Platinum jewelry manufacturing presents some very different concerns when discussing the collection of materials for refining purposes. Areas of concern are definition of materials to be collected, cross contamination, mixing of alloys when "refreshing" casting grain, the number of times refreshing can be safely accomplished, removal of magnetic material, assaying methods, processing times, return of dollars vs. ounces, increased refining costs, settlement times, and expected levels of return.

Collection of Materials
In any collection effort materials must first be defined to allow for proper refining operations. There are two basic types of materials in the jewelry industry when discussing refining. These are Meltable and Burnable.

Meltable items are those that are predominantly metal, such as trees, sprues, filings, substandard inventory (scrap), bench sweeps and any fabricated product such as sheet metal skeletons, wire tubing, etc. All of these are items that should be melted, sampled and assayed.

Burnable items are also defined as sweeps materials. Polishing dust, floor sweeps, ultrasonic  sludge, tumbling solution, slag, crucibles, sink trap sludge, filters and carpeting.

Cross Contamination
It has repeatedly been said, "Do not use the same polishing and buffing pads for both gold and platinum." Gold will become imbedded into the platinum resulting in a product that requires more finishing. Platinum particles embedded into gold product requires extensive finishing work. Manufacturers must label the buffs to be used specifically and individually for gold and platinum. Another area where cross contamination can occur and cause large problems is the mixing of bench filings or metal scrap.

Imagine a standard alloy of 95/5 IrPt alloy and an addition of 90/10 IrPt along with 95/2.5/2.5 Pt Cobalt Cu. Each of these alloys in the production cycle requires casting and bench work. Each has differing melting temperatures. If one were to mix the filings, sprues and trees for re-use then a new animal will be created with unknown properties. Any product manufactured would not be able to be identified as Platinum due to the introduction of the 90/10 material.

Cross contamination can also occur from the use of bench tools for both metals. Saw blades and other tools can deposit gold onto platinum and vice versa, not to mention iron from files and cutters, etc. It is suggested that when possible, a completely separate workstation be made available.

Refreshing
Refreshing is defined as adding in new alloy to existing scrap, casting trees or sprues and buttons. Typically with the standard gold casting processes this can be an extremely dangerous operation.  The build up of impurities in the casting metal will cause porosity and inclusions.

Additions of 50% to 75% new gold alloys are required to maintain the purity and karatage. Of course, the complete removal of investment is mandatory for both gold and platinum casting operations. The number of times manufacturing casting can be accomplished before starting with completely new casting material is very dependent upon how clean the casting material is.  The high levels of metal purity in platinum alloys, specifically platinum ranging from 90-95%, dramatically increases the number of times refreshing can be accomplished.

Magnetic Material
In certain alloys of metal, platinum with silver and nickel at the right percentage will produce a magnetic alloy. Magnetics create problems with assaying for any precious metals content. Unless processed  properly, the resulting assay may report too high of a metal content (bad for the refiner) or too low of a metal content (bad for the manufacturer). The addition of copper or copper oxide to the magnetic
material during the melting process will homogenize the magnetics and alloy for accurate assay of precious metals. This can require in some cases 200-300% addition of copper to eliminate the magnetics. As a result, refining costs to deal with this specific problem can increase. Additionally, the melting time can double or even triple. The introduction of oxygen to the melting process will accomplish the same result, however, processing times are also increased with additional costs as well.

The refining of polishing sweeps and floor sweeps typically have charges associated with the incoming weight of the material. To minimize the refining costs of these materials, standard recommendations are to remove items such as paper clips, saw blades, iron filings, staples, etc. by running a magnet throughout the material. This removes magnetics and also reduces the weight of the lot, lowering the refining costs. With platinum based sweeps this can remove platinum filings as well. Therefore, it is strongly suggested that a very close visual inspection on all sweeps be conducted to remove as many non-value materials as possible and refrain from the use of magnets.

Processing Times
The time for refining platinum materials takes longer than for gold materials. This is due to the increased temperatures required for melting platinum versus gold.  Additionally the assaying times are longer due to the different methodologies used.  Processing times for platinum based sweeps are the same for standard gold sweeps. However, the assay times are more time consuming and therefore more costly.  Mixing or collecting gold and platinum scrap automatically adds more work and effort to the refiner. This will add to the settlement time and also add cost.

Settlement Time
Standard settlement times for gold based refining materials range from straight exchange to 10 days. This varies based upon purity of metal and volume for metallic scrap. Sweeps range from two weeks to four weeks. When platinum group metals are added into the equation, time may be extended out to 14 weeks regardless of material type.

Return of Dollars Vs Ounces
One of the most important aspects of the refining process is the type of return available to you. Dollars are easily funneled back into your business. However, the consideration of having metal returned in the form of alloy or pure can have benefits and some limitations. Many refiners do not have access to pure platinum unless they transfer ounces to another refiner or trading operation.  Many times the refiners do not manufacture alloys and thus need to transfer dollars or ounces to another source to provide service for customers. Therefore, other than refining charges, consideration should be given to the costs of having metals returned as opposed to dollars.  There are always costs related to metal returns, but dealing with sources that provide full service, especially for alloys can minimize some of these costs.

Expected Levels of Return
With gold refining the manufacturer can maintain a system to track metal loss by operation and from there, predict over time what the refining returns should be. These systems can be readily applied to platinum manufacturing as well. One method that gives a level of predictability over time is to track the ratio of net weight shipped versus refining return. This can be applied to metals and sweeps and gives the manufacturer a picture of his processing operations.  Keep in mind that proper assaying is the only accurate method to determine metals content or value.

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Maximizing Refining Returns for Platinum Alloys
Knowing Your Inventory)
Robin White
David H. Fell & Co., Inc.

This is an abbreviated version of the original work. For full technical details, please consult the original paper.