Recovery of Fe and Al from red mud by a novel fractional precipitation process

2020 ◽  
Vol 27 (13) ◽  
pp. 14642-14653
Author(s):  
Fengqin Yu ◽  
Lin Huangfu ◽  
Chao Wang ◽  
Changming Li ◽  
Jian Yu ◽  
...  
Keyword(s):  
Red Mud ◽  
Precipitation Process ◽  
Fractional Precipitation

scholarly journals Effectiveness of Fly Ash and Red Mud as Strategies for Sustainable Acid Mine Drainage Management

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 707
Author(s):  
Viktoria Keller ◽  
Srećko Stopić ◽  
Buhle Xakalashe ◽  
Yiqian Ma ◽  
Sehliselo Ndlovu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Acid Mine Drainage ◽  
Red Mud ◽  
Mine Drainage ◽  
Ph Value ◽  
Coal Fly Ash ◽  
Precipitation Process ◽  
Acid Mine ◽  
Initial Ph ◽  
Acidic Mine Water

Acid mine drainage (AMD), red mud (RM) and coal fly ash (CFA) are potential high environmental pollution problems due to their acidity, toxic metals and sulphate contents. Treatment of acidic mine water requires the generation of enough alkalinity to neutralize the excess acidity. Therefore, red mud types from Germany and Greece were chosen for the neutralization of AMD from South Africa, where this problem is notorious. Because of the high alkalinity, German red mud is the most promising precipitation agent achieving the highest pH-values. CFA is less efficient for a neutralization and precipitation process. An increase in temperature increases the adsorption kinetics. The maximum pH-value of 6.0 can be reached by the addition of 100 g German red mud at 20 °C to AMD-water with an initial pH value of 1.9. German red mud removes 99% of the aluminium as aluminium hydroxide at pH 5.0. The rare earth elements (yttrium and cerium) are adsorbed by Greek red mud with an efficiency of 50% and 80% at 60 °C in 5 min, respectively.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

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