The production process of sponge zirconium involves multi-step chemical reduction and separation technology, mainly including the following core processes:

1、 Basic process: Crowell method

1. Raw material processing

Zirconia tetrachloride (ZrCl ₄) is generated through chlorination reaction using zircon sand or zirconia as raw materials. The specific steps include:

Zirconia sand mixed with carbon powder is compressed and reacted in a high-temperature chlorination furnace to produce crude zirconium tetrachloride.

The crude product is purified by distillation to remove impurities such as aluminum, silicon, and titanium.

2. Magnesium thermal reduction

Zirconium tetrachloride reacts with molten magnesium under argon protection to produce sponge zirconium and magnesium chloride:

The reaction temperature is 800-900 ℃, and the pressure needs to be controlled at 9.8-19.6kPa to achieve efficient reduction.

3. Vacuum distillation

The reduced product is subjected to high-temperature vacuum distillation to remove residual magnesium and magnesium chloride, ultimately yielding porous sponge like metallic zirconium.

2、 Special process for nuclear grade sponge zirconium: zirconium hafnium separation

1. Necessity

Nuclear reactors require the use of sponge zirconium with hafnium content below 100ppm, therefore zirconium (Zr) and hafnium (Hf) need to be separated.

2. Separation method

Extraction method: Separation is carried out by utilizing the difference in solubility of zirconium hafnium compounds in hydrochloric acid or nitric acid systems.

Gas phase separation method: Based on the difference in volatility between zirconium tetrachloride and hafnium tetrachloride, separation is achieved through distillation.

Boiling chlorination method: Zirconia sand is directly chlorinated to generate zirconium tetrachloride solution, and zirconium hafnium is separated by hydrochloric acid system to simultaneously produce nuclear grade zirconia and hafnium oxide.

3、 Modern process improvement

1. Boiling chlorination method

Using a fluidized bed reactor to directly chloride zircon sand shortens the process and reduces costs. For example, 10000 tons of zirconium tetrachloride solution can produce approximately 1700 tons of nuclear grade sponge zirconium.

2. Three tank reduction distillation combined process

Through the linkage design of sublimation tanks and dual reduction tanks, continuous production can be achieved, single furnace capacity can be increased, and the distillation cycle can be shortened to 40-50 hours.

4、 Summary of Process Flow

Raw material pretreatment → Chlorination to produce ZrCl ₄ → Zirconium hafnium separation (additional steps required for nuclear grade) → Magnesium thermal reduction → Vacuum distillation → Sponge zirconium finished product

5、 Costs and by-products

Cost of nuclear grade sponge zirconium: Zirconia sand accounts for over 60% of the raw material cost.

By product hafnium oxide: 60 tons of hafnium oxide can be produced per 10000 tons of ZrCl ₄, significantly improving economic benefits.

6、 Application Fields

Sponge zirconium is mainly used for nuclear reactor fuel cladding, aerospace high-temperature alloys, chemical corrosion-resistant equipment, etc. Nuclear grade products require extremely high purity.