Low-lead copper-base alloys pass emission tests.

The use of low-lead alloys as a substitute for leaded alloys is not solely contingent upon the new alloys' machinability and castability. The principle reason substitute alloys are being sought is environmental.

In looking at any new alloy's feasibility, an important first step is determining whether or not it will be more environmentally friendly than current leaded systems.

To examine this matter on two experimental bismuth/selenium (Bi/Se) alloys - 2%Bi/1%Se and 1%Bi/0.5%Se - a straightforward and conventional approach was used to collect the data to determine the level of metal fume exposure.

Fumes were tested for bismuth, lead, selenium, zinc, copper and nickel for the experimental alloys. A total fume exposure was determined and a time weighted average was calculated. Methods for testing are listed below, and Table 1 summarizes the results from the tests.

[TABULAR DATA FOR TABLE 1 OMITTED]

Methods

Air sampling pumps were placed on the melter, pourer and in the melting/pouring area during the experimental runs of the alloys. Fumes were collected at the Cast Metals Institute (CMI) Laboratory during the production of the experimental alloy ingots and at three foundries who conducted the melting trials.

The tests were overseen by the AFS Environmental Affairs Dept. with chemical analysis performed by the AFS/Lester B. Knight Environmental Laboratory. Standard methods and procedures were used in the collection and analysis of the samples. The analytical techniques used were NIOSH method 7300 and 7082 with ICP-AES (inductively couple plasma). The limit of detection was -0.15 ug.

All melting for these trials was conducted in various types of induction furnaces. CMI used a 500 lb coreless furnace that was covered during melting. Foundry #1 melted in an uncovered pusher furnace with 200 lb clay graphite crucible. No charcoal cover was used during melting.

Foundry #2 melted in a 300 lb coreless furnace with a partial metal cover and no charcoal on the melt.

Foundry #3 melted in a covered lift swing furnace with a 300 lb clay graphite crucible. All of the furnaces had a dust collection system with a removal vent over the furnace. The removal rate was not measured.

During pouring of the alloys, most of the ladles had some type of cover over the metal. CMI used a kaowool blanket to cover the metal, which reduced heat loss and metal fumes. No collection system was used on the ladle or near the molds being poured. Foundry #1 did not use a cover over the ladle and did not have a ventilation system near the molds during pouring. Foundry #2 had a fume removal vent attached to the ladle throughout the pouring of all molds. A metal cover was used on the ladle.

Foundry #3 used a collection system on the ladle and each individual mold had a collection hood. A silicon carbide cover was used to cover 90% of the surface of the metal in the ladle during pouring.

Results

Air exposure results from all the facilities and areas tested show that employee exposure to metal fumes, for all metals tested, were well below current OSHA permissible exposure levels. Additionally, all lead exposures were well below the regulated action level.