Beneficiation Technologies for Difficult-to-Process Phosphate Ore

Phosphate ore is a critical strategic non-metallic mineral widely used in agriculture, chemical industry, food processing, and pharmaceuticals. China possesses abundant phosphate reserves; however, these reserves are characterized by a scarcity of high-grade ores, a prevalence of low- to medium-grade ores, and a high proportion of difficult-to-process ores. Furthermore, these ores typically feature fine-grained crystals, tight mineralization, and poor separability.

Magmatic apatite has coarse crystal grains, is easily dissociated, and has good recoverability. It is often associated with magnetic minerals, so flotation is the primary method. A combined magnetic-flotation process can be employed to achieve the comprehensive recovery of phosphorus and magnetic minerals.

Sedimentary-metamorphic apatite has good floatability and is easy to process, so direct flotation is commonly used; for weathered, clay-bearing ores, a combined scrubbing-desliming and flotation process is often employed to improve the grade of feed and reduce reagent costs.

Sedimentary phosphate rock has the largest reserves, consists mainly of fine colloidal phosphate ore, and is the most difficult to process. It is classified into three types based on gangue: siliceous, calcareous, and silico-calcareous. Siliceous types are primarily pretreated using direct flotation or gravity separation; calcareous types commonly employ direct and reverse flotation, as well as roasting-digestion processes; siliceous-calcareous types are the most difficult to process and are often treated using double reverse flotation and combined processes such as gravity-flotation, magnetic-flotation, and roasting-digestion-flotation.

Currently, a comprehensive system of phosphate ore beneficiation technologies has been established, encompassing both single and combined processes, with flotation serving as the core process. For low- to medium-grade, difficult-to-beneficiate colloidal phosphate ores, the synergistic application of multiple processes has become the mainstream approach for improving concentrate quality and resource recovery rates.