Extraction of Alumina from Local Clays by Hydrochloric Acid Process@@@إنتاج الألومينا من الطفلة الوطنية بالمعالجة بحامض الأيدروكلوريك
A bench work study was carried out to investigate the use of kaolinitic clay containing 29.4% Al2O3 extremely abundant in Saudi Arabia for the production of pure alumina by calcination at 700 o C for 1h (recommended by previous investigators) then leached by hydrochloric acid. The effects of leaching temperature (25 o C to boiling temperature), period of activation (10-150 minutes), acid concentration (1M – 6M), particle size (–8 to –200 standard Tyler screen mesh), acid to clay weight ratio (4:1 to 15 : 1ml acid/gm clay) on alumina extraction were investigated. The recommended leaching conditions are: 6 molar for acid concentration at boiling conditions under reflux, one hour for leaching time, –100 mesh standard Tyler screens for particle size of calcined clay and 10 ml acid/gm clay for acid to clay weight ratio. Leaching this local clay sample under these conditions resulted in 32% alumina extraction. Local kaolinitic clay were calcined at temperatures varying between 400 o C and 800 o C at different calcination periods (5 to 120 minutes). The calcined clay was then leached with 3M HCl acid under the above-recommended leaching conditions. The optimum calcination conditions were 600 o C and 1 hour for calcination temperature and time period, respectively. The corresponding alumina extraction from local clay sample is about 63%.
Kinetic model for Ukpor clay dissolution in hydrochlorlc acid solution
The dissolution kinetics of Ukpor clay in hydrochloric acid is studied. The study was done by varying the various process parameters viz; calcination temperature, reaction temperature, acid concentration, solid-to-liquid ratio, particle size, and stirring speed. The experimental results show that the dissolution reaction increases with increase in calcination temperature, reaction temperature, acid concentration, and stirring speed, while it decreases with increasing solid-to-liquid ratio and particle size. The experimental data were analyzed according to the kinetic models for heterogeneous reaction processes using graphical and statistical methods and it was found that the dissolution of Ukpor clay in hydrochloric acid solution is controlled by ash product layer diffusion. The kinetic equation is given by 1 + 2(1-X) - 3(1-X) 2/3 = 1.40 x 103 C[HCl]0.37 (dp)-0.89 (s/l)-0.63 (w)0.42 exp (-4677/T) t. The activation energy of the dissolution reaction was calculated to be 39.009kJ/mol. This study has shown that Ukpor clay can serve as an alternative raw material for the aluminium industry in Nigeria and the kinetic data can be used in the design of process equipments for large scale production.
Influence of Diluted Spent Wash of Sugar Industries Application on Yield of and Nutrient Uptake by Sugarcane and Changes in Soil Properties
A pot experiment was conducted to study the effect of irrigation with tube well water (S0) as well as with spent wash diluted for 25 (S25), 50 (S5O) and 100 (S100) times on yield of and nutrient uptake by sugarcane grown on Typic Chromustert. The results revealed that application of spent wash diluted at any level increased the sugarcane yield and nutrient uptake significantly over S0. Less diluted spent wash gave higher yield of biomass than the concentrated one. Though, there was tendency for slight increase in the soil salinity due to use of spent wash, yet the nutrient availability of P, K and S increased considerably. Further, there was indication of betterment in some physical conditions of soil.