Fully Assembled Potassium Removal

As mills reduce the amount of effluents and emissions, they retain and recirculate more chemicals in their chemical recovery systems. Specifically, the accumulation of non-process elements such as potassium from the wood can cause corrosion and efficiency problems in the chemical recovery boiler. The challenge is to reduce or eliminate the potassium salts to manageable levels.

Potassium is enriched in electrostatic precipitator (ESP) ash and therefore ESP ash is a favorable stream to process when aiming to control the potassium content of the Kraft liquor cycle. Mills have addressed the problem by purging electrostatic precipitator ash, which causes the added expense of chemical makeup (caustic, sulfate).

The Eco-Tec Potassium Removal System (PRU) offers a more efficient solution for removing potassium salts from the electrostatic precipitator ash. The key element of this system is that it utilizes Eco-Tec’s patented ion exchange process with specialized operating conditions to selectively remove potassium from a solution containing the dissolved ash.

The PRU system efficiency reduces the potassium salts to manageable levels while recovering valuable cooking chemicals (Na, SO4, and CO3). The systems are selected and designed to meet each Kraft mill’s unique operating requirements and chemical characteristics.

Process Description of Potassium Removal

Why Use The Potassium Removal System?

Ash purging is widely used in the industry: no major capital equipment is required but the chemical losses are high. The installation of the Eco-Tec Potassium Removal System (PRU) reduces the risk of boiler corrosion and plugging while recovering valuable cooking chemicals (SO4, and CO3). This reduces the frequency of shutdowns of the recovery boiler.

Each pulp mill has different ash composition. The systems are designed to meet each kraft mill’s unique operating requirements and chemical characteristics.


  • Significantly less floor and head space.
  • Excellent removal efficiency and high chemical recovery.
  • Uses Eco-Tec’s highly efficient Recoflo ion exchange process.
  • No chemicals are required for resin bed regeneration – just water.
  • Increased steam and power production, increased boiler capacity.
  • Pre-assembled, skid-mounted, and Easy to integrate into existing processes.
  • Eco-Tec systems are highly automated and can often be used to service multiple lines.
  • Reduced downtime for recovery boiler washing, reduced operating and installation costs, reduced shipping costs.
  • Factory assembled modules and testing in Eco-Tec’s ISO registered facility assures fast start-up and reliable operation.
  • Proven, quality, corrosion resistant components and materials selected for long service life in a pulp and paper processing facility.
  • Eco-Tec provides start-up supervision, customer training, and access to the ECO-SERV program that includes performance monitoring and 24 hour telephone service.