Each year, Canada landfills more than 140,000 tonnes of electronic waste, according to a study published by Environment Canada in 2003. Experts believe that nearly 75 percent of obsolete electronic equipment is in storage because of the uncertainty surrounding proper disposal. Fortunately, lawmakers are implementing government-mandated infrastructures for recycling end-of-life electronic equipment.
Personal computers (PCs), cathode ray tube (CRT) and liquid crystal display (LCD) monitors and televisions account for more than 60 percent of Canada’s disposed electronic waste. They contain such hazardous components as lead and mercury. In fact, the average PC and monitor, for example, are comprised of 6.299 percent lead and 0.002 percent mercury. When multiplied by the number of these products reaching end-of-life, these figures equate to 3,097.7 tonnes of lead and one tonne of mercury sent to landfills in 2002!
Astonishingly, according to the same Environment Canada study, less than eight percent of disposed electronic equipment is actually recycled. With the number of obsolete electronic equipment climbing at a staggering rate, the need for increased public awareness is ever prevalent.
The Onyx system
“When broken down, the various parts of electronic equipment can be either reused or recycled,” says Paul Conca, operations manager for Onyx Environmental Services’ (OES) Electronics Recycling Division. “Hazardous substances, like lead and mercury, are released into the soil, water and air through landfill leachate and incinerator emissions. In our plant CRTs, LCDs, televisions and other electronic equipment undergo a six-step recycling and reuse process. This ensures that these toxins are kept out of our environment.”
The mercury found in electronic equipment is recycled through a distilling or retort process, where the phosphor powder is heated to and kept at 650-850C, turning the mercury into vapor. Vacuum pumps are then used to capture the resulting vapor in condensing units. In the condensing unit, the vapor is chilled to Zero degrees Celsius, bringing the mercury back into a liquid state. From here, the metallic liquid mercury drops out of the air stream and is collected for reuse.
At electronics recycling facilities the mercury found in spent lamps and obsolete liquid crystal displays can be recycled on site into 99.9 percent pure mercury. If sent offsite, it can be triple distilled to make it a technical grade (99.999 percent pure) of mercury. The recycled mercury has a myriad of different uses, from pharmaceuticals to testing equipment. It is resold and put back into the market.
“Lead is reclaimed from leaded glass in CRTs and other lead containing scrap by a process referred to as secondary lead smelting,” says Conca. The lead scrap is fed to a melt furnace where the elemental lead is melted. Here, the lead contained in lead compounds, such as lead sulfate, can also be reduced to elemental lead and melted. In order to remove the remaining sulfates and other impurities, fluxes are added to the molten lead. Because glass is a silica-based material, silica is often used as a flux during the smelting process.
CRTs are de-manufactured on site at recycling facilities into separate recyclable components. First, the CRT is removed from the monitor or television. A bald CRT is comprised of stainless steel, a copper yolk and leaded glass. Next, all of the non-glass materials are removed from the exterior of the CRT, leaving a bald CRT. Non-glass materials include ferrous and non-ferrous metals, such as low grade steel and various copper bearing materials, and plastics. Metals and plastics are separated and shipped off site as a commodity. Mixed plastics are recycled in low-grade plastics, through shredding, grinding and melting. Ferrous metals, or those metals derived from iron, are sold for metal value, while nonferrous metals, such as copper bearing metals, are collected, sorted and smelted. After the vacuum has been released, the bald CRT is segregated and shipped off site to an approved leaded-glass recycler.
Written by Scott Thibodeau, marketing manager, Onyx Environmental Services, Electronics Recycling Division, Port Washington, Wisconsin, USA. Contact Scott at SPThibodeau@onyxsp.com