What Is A Scrap Gold Refining Lot
All the metal delivered to us as a refining lot are first inspected for magnetic metals like iron, low grade stainless steel, nickel, and cobalt. Once the magnetics are removed and other non-precious metals are removed, all of the gold, the 10k, 14k, 18k for example are combined and melted together into one hom*ogeneous mass and poured into an ingot mold forning a bar.
When molten, a small pin sample was drawn and saved for future analysis to determine the final purity of the poured ingot. The pin sample is then analyzed by x-ray fluorescence spectromerty and/or fire assay to determine purity. That is, how much pure gold, 24k gold, is contained in the ingot. This amount of pure gold (we also pay for any silver that is contained in the bar) can now be sold on the market or placed in your pool account and sold later. There is no need to wait for the final refining process phase
The impure bar, or ingot, then proceeds to the primary refinery where the pure metals are separated and reclaimed. All of the gold, copper, silver. Most of the other trace elemnts have no value and are discarded. This final refining phase can take up to 18 months to complete.
The ingot, or bar, is still impure, containing all the elements that were in the melted jewelry. Typically copper, gold, a little silver, and other trace elements. Any small no-value stones and little steel springs that were inside c-clasps and lobster claw fasteners were removed using borax and boric acid flux. The flux floats the impurities to the top when poured and then easily removed and discarded once the ingot cools.
Stone Removal Refining Lots reclaims all the stones, diamonds, rubies, sapphires by dissolving the gold in a beaker rather than melting it. The gold is dissolved in Aqua-Regia acid and the stones simple sink to the bottom of the beaker. The stones are then reclaimed, thoroughly rinsed and sorted. These stones can now be sold. KMG Gold Recycling® buys diamonds from stone removal lots.
Diamonds reclaimed from stone removal lots can also be "frosted" to determine whether or not they are in fact diamonds. Frosting service subjects the stones to an acid bath which will mar the finish, or "frost" the stones that are not diamond. Diamond frosting will help separate zircon and glass from diamond.
Refining, Stone Removal, and Frosting lots are available for Gold and Silver ( 2 metal recovery), Silver Only (1 metal recovery), Platinum, Palladium, Gold and Silver (4 metal recovery).
More details about Refining Lots, Stone Removal and Frosting can be found here.
Impurities in Refining Lots
On occasion, a customer will get a refining lot with unusual results. This could be a higher than usual melt loss or a lower than average assay. A number of factors can influence your results for a refining lot.
Under Karated Jewelry
Large and small manufacturers of jewellery alike all undercarat their gold jewelry. This problem is seen throughout where jewelers fail to properly karat the gold before casting. Cutting corners at the manufacturing level can short the customer and ultimately the person or company buying the scrap gold. Gold jewelry made prior to 1976 is usually 1/2 karat or 2% lower than the stamped karat or per millage. New laws established in 1976 did away with this practice but it's important to be aware, especially when purchasing vintage or antique jewelry. It is important to note, that as a matter of business economics, all maunfacturers under-carat their gold and silver jewellery, as gold or silver, are of course, the most expensive ingredients in an alloy. Cost-cutting and the bottom line is the motivation for undercarating and it is wide spread across all manufacturers large and small. India is the leading manufacturing country for undercarated gold jewellery, while Mexico and China are the leading countries for undercarated silver jewelry.
Solder Joints
Items that have been sized or repaired are compromised depending on the solder used. Repair solder, which is typically underkarated, can lower the piece's overall gold content or karat. Chains with soldered links are especially vulnerable to this factor as many are made with chain maker solder which contain zinc, copper phosphorous and flux, no precious metals at all.
Alloys Used in Gold and Silver Jewelry
Some base metals, like Zinc and Tin, have a lower melt temperature than gold and silver and burn off during the refining process when heated to the proper temperature to achieve a hom*ogeneous melt. This burn off can be responsible for a higher than usual melt, or mass loss.
Non-Precious Metals in Gold and Silver Jewelry
Melt or mass losses can occur from the steel springs in lobster claws and C-clasps. In large chain lots, these springs can add up and represent an inflated melt loss. Many jewelers cut off the clasps and reuse them in their retail operations eliminating the inevitable contamination in their refining lots.
Gold and Silver Refining Results
Typical losses from refining gold are 1%-2.5% from melt or mass losses and another 1.5%-2.5% on assay or undercarat losses.
Typical losses from refining silver are 2%-4.5% from melt or mass losses and another 2.5%-7.5% on assay or undercarat losses.
For more information about refining gold, silver, platinum, or palladium, please email or call 1.877.468.2220.
