Recycling batteries

Modern batteries are often promoted on their environmental qualities. lithium-based batteries fall into this category. While nickel-cadmium presents an environmental problem on careless disposal, this chemistry continues to hold an important position among rechargeable batteries. Power tools are almost exclusively powered by nickel-cadmium. Lead-acid batteries continue to service designated market niches and these batteries also need to be disposed of in a proper manner. lithium-ion would simply be too fragile to replace many of these older, but environmentally unfriendly, battery chemistries.

Our quest for portability and mobility is steadily growing, so is the demand for batteries. Where will the mountains of batteries go when spent? The answer is recycling.

The lead-acid battery has led the way in recycling. The automotive industry should be given credit in organizing ways to dispose of spent car batteries. In the USA, 98% of all lead acid batteries are recycled. In comparison, only one in six households in North America recycle batteries.

Careless disposal of nickel-cadmium is hazardous to the environment. If used in landfills, the cadmium will eventually dissolve itself and the toxic substance can seep into the water supply, causing serious health problems. Our oceans are already beginning to show traces of cadmium (along with aspirin, penicillin and antidepressants) but the source of the contamination is unknown.

Although nickel-metal-hydride is considered environmentally friendly, this chemistry is also being recycled. The main derivative is nickel, which is considered semi-toxic. Nickel-metal-hydride also contains electrolyte that, in large amounts, is hazardous. If no disposal service is available in an area, individual nickel-metal-hydride batteries can be discarded with other household wastes. If ten or more batteries are accumulated, the user should consider disposing of these packs in a secure waste landfill.

Lithium (metal) batteries contain no toxic metals, however, there is the possibility of fire if the metallic lithium is exposed to moisture while the cells are corroding. Most lithium batteries are non-rechargeable and are used in cameras, hearing aids and defense applications. For proper disposal, the batteries must first be fully discharged to consume the metallic lithium content.
lithium-ion batteries used for cell phones and laptops do not contain metallic lithium and the disposal problem does not exist. Most lithium systems contain toxic and flammable electrolyte.

In 1994, the Rechargeable Battery Recycling Corporation (RBRC) was founded to promote recycling of rechargeable batteries in North America. RBRC is a non-profit organization that collects batteries from consumers and businesses and sends them to recycling organizations. Inmetco and Toxco are among the best-known recycling companies in North America
Europe and Asia have had programs to recycle spent batteries for many years. Sony and Sumitomo Metal in Japan have developed a technology to recycle cobalt and other precious metals from spent lithium-ion batteries.

Battery recycling plants require that the batteries be sorted according to chemistries. Some sorting must be done prior to the battery arriving at the recycling plants. nickel-cadmium, nickel-metal-hydride, lithium-ion and lead acid are placed in designated boxes at the collection point. Battery recyclers claim that if a steady stream of batteries, sorted by chemistry, were available at no charge, recycling would be profitable. But preparation and transportation add to the cost.

The recycling process starts by removing the combustible material, such as plastics and insulation, with a gas fired thermal oxidizer. Gases from the thermal oxidizer are sent to the plant's scrubber where they are neutralized to remove pollutants. The process leaves the clean, naked cells, which contain valuable metal content.

The cells are then chopped into small pieces, which are heated until the metal liquefies. Non-metallic substances are burned off; leaving a black slag on top that is removed with a slag arm. The different alloys settle according to their weights and are skimmed off like cream from raw milk.

Cadmium is relatively light and vaporizes at high temperatures. In a process that appears like a pan boiling over, a fan blows the cadmium vapor into a large tube, which is cooled with water mist. This causes the vapors to condense and produces cadmium that is 99.95 percent pure.

Some recyclers do not separate the metals on site but pour the liquid metals directly into what the industry refers to as 'pigs' (65 pounds) or 'hogs' (2000 pounds). The pigs and hogs are then shipped to metal recovery plants. Here, the material is used to produce nickel, chromium and iron re-melt alloy for the manufacturing of stainless steel and other high-end products.

Current battery recycling methods requires a high amount of energy. It takes six to ten times the amount of energy to reclaim metals from recycled batteries than it would through other means.

Who pays for the recycling of batteries? Participating countries impose their own rules in making recycling feasible. In North America, some recycling plants bill on weight. The rates vary according to chemistry. Systems that yield high metal retrieval rates are priced lower than those, which produce less valuable metals.

Nickel-metal-hydride yields the best return. It produces enough nickel to pay for the process. The highest recycling fees apply to nickel-cadmium and lithium?ion because the demand for cadmium is low and lithium?ion contains little retrievable metal.

Not all countries base the cost of recycling on the battery chemistry; some put it on tonnage alone. The flat cost to recycle batteries is about $1,000 to $2,000US per ton. Europe hopes to achieve a cost per ton of $300US. Ideally, this would include transportation, however, moving the goods is expected to double the overall cost. For this reason, Europe sets up several smaller processing locations in strategic geographic locations.

Significant subsidies are sill required from manufacturers, agencies and governments to support the battery recycling programs. This funding is in the form of a tax added to each manufactured cell. RBRC is financed by such a scheme.

Important: Under no circumstances should batteries be incinerated as this can cause explosion. If skin is exposed to electrolyte, flush with water immediately. If eye exposure occurs, flush with water for 15 minutes and consult a physician immediately

About the Author
Isidor Buchmann is the founder and CEO of Cadex Electronics Inc., in Vancouver BC.
Mr. Buchmann has a background in radio communications and has studied the behavior of rechargeable batteries in practical, everyday applications for two decades. Award winning author of many articles and books on batteries, Mr. Buchmann has delivered technical papers around the world.
Cadex Electronics is a manufacturer of advanced battery chargers, battery analyzers and PC software. For product information please visit www.cadex.com.