Production of Alumina from Local Clays using Nitric and Acetic Acids

摘要

The study was carried out to investigate the effect of process variables on the production of alumina (Al 2 O 3 ) by leaching of local clays obtained from four different locations in Nigeria – Ikot-Abasi, Enito II, Akpugo and Awgbu containing 56.00%, 8.45%, 25.28% and 14.43% of Al 2 O 3 respectively. The process variables whose effect on alumina leaching investigated were: acids concentration (2M to 10M), calcinations temperature (200 o C to 1000 o C), calcinations time (15 to 75 minutes), leaching time (20 to 100 minutes) and particles size (75 to 1000μm) with the experiment conducted at constant boiling temperatures of the acids used (Nitric and Acetic acid). The recommended leaching conditions used as obtained from literature were: 6M for the two acids concentrations, particles size of 150μm, calcinations and leaching time of one hour and calcinations temperature of 600 o C. Upon leaching of these clays under prescribed conditions, the optimal yield obtained by varying each of the process variables were noted. Calcination temperature was observed to have the highest effect on the yield of alumina extractible providing the highest yield of alumina after analysis using mass adsorption spectrophotometer. The yield of alumina presented under the variation of calcination temperature were: Ikot-Abasi clay and nitric acid – yield of 68.10% alumina; Ikot-Abasi and Acetic – yield of 38.07% alumina; Enito II and nitric acid – yield of 56.50% alumina; Enito II clay and acetic acid – yield of 43.41% alumina; Awgbu clay and nitric acid – 59.04% alumina yield; Awgbu clay and acetic acid – alumina yield of 46.55%; Akpugo clay and nitric acid – alumina yield 53.47%; Akpugo clay and acetic acid – alumina yield 43.23%. It was observed that Ikot-Abasi clayitric acid gave the best yield.