Copra Expeller

Infobox on Copra Expeller
Example of Copra Expeller
Facts
Origin	This table shows only a selection of the most important countries of origin and should not be thought of as exhaustive. Europe Africa: Mozambique Asia: India, Philippines, Indonesia America: USA Australia
Stowage factor (in m3/t)	1.70 - 2.00 m3/t In order to ensure better utilization of transport volume, copra expeller should be compressed. Storage in silo cells is risk-free.
Angle of repose	approx. 42°
Humidity / moisture	Copra expeller requires particular temperature, humidity/moisture and ventilation conditions Relative humidity: 70% Water content: 5 - 10% Maximum equilibrium moisture content: 70%
Oil content	1.5 - 7.0%
Ventilation	Copra expeller requires particular temperature, humidity/moisture and ventilation conditions. Recommended ventilation conditions: surface ventilation. See text for further details.
Risk factors	Self-heating / Spontaneous combustion Oil content: 1.5 - 7.0% Copra expeller is liable to the risk of self-heating/spontaneous combustion.

Copra Expeller

Description

Coconut oil is obtained by extracting the oil contained in copra. The residue is generally called copra cake, sometimes it is called copra meal. Coconut oil is used for food and for industrial purposes. Edible oil, by international standards should have less than 0.1% free fatty acid content. The oil obtained from good quality copra, with a free fatty acid content of < 0.1%, is used as cooking oil without any further processing. Even if the free fatty acid content is 3-5%, the international standard of < 0.1% can be obtained by refining and deodorizing. Edible oils are either used as cooking oil (frying oil) or processed further into filled milk, table margarine and baker's margarine.

In industry, coconut oil is used for manufacturing toilet and laundry soap. In its original or modified form, it is used as a vehicle in the paint and varnish industry. Coconut oil is also processed into methyl esters, fatty acids and fatty alcohols. These intermediate products are raw materials for manufacturing detergents, surfactants, emulsifiers, plasticizers and various other organic products which are bio-degradable. Copra cake is used in blending animal feed.

Extraction Technology, Dry Processing:
Oil extraction from copra is carried out by two methods: mechanically by pressing; or by use of solvents. Mechanical and solvent extraction uses standard technology that has been developed in the vegetable oil industry. For oil seeds such as copra which have a high oil content, mechanical extraction is efficient and economical. For oil seeds with low oil content or for further oil extraction from copra cake, the solvent extraction method is more suitable. The residual material from solvent extraction is called copra meal. Oil extraction involves five basic steps shown in the ‘Simplified general flow diagram’ (See figure): copra storage; preparation of copra; oil extraction - full press, prepress - solvent, and full solvent methods; processing of extracted oil; processing of cake or meal and storage of products.

Full press method:
In the full press method of oil extraction, maximum pressure is applied to the material and sufficient time is allowed for the oil to escape. The temperature of the material should not be allowed to rise to a level where the oil darkens due to overheating. The pressure is applied to the material between the screws and the cage of slitted steel bars. Pressing may be done in a single or in double stages. By adjusting the clearance in the choking device, the thickness of the cake can be controlled. When the clearance is reduced to decrease the thickness of the cake, the pressure applied is increased. To prevent overheating the oil, the shaft is usually hollow for water cooling, and the oil is sprinkled over the cage bars.

Prepress-solvent method:
In the prepress-solvent process, the oil is partially extracted by preliminary low pressure mechanical extraction, and then subjected to solvent extraction to remove most of the residual oil. The oil content of the initial copra material is around 70%; after the mechanical prepress extraction, the residual oil content in the prepressed cake is 16 - 20% for optimum operation. After full press extraction, the oil content in the residual copra cake is 6 - 10%, depending upon efficiency. The equipment used for prepressing is similar to expellers used for full pressing, but adjusted for less pressure and therefore it has a higher throughput.

Full solvent method:
In solvent extraction, oil in the material is leached with a solvent (where the oil dissolves in the solvent) whereas the insoluble meal is retained unaffected. The extent of extraction depends upon the kind of solvent, the temperature of solvent, the ratio of solvent to meal, the number of extraction stages, the shape of particles, the porosity of the material, and the contact duration. The most common solvent used is Template:Hexane because of its price, low toxicity, suitable boiling point for recovery and handling, and its availability. Solubility of oil in hexane increases with temperature.

The resulting streams from solvent extraction are: the micella or oil, solvent solution, and the extracted meal which comprises the meal, some solvent and a little residual oil. The solvent in the meal is removed by heating to boil off the volatile solvent, and the solvent is recovered by condensation. The solvent from the micella is removed and recovered by evaporation and condensation. Traces of solvent left in the meal and the oil are removed by steam-stripping under reduced pressure.

The equipment for solvent extraction consists of two general types; the roto-cell type with cells revolving around a vertical axis, and the basket type with baskets travelling horizontally while the solvent is sprayed over the material in counter-current flow. In the full solvent process, the prepared copra is first subjected to a first extraction (percolation), using the weak micella from the second extractor as starting solvent, and producing the strong micella for oil recovery. The extracted meal is then flaked and subjected to a second extraction (immersion) which uses fresh solvent as starting solvent and produces the weak micella solvent for the first extractor. The solvent with the extracted oil is removed in a Desolventizer-Toaster (DT) which is either of the multi-decked vertical design with steam heated pans and paddle scrapers, or the horizontal barrel type with rotating conveying paddles attached to a horizontal shaft, and steam jacketed walls. These are equipped with condensers for solvent recovery and scrubbers to remove dust entrained in the vapours. In some designs, the heat with the vapours leaving the DT is used to pre-concentrate the micella prior to evaporation of the micella.

The solvent with the micella is recovered, first by an evaporator, usually of the falling film type, where hexane is distilled off by indirect steam heating, and subsequently by a stripping column where traces of hexane in the oil are stripped by steam under vacuum. The water-hexane vapours from the stripper are condensed and collected in a water-hexane separator where hexane is separated by gravity from the water. It is decanted and reused in the extraction. Vent vapours of hexane from the extractors and condensers are recovered in a vent recovery system where hexane is absorbed by mineral oil. Hexane is recovered from the mineral oil by stripping, and recycled to the extractor.

Processing extracted oil:
Processing the extracted oil is the next basic step in the oil extraction technology. Oil from the expellers contain substantial quantities of solids (foots) that should be removed before the oil is pumped into the storage tanks. The oil is cleaned first by settling and screening and subsequently by filtration. The screening equipment is a rectangular steel tank equipped with a continuous drag chain conveyor with scraper blades, which scoop the settled solids and lift them over a fine screen for drainage at one end of the screening tank, after which they are conveyed back to the expellers to be mixed with the copra. The filtering equipment generally consists of a plate and frame filter press with canvass filtering media. Some factories use leaf filters with perforated steel filtering leaves. The foots or filter cake from the filters are recycled to the expellers for oil extraction. The oil from solvent extraction is free of solids. It leaves the stripping column at 120°C and is cooled and pumped into the storage tanks through an oil meter.

Processing cake or meal:
Copra cake leaving the expellers has a temperature of about 110 °C and is cooled in a cake cooler. The cake cascades down the cooler baffles and is cooled by a cross-flow of cooled air from blowers. After cooling, it is ground to fine particles by hammer mills or disc mills. The ground cake is bagged for local use or pelletized for export. Pelletizing requires additional equipment which small plants cannot afford. However, cake or meal for export has to be pelletized for safer and easier handling and conveying. Prior to pelletizing, the cake has to be moistened to about 12% moisture and then fed to the pellet mill. Moistening in this manner improves pelleting property, and is required for export. The oil content of copra cake should be around 6 to 10% and moisture not higher than 12%. For copra meal, the oil content is 0.5 - 2% depending on the efficiency of solvent extraction. Due to absorption, the moisture level rises during storage.

Storage of products:
The unpelletized copra cake should be bagged in woven sacks and stacked about 10 high on wooden pallets. It is hazardous to store unpelletized cake in bulk for long periods. The piles of unbagged meal should be kept small and turned over as frequently as necessary to prevent spontaneous combustion.

The (hot) finished expellers leave the production plant with a variable moisture content. After pressing, the expellers are cooled and, since they are in large pieces, they are ground and adjusted to a water content suitable for storage and transport. The ground products are then held in intermediate storage in silo cells or sent for transport.

Applications

Copra cake/expeller/meal is used as an ingredient in blending animal feed, due to the presence of oil, protein and carbohydrates. Copra cake from poor quality copra has a limited market due to its degraded condition and the presence of aflatoxin.

Shipment/storage

Product intended for shipping must be adequately matured. The time required for maturing is determined by the oil content. On the other hand, stored product from the previous year's harvest should not be accepted.

The consignor must provide certificates relating to the moisture and residual oil content and the maturing time of the product. It should also be determined that the product really is expeller and not extraction meal (extracting agent/solvent content). Oil contents of < 1.5% are indicative of extraction meal. Copra expeller consists of light gray to yellowish pieces (flakes) of variable size with a smooth, somewhat curved cut surface, which is the result of processing in an extruder.

Upon acceptance of a consignment, brown or reddish to black discoloration of the goods must be looked for, since this indicates overheating during production or excessively long storage. Expeller is mainly transported as bulk cargo. Only exceptionally is the product transported as bagged cargo (in very small quantities). Bulk containers subject to compliance with lower and upper limits for water and oil content and the maturing time of the product and water content of the container floor (see RF Self-heating).

Do not unload very hot product with hydraulically operated grabs as the hydraulic lines are not capable of withstanding such elevated temperatures. Use only cable-operated grabs for spontaneously heated product. Stow cool, dry. Mechanical ventilation of the stowage spaces must be possible. Do not stow over heated double bottom tanks, close to the engine room bulkhead and pipework which may become hot.

Risk factors

Temperature
Copra expeller requires particular temperature, humidity/moisture and ventilation conditions. Favorable travel temperature: 5 - 25°C.

Up to a temperature of 25°C, expeller may be loaded irrespective of the external temperature. At elevated external temperatures, the product temperature must be no more than 10% higher than the external temperature. Continuous temperature measurements should be taken during loading of the cargo. In tropical ports, temperatures of 25 - 55°C may occur in the products to be loaded.

The temperature must accordingly also be measured at various depths in the hold during the voyage. If the temperature rises above 55°C and any further increase is observed, countermeasures must be taken, e.g. tight closing of all hatch openings and injection of CO₂ or inert gas. The product is best stowed in the coolest possible locations. Avoid stowage spaces close to the engine room or over heated double bottom tanks.

The enzymes which initiate and intensify fat degradation and thus the self-heating process reach optimum levels of activity at temperatures of 35 - 40°C, i.e. temperatures which are easily reached within the heaped cargo. The travel temperature should thus be between 5 and 25°C. Temperatures of up to 30°C are also admissible for short periods. However, these conditions are difficult to maintain during an ocean voyage, as a consequence of which very careful attention must be paid to ensuring that the critical water content of the product is not exceeded in order to avoid self-heating to the greatest possible extent.

Humidity/Moisture
Copra expeller requires particular temperature, humidity/moisture and ventilation conditions.

Designation	Humidity/water content
Relative Humidity	70%
Water content	5 - 10%
Maximum equilibrium moisture content	70%

Expellers must be protected from all forms of moisture (seawater, rain and condensation water), since moisture encourages mold, mustiness and self-heating.

Moisture promotes self-heating brought about both by hydrolytic/enzymatic degradation and by microorganisms and may be the result of an excessively high product water content (critical water content 10.5%) or alternatively of external influences (excessively high relative humidity (critical equilibrium moisture content 75%), seawater, rain). At a water content of < 5%, there is a risk of oxidative fat cleavage, dust formation/dust explosions and self-heating.

Ventilation
Copra expeller requires particular temperature, humidity/moisture and ventilation conditions. Recommended ventilation conditions: surface ventilation. "Bulk" expeller is frequently carried without ventilation as the elevated oil content may otherwise give rise to autoxidation and thus self-heating. Due to the principal causes of self-heating in vegetable pressing residues, two problems arise with regard to ventilation:

• At an excessively high product water content (copra expeller > 10%), localized overheating caused by enzymes or bacteria results in self-heating. The resultant heat must be dissipated by constant ventilation by means of a good ventilation system. Drying by ventilation is useful, but its effectiveness is questionable because, as heating proceeds, increasingly large quantities of water vapor are released. The activity of the initiating microorganisms is not suppressed by non ventilation of the hold as some of the thermophilic (= heat-loving) bacteria are anaerobic organisms (which require no oxygen supply to stay alive).
  
• In a product with an excessively low water content (copra expeller < 5%), which must be expected to undergo oxidative fat cleavage, the supply of oxygen must be interrupted as this process would otherwise be accelerated. Any attempt to cool the cargo by ventilation supplies air, so further promoting the oxidation process.
  
  

Ventilation is helpful in the first case, but hazardous in the second. The correct ventilation measures may only be implemented if the characteristics (loading temperature, water content, duration of prior storage) of the cargo are known. However, if a large batch is made up of various sub-batches, it is entirely possible for both the above-stated causes to occur in the same heap of cargo.

In order to avoid moisture damage on the surface of the cargo, ventilation must not be performed with cold external air. The ventilation system must then be switched to return air. A certificate stating residual oil content, water content and maturing time should be demanded from the consignor. If the oxidation processes under way in the hold are vigorous, it is not possible to dissipate the quantity of heat generated by ventilation. This particularly applies if a sub-batch susceptible to oxidation with a low water content is loaded next to a sub-batch with a high moisture content.

Biotic activity
Copra expeller displays 3rd order biotic activity. It belongs to the class of products in which respiration processes are suspended, but in which biochemical, microbial and other decomposition processes still proceed. Care of the cargo must be aimed at limiting the fat cleavage process and so preventing possible self-heating of the product.

Gases
An increase in CO₂ and CO content in the hold air indicates that a cargo fire has begun. CO₂ has a smothering action on the seat of the fire because it displaces oxygen.

Self-heating / Spontaneous combustion
Oil content: 1.5 - 7.0%. Copra expeller is liable to the risk of self-heating/spontaneous combustion. Smoking/open flames are prohibited during loading, discharge and access to holds. Causes and promoting factors of self-heating are moisture, oxygen, elevated residual oil content, high fiber content and grain size.

Oxygen promotes oxidative fat cleavage. The principal cause underlying self-heating caused by oxidative fat cleavage is an excessively high oil content. An expeller oil content in excess of 7 - 10% promotes oxidation processes. An elevated unsaturated fatty acid content in the residual oil constitutes a very serious storage risk as such Fatty Acids have a strong tendency to undergo autoxidation with (atmospheric) oxygen, plentiful supplies of which are also available in a feedstuff cargo, to form saturated fatty acids. This autoxidation, as a kind of flameless combustion, results in considerable evolution of heat which may result in a hazardous build-up of heat in the feedstuff cargo if the heat cannot be dissipated.

The maturing time before ocean transport is of great significance to the promotion of self-heating processes in pressing residues, with both excessively short and excessively long maturing times possibly being disadvantageous. On acceptance, expeller should thus exhibit temperatures which are only insignificantly (approx. 10%) above external air temperature. It must be ascertained whether the batch is from the previous year's production. Unfavorable storage conditions over the period prior to shipping may mean that the product is already at elevated temperature when it arrives on board. Continuous temperature measurements are thus required during loading of the cargo.

The main risk for transport of any cargo which has heated ashore is that the product is loaded at temperatures of above 55°C and retains this temperature in the hold and, due to the poor thermal conductivity of the product, areas with a permanent heat build-up form for the entire duration of transport. The longer the duration of transport, the greater are the consequential losses arising from heating. In the areas with a heat build-up of above 60°C, the autoxidation process of the feedstuff containing residual oil gradually begins and continues as the unsaturated fatty acids oxidize. The hot spots do not spread much further. The product does, however, dry out, as a result of which moisture migrates upwards from below and water vapor collects in the space between the surface of the cargo and the underside of the hatch covers or weather deck. This accumulation of water vapor combined with maximally airtight hatch covers is the most effective method of fighting fire, as any external supplies of oxygen are blocked off.

Pursuant to the IMDG Code/IMO, ships must be equipped with systems for injecting CO₂ or inert gas.

The poor thermal conductivity of pressing residues is also of significance to self-heating. Self-heating may occur simultaneously at various points within the cargo and continue to such an extent that carbonisation (release of hydrogen, leaving carbon behind) occurs. The resultant fine-pored carbon has the characteristic of starting to smolder when exposed to oxygen. Due to the poor thermal conductivity of the product, temperature measurements to detect seats of risk are very difficult. Numerous measurements must be performed and some must also be taken within the heap. Surface measurements alone are not adequate. The poor thermal conductivity also explains late detection of the seat of a fire. The particular risk is that the cargo burns within the heap without generating appreciable quantities of smoke. The seat of the fire carves out a cavity with the result that fatal accidents may occur when someone steps onto the surface of the cargo and breaks through into such cavities.

In order to be able to detect a cargo fire in good time, it is recommended to make regular gas measurements of the hold air. A rapidly rising CO₂ content indicates increased microbial activity combined with evolution of heat within the cargo. This evolution of heat ultimately leads to the spontaneous combustion of the cargo, with evolution of carbon monoxide (CO). The presence of CO gas is considered the most reliable indication of a fire. Levels of 0.002 - 0.005 vol.% of CO in the air are deemed normal, with values rising to above 1 vol.% in a cargo fire.

On unloading, small flames may appear on the exposed surface of a heated cargo: volatile gases which have formed in the cargo over the course of self-heating and have a flash point of around 60°C have spontaneously ignited. These flames do not cause the remainder of the cargo to burn as the ignition temperature of most organic cargoes is of the order of 300 - 500°C. If such small flames or glowing areas of the surface occur in isolated areas, it is helpful to tip the last grab load back down into the area of the hold concerned, so smothering the flames.

The subsequent phases of self-heating possibly culminating in a cargo fire and the action to be taken are described in the article as outlined under Feedstuffs (self-heating process).

It is possible to conclude from characteristics observable in the ship's hold, such as temperatures, appearance and odor of the cargo, whether the product was loaded at too high a temperature and whether it has undergone self-heating with microbial spoilage and subsequent autoxidation.

The following features must be observed and recorded for this purpose:

• the flow behavior of the cargo in the heap (caked, free-flowing)
  
• the color of the product (normal, brown to black) and the distribution of color differences in the product in the hold
• the odor of the product (normal, healthy, fresh, musty, burnt)
  
• the temperature and appearance of the cargo at various depths in the bulk load
  
• the appearance of the cargo surface when the hatches are opened
  
• the appearance of escaping smoke/fumes (steam is white, smoke from overheated product with a temperature of above 90°C is black)
  
  

On the basis of this information, it is possible to conclude on the spot whether:

• the product was loaded too moist
  
• the product was loaded at too high a temperature after a drying process (toasting)
  
• the product was shipped shortly after production without complying with the maturing time
  
• biogenic self-heating has occurred during the voyage as a result of metabolic processes in microorganisms
  
• self-heating has occurred without a preceding biological self-heating process by chemical autoxidation of unsaturated fatty acids
  
• the product was loaded in a discolored state (brown to black) as a result of drying processes (toasting) performed during manufacture
  
  

Odor
Active behavior: Copra expeller has a slight, pleasant odor, but should not be stored together with odor-sensitive products as odor tainting may otherwise occur.
Passive behavior: Copra expeller is sensitive to unpleasant and/or pungent odors. Odor-tainted expeller is rejected by livestock (especially horses and cattle).

Contamination
Active behavior: Copra expeller causes severe dusting during cargo handling, such that there is a risk of dust explosion at dust/air ratios of 20 - 2000 g/m³.
Passive behavior: Copra expeller is sensitive to contamination by dust, dirt, fats and oils. The holds or containers should thus contain no residues of previous cargoes, such as ores, minerals, chemicals, salts, fertilizers.

Mechanical influences
No risk.

Toxicity / Hazards to health
An increase in CO₂ and CO content in the hold air indicates that a cargo fire has begun. Danger: Risk of asphyxiation and poisoning on inhalation. No access is permitted to the hold until it has been adequately ventilated and the atmosphere tested with a gas detector. The CO content may rise from 0.002 - 0.005 vol.% to 1 vol.%. The lethal (fatal) dose is approx. 0.1 vol.%.

Foreign admixtures (e.g. toxic castor seeds) and poisonous protein breakdown products are harmful to animals. Levels of infestation with the mold Aspergillus flavus of 3% are very harmful, in particular to turkeys, chicks and ducks, due to the aflatoxin complex.

Shrinkage/Shortage
Slight losses (trickle losses) may occur during cargo handling.

Insect infestation / Diseases
Insect infestation, especially by various species of beetles (e.g. khapra beetle), is widespread. On extended storage, there is a risk of mite infestation, which is promoted by heat and moisture. If required by the consignor or import regulations, fumigation (e.g. with Methyl Bromide) must be performed.

Reference is made to the relevant IMO regulations on hazardous cargo.

Note:(Source including Transport Information Service of the GDV)