The circular economy
The main component of pulp, paper and board is cellulose fibres. These fibres come from plant cell walls (wood, in most cases) and are produced then processed according to the simplified fibre loop shown below :
(1) Managing a forest means carrying out timber harvesting operations (destined for sawmills, wood panel factories and log production, etc.). The paper industry uses mainly wood from thinning (this wood is removed as part of a forestry operation to ensure better growth of the highest value trees), coppiced wood, and tree tops. In some countries (particularly in the Southern Hemisphere), trees come from plantations specifically created to supply wood pulp plants.
(2) Industrial wood waste (from sawmills and plywood factories) is also a raw material recovered by the pulp industry.
(3) Wood fibres are “isolated” using various pulp production processes. The pulp production units are frequently coupled with a paper production plant (integrated mill). Some pulp production facilities produce “commercial” pulp (non-integrated mill) and as such do not have a paper/board production facility.
(4) The paper and board is processed into final products (reams of paper, board boxes, boxes for tissues, etc.).
(5) After having been used, the paper and board products are mostly recovered then sorted by quality and dispatched to paper mills handling recovered fibres.
(6) Recovered fibres are used to produce paper and board and also commercial pulp in some units in Europe. NB: factories using recovered fibres can also process commercial pulp and sometimes even wood.
(7) Only a fraction of paper and board products does not enter the recovery cycle (products unsuited to recycling, inefficiency of collection method, etc.). These items are processed in incinerators or go to landfill.
(8) By-products from the paper-making process (bark, fibres unsuited to recycling, etc.) are reused as energy or as a crop improver (manuring). On-site energy production at paper mills contributes to providing energy for the process. This stage leads to the production of CO2, absorbed by the trees during photosynthesis (wood production).
This fibre loop leads to “inputs” of fibres from forest biomass (or small amounts of annual plants) as well as “outputs” (damaged fibres after repeated recycling, uncollected fibres, etc.).
This economic loop is illustrative of a “circular economy” model and has two notable features:
- Fibrous matter from paper and board is recycled to a high degree.
- The fibres come from a renewable resource thanks to their plant origin and the use of these fibres does not deplete a finite reserve of raw materials (as is the case with fossil fuels or minerals, for example).La matière fibreuse des papiers et cartons est
The type of fibre strongly influences paper or board characteristics. Consequently, for example, long fibres (from coniferous trees) make paper more resistant whereas short fibres give it opacity.
Fibres directly obtained from wood do not always have the same properties as those that have been recycled (this even more pronounced when the fibres have been recycled several times). Fibres from thermomechanical pulp are not the same as those derived from chemical pulps. An important part of paper and board production is therefore finding the right fibre “mix” according to the type of product to be made.
To improve the characteristics of paper and board, other raw materials must be added. These include starch (to boost the paper’s tearing resistance) and minerals (like kaolin or calcium carbonate) to make the paper smoother and thus easier to print on.
The raw materials used by the French paper industry can be broken down graphically as follows: