稀土在风化体系中的迁移分馏及富集成矿规律

Weathered crust elution-deposited rare earth ores as the specific rare earth resources in China is rich in the middle and heavy rare earth that arouse a widespread attention in the rare earth industry of the world. However, there is always lack of systemic cognition and integral theroy about the occurrence state, migration enrichment, metallogenic regularity and deposit characteristics of rare earth in the weathered crust elution-deposited rare earth ores. It brings more difficult to guide the prospecting and exploration of the rare earth ores reasonably. Therefore, we are planning to sampling largely to the different weathered crust elution-deposited rare earth ores, and then analyze systematically the mineral properties, the composition of clay minerals, the abrasion pH and the rare earth partitioning of the ore sample using the geostatistics. This study aims to reveal the fractionation effect of the migration enrichment, occurrence state and metallogenic regularity of rare earth in the weathered system, further demonstrate the four major effects of rare earth partitioning which are Ce Loss Effect, Rich Eu Effect, Fractionation Effect and Gd Broken Effect, establish the enrichment mechanism of rare earth and explore a new auxiliary symbol for rare earth prospecting. It will be helpful to cognize the metallogenic regularity of the weathered crust elution-deposited rare earth ores, guide the prospecting practice, enrich the metallogeny mechanism and rare earth element geochemistry, realize the liquid distribution and solution injection reasonably in the in-situ leaching technology and efficient utilization of rare earth resources.

风化壳淋积型稀土矿是我国特有的稀土资源，富含的中重稀土受到世界稀土行业广泛关注，然而风化壳淋积型稀土矿的稀土赋存状态和稀土在风化壳中迁移富集的成矿规律及稀土矿床特征一直缺乏系统认识和完整理论，无法很好地指导稀土找矿和开采。拟通过对不同风化壳淋积型稀土矿进行大量采样，利用地质统计学系统分析矿样的矿石性质、黏土矿物的组成、腐蚀pH值和稀土配分，以揭示稀土在岩石风化体系中迁移富集的分馏作用和稀土赋存状态及成矿规律，进一步论证风化壳稀土配分的铈亏效应、富铕效应、分馏效应和钆断效应这四大效应，构建稀土在风化壳矿体的中重稀土富集理论，探寻稀土找矿的新辅助标志。这不仅有利于认识风化壳淋积型稀土矿成矿规律和指导找矿实践、丰富稀土成矿理论和稀土元素地球化学，而且还有助于风化壳淋积型稀土矿原地浸出工艺的合理布液和注液，实现稀土资源的高效利用。

风化壳淋积型稀土矿是我国特有的稀土资源，富含的中重稀土受到世界稀土行业广泛关注，然而风化壳淋积型稀土矿的稀土赋存状态和稀土在风化壳中迁移富集的成矿规律及稀土矿床特征一直缺乏系统认识和完整理论，无法很好地指导稀土找矿和开采。.通过对不同风化壳淋积型稀土矿进行大量采样，利用地质统计学系统分析矿样的矿石性质、黏土矿物的组成、腐蚀pH值和稀土配分，揭示了稀土在岩石风化体系中迁移富集的分馏作用和稀土赋存状态及成矿规律，进一步论证了风化壳稀土配分的四大效应，构建了稀土在风化壳矿体的中重稀土富集理论。取得的主要成果如下：.探讨了矿石腐蚀pH值的变化规律，发现不同地势的风化矿体遵循腐蚀pH山坳＞pH山梁＞pH山顶，且矿体腐蚀pH值随着深度的增加而增加。山坳矿体黏土矿物腐蚀pH呈略中性，有利于中重稀土的富集，故风化矿体的腐蚀pH值的变化有助于轻重稀土之间的分馏，轻稀土相对集中在风化矿体的顶部，而重稀土富集于风化矿体底部。.分析了不同地势稀土的富集规律，发现山坳背处和山脊处中重稀土所占稀土总量分别为47.82%和42.74%，山坳背处为中重稀土的富集区。山顶、山梁和山坳均呈现轻稀土相对富集的“右倾型”分布模式，矿山中重稀土发生亏损，且亏损强度呈现山顶＞山梁＞山坳的规律。稀土富集倍数C山坳-HREEs＞C山梁-HREEs＞0，表明稀土在山坳的富集程度要高于山顶和山梁，且中重稀土的富集程度大于轻稀土。.考察了稀土离子的迁移规律，发现轻稀土富集在全风化层的中上部，中重稀土含富集在全风化层下部。轻稀土与中重稀土在矿体存在分馏现象。全风化层和半风化层铈的异常值为0.001~0.32、δCe＜1，呈现铈负异常现象。.优化了原地浸出注液工艺，根据离子相稀土主要富集在全风化层和半风化层，而杂质铝则主要富集在腐殖层这一规律，调节注液流量，控制注液孔中液面的高度，使浸取剂只与全风化层和半风化层接触，而不与最上层的腐殖层接触，可从源头解决浸出液中含杂质铝离子高的问题。