Introduction

This page has been assembled to assist die casters in the preparation of their annual Toxics Release Inventory (TRI) Form R reports. Each year many die casters are required to examine their facility operations and report chemical release information to the USEPA and to state and local agencies. Die casters handle a number of chemicals that are subject to the regulatory requirements of Section 313 of the Emergency Planning and Community Right to Know Act (EPCRA), which includes reporting requirements for the Toxic Chemical Release Inventory (TRI) program.

Toxic release reporting can be a very complex undertaking, depending on the types of manufacturing processes a facility is using. The rules for TRI reporting are voluminous and can be confusing. Also, within the regulatory framework and the guidance and instructions offered by the USEPA, there is a great deal of room for interpretation of a particular rule, definition or statement. Many trade associations and companies have formed their own TRI task forces or work groups just to interpret the regulations as they relate to their individual applications and needs. The USEPA offers assistance in interpreting the rules and applying them, but some of this guidance can be misleading or erroneous. Nevertheless, the USEPA can apply penalties for over-reporting as well as under-reporting TRI emissions data.

The TRI report may be the most important environmental report that die casters prepare each year. The information is these reports is reviewed and used by environmental activists, foreign and domestic competitors and by regulatory agencies. It is important that each die caster prepare the best and most accurate TRI submittal that can be achieved. The purpose of these web page resources is to assist die casters in this purpose.

Eventually, NADCA may present web resources to cover the entire gamut of TRI reporting requirements for die casters. Guidance may be offered in the future for specific die casting operations including dross handling, chip recycling, surface conversion operations, painting, machining operations, waste disposal practices, emissions to air, water, ground water and land, and transfers to off-site locations. 

General Guidance for Reporting Air Emissions from Die Casting Melt Furnaces

This section is designed to assist the die caster in estimating air emissions for this section 5.2 of EPA Form R.

Most aluminum, zinc and magnesium die casters use reverberatory, tilting barrel, electromagnetic induction, crucible and non-crucible furnace designs for melting metal. Air emissions from these various furnace designs varies significantly. 

In addition to furnace design, the metal throughput, residence time, and operating practices also affect the quality of air emissions from melt furnaces. Most die casters operate their furnaces with no air pollution control (APC) equipment; stacks are vented directly to the atmosphere some 15-20 feet above the melt room roofline. Some die casters, however, are required to capture melt furnace emissions and treat them using a bag house, electrostatic precipitator, or other APC equipment. Furnaces that are used to remelt “dirty” or “oily” chips or scrap may have afterburners and more sophisticated APC equipment, and/or may pretreat the metal using a chip dryer or other equipment.

The most recent version of TRI-Me

The materials for Reporting Year 2001 (filed in July 2002) TRI Form Rs are due to EPA each year by July 1

Questions and Answers

Engineering Calculations

Engineering calculations account for nearly two-thirds of the calculations used for TRI report emissions calculations. These calculations can be as simple as assuming that a certain percentage of the melt is lost to the stack, to as complicated as involving thermodynamic equilibrium computations.

The engineering calculations method can include emissions estimates using several different techniques. In this way, the estimator can develop quality control checks on the work being performed. For example, a percentage of melt loss calculation can be compared to the results of a mass balance and to calculations that used emission factors derived from outside sources. The emissions estimator can then produce emissions estimates using the three different techniques and compare the results. The engineer or scientist then makes a judgment as to whether the primary method of estimation is within reasonable limits and has an acceptable degree of accuracy.

Mass Balance

A mass balance can be a good approach for large die casters and was found by the USEPA to be used by 7.9% of SIC 33 facilities. Basically, the mass balance consists of taking the entire amount of metal that is purchased and melted in a year and subtracting the mass of dross and metal recycled off-site that year. The resulting deficit is attributed to air emission melt losses. Most die casting purchasing departments maintain the records needed to prepare a mass balance.

A large plant can develop some good emissions estimates if it has very tight control over the amount of metals purchased and melted and the amount of dross and recyclable metals that leave the plant. The larger volumes used by large die casters should translate to lower error and more accurate emissions estimates. Medium to small die casters can also used the mass balance technique if they have very tight inventory control for the mass of materials being balanced. A mass balance can also serve as a check on other air emissions estimate techniques.

Monitoring Data

Monitoring data is reportedly used by 26.3% of SIC 33 industries and consists of the use of actual stack sampling data under very tightly controlled conditions. The pollutant emissions are actually measured and the rate of emission is related to the rate of metal melting.

Facilities may decide to undertake the development of monitoring data of air emissions for the following reasons:

• More accurate estimate of specific chemical compounds, elements or criteria pollutants;
• To verify past emissions estimates;
• To develop site-specific emissions factors; or
• Provide supporting data for other emissions estimating techniques.

The collection of monitoring data must be approached very carefully and with a great deal of planning and coordination with manufacturing personnel. Air emissions data is notoriously highly variable (as much as an order of magnitude or more for the same test run) and the testing procedures and sample collection techniques are subject to interference from a large number of factors, not all of which are evident when the testing is in the planning stages or even when the testing is being performed. Triplicate sample runs are the standard when collecting air emissions data. A professional environmental engineering firm or laboratory, experienced in air emissions studies, should be retained to conduct the sampling and data analysis. The data, once collected, may have to be reported to the local air pollution control authority, so full consideration needs to be given to the use and distribution of the data before a decision is made to proceed with the collection of monitoring data.

Once the specific pollutant emissions rate (E_i in kg or lbs/hr) is determined, the annual pollutant loading can be calculated by multiplying the pollutant emission rate by the number of hours the manufacturing process was in operation.

Emission Factors

The TRI Data Quality Report indicates that emission factors (EF) account for only about 5% of the calculations used in SIC 33 to calculate air emissions for TRI reports. The reason for this is simple: published emission factors that are useful to the SIC 33 industries as a whole are practically non-existent.

Emission factors are most accurately derived from monitoring data but they can be derived from engineering calculations, mass balances and/or from emissions studies that have been conducted on similar melting operations.

Example Calculations for Melt Furnace Stack Emissions

The following is an example TRI emissions calculation for melt furnace stack emission metals released from a large die caster melting approximately 60,000,000 lbs of aluminum alloy annually. This example facility uses large MPH reverberatory melt furnaces and medium sized Lindbergh tilting barrel melt furnaces to melt aluminum alloy A 380.1.

This example is for an aluminum die casting facility. The same calculations can be directly translated for magnesium and zinc alloy die casting.

Range of Emission Factors:

Overall emission rates for an individual facility is entirely site specific and is dependent on type of melt furnaces in use, residence time, metal throughput, alloys being used, flux method, runaround quality and quantity, use of oily chips or scrap, and other factors.

The die caster in our example has an aggregate emissions rate of 3.6 lbs aluminum/ton of metal melted. This equates to a melt loss for air emissions of 0.18% of annual metal melt. Air emissions melt loss percentages ranging from 0.04 to 0.4 % are possible.

Example Calculation:

A die caster melts and pours 60,000,000 lbs of aluminum alloyA380.1 annually. An aggregate emission factor from all the melt furnaces of 3.6 lb aluminum/ton of metal melted has been established.