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The alumina recovery from low grade kaolin (K-JS) treated through thermal and mechanical methods was investigated. High grade kaolin (K-SX) was used as comparison. The optimum calcination temperatures for K-JS and K-SX were both 600 ℃, which resulted in 89.34wt% of alumina extraction from K-JS and 83.37wt% from K-SX. With the increase in calcination temperature, the chemical reactivity of calcined K-JS and K-SX to acid decreased. Mechanical treatment was much more effective in increasing the alumina extraction from activated kaolin. Around 99wt% of alumina was extracted from K-JS ground for 10 hours and 95wt% of alumina was extracted from K-SX ground for 20 hours. The IR results showed that the substitute of Al for Si occurred in calcined K-SX, however, the impurities in K-JS decreased this substitute. More alumina could be extracted from low grade kaolin than that from high grade kaolin under identical thermal or mechanical conditions.
The alumina recovery from low grade kaolin (K-JS) treated through thermal and mechanical methods was investigated. High grade kaolin (K-SX) was used as the comparison. The optimum calcination temperatures for K-JS and K-SX were both 600 ° C , which resulted in 89.34 wt% of alumina extraction from K-JS and 83.37 wt% from K-SX. With the increase in calcination temperature, the chemical reactivity of calcined K-JS and K-SX to acid decreased. More effective in increasing the alumina extraction from activated kaolin. Around 99 wt% of alumina was extracted from K-JS ground for 10 hours and 95 wt% of alumina was extracted from K-SX ground for 20 hours. The IR results showed that the substitute of Al for Si occurred in calcined K-SX, however, the impurity in K-JS decreased this substitute. More alumina could be extracted from low grade kaolin than that from high grade kaolin under identical thermal or mechanical conditions.