C. E. Seeley 1 Glass in Solid Waste Recovery Systems REFERENCE: Seeley, C. E., "Glass in Solid Waste Recovery Systems," Resource Recovery and Utilization, ASTM STP 592, American Society for Testing and Materials, 1975, pp. 114--121. ABSTRACT: The author discusses the basic principles of glass melting and the role of cullet or reclaimed glass from solid waste systems in glass melting. He provides limits or quality specifications for reclaimed glass and explains the reasons for the strictness of the specifications. The author is optimistic for the possible development of new technology for upgrading the reclaimed glass to a more widely acceptable material for reuse in glass manufacture. KEY WORDS: conservation, reclamation, materials recovery, natural resources Contrary to what is shown in many old prints, a small oven with a man reaching in to retrieve a gob of glass is not the way glass is made. Modern glass manufacture uses very large equipment. For example, the furnace shown in Fig. 1 is for continuous operation. Typically, this furnace may be 40-ft long, 20-ft wide, 5-ft deep, and contain 380 tons of molten glass. Th~ melting area within this size furnace is 800 ft 2. Some other furnaces are 150( fU and contain 500 to 600 tons of glass. The purpose of showing this basic glass technology is that in order te understand specifications for glass recovered from municipal solid waste, there must be some understanding of the size and complexity of the equipment employed in converting solid materials to the glassy state, let alone for the fabrication of the glass to finished products. The specifications for the recovered glass are related to the precautions which must be taken to ensure continuous and trouble-free operation in a plant. Glass melting this way is a continuous process and its economics depend on continued introduction of raw materials and the withdrawal of high quality glass. It must be stressed that the raw materials are closely controlled as to their chemical and physical properties. Extreme care is exercised in weighing, mixing, handling, and melting to safeguard the continuous process. The reason is very simple; when one of these huge furnaces become~ Technical director, Glass Science, Anchor Hocking Corporation, Lancaster, Ohio 43130. 114 Copyright(cid:14)9 1975 by ASTM lntcrnational www.astm.org
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`O-I Glass, Inc.
`Exhibit 1026
`Page 001
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`SEELEY ON GLASS RECOVERY 1 1 5 FIG. 1--Two views of a modern glass furnace: (top) (I) regenerator, (2) doghouse, (3) melter, (4) throat, (5) refiner, (6) forehearth, and (7) sidewall blocks; (bottom) (1) regenera- tor, (2) stack, (3) port, (4) crown, (5) melter, (6) throat, (7) metal line, (8) bottom block, and (9) refiner. contaminated, it is much like a huge dam. The reservoir must be drained and refilled or "pulled" continuously until the contamination is removed and the quality is again adequate. Time is the problem in correcting contamination of the reservoir of molten glass in a furnace. Emotions of the operating personnel run high when a furnace is contaminated; the many complex process steps downstream are stopped with large financial losses resulting. Thus, safeguards are necessary so as not to introduce contaminating materials into furnaces. Figure 2 shows broken glass typical of crushed or cracked rejected glassware which is now used as part of the material charged. Note several properties of this material, called "cullet" or reclaimed glass in the industry. (The term cullet also applies to glass reclaimed from waste.) The cullet shown in Fig. 2 is all one color (flint, clear, or crystal), is clean (there is no apparent dirt), there is no organic material (such as paper, rubber, plastics, etc), and there are no metals apparent (such as iron, chromium, or aluminum). Furthermore, there are no solid inorganic materials apparent (such as rocks, stones, and ceramic materials). Above all,
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`O-I Glass, Inc.
`Exhibit 1026
`Page 002
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`1 16 RESOURCE RECOVERY AND UTILIZATION FIG. 2--Typical broken glass (culleO charged to a glass furnace. the chemical constitution is known. This cullet just came from a furnace. The size is usable and manageable; the cullet is neither whole bottles nor dust, and it is dry, or reasonably so. To illustrate some of the contaminants which may be found, the following photographs show cullet in various forms of purity or impurity. Figure 3 shows mixed amber, green, and flint cullet obviously unusable for flint, but it is useful in both amber and green, to a certain extent. Figure 4 shows the glass fraction from the Bureau of Mines, Incinerator Residue Recovery, process which was used to produce amber glass in one of our production furnaces in November 1971. In terms of material charge, 4.8 percent of it was this cullet. In terms of glass after fusion loss, 5.5 percent was this recovered cullet. The recovered glass contained fine-grained refractory and aluminum particles which resulted in bubbles and solid inclusions in the finished glass. Although the refractory particle caused solid inclusions, they did not, in this case, harm the ware quality. The bubbles did give an unsightly appearance. Figure 5 shows a partially separated fraction of solid waste materials known as the nonmagnetic fraction. The sample contains dirt, aluminum, ceramics, and other materials. This photo illustrates an unuseable material or what cullet is not. Figure 6 is a photograph of rocks and ceramics, or refractory materials which contaminate recovered glass and which can cause solid inclusions in glass. One such inclusion is shown in Fig. 7.
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`O-I Glass, Inc.
`Exhibit 1026
`Page 003
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`SEELEY ON GLASS RECOVERY 1 1 7 FIG. 3--Mixed color cullet useable to manufacture new amber or green glass. FIG. 4--Glass cullet reclaimed from incinerator residue.
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`O-I Glass, Inc.
`Exhibit 1026
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`1 18 RESOURCE RECOVERY AND UTILIZATION FIG. 5--A glass-rich fraction from processed municipal solid waste. It is not useable cullet. FIG. 6--Refractory materials found in reclaimed cullet.
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`O-I Glass, Inc.
`Exhibit 1026
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`SEELEY ON GLASS RECOVERY 1 1 9 FIG. 7--Solid inclusion in glass caused by inclusion of refractory material in the cullet. GCMI Guideline Specifications for Reclaimed Glass The reclaimed glass fraction or cullet from any source--to be use- ful--must yield acceptable final glass properties and possess material handling properties consistent with equipment already in the glass plant. The container glass industry, through the Glass Container Manufacturers Institute (GCMI), has developed the GCMI Guideline Specification for glass reclaimed from municipal solid waste. Following is an explanation of the salient points of the specification. The Cullet Should Have Good Materials Handling Capabilities The cullet is not to show drainage liquids from a sample. If this requirement is not met, the cullet raw material would freeze in winter and, in some cases in conjunction with other glass batch materials, possibly set up like cement in bins or buckets under conditions of heat and long storage time. The cullet screen sizing is to be zero percent on a 2-in. bar screen. Obviously, whole glass items hinder handling and mixing. Powdery and dusty materials do not handle well in bulk systems but at this moment are not covered by the specification. The Cullet Should Yield Glass of Acceptable Color The content of organic materials other than paper and plastics cannot exceed 0.05 percent. The content of paper and plastics cannot exceed 0.05 percent. The reason is that wood, paper, plastics, and similar organic materials are reducing agents in glass and, as such, will reduce iron compounds to form a greenish yellow to amber color, now objectionable to consumers. Organic materials may also decompose and form a bubble or blister in the glass, as shown in Fig. 8. The content of magnetic material cannot exceed 0.05 percent and must be less than 1/4 in. in size. Iron metal causes an unsightly green to greenish
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`O-I Glass, Inc.
`Exhibit 1026
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`120 RESOURCE RECOVERY AND UTILIZATION FIG. 8--Blister in glass caused by inclusion of organic material which decomposed during melting of the glass, yellow. If pieces are larger than (cid:1)88 in. in size, they do not melt and produce streaks of amber or green color. The GCMI specification takes into account the tolerance of a glass tank to foreign colors. The color specification is shown in Table 1. TABLE l--Color sorting of mixed glasses in cullet. Percentage in Cullet Amber Flint Green Amber 90-100 0-5 0-35 Flint 0-10 95-100 0-15 Green 0-10 0-1 50-100 The Cullet Should Yield Acceptable Quality Glass The maximum content of solid inorganic materials other than metals cannot exceed 0,05 percent with a maximum size of ~A in. This refers to dirt, rocks, and stones which may yield "stones" (solid inorganic inclusions) or other unsightly defects in glass. To avoid stones, the maximum content of refractory materials is no more than two particles greater than 40 mesh or 20 particles in the range of from 40 to 60 mesh screen size. The problem with refractory or ceramic materials is that above 60 mesh size they do not melt and remain as solids or stones in glass and the resultant glassware is not saleable. Sand used in glass making, for example, is less than 20 mesh to ensure rapid and complete melting. Fired refractories or ceramic particles must be even smaller in size. The maximum content of nonmagnetic metals is 0.015 percent no larger than (cid:1)88 in. in size. This is directed principally to aluminum separation. Aluminum in quantity at glass melt temperatures will reduce the silica (SiO2)
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`O-I Glass, Inc.
`Exhibit 1026
`Page 007
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`SEELEY ON GLASS RECOVERY 121 in glass to silicon (Si). If the size of the aluminum pieces is large enough, the silicon will appear as tiny round particles (shown in Fig. 9) in the glass and render it unsaleable. FIG. 9--Silicon stone in glass caused by inclusion of aluminum in the cullet. Summary The GCMI specifications are demanding and the glass industry has been asked to relax them. At this point, it is not known how to do so. However, some direction is emerging. We have seen municipal solid waste go from landfill to valuable recovered materials by enterprising groups, such as the National Center for Resource Recovery, Inc., the Bureau of Mines, and others using new physical and chemical separation techniques. These activities are expected to continue with increasing attention to technological problems and economics. The glass container industry expects to work hand-in-hand with each group to secure the recovered glass and convert it to usable products. In the future, large increases in the cost of raw materials are expected, thus raising the economic value of glass in solid waste. This trend will permit investment in new equipment for processing cullet to achieve higher quality recovered glass. There is no point in dwelling on the subject of secondary products which can be made using theglass fraction from solid waste, but several interesting candidate products have been developed. Information on these is available from the Glass Container Manufacturers Institute (Washington, D.C.) In most cases, quality requirements for the recovered glass are lower than outlined here for reuse in glass melting and container manufacture.
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`Copyright by ASTM Int'l (all rights reserved); Tue Jan 14 10:36:00 EST 2020
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`Ashley Schoenrock (Owens Illinois) pursuant to License Agreement. No further reproductions authorized.
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`O-I Glass, Inc.
`Exhibit 1026
`Page 008
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