Download of Silica 2.3 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The software is categorized as Audio & Video Tools. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
Introducing Silica, a new way to convert Quartz Compositions into QuickTime movies, whether you need to convert one clip or one hundred. Just drag one or more compositions onto the Silica application tray, set the output movies' attributes, and click the export button to create a new collection of movies! Batch Processing - When exporting new movie output files, Silica handles the creation as a background task.
You may want to check out more Mac applications, such as Silica SX or PhasePlot, which might be related to Silica.