In the recovery process of rare earth (RE) from the weathered crust elution-deposited rare earth ore, ammonium sulfate is used as the leaching liquor to leach RE, and then the leachate containing RE3+ can be precipitated by oxalic acid and the RE oxalate precipitation mother liquor is reused for RE leaching process after removing the residual oxalic acid by precipitation with calcium hydroxide. However, the reuse process of precipitation mother liquor cannot proceed in the strong acid and alkali restricted areas and the discharge of mother liquor which contains a large amount of ammonium salt will cause ammonia-nitrogen waste and pollution. In order to realize the reuse of the precipitation mother liquor in this area, the direct reuse of RE oxalate precipitation mother liquor for RE leaching was investigated in this study. The RE oxalate precipitation process and the RE leaching process with oxalic acid were studied. The results showed that the residual oxalic acid concentration in the mother liquor can be controlled lower than 0.8 g/dm3 at pH 2-3 when the RE concentration in the leachate was 0.1- 1.5 g/dm3 and the RE precipitation rate reached to 94%. In addition, RE leaching efficiency was up to 90% while the oxalic acid concentration in the prepared mother liquor was 0.2-0.8 g/dm3, pH 2-3. Therefore, the precipitation mother liquor with oxalic acid concentration less than 0.8 g/dm3 could be directly reused for RE leaching. However, considering the different performance of RE ores, the recommended oxalic acid concentration in the direct used precipitation mother liquor was lower than 0.6 g/dm3.
2
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
Przeprowadzono badania mające na celu określenie wpływu parametrów syropu międzykryształowego i cukrzycy I na zmiany szybkości krystalizacji sacharozy. Na podstawie przeprowadzonych analiz wyznaczono szybkość krystalizacji cukrzycy I w warunkach przemysłowych. Określono również współczynniki hamujące szybkość krystalizacji h i η. Sumując wszystkie czynniki hamujące proces krystalizacji, zaproponowano ujęcie zależności iloczynu czynników hamujących w funkcji względnego czasu krystalizacji.
EN
Investigation was carried out with the aim to determine the effect of parameters of mother liquor and seed magma on changes in the rate of sucrose crystallization. On the basis of analyses the rate of seed magma crystallization in industrial conditions was calculated. Coefficients inhibiting the crystallization rate h and η were also determined. Summing up all factors that inhibit the process of crystallization, it was proposed to present the product of inhibiting factors in the function of relative crystallization time.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.