An Introduction to Zirconium Sheet: Properties and Applications

Introduction

Zirconium sheet is a versatile and highly sought-after material known for its exceptional properties and wide range of applications. With its remarkable corrosion resistance, excellent heat transfer capabilities, and inherent mechanical strength, zirconium sheet has become indispensable in numerous industries. In this article, we will delve into the properties of zirconium sheet and explore its various applications.

Exceptional Corrosion Resistance

One of the most impressive attributes of zirconium sheet is its outstanding corrosion resistance. Zirconium has a thin oxide layer that forms naturally on its surface, providing a protective barrier against aggressive chemicals, acids, and alkalis. This makes zirconium sheet particularly valuable in chemically demanding environments such as chemical processing plants, pharmaceutical manufacturing, and seawater desalination facilities. When exposed to corrosive substances, zirconium sheet remains unscathed, ensuring long-lasting performance and reliability.

Excellent Heat Transfer Capabilities

Another significant advantage of zirconium sheet lies in its excellent heat transfer capabilities. Zirconium exhibits high thermal conductivity, allowing efficient heat exchange between fluids or gases. This property makes zirconium sheet an ideal choice for heat exchangers in industries like petrochemicals, power generation, and refrigeration. By utilizing zirconium sheet in heat exchangers, manufacturers can enhance energy efficiency, reduce costs, and ensure optimal performance.

Mechanical Strength and Structural Integrity

In addition to its corrosion resistance and heat transfer properties, zirconium sheet possesses impressive mechanical strength and structural integrity. It has higher strength compared to other materials like stainless steel or aluminum, making it suitable for demanding applications. Zirconium sheet finds extensive use in aerospace industries, where its strength contributes to the manufacturing of lightweight but strong components. Moreover, this material is utilized in defense applications, providing the required durability to withstand extreme conditions in military equipment.

zirconium sheet

Nuclear Applications

Zirconium sheet has a vital role in nuclear applications, specifically in fuel cladding for nuclear reactors. The unique properties of zirconium make it an excellent choice for this purpose. It exhibits low neutron absorption, allowing neutrons to penetrate through the material without significant loss. Zirconium’s high melting point and exceptional corrosion resistance enable it to withstand the rigorous conditions within the reactor core, ensuring the safety and integrity of nuclear fuel rods.

Other Applications

The versatility of zirconium sheet extends beyond its primary uses. It is also employed in various other fields and industries. In the medical sector, zirconium sheet is gaining popularity for orthopedic and dental implants due to its biocompatibility and corrosion resistance. The electrical industry utilizes zirconium sheet in capacitors, connectors, and electrical contacts due to its advantageous electrical conductivity. Zirconium sheet is also used in the production of specialty chemicals, catalysts, and electrodes, benefitting from its chemical stability and catalytic properties.

Conclusion

Zirconium sheet stands as a remarkable material with its impressive properties and diverse range of applications. Its exceptional corrosion resistance, excellent heat transfer capabilities, and mechanical strength have made it essential in numerous industries. From chemically aggressive environments to nuclear power plants, from aerospace to medical applications, zirconium sheet continues to play a crucial role. With ongoing advancements in zirconium sheet technology and growing awareness of its benefits, we can expect this versatile material to find even more innovative applications in the future.

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The Versatile Metal: Zirconium’s Applications in the Chemical Industry

Zirconium is a versatile metal that is widely used in the chemical industry due to its excellent resistance to corrosion. In this article, we will explore some of the many applications of zirconium in the chemical industry.

Properties and Characteristics of Zirconium

Zirconium is a transition metal that is known for its high melting point, low thermal neutron cross-section, and exceptional corrosion resistance. Its atomic number is 40, and it has a silvery-gray color when in its pure form. Zirconium has several characteristics that make it well-suited for use in chemical processes, including:

  • Excellent corrosion resistance: Zirconium is highly resistant to corrosion, making it an ideal material for use in aggressive chemical environments.
  • Solubility: Zirconium is relatively insoluble in water and most common acids and bases, but can dissolve in hydrofluoric acid, which can be useful in certain chemical processes.
  • Oxidation resistance: Zirconium forms a protective oxide layer when exposed to air or water, which enhances its corrosion resistance.
  • Biocompatibility: Zirconium is biocompatible and is often used in medical implants and prosthetics.

Applications of Zirconium in the Chemical Industry

Zirconium has a wide range of applications in the chemical industry, including:

  • Manufacturing of pigments: Zirconium is used as a raw material to produce pigments such as zirconia and zirconium silicate, which are used in the manufacture of ceramics, glass, and tiles.
  • Corrosion-resistant equipment: Due to its exceptional corrosion resistance, zirconium is used in the manufacture of heat exchangers, reaction vessels, and other equipment that comes into contact with corrosive chemicals.
  • Catalysts: Zirconium-based catalysts are widely used in the production of various chemicals, including plastics, rubber, and pharmaceuticals.
  • Nuclear fuel cladding: Zirconium alloys are used as cladding materials for fuel rods in nuclear reactors due to their high strength, low thermal neutron cross-section, and excellent corrosion resistance.
  • Electronics: Zirconium compounds are used in the manufacture of capacitors, resistors, and other electronic components.

Safety Considerations

While zirconium is generally considered safe for use in the chemical industry, there are some safety considerations to keep in mind. These include:

  • Reactivity: Zirconium can react violently with certain chemicals, such as strong oxidizers like chlorine trifluoride or sodium chlorate. Workers should be trained on the safe handling of zirconium and its compounds.
  • Dust inhalation: Zirconium metal and some zirconium compounds can produce fine dust particles when processed or machined, which can be harmful if inhaled. Proper respiratory protection should be used when handling zirconium in powder form.
  • Radioactivity: Zirconium is not inherently radioactive, but it can become so if it is exposed to radiation in a nuclear reactor. Proper handling and disposal procedures must be followed for any zirconium-based materials that have become radioactive.

Conclusion

Zirconium is a versatile metal that has many important applications in the chemical industry due to its exceptional resistance to corrosion, ability to withstand high temperatures, and biocompatibility. Its use in manufacturing pigments, catalysts, corrosion-resistant equipment, nuclear fuel cladding, electronics, and more continues to make it an important material in modern industrial processes. As with any chemical, proper safety precautions must be taken when handling zirconium, but when used properly, it can contribute to safer, more efficient chemical processes.

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Exploring the Properties of Zirconium for Use in Nuclear Reactors

Zirconium is an important material used in the production of nuclear fuel rods for nuclear reactors. In this article, we will explore zirconium’s unique properties that make it an ideal choice for use in nuclear reactors, as well as some of the challenges and concerns associated with its use.

Physical and Chemical Properties of Zirconium Fuel Rods

Zirconium fuel rods are composed primarily of zirconium metal, which has several important physical and chemical properties that make it an ideal material for use in nuclear reactors. These include:

  • High melting point: Zirconium has a high melting point of 1855°C, which makes it able to withstand the extreme temperatures generated by nuclear fission reactions.
  • Low thermal neutron absorption: Zirconium has a low cross section for absorbing thermal neutrons, which are the neutrons that slow down as they collide with other atoms. This makes it an ideal material for use as cladding around fuel pellets, as it does not interfere with the nuclear reactions taking place inside the fuel pellets.
  • Excellent corrosion resistance: Zirconium is highly resistant to corrosion, particularly in high-temperature, high-pressure environments such as those found in nuclear reactors.
  • Good mechanical properties: Zirconium has good mechanical properties, including high strength, ductility, and toughness, which help to ensure the integrity and safety of the fuel rods.

Advantages of Using Zirconium as Nuclear Fuel

The use of zirconium as a nuclear fuel has several advantages, including:

  • High thermal conductivity: Zirconium has a high thermal conductivity, which helps to efficiently transfer heat away from the fuel pellets to the coolant in the reactor.
  • Low neutron absorption: As mentioned earlier, zirconium has a low cross section for absorbing thermal neutrons, which allows the neutrons to pass through the cladding and interact with the fuel pellets, resulting in sustained nuclear reactions.
  • Excellent corrosion resistance: Zirconium is highly resistant to corrosion, which is important in preventing the release of radioactive materials into the environment.
  • Readily available: Zirconium is abundant in the earth’s crust and is relatively easy to mine and process, making it an economically viable choice for use in nuclear reactors.

Disadvantages of Using Zirconium as Nuclear Fuel

However, there are also some disadvantages to using zirconium as nuclear fuel, including:

  • Potential for hydrogen buildup: When zirconium is exposed to water at high temperatures, it can react with the water to produce hydrogen gas, which can build up inside the fuel rods and potentially lead to explosions or other safety issues if not properly managed.
  • Radioactive waste: Like all materials used in nuclear reactors, zirconium fuel rods eventually become radioactive and must be properly disposed of once they are no longer usable. This can be a time-consuming and expensive process.
  • Regulatory concerns: The use of zirconium as nuclear fuel is subject to strict regulatory oversight to ensure the safety of workers, nearby communities, and the environment. Compliance with these regulations can be costly and time-consuming for nuclear power plant operators.

Safety Concerns and Regulations

Due to the potential hazards associated with the use of zirconium as nuclear fuel, there are several safety concerns and regulations in place to ensure the safe operation of nuclear reactors. These include:

  • Inspections and monitoring: Nuclear power plants are subject to regular inspections and monitoring by regulatory agencies to ensure compliance with safety standards.
  • Emergency preparedness plans: Nuclear power plants must have detailed emergency preparedness plans in place in case of an accident or other emergency situations.
  • Worker training and protection: Nuclear power plant workers must undergo extensive training on safety procedures and must be provided with appropriate protective gear and equipment when working with radioactive materials.

Conclusion

Zirconium is a unique and important material in the production of nuclear fuel rods. Its high melting point, low thermal neutron absorption, excellent corrosion resistance, and good mechanical properties make it an ideal choice for use in nuclear reactors. However, there are also some challenges and concerns associated with its use, including the potential for hydrogen buildup, radioactive waste, and regulatory compliance. As such, the use of zirconium as nuclear fuel is subject to strict safety regulations and oversight to ensure the safety of workers, nearby communities, and the environment.

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Preparation of Zirconium Dioxide by Wet Method and Fire Method

Zirconium dioxide is a high-temperature and corrosion-resistant ceramic material. It has three crystal structures, and its volume changes with crystal transformation:

1) When the temperature is lower than 1373K, it is a monoclinic crystal,

2) It is a tetragonal crystal at a temperature of 1373～2173K,

3) When the temperature is higher than 2173K, it is a cubic crystal.

In order to overcome the shortcomings of the unstable crystal form of zirconia, partially stabilized zirconia has been developed, and they have become important fine ceramic materials.

The industrial production methods of zirconia can be divided into the wet method and the fire method. The purity of the product obtained by the wet method can generally reach about 99%, but the production process is relatively long. The purity of the product obtained by the fire method is about 95% to 98%.

Zirconium dioxide is produced by the wet method of calcining zirconium oxychloride at high temperatures to decompose it into zirconium dioxide with a purity of 99.5%. It can also be prepared by dissolving zirconium oxychloride in water, precipitating with ammonia water, washing, drying, and calcining. High-purity zirconium dioxide can be produced using zirconium oxychloride purified by repeated recrystallization as raw material.

The fire method includes the electric melting method and the plasma metallurgy method. The electromelting method is to mix zircon and carbon evenly, melt in an electric arc furnace, silicon is removed in the gaseous form of silicon monoxide, and the produced zirconia is crushed and sized to obtain coarse zirconia. The plasma metallurgy method is to thermally dissociate zircon into zirconium dioxide and active silicon dioxide in the plasma area at a high temperature, then wash away the silicon dioxide in the dissociated products with hot lye to obtain zirconium dioxide.

zirconia powder

The method of producing products is divided into zirconia production and stabilized zirconia production process. Stabilized zirconia is used to produce stabilized zirconia for industrial refractory materials, and most of them are produced by electric melting. Adding carbon and calcium oxide as a stabilizer in the zircon electric melting process, while removing silicon, zirconia, and calcium oxide react to form a solid solution, and then crush and granulate to obtain stable zirconia.

Stabilized and partially stabilized zirconia used in fine ceramics is generally prepared by the wet method. The most mature and commonly used method is the neutralization precipitation method. Dissolve the purified zirconium oxychloride with pure water, filter to remove insoluble matter, adjust the concentration of zirconium in the solution, and add the required amount of dichloride, then filter, dry and calcinate. Calcined products can be crushed to obtain ultra-fine stable zirconia powder.

Partially stabilized zirconia is obtained by controlling the amount of stabilizer added so that it is not enough to achieve complete stability. Partially stabilized zirconia has high strength and thermal shock resistance and is widely used in structural ceramics.

With the rapid development of the fine ceramics industry, zirconia ultrafine powder with small particle size, high purity, and uniform composition is required to manufacture devices with high density, low shrinkage, and unique properties. For this reason, people have proposed new technologies and new processes for producing ultrafine zirconia powder, mainly including hydrolysis, hydrothermal synthesis, and preparation of organic zirconium compounds. These new technologies and processes have good prospects for industrial application.

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Application and Prospect Analysis of Zirconium

Zirconium is a metal material with superior physical and chemical characteristics. It is used in a variety of industrial, scientific, and technological applications. The following is an analysis of the uses and prospects of zirconium from different angles.

Zirconium Used in Nuclear Energy

Zirconium is one of the essential elements in the realm of nuclear energy due to its physical characteristics. Fuel rods and structural components for nuclear reactors can be manufactured with zirconium alloys. The high melting point, corrosion resistance, high strength, and high-temperature stability of zirconium alloys make them ideal materials for producing nuclear reactor fuel rods. Statistics show that every year, roughly 50 tons of zirconium alloys are used in the production of nuclear reactors worldwide.

Zirconium Used in Aerospace Industry

Zirconium is frequently utilized in the aerospace industry due to its superior mechanical qualities and strong temperature endurance. Zirconium alloys can be used to create components for aero engines such as blades, nozzles, and combustion chambers. Zirconium alloys can be utilized for a variety of components, including spacecraft hulls, turbines, and combustion chambers. They have exceptional qualities that can enhance spaceship performance, including lightweight, high strength, and high-temperature durability.

Zirconium Use in Medical Field

Zirconium is used extensively in the medical industry. Drugs can be radiolabeled using the zirconium isotope zirconium-89 for the detection and management of certain malignant disorders. Zirconium alloys have high strength, strong biocompatibility, and corrosion resistance, which can increase long-term durability and biological compatibility, and they can also be utilized to make artificial joints, dental implants, and other biomedical materials.

Zirconium Used in Chemical Industry

The chemical sector additionally employs extensive use of zirconium. Zirconium compounds are used in a variety of industries, including oxidants, antiseptics, catalyst supports, and catalysts. Because zirconium alloys offer great corrosion resistance, high-temperature stability, and long-term use in hostile chemical environments, they can also be utilized to make reactors, heat exchangers, reactors, and other equipment.

Zirconium Used in Electronics

Zirconium is also widely used in the field of electronics. Zirconium alloys and zirconates can both be used to create capacitors and battery electrodes, respectively. The primary areas of zirconium used in the electronics sector are nanotechnology and high-temperature superconducting materials. Zirconium can be used as an addition to boost the superconducting temperature and current density of high-temperature superconducting materials. Zirconium is also frequently utilized in nanotechnology and is capable of producing nanotubes, nanocrystals, and nanomaterials.

Zirconium Used in Metal Surface Coating

To stop corrosion and increase the hardness of metal surfaces, zirconium can be utilized in the production of surface coatings. Zirconium alloys can also be used to create metal coatings that are resistant to corrosion at high temperatures and have great corrosion resistance. Zirconium alloys are also perfect for producing drill bits, saw blades, and other tool materials due to their wear durability, and corrosion resistance.

Related reading: Where Zirconium is Used?

Conclusion

To sum up, zirconium has significant uses in the sectors of nuclear energy, aircraft, medical treatment, the chemical industry, electronics, and metal surface coating due to its exceptional physical and chemical qualities. The sustainable development of zirconium and the creation and use of ecologically friendly materials will also become popular trends as people’s awareness of environmental protection rises, further broadening the material’s potential uses.

Steps for Producing Zirconium Sulfate from Zircon

Zirconium sulfate is an important compound that has numerous industrial applications, such as in water treatment, cosmetics, and pharmaceuticals. The process of preparing zirconium sulfate from zircon involves several steps, including alkali decomposition, preparation of zirconium sulfate solution, and precipitation of acidic zirconium sulfate. This article will explore these steps in more detail, including the different methods of alkali decomposition, the preparation of zirconium sulfate solution, and the acid zirconium sulfate precipitation process.

Step 1: Alkali decomposition

There are three methods of alkali decomposition: sodium hydroxide fusion, sodium carbonate sintering, and lime sintering. The sodium hydroxide fusion method uses zircon and sodium hydroxide at a low temperature to achieve a high decomposition rate. The sodium carbonate sintering method involves sintering zircon and sodium carbonate at a high temperature and requires sulfuric acid for leaching. The lime sintering method uses zircon, limestone, and calcium chloride at a high temperature to achieve a moderate decomposition rate and requires hydrochloric acid or sulfuric acid for leaching. Each method has its advantages and disadvantages in terms of cost, efficiency, and process requirements.

Step 2 Preparation of zirconium sulfate solution

The alkali decomposition products of zircon obtained by washing with water and filtering are leached with sulfuric acid. During the leaching process, the zirconium in the alkali decomposition product turns into zirconium sulfate and goes into the solution, while the silicon turns into insoluble silicic acid. Sulfuric acid leaching is usually carried out in enameled reaction pots. First, a solution containing 50% H2SO4 is added to the reaction pot, heated to close to the boiling point, and then the required amount of alkali decomposition product is added while stirring. After the reaction, water is added to the specified total volume, then heated to close to the boiling point, and gelatin is added to thicken the silicic acid. The mixture is then filtered to remove silicon and other impurities. The concentration of sulfuric acid in the leaching solution is generally controlled at 2mol/L, and the leaching solution contains ZrO2100g/L, approximately 100g/L. This process is easy to operate, fast to filter, and produces a clear filtrate with a high zirconium leaching rate. It is also possible to use a calculated amount of concentrated sulfuric acid to react with the alkali decomposition product under stirring, followed by leaching with water. This method yields good leaching results, but the operation is more complicated.

Step 3: Acid zirconium sulfate precipitation

The solubility of zirconium in sulfuric acid solution depends on the acidity of the solution. Precipitation of zirconium sulfate crystals from zirconium sulfate solution generally adopts the method of evaporation and concentration. A good crystallization product can only be obtained by controlling the concentration and acidity of the evaporating liquid. Therefore, concentrated sulfuric acid is added in production to increase the acidity of the zirconium solution.

Conclusion

The preparation of zirconium sulfate from zircon is a complex process that involves several steps, including alkali decomposition, preparation of zirconium sulfate solution, and precipitation of acidic zirconium sulfate. Each step requires careful attention to detail and precise control of various process parameters to ensure a high-quality product. Despite its complexity, zirconium sulfate is an important compound with many industrial applications, and the preparation process outlined in this article is an essential part of its production.

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3 Alkaline Decomposition Methods for Preparation of Zirconium Sulfate

Zirconium and sulfuric acid can produce a variety of compounds, the most common ones being acidic zirconium sulfate and basic zirconium sulfate. Acidic zirconium sulfate, also known as zirconyl sulfuric acid, is widely used in industry, and its molecular formula is H2[ZrO(SO4)2]•3H2O or Zr(SO4)2•4H2O. The tetrahydrate of zirconium sulfate appears as hexagonal plate crystals, while the anhydrous form is a white powder. It is a main intermediate product of zirconium and can be used as a white leather tanning agent. The preparation of zirconium sulfate from zircon involves three steps: alkali decomposition, preparation of zirconium sulfate solution, and precipitation of acidic zirconium sulfate. This article focuses on explaining these three methods of alkali decomposition. Currently, there are three methods of alkali decomposition, namely the sodium hydroxide melting method, the sodium carbonate sintering method, and the lime sintering method.

Zirconium(IV) sulfate - Wikipedia

Sodium Hydroxide Fusion Method

The sodium hydroxide fusion method, also known as the alkali fusion method, involves adding zircon and sodium hydroxide to the reaction tank in a 1:1.3 ratio and reacting them at a temperature of 923-973K to form Na2ZrO3. The main reaction formula is ZrSO4+4NaOH=Na2ZrO3+Na2SiO3+2H2O, and the decomposition rate of zircon can reach about 99%. The alkali fusing material is then washed with water to remove soluble impurities such as excess alkali and sodium silicate. The resulting filter cake is sent for leaching to obtain a zirconium sulfate solution. The washing materials include sodium zirconate, sodium zirconium silicate, hydrated zirconia, and sodium titanate. The main features of this method are the low reaction temperature and the high decomposition rate of zirconium.

Sodium Carbonate Sintering Method.

Sodium carbonate sintering method, also known as the direct sintering method, involves putting zircon and sodium carbonate in a pan-type ball forming machine in a molar ratio of 1:3 to create pellets. The mixture is then sintered in a rotary kiln at 1373K, and the main reaction that takes place is:

ZrSiO4+3Na2CO3=Na2ZrO3+Na4SiO4+3CO2↑

After the firing process, the material is crushed and washed with water to eliminate soluble impurities such as sodium silicate. The resulting mixture is then filtered to obtain a filter cake, mainly comprising of sodium zirconate, which is later leached to produce a zirconium sulfate solution. Alternatively, zircon and sodium carbonate can be used in a molar ratio of 1:1.3. In this case, the primary sintering reaction is:

ZrSiO4+Na2CO3=Na2ZrSiO5+CO2↑

As observed from the reaction formula, the sintered product primarily consists of sodium silicon zirconate. The sintered product is then decomposed using sulfuric acid. During this process, zirconium produces zirconium sulfate and enters the solution, while silicon forms silicic acid, which can be effectively polymerized and removed during filtration. Although this method saves a significant amount of sodium carbonate, it consumes a considerable amount of acid and requires high reaction temperatures. The decomposition rate of zircon is approximately 95%.

Lime Sintering Method

The lime sintering method involves adding zircon and limestone (or chalk) in a molar ratio of 1:3, with an excess of 10% to 20% limestone. Then, calcium chloride with a mineral content of 5% is added, mixed evenly, and sent into a rotary kiln at a temperature of 1373-1473K for 4-5 hours. The decomposition rate of zircon is about 97%-98%. After sintering, the material is first washed with a cold solution containing 5% to 10% HCl to remove excess CaO, CaCl2, and most of Ca2SiO4. The generated colloidal silicic acid is also removed together with the solution. The resulting calcium zirconate is then leached with a solution containing 25% to 30% HCI at a temperature of 358-363K. Alternatively, sulfuric acid can be used for leaching. The biggest advantage of this method is that the decomposition agent is cheap and easy to obtain, but it has the disadvantage of high decomposition temperature and low decomposition rate.

Conclusion

In summary, zirconium sulfate is an important industrial material produced through alkali decomposition of zircon. The three primary methods of alkali decomposition are the sodium hydroxide fusion method, sodium carbonate sintering method, and lime sintering method. Each method has its advantages and disadvantages in terms of decomposition rate, reaction temperature, and cost of decomposition agents. Ultimately, the choice of method depends on the specific requirements of the production process.

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Does Zirconium Have Any Effect on Human Health?

Zirconia ceramics and jewelry made of zirconium are widely used in daily life, and it is generally believed that zirconium is not harmful to human health. However, some people suspect that zirconium in tiles can cause cancer.

It is possible for radioactive elements to cause malignant tumors, usually by inducing cell lesions, leading to leukemia, lymphoma, skin cancer and other blood cancers. As for the malignant tumor caused by excessive radioactivity of ceramic tiles, there are no such cases and related records in clinical experience and domestic and foreign case literature.

Adding zirconium silicate to ceramics is mainly used to increase the whiteness of ceramics. If you are still concerned about its safety, don’t blindly pursue whiteness when buying tiles.

does-zirconium-have-any-effect-on-human-health

How to Distinguish Zircon from Diamond?

Colorless and transparent zircon is a good substitute for diamonds after careful consideration. The refractive index of zircon is close to 2, and the dispersion is similar to that of the diamond. Therefore, from the appearance, zircon will also shine with colorful light, which is very similar to diamond. Before the advent of man-made diamonds, zircon was the best diamond substitute.

Zircon is very similar to diamond in appearance, but zircon is far from diamond in price. Because the two are not easy to distinguish, some unscrupulous merchants use zircon as a diamond to deceive consumers and make huge profits. So as consumers, how do we differentiate them?

Image titled Tell Cubic Zirconia from a Diamond Step 6

The main identification features of zircon are high refractive index, strong luster, high birefringence, high density, high dispersion, and typical spectral characteristics, etc., resulting in a very special optical phenomenon: When the polished zircon is observed with a magnifying glass, it can be seen from the top surface that there are obvious double shadows on the bottom surface and the ridge line. Because diamonds are “homogeneous”, there will never be a double shadow phenomenon, so zircons can be distinguished from real diamonds.

Diamond is a homogeneous body, completely black and hard under-crossed polarizers; while zircon appears as four bright and four dark under-crossed polarizers. Diamonds are lipophilic, and a ballpoint pen can easily leave uninterrupted marks on the surface of the diamond. Of course, this mark can be easily wiped off. Zircon is not lipophilic, and a ballpoint pen cannot leave uninterrupted marks on its surface. Sharpness marks.

Hydrogenation Method: A Method for Preparing Zirconium Powder

Introduction

Hydrogenation is one of the main methods for producing zirconium powder in the industry. This method refers to the process of preparing metal zirconium powder by hydrogenating and dehydrogenating bulk metal zirconium. The product metal zirconium powder prepared by the method has a purity of more than 98%, and can be mainly used in powder metallurgy additives and pyrotechnic industries.

Reaction Process

Zirconium has good plasticity and is difficult to be crushed by mechanical means, but it can be transformed into a brittle intermediate product zirconium hydride for further processing.

When hydrogen is sufficient, zirconium reacts with hydrogen to form zirconium hydride, releasing a lot of heat. The reaction formula is:

Zr+H2→ZrH2

When dehydrogenated by heating under a vacuum, zirconium hydride decomposes into metallic zirconium. The reaction formula is:

ZrH2→Zr+H2

Zirconium hydride is a non-stoichiometric substance in the interstitial phase, and the hydrogen content (x) can vary from zero to 2 with different process conditions. When x>1.65, it is brittle zirconium hydride, and the brittleness increases with the increase of x value. Zirconium powder can be obtained by grinding the brittle zirconium hydride finely and then dehydrogenating it in a high-temperature vacuum.

According to the requirements for product purity, the bulk zirconium raw materials used for hydrogenation include sponge zirconium, zirconium ingots, or zirconium scraps in zirconium processing; in order to ensure product quality, high-purity hydrogen must be used; the hydrogenation process should be in a well-airtight environment in a stainless steel reaction tank.

Specific steps are as follows:

  • After the reaction tank is filled, vacuum until the pressure is lower than 0.1Pa, heat to a temperature of 873-973K, and stop vacuuming.
  • Introduce high-purity hydrogen for hydrogenation. Sponge zirconium and zirconium shavings have a large specific surface area, which can be met by hydrogenation once. The dense zirconium with a large size needs to undergo multiple hydrogenation and dehydrogenation treatments at high temperatures to make it fully burst to ensure that the product is easy to grind. As long as the temperature and pressure of the hydrogenation process are well controlled, zirconium hydride with the desired hydrogen content can be obtained.
  • After the hydrogenation reaction is completed, continue to pass hydrogen to cool to room temperature, then extract the residual hydrogen, slowly fill in argon or air, and start unloading.
  • Put block zirconium hydride into a grinding tank, add the appropriate amount of water or ethanol to grind, then sieve and dry to get zirconium hydride powder. This zirconium hydride powder can be used as a heat-burning agent or powder metallurgy additive.
  • Spread the dried zirconium hydride powder into a thin layer in a tray, then put it into a dehydrogenation tank, and heat it slowly under a vacuum. Zirconium hydride releases a large amount of hydrogen at a temperature of about 673K.
  • When the temperature rises to 873-973K and the vacuum pressure reaches below 0.1Pa again, cool the dehydrogenation tank to room temperature, slowly pour water or ethanol into it, and then unload.
  • After grinding, sieving, and drying, the product zirconium powder is obtained.

Advantages

The zirconium powder produced by this method can maintain the content of metal impurities at the level of the raw material while ensuring that it is not contaminated by the container, and the content of some volatile impurities will be reduced, but the content of gas impurities, especially oxygen, will be reduced. Increase. The average particle size of zirconium powder can reach 5-10μm, and finer particle sizes can be separated through liquid countercurrent classification. The finer the particle size of the zirconium powder, the higher the oxygen content.

Attention

Zirconium powder, zirconium hydride powder, and hydrogen are flammable and explosive substances, and fine zirconium powder can oxidize, spontaneously ignite or explode even at room temperature. Explosion-proof measures should be taken during the production, storage, transportation, and use of zirconium powder to ensure safety.

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4 Methods for Making Metal Zirconium

Zirconium and its alloys not only have good machinability, moderate mechanical strength, and high corrosion resistance, but also have a low neutron cross-section. In the nuclear energy industry, they are widely used as structural materials for water reactors. Zirconium widely exists in zircon, so most methods of preparing metal Zr use zircon as a raw material for extracting zircon. This article will mainly introduce four methods for purifying zirconium.

Metal Thermal Reduction Method

The reducing agents used in the thermal reduction method are mainly calcium and magnesium.

(1) Calcithermic reduction

Using ZrO2 as raw material and calcium as a reducing agent, the reduction reaction is carried out at 1273-1373K under vacuum. The reduction product is a powdery mixture of Zr, CaCl2, CaO, and Ca, which can be pickled, washed with water, filtered, dried, and sieved to obtain metal zirconium.

(2) Magnesium reduction method

The magnesium reduction method mainly includes steps such as the preparation of zirconium tetrachloride, purification, magnesium reduction, and vacuum distillation. Chloride zirconium dioxide or zircon sand to obtain zirconium tetrachloride, purify, remove impurities such as SiCl4, TiCl4, AlCl3, FeCl3, and then use molten magnesium to reduce ZrCl4 to obtain a mixture of metal zirconium, magnesium, and magnesium chloride, and finally, Zirconium metal is obtained by distillation and purification.

Zirconium Ores

Hydrodehydrogenation

This method uses the reversible absorption characteristics of zirconium to hydrogen to prepare zirconium powder. At a certain temperature, zirconium and zirconium alloys absorb hydrogen to form hydrides or solid solutions. When reaching a certain level, the material will produce microcracks, become brittle, and contain a lot of hydrogen. Such powder is called zirconium hydride powder. Zirconium hydride powder is dehydrogenated under high temperature and vacuum conditions to obtain zirconium powder. After years of improvement and promotion, this method has become the main method for producing zirconium powder.

Molten Salt Electrolysis

Metals or alloys that are difficult to electrodeposit in an aqueous solution usually use molten salt electrodeposition. Insoluble anodes are usually used, stainless steel or other refractory metals are used as cathodes, and molten salts of electrodeposited metals and alkali metal chlorides or fluorides are used as electrolytes. During the electrolytic reduction process, they are decomposed by the electrolytic metal molten salts. and deposited at the cathode.

Direct Electro-Deoxidation Method

The direct electro-deoxidation method uses a single or mixed metal oxide as the raw material, presses it into a block as the cathode, removes the oxygen in the cathode by electrolytic deoxidation, and obtains a metal element or alloy with low impurity content in a high-temperature molten salt, also known as FFC Law. The metals successfully prepared by the FFC method include Zr, Hf, Be, Mg, Ca, Ba, V, Nb, W, Fe, and Cu.

Among the four methods, the magnesium reduction method and hydrogenation-dehydrogenation method are the main production methods in the industry.

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