Scrap metal
| Infobox on Scrap metal | |
|---|---|
| Example of Scrap metal |  |
| Facts | |
| Origin | - |
| Stowage factor (in m3/t) | Varies |
| Humidity / moisture | - |
| Ventilation | - |
| Risk factors | See text |
Scrap metal
Description / Application
Scrap consists of recyclable materials left over from product manufacturing and consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap can have significant monetary value.
Scrap metal originates both in business and residential environments. Typically a "scrapper" will advertise their services to conveniently remove scrap metal for people who don't need it, or need to get rid of it.
Scrap is often taken to a wrecking yard (also known as a scrapyard, junkyard, or breaker's yard), where it is processed for later melting into new products. A wrecking yard, depending on its location, may allow customers to browse their lot and purchase items before they are sent to the smelters, although many scrap yards that deal in large quantities of scrap usually do not, often selling entire units such as engines or machinery by weight with no regard to their functional status. Customers are typically required to supply all of their own tools and labour to extract parts, and some scrapyards may first require waiving liability for personal injury before entering. Many scrapyards also sell bulk metals (stainless steel, etc.) by weight, often at prices substantially below the retail purchasing costs of similar pieces.
In contrast to wreckers, scrapyards typically sell everything by weight, rather than by item. To the scrapyard, the primary value of the scrap is what the smelter will give them for it, rather than the value of whatever shape the metal may be in. An auto wrecker, on the other hand, would price exactly the same scrap based on what the item does, regardless of what it weighs. Typically, if a wrecker cannot sell something above the value of the metal in it, they would then take it to the scrapyard and sell it by weight.
Great potential exists in the scrap metal industry for accidents in which a hazardous material, which is present in scrap, causes death, injury, or environmental damage. A classic example is radioactivity in scrap; see the Goiânia accident and the Mayapuri radiological accident as examples of accidents involving radioactive materials, which entered the scrap metal industry and some details of the behaviour of contaminating chemical elements in metal smelters. The general nature of many of the tools used in scrapyards such as Alligator shear, which cut metal using hydraulics give themselves the need for safety.
The metal recycling industry encompasses a wide range of metals. The more frequently recycled metals are scrap steel, iron (ISS), lead, aluminium, copper, stainless steel and zinc. There are two main categories of metals: ferrous and non-ferrous. Metals which contain iron in them are known as Ferrous where metals without iron are non-ferrous.
- Common non-ferrous metals are copper, brass, aluminum, zinc, magnesium, tin, nickel, and lead.
- Non-ferrous metals also include precious and exotic metals.
- Precious metals are metals with a high market value in any form, such as gold, silver, and platinum group metals.
- Exotic metals contain rare elements such as cobalt, mercury, titanium, tungsten, arsenic, beryllium, bismuth, cerium, cadmium, niobium, indium, gallium, germanium, lithium, selenium, tantalum, tellurium, vanadium, and zirconium. Some types of metals are radioactive. These may be “naturally-occurring” or may be formed as by-products of nuclear reactions. Metals that have been exposed to radioactive sources may also become radioactive in settings such as medical environments, research laboratories, or nuclear power plants.
OSHA guidelines should be followed when recycling any type of scrap metal to ensure safety.
Shipment / Storage / Risk factors
Carriage advice (for containers)
Scrap is seen increasingly as a global commodity. There is a considerable trade from the West to Asian economies, not least China, to feed the considerable appetite of the local steel industry.
More and more scrap is being shipped in containers, which offers cost savings compared to traditional loading and carriage methods.
When scrap is carried in bulk, it is possible to carry out a visual inspection of the cargo, which may highlight any obvious hazards relating to the cargo. However, this is not possible when scrap is carried in a container, unless the container is actually opened. In the liner trade this is impractical.
The carrier therefore has to rely upon the description declared by the shipper when accepting the cargo. However, the International Maritime Dangerous Goods (IMDG) Code does not include any specific requirements for the carriage of scrap metal and there is a risk that shippers could be shipping non-metal items that have not been segregated during the scrapping process and which, under the right conditions may have the capacity to cause a fire within the container.
Therefore it is recommend that any shippers be asked to define exactly what the scrap actually consists of. Where this reveals products that would be classed as dangerous goods under the IMDG Code, a declaration should be made and the container marked and stowed accordingly.
Scrap covers a wide field ranging from compressed cubes of old drink cans to heavy girders and structural steel. Weight restrictions should always be foremost in the mind when loading scrap and also potential damage to containers. In the case of damage to containers the tipping of containers during discharge should not be allowed. Unless the retentions are satisfactory there is a good argument for not accepting certain types of scrap because of the damage they do to containers. In particular scrap which corrodes(acid), oil stains, or seriously damages paintwork, requires precautions taken as shown below to guard against this happening. The carriage of scrap in refrigerated containers is not permitted by ICM.
Guidelines on risk in taking precautions :
Code Risk of contamination (ROC)
1. Minimal risk Nil 0
2. Slight risk Plastic floor sheet 25
3. Moderate risk Heavy duty plastic sheet 70
4. High risk Heavy duty plastic sheet & line with old plyboard 150
Scrap Category Description ROC
CANNING Usually old cans compressed and made up into cubes 1
ALUMINIUM Normally small light parts that do not scuff the ctr. 1
DRY BATTERY Heavily weighted, palletized & shrunk wrapped 2
WET BATTERY Heavily weighted, often leaking acid residue 3
OILED MACHINERY Old machine parts which often have oil residue 3
STEEL VARIOUS Can include cut up girders and structural steel 4
MIXED May be subject to IMDG rules e.g. Swarf Class 4.2 (Full description essential) 4.
Additional information/advice on scrap
Scrap, Used auto spare parts, Recycling
It is not allowed to load these commodities in 20' or 40' OT (Open Top) containers.
SCRAP is only acceptable in DRY VANS, Used auto parts / Recycling are also only accepted in DRY VANS. Metal scrap can be classified as follows and procedures apply equally to all types of scrap:
Ferrous (I.e. steel products):
- Steel pipes
- Steel pieces
- Mild steel
Non-ferrous (I.e. non steel products):
Loose metal scrap is NOT to be accepted. Scrap is to be either BUNDLED or loaded into BIG BAGS, and is only to be accepted provided the container floor/sides and end wall are lined with protective materials e.g. plywood, also a solid Bulkhead is to be fitted at the door end.
If the SCRAP contains any residue of oil, water etc, and for ALL USED AUTO SPARES/PARTS, in addition to the above protection the container floor has to be covered/protected with plastic sheets. The plastic sheets also have to cover the lower 30 cm of the container sides as well. Containers are allowed to be tilted to a maximum of 15 degrees during loading and unloading. Under no circumstances may the container be placed in an upright position during loading and unloading. (see photo below)
Metal scrap related to military or nuclear industry is NOT ACCEPTABLE if there is any risk that Weapons and/or Ammunition or other hazardous pieces are included.
Further please adhere to following instructions:
ALL SCRAP is ONLY acceptable if the scrap is CERTIFIED FREE OF RADIO ACTIVE MATERIAL OR OTHER HAZARDOUS SOURCES, CLASSED BY the IMDG CODE
Scrap cargoes are to be surveyed prior to loading to detect the presence of radioactive material.
All commodities have a natural "background" radiation, thus the certificate must declare clearly that the background radiation" is within the internationally accepted maximum limits.
On the Certificates to be supplied by the shipper. It is to be clearly noted and shown what and how the approved independent surveyor measured and observed the background "radiation" and that the commodity can be shipped as normal scrap. This survey is effectively already done by S.G.S. in several countries however there are more global and officially approved organizations who can conduct such surveys.
Agents are responsible for verifying the authenticity of the above certificates.
Avoid contracting with unknown scrap dealers/charterers, offering scrap cargoes.
Although in practice it is often noticed, below mode of stuffing is strictly forbidden because it is causing a lot of container repairs.
It is not allowed to load these commodities in 20' or 40'OT containers.
Battery scrap and used batteries in bulk are NOT ACCEPTABLE in dry containers, unless drained of acid and cleaned/ purged and correctly packed in order to protect containers from being corroded by leaking liquid. The container floor is to be protected by thick polythene sheets, the side and end walls must also be protected by thick polythene sheets extending at least 30 cms up the container walls. Containers stuffed with battery scrap properly cleaned and packed must be stowed ON DECK.
A written statement from the shipper that batteries are properly cleaned from all kind of hazard is required and non dangerous for shipment under transport.
Batteries drained of acid but not cleaned/ purged are classified as hazardous waste and may be subject to refusal of shipment.
The following report was produced by the Care-fully to Carry Committee – the UK P&I Club’s advisory committee on cargo matters
Scrap metal (borings, shavings, turnings, cuttings, dross) – in bulk -
Ferrous materials in the form of iron swarf, steel swarf, borings, shavings or cuttings are classified in the IMO Code of Safe Practice for Solid Bulk Materials as materials liable to self heating and to ignite spontaneously.
Turnings are produced by the machining of steel, turning, milling, drilling, etc. When produced the turnings may be long and will form a tangled mass but they may be passed through a crusher or chip breaker to form shorter lengths. Both forms of turnings are shipped and shipments are frequently a mixture of short and long chips. The density of the short chips is of the order of 60
pounds per cubic foot, twice the density of the longer chips as they tend to compact more readily.
Borings are produced during the making of iron castings. Because of the nature of the parent metal, borings break up more readily than turnings. They tend to be finer and the bulk density is greater than turnings.
Turnings and borings may be contaminated with oils - cutting oils for instance - used in the manufacturing processes. Oily rags and other combustible matter may also be found among the loads.
Iron will oxidise, (rust) and iron in a finely divided form will oxidise rapidly. This oxidation is an exothermic reaction, heat is evolved. In a shallow level mass of turnings this heat will be lost to the surrounding atmosphere. However in large compact quantities as in a cargo hold this heat will be largely retained and as a result the temperature of the mass will increase. This oxidation process is accelerated if the material is wetted or damp, contaminated with certain cutting oils, oily rags or combustible matter.
The turnings may heat to high temperatures but will not necessarily exhibit flames. In one incident temperatures in excess of 500°C were observed six feet below the surface of the cargo.
Temperatures of this order may cause structural damage to the steelwork of the carrying vessel. Flames are frequently seen in cargoes of metal turnings but these flames are usually the result of ignition of the cutting oils, rags, timber and other combustible materials mixed with the turnings.
Spontaneous heating of metal turnings has caused several major casualties. In the incident mentioned above spontaneous heating was detected, the vessel was moved from port to port in attempts to agree discharge. After weeks of delay all the holds were eventually flooded to reduce the heating for safe discharge of cargo. Following discharge of the turnings the vessel loaded
a cargo of conventional scrap. During the subsequent voyage rough weather was encountered, cracks developed in the shell plating, the holds flooded and the vessel was lost with 29 lives.
In another incident heated turnings formed a solid mass in the hold which had to be mechanically broken into pieces before discharge by grab. In a further incident, following a normal passage it was not possible to discharge the cargo by grabs. The surface of the stow had crusted to a hard mass. Bulldozers were used to loosen the surface of the cargo and several hours later fire was observed in all of the holds.
The IMO Code of Safe Practice for Solid Bulk Cargoes has special requirements for the loading of turnings and borings which include:
1. Prior to loading, the temperature of the material should not exceed 55°C. Wooden battens, dunnage and debris should be removed from the cargo space before the material is loaded.
2. The surface temperature of the material should be taken prior to, during and after loading and daily during the voyage. Temperature readings during the voyage should be taken in such a way that entry into the cargo space is not required, or alternatively, if entry is required for this purpose, sufficient breathing apparatus, additional to that required by the safety equipment regulations, should be provided. If the surface temperature exceeds 90°C during loading, further loading should cease and should not recommence until the temperature has fallen below 85°C. The ship should not depart unless the temperature is below 65°C and has shown a steady or downward trend in temperature for at least eight hours. During loading and transport the bilge of each cargo space in which the material is stowed should be as dry as practicable.
3. During loading, the material should be compacted in the cargo space as frequently as practicable with a bulldozer or other means. After loading, the material should be trimmed to eliminate peaks and should be compacted. Whilst at sea any rise in surface temperature of the material indicates a self-heating reaction problem. If the temperature should rise to 80°C, a potential fire is developing and the ship should make for the nearest port. Water should not be used at sea. Early application of an inert gas to a smouldering fire may be effective. In port, copious quantities of water may be used but due consideration should be given to stability.
4. Entry into cargo spaces containing this material should be made only with the main hatches open and after adequate ventilation and when using breathing apparatus.
It will be noted that compacting the cargo as loaded with a bulldozer is recommended. This will tend to form a dense mass, pushing the short turnings into the bundles of long turnings, tending to exclude air from the stow. However some authorities argue that compacting the stow tends to break up the long turnings, creating greater surface areas for the oxidation process. However shorter turnings should compact more readily than the longer forms and thus reduce the area exposed to oxidation.
The reference to trimming level ensures that there is less cargo surface exposed to the air than cargo in a peaked condition. Furthermore, theoretically air will pass across the top of a level trim, but can pass through the stow if loaded in a peaked condition creating a 'chimney' effect, thus accelerating the heating process.
The requirements for entry into cargo spaces are very important, many lives have been lost by officers and crewmembers entering a hold to inspect a heating problem without taking adequate precautions. Oxygen is essential for the oxidation process and in a sealed space the oxygen is reduced by the heating reaction of the turnings or borings.
The concentration of oxygen in air is 20.8%. Exposure to an atmosphere of 16% oxygen concentration causes an impairment of mental and physical state. Concentrations of 10% will cause immediate unconsciousness and death will follow if not removed to fresh air and resuscitated. The symptoms which indicate an atmosphere is deficient in oxygen may give inadequate notice to most
people who will then be too weak to escape when they eventually recognise the danger. Ventilation of the hold and testing the atmosphere or use of breathing apparatus is essential for safe entry to a hold which is loaded with these cargoes.
Metal dross and residues
Aluminium dross
Aluminium dross is formed during the recovery of aluminium from scrap and in the production of ingots. Dross may constitute about 5% of the metal where clean mill scrap is involved but will constitute greater quantities where painted or litter scrap is recovered. The main components of dross are aluminium oxide and entrained aluminium. Small amounts of magnesium oxide, aluminium carbide and nitride are also present.
The dross is recovered and re-melted under controlled conditions to provide aluminium metal which is then treated to remove hydrogen and other impurities including trace elements. Storage or transport of aluminium dross should be conducted under carefully controlled conditions.
Contact with water may cause heating and the evolution of flammable and toxic gases, such as hydrogen, ammonia and acetylene. Hydrogen and acetylene have wide ranges of flammability and are readily ignited.
Aluminium dross, aluminium salt slags, aluminium skimmings, spent cathodes and spent potliner as aluminium smelting by-products are included in the IMO Code of Safe Practice for Solid Bulk Cargoes.
The Code recommends that hot or wet material should not be loaded and a relevant certificate should be provided by the shipper stating that the material was stored under cover or exposed to the weather in the particle size in which it is to be shipped for not less than three days. The material should only be loaded under dry conditions and should be kept dry during the voyage. The
material should only be stowed in a mechanically ventilated space. The ventilation equipment should be intrinsically safe.
Zinc dross
Zinc dross, zinc skimmings, zinc ash and zinc residues are all materials obtained from the recovery of zinc. The zinc types may be recovered from galvanised sheets, batteries, car components, galvanising processes, etc. Zinc ashes are formed on the surface of molten zinc baths, and whilst primarily zinc oxide, particles of finely divided zinc will also adhere to the oxide. The various types of zinc are treated by processes to produce pure zinc metal.
The ashes, dross, skimmings and residues are all reactive in the presence of moisture liberating the flammable gas hydrogen and various toxic gases. The materials are also listed in the IMO Code for Solid Bulk Cargoes which states that any shipment of the material requires approval of the competent authorities of the countries of shipment and the flag state of the ship.
The Code recommends that any material which is wet or is known to have been wetted should not be accepted for carriage. Furthermore the materials should only be handled and transported under dry conditions. Ventilation of the holds should be sufficient to prevent build up of hydrogen in the cargo spaces. All sources of ignition should be eliminated which would include naked light work such as
cutting and welding, smoking, electrical fittings etc.
One incident where the cause of an explosion in a hold containing zinc ashes was said to be a lamp used to warm the sealing tape used to seal the hatchcovers. The flame of the lamp was stated to have ignited hydrogen gas leaking from the hold. The flame flashed back into the hold to ignite an explosive concentration of hydrogen/air. The explosion lifted the hatchcovers and collapsed a deck crane. Unfortunately there was also loss of life. The hydrogen had been generated by reaction of the zinc ashes with water, zinc ashes which had been loaded in a damp condition. The zinc ashes were discharged and later spread on the quayside in a thin layer to dry. Seven days later hydrogen was still being evolved to the atmosphere, as proved by tests with a hydrogen gas detector.
Note:
Please consult the IMSBC (International Maritime Solid Bulk Cargoes Code) of the IMO (International Maritime Organisation).