System for recovery of salvageable ferrous and non-ferrous metal components from incinerated waste materials

The present invention relates in general to a system and method for recovery of salvageable materials from refuse, and specifically to a system and method for the recovery of ferrous and non-ferrous metal components from incinerated waste materials, The present invention further relates to a crusher for selectively comminuting friable material without comminuting associated malleable material.

In recent years, there has been a dramatic increase in the volume and variety of solid waste products requiring disposal by both the private and public sectors. Such solid waste products have in the past been burned in open incinerators. However, due to current regulatory and environmental laws and regulations, incineration of solid waste has been restricted to a significant extent in many geographic areas and in fact is prohibited in many urban areas today.

Disposal of solid waste products in sanitary landfills is a frequently used alternative disposal method. However, many existing landfills are reaching their capacity and additional replacement clean landfills have not been approved by local regulatory agencies and authorities due to existing environmental laws and regulations and due to an actual shortage of land in some geographic areas.

Recovery of salvageable and recyclable materials, of course, reduces the amount of waste products that must be disposed. Apparatus and methods for recovery of salvageable and recyclable components, such as glass, plastics, non-ferrous, and ferrous materials, from solid waste products are known in prior art, eg, US Patent Nos 3,549,092; 3,659,396; 3,788,568; 3,790,091; 3,973,736; 4,020,992; 4,070, 278; 4,083,774; 4,337,900; 4,362,276; and 4,387,019. Such recovery apparatus and methods are used in the recovery of solid waste products prior to disposal of the solid waste products. However, ferrous and non-ferrous metal components are generally not fully recovered by such prior art apparatus and method and carryover with the byproducts from the incineration of the solid waste products.

In addition, the quality of the recovered ferrous and non-ferrous products varies widely due to the incinerated waste product carryover, the extreme variability of the moisture content in both the waste material and the residue ash, and the fused aggregate of carbonaceous incinerated byproducts.

US Patent No 2,971,703 proposes a system for separating magnetic and non-magnetic metal components from steel plant slag; this system deals with a relatively uniform mixture of incoming material, and makes use of a throwing and impacting system for breaking down slag while leaving metallic fragments relatively unbroken. US Patent No 2,675,970 describes a material crushing machine including an eccentrically supported rotatable pressure cylinder and a yieldable wall between which material is crushed; the yieldable wall is capable of only very limited movement with respect to the pressure cylinder.

A need thus exists for a system that will permit economic recovery of ferrous and non-ferrous metal, such as aluminium, components from friable, incinerated waste materials including carbonaceous incineration byproducts, such as ash, and associated ferrous and non-ferrous metal components. Such as a system will not only permit the recovery of the salvageable ferrous and non-ferrous metal components from the incinerated waste materials, but also will reduce the amount of the incineration byproduct, e.g., ash, that must be disposed by conventional disposal such as landfill.

The present invention pertains to a system for recovering salvageable ferrous and non-ferrous materials from incinerated waste materials including friable, carbonaceous incineration byproducts such as ash, and associated ferrous metal and aluminum and other non-ferrous metal components comprising first crushing means for selectively comminuting carbonaceous incineration byproducts without comminuting associated ferrous and non-ferrous metal components; first separating means coacting with said first crushing means for selectively separating comminuted carbonaceous incineration byproducts from ferrous and non-ferrous metal components; and first magnetic means for separating ferrous metal components from non-ferrous metal components. In a preferred embodiment, the system further comprises first conveying means for conveying incinerated waste materials to the first selective crushing means and collection stations for collecting separated comminuted carbonaceous incineration byproducts, ferrous metal components and non-ferrous metal components. In a more preferred embodiment, the system further comprises second crushing means for further selectively comminuting carbonaceous incineration byproducts without comminuting associated ferrous and non-ferrous metal components; second separating means coacting with the second crushing means for selectively separating additional comminuted carbonaceous incineration byproducts from ferrous and non-ferrous metal components; second conveying means for conveying comminuted carbonaceous incineration byproducts and ferrous and non-ferrous metal components to the second separating means; third conveying means for conveying ferrous and non-ferrous metal components to said first magnetic means; and second magnetic means for separating ferrous metal components from non-ferrous metal components prior to said first crushing means.

In an even more embodiment, the system further comprises third separating means prior to said first crushing means to separate noncarbonaceous materials other than ferrous and non-ferrous metal components, such as glass, sand and dirt, from the incinerated waste materials and fourth conveying means for conveying unseparated carbonaceous byproducts and ferrous and non-ferrous metal components from the first separating means to the second selective crushing means.

The present invention further relates to a method for recovery of ferrous and non-ferrous metal components from incinerated waste materials using the system of the present invention and to a novel crusher for selectively comminuting friable materials without comminuting associated malleable materials.

Figure 1 is a process schematic diagram of a preferred embodiment of the recovery system of the present invention.

Figure 2 is a plan view of an embodiment of a preferred selective crusher employed in the present invention.

Figure 3 is a cross-sectional view taken through line A-A of the preferred selective crusher of Figure 2.

The present invention is directed to a system for recovering salvageable ferrous and non-ferrous materials from incinerated waste materials including friable carbonaceous incineration byproducts such as ash, and associated ferrous metal and aluminum and other non-ferrous metal components comprising first crushing means for selectively comminuting carbonaceous incineration byproducts without comminuting associated ferrous and non-ferrous metal components; first separating means coacting with said first crushing means for separating comminuted carbonaceous incineration byproducts from ferrous and non-ferrous metal components; and first magnetic means for separating ferrous metal components from non-ferrous metal components.

The feed material processed in the recovery system generally consists of the bottoms or ash material remaining after incineration of waste materials, and preferably the bottoms or ash produced in a furnace in a mass burning operation used to generate electricity. The bottoms product generally includes incinerated carbonaceous byproducts, such as ash, and associated incinerated ferrous and non- ferrous metal components such as aluminum, copper, nickel and brass. The bottoms product may also include glass and other refuse typically contained in municipal refuse that are not completely incinerated at the temperature maintained in the furnace. Although incinerated waste materials are the preferred feed stock of the invention, other feed materials, including ash and ash-related products and non-ferrous and/or ferrous metal components, are also suitable.

Referring to Figure 1, the feed material is delivered to a first crushing means 4 in the recovery system of the invention preferably by a first conveying means 3. The first conveying means 3 may be a belt-type conveyor at an angle from the horizontal, ie troughing angle, of between preferably about 10 and 45 degrees. The system preferably includes a second conveying means 5 that conveys the comminuted carbonaceous incineration byproducts and ferrous and non-ferrous metal components from the first crushing means 4 to a first separating means 6. The second conveying means 5 may again be a belt-type conveyer or any other conventional conveyor similar to the first conveying means 3. The first separating means 6 which separates comminuted carbonaceous incinerations byproducts from ferrous and non-ferrous metal components may be any conventional separator, such as a screen separator, which will separate comminuted carbonaceous byproducts from the associated ferrous and non-ferrous metal components. Preferably, the second conveying means 5 and first separating means 6 is a combination vibrating screen/conveyor such as sold by Bonded Scale and Machine Co. Most preferably, a variable angle vibrating conveyor/screen separator is used in order to regulate the variable flow of the comminuted carbonaceous byproducts and associated ferrous and non-ferrous metal components across the screen/conveyor to enhance separation. The screen angle is preferably between about 10 and 45 degrees, and most preferably between about 3 and 20 degrees, from the horizontal, with the exact angle being selected to maximize the retention time of the material on the screen without overloading the screen. The vibrating screen/conveyor has a plurality of openings, preferably between about 0.95 cm and 3.81 cm (3/8 inch and 1 1/2 inch), most preferably about 1.91 cm (3/4 inch), in diameter, through which a portion of the vibrated ash or other carbonaceous incineration byproduct preferably less than about 1.91 cm to 2.54 cm (3/4 inch to 1 inch) in diameter passes to a collection station position below the vibrating screen/conveyor. The collection station 12 may be any conventional collector apparatus but preferably is a belt conveyor or another collection device which transports the ash or other carbonaceous incineration byproducts to a further collection station from which it is transported to a landfill for disposal.

The first crushing means 4 is a unique crusher which selectively comminutes friable carbonaceous incineration byproducts to a desired particle size without comminuting associated ferrous or non-ferrous metal components. The crusher is preferably a single rotating roll-type crusher 20, such as shown in Figures 2 and 3, having two to six, preferably four, tungsten carbide welds 30 equidistant-spaced longitudinally across the exterior surface of a rotating roll 32 to comminute the carbonaceous incineration byproduct. In juxtaposition to the roll is a generally stationary backing plate 34. The incinerated waste materials are conveyed to the single rotating roll-type crusher 20 where they are delivered to the rotating roll 32. The rotating roll 32 is set a sufficient distance from the backing plate 34 to comminute the carbonaceous incineration byproducts to a diameter of preferably between about 0.95 to 3.81 cm (3/8 to 1 1/2 inches) or less, and most preferably 2.54 cm (1 inch) or less, without comminuting associated ferrous and non-ferrous metal components. The backing plate 34 is maintained in place by coil springs, air pressure cylinders, hydraulic cylinders or other means which serves as a release device, compressing when ferrous or non-ferrous metal components in the incinerated waste materials enter the space between the rotating roll and the backing plate at a pressure sufficient to comminute the carbonaceous incineration byproducts, but insufficient to comminute the associated ferrous and non-ferrous metal components. In a most preferred embodiment, the backing plate 34 is maintained in place by two spaced-apart air-pressure controlled rams 36 attached to the base of the backing plate 34. The rams are maintained under an air pressure of preferably 40 ± 10 psi and release and return to place almost instantly when a ferrous or non-ferrous metallic component enters the space between the rotating roll and the backing plate and is passed. The ability to vary the air pressure is desirable in order to be able to comminute the various carbonaceous incineration byproducts encountered from the same or different incineration processes.

The ferrous and non-ferrous metal components are separated in the claimed system by first magnetic means 11. The first magnetic means 11 may be used in the system prior or subsequent to the first crushing means 4. Preferably, the first magnetic means 11 is used in the system subsequent to the first crushing means 4. The first magnetic means 11 may be any type of magnet which will separate the ferrous metal components, such as iron and steel components, from the non-ferrous metal components, such as aluminum. In a preferred embodiment of the invention, the magnet is a magnetic drum head pulley, such as manufactured by Sterns Magnetics, Inc. or Erie Magnetic, Inc. The ferrous metal components are released from the magnet, and the ferrous and non-ferrous metal components are deposited at one or more collection stations 12. Preferably, the ferrous metal components are deposited at one collection station and the non- ferrous metal components are deposited at another collection station. The salvaged ferrous and non-ferrous metal components may then be sold for the recovered, specific ferrous and non-ferrous metal values.

In a most preferred embodiment of the invention, as illustrated in Figure 1, a second crushing means 8, a second separating means 9 and third separating means 2, a third conveying means 10 and fourth conveying means 7, and a second magnetic means 1 are part of the recovery system. The second crushing means 8 is similar to the first crushing means 4 in that it further selectively comminutes the carbonaceous incineration byproducts to a diameter of preferably between about 0.64 and 3.81 cm (1/4 and 1 1/2 inches) or less, and most preferably 1.27 cm (1/2 inch) or less, without comminuting associated ferrous and non-ferrous metal components. The comminuted ash and associated ferrous and non-ferrous metal components from the second crushing means 8 are conveying by a third conveying means 10 to the first magnetic means 11 for separation of the ferrous metal components from the non-ferrous metal components, such as aluminium. The third conveying means 10 may be again any conventional conveyor system, such as a belt conveyor. The fourth conveying means 7 conveys carbonaceous incineration byproducts with associated ferrous and non-ferrous metal components from the fist separating means 6 to the second crushing means 8. The fourth conveying means 7 may again be any conventional conveyor system, such as a belt conveyor.

The second separating means 9 which separates further comminuted carbonaceous incineration byproducts and associated ferrous and non-ferrous metal components from the second crushing means 8 may again be any conventional separator, such as a screen separator. Most preferably, the third conveying means 10 and second separating means 9 is a combination variable angle vibrating screen/conveyor such as described above of the second conveying means 5 and first separating means 6. Again, the screen angle is preferably between about 10 and 45 degrees, and most preferably between about 13 and 20 degrees, from the horizontal with the exact angle being selected to maximize the retention time of the material on the screen without overloading the screen. Similar to the combination second conveyor/first separator means, the vibrating screen/conveyor of the second separator means/third conveyor means combination has a plurality of openings, preferably between about 0.95 and 3.81 cm (3/8 and 1 1/2 inches), and most preferably about 1.91 cm (3/4 inch), in diameter through which a further portion of the vibrated ash or other comminuted carbonaceous incineration byproduct preferably less than about 1.91 to 2.54 cm (3/4 to 1 inch) in diameter passes to a further collection station positioned below the vibrating screen/conveyor. Preferably, the further collection station is a continuation of the belt conveyor or other collection device transporting the ash or other comminuted carbonaceous incineration byproduct that had passed through the first vibrating screen/conveyor described above.

The second magnetic means 1 is similar to the first magnetic means 11 described previously and is used in the system prior to the first crushing means, and preferably prior to the first conveying means, to separate initially a portion of the ferrous metal components, such as iron and steel components, from the non-ferrous components, such as aluminium components. The use of such second magnetic means reduces the quantity of feed material delivered to the first crushing means and the other parts of the recovery system.

A third separating means 2 prior to the first crushing means 4 is preferably used in the system to separate noncarbonaceous materials other than ferrous and non-ferrous metal components, such as glass, sand and dirt, from the feed material delivered to the first crushing means.