Waste material production references

Secondary metals production may refer to secondary metal extraction or to secondary alloy production. Secondary metal extraction normally extracts one metal from the waste and sells any valuable by-products to other metal extractors or chemical processors. In secondary alloy production, the scrap is blended and refined so as to yield an alloy of the desired chemistry. In both cases it is necessary to deal with various sizes, shapes, and compositions of waste materials and the processing route adopted moreover, the plant where the process is implemented should have sufficient flexibility to handle such widely varying input material. 

Scheme 9.1 shows a generalized sequence of reactions for the oxidation of an alkane, via alcohol, ketone and carboxylic acid, to the completely oxidized products, water and carbon dioxide. The latter are often referred to as combustion products as they are the same as those formed by burning hydrocarbons. These are not normally desirable chemical products unless it is necessary to destroy a toxic, hazardous or otherwise unwanted waste material. Oxidation itself is not difficult to achieve, and is a highly exothermic or even explosive process. Selective oxidation, however, is a much greater challenge, as it is important to stop the sequence at the desired product without proceeding further down the oxidation pathway. 

Tab. 8.5 lists the technical data of machines that are offered by a manufacturer of flat die pellet presses. For ranges of typical equipment characteristics, reference should be made to Tab. 8.3 above. While this type of equipment is also widely used for the production of animal feed, the ability to exert higher forces and the availability of special machine features (not all of which have been mentioned in this section) make these pellet presses amenable to applications that can not normally be handled with the ring die models which were discussed earlier. Of particular interest in this respect are many difficult to handle waste materials that need to be transformed into a relatively large particulate shapes for reuse as secondary raw materials. Fig. 8.65 shows a few examples. 

E. Donefer I would refer this specific question to Dr. Baumgardt, as the work on waste paper was done at his institution. Before his answer, I would like to take this opportunity to make one point in reference to the use of wood products as animal feeds. In dicussing this question with Dr. Stone of the Pulp and Paper Institute, he mentioned that wood pulp is priced at over 100/ton. This type of material is thus immediately ruled out as a potential feedstuff since good quality hay can be purchased at 25- 30/ton and grain com is available at approximately twice that price. Serious consideration must thus be made of the initial cost of potential feedstuffs and their chemical treatments, in relation to the nutritive value and costs of commonly available feeds. Com grain is an ideal feed in the fattening ration of cattle and costs less than some of the potential wood pulp feed products. Certain waste wood products such as bark and sawdust might on the other hand justify improvement procedures because of their low initial cost. ... 

At the mill, usually located close to the mine, the ore is crushed and ground to a fine slurry. Sulfuric acid, in which uranium is soluble, is used to leach the product from the bulk material. The residue, consisting of undissolved solids (waste rock) is referred to as the tailings. This material contains most of the radioactivity including radium and toxic materials such as heavy... 

In many cases, due to side reactions that are suppressed but not eliminated by suitable choice of catalyst and operating conditions, unwanted by-products or waste streams may be produced. The term unwanted by-product refers to a stream that cannot be sold for an overall profit. An example of such a by-product would be the production of a fuel stream In this case, some partial economic credit is obtained from the by-product, but in virtually all cases, this represents an overall loss when conpared with the price of the raw materials used to produce it. An exanple illustrating the cost of purifying a by-product for sale is given in Example 14.1. 

Safe disposal is another concern. Waste solvents need to be collected in proper containers. Contaminated personal protective equipment, clean-up materials, etc. may need to be segregated from the regular trash. Waste materials may need to be treated and disposed of as hazardous waste. Your facility must follow all applicable federal, state, and local environmental rules to safely dispose of solvents. Refer to the product s material safety data sheet for clean-up and disposal information. 

Refuse-Derived Fuel. Many processing faciUties divert a portion of the material that is not recovered for recycling to waste-to-energy plants, also referred to as resource recovery faciUties, where the material is employed as fuel. The processes involved in the production of refuse-derived fuel (RDF) are outlined in Figure 4 (23). Nine different RDFs have been defined, as Hsted in Table 3 (24). There are several ways to prepare RDF-3, which is perhaps the most popular form and is the feed used in the preparation of densified refuse-derived fuel (d-RDF). AH forms of RDF are part of the broader set of waste-derived fuels (WDF), which includes various waste biomass, eg, from silvaculture or agriculture (see Fuels frombiomass Fuels fromwaste). 

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