DE1517178A1 - Process for making pulp - Google Patents

Description

8 MUNICH 22 ^Y * 1517178

TVIDSKMAXKS-STK. * ■ TKLKlON «I SS SO. EB Bl 82

i. 23365 July 5, 1965

FABRICAS J3 JrAtEL LüHüTO Y rSilA lOßiiül, ci.A. , Aparatado 29-37y, Villa Obre _ö on, Mexico 20, Di ?.

Veri'aiiren for the production of wood sonal beef

The invention meets improvements in Production of wood pulp using the so-called Kraft process.

-. In particular, the invention is based on improvements directed in the production of wood pulp by the aforementioned method, through which a number is very desirable Advantages over the previously known Kraft process for the production of wood pulp can be achieved.

In the previously known Kraft method, such as them in wood pulp and 'paper mills for manufacture

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carried out by wood pulp, form inorganic Sulphides, especially sodium sulphide, the active chemicals in cooking the wood. These inorganic Sulphides are used because they are necessary to obtain pulp which has several desirable characteristics possesses, in particular with regard to the .Festigkeit and others Features: ier bleached or unbleached iulp and the finished product made from this pulp Paper.

The main object of the invention is to provide a process for producing wood pulp by the Kraft process using inorganic sulphides, especially sodium sulphide, but wooei a renewed pulp of Deut for a given Suifi! content of the jvochlauge we α.

Another aim of the invention is creation a process of the kind mentioned, in which the amount of alcohol consumed in the cooking process is substantially reduced can be.

It is readily apparent that the achievement of one or the other of the aforementioned goals and all the more both goals, a very desirable one

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means economic advantage, especially in terms of the economic factors that occur in the operation of a power pulp mill.

Another goal of the invention is creation a method of the type mentioned, in which the properties of the ± uipe, such as their strength and bleachability, are not adversely affected, but despite the increase in pulp yield and / or the reduction in the amount of aluminum consumed in the process can be significantly improved.

Further objects and advantages of the invention will become apparent from the detailed description and the following although show;

1 shows an embodiment in the form of a flow diagram of the invention, as it is preferably in a Kraft-Puipeniuhle can be carried out;

Fig. 2 a! Schauoili with graphic representations, which the ir ^ eonisse of various Strength tests for i-apier show that was made from the xulpe, which results in aer Control test run and in the Pro test run

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(Trial runs) were obtained according to the invention and

3, 4 and 5

graphs showing (a) the accumulative mean yield, (b) the show the accumulative mean value of the alkali consumed or (c) the accumulative mean value of the permanganate number, which mean values in the control test series and in each of the two Trial series, which will be described in more detail below, were obtained.

The objects of the invention are essentially achieved by doing what is conventional in the Kraft process Sodium sulphide used has been partially or wholly replaced by certain organic sulphide-containing compounds which, when added to the alkali, make the alkali more active for the lignin and other constituents of the wood makes.

In particular, in keeping with the foregoing are the organic ones used in practicing the invention sulfur-containing compounds those which the Contain sulfur in divalent form, i.e. compounds that contain two sulfur-bonded valences, such as

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κ _

this is the case with mercaptans and other organic sulfides and disulfides.

It was found within the scope of the invention that if all or a substantial part of the sulfide content of the alkaline cooking liquor is from the aforementioned organic sulfur-containing compounds, instead of wholly or at least more than about $ 90 To consist of sodium or another inorganic sulphide, the pulp yield increases, while at the same time the amount of active alkali required decreases, the permanganate number of the pulp remains the same and the strength as well as the properties of the pulp, especially those that affect the folding strength of the pulp affect the paper made of pulp, are also the same or even slightly improved.

It was found that if z.ü. 25% total sulphide _: content can be used and this total sulphide content is composed of two fractions, namely 22p real ilatrium sulphide and y / o apparent sodium sulphide, the latter fraction being composed of one of the aforementioned organic sulfur-containing compounds or of a mixture thereof consists, like mercaptans, organic sulfides and disulfides, a

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Accompanied increase of about $ 2.0 to $ 2.5 in pulp yield from a decrease of about $ 2-3 in need active alkali compared to the yield and to the active alkali requirement compared to the pulp, which is obtained when working under the same conditions except that the $ 25 Total sulphide content derived entirely from real sodium sulphide will. In the above and in the following description, the real and the apparent Sulphide content in all cases as equivalent sodium sulphide by titration with iodine and expressed as NagO certainly.

The organic sulfur-containing compounds, which can be used for practicing the invention are those which, as mentioned, contain cjsulfur contain in divalent form and have a structural formula selected from the following group:

(a) H-S-R '

(b) R - S - R

(c) RS - SR '

(d) suitable mixtures of two or all of the foregoing,

where R is an alkyl radical and R 'is hydrogen or

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Alkyl radical, which is the same or different of R and wherein each of such alkyl radicals contain one or more hydroxyl or carbonyl groups which serve to increase the hydrophilic properties of the compound.

The organic sulfur-containing compounds used according to the invention can either be pure Mercaptans or consist of organic sulfides or disulfides, or they can be organic sulfur-containing Be compounds collected from the gases released by the stoves, in the latter case some change in the relative lies of the various Components may take place from time to time during a particular operation. bo can according to the invention Benefit from the organic sulfur-containing compounds in the form in which they are in Kraft pulp mills receive, en / earth, drawn v / earth, without there is a need for the various components to clean or separate. It was found in the i-iahmen of the invention that in large-scale operation when using these organic compounds containing sulfur, as they are obtained from Kraft-i'ulpemühlen, small changes in the gases obtained from the cookers only marginally and substantially affect the overall result meaningless influence.

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To demonstrate and evaluate the effect of the organic sulfur-containing compounds mentioned in the manufacture of ground wood according to the Kraft process, the mixed sulfur-containing compounds were collected in a Kraft-Fulpemu.'le, with 23% conventional sulphide content entirely from real sodium sulphide were used. There was a control experiment using the same 2y / o ouifid..ehalts conventional, that is, without adding the organic schv / efelnalti ^ s compounds, carried out during a period of 59 -en Ta. ₁

A series of harvest trials, which extended over a period of 42 days, was then carried out under exactly the same conditions as in the control series, with the exception that the 23 ^c / g suIfid content was made up of two parts or fractions. et.it were, namely aui-j 21, Oje real sodium sulfide and 2, U /. apparent ¹ ov, l: i'i dg ehalt from organic schv / efelnalti en / erbindungen. A second series of trials voi. 30 days Jauer /. ^; urae also-lls under the ^ leic.ien liediiiguny / en carried out with the exception that in this case the sulphide content was increased to ΖΑ, Ρ .'-, Ό, which sulphide ^ .enold was composed of two parts or fractions, namely only. 21,0'f> real ITatriuinsulfid and 3,2ΐ'ο apparent sulfide content from organic sulphurous alti. en / bind en "

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In each of the test series, pure wood was used and the following conditions were met:

The time to increase the pressure in the cookers was a maximum of 2.5 hours5

Time at normal, constant pressure: 0.75 hours,

maximum pressure: 7.5 kg / cra; Maximum temperature: 175 ° C, ratios of Qe3 = i ;; tlau _: depending on the wood: 5: 1} Concentration of the active alkali: 40g Έ :: ₉ 0- / liter,

The obtained in the two series of i-roba experiments Results are shown in Table I below, in comparison with those in the control series. Regarding the numbers given for the accumulative Mean value of the yield is to be heated that this from the actual daily production of the Mill was calculated by taking the one supplied by the mill Total pulp weighed and this total weight accordingly the moisture content of the pulp (10 ^ moisture content) was adjusted to obtain a value for the weight of the air-dry pulp.

Table I.

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Table I.

Control sample test series Test series 1

Trial series 2

Sulphide content
derived from

duration
(Days)

23 / o

39 21 $ real Na ₃ S 2196 real Ha ₂ S

organic 3,2> 'ö organic sulphurous- sulphurous ^ e connections connections

42 30

Cemented conventional sulphide content 23.04 ^.

Mean apparent suIf idfic

22.95 / * 24.19 / *

Accumulative mean value of the yield from the digesters (me- 5 »12 tric tons per cooking process)

5.26 5.28

Accumulative mean value of the permanganate number (Oestrand method)

57.25 58.0

Accumulative mean of the alkali used in the cookers (kg Na ₂ O / 4.39 metric tons of AD pulp)

4.28 4.33

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As can be seen from the valley above. is, with an average apparent sulfide content in the Irobe series of tests, was Ur. 1 of essentially the same level as the mean conventional sulphide content in the control test series, l.li. of about $ 23 in both cases, the accumulative mean yield for the former 5.26 metric tons per cook compared to 5.12 metric tons per cook for the latter. The difference of 0.14 metric tons per Koohprocess corresponds to an increase in the yield of about 2, '~ (' / Ό. At the same time, the accumulative mean value of the consumed Al becomes: ·:. £? II from 4.39 to 4 , 28 kg Ha ₂ O per metric ton of AD-iulpe, which corresponds to a reduction of about $ 2.5 for the trial trial series Mr. 1 compared to the control trial series. These results were however without affecting the accumulative "gown. / erts obtained the permanganate number.

At Jer Irobeversucasrei ^h y ir. 2, tax ".eloher the average value of the apparent sulfide age increased to 24.19 / t (compared to the conventional sulfate value:: ii3 .1ts of about 23yo for the control test pure), the accumulative mean value of the yield was 5.23 metric tons per cooking process in comparison

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to 5.12 metric tons per cooking process in the control test series, which corresponds to an increase of 0.16 metric tons per cooking process, ie an increase of about 3 »1 $. The accumulative mean of the alkali used was reduced from 4.39 to 4.33 kg Na ₂ O per metric ton of AD pulp, which corresponds to a reduction of about 1.4 $. The accumulative mean value of the permanganate number was slightly higher in this test series than in the control test series (58.0 compared to 57.25).

As can be seen from the graphs of the Pig. 3 and 4 show the accumulative means the yield and the accumulative mean values of the alkali consumption in each of the two series of test runs consistent increase compared to the results obtained in the control test series. Those differences, although few in number, are nonetheless economically important to practical ones Operation of a power pulp mill as would be apparent to one skilled in the art is.

In addition, as can be seen from the graphical representation of the Fi ^. 5 it can be seen that these are advantageous Results in practicing the invention without

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significant effect on the permanganate number of the obtained Pulp achieved.

The values of the test results with regard to the Strength properties of ± paper resulting from the after the pulp obtained in the aforementioned control and sample test series are in .Pig. 2 specified. As indicated, the i / erte show in each case the results with one beat time -> iull and with successive ones Striking time intervals of 20 minutes up to a total striking time for a pulp of 80 minutes and in each case after the pulp was bleached to 80 ° GE brightness (whiteness).

lile results from the comparative graphical representations for the three test series, the results show at full and after 80 minutes of stroke time (a) that the length of the ice increases from initially 3.5 to 8.3 ^ ei of the test series Er .. 1 and from the beginning 2.6 to 7.0 in the trial pure Ur. 2 increased in comparison to an increase from initially 3.2 to 7.6 in the control-lversus-pure; (b) that the burst resistance after zeros increased from an initial fourth of about 2.0 kg / cm in all three cases to 4.0 in the trial series

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Nos. 1 and 3.6 increased in the Irobean test series 2 compared to a value of 3 »0 in the control test series; (c) that the tear resistance according to Elmendorf increased from an initial value of about 125 g in each of the two test series to 50 g in test series No. 1 and to 65 g in test series No. 2 in comparison to the control test series, in which latter it decreased from originally 90g to 50g; and (d) the folding resistance from about 50 to about 260 folds in the case of the trial series Ut. 1 and from about 20 to 760 folds in the case of the test series i \ ir. 2 compared to an increase from about 20 to only 180 folds in the case of the control test series.

The use of organic sulphurous Compounds in place of all or one of the sodium sulfide Substantial portion of this is particularly useful and advantageous in those Kraft pulp mills which only have consume relatively small amounts of liatric sulfide and in which elemental sulfur must therefore be added to the digesters in order to obtain a sufficiently high level in them To achieve sulfide content.

As mentioned, there is an important advantage of the invention in the fact that the organic

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sulfur-containing compounds in all Kraft pulp mills are readily available and without the need to clean them or their various components from one another to separate, 'used for the method according to the invention can be. For this purpose you can use the mentioned Connections are re-opened from the gases discharged from the stoves so that the connections can be fed to the stoves again. Such a process achieves substantial savings, the yield is improved and the amount of alumina consumed is reduced.

The course of the procedure described above is in Pig. I, which is shown, the gases released in the digester or in the digesters 10 can be discharged overhead via a line 11 to a condenser 12. The condensed components, such as turpentine and / or water, are discharged from the condenser through a line 14, while the non-condensed gases VO.1! The upper unde of the condenser are fed via a newspaper 15 or 20 to a 3askonaensator 16 or an Absoroer 25, from which the condensed or dissolved organic sulfur compounds are again fed to the digester 10 via the lines 26, 17 and 18, while the inert ones Residual gases

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can be derived from the condenser 16 or from the absorber 25 via lines 27, 21, 22. These two alternatives are shown in FIG. 1, in which case the condensed or loosened compounds can be diverted through a line 26 and / or a line 17 for return to the digester . In any case, the line 8 can be connected to a supply line 30 through which additional organic sulfur compounds are supplied to the digester if necessary or desirable.

Another advantage of the invention is that in large-scale operation, the active alkali in the Wood digestion liquor made from sodium sulfate or sodium hydroxide can be derived during the digestion process. In the Using sodium carbonate, elemental sulfur is also preferably added to the desirable To achieve properties of Kraft-Jruipe, while with n'eh-ien of aolch elemental ochwefel the quality of the Cup of the normally lower quality soda pipe is similar. In each case the choice is either of I.etriumsuxfate or sodium carbonate as an active alkali source for aie implementation of the invention is not only advantageous from the point of view of relative price at any given place and time, but

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also from the additional point of view, ate through the process according to the invention achieves the desirable or even improved properties of Kraft pulp when using sodium carbonate instead of! sodium sulfate is used.

Claims;

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Claims (12)

Patent claims: 1. Process ζμΓ production of wood pulp, characterized in that wood is digested in an alkaline cooking liquor, the sulfides as active contains chemical components of the lye, the sulphide content of the lye not being more than 90% sodium sulphide while the remainder of the sulfide content is supplied by an organic sulfur-containing compound which contains two sulfur-bonded valents and has a structural formula selected from the following group is selected: (a) R - S - R ' (b) R - S - R (c) RS - SR ' (d) a mixture of two or all three forms (a), (b) and (c), where R is an alkyl radical and R ^{1 is} hydrogen or an alkyl radical which is the same or different from R. 2. The method according to claim 1, characterized in that the total sulfide content of the liquor between 909841/1261 - i9 - 8AD ORIGINAL is about $ 23 and about $ 25. 3. The method according to claim 2, characterized ι that the total sulfide content consists of about 21 ^ o sodium sulfide and about 2 "/ o to about 3 $ apparent sulfide content, which latter consists of the organic sulfur-containing compound mentioned. 4. The method according to claim 1, characterized in that that the organic sulfur-containing compound from the gases produced when the wood is broken down is obtained. 5. The method according to claim 2, characterized in that the organic sulfur-containing compound is obtained from the gases released when the Wood. 6. The method according to claim 3, characterized in that the organic sulfur-containing compound is obtained from the gases which arise when the wood is broken down. 7. The method according to claim 1, characterized in that that the organic sulfur-containing compound 909841/1261 - 20 BATH consists of compounds that are recovered from gases that "arise when the wood is slept and to be fed back to the heat setting. 8. The method according to Ansoruch 2, characterized in that that the organic sulfur-containing compound consists of compounds recovered from gases that arise when the wood is unlocked and are fed back to the cooking level. ■ 9. The method according to claim 3, characterized in that the organic sulfur-containing compound is selected from compounds which are recovered from gases that arise when digesting the wood and the cooking stage are fed again. 10. The method according to claim 1, characterized in that let the radical R at least one substituent contains which is selected from the group consisting of a hydroxyl and carbonyl. 11 ο Method according to claim 1, characterized in that the radical λ ^{χ contains} at least one substituent which is selected from the group consisting of a hydroxyl and carbonyl. 9 0 984 17 126 1 - 21 ^ß AO ORIGINAL 12. The method according to claim 1, characterized in that that the radicals R and R 'each contain at least one substituent which is selected from a hydroxyl and a group consisting of carbonyl. 909841- / 1261 Translation of the drawing labels To Fig. 1: Condenser Condensed Turpentine and "ater Relieved Gases from Digesters Digester Alt. "B": Gas Absorber Alt. "A": Gas Condenser Inert Residual Gases Gas Condenser or Absorber capacitor condensed turpentine and t / ater Gases released in the cooker Stove Alternative "B" gas absorber Alternative "A": gas condenser Inert residual gases Gas condenser or absorber Recovered condensed or recovered condensed dissolved sulfur compounds or dissolved sulfur compounds Additional Sulfur Compounds additional sulfur compounds desirable fertilization, if desired. Pig. 2 909841/1261 figure Control Test Run Control test series Trial run Pulp obtained from 37th day of Run Tensile, Km Trial series Pulp received after 37 days Tear length in km Burst kullen, kg / cm ^c Burst resistance according to Mullen in kg / cm Tear, Elmendorf, gr tear resistance in g according to Elmendorf Folding, Folds, folding resistance, folds Beating time, minutes Beating time in minutes Strength properties of the pulp after being bleached up to 80 ° GE brightness Strength properties of the pulp after bleaching up to 80 ° GE brightness ('whiteness degree) Fig. "3 9098A1 / 1261 figure Control Test: Conventional Kraft Cooks without new Sulfur Compounds Accumulative Average of Yield of Digesters, metric tons / cook Average conventional sulphidity Calculated as Control experiment: Conventional Kraft processes without new * sulfur compounds Accumulative mean of the yield from the digesters, metric tons per cooking process Average conventional sulphide content based on February, March First Trial: New Sulfur Compounds being added New Sulfur Compounds February, March First trial with added new sulfur compounds New sulfur compounds Average seeming sulpiiidity Mean apparent sulphide content March, April, May Second trial March April May Second trial attempt May and June May and June 309841/1261 Fig. 4 figure Accumulative Average of active Alkali used in Digesters, kg UapO / metric tons AD PuIp Accumulative mean of the active alkalis used in the digesters, kg Na ₂ O / metric tons of AD pulp figure Accumulative Average of Permanganate! Lumber (Oestrand Method) Accumulative mean value of the permanganate number (Oestrand method) 9 0 9841/1261 Blank page