Study On The Preparation Of Potassium-bearing Compound Fertilizer With Potash Feldspar

This paper is based on the ion exchange reaction between potash feldspar and phosphorite in the phosphoric acid environment, NPK compound fertilizer and slow-released phosphate is produced by the production of the ion exchange reaction. The procedure of leaching the production of the reaction of potash feldspar with phosphorite in the phosphoric acid environment, the process of producing the NPK compound fertilizer by neutralizing the extracted solution, the effects of different end point pH of neutralizing on the NKP compound fertilizer and slow released phosphate and the release characteristics of the slow-released phosphate were especially investigated.At the leaching the production of the reaction of potash feldspar with phosphorite in the phosphoric acid environment, the orthogonal experiment result shows that, leaching time is the dominant factor of potassium leaching rate, the relatively perfect experiment conditions of the potassium leaching rate are confirmed as follow, temperature: 70℃, leaching time: 60min, water for leaching: 18mL/g; the relatively perfect experiment conditions of the phosphorine leaching rate are confirmed as follow, temperature: 90℃, leaching time: 60min, water for leaching: 18mL/g; so the relaticely perfect experiment conditions of the production leaching process are confirmed as follow, 70℃, leaching time: 100min, water for leaching: 10mL/g, at this conditions, the potassium leaching rate is 91.50%, the phosphorine leaching rate is 90.42%. During the extracted solution neutralizing procedure, the proportion of N, P, K in the NPK compound fertilizer and the available phosphorine content in the slow-released phosphate can be controlled by adjusting the end point pH of neutralizing. With the increasing of the end point pH of neutralizing, the nutrition proportion become more reasonable and the available phosphorine content in the slow-released phosphate reduced.Finally, the release characteristics of the slow-released phosphate in different releasing time and different ratio of solid and liquid are also studied. The line simulation and curve simulation were applied to simulate the release characteristics. The result shows that the releasing of the phosphorine in the slow-released phosphate experienced three period with releasing velocity reduced. In the first period, the phosphorine releasing velocity is relatively fast, then followed the period that the remaining period is relatively long and the phosphorine releasing velocity is relatively slow, in the last period, the available phosphorine has totally released gradually, the overall releasing quantity becomes to the high-point. Compared the line simulation with the curve simulation, they simulate the release characteristics of phosphorine from the different point, the two simulation methods act in common. Compared the simulated values of the two simulation methods with the experimental value, the error of the two simulation methods are both acceptable, and the curve simulation is in better agreement with experimental results. So the line simulation and the curve simulation are both effectual, and the curve simulation is relatively more in the same with the simulation of the release characteristics of phosphorine.The recovery of potassium and phosphorus can both exceed 84% and 85% when the end point pH of leaching is about 6, and the slow-released phosphate also has a higher available phosphorine content and the better release characteristics...