Ash and sulfur removal from tosya lignite coal with boric acid leaching

A kind of boron mineral abounding in our country, colemanite is the primary material used in the production of boric acid. Boric acid is a kind of weak inorganic acid which has a crystal white colour and dissolves in water and is used in germicides, insecticides and deodorizers. In the removal of ash and sulfur with leaching method, acids like HCL, H2SO4, HF and HNO3 are generally preferred. Yet, there are some important environmental inconveniences as they are extremely strong. In this framework, leaching with weak acids is inevitable on the condition that they are cheap. In the scope of this research, leaching experiments were conducted with boric acid on the removal of ash and sulfur from Kastamonu-Tosya lignite coal. Apart from that, to determine the efficiency of the leaching with boric acid, a leaching experiment was conducted with HF, HCL, and H2SO4 ash and sulfur removals were compared. It was observed that boric acid leaching is at least as efficient as sulfuric acid for removal of ash and sulfur whilst it is less efficient than HF leaching. In the optimum conditions, boric acid leaching, ash value in the coal was decreased from 14.62 % to 8.60% and the sulfur in the coal from 8.77% to 5.95%. When it comes to HF leaching, it decreased the ash value in the coal to 3.02% and sulfur value to 4.27%.