JPS5876589A - Production of paper pulp from bagasse - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves the absorption of alkali in bagasse and its grinding, i.e., sugar cane.
This invention relates to a method for producing paper pulp from shredding residue.

When the raw material part used for sugar production is separated from sugar cane, fibrous substances (plant extracts or bagasse,
remains available for other uses. For example, bagasse can be used as fuel. However, people gradually increased the amount and began using it as a raw material for paper. It is possible to produce pulp suitable for paper making from bagasse by any of the Kenkar, semi-chemical or Ken-mechanical methods. The use of mechanical processes in paper pulp production has been of great interest since newsprint can also be made from such pulp.

The most commonly known method for producing chemical mechanical bagasse pulp is the so-called 0usi method. The Kushi process consists of the following steps: 1) Absorption of alkali into the bagasse; 2) Cooking under pressure; 3) Comminution; 4) Steaming under pressure; 5) Disintegration under pressure.

By alkali of bagasse, i.e. sodium hydroxide, Na
Impregnation with 0E is achieved without applying pressure. The amount of alkali administered is 8 times more than the dry amount of bagasse.

The cooking stage is carried out under a pressure of 800 kPa and a temperature consistent therewith. Cooking times vary from 20-60 minutes.

The digestion stage is followed by comminution, which is absolutely necessary due to the heterogeneity of the bagasse entering the process. Some of the raw materials are properly digested and the result is already a paper manufacturing process! It can be led to become a finished pulp.

The heterogeneous bagasse is not disintegrated in the cooking stage and is therefore further processed by other methods. In subdivision, which is a very difficult task in practice, about half of the mud blocks are covered by papermakers 1! and otherwise, the pressure is about Q, 35
It is MPa. The aim of the steam treatment is to soften the bagasse prior to the actual mechanical disintegration. Steaming time is 20-30 minutes.

During disintegration under pressure, the energy is reduced to 200 -
Consumes at the rate of 400 KWH. After milling, the pulp, like the part of the paga sparzo separated earlier in the comminution stage, can then be conducted to a further station 11 for papermaking.

In the Kushi process, several steps in implementation proved difficult to carry out; as a result, the quality and quantity of pulp produced by this process did not meet the set requirements. The entire process is carried out under pressure, which should be noted at the expense of the equipment that this process requires. Due to the pressure method, there are also disadvantageous effects on the quality of the pulp, especially with regard to the light coloration of the pulp.

In the comb method, it is essential to perform subdivision after cooking under pressure. During cooking, the smallest particles of the bagasse mass are sufficiently broken down, but the coarser particles have to be further digested. Properly disintegrated pulp must not be subjected to further processing, i.e., pressurized, steamed, or disintegrated. Such treatment only damages the quality of the pulp and must lead to a poor final result of the pulp - inferior paper. On the other hand, coarse or poorly defibrated bagasse must not be entrained into the fully defibrated pulp during comminution, since this would reduce the quality of the pulp and thus of the paper. It is clearly understood that the quality of the pulp obtained by the comb process did not meet the demands placed on it, given the fact that subdivision between properly and improperly disintegrated pulp is practically impossible. Ru.

Moreover, the comb process has exhibited deficiencies in the production process, among which the difficulties of supplying material from one section of the process to another are cumbersome or entirely insurmountable. In this method, all alkali is added without pressure during the absorption stage.

The amount of alkali is as high as about 8 parts. Bagasse, which resembles wheat straw, becomes extremely slippery. As a result, transport and feeding to the next stage (cooking under pressure) is extremely cumbersome and unreliable. Due to such supply difficulties, the operability of the comb process suffers and even leads to shutdowns.

The object of the present invention is to provide a new chemical-mechanical process for producing paper pulp from bagasse. The process of the invention involves compressing the bagasse with a view to increasing the dry matter content prior to absorption and subjecting it once more to compression to remove the alkali from the bagasse after absorption to 4I'g.

In the first pressurization stage water is removed from the bagasse. Bagasse arriving at the point to be compressed has a dry matter content of 15-201
It has f. On pressurization the dry matter content is 25-351. The aim of the pressurization is to promote and improve absorption in the next step.

Pressure is achieved, for example, by a screw or disc press.

The absorption that takes place after the first pressurization takes place in the absence of overpressure. On contact with the hot alkaline solution, the pressurized bagasse mass absorbs the alkali and is returned to the dry matter content it had before pressurization. Absorption takes place at temperatures between 80° and 100°C. Absorption time is 10-20 minutes. The alkaline dosing lid is calculated with fIC of bagasse containing dry matter of 2
-4th grade.

In the second pressurization stage, a large amount of alkali absorbed by the bagasse is squeezed out. The dry matter content on arrival at pressurization is 15-201 and after pressurization it is 25-351! It is. The second pressing stage likewise takes place with a screw or disc press.

After the second pressurization stage, grinding of the bagasse takes place on the 2R floor. Milling is carried out without pressure, preferably in a plate mill. Energy consumption is 500-ton per tonne in the first milling stage.
It is 800 KWH. 40 per tonne in the second milling stage
Consumes 0-700 KWEI of energy.

According to an embodiment of the invention, the ground hazy pulp is subjected to latent removal. In high intensity milling, the fibers remain crimped, and as the pulp cools, the remaining crimped fibers impede sorting of the pulp and reduce the quality of paper made therefrom. In the latent removal that is part of this invention, the pulp is taken to a tank where it is vigorously agitated to a consistency of 1-511i at 60-90°C.
dilute to Residence time in the tank is 10-30 minutes.

Advantages of the process of the present invention over the comb process include low raw material requirements (yields are 80-84111), low alkali requirements, and a pressure-free process.

Now referring to the attached drawings, in Figure 1 reference number 1 indicates the absorption of alkali into bagasse and number 2
indicates cooking under pressure, 3 indicates comminution, 4 indicates pressure cooking, and 5 indicates disintegration under pressure.

In FIG. 2, reference numeral 6 indicates the first pressurization stage;
7 indicates absorption without pressure, 8 indicates second pressurization stage, 9 indicates first milling stage, 10 indicates second milling stage, and 11 indicates latent removal.

It will be obvious to one skilled in the art that different embodiments of the invention may be modified within the scope of the appended claims.

[Brief explanation of the drawing]

FIG. 1 represents a Zorrock diagram of a process for producing chemimechanical bagasse pulp according to the well-known prior art "Kushi" process, and FIG. 2 represents a block diagram of the process according to the invention. Representatives: Asamura and 4 people

Claims (6)

[Claims] (1) A process for producing paper pulp from bagasse or sugarcane crushing residues comprising the absorption of alkali into the bagasse (7) and its grinding (9, 10), increasing the dry matter content prior to absorption (7). The bagasse is compressed for the purpose of
6) and, after absorption (7), subjecting the bagasse once more to compression (8) in order to remove the alkali from it. (2) The method according to claim 1, characterized in that the absorption (7) following the first pressurization (6) is carried out without applying pressure. (3) The method according to claim 1 or 2, characterized in that the amount of alkali used is 2-41 G calculated relative to the dry matter content of the bagasse. (4) After the second pressurization (8), the bagasse is ground in two stages (9,
10) Claim No. (1)
, the method described in (2) or (3). (5) After the milling (11, 10) the pulp is diluted to a consistency of 1-3 ml at 60-90° C. under strong stirring. Method. (6) The method according to claim (5), characterized in that stirring is continued for 10 to 30 minutes.