Study On Pulping Technology Of Golden Grass And Circulation Cooking Of Black Liquor

In this study,golden grass was used as the raw material of papermaking to analyze its chemical composition and fiber quality.The pulping process was divided into caustic soda pulping and semi-chemical pulping,its pulp properties(pulp yield,kappa value)and paper physical properties were analyzed to verify its feasibility in papermaking.Direct calcification alkali recovery treatment was carried out for the waste liquid of semi-chemical pulping by caustic soda method,and the recycle cooking of calcification filtrate was obtained.The paper making enterprise model based on the recycle cooking process(with a daily production capacity of 350 t SCP)was discussed,and the energy consumption and carbon flow of the pulping unit and wastewater treatment unit of the recycle cooking process were analyzed and calculated.The specific conclusions are as follows:(1)The results of chemical composition analysis showed that ash content,1%Na OH extraction content,phenyl alcohol extraction content,cellulose extraction content,acid insoluble lignin content and pentosan content were 6.34%,48.72%,5.45%,40.10%,16.04%and 25.52%respectively.The ratio of length to width was 90.21.Therefore,Golden grass is a better raw material for pulping and papermaking.(2)The caustic soda method was used for the cooking of golden grass.The dosage of sodium hydroxide,the cooking temperature and the holding time were selected as the cooking reaction parameters.The preliminarily optimal cooking reaction parameters were obtained as follows:Na OH dosage was 20%(mass fraction),cooking temperature was 165?,and holding time was 120 min.The tested values of the pulp yield and kappa value were 41.84%and 19.1,respectively.The basic performance of the hand-sheets(60 g/m~2):whiteness was21.06%,tear index was 4.12 m N·m~2/g,rupture resistance index was 3.70kpa·m~2/g,tensile index was 62.49 N·m/g.(3)The pulping process of semi-chemical by caustic soda method was investigated by single factor test.The pulp yield,pulping effect and paper physical properties were considered,the better cooking parameters were preliminarily determined as follows:sodium hydroxide dosage was 8%(mass fraction),cooking temperature was 120?,and holding time was 120 min.The main physical properties of the paper were as follows:tear index was 2.15m N·m~2/g,bursting index was 0.97 k Pa·m~2/g,tensile index was 24.99 N·m/g.In addition,the tested values of tightness and breaking length were 0.45 g/cm~3 and2.55 km respectively,which met the qualified product standard required by GB/T 13023-2008(tightness?0.45 g/cm~3,breaking length?2.50 km).The tested values of the ring crush index was 9.14 N·m~2/g,which was higher than the requirement of GB/T 13023-2008 for superior products?8.50 N·m~2/g,which meets the production standard of AAA of corrugating medium products.(4)When the calcified filtrate was used to recycle the pulping of golden grass,the pulp yield ranged from 64.99%to 73.98%,and the pulp yield increased by 8.99%.Recycle cooking can improve the pulping effect of pulp and reduce the pulping energy consumption of PFI mill.The paper pulp obtained by recycle cooking had good performance when it was used for making corrugating medium.Based on the experimental data,a paper making enterprise model was established by using the cycle cooking process(with a daily capacity of 350 t SCP).By using the cycle cooking process,the carbon with a net fixed carbon amount of 155.06 t can be achieved during the cycle cooking process.