| 简介 |
FIELD : chemistry.
SUBSTANCE : invention can be used in production of catalysts, individual rare-earth oxides and polishing powders. Method of producing carbonates of rare-earth elements (REE) involves feeding a solution of a lanthanum or cerium salt and a solution of a salt of carbonic acid, stirring at temperature of 20–45 °C to obtain a pulp of carbonates, filtration, washing and drying the lanthanum or cerium carbonate precipitate. Solution supply is controlled by pH change in process steps. At the first stage, the pH of the rare-earth carbonates pulp is fed in range of 4.1–5.5 by feeding the solution of the carbonic acid salt. At the second stage, the pH of the lanthanum or cerium salt solution is set in range of 3.7–4.5. At the third stage, the pH of the pulp is fed in range of 6.5–7.0 by feeding the solution of the carbonic acid salt. After reaching the preset value of pH, the pulp is agitated under mixer for 20–25 minutes at the first stage and for 20–30 minutes at the second and third stages. After that, mixer is switched off and pulp is left for 20–30 minutes to mature precipitate of carbonates. Then the pulp is filtered on a vacuum filter. Mixing is performed at agitator rotation speed 800–900 rpm.
EFFECT : invention allows to enhance the product quality and efficiency of the process due to the possibility of obtaining homogeneous crystals of a regular plate-like or acicular shape of controlled size.
2 cl, 5 dwg, 3 tbl, 3 ex |
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