Melting Gold In A Crucible- A Simple Guide

In metalworking and jewelry manufacturing, melting gold is a key operation. Because of its high temperature resistance and good chemical stability, graphite crucible has become a common container for melting gold. This article will explain in detail the preparation, process and safety of using it to melt gold.

Materials and equipment for melting gold with graphite crucible

Graphite crucible: High temperature resistance, stable nature, does not react with gold. Select the size according to the amount of gold to ensure the melting efficiency.

Furnace: Key heating equipment, resistance furnace temperature control, easy operation. Induction furnace heating fast, high efficiency but high cost. Select parameters such as power and temperature control accuracy as required.

Gold raw materials: To ensure the purity, you should clean and test the recovery first.

Flux: Such as borax, sodium carbonate, can reduce melting point, reduce oxidation. According to the amount of gold to determine the amount.

Other tools: Crucible clamp crucible, stirring rod evenly heated, protective supplies to ensure safety, electronic scale weight.

Preparation before melting gold in graphite crucible

Site cleaning

Select a well-ventilated, dry and free of inflammable and explosive materials for the gold melting operation. Clean up the debris in the site. And ensure that the operation space is spacious and clean, easy to place and operate the equipment. At the same time, ensure that there are good fire fighting facilities around the site, in case of a fire can be timely response.

Check the device

Carry out a comprehensive inspection of the furnace to check whether the power cord is damaged. Whether the connection is firm, and whether the furnace body is damaged or deformed. To check whether the temperature control system of the furnace is working normally, you can set a lower temperature for trial operation. To observe whether the temperature display is accurate and whether the heating element is heating normally.

Check whether the graphite crucible has cracks, damage and other defects. If there is a problem with the crucible, you should replace it in time to avoid leakage during the melting process, resulting in gold loss and safety accidents. Then wipe the inside and outside surfaces of the crucible with a clean cloth to remove dust and impurities.

Check whether the crucible pliers, stirring rod and other tools are in good condition. To ensure that their operation is flexible and can meet the needs of the melting process.

Gold weighing and preparation

Use an electronic scale to accurately weigh the required molten gold weight. Precisely control the amount of gold used according to subsequent processing needs. When weighing, you should place the electronic scale on a horizontal, stable table and calibrated. To ensure the accuracy of the weighing results.

If the gold raw material is lumpy or irregular shape, you can cut it or break it appropriately as needed. So that it is easier to put into the graphite crucible, and can be heated more quickly and evenly when melting. At the same time, place the prepared flux with the gold in a certain proportion. So that you can add it into the graphite crucible at the same time when loading.

Detailed explanation of melting process with graphite crucible

Charge into graphite crucible

Carefully place the prepared gold and flux into the graphite crucible. Be careful not to let gold and flux spill out of the crucible to avoid loss and pollution. When loading, you can put part of the gold in first, and then add the flux. And then you can cover the remaining gold on top, which helps the flux play a better role.

After loading, place the graphite crucible into the furnace smoothly. When placed, ensure that the crucible is centered in the furnace so that it is heated evenly.

Set furnace parameters

According to the melting point of gold and the actual melting demand, set the heating procedure of the furnace. Generally speaking, the melting point of gold is about 1064 ℃. But in the actual melting process, in order to improve the melting efficiency, the temperature is usually set slightly higher than the melting point. For example, you can set the temperature at about 1200 ℃ first, and then adjust it appropriately according to the melting situation.

At the same time, set the heating speed. The heating rate should not be too fast, otherwise it may cause the graphite crucible to break due to uneven heat. And may also aggravate the oxidation of the gold surface. Generally, you can control the heating rate at about 10-20 ℃ per minute.

Heat melting of gold in graphite crucible

Start the furnace and start heating according to the set parameters. During the heating process, you should observe the operation of the furnace and temperature changes closely. As the temperature rises, the gold gradually begins to soften and melt.

When the temperature reaches near the melting point of gold, gold will begin to appear liquid. At this time, the heating rate can be properly reduced to allow the gold to fully melt. Ensuring that the interior is also completely liquid. During the melting process, the color of gold will gradually change from golden yellow to a bright liquid metallic luster.

Key points in the melting process of gold in graphite crucible

Temperature monitoring

Accurate monitoring of temperature is key in the gold melting process. Use real-time monitoring to carry out using the temperature control system of the الفرن. And you can equip an independent thermometer as a backup monitoring means to ensure the accuracy of temperature data.

Pay attention to the changes in the state of gold at different temperatures. If the temperature is too high, the gold may become overly oxidized, affecting its purity and quality. If the temperature is too low, it may lead to incomplete melting. Once the temperature anomaly is found, you should adjust the parameters of the furnace in time.

Mixing skills in graphite crucible

In the gold melting process, timely stirring can make the gold heat more evenly. It can accelerate the melting process, and also help reduce oxidation. When the gold begins to melt, gently insert a stirring stick into the liquid gold and stir slowly in a certain direction.

Pay attention to the strength and depth when stirring. To avoid violent collision between the stirring rod and the inner wall of the graphite crucible, and damage the crucible. Mixing frequency should not be too high, generally every few minutes to stir once, each stirring time is about 1-2 minutes.

Safety precautions for using graphite crucible

High temperature protection

Wear professional high temperature protective gloves and glasses when operating. You should use gloves to prevent burns, and glasses to protect against high temperature radiation and splashing droplets. You should use the crucible pliers to take and put the graphite crucible. And the action is fast and accurate to reduce high temperature exposure.

Safe use of flux

When using the flux, ensure that the site is well ventilated, and exhaust fans can be installed to exhaust harmful gases. Avoid contact with skin and eyes. Rinse immediately and seek medical advice. Wear a mask and gloves when weighing.

الخاتمة

The use of graphite crucible to melt gold, from material equipment preparation, melting preparation, process control and safety attention, every link must not be lost. Careful operation and attention to detail can maximize the value of gold.