Discarded electronics that reach the end of their lifecycles and are no longer functioning are often referred to as e-waste. E-waste includes smaller devices like cell phones, DVD players, and calculators and bulkier equipment like refrigerators, washing machines, and other large appliances. This e-waste contains aluminum, copper, ferrous metals, gold, nickel, palladium, platinum, silver, tin, and zinc. These metals are used as filaments for critical contact points and conduct electricity throughout electrical equipment. Modern electronics depend on small amounts of these valuable metals to make them work effectively.
Due to the extensive and growing use of electronics globally, e-waste has become the fastest-growing category within the world’s waste stream. By 2019, 53.6 million metric tons (about 59.1 standard tons) of e-waste were generated annually, approximately 7.3 kg (about 16.1) for every person inhabiting the planet. Though China is the world’s largest e-waste producer by volume, Europe and the Americas generate significantly more e-waste per capita. Recovering material from this e-waste involves several techniques, key among them pulverization. In waste management and recycling businesses, recovering these valuable metals has become an increasingly lucrative source of income.
Urban Mining: Economics of E-Waste Metal Recovery
Recovery of valuable metals from e-waste has become known as “urban mining.” While salvaging valuable metals from e-waste is environmentally responsible, the economics behind doing so is also sound. On average, it costs less than 8 percent to reclaim precious metals like gold or platinum from e-waste than mining and processing the ore.
Even the cost of recovering less expensive metals like aluminum and copper has become more economical than virgin mining of these resources. For example, typical cathode-ray tube televisions contain over 400 grams (nearly a pound) of copper and about 230 grams (over half a pound) of aluminum, along with one-fiftieth of an ounce (over half a gram) of gold.
Often discarded after just a few years, cellphones are another valuable source of e-waste. From a metric ton (about 1.1 standard ton) of cellphone batteries, recyclers can retrieve 135-240 kg (about 300-530 lbs.) of cobalt. When it comes to the handsets, approximately 15 kg (33 lbs.) of lithium and 70 kg (154 lbs.) of copper can be reclaimed for each metric ton. Additionally, other electronics within a cellphone can produce about 1kg of silver (2.2 lbs.) and 235g (8.3 oz.) of gold per metric ton. In comparison, each metric ton of raw ore yields an average of 100 g (3.5 oz.) of silver and 2-5 grams (.07-.18 oz.) on average.
In a January 2019 report by the World Economic Forum, however, recycling rates in the United States for e-waste stand at approximately 25 percent, with the rest stored in warehouses due to a lack of options for conveniently recycling it. This means the industry has plenty of room for innovation to drive further growth. Government subsidies and offsets also reduce waste management expenses for collection, labor, energy, transportation, and pulverization, making metal recovery even more profitable for recyclers.
Using Pulverization in Waste Management Metal Recovery
While metals have been recycled for as long as they’ve been utilized, the last half-century has brought new recycling methods that involve less effort to recover greater quantities of valuable metals. Two primary methods are usually used for salvaging metals from e-waste, either de-manufacturing or pulverizing. De-manufacturing involves dismantling e-waste by hand, while pulverizing employs large machines that reduce the need to separate manually and sort e-waste.
Meanwhile, newer methods are being developed to reclaim metals from e-waste. One approach being developed by a Dutch recycling company requires a special bath that reclaims non-ferrous metals from e-waste. This technique involves separating metals with dense water and magnet systems to make them purer. First, using shredding or pulverizing machines breaks down the e-waste through several levels of separation and granulation until metals are ground into a fine powder. This powdery material is then packed in drums and shipped to refiners and smelters for further processing. These reclaimed metals can then be reforged for a variety of purposes.
Many other innovative methods are being tested to recover metal from e-waste as well. Some companies involved in the process simply clean and separate raw metal from e-waste, often utilizing heavy machinery designed to reduce material. One company in New Zealand utilizes microorganisms to extract precious metals like gold from e-waste. A Canadian and a US company have partnered with each other to develop a means to chemically leach gold from e-waste without using cyanide, a chemical typically used to retrieve gold from raw ore.
Along with such new technologies and techniques comes the need to further develop heavy recycling equipment that enhances e-waste pulverization. In waste management, such bulk shredding and pulverizing processes help reduce the need to manually sort e-waste and enable more efficient recycling operations.
Equipment for Pulverization in Waste Management & Recycling
Even with government subsidies, recyclers need to look at the most economical methods when recovering metals from e-waste. Large-scale processing of e-waste requires various machinery to reduce the size of the material to make it more manageable. Hammer mills and rotor mills are especially useful for this purpose, offering a means for shredding and pulverization in e-waste management.
Hammer mills operate by reducing material in a grinding chamber, where hammers repeatedly pulverize e-waste with the help of a spinning shaft. The combination of hammers, impact against the grinding chamber’s walls, and collision with other material helps break e-waste down to be more manageable. Once sufficiently processed, the material passes through a screen and onto the next stage.
Hammer mills offer the following benefits to recyclers as well:
- The hammer mill’s design gives it great flexibility in its configuration. Depending on the size and nature of the e-waste, adjustments can be made to the type and configurations of hammers, as well as to the size of the screens and the mill itself.
- As a significant amount of e-waste requires that recyclers also destroy sensitive data on hard drives and other data storage devices, hammer mills offer a means to pulverize them to make data irretrievable effectively.
- Compared to an industrial shredder, a hammer mill’s hammers, when properly configured, offer the same throughput for a quarter of the cost; additionally, while knives on shredders dull quickly and require monthly change-outs, reversible hammers will last about a year.
Known also as long gap mills, rotor mills utilize an internal spinning rotor moving at high speeds to achieve e-waste pulverization. In waste management, these multipurpose machines work well for recycling operations, as they are robustly built and remain stable during operation.
A rotor mill’s capabilities also include the following:
- Handling a wide variety of materials
- Coats and mixes material at the same time
- Designed to prevent product contamination
- Lowers processing costs
- Produces finely milled material with high throughputs
IPEC produces eight Rotormill models that produce between 30-750 horsepower.