• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
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  • 法律状态
  • 优先权
    • 专利摘要:
    1496537 Bleaching pulp MO OCH DOMSJO AB 6 March 1975 [14 March 1974] 9450/75 Heading D1P Cellulose pulp is bleached with a gas containing molecular oxygen and in the presence of sodium bicarbonate, the partial pressure of the oxygen in the gas being at least 1 bar, the partial pressure of the carbon dioxide formed during bleaching being controlled to be within the range of 0.001 - 3 bars, and the bleaching step being carried at a temperature of 110-170‹C. The process is applicable to hard wood or soft wood pulps and the carbon dioxide level is controlled to give optimum selectivity in favour of deligrification over depolymerisation. The gas stream and pulp may be caused to move relative to one another e.g. by agitation, during bleaching. The carbon dioxide may be removed externally from the bleaching apparatus e.g. by absorption in an alkaline reacting liquor e.g. one containing sodium carbonate and/or bicarbonate, or by chilling and/or absorption. Alternatively, the carbon dioxide - containing gas may be absorbed into an alkaline cellulose pulp prior to the oxygen bleaching step, and the thus treated pulp subsequently subjected to the bleach step. The pulp may be further pre-treated to remove metal compounds e.g. those of copper, iron, vanadium and cobalt, which promote the degradation of carbohydrates. Metal complexing agents e.g. EDTA, amines. hydroxy amines and/or polyphosphates and manganese II salts may be present during the bleach step.
    公开号:SU847933A3
    申请号:SU752113118
    申请日:1975-03-06
    公开日:1981-07-15
    发明作者:Олоф Самуэльсон Ханс
    申请人:Мо Ох Домсье Актиеболаг (Фирма)；
    IPC主号:
    专利说明:

    The invention relates to cellulose paper-based industry and can be used in bleaching; There is a known method of bleaching pulp by saturating it with sodium carbonate solution and compressing it to a concentration of 20-66.7% followed by exposure to oxygen at 80-lOOOc 1. . There is also known a method in which the treatment with oxygen in the presence of sodium bicarbonate is carried out, which makes it possible to increase the resistance of the bleached mass to the loss of whiteness due to aging. During the bleaching process, the formation of carbon dioxide takes place, which is removed from the gas phase p. Surprisingly, it has been found that a significantly higher selectivity for the removal of lignin can be achieved if the removal of carbon dioxide is carried out up to its parhdal pressure of 0.001-3 bar. The purpose of the invention is to improve the quality of the bleached mass. The goal is achieved by the fact that according to the method of bleaching of the pulp by treating it with oxygen-containing gas in the presence of sodium hydrogen carbonate with a partial pressure of oxygen, preferably 3-20 bar and 110-170 ° C, with carbon dioxide dioxide being removed during the bleaching process carried out to a partial pressure of 0.001-3 bar. The speed of the bleaching process is continuously reduced with an increase in carbon dioxide content (carbon dioxide in the gas Eamethner I) the reduction of the bleaching mass flow is reached even at a partial pressure of 0.2 bar. At a pressure exceeding 3 bar, the duration of the process becomes quite long if the temperature is not keep up but the pulp becomes unsuitable for paper making.
    In order to achieve optimality of the PROPERTIES of the bleached mass, it is convenient to maintain the partial pressure of carbon dioxide different in different zones of the pulp column. The pulp mass can be pretreated to remove compounds that exhibit metallic activity with respect to the decomposition of carbohydrates, in particular compounds of copper, iron, vanadium and cobalt. It is possible to use solutions containing organic or inorganic acids, in particular, acetic, citric, formic , hydrochloric, sulfuric nitric and phosphoric acids, as well as sulfurous acid, condensates upon evaporation of acids and diluted wash liquids that contain sulphite liquor. Acid treatment is conveniently carried out at a pH of 1-5, for a period of time between 0.1 and 10 hours at 10-140 ° C. This process can be supplemented or replaced by treatment using complexing agents for heavy metals.
    Examples of suitable complexing agents for this purpose are phosphates, preferably polyphosphates, salts of such acids as isosaccharic acid, lactic acid, dihydroxy-oil, and aldaric acid. Sulfite liquor may be used, and aminopicicarboxylic acids, for example, ethylenediaminetetraacetic acid EDGC, as well as amines, in particular, mono- and triethanopalmne, should be mentioned.
    In carrying out the method, inhibitors can also be used. Examples of such inhibitors are various magnesium compounds, formaldehyde or compounds that form Formaldehydes and iodides.
    It has been found that the corresponding manganese compound has a positive selectivity for the removal of lignin in the process. This is the case when the mass is pretreated in such a way that, at the same time, the content of the active manganese compounds is reduced. Examples of such compounds include manganese sulfate, manganese nitrate, manganese chloride and acetate. Additives should be added before the start of oxygen bleaching or during the process, the amount of manganese compounds is 0.001-2, preferably 0.05-0.5 wt.% Of the dry weight of the mass. Example 1 Technical sulphate mass of birch wood, whose kappa number is Avl 20.2,
    and a viscosity of 1236 cmL / g is impregnated with sodium carbonate solution, then compressed to a concentration of 2428%. The temperature of the impregnated mass is 40 ° C. The mass is sent to the absorption zone of the autoclave and subjected to gas treatment, which is removed from the oxygen-bleaching process, the gas temperature 120s - the total gas pressure is 10 bar, and the partial pressure of carbon dioxide is 0.3 bar, the partial pressure of oxygen - bar . The process continues for 5 minutes during this period of time the temperature is raised to 92 ° C. Approximately 90% of the carbon dioxide entering this absorption zone is absorbed and: sodium carbonate is converted to bicarbonate. The pulp mass treated in this way is then subjected to bleaching with oxygen at 120 ° C.
    the reaction apparatus, by rotating which the pulp is set in motion. The partial pressure of the incoming gas with respect to oxygen is 6.3 bar, and with respect to carbon dioxide, 0.03 bar. The flow rate is adjusted so that the partial pressure of carbon dioxide i in the output gas is maintained at 0.3 bar in the first half the bleaching process and 0.1 bar in the final part.
    The results obtained here are summarized in a table which also shows the result of comparative testing in accordance with the usual bleaching procedure using sodium hydroxide in the presence of a magnesium complex.
    As the presented results of the proposed method show, a significantly higher viscosity and a significantly lower loss of Byxc a-product are obtained with the same degree of lignin removal. In another series of comparative tests, during which the addition of magnesium is excluded, the viscosity is achieved, which, when compared with the same Kappa number, is 70-90 units lower than that achieved in the presence of magnesium.
    Thus, in the practical implementation of the proposed method, it is possible, if desired, to exclude the addition of magnesium, while
    preserves a significantly higher yield of the final product and increased viscosity (lower degree of carbohydrate decomposition} compared to conventional methods with the same content
    lignin.
     Example2. The experiments in accordance with Example 1 are repeated, but with the difference that 0.2% by weight of EDTA is contained in the target mass. There is no noticeable change in the yield of the final product with the same Kapp number. The same can be said with regard to the whites of the mass. On the other hand, a viscosity increase of 80-100 is achieved.
    权利要求:
    Claims (3)
    [1]
    Claims. .
    Method of bleaching cellulosic pulp by treating it with oxygen-containing gas in the presence of sodium bicarbonate at part J4 da wush
    preferably 3–20 bar and IIO-IVO C with simultaneous removal of carbonaceous dioxide bleaching formed in the process, so that, in order to improve the quality of the bleached mass, carbon dioxide is removed from ; its partial pressure is 0 001-3 bar.
    Sources of information, (financial ones taken into account in the examination of d 1. Swedish patent ff 219677, cl. 55), c. 5, 1968.
    [2]
    2. Patent IT 3024158, cl.162-65 1969,
    [3]
    3. Patent OiiA W 3764464, cl. 162-65, 1973.
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    同族专利:
    公开号 | 公开日
    JPS50121503A|1975-09-23|
    SE7403452L|1975-09-15|
    ATA178975A|1978-01-15|
    BR7501340A|1975-12-09|
    DE2509691B2|1977-03-10|
    NO750745L|1975-09-16|
    AT345659B|1978-09-25|
    ZA751267B|1976-01-28|
    NO140937B|1979-09-03|
    NO140937C|1979-12-12|
    SE393138B|1977-05-02|
    FI750636A|1975-09-15|
    US4016029A|1977-04-05|
    GB1496537A|1977-12-30|
    CA1036757A|1978-08-22|
    FR2264126B1|1977-11-18|
    JPS5228884B2|1977-07-29|
    FR2264126A1|1975-10-10|
    DE2509691A1|1975-09-25|
    IT1030235B|1979-03-30|
    CH591596A5|1977-09-30|
    引用文献:
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    US2926114A|1957-08-12|1960-02-23|Kimberly Clark Co|Manufacture of cellulosic products|
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    SE353749B|1970-03-02|1973-02-12|Mo Och Domsjoe Ab|
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    SE343092B|1970-06-22|1972-02-28|Mo Och Domsjoe Ab|
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    JPS5415002A|1977-07-04|1979-02-03|Hokusan Kk|Treating method to oxidize fibrin substance|
    SE450394B|1981-12-30|1987-06-22|Mo Och Domsjoe Ab|PROCEDURE FOR BLACKING OF SIMILAR CELLULOSAMASSA|
    US4596630A|1984-12-21|1986-06-24|International Paper Company|Process for the electrochemical reductive bleaching of lignocellulosic pulp|
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    US5171405A|1990-08-28|1992-12-15|Kamyr, Inc.|Reactor having a discontinuous conduit means between surfaces of a downwardly extending stationary spiral|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE7403452A|SE393138B|1974-03-14|1974-03-14|PROCEDURE FOR BLEACHING CELLULOSA WITH AN ACID CONTAINING GAS IN THE PRESENCE OF SODIUM BICARBONATE|
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