Material pure scrap

Multiblock Copolymers. Replacement of conventional vulcanized mbber is the main appHcation for the polar polyurethane, polyester, and polyamide block copolymers. Like styrenic block copolymers, they can be molded or extmded using equipment designed for processing thermoplastics. Melt temperatures during processing are between 175 and 225°C, and predrying is requited scrap is reusable. They are mostiy used as essentially pure materials, although some work on blends with various thermoplastics such as plasticized and unplasticized PVC and also ABS and polycarbonate (14,18,67—69) has been reported. Plasticizers intended for use with PVC have also been blended with polyester block copolymers (67). 

Silicon for the chemical industry is usually purified to 98.5% by leaching the powdered 96-97% material with water. Very pure Si for semiconductor applications is obtained either from SiCU (made from the chlorination of scrap Si) or from SiHCls (a byproduct of the silicone industry, p. 338). These volatile compounds are... 

Secondary raw materials recovered from scrap are more concentrated and more pure than primary raw materials. Scrap is already in the metallic form, and requires only purification which, in the most favorable or desirable cases, involves only melting. The recovery of secondary metals can, therefore, be carried out with fewer and simpler operations, consuming a smaller amount of energy and causing less pollution, than primary metals production. For example, the production of 1 ton of copper from ore consumes about 116 GJ of energy, while the consumption is only about 19 G J when the production is from scrap. 

The methanolysis begins with reasonably clean PET scrap to which a catalyst and methanol are added. This mixture is heated under pressure to force the PET to depolym-erize. The end products are ethylene glycol and dimethyl terephthalate (DMT). Pure DMT and ethylene glycol are obtained through reciystallization and distillation, respectively. These pure materials can be used as feedstocks for the synthesis of new polyesters. 

Many types of furnace are available to produce vapor of the required purity from various raw materials and obtain a high yield of zinc. Pure zinc (super high grade, SHG high grade, HG) or, to an increasing extent, metal residues (e.g., scrap zinc,... 

Tungsten in most cases is added to the steel melt as master alloy. The two usual types are ferrotungsten and melting base. Due to their lower melting point, master alloys dissolve and distribute more readily in the steel melt as pure tungsten. Moreover, they are cheaper because they are produced either directly fix)m ore concentrates in case of ferrotungsten or from scrap materials in case of melting base alloys. 

In a pilot project of the Verband der Chemischen Industrie, a facility for disposing of chemical drums was erected in the Hoechst Ruhrchemie plant. After pretreatment, drums with capacities of >120 L are cleaned, dried, and examined for damage and cleanliness. Clean drums are forwarded to recycling. Damaged drums larger than 120 (60) L as well as small containers ( < 120 or 60 L) are ground, washed, and dried. The materials, in the form of pure steel scrap or sorted plastic chips, are then available for recycling [253], [270]. 

Today, 50-80 % of the waste products from production are reused. Metal wastes, the largest contingent, are sold as scrap. The industry is making considerable efforts to recycle reusable waste products into its own, i.e., internal, processes. Nonreusable waste products are in most cases environmentally neutral and can thus be disposed of by way of deposition. In order to utilize existing waste deposit sites for as long as possible, German industry is attempting to reduce waste product volumes and to increase the proportion of reusable, pure-type substances (rubber, plastics, raw materials, etc.). 

As mentioned, one application for recycled commingled plastics is in plastic lumber. The plastic lumber business has grown rapidly in the last five years. Not aU plastic lumber is made using recycled plastics, but much of it is. Some companies using recycled plastics for plastic lumber use mixed plastics, and others use relatively pure streams of material. Some use primarily postconsumer materials, while others use mostly industrial scrap. 

Electrodeposition cells can produce the metal in a number of forms compact metal for re-use or re-sale, powdered or flake metal, or concentrates for recycling. The metal may be produced as an alloy as an alternative to pure metal. The choice of the metal form depends largely on the use or destination of the material. It may be recycled directly within the process operation, or to another process, or reprocessed either in house or sold for refining or scrap. 

Noble metal recovery from scrap can be difficult because of the heterogeneity of the material. Sometimes, it is more difficult to obtain metals in pure form from scrap than from ore. If proper allowances in refining are not made to account for contaminants, products may be obtained that are unsuitable for demanding applications. 

Old scrap (sometimes known as capital scrap) is material which has become available as a result of some product reaching the end of its useful life. It includes worn, broken or obsolete manufactured items which arc discarded and find their way back to lead refiners or fabricators, where they are recycled to produce pure metal or transformed directly into a new... 

---