The present invention relates to a method for removing a foreign material from the surface of an article comprising the following steps: i) providing an article having a surface covered at least partly with a foreign material; ii) contacting the article provided in step i) with a cleaning medium being an acid having a pKa in the range from −10 to 7 having a minimum concentration of 1 wt.-% and with a carrier medium having a density different from the density of the cleaning medium to obtain a mixture comprising the foreign material solved and/or dispersed in the cleaning medium, the carrier medium and the article free from the foreign material; iii) allowing the mixture obtained in step ii) to separate to obtain a heterophasic emulsion comprising at least a first phase comprising the carrier medium and the article free from the foreign material and a second phase comprising the cleaning medium and the foreign material solved and/or dispersed therein; iv) separating the phases obtained in step iii); and v) separating the article free from the foreign material from the carrier medium. Furthermore, the present invention relates to an installation for carrying out the inventive process.

The present invention is related to a deinking primer composition for deinking of a substrate, wherein said deinking primer composition comprises a binder component that has a polymeric backbone with pendent hydroxy or carboxy groups that have been esterified or acetalised or ketalised to such an extent that the binder component has an acid value of 0-50 mg KOH/g or a hydroxyl value of 0-600 mg KOH/g, preferably 0-400 mg KOH/g, so that a primer layer prepared from said deinking primer composition is dissolvable in an alkaline aqueous medium.

A method is disclosed for treating aqueous feed by dissolved gas flotation. The aqueous feed originates from industrial processing of fibrous material, where the aqueous feed includes an aqueous phase and solid particulate material suspended in the aqueous phase. The method includes bringing a flocculant in contact with the aqueous feed, flocculating suspended solid particulate material into flocs and contacting formed flocs with gas bubbles and inducing their flotation in a flotation basin. The flocculant includes a polymer composition having a charge density of at the most 1.7 meq/g dry and the polymer composition includes a cationic synthetic first polymer having a charge density at least 1.0 meq/g dry at pH 2.8, and at least one second polymer obtained by polymerization of (meth)acrylamide, the second polymer being polymerized in presence of the cationic first polymer, where the first polymer has a higher charge density than the second polymer.

A processing apparatus includes a powder material supply portion that supplies a powder material containing a first particle group consisting of a plurality of first particles, and a second particle group consisting of a plurality of second particles and having an average particle diameter larger than that of the first particle group, to a fiber-containing material containing a fiber during or after defibrating, and a powder material removing portion that removes at least a portion of the powder material from the fiber-containing material supplied with the powder material. It is preferable that the processing apparatus include a defibrating portion that defibrates the fiber-containing material on an upstream side of the powder material supply portion.

A processing device has a fibrillation portion fibrillating fiber-containing materials containing fibers in the air, a particle supply portion supplying particles having Mohs' hardness of 2 or more and 5 or less to the fiber-containing materials during or after the fibrillating at the fibrillation portion for collision of the particles and the fiber-containing materials, and a particle removal portion removing the particles from the fiber-containing materials to which the particles are supplied.

A method is disclosed for treating aqueous feed by dissolved gas flotation. The aqueous feed originates from industrial processing of fibrous material, where the aqueous feed includes an aqueous phase and solid particulate material suspended in the aqueous phase. The method includes bringing a flocculant in contact with the aqueous feed, flocculating suspended solid particulate material into flocs and contacting formed flocs with gas bubbles and inducing their flotation in a flotation basin. The flocculant includes a polymer composition having a charge density of at the most 1.7 meq/g dry and the polymer composition includes a cationic synthetic first polymer having a charge density at least 1.0 meq/g dry at pH 2.8, and at least one second polymer obtained by polymerization of (meth)acrylamide, the second polymer being polymerized in presence of the cationic first polymer, where the first polymer has a higher charge density than the second polymer.

A method is disclosed for dewatering of sludge from a pulp, paper or board making process, such as deinking sludge, including obtaining of an aqueous sludge including an aqueous phase and a fibre material suspended in the aqueous phase. The sludge is subjected to a pre-thickening step, where a first part of the aqueous phase is removed from the sludge and to a pressing step, where a second part of the aqueous phase is removed from the sludge, thereby obtaining a dry pressed sludge. Before or at the pre-thickening step a polymer composition having a charge density of at the most 1.7 meq/g, preferably at most 1.5 meq/g, more preferably at most 1.1 meq/g, is added to the sludge.

A processing device, a sheet manufacturing apparatus, a processing method, and a sheet manufacturing method that suppress damage to a substrate when removing color material from the substrate, and are useful for recycling the substrate after color material is removed, are provided. A processing device has a color material removal device including at least one discharge nozzle configured to discharge particles containing cellulose to a substrate holding color material, and remove the color material from the substrate. The color material removal device preferably has a double-walled conduit construction having an internal conduit and an external conduit in which the internal conduit is inserted, at least one of an opening to the internal conduit and an opening to the external conduit functioning as the discharge nozzle.

A method is disclosed for dewatering of sludge from a pulp, paper or board making process, such as deinking sludge, including obtaining of an aqueous sludge including an aqueous phase and a fibre material suspended in the aqueous phase. The sludge is subjected to a pre-thickening step, where a first part of the aqueous phase is removed from the sludge and to a pressing step, where a second part of the aqueous phase is removed from the sludge, thereby obtaining a dry pressed sludge. Before or at the pre-thickening step a polymer composition having a charge density of at the most 1.7 meq/g, preferably at most 1.5 meq/g, more preferably at most 1.1 meq/g, is added to the sludge.

A processing apparatus includes a powder material supply portion that supplies a powder material containing a first particle group consisting of a plurality of first particles, and a second particle group consisting of a plurality of second particles and having an average particle diameter larger than that of the first particle group, to a fiber-containing material containing a fiber during or after defibrating, and a powder material removing portion that removes at least a portion of the powder material from the fiber-containing material supplied with the powder material. It is preferable that the processing apparatus include a defibrating portion that defibrates the fiber-containing material on an upstream side of the powder material supply portion.