Grain and seed cleaning and storage – why is it so important?


by Facet Engineering CEO, Colin Fairweather:

The quality of harvested grain and seed is dependent on a few important factors, these include: the settings and capacity of the harvester, the moisture level of the grain or seed at the time of harvest, the level of heat damage and kernel breakage that may occur during the harvesting process. Most of these factors are extremely difficult, if not impossible to control. Also, the quality of the grain or seed starts to deteriorate as soon as it has been harvested. It is therefore vital that dirt and impurities be removed as soon as possible, to delay the deterioration process and ensure that the product being stored is of a high quality for end users.

Based on the above-mentioned factors, it is highly recommended that harvested grain and seed are passed through a grain cleaner and/or pre-cleaner in order to optimize the quality of the grain before it goes into storage.

Pre-cleaning grain before storage plays two vital roles:

  1. Adding value to the grain through the removal of dirt, impurities and damaged particles.
  2. Ensuring a longer life of the grain whilst it is in storage.

The importance of cleaning before storage

Foreign matter also referred to as fines (any dirt or particles smaller than the grain) can collect in areas inside the storage silo. These pockets of fines can cause hot spots inside the silo, which adversely affects the aeration of the grain or seed. This can also result in moisture collecting in these areas, which can cause rot, mould and other damage to the grain.


The additional impurities take up valuable storage space inside the silo – an unnecessary cost that can be avoided if the grain has been cleaned before being taken into storage. The impurities can also contain harmful or poisonous particles which can cause further damage, negatively affecting the quality of the grain and seed.

Cleaned grain and seed is of a higher quality and will therefore fetch a better price than ‘dirty’ grain that is full of impurities. Even if a producer does not have their own storage facilities, clean grain and seed will bring a higher return on investment for the producer. Grain that is rejected by a buyer or co-op usually results in the costs of cleaning and re-submitting to be carried by the seller, costs which can ultimately be avoided.

Grain cleaners are the first and most important piece of equipment used to clean any type of grain, seed or beans. When analysing all of the elements that can have an impact on grain quality, it makes good business sense for a seed or grain producer to seriously consider procuring their own grain cleaner. It is estimated that the cost of a grain cleaner can generally be recouped over two to three seasons, making it a viable purchase, even for smaller producers.

Innovation in the field of grain and seed cleaning

Facet Engineering has been an innovator in the field of grain and seed handling and cleaning for the last 30 years, and have developed their own range of grain and seed cleaning and handling equipment that can process at capacities of as high as 120 tonnes per hour.

Their range of grain cleaners includes four models, all locally manufactured in South Africa in their state-of-the-art workshop facility. All these models can be used to clean a variety of different grains, either for pre-cleaning or fine cleaning. This is achieved by virtue of the ability to change the settings on the machines as well as fitting different screen sizes on the removable screens.

These easily-operated machines work on the tried and tested principle of vibrating screens and air extraction to separate the grain from impurities. These impurities include anything larger than the grain such as sticks (also known as overs), and anything smaller than the grain like broken kernels or sand, as well as anything lighter than the grain such as husks and dirt (also known as fines).

All the models can be supplied with an optional air extraction fan, galvanised ducting and receiving cyclone for the collection and recovery of all of the light impurities.

Facet Engineering also offers other machines for the cleaning, separating and sizing of grain, seed and cereals. These include:

Destoner – used to separate and remove stones which are of a similar size to the seed or grain kernel. This machine works on the principle of separating by specific density or weight of the particles.

Gravity table – another machine in the range which separates grain into different fractions based on specific densities. This machine is ideal for the removal of kernels which are rotten inside or eaten away.

Electronic colour sorters – highly specialised machines designed to separate or grade products such as seed, grain, beans and nuts, by virtue of their colour differences which can be configured/calibrated using pre-programmed colour parameters.

Facet Engineering’s process division works extensively in the Agri-food sector and offers solutions for: storage, conveying, cleaning, separating, grading, mixing, sorting and bagging of grain, seed and cereal products. Facet Engineering’s experience within the Agri-food processing industry spans more than 30 years. They have a wealth of knowledge in developing solutions for the handling and processing of grain, seed and cereal products.