Case Study: For months, the white liquor clarifier was a source of constant frustration, its behavior a daily mystery.
The lime mud within would settle too slowly or, without warning, sink suddenly, throwing the rakes into potentially damaging torque spikes. Operators were stuck in a reactive cycle, risking equipment failure with every decision.
We set out to find the root cause. Initial jar tests confirmed lime was the key, but the real breakthrough came from measuring the electrical charge of the mud particles in the liquor from the final causticizer to the white liquor clarifier with a borrowed Arc Scientific brand electroacoustic Zeta Potential meter.
The paper machine team used the Zeta Potential meter to evaluate first pass filler retention on the forming table, as is typical practice in fine paper mills.
How should I phrase this? The paper machine team was sort of, kind of, maybe, not happy, but just ok with loaning their fancy meter to the caustic plant. In matters such as these, the mill manager carries the deciding vote, and we were provided access to the meter. No meters were harmed during the study (whew).
We discovered a clear pattern: a negative Zeta Potential meant smooth operation, but a shift to positive meant over-liming and imminent chaos. We were measuring a cycle that was difficult to detect with the normal set of liquor titrations because of the error band around the titrations.
Tracking the inconsistency upstream, we identified the culprit: a new kiln burner whose "steady" flame actually caused temperature surges, resulting in uneven lime. Variable-quality lime led to significant fluctuations in the slaker, resulting in chronic over- or under-liming of the process.
Our solution was two-fold. We empowered the pulp mill team by providing a way to monitor this "charge window," allowing them to diagnose lime quality effects proactively. Simultaneously, we dialed in the kiln burner for consistent thermal output. Within a week, the clarifier stabilized. Settling became predictable, equipment stress vanished, and the headache was finally cured.
About Mike Ryan
Mike Ryan is recognized for enhancing operational reliability and efficiency, combining deep technical expertise with a strong focus on training and process improvement across a wide range of industrial settings.
He can be reached 24/7 by mobile at +1 (740) 649-2272 or by email at
