Preparation of Tantalum Metal Powder

Preparation of Tantalum Metal Powder

Preparation methods of tantalum

Smelting method: Tantalum and niobium ore is often accompanied by a variety of metals, and the main steps of tantalum smelting are decomposition of the concentrate, purification, and separation of tantalum and niobium to produce pure compounds of tantalum and niobium, and finally the metal.

Preparation of Tantalum

Ore decomposition can be used hydrofluoric acid decomposition method, sodium hydroxide melting method and chlorination method, etc. Separation of tantalum and niobium can use a solvent extraction method, step-by-step crystallization method, and ion exchange method.

Separation: Firstly, the tantalum-niobium iron ore concentrate is decomposed with hydrofluoric acid and sulfuric acid tantalum and niobium are dissolved in the leaching solution as fluorotantalic acid and fluoronobotic acid, while the associated elements such as iron, manganese, titanium, tungsten, and silicon are also dissolved in the leaching solution, forming a strongly acidic solution with a very complex composition.

The tantalum-niobium leach solution is extracted with methyl isobutyl ketone and extracted into the organic phase at the same time, and the organic phase is washed with a sulfuric acid solution to obtain the pure organic phase containing tantalum-niobium and the extracted residue combined, which contains trace tantalum-niobium and impurity elements, and is a strongly acidic solution, which can be recovered comprehensively.

The pure organic phase containing tantalum-niobium is back-extracted with a dilute sulfuric acid solution to obtain the organic phase containing tantalum. Niobium and a small amount of tantalum enter the aqueous phase and then the tantalum is extracted with methyl isobutyl ketone to obtain a pure niobium-containing solution.

The pure organic phase containing tantalum is then back-extracted with water to obtain a pure tantalum-containing solution. The organic phase after the reverse tantalum extraction is returned to the extraction cycle.

Pure tantalum fluoride solution or pure niobium fluoride solution reacts with potassium fluoride or potassium chloride to form potassium tantalum fluoride (K₂TaF₇) and potassium niobium fluoride (K₂NbF₇) crystals, respectively, and can also react with ammonium hydroxide to form tantalum hydroxide or niobium hydroxide precipitates. Tantalum or niobium hydroxide is calcined at 900~1000°C to produce tantalum or niobium oxide.

Preparation of tantalum.

①Tantalum metal powder can be produced by the thermal reduction of metal (sodium thermal reduction) method. The reduction of potassium fluorotantalate with sodium metal in an inert atmosphere: K2TaF7+5Na─→Ta+5NaF+2KF. The reaction is carried out in a stainless steel tank, and the reduction reaction is rapidly completed when the temperature is heated to 900℃. The tantalum powder made by this method is irregular in particle shape and fine in size, which is suitable for making tantalum capacitors.

Tantalum metal powder can also be made by electrolysis of molten salt: using the molten salt of potassium fluorotantalate, potassium fluoride, and potassium chloride mixture as the electrolyte to dissolve tantalum pentoxide (Ta2O5) in it, and electrolysis at 750℃, tantalum powder with a purity of 99.8~99.9% can be obtained.

②Tantalum metal can also be obtained by reducing Ta2O5 with carbon heat. Reduction is generally carried out in two steps: first, a certain ratio of Ta2O5 and carbon mixture in a hydrogen atmosphere at 1800 ~ 2000 ℃ to make tantalum carbide (TaC), and then TaC and Ta2O5 in a certain ratio of the mixture of vacuum reduction into tantalum metal.

Tantalum metal can also be produced by thermal decomposition or hydrogen reduction of tantalum chloride. Dense tantalum metal can be prepared by vacuum arc, electron beam, plasma beam melting, or powder metallurgy. High-purity tantalum single crystals are produced by crucible-free electron-beam regional melting.

The Ultimate Guide to Tantalum

The Ultimate Guide to Tantalum

Tantalum, a metallic element, is found mainly in tantalite and is symbiotic with niobium. Tantalum is moderately hard, ductile, and can be drawn into thin foil in the form of filaments. Its coefficient of thermal expansion is very small. Tantalum has excellent chemical properties and is extremely resistant to corrosion.

tracing tantalum

Although tantalum is highly resistant to corrosion, its corrosion resistance is due to the generation of a stable protective film of tantalum pentoxide (Ta2O5) on the surface. It does not react to hydrochloric acid or concentrated nitric acid, either under cold or hot conditions. It can be used to make evaporating vessels, etc. It can also be used as electrodes for electronic tubes, rectifiers, and electrolytic capacitors. It is also used in medical treatment to make thin sheets or threads to mend damaged tissues.

 

Chemical symbol Ta, gray metal, in the periodic table belongs to the VB group, atomic number 73, atomic weight 180.9479, body-centered cubic crystal, common chemical compound valence +5.

Tantalum was discovered by the Swedish chemist A.G. Ekeberg in 1802 and named tantalum after the Greek mythological figure Tantalus (Tantalus). 1903, the German chemist W. von Bolton prepared the first plastic metal tantalum for use as filament material. 1940, large-capacity tantalum capacitors appeared and were widely used in military communications.

In 1940, large-capacity tantalum capacitors appeared and were widely used in military communications. During the Second World War, the demand for tantalum increased dramatically, and after the 1950s, the demand for tantalum rose year by year due to its expanding applications in the capacitor, high-temperature alloy, chemical, and atomic energy industries, promoting the development of research and production of tantalum extraction processes.

The hardness of tantalum is low and correlates with the oxygen content; ordinary pure tantalum, in its annealed state, has a Vickers hardness of only 140 HV. It has a melting point of 2995°C and ranks fifth among the monomers, after carbon, tungsten, rhenium, and osmium. Tantalum is ductile and can be drawn into thin foils of the filament type. Its coefficient of thermal expansion is very small. It expands by only 6.6 parts per million per degree Celsius. In addition, it is very ductile, more so than copper.

 

Tantalum Chemical properties.

Tantalum also has excellent chemical properties and is extremely resistant to corrosion, not reacting to hydrochloric acid, concentrated nitric acid or “aqua regia” under both cold and hot conditions. However, tantalum can be corroded in hot concentrated sulfuric acid. Below 150°C, tantalum will not be corroded by concentrated sulfuric acid, but will only react above this temperature. At 250 degrees, the rate of corrosion increased to 0.116 mm per year, and at 300 degrees, the rate of corrosion was accelerated, and the surface was corroded by 1.368 mm after 1 year of immersion.

In the fuming sulfuric acid (containing 15% SO3) corrosion rate is more serious than in concentrated sulfuric acid, soaked in the solution at 130 degrees for 1 year, the surface is corroded by a thickness of 15.6 mm.

Tantalum is also corroded by phosphoric acid at high temperatures, but the reaction generally occurs at 150 degrees or more, and the surface is corroded by 20 mm when immersed in 85% phosphoric acid at 250 degrees for 1 year. In addition, tantalum can be rapidly dissolved in a mixture of hydrofluoric acid and nitric acid, and can also be dissolved in hydrofluoric acid. But tantalum is more afraid of strong bases.

In a caustic soda solution with a concentration of 40% at 110 degrees, tantalum will be dissolved rapidly, and in a potassium hydroxide solution with the same concentration, it will be dissolved rapidly for as long as 100 degrees.

Except for the above-mentioned cases, general inorganic salts generally cannot corrode tantalum below 150 degrees. Experiments have shown that at room temperature, tantalum does not react to alkaline solutions, chlorine gas, bromine water, dilute sulfuric acid, and many other agents, but only to hydrofluoric acid and hot concentrated sulfuric acid. This is a relatively rare occurrence among metals.

 

Tantalum has properties that make it very versatile. In equipment for the production of various inorganic acids, tantalum can be used as a replacement for stainless steel, with a life expectancy several dozen times longer than that of stainless steel.

In addition, in the chemical, electronic and electrical industries, tantalum can replace the tasks that used to be undertaken by the precious metal platinum, making the costs required much lower. Tantalum is manufactured into capacitors equipped into military equipment.

The United States has an exceptionally developed military industry and is the world’s largest arms exporter. Half of the world’s tantalum production is used in the production of tantalum capacitors, and the U.S. Department of Defense Logistics Agency is the largest owner of tantalum, having at one time bought out one-third of the world’s tantalum powder.

 

 

Tantalum is one of the rare metal mineral resources and is a strategic raw material indispensable for the development of the electronics industry and space technology.

 

Tantalum and niobium have similar physicochemical properties and are therefore co-occurring in minerals in nature. The classification of tantalum or niobium ore is mainly based on the content of tantalum and niobium in the mineral, which is called niobium ore when the niobium content is high and tantalum ore when the tantalum content is high.

Niobium is mainly used in the manufacture of carbon steel, super alloys, high-strength low-alloy steel, stainless steel, heat-resistant steel and alloy steel; tantalum is mainly used in the production of electronic primary devices and alloys.

Tantalum and niobium minerals are complex in form and chemical composition, which in addition to tantalum and niobium, often also contain rare earth metals, titanium, zirconium, tungsten, uranium, thorium, and tin.

The main minerals of tantalum are tantalite [(Fe, Mn)(Ta, Nb)2O6], heavy tantalite (FeTa2O6), fine crystal [(Na, Ca)Ta2O6(O, OH, F)], and black rare gold ore [(Y, Ca, Ce, U, Th)(Nb, Ta, Ti)2O6], etc. The waste residue of tin refining contains tantalum, which is also an important resource of tantalum.

 

Can the Metal “Tantalum” be Used for Rings?

Can the Metal “Tantalum” be Used for Rings?

Can the metal “tantalum” be used for rings?

Yes, it can.

Tantalum is extremely resistant to corrosion and does not react to hydrochloric acid, concentrated nitric acid, or aqua regia in either cold or hot conditions.

tantalum rings

Tantalum’s pro-biological properties make it medically useful for making thin sheets or threads to mend damaged tissue. It is also harmless to the human body when made into rings and jewelry, and can be worn without worry.

Tantalum itself is harmless to humans and is as biophilic as silver, titanium, niobium, and other metals. However, tantalum and niobium may be mixed with rare earth elements during the smelting and extraction process, resulting in a little radioactivity, but pure tantalum is very safe.

Tantalum and niobium -a symbol of love?

Niobium and tantalum are in the same group in the periodic table and have very similar physical and chemical properties. In nature, they are often “inseparable”, like a pair of “twins”. When niobium and tantalum were discovered in the early 19th century, they were thought to be one element, and it was only after about 42 years that they were separated for the first time by chemical analysis, and it became clear that they were two different metallic elements.

Tantalum (Ta) niobium (Nb) are high melting point (tantalum 2996 ° C, niobium 2468 ° C), high boiling point (tantalum 5427 °C, niobium 5127 °C) rare metals, the appearance of steel-like, gray-white luster, powder dark gray, with gas absorption, corrosion resistance, superconductivity, unipolar conductivity and high strength at high temperatures, and other characteristics.

Therefore, the current tantalum niobium new material applications related to high-tech industrial fields include electronics, precision ceramics, and precision glass industry; electro-acoustic optical devices; cemented carbide, astronautics, and electronic energy industry; biomedical engineering; superconductivity industry; special steel and other industries.

Niobium-tantalum has good resistance to physiological corrosion and biocompatibility and does not interact with body tissues, so it is often used in the manufacture of bone plates, skull plate bone screws, dental implant roots, surgical appliances, etc. Tantalum is also known as a “biophilic metal” because it replaces bone in the human body with tantalum strips on which muscles can grow.

This is why they are also known as a “pro-biological metal”. Therefore, there are no allergies when using them for rings, and the price is better. Because tantalum is almost twice as dense as niobium, a tantalum ring of the same size will be more textured, darker in color, and more expensive than a niobium ring.

Because they have always coexisted in nature, we can also define them as a good brother or a loving couple, if you want to buy a pair of rings you can consider buying one each of tantalum and niobium, which has a better meaning!

Why is Tantalum So Expensive?

Why is Tantalum So Expensive?

Because of the characteristics of tantalum such as good cold working and welding performance, tantalum has been used in electronics, semiconductor, chemical, machinery, aerospace, medical, and other industries.

tantalum metal

Why is Tantalum So Expensive?

Tantalum is a metal element with atomic number 73 and the chemical symbol Ta, the element corresponds to the steel gray metal, which has extremely high corrosion resistance, both in cold and hot conditions, and does not react to hydrochloric acid, concentrated nitric acid and “aqua regia”.

Tantalum is mainly found in tantalite and is symbiotic with niobium. Tantalum is moderately hard, ductile and can be drawn into thin foils of the filament type. Its coefficient of thermal expansion is very small.

Tantalum has very high chemical properties and is extremely resistant to corrosion. It can be used to make evaporating vessels, etc. It can also be used to make electrodes for electronic tubes, rectifiers and electrolytic capacitors. It is used medically to make thin sheets or threads to mend damaged tissue. Although tantalum is highly resistant to corrosion, its resistance to corrosion is due to the generation of a stable protective film of tantalum pentoxide (TaO) on its surface.

Smelting: Tantalum-niobium ores are often accompanied by a variety of metals, and the main steps in tantalum smelting are decomposition of the concentrate, purification and separation of tantalum and niobium to produce pure compounds of tantalum and niobium for the metal. Ore decomposition can be used hydrofluoric acid decomposition method, sodium hydroxide melting method and chlorination method, etc. Tantalum and niobium separation can be used solvent extraction method [commonly used extractants are methyl isobutyl ketone (MIBK), tributyl phosphate (TBP), secoctanol and acetamide, etc.], step-by-step crystallization method and ion exchange method.

Separation: First, the tantalum-niobium iron ore concentrate with hydrofluoric acid and sulfuric acid decomposition of tantalum and niobium is fluorotantalic acid and fluoronobotic acid dissolved in the leaching solution, while iron, manganese, titanium, tungsten, silicon and other associated elements are also dissolved in the leaching solution, forming a very complex composition of strong acidic solution. The tantalum-niobium leach solution is extracted with methyl isobutyl ketone and extracted into the organic phase at the same time. The pure organic phase containing tantalum-niobium is back-extracted with dilute sulfuric acid solution to obtain the organic phase containing tantalum.

Niobium and a small amount of tantalum enter the aqueous phase and then the tantalum is extracted with methyl isobutyl ketone to obtain a pure niobium-containing solution. The pure tantalum-containing organic phase is back-extracted with water to obtain a pure tantalum-containing solution.

The organic phase after the reverse extraction of tantalum is returned to the extraction cycle. Pure tantalum fluoride solution or pure niobium fluoride solution reacts with potassium fluoride or potassium chloride to form potassium tantalum fluoride (KTaF) and potassium niobium fluoride (KNbF) crystals, respectively, and can also react with ammonium hydroxide to form tantalum or niobium hydroxide precipitates.
Tantalum or niobium hydroxide is calcined at 900~1000°C to produce tantalum or niobium oxide.

Preparation of tantalum

Tantalum metal powder can be produced by the thermal reduction of metal (sodium thermal reduction) method. The reduction of potassium fluorotantalate with sodium metal in an inert atmosphere: K2TaF7+5Na─→Ta+5NaF+2KF. The reaction is carried out in a stainless steel tank, and the reduction reaction is completed rapidly when the temperature is heated to 900°C. The tantalum powder made by this method is irregular in particle shape and fine in size, which is suitable for making tantalum capacitors.

Tantalum metal powder can also be made by electrolysis of molten salt: using the molten salt of potassium fluorotantalate, potassium fluoride and potassium chloride mixture as the electrolyte to dissolve tantalum pentoxide (Ta2O5) in it, and electrolysis at 750℃, tantalum powder of 99.8~99.9% purity can be obtained.

Reduction of Ta2O5 with carbon heat can also be obtained from tantalum metal.

Reduction is generally carried out in two steps: first, a certain ratio of Ta2O5 and carbon mixture in the hydrogen atmosphere at 1800 ~ 2000 ℃ to make tantalum carbide (TaC), and then TaC and Ta2O5 in a certain ratio of the mixture of vacuum reduction into tantalum metal. Tantalum metal can also be produced by thermal decomposition or hydrogen reduction of tantalum chloride.

Dense tantalum metal can be prepared by vacuum arc, electron beam, plasma beam melting or powder metallurgy. High-purity tantalum single crystals are produced by crucible-free electron-beam regional melting.

Tantalum is a metallic element with an atomic number of 73 and the chemical symbol Ta, which corresponds to a steel-gray metal with extremely high resistance to corrosion, both in cold and hot conditions, and does not react to hydrochloric acid, concentrated nitric acid or “aqua regia”.

Tantalum is mainly found in tantalite, which is symbiotic with niobium. Tantalum is moderately hard, ductile and can be drawn into thin foil in the form of filaments. Its coefficient of thermal expansion is very small. Tantalum has very high chemical properties and is extremely resistant to corrosion. It can be used to make evaporating vessels, etc. It can also be used to make electrodes for electronic tubes, rectifiers and electrolytic capacitors.

It is used medically to make thin sheets or threads to mend damaged tissue. Although tantalum is highly resistant to corrosion, its resistance to corrosion is due to the generation of a stable protective film of tantalum pentoxide (TaO) on its surface.