| Cuba-9 High-Yield Bagasse Pulping | Cuba | - | Pilot scale |
MANUFACTURE OF PAPER AND PAPER PRODUCTS # 22
Background
This case study was submitted on the part of the Working Group on Cleaner Production in Pulp and Paper Industries in the framework of the UNEP IE/PAC Cleaner Production Program with the support of the Technical Research Center of Finland's Non-Waste Technology Research Unit.
The Cuba-9 Experimental Center is studying the applications of high-yield (CMP) bagasse pulping to small scale mills. The aim is to offer an integrated package consisting of a more energy efficient sugar mill with surplus bagasse, a pulp and paper mill based on a low-cost high-yield pulping process, plus animal feed and other by-products.
Cleaner Production Principle
New technology
Cleaner Production Application
Bagasse, a by-product of the sugar industry, is obtained after milling the cane to get the juice from which sugar is made. Bagasse is generally used as fuel in the mill.
Whole bagasse is thoroughly depithed at the sugar mill. The pith is used either as a fuel for the sugar mill's boiler or, mixed with other ingredients, as a cattlefeed or fertilizer. Wet, clean fiber is dewatered in a screw press, and chemical pre-treatment using NaOH carried out in a specially-designed mixer-impregnator. Treated fiber is dewatered in a second press before two-stage refining. After latency removal, the refined pulp is diluted for screening, and centricleaning with an intermediate stage of reject refining. Bleaching is by peroxide treatment at high consistency, and is followed by dilution and pH control using sulfur dioxide. After final washing in a vacuum filter the pulp is held in a storage tower ready for use on the paper mill.
The semi-commercial pilot plant consists of:
| A 20 000-ton bagasse storage yard, with microbiological treatment facilities. |
| A flexible pulp line which can make high-alpha (dissolved grade) chemical pulp 5 tons/day; bleached paper grade chemical pulp 12 tons/day; semi-chemical pulp 15 tons/day; chemi-mechanical pulp 20 tons/day; or mechanical pulp 20 tons/day. |
| A 60-m/min paper machine suitable for newsprint and printing/writings up to 120 g/m2. Wire width is 1,2 m and trim up to 0,86 m. |
| A 1,2-m trim pulp drying machine for board grades, fluff pulp and chemical pulp both in reels-and sheets. Capacity is 3-12 tons/day depending on pulp type. |
Trials on the semi-commercial line have been conducted and pulp as well as paper has been produced. Experiments on the second main objective of Cuba-9, the manufacture of bagasse dissolving pulp, have been underway since September 1988.
After 18 months of basic research and trials, Cuba-9 has succeeded in producing the first commercial bagasse chemical pulp used for fluff pulp.
High-yield bagasse pulp :
| Material Category | QTY Before | QTY After |
| Waste Generation | N/A | |
| Feedstock Use : (wet) | 3,2 t/t pulp | |
| Water Use | 100 m3/t pulp | |
| Energy Use | l,l MWh/t pulp | |
| Steam Use | 1,2 t/t pulp |
Environmental and Economic Benefits
The Cuba-9 Experimental Center is equipped with a $30 million pilot plant (1989).
One of the major aims of the technology developed has been to assist the many developing nations which wish to make newsprint from bagasse fibers. The research guidelines have been as follows :
| To use as few pulps as possible in the newsprint furnish, so as to minimize the capital cost of the processing lines; |
| To use simple and relatively inexpensive technology; |
| To use at least 80 % bagasse in the paper furnish; |
| To achieve low pollution levels and develop simple effluent treatment processes; |
| To meet widely-accepted offset newsprint standards. |
In a simple concept of the sedimentation in external treatment, an industrial scale high load clarifier for pith has been constructed in Cuba-9.
Constraints
Bagasse pulp is more difficult to wash since they have worse draining properties (20-25 oSR) than wood (12-16 oSR). A good depithing increases the filter washing loads by almost a unit.
Contacts
Review Status
This case study was submitted by the UNEP Working Group on Cleaner Production in the Pulp and Paper Industries, based at the Technical Research Center of Finland (address above) in 1992, as part of a contract for UNEP IE. Before submission, the case studies were reviewed at the Center. They were edited for the ICPIC diskette in June 1997.
Subsequently the case study has undergone another technical review by Dr Prasad Modak at Environmental Management Centre, Mumbai, India, in September 1998.