Design of collection systems Collection systems exist in two general types, as pick-up and as drop-off systems, sometimes with both types in parallel. In most countries, the collection systems is defined by the authorities, often on municipality or department level. Particularly in regions where an officially organised collection system does not exist to a large
Dry sorting of paper for recycling Mixed post-consumer paper for recycling which is not thoroughly monitored during collection typically contains unwanted material and should be sorted before the recycling process. Sorting also adds value by enabling the sorting company to create higher priced qualities. After separating the mix into pure packaging and graphic grades, both
Collection systems of paper for recycling Challenge and organisation Collection of paper and board for recycling takes place from various sources. These sources are printers and converters, offices, retailers as well as other industrial users and private households. The key to a high collection rate of paper for recycling is an efficient collection from households
Machines for fine screening and fractionation Andritz fine screening ©ANDRTIZ Basic physical mechanisms in pressure screens In a pressure screen several sub-processes occur in parallel: The deflocculation of the pulp in order to singularise particles, the passage of fibres through the apertures, the periodic cleaning of the screen plate by suction pulses caused
Process design for market deinked pulp Market DIP is pulp produced for sale on the open market to paper mills to replace virgin fibres. The production of Market DIP from RCF is the most demanding process. A prerequisite is using wood-free grades as furnish, i.e. in the form of sorted office waste. The mechanical fibre
Alternative bleaching processes The search for new, more efficient bleaching processes has produced laboratory results on alternative bleaching chemicals. These primarily refer to peroxy acids, including peracetic acid and Caro’s acid. Peracetic acid (CH3COOOH) has a high oxidation potential and is therefore very acid. Produced from concentrated acetic acid (CH3COOH) and peroxide (H2O2), it exists
Ozone bleaching (Z) Ozone bleaching is a recent development for bleaching recycled fibre pulp. In contrast to its use for bleaching chemical pulp, where it serves exclusively to degrade residual lignin further, in the bleaching of deinked pulp it destroys dyes and optical brighteners 1-3. The strength gains that accompany the treatment have secondary importance.
Bleaching with oxygen chemicals – oxygen bleaching (O) For some years, there has been a trend — not only in chemical pulp bleaching but also in recovered paper processing — towards replacing chlorine-containing bleaching chemicals by oxygen-based chemicals. The driving forces behind this trend are as follows 1: Changed consumer demands: Demand for products manufactured
Bleaching with chlorine-containing chemicals In North America, wood-free deinked pulp is usually bleached with chlorine-containing chemicals. In the past, hypochlorite bleaching was common. Recycled fibre with a mechanical pulp content up to 5 % is not only very effectively bleached but also colour-stripped. With larger proportions of mechanical pulp fibres, the treatment is accompanied by
Combined bleaching stages The use of deinked pulp depends largely on its optical characteristics. When using deinked pulp to produce high-quality graphic papers, such as supercalendered or light weight coated paper, single-stage bleaching is usually not sufficient to meet the optical requirements. To increase brightness, two or sometimes three bleaching stages are necessary with oxidative
