WO1992004092A1

WO1992004092A1 - Use of glycerine ethers as dewatering aids for solids

Info

Publication number: WO1992004092A1
Application number: PCT/EP1991/001626
Authority: WO
Inventors: Rita Köster; Maria Liphard; Gilbert Schenker; Gerhard Stoll
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1990-09-04
Filing date: 1991-08-27
Publication date: 1992-03-19
Also published as: DE4028026A1; AU8404391A; MX9100918A; ZA916982B

Abstract

The use is disclosed of 1 to 3 free hydroxy group containing glycerine ethers having general formula (I), in which R?1, R?2 and R?3 are substituents from the group composed of hydrogen atoms, alkyl groups with 8 to 22 carbon atoms and hydroxy-alkyl groups with 8 to 28 carbon atoms, and the sum of x, y and z is a number in the range from 1 to 20, provided that (a) at least one of the substituents R?1, R?2 and R?3 is not hydrogen and (b) at least one of the substituents R?1, R?2 and R?3 is hydrogen, when one or 2 the substituents R?1, R?2 and R?3 are alkyl groups with 8 to 22 carbon atoms. The use of such ethers as dewatering aids for aqueous, finely powdered solid materials allows solid materials to be obtained with a low water content without foaming of the separated water.

Description

Use of glycerol ethers as auxiliaries for solid drainage

The invention relates to the use of 1 to 3 free hydroxyl-containing glycerol ethers of the general formula I.

in the

R--, R ² and R-3 are substituents from the group formed by hydrogen atoms, alkyl groups with 8 to 22 carbon atoms and hydroxyalkyl groups with 8 to 28 carbon atoms and the sum of x, y and z is a number in the range from 1 to 20 is

with the proviso that na) at least one of the substituents Rl, R2 and R-- is not hydrogen and

b) at least one of the substituents R- ¹ , R-- and R3 is hydrogen if one or 2 of the substituents R - * -, R2 and R3 are alkyl groups with 8 to 22 carbon atoms,

as an aid for the dewatering of water-containing fine-particle solids.

In numerous industries, e.g. In mining or sewage treatment plants, large amounts of highly water-containing, fine-particle solids are produced, which have to be dewatered before the solids are processed or landfilled. For example, The dewatering of water-containing hard coal or coke is a central process in the processing of fuels based on coal. The upper limit values for the water content of these materials required by the market are often difficult to meet because e.g. Mined coal is very fine-grained due to the extensive mechanization of underground coal mining. Around 38% of the raw production currently consists of fine coal with a particle diameter in the range from 0.5 to 10 mm; a further 14% consist of fine coal with an underlying particle diameter.

It is known to use surfactants as dewatering aids for dewatering water-containing fine particulate solids, in particular hard coal, by means of which the residual moisture of fine and fine coal can be reduced. The reason for this is the property of the surfactants, to reduce the surface tension and the capillary pressure of the water in the aggregate. At the same time, the work of adhesion to detach the surface water is reduced. This leads to the use of surfactants an improved drainage with unchanged energy expenditure.

Dialkyl sulfosuccinates (US Pat. No. 2,266,954) and nonionic surfactants of the alkylphenol polyglycol ether type [Erzmetall 30, 292 (1977)] have been described as surfactant dewatering aids of the type mentioned above. However, these surfactants have the disadvantage of considerable foam formation, which leads to considerable problems in the processing plants, in particular when water is circulated in the usual way.

The invention is based on the knowledge that glycerol ethers of the general formula I, when used in water / solids systems without foaming, increase the dewatering speed and lower the residual moisture of the dewatered solids.

The alkyl groups with 8 to 22 carbon atoms, which can form the substituents R ¹ , R ² and / or R ³ , can be straight-chain, branched or cyclic; straight-chain alkyl groups are preferred. Typical examples of such alkyl groups are 2-ethylhexyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, octadecyl, eicosyl or docosyl. Instead of the aforementioned alkyl substituents, the groups R ¹ , R ² and / or R ^{3 can} also be hydroxyalkyl groups with 8 to 28 carbon atoms, which are formally derived from the alkyl groups of the abovementioned list with a corresponding carbon number and one or more, in particular one Have OH substituents.

According to their use according to the invention, a good water solubility of at least 0.1, preferably 1 to 50 g / l is advantageous for the glycerol ethers. If glycerol ethers of the formula (I) are used in which R ¹ , R ² and / or R ^{3 are} long-chain alkyl radicals, it has proven advantageous proved to select higher values for the sum of x, y and z within the given limits in order to ensure sufficient water solubility.

The glycerol ethers of the general formula I are known compounds and are described in the published Japanese patent applications 54-93 198 and 58-67 779; they can be obtained, for example, by alkylating 1 mol of an adduct of 1 to 20, in particular 1 to 10, mol of ethylene oxide and 1 mol of glycerol with 1 to 2 mol of an alkyl halide or alkyl sulfate, in particular an alkyl chloride having 8 to 22 carbon atoms, or 1 mol of the aforementioned adduct of ethylene oxide with glycerol is reacted with 1 to 3 mol of an epoxide of an alkene having 8 to 28 carbon atoms, in particular an alkene with a terminal olefinic double bond. Since the addition of ethylene oxide to glycerol already leads to a mixture of different glycerol ethoxylates, and the alkylating agents used for the further alkylation of these addition products (alkyl halides, alkyl sulfates or epoxides), as is customary in fat chemistry, also represent technical mixtures which can also react with different OH groups of the addition products, the glycerol ethers of the formula I to be used according to the invention are product mixtures of different glycerol ethers, so that the numbers given for the formula I for the substituents R ¹ , R ² and R ³ and for the sum of x, y and z are only averages.

According to a preferred embodiment of the invention, glycerol ethers of the general formula I are used in which (on average) 1 to 2 of the substituents R ¹ , R ² and R ^{3 are} alkyl groups with 12 to 18 carbon atoms and (on average) 2 to 1 of the Substituents R ¹ , R ² and R ^{3 represent} hydrogen atoms. According to a further advantageous embodiment of the invention, glycerol ethers of the general formula I are used in which (on average) 1 to 3 of the substituents R ¹ , R ² and R ^{3 are} 2-hydroxyalkyl groups with 10 to 18 carbon atoms and 2 to 0 of the substituents R. ¹ , R ² and R ³ mean hydrogen atoms.

According to a further advantageous embodiment of the invention, glycerol ethers of the general formula I are used in which the sum of x, y and z is an (average) number in the range from 1 to 10 and R 1, R ² and R ^{3 are} as above are defined.

According to a further embodiment of the invention, the glycerol ethers of the general formula I are used in an amount in the range from 0.5 to 10, in particular from 3 to 8, kg per m ³ of the water to be removed from the finely divided solids.

As mentioned at the beginning, the glycerol ethers of the general formula I are particularly suitable for dewatering water-containing, finely divided hard coal or coke; however, they can also be used for dewatering other water / solids systems, e.g. can be used for processed ores or gangue materials in ore mining, sewage sludge or the like. A further advantage of the glycerol ethers of the general formula I to be used according to the invention is that they can be combined with surfactants of different composition, e.g. with dialkyl sulfosuccinates such as di-n-octyl sulfosuccinates or polyacrylamides, which were added to the solids to be dewatered in previous treatment stages, are compatible and can optionally also be used in combination with these surfactants.

The invention further relates to processes for the dewatering of water-containing, finely divided solids, in particular hard coal or coke, in which the glycerol ethers of the general formula I are used as drainage aids; the The parameters to be observed for the structure of the glycerol ethers and the addition of the glycerol ethers to the solids to be dewatered result from the above statements.

The invention is explained in more detail below on the basis of preferred exemplary embodiments.

First, the preparation of a typical surfactant for use according to the invention is explained below (the term "surfactant" used here and below refers to the glycerol ethers of the general formula I).

a) Preparation of an adduct of 5 moles of ethylene oxide with 1 mole of glycerol.

405.2 g of glycerol (4.4 mol) were placed in an autoclave. After adding 5.7 g of a 30% solution of sodium methylate in methanol, the mixture was evacuated at 70 ° C. for 10 minutes to remove the methanol. Then 968 g of ethylene oxide (22 mol) were pressed in portions at a maximum pressure of 5 bar and a maximum temperature of 180 ° C. The product was used without neutralization. The hydroxyl number of the product was 341.9, corresponding to a molecular weight of 310.6.

282 (0.35 mol) of 50% aqueous NaOH were added to 652 g (2.1 mol) of the adduct described above and the mixture was stirred at 150 ° C. in a water jet vacuum (15 hPa) for 2 hours to remove the water. After addition of 103 g (0.35 mol) of sodium Ci2 / l4 fatty alcohol sulfate (C ₂ stiflate: about 70%; Ci4 ~ sulfate: about 30%), the reaction mixture was stirred at 180 ° C. for 8 h . After cooling to 90 ° C., the excess glycerol ethoxylate and the sodium sulfate formed in the reaction were removed by washing repeatedly with water and the product was dried in vacuo (15 hPa). This gave 132 g of a yellow, liquid product (product A; OHZ: 295).

b) reaction of the adduct according to a) with 1,2-epoxydodecane. 223.6 (0.72 mol) of the addition product described under a) of 5 mol of ethylene oxide and 1 mol of glycerol and 4.6 g of a 30% solution of sodium methylate in methanol were placed in a three-necked flask with a contact thermometer and reflux condenser. The flask was evacuated in a water jet vacuum; the methanol contained was drawn off at 80 ° C. for 10 min. After venting with argon or nitrogen, 274 g of 1,2-epoxydodecane were added; the reaction mixture was heated to 160 ° C for 30 min. The epoxide number of the reaction product (product C), determined according to RR Jay, Analyt. Chem. 1964, 3_6_, 667, was 0.18%.

In an analogous manner, by reacting the addition product described under a) of 5 mol of ethylene oxide with 1 mol of glycerol with 1,2-epoxydodecane in a molar ratio of 1: 1 and 1: 3, the products B (hydroxyl number 343; epoxide number <0.2% ) and D (hydroxyl number 204; epoxy number <0.2%).

A washed fine coal with the following analysis data was used in the following exemplary embodiments:

6.8% by weight of water

3.7% by weight of ash (wf; calculated on water-free coal) 27.2% volatile constituents (waf; calculated on water-free and ash-free coal)

The sieve analysis of the fine coal gave the following values:

- 0.5 mm 1.5%

0.5 - 2.0 mm 23.1%

2.0 - 6.3 mm 51.5%

+ 6.3 mm 23.9%.

To determine the effectiveness of the glycerol ethers of the general formula I in dewatering, the fine coal was treated with aqueous solutions of the glycerol ethers of a defined concentration and dewatered under defined conditions; the Residual moisture achieved with and without the addition of surfactant was determined in accordance with DIN 51718 by drying at 106 ° C. and weighing.

The present examples are laboratory tests in which the amounts of surfactant used in kg are based on 1000 kg of the solids to be dewatered (calculated as water-free solids). In practice, the amount of surfactant required will be lower than that used in the examples; in addition, in the practical implementation of solid dewatering, the required amounts of surfactant are used depending on the amount of water to be removed from the solid.

The structure of the glycerol ethers of the general formula I tested and their abbreviations used below are shown in Table 1.

Table 1

Glycerol ether of the general formula I

Surfactant

B

H

CH ₂ -CH (OH) -C ₁₀ H ₂₁

-) Substituents R- ~, R ² and R ³ or ethyleneoxy groups present on average in the glycerol ether molecule Example 1 .

Drainage in the pressure filter.

50 g of coal were placed in 400 ml of distilled water or surfactant solutions in distilled water and filtered after an exposure time of 60 s. For this purpose, a pressure filter was used, which was a closed filter chute which was filled with the material to be dewatered. The drainage was carried out by applying a pressure of 3 bar to the filter. The drainage time was 30 s. A filter fabric with a mesh size of 0.2 mm was used as the filter material.

The tested surfactants, the surfactant concentration of the solution with which the coal was treated, the calculated amount of surfactant per 1000 kg of coal and the residual moisture determined are summarized in Table 2.

Table 2

Pressure filter test

Surfactant surfactant concentration (kg) residual moisture concentration per 1000 kg coal (wt .-%)

(g / i)

ι, o 16 7.3

B ι, o 16 7.3

ι, o 16 8.0

D 1.0 16 7.2

without addition of surfactant 11.6

AI

As can be seen from Table 2, the residual moisture when using the surfactants to be used according to the invention is significantly reduced in comparison to coal dewatered without the addition of surfactants.

Example 2.

Drainage in a centrifuge.

A cup centrifuge was used here, with which centrifugal values of 15 to 2000 can be achieved at speeds of 300 to 3400 rpm. Perforated plates with sieve openings of 0.4 x 4.0 mm were used as the sieve covering for the centrifuge; the surfactants used as filter aids were dissolved in distilled water in concentrations of 0.1 g / 1 and 1.0 g / 1. To carry out the tests, 400 ml of the surfactant-containing solutions were placed in a glass vessel. 25 g of coal were immersed in each of these solutions. The wetting time was 60 s in each case. This was followed by a constant draining time of 180 s for the pre-dewatering of the samples. The values obtained in the preliminary dewatering of the samples, the surfactant concentration and the calculated amount of surfactant per 1000 kg of coal are summarized in Table 3.

Centrifugal parameters of 43.2, 111 and 389 (corresponding to speeds of 500, 800 and 1500 rpm) were set for the dewatering of the pre-dewatered samples in the cup centrifuge. The drainage time was 30 s. The results obtained are summarized in Table 4.

In a second series of tests, a surfactant concentration of 1.0 g / l was tested at a centrifugal value of 111 (corresponding to a speed of 800 rpm) with dewatering times of 5, 10 and 30 s; the results obtained are summarized in Table 5. As can be seen from Tables 3 to 5, all tested surfactants have a very good effect on drainage. Already in the pre-dewatering (Table 3) the effectiveness of the surfactants became clear in comparison to a sample without added surfactants; While the untreated sample had a residual moisture of 43.6% after the dropping time of 180 s, this value could be reduced to up to 26.3% by the surfactants used according to the invention. This corresponds to a relative reduction in residual moisture by approx. 40%.

As can be seen from Tables 4 and 5, a reduction in the residual moisture was achieved both by increasing the centrifugal value and by adding the surfactants to be used according to the invention.

A surfactant solution with 0.1 g / 1 made it possible to lower the residual moisture to 4.0% by weight with a centrifugal value of 111. A surfactant solution with 1.0 g / 1 lowered the residual moisture up to 3.0%. These values can also be achieved with short drainage times.

Table 3

Centrifuge test

Pre-drainage results

Table 4

Centrifugal drainage

Speed (rpm) 500 800 1500 500 800 1500

Centrifugal characteristic 43.2 111 389 43.2 111 389

Surfactant concentration (g / 1) 0.1 0.1 0.1 1.0 1.0 1.0

Residual surfactant moisture

A 4.4 4.0 3.5 4.1 3.0 2.5

B 7.0 5.7 3.6 3.1 2.9 2.5

7.6 5.8 3.8 3.7 3.4 2.2

5.9 4.7 3.1 3.9 3.1 2.7

without surfactant addition 7.8 6.1 3.9 7.8 6.1 3.9

Table 5

Results at centrifugal value 111

Drainage duration (s) 10 30

Residual moisture (wt.%)

3.4 3.4 3.0

3.2 2.9

3.3 ³ , 4

3.6 3.1

6.7 6.1

Claims

1. Use of 1 to 3 free hydroxyl-containing glycerol ethers of the general formula I

in the

R ¹ , R ² and R ^{3 are} substituents from the group formed by hydrogen atoms, alkyl groups with 8 to 22 carbon atoms and hydroxyalkyl groups with 8 to 28 carbon atoms and the sum of x, y and z is a number in the range from 1 to 20 ,

with the proviso that

a) at least one of the substituents Rl, R ² and R ^{3 is} not hydrogen and

b) at least one of the substituents R ¹ , R ² and R ^{3 is} hydrogen if one or 2 of the substituents Λ2 R ¹ , R ² and R ^{3 are} alkyl groups with 8 to 22 carbon atoms,

as an aid for the dewatering of water-containing fine particles.

2. Use according to claim 1, characterized in that in the glycerol ethers of the general formula I 1 to 2 of the substituents R * -, R ² and R ³ alkyl groups having 12 to 18 carbon atoms and 2 to 1 of the substituents R ¹ , R ² and R3 represent hydrogen atoms and the sum of x, y and z is as defined above.

3. Use according to claim 1, characterized in that in the glycerol ethers of the general formula I 1 to 3 of the substituents R--, R ² and R ³ 2-hydroxyalkyl groups having 10 to 18 carbon atoms and 2 to 0 of the substituents R ¹ , R ² and R ^{3 are} hydrogen atoms and the sum of x, y and z is as defined above.

4. Use according to at least one of claims 1 to 3, characterized in that in the glycerol ethers of the general formula I the sum of x, y and z is a number in the range from 1 to 10 and R ¹ , R ² and R ³ as are defined above.

5. Use according to at least one of claims 1 to 4, characterized in that the glycerol ethers of the general formula I in an amount in the range from 0.5 to 10, in particular from 3 to 8 kg per m ³ of the finely divided solids to withdraw water.

6. Use according to at least one of claims 1 to 5, for dewatering water-containing, finely divided coal or coke.

7. Process for the dewatering of water-containing, finely divided solids, in particular hard coal or coke, marked by the use of 1 to 3 free hydroxyl groups containing glycerol ethers according to at least one of claims 1 to 6 as dewatering aids.