Air quality, beneficial reuse issues dominate 10th EHS conference.

Conference speakers highlighted progress on controlling foundry odors and successful reuse projects for a lessened environmental impact.

Today's foundries are feeling increasing pressure to meet environmental standards - the hardest part being that many government-imposed standards are still "up in the air." The thrust of the 10th AFS Environmental, Health and Safety Conference, held August 17-19 in Indianapolis, focused on that anxiety over the tightening air standards, but the conference's 31 speakers covered topics ranging from beneficial reuse to managing crisis situations to personal protective equipment. The event's 230 attendees took advantage of the gathering to discuss environmental concerns, view displays set up by the conference's 23 exhibitors and tour Indianapolis Casting/Navistar International, Indianapolis.

ODOR CONTROL

In "Odor Control in a Steel Foundry - A Case Study," Daniel E. Cutugno, ESCO Corp., discussed the reduction of unpleasant smells associated with sand molds and a resin binder system ESCO uses at its two steel plants in Portland, Oregon. The foundries also cast in horizontally- and vertically-parted green sand molds.

Because ESCO's foundries are located along the perimeter of an "industrial sanctuary" and relatively close to residential areas, complaints from residents prompted an evaluation and control program aimed at reducing odor impacts in the neighborhood, Cutugno said. During an initial study at both foundries to identify specific processes and equipment responsible for odorous emissions, air samples were collected in inflatable "tedlar" bags and qualitatively evaluated for odor characteristics.

"Odor is unique because there is no universally accepted standard," Cutugno said, stressing that sensitivity and personal perception play important roles in determining offensiveness.

The odor characteristics studied include concentration, intensity, character and hedonic tone (the degree of pleasantness or unpleasantness). Concentration was measured in terms of the number of dilutions with odor-free air that were needed to reduce the odor to a threshold, or dilutions-to-threshold. Odor in tensity was measured using a 0-8 n-butanol reference scale. Measurements were based on the findings of a trained odor panel that sampled air from the shakeout system in "sniff cups."

The study determined the "culprits" of offensive odor through chemical analysis and aided in predicting odor impact on surrounding neighborhoods, according to Cutugno. Odors were detected from the original product constituents, such as sand coating operations and coremaking, as well as in thermal decomposition products, such as during pouring, cooling, shakeout and sand reclamation. In addition, the foundries' painting operations generated odors from both the paint itself and during the thermal cleaning of paint racks. Some processes had high odor concentrations, but low flow characteristics, such as oil sand core ovens and paint rack-cleaning ovens. Others had high odor concentrations with high flow characteristics, including pouring, cooling and shakeout.

Constituents that were determined to cause odors include higher-weight molecular compounds, sulfur and nitrogen compounds and other aromatic compounds, such as aniline, benzene and phenol.

Pilot System

Based on the results of this initial study, the foundries' pouring, cooling and shakeout operations were determined to have the greatest potential odor impact. ESCO selected an area where sand molds are dumped onto a vibratory conveyor (part of the shakeout system) to implement a pilot odor control system aimed at testing various odor neutralizers. The pilot system involved spraying the "mold dump" area with a commercial odor neutralizing liquid diluted in water directly above the indoor conveyors, upstream of the dust collector, according to Cutugno. The study tried to measure the potential effects of moisture on casting quality, the effects of moisture on the baghouse environment and the effects of a harsh indoor environment on equipment. The effect of various dosages of the neutralizer on the odor characteristics of the exhaust stream were analyzed, but initial information was inconclusive. "Foundry odors are tough to deal with," Cutugno said, stressing that because odors are intermittent in nature, come from multiple sources, change with process variables and are highly subjective, solutions can be hard to find.

Treatability Studies

The next phase of the study involved bench-scale "treatability" studies on the mold dump exhaust gases, using six commercial neutralizing liquids. Air samples bubbled through dilute solutions of various neutralizers, with water used as a control. The odor characteristics of the air samples before and after treatment were evaluated, and odor concentration and hedonic tone were evaluated in combination to determine product effectiveness. Results suggested a maximum odor reduction of approximately 60%, with tap water working effectively in helping to neutralize odor.

Cutugno said that none of the products was able to completely eliminate odors. "There was a change in odor character, but not in concentration," he said. "The odor was still there, just different." In addition, sometimes the combination of the two odors was even more disagreeable.

Full-Scale System

Based on the operational experiences from the pilot system and the results of the treatability studies, a full-scale spray system [ILLUSTRATION FOR FIGURE 1 OMITTED] was installed outdoors, on the downstream side of the programmable logic controller (PLC). Since installing the system, ESCO has had trouble quantifying odor reduction because even though complaints to the state agency have decreased, some neighbors claim odors are worse. Also, even though the foundries are controlling one odor source, there are several others that are unchecked. However, ESCO is encouraged by the studies, and the firm plans to try different products as well as tap water in further testing, Cutugno said.

EUROPEAN REUSE

Beneficial reuse is a hot topic for foundries worldwide, and in her presentation, "Beneficial Reuse - A European Perspective," Martha McBarron, The Castings Development Centre, discussed successful projects in Germany and Finland, as well as progress throughout Europe.

Table 1. Tons of Foundry By-products Reused in the U.K.

                                     Actual             Projected
Application                      1996     1997       1998      1999

Asphalt                                   9000      52,000   200,000
Building Products                5000   42,000      92,000   117,000
Cement                                  12,000      60,000    85,000
Other Road
Construction Materials                    3000        8000    25,000
Soil                                    10,000      20,000    25,000
Other                                     8000      21,000    31,000

Total Tonnages Reused            5000   85,000     253,000   483,000

Currently, there are about 3000 foundries in the European Union (EU), employing about 250,000 people and producing about 12 million tons of finished castings/year. More than 80% of castings produced in the EU come from four countries: Germany (35%), France (18%), Italy (18%) and the U.K (11%), according to McBarron.

European foundries have been under considerable pressure in recent years to meet increasingly stringent environmental requirements and to compete with the rising tide of cheap castings coming from Third World countries, she said. In addition, the cost of waste disposal in the EU has risen sharply over the last decade due to new requirements for management of disposal sites, a shortage in available landfill capacity and new taxes on waste sent to landfills. Spurred by these economic and environmental concerns, some progressive foundries in Europe have taken action to re duce waste costs.

Outstanding Successes

ClaasGuss GmbH, one of the largest foundries in Germany, producing 22,500 tons of gray and ductile iron castings/year, began to investigate the use of surplus sand and slag in the early 1990s, according to McBarron. The foundry worked with the Ministry of Environmental Affairs and the Ministry of Traffic in Nordrhein Westfalen, the Institut fur Giebereitechnic, the Faculty of Road Construction at the Univ. of Bochum, and specialists in the field of groundwater to pioneer use of sands and slag in underground engineering projects. The firm continues to seek new uses for by-products, and only a small portion of wastes still ends up in landfills today, McBarron said.

In 1994, Karhula Foundry, a Finland-based holding of Ahlstrom Pumps Corp., generated more than 5 tons of waste for every ton of castings it made. The steel casting company made waste management a priority and involved the entire workforce in a program of waste reduction and environmental improvement.

By evaluating its waste stream, the 200-employee foundry was able to identify other disposal routes, McBarron said. This included sending packing materials for use as firewood or pallets for recycling; waste paper and cardboard for board mill; empty drums to a barrel washing plant; excess sand to cement or asphalt plants and other foundries; metal-containing dusts to a metal recovery plant; and problem wastes to a treatment plant. In two years, the foundry reduced wastes sent to landfill by 65%, according to McBarron. The facility is looking at further reductions, and it has achieved ISO 14001 certification.

Reuse Today

Today, foundries in most European countries are reusing sand in asphalt, cement and concrete products, said McBarron, but in some cases reuse has been restricted to research projects or only a few foundries. Belgium, Holland and Germany are all reporting a high success rate, and opportunities are growing in the U.K.

Dusts and sludges, which are among the most difficult wastes to handle, are often more costly to dispose of, and because of stricter emissions standards, the volume of these by-products is on the rise, McBarron said. In Europe, she said, foundries are looking to injection of dusts/powders into cupolas and electric arc furnaces; briquetting, pressing or agglomeration of dusts and sludges to enable remelting or reuse; and specialist recovery of valuable metals by third parties. Still, the "hassle factor" plays a part in limiting widespread reuse initiatives.

Foundry Network

This year, a Thematic Network on Foundry Waste made up of 16 partners from 10 countries was initiated with financial assistance from the European Commission, McBarron said. To qualify for membership, partners had to demonstrate previous expertise in foundry waste management and have a current R&D project up and running.

The overall objective of the network, through coordination, cooperative research, and identification of synergies, gaps and common projects, were to:

* develop methods to reduce waste generation;

* improve the extent to which materials can be recycled within a foundry:

* develop methods to reduce the toxicity of waste, enabling it to be used as a raw material in other industries.

The Castings Development Centre initiated a two-year project in July 1997 to promote beneficial reuse of foundry byproducts in the U.K. One of the project objectives was to reduce the amount of waste material discarded in landfills by 20-40% (up to 600,000 tons/year) by the end of the project, resulting in cost savings to the industry of more than $13 million (Table 1), McBarron said.

Working Toward the Future

Integrated Pollutuion Prevention and Control (IPPC) is a directive expected to affect management of environmental impacts from a range of industrial and other installations, said McBarron. Previous environmental legislation from Europe consisted of a series of separate directives covering emissions to air, water pollution and waste management, but IPPC is based on a holistic approach taking into account a much larger range of environmental impacts. Affected installations will be required to implement the "best environmental options" for prevention and control of pollution, including good management of inputs and processes by 2007, she said.

IPPC will cover ferrous foundries producing more than 20 tons of finished castings/day and nonferrous foundries with a melting capacity in excess of 20 tons/day, according to McBarron, who stressed that the directive could affect as many as 700 European foundries.

Next Month: modern casting will cover new air regulations - bringing your foundry into compliance.