国外磷矿资源的四分之三为沉积磷块岩(国外名为磷灰岩),其磷矿物属于碳氟磷灰石,而且通常均与白云石、方解石共生。这样就有一个可浮性相近的碳氟磷灰石与白云石、方解石的分离问题。 碳酸盐型磷块岩和碳酸盐、硅酸盐混合型磷块岩的富集研究,在五十年代,主要有关国对利用西部磷矿区、苏联对利用卡拉套磷矿进行研究。但均未能获得很好解决,所以到了七十年代仍然是取要的研究课题。 美国主要承担研究磷矿的机构有美国矿业局阿尔贝尼(Albany)冶金研究中心 Three-fourths of foreign phosphorite resources are sedimentary phosphorite (aka foreign phosphorite) whose phosphorous minerals belong to fluorocarbon apatite and are usually coexisted with dolomite and calcite. In this way, there is a problem of the separation between fluorocarbon apatite and dolomite and calcite that have similar floatability. In the 1950s, the major countries concerned made use of the western phosphate rock area and the Soviet Union made research on the utilization of the karatta phosphate rock. However, they all failed to be satisfactorily solved. Therefore, by the 1970s, it was still a necessary research topic. The major U.S. institutions that undertake phosphate rock research include the Albany Metallurgical Research Center of the US Department of Mines