It is an old saying that paper quality is actually made in the pulp mill. Today, the biggest challenge for any virgin pulp producer is to produce good quality pulp without adversely impacting our eco-system that covers our water bodies, ground water level and surrounding atmosphere. Naini is an environment friendly paper mill in the first place due to the type of raw material it uses to make paper which is agricultural residue viz. bagasse and wheat straw. It is to our credit that the quality of writing-printing paper produced from agricultural residue is quite matching with the quality of paper being produced from wood. For example, the brightness of some of our qualities is as high as 94%. The other quality parameters like surface properties, strength properties and optical properties are meeting international quality norms for good quality writing-printing paper. Our modern pulp mill is the key towards this achievement. Some of the key technologies employed in our paper mills are described below:
a) Wet Storage
Every cellulosic raw material is degradable. As the raw material is seasonal, Naini has to store bagasse for lean months. The wet storage technology at our mills is developed locally and is the most economical, convenient and effective way of storing bagasse for a very long period without any deterioration of quality of raw material.
b) Wet Washing
The raw material is thoroughly washed in our indigenously designed wet washing system which removes all the dust and foreign material from the raw material. This helps in optimization of cooking and bleaching chemicals.
c) Continuous Pulping
The pulp mills are equipped with state-of-the-art continuous digester that gives both cost and quality benefits. The biggest advantage of a continuous digester is uniform and consistent quality of pulp with optimum consumption of cooking chemicals. The carbon footprints of this technology are quite low.
d) Oxygen Delignification (ODL)
If one has to identify single technology that has contributed maximum towards the improvement in pulp quality along with the improvement in environmental performance, it will certainly be ODL. Naini developed this technology to suit the requirement of agro-based pulp mill by doing lot of in-house R&D. Initially, this technology was used in wood-based pulp mills. Naini was pioneer in adapting this technology in an agro-based pulp mill. The process and equipment engineering was carried out in-house in consultation with world’s leading company Sulzer, which supplied the critical equipment for this technology. The main advantages of ODL are as below:
- Reduction in COD of bleach plant effluent by 35%
- Reduction in chlorine consumption by 35 to 40%
- Improvement in the brightness of pulp
- Improvement in strength properties of pulp
A multi-stage bleach plant helps in producing high brightness pulp (ISO 88%). The bleaching process uses oxygen and Hydrogen Peroxide (H2O2) in addition to Chlorine and Hypo for reduced load in the effluent and better brightness of the pulp.