CN1209294C

CN1209294C - Quick flocculation method for black liquor of paper-making

Info

Publication number: CN1209294C
Application number: CN 02135655
Authority: CN
Inventors: 张文超
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-10-22
Filing date: 2002-10-22
Publication date: 2005-07-06
Anticipated expiration: 2022-10-22
Also published as: CN1491901A

Abstract

The present invention relates to a quick flocculation method for paper-making black liquor, which belongs to the technical field of chemical industry. The present invention is characterized in that a flocculant of a type A and a flocculant of a type B are respectively added to the processing processes of the paper-making black liquor and second-stage water, wherein the flocculant of the type A is formed by acidifying a chemical raw material of which the ratio of silicon dioxide to alumina is from 1.2 to 2.5; the flocculant of the type B is formed by adopting 5/1000 of a polyacrylamide (PAM) water solution. The quick flocculation method for paper-making black liquor has the advantages of low disposable investment, short process flow, simple and convenient operation, low operating cost, etc. The black liquor processing cost of each ton of paper is only 80 yuan, and the reaction time is from 2 to 3 minutes.

Description

Quick flocculation method for paper-making black liquor

The technical field is as follows:

the invention belongs to the technical field of chemical industry, and relates to a rapid flocculation method of papermaking black liquor. Background art:

the paper making industry is an industry with high energy and raw material consumption, large water consumption and serious pollution, the paper making industry of China generally adopts alkaline pulping, black liquor generated in the cooking process contains a large amount of lignin, cellulose and other soluble organisms, and the pollution is serious, so the pollution of the paper making industry is treated, and the pollution of the black liquor is mainly treated. In the prior art, the papermaking industry generally adopts the following three methods to treat papermaking black liquor, namely a caustic soda recovery method, a second acid lignin separation method and a third anaerobic acidification method. The common defects of the three methods are that the one-time investment is too high, the process flow is long, the treatment operation cost is high, the operation is complicated, the treatment cost is high, the treatment effect is difficult to reach the standard, and the like, so that the paper making enterprises are difficult to bear.

The invention content is as follows:

the invention aims to provide a rapid flocculation method for papermaking black liquor, which can effectively reduce the pollution of the papermaking black liquor, and has the advantages of low investment and high treatment efficiency.

The technical scheme adopted forrealizing the purpose of the invention is as follows: the main characteristics are as follows: a type flocculant and a type B flocculant are respectively added in the treatment of the papermaking black liquor and the second-stage water, wherein the type A flocculant is generated by acidifying chemical raw materials with the ratio (value) of silicon dioxide to aluminum oxide of 1.2-2.5. The B-type flocculant is prepared from 5 per mill of Polyacrylamide (PAM) aqueous solution. The specific preparation method of the A-type flocculant adopts three modes: the water glass is acidified and then added with aluminum trichloride to prepare the water glass; the fly ash or the high-alumina clay of a thermal power plant is added with white alkali or caustic soda, calcined at 850 ℃ and acidified to prepare the material; the method is characterized by comprising the following steps of (1) crushing waste A-type molecular sieve raw materials, and carrying out acidification treatment to obtain the product; the papermaking black liquor and the secondary water are treated according to the scheme, the one-time investment is little, the process flow is short, the operation is simple and convenient, the operation cost is low, the black liquor treatment cost per ton of paper is only 80 yuan, the treated papermaking black liquor is light yellow from thick black, the SS, COD, BOD and other contents of the treated sewage are greatly reduced, and the secondary water is conveniently treated. After the second-stage water is treated by the method, most of the water can be recycled, and meanwhile, the water separated by the separation equipment is standard water and can be directly discharged or recycled.

Embodiments of the invention are further described below with the aid of the accompanying drawings.

Description of the drawings:

FIG. 1 is a process flow diagram of the present invention;

the specific implementation mode is as follows:

the invention relates to a rapid flocculation method of papermaking black liquor, which is characterized in that an A-type flocculating agent and a B-type flocculating agent are respectively added in the treatment of the papermaking black liquor and secondary water, and in the formula of the flocculating agents, the A-type flocculating agent is generated by acidifying chemical raw materials with the ratio (value) of silicon dioxide to aluminum oxide being 1.2-2.5. The B-type flocculant is prepared from 5 per mill of Polyacrylamide (PAM) aqueous solution. Namely:

the specific preparation method of the A-type flocculant comprises the following steps:

a: the flocculant is directly synthesized by chemical raw materials, and the water glass is acidified and then added with aluminum trichloride to prepare the A-type flocculant, wherein the reaction formula is as follows:

b: preparing fly ash or high-alumina clay by utilizing the fly ash or the high-alumina clay of a thermal power plant, adding white alkali or caustic soda, calcining at 850 ℃, and preparing an A-type flocculating agent after acidification, wherein the reaction formula is as follows:

c: prepared by using waste chemical products (such as A type molecular sieve)

Crushing the waste A-type molecular sieve, and then carrying out acidification treatment to prepare an A-type flocculant, wherein the reaction formula is as follows:

the reaction mechanism of adding the A-type flocculant and the B-type flocculant is briefly described as follows: the main component of the papermaking black liquor is lignin which exists in the form of soluble sodium salt, on the other hand, the lignin has colloid property, ions of the lignin carry negative charges in the black liquor, ions of the A-type flocculating agent of the invention carry positive charges, so that the ions of the A-type flocculating agent not only can neutralize the negative charges of the lignin ions, but also have adsorption and bridging effects, and also have certain decolorization capacity and can quickly agglomerate lignin particles, at the moment, the B-type organic polymer flocculating agent is added, so that the agglomeration of the lignin is larger and larger, and other impurities in the black liquor are also adsorbed, so that the black liquor is quickly changed into light yellow, and the reaction time is only 2-3 minutes.

Referring to fig. 1, in the process flow of the invention, a papermaking black liquor 1 is pumped into a reaction kettle 9 by a pump 2, an A-type flocculant 5 is pumped into a metering tank 7 and enters the reaction kettle 9 by a pump 4 under the condition of stirring, a B-type flocculant 6 is added after the A-type flocculant 5 is added, the B-type flocculant 6 is also pumped into a metering tank 8 and enters the reaction kettle 9 by a pump 3, the reaction is completed after the A-type flocculant 5 is completely added, the stirring is carried out for 2-3 minutes after the all the flocculant is added, then the black liquor is changed into light yellow water, the black liquor is pumped into a separation device 10 by a pump 11, lignin is separated, and the light yellow water flows into a secondary water tank 12 for treatment.

The treatment process of the second stage water is the same as that of black liquor, the second stage water is pumped into a reaction kettle 19 through a pump 13, the treated second stage water is clarified for about 50 minutes in a clarification tank 14 and then is pumped into a cooking workshop 18 through a pump 15 for primary and secondary washing, precipitates in the clarification tank 14 are pumped into a separation device 17 through a pump 16 to separate short fibers, and the water separated by the separation device 17 is standard water and can be directly discharged or reused.

Claims

1. A rapid flocculation method of papermaking black liquor is mainly characterized in that: a type flocculant and a type B flocculant are respectively added in the treatment of the papermaking black liquor and the secondary water, wherein the type A flocculant is generated by acidifying chemical raw materials with the ratio (value) of silicon dioxide to aluminum oxide of 1.2-2.5, and the type B flocculant is prepared by adopting 5 per mill of Polyacrylamide (PAM) aqueous solution.

2. The method for the rapid flocculation of black liquor in papermaking according to claim 1, characterized in that: the specific preparation method of the A-type flocculant adopts three modes: the water glass is acidified and then added with aluminum trichloride to prepare the water glass; the fly ash or the high-alumina clay of a thermal power plant is added with white alkali or caustic soda, calcined at 850 ℃ and acidified to prepare the material; the waste A-type molecular sieve is prepared by crushing and acidifying waste A-type molecular sieve raw materials.