Method extracting lignin from paper making pulp and conducting chemical modification
A chemical modification, lignin technology, applied in the field of chemical modification
Active Publication Date: 2015-07-15
CHENGDU INTERMENT TECH
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[0004] Although some existing technologies for processing black liquor and chemically modifying extracted lignin are given above, these technologies are all independent, and no one has organically integrated these technologies to form a set from papermaking. A complete process for extracting lignin from pulp and chemically modifying it
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[0033] Such as figure 1As shown, the high-temperature black liquor separated from the papermaking pulp by the extrusion method enters the first container 1, and then puts acidic substances therein, such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, formic acid, oxalic acid, carbon dioxide, bituminous gas, etc. The pH of the black liquor is lowered, and lignin is then precipitated from the black liquor. When the pH value of the black liquor decreased to 4, the lignin precipitation rate in the black liquor basically reached the highest value, and thereafter, as the black liquor pH value continued to decrease, the lignin precipitation rate increased very little. Before the temperature of the black liquor drops to 100° C., the first cross-flow membrane microfiltration device 2 is used to concentrate the lignin in the black liquor to obtain a first concentrated liquor. Reflected in figure 1 Above, that is, the inlet temperature T1 of the first cross-flow memb...
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Abstract
The invention discloses a method extracting lignin from paper making pulp and conducting chemical modification. The method effectively achieves extraction and chemical medication of the lignin by means of black liquor temperature, and therefore saves energy consumption. The method includes the following steps: (1) high-temperature black liquor is separated from the paper making pulp; (2) a potential of hydrogen (PH) value of the high-temperature liquor is reduced to enable the lignin to be dissolved out; (3) the lignin in the black liquor is concentrated through a first cross-flow film microfiltration device to obtain first concentrated liquid before temperature of the black liquor is reduced to 10 DEG C; (4) the first concentrated liquid is washed through hot water having temperature higher than and equal to 90 DEG C to obtain mixture liquid; (5) the lignin in the mixture liquid is concentrated through a second cross-flow film microfiltration device to obtain second concentrated liquid before temperature of the mixture liquid is reduced to 80 DEG C; (6) the second concentrated liquid is heated to 120-200 DEG C before the temperature of the second concentrated liquid is reduced to 70 DEG C, and chemical modification is conducted for the lignin in the second concentrated liquid; and (7) the lignin after the chemical modification is dried.
Description
technical field [0001] The invention relates to a method for extracting and chemically modifying lignin from papermaking pulp. Background technique [0002] During kraft or soda pulping, the washed and cooked pulp contains a large amount of black liquor (i.e. cooking waste), which is usually separated from the pulp by extrusion or filtration. Because the direct discharge of black liquor will seriously pollute the environment, and the black liquor contains useful substances such as lignin, so it is necessary to treat the black liquor. At present, there are many methods for treating black liquor, for example, "Acid precipitation extracts lignin from pulping black liquor, Liu Quanxiao, etc." Lignin was extracted from , especially pointed out that acid precipitation method often used sulfuric acid or carbon dioxide to adjust the pH value of black liquor to below 4; Volume 24, No. 4, August 2004" mentioned that the lignin in the black liquor was concentrated by using a cross-fl...
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IPC IPC(8): C08H7/00
Inventor 高麟汪涛莫代林
Owner CHENGDU INTERMENT TECH