University of Manchester

Colour X-ray imaging of iron oxide based flocs

Richard Ian Foster
Project Completed

Scientific Case

As part of the ongoing waste management operations based at Sellafield Ltd, the neutralisation of radioactive ferric feeds is used to remove radioactive elements from liquid waste via co-precipitation with Iron, forming solid iron oxide based particulates, before filtration, encapsulation and storage. Through agar embedding, the flocs ‘liquid form’ is retained for observation. Recent work at the MXIF, ‘Three dimensional structural observations of iron oxide based floc’, has allowed for the physical observation of the floc shape, size and structural morphology as these changing parameters have a huge impact on the flocculation and filtration efficiency of the process and ultimately the effectiveness of waste water decontamination.
It is proposed that with the use of colour x-ray imaging, the distribution of chemical elements throughout the flocs can be identified. Understanding the distribution of the elements will allow for a greater understanding of the co-precipitation waste treatment process and the measured decontamination factors. Identifying how the chemical composition of the flocs change depending on the size and shape of the flocs or as a result of the initial feed composition contaminates is also of importance as both have been shown to affect the effectiveness of waste water decontamination and is something of concern to the future success of the operation at Sellafield.
Fully characterising the properties, both physically and chemically, of the floc including formation conditions is currently of importance in order to maintain the processes efficiency both in the short and long term.
Iron oxide/Mixed metal oxide floc/particulates embedded within sterile biological agar

Experiment Design

Iron oxide/Mixed metal oxide floc elemental distribution

Floc: Size range from approximately 10 microns to 2 mm
Resolution: A resolution of 5 microns should be more than sufficient for initial observations
Scanners and Rigs
Nikon Custom 320kV Bay
Not Required
The above experiments would make us of the Nikon Custom Bay, along with the Colour X-ray Imaging detector constructed by Dr Christopher Egan, who will also be a key member of this research.
The proposed work would be split over the course of 5 days

Day 1: Equipment/experimental setup and plimanry sample scans
Day 2: 2D colour xray imaging sample scans
Day 3: 2D colour xray imaging samples scans (continued)
Day 4: 3D colour xray CT imaging
Day 5: Equipment/experiment take down

Sample & Safety

The samples will be suspended in agar and set inside acrylic tubing. Internal diameter 4 mm x external diameter 6 mm x 100 mm length. Some samples will involve the formation of mixed oxide flocs, these will be predominantly iron based in composition but will also contain nickel, lead, chromium, calcium and praseodymium all suspended within agar and all inactive and in mg quantities.
All samples will be prepared externally to MXIF and be brought for scanning on a daily basis.
Flocs may cause irritation if they come into contact with unprotected skin or eyes.
Flocs embedded within agar, which is sealed within acrylic tube so the chance for release is minimal.
Similar samples have been previously run at MXIF as part of a previous experiment which resulted in no health hazards

Scan Records

Project Report