Saturday, February 10, 2024

How Is Gold And Silver Refined

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A Lab Assesses The Gold

Making nitric acid for gold and silver refining.

For this process, the gold usually has to be sent to a lab. From this point, several different methods can be used to determine the karat number of gold. These analytical methods include Inductively Coupled Plasma-Mass Spectrometry , Atomic Inductively Coupled Plasma-Atomics Emission Spectrometry and Atomic Absorption Spectroscopy .

Refining Gold At Home

Most people enjoy the rewarding feeling of a DIY project. It might seem that gold refining would be a nice hobby and perhaps even profitable. You might be more tempted if you came across some gold nuggets as a modern-day gold prospector. Refining gold at home is not a good idea, though. Here are a few reasons you should leave it to a professional gold refiner:

  • Undesired results It is challenging to attain the level of gold impurity removal that you desire.
  • Potentially dangerous Some methods can be performed on a small scale but can also be dangerous. Working with acids or high heat can go horribly wrong.
  • Fees arent high An expert gold refiner charges only a small percentage based on the melt value. You wont save enough doing it yourself to warrant the risks involved.
  • Assaying process You may not be set up to measure the accuracy of your refining result. Youd need to utilize a fire assay, ICP spectrometry, X-ray fluorescence, touchstone, or density measurement technique.

Hedge Funds Staying Away From Gold And Silver Focus On Tightening Monetary Policies

Kitco News

– Hedge funds remain hesitant to jump back into the gold market as the Federal Reserve looks to tighten its monetary policy in the face of growing inflation pressures, according to analysts evaluating the latest trade data from the Commodity Futures Trading Commission.

Analysts note that although gold prices have managed to hold support above $1,750 an ounce, it has not attracted enough investor interest for a sustainable push above $1,800 an ounce.

The CFTC disaggregated Commitments of Traders report for the week ending Oct. 12 showed money managers increased their speculative gross long positions in Comex gold futures by 4,923 contracts to 131,668. At the same time, short positions increased by 570 contracts to 73,149.

Gold’s net length now stands at 58,519 contracts, relatively unchanged from the previous week. During the survey period, gold prices were caught in a narrow range, holding support above $1,750 an ounce.

Although gold prices managed to push to $1,800 an ounce last week, the rally was fleeting, with prices falling back to where they started the week. December gold futures last traded at $1,766.50 an ounce, down 0.10% on the day.

It’s not just gold that continues to suffer from a lack of investor interest.

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The Metal And Its Alloys

Pure gold has virtually no industrial uses other than as a backing for currency. In reality, no country backs its currency with an equivalent amount of gold, but to some extent the solvency of a country is equated with its gold reserves.

Jewelry represents the single largest use of gold. Because of the metalâs softness, it is alloyed with other metals to provide the requisite hardness and strength. Typical jewelry alloys include gold-silver, gold-copper, and gold-silver-copper. Most gold jewelry varies between 14 and 18 karats. Gold also finds extensive use in the casting of dental bridges and crowns. Here it is usually alloyed with silver and copper, although platinum or palladium are sometimes added to increase strength.

Because of its combination of high electrical conductivity and high corrosion resistance, gold is used in the plating of electronic contacts and transistor bases and in gold-based solders of extremely high reliability for semiconductor silicon chips. Owing to its chemical stability, gold has virtually no applications as a catalyst. However, it is sometimes used as a substrate for platinum catalysts employed in the production of nitric acid.

Chlorine Gas Method Miller Process

Gerald Whitely: Read Proverbs 26:23

In 1867, Francis Bowyer Miller patented his gold refinery process utilizing chlorine gas. A purity of 99.5% is achievable with this method. The unrefined gold is first melted and then a stream of pure chlorine gas is blown over it, turning the impurities into salts that are then removed.

PGMs are not removed during this process, which is used when pure gold isnt necessary, such as for use in electronics and other manufacturing. The Miller process is typically used by large-scale rather than small-scale refineries.

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How Is Silver Refined

A: Silver refining is basically the recovery or recycling of silver from items that contain this precious metal. Items that are refined for their silver content include:

  • Jewelry
  • Silver from photo processing solutions
  • Mirror over-spray

For industrial and manufacturing items such as silver flake from photo film, silver from x-ray film and scrap silver sludge are recovered. The process is more involved where the refiner first has to burn the film and then put the ashes into the acid base.

On the Web you may find methods for home silver refining, I would not recommend this without having an experienced refiner handy. Because you are working with acid, there is a risk in the home, especially if you are trying to collect ash which requires very high heat conducted in a furnace.

Lydian Gold And Electrum: Final Questions

The Pactolus stream was famous in antiquity for its gold Herodotus describes it as one of the two things worth seeing in Lydia . This must have provided the Lydians with tremendous wealth, allowing them to monumentalize their city with colossal fortifications and terraces, and to build their military power to conquer western Anatolia.

It has long been assumed and stated as fact that the source of electrum for Lydian electrum coins and for the refinery at Pactolus North was alluvial gold with a high silver content, found naturally in the Pactolus and other streams in the vicinity of Sardis.5 Ancient authors often do not distinguish between gold and electrum, or gold and white gold as the Greeks sometimes called this material when Herodotus describes the gold flakes in the Pactolus, he could mean either pure gold or electrum. Modern scholars have believed that this abundance of electrum from the Pactolus explains why the Lydians first minted coins in electrum, rather than pure silver and gold.

Recent analysis of natural gold from these streams and other sources around Sardis, however, reveals that the ore contains virtually no silver, but is essentially pure gold.6 A number of questions spring to mind. First, if the Lydians had pure gold, why did they mint electrum coins, and where did that electrum come from? and second, if the gold from the stream was pure, what were the Lydians refining at this industrial complex?

  • Fig. 6

    Alluvial gold from near Sardis

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Use Our Inquartation Calculator

A – Once the metal’s proportions are calculated, place the Scrap gold and base metals in a melting dish that has properly glazed with borax .B – Melt the scrap gold and base metal together. A small lot can be stirred well and form a consistent alloy simply by stirring the melting dish containing the molten metals. Larger lot with deep molten metal pools should be stirred with a carbon rod, each stir no longer than one second.It is very important that the alloy is consistent, i.e. that gold/base metal proportion is equal throughout the alloy.Tip: Preheat the carbon rod before introducing it to the molten metal. This will prevent molten metal from clinging to the rod.C – Pour the molten metal slowly, shot by shot in to a deep stainless steel bowl filled with cold water. The “shot” should look like metallic corn flakes. Flakes have a large surface area for the nitric acid to work on.
2 Silver digestion with nitric acid
Silver/Copper Nitrate solution should not be discarded. Keep it for later recovery and refining of Silver metal.

Helping with this article: Harold_V, goldenchild, Barren Realms 007 and gold4mike All members at the Gold Refining Forum

Advantages And Disadvantages Of Gold Electrolysis

WASTE TREATMENT for gold and silver refining

As the best technique for getting the purest gold all over the world, gold electrolysis is widely adopted among some gold-making companies that value only the purest gold. It does not produce gaseous fumes and other unpleasant gases. Gold electrolysis requires small amount of chemicals and labor. It is, in fact, environmentally friendly.

However, it is a very expensive procedure because a permanent stock of gold is required to run the electrolytic process. Take for instance, for every gold produced through this method, 20% of it is lost on the anode. In other words, if you aim at producing 100kg of gold, you should make provisions for 120kg, because at the end of the process, 20kg will be plated or wasted on the anode, leaving you with only 80kg of gold .

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Gold And Silver In Never

Kitco Commentaries | Opinions, Ideas and Markets Talk

Featuring views and opinions written by market professionals, not staff journalists.

One thing we can take away from the recent trade in gold, silver and platinum, it sucks. The price action has been about as bad as it gets. The metals, although in an uptrend, have wandered around the mean as if they were lost.

Understanding markets and how they trade is an important asset for traders and investors. The current action creates frustration, impatience and bad decision-making. Traders want instant gratification, which markets never guaranty. The recent activity is almost designed to put you to the test. Can you follow the game plan?

This type of action has been happening for thousands of years markets are driven by emotions. Humans will fail the emotional test 90% of the time. As the commercial says, the mind is a terrible thing to waste, but frustration and losses will drive traders to poor decision-making.

Trading your method or mine requires you to follow the rules that have been designed for your methods. We trade our algorithm and will remain long for the duration until the algo turns short. Short-term emotional decisions are wrong.

Patience, discipline, and money management always win the day. Let the map of the markets show you the way.

Thursday 11/04/21 at 10:00am EST, I will present our new portfolio models that use Mini/Micro Futures, including Gold, Silver, and Bitcoin

Main Processes Used For Silver Refining

There are three main processes used for silver refining

1. Pyrometallurgical refining involves melting processes to separate pure silver from other metals. Technically some of the pyrometallurgical techniques are pre refining steps to concentrate or separate silver and not technically refining. In order to produce high purity silver in almost all cases, electrolytic refining is used.

a) Calcining concentrates the silver by burning off any volatile materials including organic compounds.

b) Roasting can change the composition of the silver by converting say silver sulfide into native silver. As it changes the chemical composition of the silver it may not technically be a refining technique but it is an important processing step in many silver-bearing ores and concentrates.

c) Miller Process involves removing the silver and base metals from gold by sparging chlorine gas through molten gold to form silver and base metal salts which are skimmed off the molten gold for processing. Silver chloride can be further processed by smelting techniques with zinc to form silver and zinc chloride or can be processed by the addition of sodium hydroxide and sugar/dextrose reduction. Again, while these processes are quite commonly used, they are complex involving several steps and not strictly speaking refining processes.

d) Fusion melting with lead to alloy the silver and pgms. Zinc is used and removed in the slag leaving high-grade gold and silver which still need to be further refined.

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From Gold And Silver Concentrates And Ores

Cyanide leaching is often used to recover gold from its ores. Fine gold particles dissolve easily in cyanide, typically using NaCN concentrations of 0.02-0.05% if the dissolved oxygen content of the solution is not high enough, aeration may be required.

4 Au + 8 NaCN + O2 + 2 H2O 4 NaAu2 + 4 NaOH

Once dissolved in the cyanide, the gold must be recovered from the pregnant cyanide solution. Often, the Merrill-Crowe zinc precipitation process is used, or the adsorption of gold onto activated carbon.

The steps in the Merrill-Crowe process are oxygen removal, mixing in fine zinc powder, and gold precipitate recovery by filtration. The addition of zinc leads to the formation of a zinc cyanide complex and gold metal.

2 Au + Zn 2 Au + Zn42-

Sulfuric acid is used to dissolve any zinc impurities that have precipitated with the gold. The final gold solids are smelted into gold doré bars.

Silver is also easily leached using cyanide and can be recovered using the same methods employed for gold recovery, as described above. However, electrowinning has proven to be an economical alternative, even more so when utilizing emew technology. Electrowinning can be used directly after the cyanide leach, resulting in fewer process steps, and therefore lower operating costs.

Silver Processes & Uses

Removing the Dross

Although silver is relatively scarce, it is the most plentiful and least expensive of the precious metals. Nevertheless, geologists currently estimate that given current demand, the worlds extractable resources of silver will last only another twenty years.

Todays silver comes from three primary sources: silver mining silver produced as a by-product of mining for other metals and silver recycled from used materials, including old jewelry and photographic films and chemicals.

Silver is rarely found in its pure form, called nativesilver. The largest silver nugget ever found weighed a whopping 2,750 pounds troy and was discovered in Mexico. More commonly, silver is found in mineral ores such as argentite, cerargyrite, stephanite, and chlorargyrite.

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The Refining Process At Sardis

Recovering gold and silver from electrum was accomplished at Sardis during the first half of the sixth century BC in simple installations located outside the city walls and close to the Pactolus Stream .2 Two metallurgical techniques are directly attested by the archaeological remains: cementation, which was used to separate gold from silver and other metals present in secondary or placer gold and cupellation, which was used to recover silver in metallic form after the cementation process, and perhaps also before cementation, to remove base metals that also occur, together with gold and silver, in secondary or placer gold.

After cementation, the gold was tested, or assayed, to determine its purity, then collected and delivered to some other part of the city for consolidation in large amounts . To test for purity, the gold pieces would have been melted on fragments of coarse vessels, like those used for cementation , and rubbed on a touchstone, like No. 16, found in a Lydian house the streak made by rubbing would then be compared to the streak made by a gold needle of known purity.3

The furnaces, fragments of parting vessels , fragments of gold sheet, and other associated materials are the earliest known evidence for the cementation process anywhere.

Sulfur And Antimony Processes

De Re Metallica

This is similar to the salt cementation process but creates sulfides instead of chlorides. Finely divided impure gold and elemental sulfur are reacted together under moderate heat in a sealed crucible. The impurities form metal sulfides and the gold is left unreacted. The gaseous sulfide condenses on the crucible fabric. The antimony process is the same but uses stibnite instead of sulfur because stibnite is stable at a higher temperature than sulfur. This is much quicker than the salt process and gave a purer gold, but it could dissolve some of the gold as well. This process is first described in the Probierbuchlein.

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Factors To Consider When Choosing The Best Gold

Outlined below are some essential criteria you must put into consideration when deciding which gold-refining method you would like to use:

  • The cost: Is it cheap or expensive?
  • Environment: Is it environmentally friendly or not? The issue of protecting the environment is very popular in many nations, and this may hinder your gold-refining processes if some of your chemicals are toxic and harmful to human beings.
  • Merits: Choose the gold-refining system that has more merits than demerits.
  • Gold workers: Make sure your workers are properly trained on how to use the gold-refining equipment.

Electricity Method Wohlwill Process

How Pure Gold Is Refined

In 1874, Emil Wohlwill discovered that electricity could be used to purify gold. This method requires three components:

  • Cathode
  • Anode
  • Electrolyte solution

Another method must initially be used as the cathode is made from refined gold. The cathode is suspended in the solution. An electric current is passed through. The impurities are dissolved, becoming a slime that sinks and can be treated separately to recover the base metals, as well as palladium and platinum.

Pure gold is drawn from the anode to the cathode. This is a longer process than other methods but delivers 99.99% purity. It cannot be used with unrefined gold-containing more than 10 percent silver. Initial gold content must be roughly 96 percent.

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How Scrap Gold Is Refined

The most commonly used and one of the most accurate methods for refining gold is the fire assay method. This is an industry-standard procedure that, while reliable, is very involved and requires many steps. The process is worth the time and effort it takes, however, because it has been proven to be 20 times more accurate than any other method.

Even though this is the most used process for assessing gold, it can be time-consuming. The process needs to be precise, and there is a lot of room for something to go wrong and for the calculations to be inaccurate. Because of this, the process can only be relied upon if highly skilled workers carry it out meticulously. Heres how the fire assay method works.

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