DE3509712C2 - - Google Patents

Description

The present invention relates to a method for ver reducing the viscosity of lye from a pulp digestion process or of lignin sulfonate solutions.

A lignin sulfonate solution is used hereinafter Sugared waste liquor from a pulping process understand.

When pulp is broken down after a sulfate or Sulfite process produces a significant amount of waste liquor, which both for reasons of economy as well Recycled for reasons of environmental protection should be.

During the leaching from a sulfate process mostly burned, leaching from a sulfite process often separated into several components. The main components of the leaching of a sulfite process are Lignin sulfonates, which are used for a further purpose can be. For this, the original (original) Waste liquor for example by reprecipitation, condensation, alkaline or thermal treatment, fractionation or Cracking processed further.  

The leaching before the Incineration or further processing as far as possible concentrated, d. H. drawn off as much water as possible, to achieve a volume reduction. Also Lignin sulfonate solutions are processed before further processing processing concentrated.

However, the problem arises that with increasing Concentration the viscosity of the leachate or solutions increases rapidly, so that the leaching or solutions high dry contents (more than 50% by weight) and low Temperatures, especially below about 15 ° C, are no longer pumpable.

Table 1 shows the viscosity behavior as an example Lignin sulfonate solution (reducing substance, be calculates as glucose, about 12% dry; pH approx. 4) in Dependence on the dry content at different Temperatures shown.

Table 1

So far, therefore, had to storage and storage containers for Concentrated leaching or lignin sulfonate solutions always heated to lower the viscosity or the dryness had to be reduced to 40-45% by weight by dilution with water  to put the leaching or lignosulfonate solutions back into one pumpable condition.

When transporting such concentrated waste liquors or Lignin sulfonate solutions therefore had to be removed speaking arrangements are made to the visco in an area that is appropriate for the used Pumping no problems. Such arrangements such as insulation of the transport container and / or indirect Heating the transport containers during transport are relatively unsafe and very expensive.

Lowering the dry matter content by diluting it with water brings a considerable increase in volume and thus increasing transport costs with what the further processing processing of the leaching or the lignin sulfonate solutions not host can do business.

The invention is therefore based on the object to avoid disadvantages mentioned above and for leaching and Lignin sulfonate solutions in concentrated form new applications with low processing opening temperatures, d. H. them with a simple Process at low temperatures in a pumpable State to move.

This object is achieved in that the waste liquor or lignin sulfonate solution at least one water soluble Amide or imide is added.

The advantages achieved with this invention are special in leaching from a pulp process or lignin sulfonate solutions in high concentration even at low temperatures to make it pumpable again without dilution  Viscosity reasons must be done.

The amide or imide becomes the waste liquor or the Ligninsulfonat solution simply added with stirring without this requires a special device.

The temperature at which the amide or imide increases given, has no influence on the beneficial Er results of the method according to the invention; in general the temperature in the range from 20 to 80 ° C. is preferred are in the range of 40 to 70 ° C.

The amide or imide must in the waste liquor or the lignin sulfonate solution be completely soluble to get the beneficial effect achieve.

The method according to the invention is basically suitable for leaching from any pulping pulp drive, such as B. a sulfate or a sulfite on final process, but especially leaching out an acidic bisulfite digestion process is preferred used from a calcium bisulfite digestion process. He can also use all types of lignin sulfonate solutions inventive methods are successfully subjected.

The liquors from a sulfite digestion process contained in Depends on the type of digestion used Wood a more or less high proportion of sugar, especially hexoses and pentoses. Therefore, this will be waste gene for the production of ethyl alcohol or for the breeding of Yeasts used with advantage, one being desugared (fermented or stitched) waste liquor (= lignin sulfonate solution) remains.  

The addition of the amide or imide can be done either before or even after de-sugaring has taken place, is preferred however, a desugarized waste liquor, i.e. H. a lignin sulfonate solution, used. However, it should be emphasized that the beneficial Effect (reduction in viscosity) regardless is whether a sugary waste liquor or a lignin sulfonate solution is used.

The advantageous effect of the method according to the invention is also achieved regardless of the type of cation that is used as a base in the digestion process. Leaching or lignin sulfonate solutions can be separated from the Waste liquor undergoes reprecipitation to by Aus exchange of the cation to obtain modified lignin sulfonates ten, e.g. B. ammonium lignin sulfonate, sodium lignin sulfonate, Aluminum lignin sulfonate, iron lignin sulfonate, potassium Lignin sulfonate, lithium lignin sulfonate, zinc lignin sulfo nat, magnesium lignin sulfonate, chromium lignin sulfonate and Calcium lignin sulfonate. Such modified lignin sulfo nate can preferably be used for special applications be suitable; for example, Ca and NH₄⁺ lignin sulfonates together with appropriate resins at Span plate manufacturing used. Other areas of application are in the field of concrete coatings, fire solid stones, flotation aids, industrial cleaners, Pesticides and cement additives to name a few to call.

So far, methods for modifying high have failed concentrated leaching or lignin sulfonate solutions (dry content greater than 55%) but mostly due to the high Viscosity of such concentrated solutions Problems with the precipitation process and with the required Separation of the precipitated sludge.

These problems can now be solved by applying the inventions  Avoid the process according to the invention by the waste liquor or the lignin sulfonate before the reprecipitation a water solution added amide or imide. This makes him considerably faster precipitation reaction and an easier one Separation of the precipitation sludge achieved.

The amount of amide or imide that is given to the waste liquor is set can fluctuate within very wide limits. The In principle, the upper limit can be seen where there is a saturated one Solution of the amide or imide is reached; from innkeeper For economic reasons, however, one usually becomes a smaller one Add quantity. Generally the amide or imide in an amount of 0.1 to 40 percent by weight, based on Total mass, especially in an amount of 1 to 10 and most preferably in an amount of 2 to 7 Weight percent, based on total mass, added.

The amides or imides used must be in the the amount applied is completely dissolved in the waste liquor or lignin sulfonate be. As a result, the molecular weight the amides or imides used must not be too high. It was also observed that with increasing molecular weight the nitrogen compound the beneficial effect of Viscosity reduction steadily decreases.

It is preferred for economic reasons of urea. As further suitable nitrogen compounds Examples are acetamide, maleimide and succin to call imid.  

In the following the invention based on selected case play in conjunction with the attached drawing explains in more detail what other advantages and Show possible uses. It shows

FIG. 1 shows the viscosity behavior of a concentrated calcium bisulfitablauge with a dry content of 53 wt .-% and a pH of about 4.5 with and without addition of urea;

FIG. 2 the viscosity behavior of a concentrated calcium lignin sulfonate under otherwise the same conditions as in FIG. 1;

Fig. 3 shows the viscosity behavior of a modified Na-lignosulfonate solution with a solids content of 52 wt .-% and a pH of about 7.5 with and without the addition of urea and

Fig. 4 shows the viscosity behavior of a modified waste liquor (reprecipitated with ammonium as a cation) with a dry content of 45 wt .-% and a pH of about 4.5 with and without the addition of urea.

Fig. 5 shows the viscosity behavior of a modified lignin sulphonate (ammonium lignosulphonate) having a solids content of 45 wt .-% and a pH of about 4.5 with and without addition of acetamide.

Unless otherwise stated, refer to the following following statements all percentages by weight.

Example 1

This example shows the reduction in viscosity a calcium bisulfite waste liquor with a dry content of 53% and a pH of about 4.5. The content of reducing substances, calculated as glucose, was approximately 24% based on absolute dry matter (atro).

The waste liquor was 2.5 or 5% urea, (based on total mass) added.

The results are shown in Table 2 below; the graphic representation is shown in Fig. 1 Darge.

Table 2

The results show that by adding 2.5% urea the viscosity by at least a factor of 2, by adding 5% urea can be reduced by at least a factor of 2.3.

Example 2

This example shows the reduction in viscosity a calcium lignin sulfonate with a Dry content of 53% and a pH of about 4.5 shown.

The content of reducing substances, calculated as Glucose, was 12% dry.

The solution was 2.5 or 5% based on urea Total mass added.

The results are shown in Table 3 and shown graphically in FIG. 2.

Table 3

This example also clearly shows the viscosity ver reduction by using the method according to the invention.  

Example 3

In this example, the method according to the invention to reduce the viscosity of a solution modified sodium lignin sulfonate used.

The dry content of the solution was 52%, the pH was around 7.5.

The proportion of reducing substances, calculated as Glucose, was 12% dry.

2.5 and 5% urea were added to the solution.

The results are shown in Table 4 and shown graphically in FIG. 3.

Table 4

Example 4

This example illustrates the reduction in Viscosity of a concentrated solution of a modified Waste liquor (reprecipitated with ammonium as a cation) with a Dry content of 45% and a pH of approx.4.5.  

The content of reducing substances, calculated as Glucose was 24% dry.

Urea was used as nitrogen compound, which in an amount of 2.5 and 5%, each based on total mass, was added.

The results obtained can be seen in Table 5 and plotted in Fig. 4.

Table 5

A comparison of the results from Example 3 and Example 4 shows that the viscosity reduction according to the Invention is independent of whether a Waste liquor or a sugar-containing lignin sulfonate solution is set.

The above results also show that the advantageous effect of the inventive method un depending on the type of pulp used set or used in the modification cations.  

Example 5

This example shows the reduction in viscosity a concentrated solution of a calcium lignin Sulfonate with a dry content of 53% and one pH value of approx.4.5.

The content of reducing substances is approx. 24% based on the dry matter.

The solution was 2.5 or 5% acetamide based on the Total mass added.

The results are shown in Table 6 below; the corresponding graphic representation is FIG. 5.

Table 6

Example 6

This example illustrates the reduction in viscosity the aqueous solution of a modified lignin sulfonate (Ammonium lignin sulfonate) with a dry content of 45% and a pH of approx.4.5.

The content of reducing substances, calculated as Glucose, was 24% dry.

Succinimide was used as nitrogen compound, which with 5%, based on the total mass, added has been.

The results obtained are shown in Table 7.

Table 7

Claims (10)

1. A process for reducing the viscosity of lye from a pulping process or lignin sulfonate solutions, characterized in that at least one water-soluble amide or imide is added to the leachate or lignin sulfonate solution. 2. The method according to claim 1, characterized in that a waste liquor from an acidic bisulfite digestion process begins. 3. The method according to claim 2, characterized in that a waste liquor from a calcium bisulfite digestion process begins. 4. The method according to claim 1, characterized in that a desugarized waste liquor (= lignin sulfonate) puts. 5. The method according to any one of claims 1 to 4, characterized characterized in that the amide or imide in an amount of 0.1 to 40 percent by weight, based on total mass, adds. 6. The method according to claim 5, characterized in that one of the amide or imide in a lot from 1 to 10 percent by weight, based on the total mass, adds.   7. The method according to claim 6, characterized in that one of the amide or imide in one Amount from 2 to 7 percent by weight based on total mass, adds. 8. The method according to any one of claims 1 to 7, characterized characterized in that the amide Uses urea. 9. The method according to any one of claims 1 to 7, characterized characterized that one as Amide acetamide is used 10. The method according to any one of claims 1 to 7, characterized characterized that one as Imid Succinimide.