SU883217A1 - Pulp production method - Google Patents

Description

(Sft) METHOD FOR OBTAINING CELLULOSE

The invention relates to methods for the production of pulp and can be used in the pulp and paper industry in enterprises producing pulp by the alkaline method. The known soda pulping in the presence of hydrazine. Compared with conventional soda cooking, the yield of cellulose increases by 2-3 l}. However, such a method of obtaining cellulose is not sufficiently effective due to the fact that the whiteness of the obtained product is low, the yield of cellulose does not exceed k8% with a significant content of lignin. The closest in technical essence and the achieved result is the method of sulphate cooking with the introduction of hydrazine into the cooking solution in an amount of 12-30 by weight of absolutely dry wood. The pulp output is higher than in the case of similar soda cooking in the presence of hydrazine due to the advantages of sulphate cooking before soda cooking}. However, in this case the delignification is not high enough. It is characteristic of the considered methods that hydrazine reacts with the active centers of lignin, thereby preventing condensation processes, which contributes to its dissolution in alkali. The addition of hydrazine, even in the sulphate method, does not lead to a noticeable increase in the whiteness and yield of cellulose. The purpose of the invention is to increase the yield of whiteness and the degree of delignification of the target product. This goal is achieved by the fact that according to the method of producing cellulose by alkaline cooking of wood chips with an alkaline solution containing hydrazine, the cooking is carried out in the presence of copper aluminate in an amount of 0.010, 1% by weight of absolutely dry wood. 3 Said salt is preferable in terms of barring: pour it into an alkaline cooking solution by germ-cooking. The method is carried out as follows. Wood chips are loaded into the autoclave and poured over the cooking solution containing hydrazine, aluminum acid is injected in the amount of 0.01-0 U, U to the weight of absolutely dry wood, the temperature is raised to 170 ° C and held for 3 hours. In addition, cooking is carried out in open flasks at the boiling point of the mixture. The boiling temperature of the mixture rises to 0.6 h. The boiling time at boiling point is h. Example 1. Pine wood chips are air-dry. A standard size of 150 g is loaded into an autoclave, filled with a cooking solution containing hydrazine and aluminate. copper in the amount of 0.06 g (0k% by weight of absolutely dry wood). Alkaline cooking is carried out according to generally accepted conditions: rise to a temperature of 170 ° C for 1.5 hours, aging at this temperature for 2 hours. The total consumption of NaOH for sulphate cooking is 30, the sulfidity is 25%. Hydrazine is introduced into the cooking solution in an amount of 15-30% by weight of absolutely dry wood (22, g). Examples 2-6. Lnalo ;, and another 5 experiments were carried out. The difference is in the amount of copper aluminate introduced (see tab. 1). Example 7. In parallel, cellulose is obtained without the introduction of copper-aluminate copper salt in a manner similar to the known regime. Results of alkaline hydrazine cooking with and without the introduction of

0, Qk

 53.6

55,8

O.JO 56.8 0.09

65

2.1

60 62

3.2 2.4 7 .4 aluminum cobalt are given in table. Example 8. The conditions and amount of copper aluminate to be injected and the cooking liquor are similar to Example 1. Alkaline cooking was carried out in open flasks at the boiling point of the solution. The temperature rise time is 0.6 h, the cooking time is 7 h. Examples 9 I Similarly, 6 more experiments are carried out. The difference is in the varkey time and the amount of the copper-aluminate copper salt injected. See Table. 2). Example 15. In parallel, cellulose is obtained without being introduced into the cooking solution containing copper aluminate hydrazine (a known method; the results of alkaline hydrazine cooking of pine chips at the boiling point of the cooking liquid in open flasks with and without the introduction of copper aluminum oxide are given in Table 2. comparing the data presented in Tables 1 and 2, it can be seen that the introduction of copper aluminate according to the proposed method, in comparison with the known, allows to increase the yield of the target product while achieving high levels of delignification (lignin content in cellulose) and cellulose whiteness. The resulting lignin is neutralized after cooking with a weak solution of sulfuric or hydrochloric acid and can be used as a nitrogenous fertilizer, which also contains trace elements. In addition, an increase in the degree of whiteness of the pulp will allow reduce the consumption of chemicals required for bleaching and, consequently, reduce water consumption Table 1

Continued table. one

table 2

Claims (1)

Claim A method of producing cellulose by cooking wood chips with an alkaline cooking solution containing hydrazine at elevated temperature, characterized in that, in order to increase the yield, whiteness and degree of delignification of the target product, the cooking is carried out in the presence of 0.01 · 0 copper-minicarbonate , 1% by weight of absolutely dry wood.