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Can magnesium build-up be a problem in a kraft mill with oxygen bleaching?
Swedish Forest Products Research Laboratory.ORCID iD: 0000-0002-0744-8399
Swedish Forest Products Research Laboratory.
1980 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 63, no 5, 121-123 p.Article in journal (Refereed) Published
Abstract [en]

The material balance of magnesium for one mill and some important data from two other mills show that the build-up of magnesium will not be a problem. This conclusion is supported by laboratory studies and thermodynamic calculations which explain the chemical basis for the behavior of magnesium in the mill system. The main input of magnesium are the wood chips and the magnesium inhibitor. The main outputs are the effluent from the conventional bleaching and the dregs and grits. The magnesium concentrationdoes not form a closed loop, and the white liquor contains only neglectible amounts of magnesium.

Place, publisher, year, edition, pages
TAPPI Press, 1980. Vol. 63, no 5, 121-123 p.
Keyword [en]
magnesium, kraft mills, oxygen bleaching.
National Category
Engineering and Technology
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-37228OAI: oai:DiVA.org:kau-37228DiVA: diva2:844056
Available from: 2015-08-03 Created: 2015-08-03 Last updated: 2015-09-01Bibliographically approved
In thesis
1. From recovery boiler to integration of a textile fiber plant: Combination of mass balance analysis and chemical engineering
Open this publication in new window or tab >>From recovery boiler to integration of a textile fiber plant: Combination of mass balance analysis and chemical engineering
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Modern chemical technology is an efficient tool for solving problems, particularly within the complex environment of the pulp and paper industry, and the combination of experimental studies, mill data and mass balance calculations are of fundamental importance to the development of the industry. In this study various examples are presented, whereby chemical technology is of fundamental importance.

It is well documented that under normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without problems. However, in the case of  alternatives to the kraft recovery boiler, knowledge of more precise data of the molten salts is required for the design calculations. In this study the viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at temperatures relevant for a recovery boiler, i.e. similar to water at room temperature.

The presence of non-process elements (NPE) in a typical pulp mill has been investigated. The main input is with regards to the wood, and anticipated problems include; deposits in evaporators, high dead-load in liquor streams, plugging of the upper part of the recovery boiler and decreasing efficiency in the causticization department. Efficient green liquor clarification is of the greatest importance as an efficient kidney for many NPE. Mill data and calculations show that the magnesium added in the oxygen delignification does not form a closed loop.

Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be highly beneficial. The prehydrolysis liquor will contain both sugars and acetic acid. It is however not possible to fully replace the sulphuric acid of the viscose spinning bath with acetic acid of own production. The sulphuric chemicals from the viscose plant can be partly taken care of in the kraft recovery area as well as the viscose plant which can be supplied with alkali and sulphuric acid. Zinc-containing effluents from the viscose plant can be treated with green liquor to precipitate zinc sulphide.

Abstract [en]

Modern chemical technology is an extremely efficient tool for solving problems particularly in a complicated environment such as the pulp and paper industry. Here, examples are studied during which chemical technology is of fundamental importance.

At normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without hindrance. However, for certain kraft recovery boiler alternatives, knowledge of more precise data of the molten salts is required. The viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at relevant temperatures.

The main input of non-process elements (NPE) is down to the wood, and known problems include deposits in evaporators and decreasing efficiency in the causticization department. Green liquor clarification is an efficient kidney for many NPE. Magnesium added in the oxygen delignification does not form a closed loop.

Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be of significant interest, as the handling of both alkali and sulphuric compounds can be integrated. Problems will however arise as the capacity of the pulping line and the chemical recovery has to be adjusted.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2015. 56 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2015:39
Keyword
kraft pulping, recovery boiler, smelt properties, non-process elements, oxygen delignification, viscose manufacturing, integrated production, regenerated cellulose, sulfatmassa, fysikaliska egenskaper, smälta, sodapanna, processfrämmande ämnen, bioraffinaderi, integrerad produktion, regenererad cellulosa
National Category
Engineering and Technology Physical Chemistry Materials Chemistry
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-37266 (URN)978-91-7063-657-8 (ISBN)
Presentation
2015-09-17, Sal 9 C 203, Karlstads universitet, Karlstad, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2015-09-01 Created: 2015-08-03 Last updated: 2015-09-03Bibliographically approved

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