Loading...

Apatite Digestion and Two-step Leaching in Concentrate Sulfuric Acid for Recovery of REEs’ Cerium, Lanthanum, Neodymium and Yttrium

Kolahdooz, Mohammad Reza | 2019

476 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52053 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Yoozbashizadeh, Hossein
  7. Abstract:
  8. Nowadays, apatite mineral is one of the most sought for the recovery of rare earth elements. This mineral is also the main source of phosphoric acid production. To achieve this end, apatite has to react with sulfuric acid to give phosphoric acid. This process is called the wet process. During the wet process, more rare elements enter the remaining solids called phosphogypsum (PG). For the dissolution of rare elements, PG, which is the same as chalk, can be leach with an acidic solution. In this project, the phosphate concentrate from Chadormalu iron ore waste after characteristics diagnosis is digested in concentrated sulfuric acid at temperatures below 100 ° C, and then hydration is performed to hydrate the PG. During this stage, temperature, time and solid-liquid ratios varied for the recovery of rare elements of cerium, lanthanum, neodymium and yttrium. The results show that temperature and time do not have a particular effect on the retrieve of rare elements in PG, while increasing the proportion of solid to liquid ratio recovery the rare elements. Optimum conditions for recovery of rare earths at 70 ° C, 20 minutes and a solid to liquid ratio of 0.3 are selected. By investigating the production of PG in optimum conditions, we found that almost all of these structures are dihydrate and PG particles are agglomerated in six or eight corners. Then the PG produced under optimal conditions is leachate into nitric acid, so its rare earth elements enter into the acidic solution, during this process we investigated the nitric acid concentration, temperature and solid to liquid ratios. The results show that increasing the temperature and acid concentration and reducing the solid-to-liquid ratio will increase the recovery of rare earths. Finally, the chosen optimum point include: the temperature is 80 ° C, the solid to liquid ratio is 0.1 and the nitric acid concentration of 3 molar. in this project, the Minitab DOE software was designed to design and analysis the results and also we use the HighScore plus software to investigate the results of X-ray analysis
  9. Keywords:
  10. Apatite ; Digestion ; Two Step Leaching ; Rare Earth Element ; Phosphogypsum ; Experimental Design

 Digital Object List

 Bookmark

No TOC