slurry to the value shown in the table with a 1N aqueous solution of NaOH or HCl. The slurry is stirred, while No. 1 diesel oil containing conduit is charged, approximately 1.5 kg of diesel oil per 1000 kg of coal feed and condensate per 1000 kg of coal.
Obtain a charge equivalent to 0.12Kg. Add a small amount of conventional blowing agent (D-1012) to the slurry and stir the slurry for 10 seconds. The results and identification parameters for each experiment are displayed in the table. [Table] Conductor
Condensation products of alkanolamines and higher organic acids are known. US Pat. No. 2,173,909, Kryciewski, September 26, 1939, discloses that aliphatic alkanolamides can be used in the flotation of ores, especially in slightly acidic media. U.S. Patent 2,609,931, Rodman, 9/1952
May 9th teaches that monoaliphatic amide derivatives of N.N-dihydroxyalkylethylenediamines are useful superagents; columns 6, 43~
In line 47 the acetate salts of these compounds are said to be particularly useful in some applications. U.S. Patent No. 2993919, Findre, July 25, 1961,
The use of acid salts of mixtures of aliphatic alkanolamides and diethanolamines in ore flotation is described. Although condensation products of diethanolamine and fatty acids are known in the art, generally at least an equimolar excess of diethanolamine to fatty acid is used in preparing these condensates. The term "condensation product" is used herein to distinguish this product from ammonium salts of fatty acids that occur at relatively low temperatures. The condensation products in the new compositions are prepared using a ratio of about 1.8 to 2.2 moles of fatty acid for each mole of diethanolamine. The claimed composition comprises adding a water-soluble lower alkanoic acid, i.e., formic acid, acetic acid, propionic acid or butyric acid, or mixtures thereof, to the above-mentioned condensation product at a temperature at which no substantial further condensation occurs. It is manufactured by Temperatures during the addition of the lower alkanoic acid can range from about 10°C to about 100°C, preferably from about 20°C to about 50°C. Substantially all of this lower alkanoic acid added to the composition can be titrated with the alkali metal hydroxide, indicating that a hydrogen bonded acid complex is being formed rather than a salt. Infrared and proton magnetic resonance spectroscopy supports the theory that the resulting composition is an acid complex, but the elucidation of this structure is not certain and the present composition is not limited thereby. Diethanolamine/ _C1 - _C4 alkanoic acid derivatives of fatty acids are charged to a flotation medium dispersed in fuel oil. Preferably, the alkanoic acid derivative is
from about 0.1 to about 70% of the total fuel oil dispersion, more preferably
Consisting of 0.25-50% by volume. This fuel oil dispersion is
It is believed to be a new composition. Similarly, compositions comprising an alkanoic acid derivative and a blowing agent and optionally further a fuel oil are believed to be new. Example 6 A 1:2 condensate of DEA/TOFA and its acetic acid derivative is used in a coal flotation plant. The acetic acid derivative consists of 0.5 mole of acetic acid for each mole of condensate. Add conditioner to No. 1 diesel oil in an amount that increases the volume by 10%. A mixture of condi- tioner and No. 1 diesel oil was added to a tank used to collect less than 100 mesh coal per minute before introducing it into the four banks of the Daniel flotation cell.
Introduce at a speed of ^200cm3 . In one example, diesel oil alone is introduced for comparison. The PH of the coal slurry in the collection tank is measured for each experiment.
A polypropylene glycol methyl ether blowing agent having a weight average molecular weight of about 400 at 67 cm ³ per minute is introduced into each bank of cells at the air port of the first of four cells in the bank. For each experiment, a sample is collected as the coal feed is introduced into the first cell of the bank of cells. A sample of the material recovered by foam flotation is taken from near the end of the second cell in each bank of four cells. Sample the tail material in the overflow weir above the sand gate. The coal feed, flotated material and tail material in each instance are dried and then weighed. 1 g samples of coal feed, flotated material (or concentrate) and tail material are then each combusted;
Measure the weight of unburned ash. The difference in the weight of each of these fractions before and after combustion is taken to be the weight of coal present in each fraction. The percentage of ash-free or "clean" coal recovered is then calculated by the following formula: Percent clean coal = 100 x C(F-T)/F(
C-T) where: C = 100 - (percent ash in concentrate) F = 100 - (percent ash in feed) T = 100 - (percent ash in tail material) The results and identification parameters are displayed in the table. [Table] The data shown in the table is within the scope of the claims.
Acetic acid derivatives of DEA/TOFA condensates are much more effective than diesel oil alone or diesel oil containing DEA/TOFA condensates but no acetic acid in flotating some types of coal in commercial flotation operations. shows.

Claims (1)

[Scope of Claims] 1. In a foam flotation method for beneficiation of coal, the method comprises: (a) sorting the coal to separate flotation size particles; and (b) a fuel oil collector and formula. [wherein R ₁ is β- having 2 to 5 carbon atoms]
is a hydroxyalkyl group or an inert substituted β-hydroxyalkyl group; and R ₂ and R ₃ are independently R ₁ , hydrogen, an alkyl group of 1 to 4 carbon atoms or a group of the formula (wherein y is 2 or 3 and R ₄ and R ₅ are independently R ₁ , hydrogen or 1-4
is a monovalent group corresponding to the alkyl carbon atom of ) ] and a condensation product of an alkanolamine corresponding to at least 0.8 mole of fatty acid or fatty acid ester per mole of the alkanolamine, or an acid derivative of this condensation product A method characterized in that separated coal is suspended in a foamy aqueous medium containing. 2. The method according to claim 1, wherein the coal is bituminous coal with an oxidized surface. 3. The method according to claim 1, wherein the β-hydroxyalkyl group is β-hydroxyethyl. 4 R ₂ is β-hydroxyethyl or hydrogen, and R ₃ is of the formula (In the formula, R ₄ and R ₅ are each β-hydroxyethyl or hydrogen, but at least one of R ₂ and R ₄ is β-hydroxyethyl.) A method according to claim 1. 5 The molar ratio of fatty acid or its ester to alkanolamine in the condensation product is from 1.5:1 to
5:1. 6. The method of claim 1, wherein the coal is flotated in the presence of a _C1 - _C4 monocarboxylic acid derivative of the condensation product. 7. A process according to claim 6, in which the coal is flotated in the presence of acetic acid or propionic acid complexes, condensates, with the proviso that for each mole of condensate there is 0.5 mole of acetic acid or propionic acid. . 8. The method of claim 1, wherein the foamy aqueous medium contains an effective amount of a conventional blowing agent. 9 A conditioner for coal flotation containing the following reaction products: (1) a condensation product of diethanolamine and a _C10 to _C24 fatty acid condensed in a molar ratio of 1:2; and (2) moles of the condensate. Half equimolar amount of _C1 - _C4 monocarboxylic acids or mixtures thereof, based on number. 10. The conditioner for coal flotation according to claim 9, wherein the fatty acid is a tall oil fatty acid or a mixture of tall oil fatty acids. 11. The conditioner for coal flotation according to claim 9, wherein component (2) is acetic acid. 12 Furthermore, add fuel oil to a proportion of 0.1 to 0.1% of the total volume of the reaction product.
Coal flotation conditioning agent as claimed in claim 9, containing in such an amount that it constitutes 70% by volume. 13. The coal flotation conditioning agent according to claim 9, further comprising an effective amount of a blowing agent.