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Basic Provisions of the Process Licensing
What We Can Offer to You
Micron gold has always been a major challenge for many gold prospectors, whether they recognize it or not. Because it is so small, it might be present but you may not even know it. It takes extremely good panning techniques to capture it in a pan, and a sluice will generally wash the micron gold out with the tailings, maybe even easier than washing out the fine black sand.
If you suspect you have micron gold, the first step is to look for it with a good 20X or 30X magnifier, looking for discrete, small particles of gold in the black sand. If you don't see it, you may still have it present as gold encapsulated in a thin layer of iron oxide or iron sulfide or any of the other ore components that are typically encountered. Perhaps a better way is to have an XRF test performed, which will also identify other metals present, including silver, lead, zinc, mercury, and the platinum group metals (assuming the XRF device is programmed for those additional metals). The platinum group metals can be very difficult to identify visually, because they will likely be in very small quantities and their physical appearance is very plain. Remember, if you don't specifically look for it, you will never know that you had it to start with. In the iodine leaching process, the platinum group metals will concentrate with the base metals after the gold is deposited, making the recovery simpler.
There are many systems available to process micron gold, each with their strong points and their weaknesses. The mechanical processes like wave tables tend to require expensive equipment and very precise operating conditions, but the gold is immediately available and readily visible. Processes that use moving water, like the Blue Bowl and wheels, tend to require very carefully controlled flow rates and a very narrow range of classification. Essentially all of the processes, including mine, will demand that the starting materials have not been subjected to any process that would have already flushed the micron gold away with the tailings. The cyanide leaching process has been developed very successfully to recover much of the small gold, including micron gold, from low grade ore; however, such a process is totally unsatisfactory for a small scale miner because of the toxicity, the significant amount of equipment required, and the excessive controls over environmental release.
There are other leaching processes available, with varying degrees of effectiveness, ease of use, cost, and different levels of safety. I believe that my iodine process can be attractive for many of the micron gold applications that exist, whether it be beach sand, waste black sand, sluice tailings, raw ore, or even scrap jewelry (including plated or filled jewelry). The chemistry is sophisticated (but simple for the end-user), uses readily available raw materials (most are over the counter, general purpose chemicals), the chemicals are generally considered to be very safe for people, animals, and crops, and the disposal of waste materials is not considered hazardous (although disposal of large amounts of anything is generally considered inappropriate). As a side benefit, the iodine leaching process can be used as a very simple, very quick method of determining the presence or absence of gold, even as a field test. However, because of the wide range of variables, it is not a practical method for determining the quantity of gold in a particular sample.
Many of the accounts of poor performance of iodine as a leaching agent for gold have contained significant inaccuracies as to the chemistry involved, giving rise to the notion that the process is much more difficult or more dangerous than it really is. The chemistry is, in fact, extremely sophisticated to the point where only an experienced chemist would totally UNDERSTAND what is happening, but almost anyone should be able to USE the process effectively and safely. Also, the general statement that the raw materials are too expensive to make the process economical is quite often based on a poor understanding of how the iodine materials are recycled: the initial cost is VERY high at about $50 per pound, but the regeneration cost is very low. The active leaching chemical is no more dangerous or toxic than Povidone Iodine, which is designed to be swabbed onto human skin, even with minor cuts and scrapes, several times per day. The major aspects that will control the economic feasibility of a particular operation must be determined by the owner of the ore and are basically related to:
the quantity and the quality of the starting ore
the purchase cost, transportation cost, and disposal cost of the starting ore
the amount of time, effort, and resources the owner is willing to provide for extraction of the values (each ore will behave differently and will require slightly different processing)
the efficiency of the iodide recovery from the spent ore
the efficiency of the purification process for the recovered gold (especially with high value materials, "every time you touch it, you lose some of it")
the available options for sale of the recovered gold (sale to a regular gold dealer is probably not attractive due to the high purity and/or PGM content)
General advantages of the iodine leaching process, as I have developed it:
The expensive chemical in the process (potassium iodide) is largely reusable as sodium iodide.
All other chemicals used in the process are readily available, at low cost, at a grocery store, pharmacy, and/or hardware store.
In household quantities, disposal of waste products is generally accepted by most sewer authorities.
Electrical power is not required for the leaching operation, for reactivation of the leaching solution, or for the recovery of gold.
The only water requirement is for dissolving the salts to make the leaching solution, for rinsing the spent ore for iodide recovery, and for washing the recovered gold.
Leaching and storage containers can be almost any readily available glass container or plastic container, including milk jugs, peanut butter jars, polyethylene, polypropylene, etc.
Leaching is very rapid, allowing its use as a field assay tool to determine presence or absence of gold in hours, rather than in days or weeks (not recommended to determine precise quantities of gold).
No expensive monitoring equipment is required to perform the full range of leaching, processing, and recovery operations. Essentially all operations can be monitored by unique color changes in the process.
Leaching can be easily accomplished in the field, thus avoiding transport of the ore back to a central processing location.
The leach solution can be customized to be strongly aggressive toward iron or mildly aggressive, depending on the user's needs and whether or not you NEED to be aggressive.
Leaching a small amount of material in a small container. This would be appropriate for evaluating a new source of ore or for evaluating the leaching effectiveness within a larger operation. Think of this as a laboratory or exploratory scale.
Leaching a small amount of material in a bucket. This would be appropriate for micron gold left over from dredge concentrates, low volume tailings, or to determine if a multi-container system would be appropriate. Think of this as a pilot stage, to determine what is needed for processing large quantities of material.
Leaching a large amount of material in small or large portions by using multiple containers. This would be appropriate for raw ore that might require several hours of leaching time or for ores requiring a large throughput.
General limitations of the iodine leaching process, as currently identified:
Not appropriate for ore that contains silver or silver salts (the silver halide that forms is very difficult to deal with and is insoluble in the leach solution. It will also tend to rob the leach solution of iodine). BlackSand2Gold is working on details for removal/recovery of silver.
Leaching of gold particles that are readily visible may require a substantial leaching time due to the limited surface area available.
Large quantities of metallic copper or copper salts will interfere with the leaching, the processing of the leach, and will rob the leach solution of iodine. BlackSand2Gold is working on details for removal/recovery of copper, lead, mercury, and zinc.
The leaching process has not yet been optimized for separation of PGM's, but it is expected that PGM's will pass through the leaching operation and be recovered with the base metals. This problem is difficult to resolve because testing for PGM's is sophisticated and is not readily available to the small scale miner, therefore, most miners probably won't even know how to test for them.
Because every ore is different, I suggest that, if you have an interesting ore, send me about a quart (a few pounds, or whatever it takes to recover about 100 milligrams of gold) and I will do my best to extract all of the gold and PGM's from it and let you know the results and whatever problems I encounter. Based on those results, you need to decide if it might be practical for you to subscribe to my process and leach your ore and then work with me to purify it into saleable gold. It will cost you very little to subscribe to my process and to purchase a few supplies for you to actually leach your own ore. The leaching process is very simple but I do not intend to place it into public knowledge (and I require that you do not release it, either, hence the required non-disclosure agreement). I do ask that you use the Sample Submittal form to document a few things; especially, a clear statement that you actually own the sample and how to contact you with the results.
Be aware that the leaching process will generate a very pure form of metallic gold, free of the black sand and most other minerals, but it will be incredibly small particles that are very difficult to handle. You will still need to process it further to obtain a saleable material. That processing can be done by BlackSand2Gold, by most jewelers, almost any fire assay lab, or you can learn how to do it yourself, but there may be a steep learning curve.
Last Revised: 11/30/2015