FS-FPL-4710

Frothing Agent Spray:

A Novel Technology to Increase Yield in Recycling of Waste Paper

We have demonstrated the frothing agent spray concept to achieve separate control of the application of deinking chemicals, i.e., frothing agent and collector, in flotation deinking of waste paper. We conducted batch flotation using a column flotation cell to deink toner printed papers to avoid potential problems in systems require complex deinking chemistry in initial feasibility study.

The results indicate that a stable froth can be obtained by applying frothing agent through a spray on top of the column flotation cell rather than apply the frothing agent in the pulp suspension in conventional flotation. Furthermore, fiber loss can be reduced under equivalent gain of brightness of the handsheet made of deinked fibers. Then, we conducted batch flotation experiments using two commercial flotation cells, i.e., Voith Sulzer flotation cells with 18-liter capacity (E-18) and 250-liter capacity (E-250), to deink old newsprint paper (ONP) and a mixture of ONP with old magazine paper (OMG), respectively.

It was found that deinking efficiency could be significantly improved and fiber loss could be reduced if the foam in the flotation cell was suppressed by adding a defoamer, then regenerated at the top layer of the flotation pulp suspension using a foaming agent spray technique from the top of the flotation cell.

Compared to a conventional flotation process, the new process reduced the fiber loss during the flotation by about 50% with the same brightness gain (around 9) for deinking ONP and a mixture of ONP and OMG. Successful demonstration of scale-up of the frothing agent spray concept in laboratory was observed in deinking a mixture of ONP and OMG using both the E-18 and E-250 cells.

In this project we will conduct further scale up of this novel technology at our lab's pilot plant batch deinking facility.

Contact: JunYung Zhu

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