首次系统全面地梳理了冷冻法硝酸磷肥生产的基本原理和关键技术,提出了氨化中和反应后期NH₃/P₂O₅<1.5,以防止生成磷酸钙,造成有效磷退化损失的观点;从根源上找到了磷肥渣中碳酸钙粒子粗大的原因:吸收塔中碳化反应的NH₃/CO₂过小,造成生成NH₄HCO₃为主反应、生成(NH₄)₂CO₃为副反应,转化塔中以生成Ca(HCO₃)₂为主反应,再进行 Ca(HCO₃)₂转化CaCO₃的慢速反应,不利于CaCO₃粒子的超细化,增大NH₃/CO₂会影响全系统的氨碳平衡。在不改变NH₃/CO₂的前提下,磷肥渣采用煅烧分解、铵盐浸取、复合碳化法、对置式多喷嘴预碳化技术为主要特征的新工艺,为磷肥渣生产高纯度绿色纳米碳酸钙提供了技术路线,为传统硝酸磷肥生产工艺的绿色转型提供了可行方案。

For the first time,the basic principles and key technologies of the production of nitrophosphate fertilizer by the freezing method were systematically and comprehensively sorted out.It was proposed that NH₃/P₂O₅ should be less than 1.5 in the later stage of the ammoniation neutralization reaction to prevent the formation of calcium phosphate and the degradation loss of available phosphorus.The reason for the coarse particles of calcium carbonate in the phosphorus fertilizer residue was found from the root cause:the NH₃/CO₂ in the carbonization reaction in the absorption tower was too small,resulting in the main reaction of generating NH₄HCO₃ and the secondary reaction of generating (NH₄)₂CO₃,and the main reaction in the conversion tower was the formation of Ca(HCO₃)₂,followed by the slow reaction of converting Ca(HCO₃)₂ to CaCO₃,which was not conducive to the ultra-fine particle size of CaCO₃.Increasing NH₃/CO₂ would affect the ammonia-carbon balance of the entire system.Under the premise that NH₃/CO₂ could not be changed,a new process characterized by calcination decomposition,ammonium salt leaching,composite carbonization reaction and the counter-flow multi-nozzle pre-carbonization technology was adopted for the phosphorus fertilizer residue,providing a technical route for the production of high-purity green nano-calcium carbonate and a feasible solution for the green transformation of the traditional nitrophosphate fertilizer production process.