Anawati John, Azimi Gisele
Laboratory for Strategic Materials, Department of Chemical Engineering and Applied Chemistry, University of Toronto 200 College Street Toronto Ontario M5S 3E5 Canada
Department of Materials Science and Engineering, University of Toronto 184 College Street Toronto Ontario M5S 3E4 Canada.
RSC Adv. 2020 Oct 21;10(63):38640-38653. doi: 10.1039/d0ra07210a. eCollection 2020 Oct 15.
With the rapid increase in the world population, the global demand for food production has been increasing steeply. This increase has resulted in an increased demand for phosphorus crop fertilizers and livestock feed additives. Considering recent predictions that the global reserves of high-grade phosphorus resources would deplete within 15 years, new initiatives have begun to utilize low-grade resources to ensure sustainable supply of this essential nutrient. The main challenge with the use of low-grade resources is the difficulty with the efficient and economical separation of phosphorus from the other constituent elements, such as iron, aluminum, and magnesium. Most previous studies on the adoption of low-grade phosphate ores have focussed on ore beneficiation processes which are expensive, complex, and in some cases inefficient. In this study, we develop an integrated process for the direct recovery and separation of dicalcium phosphate dihydrate for fertilizer and livestock feed additive production from a low-grade (2.0 wt% P) iron-rich (19.7 wt% Fe) phosphate ore. The process combines leaching using dilute sulfuric acid (0.29 M) and selective precipitation using calcium oxide. During selective precipitation, ethylenediaminetetraacetic acid (EDTA) is used as a stabilizing agent to prevent iron and phosphorus co-precipitation. This process can be operated as a closed loop, allowing the recovery and recycling of both water and EDTA, while eliminating the production of liquid waste. The developed process achieves around 70% phosphorus recovery as an industrial-grade (19 wt% P) dicalcium phosphate dihydrate product with minimal iron, magnesium, and aluminum contamination, while also producing value-added calcium sulfate dihydrate (gypsum) and iron/magnesium byproducts. This process enables economical and sustainable recovery of phosphorus from low-grade ores, which can address the rising global demand for food production.
随着世界人口的快速增长，全球对粮食生产的需求急剧增加。这种增长导致对磷作物肥料和牲畜饲料添加剂的需求增加。考虑到最近的预测，全球高品位磷资源储备将在15年内耗尽，新的举措已开始利用低品位资源来确保这种必需营养素的可持续供应。使用低品位资源的主要挑战是难以将磷与铁、铝和镁等其他组成元素进行高效且经济的分离。以前关于采用低品位磷矿石的大多数研究都集中在矿石选矿工艺上，这些工艺成本高、复杂，而且在某些情况下效率低下。在本研究中，我们开发了一种综合工艺，用于从低品位（2.0 wt% P）、富铁（19.7 wt% Fe）的磷矿石中直接回收和分离二水磷酸二钙，用于肥料和牲畜饲料添加剂生产。该工艺将使用稀硫酸（0.29 M）浸出和使用氧化钙选择性沉淀相结合。在选择性沉淀过程中，乙二胺四乙酸（EDTA）用作稳定剂以防止铁和磷共沉淀。该工艺可以闭环运行，实现水和EDTA的回收与循环利用，同时消除废液的产生。所开发的工艺可实现约70%的磷回收率，得到工业级（19 wt% P）的二水磷酸二钙产品，铁、镁和铝的污染最小，同时还生产增值的二水硫酸钙（石膏）和铁/镁副产品。该工艺能够从低品位矿石中经济且可持续地回收磷，从而满足全球对粮食生产不断增长的需求。
