Silver as a metal: physical and chemical properties
The purest silver is a malleable and fusible element that is part of the group of precious metals. This group includes gold, platinum, and five other platinum-class metals.
All noble elements share a unique property - they remain inert when interacting with various air, liquid and gaseous media, leading to corrosion and oxidation. Lunar metal retains its natural shine when exposed to carbon dioxide. Under normal conditions, it reacts with sulfur to form silver sulfide.
In its pure form it is heavy, its density is estimated at 10.5 g/cm3. It is slightly lighter than lead, but heavier than copper. Capable of maintaining geometric dimensions and surface properties when heated, while possessing wide capabilities for changing shape.
Among other things, the precious metal is famous for its disinfecting properties.
Remelted silver bars
Melting and boiling points of silver: main factors
To melt the precious metal, a temperature of 962 °C or 1234.15 kelvin is required.
Boiling point is 2212 °C or 2485.15 kelvin.
This is the point after which a liquid body begins to transition to the gaseous stage.
Metal characteristics and melting point
Silver is more than 6,000 years old, as evidenced by archaeological finds in Turkey, Egypt and Iran. The second name of the precious metal is lunar, because according to esotericists, it is this luminary that serves as his patron, and the color resembles the cold shine of the Moon. In the past, this noble metal was valued more than gold.
Silver is characterized by the following physical properties:
- density - 10.6 g/cm3;
- hardness - soft and ductile;
- fusibility - high;
- thermal conductivity is the highest;
- electrical conductivity is the highest;
- reflectivity - yes.
The melting point of silver is 750-760 degrees.
Having decided to smelt silver yourself, you need to know the temperature at which the metal passes from a solid state of aggregation to a liquid state. It depends on the amount of foreign impurities in the composition. If the silver alloy includes a small amount of alloys, then its melting point will not exceed 750-760 degrees. The raw materials used in smelting are called charge. It is heated according to certain rules, taking into account the technological process, as well as observing safety precautions.
Why melt silver
Many people do not suspect that precious metal surrounds us everywhere. About 80% of global silver production comes from the industrial sector, with the remainder from banks and jewelry.
Lunar metal is found in radio components, batteries, contacts, capacitors, coins, cutlery, and jewelry. Even the average user's computer or laptop contains about 1 gram of precious metal.
By melting silver, you can create an analogue of a bank ingot or a unique dyeing with your own hands. If you have accumulated a lot of silver items at home that can no longer be useful, you should not rush to throw them away.
Preparatory work for silver smelting
Lunar metal is one of the materials used to make various household items and jewelry. Often, worn-out and obsolete things want to be given a new look or remade.
Silver that is outdated and tired can always be melted down
To do this, you can simply melt them and make another product, using the services of a craftsman or in a home-made environment. Melting silver at home requires strict adherence to safety precautions and the sequence of the technological process.
The silver component can be extracted on an industrial scale using specially developed technologies related to ore enrichment. In order to melt a small amount of metal at home, it is enough to have a minimum set of equipment, including:
- metal spoon;
- asbestos;
- borax;
- burner;
- scales;
- scrap metal;
- graphite powder;
- microwave or muffle oven;
- fireclay clay.
Metal smelting involves a change in the state of aggregation associated with the transition from solid to liquid under the influence of a high temperature gradient.
At home, it is necessary to take into account that the molten material must be cooled. Therefore, before starting work, it is necessary to first make a mold for casting the product. The silver material that is melted is called charge.
If it is necessary to melt a large piece of material, it can be divided into small pieces using a tool.
Making a casting mold is an integral part of the preparatory work. To do this, it is necessary to make a metal box into which a mixture of gypsum and talc will be poured. It is first made from beeswax, which can be obtained from beekeepers. The model of the product is placed in a box and filled with the mixture. After the mass hardens, the mold is heated and the wax is completely melted out of it. Wax residues may cause defects on the product. During the heating process, remaining moisture evaporates from it. The mold is ready for low tide.
To get a shaped product, you need a casting mold
Fireproof laboratory crucible or asbestos melting mold
Melting silver is impossible without a fireproof vessel or crucible. A crucible is a container for heating, firing, and drying various materials. It usually has a conical or cylindrical shape. The melting mold of asbestos is one of its varieties.
Asbestos is a chemically resistant material that can withstand temperatures up to 1900 °C. If there is no crucible, you can take a spoon and cover it with asbestos sheets, and then with flux.
You can buy a crucible in a store from 100 rubles apiece. Choose those that can withstand temperatures of 1000 degrees. The crucible resource is usually enough for 50 melts.
Before starting work, it is best to place the asbestos under a fireproof container for additional protection. This way you can avoid fire hazards.
Forceps
To work, you need to purchase heat-resistant tongs or tweezers. They are used to grip a crucible to pour the molten precious metal into a prepared mold where it will solidify.
The cost of heat-resistant tools is from 350 rubles.
Melting silver at home
Metal spoon
You can make a mini-smelter from an ordinary spoon by covering it with asbestos sheets. Next, the spoon needs to be coated with flux, which is sodium tetraborate. This is necessary so that the precious metal does not react with air when melting.
Important! Sodium tetraborate is a pharmaceutical borax. It not only prevents oxidation, but also helps the liquid base flow over the sides of the crucible.
Melting charge
A mixture is a mixture of melted metal and borax.
In order for the precious metal to quickly transition from a solid to a fluid state, silver elements are first broken into small pieces. Then they are mixed with borax in a ratio of 10 to 1 part sodium tetraborate.
Pliers
You will need pliers to break the silver elements into smaller pieces. Another tool that is also suitable for this purpose is pliers.
Magnet
Silver alloys are compounds of precious metals with various impurities. To extract particles of iron alloy from the material, you need to use a magnet.
Silver with impurities
If the alloy is not cleaned in this way, then in the future the metal will heat up unevenly, and it will take longer to transition to the liquid state.
Powerful step-down transformer with an output voltage of 25 V
The transformer is used as the main element of the melting device.
Other metal remelting methods
- A significant amount of lunar metal can be smelted using a blowtorch. Accordingly, the work equipment (crucible with charge) will have to be placed in a fireclay clay pipe of larger diameter and wall thickness.
- At home, you can melt silver using an ordinary microwave oven, using a stand made of asbestos or other temperature-resistant material.
- To melt metal, you can use a special melting furnace, which you can purchase or build yourself. It is better to install homemade or factory-made installations separately in a garage or country house.
Melting scrap silver using various devices at home
So how do you melt silver? The algorithm of actions will be approximately the same for any method. The transition from one step to another must be carried out strictly in order.
- First, a melting pot is prepared, which is a crucible or spoon treated with pharmaceutical borax.
- Silver parts are loaded into the smelter.
- Now the materials are heated to a liquid state.
- The resulting liquid filling must be poured into a pre-prepared cast iron mold.
Important! On the eve of the process, it is better to separate the precious metal by degree of purity. Material from different samples will have different combustion temperatures.
Melting silver on a gas burner
Knowing at what temperature silver melts, you can begin the process itself. Home casting involves the following steps:
- Precious metal must have a high degree of purity to work. The ideal option is 999, 960, 925 markings.
- Prepare a crucible from fire-resistant materials.
- Pre-obtain a form for low tide. You can make it yourself or buy it in a specialty store.
- Metal that has been cleaned or broken into small particles can begin to be melted. The burner should be at a distance of 3-5 centimeters from the material.
- After the final transition of the precious metal into a liquid state, it must be poured into the prepared mold. This needs to be done as quickly as possible, but carefully. The base, ready for casting, resembles a drop of mercury. It should remain inside the mold until completely hardened.
- After crystallization of the precious metal, it must be removed from the mold, then placed under a stream of ice water. If the silver does not separate from the mold, after cooling it is removed by hand.
Important! When using the burner, you must carefully monitor the flame. It should be soft so that the flux does not fly apart.
Melting scrap silver
Melting in the microwave
This method is not only safe, but also the fastest. The oven power must be at least 700 W.
Technological process
- Typically, silver in products is found in the form of an alloy with other metals. Therefore, when melting, it is necessary to extract steel or iron particles from the joint using a magnet. This action will reduce the time for the metal to transition to a liquid state and ensure uniform heating of the metal.
- Next, you need to build a smelter made of asbestos sheets and consisting of rectangular parts that differ in size. The design is intended to serve as a crucible.
- To protect against oxygen entering the alloy, borax or flux is used. It is poured into a container that acts as a smelter. After heating the flux or borax to a thick, green mass, pieces of metal blanks are placed into it.
- At first, the pieces of metal turn red, then gradually begin to melt. If during the melting process the metal is covered with a cloudy film, then it has not begun to melt. To do this, you need to adjust the burner flame and increase the temperature.
- Liquid molten metal, distinguished by its bright silver color, is poured into a mold. If an attempt to melt or manufacture a product is unsuccessful, the process must be stopped, the material must first be cooled, and then the steps must be repeated from the very beginning.
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Precautions for smelting operations
Foundry processes require increased safety precautions. There should be no flammable substances near the isolated work area. You should not skimp on protective equipment; you should definitely purchase glasses with protective glass on a garter, an apron, gloves, and work clothes.
Clothing must cover the entire body, since even a drop of hot precious metal can burn a section of skin to the bone.
You can also purchase a fire extinguisher to prevent a fire.
Homemade silver smelting
Cleaning silver from impurities yourself
The procedure for removing impurities is called refining. Using refining you can clean:
- Scrap of high-grade precious metal products;
- Technical silver;
- Waste from electrical cleaning;
The refining process should take place in a room with a powerful hood or outside. Substances harmful to humans will be released into the air.
To clean silver from impurities, you can place the material inside a liter jar and fill it halfway with nitric acid. The reaction will be manifested by heat and a pronounced bitter odor.
You will need to wait until the essence has cooled completely. Next, a saline solution is added to the container. As the reaction progresses, the precious metal chloride will settle to the bottom.
Now you need to pour running water into the jar. When the sediment sinks to the bottom again, the surface water layer is drained. The action is repeated several times until the essence becomes completely transparent.
Important! For 100 g of processed material, 250-350 ml of each reagent are needed.
A fairly common cleaning method is electrolysis. This refining is based on the characteristics of a smooth electric current. Silver parts act as the anode, and a silver plate acts as the cathode.
For the electrolysis method you will need:
- DC transformer;
- Clamps;
- Vessel with electrolyte (silver dissolved in nitric acid);
How raw materials are processed
The raw materials for obtaining the substance can be scrap of precious metals, industrial waste, or mined ore. To extract the precious metal, the following processing steps are applied step by step:
- Grinding. Recycled raw materials are crushed to obtain a fine mass.
- Firing allows you to remove flammable debris from the composition.
- Centrifugation is the separation of molten silver from other metals except lead.
- Remelting. During the cooling process in the crucible, liquid lead is separated from the noble metal, which solidifies faster.
- Electrolytic processing. The precious metal, dissolved in nitric acid, is exposed to electricity, causing the anode to attract impurities and silver to crystallize around the cathode.
- Chemical treatment allows you to obtain a substance of 1000 samples. The noble metal is dissolved using sulfuric and hydrochloric acids and ferric chloride, precipitating it with zinc. Silver is released from the solution in the form of sand, which is washed and remelted.
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At what temperature does it melt?
Depending on the sample and alloy composition, the precious metal changes its melting point, which decreases in proportion to the mass fraction of the precious element in the alloy.
| 800 sample | 780–820 °C |
| 875 sample | 780–870 °C |
| 900 sample | 780–890 °C |
| 925 sample | 810–910 °C |
| 960 sample | 900–940 °C |
| 999 sample | 960 °C |
What metals are used in silver alloys, how do they change the melting point
In the jewelry industry, copper is used as a ligature component. The temperature of the alloy decreases in proportion to the sample.
Platinum is used as an alloy in the creation of high-precision instruments. The melting point of such a metal ranges from 1000 °C.
An alloy of silver and palladium is widely used in dentistry. At a sample of 820 and above, the melting point of such an alloy is 1100 °C, however, a further decrease in the sample also lowers the melting point.
In electronics, alloys of technical silver with cadmium and tin are used as solders. Their melting point can range from 400 to 850 °C.
Category: question-answer
Is it possible to mix silver of different grades for melting?
Expert opinion
Andrey Seleznev
Chemist-technologist, Volgograd
It must be taken into account that different samples will have individual melting points. It is much easier to melt silver of the same purity, because then the metal will react equally to all processes. It is recommended to clean it from the ligature in advance by chemical or electrolysis.
Is it legal to melt silver at home in the kitchen?
Expert opinion
Pribrezhny Gennady Valentinovich
Jeweler 6th category
Activities for processing scrap and waste of precious metals are subject to licensing in accordance with the legislation of the Russian Federation. Illegal mining may result in an administrative fine. Article 15.44 of the Code of Administrative Offenses states: the fine will be one or one and a half times the cost of the materials that are the subject of the offense.
If you try to sell the resulting bullion to buyers, you may face criminal liability.
Which silver sample melts the easiest?
Expert opinion
Pribrezhny Gennady Valentinovich
Jeweler 6th category
The lower the standard of the precious metal, the easier it will melt. For example, the melting point of 925 silver differs from 875 by 130 degrees upward. Of the most common markings, the lowest melting range is 800 - from 780 °C and above.
Can silver be melted down into elegant home decoration?
Expert opinion
Grishanov Mikhail Petrovich
Jeweler, director of the Grishanov and Co. workshop
You can buy or make your own mold for casting simple jewelry, for example, a simple ring or pendant. However, to make filigree items yourself requires not only special skills, but also specialized equipment.
Burner
The process of melting silver using a gas burner occurs in stages, namely:
- you need to choose high quality silver, it is best to consider 925 sterling silver; if the piece of silver is large, you need to split it into small pieces;
- to start melting, you should prepare a special crucible made of heat-resistant materials;
- be sure to create a mold for casting the product - you will need to combine 1 part gypsum and 7 parts sand, add a little water so that the mass acquires the consistency of thick sour cream; the prepared composition is poured into a separate container, then the object that needs to be cast is taken, lubricated with soap and lowered into the uncured gypsum mixture, waiting until the mass begins to harden;
- Now you can start melting the silver product using a burner; It is important to note that the flame source should only be directed at the product being melted;
- silver of a liquid consistency is poured into a mold and left until it cools completely;
- All that remains is to separate the finished product from the gypsum stone; If the product is firmly held at the base of the mold, you can use improvised means.
