PRODUCTION OF VISCOSE FIBRES

When further harmful substances enter the atmosphere together with hydrogen sulphide, then the number of possible reactions is extended by combinations with primary and secondary pollutants. For example, there are the emissions from plants for the production of viscose fibres, where particularly H2S and CS2 are released into the atmosphere. The following reactions probably occur in the atmosphere ... 

Applied processes and techniques in the production of viscose fibres... 

Additionally to the generic BAT (see Section 13.1), for the production of viscose fibres, the following BAT have to be taken into account. 

Other uses of HCI are legion and range from the purification of fine silica for the ceramics industry, and the refining of oils, fats and waxes, to the manufacture of chloroprene mbbers, PVC plastics, industrial solvents and organic intermediates, the production of viscose rayon yam and staple fibre, and the wet processing of textiles (where hydrochloric acid is used as a sour to neutralize residual alkali and remove metallic and other impurities). 

For synthetic and regenerated fibres, the fibre production (primary spinning) is mainly made by melt spinning (polyester, nylon etc.), dry spinning (elastane etc.) or wet spinning (viscose, lyocell etc.). Lenzing AG has produced carbon footprints of viscose and lyocell fibres and compared these with other fibres (Shen and Patel, 2008 Shen et al., 2010 Terinte et al., 2014 Van der Velden et al., 2014). The production of natural fibres via agriculture or forestry has been studied elsewhere (e.g. Sandin et al., 2013). 

Microlatexes can be used in production of glass fibres, because of their low viscosity and their stability, in the leather industry (finishing), in paints, and so on. 

Taking into account the BAT in Sections 13.1 and 13.10, the following emission and consumption levels are associated with BAT for the production of viscose staple fibres ... 

The problems of monomer recovery, reaction medium viscosity, and control of reaction heat are effectively dealt with by the process design of Montedison Fibre (53). This process produces polymer of exceptionally high density, so although the polymer is stiU swollen with monomer, the medium viscosity remains low because the amount of monomer absorbed in the porous areas of the polymer particles is greatly reduced. The process is carried out in a CSTR with a residence time, such that the product k jd x. Q is greater than or equal to 1. is the initiator decomposition rate constant. This condition controls the autocatalytic nature of the reaction because the catalyst and residence time combination assures that the catalyst is almost totally expended in the reactor. 

Approximately 2.5 million t of viscose process regenerated ceUulose fibers were produced in 1990 (Table 1). Measured by production capacity in 1990, the leading producers of filament yams in 1990 were the Soviet Union state-owned factories (255,000 t capacity) and Akzo Fibres in Europe (100,000 t). The leading producers of staple fiber and tow were Courtaulds with 180,000 t capacity spUt between the UK and North America Formosa Chemicals and Fibres Co. with 150,000 t in Taiwan Tenzing with 125,000 t in Austria, and a 40% stake in South Pacific Viscose s 37,000 t Indonesian plant and Grasim Industries in India (125,000 t). BASF s U.S. capacity of 50,000 t was acquired by Tenzing in 1992. 

Cellulose may be solubilised by treatment with sodium hydroxide and carbon disulfide. It can be regenerated by acidification of the solution. This is the basis of the production of regenerated cellulose fibre, so-called viscose rayon , which is a major textile fibre. The technique is also used for the production of continuous cellulose-derived film, so-called cellophane (from cellulose and diaphane , the latter being French for transparent). 

Long fibre cotton 20-50 mm in length and 0.01-0.04 mm dia., which is the raw material for the textile industry. Waste from this cotton is utilized in the production of certain sorts of high viscosity nitrocellulose, e.g. dynamite nitrocotton. 

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