Development Of Preparing Compound Fertilizer Based On Calcium Superphosphate By Concentrated Acid-powder Method

Phosphorus is one of indispensable nutrient during the process of plant growthand development. Calcium superphosphate (SSP) is one of the earliest phosphatefertilizer varieties. Calcium superphosphate can be directly used as a single phosphatefertilizer, and can also be used as the ingredients to product Compound fertilizer. Atpresent, the most of most of China’s small-scale factory in the production of calciumsuperphosphate process used the traditional method-diluted acid-powder method.The method of the process has a lot of problems. For example, a large amount of heatis loss during the concentrated acid’s dilution process, dust pollution is serious, needto dry granulation process in the production, and energy consumption is bigger and soon.In this study, distributed phosphate rock of an enterprise in Henan province isused as the raw material, and further develops a new process for preparation ofcalcium superphosphate–the concentrated acid-powder method. The new processcancels concentrated acid with dilute acid process, avoids energy loss during theconcentrated acid’s dilution process, save the cost of drying and shall not affect thecalcium superphosphate conversion rate, even higher.Based on98%and93%of the concentrated sulfuric acid of industrial commonmass fraction as raw materials, By single factor and orthogonal test method, westudied under the process of preparing calcium superphosphate under two differentmass fraction of sulfuric acid, and get the optimal process. The main contents are asfollows.⑴With98%of the concentrated sulfuric acid as raw material, the optimaltechnology of preparing calcium superphosphate using new method: the dosage ofsulfuric acid is100%of the theoretical amount; grinding and mixing time is30minutes; phosphate rock fineness is smaller than0.125mm. Phosphorus conversionrate of the optimal process reached82.30%, and free acid content of21.36%. ⑵With93%of the concentrated sulfuric acid as raw material, the optimaltechnology of preparing calcium superphosphate using new method: the dosage ofsulfuric acid is105%of the theoretical amount; grinding and mixing time is30minutes; phosphate rock fineness is smaller than0.125mm. Phosphorus conversionrate of the optimal process reached81.06%, and free acid content of25.24%.Using98%sulfuric acid as the raw material, through the research of concentratedacid-powder process to prepare calcium superphosphate, further study on thepreparation of inorganic and organic-inorganic fertilizer based on calciumsuperphosphate. The specific conclusions are as follows:⑴By mass ratio N: P2O5=1:1, we explores the urea different added time onthe experimental results, obtain that urea best added time is at25min. By measuring,the results is that content of the nitrogen was11.18%, the content of phosphorus was15.40%, content of total nutrient was26.58%in fresh fertilizer. Meet nationalrequirements of qualified products that total nutrient content the binary compoundfertilizer is20%or more.⑵Through researches of adding time of potassium chloride (K2O:P2O5=1:1) bynew process:, it concludes that adding potassium chloride best time is25minutes. Bymeasuring, the results is that content of the potassium was12.33%, the content ofphosphorus was15.06%, content of total nutrient was27.39%in fresh fertilizer. Meetnational requirements of qualified products that total nutrient content the binarycompound fertilizer is20%or more.⑶The experimental study of ternary compound fertilizer of NPK based oncalcium superphosphate: Experiments design different NPK ratios (N:P2O5:K2O=1:1:1、2:1:1、1:2:1、1:1:2), The nutrient content of fresh fertilizer are8.1:10.6:6.3、9.6:10.6:4.9、6.2:14.2:5.3、4.6:15.3:9.7(N:P2O5:K2O). The total amount of nutrientsof the fresh fertilizer of different NPK ratios can meet the national requirements ofqualified products that total nutrient content the ternary compound fertilizer is25%ormore.⑷Experimental study of preparing organic-inorganic fertilizer by adding theorganics-crop straw to inorganic fertilizer: By single factor experimental studies of adding time and the amount of straw, it concludes that best time of adding crop strawis10minutes and best adding amount of crop straw is60gram. It further study thepreparation of straw-SSP-Urea organic-inorganic fertilizer and straw-SSP-potassiumchloride organic-inorganic fertilizer, inorganic fertilizer nutrients is essential toachieve organic-inorganic fertilizer requirements (N+P2O5+K2O≥15%). Thisstudy has great environmental and social benefits. For example, it solves the problemof crop straw treatment, prevents atmospheric pollution and nutrient losses caused bycombustion of straw.