Preparation
Basics
Delivery of the soapstone and its intensive quality inspection heralds in a complex fabrication process. It starts with the staged preparation of the raw material.
Even in this early phase the fundamentals for our often attested to product quality are created.
Preparation is arranged chronologically in 3 steps. From grinding, dehydration and drying up to optimizing.
Step 1: Grinding
Looked at chemically soapstone is a magnesium silicate. It is compounded with selected components in a standardized process.
With water added, mixing and grinding are done in large wet drum mills. The right grinding time can result, if required, in grain sizes of under 20 µm.
Step 2: Dehydrating
We distinguish between two dehydration forms: Mechanical and thermal.
Mechanical dehydration: "Filter presses" dehydrate the ground suspension under high pressure. The logical principle: As the water is drained off, various filter chambers hold back the solids. The pressing time is precisely defined. Filter cakes arise in the consistency required.
Thermal dehydration: In this process the suspension is evenly spread through a number of nozzles in a spray tower. Here it is dried with the help of hot air. Tiny and particularly free-flowing hollow spheres form. They serve as the ideal raw product for economical processing in the dry pressing technique.
Step 3: Optimizing
The conclusion of the preparation process is the optimization or conditioning of the press granules. In this processing step, parameters for further processing are defined precisely.
Great attention is paid to these three factors:
- Moisture content
- Shot weight
- Granule distribution
Controllable are the product characteristics at first in the granulate production itself, but also through systematic moisturising, compressing, and screening. The parameters thus obtained and documented consistently are the best basis for a consistent quality control over all production steps.
