Introduction to Emerging Solidification/Stabilization Methods for Mixed Waste

1

• Introduction to Emerging Solidification/Stabilizat
  ion Methods for Mixed Waste
• 4th Lecture ISU/NSNE-618
• (Dr. George will Cover Cement Waste forms)
• Vince Maio
• 9-19-03

2
Outline

• Stabilization/Solidification
• Scope of Methods
• Types of Wastes
• Requirements
• Development Program for Challenging Waste
  Streams
• Inorganic methods
• cements and ceramics
• Organic methods
• Thermosetting and Thermoplastic
• Polymer Extrusion Equipment

3
Types of Radioactive Waste
High Level Waste- Vitrification Mixed Waste-
Various Technologies followed by Solidification/St
abilization TRU waste- S/S may be required for
WIPP transportation Low-Level Waste- S/S widely
used Hazardous Waste- S/S widely used
4
Solidification/Stabilization
Solidification - Techniques that modify the waste
to form a solid material - Monolithic or
granular. Encapsulation-Type of Solidification
involving a coating or a jacket. Usually organic
process deployed Stabilization - Techniques to
reduce the hazardous potential of a waste by
converting the contaminants into less soluble,
mobile or toxic forms Goal - Perform
solidification to meet stabilization requirements
5
Scope of Methods
Vincent Maio Give thermosetting and
thermoplastic definitions
Various Methods Have Undergone Development By
DOE Range of Techniques Portland Cement
Grouting to Thermal Vitrification -
Chemical vs. Physical (Encapsulation) -
In situ vs. Ex situ - Micro vs.
Macro Types Inorganic Cement, various cement
formulations with additives, phosphate bonded
ceramics, sulfur polymer cement
Organic Based Polyesters, Epoxy, Polyethylene,
polysiloxane, other thermoplastics, and
thermosetting resins, sol gels-thermosetting and
thermoplastics Thermal Sintering,
Vitrification
6
Types of Wastes

• Mixed and Low Level Waste
• Sludges (wastewater treatment)
• Homogeneous solids (paint chips, powder, sand)
• Previously treated wastes (crushed concrete)
• Small debris (ground glass)
• Soils
• Wastewater
• Fly and bottom ash
• Unconcentrated Salt waste
• Limited by large debris, high organic, or
  unique wastes
• Complex-wide
• Oak Ridge Sludge/Solids gt 10,000 m3
• Rocky Flats gt 10,000 m3
• INEEL gt 2,000 m3
• Blowdown and ash from the three mixed waste
  incinerators
• DOE identified sludge/soils gt 60,000 m3

7
Requirements
Vincent Maio Go over waste loading and volume
reduction calculations.

• Have low volume expansion, high densification
• Increase the waste loading significantly above
  that achievable
• with the baseline process
• Are economical, simple, capable of treating a
  wide variety of
• wastes, stakeholder acceptable, and minimize
  secondary wastes
• Meet various disposal site criteria
• Produces a waste form that meets the NRC
  position paper
• requirements of 10 CFR part 61 and RCRA LDR
• UTS via TCLP for RCRA heavy metals including
  UHCs
• ASTM C-39 for compressive strength
• ANSI/ANS 16.1 for radioactive leaching
• Immersion testing, lt than 1/2 free liquids,
  DOT
• oxidizer for salts, wet dry/freeze thaw
  cycling, monolithic,
• radiation stability, biodegradation

8
Technologies Investigated

• Phosphate Bonded Ceramics
• Clemson Sintering Process
• Roc-tec (Starmet) Sintering Process
• Enhanced Concrete
• Polysiloxane
• Sol-gel
• Polyester
• Russian Iron Phosphate Process

9
Vincent Maio Show an extruder picture
Technologies Investigated (other)

• Polyethylene
• Sulfur Polymer Cement
• Epoxy

• Supplemental Equipment System
• Harmonic Compaction
• Applicable to low temperature process
• Kinetic Mixer
• allows organics based S/S methods to accommodate
  organics and higher moisture.
• Extruder

10
Challenging Waste Streams for S/S

• Salt-containing Mixed Wastes
• Most metal salts of NO3, SO4, Cl are soluble
• Can effect curing and long-term durability in
• current baseline stabilization technology
  (portland
• Cement). Affects set rate. Expansion in pores.
  
• Osmotic pressure in organics
• Fly-ash
• Generated from the incineration of combustible
• mixed wastes
• High metal and salt content compared to bottom
• ash. Plus trace organics

11
Baseline-OPC

• Grouting with portland cement
• Excellent S/S process for many waste streams.
  Much experience, low cost, simple equipment , no
  off-gas , no secondary waste, adequate
  compression strength, hydration process reduces
  excess water, chemically binds waste to matrix.
  Various additives can greatly enhance cement as a
  waste form
• Low waste loading are required with the baseline
  to ensure a non-leacheable, high integrity waste
  form
• Only 10 salt loading in Portland cements is
  currently possible
• High volume increase leads to higher handling,
  transporting and disposal costs
• Future generation of additional salt and ash
  wastes are anticipated as existing thermal units
  operate and new ones come on line.

12
Phosphate Bonded Ceramic Waste Forms

• Description
• Completed Testing of the CBPC Technology with
  actual incinerator Fly-ash
• CBPC Technology chemically/physically stabilizes
  waste utilizing the MgOKH2PO45H2O-gtMgKPO4.6H2O
  reaction(acid-base)
• Forms PO4 compounds with low solubility and a
  ceramic barrier. High strength, relative fast
  set
• Technology Development Status
• 10 monoliths of various waste forms have been
  produced-TCLP and compressive strength testing is
  acceptable.
• Mixer for large full-scale testing during has
  been designed and installed at INEEL

13
Ash Stabilization
Process

• MgO H3PO4 2H20 gt MgHPO3 3H20
• MgO KH2PO4 5H20 gt MgKPO4 6H20

Phosphate Powder
WATER
MgO
POWDER MIXTURE
FINAL WASTE FORM
WASTE
WASTE
2h
30 min
14
Phosphate Bonded Ceramics Performance

• Ash with Silicates (Class C-Fly Ash)
• Over 4,000 psi strength at up to 80 waste
  loading
• Passed TCLP at lower UTS levels
• ANSI 16.1 performed for Hg (adequate) 10-17
• Incinerator Fly Ash
• Preliminary results indicate a trend that TCLP
  could fail
• for Cd at higher waste loading
• Unique ash - no silicates, high zinc, high Pb,
  high Cd
• General Results to Date
• Successfully tested (CS, TCLP, ANSI) on soils
  and waste
• water up to 55
• Successfully stabilized Hg in Ash, oxide,
  phosphate and soil
• waste at Hg levels of up to 180 ppm - Add K2S

15
Salt Stabilization

• Salt Stabilization in Using Phosphate Bonded
  Ceramics
• Description
• Use of the CBPC technology to stabilize
  troublesome mixed wastes containing relatively
  high salt (i.e. chlorides, sulfates, nitrates)
  contents
• Technology Development Status
• Surrogate salt waste loading 50, Surrogate
  chloride 2, 6, 10,
• Surrogate nitrate 50
• CBPC stabilized surrogate salt waste passed TCLP,
  ANSI16.1 and compressive strength criteria . Also
  passed oxidation tests
• Chloride ion chemically immobilized, but nitrate
  ion leaches over time.
• Above results verified with INEEL/ICPP surrogate
  salt waste.

16
Phosphate Bonded Ceramics Performance

• Successful surrogate and actual soil testing at
  5 gal scales
• Successful full scale operations on actual
• Evaporator Bottoms
• Completed actual waste operations with glass
• and Pb lined gloves
• Fernald waste (actual) complete
• saltcrete /incinerator Blowdown tests
  unsuccessful.

17
Sintered Ceramic

• Roc-tec Sintering via NMI
• Description
• A ceramic stabilization process for metal oxide
  matrices containing RCRA and /or nuclear
  materials
• A sintering process where the waste is calcined,
  mixed with reagents, pressed, and fired at 1100 C
• Forms a mixture of liquid phase sintered solids
  where redox environments are used to establish
  the proper chemistry
• Technology Development Status
• 60 stabilized surrogate ash samples subjected to
  TCLP
• New formulations were unsuccessfully developed to
  handle high zinc and lead.

18
Sintered Ceramic
RocTec Stabilization
19
Roc-Tec Sintering Performance

• Method performed on Rocky Flats Surrogate Ash
• gt80 waste loading
• Passed TCLP for Pd, Cr, Ba (8000 ppm)
• Method performed on Fernald Silo 3 surrogate
• gt80 waste loading
• Passed TCLP for RCRA metals (UTS level)
• Surrogate incinerator Ash Results
• 60 samples made with a surrogate
• 95-50 wt
• 3 additive types alumina, silicates
• 1 passed TCLP, Pb is the challenge

20
Sintered Ceramic - Clemson Sintering Process

• Description
• A naturally occurring Red Roan Formation (clay)
  material is batched and blended with the ash -
  http//apps.em.doe.gov/ost/pubs/itsrs/itsr2037.pdf
  
• After pressing, formed parts are fired at 10500C
  to 11500C
• Chemically stable crystalline and non-crystalline
  phases result
• Technology Development Status
• 5 gallons of incinerator ash received for phase 1
  testing and testing completed
• Statistically designed experiments were
  performed, including response surface studies
  (vary waste loading, moisture, additive amounts,
  firing temperature, mixing time)
• Phase 2 incinerator ash treatment underway to
  determine large scale operation capabilities as
  well as dioxin/furan destruction capability

21
Ash Stabilization
Sintered Ceramic Stabilization
ASH
RRF
SCALE
RECYCLE
WATER
MIXER
PRESS
EXTRUDER
REMOVE FROM DIE
CUT INTO BARS
DRYER
GRIND
KILN
SCRUBBER
Known waste loading
TESTING
DISPOSAL
PASS
FAIL
-- Sample points for testing archive
22
Clemson Sintering Process Performance

• Past Work
• Fernald silo 3 material
• Successful TCLP for all waste loadings
• (25-50) at UTS levels, Ar, Ba, Cr, Pb, Ni,
  Se
• West End Treatment Facility at ORNL
• Successful TCLP for 50 waste loading
• Incinerator Ash
• 16 batches of ash, an additive, and RRF mixed
• between 10-50 waste loading
• TCLP passed at specific conditions
• General
• Advantages Waste forms can be assembled into a
  high
• density disposal pack, 65 waste loading is
  possible, process
• easily automated
• Disadvantages Parameter must be experimentally
  estimated each
• time, volatile species retention, more equipment
  than grout processes,
• dust control

23
Enhanced Cementitious Stabilization

• Description
• A process whereby salt loadings are increased in
  the basic portland cement grout method by using
  high clay content platicizers and slower setting
  binders such as fly ash and blast furnace slag.
  Advantage Uses known cement technologies and
  processes
• Technology Development Status
• Approach involves sequential statistical designs
  with 3 salt component variables and 4 stabilizing
  additives (blast furnace slag, fly ash, cement,
  platicizers). Design includes standard surrogates
• Experimental work completed. BFS performs the
  best for salt waste
• Data used to generate surface response models
  that will predict the properties (volume
  increase, free water, strength, and TCLP) as a
  function of composition, including salt loading.
  Salt loading with salt surrogate up to 50

24
Polysiloxane Encapsulation of Mixed Waste Salts

• Description
• Low temperature silicon dioxide polymerization
  with a platinum catalyst
• Cure time easily controlled by catalyst addition
• Technology Development Status
• Salt surrogate testing completed
• Preliminary results indicate excellent
  compressive strength and low leachability
• TCLP samples cut not cored

25
Polysiloxane Performance Results

• INEEL Salts
• 87 KNO3 and NaNO3
• Cr6 180 ppm (Tests at 1405 ppm)
• - Results
• 30 and 50 waste loading
• Strength gt 637 psi
• Leachability passed TCLP
• Passed DOT oxidizer test
• Salt Surrogates
• 50 waste loading - Chloride Waste (10)
• Passed TCLP for UTS
• 30 and 50 waste loading - nitrate waste (60)
• Passed TCLP for UTS for 30
• Passed TCLP for 50 (UTS except Cr)

26
Polyester Resin

• Microencapsulation of Salt Waste
• Description
• Stabilizes salt waste using polyester resin with
  50 styrene monomer and an initiator (initiator
  amount affects curing time)
• Vinyl Ester, Isophthalic, orthophthalic, and
  wet-extendable polymer resins tested (1st three
  used on MWFA standard surrogate)
• Technology Development Status
• 18 batches of waste form specimens made at waste
  loadings of 40, 50, and 60 using the salt
  surrogate - Factorial Testing employed, added rad
  surrogates
• Compressive testing completed and are acceptable,
  TCLP specimens prepared,and testing complete,
  immersion and ANSI leach tests initiated and
  complete
• DOT Oxidizer test pending to prove no
  organic-nitrate problem

27
Polyester Performance

• All salt surrogates salt tests passed TCLP (non
  UTS) for 50 waste loading.
• All salt surrogate tests passed compressive
  strength gt3000 psi
• ANSI 16.1 gave adequate leach indices ( gt 7) for
  radionuclide surrogates and anions (C1, NO3, SO4)
  -
• Exotherms kept below 100o C
• 90 day immersion tests were successful

28
Sol Gel Stabilization of Salt Waste

• Description
• Sol-Gel is a chemical synthesis technique by
  which liquids are controllably reacted to produce
  solid matrices
• Objective is to use hydrolysis and condensation
  to create a 3-D network of covalent oxide bonds
  at low temperatures
• Three classes of networks are being investigated
  polymer, (polystyrene, polyurethane),
  polycerams, ceramics
• Technology Development Status
• Preliminary testing indicates that the use of
  higher molecular weight polycerams will combine
  best characteristics for salt stabilization at
  room temperature
• Salt surrogate testing complete.

29
Russian Iron Phosphate

• Developed by Khoplin Institute
• Uses phosphoric acid and iron oxides (by products
  from other industries)
• Process is like phosphate bonded ceramics
• Actual incinerator ash stabilized at various
  waste loading up to 50 (Cd failed)
• TCLP passed for 40 waste loadings with Rocky
  Flats surrogates

30
Adtech Super Cement Process

• Activated blast furnace slag and proprietary
  additives
• Passed TCLP for salt surrogates at 36 wt
• Also success with Fernald Silo three and ORNL
  sludge

Polyethylene

• Thermoplastic polymer from ethylene gas success
  with lead encapsulation
• Demonstrated full scale with Nitrate Salt Waste
  with 30-60 nitrate salt waste.
• Acceptable immersion, thermal cycling,
  biodegradation
• Used for Macro and Micro encapsulation at
  Envirocare

31
SPC

• Sulfur with cyclopentadiene additives to form a
• thermoplastic polymer not a cement. ( Utilizes
  waste sulfur from the petrochemical industry)
• Ash-Debris waste studies
• Commercial vendor uses SPC to encapsulate ash
  from their radioactive incinerator
• Used for mercury waste
• Envirocare to may Deploy for Mercury waste
  stabilization