JP3389582B2 - Base replacement method for magnesium based sulfite pulp effluent - Google Patents

Description

Detailed Description of the Invention

[0001]

[Industrial application] Fields in which various industrial dispersants are used, such as concrete for civil engineering and construction, disperse dyes, agricultural chemicals,
The present invention relates to pulp effluent used for fuel coal water slurry and the like.

[0002]

2. Description of the Related Art Among lignin sulfonates, Na salt is generally used as an industrial dispersant. Depending on the application, Ca salt may be good. Therefore, industrially, in the sulfurous acid pulp effluent (hereinafter abbreviated as SSL), Na salt (N
a-SSL) or Ca salt (Ca-SS)
It is general to use L) with Na ₂ SO ₄ as a base substitution for Na salt. CaSO ₄ .2H ₂ O, which is generated by substitution on the basis of Ca-SSL, has a large particle size and is easily separated, so that it is industrially implemented. However, in the case of Mg-based SSL, even if a substance such as Na ₂ SO ₄ is used, it cannot be industrially implemented because it cannot be easily replaced with a base like Ca salt and cannot be separated. .

In principle, the method of substituting Mg-SSL with Na-SSL is considered to be possible by using a water-soluble Na salt which forms a sparingly soluble salt with Mg. Specifically, for example, NaOH, Na ₂ CO ₃ , NaHCO ₃ , (CO
When O) ₂ Na ₂ is used, it should be possible to replace the Mg base with the Na base in the following reaction. Mg-SSL + NaOH → Na-SSL + Mg (OH) ₂ 〃 + Na ₂ CO ₃ → Na-SSL + MgCO ₃ 〃 + NaHCO ₃ → Na-SSL + Mg (HCO ₃ ) ₂ 〃 + (COO) ₂ Na ₂ → Na-SSL + (COO) ₂ Mg Here, Mg (OH) ₂ , MgCO ₃ , (COO) ₂ Mg
Since is poorly soluble in water, it is expected that the reaction will proceed to the right and a base conversion will occur. However, unlike the CaSO ₄ .2H ₂ O that is generated when Ca-SSL is replaced with Na, all of the sparingly soluble salts generated here become fine particles.
Moreover, lignin adheres to the fine particles. Therefore, its separation is industrially difficult and has never been carried out.

[0004]

DISCLOSURE OF THE INVENTION As a result of earnest research, the inventors of the present invention industrially used Mg-SSL to Na-SSL according to the following method.
Invented that can be replaced with. (1) Na ₂ CO ₃ is used as a displacing agent, and its amount is 50-200%
(Against Mg). When the amount of Na ₂ CO ₃ is 100 mol% or less, the remaining Mg
Will increase. On the other hand, when the content is 200 mol% or more, unreacted Na ₂ CO ₃ increases, which becomes a factor of generating insoluble matter in the product.

(2) The concentration of Mg-SSL is adjusted to 5 to 35%. Reaction efficiency becomes poor at a concentration of 5% or less, in addition to 35% concentration or more, an average particle diameter of MgCO ₃ is reduced, also the separation becomes Mutsukashiku.

Other conditions for base substitution are as follows.
It ・ Reaction temperature To increase the base substitution rate and the generated sludge particles
The higher the reaction temperature, the more preferable, but it depends on the material type.
So for conifers,10-130 ℃, preferably 30-1
20 ° C. For hardwood, 90-130 ℃, preferably 100-12
0 ° C.At 10 ° C or lower, it takes a long time for the base substitution reaction time.
However, the particle size of sludge produced is also less than 2 μm,
It becomes difficult to separate. Also, above 130 ° C, the base substitution rate is
Level off and no need for more temperature. ・ Na₂CO₃Addition method Add 50-200 mol% of Mg of Mg-SSL. (Preferably
Is preferably added as an aqueous solution of 100 to 150 mol%). ・ PH If it is strongly acidic, Na₂CO₃CO₂Gas is generated
Therefore, a pH of 5 or higher is preferred.

[0007]

EXAMPLES The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to this.

[0008]

[Table 1]

As shown in Table 1, 500 ml of Mg-SSL was placed in a 1 liter beaker, neutralized to pH 5 with NaOH, and water was added to adjust the concentration to 20%. Next, the mixture is heated with stirring to remove the aqueous solution of the displacing agent.
Mg content of and 150Mol collected and added in about 2 minutes. Then, hold for 2 hours with stirring. After completion of the reaction, sludge was removed using a centrifuge at 10,000 rpm for 30 minutes. When the amount of Mg remaining in the supernatant and the properties and particle size of the settled sludge were measured, the results shown in Table 2 were obtained.

[0010]

[Table 2]

In Table 2, the substitution rate when various substitution agents are used is 80% or more excluding NaOH. However
In the case of NaHCO ₃ , the sludge particle size is as fine as 3 μm, and the properties are also gelled, which is expected to be difficult in terms of sludge separation. Also (COO) ₂
-In the case of Na ₂ , there is no problem with the substitution rate, sludge particle size , and separation, but there is a problem of higher cost than other substitution agents. On the other hand, when Na ₂ CO ₃ was used, the substitution rate was 90% or more, and it was found that there was no problem with the sludge particle size property.

[0012]

[Table 3] Table 3 shows the results of changing the SSL concentration by limiting the substitute agent to Na ₂ CO ₃ .

It can be seen that when the SSL concentration is adjusted to 5 to 30% and the substitution agent addition ratio is set to 150 Mol%, the CaCO ₃ particle size is large and the separation is good. However, when the SSL concentration is 50% and the base substitution rate is 50 mol%,
% Or less, and if it is 300 mol%, the SSL viscosity becomes high and sludge separation becomes difficult. Further, when the SSL concentration is 2%, the concentration becomes too low and the concentration cost increases, which is not economical.

[0014]

[Table 4] Table 4 shows the results of changing the base substitution temperature between coniferous and hardwood SSL species with the substitution agent limited to Na ₂ CO ₃ .

[0015]

[Table 4]

In the case of softwood, the base substitution temperature has almost no effect, and there is no problem with the base substitution rate and the sludge particle size. On the other hand, in the case of hardwood, when the base replacement temperature is 80 ° C. or lower, the base replacement rate sharply decreases, and the sludge particle size becomes 3 μm or less, which makes separation difficult. However, it was found that when the base replacement temperature was set to 100 ° C. or higher, there was no problem with the base replacement rate and sludge separability.

[0017]

According to the present invention, when replacing the base of Mg-SSL, sodium carbonate of 50 to 200 Mo is used as a substituting agent.
1% (against magnesium) and SSL concentration of 5
By adjusting the base replacement temperature to ˜35% and the base replacement temperature to 10 to 130 ° C., the base replacement can be easily performed.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumifumi Nakamoto 2-8-1, Iida-cho, Iwakuni-shi, Yamaguchi Sanyo-Kokusaku Pulp Co., Ltd., Production Technology Laboratory (56) References ) JP-A-55-137286 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C01D 5/00 C02F 1/58 D21C 11/02

Claims (3)

(57) [Claims] 1. A base replacement method for effluent, wherein sodium carbonate is used as a displacing agent when displacing magnesium sulphite pulp effluent with sodium sulphite pulp effluent. 2. The amount of sodium carbonate added is 100 to 20.
The base replacement method for drainage according to claim 1, wherein the content is 0 Mol% (vs magnesium). 3. The base replacement method for drainage according to claim 1, wherein the concentration of drainage is 5 to 35% and the substitution reaction temperature is 10 to 130 ° C.