Study On Nitrogen Compounds Pretreatment Technology Of Wheat Straw Chemi-mechanical Pulp

The technology of urea-potassium hydroxide for pretreating wheat strawwas studied in this paper. The black liquor made by this technology was rich innitrogen and potassium element and could be used in the farmland irrigation ormade into the compound fertilizer. This technology could protect theenvironment, at the same time, reduce the cost of dealing with the black liquor.So The technology of urea-potassium hydroxide for pretreating wheat straw hadthe vital significance.The technology of urea-potassium hydroxide for pretreating wheat strawwas studied in this paper with orthogonal experiment. The dosages of urea andpotassium hydroxide, temperature, time and liquor ratio were investigated inorder to produce a chemi-mechanical pulp which the unscreened yield of thepulp was beyond65%. The process parameter of the pretreatment wheat strawby potassium hydroxide-potassium sulfide technology was studied, the resultsshown that the chemi-mechanical unscreened yield was66.03%when thedosages of urea and potassium hydroxide were8.0%and6.0%respectively, andpretreatment temperature, heating time, keeping time at the high temperatureand Liquid ratio were160℃,60min,60min,1:5respectively. The physicalproperties of the hand sheet were as follow: the ring crush compressionresistance index was9.43N·m/g, breaking length was4.87Km and the tightdegree was0.43g/cm~3.In order to improve the tight degree of the paper, the method of singlefactor was studied in this paper when the potassium sulfide was used on cooking.The best cooking conditions were optimized: the dosages of urea, potassiumhydroxide and potassium sulfide were8.0%,6.0%and5.0%respectively, andpretreatment temperature, heating time, keeping time at the high temperature andLiquid ratio were160℃,60min,60min,1:5respectively. The physical propertiesof the hand sheet were as follow: the ring crush compression resistance indexwas11.54N·m/g, breaking length was4.81Km and the tight degree was 0.44g/cm~3. The tight degree still did not achieve the requirement of theexperiment.The method of reducing the dosages of potassium hydroxide was studiedin this paper in order to improve the tight degree of the paper again. The bestcooking conditions were optimized: the dosages of urea, potassium hydroxideand potassium sulfide were8.0%,5.0%and5.0%respectively, whenpretreatment temperature, heating time, keeping time at the high temperature andLiquid ratio were160℃,60min,60min,1:5separately. The physical propertiesof the hand sheet were as follow: the ring crush compression resistance indexwas8.78N·m/g, breaking length was4.75Km and the tight degree was0.55g/cm~3.Finally the physical properties had achieved the national standard A grade level(GB/T13023-2008) of the corrugated paper.Before ESEM environment scanning electron microscope experiment wasdid, black liquor was dried and grind into fine powder in order to testing thecomponent in the black liquor. The results of the study were shown as follow:The content of nitrogen element, phosphorus element, potassium element and pHwere0.047g/L,0.002g/L,0.48g/L and8.5separately, when The content ofcarbon element, sulfur element and silicon element were0.54g/L,0.028g/L and0.012g/L separately. The black liquor could be made into compound fertilizerfor agriculture, if the black liquor was processed in accordance with a method.The purpose was to save the cost, and protect the environment at the same time.But the specific processing method would be still researched in the further. Theresults were shown: black liquor could be used in the farmland irrigation whenthe black which was diluted2.5times was taken10.0milliliter in the soil.