Preparation and Properties of Pulp Black Liquor Briquettes

Effects of adding pulping black liquor in the preparation of briquettes were evaluated relative to the properties of the resulting pulp black liquor briquettes. The addition of 2% binder (pregelatinized starch) and a molding pressure of 5 MPa were sufficient to obtain briquettes that complied with DB13/1055 (2009). When 30% of pulping black liquor was added in the preparation of briquettes, the compressive strength, shatter index, moisture content, and the content of volatile matter and ash of the resulting briquettes increased. Moreover, the combustion performance of the briquettes after the addition of black liquor was higher, where the briquettes exhibited an enhanced ignition point, a more stable combustion process, and a 50% higher sulfur-fixation ratio after combustion, compared to the ordinary briquette. However, the thermal stability and calorific value decreased and the ash after combustion of the black liquor briquette contained a higher content of high melting point salts. Therefore, the addition of pulping black liquor in the composition of briquettes should be moderate. The preparation of black liquor briquettes provides an efficient way for utilization of black liquor.