James G. Hnat, Ph.D, John S. Patten, Ph.D. and Norman W. Jetta, P.E.
Vortec Corporation
3770 Ridge Pike
Collegeville, PA 19426
Telephone (610-489-2255)
Telefax (610-489-3185)
e-mail address: vortec@mail.com

Vortec has successfully completed Phases 1 and 2 of a technology demonstration program for an "Innovative Fossil Fuel Fired Vitrification Technology for Soil Remediation".

The principal objective of the program is to demonstrate the ability of a Vortec Cyclone Melting System (CMS^TM) to remediate DOE contaminated soils, mixed wastes and other waste forms containing RCRA hazardous materials, low levels of radionuclides and TSCA (PCB) materials. The demonstration program will verify the ability of this vitrification process to produce a chemically stable glass final waste form which passes both TCLP and PCT quality control requirements, while meeting all federal and state emission control regulations. The demonstration system is designed to process 36 tons/day of as-received drummed or bulk wastes.

The basic components of the CMS^TM are a counter-rotating vortex (CRV) preheater/oxidizer, a cyclone melter and a glass product reservoir. The balance of the plant consists of feed preparation and blending, product handling, heat recovery, air pollution control, and waste water treatment subsystems. The construction and operational phase of the demonstration program (Phase 3) was initiated in late January 1996 and is scheduled to be completed by the end of 1998. The demonstration testing will be conducted at the DOE Gaseous Diffusion Plant in Paducah, KY.

Phase 3 of the program, leading to the plant construction and demonstration test at Paducah' s Gaseous Diffusion Plant, is approximately 50% complete. The air permit required by the State of Kentucky has been issued. The public comment period associated with issuing a RCRA RD&D permit was closed on October 2, 1996. Site preparation has been initiated, and the formal site dedication ceremony was held October 16, 1996. DOE is in the process of completing an Environmental Assessment.

The Department of Energy's goal to clean-up its nuclear complex by the year 2019 requires the development of innovative technologies to convert soils contaminated by hazardous and/or radioactive wastes to forms which can be safely and readily entombed in accordance with current waste disposal methods. These technologies must be able to accomplish this task with minimum public and occupational health risks, with minimum environmental risks and in a timely and economical manner. Additionally, the technologies must transform the hazardous and/or radioactive waste into a final form which has long-term stability to prevent migration of contaminants, and can thus be disposed in an environmentally safe manner. It is imperative that the technology not present any major obstacles to its own safe decontamination and decommissioning. Finally, the final waste form produced must be very stable since some of the radioactive materials have very long half-lives that greatly exceed the capability of institutional controls to protect the environment.

To accomplish its waste remediation and management missions, the Department of Energy has been evaluating and supporting the development of various technologies. Vitrification and other thermal treatment technologies are being extensively evaluated because of their ability to process a wide variety of organic, heavy metal and radionuclide contaminated wastes. The Vortec Cyclone Melting System (CMS^TM) vitrification processes have the advantage of being very robust with regard to the wastes that can be effectively processed and the spectrum of final glass compositions that can be produced.

Table I summarizes the waste generated annually, stored, and buried at DOE sites that have the potential of being processed using the Vortec CMS^TM technology. These wastes are classified as Lowlevel, Mixed lowlevel and TRU waste (TRU must be capable of being contact handle). These waste streams can be processed by the Vortec CMS^TM at costs lower than the cost of the alternatives being considered by DOE (recently published Report INEL-95/0129, "Integrated Thermal Treatment System Study"). The principal reason for this reduced cost is related to the CMS^TM's ability to handle a variety of LLW and MLLW waste streams simultaneously. At Paducah for instance, the LLW is the principle agent for glass forming constituents and combines the processing of LLW and MLLW into the same operation.

This paper summarizes the progress being made in the implementation of a Demonstration of the CMS^TM at the Paducah Gaseous Diffusion Plant (PGDP). Successful implementation of the CMS^TM technology will significantly increase the rate at which LLW and MLLW waste can be processed. This increased rate will translate into reduced clean-up costs to DOE. The Paducah Gaseous Diffusion Plant (PGDP) was selected for this demonstration because of its expressed interest in the technology, the impact the demonstration will have on the remediation effort at the site, and the site's willingness to participate in the financial support of the project.

This DOE vitrification demonstration project has progressed through the detail design and procurement portions of the project. Phase 1 consisted of pilot scale testing with surrogate wastes and the conceptual design of a process plant for a generic DOE waste stream. The objective of Phase 2 was to develop a definitive process plant design for the treatment of wastes at a specific DOE facility, namely, PGDP. During Phase 2, a site specific conceptual design was developed for the processing of LLW soils and muds containing TSCA organics and RCRA metal contaminants. Phase 3 includes the construction and operation of full scale demonstration at the DOE Paducah Gaseous Diffusion Plant.

During Phase 2, the basic vitrification process design was modified to meet the specific needs of the waste streams available at Paducah. The system design developed for Paducah has significantly enhanced the processing capabilities of the Vortec vitrification process. The overall system design, after several design iterations and component tests at vendor sites, now includes the capability to shred entire drums and drum packs containing mud, concrete, plastics and PCB's and has been modified for processing bulk waste materials. This enhanced processing capability will substantially expand the total DOE waste remediation applications of the technology.

Vitrification trials were conducted during Phase 2 at Vortec's pilot scale vitrification plant located at the University of Pittsburgh Advanced Research Center in Harmarville, PA. The sampling of the effluent and influent streams taken during the tests confirmed that virtually all of the refractory radionuclides were retained in the glass and would not leach to the environment -as confirmed by both Product Consistency Tests (PCT) and Toxicity Characteristic Leaching Procedure (TCLP) testing. The organic contaminant was destroyed during testing with a Destruction and Removal Efficiency (DRE) of at least 99.99%, and semi-volatile RCRA metal surrogates were captured by the Air Pollution Control (APC) system. The data generated during these pilot tests relating to the partitioning of the contaminants throughout the system helped established the Demonstration Plant's design criteria.

Construction at the Paducah, Kentucky site for the 36 ton/day demonstration system was initiated on September 23, 1996. The State of Kentucky has judged that the CMS^TM Vitrification Technology is a glass melting operation, and has issued an Air Permit for the process. Public comment for the RD&D permit was closed on October 2, 1996. The draft RD&D permit is under review.

However, the regulatory issues have not been completely resolved. The State of Kentucky requested that the Air Permit Application be re-submission to reconcile difference between the Air Permit and the RD&D Permit. This was accomplished on October 15, 1997. These differences were cause by the expectation that the Air Permit would cover all phases of the demonstration program while the RD&D permit would only cover the processing the LLW and Mixed LLW materials. The State of Kentucky is requesting that both permits be broken into four separate processing phases. Phase Four, the last phase, will be extended duration testing.

In a related issue, DOE has initiated the preparation of an Environmental Assessment (EA) as required by the NEPA process. This EA was initiated on September 1, 1997, and is expected to be completed by December 31, 1997. In the interim, Vortec cannot assemble the demonstration plant. Equipment that is being shipped to the Paducah site can only be stored and maintained. Permission to complete construction and operation must wait for final approval of the EA that is expected by March 1, 1998.

Following an initial 30 day demonstration test, extended duration testing is planned on additional waste streams available at the Paducah site. During this extended duration, it will be possible to process approximately 80% of the contaminated LLW and MLLW stored Paducah. However, additional permits will be required to continue operation past the initial demonstration testing covered by the RD&D Permit.

The data presented in Table II-a is a qualitative comparison of alternate remediation technologies, for DOE applications. The comparisons presented are for landfill, incineration, stabilization and vitrification alternatives. From the comparisons presented in Table I, vitrification technology is judged to be superior with regard to its ability to produce a vitrified product (final waste form) which has the highest level of chemical stability and its ability to contain inorganic contaminates. In addition, vitrification processes also effectively destroy organic compounds because of the high operating temperatures and residence times at these temperatures.

Table II-b presents a comparison of different classes of vitrification technologies. The data indicates that major advantages of the CMS^TM technology are its low operating/maintenance cost, its high throughput capacity and its operational robustness while being able to produce a product which meets or exceeds all of the applicable product quality control and leaching criteria. The CMS^TM has been demonstrated not to be as sensitive to variations in the waste stream's chemical composition as other vitrification processes.

The principal objective of the FETC/Vortec program is to demonstrate the ability of the Vortec CMS^TM to remediate contaminated mixed low level waste and other waste forms of interest to DOE by operating the CMS^TM in the environment expected at PGDP, and producing glass which passes TCLP and the waste acceptance criteria (WAC) that is applicable at the selected repository. The system has a nominal design capacity of 36 tons per day (TPD) with the capability for expansion to 72 TPD by adding oxygen enrichment.

Additional objectives will be met during the program, such as:

1. Establish an operating arrangement for an extended program for continued operation of the Demonstration Plant by Vortec, thereby supporting DOE's goal of implementing new Environmental Technologies.
2. Establish the glass chemistry requirements to achieve effective vitrification of contaminated waste found at the Paducah site; that is, given a particular waste, determine how its oxide composition must be modified to produce a vitrified product that will immobilize contaminants over the long-term.
3. Establish waste size reduction, moisture content, and the glass fluxing requirements.
4. Establish the cost of construction and operation of the CMS^TM system.
5. Determine the Destruction Removal Efficiency (DRE) of the CMS^TM for organic contaminants likely to be found in waste from DOE sites requiring remediation.
6. Verify the character of the off-gas and the effectiveness of the flue gas clean-up system at meeting the Air Permit requirement.
7. Conduct start-up, shake-down, and feasibility demonstrations using the fully integrated plant. The demonstration system will process approximately 160 barrels/day containing 30% moisture and an average weight of 450 lbs/barrel.

The Department of Energy's goal to clean-up its nuclear complex by the year 2019 requires the development of innovative technologies to convert soils contaminated by hazardous and/or radioactive wastes to forms which can be readily disposed in accordance with current waste disposal methods. Vortec has been working with DOE in developing the CMS^TM to remediate various waste streams of concern to DOE. The Demonstration Plant under construction at PGDP will demonstrate at full scale the cost and operational effectiveness of the CMS^TM process.

The unique features of the CMS^TM technology make it a particularly cost-effective process for the vitrification of soils, sediments, sludge, and other solid wastes containing organic, metallic, and/or radioactive contaminants. Many of the benefits of the CMS^TM technology recognized by the glass and hazardous waste management industry would also apply to DOE's ER&WM needs. Benefits with respect to DOE's needs are:

1. The ability of the CMS^TM to produce a product which provides for long-term immobilization of heavy metals, toxic inorganics, and radionuclides. In numerous pilot scale tests conducted by Vortec, the CMS^TM has demonstrated the ability to effectively process RCRA wastes as well as surrogate contaminated soils. Simulated radionuclides and RCRA metals are effectively retained in the glass product and do not leach when tested using both the PCT and TCLP.
2. The CMS^TM has demonstrated the ability to effectively oxidize and destroy organic contaminants. Tests performed by Vortec in the U-PARC facility with various carbonaceous materials such as cyanides and other organic contaminants found in most industrial waste, and anthracene and 1, 2-dichlorobenzene as surrogates for organic and PCB contaminates, have validated the organic destruction performance of the CMS^TM.
3. The CMS^TM has demonstrated substantial flexibility with respect to the processing of various types of solid wastes and can accommodate substantial variations of feedstock composition. Vortec has completed more than 150 test programs using a variety of materials as feedstocks including U.S. Environmental Protection Agency (EPA) contaminated soils, flyash, baghouse dust, metal plating sludge, aluminum industry waste, steel industry waste and virgin glass making components. Soils with water content of up to 50 weight percent have been processed into glass products.
4. The CMS^TM demonstrated the ability to oxidize and vitrify waste materials introduced as slurries, providing the capability for mixing contaminated or waste oils with various types of hazardous solids, soil wash process sediments, and mill tailings. In addition to contaminated soils, Vortec has demonstrated the ability to vitrify Hanford low level tank waste surrogates with a water content of approximately 70% liquid and 30% solids. The CMS^TM has also demonstrated the ability to effectively vitrify a spectrum of metal plating sludge at 60% water content.
5. The CMS^TM high temperature process components have water-cooled, steel walls providing for a sealed process which can be operated at negative pressure to prevent leakage of contaminated gases to the atmosphere. These water-cooled components can continue to operate in the event that unusual wear or spalling of refractory occurs until such time as the unit can be safely shut down.
6. The 36 TPD CMS^TM demonstration unit is being designed to be transportable and modular, thus enabling wastes at several sites to be processed.
7. In the processing of substantial quantities of contaminated soils, the life cycle cost of the Vortec CMS^TM is lower than other existing vitrification processes. In commercial applications, a 72 TPD CMS^TM process unit typically has total processing costs in the range of $50 - $100 per ton of material processed. Radionuclide and PCB contamination increases the per-ton cost somewhat, depending upon the specific activity of the soil and the nature of the PCB contamination. Vortec estimates that the processing costs of low level waste with mixtures of TSCA or RCRA wastes at Paducah may be in the range of $50 to $200 per barrel for the Paducah drummed wastes.

The primary components of the basic CMS^TM are a counter-rotating vortex (CRV) reactor and a cyclone melter. An artist's rendering of the basic CMS^TM concept is shown in Figure 1. A unique feature of the process is the rapid suspension heating and oxidation of feedstock materials in the CRV reactor prior to the physical and chemical melting processes which occur within the cyclone melter.

The use of the Vortec CRV reactor in conjunction with a cyclone melter distinguishes the Vortec cyclone melting technology from other types of cyclone systems. In the CMS^TM process, granular glass-forming ingredients and other feedstocks are introduced into the top region of the CRV reactor along with fuel and combustion air. As a result of the intense counter-rotating vortex mixing, it is possible to achieve a stable reaction zone in the presence of large quantities of inert particulate matter (solids-to-gas mass ratios on the order of 1:1). Both convection and radiation heat transfer mechanisms contribute to the rapid heating of the feedstock materials within the CRV reactor. Any organic contaminants in the feedstocks are also effectively oxidized.

The melted material formed in the cyclone melter and the reaction products exit the melter through a tangential channel and enter a separator-reservoir (not shown in the figure) where a pool of molten material exits the reservoir through a bottom or side tap. The flue gases exhaust to a heat recovery unit for reaction air preheating. The flue gas exiting the heat recovery unit is treated in an air pollution control assembly prior to being exhausted out the stack. As a result of the high thermal efficiency of the Vortec CMS^TM, the flue gas flow rates are relatively modest. Because the temperature and composition of the vitrified product can be closely controlled, the amount of process fuming (volatile carryover) can also be minimized.

The average gas-solids suspension temperature leaving the CRV reactor is typically on the order of 2000°F to 2700°F, and is a function of the product being vitrified. The process temperatures in the cyclone melter are typically in the range of 2000°F to 3000°F, depending on the melting characteristics of the feedstock being processed. The nitrogen oxide emissions have been found to be substantially lower than those which occur in conventional cyclone reactors. Excess air levels are typically in the range of 5% to 20% depending on the makeup and the nature of the feedstock being processed.

Heat rates demonstrated by the Vortec pilot scale facility typically ranged between 3.0 and 6 million Btu/ton at a glass production rate of 15 TPD. This heat rate is 50% to 80% lower than heat rates for conventional gas-fired glass melting at similar capacity. The energy savings are primarily due to more efficient heating of the glass ingredients in suspension by the products of combustion and lower structural heat losses due to the small physical size of the process components. The CMS^TM can also accommodate the use of a variety of fuels, such as oil and coal-derived fuels, and even organic waste materials. The CMS^TM pilot system has demonstrated NO_x emissions of less than 4 pounds per ton of vitrified product, meeting the California emission standard for glass melters - currently the most stringent in the United States. The CMS^TM demonstration plant is designated as a glass melter by the state of Kentucky the NO_x emissions rate is set, by the air permit, at 100 tons/yr. With natural gas as the primary fuel, the NO_x emissions, calculated as NO₂, have typically been approximately 2 pounds per ton of product. Rapid temperature quenching of the combustion products by the inert solid particles and staged combustion are the primary means of limiting NO_x emissions. Tests conducted for Hanford using a high nitrate concentration tank simulant resulted in no visible plume leaving the pilot plant's stack.

After four years of design evolution under various DOE and EPA programs, the CMS^TM is completely operational at the U-PARC test facility. Vortec's system has demonstrated the production of glass and the vitrification of a variety of feedstocks, including:

• EPA surrogate soils,
• DOE surrogate soils,
• Spent Pot Liners (K-088) wastes,
• Coal fired boiler ash,
• Sewage Sludge ash,
• Auto shredder residue ash,
• Municipal solid waste incinerator ash,
• Metal Plating Sludge,
• Fiberglass waste with organic contaminants,
• Dusts containing heavy metals and organic materials,
• Electronic industry wastes,
• High sodium content tank waste surrogate.

Vortec completed the verification testing and established the plant design requirements in Phase Construction at the site has been initiated, and a site dedication was held on October 16, 1996. Vortec is continuing the development, construction, and operation of the CMS^TM Demonstration Plant during Phase 3. As of October 1, 1997, approximately 80% of the equipment has been designed and ordered with approximately 50% actually stored on site at Paducah.

Vortec believes that the CMS^TM technology is at the stage of development that will result in a mature process that is directly applicable to a large number of DOE Environmental Restoration and Waste Management (ER&WM) needs. Vortec is developing the CMS^TM technology to commercial readiness, with the intention of economically meeting all public, occupational, and environmental health and safety requirements for remediation technology. A 50 TPD CMS^TM system is in the operation at Ormet Aluminum, Inc. and a joint venture is being developed to recycle spent aluminum potliner into value added product.

Release by DOE to initiate assembly activity is expected on March 1, 1998 following the acceptance of the EA. Cold check-out is currently scheduled for September 1998 with the completion of the 30 day demonstration test scheduled for December 1998.

An isometric drawing of the plant arrangement in shown in Figure 2. The system flow diagram is shown in Figure 3. The demonstration plant has been designed to the maximum extent possible as a transportable and modular system. The majority of the individual, skid mounted components have the capability to be transported by truck without special permits.

As is indicated in the system diagram Figure 3, contaminated soil is first transported by DOE in drums from the DOE-PGDP storage area to the vitrification facility. There is always at least a three day supply of the material in the storage area. Soil samples collected prior to the 30 day demonstration test will be used to determine the batch composition.

The process of vitrifying the soil begins in the Feed Preparation Subsystem. It consists of:

1. transportation of drums to the drum shredder for introduction to the feed preparation system,
2. a drying, crushing, metal and plastic separation process to assure that a "clean" material enters the grinding operation,
3. a grinding operation to generate the proper particle size.

To preclude the escape of dust particles when dumping or transporting the soil, all the conveying systems will be designed with an enclosure and operate under negative pressure. In addition, all hoppers and transfer points (dumping points) will also be enclosed and will be under negative pressure. The dust laden air from these devices will pass through a dust collector for particle removal. Solids collected in the dust collector will be transported back into the system. Discharge from the dust collector will pass through a parallel pass HEPA filter system.

The sized and dried waste is transported to a storage silo. Glass making additives are mixed with the soil. Additives (limestone and soda ash) are used to aid in glass forming, obtaining the proper glass properties, or modifying the temperature-viscosity curve. The blending system consists of storage silos and pneumatic feed system for the delivery of the soil and additives to a blend tank. Batch mixing precedes feeding into the Cyclone Melting System.

The CMS^TM components consist of a counter-rotating vortex (CRV) reactor, a Cyclone Melter (CM), a separator/reservoir, and a recuperator heat recovery unit.

The prepared feedstock is introduced into the CRV reactor through injectors located at the top of the reactor. Reaction air, which has been heated by waste heat in the recuperator, is mixed with propane fuel in the inlet arms of the reactor. Auto ignition occurs as the fuel/air mixture enters the high temperature region of the reactor, and the resulting reaction products raise the temperature of the feedstock as it enters. Heated feedstock flows through the CRV to the Cyclone Melter, the feedstock reacts in the liquid layer deposited on the walls of the CM, producing the glass. The radionuclides and heavy metals are chemically bonded into the glass. The glass product and the exhaust gases exit the CM through a tangential exit channel and enter a glass/gas separation assembly (separator/reservoir).

The primary functions of the separator/reservoir are to separate the combustion products from the melted material and to provide an interface with a vitrified product handling system. The hot exhaust products exit through an exhaust port which is the interface for the recuperator. The recuperator utilizes the waste heat to preheat combustion air going to the CMS^TM. Molten glass flows out the separator/reservoir to the Vitrified Product Handling System.

The molten product from the CMS^TM will be water quenched to produce a cullet approximately 1/8" in average size. The cullet will be transported by conveyor to ST-90 boxes. The ST-90 boxes, when full, will be moved to a pick-up area for pick-up and disposal by the DOE-Paducah.

The Air Pollution Control System will consist of a wet electrostatic precipitator (WESP) system for particulate collection preceded by a venturi scrubber. The scrubber will remove large particulate from the flue gas stream as well as serve the function of reducing the flue gas temperature to protect the APCS components. Other equipment in the APCS consists of an air heater, HEPA filters, induced draft fan, and an exhaust stack.

After removal of small particles in the WESP, the temperature of the off-gas is raised in an off-gas heater prior to entering the HEPA filter for removal of fine particles. Redundant HEPA filters are used to facilitate maintenance. The off-gas exits the HEPA filters and flows from the system through the exhaust stack.

The Demonstration Plant also includes a waste water treatment system to remove radionuclides from the process water used in the venturi scrubber and WESP. This system consists of a clarifier, a filter press, sand filter, ion exchange unit, and various pumps and tanks.

Process water from the WESP flows through a wastewater tank, a chemical precipitation tank for chrome removal, and on to a clarifier. The solids from the clarifier, which contain some contaminants not captured in the glass, are dewatered in a filter press and are returned to the Feed Preparation System.

Radionuclides are removed by first filtering the supernate water in a sand bed. The solids are removed periodically from the sand bed by back flushing with the treated water, and the backwash is reintroduced into the clarifier. Radionuclides are removed through ion exchange treatment. The treated effluent is stored in a holding tank for reuse as quench water within the quencher/venturi scrubber.

To demonstrate the effectiveness of the technology, 400 hours of start-up and functional testing are planned, followed by a 30-day period of testing. Extended duration testing to continue processing of additional Paducah waste streams is being considered and the permitting process for these tests is being initiated.

Vortec completed Phases 1 and 2 of a three phase program to design, construct, and demonstrate the effectiveness of the CMS^TM technology at remediating soils contaminated with both heavy metals and radionuclides. At the conclusion of Phase 2, the ability of the CMS^TM to vitrify soils similar to the soil found at the DOE-Paducah was demonstrated. The vitrified product passed the TCLP as well as the PCT for leachability of a glass being used to contain radionuclides.

Phase 3 of the project has been initiated. The final design of a 36 TPD Demonstration Plant to process low-level waste is essentially complete. The Air Permit has been issued by the State of Kentucky and the RD&D permit's period for public comment ended October 2, 1996. The issuing of the permit is expected by the end of October 1997. However, resolution of permitting issues by the State of Kentucky and the DOE have resulted in a delay in initiating the assembly of the plant at the site. Permission to initiate assembly is expected by March 1, 1998.

The project is sponsored by the U.S. Department of Energy's Morgantown Energy Technology Center, under Contract DE-AC21-92MC29120 with Vortec Corporation. The period of performance of the contract is March 1993 to January 1998. The authors wish to acknowledge the contributions of DOE-METC COR Mr. Cliff Carpenter.

The authors wish to acknowledge the contributions of DOE-FETC COR, Mr. Cliff Carpenter. The period of performance for Phase 3 of the contract is February 1995 through January 1998.

1. James G. Hnat, Ph.D, John S. Patten, Ph.D., Norman Jetta, P.E. Innovative Vitrification for Soil Remediation presented at Morgantown Energy Technology Center, Environmental Technology Through Industry Partnership, October 3-5, 1995.
2. DOE/RW-0006, Rev 12, "Integrated Data Base Report - 1995"