Cadmium Recovery Inmetco

Figure 2. Nickel-Cadmium Batteries Collected for Recycling in North America


The International Metals Reclamation Company, Inc. (INMETCO), located in Ellwood City, Pennsylvania, began operations in 1978 as a metals recycler. INMETCO is committed to the concept of sustainable development, which requires balancing the need for economic growth with good stewardship in the protection of human health and the natural environment. Since 1978, INMETCO has been actively involved in the reclamation of various metallic secondary materials, including nickel, chromium, iron, molybdenum, cobalt and cadmium. Most of the secondary materials containing these metals reclaimed at INMETCO originate in the stainless steel industry, but since the introduction of the Cadmium Recovery Facility at INMETCO in 1995, a significant portion of the secondary materials also originate from spent batteries, especially NiCd's. In 1991, the U.S. EPA announced that the High Temperature Metals Recovery (HTMR) Process used by INMETCO was the Best Demonstrated Available Technology (BDAT) for treating electric arc furnace dust (EPA Waste Code K061), pickling wastes (K062), waste water treatment sludges from electroplating operations (F006), and spent nickel cadmium batteries (D006).

INMETCO's High Temperature Metals Recovery process reclaims the nickel, chromium, iron, molybdenum and cobalt from the secondary wastes indicated above and produces a remelt alloy in cast pig form, weighing 25-30 pounds. The remelt alloy is shipped to most of the stainless steel manufacturers in the United States, as well as certain other international companies, for use as raw material feedstock in the production of more stainless steel. As an ISO 9002 certified facility, INMETCO, a fully permitted facility, is the only High Temperature Metals Recovery facility in North America dedicated to the recovery of nickel, chromium, iron and molybdenum from both hazardous and non-hazardous wastes.

In the Cadmium Recovery Facility, INMETCO reclaims cadmium from spent NiCd batteries and produces a high purity cadmium shot known as Cadmet A or Cadmet B. The majority of recycled cadmium is returned to the battery industry for the production of new nickel-cadmium batteries. INMETCO's Cadmium Recovery Facility began operations in 1995, and since that time, INMETCO has been the only true recycler of NiCd batteries in North America.

High Temperature Metals Recovery Process

The INMETCO HTMR process uses industry standard equipment in a unique and patented process. At the heart of the INMETCO process is the use of coal or carbon products to reduce oxidized metal wastes to their metallic form in a rotary hearth furnace. The technology has been adapted to produce direct reduced iron from ore concentrates, carbon steel waste products, or a combination of these materials. The

High Temperature Metals Recovery process consists of four basic steps: (1) feed preparation, (2) reduction, (3) smelting, and (4) casting.

Feed Preparation - In the feed preparation phase, both solid and liquid wastes are drawn from storage containers and blended with other additives to form pellets for further processing. Coke or coal and/or other secondary carbon products are used as a reduction agent in the process, and are added at this point. A screw conveyer mixes and transports the resulting mixture to a pelletizing disk. Here, secondary liquids containing nickel and chromium are added to form green pellets. In the feed preparation phase, vented or industrial NiCd batteries are drained. Their electrolyte is used as a reagent in the wastewater treatment plant. The positive nickel plates are shredded and fed into the rotary hearth furnace and subsequently into the electric arc furnace for nickel and iron recovery. The negative cadmium plates are processed in the cadmium recovery facility.

Reduction - The blended feed materials are transferred to the rotary hearth furnace operating at approximately 1260 degrees Fahrenheit. In the rotary hearth furnace, some of the carbon added during the blending stage reacts with the oxygen in the waste to reduce the metal bearing wastes to their metallic form. Gas produced in the process is discharged to a wet scrubber system. The scrubber water is then treated in a wastewater treatment plant on-site. This water is recycled back to the plant for reuse. The only products released to the atmosphere are essentially water vapor and the usual products of combustion.

Smelting - The hot reduced feed is transferred from the rotary hearth furnace to the electric arc furnace where the third major process occurs. The electric arc furnace performs a smelting operation to produce a nickel, chromium, and iron alloy. Lime, silica, magnesia, and alumina separate to form a slag/metal bath. Metal and slag are tapped periodically from the bath. The slag is collected and hauled to a slag cooling area. This non-hazardous slag may subsequently be used in building roads, parking lots, and commercial driveways.

Casting - Casting is the final step. Molten metal is cast into pigs using a twin strand pig caster. The bars of metal formed in the molds are called "pigs". Pigs are grouped into lots of approximately 20 tons and are shipped to stainless steel manufacturers to be used as remelt alloy for the production of stainless steels.

Cadmium Recovery Facility

NiCd consumer cells are small, sealed-cell batteries, which are most familiar to consumers, are rechargeable battery power packs for cordless drills, cellular and cordless phones, camcorders, household appliances, and battery-operated toys. The batteries in power packs are typically contained in a plastic case, which must be removed prior to cadmium extraction. The plastic is removed in a two-step process including INMETCO's patented rotary thermal oxidizer. In this process, the plastic, paper, and moisture are removed without fuming off cadmium.

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DIY Battery Repair

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