Recycling metal is a modern activity made to recover metals that were used and thrown away at the end of their life cycle (mainly aluminium, steel and iron), in order to melt them down and produce new products.
Metal recycling refers to scrap metal (consists of metal left over from product manufacturing and consumption) and metal waste (used products containing metal) that are collected and melted to produce new appliances, vehicles, tools, gadgets, accessories, etc.
Today, we are recycling both ferrous and non-ferrous metals such as carbon steel and alloy steel, cast iron and wrought iron (as ferrous metals), and aluminium, copper, nickel, zinc, lead and tin (as non-ferrous metals).
Precious metals such as gold, platinum, silver, palladium and iridium are usually reused (they can be lost or thrown away only by mistake).
When comes to metal recycling, the good part is that metals can be recycled indefinitely without losing their properties.
How Does Metal Recycling Work
1. Collection
All the scrap metal recycled, including old cars and used appliances is collected at scrap metal facilities.
2. Sorting
Crane and bulldozer operators will scan the raw material for objects that can’t be processed such as propane tanks, glass or big pieces of heavy iron that could cause damage to the machinery.
Inspectors will check the material more closely (to remove any remaining objects that can’t be recycled), and after that, the crane operator will proceed with the next load of raw material for a new inspection.
3. Processing
The raw material that passes the inspection, is moved by the crane on a conveyor belt to be sent to the shredder.
According to the weight of the material, the belt can speed up or slow down the movement, to avoid a blockage of the shredder.
A heavy drum grabs the material from the conveyor belt and forces it into the shredder.
The shredder is the machinery that works the most inside the scrap metal facility (there is a lot of wear and tear on it), and this is the reason why an inspector checks it daily for damage.
All the raw material entering the shredder (old cars, used appliances, etc.) is shredded into fist size chunks, and an industrial vacuum will suck out the bits of rubber and glass that are mixed with the shredded steel.
Magnetic drums are used to separate the steel chunks from the non-ferrous materials, which will fall through to a conveyor belt locate below.
From the conveyor belt, pickers will remove any unwanted material from the steel chunks and the clean and shredded steel is ready to be shipped to customers such as steel mills and foundries.
The material that was not captured by the magnetic drums will go on for more processing because it could contain precious non-ferrous metal such as copper and brass (an alloy of copper and zinc).
The conveyor belt will transport the material containing non-ferrous metals to a machine called trommel that contains a rotating drum, which separates the material by size.
Only ferrous metals are selected
All the material remained after this final separation is trash, but before being moved to the landfill, an inspector will check it to be sure that no valuable material has slipped through.
The material containing non-ferrous metals selected by the trommel is evenly dispersed on a conveyor belt and moved to a machine called eddy current separator, where a rotating magnetic drum producing a very powerful magnetic field will repel the non-ferrous metals over a barrier and into a storage bin.
All material that doesn’t make it over the barrier, will go through the separator one more time to recover any non-ferrous metals contained.
The worthless residue will be moved by the conveyor belt to a trash bin, while the non-ferrous metals will be moved by another conveyor belt to a bin.
The non-ferrous metals will be sent to another facility to be separated after the type of metal contained (mainly copper, aluminium and brass).
Recycling Aluminium
An aluminium recycling facility uses manly bales of aluminium cans, but also aluminium parts of cars or planes, tools made of aluminium, etc.
The bales of compressed aluminium cans are loaded onto a conveyor belt and fed into a very powerful shredder.
Sorting aluminium is not an easy task because being a non-ferrous metal, the machine can’t use a magnet.
The shredded chunks of aluminium are passing on a conveyor belt through an optical sorter, which uses infrared sensors to separate the metal chunks from the non-metallic chunks, and the pieces of plastic or glass found will be blasted using jets of air.
A strong magnet will suck up any scrap of steel and will leave only the aluminium scraps to pass through.
The aluminium scraps are now clean (because the paint and lacquer covering the former aluminium cans were instantly vaporized), which means that they are ready to be melted.
To melt the aluminum scraps, the furnace reaches a temperature of 1346 Fahrenheit (°F) or 730 Celsius (°C).
During the melting process, the aluminium reacts with the air and forms a layer of aluminium oxide that floats on top.
A furnace operator will skim off the aluminium oxide with a very large steel spatula, and now the melted aluminium is ready to be poured into molds.
Huge aluminium ingots are produced
Several 32 foot long aluminium ingots are produced weighing about 27 tons each.
A 27 ton and 10 meters long aluminium ingot contains about 1.5 million aluminium cans.
The aluminium demand on the market is very high today, so the ingots obtained from the aluminium cans are sent to a rolling mill where they are heated again at a temperature of 977 Fahrenheit (°F) or 525 Celsius (°C), to relax the bonds between the aluminium atoms and release any stress withing them.
After being heated, the aluminium ingot is passed back and forth through a series of rollers, and each set of rollers makes the ingot thinner until reaching a thickness of 250 µ (microns), and a length of 32808 feet or 10,000 meters.
The massive reel of aluminium obtained this way will be used in the aerospace industry, and to produce new beverage cans, window frames, household metal packaging, new cars, etc.
Recycling Metal and the Environment
Our planet’s natural resources are limited, which means that by recycling metals we are conserving the metal reserves on the planet and we also are protecting the environment from additional air, soil and water pollution produced while mining for metal ore.
Never throw your aluminum cans to the trash bin, always try to put them into a recycling bin.
You can make some money recycling steel, iron, aluminum and other materials.
Aluminium is a pretty common metal in the Earth’s crust, but is expensive because it’s quite hard to extract from the rock around it.
The demand for aluminium being so high, it is very important to recycle every aluminum can we have because this way we are conserving the natural resources of the planet and we are reducing the greenhouse gas emissions released by the mining sector.
For every ton of steel produced from recycling, we are saving 2,500 pounds of iron ore, 1,400 pounds of coal (used as fuel to melt the metal), 120 pounds of limestone and a lot of energy.
By recycling 1 ton of aluminium cans (beverage cans) we are saving 21 MW of energy consumed while mining, shipping and refining virgin bauxite ore that is required to produce the same amount of aluminium.
Final conclusion
Recycling metal is a very important process for our planet because protects the natural resources of the Earth, reduces the energy consumption and the greenhouse gas emissions released while mining, shipping and refining metal ore, and also reduces the volume of trash being deposited in landfills.
