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Method for treating aqueous feed by dissolved gas flotation

A dissolved air flotation, water-based technology, applied in the direction of fiber raw material treatment, water/sewage treatment, chemical instruments and methods, etc., to achieve the effect of improving scraping results and enhancing the size of flocs

Pending Publication Date: 2020-07-14
KEMIRA OY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This results in an increase in conductivity or total ionic strength (i.e., salt concentration) in the process water

Method used

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  • Method for treating aqueous feed by dissolved gas flotation
  • Method for treating aqueous feed by dissolved gas flotation
  • Method for treating aqueous feed by dissolved gas flotation

Examples

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preparation example Construction

[0077] Preparation of Polymer Compositions Used in Examples

[0078] The cationic first polymer is a condensation copolymer of epichlorohydrin and dimethylamine. The amount of cationic first polymer in all final polymer compositions was 6 wt-%, based on the weight of dry polymer material of the polymer composition.

[0079] The second polymer is a copolymer of acrylamide and [2-(acryloyloxy)ethyl]trimethylammonium chloride (ADAM-Cl). Prior to polymerization of the second polymer, the monomers used, the first polymer, a pH adjuster (e.g., adipic acid, citric acid), chain transfer agent, chelating agent, redox initiator, and thermal The initiator was degassed with nitrogen. Acrylamide and ADAM-C1 monomers were added to the solution of the first polymer, the host polymer. In Table 1 the mol-% of the monomers used are given.

[0080] The resulting reaction solution was cooled at -3°C, a redox initiator was added, and radical polymerization was started. Polymerization is carri...

Embodiment 1

[0099] Treated water samples were obtained from the second loop of the old newsprint deinking process.

[0100] Deinking Facility Second Loop Disc Filter Cloudy Filtrate for Feed has the following characteristics:

[0101] 500 mg / l suspended solids, pH 7.5, ash content 55%, conductivity 2 mS / cm, cation requirement 300 μeq / l.

[0102] The dispersion water used has the following characteristics:

[0103] 150 mg / l suspended solids, pH 7.5, ash content 55%, conductivity 2 mS / cm, cation requirement 300 μeq / l.

[0104] The results in Table 4 show that using a flocculant comprising a polymer composition enables faster floc rise time in clear filtrate, reduced filtrate turbidity and reduced suspended solids, given in ppm compared to the reference composition. out (solid polymer to feed stream). Alternatively, good performance can be obtained by using lower dosages of the polymer composition. Another benefit may be increased feed capacity of the dissolved air flotation unit due to ...

Embodiment 2

[0109] Treated water samples were obtained from the first loop of a tissue washing deinking process for mixed office waste.

[0110] The scrubber filtrate used for feed has the following characteristics:

[0111] 1950 mg / l suspended solids, pH 7.7, ash content 34%, conductivity 0.64 mS / cm, cation demand 250 μeq / l.

[0112] The dispersion water used has the following characteristics:

[0113] 50 mg / l suspended solids, pH 7.5, ash content 15%, conductivity 0.62 mS / cm, cation demand 250 μeq / l.

[0114] The results in Table 5 show that using a flocculant comprising a polymer composition according to the invention enables faster rise times of flocs in clarified filtrate, reduced filtrate turbidity and reduced of suspended solids, given in ppm (solid polymer to feed stream). Alternatively, good performance can be obtained by using lower dosages of the polymer composition. Another benefit may be increased feed capacity of the dissolved air flotation unit due to faster rise times....

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Abstract

The invention relates to a method for treating aqueous feed by dissolved gas flotation, especially by dissolved air flotation (DAF), the aqueous feed originating from an industrial processing of fibrous material of cellulosic origin, such as manufacture of pulp, paper, board, recycled fibre pulp or the like, wherein the aqueous feed comprises an aqueous phase and solid particulate material suspended in the aqueous phase. The method comprises bringing a flocculant in contact with the aqueous feed and flocculating suspended solid particulate material into flocs through interaction of flocculantand suspended solid particulate material and contacting formed flocs with gas bubbles and inducing their flotation in a flotation basin. The flocculant, which is used for flocculating suspended solidparticulate material, comprises a polymer composition having a charge density of at the most 1.7 meq / g dry, preferably at the most 1.5 meq / g dry, more preferably at the most 1.1 meq / g dry, and the polymer composition comprises a cationic synthetic first polymer, which has a charge density at least 1.0 meq / g dry at pH 2.8, and at least one second polymer, which is a polymer obtained by polymerisation of (meth)acrylamide, the second polymer being polymerised in presence of the cationic first polymer, wherein the first polymer has a higher charge density than the second polymer.

Description

technical field [0001] According to the preambles of the appended independent claims, the present invention relates to the treatment of aqueous feeds from the manufacture of pulp, paper, board, recycled fiber pulp, etc. by dissolved air flotation, in particular dissolved air flotation (DAF) Methods. Background technique [0002] Dissolved air flotation is used to purify various aqueous feeds from pulp, paper and board manufacturing processes. A flocculant may be added to the aqueous feed to be treated to flocculate suspended solid particulate material present in the feed prior to introduction into the flotation cell. In a typical dissolved air flotation process, dispersed water containing dissolved gas is introduced into the flotation cells along with an aqueous feed. When the dispersed water enters the flotation cell, the dissolved gas is released in the form of small bubbles. The flocs are brought into contact with small air bubbles, whereby the air bubbles attach to th...

Claims

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Application Information

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IPC IPC(8): D21C5/02D21B1/32
CPCD21B1/32D21B1/327D21C5/02Y02W30/64D21B1/322D21B1/066D21C11/0042C02F1/52C02F1/5272C02F1/56D21C5/027
Inventor 马蒂·希耶塔涅米于里·瓦伊梅基约纳斯·利坎德罗萨·卡塞列尔
Owner KEMIRA OY
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