Black liquor is quite toxic to aquatic life, and causes a very dark caramel color in the water. It contribute 90% or above COD and BOD of the total emission in the pulp and paper industry. Black liquor has become a critical problem to solve in industries in the case of resource utilization and standard discharge at the same time.
As of now, there are three main ways to separate alkali lignin from black liquor: 1) Acid precipitation method, which by decreasing the pH of black liquor, making the alkali lignin unable to dissolve in the black liquor, settle, or separate; 2) Flocculation, which is mainly the addition of electrolyte into the black liquor( i.e. PAC/ aluminium polychlorid), to breach the balance of lignin colloid, making it settle. In this way, lignin is dicult for reuse, and can only be incinerated; 3)Membrane separation, using KS-BL recycling system, using physical method to realize lignin separation, obtain by-product to produce all kinds of lignin chemical products easily, which is a leading clean production technology, excellent prospects.
APPLICATION CASE
One paper mill within China, using conifers material, alkali pulping technology, capacity 1000m/d black liquor (solid content of black liquor is around 11%), Using KS-BL recycling system, within the highly pure alkali lignin recycled daily, 50 tons of sulfonate lignin can be put out, producing 15k tons annually. Investment can be reclaimed in less than two years. Not only does it solve environmental problems, but also brings added value to products.
SYSTEM SPECIFICATION