Drying of pure silica powder

Our customer, a French leader in high precision optical compounds, needed to find a solution to dry ultra-pure silica powder, which is a very complex product to process

Customer needs

As a leader in high precision optical compounds, our client is used to provide high quality products for different industries.


The company needed to dry ultra-pure silica in order to manufacture high tech optical systems used in products like the lenses of large telescopes, or optical fibers.

Main constraints

The challenge of the drying process is to preserve the perfect purity of the silica. To do so, the product must be dried in an air tight environment to protect it from any atmospheric pollution or alteration. The question was how to dry the product by evaporating the water it contains in a closed system?


The first solution that come to mind to solve the problem is to use filtered hot air to heat and dry the silica powder. But this solution includes very expensive filters that must be changed regularly. Moreover, the treated product is really powdery once dried. That’s why SAIREM designed a custom microwave solution to dry the powder.

Solution proposed

To solve the customer issue,  SAIREM designed a custom microwave drying system, completed by a polyamide container, which is transparent to microwave, and a micro-porous lid that allows water to escape without letting the ambient air come in and pollute the pure silica. Due to the slightly aggressive nature of the atmosphere, our experts have designed a solution fully protected with epoxy paint to limit corrosion.


The 915 MHz microwaves frequency was selected as this wavelength is adapted to heat and dry large volumes of products homogeneously.


Key benefits

SAIREM’s engineers helped the client find the best solution to meet this specific need. By using the homogeneous heating properties of the microwaves, our equipment is able to heat dry the whole silica powder mass from core to surface, without use of airflow or any potential pollution source.


We provided our customer a perfectly designed microwave drying  system, with a power of 50 kW, capable of removing 50 kg of water per hour and reducing the humidity rate from 24% to less than 1%.

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