CN1438205A

CN1438205A - Magnesium-ammonium mixed salt steaming-boiling agent for producing culture paper in which the black liquid is directly used as organic fertilizer

Info

Publication number: CN1438205A
Application number: CN 03103952
Authority: CN
Inventors: 上官志强; 范春霞; 杨福明; 上官王点
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-02-15
Filing date: 2003-02-15
Publication date: 2003-08-27
Anticipated expiration: 2023-02-15
Also published as: CN1246259C

Abstract

The present invention discloses a magnesium ammonium double salt digestion agent for producing culture paper and directly using black liquor as organic fertilizer. It includes the method for preparing ammonium magnesium sulfite double salt digestion agent by adopting magnesium oxide, liquid ammonia, sulfurous acid and urea, and the method for making pulp by said digestion agent, concentrating concentrated black liquor separated out in the course of making pulp and making the black liquor into special-purpose organic fertilizer and organic fertilizer for desert field. Said pulp is easy to bleach, and its paper flexibility is good and its paper strength is high, and its pulp-making yield is high.

Description

Magnesium-ammonium double-salt cooking agent for producing cultural paper and directly using black liquor as organic fertilizer

Technical Field

The invention relates to a papermaking technology, and mainly provides a magnesium ammonium sulfite double-salt cooking agent for producing cultural paper.

Background

The chemical pulping method commonly adopted in industry includes two major types of alkaline method and sulfite method. The method for making paper by using grass as raw material has the problems of more black pulping liquor, heavy pollution load, high treatment cost and the like, and simultaneously, the components contained in the black straw pulping liquor are complex and cannot be effectively utilized comprehensively, so that the method is not beneficial to the development of industrial recycling. Although the wastewater from the ammonium sulfite process can irrigate farmlands, the wastewater from the ammonium sulfite process has the defects of equipment corrosion, poor whiteness of paper products, easy yellowing and the like, and although various treatment methods exist, the wastewater cannot be well applied to actual production, so the ammonium sulfite process is mainly used for producing primary color paper at present. Chinese patent publication No. CN 1247914 a describes a cooking agent for producing corrugated board. Today, the global wood pulping can not fundamentally meet the requirements of middle-high grade cultural paper, and the scientific community is more and more concerned by developing a new grass pulping technology, eliminating pollution and comprehensively utilizing resources.

It is an object of the present invention to provide an improved sulfite pulping process. The method does not use caustic soda and sodium sulfite, uses the magnesium ammonium double salt cooking agent without sodium ions, can produce qualified paper pulp, and can directly obtain organic fertilizer by concentrating black liquor, so that the cost is lower than that of the sodium sulfite method, the resources are comprehensively utilized, the pollution to the environment is reduced, and the paper pulp discharged from a large amount of waste liquor in pulping and papermaking is led to a paper and fertilizer co-production way of resource utilization by single production.

Disclosure of Invention

The method of the invention is realized by the following steps:

preparation of ammonium magnesium sulfate double salt cooking agent

According to the reaction

Firstly, mixing magnesium oxide and liquid ammonia according to the proportion of the reaction for preparing the ammonium magnesium sulfite double salt, adding a certain amount of sulfurous acid, and stirring; then adjusting the pH value of the solution to 6-6.5, adding equal amount of urea, and stirring; concentrating the reaction system to obtain square transparent crystals, dehydrating and packaging for later use.

The cooking agent provided by the invention is adopted for pulping, and compared with the sodium sulfite papermaking method, the whole pulping and papermaking process is different in that the concentrated black liquor is treated: the concentrated black liquor separated by the pulp extruder is concentrated by an evaporator until the solid content reaches 30-50%, substances containing nitrogen, phosphorus, potassium and trace elements in different quantities are added according to the requirements on the fertilizer, and the special organic fertilizer is prepared by granulation and drying. Or 3-20% of emulsified asphalt is added after concentration to prepare the desert organic fertilizer with wide application.

The invention is based on the papermaking by an ammonium sulfite method, and the introduced magnesium ions have the functions of protecting the carboxyl of the fiber and preventing the ammonium group from hanging the fiber to cause the paper to turn yellow. Mg in the system²⁺、NH₄ ⁺The organic acid generated by the straw raw materials in the pulping process cannot be quickly neutralized due to weak alkali, and the alkali concentration is increased by adding a large amount of urea, so that lignin condensation caused by local acidification of a system is avoided. The urea is used as a buffering agent, and can not be decomposed under the condition that the temperature is lower than 110 ℃, and small air release is not needed in the temperature rising process; the urea is decomposed when the pulping pressure is 0.4-0.8 Mpa and the temperature is 125-170 ℃, the alkalinity of the system is increased, the whole pulping process is always carried out in a weak alkaline environment, and therefore, the lignin removal and the rinsing of the subsequent process are facilitated. Meanwhile, the cooking agent provided by the invention has stable property, so that the loss of ammonia can be reduced in the storage and papermaking production processes, and the waste of raw materials is avoided.

The paper pulp prepared by the cooking agent provided by the invention is easy to rinse, and has good toughness, high strength and high pulping yield. The method has reasonable process route, simple and convenient operation and low operation cost, can eliminate the pollution of pulping black liquor, comprehensively utilizes plant resources and is beneficial to industrial resource large-scale production.

Magnesium ammonium sulfite double salt cooking agent example:

ingredient ratio (converted to 100% Kg)

Magnesium oxide 14.2

Liquid ammonia 16.8

Sulfurous acid 69

Urea 100

Claims

1. A magnesium ammonium double salt cooking agent for producing cultural paper and directly using black liquor as organic fertilizer comprises a method for preparing a magnesium ammonium sulfite double salt cooking agent; after pulping is carried out by adopting the cooking agent, the separated thick black liquor is concentrated by an evaporator until the solid content reaches 30-50%, and then the concentrated black liquor is further processed into a special organic fertilizer and a desert organic fertilizer. The method is characterized in that: mixing magnesium oxide and liquid ammonia according to the proportion of the reaction for preparing the ammonium magnesium sulfite double salt, adding a certain amount of sulfurous acid, and stirring; then adjusting the pH value of the solution to 6-6.5, adding equal amount of urea, and stirring; and concentrating the reaction system to obtain the magnesium ammonium double salt cooking agent.

2. The method of claim 1, further comprising: adding various substances containing nitrogen, phosphorus, potassium and trace elements into the concentrated black liquor according to the requirements of the fertilizer, and granulating and drying to prepare the special organic fertilizer.

3. The method of claim 1, further comprising: 3-20% of emulsified asphalt is added into the concentrated thick black liquor to prepare the desert organic fertilizer with wide application.