How to wash a crucible Steps to clean a crucible

How to clean the crucible

1. PT crucibles are mostly washed with HF, which can dissolve silicate residues. It also has a good cleaning effect on many other contaminants.

2. Al2O3 crucibles can be made with aqua regia.

and ammonia washed. <>

3. If the pollutant is carbon black.

or some organic matter, simply burn it at a high temperature in the air atmosphere. After the crucible is washed, it is best to burn it in a muffle furnace at a high temperature.

Key points to note: Aluminum crucibles are generally disposable because they are cheaper, softer and easier to deform.

The crucible is an important part of the chemical instrument, it is the melting and refining of metal liquids and solid-liquid heating and reaction containers, is the basis to ensure the smooth progress of chemical reactions.

Introduction to aqua regia

Aqua regia (Aqua regia

Also known as "royal acid."

Nitrohydrochloric acid". It is a very corrosive, yellowish mist liquid, which is a mixture of concentrated hydrochloric acid (HCL) and concentrated nitric acid (HNO) at a volume ratio of 3:1.

It is one of the few liquids that can dissolve gold (Au), and its name is due to its corrosive nature.

Aqua regia is generally used in the etching process and some detection and analysis processes, but some metal elements such as tantalum (Ta), silver (Ag), inorganic salts such as silver chloride, barium sulfate, the king of plastics in organic matter.

Polytetrafluoroethylene.

Candles and other high-grade alkanes, an important substance in the inorganic world - silicon (Si), are not corroded by aqua regia.

Aqua regia is highly perishable and has chlorine gas.

smell, so it must be used now.

Here are the general steps to clean a crucible:

1.Safety precautions: Ensure your own safety before cleaning the crucible. Wear personal protective equipment such as heat-resistant gloves and protective eyewear to avoid exposure to heat or chemicals.

2.Pre-treatment: If there is an attachment or residue on the crucible, first carefully scrape or shake it off to remove as much dirt as possible from the surface.

3.Warm water cleaning: Place the crucible in warm water and rinse the inner and outer surfaces of the crucible with warm running water. If there is stubborn dirt, it can be gently brushed with a soft-bristled brush.

4.Cleaner use (as needed): Appropriate cleaners can be used if needed. Select the appropriate cleaning agent according to the crucible material and the type of attachment, and follow the instructions for use of the cleaning agent.

5.Special stain treatment: For some stubborn stains, such as molten metal residue or coke, you can try using special cleaners, solvents, or slag removers. Please note that these handling methods may require special safety measures and operating procedures, please follow the instructions carefully.

6.Rinse thoroughly: Rinse the crucible thoroughly with clean running water, making sure to remove all detergent residue and dirt.

7.Dry or tumble dry: Place the crucible upside down in a well-ventilated area and allow it to dry naturally. If faster drying is required, you can use a low-temperature oven or gently dry with a soft paper towel.

8.Inspection and storage: After complete drying, inspect the inner and outer surfaces of the crucible to ensure that it is clean and free of dirt. The crucible is then properly stored to avoid damage or recontamination.

1. Pour out the ash material first, then put on rubber gloves, pour the amount of concentrated sulfuric acid that can cover the residue at the bottom of the crucible into the crucible (don't be afraid of acid if you do this, but you should standardize the operation and pay attention to safety), and then put it in a fume hood and heat it in an electric furnace for 20min.

2. After cooling, pour the concentrated sulfuric acid into the waste tank, rinse the crucible with water, and find that it is relatively clean. If there is not a small amount of colored parts, basically do not need to be treated, and the treatment is not clean, according to many experimental experience, the color that can not be cleaned up has little effect, so the treatment is relatively clean, drying, you can.

1. How to clean the nickel crucible: the cleaning method is related to the contaminants (sample residues). PT crucibles are mostly washed with HF, which can dissolve silicate residues. It also has a good cleaning effect on many other pollutants.

2. Al2O3 crucibles can be washed with aqua regia and ammonia.

3. If the stain is carbon black or some organic matter, simply burn it at a high temperature in the air atmosphere. After the crucible is washed, it is best to burn it in a muffle furnace at a high temperature.

The main components of the ceramic crucible are alumina and silicon dioxide, which can not be used for alkaline substances as flux melting, and the porcelain crucible can be cleaned with acid reagent, which has heat resistance, up to about 1200 degrees Celsius, and is a good container for calcining solid substances at high temperature.

Instrument cleaning method: use a porcelain crucible cleaning machine to clean the porcelain crucible after use. With the continuous update of cleaning equipment technology, there are countless types of cleaning equipment. Although cleaning equipment is easy to use and easy to operate, they have two drawbacks that cannot be ignored.

Air calcination cleaning: The porcelain crucible to be cleaned is placed in a high-temperature tube furnace and calcined in an air atmosphere. Since the carbon-loaded metal oxides in the early stage are prepared by high-temperature calcination, this method can only remove the carbon, and the metal oxides remain in the porcelain crucible and cannot be removed.

In addition, the air calcination method has the disadvantages of higher calcination temperature, longer time and higher energy consumption.

The hydrothermal method is to use aqueous solution as the reaction medium in a specially made closed reaction vessel, and create a high-temperature and high-pressure reaction environment by heating the reaction vessel, so that the insoluble or insoluble substances under conventional conditions can be dissolved. Using this method, the porcelain crucible can be thoroughly cleaned without leaving any impurities.

Step 1: the cleaning agent is added to the PTFE lining of the hydrothermal synthesis reactor, and the cleaning agent is a mixture of distilled water and nitric acid.

Step 2: Put the porcelain crucible to be washed into the PTFE lining containing the cleaning agent.

Step 3: Put the PTFE lining with the lid and put it into the hydrothermal synthesis reactor.

Step 4: Put the hydrothermal synthesis reactor into a blast drying oven, raise the temperature to 120 180 degrees Celsius, and clean the reaction.

Step 5: Cool down after the cleaning reaction.

Step 6: Take out the PTFE lining, pour out the solution in the PTFE lining, take out the porcelain crucible in the PTFE lining, wash the PTFE lining and porcelain crucible with water, and dry.

1. The cleaning of the mold temperature machine is mainly to clean up the dust and rust in the crucible and keep it clean.

2. Preheat the crucible of the mold temperature machine to about 80, not more than 100, brush the paint on its surface, and repeat it 2 to 3 times to obtain a tight, strong and uniform coating. Slow heat to 200/300 to dry. When the mold temperature machine melts the material for the first time, it should use a small piece of nozzle material to cushion the bottom, and if there is no nozzle material, the alloy ingot should be cut into small pieces to ensure that the alloy is in close contact with the pot wall.

Do not put the whole alloy ingot in the pot, resulting in little contact between the alloy and the wall of the pot, and the heat transfer effect is not good, which is difficult to melt and easy to cause the crucible to be partially heated and damage the crucible.

3. The die-casting temperature of aluminum alloy of the mold temperature machine is generally 620 -680, if the temperature of the alloy liquid is set high, it is easy to overburn the alloy liquid, which will aggravate the oxidation rate of the alloy liquid, so the working temperature of the furnace should be reduced as much as possible under the condition that it does not affect the product molding. The maximum temperature of the pot wall when the furnace of the mold temperature machine is working is more than 800, the strength drops sharply, and cracks may occur under a slight impact or load, and the pot wall should be gently slid down when feeding.

The method of cleaning is related to contaminants (sample residues).

1. PT crucibles are mostly washed with HF, which can dissolve silicate residues. It also has a good cleaning effect on many other contaminants.

2. Al2O3 crucibles can be washed with aqua regia and ammonia.

3. If the pollutant is carbon black or some organic matter, simply burn it at a high temperature in the air atmosphere.

After the crucible is washed, it is best to burn it in a muffle furnace at a high temperature.

Finally: aluminum crucibles are generally disposable because they are cheaper, softer and easier to deform.

The melting point of platinum is degrees, the heating temperature of platinum crucible should not exceed 1200 degrees, considering the temperature error, it is recommended to use it below 1150 degrees, when heating and burning, it should be carried out in the electric furnace or on the oxidation flame of the gas lamp, and the platinum crucible should not be heated in the reducing flame or the flame emitting black smoke. or expose the platinum vessel to the blue flame center in the flame to prevent the formation of platinum carbide. Oxides, hydroxides, barium oxides, sodium thiosulfate of molten alkali metals must not be heated in a platinum crucible.

Phosphorus and sulfur-containing substances, alkali metals such as nitrate, nitrite, chloride, cyanide and platinum form brittle platinum phosphide, platinum sulfide, etc. at high temperatures, and can attack platinum.

Sample compounds containing heavy metals, such as lead, bismuth, tin, antimony, arsenic, silver, mercury, copper, etc., should not be burned and heated in a platinum crucible, these heavy metals are easily reduced to metals and platinum alloys should not be in contact with any other metals when heated at high temperatures, and must be placed on platinum triangles or ceramics, clay, quartz and other materials, and halogens and substances that can decompose halogens shall not be processed in platinum dishes, such as aqua regia, bromine water, hydrochloric acid and oxidants such as chlorate, nitrate, permanganate, manganese dioxide, chromate, Mixtures such as nitrites and mixtures of halides and oxidants. Ferric chloride has a very significant erosive effect on platinum, after the platinum dish is used for a long time, there will be a thin layer of crystallization on the surface, which must be removed in time to prevent it from penetrating into the interior, and can be boiled in dilute hydrochloric acid or dilute nitric acid, hydrochloric acid, which should not contain nitric acid, nitrate, halogens and other oxidants.

If it cannot be cleaned with dilute acid, it is washed with potassium pyrophosphate, sodium carbonate or borax melt, and if there are still stains, or the surface is black, then moisten it with fine sand (preferably sea sand) without sharp edges and corners through 100 mesh and gently rub it to restore the surface to luster.

The above is excerpted from the Handbook of Analytical Chemistry.

Crucible Usage:

Ceramic containers containing solid, heat-resistant properties.

How to use: The crucible is a bowl-shaped container with a deep ceramic bottom. When there are solids to be heated over high fire, a crucible must be used. Because it can withstand high temperatures better than glassware.

Crucibles are usually used with crucible lids placed diagonally on the crucible to prevent heated objects from jumping out and to allow air to enter and exit freely for possible oxidation reactions. Because of its small bottom, the crucible generally needs to be placed on a mud triangle before it can be heated directly by fire. The crucible can be placed upright or obliquely on the mud triangle, and can be placed by itself according to the needs of the experiment.

Do not place the crucible on a cold metal table immediately after strong heat to prevent it from breaking due to the cold. It should not be placed on the wooden table immediately to avoid burning the table top or causing disasters. The correct way to do this is to leave it on a mud tripod to cool naturally, or to place it on a stone mesh to let it cool slowly.

Please use crucible pliers for the use of crucibles.

Main uses: 1) Evaporation, concentration or crystallization of solutions.

2) Burning solid matter.

Precautions for use:

1) Both instruments can be directly heated, and can not be quenched after heating, and they can be removed with crucible pliers (2) The crucible is placed on the mud tripod when heated.

3) When evaporating, stir and use waste heat to evaporate.