Document 6By75o0Np0JOL2jY1nvxV6zv6

Asbestos Fibres: Production and Usage By M. S. BADOLLET* (Annual General Meeting, Edmonton, April, 1953) (Transaction*, Volume LV1, 1953, pp. 237-239) URING the past five years, grade, and quantities of rock, dust, Dproduction of asbestos fibres and such foreign materials as wood has increased in all countries thaatnd wire. Comparisons are made list asbestos as one of their mineral with standard Canadian grades, or, resources. Despite the many small if the fibre is of some other variety, mines that have been opened in comparison is made with shipments Canada, United States, Mexico, of that grade received during the South America, Italy, South Africa, past five years. If the sample is Australia, Yugoslavia, and Rho only a small quantity, such as a few desia, the supply still does not meet grams, it is placed between two the demand. It is estimated that glass plates and reflected against total 1952 world production of as a white wall, where the lengths may bestos fibres of all varieties ap he measured and the impurities proximated 1,000,000 tons, with counted. When large samples are Canada supplying 966,382 tons (l), available they are given special or 60 per cent of all fibre mined. tests to evaluate the fibres for use Asbestos fibre brokers continu ally are offering odd-lot samples of chrysotile, amosite, crocidolite, tremolite, and anthophyllite fibres to manufacturers, quoting fantastic prices for tonnages varying from just a few to 50 or more in a month. In many cases, the samples are not properly graded and con tain quantities of rock impurities and finely ground dust. When vendors submit samples of in regular products. These special tests include air separation and screening in a pilot plant to deter mine impurities ranging from large -f-4 mesh fragments of rock to --35 mesh granular material. Then the clean fibres as well as the original fibres are combined separately with the necessary ingredients to produce a commercial product. Physical tests on the product furnish further fac tors for evaluating the fibre. asbestos fibres, the manufacturer should consider them in terms of price, quality, quantity, and as pos sible substitutes for fibres current ly used in his products. Grading of these odd-lot fibres in most cases has been poorly done, with resultant non-uniform fibre lengths. In some instances, a num ber of miscellaneous lots of fibres have been blended for sale. This blending produces a fibre that is difficult for the manufacturer to ac cept as a substitute for the well- Should a sample of fibre pass laboratory tests, it is customary to request three to ten tons for a plant test before final approval is given. When the large shipment of fibre arrives it is thoroughly sampled and re-tested, and the data com pared with those of the original sample. If both sets of data are comparable and the plant tests are satisfactory, fibre specifications are drawn up for future purchases of this grade and variety of asbestos. standardized Canadian fibres. In some cases, the quality of the All fibres offered to the pur fibre is so poor that anyone accus chasing departments of most manu tomed to fibre examinations will facturers usually are forwarded to realize that it is worthless before their research units, where they are tests are made. carefully examined for length, The three varieties of asbestos used in large quantities industrially are chrysotile, amosite, and crocido lite. Although actinolite occasional ly appears on the market, no pub lished records show how much is used, and we may consider it of minor importance. Chrysotile Chrysotile asbestos is the most popular variety for industrial pur poses and probably accounts for 90 per cent of all asbestos fibres used in industrial products. The quantity of chrysotile im ported by United States industry in 1952 was approximately 734,500 tons (2), 668,800 tons of which came from Canada. When available, some Rhodesian and Arizona chry sotile fibres are used in textiles, special papers, and asbestos-cement products. Last year the textile in dustry in the United States im ported 26,445 tons (2) of chryso tile fibres, including No. 1 and No. 2 crudes and Group 3 fibres. This amount includes 24,631 tons of spinning fibre from Canada, and 1,824 tons of C.&G. No. 1 and No. 2 from Rhodesia. These fibres usually are re-processed by the consumer and then carded and formed into blankets, rovings, threads, cords, ropes, and yarns of various classifications depending on demand. Asbestos cloths, tapes, wicks, and braided tubing all are made to meet particular specifica tions. Fibres prepared in the textile plant (3) are used in such products as awnings, brake linings, blankets, conveyors, curtains, clothing, gloves, bag filters, draperies, coverings for electrical and power plant equip ment, flexible metal tubings, pack ings, chemical filters, thermal in sulating materials, friction mate rials, clutch facings, gaskets, elec tric blankets, ironing board covers, joint fillers, turbine jackets and blankets, and plastics. The shortage of spinning fibre has resulted in off-grade so-called (2) Bowles, Oliver, U.S. Dept, of Interior, Washington, D.C., private communication. (3) A Primer on Asbestos Textiles, prepared by the Asbestos Textile In stitute, 1946. t offered" to customers. Most of these fibres come from sources other than Canada and often are poorly graded. They sometimes are brittle and contain high percentages of Horn-fibrous ma terials. On several occasions, small sam ples of textile fibres from foreign countries have been submitted and found to be satisfactory in length, strength, and in quantity of such impurities as magnetite, limestone, rock, and dust. An order of a ton of the fibre, however, proved en tirely different and resulted in large card drops because of brittle ness and non-uniformity of fibre length. Brokers submitting samples of textile fibres should get a guaran tee from the miners that shipments of fibres will be equal to samples submitted to prospective customers. For papers and millboards, most manufacturers use fibres of Groups 3 to 6, depending upon the kind of products being made. The longer fibres are used in special papers or diaphragms requiring sufficient length to give reinforcement. The types of paper products manufac tured by a paper mill are numerous and may be mentioned briefly as electrolytic ceil or diaphragm, wick, pipe covering, millboards, roofing papers, laminated roll-board, roof ing felts, pipe line felts, welding paper, and similar materials. Fibres for asbestos-cement prod ucts vary from Groups 1 to 7, in clusive, depending upon the methods of manufacture. This group of prod ucts includes shingles, pipes, jackets, flat sheets, corrugated sheets, wall boards, and electrical panels. Asbestos asphalt roof coatings usually contain fibres of Groups 8 and 7. and floats, depending upon the particular costing., being manu factured. The ui?|jjj_fibat8 was dis cussed in AsbettffijffffiBiitit (4) pre sented at the OtWpi^@<eii(fral Meet ing of the Instj&tfe in January, 1952. In this presentation, many of the physical properties and uses of floats were discussed. The popularity of flour tiles made from organic resins and as bestos fibres has resulted in ex ceedingly large sales. Group 7 fibres used in floor tiles by all lead ing United States manufacturers amounted to approximately 170,000 tons in 1952. Asbestos-cements contain fibres of Groups 6 and 7, as well as floats, the fibre used being governed by the cement. The quantity of fibres used in these products in the United States in 1952 was approximately 30,000 tons. Amosite United States industry imported 18,310 tons of amosite fibres (5) from; South Africa last year. This was approximately 30 per cent of the total African production. Samples of amosites are being offered by many vendors and brokers. In some cases, the same samples appear under different identification numbers. These en velope samples actually are too small for evaluation and many times appear to be of good quality, al though larger samples of the same fibre contain high percentages of rock and are rejected. In many cases-, the fibre length is so short that it falls into the filler classifica tion. When properly processed, this variety of asbestos is bulky and light in density, and frequently is suitable for insulations. Amosite imported into the United States gradually is becoming short er in length and dirtier, and con tains considerable rock. It is neces sary, therefore, for the consumer to reprocess the fibre to remove the non-fibrous material which should have been removed in Africa. This additional processing cost plus loss of the non-fihrous material has raised the cost of this fibre to a point where substitutes will be given consideration. It is not known what kind of control tests are maintained on the production of amosite fibres in Africa, but it is suggested that, whatever they are, they should be reviewed in terms of consumer needs. Amosite is not as strong as chrys olite or crocidolite, nor does it hare the good flexing properties of thesefibres for use in textiles. Occasional samples of amosite, however, possess sufficiently high strength and*-good flexing properties to be useij in textiles, if they were avail able in quantity. Products requiring light weight and not needing high strength can he greatly improved by the use of this variety of asbes tos. Amosite fibres, with or without other varieties of- fibres, will exhibit w and good insulation properties, and/ when properly processed, can be formed into magnesia blocks and pipe coverings of low density and good insulating properties. Amosite, combined with other; fibres and fillers, is used to produce lightweight asbestos-cement walbboards that are attractive, easy , to install, and possess good insulation properties. A most recent instaHfttion of this construction is found in the fireproof walls of the new American ship. United State*. Crocidolite Crocidolite asbestos is found in commercial quantities in South Africa and also in Austria. Small er mines in other countries do not produce much fibre of this variety, Africa produced ii,73i tons of crocidolite last year. United States industry imported about 7,100 tons, including 274r tons of Australian Blue fibre (6). That the quality of crocidolite fibre has decreased during the'j^>ast five years is evidenced by de crease in length and an increase in rock and extreme fines in the form of finely ground ironstone. Many vendors and brokers are offering, samples of crocidolite as odd lots. Some fibres are so short that they' fall into the filler class. If the quality of this variety of- fibre con tinues to decrease, it will be nat- ' ural for customers to investigate substitutes. . ` Because of its physical proper ties, crocidolite lends itself to some special applications that are hot. , practical for chrysotile. For exam ple, this type of fibre has very high tensile strength, has good acid--; resisting properties, will give good porosity when formed into *' fillet mat, and. will filter out smalt p; tides of. dusts, smokes, and sus--; pended particles in gases, ' . Crocidolite can be converted- into textiles with some difficulty but? it does not lend itself to carding and. weaving: as easily as does chryso tile. - Probably its greatest application is in . asbestos-cement products where its properties of strength and increased porosity improve manufactoring processes and boost pro duction rateB. Crocidolite is ex tremely effective in acid-resisting ' gaskets and the so-called service (4) Badollet, M.S., Trans., Voi. LV, 1952, pp. 185-189. (6) Bowles, Oliver, U.S. Dept, of Interior, Washington, D.C., private communication. () Bowles, Oliver, U.S. Dept, of Interior, Washington, D.C., private communication. `