Abstract:
Dolomite is useful economical resource in many industries such as agricultural, steel, ceramics industries. Some industries use magnesium oxide which is the important component in dolomite. Naturally, dolomite has magnesium carbonate less than 45.65 percent thus this research focus on improvement of dolomite values. The objective of this research is to find an optimum condition for calcination process by varying the dolomite diameter and temperature. Dolomite sample using in this research obtained from Silachai Surat Co., Ltd., Surat thani province, Thailand. The experiment was carry out by using dolomite (25, 50 and 75 mm. diameter) obtained from area A and B. Samples were taken to calcination process at temperature of 1,000, 1,100 and 1,200 degree Celsius. After calcine, the dolomite was analyzed of it is chemical compositions and loss on ignition by xray fluorescent. The results indicated that pre-calcination of dolomite sample had 37, 14 and 47 percent of calcium oxide, magnesium oxide and loss on ignition, respectively. Postcalcination dolomite sample had calcium oxide and magnesium oxide composition higher than 54 and 26 percent and loss on ignition less than 19 percent. Moreover, the postcalcination dolomite sample (75 mm. diameter) of area B at the calcination temperature of 1,200 degree Celsius and at duration of 2 hours had maximum calcium oxide composition of 60.22 percent, maximum magnesium oxide composition of 37.64 percent and minimum loss on ignition of 1.82 percent. The aforementioned condition was suitable for calcination process in this research because magnesium oxide composition of dolomite was exceed the value of 35 percent and loss of ignition less than 6. These results indicated that calcination at high temperature was able to increase dolomite values. Economic analysis by discounted cash flow was executed for investigation feasibility of dolomite values improvement, investment decision and guideline of other dolomite sources of Thailand.