Smelting copper from ore at home. How to melt copper and its alloys at home

Many owners face the problem of how to melt copper at home. Some people want to cast copper products, others have accumulated copper scrap, which takes up a lot of space, and it is a pity to throw it away. Those who believe that this is a complex process and that it will not be possible to melt copper at home can be reassured. Ancient people knew how to do this several centuries BC, without having any special devices for this.

People started smelting copper BC.

The melting point of pure copper is 1083 °C.

Among metals that are widely used in industry, this is an average value. Tin, lead, magnesium, zinc, and aluminum have a significantly lower melting point; for silver and gold it is 960 °C and 1063 °C, respectively. Iron has a melting point of 1539 °C. Therefore, copper, silver and gold can be melted in iron vessels. The addition of tin, lead and zinc can significantly reduce the melting point of copper, but this produces not pure copper, but its alloys - bronze and brass.

Before melting begins, you need to prepare:

1. steel tongs,
2. hook for collecting oxide film from the surface of the melt,
3. form for filling.

The hook can be made from steel wire. The form can be any steel container; you can prepare a depression in the ground, as our ancestors did. For artistic casting you will need a special mold.

Melting in a muffle furnace

• Household muffle furnaces can be purchased in specialized stores. Modern ovens are equipped with temperature regulators and an inspection window, and can be vertically or horizontally loaded. An average quality oven can maintain temperatures up to 2000°C, while a professional oven can maintain temperatures up to 3000°C. It can melt not only copper, but also iron. But it should be taken into account that at a temperature of 2560 °C the copper melt begins to boil. After cooling, the ingot will have a porous surface, which promotes rapid oxidation and destruction. Such an ingot has an unpresentable appearance; it lacks the characteristic copper luster.
• Regardless of the smelting method, copper scrap must be crushed. This will shorten the process time and guarantee that the melt will be homogeneous.
• Crushed copper scrap is poured into a crucible, the crucible is placed in a muffle furnace preheated above 1083 °C.
• After making sure that the copper has melted, the crucible is removed from the furnace with tongs and the oxide film that always forms on the surface of the melt is removed with a hook. After this, the melt should be immediately poured into the mold.

It is not worth purchasing an expensive muffle furnace just for one melt. Copper can be melted in other ways.

Melting using homemade devices

You can melt copper using a gas torch.

Some car enthusiasts have homemade forges in their garages that can be used to melt metals. If you couldn’t find a forge, you can make it yourself.

• Supports are installed on the ground, for example, sand-lime bricks, and a steel mesh with small cells is placed on them.
• A layer of charcoal is poured onto the mesh and set on fire. To get a high temperature, you need to increase the air flow. The easiest way to do this is with a vacuum cleaner running « blowing”, directing a stream of air to the place where the coal is burning.
• All that remains is to place the crucible on the burning coals and wait for the copper to melt. The melt comes into contact with atmospheric oxygen, so an oxide film is actively formed, which must be constantly removed. You can sprinkle the surface of the melt with small coals or ash from them. Slag is formed, which is then easily separated.

Copper alloys bronze and brass can be melted using an autogenous gas torch or a blowtorch with a flame twist attachment. The flame should heat the crucible evenly from below.

Copper products invariably attract attention. Various decorative items, souvenirs and simply beautiful and unusual things are made from copper. This metal is loved by many craftsmen. And someone uses it to create some useful part. Most often, pure red copper is used, as well as its alloys: brass and bronze. If you also decide to make something out of copper, then you will have to melt this metal. But how to melt copper at home?

Available means and course of action

To implement this process, you will need:

• ordinary horn;
• crucible;
• crucible tongs;
• steel wire hook;
• muffle stove;
• charcoal;
• mold;
• vacuum cleaner.

You need to act in the following order.

On a note

When you decide to melt copper, keep in mind that the forge, if necessary, can be replaced with a blowtorch or autogen. Crucibles must be made of ceramics or clay. The muffle furnace provides the opportunity to obtain temperatures of 1083 °C for copper, 930-1140 °C for bronze, 880-950 °C for brass. In order to increase the temperature, more air must be blown into the forge. A simple blowing vacuum cleaner and a compressor are suitable for these purposes. It is important that the vacuum cleaner hose has a metal tip. A thin stream of air can be obtained if the tip hole is narrowed.

Due to the fact that the melting point of copper is quite low, this metal was one of the first that ancient people began to use to make various tools, dishes, jewelry and weapons. Copper nuggets or copper ore could be melted over a fire, which is what our distant ancestors actually did.

Despite its active use by mankind since ancient times, copper is not the most common natural metal. In this respect, it is significantly inferior to the other elements and occupies only 23rd place in their series.

How our ancestors smelted copper

Thanks to the low temperature of 1083 degrees Celsius, our distant ancestors not only successfully extracted pure metal from ore, but also produced various alloys based on it. To obtain such alloys, copper was heated and brought to a liquid molten state. Then tin was simply added to such a melt or its reduction was performed on the surface of molten copper, for which tin-containing ore (cassiterite) was used. Using this technology, bronze was obtained, an alloy with high strength, which was used to make weapons.

What processes occur when copper melts

Typically, the melting temperatures of copper and alloys obtained on its basis are different. At , which has a lower melting point, bronze is obtained with a melting point of 930–1140 degrees Celsius. And an alloy of copper and zinc (brass) melts at 900–10500 Celsius.

In all metals, the same processes occur during the melting process. When a sufficient amount of heat is received during heating, the crystal lattice of the metal begins to collapse. At the moment when it goes into a molten state, its temperature does not increase, although the process of transferring heat to it by heating does not stop. The temperature of the metal begins to rise again only when it has completely turned into a molten state.

When cooling, the opposite process occurs: first the temperature drops sharply, then for some time it stops at a constant level. After all the metal has passed into the solid phase, the temperature begins to decrease again until it cools completely.

Both melting and reverse crystallization of copper are associated with the specific heat parameter. This parameter characterizes the specific amount of heat that is required to convert a metal from a solid to a liquid state. When a metal crystallizes, this parameter characterizes the amount of heat it gives off when cooling.

A phase diagram showing the dependence of the state of the metal on temperature helps to learn more about the melting of copper. Such diagrams, which can be drawn up for any metals, help to study their properties, determine the temperatures at which they radically change their properties and current state.

In addition to the melting point, copper also has a boiling point, at which the molten metal begins to release bubbles filled with gas. In fact, no boiling of copper occurs, it’s just that this process looks very similar to it. It can be brought to this state by heating it to a temperature of 2560 degrees.

As is clear from the above, it is the low melting point of copper that can be called one of the main reasons that today we can use this metal, which has many unique characteristics.

Copper products have become widespread not only in industry, but also in everyday life. This gives home craftsmen a reason to think about how to independently change the quality of the material for the further production of metal objects. Copper smelting is a special technology that ensures its transition from solid to liquid under the influence of high temperatures.

Main characteristics of copper

The metal is easy to process. Our ancestors knew about its unique properties, as evidenced by historical information and archaeological finds. In nature, it is found both in compounds and in its native form. The surface of copper is soft, yellowish-brown in color. When in contact with air, it becomes covered with an oxide film. The technical characteristics of copper are as follows:

• It ranks second after silver in electrical and thermal conductivity.
• Low melting point: for pure copper it is 1083 degrees, for copper alloys - from 930 to 1140 degrees.
• At a temperature of 2560 degrees the material begins to boil.
• Copper is diamagnetic.
• When selecting scrap for recycling, it is important to remember that electrical copper is the purest - without impurities.
• Alloys of bronze and brass, from which many rare items are made, may contain toxic substances, such as arsenic.

Special care is required with such substances.

Copper is a beautiful material. Products made from it look luxurious and noble. This property attracts the attention of many home craftsmen.

Characteristics of copper smelting methods

Copper smelting at home and in production is the same. The process of changing state is carried out under the influence of increasing temperature. With enough heat, the metal structure of the object is destroyed. This effect can be achieved in several ways.

What does a muffle furnace consist of?

Casting using a laboratory muffle furnace, which has an adjustable heating temperature. This is a pretty simple method. The raw materials are pre-crushed into pieces. The smaller they are, the faster the melting will be.

The prepared material is placed in a graphite crucible and placed in a preheated oven. The mold for pouring must have a melting point higher than that of copper. The mass-produced heating device is equipped with a special window that allows you to monitor the technological process.

When the copper reaches a liquid state, the crucible is removed from the furnace using iron tongs. Using a wire hook, the oxide film is removed from the surface of the molten metal to the edges of the crucible. After the manipulations have been completed, the liquid consistency is carefully poured into a pre-prepared container.

Gas-burner

Copper smelting is also carried out using a gas torch. If you don’t have a crucible furnace, a hand-held portable gas burner is quite suitable. It must be placed under the bottom of the container with metal and ensure that the flame completely covers the bottom.

The method allows the material to quickly oxidize, as it involves close contact with air. To prevent the formation of a thick oxide film, the molten mass is sprinkled with crushed charcoal.

Casting copper using a blowtorch occurs in the same way as with a gas burner. The method is applicable for low-melting metals.

Horn

You can melt copper or its alloys with a forge. To do this, place a crucible with crushed metal on well-heated charcoal. To speed up the process, use a home vacuum cleaner turned on in blowing mode.

The pipe should be of small diameter with an iron tip, since the plastic will melt under the influence of high temperature. The method is ideal for those people who regularly do metal casting in large volumes.

Microwave

A powerful microwave oven with a modified design will help melt copper. To do this, remove the rotating tray. A muffle furnace is made from refractory bricks, into which the starting material is placed. The device is necessary to increase the heat-saving properties of raw materials and protect equipment elements from overheating.

Pure copper is difficult to melt because it has poor fluidity in liquid form. Experts do not recommend making small and complex parts from such material. Multicomponent compounds based on brass, tin or zinc, which do not require high temperatures, are suitable for this.

Independent copper smelting

For many people, smelting copper and making all kinds of products from it is an exciting hobby. Those who want to devote their free time to melting metal need to prepare the following devices for work:

• muffle furnace;
• pure raw materials;
• heat-resistant crucible;
• fireproof stand;
• steel wire hook;
• tongs for removing the crucible from the oven;
• personal protective equipment: suit, glasses, gloves.

Actions are performed according to the instructions:

1. They put on a special suit.
2. The raw materials are crushed and placed in a crucible.
3. Place in the oven and set the desired temperature. The metal should not be allowed to boil.
4. When the set temperature is reached, open the door, grab the crucible with tongs, remove it from the oven, and place it on a refractory stand.
5. Using a steel hook, the oxide film formed as a result of melting is moved to the edges of the container.
6. The liquid copper mass is poured into a special container and cooled.
7. In powerful muffle furnaces, red copper and all kinds of alloys can be melted.

Melting with a torch

It should be remembered that a nitrogen environment is important during melting. For low-melting copper alloys, brass or some brands of bronze, you can use a regular gas burner. For this you will need:

• feedstock;
• special forms;
• tongs for removing metal from a hot working surface;
• high pressure burner running on gas;
• protective equipment: suit, glasses, gloves.

The alloy melting technology is as follows:

1. The raw materials are highly crushed. This can be done using a file, turning the material into sawdust.
2. Place in a special form made of heat-resistant material.
3. Wear a protective suit, goggles, and thick gloves.
4. Light the burner.
5. The heating device is directed with free movements along the body of the container. To achieve quick results, the flame should touch the surface with the blue tip. In this place of the torch the temperature is highest.
6. After the solid has melted, the crucible is grabbed with tongs.
7. The liquid mass is poured into the desired form.

If you don't have a gas burner, you can use an ordinary blowtorch.

When casting non-ferrous alloys, every craftsman must remember safety precautions:

• The room where work is carried out must have good ventilation.
• To avoid burns, it is necessary to work in personal protective equipment.

Optimal air temperature, acceptable air humidity, cleanliness of the workplace, low concentration of harmful atmospheric substances, good illumination of the space are factors that help to avoid injuries.

Copper products can be very beautiful, and it is tempting to make something copper with your own hands. To do this, the metal must be melted. In foundry, for the most part, three main varieties of this metal are used: red pure copper and its alloys: bronze and brass.

You will need

• Crucible
• Crucible tongs
• Muffle furnace
• Charcoal
• Household vacuum cleaner
• Iron wire hook
• Form

Instructions

1. Place pieces of metal into the crucible. Place the crucible in the muffle furnace. Set the heating regulator to the required position. You can monitor the melting of the metal through the oven window, which is on the door. During melting, an oxide film forms on the surface of the metal.

2. When the desired temperature is reached and the metal has melted, open the door and grab the crucible with tongs. Move the oxide film to the side using an iron wire hook. Pour the melt into the mold prepared in advance. If the muffle furnace is of sufficient power, with its support it is possible to melt all kinds of copper alloys and red copper itself.

3. If there is no muffle furnace, you can melt the copper with an autogen, directing the flame upward from the bottom of the crucible. In this case, melting will occur with excellent air access. To protect the metal from intense oxidation, it is recommended to sprinkle its surface with a layer of crushed charcoal.

4. Yellow copper (brass) and fusible varieties of bronze can be melted with a blowtorch. The principle of melting is the same as when using autogen. The flame should cover the crucible as much as possible.

5. If there is neither an autogen nor a blowtorch, you can use a simple forge. In this case, place the crucible on a layer of charcoal. To increase the combustion temperature of coal, use forced air injection into the combustion zone. A blow-out household vacuum cleaner is suitable for this. The vacuum cleaner hose must strictly have a metal tip. The tip hole can be narrowed to obtain a larger thin stream of air.

If you need to melt metal for some purpose, you will be faced with a number of problems that you can solve and still carry out this procedure with your own hands. Let's say melt copper not as difficult as many other materials. And if you want, it’s absolutely possible to do it yourself.

Instructions

1. Discover a method to achieve temperatures higher than 1083 degrees Celsius. This temperature is needed in order to copper started to melt. Don't believe stories about how people managed to melt copper on a fire in a tin can or a piece of copper wire on a spoon, using only a lighter. Even if their stories are real, one can only conclude that it was not copper .

2. You are allowed to use a blast furnace if there is one where you live or if you have a chance to use it. Before renting a stove, make sure that it can heat up to the temperature you need and that it can be adjusted, because it is impossible to copper began to boil. You must be able to balance between temperature changes.

3. Try to build a smelting furnace at home yourself. You can make a melting furnace at home from scrap materials. Schemes for making such stoves are available throughout the specialized forum. The most common design is created from a used fire extinguisher. If you prefer this option, then saw off the head of the fire extinguisher and attach a closing lid. Treat the inside with clay and install a melting element; buy one that is available in specialized stores.

4. Remember that the mold into which the molten copper will be poured must have a higher melting point than the mold itself. copper .

5. Do not forget about the nitrogen environment, which must be created for successful melting; otherwise, you may simply waste the material.

Video on the topic

To melt copper However, like any other metal, it is better to use special equipment and work under the supervision of a master. But if circumstances forced you to start smelting metal at home, then make a special smelting furnace.

Instructions

1. A furnace for melting metal at home was developed by the scientist metallurgist E.Ya. Khomutov. For the base of the furnace, take an ordinary refractory pipe 300 mm long.

2. Make two holes (locking) at both ends of the pipe to attach the nichrome thread. The nichrome thread is a heating element; it must be attached together with a piece of cord, one that will protect the turns of the wire when winding.

3. Using the formula L=RxS, calculate the length of the thread, where the resistance of the heating element –R, S is the cross-section of the wire (nichrome); resistivity of nichrome –р and equal to 1.2; desired length - L.

4. Wrap the wire together with the cord in the form of a spiral and coat it with liquid glass. After this, remove the conductor and wrap the spiral with asbestos.

5. Make a temperature sensor. Take chromel and alumel wire and twist them together. Attach the wire coming from the transformer (latr) to one end of the twist. Set the transformer regulator to zero division.

6. Take a dielectric surface and add graphite powder and borax (proportion 5/1). Connect another wire from the transformer to the soldering point. It is indicated in the figure.

7. On the left is a temperature sensor. 1). transformer (latr), 2).on the 1st contact terminal, 3). from latr 2nd contact, 4.5). chromel and alumel wire, 6). a cup made of a substance that does not conduct current well, 7). composition (mixture) of borax and graphite, 8). twisting of 2 wires (soldered).

8. Apply current for a few seconds. A melt ball should appear at the contact site. Mount the working part of the thermocouple into the furnace lid and connect it to a millivolt, the one rated at 500 millivolts.

9. Calibrate the scale again; the melting point of various metals can serve as a guide. Carry out this operation in the finished oven. Make the top cover of the oven and the bottom from clay (fireclay). The oven can be equipped with a viewing window made of special glass.

10. 1) asbestos thermal insulation 2). clay pipe, 3). nichrome spiral, 4). cover (top), 5). output of nichrome thread (wire), 6). thermocouples, 7). millivoltmeter, under. If the charge will be loaded easily into the furnace itself, and not into the crucibles, then coat the inside of the furnace with graphite paste. Mix the paste on liquid glass. When working with such an oven, follow safety precautions.

Brass is a multi-component alloy of copper with some other alloying elements. Products made of brass have many useful properties and are often used in the manufacture of a wide variety of designs in the practice of a home craftsman. One of the methods of primary processing of brass is melting.

You will need

• - muffle furnace;
• - blowtorch;
• - gas-burner;
• – crucible;
• - charcoal;
• – iron wire;
• – a mold for smelting metal.

Instructions

1. Prepare a muffle furnace in which the brass will be melted and a special vessel made of refractory material (crucible) into which the starting material will be easily placed. For comfortable handling of the crucible, you will need special metal tongs and a fireproof stand. Provide excellent ventilation in the room where work will be carried out.

2. Place the crushed mass of brass in a heat-resistant crucible. It is desirable that the pieces of metal are not too huge; this will reduce melting time. Place the crucible in the muffle furnace. Using the temperature regulator, set the required value (the melting point of brass reaches 880-950 degrees). Turn on the oven. If necessary, monitor the melting process through the window located in the door of the muffle furnace.

3. After the brass has completely melted, carefully open the door, observing safety precautions, and remove the crucible, grabbing it with tongs. A film of oxides forms on the surface of the molten metal; remove it with a piece of iron wire. Pour the molten metal into a previously prepared casting mold.

4. If there is no stationary equipment for melting metals, use heat with a gas torch or a traditional blowtorch. Place the burner in a stable position with the flame pointing upward, and then secure it. Place a heat-resistant crucible with brass on an iron wire stand.

5. Turn on the burner or blowtorch. Set the flame power so that it covers the entire lower surface of the fireproof vessel. Because melting will occur with a vigorous flow of air, the process will be accompanied by powerful oxidation of the metal. To reduce oxidation, sprinkle a generous layer of crushed charcoal on the brass.

The reformation of wood into coal is carried out with the help of the process of pyrolysis, which means the decomposition of organic compounds as a result of their destruction under the influence of high temperature. Wood decomposition is carried out in an oxygen-free gas environment, in a retort. During the pyrolysis process, vapor gases are released, which are discharged through the pipe. After this, gas is separated from the liquid in the device. Today there is a huge number of units prepared for the thermal decomposition of wood. If you have the necessary materials, you can make a stove for making charcoal with your own hands.

You will need

• – ceramic brick;
• – fireclay brick;
• – clay and sand;
• – iron sheet;
• – boost fan;
• – cast iron grates;
• – lever thermostat;
• - doors.

Instructions

1. Before starting to assemble such equipment, the entire master draws up a detailed diagram of the future furnace. When making the device independently, it is better to use a ready-made circuit.

2. The perimeter of the pyrolysis furnace is laid out from ceramic bricks, which should not have cracks or chips. Internal partitions are laid using fireclay bricks. To prepare the binding solution, clay and clean sand are used.

3. The firebox can be made of ceramic and fireclay bricks. It is preferable to use fireclay bricks, because they can better withstand high temperatures, which cannot be avoided when burning fuel.

4. The fuel tank is divided into two segments: a loading section and a section for combustion of gases released during the pyrolysis process. For the best combustion of volatile substances, secondary air is supplied to this section, while the primary air passes from top to bottom.

5. Cast iron grates are installed in the firebox. In this case, it is necessary to make small gaps, because the gratings expand when heated. The fire doors are secured with special “ears”. To make them, you can use wire or sheet iron.

6. Later, you need to install doors designed to regulate the air supply and clean the stove from ash. At the same stage, stove valves are installed, with the help of which the draft in the stove is regulated. Due to the fact that the firebox design has large aerodynamic resistance, it is necessary to install a fan used to supply forced draft.

7. The charcoal stove has such advantages as the ability to recycle waste from the wood industry, the absence of emissions of harmful substances into the environment, ease of maintenance and operation, safety and durability. With so many advantages, there is one drawback, one that is impossible not to notice. It involves the need for careful thermal insulation of the pipe, because at low temperatures, condensate in the pipe can freeze, and this will lead to a decrease in its cross-section.

Helpful advice
The production of a charcoal stove should be carried out using only high-quality materials. It is desirable to have experience in welding work.

Video on the topic

Note!
The muffle furnace must allow the following temperatures to be obtained: for melting copper – 1083°C, for melting bronze – 930-1140°C, for melting brass – 880-950°C. Red copper is viscous. It is of little use for thin castings. Brass is most suitable for these purposes. The lighter the brass, the more fusible it is. It is not recommended to remelt old bronze of unknown origin, since it may contain a huge amount of arsenic. The forge is an open furnace with a hood in which charcoal is burned. To increase the temperature, additional air is blown into the forge with the support of bellows or a compressor.

Helpful advice
Clay and ceramic crucibles are used to melt copper. Instead of a forge, you can use an autogen or a blowtorch.