Peniakoff
Peniakoff :
A process for extracting aluminum from bauxite or other aluminous ores. The ore is roasted with coke and sodium sulfate in a rotary kiln at 1,200 to 1,400ºC; this converts the aluminum to sodium aluminate, which is leached out with dilute sodium hydroxide solution. The basic reactions are: Na2SO4 + 4C = Na2S + 4CO ; Na2SO4 + 2C = Na2S + 2CO2 ; 4Al2O3 + Na2S + 3Na2SO4 = 8NaAlO2 + 4SO2. The sulfur dioxide is recovered as sulfuric acid and reconverted to sodium sulfate. Alumina hydrate is precipitated from the sodium aluminate by carbon dioxide. The process has not become widely accepted because the product is contaminated by silica, but it was used in Belgium before and after World War I and in Germany in the 1920s and 1940s. (Check source for accuracy of chemical formula)
