Glass Manufacturing

GLASS MANUFACTURING, the production of glass and various types of articles made from it. Glass consists of various colorless or colored amorphous alloys, for the most part silicic (less often phosphoric and boric) salts. Lead in the form of PbO is part of potassium-lead glass, which serves for the manufacture of English Baccarat crystal, optical flint glass, and strass (glass for artificial precious stones). PbO is also part of Bohemian crystal and glass tubing. Production process. 1. Preparation of the components used for the manufacture of glass (so-called batch). In the premises of a non-mechanized batching plant, the following is performed: a) grinding of chalk, limestone, and cullet on edge runners that are either open or covered with a suction hood; b) sieving through an open sieve; c) pouring into a trough and manual mixing of all components in the trough, and carrying the batch on stretchers to the glass-blowing shop (gutta) for loading the finished mixture into the furnace. In mechanized batching plants, limestone is crushed in crushers, ground and sieved in machines with cylindrical sieves, and the components are mixed in a drum mixer; storage of both individual components and the batch is carried out in bunkers, and transfer from apparatus to apparatus or into bunkers is performed by augers and elevators. Loading of the batch into the glass-melting furnace is performed with shovels. At mechanized plants in the USSR, a special charging machine with buckets for 500-700 kg of batch is now being introduced. 2. Glass melting is performed either in pot furnaces or in tank furnaces. The furnaces are equipped with generators and have regenerators for utilizing the heat of exhaust gases for the purpose of preheating the air. At the "Dagestanskiye Ogni" plant in Derbent, glass melting is performed by utilizing natural gases. Recently, experiments have also begun with the electric melting of glass. Glass melting is performed at temperatures from 1,200° to 1,500°. Glass-melting furnaces have a number of small openings (up to 36), through which the loading of the batch and the gathering of the molten mass for blowing are performed. With the manual method of producing glass and glass articles, the molten glass mass is gathered through the opening with a blowpipe. Depending on the nature and size of the articles, blowing is performed by a "preparer" (zadelshchik) directly into molds, after which it is passed to a "master" for finishing, or a "semi-parison" (polubanochka) is preliminarily prepared by a "parison-maker" (banochnik) (by light blowing and rolling in special wooden molds). In the second case, after a repeated gathering of the glass mass, the master blows large articles: glass tubing (long glass tubes) or, in the production of window glass, so-called cylinders (khalyavy). The blowing of cylinders is performed at the edge of a special trench while alternately swinging the pipe with the gathered glass in the air. After being cut lengthwise with a diamond, the cylinder is flattened into a sheet in special flattening furnaces, while small objects (bottles, tableware) are subjected to tempering in annealing furnaces. When producing small articles, the weight of the pipe with glass reaches from 1 to 5 kg, and for large articles (window glass) - 18-20 kg. Plate glass is produced by casting: molten glass is poured from a pot delivered by a crane onto a special table with edges, on which the glass mass is rolled by a roller into sheets, which then enter the annealing furnaces. In pre-revolutionary times in Russia, all glass production was carried out exclusively by manual methods. Starting from 1926, a number of mechanized bottle and window glass plants were built in the USSR. For the mechanical blowing of bottles, Lynch machines are used, which have the appearance of two tables connected together, onto which the mass is fed from the furnace through a so-called "feeder" in the form of drops into a two-part mold on the first roughing table, where the neck of the bottle is automatically formed, and then, with the help of air compressed to 3 atmospheres, a parison is blown, which is automatically transferred to the mold of the finishing table, where the finished bottle is blown from it with compressed air, automatically moving along a conveyor into the annealing furnace. In 1913, Fourcault proposed a method for the mechanization of window glass production, which began to be widely applied from 1920 (at the present time, these machines are also manufactured in the USSR). 3. During the finishing of articles, chemical and high-quality glassware are subjected to grinding on machines with a horizontal rotating rod or lapping on horizontally rotating discs using water with sand. In necessary cases, a matte surface is produced either by the action of a sandblasting apparatus or by etching with hydrofluoric acid after preliminary coating with varnish. When graduating chemical glassware, etching with hydrofluoric acid is also used after preliminary coating of the outer surface with wax and marking the divisions. Occupational hazards and health measures. A. Batching. The processes of crushing, grinding, and mixing the batch components are accompanied by significant dust generation: during the crushing of chamotte - 36-84 mg; the highest air dustiness was found during manual mixing - from 230 mg to 1,206-1,366 mg per 1 m³ (Leites and Smirnov), and during manual sieving of the glass mass - up to 1,610 mg. With insufficient sealing of processes in a mechanized batching plant, air dustiness near the mechanical mixer and the pouring from bunkers was found to be 48-63.0 mg (Shifman). This dust contains a significant amount of SiO₂; the dust of saltpeter, soda, and potash possesses a local irritating property due to its chemical properties; the danger of lead and arsenic poisoning exists when preparing the batch for special types of glass, with the process of grinding arsenic on edge runners being the most dangerous. Health measures are reduced to the mechanization and sealing of both the production processes themselves and the transportation of materials and the finished batch, with the installation of local exhaust ventilation (preferably aspiration). The danger of occupational poisoning is eliminated by replacing lead, for example, by using Ca and Mg instead of red lead in the manufacture of glass for electric bulbs (Wittkamp); by using lump arsenic, loaded directly into the furnace, the process of grinding arsenic on edge runners is eliminated. B. Glass-blowing shop (gutta) of mechanized plants. Working conditions in the glass-blowing shop are characterized mainly by: a) unfavorable meteorological conditions (significant radiation and elevated air temperature), strong muscular strain (especially significant during the blowing of large objects and window glass); b) significant strain on the respiratory organs during the manual blowing process, especially of so-called cylinders (window glass); c) danger of infection (syphilis, tuberculosis) when using a common blowpipe. Radiation comes mainly from the openings of the furnace, the walls of the furnace, and from the molten glass. Radiation at the furnace opening reaches 3-4 cal. during the gathering of glass (the hand is exposed to radiation of up to 10 cal. according to data by Leites, Grodskaya, and Dmitriev), at the place of rolling the cylinder - 1.5-2 cal., at the place of blowing - 0.2-0.7-1.0 cal. (at a distance of 3.5 m from the furnace). The masters are subjected to the greatest radiation, followed by the preparers and parison-makers at the moment of gathering glass through the opening of the glass-melting furnace. The air temperature in the glass-blowing shop in the summer exceeds the outside air temperature by 10-12°. In winter, drafts, uneven temperature, and fluctuations in temperature in individual places by 5-10° are noted. Relative humidity is low (in summer 30-40%). A substantial measure improving meteorological working conditions during manual glass blowing is the installation of blowing ventilation in the form of air showers at workplaces. As studies by the Central Institute of Health and Organization of Labor have shown, a good effect of air showers is obtained at an air velocity of 3-4 m per second (at chest level) with a radiation intensity of 3-4 cal. at the moment of gathering glass, 2 cal. at the moment of blowing, and 1 cal. at the moment of molding (parison). Besides the use of air showers, it is necessary to install shields at the furnace openings with devices for lifting them, and to rationalize the work and rest regime (short breaks, water-salt drinking regime, hydro-procedures). During the construction of glass-blowing shop buildings, maximum conditions for aeration of the building (natural ventilation) must be ensured for the purpose of removing excess heat. A radical change in working conditions in the glass-blowing shop is possible only through the mechanization of blowing processes. A sharp predominance of infrared rays from 1.2 to 6 μ in the radiation spectrum of glass-melting furnaces. According to Vogt, a typical occupational disease is glassblower's cataract, the frequency of which among them is determined to be from 10% to 30%. Kraupa (1926) believes that at the age of over 50, cataract in old glassblowers occurs 4 times more often than in the rest of the population of the same age. Wick found cataract in only 19.5% of glassblowers who had interrupted their work during the war for 1-6 years, whereas among those working continuously, cataract was found in 43.9%. In the USSR, authors who examined glassblowers found cataract: Kaplan in 7.9% of glassblowers, Kolen in 1.9%, Samoilov in 10.6% of glassblowers (with 3.3% cataracts among workers in other workshops).

Although a number of authors attached importance to the action of ultraviolet rays in the pathogenesis of cataract, it can now be considered proven that short infrared Vogt rays (up to 1.5 µ) influence the origin of cataract (see). In this connection, it is necessary to use appropriate light filters that protect the eyes from the action of Vogt infrared rays (TIS, special cobalt glasses). The use of a common blowpipe served as a source of a number of cases of occupational syphilis infection, which necessitates periodic medical examination of glassblowers. Neither numbering nor disinfection of the pipes guarantees against syphilis infection when it is necessary for two glassblowers to blow large objects and window glass using a common pipe. The repeatedly proposed mouthpieces have not found application due to the difficulty and delay of the process itself. The introduction of pneumatic blowpipes, which eliminate both the danger of infection and the harmful factors associated with the blowing process, has not become widespread and was only a transitional moment to the full mechanization of the blowing process itself by machine method. Expiratory increased pressure in the lungs during blowing is, according to a number of authors (Lowy, Laennec, Layet, Ekkelov, Feygin, Bulgakov, Vigdorchik, Matusevich, et al.), the cause of the development of emphysema in glassblowers. The increase in lung volume, which initially occurs due to exercise, gives way after a number of years (15-20) to a loss of tissue elasticity, persistent dilation of the alveoli, desolation of vessels, etc. On the other hand, some authors (Leites, Sherel, et al.) express the opinion that blowing does not cause an emphysematous state, but an increase in lung volume, which enhances their functional capacity. It should be noted, however, that Leites cites materials from the examination of glassblowers when blowing only small objects. The frequency of finding cases of emphysema among the examined glassblowers is quite different (Landa - 2.5%, Leites - 7.6%, Feygin - 36.4%, Bulgakov - 37% in window glass production and 26.4% in bottle glass production, Matusevich - 9.6% when blowing small items and 31.8% for window glass blowers). The percentage of emphysema incidence is especially high among glassblowers older than 50 years, e.g., 36.6% for small glass blowers and 50% for large glass blowers (Vigdorchik). It is necessary, however, to keep in mind that emphysematous phenomena may also be connected with pneumoconiosis, i.e., with chalicosis. Matusevich notes that chronic bronchitis, which can also play a role in the development of pulmonary emphysema, occurs in a small number (3%). Among glassblowers, Ekkelov found chronic bronchitis in 6.7%, Landa - 14.8%. According to Matusevich's data, diseases of the upper respiratory tract (chronic pharyngitis) occur in 32% of the examined glassblowers with a predominance of hypertrophic forms. Increased puffing of the cheeks when blowing large objects, window glass can lead to atrophy of the cheek muscles and to dilation of Stensen's duct and the penetration of air into the parotid gland (pneumatocele). Cases of suppuration of the parotid gland as a complication of pneumatocele have been described. A significant number of cases of hernia of the linea alba have been noted among glassblowers (which, according to Ekkelov, account for 50% of all detected hernias). Kolsch and Lederer note the presence of voluminous muscle swellings on the palmar surface of the hands and their typical localization, dilation of the veins of the forearm, inflammation of the tendon sheaths, and contractures of the palm muscles in window glass blowers as a result of heavy strain on the muscle-tendon apparatus of the hands. The use of pipes during blowing causes abrasion of the incisors, especially when blowing window glass (Kolsch and Lederer - 30%). All these harmful factors are completely eliminated by mechanical glass blowing. Radiation in mechanized glassworks is also less than in non-mechanized ones (e.g., at a distance of 0.5 m from the Fourcault channel - 0.8-1.1 cal.). The greatest radiation is during "khalmovka" (cleaning glass and the boat from alkalis), reaching 9 calories. Unfavorable temperature conditions were noted in some mechanized glassworks (the excess over the outside temperature in summer reached 14-15°) due to the unfavorable configuration of the building, which does not ensure proper conditions for natural ventilation, the insufficiency of artificial ventilation, and insufficient insulation of heated surfaces. Among other health measures, it is necessary to note the need for mechanization of window glass cutting and mechanization of its transportation. The mechanization of tubing production, proposed by Korolev, frees the USSR from foreign patents. Labor protection legislation for workers in the glass industry: 1. According to the decree of the People's Commissariat of Labor of 10/XI 1928 No. 613 ("Izvestiya NKT", No. 51-52, 1928), a 6-hour working day is established for glassworks masters and their assistants on continuously operating furnaces AND for workers during glass etching. 2. According to the decree of the People's Commissariat of Labor of the USSR of 24/II 1925 No. 53/325, adolescents (under 18 years old) are not allowed to work on dry glass grinding and glass etching. 3. Additional leave for hazardous conditions, according to the decree of the People's Commissariat of Labor of the USSR of 30/IV 1929 No. 156 ("Izvestiya NKT", No. 20-26), is enjoyed by the following groups of workers: masters and their assistants-finishers, molders, potters, heaters, spreaders, runners, shurali, grinders, cutters, polishers (when working by the dry method), cutters working on a wheel, glass melters, batch mixers and loaders, etchers working with hydrofluoric acid, and etchers in mirror production. 4. Rules for the installation, maintenance, and safety of work in glass factories were issued by the decree of the People's Commissariat of Labor of the USSR of 11/IV 1930 No. 150 and concern all workshops of the factory, both mechanized and non-mechanized, and provide for the isolation of individual processes (e.g., dusty ones in the pottery and batch rooms), mechanization and sealing of a number of dust processes (crushing, stirring, sieving), and the installation of local ventilation. In the glassworks, it is required to install ventilation in the form of air showers, vane fans, exhaust ventilation at the furnaces, natural ventilation in the workshop itself, mechanization of cylinder transport, numbering of pipes, their disinfection, insulation of hot parts of machines, installation of showers, equipment of a rest room, etc.

G. Shifman,

A. Pasternak. 75»