Potassium Solubility of the Fly Ash from Corn Straw Power Plant

Abstract

The industry of biomass power in China has been growing tremendously in recent years, but it is faced with many challenges now. The low efficiency of straw combustion in the boiler results in that the carbon content in the fly ash could reach 15~30%. The ash is also rich in silica, potassium, calcium and has a lot of microelements. A kind of fly ash from a biomass power plant mainly uses corn straw as feedstock was studied. XRF analysis showed that the contents of K2O, CaO and MgO in the ash were 7.22%, 13.61% and 7.22%, respectively. Leaching experiments were conducted to evaluate the solubility of nutritive elements K, Ca and Mg in the ash. The results indicated that acid could enhance the solubility compared with pure water. Under the optimal conditions of filtrate final pH neutral, leaching time 20min, ratio of liquid to solid (L/S) 2, reaction temperature 40°C and stirring time 1min just for homogenization, 36.9% of K, 42.8% of Ca and 10.1% of Mg in the ash could be extracted. These dissolution rates were still very low, that means, the thorough extraction is not very easy and further research should be continued to make the straw power industry ecological and sustainable.