Rare earth production of solid waste produced primarily mineral tailings, pyro metallurgical slag generated in producing rare earth alloy, insoluble residues (e.g. leaching residue, acid residue, preferably slag, etc.) produced by a wet process, waste water treatment precipitate slag Wait. Rare earth mineral monazite, bastnasite, mixed rare earth ore, xenotime, and the like, associated with a different degree of natural radioactive elements uranium, thorium and radium, radioactive part inevitably transferred smelt production process In the tailings slag and some smelting slag, most of the solid waste generated in the production of rare earths has a certain amount of radioactivity. Table 1 lists the main wastes discharged from rare earth production plants and their radioactive specific strength [1] .
Table 1 Main waste discharged from rare earth production plants
Waste residue name | Natural Th, U content and radioactivity ratio | source | ||
Th/% | U/% | Radioactive specific strength / (Bq / kg) | ||
Tailings slag Tailings slag Alloy slag Leaching residue Water slag Acid slag Excellent slag Acid slag Radium slag Sewage residue | 0.065 0.024 0.037 Very small amount 0.250 0.420 0.780 0.056  0.004 0.049 | 0.0026 0.0023 Trace Very small amount 0.0003 Trace Trace 0.053 0.003 0.030 | 2.1×10 3 1.2×10 4 1.5×10 3 <n×10 9×10 4 1.4×10 5 8.6×10 4 4.8×10 6 2.41×10 7 1.79×10 7 | Mixed rare earth ore beneficiation Bastnasite ore dressing Production of rare earth alloy by fire method Ion-type rare earth ore leaching treatment Mixed rare earth concentrate concentrated sulfuric acid high temperature roasting Ionic rare earth concentrate acid treatment Mixed rare earth concentrate alkali treatment Alkali concentrate treatment Ibid. Ibid. |
According to the classification of radioactive waste GB 9133-1995, solid waste with a specific radioactivity of less than or equal to 4×10 6 Bq/kg is called low-level waste; the radioactive specific strength is greater than 4×10 6 Bq/kg and less than or equal to 4×10 10 Bq/kg is called intermediate waste. As can be seen from the above table, the waste residue generated in rare earth production is mostly low-level radioactive waste, but there are also a small amount of medium-level radioactive waste, which cannot be simply discarded and needs to be disposed of properly.
The characteristics of radioactive solid waste generated in the process of rare earth smelting and smelting are: large amount of non-radioactive or low-level radioactive waste slag, low radioactive specific strength, and large space at the time of storage; the amount of slag in the radioactive waste slag is small, and The radioactive specific strength is high, and the radioactive materials contained are mainly long-lived nuclides; the valence elements contained in some of the slags have recycling value and need to be temporarily stored.
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