Study On Evaluation Method Of Adaptability Of Phosphate Rock To Urea Sulfuric Acid Compound Fertilizer Technology

In this paper, combined with cleaning process of urea sulfuric acid compoundfertilizer technology we studied the distribution、constituent、classification and thefactor of effecting phosphate rock adaptability; study the influence ofphysicochemical parameters to the rate of urea sulfuric acid decomposing phosphaterock to evaluate the phosphate rock; use the easy and quick mathematical softwareMathCAD to charge calculation of compound fertilizer, and test to verify the ratehave to be reached of urea sulfuric acid decomposing phosphate rock under thecondition of the lowest cost of production. The evaluation methods of phosphate rockare as follows:1) According physicochemical parameters to judge the rate of one phosphaterock which applies to urea sulfuric acid compound fertilizer technology. Becausethere is one kind of qualitative relationship between physicochemical parameters andthe rate of phosphate rock under certain conditions: when any two parameters of thereactivity coefficient、carbon dioxide coefficient、specific surface area are greater thanthe same two parameters of the other kind of phosphate rock,then the rate of thephosphate rock is greater than the other one. So we can speculate the rate of ureasulfuric acid decomposing phosphate rock according to the value of phosphate rockphysicochemical parameters to evaluate the adaptability.For example, the reactivity coefficient、carbon dioxide coefficient of Kaiyangphosphate rock and Yunnan phosphate rock are98.51、0.475and94.14、0.194respectively; The reactivity coefficient、carbon dioxide coefficient of Sichuanphosphate rock and Huji phosphate rock are99.60、0.451and91.62、0.184respectively. The common characteristic of the two team phosphate rock is thereactivity coefficient and carbon dioxide coefficient are bigger but the surface areaare smaller, then the ratio are bigger, so we can reach that the influence of surfacearea is smaller than the synergy of reactivity coefficient and carbon dioxidecoefficient. Also the reactivity coefficient and carbon dioxide coefficient follow the rule.2) Use MathCAD software to calculate under constrained conditions, then wecan confirm the practical quantity of sulfuric acid、urea sulfuric acid proportion andthe rate of phosphate rock when the cost price of one kind of phosphate rock applyingto urea sulfuric acid compound fertilizer technology. Also we can choose differentgrade、different constituent phosphate rock to charge calculation according the gradeof fertilizer, which is able to select phosphate rock optimally and use phosphate rockresources efficiently.For example, the charge calculation result of Yunnan phosphate rock shows thatwhen the practical quantity of sulfuric acid is one hundred percent of the theoreticalquantity and the rate of urea sulfuric acid decomposing phosphate rock is eightypercent,then the cost price is lowest, but the molar ratio of urea of urea sulfuric acidproportion should satisfy the condition that R2≤1.7. And when sulfuric acid dosage isone hundred and ten percent、urea sulfuric acid proportion is2.5and the phosphaterock rate is ninety the cost price of raw material of urea sulfuric acid compoundfertilizer technology would be the lowest.3) Through evaluation test to test under the constrain conditions that practicalquantity of sulfuric acid、urea sulfuric acid proportion the phosphate rock if reachrequired rate.The evaluation test use Yunnan phosphate rock, its right sulfuric acid dosage isone hundred and ten percent and urea sulfuric acid proportion is2.5.Using ABS assurface-active agent is best. When sulfuric acid dosage is one hundred and tenpercent、urea sulfuric acid proportion is2.5and using ABS surface-active agent thephosphate rock rate is78.3%under the certain stirring rate、reaction temperature andpulp moisture content.4) The content of impurities in phosphate rock also effect its adaptability exceptthe grade and reactivity. The viscosity of slurry change by the content of magnesiumoxide and temperature, under the same temperature the slurry viscosity raises firstthen drops following the rise of magnesium oxide content. Because of differenttemperature corresponding different slurry viscosity, so we can meet the requirementof pipeline transportation by temperature control. So, the influence rule of MgO content to the slurry of urea sulfuric acid decomposing phosphate rock can providebasis for the adaptability of phosphate rock to urea sulfuric acid fertilizer compoundtechnology.