CERP: Helping Foundries Identify Routes to Reduced Air Emissions.

The Casting Emission Reduction Program is testing environmental innovations, low-emission products and process improvements to strengthen the US. foundry industry.

While foundry processes, metal compositions, casting quality and technology have been constantly evolving, the public's perception of the industry's environmental performance has not always been as quick to improve. With the advent of greater environmental consciousness and a push for regulation of foundry byproducts, Maximum Achievable Control Technology (MACT) standards and other Clean Air Act requirements, the industry has been confronted with an ultimatum: find a way to reduce emissions or find another business.

As a result of these increased environmental pressures, foundrymen have been impacted by foreign competition. This further focuses the problem: while U.S. foundries may deal with more stringent environmental standards and the resulting unfair global battlefield, they can't let their best weapon--high-quality castings--fall by the wayside in favor of environmental solutions.

Mission Objectives

The Casting Emissions Reduction Program (CERP), located at McClellan Air Force Base, Sacramento, California, is aimed at combating this dilemma. The program's test foundry was conceived more than 4 years ago as a collaborative effort between the U.S. Government and the private sector, including the "Big Three" automakers through the U.S. Council for Automotive Research (USCAR). The CERP foundry is striving to produce high-quality castings using environmentally sound technologies, processes and new materials.

"CERP offers foundries the opportunity to be more competitive," said Ron Cafferty, General Motors Powertrain, Pontiac, Michigan, who has been involved in the program from its start. "Government regulations have been, in many cases, a cost burden to many of the smaller companies. By participating in this program, USCAR helped leverage federal money by supplying technical expertise, equipment and tooling for the good of the foundry industry as a whole. We're not in this for our own good alone. For example, if you look at boats in the water, the higher the water, the less probablility that they will hit an environmental rock. We want to raise the water level for everybody."

Because metalcasting is a critical part of the Dept. of Defense (DOD) industrial base--90% of all manufactured items ordered by the DOD are castings, contain castings or are derived from them--it was in the DOD's best interest to help find cleaner and more efficient casting methods.

"CERP is using federal funds, reducing the burden on individual U.S. foundries to go out and test materials on their own--that kind of testing costs money and disrupts operations," Cafferty said.

Research results will be shared with industry in an effort to level the field, helping foundries comply with Clean Air Act requirements and future MACT standards. In addition, the data generated by this initiative are being used to inform government agencies about compliance feasibility before potentially damaging rulemaking can become reality.

"For all of the foundry industry's purported bad reputation, when you really look at it, this industy has done more as a group to achieve environmental responsibility than any other, and we ought to be proud of that," said CERP Program Director Bill Walden. "Our purpose with CERP is to provide neutral test and data-delivery capability so that the supply side of the industry will be able to have consistent accurate numbers to measure their products. In the long term, foundry people will be able to reduce their air emissions with products that are environmentally friendly while producing good parts that are competetively priced."

Other partners in CERP include APS, the U.S. EPA, the California Air Resources Board and the Casting Industry Suppliers Assn. While CERP originally was slated for completion in 2000, the research has been funded for another year. The DOD has provided $40 million for CERP metalcasting research thus far, and automotive companies have expressed interest in continuing the program beyond 2000 with money from governmental research grants and the private sector.

Base of Operations 

The 60,000-sq-ft CERP foundry can produce gray iron castings ranging in size from small aircraft components to engine blocks. The facility was built within an empty warehouse at the air force base specifically for conducting process, material and data evaluations.

While the focus of the foundry is air monitoring, the facility also can perform research into process and product environmental reduction, metallurgy, energy reduction, process controls, product quality and process improvement. Operations consist of a pre-production foundry that uses hooded single molds and a production foundry with an impact molding line and a complete core operation, including an enclosed exhaust room to verify emissions during core storage.

All of the equipment installed at the production foundry (Fig. 1) has been enhanced with specialized ventilation and monitoring systems that capture air emissions. Equipment specifications are:

* automated horizontally parted molding line (24x36x14 in. flask size) rated at 50 molds/hr;

* muller and multi-cooler rated at 50 tons of molding sand/hr;

* two induction melting furnaces capable of supplying 6 tons/hr of 2700F molten gray iron;

* stopper rod pouring furnace with camera-controlled pouring system;

* cold or hotbox core-blower with tooling capacity (44x44 in.);

* coldbox blower with a tooling capacity of 22x22 in.;

* blast monorail shotblast machine for sand removal and casting cleaning;

* robotic casting manipulator for moving hot castings from shakeout to shotblast.

The computer data system can relate process data information directly to actual air emissions.

Emissions Fact-Finding

A team of chemists and engineers works with universities, private and public agencies, consulting firms and contractors to develop new air monitoring processes and practices to help validate real time air emissions monitoring for hazardous air pollutants (HAPs) and particulate matter (PM). Since the facility opened, more than 2100 air samples have been collected and analyzed using a chemical ionization mass spectrometer.

To be able to begin operations at CERP foundry, researchers had specific testing requirements and worked to develop unique testing abilities. The facility's environmental capabilities include:

* proven methods for collecting and testing hazardous air pollutants;

* real-time measurement equipment;

* ultra-low concentration measurement levels;

* small particulate measurement (sub-micron).

Strategic Initiatives

Product testing and evaluation began in September 1998, and some of the early projects now are producing reportable results. CERP has been conducting tests on vendor-supplied low-emission binder replacement products in an effort to reduce emissions by 50%. Low-emission products will reduce the potential health risk effects of foundry air emissions and could reduce the technology-based requirements of pending MACT regulations.

Testing at CERP is primarily a two-stage process. The first stage involves running products through a "screening" process in the pre-production foundry. Tests are run on one complete cycle from molding to pouring to shakeout. "This gives a gross cut to determine what the product is like--measuring to see that it is accurate against its own baseline," Walden said. "We work with vendors to ascertain the product's emissions, as well as any negatives, and this preproduction testing gives vendors a better idea of how their binders will perform. When we're comfortable that a binder will achieve a 50% reduction, then we send it to the production plant."

Testing at the production facility is meant to give results closer to what a real foundry will achieve in full production. "This helps to reduce the risk between the laboratory and the end-user of the product," Walden said.

For the binder/seacoal replacement study, three baseline runs were completed in the pre-production foundry using:

* phenolic urethane amine coldbox core product (1.75% resin) with a neutral mold (no seacoal);

* a seacoal (5%) green sand mold with neutral core (sodium silicate);

* a standard green sand mold mix with a coldbox core.

Tests employing the low-emission products were performed using an AFS step core (8-on) pattern. More than 300 single mold pours were completed, with 9 single molds/typical test. Emissions and process data were collected from pouring, cooling and shakeout as well as from the sand system and compared to the baseline. In all, 14 vendor-supplied low-emission replacement products have been tested, and more are in line for testing.

The seacoal replacement products realized a maximum 70% reduction in emissions (Fig. 2) with some quality tradeoffs, while the low-emission binder products resulted in a maximum 30% reduction.

The results also point to the conclusion that a greater casting surface area produces greater emissions (by a factor of 6-7). Foundries producing more complex castings should be in tune to the fact that they may be producing greater emissions.

Two baseline runs also have been completed in the production foundry. Each run consisted of nine 1-hr emission tests on 5001-4 block coldbox core packages. Results of these tests are being analyzed and will be used for comparisons with currently scheduled vendor products. These vendor products have been scheduled as a result of the successful testing in pre-production.

Future testing will include a nobake molding line used to test emissions from gray iron and aluminum casting processes.

The CERP baseline emissions data has been compiled into an e-Mission Database Analysis System, and staff are currently incorporating the results of a Mexican foundry study (see sidebar "CERP Surveys Mexican Foundries for Emissions Data") for use in the system. In addition, through efforts by Univ. of Alabama-Birmingham (UAB), a survey of industry stack tests was used to generate emission factors for a National Center for Manufacturing Science database. This information is available on the CERP website for use in emissions calculations.

New Recruits

CERP has been accepting proposals from suppliers, universities and foundries for testing low air emissions green sand additives, core binders and processes since it opened. The facility has been involved in:

* green sand emissions relative to surface area, loss on ignition (LOI), sand-to-metal ratio, clay/moisture levels;

* nobake sand emissions in which a UAB computer model was developed and will be tested against measured emissions;

* Thin Wall Iron Group project in which foundry testing of various shapes, including an 1-4 block, in gray and ductile iron will be conducted;

* real time air emission instrument development;

* research collaborations with Univ, of California-Davis, UAB, and Univ. of California-Riverside.

Requirements to have product, process or equipment tested at CERP include:

* technical information or testing supporting that the system reduces total hydrocarbon emissions by at least 50%;

* material safety data sheets on products supporting lower hazardous components;

* information to support the fact that this is a commercially viable product or process, such as quality characteristics, cycle times and cost availability;

* supply of materials or equipment to the foundry at no cost during testing.

CERP Surveys Mexican Foundaries for Emissions Data

While the emission data being developed from CERP production foundry tests are valuable, it can be argued that those results really are valid only for the CERP operation--not in typical facilities with production, as well as environmental, concerns. In order to compile a practical emission database, it was necessary to perform field work.

To gain information from "real world" foundries and provide production data that matched actual emissions output, the McClellan Air Force Base assembled a team to conduct source testing pollutant emission factors for various foundry processes. These emission factors will be used to establish and evaluate options for air quality regulations or standards; develop source-specific emission factors for use in emission inventories, dispersion modeling, and other air quality activities; and provide a baseline for emissions against which new processes and materials will be benchmarked. This information is important to the development of MACT standards for HAPS emissions from iron foundries.

Members of the Emissions Measurement Committee worked with the McClellan Air Force Base source test team to develop a foundry emission measurement program that would work in operating foundries and to select sampling methods for use in the stack measurements at the iron foundries. For this study, emissions data were collected from the General Motors foundry in Toluca, Mexico (General Motors de Mexico, S.A. de C.V. Complejo De Manufactura Toluca and the Ford foundry in Cuautitlan, Mexico (Mexico Ford Motor Co. Cuautitlan Casting Plant).

The foundries produce iron cylinder blocks, bearing caps, cylinder heads, manifolds, waterpumps, crankshafts, clutch housings, and fly wheels. The production rate is 75-100 molds/hr.

Testing at the foundries focused mainly on emissions from casting blocks, and processes tested included melting, coremaking, pouring, cooling, and shakeout. The testing program included simultaneous measurement of the emissions of:

* volatile and semi-volatile organic compounds as well as aldehydes, ketones and isocyanates;

* particulate matter (total particles, particles [less than or equal to] micrometers, and particles [less than or equal to]2.5 micrometers) and condensable particulate matter;

* metals;

* collection of process data concurrently with the sampling times for the processes tested;

* collection of stack flow, moisture, pressure and temperature information from all test emission points.

The contribution from shakeout dominated most of the organic HAP emissions. The HAPs with large emission factors included benzene, phenol, toluene, and xylenes.

The polycyclic organic matter (POM) emitted at the highest rates were naphthalene and the monomethylated naphthalenes (1-methylnaphthalene and 2-methylnaphthalene). These three POMs accounted for 80% of the total POM emissions from pouring, cooling and shakeout. Many of the recognized carcinogenic POMs were not detected, including benzo[a]pyrene (BaP), benz[a]anthracene, and chrysene. Thus, the use of BaP as a surrogate for POM would be incorrect for pouring, cooling and shakeout emissions.

Major emissions of metal HAPs from melting included manganese (Mn), lead, nickel, copper, and chromium. Emissions were highest in Mn.

Emissions information on particulate matter sized less than or equal to 10 [micro] (PM10) and less than or equal to 2.5 [micro] (PM2.5) also was recorded. By this definition, PM10 includes PM2.5.

PM10 is about 50% of the total PM emissions from cooling, but less than 30% of the total PM from pouring, cooling and shakeout combined. Not all of the emissions from shakeout were captured, yet shakeout is one of the process steps in which particulate matter emissions are high.

Results of the study have been submitted to EPA and Foundry Assn. of Michigan (FAM) to help provide emissions data more comprehensive than what is available, specifically regarding organics. FAM also has included the information within its emissions database to be used by foundrymen in emission factor calculation.