ANDRITZ explores many avenues on its mission to transform pulp mills into truly circular and self-sustaining production powerhouses. The latest addition to the SulfoLoop product family is the sulfur recovery plant. Based on the ThioKraft technology, it uses bacteria to convert sulfides from green liquor into elemental sulfur.
The process was originally developed by biotech company Paques along with Stora Enso. Paques specializes in biological treatment systems with its technologies being commonly applied in wastewater treatment in the pulp and paper industries. ANDRITZ has now partnered with Paques to offer the sulfur recovery solution for pulp mill circularity.
SulfoLoop sulfur recovery plant using ThioKraft technology
Controlling the sodium sulfur balance at a pulp mill is a crucial task and can be expensive when it comes to purging sulfate streams and adding make-up chemicals to achieve the perfect result. So, imagine being able to control the required sodium sulfur balance in the process, and at the same time producing a usable side stream of sulfur.
The ThioKraft process is designed to benefit the control of the sodium sulfur balance by extracting only a minor share of the green liquor and removing the sulfur using bacteria in a bioreactor. Bacteria originating from soda lakes are able to withstand high salinity and pH. The green liquor is then treated in a bioreactor where the bacteria oxidize sulfide-ions into elemental sulfur, finally producing sulfur cakes.
The sulfur recovery process with ThioKraft
SulfoLoop™ sulfuric acid plants using the ThioKraft process are part of ANDRITZ’s CircleToZero initiative, which includes new technologies aimed at optimizing pulp mill side streams, creating new added value products, and laying a foundation for zero emissions and zero waste production.
ANDRITZ SulfoLoop™ sulfur recovery plant uses ThioKraft technology, a new and clear example of what can be achieved at a pulp mill to control the sodium-sulfur balance, at the same time as enabling significant savings in chemical use.
Brazilian pulp and paper giant Klabin is further closing the circular sustainability loop at its Puma I and Puma II projects in the south of the country. Soon it will be making its own sulfuric acid from captured non-condensable gases at its Ortigueira mill site. ANDRITZ expertise is paving the way.
Interview with Naveen Chenna, Head of Business and Technology Development, ANDRITZ: In a nutshell, can you tell us what the CircleToZero initiative is all about? CircleToZero is a global ANDRITZ initiative with the goal of achieving zero emissions and zero waste at the same time as creating financial growth for customers. For pulp and paper producers this means eliminating unused industry side streams, turning them into new value-added products, and achieving zero waste and zero emission production.
