Tackling waste management at Globe Valve.
Globe Valve Corp., located in Delphi, Indiana, is a fully integrated manufacturer of plumbing valves, faucets and fittings for the Gerber Plumbing Fixtures Corp. In addition, the company operates an automated brass foundry that uses materials that ultimately require disposal. Some of these are classified as hazardous for the characteristic of toxicity, usually because they contain lead and/ or cadmium. The rapidly rising cost to dispose of these materials was the impetus for a program to evaluate alternative methods of waste management such as waste minimization and treatment.
In 1986, the company began developing an overall waste management program aimed at reducing process waste disposal costs. This article summarizes the work that Globe Valve has done, particularly as it relates to sand reclamation and the treatment of EP-Toxic wastes to render them nonhazardous.
During 1986 alone, the Globe Valve foundry disposed of approximately 3500 tons of EP-Toxic wastes at a hazardous waste landfill. Annual disposal costs rose from $100,000 in 1985 to $500,000 in 1989. if sand reclamation and waste treatment had not been implemented, disposal costs in 1991 would have exceeded $1 million. Three-Phase Approach
A three-phase approach was initiated to control and reduce these disposal costs. The steps in the program included the following: * Classify wastes and separate EP-Toxic
wastes from those that are not classified
as EP-Toxic. * Reduce waste volume through sand
reclamation. * Treat EP-Toxic wastes to render then
Globe Valve contracted with RMT, inc., an environmental consulting firm, to conduct a waste characterization and analysis (WC&A) study, which was carried out in late 1986 and early 1987. Along with waste characterization, the feasibility of sand reclamation of the clay-bonded system sands and core sands was studied. The economic and technical viability of waste treatment was also examined during this time.
One of the first consequences of this work was the determination that approximately 10%, or 360 tons, of the wastes that were being handled as hazardous, in fact were not, and could be disposed at a local sanitary landfill. Approval was received from the Indiana Department of Environmental Management (IDEM) in 1987 for the disposal of nonhazardous core sands in a solid waste landfill.
During the time the waste characterization and treatability studies were going on, Globe began investigating thermal sand reclamation systems for molding sand and other selected wastes. Testing demonstrated that spent sand could be reclaimed to a level that would allow for its reuse in the production of quality cores and molds. Thermal sand reclamation would not only significantly reduce the volume of waste sand requiring disposal, but would cut down the purchase of new sand as well.
Between 1986 and 1989, Globe Valve spent a considerable amount of time researching and evaluating sand reclamation options. Based on these evaluations, in 1989 the company proceeded with the purchase and installation of an integrated thermal sand reclamation and waste treatment system. The system was designed, fabricated and installed by GMD Engineered Systems, Inc. Thermal reclamation
The installed system includes screw conveyors to transport clay-bonded sand from the return sand silo in the foundry to a sand reclamation building. This sand is discharged into a lump reducer, which processes the sand to granular size. Sand is then transferred by bucket elevator to the inlet of the magnetic separator where it is discharged and fed into the surge bin and stored before processing. The stored sand is then fed into the thermal reclaimer, where it enters a preheat chamber. It then flows into a calcining chamber for processing before entering the cooling cell. The sand cooler uses direct cooling from fluidizing air as well as indirect cooling from the coils of an evaporative cooler.
After the sand is cooled, it is transported by a bucket elevator to a storage bin prior to processing by pneumatic post-scrubbing equipment. The pneumatic scrubber provides additional cleaning of the sand before it is transferred to the new sand storage silos. Besides removing residual binder, the key to reusing the reclaimed sand for coremaking or as foundry system sand is to control its grain size. This has been accomplished at Globe Valve. The reclamation system was started up in the spring of 1990 and has been operating since that time.
Materials that cannot be reclaimed, such as process particulate from the thermal reclamation system, refractory waste, and casting cleaning and finishing dusts, are being treated and rendered nonhazardous. To develop a reliable treatment process, Globe Valve has conducted extensive laboratory treatability studies and has carried out field trials and start-up testing as well. Permitting Options
In March 1988, Globe Valve met with IDEM to discuss permitting options that would allow for the treatment of certain wastes in order to render them nonhazardous. Two months later, Globe formally requested IDEM for an interpretation of a USEPA opinion that the foundry could carry out treatments in such a way that would be considered a "totally enclosed treatment system,' which would exempt Globe from the need for a RCRA permit. In July 1988, IDEM confirmed this interpretation. Based on a review of the final treatment system, the agency reconfirmed its opinion in the summer of 1989 that the process was exempt from RCRA permitting. In July 1990, the USEPA agreed with the IDEM that the process was exempt. This was a major achievement. Had an RCRA treatment permit been required, the cost of the permit, its implementation requirements, and time needed for its review would all have been substantial. The entire project would have been negatively impacted. The ruling demonstrated that Globe's reclamation and treatment system complies with the intent of federal and state waste minimization and toxicity reduction goals. TCLP vs. EP-Toxicity
Effective September 25, 1990, the Toxicity Characteristic Leaching Procedure (TCLP) replaced the EP-Toxicity Test as EPA's primary evaluation method for determining a material's toxicity. However, the IDEM indicated that the results of TCLP analysis must be confirmed by the EP-Toxicity Test.' Therefore, during the start-up treatment testing, both procedures were performed. During operational monitoring, the EP-Toxicity Test was routinely performed until the time IDEM adopted the TCLP method. Results of the start-up treatment testing indicated that the two procedures provided similar results for Globe Valve's wastes.
Since then, treatment standards have been finalized by USEPA, which set the concentrations levels that must be achieved prior to disposal. For lead and cadmium, the Best Demonstrated Available Technology (BDAT) limits are the same as those limits set for hazardous waste. These rules were promulgated in final form on June 1, 1990 and EP-Toxic waste materials were banned from land disposal after August 8, 1990. Treatment Methods
During 1988 and 1989, Globe Valve made several process changes, including combining shotblast and metals reclamation wastes into one new baghouse. In addition, testing on the shotblast dust indicated a wide variability in leaching characteristics. Field trials were conducted using a portable muller to mix various dosages of carbonate and phosphate with waste samples. The variability of lead leaching and high-lead materials, which were difficult to treat in both dusts, required higher dosages of both carbonate and phosphate.
The waste treatment equipment and system design was developed through the joint effort of Globe Valve, the environmental consulting firm and equipment manufacturer. Receiving and storage equipment was installed to accept foundry waste and the thermal sand reclaimer baghouse waste. These wastes are accumulated in silos and two other silos receive and store the treatment materials. The waste and the treatment chemicals are fed into a weigh hopper in a sequence controlled by a microprocessor that is integrated with the load cells on the weigh hopper. When batching is completed, the load is dumped into a muller and blended. The treated waste is then discharged into a bucket elevator for transfer to a 20 cubic yard container, and disposed at an approved sanitary landfill.
Start-up testing of the waste treatment system was conducted in the spring of 1990. To document that treatment is effective on each individual waste type, batches of shotblast dust, metals reclamation dust, shotblast sand, sand reclaimer dust and refractory wastes were treated and tested as part of the program. The TCLP and EP-Toxicity Test results from system start-up can be summarized as follows:
Untreated samples from the five different waste streams contained levels of lead in the leachate above the hazardous waste limit. The metals reclamation dust and refractory waste leached levels of cadmium at 1.1 mg/l and 2.0 mg/l, respectively. None of the treated waste samples leached lead or cadmium at levels above the hazardous waste limits, which are also the BDAT limits, in either the TCLP or the EP-Toxicity Tests.
These results demonstrate that the wastes were treated consistently. The EP-Toxicity and TCLP leaching results for lead and cadmium are significantly below the hazardous waste and BDAT limits. In addition to the TCLP and EPToxicity Tests, indiana leach tests were also performed on the treated wastes. in these cases, lead leached at 0.2 mg/l or less. Water leaching tests were also conducted to determine the leaching of lead under nonacidic conditions to better evaluate treatment effectiveness as well as to determine Globe's liabilities for disposal of the treated waste.
During the treatment system start-up work, treatment chemicals included carbonate and phosphate. This was recently changed to an oxide and phosphate to enhance the effectiveness of the treatment. Further testing was conducted to confirm that the treatment was, in fact, effective. The results of all analyzed containers indicated that the treatment worked well.
Testing is also being carried out to provide a high level of assurance that no hazardous wastes are being shipped off-site. Since neither the EP-Toxicity Test or the TCLP are field procedures that can be quickly performed prior to shipping any wastes off-site, other techniques must be used to prevent the improper disposal of a hazardous waste. At Globe Valve this is accomplished by the following procedures: * Conducting a start-up testing program
that documents the variability and the
effectiveness of the waste treatment. * Conducting an operational monitoring
program to confirm that the treatment
continues to be effective. * Conducting operational monitoring
and maintaining records of each
treated batch of waste.
The effectiveness of treatment is being monitored with a sampling and laboratory analysis program. The frequency of EP-Toxicity and TCLP testing will be gradually reduced over time as the process is shown to be consistent. When the IDEM adopts the TCLP, it will replace the EP-Toxicity Test for operational monitoring.
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|Title Annotation:||Special Report: Sand Reclamation|
|Date:||Jul 1, 1991|
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