Introduction
In the oil seed processing industry, care needs to be taken every step of the way - from harvest, storage and seed preparation to extraction, refining, and distribution - to ensure the quality of the final product. Be it extraction for edible oils or biofuels, mechanical oil presses and solvent extraction plants are at the heart of the oil seed processing endeavour. However, we cannot deny the essential role of the oil seed cleaning machine in ensuring that extraction machines can do their jobs right.
Seed cleaning equipment is ordinarily used between the steps of seed storage and oil extraction. Its job description? To ensure that stones, sticks, weed seeds, metallic objects, dust, sand, and other foreign materials don't enter the oil seed preparatory machines or extraction equipment. By extension, a seed cleaner machine also ensures that quality edible oil or fuel is produced.
Seed cleaning techniques and oilseeds cleaning equipment affect the quality of the final product and the longevity of your processing equipment. Essentially, they affect the economics of your operation and your final profit and loss statement. When your bottom line is at stake, you surely can't afford to make mistakes.
This quick primer will take you through the need for an appropriate and good quality oilseed cleaning machine. It will take you through the techniques and machines used in seed cleaning and the consequences of letting contaminants slip through. It is a great introduction to the world of seed cleaning equipment - perfect to help you understand what questions you should ask a supplier before you purchase a seed cleaning machine from them.
Oilseeds cleaning equipment vs impurities of all kinds
After harvest and transport, when seeds arrive at an oil mill, they aren't all shiny and perfectly clean. They don't arrive ready to be processed into edible oil or fuel. They must be made ready. Step one ordinarily involves separating the oilseeds from all the foreign materials that have been gathered during harvest or transport. Impurities, or unwanted components, are usually of three kinds:
There are organic impurities: grass, stems, sticks, leaves, and the like.
Inorganic impurities: pebbles, sand, dirt, metallic pieces.
And there are oily impurities: weed seeds, pests, and other organic components which may release oils of their own.
Naturally, different shipments of oilseeds contain different quantities of impurities. The difference between a high-quality batch of oilseeds and a poor-quality one is the percentage by weight of impurities. The former will usually have roughly 1% of impurities, while in the latter, impurities can go up to as much as 10% by weight. Further, depending on the physical properties and source of the oil-bearing material, different cleaning techniques are needed. For instance, groundnut cleaning may need you to separate stones from the seeds, while copra cleaning may call for eliminating sand. The technique and seed cleaning machine used will depend on the size, weight, and other physical characteristics of the impurity.
The need for an oilseed cleaning machine
There are a few simple reasons why we must eliminate foreign materials from oilseeds:
- To prevent oil degradation: Impurities, especially oily kinds, can degrade final oil quality by lending it off colours, flavours, and smells. Impurities of all kinds may also result in unwanted sediments. Even the smallest percentage of foreign material can affect oil safety, quality, and the price which it can command in the market.
- To maintain high oil yields: Certain impurities - say cotton fibres during cottonseed oil production - may even absorb some of the oil from the seeds during processing. This will lower your total oil yield.
- To maintain protein content of press cake: You must remember that while oil quality is extremely important, so is the quality of the residual oil cake. The cake is an important resource for many allied industries, like animal feed mills. If your oilseeds, and therefore your cake, have a high percentage of impurities, that dilutes the protein content of the press cake. This reduces the value of the meal in terms of utility and also economically.
- To protect your oil processing equipment: Impurities like stones, metals, and other abrasive elements mixed in with oilseeds can damage oil pressing equipment. Such a situation may require shutting down the entire oil processing line to fix equipment damage. Not to mention the costs associated with repair, more frequent wear and tear, and the associated downtime. You can avoid these risks and costs altogether by investing in the right seed cleaner machine.
- To avoid wasting electricity: Ultimately, processing unwanted elements like weed seeds is simply a waste of resources like electricity.
As you can see, there is no way around using a highly efficient oilseed cleaning machine before oil extraction. Not cleaning the oil-bearing material well results in added costs and lower earnings, which is not a sustainable way to run an oil processing operation, let alone a highly profitable one.
Anderson International has assessed the cost of dirty oilseeds. The company has found that for a typical 300 TPD soybean oil mill, if the oilseeds have just 1% impurities, processing them can result in $8,400 worth of wasted electricity. Add to that wear and tear costs of equipment, lower oil prices earned in the market, and lower meal prices due to decreased protein content. Put all these costs together, and it turns out you pay a very high price for not using oilseeds cleaning equipment.
At what stage in the process is a seed cleaner machine used?
There are many reasons why oil may not be extracted from oilseeds immediately after harvest. For starters, oilseed presses operate at rates slower than harvesting, resulting in a bottleneck. Further, if multiple crops are harvested at once, there may not be enough capacity to process them all at once. This calls for the use of storage facilities for oilseeds.< As an oilseed processor, you would use your seed cleaning equipment either before or after storage, just before the use of the oil press. If organic and oily impurities are present in the oilseeds in large quantities, they may serve as triggers for mould growth or heating. In such a situation, oilseeds should be cleaned prior to storage. However, since harvesting and oilseed drying usually happen faster than cleaning, it's not always possible to clean large oilseed quantities before storage.
Careful harvesting to get the cleanest seed possible is an investment in the safety and quality of oilseeds. Additionally, you should use an oilseed cleaning machine directly before oil extraction. As the oilseeds are transported from storage bins to the oil pressing machine, ideally, you should introduce seed cleaning equipment in between.
Oilseeds cleaning equipment: Then and now
Seed cleaning machines have not changed significantly over time. An oilseed cleaning machine today looks quite a bit like the ones you would've found about ninety to hundred years ago. One notable difference, however, is that their safety has improved. Today, belt and chain drives and other moving components are enclosed to prevent hazards.
Types of seed cleaning equipment
Seed cleaning is not a single technique. Many different methods are used to clean oilseeds depending on their specific physiochemical properties. The steps employed differ based on specific oilseeds and the conditions in which they are grown, as we've pointed out earlier. In general, there are some basic factors based on which oilseeds are separated from foreign materials: size, weight, density, and magnetism. One or multiple of these separation principles may be combined into a single piece of seed cleaning equipment.
Seed cleaner machines may rely on gravity separation by using appropriately sized screens to eliminate particles both smaller and larger than the desired seed. The machines may use fans and the principle of air separation to separate particles that may be the same size but of different weights, like the technique of winnowing. Seed cleaners may also be specially designed to remove dust or other specific foreign materials.
Kumar's seed cleaner comprises screens of different sizes to separate leaves, stems, dust, and other impurities from oilseeds. This uses the difference in size between oilseeds and impurities to separate them. The system also comes with an aspirator to remove light particles and loose hulls, using differences in weight to achieve this.
Crown's cascade aspirators are seed cleaning machines that use size and weight for separation. They employ a combination of gravity, impact rods, and air. Kumar's destoner uses variations in density to remove stones, glass, and other high-density materials from oilseeds. Kumar's rotary drum magnetic separator, meanwhile, separates ferrous particles from oilseeds using the principle of magnetism.
We hope this primer has been a useful guide to understanding oilseeds cleaning equipment. If you want more detailed information on which machines would be the right fit for your oilseed processing plant, Kumar's experts are always happy to help.
