磷矿稀土在硫、磷混酸体系下的反应机理研究

发布时间：2018-04-13 07:21

  本文选题：磷矿 + 稀土　； 参考：《贵州大学》2015年硕士论文

【摘要】：我国拥有丰富的稀土资源和磷资源,但稀土矿产资源和磷矿矿产资源都是一次性资源,开采使用后永不再生,而稀土和磷是国民经济和技术发展的重要战略元素,磷矿中伴生稀土的综合回收显得尤为重要。因此,本文针对我国典型的含稀土磷矿的矿物学特征及硫磷混酸浸出过程稀土的分布规律和浸出机理进行详细的研究,为我国含稀土磷矿的综合开发利用提供必要的基础理论依据。通过对含稀土磷矿的矿物学性质研究,结果表明,我国典型的含稀土磷矿贵州织金磷矿、河北矾山磷矿、云南磷矿矿物组成和稀土含量有一定差别。织金磷矿以胶磷矿和白云石为主,稀土总量最高,达到了0.118%;矾山磷矿以磷灰石和透辉石为主,稀土总量为0.093%,而云南磷矿以磷灰石和硅酸盐为主,稀土含量最低,不足0.03%。三种磷矿石中,稀土均以铈(CeO2)、镧(La2O3)、钕(Nd2O3)、钇(Y2O3)为主,占到了稀土总量的85%以上,且均以轻稀土为主,其含量达到了60%以上,其中矾山磷矿石中轻稀土的含量高达81.56%。贵州织金磷矿和云南磷矿中稀土主要赋存于含磷矿物中,而河北矾山磷矿中稀土除赋存于磷灰石外,在透辉石、赤铁矿等脉石矿物中也有一定的赋存。贵州织金磷矿和河北矾山磷矿可能存在稀土的独立矿物,但数量很微。通过对含稀土磷矿在硫、磷混酸体系下浸出实验研究,结果表明,硫酸和磷酸加入方式影响稀土的浸出率,先加入磷酸充分浸出矿石再加入硫酸生成磷石膏的浸出方式,有利于提高稀土在溶液中的浸出率;浸出过程,较高的溶液初始磷酸浓度、大的浸出液固比、提高浸出温度以及延长浸出时间,有利于提高稀土的浸出率。实验获得的较佳浸出条件为,溶液初始磷酸浓度50%,硫酸过量系数1,液固比6:1,浸出温度80℃,反应时间180min;在此条件下,P2O5的浸出率达到90%以上,∑REO的浸出率达到63.402%。通过对含稀土磷矿在硫、磷混酸浸出体系下的反应机理分析,结果表明,含磷矿物首先与H3PO4反应生成Ca(H2PO4)2,Ca(H2PO4)2再与H2SO4反应生成CaSO4·nH2O。先加入H3PO4与磷矿颗粒充分反应,在磷矿颗粒反应界面附近形成的Ca(H2PO4)2产物膜层的可透性好,以类质同象形式存在于磷矿中的稀土与H3PO4反应生成的可溶性稀土磷酸盐可透过膜层充分扩散到溶液主体,此时再加入H2SO4,虽然溶液中Ca2+与SO42-生成CaSO4·nH2O的核晶速度较快,但硫酸钙晶体对稀土的包裹作用降低,从而使溶液中稀土的回收率增加。同时,含稀土磷精矿在硫、磷混酸浸出体系下,磷石膏的晶体粒度较细,大多小于10μm,以针状、板片状为主,且随浸出时间的延长,磷石膏的物相有从二水物向半水物转化的趋势,包裹的稀土有被释放的可能性,从而有利于提高稀土的浸出率。最后,磷矿石中稀土的赋存状态的不一致虽然导致了稀土的浸出效果不同,但稀土在硫磷混酸体系下的反应机理是相同的。
[Abstract]:Our country has abundant rare earth resources and phosphorus resources, but rare earth mineral resources and phosphate mineral resources are one-time resources, and rare earth and phosphorus are important strategic elements in the development of national economy and technology.The comprehensive recovery of associated rare earths in phosphate rock is particularly important.Therefore, the mineralogical characteristics of typical rare earth containing phosphate rock in China, the distribution law and leaching mechanism of rare earth in the process of mixed acid leaching of sulfur and phosphorus are studied in detail in this paper.It provides the necessary basic theoretical basis for the comprehensive development and utilization of rare earth containing phosphate rock in China.The mineralogical properties of rare earth containing phosphate rock are studied. The results show that the mineral composition and rare earth content of the typical rare earth containing phosphate rock Guizhou Zhijin phosphate rock, Hebei Fanshan phosphate rock and Yunnan phosphate rock are different to some extent.The content of rare earth is the lowest in Yunnan phosphate rock and apatite and diopside in Fanshan phosphate rock, while the content of rare earth is the lowest in Yunnan apatite and dolomite, and the content of rare earth is the lowest, which is less than 0.03 in Fanshan apatite and diopside, and is mainly composed of apatite and dolomite, while the mineral in Yunnan is mainly composed of apatite and dolomite.Among the three kinds of phosphate rock, the rare earths are mainly cerium, cerium, lanthanum, lanthanum, neodymium, neodymium, and yttrium yttrium, which account for more than 85% of the total amount of rare earths, and all of them are light rare earths, the content of which is over 60%, and the content of light rare earth in alanshan phosphate rock is as high as 81.56%.The rare earths in Guizhou Zhijin phosphate rock and Yunnan phosphate rock are mainly found in phosphorus bearing minerals, while in Hebei Fanshan phosphate rock, in addition to apatite, diopside, hematite and other gangue minerals also exist.There may be rare earth independent minerals in Zhijin phosphate rock of Guizhou and Fanshan phosphate rock in Hebei province, but the quantity is very small.The leaching experiment of rare earth containing phosphate rock in the system of sulfur and phosphoric acid is carried out. The results show that the addition of sulfuric acid and phosphoric acid affects the leaching rate of rare earths, and the leaching method of phosphorous gypsum is obtained by adding phosphoric acid to leaching the ore fully and then adding sulfuric acid to form phosphogypsum.It is beneficial to increase the leaching rate of rare earths in solution, the leaching process, the higher initial phosphoric acid concentration, the higher leaching liquid / solid ratio, the higher the leaching temperature and the longer the leaching time, so as to improve the leaching rate of rare earths.The optimum leaching conditions are as follows: solution initial phosphoric acid concentration 50, sulfuric acid excess coefficient 1, liquid-solid ratio 6: 1, leaching temperature 80 鈩，

本文编号：1743482