Partner Search

Summary

A Spanish research group from Andalucía has developed a procedure for kraft cooking of lignocellulosic material with low sulphidity alkaline bleaches in the manufacture of paste with direct addition of dihydroxyanthracene disodium salt to the digestor. The group is interested in contact with paper industry to reach a licence agreement of technical cooperation agreement.

Full description

This group has developed a novel paper manufacturing process using forestal or agricultural lignocellulosic materials, those obtained from wastes or by-products of agricultural or forestal processes, resulting in less contamination. Specifically, it involves a process of extended delignification of such materials in which, parallel to digestion, in an auxiliary reactor, anthraquinone is reduced in order to obtain a special salt, as an additive, by means of bleaches and a reducing agent, so as to reduce the contamination caused by the process.
One disadvantage of the process by which cellulose is produced (kraft cooking) is that it must be discontinued if there is a high lignin content in order to avoid parallel degradation of the carbohydrates and consequent losses in yield and paste quality. Later on, the remaining lignin is eliminated in a further bleaching stage using costly and contaminating chemicals. This contamination burden is reduced by decreasing the lignin content in the paste by means of this patent proposing a lengthy delignification treatment (extended delignification) during the cooking process, under conditions guaranteeing the quality of the paste.
It is a procedure for extended delignification in which the additive is obtained as part of the cooking process and is added to the lignocellulosic matter digestor in its most active soluble form and during a period prior to the critical conditions of cellulose degradation allowing, at the same time, reduced sulphidity and, therefore, the environmental effects of sulphur during both the cooking process and the recovery of the black bleach.
Furthermore, the protective effect of the additive upon the cellulose has an associated effect: the improvement of the variables by which the degree of polymerisation of the cellulose is measured, such as viscosity.
• This procedure leads to lower emissions of water contaminants, especially when a comparison is made of the contamination loads of the waste products generated throughout all the stages involved in the production of cellulose paste, including the cooking, paste washing, refining and bleaching processes.

Innovative Aspects

* The delignified forestal or agricultural lignocellulosic matter is created by the waste products or by-products of agricultural or forestal processes; consequently, this method of operation implies an environmental advantage.
* Pastes with a low lignin content are obtained, as well as good mechanical properties (low degradation of the cellulosic polymer).

Partner expertise sought:

- Type of partner sought: Industry
- Specific area of activity of the partner: Paper
- Task to be performed by the partner sought: application and implementation of the technolgy.