Sorting Technologies for CCA Treated Wood

Objective To design and implement an automated system to effectively sort CCA treated wood from other wood types at facilities such as C&D facilities

Automated System Designed using x-ray fluorescence technology or Designed using laser induced breakdown spectroscopy technology

Motivation CCA treated wood => ~ 6 % of all wood waste at C&D facilities Amounts of CCA treated wood at C&D facilities increasing At 6 % level, cannot be used as mulch or burned to generate fuel

Sorting Studies Chemical stain method –laboratory results –field results from pilot studies X-ray fluorescence (XRF) –laboratory results Laser Induced Breakdown Spectroscopy (LIBS) –laboratory results

Automated System –X-ray fluorescence –Laser induced breakdown spectroscopy Training and monitoring –chemical stains

Chemical Stains Chrome Azurol S PAN Indicator Rubeanic Acid

Performance on whole wood 0.25 pcf 0.6 pcf 2.5 pcf

Laboratory Results Colors get darker with increasing retention levels Chrome Azurol and PAN indicator performed best: colors not usually found in C&D waste materials reacted fastest and easy to apply Rubeanic acid: green color could be mistaken for other material inconvenience of spraying with two different solutions

Field Studies Performed to determine if chemical stains could be used at C&D facilities to sort CCA treated wood from other wood types Three facilities studied

Findings from Field Studies PAN indicator and Chrome Azurol S performed best Time and labor intensive Assumed untreated wood waste piles contained 9 % to 30 % of CCA treated wood CCA treated wood found mostly in construction type debris Demolition debris contains increasing amounts of CCA treated wood

Current Practical Applications Sorting Small Quantities of Treated from Untreated Wood Screening Fuel Quality Training Tool

Design for Shelter

Detector Mounting Design

XRF Based on emission of x-rays Characteristic x-ray emitted by the element is read by the instrument

Model 400 No special training required User friendly Printout or output easy to read and understand Head Analyzer

XRF Instruments Low maintenance, few consumables, easy cleaning No repetitive calibration necessary (6 mo. to 2 yrs.) Life span of 10 years

XRF Instrument Cost range from $20,000 - $100,000 Detector replacement cost of $1,800 - $2,400 (life span of 5 years) Licensing may be required Sensor protected by a small beryllium window ($100 for replacement)

Results of XRF Studies Arsenic is the best indicator metal, although all three metals can be analyzed for Optimum count time of 2 seconds, would be even less for on-line analysis 1,800 ft/hr for detection of 1-ft board (2 s) 3,600 ft/hr for detection of 1-ft board (1 s) Detection of CCA for Model 400 is possible at 1 inch distance with a plastic shield

LIBS Based on creation of microplasma by the use of a high-power laser A signal from emitted light transmitted to a detector

LIBS Instruments Detectors –Continuum Minilite ($50,000) More sensitive Monitors one element at a time –Ocean Optics ($2,000) Not as sensitive Monitors more than one element at a time Laser

LIBS Instruments Flash lamp replacement cost of ~ $1,000 (replacement every 3 to 6 months) No licensing required

LIBS Results Elements with higher wavelength more sensitive to analysis –Chromium (425 nm): detected –Copper (327nm and 324 nm): detected, smaller signal –Arsenic (200 nm): not detected Chromium best indicator metal

LIBS Results Shortest analysis time 1/5 of a second (200 ms) 4,500 ft/hr for detection of 1-ft board Spacing detector and wood being analyzed could be 12 “

Air Conveyor Belt Air-Tight Box Laser Lens Mirror Puff of Air Laser Beam Up to 12” Detector To PC Glass Window Fiber-optic Cable

Questions?