Subject: Environmental Science / Industrial Processes Difficulty: IELTS Listening Section 4 Good morning. Today, we’re going to explore the lifecycle of paper, focusing on two interconnected stages: primary production from virgin materials, and secondary production through recycling. This is a critical topic, as the global demand for paper products is projected to rise by nearly 40% over the next decade.
The recycling sequence involves six key stages. First, , where paper is graded by type and quality – for instance, office paper is separated from corrugated cardboard. Next is pulping , where the paper is mixed with warm water and agitated in a huge vat called a pulper, breaking it down into individual fibres. paper production and recycling ielts listening
The fifth stage is , where the recovered fibres are beaten to swell and roughen them, improving their ability to bond. Finally, stage six: paper making , where the cleaned pulp is diluted, spread onto a wire mesh screen to drain water, pressed between rollers, and then heated to dry. The recycling sequence involves six key stages
The third stage is . Here, the slurry passes through screens of varying mesh sizes to remove contaminants like staples, plastic films, and glue. Following this, a centrifugal cleaning process spins the pulp to remove heavier objects, such as paper clips and glass fragments. The fifth stage is , where the recovered
In , the wood is ground against a rotating stone. This method yields a high volume of pulp – up to 95% of the wood becomes paper – but the resulting product is relatively low quality, yellowing quickly due to residual lignin. This type is typically used for newsprint and telephone directories.
In contrast, , most commonly the Kraft process, uses a cocktail of sodium hydroxide and sodium sulphide to dissolve the lignin that binds the cellulose fibres together. This produces stronger, higher-quality paper. However, it recovers only about 50% of the wood’s mass, and it requires substantial energy and chemical recovery systems. A single large mill can consume up to 500,000 tonnes of wood annually.