Contract powder compaction services

Single component products are routinely compacted. There is frequently a requirement to formulate and blend different materials prior to compaction.
Compaction of a pre-blended product prevents different components from segregating in use and ensures consistent delivery of all components with every dose.
As a result of this requirement many of Custom Powders compaction units have integral blending facilities.

Whether it is for Food, Animal Health or an Industrial product Custom Powders carry out all formulation and pre-blending to a standard meeting the requirements of GMP.
Raw materials are dispensed, independently checked and signed off on batch cards prior to blending.
Blending can be by low shear ribbon or U-trough blender or higher shear ploughshare mixer depending on the raw material properties. Blended powder is then discharged to suitable intermediate IBCs for transfer to compaction.

The powder to be compacted is metered into the compactor ‘vertical screws’ where pre-densification and de-aeration occurs.
The vertical screws force the powder into the compactor rolls. The rolls are pressed together by hydraulic rams, the rolls then extrude the compact as a sheet, or series of ‘pencils’, or even briquettes.
A range of roll profiles are available, with different profiles required for different raw material compaction properties.
Similarly the compactors have a range of different pressure capabilities, this is required both to achieve compaction with the different materials and also in some instances to control dispersion property of the final product.
The compact sheet is then milled and then sieved through a multistage process incorporating a single, double or even triple deck sieve. The aperture of the sieve screens is used to control the final product particle size. The selection of the mill type, size and screen design is critical to achieving an efficient compaction process.

Powder compaction processes generate product via a milling step. As a result some roll compacted products can be dusty unless treated prior to packing.
With more than 25 years of experience in roll compaction production, Custom Powders are experts at eliminating dust from compacted products. Many of our dedusting systems are developed in-house, this proprietary information cannot be revealed on our web site.
However, there are 2 fundamental approaches normally used in dedusting compacted granules, these are:
1 Agitation of the granule to dislodge dust which is then removed.
2 Addition of a liquid (oil or water) to bind loose dust into the granule.
The advantage of the first option for dedusting is that it can normally be carried out continuously, as part of the roll compaction process. The dust extracted can be recycled back to the compactor, thus avoiding loss of yield.
The first option alone is not always the best solution and it is not unusual for example in the Animal Health sector to post blend material adding up to 5% of an oil. The liquid added can have other benefits for the product beyond dedusting.
The disadvantage of dedusting by post blending with a liquid is it adds at least one, sometimes two process steps if post blend sieving is required.