METHOD FOR MAKING OF PAPER, TISSUE, BOARD OR THE LIKE

• US 20150041092A1
• Filed: 02/22/2013
• Published: 02/12/2015
• Est. Priority Date: 02/22/2012
• Status: Active Grant

• Current Assignee: Kemira Oyj
• Original Assignee: Kemira Oyj
• Inventors: Hietaniemi, Matti, Karppi, Asko, Kolari, Marko, Strengell, Kimmo, Ekman, Jaakko
• Granted Patent: US 9,279,217 B2
• Time in Patent Office: Days
• US Class Current: 162/168.4
• CPC Class Codes: D21H 11/14 Secondary fibres working-up waste paper D21C5/02
• CPC Class Codes: D21H 17/28 Starch
• CPC Class Codes: D21H 17/37 Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
• CPC Class Codes: D21H 17/55 Polyamides; Polyaminoamides; Polyester-amides
• CPC Class Codes: D21H 17/63 Inorganic compounds
• CPC Class Codes: D21H 17/66 Salts, e.g. alums
• CPC Class Codes: D21H 27/002 Tissue paper; Absorbent paper D21H21/22, D21H27/02, D21H27/20 take precedence; toilet paper A47K10/00; absorbent pads for physiological fluids A61L15/16; making on paper-making machines D21F11/00
• CPC Class Codes: Y02W 30/64 Paper recycling

Abstract

The invention relates to a method for making of paper, tissue, board or the like by using recycled fibre material as a raw material. The method comprises following steps: pulping recycled paper, board or the like in a pulper and obtaining a pulp flow comprising (i) an aqueous phase and (ii) at least recycled fibres and starch having low molecular weight, which are dispersed in the aqueous phase; adding a coagulant agent to the pulp flow or to an aqueous process flow comprising starch having low molecular weight; allowing the coagulant agent to interact with the starch having low molecular weight and optionally forming aggregates; and adding at least one flocculating agent, after the addition of the coagulant agent, to any flow, which comprises interacted coagulant agent, and forming a treated flow with starch comprising agglomerate(s); retaining at least part of the said aggregates and/or the said agglomerates to the fibres or to a web, which is formed.

Claims

1. Method for making of paper, tissue, board or the like by using recycled fibre material as a raw material, the method comprising following steps:

pulping recycled paper, board or the like in a pulper and obtaining a pulp flow comprising (i) an aqueous phase and (ii) at least recycled fibres and starch having low molecular weight, which are dispersed in the aqueous phase;

characterised in

adding a coagulant agent to the pulp flow or to an aqueous process flow comprising starch having low molecular weight;

allowing the coagulant agent to interact with the starch having low molecular weight and optionally forming aggregates; and

adding at least one flocculating agent, after the addition of the coagulant agent, to any flow, which comprises interacted coagulant agent, and forming a treated flow with starch comprising agglomerate(s);

retaining at least part of the said aggregates and/or the said agglomerates to the fibres or to a web, which is formed.

2. Method according to claim 1, characterised in reducing the COD value of the treated flow with at least 10% from the COD value of the aqueous phase of the pulp flow or from the COD value of the aqueous process flow into which the coagulant agent is added.

3. Method according to claim 1, characterised in

screening the pulp flow and separating unwanted material from the pulp flow;

thickening the screened pulp flow to a higher concentration, i.e. storage concentration by separating a part of the aqueous phase from the pulp flow as a discharge flow; and

adding the coagulant agent to the pulp flow before the thickening step or to the discharge flow from the thickening step.

4. Method according to claim 3, characterised in

adding the coagulant agent to the discharge flow of the thickening step at one feeding location or more feeding locations, and

leading the discharge flow from the thickening step forward in the process and using it as dilution water between the machine chest and the headbox.

5. Method according to claim 1, characterised in

screening the pulp flow and separating unwanted material from the pulp flow;

and

adding coagulant immediately after the pulping step, before the screening step or after the screening step.

7. Method according to claim 1, characterised in selecting the coagulant agent from the group comprising aluminium sulphate, aluminium chloride, polyaluminium chloride (PAC), polyaluminium sulphate (PAS), polyaluminium silica sulphate, sodium aluminate, alum, ferric sulphate (Fe₂(SO₄)₃), ferrous sulphate (FeSO₄), ferric ferrous sulphate, ferric chloride, ferrous chloride, ferric ferrous chloride, ferric chloride sulphate, ferric nitrate, ferric sulphate nitrate, ferric chloride nitrate, ferric hydroxide, bentonite, silicious material, such as colloidal silica, and their mixture.

8. Method according to claim 7, characterised in selecting the coagulant agent from bentonite, colloidal silica, aluminium compounds and iron compounds comprising Fe (III).

11. Method according to claim 1, characterised in adding flocculating agent to the flow, which comprises interacted coagulant agent, after pulp storage silos and before a headbox of a paper or board machine.

13. Method according to claim 1, characterised in adding the flocculating agent after the coagulant agent, the reaction time for the interaction between the coagulant agent and low molecular starch being >

1 min, before the addition of the flocculating agent.

14. Method according to claim 1, characterised in selecting the flocculating agent from the group comprising cationic polyacrylamide (C-PAM), anionic polyacrylamide (A-PAM), polyvinyl amine (PVAm), polyethylene oxide (PEO), polyethyleneimine (PEI) and their mixtures.

17. Method according to claim 1, characterised in that the low molecular weight starch comprises an oxidised surface size starch having a weight average in the range of 100 000-5 000 000 g/mol, more typically 200 000-4000 000 g/mol.

19. Method according to claim 1, characterised in adding a biocide and/or an amylase enzyme inhibitor to the pulper and/or to a flow in the process, such as the pulp flow or the aqueous process flow, wherein the biocide reduces the number of viable bacteria and/or microbes in the flow at least 80%.

20. Method according to claim 19, characterised in adding the biocide and/or the amylase enzyme inhibitor to the pulp flow within 2 hours from the moment when the pulp flow exits the pulper outlet.

21. Method according to claim 19, characterised in adding the biocide and/or the amylase enzyme inhibitor to the pulp between inlet of the pulper and thickening step of the screened pulp flow or characterised in adding the biocide and/or the amylase enzyme inhibitor to the pulp flow before the pulp storage towers or silos located after the thickening step.

25. Method according to claim 1, characterised in selecting the biocide from the group comprising oxidizing biocides, such as sodium hypochlorite, hypobromous acid, chlorine dioxide;

halogenated hydantoins, such as bromochloro-dimethylhydantoin;

partially halogenated hydantoins such as monochloro-dimethylhydantoin;

haloamines, such as chloramines or bromamines; and

their mixtures.

26. Method according to claim 1, characterised in adding strengthening agents and/or flocculant additives to the pulp flow.

27. Method according to claim 26, characterised in selecting the strengthening agent from the group comprising starch, cationic polyacrylamide (C-PAM), anionic polyacrylamide (A-PAM), glyoxylated polyacrylamide (G-PAM), amphoteric polyacrylamide, polydiallyldimethylammonium chloride (poly-DADMAC), polyacrylic amide (PAAE), polyvinyl amine (PVAm), polyethylene oxide (PEO), polyethyleneimine (PEI), chitosan, guar gum, carboxymethyl cellulose (CMC) and their mixtures.

30. Method according to claim 26, characterised in selecting the flocculant additive from the group comprising bentonite, colloidal silica and conventional papermaking fixatives, such as polydiallyldimethylammonium chloride (poly-DADMAC) or polyamines, and adding the flocculant additive before or after the addition of the flocculating agent, but after the addition of the coagulant agent.

31. Method according to claim 1, characterised in pulping recycled paper, board and/or old corrugated containerboard (OCC), comprising starch, whereby the COD value of the aqueous phase of the untreated pulp flow is of >

20 kg/ton, more typically >

35 kg/ton, before the addition of the coagulant agent and the flocculating agent.

32. Method according to claim 1, characterised in the fresh water consumption of the process being <

10 m³/ton produced paper or board, and/or the process water conductivity being at headbox >

2500 μ

S/cm.

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