What is the primary use of the strong black liquor after it is concentrated?

The primary use of strong black liquor after it is concentrated is to generate steam in a recovery boiler. Black liquor is a byproduct from the pulping process of wood into paper, and it contains a significant amount of organic material and chemicals. When concentrated, this strong black liquor is rich in carbon and other elements that can be efficiently combusted.

In a recovery boiler, the concentrated black liquor is burned, and the chemical energy stored in it is converted into heat. This heat is used to produce steam, which can then be utilized for various purposes within the mill, such as driving turbines for electricity generation or providing heat for the process. Additionally, the recovery boiler also helps in recovering chemicals used in the pulping process, allowing them to be reused, which is a critical aspect of sustainable practices in the pulp and paper industry.

Overall, the process maximizes energy recovery and minimizes waste, making it an efficient method for utilizing strong black liquor.