Large reserves of feldspar ores exist in the pegmatite veins at Ban Tak district, Tak province. The main impurities of these deposits are muscovite, biotite and garnet which resulted in high Fe-content that does not meet the raw materials specification for ceramic industry. Chemical compositions of the feldspar ores are 75.93 %SiO2, 14.34%Al2O3, 0.63% Fe2O3, 4.01%K2O and 4.34%Na2O with the fire test results of L= 63.10, a = 2.04 and b = 10.56. The typical specifications of the commercialised feldspar require %SiO2, <70%, Al2O3 >17%, Fe2O3 <0.1% with K2O and Na2O both >5%. The traditional method used to remove Fe-bearing minerals is the reverse flotation. However, this method consumes high sulphuric acid which may create the environmental impact for the nearby area if the treatment is not completely done or the accident occurs. The proposed processes combine the typical process of crushing, grinding and classifying, attrition scrubber, with the wet high intensity magnetic separator (WHIMS) and the direct flotation of feldspar. WHIMS is used to remove muscovite, biotite and garnet which are the causes of high Fe-content. The results showed that efficient separation of Fe-bearing minerals could be achieved by WHIMS in the commercial scale and create the environmental friendly manner. The recovery of processed feldspar is 40% and the chemical compositions of feldspar products are 68.29 %SiO2, 18.69% Al2O3, 0.07% Fe2O3, 5.83% K2O and 6.33%Na2O with the fire test results of L= 82.10, a = -0.56 and b = 3.23 which meet the commercial grade of feldspar.

Abstract. Coal has been one of the major energy sources in the world. Many industries use coal as a main fuel. A coal dust explosion is one of the main hazards of coal utilization because of its massive damage. Coal dust explosion hazards involve the combustible fine dusts or other small particles that present a fire or deflagration hazard when suspended at a sufficient concentration in air or some other oxidizing medium. When such materials are contained in an enclosure, they present an explosion hazard. To eliminate the possibility of dust explosions by ensuring that the dust concentration does not exceed the minimum explosibility concentration (MEC) or the amount of dust per unit volume of air below which the dust cloud cannot propagate flame. Therefore, the objective of this work is to measure the MEC for coal dust explosion with the various conditions of coal storage such as the particle size, moisture of coal, degree of dispersion and delayed time of ignition source to prevent the coal dust explosion which aims to study and design the explosion safety measures for coal dust handing installations. The results show that smaller size of particle, low moisture in coal and high coal dust dispersion can increase the chance or risk of dust explosion. Also, the shorter time of dust dispersion exposes to ignition source can enhance the possibility of explosion in coal storage.

Soil degradation is the conditions with low-soil quality. It can result in low fertility, in soil. To overcome this problem, soil-quality upgrading should be applied. For this study, the acidic soil from Nan, Thailand is used to upgrade the soil conditions to fit well with the agricultural activities by using natural dolomite as a waste from the industries. It is blended with the acidic soil in various ratios from 5-30 % by weight. The optimal conditions for various soil properties such as pH, electrical conductivity (EC), bulk density and soil texture are investigated. From the results, the higher amount of dolomite can improve the soil properties. Acidity is lowered from 4.832 to 6.047. Bulk density is decreased at 1.1114 g/cm3. Particle size distribution is sharply increased with the amount of dolomite. EC values are raised up to 4.25 dS/m. The natural dolomite can increase the soil quality from Nan province.

Abstract. The beneficiation of cassiterite fines from tailing dumps in the Jarin Tin Mine, Thailand were studied through a wet concentration process and dry electrostatic and magnetic processes. The tailing dumps with the size of mineral smaller than 5 mm was collected through the tin mining in the area 20 years ago with the total amount of 17 million tons. The huge pile of the tailing dump may impact environmental in the area, so they need to be treated and recovered for the valuable heavy minerals and sand tailing for the local construction industry. The grade of the tailing dumps are 0.05% Sn, 0.002% Nb, 0.001% Ta. After the wet processing by the screen, hydrocyclone, spiral concentrator, and shaking table, the concentrate consist the most of cassiterite, ilmenite, garnet, zircon, monazite, xenotime, and quartz, containing 20% Sn with a yield of approximately 0.2%. The following dry processes used rotary dryer, screening, electrostatic separator, magnetic separator to separate cassiterite from the heavy minerals and quartz. The final tin concentrate can be upgraded to 72% Sn which can be sold to the tin smelting plant. The economic analysis of the cassiterite recovery processes was conducted using the discounted cash flow model in order to address the cost and benefit of the processes.

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