Copper–zinc (brass) remelt ingot: leaded yellow brass and low-lead grades poured for foundries, from refined metal or sorted scrap

01

Leaded yellow brass C85700 against low-lead silicon brass C87850

The Copper Development Association's alloy data show how differently two cast brasses sold as ingot are built. C85700 is a leaded yellow brass in the copper–zinc family; C87850 is a silicon brass with 2.7–3.4% silicon, almost no lead and far more copper. CDA lists sand castings for valve and general applications and ingot among the specifications for C85700, and an ingot specification as well as continuous, permanent-mould and sand castings for C87850. [1] [2]

CDA lists uses for C87850 including valve bodies for water, faucets, plumbing fittings and water meter cases, and for C85700 builders' hardware among others. [2] [1] Editorial calculation: in °C, C85700 melts between about 913 and 941 °C and C87850 between about 855 and 880 °C, so the two grades also need different pouring practice.

Editorial note: order the ingot by the designation of the casting alloy it must produce (UNS, EN or national), and ask for a heat analysis of every lot covering all limited elements — lead, iron, nickel, aluminium and silicon as well as copper and zinc — not only the copper content.

02

Lead in the ingot and the 0.25% weighted-average rule for drinking-water fittings

In the United States, 40 CFR 143.12 defines lead free for pipes, pipe fittings, plumbing fittings and fixtures as not more than a weighted average of 0.25% lead across their wetted surfaces (0.2% for solder and flux). Each wetted component's lead percentage is multiplied by its share of the total wetted surface area and the results are summed; the lead content of the material used to make the component is what counts, and where a material's lead content is given as a range, the maximum of the range must be used. [3]

Editorial calculation: using the maxima as the rule requires, a C85700 component (1.5% Pb max.) could make up at most 0.25 ÷ 1.5 ≈ 17% of a product's wetted area even if every other wetted part contained no lead, while C87850 (0.09% Pb max.) stays below 0.25% whatever its share. [3] [1] [2] For an ingot buyer this means the grade, not the casting, decides compliance: the specification maximum on the ingot certificate is the number used in the calculation.

Editorial note: low-lead ingot has to be kept apart from leaded returns and scrap in the foundry, since remelting the two together raises the lead of the next heat.

03

Ingot from XRF-sorted scrap: what sorting delivers and where lead slips through

Kölking and co-workers tested sorting of about 4.3 tonnes of metallic fraction from mixed copper-alloy foundry residues on an industrial X-ray fluorescence chute sorter, then remelted each sorted product into ingots. Metal yields were 96.5–98.3%; the 1.7–3.5% melting losses came from dross, volatilisation (mainly of zinc), non-metallic and oxide impurities and unmelted higher-melting metals such as free iron. [4]

The authors compare the Cu–Zn ingot with specifications that limit lead to 0.1% for CuZn37 and 0.2% for CuZn40: its roughly 1.4% lead would need large additions of new metal to the charge, though it is about 40% below the leaded fraction. They attribute the limited separation of leaded and low-leaded brass to the small difference in composition and the short measurement times of chute sorters, and note that aluminium, silicon and manganese impurities can probably be removed by melt refining such as oxygen blowing. [4]

Editorial calculation: to bring an ingot at 1.4% lead down to the 0.2% CuZn40 limit by dilution with lead-free metal alone, sorted scrap could make up no more than 0.2 ÷ 1.4 ≈ 14% of the charge. A handheld analyser on incoming scrap or on finished bars is a screening check; the certificate should rest on a laboratory heat analysis.

04

Zinc boils off in the furnace: holding temperature against zinc loss

Zinc's vapour pressure is far higher than copper's, so a brass melt loses zinc whenever it is held hot. Wilk and co-workers measured it by thermogravimetry on brass scrap containing 10.53 wt% zinc, heated at 20 °C per minute to temperatures from 1,080 to 1,240 °C in helium at atmospheric pressure and held for 30 minutes. [5]

The authors found the rate controlled by mass transfer in the gas phase, with overall mass-transfer coefficients of 4.74 to 8.46 × 10⁻⁵ m/s. [5] These were small samples in a crucible under inert gas, aimed at removing zinc from copper scrap, so the percentages do not transfer directly to an industrial furnace; the direction — more zinc lost the hotter the melt is held — applies to ingot making and remelting alike. Editorial note: ask the ingot maker for the zinc tolerance it holds after its own melting, and allow in the foundry's charge calculation for the zinc the ingot will lose again on remelting.

05

What to state when ordering brass ingot

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Grade: [casting alloy designation — UNS, EN or national]
Lead: [maximum lead; potable-water use and lead-free rule to meet]
Chemistry: [limits for Fe, Ni, Al, Si, Sn, P, Sb; zinc tolerance]
Source: [refined metal, sorted scrap or both; how scrap is sorted]
Form: [ingot or bar mass and dimensions; bundling]
Documents: [heat analysis per lot; laboratory method]

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