The Horsehead Resource Development Co., Inc. (HRD), flame reactor system is a patented, hydrocarbon-fueled, flash-smelting system that treats residues and wastes contaminated with metals (see figure below). The reactor processes wastes with hot (greater than 2,000°C) reducing gases produced by combusting solid or gaseous hydrocarbon fuels in oxygen-enriched air.
In a compact, low-capital cost, water-cooled reactor, the feed materials react rapidly, allowing a high waste throughput. The end products are glass-like slag; a potentially recyclable, heavy metal-enriched oxide; and in some cases, a metal alloy. The glass-like slag is not toxicity characteristic leaching procedure (TCLP) leachable. The volatile metals are fumed and captured in a baghouse; nonvolatile metals partition to the slag or may be separated as a molten alloy. Organic compounds should be destroyed at the elevated temperature of the flame reactor technology. Volume reduction (of waste to slag plus oxide) depends on the chemical and physical properties of the waste.
In general, the system requires that wastes be dry enough (less than 5 percent total moisture) to be pneumatically fed and fine enough (less than 200 mesh) to react rapidly. HRD claims larger particles (up to 20 mesh) can be processed; however, the efficiency of metals recovery is decreased. The prototype system has a capacity of 1 to 3 tons per hour. According to HRD, individual units can be scaled to a capacity of 7 tons per hour.
The flame reactor system can be applied to granular solids, soil, flue dusts, slags, and sludges that contain heavy metals. HRD claims that the flame reactor technology has successfully treated the following wastes: (1) electric arc furnace dust, (2) lead blast furnace slag, (3) soil, (4) iron residues, (5) primary copper flue dust, (6) lead smelter nickel matte, (7) zinc plant leach residues and purification residues, (8) brass mill dusts and fumes, and (9) electroplating sludges.
The system has treated wastes with the following metal species and concentrations: zinc (up to 40 percent); lead (up to 10 percent); chromium (up to 4 percent); cadmium (up to 3 percent); arsenic (up to 1 percent); copper (up to 8 percent); cobalt; and nickel. According to HRD, the system can also treat soils that are contaminated with a variety of toxic organics.
This technology was accepted into the SITE Demonstration Program in 1990. Currently, the prototype flame reactor system operates as a stationary unit at HRD's facility in Monaca, Pennsylvania. EPA and HRD believe that a mobile system could be designed and constructed for on-site treatment of hazardous waste.
The SITE demonstration was conducted in March 1991 using secondary lead smelter soda slag from the National Smelting and Refining Company (NSR) Superfund site in Atlanta, Georgia. The demonstration was conducted at the Monaca, Pennsylvania facility under a Resource Conservation and Recovery Act research, development, and demonstration permit. This permit allows treatment of wastes containing high concentrations of metals, but only negligible concentrations of organics.
The major objectives of the SITE technology demonstration were to investigate the reuse potential of the recovered metal oxides, evaluate the levels of contaminants in the residual slag and their leaching potential, and determine the efficiency and economics of processing.
A 30,000-standard-tons-per-year commercial flame reactor system processes steel mill baghouse dust (K061) at the North Star Steel Mini Mill near Beaumont, Texas. The plant was activated June 1, 1993 and is reported to be performing as designed.
Approximately 72 tons of NSR waste material were processed during the demonstration. Partial test results are shown in the table below.
Metal Concentration Ranges in Influent and Effluent |
|||
Waste |
Effluent |
Oxide |
|
|---|---|---|---|
| Arsenic | 428-1,040 |
92.1-1,340 |
1,010-1,170 |
| Cadmium | 356-512 |
<2.3-13.5 |
1,080-1,380 |
| Copper | 1,460-2,590 |
2,730-3,890 |
1,380-1,780 |
| Iron | 95,600-130,000 |
167,000-228,000 |
29,100-35,600 |
| Lead | 48,200-61,700 |
1,560-11,400 |
159,000-184,000 |
| Zinc | 3,210-6,810 |
709-1,680 |
10,000-16,200 |
All effluent slag passed toxicity characteristic leaching procedure criteria. The oxide was recycled to recover lead. The Technology Evaluation Report (EPA/540/5-91/005) and the Applications Analysis Report (EPA/540/A5-91/005) are available from EPA.
EPA PROJECT MANAGER:
Marta K. Richards
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7692
Fax: 513-569-7676
TECHNOLOGY DEVELOPER CONTACT:
Regis Zagrocki
Horsehead Resource Development Co., Inc.
Field Station - East Plant
Delaware Avenue
Palmerton, PA 18071
610-826-8818
Fax: 610-828-8872