Foundry Industry

Foundries melt ferrous and non-ferrous metals and alloys and reshape them into products at or near their finished shape through the pouring and solidification of the molten metal or alloy into a mould. The foundry industry is a differentiated and diverse industry. It consists of a wide range of installations, from small to very large each with a combination of technologies and unit operations selected to suit the input, size of series and types of product produced in the specific installation. The organisation within the sector is based on the type of metal input, with the main distinction being made between ferrous and non-ferrous foundries. 

The output of non-ferrous metal alloys is still dominated by light metal castings at a share of 75.1 %, despite a decline by 3.5 percentage points compared to the year before. The share of copper alloys went down from 10.1 to 9.8 %, and the share held by the producers of zinc alloys similarly shrank from 8.7 to 7.3 %. The difference was absorbed by miscellaneous non-ferrous metals and processes that are not detailed in the statistics. 

Data on the number of foundries are given in Table 1.3 and Table 1.4. These data show that there has been a general decline in the number of foundries since 1998, with the loss of about 5 % of the existing foundries each year. This decline is also reflected in the employment numbers, as given in Table 1.5 and Table 1.6. 

Country Total Pressure Die Casting Other Light easting Other Heavy metal alloy easting  

Foundries are major recyclers of waste materials. Scrap iron and steel comprise 85 percent or more of the ten million tons of ferrous castings produced each year in the United States. Reclaimed copper, aluminum, lead, tin, zinc, and other metals are also extensively recycled in making nonferrous castings. 

---

Worldwide furfuryl alcohol capacity in 1993 was estimated to be 110,000 metric tons (38). As with furfural, new capacity in developing countries is replacing older capacity in developed countries. China and South Africa have become significant producers of furfuryl alcohol. New plants have been built in Asia and Indonesia as well. Consumption of furfuryl alcohol is spread over the globe the largest use is in the foundry industry which is increasingly moving away from heavily industrialized countries. 

Both FNB and Hot Box appHcations are mature and declining as new technology is being used more and more in the foundry industry. 

Foundry Resins. In the foundry industry, phenoHc resins are used as the binder for sand in the manufacture of sheU molds and cores. The two mating halves are joined by clamps or a bonding agent to form a sheU mold into which the molten metal is poured for castings. The sheU is formed by depositing a resin—sand mix on a hot metal pattern plate. After a certain period the pattern is inverted and the excess resin sand is removed. The sand particles are bonded by an oven cure, and the sheU is ejected from the pattern plate. 

Foundry Industry Scoping Study, Report No. 86-5, Center for Metals Production, Pittsburgh, Pa., Nov. 1986. 

Iron and steel products must meet increasingly strict quaHty standards, requiring the steel and foundry industries to have strict control over their raw materials. Iron and steel producers continually seek scrap of uniform consistent quaHty. Because most forms of obsolete scrap are heterogeneous, scrap consumers rely on scrap origin, reHabiHty of the scrap suppHer, and specifications tailored to their particular plants to assure acceptable quaHty. 

However, much wider appHcation of this alloy in the foundry industry has developed (109). Subsequently, two additional alloys were developed containing 8% aluminum (No. 8) and 27% aluminum (No. 27) (110) compositions are given in Table 21 (89,111,112). These alloys can also be pressure die cast. 

This is the earliest and the most commonly used casting process. It has the advantages of wide metal suitability, low cost, and simple operation. It uses sand as a refractory material. Many types of sand are utilized by the foundry industry. However, because of its wide availability and relatively low cost, silica sand is the one that makes most metal castings. Silica sand is composed of the mineral quartz (Si02), which has a fusion point of approximately 1670°C (3090°F), which is often lowered by the presence of appreciable quantities of minerals with lower fusion points. 

The metal casting industry conventionally divides casting products into ferrous and nonferrous metals, in particular, iron-based, steel-based, aluminum-based, and copper-based castings. The other castings of low fractions include magnesium, lead, zinc, and their alloys. In the U.S., the foundry industry currently produces 11 million tons of metal product per year, with a shipment value of 19 billion. Of them, iron and steel accounted for 84% of metals cast.5 The remaining 15% of foundry operations are concerned with aluminum, copper, zinc, and lead production. Table 4.2 summarizes critical physical and thermal properties of aluminum, iron/steel, and cast iron. 

Table 4.4 presents wastewater flow characterization for the foundry industry by casting metals. Also presented in this table is the level of process water recycle, and the number of plants surveyed with central wastewater treatment facilities for all of the processes at that plant. The discharge flow represents all processes within the specific metal casting facilities. 

Many toxic pollutants were detected in the process wastewaters from metal molding and casting processes. The toxic pollutants detected most frequently in concentrations at or above 0.1 mg/L were phenolic compounds and heavy metals. The pollutants include 2,4,6-trichlorophenol, 2,4-dimethyl-phenol, phenol, 2-ethylhexyl, cadmium, chromium, copper, lead, nickel, and zinc. Each type of operation in the foundry industry can produce different types of pollutants in the wastewater stream. Also, because each subcategory operation often involves different processes, pollutant concentrations per casting metals may vary. 

In the U.S., the foundry industry produces roughly seven to eight million tons of spent sand each year,1 which are available to be recycled into nonfoundry applications. However, less than 15% of... 

Embankment and fill applications are the biggest end-user of spent foundry sand. Natural soils are often composed primarily of sand, clay, and water. Most spent foundry sands have these same constituents, which suggests spent foundry sand as a good fill material. The immediate benefits include saving virgin soil materials and reduce the bottom line of the foundry industry. It is also reported that foundry sand as a fill material may present better performance then conventional materials, including better resistance to freeze-thaw distress. 

Naik, T.R., Foundry Industry Byproducts Utilization, report CBU-1989-01, University of Wisconsin-Milwaukee, WI, February 1989. 

The final quality of a cast metal product is broadly dependent upon any factors which will have an effect on the metal solidification. The mechanical properties of the casting will largely be determined by the cast structure. Any structural defects occurring in the cast product may be transferred to the final product. Thus any process which would reduce defects and improve the metal structure of a cast product would clearly be of benefit to the foundry industry. 

As a final introductory point, it should be noted that there is some confusion within the foundry industry, and its literature, regarding the specific rare earths being employed. Early work in this field was conducted using mischmetal. However, in many instances, only the cerium level was reported in these tests. The presence of the other rare earths was ignored. Even today, the elements most often mentioned are the first four lanthanides lanthanum, cerium, praseodymium and neodymium. That is not to say that the effects of the other elements in the series would not be similar to those of the first four or that they could not be utilized. Rather, their roles have not been studied individually. 

The various rare earths are used in the foundry industry as rare earth silicides, in which the rare earth content is about 30%. Other alloys are used in which the level of rare earths is about 10% (10% cerium, 2% other rare earths) with silicon and iron comprising the bulk of the remaining elements. In the magnesium-ferrosilicon alloys, the rare earths are present in amounts from about 0.1% to 1.0%. These alloys are used differently by the various consumers. However, the effects of the rare earth elements, introduced by whatever means, are the same. 

As far as future research is concerned, one can anticipate a greater concern with the effects of the individual rare earth elements. Effects of cerium as opposed to lanthanum, or the other rare earths, may be more thoroughly researched. Perhaps the list of those elements specified by the foundry industry will eventually embrace those beyond neodymium. Nevertheless, much... 

It is mainly used in the industrial production of rigid polyurethane foams. Many other uses are in the fields of coatings, adhesives, sealants and elastomers such as paints, adhesives, weather-resistant sealing materials and foohvear. There is use also in the production of particle board (bonding of wood) and mould cores for the foundry industry (European Union, 1999). 

Table 5-1 summarizes the waste reduction methods discussed in this chapter, and references concerning them. For more useful information on waste management in the foundry industry, refer to Nagle (1983), and Oman (1988). 

Oman, D.E. 1988. "Waste Minimization in the Foundry Industry." USEPA/Joumal of the Air Pollution Control Association series Waste Minimization. Vol. 38, No. 7 932-940. 

Stephens, W. A., Oman, D. F., and Stolzenburg, T. R. September 1988. Waste Minimization Options for The Ferrous Foundry Industry. RMT, Inc. Madison, WI. 

Stolzenburg, T. R., et al. May 1985. "Analyses and Treatment of Reactive Waste A Case Study in the Ductile Iron Foundry Industry." Purdue Industrial Waste Conference Transactions. West Lafayette, Indiana. 

This paper highlights two of the four chemical treatment methods which have been used quite extensively in the foundry industry. 

A. T. Kearney Company. February 1971. Systems analysis of emission control in the iron foundry industry. USEPA. CPA 22-69-106. Exhibit IV. Reprinted in USEPA, Environmental Assessment of Iron Casting. EPA-600/2-80-021. January 1980. p 17. 

---