Refinery Research

By Page on May 29, 2007 at 12:09 am

Refinery Research:

Over the past year and a half we have researched refineries that use only recycled metals & fair trade metals- determined to find a local refinery we feel supports our principals.

Most refineries will say that they use mostly recycled metals—this is true, particularly with precious metals. Precious metals are just too valuable not to recycle. However, roughly only 40% of the metal is reclaimed. Typically, reclaimed metals are mixed with new metals, which are purchased from large metal companies. It’s often unclear where these metals are coming from.

• Once metal is melted down together—it’s more or less impossible to trace its origins. This is why we think it’s really crucial to establish federal standards for recycled and fair trade metals. Too much responsibility is placed on the consumer, and it is nearly impossible to learn about the material’s history.

• Last summer we toured the Hoover & Strong Refinery in Richmond, VA. Hoover & Strong offers jewelers recycled metals in various forms & utilizes refining techniques that are more environmentally efficient. Their website is also a good source of information.

• Another refinery we think is doing good work is Precious Metals West, located in Los Angeles. While Precious Metals West is a smaller company than Hoover & Strong and doesn’t have the resources to be as progressive in terms of equipment and their manufacturing capabilities, they are very flexible and open with their information. Precious Metals West will allow you to source your own metals (either recycled or purchased from a responsible mine), which they will then refine for you.

• We are really trying to encourage both of these companies to begin manufacturing recycled chain. If you want to help out—contact

Below is information taken from Hoover & Strong’s catalog about how to best sell back you scraps & the steps that are taken to refine your scraps into usable metal.

How to sell back your metal:

Six ways to separate your scrap:

1. Gold scrap-karat scrap, jewelry scrap, filings & benchsweepings
2. Silver scrap & filings
3. Platinum
4. Palladium
5. Gold filled scrap, watch brands & optical scrap (keep each item separated)
6. Floorsweeps, polishings, sink sludge , emery & filiters

How to Maximize Your Returns:

1. Anything used in precious metal manufacturing should be turned in for refining with sweeps in a container. This includes store buffs, brushes, emery paper, etc.
2. Include the weight of the scrap
3. Separate metals, not karats
4. Separating your scrap increases your bottom line by minimizing your refining charges.
5. Separate magnetic from non-magnetic material.
6. Track the scrap in your shop
7. Send your scrap to a reputable refiner

How to make sure your saving your metal scraps

Sink Trap
A sink trap can be purchased or made for very little cost. Purchase a 5-gallon or larger container that will fit under your sink.

Separate Metal
Separate the metals in the shop, silver from gold.

Floor Mats
Capture scrap in your floor mats—Use heavy-duty rough pile floor mats. Keep a small separate vacuum to collect only gold scrap, filings and floor sweeps in the shop.

Have two separate wastebaskets one for regular trash, one for trash that has small amounts of precious metals.

What happens to your scraps when you sell them to a refinery?


Clean scraps are mixed with a special flux and then melted. The flux makes the metal more fluid and homogenous. The melt is then poured into a mold, the metal settles to the bottom and the slag created by the flux remains on top taking some of the non-metallic impurities with it. After smelting, the bars are returned to the vault to be weighed and sampled. The bullion remains in the vault until you have been paid for your scrap.


After your bullion has been weighed, drill samples are taken from each end of the bullion. This sample is fire assayed in duplicate to determine the precious metal content of the refining shipment. The assay lab does a miniature refining process on multiple samples to determine the precious metal content. The bullion karat is actually determined by the percentage of fine gold remaining following the assay process. The results of the assays must agree. If they do not, the bar is remelted to ensure that it is homogenous and resampled and reassayed.

And then there are Sweeps

Sweeps require more involved processing than clean scrap. It would be impractical to melt down a sweep because of its large volume and low grade gold content. The sweep is first burned at a low heat to incinerate the combustible material. It is then milled into a fine powder and sifted. By producing a fine blended powder, the sweep is made homogenous. A representative sample is taken and assayed to determine the fine gold content.

Refining to fine gold

The metal is now ready to be refined into its precious metal component. Hoover and Strong has invested in a new refining process known as the “Miller” process. Bullions from smelting are melted into a furnace. Chlorine gas is then bubbled through the liquid metal, turning silver and base metals into solid chlorides. These float on top of the melt and are skimmed from the surface to undergo a secondary refine to reclaim any silver. Once the process is complete the remaining liquid metal is at leas 98% pure gold. This is cast into anodes and electrolytically refined by submerging into a gold-based solution. During this process, fine or 24kt gold is plated onto the cathode. Both platinum and palladium remain in the electrolyte solution where they are later recovered.

Comments (2)

  1. Thanks for this info! Everyone should really make an effort to sell back their scraps. Since I started doing this, about a year ago (I’m in LA), it’s become totally a habit and not at all a hard extra few steps to take. Keep up the great work on this blog!

  2. the floor mats method is too tedious!!! gets your metals all mixed up with dust. best way= separate waste-baskets.

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