WO2003004765A1

WO2003004765A1 - Non-woody celulose masses and their production method

Info

Publication number: WO2003004765A1
Application number: PCT/PL2002/000048
Authority: WO
Inventors: Piotr Manko; Halina Stupinska; Roman Madaj; Slawomir Milczarek
Original assignee: Biotek Sp. Z O.O.
Priority date: 2001-07-06
Filing date: 2002-07-05
Publication date: 2003-01-16
Also published as: PL348549A1

Abstract

According to the invention, the cellulose pulps for paper industry are made from stems of a plant of specie Sida hermaphrodita Rusby that is free from resins and fatty acids. This kind of raw material is very easy to obtain and is characterised by ten times higher productivity from an area unit in comparison to traditional materials such as wood. These processes do not require operations connected with neutralisation of resins and fatty acids typically found in waste water resulting from traditional processes.

Description

NON-WOODY CELULOSE MASSES AND THEIR PRODUCTION ETHOD

This invention refers to the bleached and unbleached cellulose masses made from biomass which are used for paper-making.

Cellulose masses both bleached and unbleached are generally made from coniferous and leaf trees. Small percent is made from straw or even sugar beat mass left after sugar extraction.

There is a high demand for various kinds of paper these days, while the raw material base, such as forests, is difficult to renew and has a very low annual growtli. Other raw materials, such as straw contain quite a large amount of mineral substances which damage the machines. On the other hand flax and hemp are very expensive raw materials and can be used for production of special paper only. Other options such as the sugar beet pomace are not practical since the material does not contain enough cellulose and cannot be utilised for wide scale of paper production.

The production method of cellulose pulp begins with raw material preparation, its cleaning and preliminary mechanical treatment that is chopping. Cellulose pulp is obtained in effect of physiochemical processes taking place in treated biomass. Cellulose pulps are used for making paper. The biomass made from leaf and coniferous trees demands a huge amount of work and energy, moreover, forests, which constitute the raw material base for this industry, are usually far from the manufacturer and transport generates additional costs.

Cut down and partitioned trees are transported a long distance to a cellulose pulp producer where it imdergoes bark removal, chopping and then fiirther processing. Teclmological process requires physiochemical processes to obtain bleached or unbleached cellulose pulp.

Leaf and coniferous wood contains some natural resinous substances and fatty acids as well as other high molecular organic forms which in effect of the pulp production process become pollutants difficult to remove from sewage.

Resins and fatty acids are difficult to neutralise. Cellulose pulp and paper producers are entirely responsible for removal of pollutants found in their waste.

Yet another natural substance influencing the cellulose pulp production is the lignin, which is naturally found in the raw material and is removed from biomass by physiochemical processes. The amount of lignin has great influence on energy-consumption, labour demand and the quantity of chemical substances used in the process of biomass digesting.

The total lignin contents for pine tree amounts to 30%, for birch tree it is 22% and cellulose contents are 42,0% for pine tree and respectively 41.0% for birch tree. Pollutants such as resins and fatty acids as well as high molecular components constitute 4,0% for pine and 2,5% for birch.

This invention aims at obtaining bleached and unbleached cellulose pulps derived from perennial crop grown on a farmland in an annual production cycle. The crop of interest is characterised by high growing rate and smaller energy and labour demand. It is also the more friendly for environment. In contrast to technologies described above the cellulose pulps are of comparable quality to the ones produced by traditional methods.

This aim has been achieved by changing the raw material base and alteration of the cellulose pulp production process. The invented method requires stems of a perennial plant of specie Sida hermaphrodita Rusby. Stems are processed with solutions of sulphur compounds and alkalis in raised temperature which allows for bleached or unbleached final result. Teclmologically mature stems of Sida are harvested by a silo-harvester and chopped up into 10-100 mm long pieces, preferably 40-50 mm long. Such prepared biomass is ready for fiirther processing.. It undergoes digesting and lignin separation by solutions of sulphur compounds and alkalis at temperature of 150-170 °C, preferably 160 °C in less than 1 hour.

The excess of Sida hermaplirodita Rusby biomass can be stored without adding preservatives or other substances stopping fermentation.

All solutions generated in the biomass production process are regenerated.

The cellulose pulp made from Sida hermaplirodita Rusby stems in accordance with the invented method meets the same requirements as for products made from wood.

The cellulose pulp imdergoes multistage bleaching with chloric and oxygen bleaching agents. There are significantly less resins and fatty acids as well as chlorophenol compounds involved in bleaching and consequently removed with sewage. There are many times less resind, fatty acids and lignin in the Sida stems than in wood. Bleached cellulose pulp produced from Sida hermaplirodita Rusby in accordance with the invented method meets all the technical requirements binding for wooden cellulose pulps.

Sida hermaplirodita Rusby plantations are located near paper producers. Some are being started there and will supply the raw material needed for paper making in the fiiture.

The Sida hermaphrodita Rusby annual growth is ten times higher than the growth of wood in a forest of a corresponding size. Harvesting requires a silo- harvester to cut down the stems. The process then is simple and requires less energy and labour as compared to traditional forest management. Harvested stems are straight away ready for technological processing as there is no need for removal of bark or chopping required by wooden raw material. This results in significant energy savings equal to 10 kWli Mg of cellulose as compared to energy required to process wood. The content of lignin removed from Sida stems in teclmological process is equal to 19,7% that is much smaller amount than found in wood, while concentration of cellulose contents is 40,6% which is comparable with its contents in pine and birch wood.

Sida hermaphrodita Rusby does not contain any resins or fatty acids that makes it very useful for cellulose pulp production and has a positive impact on environment quality as the composition of water is less haraiful.

In comparison to the traditional raw material it is some 20% less costs to produce cellulose pulp from Sida stems and in accordance with the invented method as it is less polluting (less lignin) and requires less chemical agents.

The examples of practical application of the invention are following:

Example I

Once the stems of Sida hermaplirodita Rusby become teclmologically mature they are harvested by a silo-harvester and chopped up into 40-50 mm long pieces. Such prepared biomass is stored in a stockyard and then digested in a process controlled boiling tank with digesting sulfite liquor. Active alkalis are added in the amount of 180 kg/Mg of raw material, module 3:1, reaction time 45 minutes at temperature of 160°C. Once the treatment is finished the contents of the boiling tank are shifted into a blowing vessel where multi-stage washing on pressure filters takes place. The pulp is afterwards cleaned and sorted. The Sida cellulose pulp achieved digestion level of 48 units of kappa number and with 57% productivity that is 4-5% higher than in case of cellulose pulps made from pine wood of similar digestion. The obtained resistance parameters allow for the use of this cellulose pulp for packing paper production. They are identical as in case of cellulose pulps made from wood. Example II

The raw material prepared as in example 1 is placed in a process controlled boiling tank and treated with digesting sulfate liquor. Active alkalis were added in amount of 250 kg/Mg of raw matter, module 3:1, reaction time 45 minutes at temperature of 160°C. Once the treatment is finished the contents of the boiling tank are shifted into a blowing vessel where multi-stage washing ^"on pressure filters takes place. The pulp is afterwards cleaned and sorted. Cellulose pulp was obtained at 49,0%. Multi-stage bleaching process starts next which requires regular equipment used for bleaching as well as identical conditions as in case of bleaching wooden pulps. Cellulose pulp under discussion was obtained at 43% productivity and was characterised by a high degree of white colour, which is 88,7%. The obtained resistance parameters are comparable to corresponding pulps made from wood.

Cellulose pulp production from wood is connected with yet another drawback that is neutralising hannful waste such as slabs. There is no such a problem with the Sida raw material and the invented production method.

Claims

1. Unbleached and bleached cellulose pulps from biomass treated with sulphur compounds solutions and alkalis at raised temperature characterised in that cellulose pulps are produced from stems of a perennial plant of specie Sida heπnaplirodita Rusby.

2. The method for production of bleached and unbleached cellulose pulps characterized in that the teclmologically mature stems of said plant are cut down by agricultural machines, particularly by silo cutters which at the same time chopped up stems into 10-100 mm long pieces, preferably 40-50 mm long pieces.

3. The method according to claim 2 characterised in that the excess of harvested biomass in the foπn of chopped stems is stored without any preservatives or protection agents against fermentation.

4. The method according to claim 2 and 3 characterised in that the chopped up biomass is directed directly to the process of digesting and separating the lignin by treatment with sulphur compounds and alkalis at the temperature of 150- 170°C, preferably 160°C within less than 1 hour.

5. The method according to claim 2 and 3 characterised in that solutions without resins and fatty acids from digesting biomass process, are directed to the regeneration without their separation.