Bagasse, by virtue of its cellulose, pentosans & lignin content has many other alternative uses, resulting the production of much value – added products such as Market Pulp.
Market Pulp -
Market pulp is defined as pulp, which is sold in open market in the shape of pulp & excludes any pulp used for captive consumption in a paper mill.
The market pulp business is dominated by five competing countries, Canada, USA, Sweden, Finland & Norway, which are often called ‘Nordic’ group. 70% of the annual world sales of pulp is met by these countries, in which Canada alone has a share of 25% in the global market. Canada exports 90% of its pulp production.
There are thousands of different types of paper & paper board products in the market. The manufacturer of different kinds of paper like newsprint, writing & printing papers, catalogue papers, tissue papers, craft / packaging papers etc. require different kinds of pulps like Thermo- mechanical, Chemi-thermo-mechanical, Semi-chemical, Chemical pulp etc., in various combinations. All these types of pulps cannot be economically manufactured by each & every paper mill. Hence it is economical for them to purchase the market pulp.
Many small scale manufacturers find it impractical to make any kind of pulp at all, as the initial investment cost is high.
If there is a cluster of small paper mills in any area, a central pulp mill of large size can produce pulp economically.
Market pulp from Bagasse -
One of the prime advantages of using bagasse as fibrous raw material for the manufacturer of pulp & paper is that it does not require debarking & chipping as in the case of wood logs. On the other hand, bagasse requires depithing, but the pith can be used as a fuel for Boiler and also for the manufacture of Furfural.
All ligno-cellulose materials contain cellulose fibres, which are bound together with a glue- like binder called lignin and other organic matters like pentosans, gums, resins, sugar, mineral salts etc., The main task in the manufacture of paper from any of the fibrous raw materials is to separate the cellulosic fibres from lignin & other organic matters & treat them suitably to yield a high grade pulp. This operation is known as ‘Pulping’, which is carried out in all paper factories by adopting any of the following general methods –
1. Chemical / Semi-chemical pulping
2. Thermo - mechanical pulping.
3. A combination of the above.
1. Chemical / Semi-chemical Pulping processes –
In the chemical process, bagasse is cooked in a chemical solution containing sodium sulphate / sulphite in a closed vessel with steam at high pressure to separate the lignin bonding.
In Semi-chemical pulping, a mild chemical treatment is given to bagasse just to soften the lignin bonding. The material is then cooked in digesters & broken by using an impeller / disc refiner.
For starting these processes, depithed bagasse is a promising raw material, which can be supplied by the Sugar factories.
2. Thermo - mechanical Pulping process
In this process, some sort of mechanical force is used to separate the fibres from the lignin bonding.
The critical equipment is called Pressurised Refiner or De-fibrator, in which two disc shaped rough surfaces
rotate in opposite direction. Due to this high speed rotation in opposite direction, the fibres are torn apart. Bagasse is steam - cooked in a digester prior to refining, to soften the fibres.
A second atmospheric type Refiner performs the second stage refining operation to yield the required quality of mechanical pulp.
Sugar factories can additionally install these equipments to supply thermo-mechanical pulp to the Craft Paper units.
3. A combination of the above –
Specific pulping technologies are adopted as per the type of paper required. In printing & writing papers, chemical / semi-chemical pulp is mainly used whereas in newsprint & craft papers, thermo-mechanical pulp is largely used. Normally, a combination of many types of pulps prepared from various processes are used in paper making to achieve the desired qualities.
In other words, Thermo - Mechanical Pulp is used for the production of unbleached papers like newsprint & craft papers for packaging also for medium brightness book papers, writing & printing papers.Chemical pulp is used for papers of highest brightness.
TNPL in India uses mechanical pulp from bagasse for the manufacture of newsprint, which gives vital properties of high opacity, rapid ink absorbancy, softness, bulk & good printability. The pulp is made from the thermo - mechanical process. Their newsprint consists of 50% bagasse mechanical pulp, 35% bagasse chemical pulp & 15% Eucalyptus chemical pulp. The performance of the bagasse newsprint produced from the above formula is good on high speed printing machines.
India is importing 2-3 lakh tons of various grades of pulp at high prices from Rs 20,000/- to Rs. 25,000/- per ton. In view of the market opportunities, the following projects can be set up –
1. Bagasse–based TMP (Thermo– mechanical pulp)Plant –
This Plant separates the lignin – cellulose bond by using Thermo-mechanical energy from the refiner / de–fibrator. TMP Plants are offered based on bagasse, with a minimum capacity of 50 tons per day. Individual units upto 200 tons per day can be set up in a single location, which will add good value to the bagasse. Though TMP is not traded now-a-days, it is a very promising rawmaterial to make craft/packaging paper from bagasse.
2. Bagasse–based CTMP (Chemi–thermo mechanical pulp) Plant –
This Plant also separates the lignin from cellulose by chemical & thermo-mechanical action, using de-fibrators. CTMP Plants are offered based on bagasse with a minimum capacity of 50 tons per day and upto a bleaching of 60 ISO. individual units upto 100 tons per day can be set up in a single location, which will add very good value to the bagasse. CTMP/bleached CTMP is largely imported into India by the newsprint manufacturers.
The pay-back period on all the above pulp projects is less than 3 years.
For more details, please contact –
Goodrich Sugar & Chemical Complex Limited
No. 16, 2nd Main, 2nd Cross,
AECS Layout 3rd Stage,
Sanjaynagar, Bangalore – 560 094,
|Ph: 0091 - 80 – 23411400|
Fax: 0091 - 80 – 23410388