The Production Of Pulp Flashcards
In mechanical pulp: the logs of coniferous trees are saturated with what and debarked?
Water
Three types of pulping
Mechanical, chemical and waste.
In mechanical pulp: how is the lignin softened?
The wood is ground down
In mechanical pulp: how is the ‘ground wood pulp’ formed?
The mechanised forces separate the Fibres.
In mechanical pulp: the pulp is screened to?
Accept 1-2mm pieces
In mechanical pulp: what happens to the larger pulp pieces?
Re-circulated for additional screening.
What is the most widely used method in the UK for producing wood pulp?
Mechanical pulp
In chemical pulp: what happens after de-barking?
The hard and softwood logs are cut into 2cm chips along the grain.
In mechanical pulp: what is the resulting pulp used for?
Low-grade paper such as newspapers
In chemical pulp: what happens after the logs are cut into 2cm chips along the grain?
They are pounded into fragments and screened.
In chemical pulp: what happens to the resulting pulp?
It’s stored and treated with either an acid or an alkali.
In chemical pulp: what is an acid or an alkali added to the pulp?
To break down the lignin
Most … Pulp is made by the alkaline Kraft process or sulphate process. Which pulp?
Chemical
In chemical pulp: what does the alkaline Kraft process or sulphate process use to ‘cook’ the wood pulp?
Caustic soda and sodium sulphate.
The amount of fibre produced is lower than with mechanical methods, but the fibres are longer, stronger and contain fewer impurities. Which pulping does this apply to?
Chemical
What is used for waste pulp?
Recycled paper and board
Waste pulp is used for what and why?
Lower grades of paper as its strength, durability and colour are not as good as virgin fibres.
Virgin fibres are produced when?
Using mechanical and chemical methods.
What is waste pulp often mixed with?
Virgin fibres to produce better quality papers as fibres become shorter be weaker and lose their paper-making qualities.
Which pulp makes use of recycle papers, which are a sustainable resource?
Waste
Which pulp can be bleached to produce higher value-added products?
Mechanical
In mechanical pulp: what is the pulp bleached with?
Peroxide or sodium hydroxide.
