This group includes facilities engaged in exploration for, and operation of oil and natural gas fields. Activities include locating, drilling and completing wells, operation of separators, emulsion breakers and desilting equipment, and all other activities up to the point of shipment. Drilling operations rely heavily on the use of barite, which is employed as a weighting agent in drilling muds.
4.1.7 PETROLEUM REFINING AND RELATED INDUSTRIES (SIC 29, 49)
Petroleum refining establishments produce gasoline, fuel oils, lubricants and other products from crude petroleum. Related industries include production of asphalt and tar mixtures for paving and roofing applications; coke, fuel briquette, powdered and packaged fuel production, and scrubbing and distribution of natural gas.
Tetraethyl lead is used, although less and less each year, as a gasoline antiknock additive. Much of the leaded gasoline is exported for use outside of the country. Lead-bearing waste streams can result both from the manufacture and use of leaded gasoline. Various heavy metals are employed as catalysts in petroleum refining. Coke can be contaminated with small concentrations of vanadium, nickel and other metals. Finally, vanadium is used in scrubbing solutions for the removal of hydrogen sulfide from natural gas. Poor vanadium recovery can result in a hazardous metal-bearing waste.
4.1.8 INDUSTRIAL MACHINERY (SIC 35)
Industrial machinery manufacturing includes production of engines, turbines, farm construction, mining, and materials handling equipment, metalworking machinery and refrigeration equipment. Vanadium is used in dies and high speed tools to increase high temperature abrasion resistance, and in crankshafts and gears to add shock and wear resistance. Chromium is found in steel and iron castings, tools, stainless and high speed steels. Silver is employed in welding and brazing alloys, especially in air conditioning and refrigeration equipment. Antimony is used in tin and lead alloys in the manufacture of bearings and power transmission equipment. Copper is employed in air conditioning systems, farm machinery, and other equipment. Nickel-bearing steels are frequently employed for strength. Stainless steel, which contains nickel, has important corrosion and heat resistance properties. Cobalt is employed in hardfacing alloys, high speed steels, machining tools, and construction and mining equipment. Zinc and cadmium provide corrosion protection. Zinc is also used in die castings and brass parts. All of these metals can be released into waste streams, especially through plating and surface treatment operations.
4.1.9 ELECTRICAL AND ELECTRONIC MACHINERY, EQUIPMENT, INSTRUMENTATION AND SUPPLIES (SIC 36, 38)
This group includes facilities engaged in the manufacturing of products for the generation, storage, transmission, transformation and utilization of electrical energy, and products for measuring and controlling processes. Products include motors, generators, controls, welding equipment, household appliances, electrical lighting and wiring, communications and computer equipment, electronic components and accessories, batteries, and other products.
Beryllium connections and contacts are employed for switchgear and relays. Beryllium oxide is used as substrata for electronic circuits. Cadmium is used in television and fluorescent light phosphors. Cadmium, nickel and mercury are employed in batteries such as "nicad" cells and mercury cells. Mercury is used in fluorescent lamps, electrical switches, and outdoor lamps, as well as instruments for measuring pressure, temperature, and density. Selenium is employed as a photoreceptor in copying machines, and as a semiconductor in rectifiers. Lead applications include lead acid storage batteries, a component in color television glass, and, in its oxide form, use as a dielectric material.
Silver is employed for low resistance electrical contacts and conductors, and in silver cell batteries. Antimony is used in lead acid storage batteries to improve the workability of the lead and lead oxides. Copper and copper alloy wires, connectors, cables, switches, printed circuit boards, and transistor and rectifier bases are common throughout the industry. Nickel is used in high resistance heating elements, glass-to-metal seals, batteries, and specialty steels for power generation equipment Household appliances employ stainless and electroplated steel containing nickel.
Cobalt finds applications in permanent magnet production, and in sealing glass to metal. Zinc is used in galvanized and ferrous castings, die-cast parts, brass wire, dry cell battery cases, soldering flux, CRT phosphors, and zinc ferrite inductors.
Transportation equipment manufacturers produce vehicles for movement of passengers and cargo by land, air, and water. Important products include motor vehicles, aircraft, guided missiles and space vehicles, ships, boats, and railroad equipment.
Beryllium metals and alloy are used in aircraft, satellites and spacecraft, and in navigation equipment. Chromium is employed in steel and iron castings, and in stainless steels. Lead is used in batteries, engine bearings, wheel weights, and solder for automotive use. Copper alloys find applications in radiators, brake linings, tubes, bearings and bushings. Copper provides corrosion and biofouling resistance in marine vessels. Nickel alloys are used in aircraft for structural airframes and gas turbines. Nickel electroplated bumpers and wheel covers are common in automotive vehicles. There has been increased use of vanadium high strength low alloy (HSLA) steels in cars and aircraft engines, wing structures and undercarriages. Cobalt is used in jet engine parts and in turbines. Zinc is employed in die-cast components and for corrosion protection for automobiles. Zinc is also a component of the brass found in radiators and tubing. Zinc oxide is employed in the manufacture of rubber for tires.
4.1.11 PRINTING AND PHOTOGRAPHIC PROCESS INDUSTRIES (SIC 27, 386, 7819)
These groups include establishments engaged in printing by one or more of the common practices such as letterpress, lithography, gravure or screen; and in photographic processes, specifically developing.
Silver is used in photographic film and paper, X-ray film, and photo-offset printing plates, and is a constituent of aqueous waste streams from developing processes.
4.1.12 WOOD PRESERVING (SIC 2491)
Businesses engaged in treating wood to prevent decay and to protect against insects and fire are included in this group. Poles, piles, and foundation plates are typical products requiring wood preserving.
Chromium copper arsenate is a commonly used preservative for softwood. To a lesser extent, ammoniacal copper arsenate is also used.
4.1.13 ELECTRIC POWER GENERATION AND TRANSMISSION (SIC 491)
Facilities engaged in the generation, transmission and distribution of electric energy are included in this group. Chromium chemicals are employed as corrosion inhibitors in cooling and heating systems. Vanadium steels are employed in pipeline construction. Beryllium is used in nuclear electric energy generating facilities for various equipment.
Specific activities common to many of the industries described above have been identified that are responsible for generating the major share of the State's hazardous metal-bearing wastes. Figure 4-1 depicts a flow chart of waste generating operations used in industries involved in metalworking of one sort or another for the formulation of their products. These operations include thermal metalworking, machining, surface preparation, treatment and plating, removal of process chemicals from the product, and coating. These operations are examined in Sections 5.0 through 9.0; currently used as well as promising waste reduction approaches for each are identified and discussed.
Section 10.0 discusses auxiliary operations in manufacturing facilities that generate metal-bearing wastes, and methods for minimizing these waste products. Examples include cooling system cleaning, and general operating practice improvements that result in waste minimization.
There also exist non-metalworking processes that are responsible for generating considerable hazardous metal waste in California. These include, among others, aspects of printed circuit board fabrication, photographic processes used in photofinishing and printing industries, as well as certain refinery activities, such as sulfur recovery from tail gases. Waste minimization strategies for these activities are discussed in Section 11.0.
Typical Sequential Metal Product Operations Generating Hazardous Metal Wastes
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VOC & Paniculate Emissions
WORKING STOCK AND RAW MATERIALS INCLUDING II ETALS
(Cleaning & Stripping)
Surface Treatment & Plating
(Chromating, Case Hardening,ale.)
(Electro- and Electro less Plating)
Process Chemical Removal
(Drainage & Rinsing)
(Paint Manufacturing & Application)
Process Solutions f
Process i F Solutions Was(ewater
USEPA 1986. Waste Minimization Issues and Options. Volume 2. Appendix B: Process Studies. Prepared by Jacobs Engineering Group for USEPA, Office of Solid Waste, Waste Treatment Branch. EPA/530-SW-86-042.
Wapora, Inc. 1975. Assesment of Industrial Hazardous Waste Practices. Paint and Applied Product Industry. Contract Solvent Reclaiming Operations, and Factory Application of Coatings. U.S. Environmental Protection Agency, EPA-530-SW-119C.
WASTE MANAGEMENT IN FOUNDRY ACTIVITIES
In the United States, most metal casting involves the use of secondary (recycled) metals. Scrap metal along with fluxing agents are charged to an electric arc furnace (EAF), or an induction or cupola furnace for melting. In cupola furnaces, coke in the metal feed is used as a source of fuel. Inside the furnace, fluxing agents help to remove nonmetallic impurities such as sulfur from the melt. The mixture of fluxing agent and impurities, known as slag, floats on the surface of the molten metal and protects it from oxidation. In some operations, degassing of the metal is performed either under vacuum or by purging with inert gas such as nitrogen or argon. The role of degassing is to remove oxygen from the metal.
Once the molten metal has been treated to achieve the desired properties, it is poured into a mold or cast. Casting materials may include silica sands, chromite sands, heat-cured furan or phenolic resins, or many other heat resistant materials. These materials are often mixed with a clay or organic resin binder and pressed around a pattern of the part. When cured, the pattern is removed leaving a cavity in the sand mold. In some casting operations, the pattern remains inside the mold and is burned-out by the molten metal. Once the poured metal has cooled, the mold is broken apart and the casting removed. The metal part may then be subjected to a sand blasting so as to remove any casting sand, metal flash, or oxide. In addition to job shops, many facilities engaged in metal fabrication do their own casting.
The major wastes generated in the secondary metal industry include baghouse or scrubber wastes associated with the control of air emissions from the furnace, hazardous slags produced during the melting and treatment operation of certain metals, and spent casting sands which can no longer be reused. Sprue, risers, and reject castings are usually returned to the furnace for remelting. Slags which contain high levels of ferrous metal are usually recycled onsite, while slags associated with nonferrous casting are normally sent to an offsite reclaimer.
During the melting process, a small percentage of each charge is converted to dust or fume and collected by means of baghouses or wet scrubbers. Depending on the types of metal being melted, this dust will contain varying amounts of zinc, lead, nickel, cadmium, and chromium. Carbon-steel dusts tend to be high in zinc and lead due to the use of galvanized scrap while stainless steel dusts are high in nickel and chrome. Dusts associated with nonferrous metal production may include copper, aluminum, lead, tin, and zinc. While most steel dust is encapsulated and disposed of in a regulated landfill, many of the nonferrous dusts are sent to a recycler for recovery of metal because of the greater value of this material. Ways to reduce the volume or toxicity of steel dusts include the following source reduction, recycling and treatment methodologies:
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