CA1241015A

CA1241015A - Fluidifier and stabilizer additive and method of preparation thereof

Info

Publication number: CA1241015A
Application number: CA000482623A
Authority: CA
Inventors: Aldo Prevedello; Carlo Piccinini; Edoardo Platone
Original assignee: SnamProgetti SpA
Current assignee: SnamProgetti SpA
Priority date: 1984-05-29
Filing date: 1985-05-28
Publication date: 1988-08-23
Also published as: DD233951A5; NL8501537A; CS251788B2; JPH0665715B2; PL145004B1; IN165180B; FI852114A0; GB2159536A; SE8502510D0; GR851286B; ZA853852B; FR2565124B1; GB2159536B; SU1516015A3; JPS61436A; ES8604291A1; FR2565124A1; AU568935B2; DE3519115A1; GB8513176D0

Abstract

ABSTRACT OF THE DISCLOSURE

A fluidifier and stabilizer additive, particularly suitable for coal suspensions in water, based on sulphonated tar, is produced by oxidation of sulphonated and salified tar, the oxidation being evidenced by the development of SO2 during the sulphonation reaction. The method for the preparation of the additive, consists of contacting tar with liquid or gaseous SO3, tar and/or SO3 preferably dissolved in an halogenated organic solvent, and the solvent is recovered and the oxidized sulphonated additive is salified.

Description

~.24~015 The present invention relates to a fluidifier and stabilizer additive and to the method of preparation thereof.
In particular, the present invention relates to a fluidifier and stabilizer additive for suspensions of solids in liquids and to the method for the preparation thereof.
Still more particularly, the present invention relates to a fluidifier and stabilizer additive for suspensions of coal in liquids and to the method for the preparation ther~
of.
In a more particular way, the present invention relates to a fluidifier and stabilizer additive for coal suspensions in water, and to the method of preparation thereof.
In a still more particular way, the present invention relates to a fluidifier and stabilizer additJiYe for coal suspensions in water, when coal i3 at high conce~traiion i.e., at a concentration of more than 60% by weigh~, in particul~r of from 70 to 80% by weight or more, and to the method for the preparation thereof.
In the following disclosure, we will refer to the case of coalt water suspensions, it being however to be understood that the additive of the present invention can be used wherever fluidification and stabilization ?roblems exist due to the presence of suspended solids.
Fluidifier and stabilizer additives for coal suspen-sions in water are known, which are constituted by sul-phonated and salified neutralized compounds of tars, said sulphonated compounds being obtained by means of the action of anh~rdrous,concentrated or fuming sulphuric acid on tne 12~101~

tars. The sulphonated additives of the known art suffer from the drawback of containing large amounts of alkaline or ammonium sulphates, generated in the neutralization step with alkaline or ammonium hydroxides o~ the sulphuric solution contalning sulphonated tar products.
In order to sulphonate all tar, excesses of sulphur-ic acid have indeed to be used and the alkaline or ammonium sulphates remain inside sulphonated and neutralized tar once that water used to supply the neutralizing agents has been removed.
A second drawback of the additives of the known art consists in that, in order to have better viscosity char acteristics, they must be at least partly condensated with formaldehyde and this imposes an additional step which is very expensive.
It has been surprisingly found that it is possible to overcome the drawbacks of the known art and to have an additive based on salified sulphonated tar havin~ be_ ter properties than the known ones.
A first object of the present invention ls a fluid-ifying and stabilizing additive based on sulphonated and salified tar, characterized in that sulphonated and saliI'i ed tar is oxidized, the oxidation being evidenced by the development of S02during the sulphonation step, the amourt f S02 developed being comprised within the ran~e o~ from

2% to 60% by weight of used tar, preferabl~ o~ from 10%
to 35% by weight.
In the disclosure of the present invention, by the term tar, there are meant pit-coal tar as such, such as that obtained in coke-ovens, in particular by the dis-tillation of coal at 1.100C or higher, the fractions 12~1015 thereof having boiling points comprised within the range of from 10Q and 350C, the residue of pit-coal tar distil lation at 350C, besides tars or tar fractions obtained in petroleum-processing plants.
Tar, whichever it ma~ be, must contain in at least a small percentage of compounds with more than 2 aromatic condensed rings.
A second object of the present invention is the method for the preparation of the fluidifying and stabilizing ad-ditive previously described. The method according to the present invention comprises the steps of:
1) to slowly bring into contact (preferably without with-drawing the reaction heat), tar with liquid or gaseous sulphuric anhydride in the presence of one or more tar solvents, selected from the class of halogenated organic compounds, inert as for the sulphonation reaction, not mixable or poorly mixable with water, preferably select ed among those whose boiling point is comprised within the range of from 30 to 130C, and in particular select ed among carbon tetrachloride, tetrachloroethylene, di-chloroethane.
2) to complete the reaction between S03 and tar at a tem-perature comprised ~ithin the range of from 800C to 140C, preferably of from 90 to 120C, checking the development of S02 until it reaches a value comprised within the range of fr~m 2% to 60% by weight relati-vely to the weight of tar feed, preferably of from 10%
to 35% by weight.

3) to neutralize the solution of sulphonated and oxidized tar with aqueous solutions of basic agents, preferably of sodium hydroxide or of ammonium hydroxide, until a ~2~101~

pH value of 7, and even a pH value of 10 is reached.

4) to remove the solvent or the solvents of the tar by decantation and/or evaporation.

5) to recover the aqueous solution containing the sulphon ated, salified and oxidized additive.

6) to concentrate or possibly dry the additive.
The steps 3 and 4 may be reversed.
According to a particular embodiment of the method of the present invention, tar can be preliminarly dissolv ed in one or more of said solvents and liquid or gaseous sulphuric anhydride may be introduced into tar solution as such, or with it too being dissolved in one or more of ~aid solvents, with the only precaution that the solvents be mutually compatible, i.e., do not give rise to chemical reactions.
According to a second particular embodi~ent of the method according to the present invention, tar, dissolv-ed in one or more of said solvents or not di~soived, can be poured into a solution of sulphur trioxide in one or more of said solvents, ta~ing care, in case that it be poured as a solution, that the solvents be compatible, and however pouring it very slowly, in order to avoid a too violent reaction.
Some Examples ~ill be now given, to the purpose of better illustrating the invention, it being to be under-stood that the invention is not to be considered as being limited in any ways to them or by theD.
Tar used in all the tests of the ~xampLes i3 a tar from coke-oven having a specific gravity of 1.1577 g/cm3 and a viscosity of ô3.81 cSt at 40C.
Example 1 ~41015 The reaction equipment consisted of a 500 cc four-neck flask, provided with a mechanical stirrer with PTFE
blades, thermometer, water-cooled spherical-bulb cooler and loading funnel.
Into the flask 44 g of tar diluted with 100 cc of te trachloroethylene are charged, whilst into the loading fun nel a solution of 53 g of liquid SO3 in 100 cc of tetra-chloroethylene is poured.
The solution of sulphur trioxide is introduced into the reaction flask in about two hours, the reaction flasx being continuousl~ cooled so as to maintain its inner tem-perature in the region of 10-15C.
At the end of SO3 addition, the inner temperature is allowed to increase to 20-25C and then about one hour later the reaction mixture is heated to refluxing tern-perature (about 120C), and is kept at this temperature for one hour.
The reaction mixture is then cooled, it is diluted with water and the resulting raw reaction product is trans ferred into a beaker wherein it is neutralized up to pH

7 by means of an NaOH aqueous solution; the whole mass is then distilled under atmospheric pressure, so as to re-cover the solvent as a water/tetrachloroethylene a~eotrop-ic mixture.
An amount of 975 g of solid-free aqueous solution is obtained, and a 196 cc portion of the initial 200 cc of solvent is recovered.
Na2SO4 content 1.70%
Dry active substance 107 g Sodium sulphate formed 16.6 g Grams of SO2 rormed 2.1 g o~

Example 2 The equipment is as described under Example 1.
Into the flask 43 g of tar diluted with 100 cc ~f carbon tetrachloride are charged, whilst into the load-ing funnel 51.7 g of S03 diluted with 100 cc of carbon tetrachloride are introduced.
In a two hours time the solution of S03 is added, under external water cooling (inner temperature 15-1~C), the reaction mixture is then left one hour at room tem-perature, and is then refluxed ( ~800C) over two hours.
The reaction mass is cooled to room temperature, is diluted with water, transferred into a beaker washing again the flask with water, and is neutralized up to a pH value of 7 with an aqueous solution of sodium hy-droxide.
The azeotropic mixture carbon tetrachloride/water is distilled off as the overhead fraction, an aqueous solution of 1176 g being obtained as the residue.
Na2S04 content 1.7%
Dry active part 94.5g Sodium sulphate formed 20 g Grams of S02 formed 2.6g Examples 3-17 Examples from N 3 to N 17 have been carried GUt under the identical experimental conditions as for tem-perature, tar and S03 dilution in the solvent, and time of S03 addition to tar.
Equipment: see Example N 1.
Reaction route: into the flask, tar ~iluted with 100 cc of tetrachloro-ethylene (TCE) is charged and inside the funnel, S03 diluted with a further 100 cc of TCE is charg-~2.~0~5 ed.
The addition of S03 solution is carried out in about 90' with the reaction flask being externally water-cool-ed (inner temperature 10-15C).
The reaction mass i3 then ma ntained at room tem-perature (about 20-30C) for one hour and is then reflux ed one hour at 120C. The reaction mas is cooled to room temperature, is diluted with water and is then neutrali~-ed with aqueous sodium hydroxide. The most of the solvent is separated as the lower phase in the end reaction mix-ture after the neutralization thereof and is partly re-covered as an azeotropic mixture with ~,rater. The o~erall recovery of the solvent i3 of about 96-97%.
The data relating to these tests are reported in Table 1.
The discharge gases (~ostly constituted by S02 ac-companied by some traces of SC3) have ~een analyzed in all examples Dy absor~ing them downstream of the cooler in a trap containing a titrated NaOH aqueou3 solution.
Example 18 The equipment is as described under Example 1.
Charge inside the reaction flask: 80 g of S03 dilut-ed with 100 cc of TCE.
Charge inside the dropping funnel: 44 g of tar dilut-ed with TCE.
The solution of tar is added to the solution of S03 in about 50' while the temperature of the reaction mix-ture increases progressively from 22 to 72C; the reac-tion mass is then heated up to ,20~, the temperature 3 being maintained at this value for one hour. The most of the solvent is then decanted at 80~C. The flask is ~10~

then immersed in a thermostatic bath at 140C.
The most of the solvent is recovered in a time of 80' (recovery about 98%). The reaction mixture is neu-tralized while being still hot (80-850C) up to pH 7 with 5 NaOH at 15~/o concentration and is then diluted with wa-ter.
An amount of 795 g of aqueous solution is obtained.
Sodium sulphate content 2.9%
Dry active part 92.9g Sodium sulphate 23.1g S2 developed during the reaction 13 g Organic sulphur 14.3 Example 19 Equipment as under Example 1.
Charge inside the flask: 44 g of tar diluted with 326 g of TCE.
Charge inside the dropping funnel: 81 g of liquld so3.
The addition of liquid S03 to the solution 3f ~ar is carried out in a time of 40', without external cool-ing of the reaction flask. (The temperat~lre, initially of 23C, increases up to a peak value of 90~C and is o~
65C at the end of the addition).
The reaction mixture is heated to 20C ~n a time of 15 minutes, and is kept at this temperature for a time of one hour.
The solvent is then decanted at about 90C (recover-ed 274 g of TCE), the reaction flask is ~hen immer3ed in a thermostatic oil bath a~, 132-134C to the pur?ose of 3 recovering the solvent by distillation. ~y means of this second operation the residual TCE is recovered. The ~Z41015 residual mixture is neutralized at about 80-gooc with an aqueous solution of NaQH up to pH 7. Weight of the end aqueous solution of sulphonated-oxidized and salifi ed tar: 477 g.
Na2S 4 6.8%
Dry active part 97.5g Sodium sulphate 32.4g S2 developed 13.9g Organic sulphur 17.1g Example 20 Equipment as under Example 1.
Charge inside the reaction flask: 44 g of tar dilut-ed with 327 g of TCE.
Charge inside the dropping funnel: 79 g of liquid S03.
The S03 solution is added to tar ln a time of 40', without external cooling of the reaction flask. (Inner temperature, initially of 21C,, increases up to a peak value of 90C and at the end of S03 addition is of 65C).
The reaction mixture is then heated up to TCE boil-ing temperature (about 120C) in a time of 15', it being then maintained at this temperature for one hour. The most of the solvent (270g) is then decanted off at about 85C, the reaction flask is then immersed in a th~rmostatic oil bath at 1~0C. The residual solvent is collected in a time of two hours. The solid residue inside the flask is neutralized with aqueous sodium hydroxide up to pH 7.
Weight of the end aqueous solution 474.4g Sodium sulphate content 7.4%
3 Dry active part 93.9g Sodium sulphate 35.1g ' 1v .

S~2 developed during the test 13.1g Organic sulphur 15.4g Comparison Example N 1 Equipment as described under Example N 1.
Reaction route. Into the flask, 38.8 g of tar dilut-ed with 200 cc of tetrachloroethylene are charged, whilst inside the loading funnel 43.8 g of liquid S03 are placed.
. This latter is introduced into the reaction flask, exter-nally cooled with running water, so as to always keep the internal temperature in the region of 17-20C, in a time of about 80 minutes. The mixture is then kept under stir-ring for further 4 hours, always maintaining its inner tem perature in the region of 17C. The mixture of sulphonat-ed tar is then neutralized up to a pH ~alue of 7 with a-queous sodium hydroxide.
The solvent is then reco~rered by azeotropic distil-lation.
An amount of 897.3 g of aqueous solut-on is s~tain-ed.
Sodium sulphate content 3.82%
Dry active part 63.9 g Sodium sulphate 34.3 ~
S2 developed lower than ana-lytical limit Organic sulphur 9.2 g The so-obtained product does not have dispersing prop erties.
Comparison Example N 2 Equipment as descri~ed under Example N 1, with the exception that the reaction flask is of 250 cc instead of 50~ cc.

lZ4~

~eaction route: Inside the flask 17.0 g of tar dilut-ed with 50 cc of TCE are loaded.
Inside the loading funnel 31.8 g of S03 diluted with 50 cc of TCE are placed.
This latter is charged into the reaction flask, under external cooling with running water so as to maintain the inner temperature in the region of 16-180C, in a time of about 135'. The mixture is then ~ept under stirring for further 1301 always at a temperature of about 18C.
The reaction mixture is then neutralized with a sodium hydroxide aqueous solution up to pH 7.
An amount of 787.4 g of aqueous solution of sodium salt of sulp~onated tar is obtained.
Sodium sulphate content 1.45%
Dry active part 58.6 g Sodium sulphate 11.4 g S2 developed during the reaction lower than ana-lytical limit Organic sulphur 9.4 g The so-obtained product does not show dispersin~ prop-erties.
Water/coal dispersion viscosity measurements To the purpose of evaluating the various dispersant samples (both of the herein disclosed structure and a-vailable from commerce), viscosity measurements have been carried out at different speed gradients b~ means of a ro-tational viscometer Haake RV12, equipped with an MVI sensor and M500 measuring head.
To that purpose, 70 g of coal of particle size <60 mesh and moisture content <0.5% are weighed in a 200 cc beaker, and an aqueous mixture of the dispersant being ~'~,4~0~;

examined is added, so as to have in all:
70 % by weight of coal 29.5 % by weight of water 0.5 % by weight of dispersant The products are mixed by means of a stirrer INith two metal whisks for 1' at 650 rpm and for 2' at 1200 rpm.
The suspension so obtained is introduced lnto the outer measurement cylinder of the viscometer, already isother_ ed at 20C, and after 15' of stay at 20~C, the values of shear stress ( T ) at various speed gradients (y) (from 3.8 to about 150 s ) are measured. ~he experimental values so obtained are elaborated using the power or Ostwald equation ~ =K.~
valid for pseudoplastic behaviour.
For each set of experimental measure~ent3 ~-~ the values of K and n and the curve Icalc~~ ,are c with linear regression. Moreover, for the last fiv~ y values tested (i = 37, 60, 75, 12C and about 150 s ! the values of "asymptotic" viscosity ~sympt is calcuiated.
imposing the rectificat ion of ~-y experimental data.
The values obtained for some samples by so operating are as follows:
Dispersant K na3 pt (as~Jmptotic type n Pa.S viscosity Pa.S
DAXAD 15 (com0.91 0.83 ').58 mercial product) Example 18 0.92 0.81 0.61 Example 11 0.87 1.05 0.57 30 Measurements or resistance to she~r stre3s A sample of the dis?ersant according to the invention 12410~

has been compared with a commercial sample (DAXAD 15, Grace Italia) according to the method hereinunder de-fined as "stability as a function of shear stresses".
Into a 1-litre flanged glass reactor, of 10 cm in height and 10 cm in diameter, 336 g of dry (moisture <0.5,~) coal with particle size<60 mesh and a solution of dispersant in water are introduced, so as to have at the end of the loading:
70/0 by weight of coal 29.5 % by weight of H20 0.5 % by weight of dispersant The mixture is stirred with the reactor being open to the atmosphere, by means of a whisk-stirrer for 2' at 650 rpm and then for 10' at 1200 rpm.
The flange is closed, at the 200 ml level an impel-ler with a flywheel of 2 cm in diameter is placed and the mixture is kept under stirring at 200 rpm for 24 hours. The stirring is discontinued, the impeller is re moved, and the whole is left to rest over three days.
After that time period, the beaker isinclined and the sludge is poured off.
The results obtained are shown in the following Table by means pf the symbols:
* = case in which all the sludge flows spontaneously ** = case in which it is possible to easily fluidify again by means of a glass rod, or of a similar tool, the residue remained on the bottom **~ = case in which on the bottom a compact deposit not easily withdrawable by means of a spatule or the like is formed.

14.

Charged weights, g Active part concentra-Additive tion of ad-aqueous ditive aqueous Pouring Additive Coal solution Water solution behavicur DAXAD (15) 336 24 120 10.0 **
Example 11 336 36.92 107 . o8 6 . 5 J~ .
s N J 0 ~~D ~ ~r ~ ~ N ~ ~7 J ~ ~ ~ ~ N ~~D `D ~ 0 o t~
~11 O O O O O ~ ~ ~ r- ~ - ~ N N ~1 t~
~rl O
U~

O
,1 ~ ' S 3 ~,r, ~ ~ D ~=~ N 0~ 0 . ~ ~
~ ~) ~ ~r--C~ ~ O N U~Lf) 0 L
C~ O
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O '~
O ~ ~ ~C~` N O N 0 0 0 E . . . . . . . . . . ~ ~ ~ <~
~ ~ O -a~~J N ~J ~ ~ ~U`~L~'~ C~ ~ ~ r r-O C~
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¢ G~~>
C: O J~
E ~a a 3 J~ ~ N t-- 1S N0 ~ 0~ 0 ~t ~0 ~ ~ t-- ~ t--:C
u ~ ~ ~ ~ u~ o H 0 3 0 --~---- N N N N ~ 1 P;
¢
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m u~ o 0 o ~ ~ ~ 0 u~ a~ ~ ~ ~ 0 0 ~, O
¢ ~ ~ '~ 0 ~ N ~) l~ O ~ O ~ 0 C-- -- t Z '~ . J ~ ~ ~ 0 0 O~ 0 ~ ~ ~ O~
C~: C, C) ~ .

:~ O
E~
3 E ~ t~ D 3 u~
,0~ ~ N i~ ~ J 15~ ~ ~) 'D t-- ~D 0 0 0 O
r~
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.

o ~ Il~ N N t~ 3 r- ~O
U~
E ~ ~ O O O O O O l`f) t-- O N \D O
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a ~a ~) J 1~ ~ ~ 0 ~ -- ~J ~ ~ Lr~ ' ~D !~
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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fluidifier and stabilizer additive based on sulphonated and salified tar wherein sulphonated/salified tar is oxidized, the oxidation being evidenced by the development of SO2 during the sulphonation reaction, the amount of SO2 developed being in the range of from 2% to 60%
by weight relative to the weight of tar.

2. An additive according to claim 1, wherein SO2 is developed in an amount in the range of from 10% to 35% by weight relative to tar weight.

3. A method for the preparation of the additive according to claim 1, comprising the steps of:-a) slowly bringing into contact tar with liquid or gaseous sulphur trioxide in the presence of one or more tar solvents selected from the class of halogenated organic compounds, inert to the sulphonation reaction, not mixable or poorly mixable in water;
b) completing the reaction between SO3 and tar at a tem-perature in the range from 80°C to 140°C, checking the development of SO2 until it reaches a value in the range from 2% to 60% by weight relative to the weight of tar;
c) neutralizing the solution of sulphonated and oxidized tar with aqueous solution of alkaline agents;
d) removing the solvent(s) of tar by decantation and/or evaporation;
e) recovering the aqueous solution containing the sulphonated-salified and oxidized additive dissolved, and f) concentrating or drying the additive;

it being possible to invert the steps (c) and (d).

4. A method according to claim 3, wherein in step ( b) the temperature range is from 90 to 120°C.

5. A method according to claim 3, wherein the solvents have boiling points in the range from 30 to 130°C.

6. A method according to claim 3, wherein the solvents are selected among carbon tetrachloride, tetrachloroethylene and dichloroethane.

7. A method according to claim 3, wherein SO2 is developed in an amount in the range from 10% to 35% by weight relative to the weight of tar.

8. A method according to claim 3, wherein the neutraliza-tion is carried out with a sodium hydroxide solution.

9. A method according to claim 3, wherein the neutraliza-tion is carried out with a solution of ammonium hydroxide.

10. A method according to claim 3, 8 or 9, wherein the neutralization is carried out up to pH 7.

11. A method according to claim 3, 8 or 9, wherein the neutralization is carried out up to pH 10.

12. A method according to claim 3, wherein tar is preliminarly dissolved in one or more of the solvents and sulphur trioxide is brought into contact with said tar by introducing it into the solution of tar either as such, or dissolved in one or more of the solvents.

13. A method according to claim 3, wherein tar is brought into contact with sulphur trioxide by pouring tar either as such or dissolved in one or more of the solvents into a solution of sulphur trioxide in one or more of the solvents.