化肥和饲料添加剂生产磷流动特征研究

磷是作物和畜禽生长必需的营养元素,同时也是不可再生资源。为了提高农牧业生产力,80%左右的磷矿石用于生产磷肥与磷饲料添加剂,因此提高磷肥和磷饲料添加剂生产效率至关重要。然而关于磷肥和磷饲料添加剂"采矿—选矿—磷酸—磷肥/磷饲料添加剂"整个链条的磷流动特征和各个环节效率的定量研究却很少。本研究通过企业实地调研,建立企业流动数据库,利用物质流分析的方法扩展了NUFER(NUtrient flows in Food chains,Environment and Resources use)模型的磷肥和饲料磷添加剂生产模块。以我国某大型磷化工企业为例,定量揭示磷化工企业"采矿—选矿—磷酸—磷肥/磷饲料添加剂"整个链条磷流动特征、损失和利用效率;分析各种磷肥和饲料添加剂产品生产磷流动、利用效率和磷足迹;并利用情景分析提出提高磷利用效率的策略和优化潜力。结果表明:2015年该企业利用含3.902?106 t P2O5的自然矿石,生产了2.426?106 t(折纯P2O5,下同)磷复肥和磷饲料添加剂,其中磷酸二铵和磷酸一铵是最主要的产品,分别为156万t和54万t。磷酸二铵、磷酸一铵、重过磷酸钙、磷酸一二钙、普通过磷酸钙、复合肥、硫肥和磷酸二氢钾产品的生产效率分别为98%、98%、93%、95%、91%、99%、98%和91%,整个生产链条的生产效率为80%。大多数的磷资源在矿石加工部门损失掉,占磷损失量的51%;其次是矿石开采部门(25%)和磷酸生产部门(14%)。通过提高生产效率和废弃物利用率,磷资源损失预计可以减少42%。研究企业的磷利用效率在国内已达先进水平,但仍有提升潜力。

Phosphorus flow from large-scale fertilizer and feed additive chemical enterprises

Phosphorus (P), as an essential nutrient for crops and livestock, is a non-renewable resource. In order to improve the productivity of agriculture and animal husbandry, about 80% of phosphate rocks are used to produce phosphate fertilizers and P feed additives. Therefore, it is very important to improve the production efficiency of P. However, information on flow characteristics and use efficiency of P in the production chain of "mining-benefaction-phosphoric acid-P fertilizers (feed additive)" has remained scarce. This study was done in support of establishing database on P flow through enterprise survey. The fertilizer and feed additive production module of NUFER (NUtrient flows in Food chains, Environment and Resources use) model, which is based on Material Flow Analysis (MFA) was used. Using a large P chemical enterprise in China as a case study, we analyzed P flow characteristics, P use efficiency, P footprint and P loss in the "mining-benefaction-phosphoric acid-P fertilizers (feed additive)" system and future scenarios for P chemical enterprises. The results showed that of the 3 902 Gg P ore resources (100% P₂O₅, the same as below), only 2 426 Gg ended up in fertilizers and P feed additives in 2015. Diammonium phosphate (DAP) was the highest yield product (1 558 Gg), followed by mono-ammonium phosphate (MAP), NPK compound fertilizer (NPK), triple superphosphate (TSP), di-calcium phosphate (MDCP) feed additive, single superphosphate (SSP), NPS compound fertilizer (NPS) and potassium dihydrogen phosphate (KH₂PO₅). The corresponding yields were respectively 634 Gg, 154 Gg, 130 Gg, 34 Gg, 22 Gg, 3 Gg and 1 Gg. The production efficiency was 99% for NPK, 98% for DAP, MAP and NPS, 95% for MDCP, 93% for TSP and 91% for SSP and KH₂PO₅. The production efficiency of the entire production chain was 80%. Most of the P loss came from phosphate rock processing, which accounted for 51% of total P loss. This was followed by mining (25%) and phosphoric acid product (14%). By optimizing production efficiency and improving recycling rate of wastes, P loss was expected to reduce by 42%. Although the utilization efficiency of P in the enterprise was at an advanced stage in China, there was still room for improvement.