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Perhaps you remember the Keanu Reeves movies about choosing between living in a real world versus an artificial one. The Matrix franchise was a blockbuster. Perlmutter & Idea Development’s own solid-liquid separation decision matrix, which we released in 2024, has not gained quite the same following. Yet, we’ve seen great success using it to guide chemical process engineer decision-making. To illustrate the tool’s value, this article discusses how this approach supported a recent specialty water chemical application.

The existing process involve several solid-liquid separation steps, outlined here:

  • Aqueous reaction (RX-1) produces by-product fines which must be removed as the reaction liquid is the product.
  • Reaction liquid continues to a second reaction step (RX-2) to precipitate solids which are the final product.
  • Solids must be solvent-washed (solvent-swap) and dried.
  • Filtrate is then recirculated back to RX-1.

This process uses a manual bag filter for clarification and a manual vacuum nutsche filter for cake washing and drying. In both cases, the filter media is nylon media. The challenge is the solid particles size distribution (PSD) in both steps are fine in the range of < 1 micron and are a low concentration in the 1 -5 % range.

Our objective was to design an automated process that met quality and containment requirements with increased yields. The expansion design was also expected to minimize footprint and use the same solid-liquid separation technology for both steps.

Matrix At Work in Specialty Water Chemical Application

P&ID’s Matrix, of this tool, which you can download for free at MATRIX, addresses three main components:

  1. Material properties
  2. The technology’s mechanical properties
  3. Separation technology performance

To use the Matrix, each box is completed and then discussed with ranked choices evaluated against operational, economic and plant (internal and external) objectives.

In this specialty water chemical example, we first examined the material properties of the slurry including range of PSD, typical solids content of the slurry (% Solids) and the process characteristics in both steps. With several competing parameters there was no clear choice of technology.

Continuing, we looked at filter aid, both as a body feed and precoat, and then examined the resultant cake structure. Throughout our brainstorming and asking of critical questions, we realized that filter aid would be acceptable in the final washed and dried product, as long as the filter aid met the National Sanitation Foundation (NSF) and American National Standards Institute (ANSI) water quality standards. Using filter aid would make the choice of filter media easier.

With this information and analysis, we went back to the P&ID Handbook of Solid-Liquid Filtration and looked for appropriate technologies. Then by completing the Matrix we determined that a Nutsche Filter-Dryer and the use of filter aid as a body feed would achieve all the objectives.

Simplifying the Decision-Making Process

Applying the Matrix helped to provide a framework for our discussions. This straightforward tool allowed P&ID and the client to evaluate technologies using consistent parameters. It simplified our efforts to select the appropriate technology supplier with which to conduct lab and pilot testing. Ultimately, this resulted in a process guarantee for the expansion.

Let me know if this is helpful to you. P&ID is ready to assist you for you solid-liquid separation, process drying and mixing/reacting processes.