Combined process using grasses as raw materials

Abstract

The invention discloses a combined process using grasses as raw materials. The combined process is a whole-process reaction process comprising a preparation process of a high-grade paper slurry, a preparation process of a pulp for packaging paper, and a preparation process of a foliar fertilizer. The preparation process of the high-grade paper slurry mainly includes the process steps of: three reactions in three reaction tanks, four times of extrusion and pulping by a high concentration pulping machine; and the slurry with high yield is prepared. Pulp squeezing water obtained by first alkali addition softening, first pulp squeezing and / or first two times of pulp squeezing in the preparation process of the high-grade paper slurry is used as a raw material for the preparation process of thepulp for packaging paper; the pulp squeezing water containing a part of cellulose and unreacted agents is subjected to softening and grinding treatment to obtain the slurry for packaging paper. Squeezing water produced in the preparation process of the pulp for packaging paper is recovered and treated as a raw material for preparation of the foliar fertilizer. The combined process has the advantages of no black liquor discharge, water recycling, and energy conservation; therefore, the combined process is a green pulping process.

Description

technical field [0001] The invention belongs to the technical field of papermaking and waste liquid recovery thereof, and in particular relates to a combined process using grass plants as raw materials. The process jointly prepares high-grade paper pulp, packaging paper pulp and foliar fertilizer. Background technique [0002] Paper is an important item closely related to human life. It has developed into a raw material for packaging, printing, cigarettes, stationery, machinery, building materials, military industry and other industries. The paper industry has a wide range of applications in all walks of life. The development of the paper industry directly It reflects the level of a country's national economy and civilization construction. my country is a big country for papermaking and papermaking, and papermaking has become an important basic industry that drives the development of the national economy. According to China's 2015 Paper Industry Annual Report, in 2015 there...

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Problems solved by technology

[0005] The traditional papermaking process is to process the papermaking raw materials through pulping, modulation, papermaking, processing and other main processing steps. Among them, pulping is the first step and the most critical step in papermaking. The pulping process is to remove the pulping raw materials. The process of lignin; the removal process is mainly divided into chemical pulping method, mechanical pulping method and semi-chemical pulping method, chemical pulping method is the most widely used production method; it mainly includes crushing-cooking-alkali softening- Squeezing-washing-bleaching and other operations; the chemical pulping method is to use chemical liquid to continuously cook the flakes in a device that is fed with high-temperature steam above 150°C, so that the lignin in the pulping raw materials can be produced with chemical reagents at high temperature. The reaction produces water-soluble matter, which is separated from the fiber into a slurry; although chemical pulping retains the natural length of the fiber and removes most of the lignin, the yield of the slurry is low and the pollution is large, and in the cooking process, due to chemical agents The addition of the prepared pulp has an unpleasant smell and a bitter taste, and a large amount of black liquor will be produced in the subsequent squeezing and washing process

[0006] Black liquor contains a large amount of suspended solids, organic pollutants and toxic substances, of which about 30-35% are inorganic substances, and the main components are sodium hydroxide, sodium carbonate, sodium sulfide, sodium sulfate and other sodium salts combined with organic substances ; It also contains 65-70% organic substances, the main components are lignin, resin, starch and low-molecular compounds, etc. If the black liquor is directly discharged into the water body, it will cause serious pollution, such as containing a large amount of fiber, pigment and inorganic Salt papermaking wastewater will turn the water black and have a special stench; the biochemical oxygen demand (BOD) of papermaking black liquor containing high concentrations of organic pollutants can be as high as 5000-40000g / L, which will consume a large amount of dissolved water. Oxygen affects the water quality; a large amount of alkaline substances in the black liquor will cause the pH value of the water to rise sharply and destroy the balance of the water environment

[0007] Traditional alkali recovery technology equipment is complex and requires a large amount of investment. It is reported that a set of alkali recovery equipment generally requires an investment of more than 30 million yuan, and its daily operating costs are also relatively high. It is as high as 2671 yuan / ton of alkali, while the market price of sodium hydroxide is only 1800 yuan. Therefore, most of our enterprises are unable to carry out alkali recovery at present, but directly discharge the black liquor or directly discharge it after dilution, causing environmental pollution, especially in water areas. extreme pollution

[0008] At present, there are relevant reports on the preparation of fertilizers from papermaking black liquor, and they have not been effectively promoted. Not only that, but there are also some problems in these technical solutions: (1) the cost is high; (2) the quality of the prepared fertilizer is poor , poor fertilizer efficiency; (3) it is necessary to add other nutrient sources, and its consumption is equivalent to that of fertilizers prepared by other methods in the prior art; (4) there are few utilization methods and a single variety

[0011] Disclosed in Chinese patent CN101486604A is a kind of fulvic acid foliar fertilizer of ammonium method grass pulp black liquor as raw material, and this foliar fertilizer is to use imonium method grass pulp black liquor as raw material, and in the preparation process of described foliar fertilizer , using two consecutive flash evaporation-five-effect evaporation technology to concentrate the black liquor of ammonium method grass pulp, although in order to improve the utilization rate of heat energy, it adopts the method of steam recycling, but it is inevitable to introduce additional energy; not only that , the equipment for this process is in a high temperature state for a long time, and a large amount of money is also required for equipment wear and maintenance

Moreover, this preparation process only adds soluble trace elements to the concentrated ammonium method straw pulp black liquor, and does not do any treatment to harmful substances and suspended solids in the imonium method straw pulp black liquor, which are still retained in the obtained Fulvic acid foliar fertilizer; plants that absorb this kind of foliar fertilizer may also deposit some toxic and harmful substances and elements in the body while supplementing nutrients

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