Using Crystallization to Meet Separations Needs in Environmental - - PowerPoint PPT Presentation

Using Crystallization to Meet Separations Needs in Environmental Management

• 1. Separations and Capabilities in Crystallization
• 2. Removal of Sulfates

Ronald W. Rousseau School of Chemical & Biomolecular Engineering Georgia Institute of Technology

Separation Technologies in EM: Role of Crystallization

• Crystallization of pure mineral phases from

supersaturated solutions1

• Pretreatment processes2,4
• Selective separations using new molecules and

materials3,5

• Sulfate removal4,5

1. Nuclear Separations Technologies Workshop Report, DOE, July 2011, p. B‐23 2. Ibid, p. C‐7; 3. Ibid, p. B‐4; 4.

• L. Nassif, G. Dumont, H. Alysouri, R. W. Rousseau, D. Geneisse, Environ. Sci. Technol., 2008,

42, 4940. 5.

• A. Rajbanshi, B. A. Moyer, and R. Custelcean, Cryst. Growth Des., 2011, 11, 2702.

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Crystallization Research Team

ChBE, Georgia Tech

• Daniel Griffin, Graduate Research Assistant
• Martha Grover, Associate Professor
• Yoshiaki Kawajiri, Assistant Professor
• Huayu Li, Graduate Research Assistant
• Ronald W. Rousseau, Professor

Expect interactions with other research teams:

• Bruce Moyer at ORNL
• Bill Wilmarth and David Hobbs at SRNL

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Crosscutting Criteria/Needs for Successful Crystallization Processes

• Yield: recovery of solute in process
• Purity: contamination of product
• Crystal Characteristics: size

distribution and morphology

Crystal Characteristics

Crystallization & Solid‐Liquid Sep’n

Yield Purity

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On‐Line Measurements

• FBRM provides

– chord counts in histogram format – mean of chord lengths distribution – skewness of histogram

• Cord counts Crystal Sizes

– geometric model* – optical model** – empirical model (this work)

* J. Worlitschek, T. Hocker, M. Mazzotti, Part. Part. Syst Charact.,

• 2005. 22, 81.

** N. Kail, , H. Briesen, W. Marquardt, Powd. Techn, 2008. 185, 211.

GT Work on Size Distribution



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Experimental Results

• Fingerprint vector for every size.
• The linearity and additivity is validated by mono

size distribution and mixing of different sizes.

50 100 150 200 250 300 0.01 0.02 0.03 0.04 0.05

Chord length [m] u [ml]

20~53 m 53~75 m 75~106 m 106~150 m 150~212 m 212~250 m 250~300 m 300~425 m 425~500 m

1 

       b Ux x U b

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• Poor glass characteristics
• Corrosion
• Potential process instabilities

Sulfates Cause Issues In Vitrification and Other Storage Forms

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Integration of Sulfate Removal

Salt/Supernatant Al dissolution and processing Sludge Appropriate Processing Sulfate Removal Vitrification Sulfates Sulfate‐containing streams

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• Separate sulfates in forms that do not need to be vitrified

– very low levels of radioactive species – perhaps eligible for saltstone disposal

• Use of crystallization

– crystallize sulfate without Cs and contaminants; i.e. eliminate co‐ crystallization, inclusions – facilitate washing and solid‐liquid separation

Salt processing

• Framework for separation
• Use developed tools:

– FBRM (CSD) – FTIR (solution composition)

• Sulfate solubility in

complex solutions

• Develop process format

Experimental Plan

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Concluding Comments

• Separations technologies are essential

for remediation of environmental issues

• Crystallization is a promising method for

many separations issues

• We have advanced crosscutting

capabilities for on‐line monitoring of crystal size distribution

• We have begun working on the removal
• f sulfates from complex solutions