Ask MGS: What are Gold Concentrates?

One of the reasons our clients choose MGS is our depth of experience. With more than 30 years in the business, we’re experts on gold. Naturally, this invites lots of questions from jewelers, pawnbrokers, and other professionals who want to learn more about the world’s most popular metal – and we’re happy to oblige! This week’s question is “What are gold concentrates?”
While “gold concentrates” sounds like one of gold’s chemically modified derivatives, it is in fact, natural. Better known as “pay dirt,” gold concentrates are sourced in two different ways. The first is through gold panning (or other techniques that use gravity separation). When panning for gold, the objective is to separate the particles of dirt from the heavy particles of gold. In most cases however, gold is not the only heavy material in the pan. This end result of the panning process is the gold concentrates – which must be sifted through manually to extract the bits of gold. Gold concentrates tend to be mostly iron, so they are also known as “black sands.”

Gold concentrates are also made by grinding down ore, quartz, or other productive rock types into sand. This procedure is much faster and easier than panning, but the tradeoff is a final product that has less gold “concentrated” within. The pay dirt bundled with panning kits or sold as souvenirs in gold rush towns usually comes from this grinding method.

In a way, gold concentrates are quite similar to the polishing material and filing dust that collects on a jeweler’s workbench. The main difference is that bench sweeps contain a lot more gold – which is why we buy them. Unfortunately, natural gold concentrates don’t contain enough gold for our refinery to work with, so we don’t accept any from customers. However, we do have clients whio do work with gold concentrates, feel free to call and we’ll send you in the right direction.

Have a question about precious metals for MGS? Contact us or post on our Facebook page.

How Ultra-Pure Gold is Made

Hans Emil Wohlwill, a German engineer, invented the Wohlwill Process in 1874. Unlike the Miller Process, which is known among refineries as a relatively cheap and easy way to produce high-purity gold (in the 99.95% purity range), the Wohlwill Process is complex and expensive. But when done correctly, it can produce gold samples of 99.999% purity.

The Wohlwill Process has three main components:

  • The anode – an electrode through which electric current flows into a polarized electrical device
  • The cathode – an electrode through which electric current flows out of a polarized electrical device
  • The electrolyte – an electrically conductive substance (standing in for a polarized electrical device)

Each of these components contains gold. The anode is made of somewhat impure gold – about 95% purity or higher (lower purity will reduce the efficiency of the procedure). The cathode is made out of pressed 24k gold sheets. The electrolyte is pure chloroauric acid, made by dissolving gold in a powerful acid called aqua regia.
With these components properly set up, an electric current is applied. Electricity travels from the anode, through the conductive electrolyte, and into the cathode. When this occurs, the gold in the impure anode dissolves and its ions travel though the chloroauric acid, then electroplate or “stick” to the 24k gold cathode. This continues until the anode completely dissolves. The ultra-pure gold that collected on the cathode is melted down to whatever specification the application demands.

This is a very expensive procedure – especially because it takes gold to make gold. To perform the Wohlwill Process, a refiner must have enough gold for anodes and cathodes. They also must have large amounts of gold on hand to convert to chloroauric acid (fortunately, this process is reversible). Because of the complexity and cost of the Wohlwill Process, it’s used only for specific applications. Instead, most refiners prefer to use the Miller Process to create high-purity gold.

Facts & Figures about Gold Recycling

Gold is a critical part of the world’s infrastructure – influencing the global economy, allowing for technological innovations, and creating timeless artwork. Unfortunately, gold is a non-renewable resource that is labor intensive to produce. But on the bright side, the burden of gold production is lessened by recycling efforts that contribute to the world’s gold supply.
For example, according to the U.S. Geological Survey, the United States produced 211 tons of gold in 2014, with a reported consumption of 165 tons. During that year, 200 tons of gold scrap was recycled - 17.5% more than the reported gold consumption. Most of this recycled gold comes from facilities that process electronic waste such as computers, televisions, smartphones, etc.

Electronic recycling is an important service for the gold market and the environment, but it’s a very tough business to succeed in. For one, the extraction process is difficult, time consuming, and requires dangerous chemicals. Additionally, the yield is very small. One ton of printed circuit boards contains approximately 10 ounces of gold, so e-scrap refineries are dependent on high volumes.

Currently, our refinery is not certified to remove gold from electronics. Our focus is on recycling the gold, silver, platinum, and palladium scraps that are byproducts of jewelry making, manufacturing, and other sources. But if you’ve ever been to our storefront after the 10am London Fix, you know that we refine at a high volume too! For more than 30 years, the mission of our refinery has been to help local businesses by making gold recycling as easy as possible. To celebrate gold recyclers everywhere, check out the infographic below for some interesting statistics from the industry.