Silver refining: features and methods

There are many ways to obtain silver and some other precious metals by purification from impurities, and some of them are possible exclusively in industrial enterprises and chemical laboratories. However, there are methods that allow you to carry out the refining of silver in a domestic environment.

We will talk about them in our review.

In order to obtain refined silver from technical silver, techniques are used to rid it of various impurities. The combination of all techniques is called refining. At its core, this procedure is an industrial process, however, all the necessary manipulations can be performed at home.

For cleansing, you can use items such as:

• any silver jewelry;
• sludge obtained in the course of electrical treatment of Argentum;
• technical scrap containing impurities;
• waste of the lead industry.

Homemade methods of silver refining include the following techniques:

• chemical chlorination;
• cupelling;
• electrolysis.

The final choice of refining option depends on factors such as:

• the amount of metal processed;
• the ability to ensure the continuity of the technological process;
• the original condition of the alloy being processed.

The set of basic ones directly depends on which method of obtaining silver you have chosen.

So, for the refining of Argentum elements, you will need:

• glass container;
• quartz stick;
• Nitric acid;
• ammonium chloride;
• salt;
• sodium sulfide;
• any filter;
• funnel;
• deionized water;
• copper scrap.

When carrying out cupelling, it is necessary to prepare:

• stove;
• lead;
• crucible.

To perform electrolysis, you need:

• power unit;
• insulating material;
• stainless steel fork;
• insulating tape;
• tea bag pouch;
• any plastic container.

Silver refining is quite a profitable business. But since some chemicals are used during metal cleaning, safety rules must be followed.

The first thing you should pay attention to before starting work is the possibility of ventilation of the room in which the silver purification measures will be carried out... The ideal option would be to carry out work outdoors - this will prevent poisoning with hazardous chemicals. If this is not possible, then you should choose a room in which a powerful hood is installed, and there are also windows that can be opened if necessary.

At the stage of working with nitric acid, additionally you need to wear a respirator, otherwise, vapors of this dangerous substance will enter the lungs and cause paralysis of the upper respiratory tract.

We pay special attention to the fact that it is strictly forbidden to pour water into acid - this may cause splashing of the chemical. According to the safety rules of behavior in a chemical laboratory, you can only carefully add the acid itself to the water.

In general, if exactly follow the technical instructions for refining and follow the established sequence of processes, then you can get a precious metal of the highest quality even in domestic conditions without any threat to the life and health of the person doing the work.

This method is used to obtain precious metals from solutions. The procedure for cleaning silver from additional impurities at home in this case includes several steps.

1. Initially, some sodium sulfate is added to the solution to form silver sulfate. After the compounds have reacted with each other, ammonium chloride is added to them - as a result of this reaction, silver chloride is obtained.
2. The liquid formed in the course of these reactions is defended for some time so that it is divided into separate fractions. The result should be two separate solutions - one transparent, the other more turbid.
3. After chemical refining of silver, the silver itself should be separated from the solution; this will require a funnel and a paper filter.
4. The entire solution is poured into a bag - the liquid will flow out into a plastic container, and powdered metal will be visible on the paper.
5. All the resulting powder should be dried and fused into a single whole - this is silver chloride of a low standard. It is necessary to extract pure metal from it by dry method. To do this, it is mixed with calcium carbonate in equal proportions and melted.

The cleaning of low-grade technical argentum is carried out using cupping. This technology is based on the unique feature of lead, melted together with argentum, to oxidize in the open air and separate from the metal itself along with other impurities.

To perform cupping, you will need a bowl-shaped stove completely covered with marl. For reference: Marl is a rare porous limestone clay. It has a characteristic that maximizes the absorption of lead oxides.

The step-by-step technique for removing silver is as follows.

1. The oven is thoroughly warmed up and test tubes filled with technical argentum and lead are placed in it.
2. The crucible is heated to final melting. Upon completion of the thermal reaction, the crucible is removed, and its contents are poured into pre-prepared molds.
3. After the composition has completely cooled down, it will have a rainbow hue. This means that it contains not only silver, but also some other precious metals.

Contaminated silver acts as an anode in electrolysis, the cathode is represented by thin strips made of stainless steel.

The anode is placed in small linen bags - they will later collect all dissolved contaminants in the form of silver particles that have escaped electrolytic dissolution. In this case, the silver itself is deposited on the cathodes. If you do not have a lot of experience in performing silver refining, then it is better to turn to this particular technique.

The whole process is conventionally divided into 3 main stages:

• dissolution of metal in acid;
• isolation of silver salts and their further fusion;
• the refining itself.

At the initial stage, you will need:

• nitric acid solution 68-70%;
• quartz stick;
• any glass container.

First, pure acid is mixed with deionized water in a ratio of 1 to 1. The resulting composition is stirred with a quartz stick. The diluted acid is poured into specialized containers designed for chemical experiments. To obtain silver nitrate, you will need about 50 g of silver for each liter of liquid.

The substance containing silver must be melted in this liquid. This process is accompanied by the release of NO2 gas, and also causes the composition to turn blue. Dissolution takes quite a long time - it takes at least 8-12 hours to complete the reaction.

After that, the so-called "silver pigment" should be obtained. For this, metallic argentum is displaced from silver nitrate by copper. Please note that any water pipes polished to a shine can be used as a source of copper. The addition of this element provokes an acceleration of the chemical reaction. The resulting silvery tubular cement is powdered argentum.

The essence of the process lies in the fact that the tubes give their copper to silver nitrate, so during the refining they completely dissolve, and if this happens, you need to add another portion. During the displacement of silver, the process slows down, so you can safely leave it unchecked for several days. The only thing is necessary keep under control the presence of copper in the solution, and also watch that no foreign elements appear in it.

Then you can directly filter the cement. Keep in mind that the filtration procedure must be performed at least 5 times, this is the only way to get rid of the copper nitrate residues. After cleaning is completed, collect any remaining cement, evaporate excess moisture, or wait until it naturally evaporates.

At the end of the filtration, some silver may remain in the solution, so you can add a little table salt to it and leave it until a precipitate appears. Dry silver cement should be removed and melted, for this it must be heated consistently and evenly. Then casting into water is performed. Due to this, grains are formed, intended for subsequent work with metal.

At this stage, silver of about 980 samples is obtained, that is, some additional impurities will still be present in the alloy.It will be possible to get rid of them at the third stage, when refined silver is obtained directly, but first it is necessary to remelt the resulting metal alloy into a bar.

A stainless steel tape should be attached to the resulting silver form so that its edge remains hanging. After that, a cathode should be created from a plug, electrical tape and pliers, and the anode stick is threaded through the filter. The silver solution prepared in advance is diluted with ordinary distilled water, bringing its amount to 2 liters. The cathode is placed in an electrolytic bath, filled with an electrolyte solution so as to exclude contact with the contact area of ​​the tape and the silver bar. After that, the minus is connected to the plug, and the plus, respectively, to the stick, and an electric current is supplied.

After that, care must be taken that the growing silver crystals do not reach the cathode, as this can cause a short circuit.

Upon completion of the reaction the silver bar is completely dissolved, after which the electrolyte is drained. Silver crystals are washed several times in water and dried. Then all that remains is to melt the crystals.

Refining silver in the home can be fun and beyond your expectations. Each of the methods used is unique in its own way, and the effectiveness of the technology directly depends only on the efforts that you put into it.

For information on the features of silver refining, see the next video.