Comparison of environmental damage degree of ionic rare earth production process

The production and development of ion-type rare earth ore in China has experienced three fundamentally different process technologies, namely, pool leaching, heap leaching and in-situ leaching, which have significant differences in the environmental management and ecological environmental protection of mines.

In the early 1970s, the rare earth production process was briefly described as “top-soil stripping – ore body mining – pool leaching – recovery immersion liquid – tailings rejection”. This process is commonly known as the “Moving Mountain Movement”. Due to the simplicity of the process, it was widely used at the time.

Mining has caused two major damages to the ecological environment of the mining area. First, direct damage to the surface vegetation. After the mining, the vegetation and the effective soil layer are basically stripped, the bedrock is bare, the vegetation is gone, and the natural restoration is extremely difficult, which is easy to cause soil erosion in the mining area and desertification. The second is the large amount of tailings produced during the mining, and a large amount of land under pressure has caused damage to the original ecosystem of the site.

The heap leaching process began in the late 1990s, and its production process is basically similar to that of the pool leaching process. The “top-soil stripping – ore body mining – dam heap leaching – recovery immersion liquid” cycle is repeated. Due to the widespread use of large-scale machinery mining and shipping, the production scale is larger than that of the pool. The direct destruction of the surface vegetation by the heap leaching process is the same as the pool leaching process, and the occupied yard still occupies a large area.

The in-situ leaching process is the result of the national key scientific and technological research during the “Eighth Five-Year Plan” period. Without destroying the surface vegetation of the ore body and excavating the ore from the topsoil, a series of shallow wells (shallow troughs) are used to inject the leaching solution. The heterogeneous ore bodies under natural burial conditions selectively dissolve or exchange and recover useful components therein. The principle process of the production process is: “in-situ drilling – injection penetration – mother liquor recovery”. Compared with the pool dip and heap leaching process, there is a fundamental difference.

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