Expansion characteristics and experimental analysis of vermiculite

Vermiculite is a natural mineral that can expand into a porous structure after high temperature roasting, and is widely used in horticulture, construction, industrial adsorption and other fields. The expansion characteristics of vermiculite are closely related to its primary particle size, and the expansion times and final properties of vermiculite with different particle size after roasting show

 

Introduction to vermiculite

Vermiculite is a natural mineral that can expand into a porous structure after high temperature roasting, and is widely used in horticulture, construction, industrial adsorption and other fields. The expansion characteristics of vermiculite are closely related to its primary particle size, and the expansion times and final properties of vermiculite with different particle size after roasting show significant differences.

 

Vermiculite roasting process

The expansion effect of vermiculite depends on the calcination temperature, time and primary particle size. During the roasting process, vermiculite expands at high temperatures and forms a lightweight, porous structure. The change of expansion ratio is affected by the primary vermiculite particle size, and the different particle size of vermiculite shows different expansion amplitude under the same roasting condition.

 

Analysis of expansion ratio of primary vermiculite with different particle size

According to the experimental data, the larger the particle size of primary vermiculite, the larger the expansion ratio after roasting. The following is the expansion ratio of primary vermiculite with different particle sizes in the roasting process:

Particle size 0.3-1mm: The expansion ratio of primary vermiculite after roasting in this particle size range is usually 5-7 times. The smaller particles will expand into more delicate expanded vermiculite when calcination, which is suitable for horticultural soil improvement where lighter, higher permeability and water retention are required.

Particle size 1-3mm: The expansion ratio of vermiculite after roasting in this particle size range is usually 7-8 times. Medium-size vermiculite has a balanced expansion effect and is suitable for a wide range of industrial and construction applications, such as lightweight building materials and insulation materials.

Particle size 1.5-3.5mm: The larger particle size of primary vermiculite usually expands 6-15 times, and the expansion times increase with the increase of particle size. This kind of vermiculite has the most significant expansion effect under high temperature roasting, and is suitable for special industrial uses such as horticulture, sound insulation, adsorption and fireproof materials that require larger particles.

 

 

The relationship between vermiculite size and expansion ratio

1. The larger the particle size, the larger the expansion ratio: The experimental results show that the particle size of primary vermiculite is positively correlated with its expansion ratio. Larger grain size vermiculite can expand better during roasting, forming a lighter and more porous structure, so its expansion ratio of smaller grain vermiculite is higher.

2. The range of expansion times: the expansion times of different grain sizes of vermiculite after roasting fluctuate within a certain range:

Small grain vermiculite (0.3-1mm) has a small expansion, usually 5-7 times;

The expansion of medium-size vermiculite (1-3mm) is moderate, usually 7-8 times;

Large-grain vermiculite (1.5-3.5mm) has a large expansion, usually ranging from 6-15 times.

Adapt to different application needs: vermiculite with different expansion multiples is suitable for different industry needs. Small grain vermiculite is more suitable for horticultural fields, providing lightweight, breathable, water-retaining soil improvement materials; Medium size vermiculite is widely used in building insulation and sound insulation materials. Large grain vermiculite is commonly used for special purposes such as horticulture, industrial adsorption, fire prevention and heat insulation.

 

 

Sand content and roasting process

During the roasting process, the sand content of vermiculite will change, especially during high temperature roasting, and some impurities (such as sand particles) may be removed. The change of sand content of vermiculite with different particle size is also different:

Small grain vermiculite (0.3-1mm) reduces the sand content significantly after roasting, usually removing 10%-15% of the sand particles.

The sand content of medium-size vermiculite (1-3mm) decreased less, by about 5%-8%.

Large grain vermiculite (1.5-3.5mm) due to the large particle size, its sand content decreases more slowly, usually by 2%-5%.

 

 

Conclusion

1. Expansion ratio is directly related to particle size: vermiculite with larger particle size has higher expansion ratio, which is suitable for industrial and construction applications with higher expansion ratio requirements.

2. The roasting temperature is closely related to the expansion effect: the most ideal expansion effect usually appears between 800°C and 1200°C, and too high a temperature may lead to a decline in the expansion effect of vermiculite.

3. Select the appropriate particle size and expansion multiple for different needs: vermiculite with different particle sizes is suitable for different application scenarios, and select the appropriate particle size and expansion multiple to achieve the best performance.

 

 

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